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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.。
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Worlds Collide:
Exploring the Use of Social Media Technologies for
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世界的碰撞：
探索社交媒体技术在在线学习的应用
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毕业设计论文外文文献翻译
毕业设计(论文）外文文献翻译院系：财务与会计学院年级专业：201＊级财务管理姓名:学号：132148*＊*附件: 财务风险管理【Abstract】Although financial risk has increased significantly in recent years risk and risk management are not contemporary issues。
The result of increasingly global markets is that risk may originate with events thousands of miles away that have nothing to do with the domestic market。
Information is available instantaneously which means that change and subsequent market reactions occur very quickly。
The economic climate and markets can be affected very quickly by changes in exchange rates interest rates and commodity prices。
Counterparties can rapidly become problematic。
As a result it is important to ensure financial risks are identified and managed appropriately. Preparation is a key component of risk management。
【Key Words】Financial risk，Risk management，YieldsI. Financial risks arising1.1What Is Risk1.1.1The concept of riskRisk provides the basis for opportunity. The terms risk and exposure have subtle differences in their meaning. Risk refers to the probability of loss while exposure is the possibility of loss although they are often used interchangeably。
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毕设外文文献+翻译1外文翻译外文原文CHANGING ROLES OF THE CLIENTS、ARCHITECTSAND CONTRACTORS THROUGH BIMAbstract:Purpose –This paper aims to present a general review of the practical implications of building information modelling (BIM) based on literature and case studies. It seeks to address the necessity for applying BIM and re-organising the processes and roles in hospital building projects. This type of project is complex due to complicated functional and technical requirements, decision making involving a large number of stakeholders, and long-term development processes.Design/methodology/approach–Through desk research and referring to the ongoing European research project InPro, the framework for integrated collaboration and the use of BIM are analysed.Findings –One of the main findings is the identification of the main factors for a successful collaboration using BIM, which can be recognised as “POWER”: product information sharing (P),organisational roles synergy (O), work processes coordination (W), environment for teamwork (E), and reference data consolidation (R).Originality/value –This paper contributes to the actual discussion in science and practice on the changing roles and processes that are required to develop and operate sustainable buildings with the support of integrated ICT frameworks and tools. It presents the state-of-the-art of European research projects and some of the first real cases of BIM application inhospital building projects.Keywords:Europe, Hospitals, The Netherlands, Construction works, Response flexibility, Project planningPaper type :General review1. IntroductionHospital building projects, are of key importance, and involve significant investment, and usually take a long-term development period. Hospital building projects are also very complex due to the complicated requirements regarding hygiene, safety, special equipments, and handling of a large amount of data. The building process is very dynamic and comprises iterative phases and intermediate changes. Many actors with shifting agendas, roles and responsibilities are actively involved, such as: the healthcare institutions, national and local governments, project developers, financial institutions, architects, contractors, advisors, facility managers, and equipment manufacturers and suppliers. Such building projects are very much influenced, by the healthcare policy, which changes rapidly in response to the medical, societal and technological developments, and varies greatly between countries (World Health Organization, 2000). In The Netherlands, for example, the way a building project in the healthcare sector is organised is undergoing a major reform due to a fundamental change in the Dutch health policy that was introduced in 2008.The rapidly changing context posts a need for a building with flexibility over its lifecycle. In order to incorporate life-cycle considerations in the building design, construction technique, and facility management strategy, a multidisciplinary collaboration is required. Despite the attempt for establishing integrated collaboration, healthcare building projects still facesserious problems in practice, such as: budget overrun, delay, and sub-optimal quality in terms of flexibility, end-user?s dissatisfaction, and energy inefficiency. It is evident that the lack of communication and coordination between the actors involved in the different phases of a building project is among the most important reasons behind these problems. The communication between different stakeholders becomes critical, as each stakeholder possesses different setof skills. As a result, the processes for extraction, interpretation, and communication of complex design information from drawings and documents are often time-consuming and difficult. Advanced visualisation technologies, like 4D planning have tremendous potential to increase the communication efficiency and interpretation ability of the project team members. However, their use as an effective communication tool is still limited and not fully explored. There are also other barriers in the information transfer and integration, for instance: many existing ICT systems do not support the openness of the data and structure that is prerequisite for an effective collaboration between different building actors or disciplines.Building information modelling (BIM) offers an integrated solution to the previously mentioned problems. Therefore, BIM is increasingly used as an ICT support in complex building projects. An effective multidisciplinary collaboration supported by an optimal use of BIM require changing roles of the clients, architects, and contractors; new contractual relationships; and re-organised collaborative processes. Unfortunately, there are still gaps in the practical knowledge on how to manage the building actors to collaborate effectively in their changing roles, and todevelop and utilise BIM as an optimal ICT support of the collaboration.This paper presents a general review of the practical implications of building information modelling (BIM) based on literature review and case studies. In the next sections, based on literature and recent findings from European research project InPro, the framework for integrated collaboration and the use of BIM are analysed. Subsequently, through the observation of two ongoing pilot projects in The Netherlands, the changing roles of clients, architects, and contractors through BIM application are investigated. In conclusion, the critical success factors as well as the main barriers of a successful integrated collaboration using BIM are identified.2. Changing roles through integrated collaboration and life-cycle design approachesA hospital building project involves various actors, roles, and knowledge domains. In The Netherlands, the changing roles of clients, architects, and contractors in hospital building projects are inevitable due the new healthcare policy. Previously under the Healthcare Institutions Act (WTZi), healthcare institutions were required to obtain both a license and a building permit for new construction projects and major renovations. The permit was issued by the Dutch Ministry of Health. The healthcare institutions were then eligible to receive financial support from the government. Since 2008, new legislation on the management of hospital building projects and real estate has come into force. In this new legislation, a permit for hospital building project under the WTZi is no longer obligatory, nor obtainable (Dutch Ministry of Health, Welfare and Sport, 2008). This change allows more freedom from the state-directed policy, and respectively,allocates more responsibilities to the healthcare organisations to deal with the financing and management of their real estate. The new policy implies that the healthcare institutions are fully responsible to man age and finance their building projects and real estate. The government?s support for the costs of healthcare facilities will no longer be given separately, but will be included in the fee for healthcare services. This means that healthcare institutions must earn back their investment on real estate through their services. This new policy intends to stimulate sustainable innovations in the design, procurement and management of healthcare buildings, which will contribute to effective and efficient primary healthcare services.The new strategy for building projects and real estate management endorses an integrated collaboration approach. In order to assure the sustainability during construction, use, and maintenance, the end-users, facility managers, contractors and specialist contractors need to be involved in the planning and design processes. The implications of the new strategy are reflected in the changing roles of the building actors and in the new procurement method.In the traditional procurement method, the design, and its details, are developed by the architect, and design engineers. Then, the client (the healthcare institution) sends an application to the Ministry of Healthto obtain an approval on the building permit and the financial support from the government. Following this, a contractor is selected through a tender process that emphasises the search for the lowest-price bidder. During the construction period, changes often take place due to constructability problems of the design and new requirements from the client.Because of the high level of technical complexity, and moreover, decision-making complexities, the whole process from initiation until delivery of a hospital building project can take up to ten years time. After the delivery, the healthcare institution is fully in charge of the operation of the facilities. Redesigns and changes also take place in the use phase to cope with new functions and developments in the medical world.The integrated procurement pictures a new contractual relationship between the parties involved in a building project. Instead of a relationship between the client and architect for design, and the client and contractor for construction, in an integrated procurement the client only holds a contractual relationship with the main party that is responsible for both design and construction. The traditional borders between tasks and occupational groups become blurred since architects, consulting firms, contractors, subcontractors, and suppliers all stand on the supply side in the building process while the client on the demand side. Such configuration puts the architect, engineer and contractor in a very different position that influences not only their roles, but also their responsibilities, tasks and communication with the client, the users, the team and other stakeholders.The transition from traditional to integrated procurement method requires a shift of mindset of the parties on both the demand and supply sides. It is essential for the client and contractor to have a fair and open collaboration in which both can optimally use their competencies. The effectiveness of integrated collaboration is also determined by the client?s capacity and strategy to organize innovative tendering procedures.A new challenge emerges in case of positioning an architect in a partnership with the contractor instead of with the client. In case of the architect enters a partnership with the contractor, an important issues is how to ensure the realisation of the architectural values as well as innovative engineering through an efficient construction process. In another case, the architect can stand at the client?s side in a strategic advisory role instead of being the designer. In this case, the architect?s responsibility is translating client?s requirements and wishes into the architectural values to be included in the design specification, and evaluating the contractor?s proposal against this. In any of this new role, the architect holds the responsibilities as stakeholder interest facilitator, custodian of customer value and custodian of design models.The transition from traditional to integrated procurement method also brings consequences in the payment schemes. In the traditional building process, the honorarium for the architect is usually based on a percentage of the project costs; this may simply mean that the more expensive the building is, the higher the honorarium will be. The engineer receives the honorarium based on the complexity of the design and the intensity of the assignment. A highly complex building, which takes a number of redesigns, is usually favourable for the engineers in terms of honorarium. A traditional contractor usually receives the commission based on the tender to construct the building at the lowest price by meeting the minimum specifications given by the client. Extra work due to modifications is charged separately to the client. After the delivery, the contractor is no longer responsible for the long-term use of the building. In the traditional procurement method, all risks are placed with theclient.In integrated procurement method, the payment is based on the achieved building performance; thus, the payment is non-adversarial. Since the architect, engineer and contractor have a wider responsibility on the quality of the design and the building, the payment is linked to a measurement system of the functional and technical performance of the building over a certain period of time. The honorarium becomes an incentive to achieve the optimal quality. If the building actors succeed to deliver a higher added-value thatexceed the minimum client?s requirements, they will receive a bonus in accordance to the client?s extra gain. The level of transparency is also improved. Open book accounting is an excellent instrument provided that the stakeholders agree on the information to be shared and to its level of detail (InPro, 2009).Next to the adoption of integrated procurement method, the new real estate strategy for hospital building projects addresses an innovative product development and life-cycle design approaches. A sustainable business case for the investment and exploitation of hospital buildings relies on dynamic life-cycle management that includes considerations and analysis of the market development over time next to the building life-cycle costs (investment/initial cost, operational cost, and logistic cost). Compared to the conventional life-cycle costing method, the dynamic life-cycle management encompasses a shift from focusing only on minimizing the costs to focusing on maximizing the total benefit that can be gained. One of the determining factors for a successful implementation of dynamic life-cycle management is the sustainable design of the building and building components, which means that the design carriessufficient flexibility to accommodate possible changes in the long term (Prins, 1992).Designing based on the principles of life-cycle management affects the role of the architect, as he needs to be well informed about the usage scenarios and related financial arrangements, the changing social and physical environments, and new technologies. Design needs to integrate people activities and business strategies over time. In this context, the architect is required to align the design strategies with the organisational, local and global policies on finance, business operations, health and safety, environment, etc.The combination of process and product innovation, and the changing roles of the building actors can be accommodated by integrated project delivery or IPD (AIA California Council, 2007). IPD is an approach that integrates people, systems, business structures and practices into a process that collaboratively harnesses the talents and insights of all participants to reduce waste and optimize efficiency through all phases of design, fabrication and construction. IPD principles can be applied to a variety of contractual arrangements. IPD teams will usually include members well beyond the basic triad of client, architect, and contractor. At a minimum, though, an Integrated Project should include a tight collaboration between the client, the architect, and the main contractor ultimately responsible for construction of the project, from the early design until the project handover. The key to a successful IPD is assembling a team that is committed to collaborative processes and is capable of working together effectively. IPD is built on collaboration. As a result, it can only be successful if the participants share and apply common values and goals.3. Changing roles through BIM applicationBuilding information model (BIM) comprises ICT frameworks and tools that can support the integrated collaboration based on life-cycle design approach. BIM is a digital representation of physical and functional characteristics of a facility. As such it serves as a shared knowledge resource for information about a facility forming a reliable basis for decisions during its lifecycle from inception onward (National Institute of Building Sciences NIBS, 2007). BIM facilitates time and place independent collaborative working. A basic premise of BIM is collaboration by different stakeholders at different phases of the life cycle of a facility to insert, extract, update or modify information in the BIM to support and reflect the roles of that stakeholder. BIM in its ultimate form, as a shared digital representation founded on open standards for interoperability, can become a virtual information model to be handed from the design team to the contractor and subcontractors and then to the client.BIM is not the same as the earlier known computer aided design (CAD). BIM goes further than an application to generate digital (2D or 3D) drawings. BIM is an integrated model in which all process and product information is combined, stored, elaborated, and interactively distributed to all relevant building actors. As a central model for all involved actors throughout the project lifecycle, BIM develops andevolves as the project progresses. Using BIM, the proposed design and engineering solutions can be measured against the client?s requirements and expected building performance. The functionalities of BIM to support the design process extend to multidimensional (nD), including: three-dimensional visualisation and detailing, clash detection, material schedule, planning, costestimate, production and logistic information, and as-built documents. During the construction process, BIM can support the communication between the building site, the factory and the design office– which is crucial for an effective and efficient prefabrication and assembly processes as well as to prevent or solve problems related to unforeseen errors or modifications. When the building is in use, BIM can be used in combination with the intelligent building systems to provide and maintain up-to-date information of the building performance, including the life-cycle cost.To unleash the full potential of more efficient information exchange in the AEC/FM industry in collaborative working using BIM, both high quality open international standards and high quality implementations of these standards must be in place. The IFC open standard is generally agreed to be of high quality and is widely implemented in software. Unfortunately, the certification process allows poor quality implementations to be certified and essentially renders the certified software useless for any practical usage with IFC. IFC compliant BIM is actually used less than manual drafting for architects and contractors, and show about the same usage for engineers. A recent survey shows that CAD (as a closed-system) is still the major form of technique used in design work (over 60 per cent) while BIM is used in around 20 percent of projects for architects and in around 10 per cent of projects for engineers and contractors.The application of BIM to support an optimal cross-disciplinary and cross-phase collaboration opens a new dimension in the roles and relationships between the building actors. Several most relevant issues are: the new role of a model manager; the agreement on the access right and IntellectualProperty Right (IPR); the liability and payment arrangement according to the type of contract and in relation to the integrated procurement; and the use of open international standards.Collaborative working using BIM demands a new expert role of a model manager who possesses ICT as well as construction process know-how (InPro, 2009). The model manager deals with the system as well as with the actors. He provides and maintains technological solutions required for BIM functionalities, manages the information flow, and improves the ICT skills of the stakeholders. The model manager does not take decisions on design and engineering solutions, nor the organisational processes, but his roles in the chain of decision making are focused on:the development of BIM, the definition of the structure and detail level of the model, and the deployment of relevant BIM tools, such as for models checking, merging, and clash detections;the contribution to collaboration methods, especially decision making and communication protocols, task planning, and risk management;and the management of information, in terms of data flow and storage, identification of communication errors, and decision or process (re-)tracking.Regarding the legal and organisational issues, one of the actual questions is: “In what way does the intellectual property right (IPR) in collaborative working using BIM differ from the IPR in a traditional teamwork?”. In terms of combine d work, the IPR of each element is at tached to its creator. Although it seems to be a fully integrated design, BIM actually resulted from a combination of works/elements; for instance: the outline of the building design, is created by the architect, the design for theelectrical system, is created by the electrical contractor, etc. Thus, in case of BIM as a combined work, the IPR is similar to traditional teamwork. Working with BIM with authorship registration functionalities may actually make it easier to keep track of the IPR.How does collaborative working, using BIM, effect the contractual relationship? On the one hand,collaborative working using BIM does not necessarily change the liability position in the contract nor does it obligate an alliance contract. The General Principles of BIM A ddendum confirms: …This does not effectuate or require a restructuring of contractual relationships or shifting of risks between or among the Project Participants other than as specifically required per the Protocol Addendum and its Attachments? (ConsensusDOCS, 2008). On the other hand, changes in terms of payment schemes can be anticipated. Collaborative processes using BIM will lead to the shifting of activities from to the early design phase. Much, if not all, activities in the detailed engineering and specification phase will be done in the earlier phases. It means that significant payment for the engineering phase, which may count up to 40 per cent of the design cost, can no longer be expected. As engineering work is done concurrently with the design, a new proportion of the payment in the early design phase is necessary.4. Review of ongoing hospital building projects using BIMIn The Netherlands, the changing roles in hospital building projects are part of the strategy, which aims at achieving a sustainable real estate in response to the changing healthcare policy. Referring to literature and previous research, the main factors that influence the success of the changing roles can be concluded as: the implementation of an integrated procurementmethod and a life-cycle design approach for a sustainable collaborative process; the agreement on the BIM structure and the intellectual rights; and the integration of the role of a model manager. The preceding sections have discussed the conceptual thinking on how to deal with these factors effectively. This current section observes two actual projects and compares the actual practice with the conceptual view respectively.The main issues, which are observed in the case studies, are: the selected procurement method and the roles of the involved parties within this method;the implementation of the life-cycle design approach;the type, structure, and functionalities of BIM used in the project;the openness in data sharing and transfer of the model, and the intended use of BIM in the future; and the roles and tasks of the model manager.The pilot experience of hospital building projects using BIM in the Netherlands can be observed at University Medical Centre St Radboud (further referred as UMC) and Maxima Medical Centre (further referred as MMC). At UMC, the new building project for the Faculty of Dentistry in the city of Nijmegen has been dedicated as a BIM pilot project. At MMC, BIM is used in designing new buildings for Medical Simulation and Mother-and-Child Centre in the city of Veldhoven.The first case is a project at the University Medical Centre (UMC) St Radboud. UMC is more than just a hospital. UMC combines medical services, education and research. More than 8500 staff and 3000 students work at UMC. As a part of the innovative real estate strategy, UMC has considered to use BIM for its building projects. The new development of the Faculty ofDentistry and the surrounding buildings on the Kapittelweg in Nijmegen has been chosen as a pilot project to gather practical knowledge and experience on collaborative processes with BIM support.The main ambition to be achieved through the use of BIM in the building projects at UMC can be summarised as follows: using 3D visualisation to enhance the coordination and communication among the building actors, and the user participation in design;integrating the architectural design with structural analysis, energy analysis, cost estimation, and planning;interactively evaluating the design solutions against the programme of requirements and specifications;reducing redesign/remake costs through clash detection during the design process; andoptimising the management of the facility through the registration of medical installations andequipments, fixed and flexible furniture, product and output specifications, and operational data.The second case is a project at the Maxima Medical Centre (MMC). MMC is a large hospital resulted from a merger between the Diaconessenhuis in Eindhoven and St Joseph Hospital in Veldhoven. Annually the 3,400 staff of MMC provides medical services to more than 450,000 visitors and patients. A large-scaled extension project of the hospital in Veldhoven is a part of its real estate strategy. A medical simulation centre and a women-and-children medical centre are among the most important new facilities within this extension project. The design has been developed using 3D modelling with several functionalities of BIM.The findings from both cases and the analysis are as follows.Both UMC and MMC opted for a traditional procurement method in which the client directly contracted an architect, a structural engineer, and a mechanical, electrical and plumbing (MEP) consultant in the design team. Once the design and detailed specifications are finished, a tender procedure will follow to select a contractor. Despite the choice for this traditional method, many attempts have been made for a closer and more effective multidisciplinary collaboration. UMC dedicated a relatively long preparation phase with the architect, structural engineer and MEP consultant before the design commenced. This preparation phase was aimed at creating a common vision on the optimal way for collaboration using BIM as an ICT support. Some results of this preparation phase are: a document that defines the common ambition for the project and the collaborative working process and a semi-formal agreement that states the commitment of the building actors for collaboration. Other than UMC, MMC selected an architecture firm with an in-house engineering department. Thus, the collaboration between the architect and structural engineer can take place within the same firm using the same software application.Regarding the life-cycle design approach, the main attention is given on life-cycle costs, maintenance needs, and facility management. Using BIM, both hospitals intend to get a much better insight in these aspects over the life-cycle period. The life-cycle sustainability criteria are included in the assignments for the design teams. Multidisciplinary designers and engineers are asked to collaborate more closely and to interact with the end-users to address life-cycle requirements. However, ensuring the building actors to engage in an integrated collaboration to generate sustainable design solutions that meet the life-cycle。
毕业设计外文文献翻译(原文+译文)
Environmental problems caused by Istanbul subway excavation and suggestionsfor remediation伊斯坦布尔地铁开挖引起的环境问题及补救建议Ibrahim Ocak Abstract：Many environmental problems caused by subway excavations have inevitably become an important point in city life. These problems can be categorized as transporting and stocking of excavated material, traffic jams, noise, vibrations, piles of dust mud and lack of supplies. Although these problems cause many difficulties,the most pressing for a big city like Istanbul is excava tion,since other listed difficulties result from it. Moreover, these problems are environmentally and regionally restricted to the period over which construction projects are underway and disappear when construction is finished. Currently, in Istanbul, there are nine subway construction projects in operation, covering approximately 73 km in length; over 200 km to be constructed in the near future. The amount of material excavated from ongoing construction projects covers approximately 12 million m3. In this study, problems—primarily, the problem with excavation waste(EW)—caused by subway excavation are analyzed and suggestions for remediation are offered.摘要：许多地铁开挖引起的环境问题不可避免地成为城市生活的重要部分。
毕业设计外文文献翻译范文
毕业设计外文文献翻译专业学生姓名班级学号指导教师优集学院外文资料名称：Knowledge-Based Engineeri--ng Design Methodology外文资料出处：Int.J.Engng Ed.Vol.16.No.1附件： 1.外文资料翻译译文2.外文原文基于知识工程(KBE)设计方法D. E. CALKINS1.背景复杂系统的发展需要很多工程和管理方面的知识、决策，它要满足很多竞争性的要求。
设计被认为是决定产品最终形态、成本、可靠性、市场接受程度的首要因素。
高级别的工程设计和分析过程(概念设计阶段)特别重要，因为大多数的生命周期成本和整体系统的质量都在这个阶段。
产品成本的压缩最可能发生在产品设计的最初阶段。
整个生命周期阶段大约百分之七十的成本花费在概念设计阶段结束时，缩短设计周期的关键是缩短概念设计阶段，这样同时也减少了工程的重新设计工作量。
工程权衡过程中采用良好的估计和非正式的启发进行概念设计。
传统CAD工具对概念设计阶段的支持非常有限。
有必要，进行涉及多个学科的交流合作来快速进行设计分析(包括性能，成本，可靠性等)。
最后，必须能够管理大量的特定领域的知识。
解决方案是在概念设计阶段包含进更过资源，通过消除重新设计来缩短整个产品的时间。
所有这些因素都主张采取综合设计工具和环境，以在早期的综合设计阶段提供帮助。
这种集成设计工具能够使由不同学科的工程师、设计者在面对复杂的需求和约束时能够对设计意图达成共识。
那个设计工具可以让设计团队研究在更高级别上的更多配置细节。
问题就是架构一个设计工具，以满足所有这些要求。
2.虚拟(数字)原型模型现在需要是一种代表产品设计为得到一将允许一产品的早发展和评价的真实事实上原型的过程的方式。
虚拟样机将取代传统的物理样机，并允许设计工程师，研究“假设”的情况，同时反复更新他们的设计。
真正的虚拟原型，不仅代表形状和形式，即几何形状，它也代表如重量，材料，性能和制造工艺的非几何属性。
毕业设计(论文)外文翻译【范本模板】
华南理工大学广州学院本科生毕业设计(论文）翻译英文原文名Review of Vibration Analysis Methods for Gearbox Diagnostics and Prognostics中文译名对变速箱振动分析的诊断和预测方法综述学院汽车工程学院专业班级车辆工程七班学生姓名刘嘉先学生学号201130085184指导教师李利平填写日期2015年3月15日英文原文版出处：Proceedings of the 54th Meeting of the Society for Machinery Failure Prevention Technology, Virginia Beach，V A, May 1-4，2000，p. 623-634译文成绩：指导教师(导师组长）签名：译文：简介特征提取技术在文献中有描述;然而，大多数人似乎掩盖所需的特定的预处理功能。
一些文件没有提供足够的细节重现他们的结果，并没有一个全面的比较传统的功能过渡齿轮箱数据。
常用术语,如“残差信号”,是指在不同的文件不同的技术.试图定义了状态维修社区中的常用术语和建立所需的特定的预处理加工特性。
本文的重点是对所使用的齿轮故障检测功能。
功能分为五个不同的组基于预处理的需要。
论文的第一部分将提供预处理流程的概述和其中每个特性计算的处理方案。
在下一节中，为特征提取技术描述，将更详细地讨论每一个功能。
最后一节将简要概述的宾夕法尼亚州立大学陆军研究实验室的CBM工具箱用于齿轮故障诊断。
特征提取概述许多类型的缺陷或损伤会增加机械振动水平。
这些振动水平，然后由加速度转换为电信号进行数据测量。
原则上,关于受监视的计算机的健康的信息被包含在这个振动签名。
因此，新的或当前振动签名可以与以前的签名进行比较,以确定该元件是否正常行为或显示故障的迹象。
在实践中，这种比较是不能奏效的。
由于大的变型中,签名的直接比较是困难的。
相反,一个涉及从所述振动署名数据特征提取更多有用的技术也可以使用。
毕业设计外文翻译样本
Influence of underground water seepage flow on surrounding rockdeformation of multi-arch tunnelAbstract: Based on a typical multi-arch tunnel in a freeway, the fast Lagrangian analysis of continua in3 dimensions(FLAC ) was used to calculate the surrounding rock deformation of the tunnel under which the effect of underground water seepage flow was taken into account or not. The distribution of displacement field around the multi-arch tunnel, which is influenced by the seepage field, was gained. The result indicates that the settlement values of the vault derived from coupling analysis are bigger when considering the seepage flow effect than that not considering. Through the contrast of arch subsidence quantities calculated by two kinds of computation situations, and the comparison between the calculated and measured value of tunnel vault settlement, it is found that the calculated value(5.7−6.0 mm) derived from considering the seepage effect is more close to the measured value(5.8−6.8 mm). Therefore, it is quite necessary to consider the seepage flow effect of the underground water in aquiferous stratum for multi-arch tunnel design. key words: multi-arch tunnel; underground water seepage flow; coupling flow and stress; surrounding rock deformation; vault settlement1 IntroductionWith high speed development of our national economy, the highway is constructed on large-scale all around the country. Along the freeway from Changsha to Chongqing(one section of which is from Changde to Jishou), many tunnels have to be constructed. As these tunnels’s topography and geomorphic conditions are very complex and the rain is very rich, the invasion of underground water and surface water is a difficult problem in the tunnel construction and its future function. In the past railway and highway tunnel construction, some effective waterproof construction technologies were proposed . But the researches on the mechanism of coupling function of fluid and stress and its influence on tunnels are not enough. For example, LIU and CHENcalculated and analyzed the double-arch tunnel structure in water-eroded groove but did not consider the underground water seepage force. YANG et al studied the earthquake response of large span and double-arch shallow tunnel, combining with dynamic stress but without underground water seepage stress. In fact, tunnel excavation forms two secondary stresses fields that can change the distribution of initial rock stress field and theunderground water seepage field. And the seepage flow of underground water also has importantinfluence on the stability of tunnel.Generally speaking, when the surface water seeps in underground, it will constitute the initial seepage flow field together with the underground water. But after tunnel excavation the initial seepage flow field will be destructed. In order to achieve a newbalance, it can produce a new seepage flow field around the tunnel with the underground water flowing into the tunnel. The pore-water pressure can change the stress field of adjacent rock mass. This problem is the coupling flow and stress question on which some scholars study now . LI et al analyzed the subsea tunnel withcoupling process and LEE and NAM discussed the seepage flow force around the tunnel with coupling analysis. In order to know the effect of underground water seepage flow on the surrounding rock deformation of tunnel, a multi-arch tunnel(named Bi-Ma-Xi tunnel) engineering was analyzed with FLAC in this work.2 Engineering and geology conditions2.1 TopographyThe tunnel locates at a hill on long-term weathering and denudation action. In the tunnel area, there are some gullies that primarily s trike towards north and some strike from east to north. Tunnel axis direction and topographic contour line are intersected with orthogonal or a great angle at section K218+087−K218+380 and with a small angle or even parallel at section K218+380− K218+565. The topography is rather steep and forms a “V” type gully. The general hill strike is about 340˚, which is close from north to south. The topography slope is about 15˚−35˚. The green vegetation is mainly the small bamboo and herbaceous plants. The rock bed is visible in some places.2.2 Lithologyccording to engineering geology survey and drilling exposure data, the stratum of3D [1−3] 4][5]surveying area from young to old is as follows.The Quaternary Holocene(Qh): the soil-like loam layer, snuff color, plastic-stiffly,0−4.60 m thick. This layer is ignored in numerical model.The Upper Cretaceous (K2j): Sandstone layer, red brown or palm fibre or dust colour,fine-grained structure. The calcareous cemented rock layer is mixed with mud cemented rock layer and the former is the main part and it is thin and medium thickness structural layer. The horizontal bedding layer develops and the dip angle is small. According to weathered degree the stratum can be divided into three layers from the top down: intensely, weakly and tinily weathered layer. The sketch map of geology section is shown in Fig.1.Fig.1 Sketch of geological profile for tunnel2.3 Geology constitutionIn tunnel area there is no large fracture structure and nor any new tectogenesis. The geology constitution is a monoclinal structure. The rock dip direction of general occurrence is 95˚−115˚. The dip angle distribution ranges from 8˚ to15˚. Three sets of joint crack develop: 1) dip direction 148˚, dip angle 89˚;2) dip direction 350˚, dip angle 56˚; 3) dip direction 225˚, dip angle 77˚. The joint cracks mostly twist with pressure and crack faces are almost close. Minorities of the crack faces are patulous and the distance between two cracks often varies from 5 to 20 cm. The connectivity is fairly good.3 Construction of 3D numerical model3.1 model of numerical calculationThis tunnel is a freeway multi-arch tunnel, of which the left one and right one are general parallel. The two tunnels are about symmetrical by the middle arch wall. The average thickness of middle wall is 2.1 m. The key dimensions of tunnel section are shown in Fig.2.Fig.2 Sketch of multi-tunnel cross section (unit: cm)When modeling the tunnel, the direction along the tunnel is y-axis and in horizontal plane the perpendicularity of tunnel direction is x-axis and plumb upward is z-axis. The influence of tunnel excavation is considered. The radius of influence range is above 3 times of one tunnel span. So in width direction, 50 m extends respectively outside the left and right tunnel, plus the span itself, width direction calculation range is 125 m. Downwards from the original point is 3 times of the height of the tunnel, which equals 45 m and upward is till the earth’s surface (does not consider the clay layer, calculating depth range includes intensely, weakly, tinily weathered red sandstone from above to below respectively). The buried depth of the tunnel is about 25 m. Plus the 10 m of its height, in z-axis the depth is 80 m. Along the tunnel direction an unit length is considered because tunnel excavation can be considered asa plane-strain problem. The size of the 3D numerical model is 125 m×80 m×1 m. The 3D numerical model and its coordinate axis location are shown in Fig.3.Fig.3 3D numerical model of tunnel in FLACThe displacement boundary conditions are adopted in numerical model. Bottom border is constrained with vertical displacement and upper border is free border. Both left and right border are restrained with horizontal displacement. The same boundary conditions are applied in both the front and back borders in y-axis.3.2 Calculation parametersThe mechanics parameters in numerical analysis are provided by geotechnical engineering investigation data and combined with the national criterion need and parameters discount request in numerical simulation. The mechanics parameters of the surrounding rock and the C25 concrete middle arch wall are listed in Table 1. The surrounding rock and the concrete intensity criteria adopted is the elastic-plastic criterion of Mohr-Coulomb. Table 2 shows the surrounding rock relevant seepage flow parameters when coupling problem is considered in numerical simulation. Table 3 lists the parameters of shot concrete(primary lining) and anchor support structure of the multi-arch tunnel. In this calculation process, the parameters of Grade IV surrounding rock supporting system are adopted. And only the affection of the anchor and shotconcrete is considered. The effect of secondary lining is not considered in numerical simulation.4 Discussion on calculation results4.1 Surrounding rock deformation characteristics without underground water seepage flowBased on the established numerical model, the process in which the underground water seepage flow function was not considered was carried on by FLAC . Fig.4 shows the vertical displacement contour-line map in this instance after multi-arch tunnel excavation. From Fig.4 it can be obviously seen that nearby the tunnel excavation region the rock deformation is relatively serious. The vault rock displacement is negative, indicating that the displacement direction is vertical downwards and subsidence occurs. But around the tunnel bottom the surrounding rock displacement is positive, indicating that the direction is vertical upwards and bulging phenomenon occurs.In the process of numerical calculation, the left and right tunnels were simulated simultaneously, namely they were excavated in the identical section plane simultaneously, that is to say, the influence of the construction order is not considered. In the computation process ofFLAC , some interesting grid points were selected to monitor their vertical displacement. The monitored grid points’ number and corresponding coordinate position are listed in Table 4.Fig.5 shows the time process curves of z-displacement (absolute value) of the monitored grid points around left tunnel vault. From Fig.5 it can be seen that the vertical displacement value(or called settlement value) of tunnel vault surrounding rock has relationship with its own position. The clos er the grid point’s position away from the tunnel excavation region, the larger the settlement value. For example, on the middle upper grid point (41 ) of left tunnel, its final calculation settlement value is 3.7 mm, and another grid poi nts’ values are getting smaller with the distance becoming longer.Fig.5 Time process curves of z-displacement of monitored grid points around le ft tunnel vault4.2 Surrounding rock deformation characteristics with underground water seepage flowThe influencing factors of surrounding rock deformation after tunnel excavation in Refs.[10−13], mainly concentrating on the grade of surrounding rock, excavating and supporting method, the neighbor construction load and the construction working procedure. Generally it almost does not consider the influence of underground water seepage flow. But in fact, the underground water existence has important influence on the surrounding rock deformation. For instance, in the excavation and tunnel engineering, the underground water seepage flow can cause quite big displacement of the soil or rock mass and even threaten the safety of engineering . In this study, some quantitative researches on the influence of surrounding rock deformation were carried out by underground water seepage flow.The stratum is fully saturated with water before tunnel is excavated. The seepage flow boundary condition includes that thepore-water pressure of the top surface is limited to zero and the two sides as well as the base boundary are water-proof boundaries . Before tunnel excavation the pore pressure of the stratum is hydro-static pressure. After tunnel excavation, around the tunnel excavation boundary is simulated by a free water seepage flow boundary where the adjacent underground water infiltrates into the excavated area. And the seepage flow field of surrounding rock has been changed with the excavation being carried on. Then the coupling analysis was executed by FLAC .Fig.6 shows the vertical displacement contour-line map after multi-arch tunnel excavation when considering the underground water seepage flow function. Obviously it can be seen that in coupling analysis the arch subsidence quantity is larger than that of not considering seepage function andthe affected region is also wider than that of the former as shown in Fig.4.Fig.6 z-displacement contour-line map of surrounding rock when considering underground water seepage flow function (unit: mm)coupling analysis, as the change of pore pressure in surrounding rock, the effective stress will be changed and it will cause the rock porosity ratio to reduce, leading to a larger arch subsidence quantity compared with that of not considering the seepage flow effect. But the vertical displacements at the bottom of the tunnel are not changed a lot. Fig.7 shows the calculated vertical displacement value for both vault’s middle position (grid point 41 and gridpoint 52 ). It can be seen that the subsidence quantity gradually increases with computation development, after finally tends to its new balance, both vault’s vertical displacement quantities finally stabilize at about 5.7 mm and the two time process curves are basically consistent.Fig.7 Curves of both vault’s node displacement vs calculation stepsFig.8 shows the time process curves of z -displacement(absolute value) of the monitored grid points around the left tunnel vault when taking the underground water seepage flow intoconsideration. Contrasting with Fig.5 it is obviously seen that the settlement value of 41 grid point is increased and reaches 5.7 mm. And to the other monitored grid points, their subsidence quantities also basically tend to 5.0 mm. The calculation subsidence quantities do not change when their relative positions changes.Fig.8 Time process curves of vault settlement when taking underground water seepage f low into consideration4.3 Comparison of deformation measurement results of surrounding rock In the process of excavating, the Bi Ma-Xi tunnel, the inspecting and consulting company of the fourth investigation and design institute of Chinese Railways Ministry monitored the surrounding rock deformation. Fig.9 shows the monitored vault settlement curves at sections K218+280 and K218+310.#Fig.9 Curves of measured value of vault settlement in process of left tunnel excavationComparing Fig.9 with Fig.5 and Fig.8, the maximal vault settlement calculation value is 3.7 mm when without considering underground water seepage flow, and when taking it into consideration the maximal calculation value is equal to 5.7 mm. And the practical monitored results reach 6.5 mm and tend to be stable after 2 months when the tunnel is excavated. The case fits very well with the coupling analysis result. The vault settlement measurement values in this multi-arch tunnel are all basically leveled off between 5.8 mm and 6.8 mm.The calculation results of coupling fluid-mechanical analysis are slightly smaller than the measured results. The reason is that the numerical calculation is thought as converged when the maximal unbalanced force in surrounding rock tends to a less value after tunnel excavation. And it does not consider the effect of actual time. The parameters in calculating unavoidably exist difference with the parameter of rock mass in reality. These reasons lead to the difference between the coupling analysis and the engineering measurement. But the results obtained in section 4.1 are less than the measuring results considering it indicates that the numerical analysis without underground water seepage flow cannot meet the need of engineering.5 Conclusions1) When underground water seepage flow function is considered in coupling fluid-mechanical analysis, the calculation vault settlements have finally achieved5.7−6.0 mm with the interaction of undergroundwater seepage flow and stress release in surrounding rock around the tunnel. The coupling calculation results are very close to the vault measurement settlement. It indicates that constructing tunnels in aquiferous stratum the underground water seepage flow effect must be considered in the design phase.2) The settlement of the surrounding rock above the tunnel has close relationship with its own position. The region near the tunnel excavation zone has the biggest rock deformation, so it should promptly complete supporting measures. When not considering the seepage flow function, the farther the region, the smaller the rock deformation; but when considering the seepage flow function, the settlement of the surrounding rock is above the tunnel and then basically tends to stable in shallower tunnel and it has obviously influence on the ground surface subsidence.地下水渗流对双连拱隧道围岩变形的影响摘要：一般来说，对于高速公路双连拱隧道，用FLAC3D计算隧道围岩变形时是没有考虑到地下水渗流影响的。
毕业设计(论文)外文资料翻译(学生用)
毕业设计外文资料翻译学院：信息科学与工程学院专业：软件工程姓名： XXXXX学号： XXXXXXXXX外文出处： Think In Java (用外文写)附件： 1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文网络编程历史上的网络编程都倾向于困难、复杂，而且极易出错。
程序员必须掌握与网络有关的大量细节，有时甚至要对硬件有深刻的认识。
一般地，我们需要理解连网协议中不同的“层”（Layer）。
而且对于每个连网库，一般都包含了数量众多的函数，分别涉及信息块的连接、打包和拆包；这些块的来回运输；以及握手等等。
这是一项令人痛苦的工作。
但是，连网本身的概念并不是很难。
我们想获得位于其他地方某台机器上的信息，并把它们移到这儿；或者相反。
这与读写文件非常相似，只是文件存在于远程机器上，而且远程机器有权决定如何处理我们请求或者发送的数据。
Java最出色的一个地方就是它的“无痛苦连网”概念。
有关连网的基层细节已被尽可能地提取出去，并隐藏在JVM以及Java的本机安装系统里进行控制。
我们使用的编程模型是一个文件的模型；事实上，网络连接（一个“套接字”）已被封装到系统对象里，所以可象对其他数据流那样采用同样的方法调用。
除此以外，在我们处理另一个连网问题——同时控制多个网络连接——的时候，Java内建的多线程机制也是十分方便的。
本章将用一系列易懂的例子解释Java的连网支持。
15.1 机器的标识当然，为了分辨来自别处的一台机器，以及为了保证自己连接的是希望的那台机器，必须有一种机制能独一无二地标识出网络内的每台机器。
早期网络只解决了如何在本地网络环境中为机器提供唯一的名字。
但Java面向的是整个因特网，这要求用一种机制对来自世界各地的机器进行标识。
为达到这个目的，我们采用了IP（互联网地址）的概念。
IP以两种形式存在着：(1) 大家最熟悉的DNS（域名服务）形式。
我自己的域名是。
所以假定我在自己的域内有一台名为Opus的计算机，它的域名就可以是。
毕设外文翻译 (英文原文+翻译)
英文翻译：PARTⅠ各种光纤接入技术Optical Fiber Technology With Various Access1 光网络主流1.1 光纤技术光纤生产技术已经成熟，现在大批量生产，广泛应用于今天的零色散波长λ0=1.3μm的单模光纤，而零色散波长λ0=1.55μm的单模光纤已开发并已进入实用阶段，这是非常小的1.55μm的波长衰减，约0.22dB/km，它更适合长距离大容量传输，是首选的长途骨干传输介质。
目前，为了适应不同的线路和局域网的发展要求，已经制定了一个非分散纤维，低色散斜率光纤，大有效面积光纤，水峰光纤等新型光纤。
长波光学研究人员研究认为，传输距离可以达到数千公里的理论，可以实现无中继传输距离，但它仍然是阶段理论。
1.2 光纤放大器1550nm波长掺铒（ER）的光纤放大器（EDFA），掺铒数字，模拟和相干光通信中继器可以以不同的速率传输光纤放大器，也可以发送特定波长的光信号。
在从模拟信号转换成数字信号、从低到高比特率比特率的光纤网络升级中，系统采用光复用技术的扩大，他们都不必改变掺铒放大器电路和设备。
掺铒放大器可作为光接收机前置放大器，后置放大器的光发射机和放大器的补偿光源装置。
1.3 宽带接入不同的环境中企业和住宅客户提供了多种宽带接入解决方案。
接入系统主要完成三大功能：高速传输，复用/路由，网络的扩展。
目前，接入系统的主流技术，ADSL 技术可以双绞铜线传输经济每秒几兆比特的信息，即支持传统的语音服务，而且还支持面向数据的因特网接入位，理事会结束的ADSL多路复用访问的数据流量，路由的分组网络，语音流量将传送到PSTN，ISDN或其它分组网络。
电缆调制解调器在HFC网络提供高速数据通信，将带宽分为上行和下行信道同轴电缆渠道，它可以提供挥发性有机化合物的在线娱乐，互联网接入等服务，同时还提供PSTN业务。
固定无线接入系统如智能天线和接收机的无线接入系统使用了许多高新技术，是一个以创新的方式接入的技术，作为目前仍滞留在今后进一步探索实践的方式最不确定的接入技术。
毕业设计外文资料翻译——翻译译文
毕业设计外文资料翻译（二）外文出处：Jules Houde 《Sustainable development slowed down by bad construction practices and natural and technological disasters》2、外文资料翻译译文混凝土结构的耐久性即使是工程师认为的最耐久和最合理的混凝土材料，在一定的条件下，混凝土也会由于开裂、钢筋锈蚀、化学侵蚀等一系列不利因素的影响而易受伤害。
近年来报道了各种关于混凝土结构耐久性不合格的例子。
尤其令人震惊的是混凝土的结构过早恶化的迹象越来越多。
每年为了维护混凝土的耐久性，其成本不断增加。
根据最近在国内和国际中的调查揭示，这些成本在八十年代间翻了一番，并将会在九十年代变成三倍。
越来越多的混凝土结构耐久性不合格的案例使从事混凝土行业的商家措手不及。
混凝土结构不仅代表了社会的巨大投资，也代表了如果耐久性问题不及时解决可能遇到的成本，更代表着，混凝土作为主要建筑材料，其耐久性问题可能导致的全球不公平竞争以及行业信誉等等问题。
因此，国际混凝土行业受到了强烈要求制定和实施合理的措施以解决当前耐久性问题的双重的挑战，即：找到有效措施来解决现有结构剩余寿命过早恶化的威胁。
纳入新的结构知识、经验和新的研究结果，以便监测结构耐久性，从而确保未来混凝土结构所需的服务性能。
所有参与规划、设计和施工过程的人，应该具有获得对可能恶化的过程和决定性影响参数的最低理解的可能性。
这种基本知识能力是要在正确的时间做出正确的决定，以确保混凝土结构耐久性要求的前提。
加固保护混凝土中的钢筋受到碱性的钝化层(pH值大于12.5)保护而阻止了锈蚀。
这种钝化层阻碍钢溶解。
因此，即使所有其它条件都满足(主要是氧气和水分)，钢筋受到锈蚀也都是不可能的。
混凝土的碳化作用或是氯离子的活动可以降低局部面积或更大面积的pH值。
当加固层的pH值低于9或是氯化物含量超过一个临界值时，钝化层和防腐保护层就会失效，钢筋受腐蚀是可能的。
毕业设计外文翻译例文
大连科技学院毕业设计(论文)外文翻译学生姓名专业班级指导教师职称所在单位教研室主任完成日期 2016年4月15日Translation EquivalenceDespite the fact that the world is becoming a global village, translation remains a major way for languages and cultures to interact and influence each other. And name translation, especially government name translation, occupies a quite significant place in international exchange.Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. While interpreting—the facilitating of oral or sign-language communication between users of different languages—antedates writing, translation began only after the appearance of written literature. There exist partial translations of the Sumerian Epic of Gilgamesh (ca. 2000 BCE) into Southwest Asian languages of the second millennium BCE. Translators always risk inappropriate spill-over of source-language idiom and usage into the target-language translation. On the other hand, spill-overs have imported useful source-language calques and loanwords that have enriched the target languages. Indeed, translators have helped substantially to shape the languages into which they have translated. Due to the demands of business documentation consequent to the Industrial Revolution that began in the mid-18th century, some translation specialties have become formalized, with dedicated schools and professional associations. Because of the laboriousness of translation, since the 1940s engineers have sought to automate translation (machine translation) or to mechanically aid the human translator (computer-assisted translation). The rise of the Internet has fostered a world-wide market for translation services and has facilitated language localizationIt is generally accepted that translation, not as a separate entity, blooms into flower under such circumstances like culture, societal functions, politics and power relations. Nowadays, the field of translation studies is immersed with abundantly diversified translation standards, with no exception that some of them are presented by renowned figures and are rather authoritative. In the translation practice, however, how should we select the so-called translation standards to serve as our guidelines in the translation process and how should we adopt the translation standards to evaluate a translation product?In the macro - context of flourish of linguistic theories, theorists in the translation circle, keep to the golden law of the principle of equivalence. The theory of Translation Equivalence is the central issue in western translation theories. And the presentation of this theory gives great impetus to the development and improvement of translation theory. It‟s not diffi cult for us to discover that it is the theory of Translation Equivalence that serves as guidelines in government name translation in China. Name translation, as defined, is the replacement of thename in the source language by an equivalent name or other words in the target language. Translating Chinese government names into English, similarly, is replacing the Chinese government name with an equivalent in English.Metaphorically speaking, translation is often described as a moving trajectory going from A to B along a path or a container to carry something across from A to B. This view is commonly held by both translation practitioners and theorists in the West. In this view, they do not expect that this trajectory or something will change its identity as it moves or as it is carried. In China, to translate is also understood by many people normally as “to translate the whole text sentence by sentence and paragraph by paragraph, without any omission, addition, or other changes. In both views, the source text and the target text must be “the same”. This helps explain the etymological source for the term “translation equivalence”. It is in essence a word which describes the relationship between the ST and the TT.Equivalence means the state or fact or property of being equivalent. It is widely used in several scientific fields such as chemistry and mathematics. Therefore, it comes to have a strong scientific meaning that is rather absolute and concise. Influenced by this, translation equivalence also comes to have an absolute denotation though it was first applied in translation study as a general word. From a linguistic point of view, it can be divided into three sub-types, i.e., formal equivalence, semantic equivalence, and pragmatic equivalence. In actual translation, it frequently happens that they cannot be obtained at the same time, thus forming a kind of relative translation equivalence in terms of quality. In terms of quantity, sometimes the ST and TT are not equivalent too. Absolute translation equivalence both in quality and quantity, even though obtainable, is limited to a few cases.The following is a brief discussion of translation equivalence study conducted by three influential western scholars, Eugene Nida, Andrew Chesterman and Peter Newmark. It‟s expected that their studies can instruct GNT study in China and provide translators with insightful methods.Nida‟s definition of translation is: “Translation consists in reproducing in the receptor language the closest natural equivalent of the source language message, first in terms of meaning and secondly in terms of style.” It i s a replacement of textual material in one language〔SL〕by equivalent textual material in another language（TL）. The translator must strive for equivalence rather than identity. In a sense, this is just another way of emphasizing the reproducing of the message rather than the conservation of the form of the utterance. The message in the receptor language should match as closely as possible the different elements in the source language to reproduce as literally and meaningfully as possible the form and content of the original. Translation equivalence is an empirical phenomenon discovered bycomparing SL and TL texts and it‟s a useful operational concept like the term “unit of translati on”.Nida argues that there are two different types of equivalence, namely formal equivalence and dynamic equivalence. Formal correspondence focuses attention on the message itself, in both form and content, whereas dynamic equivalence is based upon “the principle of equivalent effect”.Formal correspondence consists of a TL item which represents the closest equivalent of a ST word or phrase. Nida and Taber make it clear that there are not always formal equivalents between language pairs. Therefore, formal equivalents should be used wherever possible if the translation aims at achieving formal rather than dynamic equivalence. The use of formal equivalents might at times have serious implications in the TT since the translation will not be easily understood by the target readership. According to Nida and Taber, formal correspondence distorts the grammatical and stylistic patterns of the receptor language, and hence distorts the message, so as to cause the receptor to misunderstand or to labor unduly hard.Dyn amic equivalence is based on what Nida calls “the principle of equivalent effect” where the relationship between receptor and message should be substantially the same as that which existed between the original receptors and the message. The message has to be modified to the receptor‟s linguistic needs and cultural expectation and aims at complete naturalness of expression. Naturalness is a key requirement for Nida. He defines the goal of dynamic equivalence as seeking the closest natural equivalent to the SL message. This receptor-oriented approach considers adaptations of grammar, of lexicon and of cultural references to be essential in order to achieve naturalness; the TL should not show interference from the SL, and the …foreignness …of the ST setting is minimized.Nida is in favor of the application of dynamic equivalence, as a more effective translation procedure. Thus, the product of the translation process, that is the text in the TL, must have the same impact on the different readers it was addressing. Only in Nida and Taber's edition is it clearly stated that dynamic equivalence in translation is far more than mere correct communication of information.As Andrew Chesterman points out in his recent book Memes of Translation, equivalence is one of the five element of translation theory, standing shoulder to shoulder with source-target, untranslatability, free-vs-literal, All-writing-is-translating in importance. Pragmatically speaking, observed Chesterman, “the only true examples of equivalence (i.e., absolute equivalence) are those in which an ST item X is invariably translated into a given TL as Y, and vice versa. Typical examples would be words denoting numbers (with the exceptionof contexts in which they have culture-bound connotations, such as “magic” or “unlucky”), certain technical terms (oxygen, molecule) and the like. From this point of view, the only true test of equivalence would be invariable back-translation. This, of course, is unlikely to occur except in the case of a small set of lexical items, or perhaps simple isolated syntactic structure”.Peter Newmark. Departing from Nida‟s receptor-oriented line, Newmark argues that the success of equivalent effect is “illusory “and that the conflict of loyalties and the gap between emphasis on source and target language will always remain as the overriding problem in translation theory and practice. He suggests narrowing the gap by replacing the old terms with those of semantic and communicative translation. The former attempts to render, as closely as the semantic and syntactic structures of the second language allow, the exact contextual meaning of the original, while the latter “attempts to produce on its readers an effect as close as possible to that obtained on the readers of the original.” Newmark‟s description of communicative translation resembles Nida‟s dynamic equivalence in the effect it is trying to create on the TT reader, while semantic translation has similarities to Nida‟s formal equivalence.Meanwhile, Newmark points out that only by combining both semantic and communicative translation can we achieve the goal of keeping the …spirit‟ of the original. Semantic translation requires the translator retain the aesthetic value of the original, trying his best to keep the linguistic feature and characteristic style of the author. According to semantic translation, the translator should always retain the semantic and syntactic structures of the original. Deletion and abridgement lead to distortion of the author‟s intention and his writing style.翻译对等尽管全世界正在渐渐成为一个地球村，但翻译仍然是语言和和文化之间的交流互动和相互影响的主要方式之一。
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 .。
毕业设计外文资料翻译译文
附件1：外文资料翻译译文包装对食品发展的影响一个消费者对某个产品的第一印象来说包装是至关重要的，包括沟通的可取性，可接受性，健康饮食形象等。
食品能够提供广泛的产品和包装组合，传达自己加工的形象感知给消费者，例如新鲜包装/准备，冷藏，冷冻，超高温无菌，消毒（灭菌），烘干产品。
食物的最重要的质量属性之一，是它的味道，其影响人类的感官知觉，即味觉和嗅觉。
味道可以很大程度作退化的处理和/或扩展存储。
其他质量属性，也可能受到影响，包括颜色，质地和营养成分。
食品质量不仅取决于原材料，添加剂，加工和包装的方法，而且其预期的货架寿命（保质期）过程中遇到的分布和储存条件的质量。
越来越多的竞争当中，食品生产商，零售商和供应商；和质量审核供应商有显着提高食品质量以及急剧增加包装食品的选择。
这些改进也得益于严格的冷藏链中的温度控制和越来越挑剔的消费者。
保质期的一个定义是：在食品加工和包装组合下，在食品的容器和条件，在销售点分布在特定系统的时间能保持令人满意的食味品质。
保质期，可以用来作为一个新鲜的概念，促进营销的工具。
延期或保质期长的产品，还提供产品的使用时间，方便以及减少浪费食物的风险，消费者和/或零售商。
包装产品的质量和保质期的主题是在第3章中详细讨论。
包装为消费者提供有关产品的重要信息，在许多情况下，使用的包装和/或产品，包括事实信息如重量，体积，配料，制造商的细节，营养价值，烹饪和开放的指示，除了法律准则的最小尺寸的文字和数字，有定义的各类产品。
消费者寻求更详细的产品信息，同时，许多标签已经成为多语种。
标签的可读性是为视障人士的问题，这很可能成为一个对越来越多的老年人口越来越重要的问题。
食物的选择和包装创新的一个主要驱动力是为了方便消费者的需求。
这里有许多方便的现代包装所提供的属性，这些措施包括易于接入和开放，处置和处理，产品的知名度，再密封性能，微波加热性，延长保质期等。
在英国和其他发达经济体显示出生率下降和快速增长的一个相对富裕的老人人口趋势，伴随着更加苛刻的年轻消费者，他们将要求和期望改进包装的功能，如方便包揭开（百货配送研究所，IGD）。
毕设外文翻译电子版
7.1 INTRODUCTIONAfter lathes, milling machines are the most widely used for manufacturing applications. In milling, the workpiece is fed into a rotating milling cutter, which is a multi-point tool as shown in Fig. 7.1, unlike a lathe, which uses a single point cutting tool. The tool used in milling is called the milling cutter.Fig. 7.1Schematic diagram of a milling operationThe milling process is characterised by:(i)Interrupted cutting Each of the cutting edges removes materialfor only a part of the rotation of the milling cutter. As a result, the cutting edge has time to cool before it again removes material.Thus the milling operation is much more cooler compared to the turning operation. This allows for a much larger material rates.(ii)Small size of chips Though the size of the chips is small, in view of the multiple cutting edges in contact a large amount of material is removed and as a result the component is generally completed ina single pass unlike the turning process which requires a largenumber of cuts for finishing.(iii)Variation in chip thickness This contributes to the non-steady state cyclic conditions of varying cutting forces during the contact of the cutting edge with the chip thickness varying from zero to maximum size or vice versa. This cyclic variation of the force can excite any of the natural frequencies of the machine tool system and is harmful to the tool life and surface finish generatedA milling machine is one of the most versatile machine tools. It is adaptable for quantity production as well as in job shops and tool rooms. The versatility of milling is because of the large variety of accessories and tools available with milling machines. The typical tolerance expected from the process is about ±0.050 mm.7.2 TYPES OF MILLING MACHINESTo satisfy various requirements milling machines come in a number of sizes and varieties. In view of the large material removal ratesmilling machines come with a very rigid spindle and large power. The varieties of milling machines available are:(i) Knee and Column type(a) horizontal(b) vertical(c) universal(d) turret typeThese are the general purpose milling machines, which have a high degree of flexibility and are employed for all types of works including batch manufacturing. A large variety of attachments to improve the flexibility are available for this class of milling machines.(ii) Production (Bed) type(a) simplex(b) duplex(c) triplexThese machines are generally meant for regular production involving large batch sizes. The flexibility is relatively less in these machines which is suitable for productivity enhancement.(iii) Plano millersThese machines are used only for very large workpieces involving table travels in meters.(iv) Special type(a) Rotary table(b) Drum type(c) Copy milling (Die sinking machines)(d) Key way milling machines(e) Spline shaft milling machinesThese machines provide special facilities to suit specific applications that are not catered to by the other classes of milling machines.7.2.1 Knee and Column Milling MachinesThe knee(升降台) and column type is the most commonly used machine in view of its flexibility and easier setup. A typical machine construction is shown in Fig. 7.2 for the horizontal axis. The knee houses the feed mechanism and mounts the saddle and table. The table basically has the T-slots running along the X-axis for the purpose of work holding. The table moves along the X-axis on the saddle while the saddle moves along the Y-axis on the guide ways provided on the knee.The feed is provided either manually with a hand wheel or connected for automatic by the lead screw, which in turn is coupled to the main spindle drive. The knee can move up and down (Z-axis) on a dovetail provided on the column.Fig. 7.2 Horizontal knee and column type milling machineThe massive column at the back of the machine houses all the power train including the motor and the spindle gearbox. The power for feeding the table lead screw is taken from the main motor through a separate feed gearbox. Sometimes a separate feed motor is provided for the feed gearbox as well.While the longitudinal and traverse motions are provided with automatic motion, the raising of the knee is generally made manually.The spindle is located at the top end of the column. The arbour used to mount the milling cutters is mounted in the spindle and is provided with a support on the other end to take care of the heavy cutting forces by means of an overarm with bearing. As shown in Fig.7.2 the overarm extends from the column with a rigid design. The spindle nose has the standard Morse taper of the suitable sizedepending upon the machine size.The milling cutters are mounted on the arbour at any desired position, the rest of the length being filled by standard hardened collars of varying widths to fix the position of the cutter. The arbour is clamped in the spindle with the help of a draw bar and then fixed with nuts.Milling machines are generally specified on the following basis:(i) Size of the table, which specifies the actual working area on the table and relates to the maximum size of the workpiece that can be accommodated.(ii) Amount of table travel, which gives the maximum axis movement that is possible.(iii) Horse power of the spindle, which actually specifies the power of the spindle motor used. Smaller machines may come with 1 to 3 hp while the production machines may go from 10 to 50 hp.Another type of knee and column milling machine is the vertical axis type. Its construction is very similar to the horizontal axis type, except for the spindle type and location.The vertical axis milling machine is relatively more flexible (Fig. 7.4) and suitable for machining complex cavities such as die cavities in tool rooms. The vertical head is provided with a swiveling facility in horizontal direction whereby the cutter axis can be swivelled. This isuseful for tool rooms where more complex milling operations are carried out.The spindle is located in the vertical direction and is suitable for using the shank mounted milling cutters such as end mills, In view of the location of the tool, the setting up of the workpiece and observing the machining operation is more convenient.Fig, 7.3 Vertical knee and column type milling machineFig.7.4 Some of the milling operations normally carried out on vertical axis machinesThe universal machine has the table which can be swivelled in a horizontal plane at about 45o to either the left or right. This makes the universal machine suitable for milling spur and helical gears as well as worm gears and cams.7.2.2 Bed Type Milling MachineIn production milling machines it is desirable to increase the metal removal rates. If it is done on conventional machines by increasingthe depth of cut, there is possibility of chatter. Hence another varietyof milling machines named as bed type machines are used which are made more rugged and are capable of removing more material. The ruggedness is obtained as a consequence of the reduction in versatility.The table in the case of bed type machines is directly mounted on the bed and is provided with only longitudinal motion.The spindle moves along with the column to provide the cutting action. Simplex machines (Fig. 7.5) are the ones with only one spindle head while duplex machines have two spindles (Fig. 7.6). The two spindles are located on either side of a heavy workpiece and remove material from both sides simultaneously.Fig. 7.5 Simplex bed type milling machineFig. 7.6 Duplex bed type milling machine7.3 MILLING CUTTERSThere are a large variety of milling cutters available to suit specific requirements. The versatility of the milling machine is contributed toa great extent by the variety of milling cutters that are available.7.3.1 Types of Milling CuttersMilling cutters are classified into various types based on a variety of methods.(i) Based on construction:(a) Solid(b) Inserted tooth typeBased on mounting:(a) Arbor mounted(b) Shank mounted(c) Nose mountedBase on rotation:(a) Right hand rotation (counter clockwise)(b) Left hand rotation (clockwise)Based on helix:(a) Right hand helix(b) Left hand helixMilling cutters are generally made of high speed steel or cemented carbides. The cemented carbide cutters can be of a brazed tip variety or with indexable tips. The indexable variety is more common since it is normally less expensive to replace the worn out cutting edges than to regrind them.Plain milling cutters These are also called slab milling cutters and are basically cylindrical with the cutting teeth on the periphery as shown in Fig. 7.7. These are generally used for machining flat surfaces.Fig. 7.7 Arbor mounted milling cutters for general purposeLight duty slab milling cutters generally have a face width, which is small of the order of 25 mm. They generally have straight teeth and large number of teeth.Heavy duty slab milling cutters come with a smaller number of teeth to allow for more chip space. This allows taking deeper cuts and consequently high material removal rates.Helical milling cutters have a very small number of teeth but a large helix angle. This type of cutter cuts with a shearing action, which can produce a very fine finish. The large helix angle allows the cutter to absorb most of the end load and therefore the cutter enters and leaves the workpiece very smoothly.Side and face milling cutters These have the cutting edges not only onthe face like the slab milling cutters, but also on both the sides. As aresult, these cutters become more versatile since they can be used for side milling as well as for slot milling.Staggered tooth side milling cutters are a variation where the teeth are arranged in an alternate helix pattern. This type is generally used for milling deep slots, since the staggering of teeth provides for greater chip space.Another variation of the side and face cutter is the half side milling cutter, which has cutting edges only on one side. This arrangement provides a positive rake angle and is useful for machining on only one side. These have a much smoother cutting action and a long tool life. The power consumed is also less for these cutters.Fig. 7.8Special forms of arbor mounted milling cuttersSlitting saws The other common form of milling cutters in the arbor mounted category is the slitting saw. This is very similar to a saw blade inappearance as well as function. Most of these have teeth around the circumference while some have side teeth as well. The thickness of these cutters is generally very small and is used for cutting off operations or for deep slots.Special form cutters In addition to the general type of milling cutters described above, there are a large number of special form milling cutters available which are used for machining specific profiles.Angular milling cutters are made in single or double angle cutters for milling any angle such as 30, 45 or 60o Form relieved cutters are made of various shapes such as circular, corner rounding, convex or concave shapes.T-slot milling cutters are used for milling T-slots such as those in the milling machine table. The central slot is to be milled first using an end mill before using the T-slot milling cutter. Woodruff key seat milling cutters are used for milling as the name suggests, woodruff key seats Some other special form cutters are dovetail milling cutters and gear milling cutters.End mills These are shank mounted as shown in Fig. 7.9 and are generally used in vertical axis milling machines. They are used for milling slots, key ways and pockets where other type of milling cutters cannot be used. A depth of cut of almost half the diameter can be taken with the end mills.The end mills have the cutting edge running through the length of the cutting portion as well as on the face radially up to a certain length. The helix angle of the cutting edge promotes smooth and efficient cutting even at high cutting speeds and feed rates. High cutting speeds(转速?) are generally recommended for this type of milling cutters.Fig. 7.9 Shank mounted milling cutters and various types of end mills There are a large variety of end mills. One of the distinctions is based on the method of holding, i.e., the end mill shank can be straight or tapered. The straight shank is used on end mills of small size and held in the milling machine spindle with the help of a suitable collet. The tapered shank can be directly mounted in the spindle with the help of the selfholding taper. If the taper is small compared to the spindle taper, then an adopter accommodating both the tapers is used.The end teeth of the end mills may be terminated at a distance from the cutter center or may proceed till the center (Fig. 7.9 f). Those with the cutting edge up to the center are called slot drills or end cutting end mills since they have the ability to cut into the solid material (Fig. 7.9 g). The other type of end mills which have a larger number of teeth cannot cut into solid material and hence require a pilot hole drilled before a pocket is machined.The cutting edge along the side of an end mill is generally straight and sometimes can be tapered by grinding on a tool and cutter grinder such that the draft required for mould and die cavities can be automatically generated.。
1.毕设外文翻译(原版)
IEEE TRANSACTIONS ON AUTOMATIC CONTROL, VOL. AC-19, NO.
5,
OCTOBER
1974
H. P. Geering, “ O p t k l control theory for nonscalar-valued [22] L. A. Zadeh, “Optimality and non-scalar-valued performance performance criteria, Ph.D. dissertation, Dept. Elec. Eng., criteria,” I E E E Trans. Automat. Contr. (Corresp.), vol. AC-8, Mass. Inst. Technol., Cambridge, Aug. 1971 (available in the pp. 59-60, 1963. form of Microfiche Nr. AD 731213, NTIS, U. S. Dept. of Comm.). theory for H. P. Geering and M. Athans,“Optimalcontrol non-scalar-valued performance criteria,” in Proc. 5th Ann. Princeton Conf. Information Sciences and Systems, Princeton, N.J., Mar. 1971. H. Halkin, “On the necessary condition for optimal control of non-linear systems,” J . Analyse Mathhatique, vol. 12, pp. IHans P. Geering (S’7&M’71) was bornon 82, 1964. June 7, 1942. H e received the degree of H. Halkin, “Topological aspects of optimal control of dynamicalpolysystems,” Contrib. Differential Equations, vol. 3, pp. Diplomierter Elektroingenieur from the Eid377-385. 1964. genoesische Technische Hochschulein Zurich, E. B. Lee and L. Markus, Foundations of Optimal Control Switzerland, in 1966, and the M.S. and Ph.D. Theory. New York: Wiley, 1967. degrees from the Massachusetts Institute of L. W.-Neustadt, “A general theory of extremals,” J . Comput. Technology, Cambridge,in 1969 and 1971, Sci. Syst., V O ~ .3, pp. 57-92, 1969. respectively. C. Olech, “Existence theorems for optimal problems with vecIn 1967 and 1968, he worked with Sprecher tor valued cost function,” Center of Dynamical Systems, & Schuh AG in Suhr, Switzerland, and Brown University, Providence, R.I., Tech. Rep. 67-6, 1967. Oerlikon-Buehrle AG in Zurich, Switzerland, K. Ritter, “Optimization theory in linear spaces-Part I,” Math. Annul., vol. 182, pp. 189-206, 1969. From September, 1968 to August, 1971 he was a Research Assistant , “Optimization theory in linear spaces-Part 11,” Math. in the M.I.T. Electronic Systems Laboratory and a Teaching AsAnnal., vol. 183, pp. 169-180, 1969. sistant in the Department of Electrical Engineering at M.I.T. He is , “Optimization theory in linear spaces-Part 111,”Math. presently with Oerlikon-Buehrle AG. His research interests are in Annul., vol. 184, pp. 133-154, 1970. estimation and control theory. R.. T. ltockafellar, Con.vexAnalysis. Princeton, N.J.: Princeton Dr. Geel.ing is a member of Schweizerische Gesellschaft fur AutoUniv. Press, 1970. E. Tse. “On the oDtimal control of linear svstems with in- matik (IFAC) and Schweizerischer Elektrotechnischer Verein. completeinformati&,” Ph.D. dissertation, U*ep. Elec. Eng., Mass. Inst. Technol., Cambridge, Nov., 1969. [20] B. Z. Vulikh, Introduction to the Theory of Partially Ordered Spaces. Groningen, The Netherlands: Wolters-Noordhoff Sc., 1967. [21] H. S. Witsenhausen, “Minimax control of uncertain system,” Electronic Systems Lab., Mass. Inst. Technol., Cambridge, Michael Athans (S’58-M%-SM’69-F’73) for a photograph and Rep. ESGIt-269, 1966. biography see page 30 of February the issue of TRANSACTIONS. this
(完整版)_毕业设计(论文)外文翻译_(原文)
毕业设计（论文）——外文翻译（原文）NEW APPLICATION OF DATABASERelational databases in use for over two decades. A large portion of the applications of relational databases in the commercial world, supporting such tasks as transaction processing for banks and stock exchanges, sales and reservations for a variety of businesses, and inventory and payroll for almost of all companies. We study several new applications, which recent years.First. Decision-support systemAs the online availability of data , businesses to exploit the available data to make better decisions about increase sales. We can extract much information for decision support by using simple SQL queries. Recently support based on data analysis and data mining, or knowledge discovery, using data from a variety of sources.Database applications can be broadly classified into transaction processing and decision support. Transaction-processing systems are widely used today, and companies generated by these systems.The term data mining refers loosely to finding relevant information, or “discovering knowledge,” from a large volume of data. Like knowledge discovery in artificial intelligence, data mining attempts to discover statistical rules and patterns automatically from data. However, data mining differs from machine learning in that it deals with large volumes of data, stored primarily on disk.Knowledge discovered from a database can be represented by a set of rules. We can discover rules from database using one of two models:In the first model, the user is involved directly in the process of knowledge discovery.In the second model, the system is responsible for automatically discovering knowledgefrom the database, by detecting patterns and correlations in the data.Work on automatic discovery of rules influenced strongly by work in the artificial-intelligence community on machine learning. The main differences lie in the volume of data databases, and in the need to access disk. Specialized data-mining algorithms developed to which rules are discovered depends on the class of data-mining application. We illustrate rule discovery using two application classes: classification and associations.Second. Spatial and Geographic DatabasesSpatial databases store information related to spatial locations, and provide support for efficient querying and indexing based on spatial locations. Two types of spatial databases are particularly important:Design databases, or computer-aided-design (CAD) databases, are spatial databases used to store design information about databases are integrated-circuit and electronic-device layouts.Geographic databases are spatial databases used to store geographic information, such as maps. Geographic databases are often called geographic information systems.Geographic data are spatial in nature, but differ from design data in certain ways. Maps and satellite images are typical examples of geographic data. Maps may provide not only location information -such as boundaries, rivers and roads---but also much more detailed information associated with locations, such as elevation, soil type, land usage, and annual rainfall.Geographic data can be categorized into two types: raster data (such data consist a bit maps or pixel maps, in two or more dimensions.), vector data (vector data are constructed from basic geographic objects). Map data are often represented in vector format.Third. Multimedia DatabasesRecently, there much interest in databases that store multimedia data, such as images, audio, and video. Today multimedia data typically are stored outside the database, in files systems. When the number of multimedia objects is relatively small, features provided by databases are usually not important. Database functionality becomes important when the number of multimedia objects stored is large. Issues such as transactional updates, querying facilities, and indexing then become important. Multimedia objects often they were created, who created them, and to what category they belong. One approach to building a database for such multimedia objects is to use database for storing the descriptive attributes, and for keeping track of the files in which the multimedia objects are stored.However, storing multimedia outside the database makes it the basis of actual multimedia data content. It can also lead to inconsistencies, such a file that is noted in the database, but whose contents are missing, or vice versa. It is therefore desirable to store the data themselves in the database.Forth. Mobility and Personal DatabasesLarge-scale commercial databases stored in central computing facilities. In the case of distributed database applications, there strong central database and network administration. Two technology trends which this assumption of central control and administration is not entirely correct:1.The increasingly widespread use of personal computers, and, more important, of laptop or “notebook” computers.2.The development of a relatively low-cost wireless digital communication infrastructure, base on wireless local-area networks, cellular digital packet networks, and other technologies.Wireless computing creates a situation where machines no longer at which to materialize the result of a query. In some cases, the location of the user is a parameter of the query. A example is a traveler’s information system that provides data on the current route must be processed based on knowledge of the user’s location, direction of motion, and speed.Energy (battery power) is a scarce resource for mobile computers. This limitation influences many aspects of system design. Among the more interesting consequences of the need for energy efficiency is the use of scheduled data broadcasts to reduce the need for mobile system to transmit queries. Increasingly amounts of data may reside on machines administered by users, rather than by database administrators. Furthermore, these machines may, at times, be disconnected from the network.SummaryDecision-support systems are gaining importance, as companies realize the value of the on-line data collected by their on-line transaction-processing systems. Proposed extensions to SQL, such as the cube operation, of summary data. Data mining seeks to discover knowledge automatically, in the form of statistical rules and patterns from large databases. Data visualization systems data as well as geographic data. Design data are stored primarily as vector data; geographic data consist of a combination of vector and raster data.Multimedia databases are growing in importance. Issues such as similarity-based retrieval and delivery of data at guaranteed rates are topics of current research.Mobile computing systems , leading to interest in database systems that can run on such systems. Query processing in such systems may involve lookups on server database.毕业设计（论文）——外文翻译（译文）数据库的新应用我们使用关系数据库已经有20多年了，关系数据库应用中有很大一部分都用于商业领域支持诸如银行和证券交易所的事务处理、各种业务的销售和预约，以及几乎所有公司都需要的财产目录和工资单管理。
毕业设计外文翻译原文
Int J Adv Manuf Technol (2014) 72:277–288DOI 10.1007/s00170-014-5664-3Workpiece roundness profile in the frequency domain: an application in cylindrical plunge grindingAndre D. L. Batako & Siew Y. GohReceived: 21 August 2013 / Accepted: 21 January 2014 / Published online: 14 February 2014# Springer-Verlag London 2014Abstract In grinding, most control strategies are based on the spindle power measurement, but recently, acoustic emission has been widely used for wheel wear and gap elimination. This paper explores a potential use of acoustic emission (AE) to detect workpiece lobes. This was achieved by sectioning and analysing the AE signal in the frequency domain. For the first time, the profile of the ground workpiece was predicted mathematically using key frequencies extracted from the AE signals. The results were validated against actual workpiece profile measurements. The relative shift of the wave formed on the surface of the part was expressed using the wheel- workpiece frequency ratio. A comparative study showed that the workpiece roundness profile could be monitored in the frequency domain using the AE signal during grinding. Keywords Plunge grinding . Roundness . Waviness . Frequency . Acoustic emission1IntroductionGrinding is mostly used as the last stage of a manufacturing process for fine finishing. However, recently, high efficiency deep grinding (HEDG) was introduced as a process that achieves high material removal rates exceeding 1,100 mm3/ mm/s [1–5]. Grinding is mainly used to achieve high dimen- sional and geometrical accuracy. However, in cylindrical plunge grinding, vibration is a key problem in keeping tight tolerances and form accuracy (roundness) of ground parts.Machine tools are designed and installed to have minimum vibration (with anti-vibration pad when required). Neverthe- less, in grinding, the interaction between the wheel and the workpiece generates persistent vibration. This leads to varia- tion of the forces acting in the contact zone, which in turn causes a variation in the depth of cut on the ground workpiece. Consequently, this creates waviness on the circumference of the workpiece. The engendered uneven profile on the work- piece surface leads to a modulation of the grinding conditions of the following successive rotations; this is called workpiece regenerative effect. The building up of this effect can take place in grinding cycles with longer duration. Similar effects occur on the grinding wheel surface; however, the process of the build up is slow [6–9].It is generally difficult to get a grinding wheel perfectly balanced manually, which is acceptable for general purpose grinding. For precision grinding, automatic dynamic wheel balancing devices are used. Though current grinding ma- chines have automatic balancing systems to reduce the out- of-balance of grinding wheels, in actual grinding, forced vi- bration is still caused by the dynamically unbalanced grinding wheels [10]. This is because any eccentricity in the rotating grinding wheel generates a vibratory motion.The stiffness of the wheel spindle and the tailstock also affects the wheel-workpiece-tailstock subsystem, which oscil- lates due to the interaction of the wheel with the workpiece. In practice, the generated force vibration is hard to eliminate completely. This type of vibration has greater influence on the formation of the workpiece profile. During the grinding process, the out-of-balance of the wheel behaves as a sinusoi- dal waveform that is i mprinted on t he workpiece s urface. T his, as in a previous case, leads to the variation of depth of cut andA.D.L.Ba t ako(*):S.Y.GohAMTReL, The General Engineering Research Institute, Liverpool John Moores University (LJMU), Byrom Street, Liverpool L3 3AF, UKe-mail: a.d.batako@ creates low-frequency lobes around the workpiece, and this is the key target of the study presented here.Other factors such as grinding parameters have to be taken into consideration in the study of grinding vibration becausethese aspects affect the stability of the process. This is because the resulting workpiece profile is the combined effect of different type of vibration in grinding [7, 11]. The studies carried out by Inasaki, Tonou and Yonetsu showed that the grinding parameters have a strong influence on the amplitude and growth rate of the workpiece and wheel regenerative vibration [12].The actual measurement of the workpiece profile is an integral part of the manufacturing process due to the uncertain-ty in wheel wear and the complexity of the grinding process. Contactless measurement and contact stylus systems were developed to record the variations of the workpiece size and roundness. However, these techniques can be used as post-process checking as it is limited to a particular set-up and must be used without the disturbance of the cutting fluid in a clean air-conditioned environment with stable t emperature [13–16].In the industry, random samples from batches are usually inspected after the grinding process. Any rejection of parts or sometimes batches increases the manufacturing time and cost. Therefore, it becomes important to develop online monitoring systems to cut down inspection time and to minimise rejected parts in grinding. Some of the existing monitoring systems in grinding are based on the wheel spindle power. However, sen-sors such as acoustic emission and accelerometers are also used to gather information of the grinding process for different appli-cation. Dornfeld has given a comprehensive view of the appli-cation of acoustic emission (AE) sensors in manufacturing [17]. Most reported applications of AE in grinding are for gap elim-ination, touch dressing and thermal burn detection [18–21].In cylindrical grinding processes, the generated chatter vibration causes the loss of form and dimensional accuracy of ground workpieces. The effect of vibration induces the formation of lobes on the workpiece surface, which are usu- ally detected using roundness measurement equipment. High- precision parts with tight tolerance are increasingly in demand and short cycle times put pressure on manufacturing process- es. This leads to the need for developing in-process roundness monitoring systems for cylindrical grinding processes.The potential of using acoustic emission to detect the formation of lobes on a workpiece during a cylindrical plunge grinding process is investigated in this work. The aim is to extract the workpiece roundness profile from the acoustic emission signal in the frequency domain. The extracted fre- quencies are compared with actual measurement in frequency domain, i.e. harmonic components. T he key frequencies o f the harmonic content are used to predict the expected profile on the ground p art.2The study of acoustic emission plunge grindingAE is an elastic wave that is generated when the workpiece is under the loading action of the cutting grits due to the interfacial and internal frictional and structural modification. The wave generated is transmitted from the contact zone through the components of the machine structure [22, 23]. In grinding processes, the main source of the AE signal is the mechanical stress applied by the wheel on the workpiece in the grinding zone [24]. The chipping action of the abrasive grits on the workpiece surface generates a multitude of acous- tic waves, which are transmitted to the sensor through the centres and the tailstock of machine. The machining condition is reflected in the signal through the magnitude of the acoustic emission, which varies with the intensity of the cutting, e.g. rough, medium or fine grinding. The key information of the machining process and its condition is buried in the AE signal. To extract any information of interest from the AE signals, it is important to identify the frequency bandwidth and study the signal in details.Susic and Grabec showed that intensive changes of AE signal relate to the grinding condition, thus the ground surface roughness could be estimated based on the measured signal with a profile correlation function [25]. A strong chatter vibration in grinding is also reflected in the recorded RMS AE signal. As vibration could generate the waviness on the workpiece, hence, the AE signal was also used to study the roundness profile [26]. A comprehensive study of the chatter vibration, wheel surface and workpiece quality in cylindrical plunge grinding based on the AE signal was carried out recently [27].In roundness measurement systems, the roundness of the part is also given as harmonic components. Generally, the frequency span given by the measurement machine is of low frequency—500 Hz and below. This is because the roundness profile deals with the waviness but not with the surface roughness that is always of higher frequency. Fricker [8] and Li and Shin [28] also indicated parts profile of frequency below 300 Hz. Part roundness profile is expressed in undula- tion per revolution. Therefore, lower frequency components are mainly targeted by t he measurement equipment, b ut higher frequency components tends to ride on top of lower carriers. In most cases, the provided frequency profile is in the range of 300 Hz [8, 28]. Therefore, this work studies the AE signal along the grinding process using the fast Fourier transform (FFT) with a particular focus on frequencies below 300 Hz. This allowed for a direct comparison between the results from this investigation and the actual roundness measurements.Figure 1 illustrates the equipment used in this study, where (a) is the configuration of the grinding machine with the location of the sensors and (b) is the roundness measurement machine. To improve signal transmission, the coating of the tailstock was removed from the location of the sensors as shown in this figure.During this study, observations of the shape of the recorded AE and the signal of spindle power indicated that there are three main phases in a typical cylindrical plunge grindingFig. 1 Experimental equipment: a grinding machine and sensors config- uration, b Talyrond 210 roundness measurement systemcycle, i.e. before grinding, actual grinding and dwell. In this work, the words ―dwell‖and ―dwelling‖are used to describe the ―spark out‖phase where the infeed stops and the grinding wheel enters a dwelling stage. For short notation, ―dwell‖is used in most figures.First phase (before grinding): at the beginning of the process, the grinding wheel approaches the workpiece in a fast infeed without any physical contact between the wheel and the workpiece.Second phase (actual grinding): when the grinding wheel gets very close to the workpiece, the rapid feed changes to the programmed infeed value then the grinding wheel gradually gets into contact with the workpiece. The phase starts with the first contact of the wheel with the part and runs until the targeted diameter is reached.Third phase (dwell or spark out): when the target diam- eter is reached, the infeed stops and the wheel stays in contact with the part. The duration of the dwelling pro- cess varies depending on the grinding conditions and is intended to remove the leftover material on the part due to mechanical and thermal deflection and to reduce the outof roundness. The grinding wheel retracts from the work- piece at the end of the programmed spark out (dwell).In this study, the power and AE signals were recorded simultaneously; however, the acceleration of the tailstock was also recorded for further investigation. The recorded signals are illustrated in Fig. 2 with a delimitation of the three phases.In addition, the actual grinding phase was subdivided to introduce the notion of ―grinding-in‖, ―steady grinding‖and ―pre-dwell‖ as depicted in Fig. 3. The steady grinding ends with a pre-dwell period. There is a transition state between the grinding in and the steady grinding states; this is where the cutting process starts entering the steady state. This is illus- trated by an ellipse in Fig. 2. During the grinding-in, the depth of cut increases from zero to a constant value per revolution, then the steady-state grinding runs under a constant depth of cut. The pre-dwell section is not an obvious technological phase, rather it is a tool used in this study.To aid the signal processing techniques, especially the fast Fourier transform and Yule Walker methods, a referenced sampling was introduced using an RPM pickup (see work- piece rotation in Fig. 3). Recording the workpiece rotation simultaneously with the AE signal helped portioning the signal to reduce processing time and to study time-varying process in the grinding.3Simulation and modellingWorkpiece responseIn this investigation, it was necessary to filter out from the recorded signals the frequencies of other parts of the grinding machine, especially the natural frequency of the workpiece. Fig. 2 Recorded power and acoustic emission signals with process phasesφ ¼ δ.2π.βð2ÞConsequently, the dynamics of the waviness Ω formed with time t at the surface of the part can be expressed as follows: Ω ¼ sin ðωt þ φÞð3ÞTherefore, the equation of the wave generated by the wheel at the surface of the workpiece was derived as follows:. Ω ¼ sin ωt þ 2πδ.βð4Þ3.3 Simulation of the workpiece profileFig. 3 Typical AE signal for one full grinding cycle with RPM outputTherefore, the workpiece response was studied using finite element analysis (FEA) and an experimental impact test to identify its natural frequency. The result of this study is depicted in Fig. 4, where it is seen that the natural frequency of the workpiece is 1,252 Hz. The outputs of the impact test and the FEA are in good agreement and show that the natural frequency of the workpiece is over 1 kHz; consequently, it will not appear in the range of low frequencies of interest.Process modellingDesignating the wheel rotational frequency by fs and the workpiece rotational frequency by fw , the ratio of these two entities was expressed as follows: β ¼ f s = f wð1ÞThe notion of frequency ratio (β) helps understanding the generation of the workpiece profile as it relates key process During the roundness measurement process, the machine uses a single trace of the stylus on the workpiece circumference to generate the profile of the workpiece. Here, the stylus is in direct contact with the measured part.However, in this study, an attempt is made for the first time to predict the final workpiece profile using process signatures extracted from the recorded signals. The link between the prediction model and the grinding process is the sensor, which collects the signal from the entire process. Therefore, the model predicts an average workpiece profile in contrary to measuring machine which gives only a single trace on the part. The procedure of capturing and extracting process sig- nature is schematically illustrated in Fig. 5.The procedure works as follows: throughout the grinding process, the acoustic emission, vibration and RPM sensor record the signals. The signals are processed using various techniques (e.g. FFT) to obtain the system response in the frequency domain. The model extracts process-inherent key dominant frequencies, and uses these frequencies and their respective amplitudes to generate the expected profile of the workpiece.The following expression in Eq. (5) is used to predict the final profile of the ground part. parameters and defines the fundamental harmonic, which naffects the part profile. In this study, it was found that the wheel-workpiece frequency ratio has a direct effect on the ∏ ¼ X i ¼1 ½αi cos ð2π t f i Þ] þ rand ðt Þ ð5Þ workpiece roundness as it constitutes the fundamental har- monic for this specific machining configuration.During the grinding process, there is a relative lag between the grinding wheel and the workpiece due to the difference in their rotational frequencies. This difference (δ) is numerically equal to the decimal part of the frequency ratio. This causes the currently forming wave to creep, with reference to the wave formed in the previous revolution of the part. By ex- pressing the wheel angular speed as ω, and the decimal part of the frequency ratio in Eq. 1 as δ, the relative shift φ of the wave on the workpiece surface was defined as follows: Where f i is the i th dominant frequency with an amplitude ofαi , and t is the time. rand (t ) is the added random noise to incorporate the randomness of grits cutting actions.4 Experimental workIn this investigation, the response of the machine tool was studied at different stages, namely idle, running by switching its components one by one and recording the signal from oneFig. 4 Workpiece response: a experiment and b FEAsingle location, and finally in operation conditions while grinding. This allowed identifying and discriminating fre- quency components belonging to the machine tools structure and those frequencies induced by noise and interference from nearby operating machineries.An analogue to digital (A/D) converter (NI 6110) was used to record the analogue signals from the power of the motor, the acceleration and the acoustic emission sensors through the tailstock. This A/D device had four channels with a sampling rate up to 5 MS/s per channel, providing a total sampling rate of 20 MS/s. This device allowed for a simultaneous four-channel sampling of analogue inputs voltage in the range of ±5 mV to42 V. The LabView software was used to control the data acquisition process during the experiments. To iden- tify the most suitable sampling, the signals were recorded at various sampling rates. The recorded signal was proc- essed using MATLAB.Sets of workpiece batches were ground using rough, medium and fine infeed. The grinding wheel speed was 35 m/s, and the workpiece was rotating at 100 rpm. In this experiment, a dwell or spark out of 10 s was applied to all grinding cycles. In total, 220 μm of material was removed from each part.The ground parts were allowed to settle down for 24 h at 19±1 °C in a temperature controlled room before the measure- ments were taken. The roundness profile of the ground parts were measured using a Talyrond 210 illustrated in Fig. 1. AFig. 5 Modelling pseudo- algorithmtypical measured workpiece roundness is illustrated in Fig. 6, where (a) is the roundness profile and (b) is the corresponding linear profile obtained by dissecting the round profile and expanding it in a line.5ResultsIn this work, various signal processing techniques were used to study the recorded signals as described above. In order to extract t he i nformation o f t he workpiece r oundness p rofile, t he acoustic emission signal was scrutinised using the above- mentioned partitioning technique. Each portion of the signal was analysed using the FFT and Yule Walker (YW) methods. However, short-time Fourier transform (STFT) and the continuous wavelet transform (CWT) were able to handle full grinding cycle signals.Figures 7 and 8 illustrate a typical power spectrum using the STFT and CWT of a full grinding cycle. Similar outputs were obtained with the FFT and YW methods; however, these last two methods required signal partitioning due to the com- putational window s ize.Figure 8 illustrates the three phases of a grinding cycle, where the frequency spectrum is given with time span along the grinding cycle. It is seen in this picture as in Fig. 7 that process-inherent f requencies a ppeared o nly d uring t he ―actual grinding‖ phase and partially in the ―dwell or spark out‖ period. Comparing STFT and CWT, it is observed that the STFT (Fig. 7) provided an aggregate frequency spectrum, when the CWT resolved each individual frequency (Fig. 8). This improved resolution allows identifying the birth of lobesFig. 6 Typical workpiece roundness measurement using Talyrond 210: a roundness profile, b corresponding linear profilein time within the grinding cycle. It opens an opportunity in studying the workpiece profile in the frequency domain. It is seen in both figures that the parasitic 50 Hz can be well discriminated f rom t he p rocess f requency. V arious f requencies up to 500 Hz that characterise the workpiece prolife are picked up in the actual grinding phase. Frequencies that dominate the spectrum towards the end of the actual grinding will poten- tially form and reside on the final part profile.Figure 9 presents the results of AE, where the sectioned signal was analysed in the frequency domain using FFT toextract the frequencies of interest. This picture displays a waterfall plot of the frequency spectrum in each phase of the grinding cycle. This study focused on the detection of process - inherent frequencies, with less attention to the actual value of the magnitude as it is subject of another investigation. It is observed in the ―before grinding ‖ section of the signal that nothing happens in the frequency domain; hence, no frequen- cy peaks were detected. In the ―grinding -in ‖ section, once the wheel hits the workpiece, several frequency peaks appear in the signal, characterising special events in the grindingFig. 7 Full grinding cycle AE signal frequency spectrum using STFTFig. 8 Full grinding cycle AE signal frequency spectrum using CWTFig. 9 Waterfall plot offrequency spectrum of a full grinding cycleprocess. The amplitudes of these frequencies increase as the process evolves into ―actual grinding ‖ due to the cutting intensity and diminish towards the end of the grinding cycle (spark out ). In this figure, the transition between the grinding phases can be observed from the variations in the frequencies and their amplitudes along the progression of the process. During the actual grinding, due to the generated vibration and the increase of the material removal, high peaks were detected. Less frequency components and small amplitude in the dwell period is due to reduced grains activities because there is no actual infeed of the wheel and the workpiece enters a relaxation stage while the wheel removes only leftover material c aused b y wheel/workpiece d eflection. Comparing the detected frequencies in the AE signal with the off-line measurement, it was identified that there is a factor of 0.6 between the two set of results in this particular test. This factor varies depending on machining configuration. Using this factor, all the detected harmonics from the frequency analysis were correlated to those from roundness measure- ment. Figure 12 gives a sample of comparative results for fine infeed grinding, showing the detected frequencies and their corresponding measured harmonics.For example, multiplying the frequency 54 in Fig. 10 (fre- quency analysis) by this factor (0.6) provides the value 32.4 (33), which is the harmonic detected by the measurement machine in Fig. 11. It is seen that the major lobes (33) formedFig. 10 Frequency content of the signal in dwell phase (fine infeed))Fig. 11 Harmonic profile from the actual measurement (fine infeed)Fig. 12 Extracted harmonics and measured values (fine infeed)on the ground workpiece in Fig. 12 as well as the other components, i.e. 48, 82, 115 and 148, were clearly detected in the AE signal as 78, 136,190 and 248 Hz.It is worth mentioning that the actual magnitude of the power spectrum of detected frequencies is not in the scope of the work presented here. This is because this work focused on the detection of process-inherent frequencies in order to develop a control strategy to improve the round- ness of the part. The control strategy and the actual magni- tude are considered in the next phase, where the system will be calibrated.The study of the frequencies in fine infeed showed that during the dwelling period (spark out), the amplitude of the detected harmonics decreases drastically. It is observed that in spark out (dwell), the amplitude of 243 Hz which was dom- inating throughout the cycle dropped and led to 54 Hz to become the dominate in the last phase in Fig. 10. This section carries important information of the final workpiece profile. The number of lobes formed on the workpiece is now defined as a product of the extracted frequencies with the defined factor. This holds true for any frequency detected and for given machining parameters configuration. The factor of 0.6 given here is adequate for this specific experimental set up used in these particular tests. However, it was identified that this factor varies as a function of process settings. The origin of this factor was identified but not stated here, as it is commercially viable for the companies pursuing further de- velopment of this work.This study confirmed that the final profile of the work- piece is the result of overlapping waves of different fre- quencies as an additive process. This is schematically illus- trated in Fig. 13. In addition, these waves have a relative translation with reference to each other due to a shifting effect caused by the relative creep of the grinding wheel with reference to the rotating workpiece as described in Eqs. (2–4). It is worthwhile stating that this work does not study the roughness which is characterised by high frequen- cy; however, it focused on the formation of lobes which are of lower frequency.This is evidenced in Fig. 14 for rough infeed grinding, where the AE signal was analysed per workpiece revo- lution in the actual steady -state grinding. This figureFig. 13 Additive effect of key harmonics forming a profile on a workpieceFig. 14 Process frequency content in steady-state grinding with rough infeedshows how different frequencies appear or disappear from revolution to revolution due to the shifting and overlapping effect. Also, the amplitude of these frequen- cies varies along the process. However, in fine infeed, it was observed that the process is dominated by two high peaks of 54 and 243 Hz (second and ninth harmonic in Fig. 12), which appeared throughout the full grinding cycle.Using the wave additive property and applying Eq. (5) allowed predicting the expected workpiece profile using the information extracted from the signal in the frequency domain. One of the examples is shown in Fig. 15 in a form of linear profile, which is obtained by dissecting the circu- lar profile and extending it along a line of 360°. The measurement machine chooses an arbitrary point and dis- sects the profile. Here, Fig. 15a is a linear roundness profile of the workpiece obtained from the actual round- ness measurement system, and Fig. 15b is the predicted (simulated) workpiece profile using the frequency compo- nents extracted from the AE signal. The point where the measuring machine cuts the profile and sets the origin of the axis 0.0°is unknown to the machine operator; there- fore, the results in Fig. 15a are shifted relative to Fig. 15b by an unknown value. However, there is a good agreement between these two profiles in terms of the surface undula- tion per revolution. This prediction will be used in the control strategy to improve the part profile well before the process enters the spark out phase.a)Simulate signal54321 0 -1-2-3-4 050 100 150200 250 300 350DegreeFig. 15 Linear workpiece profile: (a) actual measurement; (b) predicted (simulated ) profile6 DiscussionThe results show that the detected major dominant frequency in the AE signal is of importance because it indicates the number of major lobes formed on the workpiece. The other frequency components represent the small peaks on the work- piece surface. Actual workpiece measurements supported this finding. The extracted information of workpiece profile using the techniques presented here provides the room for the de- velopment of a control strategy to improve the workpiece roundness.This study showed that the formation of the workpiece profile is a function of the process parameters where the wheel and the workpiece play the key role. This is because at high rotating speeds, a slight unbalance of the wheel leads to high eccentric force, hence uneven stock removal. This is magni- fied by the effect of regular or irregular imprints on the workpiece surface. The shifting of the wheel relative to the workpiece leads to the generation of various waves on the workpiece. It was observed in fine infeed that the machining conditions are relatively stable; therefore, there were no drastic changes in the AE signal in terms of frequencies and amplitudes. However, in rough infeed with increased depth of cut and longer contact length, there is a tendency to have vibrations at high amplitude. This leads to radical changes in the cutting intensity at a regular pattern and at the pace of the fundamental frequency. An example is observed in Fig. 14 where certain frequencies appear constantly in the last three rotations (see sixth, seventh and eight rotations). If there is no shift between successive rotations, the matching of dominant frequenciesmay cause a beating effect as the wheel and the workpiece would make their contacts at the same points. Consequently, the formed lobes would become more apparent around the workpiece. An example of the beating effect is seen in the AE signal in Fig. 3 where the amplitude of the signal is modulated.Low infeed rate has a small depth of cut, short contact length and provides an increased number of lobes. However, the opposite is true in high infeed rate, where a small number of lobes is generated with higher amplitude. The higher the number of lobes, the smaller the interval between the lobes and the smoother is the profile formed. Thus, the workpiece produced using the rough infeed has higher peak with lower number of lobes, while with the fine infeed, the number of lobes is higher and the peaks are of small heights.7 Conclusions This paper provides some key relations between the process and the acoustic sounds emitted during machining. Process- inherent frequencies were successfully extracted from the AE signal and compared with the information of the measured workpiece profile. The obtained results were verified using data from the actual roundness measurement. A range of grinding parameters was covered and the outcomes correlated well with the measurements. A fundamental frequency ratio was established. A mathematical expression was derived to predict the expected profile of the machined part. The rela- tionship between the frequencies buried in the AE and those A m p l i t u d eb)。
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基于LabVIEW的变速箱故障诊断系统
摘要
这篇论文主要介绍了变速箱的实施过程和设计原理的故障诊断系统，利用虚拟仪器发展中的software-LabVIEW来实现系统的核心设计，通过小波变换和神经网络，通过例子最终验证了该系统的可行性。
1.介绍
作为一个复杂的齿轮机械系统，变速箱有许多特征参数----固定驱动比，大的驱动力矩和紧凑结构。
因此，它通常用来改变转速和转换功率。
与此同时，它是一个容易流失的组件，在过去，Matlab软件编程是为了诊断这样的设备的错误，来分析和处理故障诊断信号，其中的错误位置和故障类型是人工判断的。
这种方法会给变速箱的故障诊断带来人为因素。
这种方法带有局限性，它不容易识别或者是搞清变速箱的故障。
随着计算机技术和机器故障诊断技术的发展，我们提出了一种新思路---基于计算机智能检测的变速箱故障诊断系统，为了提高变速箱故障诊断测量的准确度，快速性，便捷性，和可靠性。
该系统利用小波变换从振动信号中提取参数特点，利用神经网络来得出结论。
这也同时凸显出原检验方法的弱点，分类智能化变速箱的诊断失误。
本文将简要介绍LabVIEW软件尤其是介绍LabVIEW软件的主要问题和情景结构，该系统发展并实现了基于计算机智能检验的变速箱故障诊断系统。
2.总结虚拟仪器的软件开发
虚拟仪器LabVIEW（实验室）是一种发展工程工作台的工作包，虚拟仪器是一种基于G程序（图形语言）由NI（国家仪器公司）一家美国公司提供的。
关于LabVIEW的虚拟仪器的设计能逃避LabVIEW环境。
LabVIEW能够模仿传统仪器上的控制面板，并给出了显示结果，同时还可以以各种形式的计算机显示器显示。
它拥有强大功能的计算器，可以实现信号数据的操作，分析和处理。
此外，它可以完成收集、测量和调节信号I/O接口，从而完成各种测试功能。
在世界上，LabVIEW产品广泛应用与众多领域，例如航空、航天、
通信、汽车半导体和生物医学科学等。
作为一个虚拟仪器，LabVIEW在为工程师们执行自己的思想方面更具有优势,使非专业的程序员更加方便，使得程序与传统的编程工具相比更具可读性，如C、c++、VC + +、VB等。
同时,它具有较强的可扩展性和适应性。
所以在这里我们采用了图形语言LabVIEW来对整个过程的故障进行诊断。
与此同时，LabVIEW通过BP神经网络在转化的振动信号的小波变换和分类信号特性方面更具创造性。
更重要的是,它为故障诊断变速箱提供了一种全新的设计手段。
3.基于LabVIEW变速箱DIAGNOISIS的系统故障
A.变速箱故障诊断系统的结构与构成
变速箱故障诊断系统采用微量和数字传输序列的框架结构来完成故障诊断，包括训练部分和审查部分。
图1显示的是框架体系。
训练部分
审查部分
图1 系统的框架体系
在训练部分中,首先,变速箱中典型的故障信号的输入到系统，然后在LabVIEW中选择合适的小波变换基础,利用小波工具来分析信号,一些频率的特征参数被挑出并且加以规范化后，将会通过全局变量被输入到LabVIEW中的BP训练网络,最后一致的重量和阈值获得和诊断网络结构经训练BP神经网络后得加以确定。
在审查部分，采集到的故障信号通过A/D转换输入到计算机。
利用小波理论的LabVIEW工具提取的特征参数，为了要得到变速箱的故障类型，，归一化的结果将会被输入到已训练的BP神经网络加以识别和诊断变速箱的故障。
B.主要技术问题的实现和它们的设置
从图１中显示的系统框架来看，有一些技术问题。
如下所示：
1)从故障信号提取和归一化的特征参数。
2)从神经网络提取的重量。
3)固定网络的故障诊断。
上述问题涉及LabVIEW 的多种风格，接下来，我们来具体描述它们的设置：
1) 小波变换和规范化过程
该系统通过Lab 使用的小波工具,来实现小波变换,提取特征参数信号。
前面板和程序框图中可以在图2中看到。
该系统对故障信号用小波的工具包分解到N 层，获得一组低频信号与N 组高频信号然后获得高频系数权重的高频信号
12{,,,}n d d d Λ。
假定E.j 是jth 层高频系数串行d.j 的能量，这里
21n
j i i E X ==∑
其中n 是d.j 权重的数量。
全层高频系数的能量可以通过以上的计算得到。
经过归一化后全层高频系数的能量，形成的向量是我们所需要的特征参数。
图2 小波变换的前面板和系统框图
2) BP 神经网络的训练
利用在LabVIEW 中的阵列控制器与神经网络算法,该系统可以实现BP 神经网络的训练,获得对故障诊断的权重。
图3为显示面板。
本系统采用三层BP 神经网络规范。
输入层N 的数目是小波分析层的数目输出层M 的数目是齿轮箱故障类型的数目。
隐藏层H 的数量是无限的；它是由输入层和输出层的数目决定的。
我们经验公式得到方程
H l =+。
l 是一个范围为１-10的整数。
输入层、输出层和隐藏层的代码号分别是7、10、4。
图3 训练网络的前面板
BP 神经网络的典型的故障识别训练有素的。
系统的输入向量为变速器的
故障信号的特征矢量。
输出向量是齿轮箱故障类型。
根据BP算法,系统利用实验样品、增益权重和阈值，从输入层、隐藏层和隐藏层到输出层训练网络,来满足整个网络的误差要求。
曲线可以显示不同的变化的趋势。
图4 BP神经网络的程序框架
3)BP神经网络的应用
BP神经网络的应用是选择后的网络的故障识别。
它是由LabVIEW算法实现的。
运用增重到网络以识别信号，得到故障类型。
这个程序框架显示在图4中。
此部分为实现变速箱故障诊断的重要过程。
它实时读取特征参数，并利用用于实时训练的BP神经网络识别，获取最后的故障类型。
这是BP网络的一个标准的动态计算过程。
4.变速箱故障诊断的实例
在实例中,小波变换选择小波DB2作为基本小波，它在第七层。
小波变换DB2是一种正交的变换。
有几个故障类型，如齿轮断裂、点蚀、磨损与崩溃。
首先我们固定输入层，输出层和隐藏层的数目分别为7、10、4，假设故障是侵蚀的,利用这个系统完成振动信号采集，然后提取信号的特征参数，最后通过训练BP神经网络得出结论。
图5显示了这个系统前面板的结论区。
图5 前面板的结论区
通过结论部分的主要界面，我们可以看到齿轮断裂、腐蚀、磨损、碰撞和错误的结论的坐标数据点。
结论是按照预测进行的，所以它演示了该系统的可行性和有效性。
5.结论
该系统基于LabVIEW，利用小波变换融合算法提取振动信号的特征参数。
然后它用神经网络来判断，并得出结论。
整个诊断系统应用了信号小波变换，BP神经网络与数据采集，数据辨识、贮存等,实现实时数据采集和故障类型的识别。
本系统的优点:
从信号处理方面来看，它完成信号特征参数的提取，并使用先进的方法来保证系统的精密、便利和信誉。
从系统的总体结构来看，它利用LabVIEW来产生系统，使得软件变成硬件替代。
这里是一个突破。
这样一来，它提高了结构的安全性和可靠性。
进而，在应用和扩展时将更加方便。
该系统的应用将会为复杂仪器提供一个新的故障诊断技术路径，并且为将来的发展将创下一个新的空间。