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英文The road (highway)The road is one kind of linear construction used for travel。

It is made of the roadbed，the road surface, the bridge, the culvert and the tunnel. In addition, it also has the crossing of lines, the protective project and the traffic engineering and the route facility。

The roadbed is the base of road surface, road shoulder，side slope, side ditch foundations. It is stone material structure, which is designed according to route's plane position .The roadbed, as the base of travel, must guarantee that it has the enough intensity and the stability that can prevent the water and other natural disaster from corroding.The road surface is the surface of road. It is single or complex structure built with mixture。

The road surface require being smooth，having enough intensity，good stability and anti—slippery function. The quality of road surface directly affects the safe, comfort and the traffic。

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A Design and Implementation of Active NetworkSocket ProgrammingK.L. Eddie Law, Roy LeungThe Edward S. Rogers Sr. Department of Electrical and Computer EngineeringUniversity of TorontoToronto, Canadaeddie@, roy.leung@utoronto.caAbstract—The concept of programmable nodes and active networks introduces programmability into communication networks. Code and data can be sent and modified on their ways to destinations. Recently, various research groups have designed and implemented their own design platforms. Each design has its own benefits and drawbacks. Moreover, there exists an interoperability problem among platforms. As a result, we introduce a concept that is similar to the network socket programming. We intentionally establish a set of simple interfaces for programming active applications. This set of interfaces, known as Active Network Socket Programming (ANSP), will be working on top of all other execution environments in future. Therefore, the ANSP offers a concept that is similar to “write once, run everywhere.” It is an open programming model that active applications can work on all execution environments. It solves the heterogeneity within active networks. This is especially useful when active applications need to access all regions within a heterogeneous network to deploy special service at critical points or to monitor the performance of the entire networks. Instead of introducing a new platform, our approach provides a thin, transparent layer on top of existing environments that can be easily installed for all active applications.Keywords-active networks; application programming interface; active network socket programming;I. I NTRODUCTIONIn 1990, Clark and Tennenhouse [1] proposed a design framework for introducing new network protocols for the Internet. Since the publication of that position paper, active network design framework [2, 3, 10] has slowly taken shape in the late 1990s. The active network paradigm allows program code and data to be delivered simultaneously on the Internet. Moreover, they may get executed and modified on their ways to their destinations. At the moment, there is a global active network backbone, the ABone, for experiments on active networks. Apart from the immaturity of the executing platform, the primary hindrance on the deployment of active networks on the Internet is more on the commercially related issues. For example, a vendor may hesitate to allow network routers to run some unknown programs that may affect their expected routing performance. As a result, alternatives were proposed to allow active network concept to operate on the Internet, such as the application layer active networking (ALAN) project [4] from the European research community. In the ALAN project, there are active server systems located at different places in the networks and active applications are allowed to run in these servers at the application layer. Another potential approach from the network service provider is to offer active network service as the premium service class in the networks. This service class should provide the best Quality of Service (QoS), and allow the access of computing facility in routers. With this approach, the network service providers can create a new source of income.The research in active networks has been progressing steadily. Since active networks introduce programmability on the Internet, appropriate executing platforms for the active applications to execute should be established. These operating platforms are known as execution environments (EEs) and a few of them have been created, e.g., the Active Signaling Protocol (ASP) [12] and the Active Network Transport System (ANTS) [11]. Hence, different active applications can be implemented to test the active networking concept.With these EEs, some experiments have been carried out to examine the active network concept, for example, the mobile networks [5], web proxies [6], and multicast routers [7]. Active networks introduce a lot of program flexibility and extensibility in networks. Several research groups have proposed various designs of execution environments to offer network computation within routers. Their performance and potential benefits to existing infrastructure are being evaluated [8, 9]. Unfortunately, they seldom concern the interoperability problems when the active networks consist of multiple execution environments. For example, there are three EEs in ABone. Active applications written for one particular EE cannot be operated on other platforms. This introduces another problem of resources partitioning for different EEs to operate. Moreover, there are always some critical network applications that need to run under all network routers, such as collecting information and deploying service at critical points to monitor the networks.In this paper, a framework known as Active Network Socket Programming (ANSP) model is proposed to work with all EEs. It offers the following primary objectives.• One single programming interface is introduced for writing active applications.• Since ANSP offers the programming interface, the design of EE can be made independent of the ANSP.This enables a transparency in developing andenhancing future execution environments.• ANSP addresses the interoperability issues among different execution environments.• Through the design of ANSP, the pros and cons of different EEs will be gained. This may help design abetter EE with improved performance in future.The primary objective of the ANSP is to enable all active applications that are written in ANSP can operate in the ABone testbed . While the proposed ANSP framework is essential in unifying the network environments, we believe that the availability of different environments is beneficial in the development of a better execution environment in future. ANSP is not intended to replace all existing environments, but to enable the studies of new network services which are orthogonal to the designs of execution environments. Therefore, ANSP is designed to be a thin and transparent layer on top of all execution environments. Currently, its deployment relies on automatic code loading with the underlying environments. As a result, the deployment of ANSP at a router is optional and does not require any change to the execution environments.II. D ESIGN I SSUES ON ANSPThe ANSP unifies existing programming interfaces among all EEs. Conceptually, the design of ANSP is similar to the middleware design that offers proper translation mechanisms to different EEs. The provisioning of a unified interface is only one part of the whole ANSP platform. There are many other issues that need to be considered. Apart from translating a set of programming interfaces to other executable calls in different EEs, there are other design issues that should be covered, e.g., • a unified thread library handles thread operations regardless of the thread libraries used in the EEs;• a global soft-store allows information sharing among capsules that may execute over different environmentsat a given router;• a unified addressing scheme used across different environments; more importantly, a routing informationexchange mechanism should be designed across EEs toobtain a global view of the unified networks;• a programming model that should be independent to any programming languages in active networks;• and finally, a translation mechanism to hide the heterogeneity of capsule header structures.A. Heterogeneity in programming modelEach execution environment provides various abstractions for its services and resources in the form of program calls. The model consists of a set of well-defined components, each of them has its own programming interfaces. For the abstractions, capsule-based programming model [10] is the most popular design in active networks. It is used in ANTS [11] and ASP [12], and they are being supported in ABone. Although they are developed based on the same capsule model, their respective components and interfaces are different. Therefore, programs written in one EE cannot run in anther EE. The conceptual views of the programming models in ANTS and ASP are shown in Figure 1.There are three distinct components in ANTS: application, capsule, and execution environment. There exist user interfaces for the active applications at only the source and destination routers. Then the users can specify their customized actions to the networks. According to the program function, the applications send one or more capsules to carry out the operations. Both applications and capsules operate on top of an execution environment that exports an interface to its internal programming resources. Capsule executes its program at each router it has visited. When it arrives at its destination, the application at destination may either reply it with another capsule or presents this arrival event to the user. One drawback with ANTS is that it only allows “bootstrap” application.Figure 1. Programming Models in ASP and ANTS.In contrast, ASP does not limit its users to run “bootstrap” applications. Its program interfaces are different from ANTS, but there are also has three components in ASP: application client, environment, and AAContext. The application client can run on active or non-active host. It can start an active application by simply sending a request message to the EE. The client presents information to users and allows its users to trigger actions at a nearby active router. AAContext is the core of the network service and its specification is divided into two parts. One part specifies its actions at its source and destination routers. Its role is similar to that of the application in ANTS, except that it does not provide a direct interface with the user. The other part defines its actions when it runs inside the active networks and it is similar to the functional behaviors of a capsule in ANTS.In order to deal with the heterogeneity of these two models, ANSP needs to introduce a new set of programming interfaces and map its interfaces and execution model to those within the routers’ EEs.B. Unified Thread LibraryEach execution environment must ensure the isolation of instance executions, so they do not affect each other or accessThe authors appreciate the Nortel Institute for Telecommunications (NIT) at the University of Toronto to allow them to access the computing facilitiesothers’ information. There are various ways to enforce the access control. One simple way is to have one virtual machine for one instance of active applications. This relies on the security design in the virtual machines to isolate services. ANTS is one example that is using this method. Nevertheless, the use of multiple virtual machines requires relatively large amount of resources and may be inefficient in some cases. Therefore, certain environments, such as ASP, allow network services to run within a virtual machine but restrict the use of their services to a limited set of libraries in their packages. For instance, ASP provides its thread library to enforce access control. Because of the differences in these types of thread mechanism, ANSP devises a new thread library to allow uniform accesses to different thread mechanisms.C. Soft-StoreSoft-store allows capsule to insert and retrieve information at a router, thus allowing more than one capsules to exchange information within a network. However, problem arises when a network service can execute under different environments within a router. The problem occurs especially when a network service inserts its soft-store information in one environment and retrieves its data at a later time in another environment at the same router. Due to the fact that execution environments are not allowed to exchange information, the network service cannot retrieve its previous data. Therefore, our ANSP framework needs to take into account of this problem and provides soft-store mechanism that allows universal access of its data at each router.D. Global View of a Unified NetworkWhen an active application is written with ANSP, it can execute on different environment seamlessly. The previously smaller and partitioned networks based on different EEs can now be merging into one large active network. It is then necessary to advise the network topology across the networks. However, different execution environments have different addressing schemes and proprietary routing protocols. In order to merge these partitions together, ANSP must provide a new unified addressing scheme. This new scheme should be interpretable by any environments through appropriate translations with the ANSP. Upon defining the new addressing scheme, a new routing protocol should be designed to operate among environments to exchange topology information. This allows each environment in a network to have a complete view of its network topology.E. Language-Independent ModelExecution environment can be programmed in any programming language. One of the most commonly used languages is Java [13] due to its dynamic code loading capability. In fact, both ANTS and ASP are developed in Java. Nevertheless, the active network architecture shown in Figure 2 does not restrict the use of additional environments that are developed in other languages. For instance, the active network daemon, anted, in Abone provides a workspace to execute multiple execution environments within a router. PLAN, for example, is implemented in Ocaml that will be deployable on ABone in future. Although the current active network is designed to deploy multiple environments that can be in any programming languages, there lacks the tool to allow active applications to run seamlessly upon these environments. Hence, one of the issues that ANSP needs to address is to design a programming model that can work with different programming languages. Although our current prototype only considers ANTS and ASP in its design, PLAN will be the next target to address the programming language issue and to improve the design of ANSP.Figure 2. ANSP Framework Model.F. Heterogeneity of Capsule Header StructureThe structures of the capsule headers are different in different EEs. They carries capsule-related information, for example, the capsule types, sources and destinations. This information is important when certain decision needs to be made within its target environment. A unified model should allow its program code to be executed on different environments. However, the capsule header prevents different environments to interpret its information successfully. Therefore, ANSP should carry out appropriate translation to the header information before the target environment receives this capsule.III. ANSP P ROGRAMMING M ODELWe have outlined the design issues encountered with the ANSP. In the following, the design of the programming model in ANSP will be discussed. This proposed framework provides a set of unified programming interfaces that allows active applications to work on all execution environments. The framework is shown in Figure 2. It is composed of two layers integrated within the active network architecture. These two layers can operate independently without the other layer. The upper layer provides a unified programming model to active applications. The lower layer provides appropriate translation procedure to the ANSP applications when it is processed by different environments. This service is necessary because each environment has its own header definition.The ANSP framework provides a set of programming calls which are abstractions of ANSP services and resources. A capsule-based model is used for ANSP, and it is currently extended to map to other capsule-based models used in ANTSand ASP. The mapping possibility to other models remains as our future works. Hence, the mapping technique in ANSP allows any ANSP applications to access the same programming resources in different environments through a single set of interfaces. The mapping has to be done in a consistent and transparent manner. Therefore, the ANSP appears as an execution environment that provides a complete set of functionalities to active applications. While in fact, it is an overlay structure that makes use of the services provided from the underlying environments. In the following, the high-level functional descriptions of the ANSP model are described. Then, the implementations will be discussed. The ANSP programming model is based upon the interactions between four components: application client , application stub , capsule , and active service base.Figure 3. Information Flow with the ANSP.•Application Client : In a typical scenario, an active application requires some means to present information to its users, e.g., the state of the networks. A graphical user interface (GUI) is designed to operate with the application client if the ANSP runs on a non-active host.•Application Stub : When an application starts, it activates the application client to create a new instance of application stub at its near-by active node. There are two responsibilities for the application stub. One of them is to receive users’ instructions from the application client. Another one is to receive incoming capsules from networks and to perform appropriate actions. Typically, there are two types of actions, thatare, to reply or relay in capsules through the networks, or to notify the users regarding the incoming capsule. •Capsule : An active application may contain several capsule types. Each of them carries program code (also referred to as forwarding routine). Since the application defines a protocol to specify the interactions among capsules as well as the application stubs. Every capsule executes its forwarding routine at each router it visits along the path between the source and destination.•Active Service Base : An active service base is designed to export routers’ environments’ services and execute program calls from application stubs and capsules from different EEs. The base is loaded automatically at each router whenever a capsule arrives.The interactions among components within ANSP are shown in Figure 3. The designs of some key components in the ANSP will be discussed in the following subsections. A. Capsule (ANSPCapsule)ANSPXdr decode () ANSPXdr encode () int length ()Boolean execute ()New types of capsule are created by extending the abstract class ANSPCapsule . New extensions are required to define their own forwarding routines as well as their serialization procedures. These methods are indicated below:The execution of a capsule in ANSP is listed below. It is similar to the process in ANTS.1. A capsule is in serial binary representation before it issent to the network. When an active router receives a byte sequence, it invokes decode() to convert the sequence into a capsule. 2. The router invokes the forwarding routine of thecapsule, execute(). 3. When the capsule has finished its job and forwardsitself to its next hop by calling send(), this call implicitly invokes encode() to convert the capsule into a new serial byte representation. length() isused inside the call of encode() to determine the length of the resulting byte sequence. ANSP provides a XDR library called ANSPXdr to ease the jobs of encoding and decoding.B. Active Service Base (ANSPBase)In an active node, the Active Service Base provides a unified interface to export the available resources in EEs for the rest of the ANSP components. The services may include thread management, node query, and soft-store operation, as shown in Table 1.TABLE I. ACTIVE SERVICE BASE FUNCTION CALLSFunction Definition Descriptionboolean send (Capsule, Address) Transmit a capsule towards its destination using the routing table of theunderlying environment.ANSPAddress getLocalHost () Return address of the local host as an ANSPAddress structure. This isuseful when a capsule wants to check its current location.boolean isLocal (ANSPAddress) Return true if its input argument matches the local host’s address andreturn false otherwise.createThread () Create a new thread that is a class ofANSPThreadInterface (discussed later in Section VIA “Unified Thread Abstraction”).putSStore (key, Object) Object getSStore (key) removeSStore (key)The soft-store operations are provided by putSStore(), getSSTore(), and removeSStore(), and they put, retrieve, and remove data respectively. forName (PathName) Supported in ANSP to retrieve a classobject corresponding to the given path name in its argument. This code retrieval may rely on the code loading mechanism in the environment whennecessary.C. Application Client (ANSPClient)boolean start (args[])boolean start (args[],runningEEs) boolean start (args[],startClient)boolean start (args[],startClient, runningEE)Application Client is an interface between users and the nearby active source router. It does the following responsibilities.1. Code registration: It may be necessary to specify thelocation and name of the application code in some execution environments, e.g., ANTS. 2. Application initialization: It includes selecting anexecution environment to execute the application among those are available at the source router. Each active application can create an application client instance by extending the abstract class, ANSPClient . The extension inherits a method, start(), to automatically handle both the registration and initialization processes. All overloaded versions of start() accept a list of arguments, args , that are passed to the application stub during its initialization. An optional argument called runningEEs allows an application client to select a particular set of environment variables, specified by a list of standardized numerical environment ID, the ANEP ID, to perform code registration. If this argument is not specified, the default setting can only include ANTS and ASP. D. Application Stub (ANSPApplication)receive (ANSPCapsule)Application stubs reside at the source and destination routers to initialize the ANSP application after the application clients complete the initialization and registration processes. It is responsible for receiving and serving capsules from the networks as well as actions requested from the clients. A new instance is created by extending the application client abstract class, ANSPApplication . This extension includes the definition of a handling routine called receive(), which is invoked when a stub receives a new capsule.IV. ANSP E XAMPLE : T RACE -R OUTEA testbed has been created to verify the design correctnessof ANSP in heterogeneous environments. There are three types of router setting on this testbed:1. Router that contains ANTS and a ANSP daemonrunning on behalf of ASP; 2. Router that contains ASP and a ANSP daemon thatruns on behalf of ANTS; 3. Router that contains both ASP and ANTS.The prototype is written in Java [11] with a traceroute testing program. The program records the execution environments of all intermediate routers that it has visited between the source and destination. It also measures the RTT between them. Figure 4 shows the GUI from the application client, and it finds three execution environments along the path: ASP, ANTS, and ASP. The execution sequence of the traceroute program is shown in Figure 5.Figure 4. The GUI for the TRACEROUTE Program.The TraceCapsule program code is created byextending the ANSPCapsule abstract class. When execute() starts, it checks the Boolean value of returning to determine if it is returning from the destination. It is set to true if TraceCapsule is traveling back to the source router; otherwise it is false . When traveling towards the destination, TraceCapsule keeps track of the environments and addresses of the routers it has visited in two arrays, path and trace , respectively. When it arrives at a new router, it calls addHop() to append the router address and its environment to these two arrays. When it finally arrives at the destination, it sets returning to false and forwards itself back to the source by calling send().When it returns to source, it invokes deliverToApp() to deliver itself to the application stub that has been running at the source. TraceCapsule carries information in its data field through the networks by executing encode() and decode(), which encapsulates and de-capsulates its data using External Data Representation (XDR) respectively. The syntax of ANSP XDR follows the syntax of XDR library from ANTS. length() in TraceCapsule returns the data length, or it can be calculated by using the primitive types in the XDRlibrary.Figure 5. Flow of the TRACEROUTE Capsules.V. C ONCLUSIONSIn this paper, we present a new unified layered architecture for active networks. The new model is known as Active Network Socket Programming (ANSP). It allows each active application to be written once and run on multiple environments in active networks. Our experiments successfully verify the design of ANSP architecture, and it has been successfully deployed to work harmoniously with ANTS and ASP without making any changes to their architectures. In fact, the unified programming interface layer is light-weighted and can be dynamically deployable upon request.R EFERENCES[1] D.D. Clark, D.L. Tennenhouse, “Architectural Considerations for a NewGeneration of Protocols,” in Proc. ACM Sigcomm’90, pp.200-208, 1990. [2] D. Tennenhouse, J. M. Smith, W. D. Sicoskie, D. J. Wetherall, and G. J.Minden, “A survey of active network research,” IEEE Communications Magazine , pp. 80-86, Jan 1997.[3] D. Wetherall, U. Legedza, and J. Guttag, “Introducing new internetservices: Why and how,” IEEE Network Magazine, July/August 1998. [4] M. Fry, A. Ghosh, “Application Layer Active Networking,” in ComputerNetworks , Vol.31, No.7, pp.655-667, 1999.[5] K. W. Chin, “An Investigation into The Application of Active Networksto Mobile Computing Environments”, Curtin University of Technology, March 2000.[6] S. Bhattacharjee, K. L. Calvert, and E. W. Zegura, “Self OrganizingWide-Area Network Caches”, Proc. IEEE INFOCOM ’98, San Francisco, CA, 29 March-2 April 1998.[7] L. H. Leman, S. J. Garland, and D. L. Tennenhouse, “Active ReliableMulticast”, Proc. IEEE INFOCOM ’98, San Francisco, CA, 29 March-2 April 1998.[8] D. Descasper, G. Parulkar, B. Plattner, “A Scalable, High PerformanceActive Network Node”, In IEEE Network, January/February 1999.[9] E. L. Nygren, S. J. Garland, and M. F. Kaashoek, “PAN: a high-performance active network node supporting multiple mobile code system”, In the Proceedings of the 2nd IEEE Conference on Open Architectures and Network Programming (OpenArch ’99), March 1999. [10] D. L. Tennenhouse, and D. J. Wetherall. “Towards an Active NetworkArchitecture”, In Proceeding of Multimedia Computing and Networking , January 1996.[11] D. J. Wetherall, J. V. Guttag, D. L. Tennenhouse, “ANTS: A toolkit forBuilding and Dynamically Deploying Network Protocols”, Open Architectures and Network Programming, 1998 IEEE , 1998 , Page(s): 117 –129.[12] B. Braden, A. Cerpa, T. Faber, B. Lindell, G. Phillips, and J. Kann.“Introduction to the ASP Execution Environment”: /active-signal/ARP/index.html .[13] “The java language: A white paper,” Tech. Rep., Sun Microsystems,1998.。

3桂电毕设英文翻译原文

毕业设计(论文)英文翻译原文院（系）：成人教育学院专业：工商企业管理学生姓名：周杨学号： 030113300433指导教师：王蕴老师职称：教授2014年10月12 日The Changing Pattern of Pay and BenefitsTudor, Thomas R, Trumble, Robert R Journal of Compensation & Benefits/May/2008Today, many companies still base their reward systems on the 1950s compensation mode l made popular during the brief period when U.S. companies dominated the world. With today s increasingly competitive environment, however, companies must look more closely at the co st-benefit of rewards, instead of just using them in an attempt to reduce employee dissatisfacti on. Companies must provide short-term motivation and encourage employees to develop long -term skills that will aid the company. Most importantly, companies must also attract and retai n high performers, instead of alienating them with pay systems that give everyone pay increas es without regard to levels of performance. For example, such new compensation approaches may include skill-based pay, gainsharing plans, and flexible benefits systems.Traditional compensation approaches are still often modeled on the centralization-based organizational model, in which decisions were made at the top and management rigidly define d tasks. However, with global competition becoming an increasingly prominent issue, compan ies need reward systems that match their movement to decentralized structures. Larger numbe rs of companies are also becoming very aware that they cannot just pass additional compensat ion costs onto future customers. Today, our pay systems must move in step with the participati ve-management trend by becoming more flexible instead of remaining fixed. This adjustment involves many factors including shorter product life cycles, a need to be more flexible, a need for workers to continually gain additional skills, and for them to think more on the job.In today's most successful companies, employee rewards and benefits are increasingly in corporated into an organization's strategic planning. Why? The rationale is that employee com pensation has a substantial impact on the long-term financial position of a firm. Compensation structures should consider an organization's strategic requirements and should match organiza tional goals. Compensation strategic planning should involve:consideration of the internal and external environment; and creation of an organization's compensation statement, compensatio n goals, and the development of compensation policies.Today, one strategic compensation trend is the use of pay incentives instead of the traditi onal, annual “everybody gets” pay increase. The rationale is to control costs and to more close ly tie performance to compensation. We can group the changing pattern of compensation into two general areas: Pay Method Trends and Benefits Trends. Human Resources managers shou ld familiarize themselves with these changing trends and determine the plan that is most suita ble for their organization.PAY METHOD TRENDSThere are a number of pay methods available for use by employers, including general pa y increases, cost-of-living increases, merit pay, bonuses, skill-based pay, competence-based pa y, CEO compensation, gainsharing, and various types of incentive pay.General Pay IncreaseA general pay increase is a pay increase given to everyone in a company. It can be a lum p-sum payment, but it is more likely to be a percentage increase in base salary. The employer' s rationale for the pay increase may have been the result of a market survey, job evaluation, or just a profitable year. The trend, however, is for general increases to decline as pay-for-perfor mance systems become increasingly dominant. In addition, giving everyone the same raise so metimes decreases morale because high-performing employees see poor performers getting th e same reward.Cost-of-Living IncreaseCost-of-living increases are general pay increases triggered by a rise in an inflation-sensi tive index, such as the consumer price index or the producer price index. As with general pay increases, the use of cost-of-living pay increases is decreasing among companies. The rational e for this decrease is that with lower inflation (thus little change in prices), incomes are more s table and the need for inflation adjustments is not as great as it was in the past. In addition, col lective bargaining agreements are now less likely to include provisions for cost-of-living incre ases, so nonunion firms are not under as much pressure to provide them in an attempt to matc h union-negotiated compensation. Their decline can also be attributed to the fact that employe rs are moving away from pay systems that are nonperformance related.Merit PayMerit pay is another generic term in which pay incentives are given for overall job perfor mance.² Some problems frequently encountered with merit pay plans include: the use of subjective criteria when measuring employee performance;a lack of uniform standards for rating individual employees;differences among managers in how to make individual ratings.Merit pay was the first attempt by firms to create a pay-for-performance system. Howeve r, due to employer (and employee) dissatisfaction with merit pay plans, the trend is to eliminat e them and instead use pay-for-performance plans that are more objective (such as bonus plan s), and that use specific performance measuring criteria that aid in the performance appraisal p rocess.³ This trend includes both the private and public sectors, because the merit pay system i n the federal sector has also been inadequate.BonusA bonus is a generic term involving a type of pay-for-performance plan. Managers can give a bonus for individual or group performance, and for meeting objectives such as MBO (ma nagement by objectives). Researchers and practitioners have given these plans high marks for motivating employees, for creating loyalty, and for meeting performance objectives. In additio n, bonuses reduce the turnover of high-performing employees and increase the turnover of lo w performers, who do not get bonuses. If the bonus system is well-designed, they also create i nternal equity. As such, bonus systems (pay-for-performance) are the current trend in compens ation.Skill-Based PaySkill-based pay emphasizes a company's desire to increase the skills and knowledge of it s workforce. It may involve classes, voluntary job rotation, or tests. Its benefits are many, incl uding having trained people available to do a job if someone is absent. Skill-based pay also w orks well with quality circles because:it provides employees with a better understanding of the jobs their coworkers perform;it reduces resistance to restructuring or other needed changes;it leads to a more flexibleworkforce that can better adapt to new technologies or processes; and it encourages a lea rning environment.It does, however, require a large investment in training which can be expen sive.Competence-Based PayCompetence-based pay (the grid system) is very new and does vary from plan-to-plan. T he idea is not only to reward employees for how well they do a job, but for how they do the jo b. For example, a competence-based pay plan can be used to persuade workers to use the com puters that are sitting on their desks, or to adapt to other changes that come along. The rational e behind a competence-based pay plan is to keep employee skills current.CEO CompensationThe compensation of CEOs (and other top executives) has also been changing, and now inclu des more pay incentives—such as stock options—to better link performance with compensati on. Plans linking executive pay with performance may include stock options, cash bonuses, p hantom stock, or deferred compensation, all of which are ways of making top management m ore accountable for company performance. Today, performance considerations are a larger par t of executive compensation. The Securities and Exchange Commission also requires corporat ions to explain the rationale behind their executive compensation programs to shareholders.GainsharingGainsharing is a pay-for-performance plan in which “gains” are shared with employees f or improvements in profitability or productivity.Gainsharing plans are designed to create a partnership with employees so that both management and labor are working toward the same goa ls and that both groups are benefiting from the results. Gainsharing is a growing trend, and it f its well with other trends, such as participatory management, worker empowerment, and team work. It is also being used in many service businesses, such as banking and insurance. Gainsh aring encourages employee involvement and acceptance of change, and aligns employee goals with company goals.Five Types of Pay IncentivesWhile all pay incentives can be generically coined as “gainsharing,” we will briefly ment ion five types:1. ESOPs. Employee Stock Ownership Plans allow the sharing of gains through dividends and any increase in the value of company stock. ESOPs do create ownership in the company for e mployees that may result in additional motivation, but they do not necessarily have a participa tive-management component.2. Profit-Sharing Plans. Profit-sharing plans allow employees to share in the revenue they hel ped generate. This sharing can be either deferred or immediate. Some observers argue that ass ociating rewards and performance is difficult if managers only give rewards annually, and that perhaps employees should not share in the profits because they do not share in the risks. How ever, companies such as Lincoln Electric and Ford feel that profit sharing is a strong inducem ent to increase performance. The current rate of growth of these plans is significant. For best motivational results, companies should use a system that is based on some criteria that emplo yees understand, instead of just an arbitrary amount. The advantage of profitsharing plans is t hat employers do not have to pay a large sum of money if the profit target is not met.3. Scanlon Plans. Scanlon plans allow employees to share in any savings in labor cost (using a ratio) that is due to their increased performance. The rationale for ScanIon plans is to help em ployees identify with and participate in the company. Employees participating in such plans m ay have access to suggestion programs, brainstorming sessions, or committees to solve produc tion problems. The employer and the employees then share in the savings that result.4. Rucker Plans. Rucker plans allow employees to share in any improvement in the ratio of e mployee costs to the valued added in manufacturing. This is the most complex gainsharing pla n, because it deals with four variables: labor costs, sales value of production (changes in equip ment, or work methods, for example), purchases of outside services such as subcontracting, or utilities, and purchases of outside materials, involving “inventory, theft, and so on”. Rucker p lans are designed to give employees a stake in areas such as reducing labor costs, using raw m aterials, and outsourcing decisions. As such, everyone shares in the savings.5. Improshare Pl ans. Improshare plans allow employees to share in productivity gains that occur because of their efforts.[sup5] Following the Improshare approach, managers give bonuses when the actual hours for a specific amount of productivity are less than the standard that they created using a formula. The savings are split between the company and the workers, in a ratio such as 50⁄50.CHANGES IN BENEFIT PLANSChanges in benefit plans have occurred as a result of efforts to keep up with trends, to co ntain costs, and to meet government regulations. Employees often view benefits as an entitle ment, and their cost—which has steadily increased—now averages 36 percent of total wages. The trend is to get the most out of benefits, while keeping costs down. For example, employer s do not want to pay for any overlap of coverage, or to pay too much for coverage. As their co sts continue to go up, employers are now starting to question how much employees value their benefits. For example:Do they support recruitment, motivate, and retain good employees? Do they support the strategic mission of the firm?Do proposed benefits support the company's retention goals and the demographics of pot ential recruits?Do they support the company culture or the culture the company now wants to promote?A movement now exists among employers for measuring benefit results and continuously eval uating benefits. A focus on Total Quality Management makes the internal employee the custo mer of HR departments who have the product of “benefits.” HR departments want to satisfy t he customer, but are also benchmarking and quantifying each benefit. The strategic trend is to design benefits to make it easier to realize the corporate mission and to enhance the value of t he benefits offered. Another major trend is offering flexible benefits where employees make b enefit decisions to fit their lifestyles. 401(k) PlansToday, 401 (k) plans are popular retirement vehicles because contributions are made on b efore-tax basis and investment earnings are tax deferred. They also address the trend of more mobile employees, who do not stay with a company for their entire working lives. With 401 ( k) plans, employee accounts can be transferred to another company's plan or to an Individual Retirement Account. A company can also establish 401(k) plans without providing for employ er matching contributions, so the only employer cost is for plan administration.Managed Care PlansManaged care plans, such as Preferred Provider Organizations (PPOs) and Health Mainte nance Organizations (HMOs), are a growing benefit trend away from traditional medical insur ance. These plans often include preventive maintenance features that attempt to treat illnesses earlier to avoid higher costs. Although they have disadvantages, they are designed to save ben efit expenses. And, due to the of rising cost of health care, companies can no longer afford towrite a blank check to cover their employees' health care costs. So, they are requiring employ ees to pick up a portion of these costs by shifting more of the premium burden to employees, and⁄or increasing deductibles.Prepaid Legal ServicesPrepaid legal services are new plans in which legal expenses are paid before the services are used. The growing number of lawsuits in this country has sparked demand for this type of benefit. A company may offer this benefit if it wants to protect its employees from the threat o f litigation, so that their minds are on their work. Or, it may offer this benefit to keep up with i ts competitors who are offering such plans. At this point, it is too early to tell how popular pre paid legal services plans will be in the future, though it is possible that they will be offered as a flexible benefit option.Dependent-Care AssistanceDependent-care assistance is also a new benefit whose popularity is growing. Companies are beginning to recognize that in todays economy, both parents often work and that many wo rkers are raising children in single-parent households. This benefit can help attract employees and reduce turnover because parents do not like to make changes if their child-care provider s atisfies them. In addition to caring for children, many employees are responsible for the care o f elderly parents or other relatives. Eldercare is a benefit that addresses this need, and allows e mployees to stay focused on work instead of worrying about their parents. Dependent care ass istance is likely to be increasingly offered as an option in flexible benefit plans.Wellness ProgramsWellness programs are designed to reduce sick-leave and medical expenses. These progr ams may include exercise, nutrition, stress reduction classes, as well assmoking and substance abuse help. Why the popularity of wellness and counseling progr ams? Studies show that lifestyle and diet impact illness, and that counseling programs can hel p curtail other higher cost benefit usage.In linking benefits to a corporate strategy plan, employers want to: help employees to lower their health costs; reduce turnover of good employees; and increase productivity .A company's HR department can perform audits to make sure that a wellness program is a valued added benefit.Flexible Benefit PlansFlexible benefit plans are increasing in number because the needs of workers are more di verse today. The rationale behind these plans is to increase employee satisfaction, reduce turn over, and decrease expenses to employers. Flexible benefit plans can also help employees realize the value of their benefits. The cost to administer these plans may be higher than with stan dard benefit provision, but flexible benefit plans can save money by not providing a specific b enefit to an employee who does not want it. Flexible benefit plans support workplace diversit y and changing employee demographics by allowing employers to offer a variety of benefits t o their workers.Frequently included in flexible benefit plans are salary reduction features that enable em ployees to divert pretax dollars into nontaxable benefit choices. If an employer needs to reduc e costs because of low profits one year, it can lessen its contribution to benefits, but still allow employees to direct where they want their benefit dollars to go, instead of making across-the-board cuts in coverage.Flexible benefit plans also put a price on benefits, which helps makes employees aware o f their actual cost—a fact often taken for granted. Flexible benefit plans help to equalize benef its provision because one employee may want a child-care benefit, but an older employee may want more life insurance coverage. These plans tend to have a positive impact on employees and are more cost-effective to employers.Flexible benefit plans also:reduce the entitlement mentality that has become associated •with the provision of many benefits;better associate benefits with direct compensation; andfit well with the trend of more employee involvement in company decision-making.Outplacement Benefit PlansOutplacement benefits plans provide support for terminated employees, and in turn show the remaining employees that the company is trying to be fair. Such plans may include office space, resume writing assistance, and employment counseling, among other benefits. These pl ans are designed to reduce termination litigation and to help maintain the morale of remaining employees.Source:Tudor,Thomas R,Trumble,Robert R.The Changing Pattern of Pay and Benefits[J].Jour nal of Compensation & Benefits,2008,(May):22-25Pay for performanceNot everyone sees the trend toward paying for skills and/or competencies as a good thing:It would be easy to conclude from reports in the business press that merit pay is dead and organizations need to reconstitute pay plans to pay people in some new way. Suggestions include paying employees for the knowledge, shills, abilities and behaviors they bring to theworkplace. Although interesting, this call for wholesale reform overlooks fundamental tenets of economic and behavioral theories.Pay for performance is the holy grail of modern compensation administration—widely sought but hard to actually achieve .Pay for performance is the flag, motherhood, and apple pie, but it is easier said than done. One primary problem is defining performance properly, so that the organization pays for results and not for effort. Once over that hurdle, there remains the large impediment of finding enough money to make the reward for top performance meaningful. Many different approaches are used—various variable pay schemes, annual awards in lieu of permanent increase in base pay, and the traditional merit pay salary increase.The concept of pay for performance has different meanings to different people. Many either fail to recognize the pay for performance fails when the different in reward between adequate performance and outstanding performance is inconsequential or cannot solve the problem of funding adequate differentiation while dealing with essential range maintenance costs.For example, Logue reported on the introduction of performance-based pay for unionized employees in a public university. The old system had four annual, essentially “automatic,”5percent steps from minimum to maximum. The new system added 10 percent to the top of the salary range. All employees would move through the regular range automatically, but growth within the top 10 percent was based only on performance. Since 20 percent of all salary increase funds were allocated to performance increases, top performers could receive additional amounts over and above the automatic movement through the standard portion of the salary range.Such performance-based salary increases (PSIs) went to 12 percent of the represented employees, who receive PSIs ranging from 3.9 to 5.9 percent in the first fiscal year (2000 to 2001). PSIs ranged from 0.5 to 4 percent in fiscal year 2001 to 2002 due to the greater number of employees receiving increases. One wonders what happened the third year! In any event, achieving an extra 1 or 2 or 3 percent is unlikely to stimulate anyone to significantly higher levels or performance, particularly when they are guaranteed automatic annual increases.Others take steps to address the differentiation problem:Through the implementation of a new tool called the Monoline Merit Increase Matrix, one organization shows how it rewards employees based on performance and gets more mileage out of its merit increase budget…The Monoline Merit eliminates the use of comparisons for merit increase. It is designed to create a larger distinction in the merit percent provided between top performers and employees who meet expectations and are paid fairly for their work…Under the new methodology, managers must examine the possibility that employees who meet performance goals do not have to receive a merit increase if they are competitively paid. Pay for whose performance :Even if one can solve the differentiation problem, there still remains the problem of determining the locus of performance pay plans all devolve into two broad categories, depending on whether performance is measured at the group or at the individual level: Group plans can fail to specifically direct or reward individual employees behaviors. As a result, group plans have produced somewhat limited results with respect to improvements in employees performance or organizational profitability. Further, group plans do not different reward individual who perform well vs. those who do not. This may exact the perception of pay inequities among better performers.Performance pay plans based on individual performance are more effectives in improving individual employee performances vs. group plans. Typically, these plans provide specific and objective goals for employees to work toward. However, rewarding individual performance may reduce cooperation among employees and focus employees on a restricted range of results.Designing an effective compensation program:First, an effective compensation program should recognize that monetary rewards do change employee behavior despite what some academicians have claimed. The power of money is twofold. It not only is valued for itself, for what it can buy, but it can also serve as a powerful communication devise, as a score card if you will.Second, stick to the basics when designing a salary program. Pay people at a reasonable market level for base salary based on survey data (what is reasonable will depend on your ability to pay and the availability of the talent you need.) focus primarily on external pay market data, and maintain internal equity only within each separate pay market. That is, internal equity is important within information technology, engineering, accounting, etc., but is not important between these groups as they are in separate pay markets. One size never fits all!Third, use variable pay everywhere. For those positions that cannot be individually measured, use group measures (work group, location, division, and/or corporate measures, as appropriate). For those positions that can be individual measured, use a combination of individual and group measures (individual measures to motivate individual effort, group measures to encourage cooperative behavior).Fourth, keep the performance measures as simple as possible and limit their numbers, preferably to two or three, Remember, what you measure is what you get, so pick yourmeasures carefully.Fifth, communicate, communicate, communicate. Communicate the details of the program. Communicate the rationale for the measures—that is, how they fit into the organization’s strategy. Communicate on an ongoing basis actual performance versus target performance.Source: Martin G.Wolf,2002 “linking performance scorecards to profit performance pay”ACA News,vol.41,no.4,april,pp.23-25.Variable payVariable pay is an expanding field within compensation driven by the emerging trends of pay for performance and competitive advantage. Funding these new programs and developing the processes supporting long-term effectiveness is critical.Pay for performanceIn the past, company employment was routinely assumed to be for a career. Many, many employees worked for one organization for their entire work life. Loyalty on the part of the employer and employees was taken for granted. Times have changed. Reengineering, downsizing, and talent wars have reworked the playing field for employment decisions. No longer does a new college graduate dream of working for the same company for life. In addition, worldwide competitive business pressure has focused corporations on performance. In the past and still for many organizations today, paying for performance is normally done with promotions over the career. Base pay increase over time is a normal method to reward performance.Information technology professionals can now move from company to company with ease and can expect to receive a year 2000 bonus if they stay until the new millennium. Organizations realize the competitive demands for change and the need to motivate change. Many employees are now asking “What is in it for me if I take the risk?” Variable pay is an excellent way to answer the question. Pay for performance with variable pay below the executive level is in its infancy for most organization excluding the sales organization. Less than 30 percent is profit sharing and does not have a line of sight to business unit performance .Fewer than 10 percent of organization have variable pay programs for all employees that reward individual, team, and business unite performance. Variable pay has many opportunities for growth with the new organization emphasis on performance, retention, and competitive advantage.Funding variable payFinancially, variable pay is very attractive compared to base pay increase programs. Base pay increase compound and a concern for permanent increase cost. In addition, base pay increases have an entitlement mentality where the recipient is looking for the next one shortly after receiving the last increase. Many corporation reinforce this expectation by having an annual increase plan (normally called a merit increase plan ) to adjust for inflation and market movement.Variable pay is attractive because it does not compound from year to year, and the unspent funds can be reused each year or budget cycle. Having employees learn their performance bonus each year creates a compelling reason for them to improve instead of relaxing into an entitlement mentality, which is often the result of base pay increase programs. When business results are good, the payout can be attractive, and, when times are bad, the payout is small, reducing costs and helping to improve the bottom line.Strategic planning can support the movement to variable pay. Moving to a strong variable pay program can take years with the need to build success along the way.Variable pay successSo if variable pay has such great potential, why has there been such a reluctant to implement variable pay? One answer is that the failure rate for variable pay plans is 38 percent as document in an ACA study by Marc Wallace. The success rate in executive compensation and sales compensation is substantially greater, but the concern for excessive reward is real. Executive compensation requires hand holding and considerable administration. Many small-group plans require period redesign, which takes more compensation consulting resources than are available. These draw backs are part of the reluctance of management to implement variable pay.Building variable pay plans to be continuous for the long term is the key to variable pay success, Most plans need to be renewed annually to ensure on going success. Fairness, trust and impact on the business are all measures of success. Plans that do not continuously evolve need extra attention every year and will fail to more frequently. I helped implement two variable pay plan for all employees at Coring incorporated, and those plans are now over 10 years old and going strong, One is a spot bonus plan, and the other is good sharing .variable pay plans can indeed work very well.Balancing individual incentives with shared business goals is important. This rewards for business success are the most critical and should be more significant in total dollars than individual reward. The bottom line is that the business needs to succeed. Line of sight and control are also important variables. Many times this is where incentives come into play. People like to be judged on what is control is delicate. Too much emphasis on individual。

采矿工程毕业设计_外文翻译英译汉中英文

ROOM-AND-PILLAR METHOD OF OPEN-STOPE MINING空场采矿法中的房柱采矿法Chapter 1.A Classification of the Room-and-Pillar Method of Open-Stope Mining第一部分，空场采矿的房柱法的分类OPEN STOPING空场采矿法An open stope is an underground cavity from which the initial ore has been mined. Caving of the opening is prevented (at least temporarily) by support from the unmined ore or waste left in the stope,in the form of pillars,and the stope walls (also called ribs or abutments). In addition to this primary may also be required using rockbolts , reinforcing rods, split pipes ,or shotcrete to stabilize the rock surface immediately adjacent to the opening. The secondary reinforcement procedure does not preclude the method classified as open stoping.露天采场台阶是开采了地下矿石后形成的地下洞室。

通过块矿或采场的支柱和（也称为肋或肩）采场墙形式的废料的支持来（至少是暂时的）预防放顶煤的开幕。

除了这个，可能还需要使用锚杆，钢筋棒，分流管，或喷浆，以稳定紧邻开幕的岩石表面。

翻译原文

The inﬂuence of temperature on nutrient treatmentefﬁciency in stormwater bioﬁlter systemsG.-T.Blecken*,Y.Zinger***,T.M.Muthanna**,A.Deletic***,T.D.Fletcher***and M.Viklander* *Urban Water,Department of Civil,Mining and Environmental Engineering,Lulea˚University of Technology, 97187Lulea˚,Sweden(E-mail:godecke.blecken@ltu.se;maria.viklander@ltu.se)**Norwegian Institute for Water Research,Havnegata9,7010Trondheim,Norway(E-mail:tone.muthanna@niva.no)***Department of Civil Engineering,Facility for Advancing Water Bioﬁltration,Monash University,Victoria 3800,Australia(E-mail:yaron.zinger@.au;Tim.Fletcher@.au;ana.deletic@.au)Abstract Nutrients can cause eutrophication of natural water bodies.Thus,urban stormwater which is an important nutrient source in urbanised areas has to be treated in order to reduce its nutrient loads.Bioﬁlters which use soilﬁlter media,bioﬁlms and plants,are a good treatment option for nutrients.This paper presents the results of a bioﬁlter column study in cold temperatures(þ28C,þ88C,control atþ208C) which may cause special problems regarding bioﬁlter performance.It was shown that particle-bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively inﬂuenced by cold temperatures.Nitrogen,however,was not reduced;especially NO x was produced in the columns. This behaviour can be explained with both insufﬁcient denitriﬁcation and high leaching from the columns. Keywords Bioﬁlter;cold climate;nutrients;stormwater treatmentIntroductionNutrients can cause eutrophication in receiving natural water bodies(Browman et al., 1979;Pitt et al.,1999;Kim et al.,2003).Stormwater runoff is an important source of nutrients in urbanised areas(Larm,2000;Graves et al.,2004;Taylor et al.,2005),and it should therefore be treated.Stormwater bioﬁltration,also known as bioretention,is a novel option that might be able to treat nutrients in stormwater in order to prevent eutrophication of recipients.A bioﬁlter consists ofﬁlter media placed in a trench or basin that is planted on the top.It has a detention storage on the top(by placement in a depression)and a drainage pipe at the bottom to collect the treated water.Stormwater is treated by mechanical,biological and chemical processes in theﬁlter media,but also by the plants and bioﬁlms,that develops in the media and on the plant roots(Prince George’s County,2002;Hsieh and Davis,2005).Several studies conducted so far have shown a signiﬁcant removal of phosphorus, phosphate and ammonium,but with low(and sometimes negative)removal of nitrate (Davis et al.,2001;Lloyd et al.,2001;Henderson et al.,2007).However,bioﬁlters are still a relatively new technology and hence,only limited data of the performance of these systems are available.Particular problems could arise when implementing bioﬁlters in regions with constant or temporary cold temperatures,due to reduced biological activity, shorter growing seasons and a smaller number of adapted plant species.However,these systems may still perform well in these instances,since adequate nutrient removal has been achieved in constructed wetlands in cold subalpine climates(Heyvaert et al.,2006). Bioﬁlter performance in cold temperatures is the deciding factor to their successful implementation in regions with rainfall on non-frozen ground during cold periods Water Science & Technology Vol 56 No 10 pp 83–91 Q IWA Publishing 2007 83doi:10.2166/wst.2007.749(autumn,winter and spring in temperate climate;autumn,later spring and summer in cold climate).This paper presents preliminary results of a study of the performance of bioﬁlters in relation to temperature.The aim was to determine the nutrient treatment performance of stormwater bioﬁlters in low temperatures in order to enable an analysis of whether there is a correlation between temperature and treatment rate.Material and methods Experimental set-up Laboratory tests were conducted on 15bioﬁlter mesocosms (‘bioﬁlter columns’)made of PVC stormwater pipe (inner diameter:377mm,area:0.11m 2,height:900mm).A trans-parent top (height:400mm)allowed water to pond without affecting light availability for plant growth.The inside wall was sandblasted to prevent preferential ﬂow along the wall.A drainage pipe (diameter:58mm)at the bottom discharged to a sampling outlet (Figures 1and 2).The ﬁlter media in the columns included four layers (listed from top,Figure 2):(1)sandy loam layer,400mm,medium to coarse sand with 20%topsoil in the upper 100mm,(2)sand layer,400mm,ﬁne to medium sand,(3)transition layer,30mm,coarse sand and (4)underdrain,70mm,ﬁne gravel with embedded drainage pipe.The columns were planted with Carex rostrata Stokes (Bottle sedge)which is wide-spread in the northern hemisphere (Anderberg and Anderberg,2006).The plant density in the columns was 8plants per column,which corresponds to a density of approximately 73plants/m 2.Before they were planted in the columns,the plants were grown for 5weeks outside to develop a substantial root system.Afterwards they were grown in the columns for two month and irrigated with tapwater.Figure 1Bioﬁlter columns in climate roomG.-T.Bleckenetal.84In order to investigate the temperature effect on the bioﬁlter performance,the tests were carried out in three thermostat controlled climate rooms at constant target tempera-tures of þ28C,þ88C,and þ208C (þ35.68F,þ46.48F,and þ688F,resp.).Five columns each were placed in every climate room (Figure 1).The air temperature in the climate rooms was logged at a 15minute interval using one EBI 20-T (88C)and two EBI 2T-112(28C and 208C)temperature loggers (ebro Electronic,Ingolstadt,Germany).All columns were illuminated with high pressure sodium greenhouse lamps (G-Power Agro,400W,55,000Lm)12hours daily.Experimental procedureStormwater .Since natural stormwater was not available in the required quantity and with constant water quality over the time of the experiment,nor could be stored without signiﬁcant changes to its quality,semi-synthetic stormwater was used.It was made by mixing tap water with gully pot sediment to achieve the required TSS concentration,topped with certain pollutants to achieve the targeted pollutant concentrations,as outlined in Table 1(only for nutrients;heavy metals were added as well,but are not reported in this paper).A new mixture was made for every stormwater application.The water was stored at the respective temperature (28C,88C,208C,resp.)for at least 24hours before dosing the columns in order to have similar water and air temperatures.In Lulea ˚(Sweden)it rains approximately two times per week in September and October (the month with the most rain events in cold temperatures)with a total precipi-tation amount of around 110mm (SMHI,2005).This corresponds to an average of 5.4L/m 2stormwater runoff per rain event from a catchment with 85%impervious surface.It Figure 2Bioﬁlter column conﬁgurationG.-T.Blecken et al.85was assumed that the bioﬁlter area represents appr.4%of the catchment area (one col-umn with 0.11m 2for 2.75m 2catchment)(Wong et al.,2006).Therefore every column was dosed with 15L (5.4L/m 2·2.75m 2¼14.85L <15L)of stormwater twice weekly.Sampling .From the stormwater a sample was taken in three replicates before every stormwater application.All outﬂow water was collected in PE-tanks until the next dosing event,it was stored at þ28C,and a composite sample was taken from each PE-tank,i.e.15samples per each dosing.This paper reports on results of the ﬁrst four weeks of stormwater dosing (i.e.eight events).Analyses .All samples were analysed for total and dissolved N,ammonium (NH þ4),nitrate/nitrite (NO x ),TSS,and pH.The dissolved samples were ﬁltered,using Whatman ME25membrane 0.45m m pore size ﬁlters.Before analysing P and N,the samples were digested with peroxo-disulphate (according to the Swedish standard method SS 028127)and oxidised with peroxisulphate (SS 028131),resp.The analyses were conducted with a continuous micro ﬂow analyser (QuAAtro,Bran þLuebbe,Hamburg,Germany)according to the device-speciﬁc methods no.Q-031-04for P,no.Q-003-04for N and NO x and no.Q-001-04for NH þ4.TSS was determined by ﬁltration through Whatman GF/A 1.6m m pore size glass microﬁbre ﬁlters (SS-EN 872)in one replicate.pH was measured with a ﬁeld pH-meter (pH330,WTW GmbH,Weilheim,Germany).Data analyses Pollutant reduction was calculated as reduction ¼(1-(out/in))·100%.Thus,production of pollutants results in a negative reduction rate.Analysis of variance (ANOVA)was used to test the inﬂuence of temperature on outﬂow concentrations.Furthermore,box plots were created for nitrogen species and phosphorus to compare in-and outﬂow concen-trations and their evolution over time.All statistical calculations and plots were computed with the software MINITAB w 15.1.Results and discussion The mean temperature in the three different rooms were 1.88C (SD:1.018C),7.48C (SD:0.358C)and 20.38C (SD:1.028C)respectively.Thus,the real temperatures were very near the target temperatures.The mean inﬂow and outﬂow pollutant concen-trations (mg/L)as well as reduction rates (%)at the three different temperatures are shown in Table 2.pH .The average pH-value of the stormwater was 6.9.The pH increased in the columns and the outﬂow pH at all temperatures was around 7.4.Table 1Semi-synthetic stormwater pollutants and their sourcesPollutant Targeted SourcepH6.9H 2SO 4TSS140mg/L Stormwater gully pot sediment (#400m m Phosphorus (total)0.3mg/L KH 2PO 4(potassium dihydrogen phosphate)0.32mg/L nitrate:KNO 3(potassium nitrate)Nitrogen (total) 1.4mg/L 0.24mg/L ammonium:NH 4Cl (ammonium chloride)organic nitrate:C 6H 4NO 2(nicotinic acid)G.-T.Bleckenetal.86TSS .Reduction of TSS was around 97%,and whilst the effect of temperature on this removal was statistically signiﬁcant (p ¼0.001),it accounted for very little of the observed variation,and was of no practical signiﬁcance (Table 3,Figure 3).Other factors are clearly inﬂuencing TSS removal,although it was high in all cases.The low difference between the columns at different temperatures is not surprising since the TSS removal is mainly a matter of mechanical ﬁltration which itself is not inﬂuenced by temperature (unless the soil media soil freezes forming channels).Because of the high TSS removal,a high (and largely temperature independent)removal of particle bound pollutants could be expected.Phosphorus .In the stormwater inﬂow 85%of the total phosphorus was particle bound.The fraction was slightly different in the outﬂow at the different temperatures (28C:87%particle bound,88C:84%particle bound and 208C:82%particle bound).A temperature independent removal of about 80%was detected for total phosphorus (p ¼0.933,Table 3).There is a very clear decrease in the outﬂow concentrations and their variances over time (Figure 4).Dissolved phosphorus was also well removed by the bioﬁlter,with no signiﬁcant temperature dependence (p ¼0.285,Table 3).However,its reduction rate was slightly higher at cold temperatures.The results make sense,if we assume that physical ﬁltration is the main mechanism for P removal,while biological activity within the soil may cause some leaching of P from media (the higher biological activity occurs at higher temperatures).This leaching is getting smaller with time as the Table 2Pollutant concentrations and removalStormwater (2)all temp.Outﬂow (3)28C 88C 208CpH 6.90(0.20)7.32(0.13)7.40(0.10)7.46(0.18)TSS concentration 142.7(13.9) 3.6(1.4) 5.1(1.7) 4.6(2.1)mean reduction 97.5%96.4%96.8%N total concentration 1.38(0.16) 1.38(0.29) 1.54(0.25) 4.23(0.68)mean reduction 20.5%211.6%2207.8%N dissolved concentration 1.16(0.08) 1.33(0.26) 1.31(0.15) 3.94(1.02)mean reduction 214.9%213.2%2240%NO x (1)concentration 0.24(0.01)0.72(0.26)0.89(0.13) 3.79(0.57)mean reduction 2198%2265%21461%NH 4(1)concentration 0.32(0.05)0.11(0.05)0.14(0.06)0.15(0.05)mean reduction 64.5%56.2%51.7%P total concentration 0.292(0.018)0.055(0.036)0.058(0.032)0.056(0.030)mean reduction 81.2%80.3%80.7%P dissolved concentration 0.031(0.017)0.007(0.002)0.009(0.004)0.010(0.005)mean reduction 77.5%71.5%69.3%(1)only the ﬁrst 4events have been analysed (2)three replicates per event analysed (3)mean value of ﬁve replicate columns and all events.Table 3One-way ANOVA:p-value of temperature inﬂuence on outﬂow concentrations and R 2(adjusted)of the modelp -value R 2(adj.)TSS 0.0019.0%N total 0.00089.4%N dissolved 0.00080.4%NO x (2)0.00093.7%NH ð2Þ40.065 6.0%P total0.9330.0%P ð2Þdiss :0.285 2.1%G.-T.Blecken et al.87source is depleted,which explains the decreasing outﬂow concentrations with time in Figure 4.Overall however,mechanical removal of phosphorus is the most important factor and therefore overall P removal is high.Nitrogen .While the bioﬁlters at 28C and 88C showed little or no leaching of total nitrogen,a high production (on average 2208%removal)was observed at 208C (Figure 5,Table 2).No trend over time wasobserved.Figure 3Box plot of in-and outﬂow TSS concentrations at the 3different temperatures and 8samplings Figure 4Box plots of in-and outﬂow total phosphorus concentrations at the 3different temperatures and 8samplingsG.-T.Bleckenetal.88The total nitrogen in the synthetic stormwater inﬂuent was 84%dissolved,whilst in the treated outﬂow water 96%,85%and 93%was at 28C,88C and 208C,respectively.The proportion of the nitrogen compounds changed during the treatment in the bioﬁlter.NH þ4was reduced at all temperatures,whilst NO x was produced (Table 2,Figure 6).This means that nitriﬁcation in the unsaturated zone of the bioﬁlter was occurring and there-fore NH þ4levels were decreased and NO x levels were increased.Since no denitriﬁcation was taking place due to the lack of an anoxic zone and/or a carbon source,levels of NO xFigure 5Box plots of in-and outﬂow total nitrogen concentrations at the 3different temperatures and 8samplingsFigure 6Box plots of in-and outﬂow:(a)dissolved NO x ,(b)and dissolved NH þ4concentrations at the 3different temperatures and 8samplings G.-T.Blecken et al.89However,a signiﬁcant temperature effect was demonstrated for dissolved nitrogen behaviour (p ¼0.000dissolved N and NO x ,Table 3):the higher the temperature the higher the NO 3production due to increasing nitriﬁcation with increasing temperatures.More importantly,more nitrogen from the soil leached to the outﬂow water at higher temperatures.Unfortunately,it is not clear yet whether the leaching will stop over time as plants mature,as has been observed in similar bioﬁlter studies (Zinger et al.,2007).The plants had only 2–3months of establishment,while in Zinger at al ’s experiments they had 5months to establish.It is known that plants (and in particular their roots)play a major role in N removal,since unvegetated bioﬁlters are always demonstrated to leach nitrogen (Hatt et al.,2006;Lee and Schloz,2007),whilst vegetated bioﬁlters do not (Henderson et al.,2007).Conclusion Even in cold climates,it is clear that effective removal of particle-bound pollutants (TSS and particulate phosphorus)can be achieved.This veriﬁes the ﬁndings of other cold climate studies (Ba ¨ckstro ¨m,2002;Muthanna et al.,2007).However,the results showed poor overall removal of nitrogen from the stormwater.In particular,there was a very high production of NO x ,which was probably caused by nitriﬁcation,and limited denitriﬁ-cation.Such large net production of nitrogen was not expected as other studies have shown a reduction or at least only minor production of nitrogen even in bioﬁlters without an anoxic zone (Kim et al.,2003;Scholz,2004;Zinger et al.,2007).However,it is possible that the short establishment time of the plants in the presented experiments is the main cause of this.Further research should be conducted to investigate if the removal of N will begin to improve over time.The bioﬁlters showed the best performance for nitrogen (i.e.the lowest production)at the coldest temperatures.A key area of subsequent research is therefore to determine if the addition of an anoxic zone with added carbon source,which has been shown to improve denitriﬁcation in bioﬁlters (Kim et al.,2003;Zinger et al.,2007),would remain effective,even in cold temperatures.References Anderberg,A.-L.and Anderberg,A.(2006).Den virtuella ﬂoran:Naturhistoriska Riksmuseet.http://linnaeus.nrm.se/ﬂora/(accessed 08October 2007).Browman,M.G.,Harris,R.F.,Ryden,J.C.and Syers,J.K.(1979).Phosphorus loading from urban stormwater runoff as a factor in lake eutrophication -Theoretical considerations and qualitative aspects.J.Environ.Qual.,8(4),561–566.Ba ¨ckstro ¨m,M.(2002).Grassed Swales for Urban Drainage .Doctoral Thesis 2002:06,Division of Sanitary Engineering,Lulea ˚University of Technology,Lulea ˚,Sweden.Davis,A.P.,Shokouhian,M.,Sharma,H.and Minami,C.(2001).Laboratory study of biological retention for urban stormwater management .Water Environ.Res.,73(1),5–14.Graves,G.A.,Wan,Y.and Fike,D.L.(2004).Water quality characteristics of storm water from major land uses in south Florida .J.Am.Water Resour.Assoc.,40(6),1405–1418.Hatt,B.E.,Siriwardene,N.,Deletic,A.and Fletcher,T.D.(2006).Filter media for stormwater treatment and recycling:the inﬂuence of hydraulic properties of ﬂow on pollutant removal .Water Sci.Technol.,54(6–7),263–271.Henderson,C.,Greenway,M.and Phillips,I.(2007).Removal of dissolved nitrogen,phosphorus and carbon from stormwater by bioﬁltration mesocosms .Water Sci.Technol.,55(4),183–191.Heyvaert,A.C.,Reuter,J.E.and Goldman,C.R.(2006).Subalpine,cold climate,stormwater treatment with a constructed surface ﬂow wetland .J.Am.Water Resour.Assoc.,42(1),45–54.Hsieh,C.-H.and Davis,A.P.(2005).Multiple-event study of bioretention for treatment of urban storm water runoff.Water Sci.Technol.,51(3–4),177–181.G.-T.Blecken et al.90Kim,H.,Seagren,E.A.and Davis,A.P.(2003).Engineered bioretention for removal of nitrate from stormwater runoff.Water Environ.Res.,75(4),355–367.Larm,T.(2000).Stormwater quantity and quality in a multiple pond-wetland system:Flemingsbergsviken case study.Ecol.Eng.,15(1–2),57.Lee,B.-H.and Scholz,M.(2007).What is the role of Phragmites australis in experimental constructed wetlandﬁlters treating urban runoff?Ecol.Eng.,29(1),87–95.Lloyd,S.,Fletcher,T.D.,Wong,T.H.F.and Wootton,R.M.(2001).Assessment of pollutant removalperformance in a bio-ﬁltration system-preliminary results.Paper presented at the Second South Paciﬁc Stormwater Conference,New Zealand.Muthanna,T.M.,Viklander,M.,Blecken,G.-T.and Thorolfsson,S.T.(2007).Snowmelt pollutant removal in bioretention areas.Water Res.,41(18),4061–4072.Pitt,R.,Clark,S.and Field,R.(1999).Groundwater contamination potential from stormwater inﬁltration practices.Urban Water,1(3),217.Prince George’s County(2002).Bioretention Manual.Lead Author:D.A.Winogradoff.Department of Environmental Resources,Programs&Planning Division,Prince George’s County,Maryland,USA. Scholz,M.(2004).Treatment of gully pot efﬂuent containing nickel and copper with constructed wetlands ina cold climate.J.Chem.Technol.Biotechnol.,79,153–162.SMHI.Swedish Meteorological and Hydrological Institute(2005).Klimatkarta Uppma¨tt nederbo¨rd 1961–1990,ma˚nadsvis.(In Swedish).Taylor,G.D.,Fletcher,T.D.,Wong,T.H.F.,Breen,P.F.and Duncan,H.P.(2005).Nitrogen composition in urban runoff–implications for stormwater management.Water Res.,39(10),1982.Wong,T.H.F.,Fletcher,T.D.,Duncan,H.P.and Jenkins,G.A.(2006).Modelling urban stormwater treatment–A uniﬁed approach.Ecol.Eng.,27(1),58.Zinger,Y.,Fletcher,T.D.,Deletic,A.,Bleckenr,G.-T.and Viklande,M.(2007).Optimisation of the Nitrogen Retention Capacity of Stormwater Bioﬁltration Systems.Paper presented at the NOVATECH 2007,Lyon,France.G.-T. Blecken et al.91。

毕业设计英文翻译原文

英文原文1. General description of the SIEMAG disc brake unitThis brake unit is the electro-hydraulic control system of a gearless disc brake for winders. The brake unit operates on the exhaust principle, i.e. the braking force is generated by sets of disc springs and released by hydraulic pressure.The braking force generators with the brake shoes directly act axially on the brake disc. The braking force is generated by sets of disc springs and transmitted onto the brake shoes. The number of brake elements determines the respective braking force required.As soon as the brakes are being released, the brake shoes are lifted form the brake disc with the aid of pressure oil. During the braking, the oil flows back into the tank and the brake shoes are being pressed against the brake disc.The braking force generators type BSFG 408 are s series product supplied by the Swedish firm ASEA-Hagglunds. They have a maximum press-down force of2X7906 kN.For reasons of better system availability, the hydraulic pressure is generated by two regulating pumps that are each driven by an electric motor. Both pumps are started when the system is being switched on. Any failure of a pump will be signaled.The oil filtration is undertaken by a pressure filter‘6.2’provided in front of the braking force generators. Furthermore, two gear pumps that are directly coupled with the regulating pumps, maintain a permanent oil cooling and filtering circuit during system operation (filter‘6.1’and cooler ‘14’). Both filters have an electrical contamination control. The mesh size of the filters is specified by the supplier to be 10μm (see TAS No.3.9.6.4). The equipment includes a controlled electrical tank heating. The fluid level in the tank is monitored as well.The service braking is done with the aid of two electrically controlled proportional pressure relief valves‘43.1’and‘43.2’that are hydraulically connected in series.The safety braking is done with the aid of position-controlled 4/2-way electro valves‘53.1’、‘53.2’、‘39.1’、‘39.2’、‘58.1’、‘58.2’、‘66.1’，and‘66.2’which are electrically actuated in closed-circuit connection.In the event of a safety braking, the directional control valves‘39.1’and‘39.2’are switched off, separating thus the pump pressure from the remaining brake releasing system(hydraulic shunt).During the safety braking, the directional control valves‘6.1’and‘66.2’are acting as pilot valves for the 2/2-way valves‘65.1’and ‘65.2’which again release the pressure relief valves‘64.1’and‘64.2’.The electro valves‘53.1’and‘53.2’operate as outlet valves according to TAS No.3.9.5.9.The mechanically controlled pressure relief valves‘60.1’and‘60.2’are arranged in the outlet line of these valves. They determine the residual pressures in the course of safety braking. These residual pressures (pressure stages 1 and 2) are maintained by bladder-type accumulators.The gas pressure of the respective accumulator used is monitored.The march of pressure is adjusted with the aid of mechanical skids which are adapted to the braking process desired.A hand-operated pump‘48’is provided for assembly purposes, when the controlled main stop cocks‘46.1’and‘46.2’in the outlet line of the brake elements are locked.The position-controlled 4/2-way valves‘63’and the pressure relief valves ‘25.1’and‘25.2’(residual pressure accumulator) are fed by a back-up power supply in open-circuit connection. The valves get open when the solenoids are energized.With the command‘RELEASE BRAKE’，the two residual pressure accumulators are filled through the check valves‘87.1’and‘87.2’.The residual pressure accumulator‘24.1’(pressure stage 1) is connected through the 4/2-way valve‘86’. The residual pressure accumulator‘24.2’(pressure stage 2) is automatically connected by a change-over of the 4/2-way valve‘86’, when the hoisting load changes accordingly.2. Functional description of the electro-hydraulic control system corresponding to the hydraulic drawing No.0905216/12.1 Method of operation of the brake unitThe braking force is the sum of pressing forces per brake shoe, reduced by the forces being generated by the oil pressure in the cylinders of the brake element.The force required for the service braking is achieved by controlling the oil pressure. Two pressure regulating valves‘43.1’and‘43.2’, each being fitted with separate control electronics and function control, are connected in series, permitting thus a stepless adjustment of the valves between a minimum and a maximum pressure. In the case of failure of one brake is applied when the spring forces press the brake shoes against the brake disc without counterpressure. The brake is released when the pressure oil in the cylinders of the brake elements reduces the spring forces to zero and the brake shoes are lifted the brake disc.The brake releasing pressure is generated through the pressure-controlled pumps‘1.1’and‘1.2’which are driven by electric motors‘3.1’and‘3.2’. The pressure regulating valves of the pumps are adjusted in such a way that, as soon as the brake releasing pressure has been reached, the pumps reduce the flow rate from the maximum value to the quantity required for maintaining the releasing the pressure. This means in other words that the pumps only deliver the quantity of oil that is demanded to replace any oil losses from leakage and to maintain the pressure adjusted on the pressure regulating valves‘43.1’and‘43.2’.When starting the safety braking, the circuit of the electro-hydraulic brake control system (including pump motors) is cut off. The 4/2-way valves ‘53.1’，‘53.2’,‘39.1’and‘39.2’are thus de-energized and the pump circuit is separated form the brake elements and the pressure accumulators‘24’. The service brake valves‘43.1’and‘43.2’remain energized through a back-up current supply. The residual pressure is as high as to ensure the winder retardation being below the rope slip limit.The hand-operated pump‘48’is only connected for the start-up operation and stored separately.2.2 Operating states2.2.1 Starting the systemThe winder is at standstill and the brake applied. The control voltage and the voltage for the pump motors‘3.1’and‘3.2’is available. The electrical monitoring system signals the system to be trouble-free and all preconditions for starting the pumps‘1.1’and‘1.2’fulfilled (please see also item 2.3.1), which means that the safety circuit is closed as well.The 4/2-way valves‘39.1’and‘39.2’are energized by starting the pump motors‘3.1’and‘3.2’,thus opening the cross section between pumps and brake elements. The safety brake valves ‘53.1’、‘53.2’、‘58.1’、‘58.2’、‘66.1’and‘66.2’close.The pumps‘1.1’and‘1.2’are now connected through the pressure regulating valves‘43.1’and‘43.2’with the brake elements. The coils of these valves are de-energized, i.e. the valves are open, permitting the oil to return without pressure form the pumps‘1.1’and‘1.2’through the pressure regulating valves into the tank.2.2.2 Releasing the service brakeWith the command‘RELEASE BRAKE’, the coils of the pressure regulating valves‘43.1’and‘43.2’are fed with the maximum valve of regulable current, and the valves retain the maximum releasing pressure adjusted. The pumps‘1.1’and‘1.2’thus feed the oil through the valves‘39.1’and‘39.2’to the brake element. The accumulators for the residual pressure‘24.1’and‘24.2’are also filled through the operating pumps. The brake elements are released as soon as the maximum releasing pressure has been reached. The pressure-controlled pumps then reduce the flow rate to the quantity required for compensating all oil loses form leakage. The releasing pressure is maintained by the pressure regulating valves‘43.1’and‘43.2’.The pressure switches‘34.1’/‘34.2’monitor the filling of the bladder-type accumulators for residual pressure‘24.1’/‘24.2’.With this operating state, the valves‘53.1’and‘53.2’are closed and the outlets of the hydraulic safety circuit thus locked.2.2.3 Service brakingDuring the service braking, the pressure regulating valves‘43.1’and‘43.2’are steplessly controlled. This reduces the releasing pressure in conformity with the position of the brake lever. The oil displaced form the brake elements as well as the excess oil form the pumps‘1.1’and‘1.2’flows back through the pressure regulating valves‘43.1’and‘43.2’into the tank.These proportional pressure regulating valves comprise a pilot control valve and a main valve. They are operated by parallel control of the pilot control valves with the main valves connected in series.This means in other words that both proportional pressure regulating valves are always active in the pilot control circuit. However, the main pressure regulating function is always fulfilled by that valve which is nearer to the pressure source. Only in the event of a failure this function is performed by the subsequent valve.The power supply to the control electronics of each regulating valve is additionally backed up by a battery ensuring, in the event of a total power failure or wire brakeage, that at least one regulating valve remains operative.The buffered voltage supplies are monitored for a failure of the buffering in the electrical and electronical circuits of the brake control system.2.2.4 Safety brakingAs soon as the safety circuit is actuated, the pump motors‘3.1’and‘3.2’and the entire electrical control system, except the control of the service brake regulating valves, are de-energized.The oil draining pressure is released through the pressure relief valves ‘64.1’and‘64.2’by de-energizing the solenoid valves‘66.1’and‘66.2’. The releasing pressure in the brake elementsand in the conduits is thus rapidly reduced to that value at which the brake shoes touch the brake discs without pressing force.The de-energized valves‘39.1’and‘39.2’(hydraulic shunt) isolate the pumps‘1.1’and‘1.2’form the brake elements and, at the same time, connect the brake elements with the residual pressure accumulator ‘24.1’and‘24.2’.The hydraulic pressure is further reduced the residual pressure lever through the directional control valves‘53.1’and‘53.2’, the throttling valves ‘56.1’and‘56.2’as well as the cam-controlled pressure relief valves‘60.1’and‘60.2’connected in parallel.The opening time of the above valves determines the threshold time, it can be adjusted through the throttling valves‘59.1’and‘59.2’in a range of 0.2 and 1.0 s. The minimum pressure valve of the open valves‘60.1’and‘60.2’is equivalent to the residual pressure valve and is limited by the final position of the mechanical cam plate.The residual pressure valve is reached after a prolon-gated threshold time of approx.0.1s.For a fine adjustment of the threshold curve and as an additional safety measure ,two throttling valves‘57’are provided for the respective residual pressure value. These components permit the pressure reduction characteristic (braking curve) to be variably adjusted (depending on requirements) and reproduced at any time.The capacity of the residual pressure accumulator is adapted to the maximum braking time of the winder, under consideration of the opening cross sections of the valves ‘57’and of the leakage rate of all valves. The time of maintaining residual pressure is abt.50% longer than the maximum braking time.When the winder comes to a standstill, a time element is started. After abt.2s, the valve‘63’is opened by a starting pulse and the residual pressure reduced to zero. At the same time, the residual pressure accumulator not needed is discharged through the pressure relief valve‘25.1’or‘25.2’(the valve is energized for a short moment).The possibility of adjusting and reproducing the braking curve between application pressure and residual pressure is of particular importance since, within this period, rope vibrations may occur which, with Koepe winders, may cause a slipping of ropes.The valves‘58’，‘65’，and‘66’as well as‘53’and‘39’are monitored for their position and, prior to the start of the winder releasing the safety brake checked for conformity.Furthermore, the starting and end positions of all curves are checked for conformity and thus also for correct functioning.During the safety braking, the pressure relief valves‘43.1’and‘43.2’remain operative.2.2.5 Releasing the safety brakeSince the control system including the pump motors is de-energized as soon as safety braking is started, the brake control system is in a resting state. The system is depressurized and the brake applied.The power required for the pump motors‘3.1’and‘3.2’and the control system is available.The system can be started when1. the electrical monitoring system does not signal any failure.2.all prerequisites for starting the pumps‘1.1’and‘1.2’are fulfilled.3.conformity of the valves‘39’、‘53’、‘58’、65‘、65’、‘66’and‘89’is given.The system is started and the brake released as described under items 2.2.1and 2.2.2.。

大学本科毕业设计--英文原文+中文翻译

Library of C the CNC industrialdeveloped tens of thousands and educational field, he hasNUMERICAL CONTROLNumerical Control technology as it is known today, emerged in the mid 20th century. It can be traced to the year of 1952, the U.S. Air Force, and the names of John Parsons and the Massachusetts Institute of Technology in Cam-bridge, MA, USA. It was not applied in production manu-facturing until the early 1960's. The real boom came in the form of CNC, around the year of 1972, and a decade later with the introduction of affordable micro computers. The history and development of this fascinating technology has been well documented in many publications.In the manufacturing field, and particularly in the area of metal working, Numerical Control technology has caused something of a revolution. Even in the days before comput-ers became standard fixtures in every company and in many homes, the2machine tools equipped with Numerical Control system found their special place in the machine shops. The recent evolution of micro electronics and the never ceasing computer development, including its impact on Numerical Control, has brought significant changes to the manufacturing sector in general and metalworking in-dustry in particular.DEFINITION OF NUMERICAL CONTROLIn various publications and articles, many descriptions have been used during the years, to define what Numerical Control is. It would be pointless to try to find yet another definition, just for the purpose of this handbook. Many of these definitions share the same idea, same basic concept, just use different wording.The majority of all the known definitions can be summed up into a relatively simple statement:Numerical Control can be defined as an operation of machine tools by the means of specifically coded instructions to the machine control systemThe instructions are combinations of the letters of alpha-bet, digits and selected symbols, for example, a decimal point, the percent sign or the parenthesis symbols. All in-structions are written in a logical order and a predetermined form. The collectionNUMERICAL CONTROLof all instructions necessary to ma-chine a part is called an NC Program, CNC Program, or a Part Program. Such a program can be stored for a future use and used repeatedly to achieve identical machining re-sults at any time.♦ NC and CNC TechnologyIn strict adherence to the terminology, there is a differ-ence in the meaning of the abbreviations NC and CNC. The NC stands for the older and original Numerical Control technology, whereby the abbreviation CNC stands for the newer Computerized Numerical Control technology, a modem spin-off of its older relative. However, in practice, CNC is the preferred abbreviation. To clarify the proper us-age of each term, look at the major differences between the NC and the CNC systems.Both systems perform the same tasks, namely manipula-tion of data for the purpose of machining a part. In both cases, the internal design of the control system contains the logical instructions that process the data. At this point the similarity ends. The NC system (as opposed to the CNC system) uses a fixed logical functions, those that are built-in and perma-nently wired within the control unit. These functions can-not be changed by the programmer or the machine opera-tor. Because of the fixed4wiring of the control logic, the NC control system is synonymous with the term 'hardwired'. The system can interpret a part program, but it does not al-low any changes to the program, using the control features. All required changes must be made away from the control, typically in an office environment. Also, the NC system re-quires the compulsory use of punched tapes for input of the program information.The modem CNC system, but not the old NC system, uses an internal micro processor (i.e., a computer). This computer contains memory registers storing a variety of routines that are capable of manipulating logical functions. That means the part programmer or the machine operator can change the program on the control itself (at the ma-chine), with instantaneous results. This flexibility is the greatest advantage of the CNC systems and probably the key element that contributed to such a wide use of the tech-nology in modern manufacturing. The CNC programs and the logical functions are stored on special computer chips, as software instructions, rather than used by the hardware connections, such as wires, that control the logical func-tions. In contrast to the NC system, the CNC system is syn-onymous with the term 'softwired'.NUMERICAL CONTROLWhen describing a particular subject that relates to the numerical control technology, it is customary to use either the term NC or CNC. Keep in mind that NC can also mean CNC in everyday talk, but CNC can never refer to the older technology, described in this handbook under the abbrevia-tion ofNC. The letter 'C 'stands for Computerized, and it is not applicable to the hardwired system. All control systems manufactured today are of the CNC design. Abbreviations such as C&C or C'n 'C are not correct and reflect poorly on anybody that uses them.CONVENTIONAL AMD CNC MACHININGWhat makes the CNC machining superior to the conven-tional methods? Is it superior at all? Where are the main benefits? If the CNC and the conventional machining pro-cesses are compared, a common general approach to ma-chining a part will emerge: Obtain and study the drawingSelect the most suitable machining methodDecide on the setup method (work holding)Select the cutting toolsEstablish speeds and feedsMachine the part6This basic approach is the same for both types of machin-ing. The major difference is in the way how various data are input. A feedrate of 10 inches per minute (10 in/min) is the same in manual or CNC applications, but the method of applying it is not. The same can be said about a coolant - it can be activated by turning a knob, pushing a switch or programming a special code. All these actions will result in a coolant rushing out of a nozzle. In both kinds of machin-ing, a certain amount of knowledge on the part of the user is required. After all, metal working, particularly metal cut-ting, is mainly a skill, but it is also, to a great degree, an art and a profession of large number of people. So is theappli-cation of Computerized Numerical Control. Like any skill or art or profession, mastering it to the last detail is neces-sary to be successful. It takes more than technical knowl-edge to be a CNC machinist or a CNC programmer. Work experience and intuition, and what is sometimes called a 'gut-feel', is a much needed supplement to any skill.In a conventional machining, the machine operator sets up the machine and moves each cutting tool, using one or both hands, to produce the required part. The design of a manual machine tool offers many features that help the process of machining a part -NUMERICAL CONTROLlevers, handles, gears and di-als, to name just a few. The same body motions are re-peated by the operator for every part in the batch. However, the word 'same 'in this context really means'similar 'rather than 'identical'. Humans are not capable to repeat every process exactly the same at all times - that is the job ofma-chines. People cannot work at the same performance level all the time, without a rest. All of us have some good andsome bad moments. The results of these moments, when*applied to machining a part, are difficult to predict. There will be some differences and inconsistencies within each batch of parts. The parts will not always be exactly the same. Maintaining dimensional tolerances and surface fin-ish quality are the most typical problems in conventional machining. Individual machinists may have their own time 'proven' methods, different from those of their fellow col-leagues. Combination of these and other factors create a great amount of mconsistency.The machining under numerical control does away with the majority of inconsistencies. It does not require the same physical involvement as manual machining. Numerically controlled machining does not need any levers or dials or handles, at least8not in the same sense as conventional ma-chining does. Once the part program has been proven, it can be used any number of times over, always returning consistent results. That does not mean there are no limiting factors. The cutting tools do wear out, the material blank in one batch is not identical to the material blank in another batch, the setups may vary, etc. These factors should be considered and compensated for, whenever necessary.The emergence of the numerical control technology does not mean an instant, or even a long term, demise of all man-ual machines. There are times when a traditional machin-ing method is preferable to a computerized method. For ex-ample, a simple one time job may be done more efficiently on a manual machine than a CNC machine. Certain types of machining jobs will benefit from manual or semiauto-matic machining, rather than numerically controlled ma-chining. The CNC machine tools are not meant to replace every manual machine, only to supplement them.In many instances, the decision whether certain machin-ing will be done on a CNC machine or not is based on the number of required parts and nothing else. Although the volume of partsNUMERICAL CONTROLmachined as a batch is always an important criteria, it should never be the only factor. Consideration should also be given to the part complexity, its tolerances, the required quality of surface finish, etc. Often, a single complex part will benefit from CNC machining, while fifty relatively simple parts will not.Keep in mind that numerical control has never machined a single part by itself. Numerical control is only a process or a method that enables a machine tool to be used in a pro-ductive, accurate and consistent way.NUMERICAL CONTROL ADVANTAGESWhat are the main advantages of numerical control?It is important to know which areas of machining will benefit from it and which are better done the conventional way. It is absurd to think that a two horse power CNC mill will win over jobs that are currently done on a twenty times more powerful manual mill. Equally unreasonable are ex-pectations of great improvements in cutting speeds and feedrates over a conventional machine. If the machining and tooling conditions are the same, the cutting time will be very close in both cases.Some of the major areas where the CNC user can and should expect improvement:10Setup time reductionLead time reductionAccuracy and repeatabilityContouring of complex shapesSimplified tooling and work holdingConsistent cutting timeGeneral productivity increaseEach area offers only a potential improvement. Individ-ual users will experience different levels of actual improve-ment, depending on the product manufactured on-site, the CNC machine used, the setup methods, complexity of fixturing, quality of cutting tools, management philosophy and engineering design, experience level of the workforce, individual attitudes, etc.Setup Time ReductionIn many cases, the setup time for a CNC machine can be reduced, sometimes quite dramatically. It is important to realize that setup is a manual operation, greatly dependent on the performance of CNC operator, the type of fixturing and general practices of the machine shop. Setup time is unproductive, but necessary - it is a part of the overhead costs of doing business. To keep the setupNUMERICAL CONTROLtime to a mini-mum should be one of the primary considerations of any machine shop supervisor, programmer and operator. Because of the design of CNC machines, the setup time should not be a major problem. Modular fixturing, standard tooling, fixed locators, automatic tool changing, pallets and other advanced features, make the setup time more efficient than a comparable setup of a conventional machine. With a good knowledge of modern manufacturing, productivity can be increased significantly.The number of parts machined under one setup is also important, in order to assess the cost of a setup time. If a great number of parts is machined in one setup, the setup cost per part can be very insignificant. A very similar re-duction can be achieved by grouping several different oper-ations into a single setup. Even if the setup time is longer, it may be justified when compared to the time required to setup several conventional machines.Lead Time ReductionOnce a part program is written and proven, it is ready to be Bsed again in the future, even at a short notice. Although the lead time for the first run is usually longer, it is virtually nil for any subsequent run. Even if an engineering change of the part design12requires the program to be modi tied, it can be done usually quickly, reducing the lead time.Long lead time, required to design and manufacture sev-eral special fixtures for conventional machines, can often be reduced by preparing a part program and the use of sim-plified fixturing. Accuracy and RepeatabilityThe high degree of accuracy and repeatability of modern CNC machines has been the single major benefit to many users. Whether the part program is stored on a disk or in the computer memory, or even on a tape (the original method), it always remains the same. Any program can be changed at will, but once proven, no changes are usually required any more. A given program can be reused as many times as needed, without losing a single bit of data it contains. True, program has to allow for such changeable factors as tool wear and operating temperatures, it has to be stored safely, but generally very little interference from the CNC pro-grammer or operator will be required. The high accuracy of CNC machines and their repeatability allows high quality parts to be produced consistently time after time. Contouring of Complex ShapesNUMERICAL CONTROLCNC lathes and machining centers are capable of con-touring a variety of shapes. Many CNC users acquired their machines only to be able to handle complex parts. A good examples are CNC applications in the aircraft and automo-tive industries. The use of some form of computerized pro-gramming is virtually mandatory for any three dimensional tool path generation.Complex shapes, such as molds, can be manufactured without the additional expense of making a model for trac-ing. Mirrored parts can be achieved literally at the switch of a button. Storage of programs is a lot simpler than storage of patterns, templates, wooden models, and other pattern making tools.Simplified Tooling and Work HoldingNonstandard and 'homemade' tooling that clutters the benches and drawers around a conventional machine can be eliminated by using standard tooling, specially designed for numerical control applications. Multi-step tools such as pilot drills, step drills, combination tools, counter borers and others are replaced with several individual standard tools. These tools are often cheaper and easier to replace than special and nonstandard tools.Cost-cutting measures have forced many tool suppliers to keep a low or even a nonexistent inventory, increasing the delivery lime14to the customer. Standard, off-the-shelf tooling can usually beob-tained faster then nonstandard tooling.Fixturing and work holding for CNC machines have only one major purpose - to hold the part rigidly and in the same position for all parts within a batch. Fixtures designed for CNC work do not normally require jigs, pilot holes and other hole locating aids.♦ Cutting Time and Productivity IncreaseThe cutting time on the CNC machine is commonly known as the cycle time - and is always consistent. Unlike a conventional machining, where the operator's skill, experi-ence and personal fatigue are subject to changes, the CNC machining is under the control of a computer. The small amount of manual work is restricted to the setup andload-ing and unloading the part. For large batch runs, the high cost of the unproductive time is spread among many parts, making it less significant. The main benefit of a consistent cutting time is for repetitive jobs, where the production scheduling and work allocation to individual machine tools can be done very accurately.The main reason companies often purchase CNCma-chines is strictly economic - it is a serious investment. Also, having a competitive edge is always on the mind of every plant manager. The numerical control teclmology offers excellent means to achieve a significant improvement in the manufacturing productivity and increasing the overall quality of the manufactured parts. Like any means, it has to be used wisely and knowledgeably. When more and more companies use the CNCtechnology, just having a CNC machine does not offer the extra edge anymore. Thecom-panies that get forward are those who know how to use the technology efficiently and practice it to be competitive in the global economy.To reach the goal of a major increase in productivity, it is essential that users understand the fundamental principles on which CNC technology is based. These principles take many forms, for example, understanding the electronic cir-cuitry, complex ladder diagrams, computer logic, metrol-ogy, machine design, machining principles and practices and many others. Each one has to be studied and mastered by the person in charge. In this handbook, the emphasis is on the topics that relate directly to the CNC programming and understanding the most common CNC machine tools, the Machining Centers and the lathes (sometimes also called the Turning Centers). The part quality consideration should be very important to every programmer and ma-chine tool operator and this goal is also reflected in the handbook approach as well as in the numerous examples.TYPES OF CNC MACHINE TOOLSDifferent kinds of CNCmachines cover an extremelylarge variety. Their numbersare rapidly increasing, as thetechnology developmentadvances. It is impossible toiden-tify all the applications,they would make a long list.Here is a brief list of some ofthe groups CNC machines canbe part of: *Mills and Machining centersLathes and Turning CentersDrilling machines CNC machining centers andlathes dominate the number ofinstallations in industry. Thesetwo groups share the marketjust about equally. Someindustries may have a higherneed for one group ofmachines, depending on their □ Boring mills and Profilers □ EDM machines □ Punch presses and Shears □ Flame cutting machines □ Routers □ Water jet and Laser profilers □ Cylindrical grinders □ Welding machines □ Benders, Winding and Spinning machines, etc.needs. One must remember that there are many different kinds of ladies and equally many different kinds ofma-chining centers. However, the programming process for a vertical machine is similar to the one for a horizontalma-chine or a simple CNC mill. Even between differentma-chine groups, there is a great amount of general applica-tions and the programming process is generally the same. For example, a contour milled with an end mill has a lot in common with a contour cut with a wire.♦ Mills and Machining Centers Standard number of axes on a milling machine is three - the X, Y and Z axes. The part set on a milling system is al-ways stationary, mounted on a moving machine table. The cutting tool rotates, it can move up and down (or in and out), but it does not physically follow the tool path.CNC mills - sometimes called CNC milling machines - are usually small, simple machines, without a tool changer or other automatic features. Their power rating is often quite low. In industry, they are used for toolroom work, maintenance purposes, or small part production. They are usuallydesigned for contouring, unlike CNC drills.CNC machining centers are far more popular and effi-cient than drills and mills, mainly for their flexibility. The main benefit the user gets out of a CNC machining center is the ability to group several diverse operations into a single setup. For example, drilling, boring, counter boring, tap-ping, spot facing and contour milling can be incorporated into a single CNC program. In addition, the flexibility is enhanced by automatic tool changing, using pallets to minimize idle time, indexing to a different side of the part, using a rotary movement of additional axes, and a number of other features. CNC machining centers can be equipped with special software that controls the speeds and feeds, the life of the cutting tool, automatic in-process gauging and offset adjustment and other production enhancing and time saving devices.There are two basic designs of a typical CNC machining center. They are the vertical and the horizontal machining centers. The major difference between the two types is the nature of work that can be done on them efficiently. For a vertical CNC machining center, the most suitable type of work are flat parts, either mounted to the fixture on the ta-ble, or held in a vise or a chuck. The work that requires ma-chining on two or more faces m a single setup is more de-sirable to be done on a CNC horizontal machining center. An good example is a pump housing and other cubic-like shapes. Some multi-face machining of small parts can also be done on a CNC vertical machining center equipped with a rotary table.The programming process is the same for both designs, but an additional axis (usually a B axis) is added to the hori-zontal design. This axis is either a simple positioning axis (indexing axis) for the table, or a fully rotary axis for simul-taneous contouring. This handbook concentrates on the CNC vertical ma-chining centers applications, with a special section dealing with the horizontal setup and machining. The program-ming methods are also applicable to the small CNC mills or drilling and/or tapping machines, but the programmer has to consider their restrictions.♦ Lathes and Turning CentersA CNC lathe is usually a machine tool with two axes, the vertical X axis and the horizontal Z axis. The main feature of a lathe that distinguishes it from a mill is that the part is rotating about the machine center line. In addition, the cut-ting tool is normally stationary, mounted in a sliding turret. The cutting tool follows the contour of the programmed tool path. For the CNC lathes with a milling attachment, so called live tooling, the milling tool has its own motor and rotates while the spindle is stationary.The modem lathe design can be horizontal or vertical. Horizontal type is far more common than the vertical type, but both designs have their purpose in manufacturing. Sev-eral different designs exist for either group. For example, a typical CNC lathe of the horizontal group can be designed with a flat bed or a slant bed, as a bar type, chucker type or a universal type. Added to these combinations are many ac-cessories that make a CNC lathe an extremely flexible ma-chine tool. Typically, accessories such as a tailstock, steady rests or follow-up rests, part catchers,pullout-fingers and even a third axis milling attachment are popular compo-nents of the CNC lathe. ?CNC lathe can be veiy versatile - so versatile in fact, that it is often called a CNC TurningCenter. All text and program examples in this handbook use the more traditional term CNC lathe, yet still recogniz-ing all its modern functions.中文翻译：数控正如我们现在所知，数控技术出现于20世纪中叶。

毕业设计(英文翻译)

附录G：英文翻译参考（要求学生完成与论文有关的外文资料中文字数5000字左右的英译汉，旨在培养学生利用外文资料开展研究工作的能力，为所选课题提供前沿参考资料。

）毕业设计（英文翻译）题目系别：专业：班级：学生姓名：学号：指导教师：一位从事质量管理的人约瑟夫·朱兰出生于圣诞夜,1904 在罗马尼亚的喀尔巴阡山脉山中。

他青年时期的村庄中贫穷、迷信和反犹太主义甚是猖獗。

1912年朱兰家搬到了明尼阿波尼斯州，虽然充满了危险，但是它却让一个男孩充满信心和希望。

从如此多了一个在质量观念的世界最好改革者之一。

在他90年的生活中，朱兰一直是一个精力充沛的思想者倡导者，推动着传统的质量思想向前走。

因为九岁就被雇用,朱兰表示在他的生活工作上永不停止。

记者:技术方面如何讲质量?朱兰:技术有不同方面:一、当然是精密。

物的对精密的需求像电子学、化学…我们看来它们似乎需要放大来说,和重要的原子尘的有关于质量。

要做到高精密具有相当大的挑战，而且我们已经遇见非常大的挑战。

另外的一个方面是可信度－没有失败。

当我们举例来说建立一个系统，同类空中交通管制的时候,我们不想要它失败。

我们必须把可信度建入系统。

因为我们投入很大的资金并依赖这些系统，系统非常复杂，这是逐渐增加的。

除此之外,有对公司的失败费用。

如果事物在领域中意外失败,可以说，它影响民众。

但是如果他们失败在内部,然后它影响公司的费用,而且已经试着发现这些费用在哪里和该如何免除他们。

因此那些是相当大的因素:精密、可信度和费用。

还有其它的,当然，但是我认为这些是主要的一些。

记者:据说是质量有在美国变成一种产业的可能?朱兰:资讯科技当然有。

已经有大的变化。

在世纪中初期当质量的一个想法到一个检验部门的时候，这有了分开的工作，东西被做坏之后。

检验是相当易错的程序,实际上。

而且无论如何，资讯科技在那天中相当花时间，直到某事已经被认为是否资讯科技是正确的。

应该强调计划，如此它不被错误首先订定。

ERDAS帮助文档翻译

本科毕业设计（论文）中英文对照翻译院（系部）资源环境学院专业名称地理信息系统年级班级2001-03学生姓名毛巍指导老师张鸿升二00五年六月十日英文翻译（原文）Introduction to Model MakerA model is a set of instructions that is processed by the IMAGINE Spatial Modeler component for performing GIS and image processing operations.The IMAGINE Model Maker is an editor for creating models using a palette of tools. These tools are used to place graphics representing input data, functions, criteria, and output data on a page to create a graphical model by drawing its flow chart.The Spatial Modeler Language (SML) is a modeling language that is used by Model Maker to execute the operations specified in the graphical models that you create. You can also use the Spatial Modeler Language directly to write your own script models that may be run from the Model Librarian.If a calibrated file is input to a model, output files created by the model will also be calibrated. If a subset of the area of the input file is output, the calibration is adjusted accordingly. If there are any other files input to the model, they must be the same size and have exactly the same calibration information as the first calibrated input file. You cannot input calibrated and georeferenced files together.This documentation explains: General Capabilities, Starting Model Maker, Defining Objects, Using Function Definitions, Specifying Criteria, Output Parameters, Creating a Model, Running a Model, Using the Spatial Modeler LanguageGeneral CapabilitiesModel Maker allows you to write both simple and complex models that incorporate GIS and image processing functions. These include:※mathematical operations on raster layers (adding, subtracting, multiplying, ratioing, or other image algebra functions),※convolution filtering,※neighborhood analyses (analyzing a pixel based on the values of neighboring pixels),※subsetting and mosaicking,※principal components analysis, and※contiguity analysis.The results of a model (an output file) can be written to a file, automatically opened in a Viewer window, or both.Internal checks within Model Maker help you create valid models from the beginning.Starting Model MakerYou can access Model Maker by selecting the Model Maker option from the Spatial Modeler dialog. To access this dialog, click this icon on the ERDAS IMAGINE icon panel:Model Maker PartsThe parts of the Model Maker window and palette of tools are explained in the following illustration:Mostly, you will be working with:※ objects — (see below) the data upon which you operate or create※function definitions — the instructions that you compose on how the data are to be manipulated.These are explained below.ObjectsAn object is an input to or an output from a function. The four basic object types used in Model Maker are described below.ScalarA scalar object is simply a single numeric value.TableA table object is a series of numeric values or character strings. A table has one column and a fixed number of rows. Tables are typically used to store columns from an attribute table, or a list of values which pertain to the individual layers of a raster layerset.A table may consist of up to 32,767 rows. Information in the table can be attributes, calculated (e.g., histograms), or user-defined.MatrixA matrix object is a set of numbers arranged in a two dimensional array. A matrixhas a fixed number of rows and columns. Matrices may be used to store convolution kernels or the neighborhood definition used in neighborhood functions. They can also be used to store covariance matrices, eigenvector matrices, or matrices of linear combination coefficients.※ See the “Enhancement” chapter of the ERDAS Field Guide for more information about convolution filtering.Normalized Matrix ObjectYou have the option to normalize the matrix in the Matrix dialog. Normalizing the matrix replaces the cell values of the matrix with the values divided by the sum of all values of the matrix except when the sum is zero.For example, a 3 x 3 matrix of:1 1 11 1 11 1 1...is used to average the pixels in an image. If these values were actually used, the output pixel values would be 9 times larger than expected.The real matrix used to average the pixel values is:1/9 1/9 1/91/9 1/9 1/91/9 1/9 1/9For either custom or built-in input matrices, the default is to normalize the matrix which is usually desired for convolution filtering. If you are entering a matrix of coefficients for a function such as LINEARCOMB, you may want to turn off the Normalize check box. For output matrices, normalization is turned off.RasterA raster object is a single layer or layerset of raster data. Rasters are typically used to contain and manipulate data from image files.VectorA vector object is either an Arc/Info Coverage or an Annotation Layer.Data TypesThe objects above may be of the following data types:※ Binary - either 0 (false) or 1 (true)※ Integer - integer values from -2,147,483,648 to 2,147,483,647 (signed 32-bit integer)※Float - floating point data (double precision)Table objects may also use the following data type:※ String - a character string.Defining Objects in a ModelIn a model, objects are used as:※ input to a function definition, to be operated upon※output, the result(s) of your model.ConnectionsWhether an object is input or output is specified by how you connect each object to a function definition.※ By making a connection from an object to a function definition, you specify that object as input to the function definition.※ By making a connection from a function definition to an object, you specify that object as output from the function definition.Of course, function definitions can be chained together in complex models, and therefore an object can be both input and output.Objects (rasters, matrices, tables, and scalars) may be connected only to functions, and functions may be connected only to objects. Connections which would form a circular path in the model are not allowed.Model Maker will not let you connect a function to more than one output. If you try to draw a connector to a second output, the connector to the first output will disappear.As you move object and function graphics in the Model Maker window, the connection arrows also move accordingly.You can remove a connection by using the connector tool and simply drawing in the reverse direction (i.e., from function to object).Input ObjectsFollow these steps to define input objects in a model:1. Decide upon which objects you need to operate to create one output. These will be your input objects. Often, there will be only one or two input objects.2. For each input object, select the appropriate object tool (Raster , Matrix, Table ,or Scalar ) from the Model Tools palette, and place the object graphic in the Model Maker window. You can rearrange these graphics any time.3. Double-click on each object graphic in the Model Maker window to open the appropriate dialog for defining that object. The Raster, Matrix, Table, or Scalar dialog is opened.4. Use the Function tool from the Model Tools palette to place a function graphic in your model. Position your graphics so that a line can be drawn from each input object graphic to the function graphic.5. Select the Connector tool from the Model Tools palette. Click on an input object graphic and drag the connector to the function graphic. Repeat for each input object.Now your input objects are defined so that you can create a function definition with those objects.Output ObjectsFollow these steps to define an output object:There can be only one output object for each function definition. There can, however, be many function definitions in a model.1. If needed, use the Function tool in the Model Tools palette to place a function graphic in your model.2. Select the appropriate object tool for your output (Raster , Matrix ,Table , or Scalar ) from the Model Tools palette, and place the object graphic in the Model Maker window. The type of object that you select will depend upon the function definition.3. Select the Connector tool in the Model Tools palette. Click on the function graphic and drag the connector to the output object graphic.Function DefinitionsObjects used in a Model Maker model are operated upon with function definitions that you write with the Model Maker. The function definition is an expression (like “a + b + c”) that defines your output. You will use a variety of mathematical, statistical, Boolean, neighborhood, and other functions, plus the input objects that you set up, to write a function definition.To create a function definition, follow these steps:1. Define your input objects, following the steps above. You should have your input objects defined, and all connections made from the input objects to the function graphic.2. Double-click on the function graphic. The Function Definition dialog is opened. Use this dialog to compose a function definition.You should define all input objects to a function before you double-click on the function graphic. Then, the inputs you specified will be listed in the Function Definition dialog. You can then select the input objects from a list in the dialog as you compose your function definition.Recoding Raster ObjectsIf the purpose of your model is to recode only, you can set up the recode in the Raster dialog and you do not need to select a function in the Function dialog. Place the input raster graphic on the page, set up the recode when defining the raster and connect this graphic to the function graphic. Then connect the function graphic to an output raster graphic.Within the function definition, you simply click on the input raster which will be recoded and copied to the output raster.Using the Function Definition DialogInput ObjectsThe Available Inputs list in the dialog shows all of the input objects that are available for your function definition. These are the inputs that are connected to the function as inputs. To change this list, change the objects that are connected to the function.To use an input object in your function definition, click on the object name in this list. It will be displayed in the text field at the cursor location.FunctionsUsing the popup list and the scrolling list of functions, you can select functions according to function categories. The function categories and the functions in each category are documented in the Spatial Modeler Language on-line manual. When you click a function from the scrolling list, it is opened in the text field at the cursor location.The simplest function definition is a copy. A copy requires no functions. Just click on an available input object in the list, so that your function definition consists only of the input object name. When the model is executed, this will simply copy the selected input to the output object. This is useful when all you want to do to a raster is recode it.Prototype ArgumentsMany functions in the scrolling list have prototypes, which are short descriptions of the appropriate input objects or values upon which that function operates. Prototypes are surrounded by < > brackets. You must replace a prototype with an object or value.After you place a function int o the function definition text field, click in a function’s prototype to position the cursor within the brackets. Then click the desired input object, and it will automatically replace the prototype.Specifying CriteriaThe Criteria function in Model Maker gives you the power of the CONDITIONAL function within the Spatial Modeler Language. You can use the Criteria function to build a table of conditions which must be satisfied to output a particular row value for a descriptor (or cell value) associated with the raster you select. Double-click the criteria graphic in an existing model to define the criteria with theCriteria dialog. To establish a new Criteria function, click the icon on the Model Maker tool palette.The inputs to a Criteria function are rasters. The columns of the Criteria table represent either descriptors associated with a raster layer, or the layer itself if the cell values are of direct interest. Criteria which must be met for each output column are entered in a cell in that column (e.g., >5). Multiple sets of criteria may be entered in multiple rows. The output raster will contain the first row number of a set of criteria that were met for a raster cell.ExampleThe example below illustrates how you can use the Criteria function.If des criptors of “Acreage” and “Class Name” are available and a map of pine forests larger than 10 acres is desired: both “Acreage” and “Class Name” are added as column titles in the Criteria dialog. In the cell under “Acreage,” “>10” is entered and under “Class Name,” “Pine” is entered. In this one row example, a pixel value of one is output for pixels that satisfy both criteria.To take this example further, if more than one acreage class is desired, a row is added to the criteria table for each size class des ired. Under “Acreage” in the first row “>50” might be entered and in the second row “>10.” The first row in which the criteria are satisfied will be the output pixel value, thus the relational expressions should be more restrictive as you go down the rows.Output ParametersSince you can have several inputs in one model, you have the option to define the working window and the cell size of the output data.Default settings for these parameters can be set in the Preference Editor. Working WindowYou can input raster layers of differing areas into one model. However, you must specify the image area (or working window) to use in the model calculation. Select one of three options:※ Union - the model will operate on the union of all input rasters.※ Intersection - the model will use only the area of the rasters that is common to all input rasters.※ Other - specify the working window in explicit coordinates.The default setting is union. To change this parameter, under Model on the Model Maker menu bar, click Set Window and the Set Window dialog is opened. Cell SizeInput rasters may also be of differing resolutions (pixel size), so you must also select the output file cell size as either:※Minimum - the minimum cell size of the input layers will be used. This is the default setting.※Maximum - the maximum cell size of the input layers will be used.※Other - specify a new cell size.To change the cell size, under Model on the Model Maker menu bar, click Set Cell Size. The Set Cell Size dialog is opened.Creating a ModelThere are several graphical models included with ERDAS IMAGINE in the<$IMAGINE_HOME>/etc/models directory. You can load these models to run them or edit them to create new models.Creating a New ModelThere are two basic ways to create a new model:※ edit an existing model,※ create a model from “scratch.”Edit an Existing ModelOpen an existing model, either one that was delivered with IMAGINE, or one that you previously created. Select File | Open in the Model Maker menu bar and select the model to view. Doubleclick on any of the graphics in the model to redefine them. You can change the inputs used, select another function to use, etc.Then, select File | Save As from the Model Maker menu bar. Enter a new name for your model.Using the Spatial Modeler LanguageThe Spatial Modeler Language is a language designed for advanced modeling and includes over 200 functions and operators. Models can be created in a text file and run from a command line, or from within ERDAS IMAGINE.The Spatial Modeler Language encompasses all functions available in Model Maker as well as:※ conditional branching and looping※ complex and color data types※ more flexibility in using raster objects and descriptorsGraphical models created with Model Maker can be output to a script file (text only) in the Spatial Modeler Language. These scripts can then be edited with a text editor using the Modeler Language syntax and re-run or saved in a library. Generating a ScriptModels created with Model Maker can be saved as a script file (text only) by selecting Process | Generate Script on the Model Maker menu bar.You can access this script from the Model Librarian option of the Spatial Modeler.Through the Model Librarian, you can Edit, Run, or Delete models.The Edit option brings up a text editor where you can use the Modeler Language to write new or edit existing models.Spatial ModelerSpatial Modeler enables you to create and run models for image processing and GIS analysis. It is a highly flexible tool which uses Model Maker and the Spatial Modeler Language.The Spatial Modeler Language is a modeling language that is used internally by Model Maker to execute the operations specified in the graphical models that you create. You can also use the Spatial Modeler Language directly to write your own script models.Click this icon on the ERDAS IMAGINE icon panel to access Spatial Modeler:Model Maker... Click to open the Model Maker window and the Model Maker Tool palette. This window allows you to work with graphical models. You can view or edit existing models and create new models.Script Librarian... Click to open the Model Librarian dialog. This dialog lists all the existing script models in the system. Using this option, you can view, edit, create, and delete script models.Close Click to close this dialog.Help Click to open this On-Line Help document.※ For information on using the ERDAS IMAGINE graphical interface, see the on-line IMAGINE Interface manual.※ See the ERDAS IMAGINE Tour Guides manual for step-by-step instructions on using Model Maker.※ See the on-line Spatial Modeler Language manual for more information about creating script models.英文翻译（译文）模型生成器的介绍一个模型就是一系列指示，它在IMAGINE软件的空间建模组件中被处理，从而运行地理信息系统和图像处理操作。

毕业设计论文翻译（译文+原文）

Hacking tricks toward security on network environments Tzer-Shyong Chen1, Fuh-Gwo Jeng 2, and Yu-Chia Liu 11 Department of Information Management, Tunghai University, Taiwan2 Department of Applied Mathematics, National Chiayi University, TaiwanE-Mail:****************.edu.twAbstractMounting popularity of the Internet has led to the birth of Instant Messaging, an up-and-coming form of Internet communication. Instant Messaging is very popular with businesses and individuals since it has instant communication ability. As a result, Internet security has become a pressing and important topic for discussion. Therefore, in recent years, a lot of attention has been drawn towards Internet security and the various attacks carried out by hackers over the Internet. People today often handle affairs via the Internet. For instance, instead of the conventional letter, they communicate with others by e-mails; they chat with friends through an instant messenger; find information by browsing websites instead of going to the library; perform e-commerce transactions through the Internet, etc. Although the convenience of the Internet makes our life easier, it is also a threat to Internet security. For instance, a business email intercepted during its transmission may let slip business confidentiality; file transfers via instant messengers may also be intercepted, and then implanted with backdoor malwares; conversations via instant messengers could be eavesdropped. Furthermore, ID and password theft may lose us money when using Internet bank service. Attackers on the Internet use hacking tricks to damage systems while users are connected to the Internet. These threats along with possible careless disclosure of business information make Instant Messaging a very unsafe method of communication for businesses. The paper divides hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing or fraud via e-mails. (3) Fake Websites. Keywords:Hacking tricks, Trojan programs, Phishing, Firewall, Intrusion detection system.1. IntroductionIncreasingly more people are using instant messengers such as MSN Messenger, Yahoo! Messenger, ICQ, etc as the media of communication. These instant messengers transmit alphanumeric message as well as permit file sharing. During transfer, a file may be intercepted by a hacker and implanted with backdoor malware. Moreover, the e-mails users receive every day may include Spam, advertisements, and fraudulent mail intended to trick uninformed users. Fake websites too are prevalent. Websites which we often visit could be counterfeited by imitating the interface and the URL of the original, tricking users. The paper classifies hacking tricks into three categories which are explained in the following sections.2. Hacking TricksThe paper divides hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing (3) Fake Websites.2.1 Trojan programs that share files via instant messengerInstant messaging allows file-sharing on a computer [9]. All present popular instant messengers have file sharing abilities, or allow users to have the above functionality by installing patches or plug-ins; this is also a major threat to present information security. These communication softwares also makeit difficult for existing hack prevention methods to prevent and control information security. Therefore, we shall discuss how to control the flow of instant messages and how to identify dangerous user behavior.Hackers use instant communication capability to plant Trojan program into an unsuspected program; the planted program is a kind of remotely controlled hacking tool that can conceal itself and is unauthorized. The Trojan program is unknowingly executed, controlling the infected computer; it can read, delete, move and execute any file on the computer. The advantages of a hacker replacing remotely installed backdoor Trojan programs [1] with instant messengers to access files are:When the victim gets online, the hacker will be informed. Thus, a hacker can track and access the infected computer, and incessantly steal user information.A hacker need not open a new port to perform transmissions; he can perform his operations through the already opened instant messenger port.Even if a computer uses dynamic IP addresses, its screen name doesn’t change.Certain Trojan programs are designed especially for instant messengers. These Trojans can change group settings and share all files on the hard disk of the infected computer. They can also destroy or modify data, causing data disarray. This kind of program allows a hacker access to all files on an infected computer, and thus poses a great threat to users. The Trojan program takes up a large amount of the resources of the computer causing it to become very slow and often crashes without a reason.Trojan programs that access a user computer through an instant messenger are probably harder to detect than classic Trojan horse programs. Although classic Trojan intrudes a computer by opening a listening or outgoing port which is used to connect toa remote computer, a desktop firewall can effectively block such Trojans. Alternatively, since it is very difficult for the server’s firewall to spot intrusion by controlling an instant messenger’s flow, it is extremely susceptible to intrusion.Present Trojan programs have already successfully implemented instant messengers. Some Trojan programs are Backdoor Trojan, AIMVision, and Backdoor. Sparta.C. Backdoor Trojans use ICQ pager to send messages to its writer. AIMVision steals AIM related information stored in the Windows registry, enabling a hacker to setup an AIM user id. Backdoor. Sparta.C uses ICQ to communicate with its writer and opens a port on an infected host and send its IP Address to the hacker, and at the same time attempts to terminate the antivirus program or firewall of the host.2.1.1 Hijacking and ImpersonationThere are various ways through which a hacker can impersonate other users [7]. The most commonly used method is eavesdropping on unsuspecting users to retrieve user accounts, passwords and other user related information.The theft of user account number and related information is a very serious problem in any instant messenger. For instance, a hacker after stealing a user’s information impersonate the user; the user’s contacts not knowing that the user’s account has been hacked believe that the person they’re talking to is the user, and are persuaded to execute certain programs or reveal confidential information. Hence, theft of user identity not only endangers a user but also surrounding users. Guarding against Internet security problems is presently the focus of future research; because without good protection, a computer can be easily attacked, causing major losses.Hackers wishing to obtain user accounts may do so with the help of Trojans designed to steal passwords. If an instant messenger client stores his/her password on his/her computer, then a hacker can send a Trojan program to the unsuspecting user. When the user executes the program, the program shall search for the user’s password and send it to the hacker. There are several ways through which a Trojan program can send messages back to the hacker. The methods include instant messenger, IRC, e-mails, etc.Current four most popular instant messengers are AIM, Yahoo! Messenger, ICQ, and MSN Messenger, none of which encrypts its flow. Therefore, a hackercan use a man-in-the-middle attack to hijack a connection, then impersonate the hijacked user and participate in a chat-session. Although difficult, a hacker can use the man-in-the-middle attack to hijack the connection entirely. For example, a user may receive an offline message that resembles that sent by the server, but this message could have been sent by the hacker. All at once, the user could also get disconnected to the server. Furthermore, hackers may also use a Denial of Service (DoS) tool or other unrelated exploits to break the user’s connection. However, the server keeps the connection open, and does not know that the user has been disconnected; thus allowing the hacker to impersonate the user. Moreover, since the data flow is unencrypted and unauthenticated, a hacker can use man-in-the-middle attacks that are similar to that of ARP fraud to achieve its purpose.2.1.2 Denial of Service (DoS)There are many ways through which a hacker can launch a denial of service (DoS) attack [2] on an instant messenger user. A Partial DoS attack will cause a user end to hang, or use up a large portion of CPU resources causing the system to become unstable.Another commonly seen attack is the flooding of messages to a particular user. Most instant messengers allow the blocking of a particular user to prevent flood attacks. However, a hacker can use tools that allow him to log in using several different identities at the same time, or automatically create a large number of new user ids, thus enabling a flood attack. Once a flood attack begins, even if the user realizes that his/her computer has been infected, the computer will not be able to respond. Thus, the problem cannot be solved by putting a hacker’s user id on the ignore list of your instant messenger.A DoS attack on an instant messenger client is only a common hacking tool. The difficulty of taking precautions against it could turn this hacking tool into dangerous DoS type attacks. Moreover, some hacking tools do not just cause an instant messenger client to hang, but also cause the user end to consume large amount of CPU time, causing the computer to crash.2.1.3 Information DisclosureRetrieving system information through instant messenger users is currently the most commonly used hacking tool [4]. It can effortlessly collect user network information like, current IP, port, etc. IP address retriever is an example. IP address retrievers can be used to many purposes; for instance, a Trojan when integrated with an IP address retriever allows a hacker to receive all information related to the infected computer’s IP address as soon as the infected computer connects to the internet. Therefore, even if the user uses a dynamic IP address, hackers can still retrieve the IP address.IP address retrievers and other similar tools can also be used by hackers to send data and Trojans to unsuspecting users. Hackers may also persuade unsuspecting users to execute files through social engineering or other unrelated exploits. These files when executed search for information on the user’s computer and sends them back to the hacker through the instant messenger network.Different Trojan programs were designed for different instant messaging clients. For example, with a user accounts and password stealing Trojans a hacker can have full control of the account once the user logs out. The hacker can thus perform various tasks like changing the password and sending the Trojan program to all of the user’s contacts.Moreover, Trojans is not the only way through which a hacker can cause information disclosure. Since data sent through instant messengers are unencrypted, hackers can sniff and monitor entire instant messaging transmissions. Suppose an employee of an enterprise sends confidential information of the enterprise through the instant messenger; a hacker monitoring the instant messaging session can retrieve the data sent by the enterprise employee. Thus, we must face up to the severity of the problem.2.2 PhishingThe word “Phishing” first appeared in 1996. It is a variant of ‘fishing’, and formed by replacing the ‘f’ in ‘fishing’ with ‘ph’ from phone. It means tricking users of their money through e-mails.Based on the statistics of the Internet Crime Complaint Center, loss due to internet scam was as high as $1.256 million USD in 2004. The Internet Crime Complaint Center has listed the above Nigerian internet scam as one of the ten major internet scams.Based on the latest report of Anti-Phishing Working Group (APWG) [8], there has been a 28% growth of Phishing scams in the past 4 months, mostly in the US and in Asia. Through social engineering and Trojans, it is very difficult for a common user to detect the infection.To avoid exploitation of your compassion, the following should be noted:(1)When you need to enter confidentialinformation, first make sure that theinformation is entered via an entirely secureand official webpage. There are two ways todetermine the security of the webpage:a.The address displayed on the browserbegins with https://, and not http://. Payattention to if the letter ‘s’ exists.b.There is a security lock sign on the lowerright corner of the webpage, and whenyour mouse points to the sign, a securitycertification sign shall appear.(2)Consider installing a browser security softwarelike SpoofStick which can detect fake websites.(3)If you suspect the received e-mail is a Phishinge-mail, do not open attachments attached to theemail. Opening an unknown attachment couldinstall malicious programs onto your computer.(4)Do not click on links attached to your emails. Itis always safer to visit the website through theofficial link or to first confirm the authenticityof the link. Never follow or click on suspiciouslinks in an e-mail. It is advisable to enter theURL at the address bar of the web browser,and not follow the given link.Generally speaking, Phishing [3] [5] is a method that exploits people’s sympathy in the form of aid-seeking e-mails; the e-mail act as bait. These e-mails usually request their readers to visit a link that seemingly links to some charitable organization’s website; but in truth links the readers to a website that will install a Trojan program into the reader’s computer. Therefore, users should not forward unauthenticated charity mails, or click on unfamiliar links in an e-mail. Sometimes, the link could be a very familiar link or an often frequented website, but still, it would be safer if you’d type in the address yourself so as to avoid being linked to a fraudulent website. Phisher deludes people by using similar e-mails mailed by well-known enterprises or banks; these e-mails often asks users to provide personal information, or result in losing their personal rights; they usually contain a counterfeit URL which links to a website where the users can fillin the required information. People are often trapped by phishing due to inattentionBesides, you must also be careful when using a search engine to search for donations and charitable organizations.2.3 Fake WebsitesFake bank websites stealing account numbers and passwords have become increasingly common with the growth of online financial transactions. Hence, when using online banking, we should take precautions like using a secure encrypted customer’s certificate, surf the net following the correct procedure, etc.There are countless kinds of phishing baits, for instance, messages that say data expired, data invalid, please update data, or identity verification intended to steal account ID and matching password. This typeof online scam is difficult for users to identify. As scam methods become finer, e-mails and forged websites created by the impostor resemble their original, and tremendous losses arise from the illegal transactions.The following are methods commonly used by fake websites. First, the scammers create a similar website homepage; then they send out e-mails withenticing messages to attract visitors. They may also use fake links to link internet surfers to their website. Next, the fake website tricks the visitors into entering their personal information, credit card information or online banking account number and passwords. After obtaining a user’s information, the scammers can use the information to drain the bank accounts, shop online or create fake credit cards and other similar crimes. Usually, there will be a quick search option on these fake websites, luring users to enter their account number and password. When a user enters their account number and password, the website will respond with a message stating that the server is under maintenance. Hence, we must observe the following when using online banking:(1)Observe the correct procedure for entering abanking website. Do not use links resultingfrom searches or links on other websites.(2)Online banking certifications are currently themost effective security safeguard measure. (3)Do not easily trust e-mails, phone calls, andshort messages, etc. that asks for your accountnumber and passwords.Phishers often impost a well-known enterprise while sending their e-mails, by changing the sender’s e-mail address to that of the well known enterprise, in order to gain people’s trust. The ‘From’ column of an e-mail is set by the mail software and can be easily changed by the web administrator. Then, the Phisher creates a fake information input website, and send out e-mails containing a link to this fake website to lure e-mail recipients into visiting his fake website.Most Phishers create imitations of well known enterprises websites to lure users into using their fake websites. Even so, a user can easily notice that the URL of the website they’re entering has no relation to the intended enterprise. Hence, Phishers may use different methods to impersonate enterprises and other people. A commonly used method is hiding the URL. This can easily be done with the help of JavaScript.Another way is to exploit the loopholes in an internet browser, for instance, displaying a fake URL in the browser’s address bar. The security loophole causing the address bar of a browser to display a fake URL is a commonly used trick and has often been used in the past. For example, an e-mail in HTML format may hold the URL of a website of a well-known enterprise, but in reality, the link connects to a fake website.The key to successfully use a URL similar to that of the intended website is to trick the visual senses. For example, the sender’s address could be disguised as that of Nikkei BP, and the link set to http://www.nikeibp.co.jp/ which has one k less than the correct URL which is http://www.nikkeibp.co.jp/. The two URLs look very similar, and the difference barely noticeable. Hence people are easily tricked into clicking the link.Besides the above, there are many more scams that exploit the trickery of visual senses. Therefore, you should not easily trust the given sender’s name and a website’s appearance. Never click on unfamiliar and suspicious URLs on a webpage. Also, never enter personal information into a website without careful scrutiny.3. ConclusionsBusiness strategy is the most effective form of defense and also the easiest to carry out. Therefore, they should be the first line of defense, and not last. First, determine if instant messaging is essential in the business; then weigh its pros and cons. Rules and norms must be set on user ends if it is decided that the business cannot do without instant messaging functionality. The end server should be able to support functions like centralized logging and encryption. If not, then strict rules must be drawn, and carried out by the users. Especially, business discussions must not be done over an instant messenger.The paper categorized hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing (3) Fake Websites. Hacking tricks when successfully carried out could cause considerable loss and damage to users. The first category of hacking tricks can be divided into three types: (1) Hijacking and Impersonation; (2) Denial of Service; (3) Information Disclosure.Acknowledgement:This work was supported by the National Science Council, Taiwan, under contract No. NSC 95-2221-E-029-024.References[1] B. Schneier, “The trojan horse race,”Communications of ACM, Vol. 42, 1999, pp.128.[2] C. L. Schuba, “Analysis of a denial of serviceattack on TCP,” IEEE Security and PrivacyConference, 1997, pp. 208-223.[3] E. Schultz, “Phishing is becoming moresophisticated,” Computer and Security, Vol.24(3), 2005, pp. 184-185.[4]G. Miklau, D. Suciu, “A formal analysis ofinformation disclosure in data exchange,”International Conference on Management ofData, 2004, pp. 575-586.[5]J. Hoyle, “'Phishing' for trouble,” Journal ofthe American Detal Association, Vol. 134(9),2003, pp. 1182-1182.[6]J. Scambray, S. McClure, G. Kurtz, Hackingexposed: network security secrets and solutions,McGraw-Hill, 2001.[7]T. Tsuji and A. Shimizu, “An impersonationattack on one-time password authenticationprotocol OSPA,” to appear in IEICE Trans.Commun, Vol. E86-B, No.7, 2003.[8]Anti-Phishing Working Group,.[9]/region/tw/enterprise/article/icq_threat.html.有关网络环境安全的黑客技术摘要：现在人们往往通过互联网处理事务。

办公楼毕业设计英文翻译(外文翻译)

In 1980 the Level House, designed by Skidmore, Owings and Merril1 (SOM) received the 25-year award from the American Institute of Architects “in recognition of architectural design of enduring significance”. This award is given once a year for a building between 25and 35 years old .Lewis Mumford described the Lever House as “the first office building in which modern materials, modern construction, modern functions have been combined with a modern plan”. At the time, this daring concept could only be achieved by visionary men like Gordon Bunshaft , the designer , and Charles Luckman , the owner and then-president of Lever Brothers . The project also included a few “first” : (1) it was the first sealed glass tower ever built ; (2) it was the first office building designed by SOM ;and (3) it was the first office building on Park Avenue to omit retail space on the first floor. Today, after hundreds of look-alike and variations on the grid design, we have reached what may be the epitome of tall building design: the nondescript building. Except for a few recently completed buildings that seem to be people-oriented in their lower floors, most tall buildings seem to be a repletion of the dull, graph-paper-like monoliths in many of our cities. Can this be the end of the design-line for tall buildings? Probably not. There are definite signs that are most encouraging. Architects and owners have recently begun to discuss the design problem publicly. Perhaps we are at the threshold of a new era. The 1980s may bring forth some new visionaries like Bunshaft and Luckman. If so, what kinds of restrictions or challenges do they face? 译文：来自高层建筑展望及建筑结构

毕业设计外文翻译英文

Bid Compensation Decision Model for Projectswith Costly Bid PreparationS.Ping Ho,A.M.ASCE 1Abstract:For projects with high bid preparation cost,it is often suggested that the owner should consider paying bid compensation to the most highly ranked unsuccessful bidders to stimulate extra effort or inputs in bid preparation.Whereas the underlying idea of using bid compensation is intuitively sound,there is no theoretical basis or empirical evidence for such suggestion.Because costly bid preparation often implies a larger project scale,the issue of bid compensation strategy is important to practitioners and an interest of study.This paper aims to study the impacts of bid compensation and to develop appropriate bid compensation strategies.Game theory is applied to analyze the behavioral dynamics between competing bidders and project owners.A bid compensation model based on game theoretic analysis is developed in this study.The model provides equilibrium solutions under bid compensation,quantitative formula,and quali-tative implications for the formation of bid compensation strategies.DOI:10.1061/(ASCE )0733-9364(2005)131:2(151)CE Database subject headings:Bids;Project management;Contracts;Decision making;Design/build;Build/Operate/Transfer;Construction industry .IntroductionAn often seen suggestion in practice for projects with high bid preparation cost is that the owner should consider paying bid compensation,also called a stipend or honorarium,to the unsuc-cessful bidders.For example,according to the Design–build Manual of Practice Document Number 201by Design–Build In-stitute of America (DBIA )(1996a ),it is suggested that that “the owner should consider paying a stipend or honorarium to the unsuccessful proposers”because “excessive submittal require-ments without some compensation is abusive to the design–build industry and discourages quality teams from participating.”In another publication by DBIA (1995),it is also stated that “it is strongly recommended that honorariums be offered to the unsuc-cessful proposers”and that “the provision of reasonable compen-sation will encourage the more sought-after design–build teams to apply and,if short listed,to make an extra effort in the prepara-tion of their proposal.”Whereas bid preparation costs depend on project scale,delivery method,and other factors,the cost of pre-paring a proposal is often relatively high in some particular project delivery schemes,such as design–build or build–operate–transfer (BOT )contracting.Plus,costly bid preparation often im-plying a large project scale,the issue of bid compensation strat-egy should be important to practitioners and of great interest of study.Existing research on the procurement process in constructionhas addressed the selection of projects that are appropriate for certain project delivery methods (Molenaar and Songer 1998;Molenaar and Gransberg 2001),the design–build project procure-ment processes (Songer et al.1994;Gransberg and Senadheera 1999;Palaneeswaran and Kumaraswamy 2000),and the BOT project procurement process (United Nations Industrial Develop-ment Organization 1996).However,the bid compensation strat-egy for projects with a relatively high bid preparation cost has not been studied.Among the issues over the bidder’s response to the owner’s procurement or bid compensation strategy,it is in own-er’s interest to understand how the owner can stimulate high-quality inputs or extra effort from the bidder during bid prepara-tion.Whereas the argument for using bid compensation is intuitively sound,there is no theoretical basis or empirical evi-dence for such an argument.Therefore,it is crucial to study under what conditions the bid compensation is effective,and how much compensation is adequate with respect to different bidding situa-tions.This paper focuses on theoretically studying the impacts of bid compensation and tries to develop appropriate compensation strategies for projects with a costly bid preparation.Game theory will be applied to analyze the behavioral dynamics between com-peting bidders.Based on the game theoretic analysis and numeric trials,a bid compensation model is developed.The model pro-vides a quantitative framework,as well as qualitative implica-tions,on bid compensation strategies.Research Methodology:Game TheoryGame theory can be deﬁned as “the study of mathematical models of conﬂict and cooperation between intelligent rational decision-makers”(Myerson 1991).Among economic theories,game theory has been successfully applied to many important issues such as negotiations,ﬁnance,and imperfect markets.Game theory has also been applied to construction management in two areas.Ho (2001)applied game theory to analyze the information asymme-try problem during the procurement of a BOT project and its1Assistant Professor,Dept.of Civil Engineering,National Taiwan Univ.,Taipei 10617,Taiwan.E-mail:spingho@.twNote.Discussion open until July 1,2005.Separate discussions must be submitted for individual papers.To extend the closing date by one month,a written request must be ﬁled with the ASCE Managing Editor.The manuscript for this paper was submitted for review and possible publication on March 5,2003;approved on March 1,2004.This paper is part of the Journal of Construction Engineering and Management ,V ol.131,No.2,February 1,2005.©ASCE,ISSN 0733-9364/2005/2-151–159/$25.00.D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y N A N J I N G U N I VE R S I T Y OF o n 01/06/14. C o p y r i g h t A S C E . F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .implication in project ﬁnancing and government policy.Ho and Liu (2004)develop a game theoretic model for analyzing the behavioral dynamics of builders and owners in construction claims.In competitive bidding,the strategic interactions among competing bidders and that between bidders and owners are com-mon,and thus game theory is a natural tool to analyze the prob-lem of concern.A well-known example of a game is the “prisoner’s dilemma”shown in Fig.1.Two suspects are arrested and held in separate cells.If both of them confess,then they will be sentenced to jail for 6years.If neither confesses,each will be sentenced for only 1year.However,if one of them confesses and the other does not,then the honest one will be rewarded by being released (in jail for 0year )and the other will be punished for 9years in jail.Note that in each cell,the ﬁrst number represents player No.1’s payoff and the second one represents player No.2’s.The prisoner’s dilemma is called a “static game,”in which they act simultaneously;i.e.,each player does not know the other player’s decision before the player makes the decision.If the payoff matrix shown in Fig.1is known to all players,then the payoff matrix is a “common knowledge”to all players and this game is called a game of “complete information.”Note that the players of a game are assumed to be rational;i.e.,to maximize their payoffs.To answer what each prisoner will play/behave in this game,we will introduce the concept of “Nash equilibrium ,”one of the most important concepts in game theory.Nash equilibrium is a set of actions that will be chosen by each player.In a Nash equilib-rium,each player’s strategy should be the best response to the other player’s strategy,and no player wants to deviate from the equilibrium solution.Thus,the equilibrium or solution is “strate-gically stable”or “self-enforcing”(Gibbons 1992).Conversely,a nonequilibrium solution is not stable since at least one of the players can be better off by deviating from the nonequilibrium solution.In the prisoner’s dilemma,only the (confess,confess )solution where both players choose to confess,satisﬁes the stabil-ity test or requirement of Nash equilibrium.Note that although the (not confess,not confess )solution seems better off for both players compared to Nash equilibrium;however,this solution is unstable since either player can obtain extra beneﬁt by deviating from this solution.Interested readers can refer to Gibbons (1992),Fudenberg and Tirole (1992),and Myerson (1991).Bid Compensation ModelIn this section,the bid compensation model is developed on the basis of game theoretic analysis.The model could help the ownerform bid compensation strategies under various competition situ-ations and project characteristics.Illustrative examples with nu-merical results are given when necessary to show how the model can be used in various scenarios.Assumptions and Model SetupTo perform a game theoretic study,it is critical to make necessary simpliﬁcations so that one can focus on the issues of concern and obtain insightful results.Then,the setup of a model will follow.The assumptions made in this model are summarized as follows.Note that these assumptions can be relaxed in future studies for more general purposes.1.Average bidders:The bidders are equally good,in terms oftheir technical and managerial capabilities.Since the design–build and BOT focus on quality issues,the prequaliﬁcation process imposed during procurement reduces the variation of the quality of bidders.As a result,it is not unreasonable to make the “average bidders”assumption.plete information:If all players consider each other tobe an average bidder as suggested in the ﬁrst assumption,it is natural to assume that the payoffs of each player in each potential solution are known to all players.3.Bid compensation for the second best bidder:Since DBIA’s(1996b )manual,document number 103,suggests that “the stipend is paid only to the most highly ranked unsuccessful offerors to prevent proposals being submitted simply to ob-tain a stipend,”we shall assume that the bid compensation will be offered to the second best bidder.4.Two levels of efforts:It is assumed that there are two levelsof efforts in preparing a proposal,high and average,denoted by H and A ,respectively.The effort A is deﬁned as the level of effort that does not incur extra cost to improve quality.Contrarily,the effort H is deﬁned as the level of effort that will incur extra cost,denoted as E ,to improve the quality of a proposal,where the improvement is detectable by an effec-tive proposal evaluation system.Typically,the standard of quality would be transformed to the evaluation criteria and their respective weights speciﬁed in the Request for Pro-posal.5.Fixed amount of bid compensation,S :The ﬁxed amount canbe expressed by a certain percentage of the average proﬁt,denoted as P ,assumed during the procurement by an average bidder.6.Absorption of extra cost,E :For convenience,it is assumedthat E will not be included in the bid price so that the high effort bidder will win the contract under the price–quality competition,such as best-value approach.This assumption simpliﬁes the tradeoff between quality improvement and bid price increase.Two-Bidder GameIn this game,there are only two qualiﬁed bidders.The possible payoffs for each bidder in the game are shown in a normal form in Fig.2.If both bidders choose “H ,”denoted by ͑H ,H ͒,both bidders will have a 50%probability of wining the contract,and at the same time,have another 50%probability of losing the con-tract but being rewarded with the bid compensation,S .As a re-sult,the expected payoffs for the bidders in ͑H ,H ͒solution are ͑S /2+P /2−E ,S /2+P /2−E ͒.Note that the computation of the expected payoff is based on the assumption of the average bidder.Similarly,if the bidders choose ͑A ,A ͒,the expected payoffswillFig.1.Prisoner’s dilemmaD o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y N A N J I N G U N I VE R S I T Y OF o n 01/06/14. C o p y r i g h t A S C E . F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .be ͑S /2+P /2,S /2+P /2͒.If the bidders choose ͑H ,A ͒,bidder No.1will have a 100%probability of winning the contract,and thus the expected payoffs are ͑P −E ,S ͒.Similarly,if the bidders choose ͑A ,H ͒,the expected payoffs will be ͑S ,P −E ͒.Payoffs of an n -bidder game can be obtained by the same reasoning.Nash EquilibriumSince the payoffs in each equilibrium are expressed as functions of S ,P ,and E ,instead of a particular number,the model will focus on the conditions for each possible Nash equilibrium of the game.Here,the approach to solving for Nash equilibrium is to ﬁnd conditions that ensure the stability or self-enforcing require-ment of Nash equilibrium.This technique will be applied throughout this paper.First,check the payoffs of ͑H ,H ͒solution.For bidder No.1or 2not to deviate from this solution,we must haveS /2+P /2−E ϾS →S ϽP −2E͑1͒Therefore,condition (1)guarantees ͑H ,H ͒to be a Nash equilib-rium.Second,check the payoffs of ͑A ,A ͒solution.For bidder No.1or 2not to deviate from ͑A ,A ͒,condition (2)must be satisﬁedS /2+P /2ϾP −E →S ϾP −2E͑2͒Thus,condition (2)guarantees ͑A ,A ͒to be a Nash equilibrium.Note that the condition “S =P −2E ”will be ignored since the con-dition can become (1)or (2)by adding or subtracting an inﬁnitely small positive number.Thus,since S must satisfy either condition (1)or condition (2),either ͑H ,H ͒or ͑A ,A ͒must be a unique Nash equilibrium.Third,check the payoffs of ͑H ,A ͒solution.For bid-der No.1not to deviate from H to A ,we must have P −E ϾS /2+P /2;i.e.,S ϽP −2E .For bidder No.2not to deviate from A to H ,we must have S ϾS /2+P /2−E ;i.e.,S ϾP −2E .Since S cannot be greater than and less than P −2E at the same time,͑H ,A ͒solution cannot exist.Similarly,͑A ,H ͒solution cannot exist either.This also conﬁrms the previous conclusion that either ͑H ,H ͒or ͑A ,A ͒must be a unique Nash equilibrium.Impacts of Bid CompensationBid compensation is designed to serve as an incentive to induce bidders to make high effort.Therefore,the concerns of bid com-pensation strategy should focus on whether S can induce high effort and how effective it is.According to the equilibrium solu-tions,the bid compensation decision should depend on the mag-nitude of P −2E or the relative magnitude of E compared to P .If E is relatively small such that P Ͼ2E ,then P −2E will be positive and condition (1)will be satisﬁed even when S =0.This means that bid compensation is not an incentive for high effort when the extra cost of high effort is relatively low.Moreover,surprisingly,S can be damaging when S is high enough such that S ϾP −2E .On the other hand,if E is relatively large so that P −2E is negative,then condition (2)will always be satisﬁed since S can-not be negative.In this case,͑A ,A ͒will be a unique Nash equi-librium.In other words,when E is relatively large,it is not in the bidder’s interest to incur extra cost for improving the quality of proposal,and therefore,S cannot provide any incentives for high effort.To summarize,when E is relatively low,it is in the bidder’s interest to make high effort even if there is no bid compensation.When E is relatively high,the bidder will be better off by making average effort.In other words,bid compensation cannot promote extra effort in a two-bidder game,and ironically,bid compensa-tion may discourage high effort if the compensation is too much.Thus,in the two-bidder procurement,the owner should not use bid compensation as an incentive to induce high effort.Three-Bidder GameNash EquilibriumFig.3shows all the combinations of actions and their respective payoffs in a three-bidder game.Similar to the two-bidder game,here the Nash equilibrium can be solved by ensuring the stability of the solution.For equilibrium ͑H ,H ,H ͒,condition (3)must be satisﬁed for stability requirementS /3+P /3−E Ͼ0→S Ͼ3E −P͑3͒For equilibrium ͑A ,A ,A ͒,condition (4)must be satisﬁed so that no one has any incentives to choose HS /3+P /3ϾP −E →S Ͼ2P −3E͑4͒In a three-bidder game,it is possible that S will satisfy conditions (3)and (4)at the same time.This is different from the two-bidder game,where S can only satisfy either condition (1)or (2).Thus,there will be two pure strategy Nash equilibria when S satisﬁes conditions (3)and (4).However,since the payoff of ͑A ,A ,A ͒,S /3+P /3,is greater than the payoff of ͑H ,H ,H ͒,S /3+P /3−E ,for all bidders,the bidder will choose ͑A ,A ,A ͒eventually,pro-vided that a consensus between bidders of making effort A can be reached.The process of reaching such consensus is called “cheap talk,”where the agreement is beneﬁcial to all players,and no player will want to deviate from such an agreement.In the design–build or BOT procurement,it is reasonable to believe that cheap talk can occur.Therefore,as long as condition (4)is satis-ﬁed,͑A ,A ,A ͒will be a unique Nash equilibrium.An important implication is that the cheap talk condition must not be satisﬁed for any equilibrium solution other than ͑A ,A ,A ͒.In other words,condition (5)must be satisﬁed for all equilibrium solution except ͑A ,A ,A͒Fig.2.Two-biddergameFig.3.Three-bidder gameD o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y N A N J I N G U N I VE R S I T Y OF o n 01/06/14. C o p y r i g h t A S C E . F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .S Ͻ2P −3E ͑5͒Following this result,for ͑H ,H ,H ͒to be unique,conditions (3)and (5)must be satisﬁed;i.e.,we must have3E −P ϽS Ͻ2P −3E͑6͒Note that by deﬁnition S is a non-negative number;thus,if one cannot ﬁnd a non-negative number to satisfy the equilibrium con-dition,then the respective equilibrium does not exist and the equi-librium condition will be marked as “N/A”in the illustrative ﬁg-ures and tables.Next,check the solution where two bidders make high efforts and one bidder makes average effort,e.g.,͑H ,H ,A ͒.The ex-pected payoffs for ͑H ,H ,A ͒are ͑S /2+P /2−E ,S /2+P /2−E ,0͒.For ͑H ,H ,A ͒to be a Nash equilibrium,S /3+P /3−E Ͻ0must be satisﬁed so that the bidder with average effort will not deviate from A to H ,S /2+P /2−E ϾS /2must be satisﬁed so that the bidder with high effort will not deviate from H to A ,and condi-tion (5)must be satisﬁed as argued previously.The three condi-tions can be rewritten asS Ͻmin ͓3E −P ,2P −3E ͔andP −2E Ͼ0͑7͒Note that because of the average bidder assumption,if ͑H ,H ,A ͒is a Nash equilibrium,then ͑H ,A ,H ͒and ͑A ,H ,H ͒will also be the Nash equilibria.The three Nash equilibria will constitute a so-called mixed strategy Nash equilibrium,denoted by 2H +1A ,where each bidder randomizes actions between H and A with certain probabilities.The concept of mixed strategy Nash equilib-rium shall be explained in more detail in next section.Similarly,we can obtain the requirements for solution 1H +2A ,condition (5)and S /2+P /2−E ϽS /2must be satisﬁed.The requirements can be reorganized asS Ͻ2P −3EandP −2E Ͻ0͑8͒Note that the conﬂicting relationship between “P −2E Ͼ0”in condition (7)and “P −2E Ͻ0”in condition (8)seems to show that the two types of Nash equilibria are exclusive.Nevertheless,the only difference between 2H +1A and 1H +2A is that the bidder in 2H +1A equilibrium has a higher probability of playing H ,whereas the bidder in 1H +2A also mixes actions H and A but with lower probability of playing H .From this perspective,the difference between 2H +1A and 1H +2A is not very distinctive.In other words,one should not consider,for example,2H +1A ,to be two bidders playing H and one bidder playing A ;instead,one should consider each bidder to be playing H with higher probabil-ity.Similarly,1H +2A means that the bidder has a lower probabil-ity of playing H ,compared to 2H +1A .Illustrative Example:Effectiveness of Bid Compensation The equilibrium conditions for a three-bidder game is numerically illustrated and shown in Table 1,where P is arbitrarily assumed as 10%for numerical computation purposes and E varies to rep-resent different costs for higher efforts.The “*”in Table 1indi-cates that the zero compensation is the best strategy;i.e.,bid compensation is ineffective in terms of stimulating extra effort.According to the numerical results,Table 1shows that bid com-pensation can promote higher effort only when E is within the range of P /3ϽE ϽP /2,where zero compensation is not neces-sarily the best strategy.The question is that whether it is beneﬁ-cial to the owner by incurring the cost of bid compensation when P /3ϽE ϽP /2.The answer to this question lies in the concept and deﬁnition of the mix strategy Nash equilibrium,2H +1A ,as explained previously.Since 2H +1A indicates that each bidderwill play H with signiﬁcantly higher probability,2H +1A may already be good enough,knowing that we only need one bidder out of three to actually play H .We shall elaborate on this concept later in a more general setting.As a result,if the 2H +1A equilib-rium is good enough,the use of bid compensation in a three-bidder game will not be recommended.Four-Bidder Game and n-Bidder GameNash Equilibrium of Four-Bidder GameThe equilibrium of the four-bidder procurement can also be ob-tained.As the number of bidders increases,the number of poten-tial equilibria increases as well.Due to the length limitation,we shall only show the major equilibria and their conditions,which are derived following the same technique applied previously.The condition for pure strategy equilibrium 4H ,is4E −P ϽS Ͻ3P −4E͑9͒The condition for another pure strategy equilibrium,4A ,isS Ͼ3P −4E͑10͒Other potential equilibria are mainly mixed strategies,such as 3H +1A ,2H +2A ,and 1H +3A ,where the numeric number asso-ciated with H or A represents the number of bidders with effort H or A in a equilibrium.The condition for the 3H +1A equilibrium is3E −P ϽS Ͻmin ͓4E −P ,3P −4E ͔͑11͒For the 2H +2A equilibrium the condition is6E −3P ϽS Ͻmin ͓3E −P ,3P −4E ͔͑12͒The condition for the 1H +3A equilibrium isS Ͻmin ͓6E −3P ,3P −4E ͔͑13͒Illustrative Example of Four-Bidder GameTable 2numerically illustrates the impacts of bid compensation on the four-bidder procurement under different relative magni-tudes of E .When E is very small,bid compensation is not needed for promoting effort H .However,when E grows gradually,bid compensation becomes more effective.As E grows to a larger magnitude,greater than P /2,the 4H equilibrium would become impossible,no matter how large S is.In fact,if S is too large,bidders will be encouraged to take effort A .When E is extremely large,e.g.,E Ͼ0.6P ,the best strategy is to set S =0.The “*”in Table 2also indicates the cases that bid compensation is ineffec-Table pensation Impacts on a Three-Bidder GameEquilibriumE ;P =10%3H 2H +1A 1H +2A 3A E ϽP /3e.g.,E =2%S Ͻ14%*N/A N/N 14%ϽS P /3ϽE ϽP /2e.g.,E =4%2%ϽS Ͻ8%S Ͻ2%N/A 8%ϽS P /2ϽE Ͻ͑2/3͒P e.g.,E =5.5%N/AN/AS Ͻ3.5%*3.5%ϽS͑2/3͒P ϽEe.g.,E =7%N/A N/A N/A Always*Note:*denotes that zero compensation is the best strategy;and N/A =the respective equilibrium does not exist.D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y N A N J I N G U N I VE R S I T Y OF o n 01/06/14. C o p y r i g h t A S C E . F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .tive.To conclude,in a four-bidder procurement,bid compensation is not effective when E is relatively small or large.Again,similar to the three-bidder game,when bid compensation becomes more effective,it does not mean that offering bid compensation is the best strategy,since more variables need to be considered.Further analysis shall be performed later.Nash Equilibrium of n -Bidder GameIt is desirable to generalize our model to the n -bidder game,al-though only very limited qualiﬁed bidders will be involved in most design–build or BOT procurements,since for other project delivery methods it is possible to have many bidders.Interested readers can follow the numerical illustrations for three-and four-bidder games to obtain the numerical solutions of n -bidder game.Here,only analytical equilibrium solutions will be solved.For “nA ”to be the Nash equilibrium,we must have P −E ϽS /n +P /n for bidder A not to deviate.In other words,condition (14)must be satisﬁedS Ͼ͑n −1͒P −nE͑14͒Note that condition (14)can be rewritten as S Ͼn ͑P −E ͒−P ,which implies that it is not likely for nA to be the Nash equilib-rium when there are many bidders,unless E is very close to or larger than P .Similar to previous analysis,for “nH ”to be the equilibrium,we must have S /n +P /n −E Ͼ0for stability requirement,and condition (15)for excluding the possibility of cheap talk or nA equilibrium.The condition for the nH equilibrium can be reorga-nized as condition (16).S Ͻ͑n −1͒P −nE ͑15͒nE −P ϽS Ͻ͑n −1͒P −nE͑16͒Note that if E ϽP /n ,condition (16)will always be satisﬁed and nH will be a unique equilibrium even when S =0.In other words,nH will not be the Nash equilibrium when there are many bidders,unless E is extremely small,i.e.,E ϽP /n .For “aH +͑n −a ͒A ,where 2Ͻa Ͻn ”to be the equilibrium so-lution,we must have S /a +P /a −E Ͼ0for bidder H not to devi-ate,S /͑a +1͒+P /͑a +1͒−E Ͻ0for bidder A not to deviate,and condition (15).These requirements can be rewritten asaE −P ϽS Ͻmin ͓͑a +1͒E −P ,͑n −1͒P −nE ͔͑17͒Similarly,for “2H +͑n −2͒A ,”the stability requirements for bidder H and A are S /͑n −1͒ϽS /2+P /2−E and S /3+P /3−E Ͻ0,re-spectively,and thus the equilibrium condition can be written as ͓͑n −1͒/͑n −3͔͒͑2E −P ͒ϽS Ͻmin ͓3E −P ,͑n −1͒P −nE ͔͑18͒For the “1H +͑n −1͒A ”equilibrium,we must haveS Ͻmin ͕͓͑n −1͒/͑n −3͔͒͑2E −P ͒,͑n −1͒P −nE ͖͑19͒An interesting question is:“What conditions would warrant that the only possible equilibrium of the game is either “1H +͑n −1͒A ”or nA ,no matter how large S is?”A logical response to the question is:when equilibria “aH +͑n −a ͒A ,where a Ͼ2”and equilibrium 2H +͑n −2͒A are not possible solutions.Thus,a suf-ﬁcient condition here is that for any S Ͼ͓͑n −1͒/͑n −3͔͒͑2E −P ͒,the “S Ͻ͑n −1͒P −nE ”is not satisﬁed.This can be guaranteed if we have͑n −1͒P −nE Ͻ͓͑n −1͒/͑n −3͔͒͑2E −P ͒→E Ͼ͓͑n −1͒/͑n +1͔͒P͑20͒Conditions (19)and (20)show that when E is greater than ͓͑n −1͒/͑n +1͔͒P ,the only possible equilibrium of the game is either 1H +͑n −1͒A or nA ,no matter how large S is.Two important practical implications can be drawn from this ﬁnding.First,when n is small in a design–build contract,it is not unusual that E will be greater than ͓͑n −1͒/͑n +1͔͒P ,and in that case,bid compensa-tion cannot help to promote higher effort.For example,for a three-bidder procurement,bid compensation will not be effective when E is greater than ͑2/4͒P .Second,when the number of bidders increases,bid compensation will become more effective since it will be more unlikely that E is greater than ͓͑n −1͒/͑n +1͔͒P .The two implications conﬁrm the previous analyses of two-,three-,and four-bidder game.After the game equilibria and the effective range of bid compensation have been solved,the next important task is to develop the bid compensation strategy with respect to various procurement situations.Table pensation Impacts on a Four-Bidder GameEquilibriumE ;P =10%4H 3H +1A 2H +2A 1H +3A 4A E ϽP /4e.g.,E =2%S Ͻ22%*N/A N/A N/A S Ͼ22%P /4ϽE ϽP /3e.g.,E =3%2%ϽS Ͻ18%S Ͻ2%N/A N/A S Ͼ18%P /3ϽE ϽP /2e.g.,E =4%6%ϽS Ͻ14%2%ϽS Ͻ6%S Ͻ2%N/A S Ͼ14%P /2ϽE Ͻ͑3/5͒P e.g.,E =5.5%N/A 6.5%ϽS Ͻ8%3%ϽS Ͻ6.5%S Ͻ3%S Ͼ8%͑3/5͒P ϽE Ͻ͑3/4͒P e.g.,E =6.5%N/AN/AN/AS Ͻ4%*S Ͼ4%͑3/4͒P ϽEe.g.,E =8%N/A N/A N/A N/AAlways*Note:*denotes that zero compensation is the best strategy;and N/A=respective equilibrium does not exist.D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y N A N J I N G U N I VE R S I T Y OF o n 01/06/14. C o p y r i g h t A S C E . F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .。

毕业设计论文外文文献翻译智能交通信号灯控制中英文对照

英语原文Intelligent Traffic Light Controlby Marco Wiering The topic I picked for our community project was traffic lights. In a community, people need stop signs and traffic lights to slow down drivers from going too fast. If there were no traffic lights or stop signs, people’s lives would be in danger from drivers going too fast.The urban traffic trends towards the saturation, the rate of increase of the road of big city far lags behind rate of increase of the car.The urban passenger traffic has already become the main part of city traffic day by day and it has used about 80% of the area of road of center district. With the increase of population and industry activity, people's traffic is more and more frequent, which is unavoidable. What means of transportation people adopt produces pressure completely different to city traffic. According to calculating, if it is 1 to adopt the area of road that the public transport needs, bike needs 5-7, car needs 15-25, even to walk is 3 times more than to take public transits. So only by building road can't solve the city traffic problem finally yet. Every large city of the world increases the traffic policy to the first place of the question.For example，according to calculating, when the automobile owning amount of Shanghai reaches 800,000 (outside cars count separately ), if it distributes still as now for example: center district accounts for great proportion, even when several loop-lines and arterial highways have been built up , the traffic cannot be improved more than before and the situation might be even worse. So the traffic policy Shanghai must adopt , or called traffic strategy is that have priority to develop public passenger traffic of city, narrow the scope of using of the bicycle progressively , control the scale of growth of the car traffic in the center district, limit the development of the motorcycle strictly.There are more municipals project under construction in big city. the influence on the traffic is greater.Municipal infrastructure construction is originally a good thing of alleviating the traffic, but in the course of constructing, it unavoidably influence the local traffic. Some road sections are blocked, some change into an one-way lane, thus the vehicle can only take a devious route . The construction makes the road very narrow, forming the bottleneck, which seriously influence the car flow.When having stop signs and traffic lights, people have a tendency to drive slower andlook out for people walking in the middle of streets. To put a traffic light or a stop sign in a community, it takes a lot of work and planning from the community and the city to put one in. It is not cheap to do it either. The community first needs to take a petition around to everyone in the community and have them sign so they can take it to the board when the next city council meeting is. A couple residents will present it to the board, and they will decide weather or not to put it in or not. If not put in a lot of residents might be mad and bad things could happened to that part of the city.When the planning of putting traffic lights and stop signs, you should look at the subdivision plan and figure out where all the buildings and schools are for the protection of students walking and riding home from school. In our plan that we have made, we will need traffic lights next to the school, so people will look out for the students going home. We will need a stop sign next to the park incase kids run out in the street. This will help the protection of the kids having fun. Will need a traffic light separating the mall and the store. This will be the busiest part of the town with people going to the mall and the store. And finally there will need to be a stop sign at the end of the streets so people don’t drive too fast and get in a big accident. If this is down everyone will be safe driving, walking, or riding their bikes.In putting in a traffic light, it takes a lot of planning and money to complete it. A traffic light cost around $40,000 to $125,000 and sometimes more depending on the location. If a business goes in and a traffic light needs to go in, the business or businesses will have to pay some money to pay for it to make sure everyone is safe going from and to that business. Also if there is too many accidents in one particular place in a city, a traffic light will go in to safe people from getting a severe accident and ending their life and maybe someone else’s.The reason I picked this part of our community development report was that traffic is a very important part of a city. If not for traffic lights and stop signs, people’s lives would be in danger every time they walked out their doors. People will be driving extremely fast and people will be hit just trying to have fun with their friends. So having traffic lights and stop signs this will prevent all this from happening.Traffic in a city is very much affected by traffic light controllers. When waiting for a traffic light, the driver looses time and the car uses fuel. Hence, reducing waiting times before traffic lights can save our European society billions of Euros annually. To make traffic light controllers more intelligent, we exploit the emergence of novel technologies such as communication networks and sensor networks, as well as the use of more sophisticated algorithms for setting traffic lights. Intelligent traffic light control does not only mean thattraffic lights are set in order to minimize waiting times of road users, but also that road users receive information about how to drive through a city in order to minimize their waiting times. This means that we are coping with a complex multi-agent system, where communication and coordination play essential roles. Our research has led to a novel system in which traffic light controllers and the behaviour of car drivers are optimized using machine-learning methods.Our idea of setting a traffic light is as follows. Suppose there are a number of cars with their destination address standing before a crossing. All cars communicate to the traffic light their specific place in the queue and their destination address. Now the traffic light has to decide which option (ie, which lanes are to be put on green) is optimal to minimize the long-term average waiting time until all cars have arrived at their destination address. The learning traffic light controllers solve this problem by estimating how long it would take for a car to arrive at its destination address (for which the car may need to pass many different traffic lights) when currently the light would be put on green, and how long it would take if the light would be put on red. The difference between the waiting time for red and the waiting time for green is the gain for the car. Now the traffic light controllers set the lights in such a way to maximize the average gain of all cars standing before the crossing. To estimate the waiting times, we use 'reinforcement learning' which keeps track of the waiting times of individual cars and uses a smart way to compute the long term average waiting times using dynamic programming algorithms. One nice feature is that the system is very fair; it never lets one car wait for a very long time, since then its gain of setting its own light to green becomes very large, and the optimal decision of the traffic light will set his light to green. Furthermore, since we estimate waiting times before traffic lights until the destination of the road user has been reached, the road user can use this information to choose to which next traffic light to go, thereby improving its driving behaviour through a city. Note that we solve the traffic light control problem by using a distributed multi-agent system, where cooperation and coordination are done by communication, learning, and voting mechanisms. To allow for green waves during extremely busy situations, we combine our algorithm with a special bucket algorithm which propagates gains from one traffic light to the next one, inducing stronger voting on the next traffic controller option.We have implemented the 'Green Light District', a traffic simulator in Java in which infrastructures can be edited easily by using the mouse, and different levels of road usage can be simulated. A large number of fixed and learning traffic light controllers have already been tested in the simulator and the resulting average waiting times of cars have been plotted and compared. The results indicate that the learning controllers can reduce average waiting timeswith at least 10% in semi-busy traffic situations, and even much more when high congestion of the traffic occurs.We are currently studying the behaviour of the learning traffic light controllers on many different infrastructures in our simulator. We are also planning to cooperate with other institutes and companies in the Netherlands to apply our system to real world traffic situations. For this, modern technologies such as communicating networks can be brought to use on a very large scale, making the necessary communication between road users and traffic lights possible.中文翻译：智能交通信号灯控制马克·威宁我所选择的社区项目主题是交通灯。

毕业设计英文翻译中英文对照版

Feasibility assessment of a leading-edge-flutter wind power generator前缘颤振风力发电机的可行性评估Luca Caracoglia卢卡卡拉克格里亚Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering Center, 360 Huntington A venue, Boston, MA 02115, USA美国东北大学土木与环境工程斯内尔工程中心400，亨廷顿大道360，波士顿02115This study addresses the preliminary technical feasibility assessment of a mechanical apparatus for conversion of wind energy. 这项研究涉及的是风能转换的机械设备的初步技术可行性评估。

The proposed device, designated as ‘‘leading-edge-fl utter wind power generator’’, employs aeroelastic dynamic instability of a blade airfoil, torsionally rotating about its leading edge. 这种被推荐的定义为“前缘颤振风力发电机”的设备，采用的气动弹性动态不稳定叶片翼型，通过尖端旋转产生扭矩。

Although the exploitation of aeroelastic phenomena has been proposed by the research community for energy harvesting, this apparatus is compact, simple and marginally susceptible to turbulence and wake effects.虽然气动弹性现象的开发已经有研究界提出可以通过能量采集。

本科毕业设计翻译英文

( 1. Faculty of Civil Engineering & Geosciences, Delft University of Technology , P. O. Box 5048,2600 GA Delft, t he Nether lands; 2. Key Laboratory of Silicate Materials Science and Engineering of the Ministry of Education, Wuhan University of Technology, Wuhan 430070, China)Abstract: Coal tar, a by- product from the destructive distillation of coal in co king oven, is widely used in road engineering for its excellent adhesion and fuel resistance properties, especially for pavement surface treatments in gas stations and airports.However, coal tar has a high Poly cyclic Aromatic Hydro carbons ( or PAHs) content, which makes it toxic.I n 1985, the International Agency for Research on Cancer ( IARC) has proved that coal tar is carcinogenic to humans. Research showed that Coal Tar- based Sealers ( CTS) contribute to the majority of PAHs pollution in the water environment. Because of this environmental concern, CT S are not allowed in many dev eloped countries in the USA and Europe. In contrast, coal tar is still used for road engineering in China and is even used increasingly .This paper gives a literature review on the general information and research about environmental concern of using coal tar in road engineering. Based on the review , some possible alternatives to replace coal tar are described. These alternatives include nanoclay/ epoxy modified bitumen/ bitumen emulsion and waterborne polyuret hane/ epoxy resin, which are environmental friendly. They have the potential to perform as w ell as CTS, and even better in some special applications.Key words:coal tar; pavement surface treatment; adhesion property; poly cyclic aromatic hydrocarbons; modified bitumen emulsionCLC number: U 416 Document code: A Article ID: 1671- 4431( 2010) 17- 0001- 07Received date: 2010- 05- 07.Biography : Xiao Y( 1986- ) , Ph D Candidate. E-mail: yue. xiao@1 introductionTwo basic types of binders are currently used in the pavement surface treatment market: coal tar-based and bitumen-based. At some places like g as stat ions and airports, coal tar-based surface sealers performed much better than bitumen-based sealers with regards to adhesion properties and chemical resistance. Coal tar-based have better resistance to petroleum oils and inorganic acids, and have better moisture resistance[ Austin, 2005] .Because of these out standing properties, CTS are widely used in road engineering for pavement surfacetreatment for many years. However, coal tar is a complex hydrocarbon mixture consisting of hundred of PAH[SCHER, 2008] . These PAHs are toxic and considered human carcinogens. Because of it s environmental unfriendly properties, coal tar is not allowed in most of the developed counties like the Netherlands. In the Netherlands,use of tar containing product s is not allowed since 20 years, with one temporary except ion for antiskid runways in airfields [ van Leest , 2005] . But after 2010, it w ill not be allowed for airport pavement application anymore. Compared to these bans, coal tar is still used for road engineering in China. China Coal Tar Industry Report mentioned that the coal tar consumption w ill be on the upward t rend [CCTIR, 2008] .Based on new technologies like nano technology and two-component technology, other materials are developed for pavement surface treatment and they perform w ell. Modified bitumen emulsions, which can be applied at low temperatures, were successfully used in South Africa, Australia and many other countries. Additives such as polymers ( SBS, SBR and EVA ) , clays ( illite, kaolinite and montmorillonite ) are known to improve the properties of bitumen emulsions in special road applications [ TRB-EC102, 2006;Xiao, 2010] . With the waterborne two-component technology, coating manufacturers can producehigh-performance sealers and achieve the same or better properties than solvent-based sealers. Furthermore, waterborne resins for coating s usually do not contain or just contain a small amounts of other solvent s, indicating that waterborne two component systems are environmental friendly. Epoxy modified bitumen w as originally developed in the late 1950s by Shell Oil Company as a material designed to withstand fuel exposure [ Thom, 2006] . After full curing , epoxy modified bitumen mixture has high temperature stability and strength, excellent fatigue, superior adhesion and rutting resistance.In this paper, a short literature review is given on the use and properties of CTS for pavement surface treatment and its environmental concern. After that several possible alternatives are discussed, such as nanoclay modified bitumen emulsion, epoxy modified bitumen, waterborne polyurethane/ epoxy resin. These alternatives may have good properties and are environmental friendly.2 Use and Advantages of Coal Tar Based SealersCoal tar-based products are used in many industries, for example pavement engineering, the building industry and medical treatment s. In pavement engineering , one of the largest applications is CTS.Coal tar can be used as a binder and filler in surface treatment formulations, and as a modifier for epoxyresin surface coating s. T he streets of Baghdad w ere the first to be paved with tar from the 8th century AD. Tar was a vital component of the first sealed, or tarmac roads. The first tar macadam road with a tar-bound surface was placed in 1848 out side Nottingham, England. In Washington D. C. some of thetar-bound surface courses have a service life of about 30 years.Coal tar is a very complex mixture of chemicals. It s molecular structure is quite different from bitumen.Some of the constituents are described as PAHs. Being stable in molecular structure, these chemicals are incompatible with oil and gas, and provide a barrier coat to protect asphalt surfaces against the destructive effects of petroleum based products and chemicals [Aust in, 2005] . CTS have a better chemical resistance than bitumen based, extremely low permeability to moisture and a high resistance to ultraviolet radiation. These properties make it ideally suited for parking areas w here concentrations of oil and gasoline leaks are prevalent, like gas stations, truck and bus terminals and airport s. CTS are used to extend the life and reduce maintenance cost associated with asphalt pavements, primarily in asphalt road pavement. They are typically used at airports for aprons, taxiways and runways. The Federal Aviation Administration Advisory Circular 150/ 5370-10A Standards for Specifying Construction of Airports include a requirement for pavement sealers that they should contain at least 35% coal tar in runway asphalt pavement.The reason for this requirement is that CTS have a much better resistance to jet fuel than bitumen-based sealers [Austin, 2005].3 Environmental ConcernGenerally, coal tars consist of a mixture of many organic compounds, like benzene, toluene, phenol, naphthalene, anthracite , and others. The risk assessment of coal tar is largely based on PAHs, especially on Benzo (a) pyrene . PAHs are the most relevant component s in terms of toxicity in coal tarproducts[ SCHER, 2008] .3. 1 Polycyclic aromatic hydrocarbonsPolycyclic aromatic hydrocarbons are also known as polycyclic aromatic compounds, polyaromatic hydrocarbons or as polynuclear aromatics. PAHs are a group of over 100 different chemicals consisting of carbon and hydrogen in fused-ring structures. T able 1 shows several typical chemical structures of PAHs. PAHs are highly toxic and harmful to human and ecosystem health [Austin, 2005] . The content of PAHs in coal tar increases as the carbonization temperature increases.3.2 Environmental riskIn 1985, IARC has pointed out that coal tar pitches are carcinogenic in humans [IARC, 1985] . In 2008,three scientific commit tees ( SCCP, the Scientific Commit -tee on Consumer Products; SCHER, the Scientific Committee on Health and Environmental Risks; SCEN IHR, the Scientific Commit tee on Emerging and NewlyIdentified Health Risks) concluded that cancer risk was the most serious point of coal tar s risk characterizations [ SCHER, 2008] . Occupational exposure to coal tar increases the risk of developing skin cancer and other tissue sites , like lung, bladder, kidney and digestive tract . According to the IARC, products that include more than 5 percent of crude coal tar are Group 1 carcinogen which has sufficient evidence of carcinogenicity in humans. So, many countries all over the world have eliminated it s usage.In 2003, scientist s from the city of Austin ( USA ) identified CTS as a significant source of PAHs contamination. The United States Geological Survey and Austin City have conducted additional research that corroborates this finding, concluding that coal tar sealants are responsible for the majority of PAHs pollution in water environment in the Austin area. Coal tar-based pavement sealers are considered as a source of urban water pollution. These are long-lasting substances that can build up in the food chain to harmful levels to humans. Based on their investigations, Austin became the first city in the USA to ban the use of CTS for pavements [ Austin,2005; Mahler, 2005] .As a precaution, in Germany, manufacturers have voluntarily agreed to ban coal tar from their product s. In the Netherlands, coal tar containing products did not meet the Dutch Environmental Standards and w ill not be allowed for airport pavement after 2010.4 Possible AlternativesAccording to these environmental concerns, alternatives are required. These alternatives should have atleast comparable or better properties than CTS. At the same time, they should be environmental friendly. In this section, the possible use of modified bitumen emulsions, epoxy modified bitumen and waterborne resins are discussed.4. 1 Modified bitumen emulsionsBitumen emulsions are heterogeneous systems with two or more liquid phases, consisting of a continuous liquid phase ( water ) and at least one second liquid phase ( bitumen) dispersed in the former as fine droplets [ TRB-EC102, 2006] . Standard bitumen emulsions are normally considered to be of the oil in water type and contain from 40% to 75% bitumen, 0. 1% to 2. 5% emulsifier, 25% to 60% water plus some minor components. The bitumen droplets rang e from 0. 1 to 20 micron in diameter.4. 1. 1 Properties of modified bitumen emulsionsUnlike bitumen, bitumen emulsions do not need to be heated at high temperatures before application. Temperature storage and application at ambient temperature can avoid the use of energy and emissions associated with heating and drying [Kennedy, 1997]. This makes bitumen emulsions more economic and environmental friendl , compared to coal tar-based products.Additives are used to improve the properties of bitumen emulsions in special road applications. Polymer( SBS, SBR and EVA) , clay illite , kaolinite and montmorillonite and epoxy modified bitumen/ bitumen emulsions were successfully used in South Africa and Australia [ TRB-EC102, 2006; Xiao, 2010] .During the application of bitumen emulsion, the water must be separated from the bitumen phase and evaporate.This separation is called breaking. After complete evaporation of the water, the bitumen particles will coalesce and bond together to develop mechanical properties. This strength development is curing.4. 1.2 nanoclay modified bitumen emulsionThe most preferred and widely used nanoclays are organically modified smectite clays with a 2: 1-type layey structure such as montmorillonite, saponite, etc [ Ammala , 2007] . All these layered silicates have the same crystalline structure and normally have a thickness of about 1 nanometer and a length of about 50 ~ 1 000 nanometers.In nanoclay modified bitumen emulsion, three possible particle dispersions can be distinguished as Fig. 1 shows [Xiao, 2010]. In the case of type one (see Fig. 1( a) ) , all the nanoclay particles are dispersed in the bitumen droplets. In this case, after breaking and curing the particles are dispersed in the binder between the aggregates. In the second type (see Fig. 1( b) ) , all of the nanoclay particles are dispersed in the water phase. After breaking and full curing, the particles are surrounding at the boundaries of the bitumen droplet s. The third type( see Fig. 1( c) ) is a combination of the first two types. Some of the particles are dispersed in the bitumen droplets while the others are dispersed in the water phase. In this condition, after breaking and curing the nanoclay particles both occur in the binder and between the bitumen droplets.These dispersion types have a significant influence on the properties of bitumen residues. Further investigations need to be carried on for checking these dispersions.Fig . 2 shows the possible outstanding properties of nanoclay modified bitumen emulsion on outside chemical resistance [Xiao, 2010] . With the unmodified bitumen emulsion after curing on the pavement surface, fuel, moisture and ultraviolet radiation can affect the binder directly. These can decrease the performance and cause raveling and ageing problems. When nanoclay modified bitumen emulsions are used for surface treatment, four steps can be dist inguished during breaking and curing. First, nanoclay modified bitumen emulsion consist s mainly of water, bitumen drop and nanoclay layers. Second, the water phase evaporates during the breaking and curing process. Then, bitumen droplets adhere to nanoclay particles, causing clusters to form the binder. At the last, binder is formed with nanoclay layers inside.The dispersed nanoclay particles can decrease surface damages due to fuel, moisture, air, etc. to a certain extent, resulting in better chemical and ageing resistance.4.2 Epoxy modified bitumensThe epoxy modified bitumen binder is a two phase chemical system in which the continuous phase is an acid cured epoxy and the discontinuous phase is a mixture of specialized bitumens, which makes the mixture performdifferent from a traditional asphalt mixture.4. 2. 1 Properties of epoxy modified bitumensEpoxy modified bitumen was used for pavement treatment long time ago and has achieved better properties than unmodified bitumen. In 1967, it was used to strengthen the surface of San Francisco Bay smile-long San Mateo-Hay ward Bridge. After more than 40 years, the bridge surface is reported to be in excellent condition.The special structure of epoxy modified bitumen makes it perform different from traditional bitumen. It does not become brittle at low temperature and does not melt at high temperature. Epoxy modified bitumen is a flexible material that can be applied in thin surface layers. When used on roads, it sets quickly enough to allow early traffic even before full curing, which enables the road to be reopened withintwo hours [ Xiao, 2010] .Epoxy modified bitumen is reported to be extremely durable as w ell as flexible. Surfaces with epoxy modified bitumen obtained better skid resistance and produce less noise than bitumen based sealers. Epoxy modified bitumen has extremely high temperature stability and strength, superior rutting resistance, excellent adhesion properties, high resistance to surface abrasion and is sufficiently fuel resistance [ Elliot t, 2008; Xiao, 2010] .4.2.2 Two-component epoxy modifiedbitumenTwo-component epoxy modified bitumen is acold mix application material. It is a two componentreactive material based on two components. One is amix of bitumen, bitumen-compatible epoxides andadditives. The other one is a mix of hardeners. After mixing of these two component s, there will be a fast react ion leading to epoxy resin within a bitumen based matrix.The tensile strength of Esha Seal 2C, which is a kind of two-component epoxy modified bitumen, obtained from ICOPAL BV, was evaluated using the Direct T ensile Test . Fig. 3 shows the tensile strengthafter different curing times and temperatures.Results indicate that the curing rate of epoxy modified bitumen emulsion depends on the curing temperature. The tensile strength increases with increasing curing time temperature . The tensile strength after full curing is higher than thetensile strength of bitumen, which implies that roads can be reopened for traffic very quickly w hen epoxy modified bitumens are applied in the surface layer.4. 3 Waterborne resinsWaterborne resins use water as the main volatile liquid component . It always shows good adhesion and the resistance to fuel, water and chemical is good. New technologies in waterborne systems provide unique technical solutions to get good properties, such as good adhesion to concrete and acidic resistance. With the waterborne two-component technology, coating manufacturers can formulate high-performance coatings without a cosolvent and achieve the same or better properties. Here waterborne polyurethane and epoxy resins will be discussed.4. 3. 1 Waterborne polyurethane resinsPolyurethane is a polymer consisting of a chain of organic units joined by urethane carbamate links. Polyurethane resins are formed from the reaction of an isocyanate with compounds containing active hydrogen, as Fig.4 shows. When the two components are mixed the hydroxyl groups ( - OH) in the resin react with the isocyanate groups ( N=C=O) in the hardener and a three dimensional molecular structure is produced[Weiss, 1997] .Because only one isocyanate group can react with one hydroxyl group, it is possible to vary the ratio of hydroxyl groups and isocyanate groups slightly either w ay in order to modify the mechanical properties of the system.Basically, waterbornepolyurethanes can be described asreactive or non-reactive polymerscontaining urethane and urea groupswhich are stabilized in water byinternal or external emulsifiers. Thesedifferent hydrophilic modify cationsallow the production of stablewaterborne polyurethanes with average particle sizes between 10 nm and 200 nm. Waterborne polyurethane resin is a water-based aliphatic polyurethane emulsion.Waterborne polyurethanes are environmental friendly. They provide a tough, durable and highly flexible binder. The advantages associated with polyurethane coatings are their high tensile strength, excellent adhesion properties and chemical/ mechanical resistance. Properties of waterborne polyurethanes can be improved by adding modifiers, such as organoclay layers [ Kim, 2003; Xiao, 2010] .Addagrip 1000 System resin is a two-component polyurethane resin designed by Addagrip Surface Treatments UK Ltd. It can be used for sealing to protect asphalt surfaces from erosion caused by frostdamage, chemical at tack and aviation fuel spillage. Areas treated over the last twenty years at military and civil air fields have prevented further deterioration and increased the service life of the concrete pavement by an estimated 10~ 15 years. Table 2 show s the properties of the samples before and after surface treatment with Addagrip 1000 System resin. 10 cm x 10 cmx10 cm blocks w ere used. The sample surfaces w ere heated and dried by a hot compressedair system before the resin w as sprayed onto the surface [Addagrip Ltd. ] . After surface reatment with this kind of polyurethane resin, the water and fuel resistance can be improved significantly.4. 3. 2 Waterborne epoxy resinsEpoxy is a copolymer. It is formed from two different chemicals, the resin and the hardener. Most common epoxy resins are produced from a reaction between Epichlorhydrin and bispheno-l A, see Fig.5[Weiss,1997] .Waterborne epoxy resin, with excellent adhesion properties, is another possible alternative. Waterborne epoxy resin is a stable resin material prepared by dispersing epoxy resin in the form of particles or droplet s into the dispersion medium based on water as a continuous phase.Application ofwaterborne epoxy resinsis not onlyconvenient but alsocauses no pollution tothe environmentand no harm to thehuman body. Afteradding a properamount of curing/ solidifying agent, advantages like high strength ,high-temperature resistance, chemical resistance, fatigue resistance, and high antiaging ability can be achieved [ Xiao, 2010; Weiss, 1997]5 ConclusionCTS are widely used for pavement surface treatments because of their excellent adhesion properties and good fuel resistance. How ever, because of their high PAHs content s, which are considered as human carcinogens, CTS are not allowed anymore in some of the developed counties. In order to eliminate the significant threat of pollution to our environment, w e should stop using CTS. Instead, modified bitumen emulsions, epoxy modified bitumen, waterborne polyurethanes and waterborne epoxy resins could achievecomparable or better properties than CTS. All of them have good adhesion, excellent chemical and ageing resistance. Epoxy modified bitumen has extremely high temperature stability and strength. Application of waterborne resins is convenient and the curing rate can be easily adjusted by changing the ratio of chemical components. And, the most important, these alternatives are environmental friendly.AcknowledgementsThe scholarship from the China Scholarship Council is acknowledged. T he authors would like to express thanks to ICOPAL BV for their materials and technical supports.References[1] AddagripLtd.www .adda grip [2] Ammala A, Hill A J.Poly( M-Xylene Adipamide)-Kaolinite and Poly( M-XyleneAdipamide)-Montmorillonite Nanocomposites [J] . Journal of Applied Polymer Science, 2007(104):1377- 1381.[3] Austin. http: / /www .ci. austin. tx . us/ watershed/ coaltar- ban. htm. Austin Bans Use of Coal Tar Sealants-first in Nation,2005.[4] CCTIR.China Coal Tar Industry Report 2006-2010.[R],2008.[5] Elliott R. 2008. Epoxy Asphalt: Concept and Properties. Workshop of TRB 2008.[6] IARC. Polynuclear Aromatic 4 Bitumens , Coal Tars and Der ived Products,Shale Oils and Soots. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans,Vol. 35. Lyon, France:International Agency for Research on Cancer,1985.[7] Kennedy J. Alter native Materials and Techniques for Road Pavement Construction[R] . London: DOE Energy Efficiency Office,1997.[8] Kim B K, Seo J W, Jeong H M. Morphology and Properties of Waterborne Polyurethane/ clay Nanocomposite [J]. European[9] SCHER. Scientific Committee on Health and Environmental Risks. Coal tar pitch, high temperature Human Health Part. CAS No: 65996- 93- 2. EINECS No: 266- 028-2.[10] Thom N H. Asphalt Cracking: A Nottingham Perspective [J].Engenaria Civil/ Civil Engineering, 2006(26) : 75- 84.[11] TRB-EC102. Asphalt Emulsion Technology. Transportation Research Board[S], 2006.[12] Van Leest A J, Gaar keuken G. The F O D. Resistance of Sur face Layers on Airfields in the Netherlands; in Situ and Laboratory Testing [R] . 2005 European Airport Pavement Workshop, 2005. [13] Van Metre P C, Mahler B J. Trends in Hydrophobic Organic Contaminants in Urban and Reference Lake Sediments Across the United States, 1970- 2001[J]. Environmental Science and Technology,2005, 39( 15) : 5567- 5574.[14] Weiss K D. Paint and Coatings: A Mature Industry in Transition [J].Progress in Polymer Science, 1997, 22(2):203- 245.[15] Xiao Y. Literature Review on Possible Alternatives to Tar for Antiskid Layers . Delft University o f Technology, Road and Railway Engineering Section[R] . Report No.7-10-185-1,the Nether lands.。

毕业设计中英文翻译

Key to the development of four-rotors micro air vehicletechnologyTo date, micro d experimental study on the basic theory of rotary wing aircraft and have made more progress, but to really mature and practical, also faces a number of key technical challenges.1. Optimal designOverall design of rotary-wing aircraft when small, need to be guided by the following principles: light weight, small size, high speed, low power consumption and costs. But these principles there are constraints and conflicting with each other, such as: vehicle weights are the same, is inversely proportional to its size and speed, low energy consumption. Therefore, when the overall design of miniature four-rotor aircraft, first select the appropriate body material based on performance and price, as much as possible to reduce the weight of aircraft; second, the need to take into account factors such as weight, size, speed and energy consumption, ensuring the realization of design optimization.2. The power and energyPower unit includes: rotor, micro DC motor, gear reducer, photoelectric encoder and motor drive module, the energy provided by onboard batteries. Four-rotors micro air vehicle's weight is a major factor affecting their size and weight of the power and energy devices accounted for a large share of the weight of the entire body. For the OS4 II, the proportion is as high as 75%. Therefore, development of lighter, more efficient power and energy devices is further miniaturized four key to rotary wing aircraft.The other hand, the lifting occurs with a power unit, most airborne energy consumption. For example, OS4 II power 91% power consumption. To increase the efficiency of aircraft, the key is to improve the efficiency of the power plant. In addition to maximize transmission efficiency, you must alsoselect the motor and reduction ratios, taking into account the maximum efficiency and maximum power output under the premise of two indicators, electric operating point within the recommended run area.3. The establishment of mathematical modelIn order to achieve effective control of four-rotors micro air vehicles, must be established accurately under various flight model. But during the flight, it not only accompanied by a variety of physical effects (aerodynamic, gravity, gyroscopic effect and rotor moment of inertia, also is vulnerable to disturbances in the external environment, such as air. Therefore, it is difficult to establish an effective, reliable dynamic model. In addition, the use of rotary wing, small size, light weight, easy to shape, it is difficult to obtain accurate aerodynamic performance parameters, and also directly affects the accuracy of the model.Establishment of mathematical model of four-rotor MAV, must also be studied and resolved problems rotor under low Reynolds number aerodynamics. Aerodynamics of micro air vehicle with conventional aircraft is very different, many aerodynamic theory and analysis tools are not currently applied, requires the development of new theories and research techniques.4. Flight controlFour-rotors micro air vehicle is a six degrees of freedom (location and attitude) and 4 control input (rotor speed) of underactuated system (Underactuated System), have more than one variable, linear, strongly coupled and interfere with sensitive features, makes it very difficult to design of flight control system. In addition, the controller model accuracy and precision of the sensor performance will also be affected.Attitude control is the key to the entire flight control, because four-rotors micro air vehicle's attitude and position a direct coupling (roll pitch p directly causes the body to move around before and after p), if you can precisely control the spacecraft attitude, then the control law is sufficient to achieve itsposition and velocity PID control. International study to focus on with attitude control design and validation, results show that although the simulation for nonlinear control law to obtain good results, but has a strong dependence on model accuracy, its actual effect rather than PID control. Therefore, developed to control the spacecraft attitude, also has strong anti-jamming and environment-Adaptive attitude control of a tiny four-rotary wing aircraft flight control system of priorities.5. Positioning, navigation and communicationMiniature four-rotor aircraft is primarily intended for near-surface environments, such as urban areas, forests, and interior of the tunnel. However, there are also aspects of positioning, navigation and communication. One hand, in near-surface environments, GPS does not work often requires integrated inertial navigation, optics, acoustics, radar and terrain-matching technology, development of a reliable and accurate positioning and navigation technology, on the other, near-surface environment, terrain, sources of interference and current communication technology reliability, security and robustness of application still cannot meet the actual demand. Therefore, development of small volume, light weight, low power consumption, reliability and anti-jamming communication chain in four-rotors micro air vehicle technology (in particular the multi-aircraft coordination control technology) development, are crucial.微小型四旋翼飞行器发展的关键技术迄今为止，微小型四旋翼飞行器基础理论与实验研究已取得较大进展，但要真正走向成熟与实用，还面临着诸多关键技术的挑战。

液压专业毕业设计外文翻译(有译文、外文文献)值得收藏哦!

外文原文：The Analysis of Cavitation Problems in the Axial Piston Pumpshu WangEaton Corporation,14615 Lone Oak Road,Eden Prairie, MN 55344This paper discusses and analyzes the control volume of a piston bore constrained by the valve plate in axial piston pumps. The vacuum within the piston bore caused by the rise volume needs to be compensated by the flow; otherwise, the low pressure may cause the cavitations and aerations. In the research, the valve plate geometry can be optimized by some analytical limitations to prevent the piston pressure below the vapor pressure. The limitations provide the design guide of the timings and overlap areas between valve plate ports and barrel kidneys to consider the cavitations and aerations. _DOI: 10.1115/1.4002058_Keywords: cavitation , optimization, valve plate, pressure undershoots1 IntroductionIn hydrostatic machines, cavitations mean that cavities or bubbles form in the hydraulic liquid at the low pressure and collapse at the high pressure region, which causes noise, vibration, and less efficiency.Cavitations are undesirable in the pump since the shock waves formed by collapsed may be strong enough to damage components. The hydraulic fluid will vaporize when its pressure becomes too low or when the temperature is too high. In practice, a number of approaches are mostly used to deal with the problems: (1) raise the liquid level in the tank, (2) pressurize the tank, (3) booster the inlet pressure of the pump, (4) lower the pumping fluid temperature, and (5) design deliberately the pump itself.Many research efforts have been made on cavitation phenomena in hydraulic machine designs. The cavitation is classified into two types in piston pumps: trapping phenomenon related one (which can be preventedby the proper design of the valve plate) and the one observed on the layers after the contraction or enlargement of flow passages (caused by rotating group designs) in Ref. (1). The relationship between the cavitation and the measured cylinder pressure is addressed in this study. Edge and Darling (2) reported an experimental study of the cylinder pressure within an axial piston pump. The inclusion of fluid momentum effects and cavitations within the cylinder bore are predicted at both high speed and high load conditions. Another study in Ref. (3) provides an overview of hydraulic fluid impacting on the inlet condition and cavitation potential. It indicates that physical properties (such as vapor pressure, viscosity, density, and bulk modulus) are vital to properly evaluate the effects on lubrication and cavitation. A homogeneous cavitation model based on the thermodynamic properties of the liquid and steam is used to understand the basic physical phenomena of mass flow reduction and wave motion influences in the hydraulic tools and injection systems (4). Dular et al. (5, 6) developed an expert system for monitoring and control of cavitations in hydraulic machines and investigated the possibility of cavitation erosion by using the computational fluid dynamics (CFD) tools. The erosion effects of cavitations have been measured and validated by a simple single hydrofoil configuration in a cavitation tunnel. It is assumed that the severe erosion is often due to the repeated collapse of the traveling vortex generated by a leading edge cavity in Ref. (7). Then, the cavitation erosion intensity may be scaled by a simple set of flow parameters: the upstream velocity, the Strouhal number, the cavity length, and the pressure. A new cavitation erosion device, called vortex cavitation generator, is introduced to comparatively study various erosion situations (8).More previous research has been concentrated on the valve plate designs, piston, and pump pressure dynamics that can be associated with cavitations in axial piston pumps. The control volume approach and instantaneous flows (leakage) are profoundly studied in Ref. [9]. Berta et al. [10] used the finite volume concept to develop a mathematical model in which the effects of port plate relief grooves have been modeled andthe gaseous cavitation is considered in a simplified manner. An improved model is proposed in Ref. [11] and validated by experimental results. The model may analyze the cylinder pressure and flow ripples influenced by port plate and relief groove design. Manring compared principal advantages of various valve plate slots (i.e., the slots with constant, linearly varying, and quadratic varying areas) in axial piston pumps [12]. Four different numerical models are focused on the characteristics of hydraulic fluid, and cavitations are taken into account in different ways to assist the reduction in flow oscillations [13].The experiences of piston pump developments show that the optimization of the cavitations/aerations shall include the following issues: occurring cavitation and air release, pump acoustics caused by the induced noises, maximal amplitudes of pressure fluctuations, rotational torque progression, etc. However, the aim of this study is to modify the valve plate design to prevent cavitation erosions caused by collapsing steam or air bubbles on the walls of axial pump components. In contrastto literature studies, the research focuses on the development of analytical relationship between the valve plate geometrics and cavitations. The optimization method is applied to analyze the pressure undershoots compared with the saturated vapor pressure within the piston bore.The appropriate design of instantaneous flow areas between the valveplate and barrel kidney can be decided consequently.2 The Axial Piston Pump and Valve PlateThe typical schematic of the design of the axis piston pump is shown in Fig. 1. The shaft offset e is designed in this case to generate stroking containment moments for reducing cost purposes.The variation between the pivot center of the slipper and swash rotating center is shown as a. The swash angle αis the variable that determines the amount of fluid pumped per shaft revolution. In Fig. 1, the n th piston-slipper assembly is located at the angle ofθ. The displacement of the n thnpiston-slipper assembly along the x-axis can be written asx n= R tan（α）sin（θ）+ a sec（α）+ e tan(α) (1)nwhere R is the pitch radius of the rotating group.Then, the instantaneous velocity of the n th piston isx˙n = R 2sec ()αsin （n θ）α+ R tan （α）cos （n θ）ω+ R 2sec ()αsin （α）α + e 2sec ()αα (2)where the shaft rotating speed of the pump is ω=d n θ / dt .The valve plate is the most significant device to constraint flow inpiston pumps. The geometry of intake/discharge ports on the valve plateand its instantaneous relative positions with respect to barrel kidneys areusually referred to the valve plate timing. The ports of the valve plateoverlap with each barrel kidneys to construct a flow area or passage,which confines the fluid dynamics of the pump. In Fig. 2, the timingangles of the discharge and intake ports on the valve plate are listed as(,)T i d δ and (,)B i d δ. The opening angle of the barrel kidney is referred to asϕ. In some designs, there exists a simultaneous overlap between thebarrel kidney and intake/discharge slots at the locations of the top deadcenter (TDC) or bottom dead center (BDC) on the valve plate on whichthe overlap area appears together referred to as “cross -porting” in thepump design engineering. The cross-porting communicates the dischargeand intake ports, which may usually lower the volumetric efficiency. Thetrapped-volume design is compared with the design of the cross-porting,and it can achieve better efficiency 14]. However, the cross-porting isFig. 1 The typical axis piston pumpcommonly used to benefit the noise issue and pump stability in practice.3 The Control Volume of a Piston BoreIn the piston pump, the fluid within one piston is embraced by the piston bore, cylinder barrel, slipper, valve plate, and swash plate shown in Fig. 3. There exist some types of slip flow by virtue of relativeFig. 2 Timing of the valve platemotions and clearances between thos e components. Within the control volume of each piston bore, the instantaneous mass is calculated asM= n V(3)nwhere ρ and n V are the instantaneous density and volumesuch that themass time rate of change can be given asFig. 3 The control volume of the piston boren n n dM dV d V dt dt dtρρ=+ (4) where d n V is the varying of the volume.Based on the conservation equation, the mass rate in the control volume isn n dM q dtρ= (5)where n q is the instantaneous flow rate in and out of one piston. From the definition of the bulk modulus,n dP d dt dtρρβ= (6) where Pn is the instantaneous pressure within the piston bore. Substituting Eqs. (5) and (6) into Eq. (4) yields(?)n n n n n ndP q dV d V w d βθθ=- (7) where the shaft speed of the pump is n d dtθω=. The instantaneous volume of one piston bore can be calculated by using Eq. (1) asn V = 0V + P A [R tan （α）sin （n θ）+ a sec （α） + e tan(α) ] (8)where P A is the piston sectional area and 0V is the volume of eachpiston, which has zero displacement along the x-axis (when n θ=0, π).The volume rate of change can be calculated at the certain swash angle, i.e., α =0, such thattan cos n p n ndV A R d αθθ=（）（） (9) in which it is noted that the piston bore volume increases or decreaseswith respect to the rotating angle of n θ.Substituting Eqs. (8) and (9) into Eq. (7) yields0[tan()cos()] [tan sin sec tan() ]n P n n n p n q A R dP d V A R a e βαθωθαθαα-=-++（）（）（）(10)4 Optimal DesignsTo find the extrema of pressure overshoots and undershoots in the control volume of piston bores, the optimization method can be used in Eq. (10). In a nonlinear function, reaching global maxima and minima is usually the goal of optimization. If the function is continuous on a closed interval, global maxima and minima exist. Furthermore, the global maximum (or minimum) either must be a local maximum (or minimum) in the interior of the domain or must lie on the boundary of the domain. So, the method of finding a global maximum (or minimum) is to detect all the local maxima (or minima) in the interior, evaluate the maxima (or minima) points on the boundary, and select the biggest (or smallest) one. Local maximum or local minimum can be searched by using the first derivative test that the potential extrema of a function f( · ), with derivative ()f ', can solve the equation at the critical points of ()f '=0 [15].The pressure of control volumes in the piston bore may be found as either a minimum or maximum value as dP/ dt=0. Thus, letting the left side of Eq. (10) be equal to zero yieldstan()cos()0n p n q A R ωαθ-= (11)In a piston bore, the quantity of n q offsets the volume varying and thendecreases the overshoots and undershoots of the piston pressure. In this study, the most interesting are undershoots of the pressure, which may fall below the vapor pressure or gas desorption pressure to cause cavitations. The term oftan()cos()p n A R ωαθ in Eq. (11) has the positive value in the range of intake ports (22ππθ-≤≤), shown in Fig. 2, which means that the piston volume arises. Therefore, the piston needs the sufficient flow in; otherwise, the pressure may drop.In the piston, the flow of n q may get through in a few scenariosshown in Fig. 3: (I) the clearance between the valve plate and cylinder barrel, (II) the clearance between the cylinder bore and piston, (III) the clearance between the piston and slipper, (IV) the clearance between the slipper and swash plate, and (V) the overlapping area between the barrel kidney and valve plate ports. As pumps operate stably, the flows in the as laminar flows, which can be calculated as [16]312IV k k Ln i I k h q p L ωμ==∑ (12)where k h is the height of the clearance, k L is the passage length,scenarios I –IV mostly have low Reynolds numbers and can be regarded k ω is the width of the clearance (note that in the scenario II, k ω =2π· r, in which r is the piston radius), and p is the pressure drop defined in the intake ports as p =c p -n p (13)where c p is the case pressure of the pump. The fluid films through theabove clearances were extensively investigated in previous research. The effects of the main related dimensions of pump and the operating conditions on the film are numerically clarified inRefs. [17,18]. The dynamic behavior of slipper pads and the clearance between the slipper and swash plate can be referred to Refs. [19,20]. Manring et al. [21,22] investigated the flow rate and load carrying capacity of the slipper bearing in theoretical and experimental methods under different deformation conditions. A simulation tool calledCASPAR is used to estimate the nonisothermal gap flow between the cylinder barrel and the valve plate by Huang and Ivantysynova [23]. The simulation program also considers the surface deformations to predict gap heights, frictions, etc., between the piston and barrel andbetween the swash plate and slipper. All these clearance geometrics in Eq.(12) are nonlinear and operation based, which is a complicated issue. In this study, the experimental measurements of the gap flows are preferred. If it is not possible, the worst cases of the geometrics or tolerances with empirical adjustments may be used to consider the cavitation issue, i.e., minimum gap flows.For scenario V, the flow is mostly in high velocity and can be described by using the turbulent orifice equation as((Tn d i d d q c A c A θθ= (14)where Pi and Pd are the intake and discharge pressure of the pump and ()i A θ and ()d A θ are the instantaneous overlap area between barrel kidneys and inlet/discharge ports of the valve plate individually.The areas are nonlinear functions of the rotating angle, which is defined by the geometrics of the barrel kidney, valve plate ports,silencing grooves, decompression holes, and so forth. Combining Eqs.(11) –(14), the area can be obtained as3()K IV A θ==(15)where ()A θ is the total overlap area of ()A θ=()()i d A A θλθ+, and λ is defined as=In the piston bore, the pressure varies from low tohigh while passing over the intake and discharge ports of the valve plates. It is possible that the instantaneous pressure achieves extremely low values during the intake area( 22ππθ-≤≤ shown in Fig. 2) that may be located below the vapor pressure vp p , i.e., n vp p p ≤;then cavitations canhappen. To prevent the phenomena, the total overlap area of ()A θ mightbe designed to be satisfied with30()K IV A θ=≥(16)where 0()A θ is the minimum area of 0()A θ=0()()i d A A θλθ+ and 0λis a constant that is0λ=gaseous form. The vapor pressure of any substance increases nonlinearly with temperature according to the Clausius –Clapeyron relation. With the incremental increase in temperature, the vapor pressure becomes sufficient to overcome particle attraction and make the liquid form bubbles inside the substance. For pure components, the vapor pressure can be determined by the temperature using the Antoine equation as /()10A B C T --, where T is the temperature, and A, B, and C are constants[24].As a piston traverse the intake port, the pressure varies dependent on the cosine function in Eq. (10). It is noted that there are some typical positions of the piston with respect to the intake port, the beginning and ending of overlap, i.e., TDC and BDC (/2,/2θππ=- ) and the zero displacement position (θ =0). The two situations will be discussed as follows:(1) When /2,/2θππ=-, it is not always necessary to maintain the overlap area of 0()A θ because slip flows may provide filling up for the vacuum. From Eq. (16), letting 0()A θ=0,the timing angles at the TDC and BDC may be designed as31cos ()tan()122IV c vpk k i I P k p p h A r L ωϕδωαμ--≤+∑ (17) in which the open angle of the barrel kidney is . There is nocross-porting flow with the timing in the intake port.(2) When θ =0, the function of cos θ has the maximum value, which can provide another limitation of the overlap area to prevent the low pressure undershoots suchthat 30(0)K IVA =≥ (18)where 0(0)A is the minimum overlap area of 0(0)(0)i A A =.To prevent the low piston pressure building bubbles, the vaporpressure is considered as the lower limitation for the pressure settings in Eq. (16). The overall of overlap areas then can be derived to have adesign limitation. The limitation is determined by the leakage conditions, vapor pressure, rotating speed, etc. It indicates that the higher the pumping speed, the more severe cavitation may happen, and then the designs need more overlap area to let flow in the piston bore. On the other side, the low vapor pressure of the hydraulic fluid is preferred to reduce the opportunities to reach the cavitation conditions. As a result, only the vapor pressure of the pure fluid is considered in Eqs. (16)–(18). In fact, air release starts in the higher pressure than the pure cavitation process mainly in turbulent shear layers, which occur in scenario V.Therefore, the vapor pressure might be adjusted to design the overlap area by Eq. (16) if there exists substantial trapped and dissolved air in the fluid.The laminar leakages through the clearances aforementioned are a tradeoff in the design. It is demonstrated that the more leakage from the pump case to piston may relieve cavitation problems.However, the more leakage may degrade the pump efficiency in the discharge ports. In some design cases, the maximum timing angles can be determined by Eq. (17)to not have both simultaneous overlapping and highly low pressure at the TDC and BDC.While the piston rotates to have the zero displacement, the minimum overlap area can be determined by Eq. 18 , which may assist the piston not to have the large pressure undershoots during flow intake.6 ConclusionsThe valve plate design is a critical issue in addressing the cavitation or aeration phenomena in the piston pump. This study uses the control volume method to analyze the flow, pressure, and leakages within one piston bore related to the valve plate timings. If the overlap area developed by barrel kidneys and valve plate ports is not properly designed, no sufficient flow replenishes the rise volume by the rotating movement. Therefore, the piston pressure may drop below the saturated vapor pressure of the liquid and air ingress to form the vapor bubbles. To control the damaging cavitations, the optimization approach is used to detect the lowest pressure constricted by valve plate timings. The analytical limitation of the overlap area needs to be satisfied to remain the pressure to not have large undershoots so that the system can be largely enhanced on cavitation/aeration issues.In this study, the dynamics of the piston control volume is developed by using several assumptions such as constant discharge coefficients and laminar leakages. The discharge coefficient is practically nonlinear based on the geometrics, flow number, etc. Leakage clearances of the control volume may not keep the constant height and width as well in practice due to vibrations and dynamical ripples. All these issues are complicated and very empirical and need further consideration in the future. Theresults presented in this paper can be more accurate in estimating the cavitations with these extensive studies.Nomenclature0(),()A A θθ= the total overlap area between valve plate ports and barrel kidneys 2()mmAp = piston section area 2()mmA, B, C= constantsA= offset between the piston-slipper joint and surface of the swash plate 2()mmd C = orifice discharge coefficiente= offset between the swash plate pivot and the shaft centerline of the pump 2()mmk h = the height of the clearance 2()mmk L = the passage length of the clearance 2()mmM= mass of the fluid within a single piston (kg)N= number of pistonsn = piston and slipper counter,p p = fluid pressure and pressure drop (bar)Pc= the case pressure of the pump (bar)Pd= pump discharge pressure (bar)Pi = pump intake pressure (bar)Pn = fluid pressure within the nth piston bore (bar)Pvp = the vapor pressure of the hydraulic fluid(bar)qn, qLn, qTn = the instantaneous flow rate of each piston(l/min)R = piston pitch radius 2()mmr = piston radius (mm)t =time (s)V = volume 3()mmwk = the width of the clearance (mm)x ,x ˙= piston displacement and velocity along the shaft axis (m, m/s) x y z --=Cartesian coordinates with an origin on the shaft centerline x y z '''--= Cartesian coordinates with an origin on swash plate pivot ,αα=swash plate angle and velocity (rad, rad/s)β= fluid bulk modulus (bar)δδ= timing angle of valve plates at the BDC and TDC (rad),B Tϕ= the open angle of the barrel kidney(rad)ρ= fluid density(kg/m3),θω= angular position and velocity of the rotating kit (rad, rad/s)μ=absolute viscosity(Cp),λλ= coefficients related to the pressure drop外文中文翻译：在轴向柱塞泵气蚀问题的分析本论文讨论和分析了一个柱塞孔与配流盘限制在轴向柱塞泵的控制量设计。

毕业设计英文翻译(原文)

编号：毕业设计(论文)外文翻译（原文）院（系）：桂林电子科技大学专业：电子信息工程学生姓名： xx学号： xxxxxxxxxxxxx 指导教师单位：桂林电子科技大学姓名： xxxx职称： xx2014年x月xx日Timing on and off power supplyusesThe switching power supply products are widely used in industrial automation and control, military equipment, scientific equipment, LED lighting, industrial equipment,communications equipment,electrical equipment,instrumentation, medical equipment, semiconductor cooling and heating, air purifiers, electronic refrigerator, LCD monitor, LED lighting, communications equipment, audio-visual products, security, computer chassis, digital products and equipment and other fields.IntroductionWith the rapid development of power electronics technology, power electronics equipment and people's work, the relationship of life become increasingly close, and electronic equipment without reliable power, into the 1980s, computer power and the full realization of the switching power supply, the first to complete the computer Power new generation to enter the switching power supply in the 1990s have entered into a variety of electronic, electrical devices, program-controlled switchboards, communications, electronic testing equipment power control equipment, power supply, etc. have been widely used in switching power supply, but also to promote the rapid development of the switching power supply technology .Switching power supply is the use of modern power electronics technology to control the ratio of the switching transistor to turn on and off to maintain a stable output voltage power supply, switching power supply is generally controlled by pulse width modulation (PWM) ICs and switching devices (MOSFET, BJT) composition. Switching power supply and linear power compared to both the cost and growth with the increase of output power, but the two different growth rates. A power point, linear power supply costs, but higher than the switching power supply. With the development of power electronics technology and innovation, making the switching power supply technology to continue to innovate, the turning points of this cost is increasingly move to the low output power side, the switching power supply provides a broad space for development.The direction of its development is the high-frequency switching power supply, high frequency switching power supply miniaturization, and switching power supply into a wider range of application areas, especially in high-tech fields, and promote the miniaturization of high-tech products, light of. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.classificationModern switching power supply, there are two: one is the DC switching power supply; the other is the AC switching power supply. Introduces only DC switching power supply and its function is poor power quality of the original eco-power (coarse) - such as mains power or battery power, converted to meet the equipment requirements of high-quality DC voltage (Varitronix) . The core of the DC switching power supply DC / DC converter. DC switching power supply classification is dependent on the classification of DC / DC converter. In other words, the classification of the classification of the DC switching power supply and DC/DC converter is the classification of essentially the same, the DC / DC converter is basically a classification of the DC switching power supply.DC /DC converter between the input and output electrical isolation can be divided into two categories: one is isolated called isolated DC/DC converter; the other is not isolated as non-isolated DC / DC converter.Isolated DC / DC converter can also be classified by the number of active power devices. The single tube of DC / DC converter Forward (Forward), Feedback (Feedback) two. The double-barreled double-barreled DC/ DC converter Forward (Double Transistor Forward Converter), twin-tube feedback (Double Transistor Feedback Converter), Push-Pull (Push the Pull Converter) and half-bridge (Half-Bridge Converter) four. Four DC / DC converter is the full-bridge DC / DC converter (Full-Bridge Converter).Non-isolated DC / DC converter, according to the number of active power devices can be divided into single-tube, double pipe, and four three categories. Single tube to a total of six of the DC / DC converter, step-down (Buck) DC / DC converter, step-up (Boost) DC / DC converters, DC / DC converter, boost buck (Buck Boost) device of Cuk the DC / DC converter, the Zeta DC / DC converter and SEPIC, the DC / DC converter. DC / DC converters, the Buck and Boost type DC / DC converter is the basic buck-boost of Cuk, Zeta, SEPIC, type DC / DC converter is derived from a single tube in this six. The twin-tube cascaded double-barreled boost (buck-boost) DC / DC converter DC / DC converter. Four DC / DC converter is used, the full-bridge DC / DC converter (Full-Bridge Converter).Isolated DC / DC converter input and output electrical isolation is usually transformer to achieve the function of the transformer has a transformer, so conducive to the expansion of the converter output range of applications, but also easy to achieve different voltage output , or a variety of the same voltage output.Power switch voltage and current rating, the converter's output power is usually proportional to the number of switch. The more the number of switch, the greater the output power of the DC / DC converter, four type than the two output power is twice as large,single-tube output power of only four 1/4.A combination of non-isolated converters and isolated converters can be a single converter does not have their own characteristics. Energy transmission points, one-way transmission and two-way transmission of two DC / DC converter. DC / DC converter with bi-directional transmission function, either side of the transmission power from the power of lateral load power from the load-lateral side of the transmission power.DC / DC converter can be divided into self-excited and separately controlled. With the positive feedback signal converter to switch to self-sustaining periodic switching converter, called self-excited converter, such as the the Luo Yeer (Royer,) converter is a typical push-pull self-oscillating converter. Controlled DC / DC converter switching device control signal is generated by specialized external control circuit.the switching power supply.People in the field of switching power supply technology side of the development of power electronic devices, while the development of the switching inverter technology, the two promote each other to promote the switching power supply annual growth rate of more than two digits toward the light, small, thin, low-noise, high reliability, the direction of development of anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, AC / AC DC / AC, such as inverters, DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardization, and has been recognized by the user, but AC / DC modular, its own characteristics make the modular process, encounter more complex technology and manufacturing process. Hereinafter to illustrate the structure and characteristics of the two types of switching power supply.Self-excited: no external signal source can be self-oscillation, completely self-excited to see it as feedback oscillation circuit of a transformer.Separate excitation: entirely dependent on external sustain oscillations, excited used widely in practical applications. According to the excitation signal structure classification; can be divided into pulse-width-modulated and pulse amplitude modulated two pulse width modulated control the width of the signal is frequency, pulse amplitude modulation control signal amplitude between the same effect are the oscillation frequency to maintain within a certain range to achieve the effect of voltage stability. The winding of the transformer can generally be divided into three types, one group is involved in the oscillation of the primary winding, a group of sustained oscillations in the feedback winding, there is a group of load winding. Such as Shanghai is used in household appliances art technological production of switching power supply, 220V AC bridge rectifier, changing to about 300V DC filter added tothe collector of the switch into the transformer for high frequency oscillation, the feedback winding feedback to the base to maintain the circuit oscillating load winding induction signal, the DC voltage by the rectifier, filter, regulator to provide power to the load. Load winding to provide power at the same time, take up the ability to voltage stability, the principle is the voltage output circuit connected to a voltage sampling device to monitor the output voltage changes, and timely feedback to the oscillator circuit to adjust the oscillation frequency, so as to achieve stable voltage purposes, in order to avoid the interference of the circuit, the feedback voltage back to the oscillator circuit with optocoupler isolation.technology developmentsThe high-frequency switching power supply is the direction of its development, high-frequency switching power supply miniaturization, and switching power supply into the broader field of application, especially in high-tech fields, and promote the development and advancement of the switching power supply, an annual more than two-digit growth rate toward the light, small, thin, low noise, high reliability, the direction of the anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, the DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardized, and has been recognized by the user, but modular AC / DC, because of its own characteristics makes the modular process, encounter more complex technology and manufacturing process. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.The switching power supply applications in power electronic devices as diodes, IGBT and MOSFET.SCR switching power supply input rectifier circuit and soft start circuit, a small amount of applications, the GTR drive difficult, low switching frequency, gradually replace the IGBT and MOSFET.Direction of development of the switching power supply is a high-frequency, high reliability, low power, low noise, jamming and modular. Small, thin, and the key technology is the high frequency switching power supply light, so foreign major switching power supply manufacturers have committed to synchronize the development of new intelligent components, in particular, is to improve the secondary rectifier loss, and the power of iron Oxygen materials to increase scientific and technological innovation in order to improve the magnetic properties of high frequency and large magnetic flux density (Bs), and capacitor miniaturization is a key technology. SMT technology allows the switching power supply has made considerable progress, the arrangement of the components in the circuit board on bothsides, to ensure that the light of the switching power supply, a small, thin. High-frequency switching power supply is bound to the traditional PWM switching technology innovation, realization of ZVS, ZCS soft-switching technology has become the mainstream technology of the switching power supply, and a substantial increase in the efficiency of the switching power supply. Indicators for high reliability, switching power supply manufacturers in the United States by reducing the operating current, reducing the junction temperature and other measures to reduce the stress of the device, greatly improve the reliability of products.Modularity is the overall trend of switching power supply, distributed power systems can be composed of modular power supply, can be designed to N +1 redundant power system, and the parallel capacity expansion. For this shortcoming of the switching power supply running noise, separate the pursuit of high frequency noise will also increase, while the use of part of the resonant converter circuit technology to achieve high frequency, in theory, but also reduce noise, but some The practical application of the resonant converter technology, there are still technical problems, it is still a lot of work in this field, so that the technology to be practical.Power electronics technology innovation, switching power supply industry has broad prospects for development. To accelerate the pace of development of the switching power supply industry in China, it must take the road of technological innovation, out of joint production and research development path with Chinese characteristics and contribute to the rapid development of China's national economy.Developments and trends of the switching power supply1955 U.S. Royer (Roger) invented the self-oscillating push-pull transistor single-transformer DC-DC converter is the beginning of the high-frequency conversion control circuit 1957 check race Jen, Sen, invented a self-oscillating push-pull dual transformers, 1964, U.S. scientists canceled frequency transformer in series the idea of switching power supply, the power supply to the size and weight of the decline in a fundamental way. 1969 increased due to the pressure of the high-power silicon transistor, diode reverse recovery time shortened and other components to improve, and finally made a 25-kHz switching power supply.At present, the switching power supply to the small, lightweight and high efficiency characteristics are widely used in a variety of computer-oriented terminal equipment, communications equipment, etc. Almost all electronic equipment is indispensable for a rapid development of today's electronic information industry power mode. Bipolar transistor made of 100kHz, 500kHz power MOS-FET made, though already the practical switching power supply is currently available on the market, but its frequency to be further improved. Toimprove the switching frequency, it is necessary to reduce the switching losses, and to reduce the switching losses, the need for high-speed switch components. However, the switching speed will be affected by the distribution of the charge stored in the inductance and capacitance, or diode circuit to produce a surge or noise. This will not only affect the surrounding electronic equipment, but also greatly reduce the reliability of the power supply itself. Which, in order to prevent the switching Kai - closed the voltage surge, RC or LC buffers can be used, and the current surge can be caused by the diode stored charge of amorphous and other core made of magnetic buffer . However, the high frequency more than 1MHz, the resonant circuit to make the switch on the voltage or current through the switch was a sine wave, which can reduce switching losses, but also to control the occurrence of surges. This switch is called the resonant switch. Of this switching power supply is active, you can, in theory, because in this way do not need to greatly improve the switching speed of the switching losses reduced to zero, and the noise is expected to become one of the high-frequency switching power supply The main ways. At present, many countries in the world are committed to several trillion Hz converter utility.the principle of IntroductionThe switching power supply of the process is quite easy to understand, linear power supplies, power transistors operating in the linear mode and linear power, the PWM switching power supply to the power transistor turns on and off state, in both states, on the power transistor V - security product is very small (conduction, low voltage, large current; shutdown, voltage, current) V oltammetric product / power device is power semiconductor devices on the loss.Compared with the linear power supply, the PWM switching power supply more efficient process is achieved by "chopping", that is cut into the amplitude of the input DC voltage equal to the input voltage amplitude of the pulse voltage. The pulse duty cycle is adjusted by the switching power supply controller. Once the input voltage is cut into the AC square wave, its amplitude through the transformer to raise or lower. Number of groups of output voltage can be increased by increasing the number of primary and secondary windings of the transformer. After the last AC waveform after the rectifier filter the DC output voltage.The main purpose of the controller is to maintain the stability of the output voltage, the course of their work is very similar to the linear form of the controller. That is the function blocks of the controller, the voltage reference and error amplifier can be designed the same as the linear regulator. Their difference lies in the error amplifier output (error voltage) in the drive before the power tube to go through a voltage / pulse-width conversion unit.Switching power supply There are two main ways of working: Forward transformand boost transformation. Although they are all part of the layout difference is small, but the course of their work vary greatly, have advantages in specific applications.the circuit schematicThe so-called switching power supply, as the name implies, is a door, a door power through a closed power to stop by, then what is the door, the switching power supply using SCR, some switch, these two component performance is similar, are relying on the base switch control pole (SCR), coupled with the pulse signal to complete the on and off, the pulse signal is half attentive to control the pole voltage increases, the switch or transistor conduction, the filter output voltage of 300V, 220V rectifier conduction, transmitted through the switching transformer secondary through the transformer to the voltage increase or decrease for each circuit work. Oscillation pulse of negative semi-attentive to the power regulator, base, or SCR control voltage lower than the original set voltage power regulator cut-off, 300V power is off, switch the transformer secondary no voltage, then each circuit The required operating voltage, depends on this secondary road rectifier filter capacitor discharge to maintain. Repeat the process until the next pulse cycle is a half weeks when the signal arrival. This switch transformer is called the high-frequency transformer, because the operating frequency is higher than the 50HZ low frequency. Then promote the pulse of the switch or SCR, which requires the oscillator circuit, we know, the transistor has a characteristic, is the base-emitter voltage is 0.65-0.7V is the zoom state, 0.7V These are the saturated hydraulic conductivity state-0.1V-0.3V in the oscillatory state, then the operating point after a good tune, to rely on the deep negative feedback to generate a negative pressure, so that the oscillating tube onset, the frequency of the oscillating tube capacitor charging and discharging of the length of time from the base to determine the oscillation frequency of the output pulse amplitude, and vice versa on the small, which determines the size of the output voltage of the power regulator. Transformer secondary output voltage regulator, usually switching transformer, single around a set of coils, the voltage at its upper end, as the reference voltage after the rectifier filter, then through the optocoupler, this benchmark voltage return to the base of the oscillating tube pole to adjust the level of the oscillation frequency, if the transformer secondary voltage is increased, the sampling coil output voltage increases, the positive feedback voltage obtained through the optocoupler is also increased, this voltage is applied oscillating tube base, so that oscillation frequency is reduced, played a stable secondary output voltage stability, too small do not have to go into detail, nor it is necessary to understand the fine, such a high-power voltage transformer by switching transmission, separated and after the class returned by sampling the voltage from the opto-coupler pass separated after class, so before the mains voltage, and after the classseparation, which is called cold plate, it is safe, transformers before power is independent, which is called switching power supply.the DC / DC conversionDC / DC converter is a fixed DC voltage transformation into a variable DC voltage, also known as the DC chopper. There are two ways of working chopper, one Ts constant pulse width modulation mode, change the ton (General), the second is the frequency modulation, the same ton to change the Ts, (easy to produce interference). Circuit by the following categories:Buck circuit - the step-down chopper, the average output voltage U0 is less than the input voltage Ui, the same polarity.Boost Circuit - step-up chopper, the average output voltage switching power supply schematic U0 is greater than the input voltage Ui, the same polarity.Buck-Boost circuit - buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, the inductance transmission.Cuk circuit - a buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, capacitance transmission.The above-mentioned non-isolated circuit, the isolation circuit forward circuits, feedback circuit, the half-bridge circuit, the full bridge circuit, push-pull circuit. Today's soft-switching technology makes a qualitative leap in the DC / DC the U.S. VICOR company design and manufacture a variety of ECI soft-switching DC / DC converter, the maximum output power 300W, 600W, 800W, etc., the corresponding power density (6.2 , 10,17) W/cm3 efficiency (80-90)%. A the Japanese Nemic Lambda latest using soft-switching technology, high frequency switching power supply module RM Series, its switching frequency (200 to 300) kHz, power density has reached 27W/cm3 with synchronous rectifier (MOSFETs instead of Schottky diodes ), so that the whole circuit efficiency by up to 90%.AC / DC conversionAC / DC conversion will transform AC to DC, the power flow can be bi-directional power flow by the power flow to load known as the "rectification", referred to as "active inverter power flow returned by the load power. AC / DC converter input 50/60Hz AC due must be rectified, filtered, so the volume is relatively large filter capacitor is essential, while experiencing safety standards (such as UL, CCEE, etc.) and EMC Directive restrictions (such as IEC, FCC, CSA) in the AC input side must be added to the EMC filter and use meets the safety standards of the components, thus limiting the miniaturization of the volume of AC / DC power, In addition, due to internal frequency, high voltage, current switching, making the problem difficult to solve EMC also high demands on the internal high-density mountingcircuit design, for the same reason, the high voltage, high current switch makes power supply loss increases, limiting the AC / DC converter modular process, and therefore must be used to power system optimal design method to make it work efficiency to reach a certain level of satisfaction.AC / DC conversion circuit wiring can be divided into half-wave circuit, full-wave circuit. Press the power phase can be divided into single-phase three-phase, multiphase. Can be divided into a quadrant, two quadrant, three quadrants, four-quadrant circuit work quadrant.he selection of the switching power supplySwitching power supply input on the anti-jamming performance, compared to its circuit structure characteristics (multi-level series), the input disturbances, such as surge voltage is difficult to pass on the stability of the output voltage of the technical indicators and linear power have greater advantages, the output voltage stability up to (0.5)%. Switching power supply module as an integrated power electronic devices should be selected。

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Highway Subgrade Construction in Expansive Soil AreasJian-Long Zheng1Rui Zhang2and He-Ping Yang31 Professor and President, ChangSha Univ. of Science and Technology, Chiling Road 45, Changsha, Hunan 410076, China. E-mail: zjl_csust@2 Ph.D. Candidate and Lecturer, School of Highway Engineering, ChangSha Univ. of Science and Technology, Chiling Road 45, Changsha, Hunan 410076, China. E-mail: zr_csust@3Professor, School of Highway Engineering, ChangSha Univ. of Science and Technology, Chiling Road 45, Changsha, Hunan 410076, China. E-mail: cscuyang@(Accepted 22 May 2007)IntroductionExpansive soil is predominantly clay soil that undergoes appreciable volume and strength changes following a change in moisture content. These volume changes can cause extensive damage to the geotechnical infrastructure, and the damage is often repeatable and latent in the long term (Liao 19848). China is one of the countries with a wide distribution of expansive soils. They are found in more than 20 provinces and regions, nearly 600,000 km2in extent. It has been estimated that the planned highways totaling 3,300 km in length pass through expansive soils areas (Zheng and Yang 200422). Improper highway construction in such areas could well lead to great losses and damage to the environment.In 2002, the Chinese Ministry of Communications (CMOC) sponsored a research project, “A Complete Package for Highway Construction in Expansive Soil Areas,” whose primary objective was to solve expansive soil problems in highway engineering. A research group with personnel from Changsha University of Science and Technology (CUST) was set up. Comprehensive laboratory tests, field investigations, and analyses were carried out, aimed at solving highway engineering problems in several different expansive soil areas. A complete presentation of the results of this research is beyond the scope of this paper, but the research on subgradeconstruction for the Nanning to Youyi Guan (NanYou) highway will be discussed to introduce the laboratory studies performed on soil properties, classification of swelling potential, and engineering properties of expansive filler soils. Field investigations of slope failures in the Ningming area also will be described. Several new techniques for building embankments and treating expansive soil cut slopes also are presented.Site GeologyNingming Basin lies in south China. The region has in an oceanic monsoon climate with long summers and quite short winters. The annual average temperature is 22.1° centigrade and the annual rainfall is about 1,200 mm, falling mostly from April to August. There is a very obvious difference between the rainy and dry seasons. The Ningming Basin is an east–west tectonic faulted basin formed in Q2–4, with deposits of lacustrine mudshale from the Nadu formation (N y) of the Eocene, 1,500 m in thickness. Argillaceous siltstone and little siltstone are present as well. The obliquity of the stratum is about 5°–7°in the middle of the basin, but 22°at the edge. In addition, there are Jurassic and Triassic siltstone and limestone around the basin.A typical geological profile from the Ningming area is shown in Fig. 1. Ningming expansive soils, dark or light gray in color, are of residual origin from the weathering of mudshale or shale from the Nadu formation of the Eocene. Due to the parent rock’s structure, the residual expansive soils have a residual fabric (microbedding and tiny tectonic fissures) originating from the parent rock, and many included ferromanganese nodules. The weathered mudshale, once exposed, collapses rapidly into smaller prism-shaped fragments, which can continue to fragment into smaller and smaller pieces. A great many vertical, cross and horizontal tectonic joints, tectonic fissures, and weathered fissures clearly can be seen in excavated profiles, and a soft interlayer exists between the soil and mudshale layers. The active zone, about 3-m thick (CMOC 1996b10) is several meters below the surface, but nevertheless affected by seasonal climatic changes (Nelson and Miller 199213).Research on Embankment Construction and Its Engineering ApplicationIn expansive soil areas, embankments filled with expansive soils usually encounter nonuniform settlement (Hu et al. 20044). Road shoulders, which cannot be compacted, adequately, develop large longitudinal cracks, and large wave deformations appear along the cross section. The bearing capacity of the pavement decreases substantially as a result of the reduced resilient modulus of the subgrade, and slope surface failures usually occur. Embankment failures usually involve three phases: shrinkage cracks form in the slope during the dry season; water infiltrates into the soil mass through the cracks in the subsequent wet season, with soil swelling; and finally, the shear strength of the clayey soil deteriorates to the extent that the shear forces within the slope cannot be adequately resisted, resulting in a localized slope failure. Generally, times until failure can range from several months to several years (Zhang et al. 2005).Selection of Embankment FillerIt has been stipulated in China’s Technical Specification for the Construction of Highway Subgrades (CMOC 1996a11) that expansive soil with a high swelling potential should not be used as embankment fill material due to its poor water stability. Expansive soil with medium swelling potential can be used as filler only after it has been improved. Expansive soil with low swelling potential can be used as filler according to the climate, hydrological conditions, and the highway classification, but the side slopes and top of the embankment should be protected. In light of these specifications, nearly five million m3of expansive soils and highly weathered mudshale excavated for the construction of the NanYou highway in the Ningming area could not be used as embankment filler without being improved, because they are characterized as having moderate swelling potential.Consequently, the research group studied stabilizing expansive soils with calcium lime, Portland cement, and mixtures of lime and cement in the laboratory. The resulting clay contents, compressibility, California bearing ratio (CBR), and swelling capabilities showed that the improving effect of the lime was the greatest (Chen 20042). For light-gray expansive soil, the optimum lime content was determined to be 3%, and the optimum moisture content was 15.2%. These values were determined by compaction tests at 2,684.9 kj/m3. The resulting CBR and soakedswelling ratio satisfied the specifications for fill. However, in practice it is very hard to mix lime and expansive soil properly because the natural moisture content of the soil is so very high. The soil easily agglomerates, so the operation is complicated and requires heavy construction machinery. In addition, the high price of lime will greatly increase highway construction costs, and lime dust that inevitably escapes during spreading will do some harm to the environment. Therefore, lime stabilization is not popular in engineering practice. However, if the expansive soils must be replaced by nonexpansive material transported from several hundred kilometers away that would entail high costs and environmental degradation.According to the Chinese specification, the CBR of fill in an upper embankment (less than 1.5 m below the embankment surface) should reach 4%, and it should be 3% for the material in the lower embankment (more than 1.5 m below the surface). In light of the routine soaking that is part of the CBR test method, the CBR of expansive soils can rarely reach 3%. However, according to the change of CBR with moisture content (Fig. 3), and the change in swell percent of CBR samples with time , the research group found that if the CBR samples were not soaked, the CBR was very high at relatively low moisture content. Therefore, research was carried out on the feasibility of using expansive soils as fill, including research on evaluating their bearing capacity and the field compaction control of expansive soil fill.Changes in California bearing ratio with moisture contentEvaluating the Bearing Capacity of Expansive SoilsSubgrade “stiffness” controls the total pavement thickness, especially with flexible pavements. So, it is very important to correctly test the stiffness of subgrade materials, and the conditions (density and moisture content) at which the material is tested should be considered. The CBR testing condition stipulated in China’s Test Methods of Soils for Highway Engineering (CMOC 1996b) involves compacting the material in a mold (0.152 m in diameter and 0.120 m high) and soaking for 4 days under a surcharge weight of 50 N, corresponding to 2.7 kPa. However, for clayey materials, this procedure leads to only the upper and lower parts of the sample becoming saturated or nearly saturated, because of the low permeability of clay, especially for expansive soils, and the air entrapped in the sample. The measuredCBR then only corresponds to the saturated soil in the shallow upper part, where the soil has disintegrated under the light surcharge after soaking (Uzan 1998).However, suppose expansive soil is used as fill in the lower embankment and nonexpansive fill material is used in the upper as a moisture barrier. Then, the surface of the lower embankment would not be soaked, and the upward pressure on the surface would no longer be 50 N. Therefore, the research group studied a modified CBR test on expansive soil simulating such field conditions. The study mainly focused on weathered mudshale, whose swell potential is medium, and which formeda large percentage of excavated material in the construction of the NanYou Highway.1.Li, S. L., Qin, S. J, and Bo, Z. Z. (1992). Studies on the engineering geology of expansive soils in China, Jiangsu Science and Technology Publishing House, Nanjing, China, 212.2.Liao, S. W. (1984). Expansive soil and railway engineering, Chinese Railway Publishing Press, Beijing, 374.3.Mao, Y. C. (2006). “Tests on the feasibility of using expansive soil as embankment fill.” MSc thesis, Changsha Univ. of Science and Technology, Changsha, China.4.Ministry of Communications of the People's Republic of China (CMOC). (1996a). Technical specifications for the construction of highway subgrades JTJ033-95., Renmin Communication Press, Beijing.5.Ministry of Communications of the People's Republic of China (CMOC). (2003). Specifications for the design of highway subgrades JTJ013-2002, Renmin Communication Press, Beijing, 156.6.Ministry of Communications Second Highway Survey Design and Research Institute of China (CMOC). (1996b). Handbook of design for highway subgrades, 2nd Ed., Renmin Communication Press, Beijing, 407.7.Uzan, J. (1998). “Characterization of clayey subgrade materials for mechanistic design of flexible pavements.” Transportation Research Record. 1629, National Research Council, Transportation Research Board, Washington, D. C., 188–196.8.Wei, T. Z. (1990). “Some factors influencing on deformation of foundation on expansive soil in Guangxi.” Proc., 1st Chinese Symp. on Expansive Soils, Southwest Jiaotong University, Chengdu, 232–238.9.Yang, H. P. (1999). “Approach to strengthening expansive soil embankment side slope with geogrid.” Chinese J. Highw., 16(3), 42–46.10.Yang, H. P., Qu, Y. X., and Zheng, J. L. (2005). “New developments in studies of Ningming expansive soils.” Chinese J. Geotech. Eng., 17(9), 981–987.。

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