控制工程外文文献翻译
控制电路设计毕业论文中英文对照资料外文翻译文献
中英文对照资料外文翻译文献外文文献:Designing Stable Control LoopsThe objective of this topic is to provide the designer with a practical review of loop compensation techniques applied to switching power supply feedback control. A top-down system approach is taken starting with basic feedback control concepts and leading to step-by-step design procedures, initially applied to a simple buck regulator and then expanded to other topologies and control algorithms. Sample designs are demonstrated with Math cad simulations to illustrate gain and phase margins and their impact on performance analysis.I. I NTRODUCTIONInsuring stability of a proposed power supply solution is often one of the more challenging aspects of the design process. Nothing is more disconcerting than to have your lovingly crafted breadboard break into wild oscillations just as its being demonstrated to the boss or customer, but insuring against this unfortunate event takes some analysis which many designers view as formidable. Paths taken by design engineers often emphasize either cut-and-try empirical testing in the laboratory or computer simulations looking for numerical solutions based on complex mathematical models. While both of these approach a basic understanding of feedback theory will usually allow the definition of an acceptable compensation network with a minimum of computational effort.II. S TABILITY D EFINEDFig. 1. Definition of stabilityFig. 1 gives a quick illustration of at least one definition of stability. In its simplest terms, a system is stable if, when subjected to a perturbation from some source, its response to that perturbation eventually dies out. Note that in any practical system, instability cannot result in a completely unbounded response as the system will either reach a saturation level –or fail. Oscillation in a switching regulator can, at most, vary the duty cycle between zero and 100% and while that may not prevent failure, it wills ultimate limit the response of an unstable system. Another way of visualizing stability is shown in Fig. 2. While this graphically illustrates the concept of system stability, it also points out that we must make a further distinction between large-signal and small-signal stability. While small-signal stability is an important and necessary criterion, a system could satisfy thisrt quirement and yet still become unstable with a large-signal perturbation. It is important that designers remember that all the gain and phase calculations we might perform are only to insure small-signal stability. These calculations are based upon – and only applicable to – linear systems, and a switching regulator is – by definition –a non-linear system. We solve this conundrum by performing our analysis using small-signal perturbations around a large-signal operating point, a distinction which will be further clarified in our design procedure discussion。
机电专业中英文文献翻译-控制技术
Control Technology1.Introduction to Control EngineeringWhenever energy is to be used purposefully, some form of control is necessary, in recent times there has been a considerable advance made in the art of automatic control. The art is, however, quite old, stemming back to about 1790 when James Watt invented the centrifugal governor to control the speed of his steam engines. He found that while in many applications an engine speed independent of load was removed the speed increased.In a simple centrifugal governor system, variations in engine speed are detected and used to control the pressure of the steam entering the engine. Under steady conditions the moment of the weight of the metal spheres balances that due to the centrifugal force and the steam valve opening is just sufficient to maintain the engine speed at the required level. When an extra load torque is applied to the engine, its speed will tend to fall, the centrifugal force will decrease and the metal spheres will tend to fall slightly. Their height controls the opening of the steam valve which now opens further to allow a greater steam pressure on the engine. The speed thus tends to rise, counteracting the original tendency for the speed to fall. If the extra load is removed, the reverse process takes place, the metal spheres tend to rise slightly, so tending to close the steam valve and counteracting any tendency for the speed to rise.It is obviously that without the governor the speed would fall considerably on land. However, in a correctly designed system with a governor the fall in speed would be very much less. An undesirable feature which accompanies a system which has been designed to be very sensitive to speed changes is the tendency to “hunt” or oscillate about the final speed. The real problem in the synthesis of all systems of this type is to prevent excessive oscillation but at the same time produce good “regulation”. Regulation is defined as the percentage change in controlled quantity on load relative to the value of the controlled under condition of zero load. Regulators form an important class of control system, their object generally being to keep some physical quantity constant (e.g. speed, voltage, liquid level, humidity, etc.) regardless of load variation. A good regulator has only very small regulation.The automatic control of various large-scale industrial processes, as encountered in the manufacture and treatment of chemicals, food and metals, has emerge duringthe last thirty years as an extremely important part of the general field of control engineering. In the initial stages of development it was scarcely realized that the theory of process control was intimately related to the theory of servomechanisms and regulators. Even nowadays complete academic design of process control systems is virtually impossible owing to our poor understanding of the dynamics of processes. In much of the theory introduced in this book, servomechanisms and regulators are used as example to illustrate the methods of analysis. These methods are, however, often applicable to process control systems, which will be themselves introduced separately.2. Programmable ControllersIn the 1960s, electromechanical devices were the order of the day as far as far as control was concerned. These devices, commonly known as relays, were being used by the thousands to control many sequential-type manufacturing processes and stand-alone machines. Many of these relays were in use in the transportation industry, more specifically, the automotive industry. These relays used hundreds of wires and their interconnections to affect a control solution. The performance of a relay panels called for 300 to 500 or more relays, and the reliability and maintenance issues associated with supporting these panels became a very great challenge. Cost became another issue, for in spite of the low cost of the relay itself, the installed cost of the panel could be quite high. The total cost including purchased parts, wiring, and installation labor, could range from $30~$50 per relay. To make matters worse, the constantly changing needs of a process called for recurring modifications of a control panel. With relays, this was a costly prospect, as it was accomplished by a major rewiring effort on the panel. In addition, these changes were sometimes poorly documented, causing a second-shift maintenance nightmare months later. In light of this, it was not uncommon to discard an entire control panel in favor of a new one with the appropriate components wired in a manner suited for the new process. Add to this the unpredictable, and potentially high, cost of maintaining these systems as on high-volume motor vehicle production lines, and it became clear that something was needed to improve the control process-to make it more reliable, easier to troubleshoot, and more adaptable to changing control needs.That something, in the late 1960s, was the first programmable controller. This first “revolutionary” system was developed as a specific response to the needs of the major automotive manufacturers in the United States. These early controllers, or Programmable Logic Controllers(PLC), represented the first systems that (1)could beused on the factory floor, (2)could have there “logic” change without extensive rewiring or component changes, and(3)were easy to diagnose and repair when problems occurred. It is interesting to observe the progress that has been made in the past 15 years in the programmable controller area. The pioneer products of the late 1960s must have been confusing and frightening to a great number of people. For example, what happened to the hardwired and electromechanical devices that maintenance personnel were used to repairing with hand tools? They were replaced with “computers” disguised as electronics designed t o replace relays. Even the programming tools were designed to appear as relay equivalent presentations. We have the opportunity now to examine the promise, in retrospect, what the programmable controller brought manufacturing?Figure 10.1All programmable controllers consist of the basic functional blocks shown in Figure 10.1. We will examine each block to understand the relationship to the control system. First we looked at the center, as it is the heart of the system. It consists of a microprocessor, logic memory for the storage of the actual control logic, storage or variable memory for use with data that will ordinarily change as a function of the control program execution, and a power supply to provide electrical power for the processor and memory. Next comes the I/O block. This function takes the control level signals for the CPU and converts them to voltage and current levels suitable for connection with factory grade sensors and actuators. The I/O type can range from digital, analog, or a va riety of special purpose “smart” I/O which are dedicated to a certain application task. The programmer is normally used only to initially configure and program a system and is not required for the system to operate. It is also used in troubleshooting a system, and can prove to be a valuable tool in pinpointing the exactcause of a problem. The field devices shown here represent the various sensors and actuators connected to the I/O. These are the arms, legs, eyes, and ears of the system, including pushbuttons, limit switches, proximity switches, photo sensors, thermocouples, position sensing devices, and bar code reader as input; and pilot light, display devices, motor starters, DC and AC drivers, solenoids, and printers as outputs.控制技术1.控制工程绪论只要有目的地利用能量,都有必要采取某种控制形式。
控制工程外文文献翻译
外文文献翻译20106995 工机2班吴一凡注:节选自Neural Network Introduction神经网络介绍,绪论。
HistoryThe history of artificial neural networks is filled with colorful, creative individuals from many different fields, many of whom struggled for decades to develop concepts that we now take for granted. This history has been documented by various authors. One particularly interesting book is Neurocomputing: Foundations of Research by John Anderson and Edward Rosenfeld. They have collected and edited a set of some 43 papers of special historical interest. Each paper is preceded by an introduction that puts the paper in historical perspective.Histories of some of the main neural network contributors are included at the beginning of various chapters throughout this text and will not be repeated here. However, it seems appropriate to give a brief overview, a sample of the major developments.At least two ingredients are necessary for the advancement of a technology: concept and implementation. First, one must have a concept, a way of thinking about a topic, some view of it that gives clarity not there before. This may involve a simple idea, or it may be more specific and include a mathematical description. To illustrate this point, consider the history of the heart. It was thought to be, at various times, the center of the soul or a source of heat. In the 17th century medical practitioners finally began to view the heart as a pump, and they designed experiments to study its pumping action. These experiments revolutionized our view of the circulatory system. Without the pump concept, an understanding of the heart was out of grasp.Concepts and their accompanying mathematics are not sufficient for a technology to mature unless there is some way to implement the system. For instance, the mathematics necessary for the reconstruction of images from computer-aided topography (CAT) scans was known many years before the availability of high-speed computers and efficient algorithms finally made it practical to implement a useful CAT system.The history of neural networks has progressed through both conceptual innovations and implementation developments. These advancements, however, seem to have occurred in fits and starts rather than by steady evolution.Some of the background work for the field of neural networks occurred in the late 19th and early 20th centuries. This consisted primarily of interdisciplinary work in physics, psychology and neurophysiology by such scientists as Hermann von Helmholtz, Ernst Much and Ivan Pavlov. This early work emphasized general theories of learning, vision, conditioning, etc.,and did not include specific mathematical models of neuron operation.The modern view of neural networks began in the 1940s with the work of Warren McCulloch and Walter Pitts [McPi43], who showed that networks of artificial neurons could, in principle, compute any arithmetic or logical function. Their work is often acknowledged as the origin of theneural network field.McCulloch and Pitts were followed by Donald Hebb [Hebb49], who proposed that classical conditioning (as discovered by Pavlov) is present because of the properties of individual neurons. He proposed a mechanism for learning in biological neurons.The first practical application of artificial neural networks came in the late 1950s, with the invention of the perception network and associated learning rule by Frank Rosenblatt [Rose58]. Rosenblatt and his colleagues built a perception network and demonstrated its ability to perform pattern recognition. This early success generated a great deal of interest in neural network research. Unfortunately, it was later shown that the basic perception network could solve only a limited class of problems. (See Chapter 4 for more on Rosenblatt and the perception learning rule.)At about the same time, Bernard Widrow and Ted Hoff [WiHo60] introduced a new learning algorithm and used it to train adaptive linear neural networks, which were similar in structure and capability to Rosenblatt’s perception. The Widrow Hoff learning rule is still in use today. (See Chapter 10 for more on Widrow-Hoff learning.) Unfortunately, both Rosenblatt's and Widrow's networks suffered from the same inherent limitations, which were widely publicized in a book by Marvin Minsky and Seymour Papert [MiPa69]. Rosenblatt and Widrow wereaware of these limitations and proposed new networks that would overcome them. However, they were not able to successfully modify their learning algorithms to train the more complex networks.Many people, influenced by Minsky and Papert, believed that further research on neural networks was a dead end. This, combined with the fact that there were no powerful digital computers on which to experiment,caused many researchers to leave the field. For a decade neural network research was largely suspended. Some important work, however, did continue during the 1970s. In 1972 Teuvo Kohonen [Koho72] and James Anderson [Ande72] independently and separately developed new neural networks that could act as memories. Stephen Grossberg [Gros76] was also very active during this period in the investigation of self-organizing networks.Interest in neural networks had faltered during the late 1960s because of the lack of new ideas and powerful computers with which to experiment. During the 1980s both of these impediments were overcome, and researchin neural networks increased dramatically. New personal computers and workstations, which rapidly grew in capability, became widely available. In addition, important new concepts were introduced.Two new concepts were most responsible for the rebirth of neural net works. The first was the use of statistical mechanics to explain the operation of a certain class of recurrent network, which could be used as an associative memory. This was described in a seminal paper by physicist John Hopfield [Hopf82].The second key development of the 1980s was the backpropagation algo rithm for training multilayer perceptron networks, which was discovered independently by several different researchers. The most influential publication of the backpropagation algorithm was by David Rumelhart and James McClelland [RuMc86]. This algorithm was the answer to the criticisms Minsky and Papert had made in the 1960s. (See Chapters 11 and 12 for a development of the backpropagation algorithm.)These new developments reinvigorated the field of neural networks. In the last ten years, thousands of papers have been written, and neural networks have found manyapplications. The field is buzzing with new theoretical and practical work. As noted below, it is not clear where all of this will lead US.The brief historical account given above is not intended to identify all of the major contributors, but is simply to give the reader some feel for how knowledge in the neural network field has progressed. As one might note, the progress has not always been "slow but sure." There have been periods of dramatic progress and periods when relatively little has been accomplished.Many of the advances in neural networks have had to do with new concepts, such as innovative architectures and training. Just as important has been the availability of powerful new computers on which to test these new concepts.Well, so much for the history of neural networks to this date. The real question is, "What will happen in the next ten to twenty years?" Will neural networks take a permanent place as a mathematical/engineering tool, or will they fade away as have so many promising technologies? At present, the answer seems to be that neural networks will not only have their day but will have a permanent place, not as a solution to every problem, but as a tool to be used in appropriate situations. In addition, remember that we still know very little about how the brain works. The most important advances in neural networks almost certainly lie in the future.Although it is difficult to predict the future success of neural networks, the large number and wide variety of applications of this new technology are very encouraging. The next section describes some of these applications.ApplicationsA recent newspaper article described the use of neural networks in literature research by Aston University. It stated that "the network can be taught to recognize individual writing styles, and the researchers used it to compare works attributed to Shakespeare and his contemporaries." A popular science television program recently documented the use of neural networks by an Italian research institute to test the purity of olive oil. These examples are indicative of the broad range of applications that can be found for neural networks. The applications are expanding because neural networks are good at solving problems, not just in engineering, science and mathematics, but m medicine, business, finance and literature as well. Their application to a wide variety ofproblems in many fields makes them very attractive. Also, faster computers and faster algorithms have made it possible to use neural networks to solve complex industrial problems that formerly required too much computation.The following note and Table of Neural Network Applications are reproduced here from the Neural Network Toolbox for MATLAB with the permission of the Math Works, Inc.The 1988 DARPA Neural Network Study [DARP88] lists various neural network applications, beginning with the adaptive channel equalizer in about 1984. This device, which is an outstanding commercial success, is a single-neuron network used in long distance telephone systems to stabilize voice signals. The DARPA report goes on to list other commercial applications, including a small word recognizer, a process monitor, a sonar classifier and a risk analysis system.Neural networks have been applied in many fields since the DARPA report was written. A list of some applications mentioned in the literature follows.AerospaceHigh performance aircraft autopilots, flight path simulations, aircraft control systems, autopilot enhancements, aircraft component simulations, aircraft component fault detectorsAutomotiveAutomobile automatic guidance systems, warranty activity analyzersBankingCheck and other document readers, credit application evaluatorsDefenseWeapon steering, target tracking, object discrimination, facial recognition, new kinds of sensors, sonar, radar and image signal processing including data compression, feature extraction and noise suppression, signal/image identificationElectronicsCode sequence prediction, integrated circuit chip layout, process control, chip failure analysis, machine vision, voice synthesis, nonlinear modelingEntertainmentAnimation, special effects, market forecastingFinancialReal estate appraisal, loan advisor, mortgage screening, corporate bond rating, credit line use analysis, portfolio trading program, corporate financial analysis, currency price predictionInsurancePolicy application evaluation, product optimizationManufacturingManufacturing process control, product design and analysis, process and machine diagnosis, real-time particle identification, visual quality inspection systems, beer testing, welding quality analysis, paper quality prediction, computer chip quality analysis, analysis of grinding operations, chemical product design analysis, machine maintenance analysis, project bidding, planning and management, dynamic modeling of chemical process systemsMedicalBreast cancer cell analysis, EEG and ECG analysis, prosthesis design, optimization of transplant times, hospital expense reduction, hospital quality improvement, emergency room test advisement0il and GasExplorationRoboticsTrajectory control, forklift robot, manipulator controllers, vision systemsSpeechSpeech recognition, speech compression, vowel classification, text to speech synthesisSecuritiesMarket analysis, automatic bond rating, stock trading advisory systemsTelecommunicationsImage and data compression, automated information services,real-time translation of spoken language, customer payment processing systemsTrans portationTruck brake diagnosis systems, vehicle scheduling, routing systemsConclusionThe number of neural network applications, the money that has been invested in neural network software and hardware, and the depth and breadth of interest in these devices have been growing rapidly.翻译:在人工神经网络的发展历程中,涌现了许多在不同领域中富有创造性的传奇人物,他们艰苦奋斗几十年,提出了许多至今仍然让我们受益的概念。
控制工程学中英对照论文
控制工程基础论文英中对照翻译专业:机电一体化二班学号:20087687姓名:罗庚Machinery control applications in the modern textile industrySome years, as people more conscious of the aesthetic and living standards, high-grade yarn-dyed products are increasingly popular. Not real silk, chemical fiber, rayon, cotton yarn, also can be blended and Silk weaving, dyeing bobbins which led the industry in the yarn is widely available. General yarn before dyeing tube blanks need to be purchased to suit the yarn package dyeing contact with the "pine-style cheese" for the next procedure to use, so slack increasing demand for precision windingExisting domestic slack winding machine structure is generally focused on single-spindle drive mode, usually including winding, yarn, over-feed, such as several sports, the use of mechanical gears and cam completion, for a variety of yarns of different winding process, equipment is more difficult to adjust; yarn organizations to adopt a grooved drum and rotary wing, for some high-end yarn is easy to produce injury; the same time as the structure is used in mechanical transmission, winding speed is not high. This pine-style winding currently abroad has been completely based on electronic gear and all digital electronic cam winding structure, namely, the independent single spindle drive; winding, traversing yarn guide, yarn over-feed, tension compensation are used separate motor control the movement of the relationship between the motor can be described by parameter setting, flexible response to various characteristics of the yarn winding process needs; traversing yarn guide used the "yarn guide", commonly known as "rabbit head" , damage to the yarn is very small, especially for high-grade yarn-dyed yarn winding; In addition, as the motor drive there is no direct mechanical connection, combined with high-speed precision motion control software algorithms, can easily achieve high precision cross-winding, winding speed of winding is much larger than mechanical slack, greatly improving the efficiency of the windingBeijing and Li Technology Co., Ltd. through the motor and domestic well-known textile machinery group co slack for precision winding process characteristics, in their many years of accumulation of the servo and motion control technology, based on the successful development of the country for the first time round with their own Intellectual property rights of high-speed precision slack winding electrical control program. The scheme has good performance and low cost, greatly enhancing the domestic slack winder automation level, the major technical indicators have reached the level of similar foreign equipment.System control program profilesSingle-spindle control, for example, a system control program shown in Figure principle, traverse the motor shaft connected to a wire wheel, wire wheel through the positive and negative spin-driven fastening the wire yarn guide and move around, to achieve cross-yarn Fixed cable movement; winding yarn tube direct-drive rotary motor, to achieve the yarn winding movement, the horizontal motion and the synthesis of the two movements after winding yarn showed the shape of a spiral wire wound on bobbins surface back and forth . Tension compensation and over-feed motor is mainly used to control the motor in the process of yarn winding tension.The yarn guide traverse the program uses a motor through the unique design of the ultra-small inertia servo motor, motor winding, and over-feed is also used in custom designed high-speed brushless DC motor, the tension motor uses a common step motor. Figure in the "single-spindle control driver" is and the benefits of the motor development in its own all-digital AC servo drive, based on the embedded high-speed electronic yarn winder precision motion control algorithms, winding brushless motors speed control and special yarn tension control strategy based motor drive control system. The whole system is simple, functional and communication through the adjustment of the keyboard or the "single-spindle control driver" parameter can be easily set up the internal memory of yarn winding forming the geometric parameters (full tube diameter, to close edge amplitude, etc.), winding the line speed , the winding ratio, traverse the length of yarn, hard-edged trim tube differential amplitude, differential cycle, the cam curve of the differential parameters, along with RS232, RS485, CAN bus communication interface of three, can easily complete networked multi-spindle control, the full realization of flexible digital winding. The main technical parameters are listed below:Than the control winding 2.000 ~ 12.000;Traverse to the acceleration of the servo motor for up to 8000r/s2, reciprocating frequency of the maximum is 800 beats / minute, 160 per minute 0 commutation;Traverse servo motor function with dynamic range automatically give change, no external zero position sensor;Embedded winding and compensation for the three over-feed and tension motor control, can drive, brushless DC motor driver, stepper motor driver interface, easy to realize the winding motor, over-feed motor and motor control tension compensation ;Embedded winding and compensation for the three over-feed and tension motor control, can drive, brushless DC motor driver, stepper motor driver interface, easy to realize the winding motor, over-feed motor and motor control tension compensation ;Calibration function with an empty tube diameter;A variety of real-time parameter display, such as the actual line speed, yarn diameter cylinder, reciprocating frequency;Multiple fault protection measures, such as abnormal parameters, motorspeed, dynamic range tolerance, hardware fault, etc.;Operating parameters in real time with power-down protection functions, such as the length of winding, winding diameter;Introduction to traverse servo motor controTo ensure the bobbins with good dyeing properties, need to start winding to the full tube diameter between any point on the yarn on the cheese into the interchange in space, not parallel to each other to ensure that each yarn is no overlap That is the need for winding bobbins for precise control over. The so-called winding ratio, is the yarn guide traverse back and forth each time, the number of laps winding bobbins. The traditional cross-grooved drum winding winding (any winding), a constant winding ratio of precision winding, three forms of NC layer winding, the program mainly to achieve a constant winding ratio, and numerical precision cross-winding layer Winding two functionsIn order to achieve precision cross-winding, "Control of single spindle drive " real-time collection through the winding motor feedback encoder pulse signal calculation of real-time speed, precision winding process according to the requirements come with a unique numerical algorithm traverse servo motor speed reference Instructions to ensure the traverse servo motor speed and the winding ratio of the motor speed according to the definition of the winding to maintain a certain relationship, so that the yarn helix shape of space around the bobbins on the back and forth. Winding through the precise control over, winding the yarn back and forth to each other cross, do not overlap, that clever use of electronic gear and electronics to replace mechanical cam and cam gear to achieve precision yarn winding tubeIn addition to differential electronic cam algorithm to eliminate hard-edged technology, the program has achieved full of original yarn guide for minimum arc length control algorithm to take full advantage of the high-speed DSP digital signal processor computing power, real-time calculation and correction Yarn guide traverse servo motor and the motor drive winding bobbins cam curve law, ensure that in any winding speed and winding diameter state, the yarn guide to the arc length for the minimum, maximum cylinder to eliminate winding yarn Hard-edged phenomenon.Introduction to the winding wire speed controlT heoretically, the line speed winding bobbins with yarn winding tube radius changes, and changes in velocity fluctuations directly caused by the winding tension, which will affect the yarn quality and yarn tube forming the mechanicaland physical properties . If the outer yarn yarn tension greater than the inner tension, it is easy to produce cheese yarn extrusion outer edge of the inner bulge phenomenon of yarn; if the yarn tension during the change is too large, may easily lead to a result of winding yarn Stretch yarn tension there different rates in different, which requires the winding process to minimize tension and pressure fluctuations. Therefore, apart from ensuring a constant pressure on bobbins to ensure the relative stability of the control of winding speed is an important measure tension fluctuationAbout Tension ControlProcessing precision winding yarn tension directly affects the size of the tightness of winding bobbin, thus affecting the capacity of cheese around the yarn and the difficulty of dyeing and processing of yarn breakage rate, so all kinds of precision winding winding machines are part of the yarn tension control, especially for the yarn package dyeing process with tension, not be too big to get the slack drum, is conducive to staining. In addition to taking measures to ensure the program is relatively constant yarn winding speed, but also another design of a tension adjustment device decreases, the use of a stepper motor control of the tension lever. Online Speed up Process, by adjusting the stepper motor rotation status, control the angle of the tension lever to change the yarn strength by holding the door of the gate in order to ensure constant tension winding; Also in accordance with the special bobbins "in tight outside Song, "the process requirements, the radius can be adjusted according to yarn winding tension rod tube angle, to ensure thatsmall-diameter tube when winding yarn winding tension, winding tension and large diameterPrecision winding, yarn, textile machinery textile process to improve the quality of key equipment, high-speed precision digital winding program successfully mastered the high-speed precision yarn winding process in the "KNOW HOW", all with permanent magnet motor drive technology, machine energy consumption is far lower than the conventional variable frequency motor drive equipment. At the same time the flexible use of digital control technology, is ideal for high-grade fabric in many varieties, small batch production of bobbins, with good social and economic benefits. And facilitate the development of the motor technology company involved in the innovative electronic control solutions, digital servo motor and drive, precision motion control, and computer network communication technology, is a typical high-tech mechanical and electrical integration of control programs is to use digital control a typical case of the transformation of traditional industries机械控制在现代纺织工业的应用些年,随着人们审美意识增强和生活水平的提高,高档色织产品愈加受到人们喜爱。
过程装备与控制工程外文文献翻译
Principles of Mass Transfer1. General RemarksSome of the most typical chemical engineering problems lie in the field of mass transfer. A distinguishing mark of the chemical engineer is his ability to design and operate equipment in which reactants are prepared, chemical reactions take place, and separations of the resulting products are made. This ability rests largely on a proficiency in the science of mass transfer.Applications of the principles of momentum and heat transfer are common in many branches of engineering, but the application of mass transfer has traditionally been largely limited to chemical engineering. Other important applications occur in metallurgical processes, in problems of high-speed flight, and in waste treatment and pollution-control processes.By mass transfer is meant the tendency of a component in a mixture to travel from a region of high concentration to one of low concentration. For example, if an open test tube with some water in the bottom is placed in a room in which the air is relatively dry, water vapor will diffuse out through the column of air in the test tube. There is a mass transfer of water from a place where its concentration is high (just above the liquid surface) to a place where its concentration is low (at the outlet of the tube). If the gas mixture in the tube is stagnant, the transfer occurs by molecular diffusion. If there is a bulk mixing of the layers of gas in the tube by mechanical stirring or because of a density gradient, mass transfer occurs primarily by the mechanism of forced or natural convection. These mechanisms are analogous to the transfer of heat by conduction and by convection; there is, however, no counterpart in mass transfer for thermal radiation.The analogy between momentum and energy transfer has already been studied in some detail, and it is now possible to extend the analogy to include mass transfer.In discussing the fundamentals of mass transfer we shall consider mainly binary mixtures, although multicomponent mixtures are important in industrial applications. Some of these more complicated situations will be discussed after the basic principles have been illustrated in terms of binary mixtures,2. Molecular DiffusionMolecular diffusion occurs in a gas as a result of the random motion of the molecules. This motion is sometimes referred to as a random walk. Across a plane normal to the direction of the concentration gradient (or any other plane), there are fluxes of molecules in both directions. The direction of movement for any one molecule is independent of the concentration in dilute solutions. Consequently, in a system in which there is a concentration gradient, the fraction of molecules of a particular species (referred to as species A) which will move across a plane normal to the gradient is the same for both the high-and low-concentration sides of the plane. Because the total number of molecules of A on the high-concentration side is greater than on the low-concentration side, there is therefore a net movement of A in the direction in which the concentration of A is lower. If there are no counteracting effects, the concentrations throughout the mixture tend to become the same. In the analogous transfer of heat in a gas by conduction, the distribution of hotter molecules (those which have a higher degree of random molecular motion) tends to be evened out by random mixing on a molecular scale. Similarly, if there is a gradient of directed velocity (as distinguished from random velocity) across the plane, the velocity distribution tends toward uniformity as a result of the random molecular mixing. There is a transfer of momentum, which is proportional to the viscosity of the gas.The above remarks apply only in an approximate and qualitative way. The quantitative prediction of the diffusivity, thermal conductivity, and viscosity of a gas from a knowledge of molecular properties can be quite complicated. The consideration of such relations forms an important part of the subject of statistical mechanics.Molecular diffusion also occurs in liquids and solids. Crystals in an unsaturated solution dissolve, with subsequent diffusion away from the solid-liquid interface. Diffusion in solids is of importance in metallurgical operations. When iron which is unsaturated with respect to carbon is heated in a bed of coke, the concentration of the carbon near the surface is increased by inward diffusion of carbon atoms.3. E ddy DiffusionJust as momentum and energy can be transferred by the motion of finite parcels of fluid, so mass can be transferred. We have seen that the rate of these transfer operations, caused by bulk mixing in a fluid, can be expressed in terms of the eddy kinematics viscosity, the eddy thermal diffusivity, and the eddy diffusivity. This latter quantity can be related to a mixing length which is the same as that defined in connection with momentum and energy transfer. In fact, the analogy between heat and mass transfer is so straightforward that equations developed for the former are often found to apply to the latter by a mere change in the meaning of the symbols.Eddy diffusion is apparent in the dissipation of smoke from a smokestack. Turbulence causes mixing and transfer of the smoke to the surrounding atmosphere. In certain locations where atmospheric turbulence is lacking, smoke originating at the surface of the earth is dissipated largely by molecular diffusion. This causes serious pollution problems because mass is transferred less rapidly by molecular diffusion than by eddy diffusion.4. C onvective Mass-Transfer CoefficientsIn the study of heat transfer we found that the solution of the differential energy balance was sometimes cumbersome or impossible, and it was convenient to express the rate of heat flow in terms of a convective heat-transfer coefficient by an equation like)(m s t t h Aq -= The analogous situation in mass transfer is handled by an equation of form)(Am As P A k N ρρ-=The mass flux NA is measured relative to a set of axes fixed in space. The driving force is the difference between the concentration at the phase boundary (a solid surface or a fluid interface) and the concentration at some arbitrarily defined point in the fluid medium. The convective coefficient kp may apply to forced or natural convection; there are no mass-transfer counterparts for boiling, condensation, or radiation heat-transfer coefficients. The value of kp is a function of the geometry of the system and the velocity and properties of the fluid, just as was the coefficient h.(Selected from* C. O. Bennett, and J. E. Myens, Momentum, Heat, and Mass Transfer, 2nd Edition, McGraw-Hill Inc. , 1974. )传质原理1. 概述一些典型的化学工程问题存在于传质领域。
材料成型及控制工程外文翻译文献
材料成型及控制工程外文翻译文献(文档含英文原文和中文翻译)在模拟人体体液中磷酸钙涂层激光消融L. Cle`ries*, J.M. FernaHndez-Pradas, J.L. Morenza德国巴塞罗那大学,西班牙1999年七月二十八日-2000年2月文摘:三种类型的磷酸钙涂层基质,在钛合金激光烧蚀技术规定提存,沉浸在一个模拟的身体# uid为了确定条件下他们的行为类似于人的血浆。
羟基磷灰石涂层也也非晶态磷酸钙涂层和a-tricalcium磷酸盐做溶解阶段b-tricalcium磷酸盐的涂料有细微的一个阶段稍微瓦解。
一个apatitic阶段降水量偏爱在羟基磷灰石涂层的涂料磷酸b-tricalcium上有细微的一个阶段。
在钛合金基体上也有降水参考,但在大感应时代。
然而,在非晶态磷酸钙涂层不沉淀形成。
科学出版社有限公司(2000保留所有权利。
关键词:磷酸钙,脉冲激光沉积,SBF1 介绍激光消融技术用于沉积磷酸钙涂层金属基体上,将用作植体骨重建。
用这个技术,磷酸钙涂层量身定做阶段和结构也成功地研制生产了[1,2]和溶解特性鉴定海洋条件]。
然而,真正的身体条件# uid饱和对羟基磷灰石的阶段,这是钙离子的浓度高于均衡的这个阶段。
因而,这就很有趣也测试条件磷酸钙涂料接近体内的情况,以了解其完整性,在这些条件及其催化反应性质}表面沉淀过程。
因此,非晶态磷酸钙涂层(ACP),羟基磷灰石(HA)涂层,涂层中的一个阶段b-tricalcium磷酸盐较小(ba-TCP)积下激光烧蚀是沉浸在饱和溶液为迪!时间、不同的结构性演变进行了测定。
饱和溶液的使用的是身体uid(SBF模拟#),解决了其离子浓度、酸碱度几乎等于那些人类血浆[5]。
该解决方案也是一个利用在仿生(沉淀)工艺生产磷灰石层在溶胶凝胶活性钛基体。
2 实验模拟身体化学溶解试剂级严格依照以下的顺序,除氢钠,NaHCO3:)3,K2HPO4 H2O,MgCl2)6 H2O,氯化钙和Na2SO4)2 H2O,在去离子水。
过程装备与控制工程专业U形管换热器毕业论文外文文献翻译及原文
毕业设计(论文)外文文献翻译文献、资料中文题目:U形管换热器文献、资料英文题目:文献、资料来源:文献、资料发表(出版)日期:院(部):专业:过程装备与控制工程专业班级:姓名:学号:指导教师:翻译日期: 2017.02.14毕业设计(论文)外文翻译毕业设计(论文)题目: U形管式换热器设计外文题目: U-tube heat exchangers译文题目:指导教师评阅意见U-tube heat exchangersM. Spiga and G. Spiga, Bologna1 Summary:Some analytical solutions are provided to predict the steady temperature distributions of both fluids in U-tube heat exchangers. The energy equations are solved assuming that the fluids remain unmixed and single-phased. The analytical predictions are compared with the design data and the numerical results concerning the heat exchanger of a spent nuclear fuel pool plant, assuming distinctly full mixing and no mixing conditions for the secondary fluid (shell side). The investigation is carried out by studying the influence of all the usual dimensionless parameters (flow capacitance ratio, heat transfer resistance ratio and number of transfer units), to get an immediate and significant insight into the thermal behaviour of the heat Exchanger.More detailed and accurate studies about the knowledge of the fluid temperature distribution inside heat exchangers are greatly required nowadays. This is needed to provide correct evaluation of thermal and structural performances, mainly in the industrial fields (such as nuclear engineering) where larger, more efficient and reliable units are sought, and where a good thermal design can not leave integrity and safety requirements out of consideration [1--3]. In this view, the huge amount of scientific and technical informations available in several texts [4, 5], mainly concerning charts and maps useful for exit temperatures and effectiveness considerations, are not quite satisfactory for a more rigorous and local analysis. In fact the investigation of the thermomechanieal behaviour (thermal stresses, plasticity, creep, fracture mechanics) of tubes, plates, fins and structural components in the heat exchanger insists on the temperature distribution. So it should be very useful to equip the stress analysis codes for heat exchangers withsimple analytical expressions for the temperature map (without resorting to time consuming numerical solutions for the thermal problem), allowing a sensible saving in computer costs. Analytical predictions provide the thermal map of a heat exchanger, aiding in the designoptimization.Moreover they greatly reduce the need of scale model testing (generally prohibitively expensive in nuclear engineering), and furnish an accurate benchmark for the validation of more refined numerical solutions obtained by computer codes. The purpose of this paper is to present the local bulk-wall and fluid temperature distributions forU-tube heat exchangers, solving analytically the energy balance equations.122 General assumptionsLet m, c, h, and A denote mass flow rate (kg/s), specific heat (J/kg -1 K-l), heat transfer coefficient(Wm -2 K-l), and heat transfer surface (m2) for each leg, respectively. The theoretical analysis is based on classical assumptions [6] :-- steady state working conditions,-- equal flow distribution (same mass flow rate for every tube of the bundle),-- single phase fluid flow,-- constant physical properties of exchanger core and fluids,-- adiabatic exchanger shell or shroud,-- no heat conduction in the axial direction,-- constant thermal conductances hA comprehending wall resistance and fouling.According to this last assumption, the wall temperature is the same for the primary and secondary flow. However the heat transfer balance between the fluids is quite respected, since the fluid-wall conductances are appropriately reduced to account for the wall thermal resistance and thefouling factor [6]. The dimensionless parameters typical of the heat transfer phenomena between the fluids arethe flow capacitance and the heat transfer resistance ratiosand the number of transfer units, commonly labaled NTU in the literature,where (mc)min stands for the smaller of the two values (mc)sand (mc)p.In (1) the subscripts s and p refer to secondary and primary fluid, respectively. Only three of the previous five numbers are independent, in fact :The boundary conditions are the inlet temperatures of both fluids3 Parallel and counter flow solutionsThe well known monodimensional solutions for single-pass parallel and counterflow heat exchanger,which will be useful later for the analysis of U-tube heat exchangers, are presented below. If t, T,νare wall, primary fluid, and secondary fluid bulk temperatures (K), and ξ and L represent the longitudinal space coordinate and the heat exchanger length (m), the energy balance equations in dimensionless coordinate x = ξ/L, for parallel and counterflow respectivelyread asM. Spiga and G. Spiga: Temperature profiles in U-tube heat exchangersAfter some algebra, a second order differential equation is deduced for the temperature of the primary (or secondary) fluid, leading to the solutionwhere the integration constants follow from the boundary conditions T(0)=T i , ν(0)≒νifor parallel T(1) = Ti ,ν(0) = νifor counter flow. They are given-- for parallel flow by - for counterflow byWishing to give prominence to the number of transfer units, it can be noticed thatFor counterflow heat exchangers, when E = 1, the solutions (5), (6) degenerate and the fluidtemperatures are given byIt can be realized that (5) -(9) actually depend only on the two parametersE, NTU. However a formalism involving the numbers E, Ns. R has been chosen here in order to avoid the double formalism (E ≤1 and E > 1) connected to NTU.4 U-tube heat exchangerIn the primary side of the U-tube heat exchanger, whose schematic drawing is shown in Fig. 1, the hot fluid enters the inlet plenum flowing inside the tubes, and exits from the outlet plenum. In the secondary side the fluid flows in the tube bundle (shell side). This arrangement suggests that the heat exchanger can be considered as formed by the coupling of a parallel and a counter-flow heat exchanger, each with a heigth equal to the half length of the mean U-tube. However it is necessary to take into account the interactions in the secondary fluid between the hot and the cold leg, considering that the two flows are not physically separated. Two extreme opposite conditions can be investigated: no mixing and full mixing in the two streams of the secondary fluid. The actual heat transfer phenomena are certainly characterized by only a partial mixing ofthe shell side fluid between the legs, hence the analysis of these two extreme theoretical conditions will provide an upper and a lower limit for the actual temperature distribution.4.1 No mixing conditionsIn this hypothesis the U-tube heat exchanger can be modelled by two independent heat exchangers, a cocurrent heat exchanger for the hot leg and a eountercurrent heat exchanger for the cold leg. The only coupling condition is that, for the primary fluid, the inlet temperature in the cold side must be the exit temperature of the hot side. The numbers R, E, N, NTU can have different values for the two legs, because of thedifferent values of the heat transfer coefficients and physical properties. The energy balance equations are the same given in (2)--(4), where now the numbers E and Ns must be changed in E/2 and 2Ns in both legs, if we want to use in their definition the total secondary mass flow rate, since it is reduced in every leg to half the inlet mass flow rate ms. Of course it is understood that the area A to be used here is half of the total exchange area of the unit, as it occurs for the length L too. Recalling (5)--(9) and resorting to the subscripts c and h to label the cold and hot leg, respectively, the temperature profile is given bywhere the integration constants are:M. Spiga and G. Spiga: Temperature profiles in U-tube heat exchangersIf E, = 2 the solutions (13), (14) for the cold leg degenerate into4.2 Full mixing conditionsA different approach can be proposed to predict the temperature distributions in the core wall and fluids of the U-tube heat exchanger. The assumption of full mixing implies that the temperaturesof the secondary fluid in the two legs, at the same longitudinal section, are exactly coinciding. In this situation the steady state energy balance equations constitute the following differential set :The bulk wall temperature in both sides is thenand (18)--(22) are simplified to a set of three equations, whose summation gives a differential equation for the secondary fluid temperature, withgeneral solutionwhere # is an integration constant to be specified. Consequently a second order differential equation is deduced for the primary fluid temperature in the hot leg :where the numbers B, C and D are defined asThe solution to (24) allows to determine the temperaturesand the number G is defined asThe boundary conditions for the fluids i.e. provide the integration constantsAgain the fluid temperatures depend only on the numbers E and NTU.5 ResultsThe analytical solutions allow to deduce useful informations about temperature profiles and effectiveness. Concerning the U-tube heat exchanger, the solutions (10)--(15) and (25)--(27) have been used as a benchmark for the numerical predictions of a computer code [7], already validated, obtaining a very satisfactory agreement.M. Spiga and G. Spiga: Temperature profiles in U-tube heat exchangers 163 Moreover a testing has been performed considering a Shutte & Koerting Co. U-tube heat exchanger, designed for the cooling system of a spent nuclear fuel storage pool. The demineralized water of the fuel pit flows inside the tubes, the raw water in the shell side. The correct determination of the thermal resistances is very important to get a reliable prediction ; for every leg the heat transfer coefficients have been evaluated by the Bittus-Boelter correlation in the tube side [8], by the Weisman correlation in the shell side [9] ; the wall material isstainless steel AISI 304.and the circles indicate the experimental data supplied by the manufacturer. The numbers E, NTU, R for the hot and the cold leg are respectively 1.010, 0.389, 0.502 and 1.011, 0.38~, 0.520. The difference between the experimental datum and the analytical prediction of the exit temperature is 0.7% for the primary fluid, 0.9% for the secondary fluid. The average exit temperature of the secondary fluid in the no mixing model differs from the full mixing result only by 0.6%. It is worth pointing out the relatively small differences between the profiles obtained through the two different hypotheses (full and no mixing conditions), mainly for the primary fluid; the actual temperature distribution is certainly bounded between these upper and lower limits,hence it is very well specified. Figures 3-5 report the longitudinal temperaturedistribution in the core wall, τw = (t -- νi)/(Ti -- νi), emphasizing theeffects of the parameters E, NTU, R.As above discussed this profile can be very useful for detailed stress analysis, for instance as anM. Spiga and G. Spiga: Temperature profiles in U-tube heat exchangersinput for related computer codes. In particular the thermal conditions at the U-bend transitions are responsible of a relative movement between the hot and the cold leg, producing hoop stresses with possible occurrence of tube cracking . It is evident that the cold leg is more constrained than the hot leg; the axial thermal gradient is higher in the inlet region and increases with increasing values of E, NTU, R. The heat exchanger effectiveness e, defined as the ratio of the actual heat transfer rate(mc)p (Ti-- Tout), Tout=Tc(O), to the maximum hypothetical rateunder the same conditions (mc)min (Ti- νi), is shown in Figs. 6, 7respectively versus the number of transfer units and the flow capacitance ratio. As known, the balanced heat exchangers E = 1) present the worst behaviour ; the effectiveness does not depend on R and is the same for reciprocal values of the flow capacitance ratio.U形管换热器m . Spiga和g . Spiga,博洛尼亚摘要:分析解决方案提供一些两相流体在u形管换热器中的分布情况。
控制系统介绍外文文献翻译、中英文翻译、外文翻译
Introductions to Control SystemsAutomatic control has played a vital role in the advancement of engineering and science. In addition to its extreme importance in space-vehicle, missile-guidance, and aircraft-piloting systems, etc, automatic control has become an important and integral part of modern manufacturing and industrial processes. For example, automatic control is essential in such industrial operations as controlling pressure, temperature, humidity, viscosity, and flow in the process industries; tooling, handling, and assembling mechanical parts in the manufacturing industries, among many others.Since advances in the theory and practice of automatic control provide means for attaining optimal performance of dynamic systems, improve the quality and lower the cost of production, expand the production rate, relieve the drudgery of many routine, repetitive manual operations etc, most engineers and scientists must now have a good understanding of this field.The first significant work in automatic control was James Watt’s centrifugal governor for the speed control of a steam engine in the eighteenth century. Other significant works in the early stages of development of control theory were due to Minorsky, Hazen, and Nyquist, among many others. In 1922 Minorsky worked on automatic controllers for steering ships and showed how stability could be determined by the differential equations describing the system. In 1934 Hazen, who introduced the term “ervomechanisms”for position control systems, discussed design of relay servomechanisms capable of closely following a changing input.During the decade of the 1940’s, frequency-response methods made it possible for engineers to design linear feedback control systems that satisfied performance requirements. From the end of the 1940’s to early 1950’s, the root-locus method in control system design was fully developed.The frequency-response and the root-locus methods, which are the core of classical theory, lead to systems that are stable and satisfy a set of more or less arbitrary performance requirements. Such systems are, ingeneral, not optimal in any meaningful sense. Since the late 1950’s, the emphasis on control design problems has been shifted from the design of one of many systems that can work to the design of one optimal system in some meaningful sense.As modern plants with many inputs and outputs become more and more complex, the description of a modern control system requires a large number of equations. Classical control theory, which deals only with single-input-single-output systems, becomes entirely powerless for multiple-input-multiple-output systems. Since about 1960, modern control theory has been developed to cope with the increased complexity of modern plants and the stringent requirements on accuracy, weight, and industrial applications.Because of the readily available electronic analog, digital, and hybrid computers for use in complex computations, the use of computers in the design of control systems and the use of on-line computers in the operation of control systems are now becoming common practice.The most recent developments in modern control theory may be said to be in the direction of the optimal control of both deterministic and stochastic systems as well as the adaptive and learning control of complex systems. Applications of modern control theory to such nonengineering fields as biology, economics, medicine, and sociology are now under way, and interesting and significant results can be expected in the near future.Next we shall introduce the terminology necessary to describe control systems.Plants. A plant is a piece of equipment, perhaps just a set of machine parts functioning together, the purpose of which is to perform a particular operation. Here we shall call any physical object to be controlled (such as a heating furnace, a chemical reactor, or a spacecraft) a plant.Processes. The Merriam-Webster Dictionary defines a process to be a natural, progressively continuing operation or development marked by a series of gradual changes that succeed one another in a relatively fixed way and lead toward a particular result or end; or an artificial or voluntary, progressively continuing operation that consists of a series of controlledactions or movements systematically directed toward a particular result or end.Here we shall call any operation to be controlled a process. Examples are chemical, economic, and biological process.Systems. A system is a combination of components that act together and perform a certain objective. A system is not limited to abstract, dynamic phenomena such as those encountered in economics. The word “system” should, therefore, be interpreted to imply physical, biological, economic, etc., system.Disturbances. A disturbance is a signal which tends to adversely affect the value of the output of a system. If a disturbance is generated within the system, it is called internal, while an external disturbance is generated outside the system and is an input.Feedback control.Feedback control is an operation which, in the presence of disturbances, tends to reduce the difference between the output of a system and the reference input (or an arbitrarily varied, desired state) and which does so on the basis of this difference. Here, only unpredictable disturbance (i.e., those unknown beforehand) are designated for as such, since with predictable or known disturbances, it is always possible to include compensation with the system so that measurements are unnecessary.Feedback control systems. A feedback control system is one which tends to maintain a prescribed relationship between the output and the reference input by comparing these and using the difference as a means of control.Note that feedback control systems are not limited to the field of engineering but can be found in various nonengineering fields such as economics and biology. For example, the human organism, in one aspect, is analogous to an intricate chemical plant with an enormous variety of unit operations.The process control of this transport and chemical-reaction network involves a variety of control loops. In fact, human organism is an extremely complex feedback control system.Servomechanisms. A servomechanism is a feedback control system in which the output is some mechanical position, velocity, or acceleration. Therefore, the terms servomechanism and position- (or velocity- oracceleration-) control system are synonymous. Servomechanisms are extensively used in modern industry. For example, the completely automatic operation of machine tools, together with programmed instruction, may be accomplished by use of servomechanisms.Automatic regulating systems. An automatic regulating system is a feedback control system in which the reference input or the desired output is either constant or slowly varying with time and in which the primary task is to maintain the actual output at the desired value in the presence of disturbances.A home heating system in which a thermostat is the controller is an example of an automatic regulating system. In this system, the thermostat setting (the desired temperature) is compared with the actual room temperature. A change in the desired room temperature is a disturbance in this system. The objective is to maintain the desired room temperature despite changes in outdoor temperature. There are many other examples of automatic regulating systems, some of which are the automatic control of pressure and of electric quantities such as voltage, current and frequency.Process control systems. An automatic regulating system in which the output is a variable such as temperature, pressure, flow, liquid level, or pH is called a process control system.Process control is widely applied in industry. Programmed controls such as the temperature control of heating furnaces in which the furnace temperature is controlled according to a preset program are often used in such systems. For example, a preset program may be such that the furnace temperature is raised to a given temperature in a given time interval and then lowered to another given temperature in some other given time interval. In such program control the set point is varied according to the preset time schedule. The controller then functions to maintain the furnace temperature close to the varying set point. It should be noted that most process control systems include servomechanisms as an integral part.控制系统介绍自动控制在工程学和科学的推进扮演一个重要角色。
建筑施工质量控制外文翻译参考文献
建筑施工质量控制外文翻译参考文献(文档含中英文对照即英文原文和中文翻译)译文:建筑施工过程中质量管理的动机分析和控制方法的研究摘要在建筑施工过程中实施质量管理可以有效地防止在后续建筑产品使用过程中安全事故的发生。
与此同时可以减少建设供应链的总成本,这也有利于增强建筑施工企业的品牌知名度和声誉。
在建筑施工过程中结合质量管理过程和当前建筑施工阶段的主要质量问题,分析了建设过程中的管理动机,将供应链管理与目标管理理念和方法应用到质量管理中,最后提出了具体的质量控制措施。
这些都是为了在建筑施工过程中提高建筑产品的总体质量。
关键字——建筑施工、质量管理、质量动机、控制1.引言调查显示建筑施工企业主要采用现场控制的质量管理模式是预先控制。
大多企业常常使得建筑施工过程中与建设管理中的质量管理相同,他们通常忽略了施工准备阶段质量问题的预防,如供应商的选择、道路的规划和临时设施,这些因素在建筑施工过程中的质量管理上起着至关重要的作用。
建设质量事故频繁发生,引起了许多领域的高度关注,如各级政府部门、施工企业和业主,特别是重庆綦江虹桥的坍塌、五龙的滑坡和洪湖湿地路基施工中的一系列质量安全事故,人们开始对施工质量问题做全方位的思考。
通过研究李秀峰总结归纳了造成工程的质量问题并引入项目质量控制分析方法,Low Sui Pheng 和Jasmine Ann Teo[2] 建立了施工中的质量管理框架来通过经验分析实现项目的质量控制,SangHyun Lee and others[3] 利用系统质量动态结构和变更管理模型的编程方法和控制方法,最终实现了大规模的并行设计和施工项目的管理和控制。
方唐分析了建设项目质量管理的整个过程和控制方法,她认为应该实现对影响建设单位质量的人、材料、机械、方法和环境的完全控制;吴天翔研究出管理因素是影响建设项目质量控制的重要因素,强调了施工过程中需要严格控制的各个方面和整体实现加强管理的需要。
为了解决建设施工过程中的建设质量问题,韩伟建立了一个建筑项目的分析和处理程序。
控制工程英语介绍
控制工程英语介绍English:"Control engineering, also known as control systems engineering, is a branch of engineering that deals with the design, analysis, and application of systems to maintain desired levels of performance and stability. This field combines knowledge from various disciplines such as mathematics, physics, and engineering to create automated systems that can regulate or guide processes efficiently. Control systems can be found in a wide range of industries, including manufacturing, automotive, aerospace, and robotics, where precise control of variables such as temperature, pressure, speed, or position is essential.The fundamental concept in control engineering is feedback, which involves monitoring the output of a system and using it to adjust the input for desired outcomes. There are two primary types of control systems: open-loop and closed-loop (also known as feedback control systems). In an open-loop system, the input is not adjusted based onthe output, while in a closed-loop system, the system continuously monitors and adjusts itself based on feedback.Control engineers use various mathematical and computational techniques to model systems and design controllers. These techniques include linear and nonlinear control theories, state-space representation, frequency domain analysis, and digital control methods. With the rise of smart technologies and the Internet of Things (IoT), control engineering plays an increasingly vital role in the development of intelligent, interconnected systems.As a discipline, control engineering offers the potential to improve efficiency, safety, and reliability across numerous sectors. For instance, in manufacturing, control systems can optimize production processes and improve product quality. In transportation, they contribute to the development of autonomous vehicles and traffic management systems. In the energy sector, control engineering can enhance the integration of renewable energy sources and grid stability. Thus, control engineering is a crucial field that drives innovation and advancements in modern technology."中文翻译:"控制工程,也称为控制系统工程,是工程学的一个分支,涉及设计、分析和应用系统以保持所需的性能和稳定性水平。
材料成型及控制工程外文文献翻译
本科毕业论文外文文献及译文文献、资料题目:The effects of heat treatment onthe microstructure and mechani-cal property of laser melting dep-ositionγ-TiAl intermetallic alloys 文献、资料来源:Materials and Design文献、资料发表(出版)日期:2009.10.25院(部):材料科学与工程学院专业:材料成型及控制工程班级:姓名:学号:指导教师:翻译日期:2011.4.3中文译文:热处理对激光沉积γ-TiAl金属间化合物合金的组织与性能的影响摘要:Ti-47Al-2.5V-1Cr 和Ti-40Al-2Cr (at.%)金属间化合物合金通过激光沉积(LMD)成形技术制造。
显微组织的特征通过光学显微镜(OM)、扫描电子显微镜(SEM)、投射电子显微镜(TEM)、和X射线衍射仪(XRD)检测。
沿轴向评估热处理后的沉积试样室温下的抗拉性能和维氏硬度。
结果表明:由γ-TiAl 和α2-Ti3Al构成的γ-TiAl基体试样具有全密度柱状晶粒和细的层状显微组织。
Ti-47Al-2.5V-1Cr基体合金和Ti-40Al-2Cr基体合金沿轴向的室温抗拉强度大约分别为650 MPa、600MPa,而最大延伸率大约为0.6% 。
热处理后的Ti-47Al-2.5V-1Cr和Ti-40Al-2Cr合金可以得到不同的显微组织。
应力应变曲线和次表面的拉伸断裂表明沉积和热处理后的试样的断裂方式是沿晶断裂。
1.简介金属间化合物γ-TiAl合金由于其高熔点(﹥1450℃)、低密度(3g/cm3)、高弹性模量(160-180GPa)和高蠕变强度(直到900℃)成为很有前景的高温结构材料,一直受到广泛研究[1–4]。
但是对于其结构应用来说,这种材料主要缺点之一是在室温下缺少延展性。
此外,这种合金运用传统的制造工艺诸如锻压、轧制和焊接,加工起来比较困难[5]。
控制工程学术英语
控制工程学术英语Control Engineering Academic EnglishControl engineering is a multidisciplinary field that combines elements of electrical, mechanical, and computer engineering to design and develop systems that regulate and manage the behavior of other devices or systems. This field has a wide range of applications, from industrial automation and robotics to transportation and healthcare. Academic writing in control engineering requires a specialized vocabulary and a clear, concise communication style to convey complex technical concepts effectively.One of the key aspects of control engineering academic writing is the use of mathematical models and equations. These models are used to describe the behavior of the systems being controlled and to develop algorithms and control strategies. The use of mathematical notation is essential in this field, and it is important to ensure that equations are presented clearly and accurately. Additionally, control engineers must be able to interpret and analyze the results of these mathematical models to make informed decisions about the design and implementation of control systems.Another important aspect of control engineering academic writing is the use of graphical representations, such as block diagrams, signal flow graphs, and control system diagrams. These visual aids are used to illustrate the structure and behavior of control systems, making it easier for readers to understand the underlying concepts. Control engineers must be skilled in creating and interpreting these graphical representations, as they are a crucial part of the communication process in the field.In addition to the technical aspects of control engineering, academic writing in this field also requires a strong understanding of the broader context in which control systems are used. This includes knowledge of industry standards, regulatory frameworks, and ethical considerations. Control engineers must be able to communicate the implications of their work to a range of stakeholders, including policymakers, industry leaders, and the general public.One of the challenges of control engineering academic writing is the need to balance technical detail with accessibility. Control engineers must be able to communicate complex ideas to a diverse audience, including those who may not have a deep understanding of the field. This requires the use of clear and concise language, as well as the ability to explain technical concepts in a way that is easy to understand.Despite these challenges, control engineering academic writing is an essential component of the field. It allows researchers and practitioners to share their ideas, collaborate on solutions, and advance the state of the art in control systems. By mastering the skills of academic writing in control engineering, individuals can contribute to the ongoing development of this critical field and help shape the future of technology and innovation.。
工程施工管理专业外文文献翻译中英文
xxxxxx大学本科毕业设计外文翻译Project Cost Control: the Way it Works工程本钱控制:它的工作方式学院〔系〕:xxxxxxxxxxxx专业:xxxxxxxx学生姓名:xxxxx学号:xxxxxxxxxx指导教师:xxxxxx评阅教师:完成日期:xxxx大学工程本钱控制:它的工作方式在最近的一次咨询任务中,我们意识到对于整个工程本钱控制体系是如何设置和应用的,仍有一些缺乏理解。
所以我们决定描述它是如何工作的。
理论上,工程本钱控制不是很难跟随。
首先,建立一组参考基线。
然后,随着工作的深入,监控工作,分析研究结果,预测最终结果并比拟参考基准。
如果最终的结果不令人满意,那么你要对正在进展的工作进展必要的调整,并在适宜的时间间隔重复。
如果最终的结果确实不符合基线方案,你可能不得不改变方案。
更有可能的是,会 (或已经) 有围变更来改变参考基线,这意味着每次出现这种情况你必须改变基线方案。
但在实践中,工程本钱控制要困难得多,通过工程数量无法控制本钱也证明了这一点。
正如我们将看到的,它还需要大量的工作,我们不妨从一开场启用它。
所以,要跟随工程本钱控制在整个工程的生命周期。
同时,我们会利用这一时机来指出几个重要文件的适当的地方。
其中包括商业案例,请求〔资本〕拨款〔执行〕,工作包和工作分解构造,工程章程(或摘要),工程预算或本钱方案、挣值和本钱基线。
所有这些有助于提高这个组织的有效地控制工程本钱的能力。
业务用例和应用程序(执行)的资金重要的是要注意,当负责的管理者对于工程应如何通过工程生命周期展开有很好的理解时,工程本钱控制才是最有效的。
这意味着他们在主要阶段的关键决策点之间行使职责。
他们还必须识别工程风险管理的重要性,至少可以确定并方案阻止最明显的潜在风险事件。
在工程的概念阶段•每个工程始于确定的时机或需要的人。
通常是有着重要性和影响力的人,如果工程继续,这个人往往成为工程的赞助。
电气控制工程外文翻译
附录附录1 外文文献C8051F020 (PORT INPUT/OUTPUT)The C8051F020/1/2/3 are fully integrated mixed-signal System on a Chip MCUs with 64 digital I/O pins (C8051F020/2) or 32 digital I/O pins (C8051F021/3), organized as 8-bit Ports. The lower ports: P0, P1, P2, and P3, are both bit- and byte-addressable through their corresponding Port Data registers. The upper ports: P4, P5, P6, and P7 are byte-addressable. All Port pins are 5 V-tolerant, and all support configurable Open-Drain or Push-Pull output modes and weak pull-ups.The C8051F020/1/2/3 devices have a wide array of digital resources which are available through the four lower I/O Ports: P0, P1, P2, and P3. Each of the pins on P0, P1, P2, and P3, can be defined as a General-Purpose I/O (GPIO) pin or can be controlled by a digital peripheral or function (like UART0 or /INT1 for example), as shown in Figure 17.2. The system designer controls which digital functions are assigned pins, limited only by the number of pins available. This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read from its associated Data register regardless of whether that pin has been assigned to a digital peripheral or behaves as GPIO. The Port pins on Port1 can be used as Analog Inputs to ADC1.The Priority Crossbar Decoder, or “Crossbar”, allocates and assigns Port pins on Port 0 through Port 3 to the digital peripherals (UARTs, SMBus, PCA, Timers, etc.) on the device using a priority order. The Port pins are allocated in order starting with P0.0 and continue through P3.7 if necessary. The digital peripherals are assigned Port pins in a priority order which is listed in Figure 17.3, with UART0 having the highest priority and CNVSTR having the lowest priority.The Crossbar assigns Port pins to a peripheral if the corresponding enable bits of the peripheral are set to a logic 1 in the Crossbar configuration registers XBR0, XBR1, and XBR2, shown in Figure 17.7, Figure 17.8, and Figure 17.9. For example, if theUART0EN bit (XBR0.2) is set to a logic 1, the TX0 and RX0 pins will be mapped to P0.0 and P0.1 respectively. Because UART0 has the highest priority, its pins will always be mapped to P0.0 and P0.1 when UART0EN is set to a logic 1. If a digital peripheral’s enable bits are not set to a logic 1, then its por ts are not accessible at the Port pins of the device. Also note that the Crossbar assigns pins to all associated functions when a serial communication peripheral is selected (i.e. SMBus, SPI, UART). It would be impossible, for example, to assign TX0 to a Port pin without assigning RX0 as well. Each combination of enabled peripherals results in a unique device pinout.All Port pins on Ports 0 through 3 that are not allocated by the Crossbar can be accessed as General-Purpose I/O (GPIO) pins by reading and writing the associated Port Data registers ,a set of SFRs which are both byte- and bit-addressable. The output states of Port pins that are allocated by the Crossbar are controlled by the digital peripheral that is mapped to those pins. Writes to the Port Data registers (or associated Port bits) will have no effect on the states of these pins.A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regardless of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC, CLR, SET, and the bitwise MOV operation). During the read cycle of the read-modify-write instruction, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.Because the Crossbar registers affect the pinout of the peripherals of the device, they are typically configured in the initialization code of the system before the peripherals themselves are configured. Once configured, the Crossbar registers are typically left alone.Once the Crossbar registers have been properly configured, the Crossbar is enabled by setting XBARE (XBR2.6) to a logic 1. Until XBARE is set to a logic 1, the output drivers on Ports 0 through 3 are explicitly disabled in order to prevent possible contention on the Port pins while the Crossbar registers and other registerswhich can affect the device pinout are being written.The output drivers on Crossbar-assigned input signals (like RX0, for example) are explicitly disabled; thus the values of the Port Data registers and the PnMDOUT registers have no effect on the states of these pins.The output drivers on Ports 0 through 3 remain disabled until the Crossbar is enabled by setting XBARE (XBR2.6) to a logic 1.The output mode of each port pin can be configured as either Open-Drain or Push-Pull; the default state is Open-Drain. In the Push-Pull configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and writing a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent contention between devices in systems where the Port pin participates in a shared interconnection in which multiple outputs are connected to the same physical wire (like the SDA signal on an SMBus connection).The output modes of the Port pins on Ports 0 through 3 are determined by the bits in the associated PnMDOUT registers (See Figure 17.11, Figure 17.14, Figure 17.16, and Figure 17.18). For example, a logic 1 in P3MDOUT.7 will configure the output mode of P3.7 to Push-Pull; a logic 0 in P3MDOUT.7 will configure the output mode of P3.7 to Open-Drain. All Port pins default to Open-Drain output.The PnMDOUT registers control the output modes of the port pins regardless of whether the Crossbar has allocated the Port pin for a digital peripheral or not. The exceptions to this rule are: the Port pins connected to SDA, SCL, RX0 (if UART0 is in Mode 0), and RX1 (if UART1 is in Mode 0) are always configured as Open-Drain outputs, regardless of the settings of the associated bits in the PnMDOUT registers.A Port pin is configured as a digital input by setting its output mode to “Open-Drain” and writing a logic 1 to t he associated bit in the Port Data register. For example, P3.7 is configured as a digital input by setting P3MDOUT.7 to a logic 0 and P3.7 to a logic 1.If the Port pin has been assigned to a digital peripheral by the Crossbar and that pin functions as an input (for example RX0, the UART0 receive pin), then the output drivers on that pin are automatically disabled.In addition to the external interrupts /INT0 and /INT1, whose Port pins are allocated and assigned by the Crossbar, P3.6 and P3.7 can be configured to generate edge sensitive interrupts; these interrupts are configurable as falling- or rising-edge sensitive using the IE6CF (P3IF.2) and IE7CF (P3IF.3) bits. When an active edge is detected on P3.6 or P3.7, a corresponding External Interrupt flag (IE6 or IE7) will be set to a logic 1 in the P3IF register (See Figure 17.19). If the associated interrupt is enabled, an interrupt will be generated and the CPU will vector to the associated interrupt vector location. See Section “12.3. Interrupt Handler” on page 116 for more information about interrupts.By default, each Port pin has an internal weak pull-up device enabled which provides a resistive connection (about 100 k兦) between the pin and VDD. The weak pull-up devices can be globally disabled by writing a logic 1 to the Weak Pull-up Disable bit, (WEAKPUD,XBR2.7). The weak pull-up is automatically deactivated on any pin that is driving a logic 0; that is, an output pin will not contend with its own pull-up device. The weak pull-up device can also be explicitly disabled on a Port 1 pin by configuring the pin as an Analog Input, as described below.The pins on Port 1 can serve as analog inputs to the ADC1 analog MUX. A Port pin is configured as an Analog Input by writing a logic 0 to the associated bit in theP1MDIN register (see Figure 17.13). All Port pins default to a Digital Input mode. Configuring a Port pin as an analog input:1.Disables the digital input path from the pin. This prevents additional power supply current from being drawn when the voltage at the pin is near VDD /2. A read of the Port Data bit will return a logic 0 regardless of the voltage at the Port pin.2.Disables the weak pull-up device on the pin.3.Causes the Crossbar to “skip over” the pin when allocating Port pins for digital peripherals.If the External Memory Interface (EMIF) is enabled on the Low ports (Ports 0through 3), EMIFLE (XBR2.1) should be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and if the External Memory Interface is in Multiplexed mode, P0.5 (ALE).If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the External Memory Interface will control the output states of the affected Port pins during the execution phase of the MOVX instruction, regardless of the settings of the Crossbar registers or the Port Data registers. The output configuration of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly disable the output drivers on the Data Bus.In this example, we configure the Crossbar to allocate Port pins for UART0, the SMBus, UART1, /INT0, and /INT1 (8 pins total). Additionally, we configure the External Memory Interface to operate in Multiplexed mode and to appear on the Low ports. Further, we configure P1.2, P1.3, and P1.4 for Analog Input mode so that the voltages at these pins can be measured by ADC1. The configuration steps are as follows:1.XBR0, XBR1, and XBR2 are set such that UART0EN = 1, SMB0EN = 1, INT0E = 1, INT1E = 1, and EMIFLE = 1. Thus: XBR0 = 0x05, XBR1 = 0x14, and XBR2 = 0x02.2.We configure the External Memory Interface to use Multiplexed mode and to appear on the Low ports. PRTSEL = 0, EMD2 = 0.3.We configure the desired Port 1 pins to Analog Input mode by setting P1MDIN to0xE3 (P1.4, P1.3, and P1.2 are Analog Inputs, so their associated P1MDIN bits are set to logic 0).4.We enable the Crossbar by setting XBARE = 1: XBR2 = 0x46.-UART0 has the highest priority, so P0.0 is assigned to TX0, and P0.1 is assigned to RX0.-The SMBus is next in priority order, so P0.2 is assigned to SDA, and P0.3 is assigned to SCL.-UART1 is next in priority order, so P0.4 is assigned to TX1. Because the External Memory Interface is selected on the lower Ports, EMIFLE = 1, which causes theCrossbar to skip P0.6 (/RD) and P0.7 (/WR). Because the External Memory Interface is configured in Multiplexed mode, the Crossbar will also skip P0.5 (ALE). RX1 is assigned to the next non-skipped pin, which in this case is P1.0.-/INT0 is next in priority order, so it is assigned to P1.1.-P1MDIN is set to 0xE3, which configures P1.2, P1.3, and P1.4 as Analog Inputs, causing the Crossbar to skip these pins.-/INT1 is next in priority order, so it is assigned to the next non-skipped pin, which is P1.5.-The External Memory Interface will drive Ports 2 and 3 (denoted by red dots in Figure 17.6) during the execution of an off-chip MOVX instruction.5.We set the UART0 TX pin (TX0, P0.0), UART1 TX pin (TX1, P0.4), ALE, /RD,/WR (P0.[7:3]) outputs to Push-Pull by setting P0MDOUT = 0xF1.6.We configure the output modes of the EMIF Ports (P2, P3) to Push-Pull by settingP2MDOUT = 0xFF and P3MDOUT = 0xFF.7.We explicitly disable the output drivers on the 3 Analog Input pins by settingP1MDOUT = 0x00 (configure outputs to Open-Drain) and P1 = 0xFF (a logic 1 selects the high-impedance state).附录2 文献翻译C8051F020 (端口输入/输出)C8051F020/1/2/3 MCU 是高集成度的混合信号片上系统,有按8 位端口组织的64 个数字I/O 引脚(C8051F020/2)或32 个数字I/O 引脚(C8051F021/3)。
过程装备与控制工程专业外语(原文+翻译)
Unit 21Pumps1. IntroductionPump, device used to raise, transfer, or compress liquids and gases. Four' general classes of pumps for liquids are described below t In all of them , steps are taken to prevent cavitation (the formation of a vacuull1), which would reduce the flow and damage the structure of the pump, - pumps used for gases and vapors are usually known as compressors . The study of fluids in motion is called fluid dynamics.1.介绍泵是提出,转移或压缩液体和气体的设备。
下面介绍四种类型的泵。
在所有的这些中,我们一步步采取措施防止气蚀,气蚀将减少流量并且破坏泵的结构。
用来处理气体和蒸汽的泵称为压缩机,研究流体的运动的科学成为流体动力学。
Water Pump, device lor moving water from one location to another, using tubes or other machinery. Water pumps operate under pressures ranging from a fraction of a pound to more than 10,000 pounds per square inch. Everyday examples of water pumps range from small electric pumps that circulate and aerate water in aquariums and fountains to sump pumps that remove 'Water from beneath the foundations of homes.水泵是用管子或其他机械把水从一个地方传到另一个地方。
自动控制毕业论文中英文资料外文翻译文献
毕业论文外文译文学院自动化与电气工程学院专业自动控制Component-based Safety Computer of RailwaySignal Interlocking System1 IntroductionSignal Interlocking System is the critical equipment which can guarantee traffic safety and enhance operational efficiency inrailwaytransportation. For a longtime, the core control computer adopts in interlocking system is the special customized high-gradesafety computer, for example,the SIMIS ofSiemens, the EI32of Nipp on Signal, and soon. Along with therapiddevelopme nt of electronic technology, the customized safety comput er isfacing severechallenges,for instance,the high development costs, poor usability,weakexpansibility and slow technologyupdate. Toovercomethe flaws ofthe high-grade special customized computer, the U.S. Department of Defensehas putforwardthe concept:we shouldadopt commercial standardsto replace military normsand standards formeeting consumers’demand[1]. In the meantime, thereare severalexplorations and practices about adoptingopensystem architecture inavionics.The United Stated andEurope have do muchresearch about utilizing cost-effective fault-tolerant computer to replace the dedicated computer in aerospace and othersafety-critical fields. Inrecentyears, it is gradu ally becoming a new trend thatthe utilization of standardized components inaerospace, industry, transportatio nand othersafety-critical fields.2Railwayssignal interlocking system2.1Functionsof signal interlocking system The basic functionofsignal interlocking system is t oprotect train safety bycontrollingsignal equipme nts, such as switchpoints,signals andtrackunitsinastation,and it handles routes viaac ertaininterlocking regulation.Sincethebirth of the railwaytransportation, signalinterlocking system has gone through manual signal, mechanical signal, relay-basedinterlocking,andthe moderncomputer-based Interlocking System.2.2 Architecture of signal interlockingsystem Generally,theInterlockingSystemhas a hierarchical structure. According tothe function of equipments,thesystem can be divided to the function of equipments;t he system canbe dividedinto three layers as shown in figure1.Figure 1 Architecture of Signal Interlocking System 3 Component-based safety computer design3.1DesignstrategyThe design concept of component-basedsafety criticalcomputer is different from thatof special customized computer.Our designstrategy of SIC is on a base of fault-tolerance and system integration.We separatetheSIC intothreelayers, the standardized component unit layer, safetysoftwarelayer and thesystem laye r.Different safety functions are allocated foreachlayer,and the final integration of thethreelayers ensures the predefined safety integritylevelof the wholeSIC. The three layers canbedescribed as follows: (1)Component unit layer includesfourindepen dent standardizedCPU modules. Ahardware“SAFETYAND” logic is implemented inthis year.(2)Safety softwarelayermainly utilizes fail-safe strategyand fault-tolerant management.Theinterlockingsafety computing of the whole systemado pts two outputs fromdifferent CPU,it canmostly ensure thediversity ofsoftware to hold withdesign errors of signal versionand remove hidden risks.(3)System layer aims to improve reliability, av ailabilityand maintainability bymeans ofredundancy.3.2 Designof hardware fault-tolerant structureAsshown infigure2,theSIC of four indep endent component units (C11, C12,C21, C22). Thefault-tolerant architectureadopts dual2 vote 2 (2v2×2) structure,andakind of high-performance standardized modulehas been selectedas computing unit which adopts In telX Scalekernel, 533 MHZ.The operation of SIC is based on a dual two-layer data buses. The high bus adopts thestandard Ethernet andTCP/IP communication protocol, andthelowbus is Controller AreaNetwork (CAN). C11、C12 and C21、C22respectivelymake up of twosafety computingcomponents IC1andIC2, which are of 2v2 structure. And eachcomponent hasan external dynamic circui twatchdog thatis set for computing supervision and switching.Figure2Hardware structureof SIC3.3ﻩStandardized component unitAfter component module is made certain, according tothe safety-criticalrequirements ofrailwaysigna linterlocking system, we haveto do a secondarydevelopment on the module.The design includes powersupply,interfaces and other embedded circuits.The fault-tolerant processing, synchronizedcomputing, and fault diagnosisof SIC mostlydepend on the safetysoftware.Here the safety softwaredesign methodis differingfrom that of the special computer too.For dedicatedcomputer,the software is o ftenspecially designed basedon the barehardware. Asrestricted by computing ability and application object, a special scheduling program is commonly designedas safetysoftware for the computer, and not a universaloperating system.The fault-tolerant processingand faultdiagnosisof the dedicated computer are tightlyhardware-coupled. However, the safety softwar efor SIC is exoteric and loosely hardware-coupled, and itis basedon a standard Linux OS.Thesafety softwareis vitalelementof secondary development. ItincludesLinux OS adjustment, fail-safe process, fault-tolerance management,and safety inte rlocking logic. Thehierarchyrelations between themareshown inFigure 4.Safety Interlock LogicFail-safe processFault-tolerance managementLinux OS adjustmentFigure 4Safety softwarehierarchy of SIC 3.4Fault-tolerant model and safetycomputation3.4.1Fault-tolerant modelTheFault-tolerantcomputation of SICis of a m ultilevelmodel:SIC=F1002D(F2002(S c11,S c12),F2002(Sc21,S c22)) Firstly, basic computing unitCi1 adopts one algorithm to completethe S Ci1,and Ci2 finishes the SCi2via adifferent algorithm, secondly2 out of2(2oo2)safety computing componentofSIC executes2oo2calculation and gets F SICi from the calculation results of S Ci1 S Ci2, and thirdly,according the states of watchdog andswi tch unit block, the result of SICis gotten via a1out of 2 with diagnostics(1oo2D)calculation, whichis ba sed onF SIC1 and FSIC2.The flow of calculations isas follows:(1) S ci1=F ci1(D net1,Dnet2,D di,D fss)(2)S ci2=F ci2(D net1,D net2,D di,Dfss)(3)F SICi=F2oo2(S ci1,Sci2 ),(i=1,2)(4)SIC_OutPut=F1oo2D(FSIC1,F SIC2)3.4.2 SafetycomputationAs interlocking system consists ofa fixed set of task, the computational modelof SIC is task-based. In general, applicationsmay conform to a time-triggered,event-triggered or mixedcomputational model.Here the time-triggered modeisselected, tasks are executed cyclically.The consistencyof computing states between the two unitsis the foundation of SICfor ensuring safety a nd credibility. AsSIC worksunder a loosely c oupled mode, itis different fromthat of dedicated hard ware-coupled computer.So a specialized synchronization al gorithmis necessaryforSIC.SICcan be consideredasa multiprocessordistributed system,and itscomputationalmodel is essentially basedon data comparing via high bus communication.First,ananalyticalapproach is usedto confirm theworst-case response time of eachtask. Toguarantee thedeadlineof tasks that communicate across the network,the accesstimeanddelayof communication medium is setto a fixed possiblevalue. Moreover, the computational model must meets the real time requirements of railway interlockingsystem, withinthesystem computing cycle, we set many check points P i (i=1,2,... n) , whichare smallenoughfor synchronization, an d c omputat io n resul t vot in g is exe cuted at each p oin t. The safe ty computa ti on flow of SI C i s shown i n F igu re 5.S t a r tclockclockS a f e t y f u n c t i o n s T a s k s o f i n t e r l o c k i n g l o g i c i :p:c h e c k p o i n t I n i t i a l i z e S y n c h r o n i z a t i o n G u a r a n t e e S y n c h r o n o u s T i m e t r i g g e rFigur e 5 S afet y comp utat io nal model of S IC4. Hardware saf ety integrity l evel evaluat ion4.1 S afety Int egri tyAs an auth oritat ive intern ational stand ard f orsafety-related sy st em, IE C 61508 p resents a defi nit ion of sa fe ty integr ity : pro bab il ity of a safety-related sys tem satisfac tori ly perf or ming the req uir ed safe ty functions un der all the stated condi tions within a stat ed perio d o f ti me . In IEC 61508, there ar e four lev els ofsafety integrityareprescribe, SIL1~SIL4. The SIL1is the lowest,and SIL4 highest.Accordingto IEC61508, the SICbelongstosafety-relatedsystems in high demand or continuous mode of operation. The SIL of SIC can be evaluated viatheprobability of dangerous per hour. The provision of SIL aboutsuch system in IEC61508,see table 1.Table1-SafetyIntegrity levels: targetfailure measures for asafety function operating inhigh demand orcontinuous mode of operationSafety Int egrity level High demandor continuous modeof Operation(Probability of a dangerous Failureper hour)4≥10-9to <10-83 ≥10-8 to<10-72 ≥10-7to <10-61≥10-6to <10-54.2 Reliability blockdiagram ofSICAfteranalyzing the structure and working principle o fthe SIC, weget the bock diagramof reliability,as figure 6.Figure 6 Block diagram of SIC reliability5.ConclusionsInthispaper, weproposed anavailable standardizedcomponent-based computerSIC.Railway signal interlocking isa fail-safe system with arequired probabilit yof lessthan 10-9 safetycritical failures perhour.In orderto meet the critical constraints, fault-t olerantarchitecture and safety tactics are usedin SIC. Although the computational model andimplementationtechniquesare rather complex, the philosophyof SICprovides acheerfulprospect to safety critical applications,it renders in asimpler style of hardware, furthermore, itcan shorten developmentcycle and reduce cost.SIC has been put into practical applica tion,and highperformance of reliabilityand safetyhasbeen proven. ………………………………………………………………………………………………………From:模块化安全铁路信号计算机联锁系统1概述信号联锁系统是保证交通安全、提高铁路运输效率的关键设备。
PLC控制系统英文文献+翻译
PLC控制系统英文文献+翻译PLC控制系统英文文献+翻译Beer filling, Gland machine PLC control system 1.Intorduction Malt beer production process is divided into manufacturing, manufacturing wort, before fermentation, after fermentation, filtration sterilization, packaging, and so few procedures. Beer filling, Gland part of a packaging machine processes. The membrane filtration of beer after the pipeline into the rotary Jiugang, then the valve into the bottle of wine, Gland, was bottled beer. Beer filling, Gland machine's efficiency and degree of automation direct impact on the level of beer production.China's beer industry to meet the increasing scale of production and the demand for beer modern high-speed filling machinery filling the requirements of domestic beer manufacturers are actively seeking to transform the unit or the filling of beer production equipment, making it a good use Performance, advanced technology and high production efficiency and operating a safe and secure, low maintenance costs of the modernization of beer filling machine. 2. Filling beer, Gland principle and control aircraft partsLiquid filling machine by filling principle can be divided into atmospheric filler,filling machines and vacuum pressure on the filling machine. Beer filling,Gland-filling method used pressure is higher than the atmospheric pressure under the filling, storage of the cylinder pressure than the pressure of the bottle, beer bottle into the liquid on pressure.Technology at home and abroad to achieve the filling line is basically: The Rotary Jiugang the rotating movement, placed in Jiugang slots on the empty bottles through the machinery will befixed at the upper Jiugang vacuum valve to open, closed Vacuum bottles for good treatment, Bozhuan stem from operating, open the valve of the bottle filling CO2 gases, vacuum convex .Round to open the vacuum valve, the bottle will air mixed with CO2 out of gas, open the valve again, the CO2 gas bottle filling, the filling valve on the pressure valve in the bottle close to back-pressure gas pressure at the open-Jiuye Pingbi into the bottle, through pneumatic or electrical control filling valve to achieve the filling of beer.Today's advanced international beer filling, Gland machine control system mainly by the photoelectric switch position detection part and take the bottles with, Jiugang speed part, dominated by the PLC, touch screen and other components. Filling, Gland of the mechanical structure and PLC programmable control devices, frequency stepless speed regulation, human-computer interface, and other modern means of complete automatic control technology, the combination of a mechanical and electrical integration.3. Controlled part of the programmeMany domestic beer manufacturers are now using the filling, Gland of the control system of uneven degree of automation; button and all the manual switch technology have set up operations in a box on the panel, PLC controller for the majority of Japanese companies or OMRON Mitsubishi's early products, equipment chain of control, less protection settings, plus the beer filling the scene poor environment, humidity, such as contact with the switch contacts serious corrosion, the system's signal detection of the high failure rate, resulting in equipment control system Operation of low reliability, the normal operation of equipment, such as short-cycle phenomenon.To the actual transformation of the Dandong Yalu River Brewery Co., Ltd. of filling, Gland machine control system as an example, the transformation of methods to clarify the control of such equipment thinking and ideas, according to the scene of the actual process conditions, to prepare the operation of the PLC Procedures. For beer filling, Gland control system of the actual situation and in accordance with the actual process conditions at the scene, re-design of the equipment of the PLC control system. This transformation of the same methods and ideas can be applied to other liquids and the transformation of filling equipment. 3.1 system hardware configurationJapan's Mitsubishi Corporation to use the FX2N128MRPLC use the system to replace the original 2-OMRON's C60P PLC, the original system of the PLC is due to old models, and computer on-line communications need to configure special converters, the system need to increase the external I / O input points , The extension of spare parts more difficult to find. FX2N128MRPLC is an integrated 128-point I / O controller of the box, a computing speed, command rich, high-cost performance, on-line programming simple and easy extension of the advantages of the Mitsubishi FX series, features the strongest small controller .(1) by the Mitsubishi 900 series of 970 GOT human-computer touch screen system to replace the original use of the button panel display equipment and monitor the operation of operating parameters. 970GOT HMI for the 16-color high-brightness significantly, through the convergence of connectivity and FX2N128MRPLC directly connected to the CPU, achieving rapid response. Has many maintenance features, such as the list-editing features, ladder monitoring (troubleshooting) function, the system monitoring functions to find fault and maintenanceof PLC Systems.(2) filling, Gland of the frequency converter in the transformation of no replacement, on-site detection signal means-testing is still used switch, switch for detecting long-term work in the humidity of the great occasions, the choice of capacitive proximity switches, according to PLC I / O terminal of the connection mode, select the type of close PNP switch, the control system of Figure 1. 3.2 Systems Programming PLC controller programming focus and the core is around Jiugang the rotation speed control and Jiugang on 60 bottles of detecting the location of the displaced, broken bottles, empty bottles at the location of testing and related displacement filling Such as control valves. The bottles displacement of testing procedures, using a Mitsubishi PLC in the left command.Figure 1 control system structure diagram .Bottles displacement of detection, using the left-PLC command, which commands the whole of one of the core control procedures, the main electrical switch detection and bottles at the bottle simultaneously detect mobile, the main motor to every week, just to the corresponding Jiugang Have a bottle of, PLC unit within the internal correspondence that 60 bottles of the unit for the M500 ~ M559, the number of units by the first letter K is set to K60, with each change in a second letter K is set to K1, M50 Reaction of the empty bottles in the short position, and detect the location of the motor speed to go on the frequency shift in the corresponding unit within the built-in "1" or "0", control valves and the corresponding mixing caps The motor stopped and opened. Continuous detection system in place after the 90 empty bottles, stop stirring caps the motor running, testing the number of bottles in accordance with the user's requirements canbe arbitrary.A bottle of detection. Rotary Jiugang through pressure to back pressure with the bottle of liquor in the process of empty bottles in the back-pressure, because the bottle itself may crack and other reasons leading to a sudden burst bottles, which need to detect the location of unexploded bottle bottle, in this bottle - The position opened purge solenoid valves, compressed air out, broken bottles at the bottle-blowing from the position in a row after the purge and several bottles of the electromagnetic valve open jet, a high-pressure spray Shuizhu, in the break Bottle position around a few bottles of spray bottles in a row.Detection of broken bottles and bottle-detection switch simultaneously detect movement of breaking bottles, to the main motor of each week, precisely corresponding Jiugang passed a bottle of, PLC unit within the internal correspondence that 20 broken bottles at the unit for the M600 ~ M619, unit With the number of the first letter K is set to K20, with each change in a second letter K is set to K1, M52 response to the location of the broken bottles and detected the location of the motor speed to the frequency shift continue, In the corresponding unit within the built-in "1" or "0", control and the corresponding jet purge solenoid valve opened and stopped. Continuous Spray and purge solenoid valve open to listen, time stopped in accordance with technological requirements can be arbitrary.System security is to control access to the caps simultaneously tracking, not only accurately detect the electrical switching speed detection, the broken bottles into the bottle and detection switch detection switch three conditions.970GOT human-computer touch-screen terminals operated by the software company's Mitsubishi GT WORKS package, whichis a GT Designer with the entire GOT9000 series of graphics software packages. The package is simple, prior to a personal computer simulation on the configuration and debug, after the man-machine operators to download terminals. At the same time, because the man-machine interface and a touch-screen role, will set common switch on the screen to facilitate the operation. And also to increase the number of features, such as setting alarm information. 4.After transformation control systemSystem at the normal operation of the machine for automatic control, in accordance with bottles into and out of the bottle for lack or slow pace set by running into the bottle stall bottles, no less than a bottle cap, automatic washing bottles burst, filling automatic back-pressure position , Covered under the system automatically lose covered a stop and safety protection, such as the coordination of action interlock. All the original button after the operation of the touch screen on. 5.Detection of the state control system monitoringDetection switch into the bottle and break bottles detection switch bottles of pressure by testing each part of the small metal plates above the location of a photoelectric pulse output, a further PLC acquisition, as each bottle of the pressure above the small metal plates is the location of activities , In the machine running after some time, some pressure above the small bottles of iron tablets and detection switch in the location of displacement, resulting in detection switch mistaken judgement, if not for the judgement of bottles of bottles, bottle explosion Lou Jian, misuse, such as the seizure of output errors So that the PLC have mistaken action, such as a back-pressure, unexploded bottle blowing, washing, stirring cap control system malfunction, such as failure phenomenon.Before the transformation of the daily production process, encountered this phenomenon, the operatives could only switch to the various functional or manual control buttons reach the stall so that the equipment work in the absence of monitoring state, the machine lost control function. Caused a lot of production of raw materials such as gas, water, wine waste. Only in the production of intermittent, can be fitter and maintenance electrician in accordance with the detection of small switch on the light-emitting diodes and anti-displacement by adjusting the distance only 5 ~ 8 mm detection switch installation location, and switch to fix detection of small metal plates Gap. This means of detection is very backward, after adjustment reaction to the results, timely response can not be adjusted results.In view of this testing situation, after the transformation of the filling, Gland control system configuration, this part of a new detection and integration in human-computer touch screen, complete bottle of detection.In human-computer touch screen interface on the page display, respectively, at customs, such as electromagnetic motor mixing valve switch state are in different colors to show, very intuitive.Increase the system's functions is to ensure the irrigation of the machine-Gland normal operation of automated control system specifically designed to. 6 Concluding remarks After the transformation of the control system will greatly simplify the complicated mechanical structure, the running and control of inspection, the degree of automation systems meet the design requirements, greatly reducing the operational strength of the labor so that the shrub-like beer output than in the past Raising more than 30 percent, greatly reduce the failure rate.Embodies the modern equipment of automatic control technology. In the digestion and absorption of today's industrial control on the basis of advanced technology innovation, development of domestic technology from the most advanced filling control system.啤酒灌装、压盖机PLC控制系统1、引言啤酒生产过程分为麦芽制造、麦芽汁制造、前发酵、后发酵、过滤灭菌、包装等几道工序。
本科毕业论文内部控制外文文献翻译完整版中英对照
本科毕业论文内部控制外文文献翻译完整版中英对照A Clear Look at Internal Controls: Theory and ConceptsHammed Arad (Philae)Department of accounting, Islamic Azad University, Hamadan, IranBarak Jamshedy-NavidFaculty Member of Islamic Azad University, Kerman-shah, IranAbstract: internal control is an accounting procedure or system designed to promote efficiency or assure the implementation of a policy or safeguard assets or avoid fraud and error. Internal Control is a major part of managing an organization. It comprises the plans, methods, and procedures used to meet missions, goals, and objectives and, in doing so, support performance-based management. Internal Control which is equal with management control helps managers achieve desired results through effective stewardship of resources. Internal controls should reduce the risks associated with undetected errors or irregularities, but designing and establishing effective internal controls is not a simple task and cannot be accomplished through a short set of quick fixes. In this paper the concepts of internal controls and different aspects of internal controls are discussed. Keywords: Internal Control, management controls, Control Environment, Control Activities, Monitoring1. IntroductionThe necessity of control in new variable business environment is not latent for any person and management as a response factor for stockholders and another should implement a great control over his/her organization. Control is the activity of managing or exerting control over something. he emergence and development of systematic thoughts in recent decade required a new attention to business resource and control over this wealth. One of the hot topic a bout controls over business resource is analyzing the cost-benefit of each control.Internal Controls serve as the first line of defense in safeguarding assets and preventing and detecting errors and fraud. We can say Internal control is a whole system of controls financial and otherwise, established by the management for the smooth running of business; it includes internal cheek, internal audit and other forms of controls.COSO describe Internal Control as follow. Internal controls are the methods employed to help ensure the achievement of an objective. In accounting and organizational theory, Internal control is defined as a process effected by an organization's structure, work and authority flows, people and management information systems, designed to help the organization accomplish specific goals or objectives. It is a means by which an organization's resources are directed, monitored, and measured. It plays an important role in preventing and detecting fraud and protecting the organization's resources, both physical (e.g., machinery and property) and intangible (e.g., reputation or intellectual property such as trademarks). At the organizational level, internal control objectives relate to the reliability of financial reporting, timely feedback on the achievement of operational or strategic goals, and compliance with laws and regulations. At the specific transaction level, internal control refers to the actions taken to achieve a specific objective (e.g., how to ensure the organization's payments to third parties are for valid services rendered.) Internal controlprocedures reduce process variation, leading to more predictable outcomes. Internal controls within business entities are called also business controls. They are tools used by manager's everyday.* Writing procedures to encourage compliance, locking your office to discourage theft, and reviewing your monthly statement of account to verify transactions are common internal controls employed to achieve specific objectives.All managers use internal controls to help assure that their units operate according to plan, and the methods they use--policies, procedures, organizational design, and physical barriers-constitute. Internal control is a combination of the following:1. Financial controls, and2. Other controlsAccording to the institute of chartered accountants of India internal control is the plan of organization and all the methods and procedures adopted by the management of an entity to assist in achieving management objective of ensuring as far as possible the orderly and efficient conduct of its business including adherence to management policies, the safe guarding of assets prevention and detection of frauds and error the accuracy and completeness of the accounting records and timely preparation of reliable financial information, the system of internal control extends beyond those matters which relate to the function of accounting system. In other words internal control system of controls lay down by the management for the smooth running of the business for the accomplishment of its objects. These controls can be divided in two parts i.e. financial control and other controls.Financial controls:- Controls for recording accounting transactions properly.- Controls for proper safe guarding company assets like cash stock bank debtor etc- Early detection and prevention of errors and frauds.- Properly and timely preparation of financial records I e balance sheet and profit and loss account.- To maximize profit and minimize cost.Other controls: Other controls include the following:Quality controls.Control over raw materials.Control over finished products.Marketing control, etc6. Parties responsible for and affected by internal controlWhile all of an organization's people are an integral part of internal control, certain parties merit special mention. These include management, the board of directors (including the audit commit tee), internal auditors, and external auditors.The primary responsibility for the development and maintenance of internal control rests with an organization's management. With increased significance placed on the control environment, the focus of internal control has changed from policies and procedures to an overriding philosophy and operating style within the organization. Emphasis on these intangible aspects highlights the importance of top management's involvement in the internal control system. If internal control is not a priority for management, then it will not be one for people within the organization either.As an indication of management's responsibility, top management at a publicly owned organization will include in the organization's annual financial report to the shareholders a statement indicating that management has established a system of internal control that management believes is effective. The statement may also provide specific details about the organization's internal control system.Internal control must be evaluated in order to provide management with some assurance regarding its effectiveness. Internal control evaluation involves everything management does to control the organization in the effort to achieve its objectives. Internal control would be judged as effective if its components are present and function effectively for operations, financial reporting, and compliance. he boards of directors and its audit committee have responsibility for making sure the internal control system within the organization is adequate. This responsibility includes determining the extent to which internal controls are evaluated. Two parties involved in the evaluation of internal control are the organization's internal auditors and their external auditors.Internal auditors' responsibilities typically include ensuring the adequacy of the system of internal control, the reliability of data, and the efficient use of the organization's resources. Internal auditors identify control problems and develop solutions for improving and strengthening internal controls. Internal auditors are concerned with the entire range of an organization's internal controls, including operational, financial, and compliance controls.Internal control will also be evaluated by the external auditors. External auditors assess the effectiveness of internal control within an organization to plan the financial statement audit. In contrast to internal auditors, external auditors focus primarily on controls that affect financial reporting. External auditors have a responsibility to report internal control weaknesses (as well as reportable conditions about internal control) to the audit committee of the board of directors.8. Limitations of an Entity's Internal ControlInternal control, no matter how well designed and operated, can provide only reasonable assurance of achieving an entity's control objectives. The likelihood of achievement is affected by limitations inherent to internal control. These include the realities that human judgment in decision-making can be faulty and that breakdowns in internal control can occur because of human failures such as simple errors or mistakes. For example, errors may occur in designing,Maintaining, or monitoring automated controls. If an entity’s IT personnel do not completely understand how an order entry system processes sales transactions, they may erroneously design changes to the system to process sales for a new line of products. On the other hand, such changes may be correctly designed but misunderstood by individuals who translate the design into program code. Errors also may occur in the use of information produced by IT. For example, automated controls may be designed to report transactions over a specified dollar limit for management review, but individuals responsible for conducting the review may not understand the purpose of such reports and, accordingly, may fail to review them or investigate unusual items.Additionally, controls, whether manual or automated, can be circumvented by the collusion of two or more people or inappropriate management override of internal control. For example, management may enter into side agreements with customers that alter the terms and conditions of the entity’s standard sales con tract in ways that would preclude revenuerecognition. Also, edit routines in a software program that are designed to identify and report transactions that exceed specified credit limits may be overridden or disabled.Internal control is influenced by the quantitative and qualitative estimates and judgments made by management in evaluating the cost-benefit relationship of an entity’s internal control. The cost of an entity's internal control should not exceed the benefits that are expected to be derived. Although the cost-benefit relationship is a primary criterion that should be considered in designing internal control, the precise measurement of costs and benefits usually is not possible.Custom, culture, and the corporate governance system may inhibit fraud, but they are not absolute deterrents. An effective control environment, too, may help reduce the risk of fraud. For example, an effective board of directors, audit committee, and internal audit function may constrain improper conduct by management. Alternatively, the control environment may reduce the effectiveness of other components. For example, when the nature of management incentives increases the risk of material misstatement of financial statements, the effectiveness of control activities may be reduced.9. Balancing Risk and ControlRisk is the probability that an event or action will adversely affect the organization. The primary categories of risk are errors, omissions, delay and fraud In order to achieve goals and objectives, management needs to effectively balance risks and controls. Therefore, control procedures need to be developed so that they decrease risk to a level where management can accept the exposure to that risk. By performing this balancing act "reasonable assurance” can be attained. As it relates to financial and compliance goals, being out of balance can causebe proactive, value-added, and cost-effective and address exposure to risk.11. ConclusionThe concept of internal control and its aspects in any organization is so important, therefore understanding the components and standards of internal controls should be attend by management. Internal Control is a major part of managing an organization. Internal control is an accounting procedure or system designed to promote efficiency or assure the implementation of a policy or safeguard assets or avoid fraud and error. According to custom definition, Internal Control is a process affected by an entity's board of directors, management and other personnel designed to provide reasonable assurance regarding the achievement of objectives in the following categories namely. The major factors of internal control are Control environment, Risk assessment, Control activities, Information and communication, Monitoring. This article reviews the main standards and principles of internal control and described the relevant concepts of internal control for all type of company.内部控制透视:理论与概念哈米德阿拉德(Philae)会计系,伊斯兰阿扎德大学,哈马丹,伊朗巴克Joshed -纳维德哈尼学院会员伊斯兰阿扎德大学,克尔曼伊朗国王,伊朗摘要:内部控制是会计程序或控制系统,旨在促进效率或保证一个执行政策或保护资产或避免欺诈和错误。
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外文文献翻译20106995 工机2班吴一凡注:节选自Neural Network Introduction神经网络介绍,绪论。
HistoryThe history of artificial neural networks is filled with colorful, creative individuals from many different fields, many of whom struggled for decades to develop concepts that we now take for granted. This history has been documented by various authors. One particularly interesting book is Neurocomputing: Foundations of Research by John Anderson and Edward Rosenfeld. They have collected and edited a set of some 43 papers of special historical interest. Each paper is preceded by an introduction that puts the paper in historical perspective.Histories of some of the main neural network contributors are included at the beginning of various chapters throughout this text and will not be repeated here. However, it seems appropriate to give a brief overview, a sample of the major developments.At least two ingredients are necessary for the advancement of a technology: concept and implementation. First, one must have a concept, a way of thinking about a topic, some view of it that gives clarity not there before. This may involve a simple idea, or it may be more specific and include a mathematical description. To illustrate this point, consider the history of the heart. It was thought to be, at various times, the center of the soul or a source of heat. In the 17th century medical practitioners finally began to view the heart as a pump, and they designed experiments to study its pumping action. These experiments revolutionized our view of the circulatory system. Without the pump concept, an understanding of the heart was out of grasp.Concepts and their accompanying mathematics are not sufficient for a technology to mature unless there is some way to implement the system. For instance, the mathematics necessary for the reconstruction of images from computer-aided topography (CAT) scans was known many years before the availability of high-speed computers and efficient algorithms finally made it practical to implement a useful CAT system.The history of neural networks has progressed through both conceptual innovations and implementation developments. These advancements, however, seem to have occurred in fits and starts rather than by steady evolution.Some of the background work for the field of neural networks occurred in the late 19th and early 20th centuries. This consisted primarily of interdisciplinary work in physics, psychology and neurophysiology by such scientists as Hermann von Helmholtz, Ernst Much and Ivan Pavlov. This early work emphasized general theories of learning, vision, conditioning, etc.,and did not include specific mathematical models of neuron operation.The modern view of neural networks began in the 1940s with the work of Warren McCulloch and Walter Pitts [McPi43], who showed that networks of artificial neurons could, in principle, compute any arithmetic or logical function. Their work is often acknowledged as the origin of theneural network field.McCulloch and Pitts were followed by Donald Hebb [Hebb49], who proposed that classical conditioning (as discovered by Pavlov) is present because of the properties of individual neurons. He proposed a mechanism for learning in biological neurons.The first practical application of artificial neural networks came in the late 1950s, with the invention of the perception network and associated learning rule by Frank Rosenblatt [Rose58]. Rosenblatt and his colleagues built a perception network and demonstrated its ability to perform pattern recognition. This early success generated a great deal of interest in neural network research. Unfortunately, it was later shown that the basic perception network could solve only a limited class of problems. (See Chapter 4 for more on Rosenblatt and the perception learning rule.)At about the same time, Bernard Widrow and Ted Hoff [WiHo60] introduced a new learning algorithm and used it to train adaptive linear neural networks, which were similar in structure and capability to Rosenblatt’s perception. The Widrow Hoff learning rule is still in use today. (See Chapter 10 for more on Widrow-Hoff learning.) Unfortunately, both Rosenblatt's and Widrow's networks suffered from the same inherent limitations, which were widely publicized in a book by Marvin Minsky and Seymour Papert [MiPa69]. Rosenblatt and Widrow wereaware of these limitations and proposed new networks that would overcome them. However, they were not able to successfully modify their learning algorithms to train the more complex networks.Many people, influenced by Minsky and Papert, believed that further research on neural networks was a dead end. This, combined with the fact that there were no powerful digital computers on which to experiment,caused many researchers to leave the field. For a decade neural network research was largely suspended. Some important work, however, did continue during the 1970s. In 1972 Teuvo Kohonen [Koho72] and James Anderson [Ande72] independently and separately developed new neural networks that could act as memories. Stephen Grossberg [Gros76] was also very active during this period in the investigation of self-organizing networks.Interest in neural networks had faltered during the late 1960s because of the lack of new ideas and powerful computers with which to experiment. During the 1980s both of these impediments were overcome, and researchin neural networks increased dramatically. New personal computers and workstations, which rapidly grew in capability, became widely available. In addition, important new concepts were introduced.Two new concepts were most responsible for the rebirth of neural net works. The first was the use of statistical mechanics to explain the operation of a certain class of recurrent network, which could be used as an associative memory. This was described in a seminal paper by physicist John Hopfield [Hopf82].The second key development of the 1980s was the backpropagation algo rithm for training multilayer perceptron networks, which was discovered independently by several different researchers. The most influential publication of the backpropagation algorithm was by David Rumelhart and James McClelland [RuMc86]. This algorithm was the answer to the criticisms Minsky and Papert had made in the 1960s. (See Chapters 11 and 12 for a development of the backpropagation algorithm.)These new developments reinvigorated the field of neural networks. In the last ten years, thousands of papers have been written, and neural networks have found manyapplications. The field is buzzing with new theoretical and practical work. As noted below, it is not clear where all of this will lead US.The brief historical account given above is not intended to identify all of the major contributors, but is simply to give the reader some feel for how knowledge in the neural network field has progressed. As one might note, the progress has not always been "slow but sure." There have been periods of dramatic progress and periods when relatively little has been accomplished.Many of the advances in neural networks have had to do with new concepts, such as innovative architectures and training. Just as important has been the availability of powerful new computers on which to test these new concepts.Well, so much for the history of neural networks to this date. The real question is, "What will happen in the next ten to twenty years?" Will neural networks take a permanent place as a mathematical/engineering tool, or will they fade away as have so many promising technologies? At present, the answer seems to be that neural networks will not only have their day but will have a permanent place, not as a solution to every problem, but as a tool to be used in appropriate situations. In addition, remember that we still know very little about how the brain works. The most important advances in neural networks almost certainly lie in the future.Although it is difficult to predict the future success of neural networks, the large number and wide variety of applications of this new technology are very encouraging. The next section describes some of these applications.ApplicationsA recent newspaper article described the use of neural networks in literature research by Aston University. It stated that "the network can be taught to recognize individual writing styles, and the researchers used it to compare works attributed to Shakespeare and his contemporaries." A popular science television program recently documented the use of neural networks by an Italian research institute to test the purity of olive oil. These examples are indicative of the broad range of applications that can be found for neural networks. The applications are expanding because neural networks are good at solving problems, not just in engineering, science and mathematics, but m medicine, business, finance and literature as well. Their application to a wide variety ofproblems in many fields makes them very attractive. Also, faster computers and faster algorithms have made it possible to use neural networks to solve complex industrial problems that formerly required too much computation.The following note and Table of Neural Network Applications are reproduced here from the Neural Network Toolbox for MATLAB with the permission of the Math Works, Inc.The 1988 DARPA Neural Network Study [DARP88] lists various neural network applications, beginning with the adaptive channel equalizer in about 1984. This device, which is an outstanding commercial success, is a single-neuron network used in long distance telephone systems to stabilize voice signals. The DARPA report goes on to list other commercial applications, including a small word recognizer, a process monitor, a sonar classifier and a risk analysis system.Neural networks have been applied in many fields since the DARPA report was written. A list of some applications mentioned in the literature follows.AerospaceHigh performance aircraft autopilots, flight path simulations, aircraft control systems, autopilot enhancements, aircraft component simulations, aircraft component fault detectorsAutomotiveAutomobile automatic guidance systems, warranty activity analyzersBankingCheck and other document readers, credit application evaluatorsDefenseWeapon steering, target tracking, object discrimination, facial recognition, new kinds of sensors, sonar, radar and image signal processing including data compression, feature extraction and noise suppression, signal/image identificationElectronicsCode sequence prediction, integrated circuit chip layout, process control, chip failure analysis, machine vision, voice synthesis, nonlinear modelingEntertainmentAnimation, special effects, market forecastingFinancialReal estate appraisal, loan advisor, mortgage screening, corporate bond rating, credit line use analysis, portfolio trading program, corporate financial analysis, currency price predictionInsurancePolicy application evaluation, product optimizationManufacturingManufacturing process control, product design and analysis, process and machine diagnosis, real-time particle identification, visual quality inspection systems, beer testing, welding quality analysis, paper quality prediction, computer chip quality analysis, analysis of grinding operations, chemical product design analysis, machine maintenance analysis, project bidding, planning and management, dynamic modeling of chemical process systemsMedicalBreast cancer cell analysis, EEG and ECG analysis, prosthesis design, optimization of transplant times, hospital expense reduction, hospital quality improvement, emergency room test advisement0il and GasExplorationRoboticsTrajectory control, forklift robot, manipulator controllers, vision systemsSpeechSpeech recognition, speech compression, vowel classification, text to speech synthesisSecuritiesMarket analysis, automatic bond rating, stock trading advisory systemsTelecommunicationsImage and data compression, automated information services,real-time translation of spoken language, customer payment processing systemsTrans portationTruck brake diagnosis systems, vehicle scheduling, routing systemsConclusionThe number of neural network applications, the money that has been invested in neural network software and hardware, and the depth and breadth of interest in these devices have been growing rapidly.翻译:在人工神经网络的发展历程中,涌现了许多在不同领域中富有创造性的传奇人物,他们艰苦奋斗几十年,提出了许多至今仍然让我们受益的概念。