英文文献_科技类_原文及翻译_(电子_电气_自动化_通信)1

外文文献原稿和译文原稿Intelligent vehicle is a use of computer, sensor, information, communication, navigation, artificial intelligence and automatic control technology to realize the environment awareness, planning decision and automatic drive of high and new technology. It in aspects such as military, civil and scientific research has received application, to solve the traffic safety provides a new way.With the rapid development of automobile industry, the research about the car is becoming more and more attention by people. Contest of national competition and the province of electronic intelligent car almost every time this aspect of the topic, the national various universities are also attaches great importance to research on the topic, many countries have put the electronic design competition as a strategic means of innovative education. Electronic design involving multiple disciplines, machinery and electronics, sensor technology, automatic control technology, artificial intelligent control, computer and communication technology, etc., is a high-tech in the field of many. Electronic design technology, it is a national high-tech instance is one of the most important standard, its research significance is greatThe design though just a demo model, but is full of scientific and practical. First we according to the complex situation of road traffic, in accordance with the appropriate author to make a road model, including bend, straight and pavement set obstacles, etc. On curved and straight, the car along the orbit free exercise, when the small car meet obstacles, pulse modulation infrared sensors to detect the signal sent to the microcontroller, a corresponding control signal according to the program MCU control cars automatically avoid obstacles, to carry on the back, forward, turn left, turn rightSubject partsIntelligent vehicle is a concentration of environment awareness, planning decision, multi-scale auxiliary driving, and other functions in an integrated system, isan important part of intelligent transportation system. In military, civilian, space exploration and other fields has a broad application prospect. The design of smart car control system are studied, based on path planning is a process of the intelligent car control system2.1 theory is put forwardThe progress of science and technology of intelligent led products, but also accelerated the pace of development, MCU application scope of its application is increasingly wide, has gone far beyond the field of computer science. Small to toys, credit CARDS, big to the space shuttle, robots, from data acquisition, remote control and fuzzy control, intelligent systems with the human daily life, everywhere is dependent on the single chip microcomputer, this design is a typical application of single chip microcomputer. This design by implementing the driverless car, on the tests, by the reaction of the single chip microcomputer to control the car, make its become intelligent, automatic forward, turn and stop function, after continuing the perfection of this system also can be applied to road testing, security patrol, can meet the needs of society.In design, the use of the sensors to detect road surface condition, sensor central sea are faint and adopts a comparing amplifier amplification, and the signal input to the controller, the controlled end using stepper motor, because of the step motor is controlled electrical pulse, as long as the output from the controller to satisfy stepper motor merits of fixed control word. In operation of stepping motor and a driving circuit, it also to join a drive circuit in the circuit, each function module is different to the requirement of power supply current, the power supply part set up conversion circuit, so as to meet the needs of the various parts. After comparison choice element, design the circuit principle diagram and the circuit board, and do the debugging of hardware, system software and hardware is often the combination of organic whole. Software, on the use of the 51 single-chip timer interrupt to control pavement test interval and the car movement and speed. Due to take that road is simple, it is using more traditional assembly language for programming. For the correctness of the program design, using a commonly used keil c51 simulation software simulation validation, the last is integrated debugging of software and hardware, and prove thecorrectness and feasibility of the design scheme.2.2 electronic intelligent car design requirements(1) electric vehicles can be able to according to the course to run all the way; (2) electric vehicles can store and display the number of detected metal and sheet metal to the starting line in the distance; (3) are accurately electric cars after exercising all the way to the display of the electric vehicle the entire exercise time; (4) electric cars can't collisions with obstacles in the process of exercise.2.3 the general conception of computer network teaching websiteUsing 89 c51 as the car's control unit, sensor eight-way from outside, in the front of the car, as a black belt in the process of the car into the garage detecting element, at the rear end of the car when connected to eight-channel infrared sensors as the car pulled out of the garage of a black belt in detecting element, the LJ18A3-8 - Z/BX inductive proximity switch as garage iron detecting element, the microcontroller after receiving sensor detects the signal through the corresponding procedures to control the car forward, backward, turn, so that the car's performance indicators meet the requirements of the design.Intelligent car is a branch of intelligent vehicle research. It with the wheel as mobile mechanism, to realize the autonomous driving, so we call it the smart car. Smart car with the basic characteristics of the robot, easy to programming. It with remote control car the difference is that the latter requires the operator to control the steering, start-stop and in a more advanced remote control car can also control the speed (common model car belong to this type of remote control car); The smart car Is to be implemented by computer programming for the car stop, driving direction and speed control, without human intervention. Operator the smart car can be changed by a computer program or some data to change its drive type. This change can be controlled through programming, the characteristics of the car driving way is the biggest characteristic of smart car. The control system of smart car research purpose is to make the car driving with higher autonomy. If any given car a path, through the system, the car can get system for path after image processing of data moving and Angle (a), and can be scheduled path, according to the displacement and Angle information.The control system structure analysisAccording to the above design idea, the structure of the intelligent car control system can be divided into two layers1, the planning layerPC control system, the planning layer provides the information of the whole car driving, including path processing module and communication module. It has to solve the basic problem(1) using what tools to deal with the car path graph;(2) the car movement model is established, the data to calculate the car driving;(3) set up the car's motion model, the data to calculate the car driving;Layer 2, behaviorLower machine control system, the behavior is the underlying structure of a smart car control system, realize the real-time control of the car driving, it includes communication module, motor control module and data acquisition module. It to solve the basic problems are:(1) receiving, processing, PC sends data information;(2) the design of stepping motor control system;(3) information collection and the displacement and Angle of the car, car positioning posture, analysis system control error;The total design schemeSmart car control system are obtained by system structure, order process:(1) start AutoCAD, create or select a closed curve as the cart path, pick up the car starting $path graph(2) to choose the path of the graphics processing, make the car turning exist outside the minimum turning radius of edges and corners with circular arc transition(3) to generate a new path to simulate the motion process of car;(4) to calculate the displacement of the car driving need and wheel Angle, and then sends the data to the machine(5) under the machine after receiving data, through software programming control the rotation speed and Angle of the car wheels and make it according to the predetermined path A complete control system requirements closely linked to eachfunction module in the system, according to the order process and the relationship between them, the total design scheme of the system is available.Design of basically has the following several modulesPart 1, the information acquisition module, data collection is composed of photoelectric detection and operation amplifier module, photoelectric detection were tracing test and speed test of two parts. To detect the signal after budget amplifier module lm324 amplifier plastic to single chip, its core part is several photoelectric sensor.2, control processing module: control processing module is a stc89c52 MCU as the core, the microcontroller will be collected from the information after the judgement, in accordance with a predetermined algorithm processing, and the handling results to the motor drive and a liquid crystal display module, makes the corresponding action.3, perform module: executable module consists of liquid crystal display (LCD), motor drive and motor, buzzer of three parts. LCD is mainly based on the results of single chip real-time display, convenient and timely users understand the current state of the system, motor driver based on single chip microcomputer instruction for two motor movements, can according to need to make the corresponding acceleration, deceleration, turning, parking and other movements, in order to achieve the desired purpose. Buzzer is mainly according to the requirements in a particular position to make a response to the report.译文一、引言智能车辆是一个运用计算机、传感、信息、通信、导航、人工智能及自动控制等技术来实现环境感知、规划决策和自动行驶为一体的高新技术综合体。

1、外文原文A: Fundamentals of Single-chip MicrocomputerTh e si ng le -c hi p m ic ro co mp ut er i s t he c ul mi na ti on of both t h e de ve lo pm en t of the dig it al com pu te r an d th e in te gr at ed c i rc ui t arg ua bl y t h e tow m os t s ig ni f ic an t i nv en ti on s o f t he 20th c e nt ur y [1].Th es e tow type s of arch it ec tu re are foun d in sin g le -ch i p m i cr oc om pu te r. Som e empl oy the spli t prog ra m/da ta me mo ry of the H a rv ar d ar ch it ect u re , sh ow n in Fig.3-5A -1, oth ers fo ll ow the p h il os op hy , wi del y ada pt ed for gen er al -p ur po se com pu te rs and m i cr op ro ce ss o r s, o f ma ki ng no log i ca l di st in ct ion be tw ee n p r og ra m and dat a me mo ry as in the Pr in ce to n arch ite c tu re , show n i n Fig.3-5A-2.In gen er al ter ms a sin gl e -chi p mic ro co mp ut er i sc h ar ac te ri zed b y t he i nc or po ra ti on of a ll t he un it s of a co mp uter i n to a sin gl e d ev i ce , as sho wn inFi g3-5A -3.Fig.3-5A-1 A Harvard typeFig.3-5A-2. A conventional Princeton computerFig3-5A-3. Principal features of a microcomputerRead only memory (ROM.R OM is usua ll y for the pe rm an ent,n o n-vo la ti le stor a ge of an app lic a ti on s pr og ra m .M an ym i cr oc om pu te rs and m are inte nd e d for high -v ol um e ap pl ic at ions a n d he nc e t h e eco n om ic al man uf act u re of th e de vic e s re qu ir es t h at t he cont en t s o f t he prog ra m me m or y be co mm it t ed perm a ne ntly d u ri ng the man ufa c tu re of ch ip s .Cl ea rl y, thi s im pl ie s a r i go ro us app ro ach to ROM cod e deve l op me nt sin ce cha ng es can not b e mad e afte r manu f a c tu re .Th is dev e lo pm en t proc ess may invo lv e e m ul at io n us in g aso ph is ti ca te d de ve lo pm en t sy ste m wit h a h a rd wa re emu la tio n cap ab il it y as w el l as the use o f po we rf ul s o ft wa re too ls.So me man uf act u re rs pro vi de add it io na l RO M opt i on s by i n cl ud in g in their ra n ge dev ic es wit h (or int en de d fo r use wit h u s er pro gr am ma ble me mo ry. Th e sim p le st of th es e is usu al ly d e vi ce whi ch can op er at e in a micro p ro ce ssor mod e by usi ng som e o f the inp ut /outp u t li ne s as an ad dr es s an d da ta b us fora c ce ss in g ex te rna l mem or y. Thi s t y pe of de vi ce can beh av ef u nc ti on al ly as th e sing le chip mi cr oc om pu te r from whi ch it is d e ri ve d al be it wit h re st ri ct ed I/O and a mod if ied ex te rn al c i rc ui t. The use of thes e d ev ic es is com mo n eve n in prod uc ti on c i rc ui ts wher e t he vo lu me does no tj us ti f y t h e d ev el o pm en t c osts o f c us to m o n -ch i p R OM [2];t he re c a n s ti ll bea s ignif i ca nt saving i n I /O and o th er c h ip s com pa re d to a conv en ti on al mi c ro pr oc es sor b a se d ci rc ui t. Mor e ex ac t re pl ace m en t fo r RO M dev i ce s ca n be o b ta in ed in th e fo rm of va ri an ts w it h 'p ig gy -b ack 'E P RO M(Er as ab le pro gr am ma bl e ROM s oc ke ts or dev ic e s with EPROM i n st ea d o f RO M 。

目录1译文 (1)2原文 (7)1参考文献译文绿色创想建筑商计划提供了节能解决方案与行业认可的新住房平均相比，绿色畅想建筑商计划旨在降低家用能源和水的想好，减少排放。

该项目创新性地结合了建筑科学和高品质的产品，在帮助建筑商和开发商建造舒适型住房的同时，降低房屋对环境的影响。

随着生活费用的不断上涨，悦来愈多的人开始考虑将环保技术纳入新住房当中。

与行业认可的新住房陪你冠军水瓶相比，依照GE绿色创想建筑商计划所建造的房屋每年客减少20%的能耗与室内用水量，并且使生活用气排放量减少20%。

对于一套面积为2500平方英尺的住房而言，该计划每年可使购房者减少600至1500美元的电费和水费。

自该计划于2007年5月启动以来，整个美国与加拿大的建筑商与开发商纷纷申请建造绿色创想式房屋，其中包括德州西斯顿峡谷们的社区开发商。

按照绿色畅想计划正在开发的首个峡谷么社区被称为Discovery Companies，预计将于2008年夏季开盘。

加拿大的Fi的零售税环保想象住房计划推出在2007年9月，GE加拿大与波尔多发展组织签订计划，决定在位于加拿大阿尔伯他省卡尔加里西部的社区Rocky View实施加拿大首个绿色创想建筑商计划。

这块地区60多年来，一直有当地的一个牧民家庭所有，长期以来除了放养家畜之外始终难以用于其他用途。

迫于地区发展的强大压力，这个家庭决定对这块土地进行开发。

当这家人了解到如何最邮箱的进行地产开发之后，开始认真考虑如何处理这篇土地。

其中，家庭价值、对环境的保护意识以及社区精神都称为了需要考虑的关键问题。

实施证明，将GE的绿色创想建筑商计划与波尔多发展组织的环境可持续发展战略相结合是非常成功的。

规划中的面积为1750英亩的混用型绿色创想建筑商和谐开发项目见那个进行客持续开发，其中包括关于有效实用土地的创新性环保计划。

竣工使，此开放项目将建筑起3500所住房和衣架保健中心、一个27洞国际高尔夫球场、一所学校和一篇商业用地。

英文参考文献原文复印件及译文专业：自动化08级1班姓名：学号：080412122指导教师：赵奇完成日期年月SCM theory and the minimum MCU AdventWith the development of automation technology and microelectronics technology, as well as the fieldbus technology becomes more mature, numerical control technology in the production process is applied more and more widely, on the site of the signal collection, transmission and data processing is put forward higher requirements.Intelligent transmitter is composed of sensor and microprocessor ( computer ) and the phase structure. It makes full use of the microprocessor computing and storage capacity, the sensor data processing, including the measurement signal processing (such as filtering, amplification, A/D conversion ), data display, automatic calibration and automatic compensation.The microprocessor is the core of intelligent transmitter. It can not only carry on the data computation, storage and data processing, but also through a feedback loop to adjust to the sensor, data acquisition to achieve the best. The microprocessor has a variety of software and hardware function, so it can complete the traditional transducer difficult task. So intelligent transmitter reduces sensor manufacturing difficulty, and largely improves the performance of the sensor lord. In addition, intelligent transmitter also has the following characteristics:1 with automatic compensation ability, through the software on the sensor's nonlinear, temperature drift, drift and automatic compensation.Self diagnosis, after power for the sensor to check all parts of self, the sensor is normal, and make judgments.Data processing is convenient and accurate, according to internal procedures, automatic data processing, such as statistical processing, removal of abnormal value.2 with two-way communication function. The microprocessor can receive and process the sensor data, can also be information feedback to the sensor, thus the process of measurement adjustment and control.The information can be stored and can be stored in memory, the characteristics of sensor data, configuration information and compensation characteristics.3 has a digital interface output function, the output of the digital signal conveniently and computer or field bus connectionThe difference between the transmitter and sensorIn editing software in the process of joining the watchdog circuit. Theapplication of watchdog circuit, so that the chip can be in no condition to realize continuous work. But there are still some problems:1the watchdog circuit at run-time, meaning, system error. 2circulation process error too many times, the watchdog can not effectively resolved3 in measurement and control system in the period of time in one-chip, computer peripheral devices such as a large amount of time, is not running, waiting for orders. In these cases, the hardware watchdog is to use a timer, to monitor the main program operation, that is to say in the main program of the operatio n process, we will in time to time before the timer is reset if the dead cycle, or PC pointers can't come back. Then time to time will make chip reset.SCM is the main computer components are integrated on a single chip microcomputer. It is a collection of counting and many interfaces in one microcontroller, is widely used in intelligent products and industrial automation, and51 SCM SCM is the most typical and the most representative one.Signal generator in the teaching, testing, monitoring and other fields have a very wide range of applications, but also with the modern electronic communications technology development, often requires high precision and adjustable frequency signal generator.The design of direct use A T89C51 SCM as an important component of the wave generator, coupled with clever software design and simple external circuit, a frequency, adjustable amplitude sine wave, triangle wave, sawtooth wave and Fang Bo and other signals. Signal frequency, amplitude, through the keyboard input directly, by the LED display. And various types of existing waveform generator comparison, ATMEL AT89C51 is a highly effective micro controller, which produces a small number of signal interference, output stability, high reliability, especially the simple and convenient operation, low cost, very suitable for teaching and experimental physics laboratory use.Microchip security, SCM and technology development department vice president Steve Drehobl said:" Microchip continuously expand 8microcontroller applications, creating a new generation of ultra compact flash memory device, using PIC MCU into non-traditional applications. These6pin device with high cost-effectiveness replaces the discrete logic or mechanical function, reduces the number of components and board space, also give engineers more design flexibility.The United States of America microchip technology company ( Microchip Technology ) recently launched the world 's smallest6 pin package chip ( MCU ), thePIC microcontroller architecture powerful functions into ultra small volume of the SOT-23 package, the single chip microcomputer application domain expands further, in some space is extremely limited and cost requirements for lower application field is expected to have a brilliant future.Traditional single chip market, MCU products can be used on a number of different fields, such as home appliances to the automotive, communications, office automation and industrial control. According to market analysis firm IC Insight global MCU market data,2003total sales of $10400000000, at $12200000000 in2004. Although each main MCU suppliers have already introduced 16bit,32 bit single chip, but the market is still used in most8 bit single chip microcomputer products, accounted for the overall market of about 40%. Therefore8 bits single chip computer still has large application market, mainly in such products in the ease of use, cost advantages, while performance can meet most of the needs of applications. This Steve Drehobl said:"8 bit single chip has the advantages of easy operation and use characteristics, design staff will soon be able to master the principles and methods of using8 bit single chip microcomputer; design cycle is short, design tool is more than 16,32design tool much cheaper; third, in reality, we are more according to what kind of application can produce what kind of performance to determine how many bits MCU used. If in those using8 bit single chip can meet the needs of the application, you must use 16 bit and 32 bit, from the function, more abundant, but the cost rise. Again, the current problems should not be ignored. If the excessive use of electric current, battery power consumption is relatively large单片机理论与最小MCU问世随着自动化技术的发展和微电子技术的进步，以及现场总线技术的日益成熟，数控技术在生产过程中的应用越来越广泛，对现场信号的采集、传输和数据处理提出更高的要求。

英文文献科技类原文及翻译1On the deployment of V oIP in Ethernet networks:methodology and case studyAbstractDeploying IP telephony or voice over IP (V oIP) is a major and challenging task for data network researchers and designers. This paper outlines guidelines and a step-by-step methodology on how V oIP can be deployed successfully. The methodology can be used to assess the support and readiness of an existing network. Prior to the purchase and deployment of V oIP equipment, the methodology predicts the number of V oIP calls that can be sustained by an existing network while satisfying QoS requirements of all network services and leaving adequate capacity for future growth. As a case study, we apply the methodology steps on a typical network of a small enterprise. We utilize both analysis and simulation to investigate throughput and delay bounds. Our analysis is based on queuing theory, and OPNET is used for simulation. Results obtained from analysis and simulation are in line and give a close match. In addition, the paper discusses many design and engineering issues. These issues include characteristics of V oIP traffic and QoS requirements, V oIP flow and call distribution, defining future growth capacity, and measurement and impact of background traffic. Keywords: Network Design，Network Management，V oIP，Performance Evaluation，Analysis，Simulation，OPNET1 IntroductionThese days a massive deployment of V oIP is taking place over data networks. Most of these networks are Ethernet based and running IP protocol. Many network managers are finding it very attractive and cost effective to merge and unify voice and data networks into one. It is easier to run, manage, and maintain. However, one has to keep in mind that IP networks are best-effort networks that were designed for non-real time applications. On the other hand, V oIP requires timely packet delivery with low latency, jitter, packet loss, andsufficient bandwidth. To achieve this goal, an efficient deployment of V oIP must ensure these real-time traffic requirements can be guaranteed over new or existing IP networks. When deploying a new network service such as V oIP over existing network, many network architects, managers, planners, designers, and engineers are faced with common strategic, and sometimes challenging, questions. What are the QoS requirements for V oIP? How will the new V oIP load impact the QoS for currently running network services and applications? Will my existing network support V oIP and satisfy the standardized QoS requirements? If so, how many V oIP calls can the network support before upgrading prematurely any part of the existing network hardware? These challenging questions have led to the development of some commercial tools for testing the performance of multimedia applications in data networks. A list of the available commercial tools that support V oIP is listed in [1,2]. For the most part, these tools use two common approaches in assessing the deployment of V oIP into the existing network. One approach is based on first performing network measurements and then predicting the network readiness for supporting V oIP. The prediction of the network readiness is based on assessing the health of network elements. The second approach is based on injecting real V oIP traffic into existing network and measuring the resulting delay, jitter, and loss. Other than the cost associated with the commercial tools, none of the commercial tools offer a comprehensive approach for successful V oIP deployment. I n particular, none gives any prediction for the total number of calls that can be supported by the network taking into account important design and engineering factors. These factors include V oIP flow and call distribution, future growth capacity, performance thresholds, impact of V oIP on existing network services and applications, and impact background traffic on V oIP. This paper attempts to address those important factors and layout a comprehensive methodology for a successful deployment of any multimedia application such as V oIP and video conferencing. However, the paper focuses on V oIP as the new service of interest to be deployed. The paper also contains many useful engineering and design guidelines, and discusses many practical issues pertaining to the deployment of V oIP. These issues include characteristics of V oIP traffic and QoS requirements, V oIP flow and call distribution, defining future growth capacity, and measurement and impact of background traffic. As a case study, we illustrate how ourapproach and guidelines can be applied to a typical network of a small enterprise. The rest of the paper is organized as follows. Section 2 presents a typical network topology of a small enterprise to be used as a case study for deploying V oIP. Section 3 outlines practical eight-step methodology to deploy successfully V oIP in data networks. Each step is described in considerable detail. Section 4 describes important design and engineering decisions to be made based on the analytic and simulation studies. Section 5 concludes the study and identifies future work.2 Existing network3 Step-by-step methodologyFig. 2 shows a flowchart of a methodology of eight steps for a successful V oIP deployment. The first four steps are independent and can be performed in parallel. Before embarking on the analysis and simulation study, in Steps 6 and 7, Step 5 must be carried out which requires any early and necessary redimensioning or modifications to the existing network. As shown, both Steps 6 and 7 can be done in parallel. The final step is pilot deployment.3.1. VoIP traffic characteristics, requirements, and assumptionsFor introducing a new network service such as V oIP, one has to characterize first the nature of its traffic, QoS requirements, and any additional components or devices. For simplicity, we assume a point-to-point conversation for all V oIP calls with no call conferencing. For deploying V oIP, a gatekeeper or Call Manager node has to be added to the network [3,4,5]. The gatekeeper node handles signaling for establishing, terminating, and authorizing connections of all V oIP calls. Also a V oIP gateway is required to handle external calls. A V oIP gateway is responsible for converting V oIP calls to/from the Public Switched Telephone Network (PSTN). As an engineering and design issue, the placement of these nodes in the network becomes crucial. We will tackle this issue in design step 5. Otherhardware requirements include a V oIP client terminal, which can be a separate V oIP device, i.e. IP phones, or a typical PC or workstation that is V oIP-enabled. A V oIP-enabled workstation runs V oIP software such as IP Soft Phones .Fig. 3 identifies the end-to-end V oIP components from sender to receiver [9]. The first component is the encoder which periodically samples the original voice signal and assigns a fixed number of bits to each sample, creating a constant bit rate stream. The traditional sample-based encoder G.711 uses Pulse Code Modulation (PCM) to generate 8-bit samples every 0.125 ms, leading to a data rate of 64 kbps . The packetizer follows the encoder and encapsulates a certain number of speech samples into packets and adds the RTP, UDP, IP, and Ethernet headers. The voice packets travel through the data network. An important component at the receiving end, is the playback buffer whose purpose is to absorb variations or jitter in delay and provide a smooth playout. Then packets are delivered to the depacketizer and eventually to the decoder which reconstructs the original voice signal. We will follow the widely adopted recommendations of H.323, G.711, and G.714 standards for V oIP QoS requirements.Table 1 compares some commonly used ITU-T standard codecs and the amount ofone-way delay that they impose. To account for upper limits and to meet desirable quality requirement according to ITU recommendation P.800, we will adopt G.711u codec standards for the required delay and bandwidth. G.711u yields around 4.4 MOS rating. MOS, Mean Opinion Score, is a commonly used V oIP performance metric given in a scale of 1–5, with 5 is the best. However, with little compromise to quality, it is possible to implement different ITU-T codecs that yield much less required bandwidth per call and relatively a bit higher, but acceptable, end-to-end delay. This can be accomplished by applying compression, silence suppression, packet loss concealment, queue management techniques, and encapsulating more than one voice packet into a single Ethernet frame.3.1.1. End-to-end delay for a single voice packetFig. 3 illustrates the sources of delay for a typical voice packet. The end-to-end delay is sometimes referred to by M2E or Mouth-to-Ear delay. G.714 imposes a maximum total one-way packet delay of 150 ms end-to-end for V oIP applications . In [22], a delay of up to 200 ms was considered to be acceptable. We can break this delay down into at least three different contributing components, which are as follows (i) encoding, compression, and packetization delay at the sender (ii) propagation, transmission and queuing delay in the network and (iii) buffering, decompression, depacketization, decoding, and playback delay at the receiver.3.1.2. Bandwidth for a single callThe required bandwidth for a single call, one direction, is 64 kbps. G.711 codec samples 20 ms of voice per packet. Therefore, 50 such packets need to be transmitted per second. Each packet contains 160 voice samples in order to give 8000 samples per second. Each packet is sent in one Ethernet frame. With every packet of size 160 bytes, headers of additional protocol layers are added. These headers include RTP+UDP+IP+Ethernet with preamble of sizes 12+8+20+26, respectively. Therefore, a total of 226 bytes, or 1808 bits, needs to be transmitted 50 times per second, or 90.4 kbps, in one direction. For both directions, the required bandwidth for a single call is 100 pps or 180.8 kbps assuming a symmetric flow.3.1.3. Other assumptionsThroughout our analysis and work, we assume voice calls are symmetric and no voice conferencing is implemented. We also ignore the signaling traffic generated by the gatekeeper. We base our analysis and design on the worst-case scenario for V oIP call traffic. The signaling traffic involving the gatekeeper is mostly generated prior to the establishment of the voice call and when the call is finished. This traffic is relatively small compared to the actual voice call traffic. In general, the gatekeeper generates no or very limited signaling traffic throughout the duration of the V oIP call for an already established on-going call. In this paper, we will implement no QoS mechanisms that can enhance the quality of packet delivery in IP networks.A myriad of QoS standards are available and can be enabled for network elements. QoS standards may i nclude IEEE 802.1p/Q, the IETF’s RSVP, and DiffServ.Analysis of implementation cost, complexity, management, and benefit must be weighed carefully before adopting such QoS standards. These standards can be recommended when the cost for upgrading some network elements is high and the network resources are scarce and heavily loaded.3.2. VoIP traffic flow and call distributionKnowing the current telephone call usage or volume of the enterprise is an important step for a successful V oIP deployment. Before embarking on further analysis or planning phases for a V oIP deployment, collecting statistics about of the present call volume and profiles is essential. Sources of such information are organization’s PBX, telephone records and bills. Key characteristics of existing calls can include the number of calls, number of concurrent calls, time, duration, etc. It is important to determine the locations of the call endpoints, i.e. the sources and destinations, as well as their corresponding path or flow. This will aid in identifying the call distribution and the calls made internally or externally. Call distribution must include percentage of calls within and outside of a floor, building, department, or organization. As a good capacity planning measure, it is recommended to base the V oIP call distribution on the busy hour traffic of phone calls for the busiest day of a week or a month. This will ensure support of the calls at all times with high QoS for all V oIP calls.When such current statistics are combined with the projected extra calls, we can predict the worst-case V oIP traffic load to be introduced to the existing network.Fig. 4 describes the call distribution for the enterprise under study based on the worst busy hour and the projected future growth of V oIP calls. In the figure, the call distribution is described as a probability tree. It is also possible to describe it as a probability matrix. Some important observations can be made about the voice traffic flow for inter-floor and external calls. For all these type of calls, the voice traffic has to be always routed through the router. This is so because Switchs 1 and 2 are layer 2 switches with VLANs configuration. One can observe that the traffic flow for inter-floor calls between Floors 1 and 2 imposes twice the load on Switch 1, as the traffic has to pass through the switch to the router and back to the switch again. Similarly, Switch 2 experiences twice the load for external calls from/to Floor 3.3.3. Define performance thresholds and growth capacityIn this step, we define the network performance thresholds or operational points for a number of important key network elements. These thresholds are to be considered when deploying the new service. The benefit is twofold. First, the requirements of the new service to be deployed are satisfied. Second, adding the new service leaves the network healthy and susceptible to future growth. Two important performance criteria are to be taken into account.First is the maximum tolerable end-to-end delay; and second is the utilization bounds or thresholds of network resources. The maximum tolerable end-to-end delay is determined by the most sensitive application to run on the network. In our case, it is 150 ms end-to-end for V oIP. It is imperative to note that if the network has certain delay sensitive applications, the delay for these applications should be monitored, when introducing V oIP traffic, such that they do not exceed their required maximum values. As for the utilization bounds for network resources, such bounds or thresholds are determined by factors such as current utilization, future plans, and foreseen growth of the network. Proper resource and capacity planning is crucial. Savvy network engineers must deploy new services with scalability in mind, and ascertain that the network will yield acceptable performance under heavy and peak loads, with no packet loss. V oIP requires almost no packet loss. In literature, 0.1–5% packet loss was generally asserted. However, in [24] the required V oIP packet loss was conservatively suggested to be less than 105 . A more practical packet loss, based on experimentation, of below 1% was required in [22]. Hence, it is extremely important not to utilize fully the network resources. As rule-of-thumb guideline for switched fast full-duplex Ethernet, the average utilization limit of links should be 190%, and for switched shared fast Ethernet, the average limit of links should be 85% [25]. The projected growth in users, network services, business, etc. must be all taken into consideration to extrapolate the required growth capacity or the future growth factor. In our study, we will ascertain that 25% of the available network capacity is reserved for future growth and expansion. For simplicity, we will apply this evenly to all network resources of the router, switches, and switched-Ethernet links. However, keep in mind this percentage in practice can be variable for each network resource and may depend on the current utilization and the required growth capacity. In our methodology, the reservation of this utilization of network resources is done upfront, before deploying the new service, and only the left-over capacity is used for investigating the network support of the new service to be deployed.3.4. Perform network measurementsIn order to characterize the existing network traffic load, utilization, and flow, networkmeasurements have to be performed. This is a crucial step as it can potentially affect results to be used in analytical study and simulation. There are a number of tools available commercially and noncommercially to perform network measurements. Popular open-source measurement tools include MRTG, STG, SNMPUtil, and GetIF [26]. A few examples of popular commercially measurement tools include HP OpenView, Cisco Netflow, Lucent VitalSuite, Patrol DashBoard, Omegon NetAlly, Avaya ExamiNet, NetIQ Vivinet Assessor, etc. Network measurements must be performed for network elements such as routers, switches, and links. Numerous types of measurements and statistics can be obtained using measurement tools. As a minimum, traffic rates in bits per second (bps) and packets per second (pps) must be measured for links directly connected to routers and switches. To get adequate assessment, network measurements have to be taken over a long period of time, at least 24-h period. Sometimes it is desirable to take measurements over several days or a week. One has to consider the worst-case scenario for network load or utilization in order to ensure good QoS at all times including peak hours. The peak hour is different from one network to another and it depends totally on the nature of business and the services provided by the network.Table 2 shows a summary of peak-hour utilization for traffic of links in both directions connected to the router and the two switches of the network topology of Fig. 1. These measured results will be used in our analysis and simulation study.外文文献译文以太网网络电话传送调度：方法论与案例分析摘要对网络数据研究者与设计师来说，IP电话或者语音IP电话调度是一项重大而艰巨的任务。

外文出处：Farhadi, A. (2008). Modeling, simulation, and reduction of conducted electromagnetic interference due to a pwm buck type switching power supply. Harmonics and Quality of Power, 2008. ICHQP 2008. 13th International Conference on, 1 - 6.Modeling, Simulation, and Reduction of Conducted Electromagnetic Interference Due to a PWM Buck Type Switching Power Supply IA. FarhadiAbstract:Undesired generation of radiated or conducted energy in electrical systems is called Electromagnetic Interference (EMI). High speed switching frequency in power electronics converters especially in switching power supplies improves efficiency but leads to EMI. Different kind of conducted interference, EMI regulations and conducted EMI measurement are introduced in this paper. Compliancy with national or international regulation is called Electromagnetic Compatibility (EMC). Power electronic systems producers must regard EMC. Modeling and simulation is the first step of EMC evaluation. EMI simulation results due to a PWM Buck type switching power supply are presented in this paper. To improve EMC, some techniques are introduced and their effectiveness proved by simulation.Index Terms:Conducted, EMC, EMI, LISN, Switching SupplyI. INTRODUCTIONFAST semiconductors make it possible to have high speed and high frequency switching in power electronics []1. High speed switching causes weight and volume reduction of equipment, but some unwanted effects such as radio frequency interference appeared []2. Compliance with electromagnetic compatibility (EMC) regulations is necessary for producers to present their products to the markets. It is important to take EMC aspects already in design phase []3. Modeling and simulation is the most effective tool to analyze EMC consideration before developing the products. A lot of the previous studies concerned the low frequency analysis of power electronics components []4[]5. Different types of power electronics converters are capable to be considered as source of EMI. They could propagate the EMI in both radiated and conducted forms. Line Impedance Stabilization Network (LISN) is required for measurement and calculation of conducted interference level []6. Interference spectrum at the output of LISN is introduced as the EMC evaluation criterion []7[]8. National or international regulations are the references forthe evaluation of equipment in point of view of EMC []7[]8.II. SOURCE, PATH AND VICTIM OF EMIUndesired voltage or current is called interference and their cause is called interference source. In this paper a high-speed switching power supply is the source of interference.Interference propagated by radiation in area around of an interference source or by conduction through common cabling or wiring connections. In this study conducted emission is considered only. Equipment such as computers, receivers, amplifiers, industrial controllers, etc that are exposed to interference corruption are called victims. The common connections of elements, source lines and cabling provide paths for conducted noise or interference. Electromagnetic conducted interference has two components as differential mode and common mode []9.A. Differential mode conducted interferenceThis mode is related to the noise that is imposed between different lines of a test circuit by a noise source. Related current path is shown in Fig. 1 []9. The interference source, path impedances, differential mode current and load impedance are also shown in Fig. 1.B. Common mode conducted interferenceCommon mode noise or interference could appear and impose between the lines, cables or connections and common ground. Any leakage current between load and common ground couldbe modeled by interference voltage source.Fig. 2 demonstrates the common mode interference source, common mode currents Iandcm1 and the related current paths[]9.The power electronics converters perform as noise source Icm2between lines of the supply network. In this study differential mode of conducted interference is particularly important and discussion will be continued considering this mode only.III. ELECTROMAGNETIC COMPATIBILITY REGULATIONS Application of electrical equipment especially static power electronic converters in different equipment is increasing more and more. As mentioned before, power electronics converters are considered as an important source of electromagnetic interference and have corrupting effects on the electric networks []2. High level of pollution resulting from various disturbances reduces the quality of power in electric networks. On the other side some residential, commercial and especially medical consumers are so sensitive to power system disturbances including voltage and frequency variations. The best solution to reduce corruption and improve power quality is complying national or international EMC regulations. CISPR, IEC, FCC and VDE are among the most famous organizations from Europe, USA and Germany who are responsible for determining and publishing the most important EMC regulations. IEC and VDE requirement and limitations on conducted emission are shown in Fig. 3 and Fig. 4 []7[]9.For different groups of consumers different classes of regulations could be complied. Class Afor common consumers and class B with more hard limitations for special consumers are separated in Fig. 3 and Fig. 4. Frequency range of limitation is different for IEC and VDE that are 150 kHz up to 30 MHz and 10 kHz up to 30 MHz respectively. Compliance of regulations is evaluated by comparison of measured or calculated conducted interference level in the mentioned frequency range with the stated requirements in regulations. In united European community compliance of regulation is mandatory and products must have certified label to show covering of requirements []8.IV. ELECTROMAGNETIC CONDUCTED INTERFERENCE MEASUREMENTA. Line Impedance Stabilization Network (LISN)1-Providing a low impedance path to transfer power from source to power electronics converter and load.2-Providing a low impedance path from interference source, here power electronics converter, to measurement port.Variation of LISN impedance versus frequency with the mentioned topology is presented inFig. 7. LISN has stabilized impedance in the range of conducted EMI measurement []7.Variation of level of signal at the output of LISN versus frequency is the spectrum of interference. The electromagnetic compatibility of a system can be evaluated by comparison of its interference spectrum with the standard limitations. The level of signal at the output of LISN in frequency range 10 kHz up to 30 MHz or 150 kHz up to 30 MHz is criterion of compatibility and should be under the standard limitations. In practical situations, the LISN output is connected to a spectrum analyzer and interference measurement is carried out. But for modeling and simulation purposes, the LISN output spectrum is calculated using appropriate software.基于压降型PWM开关电源的建模、仿真和减少传导性电磁干扰摘要：电子设备之中杂乱的辐射或者能量叫做电磁干扰(EMI)。

华北电力大学毕业设计（论文）附件外文文献翻译学号： 200701000324 姓名:杨曦所在院系：电力工程系专业班级：电气化0707指导教师：安勃原文标题： Research on Smart Grid in China2011年06月20日对中国智能电网的研究1摘要——智能电网是电力系统的未来发展的新方向。

在本文中，首先是智能电网的背景，意义，以及概念和结构。

典型的智能电网图如下所示.然后,在美国和欧洲智能电网的发展现状进行了描述，并对这些国家未来发展思路的趋势进行了总结和比较及分析。

此外，分析了中国智能电网发展的必要性，详细介绍了在目前与中国与有关项目，并对特高压电网和智能电网之间的的关系进行了讨论。

最后，对智能电网在未来在中国电网的潜在作用进行了展望和并为中国的智能电网发展指明新方向.索引词,智能电网，特高压电网，规划,经营，管理一导言随着世界经济全球化的推广,石油价格一直维持在一个上升的趋势。

还值得注意的是世界范围内的的能源供应短缺，对资源和环境的压力越来越大,同时，由于目前电网的低效率，在能源输送过程中损失了巨大的电力。

此外,由于不断增长的电力需求和用户对电力可靠性和质量日益增长的要求，电力工业正面临着前所未有的挑战和机遇。

因此，一个有环境友好,经济，高性能，低投资，安全性，可靠性和灵活性特点的的电力系统一直是电力工程师的目标。

尽管如此，基础设施和先进的仪表出现互联网更广泛地的使用加速了这个过程[1］。

自1990年以来随着分布式发电越来越多地使用，已经对对电网的强度提出更多的需求和要求［2][3]。

对于这些问题，为了找出最佳的解决方案，电力公司应接受新的思路，采用新技术，对现有的能源系统进行潜力挖掘，对技术和应用加以改进。

来自不同国家的学者和专家已经达成共识：未来电网的必须能够满足不同的需求及能源发电，高度市场化的电力交易的需求，由此可以满足客户的自我选择。

所有这些都将成为未来智能电网的发展方向。

Intelligent Power Supply英文With the rapid development of electronic technology, application field of electronic system is more and more extensive, electronic equipment, there are more and more people work with electronic equipment, life is increasingly close relationship. Any electronic equipment are inseparable from reliable power supply for power requirements, they more and more is also high. Electronic equipment miniaturized and low cost in the power of light and thin,small and efficient for development direction. The traditional transistors series adjustment manostat is continuous control linear manostat. This traditional manostat technology more mature, and there has been a large number of integrated linear manostat module, has the stable performance is good, output ripple voltage small, reliable operation, etc. But usually need are bulky and heavy industrial frequency transformer and bulk and weight are big filter.In the 1950s, NASA to miniaturization, light weight as the goal, for a rocket carrying the switch power development. In almost half a century of development process, switch power because of is small volume, light weight, high efficiency, wide range, voltage advantages in electric, control, computer, and many other areas of electronic equipment has been widely used. In the 1980s, a computer is made up of all of switch power supply, the first complete computer power generation. Throughout the 1990s, switching power supply in electronics,electrical equipment, into the rapid development. In addition, large scale integrated circuit technology, and the rapid development of switch power supply with a qualitative leap, raised high frequency power products of, miniaturization, modular tide.Power switch tube, PWM controller and high-frequency transformer is an indispensable part of the switch power supply. The traditional switch power supply is normally made by using high frequency power switch tube division and the pins, such as using PWM integrated controller UC3842 + MOSFET is domestic small power switch power supply, the design method of a more popularity.Since the 1970s, emerged in many function complete integrated control circuit, switch power supply circuit increasingly simplified, working frequency enhancesunceasingly, improving efficiency, and for power miniaturization provides the broad prospect. Three end off-line pulse width modulation monolithic integrated circuit TOP (Three switch Line) will Terminal Off with power switch MOSFET PWM controller one package together, has become the mainstream of switch power lC development. Adopt TOP switch lC design switch power, can make the circuitsimplified,volume further narrowing, cost also is decreased obviousiy.Monolithic switching power supply has the monolithic integrated, the minimalist peripheral circuit, best performance index, no work frequency transformer can constitute a significant advantage switching power supply, etc. American Pl (with) company in Power in the mid 1990s first launched the new high frequency switching Power supply chip, known as the "top switch Power", with low cost, simple circuit, higher efficiency. The first generation of products launched in 1994 represented TOP100/200 series, the second generation product is the TOPSwitch - debuted in 1997 П .The above products once appeared showed strong vitality and he greatly simplifies the design of 150W following switching power supply and the development of new products for the new job, also, high efficiency and low cost switch power supply promotion and popularization created good condition, which can be widely used in instrumentation, notebook computers, mobile phones, TV, VCD and DVD, perturbation VCR, mobile phone battery chargers, power amplifier and other fields, and form various miniaturization, density, on price can compete with the linear manostat AC/DC power transformation module.Switching power supply to integrated direction of future development will be the main trend, power density will more and more big, to process requirements will increasingly high. In semiconductor devices and magnetic materials, no new breakthrough technology progress before major might find it hard to achieve, technology innovation will focus on how to improve the efficiency and focus on reducing weight. Therefore, craft level will be in the position of power supply manufacturing higher in. In addition, the application of digital control IC is the future direction of the development of a switch power. This trust in DSP for speed and anti-interference technology unceasing enhancement. As for advanced control method, now the individual feels haven't seen practicability of the method appears particularly strong, perhaps with the popularity of digital control, and there are some new control theory into switching power supply.(1) The technology: with high frequency switching frequencies increase, switchconverter volume also decrease,power density has also been boosted, dynamic response improved. Small power DC - DC converter switch frequency will rise to MHz. But as the switch frequency unceasing enhancement, switch components and passive components loss increases, high-frequency parasitic parameters and high-frequency EMI and so on the new issues will also be caused．(2) Soft switching technologies: in order to improve the efficiency of non-linearity of various soft switch, commutation technical application and hygiene, representative of soft switch technology is passive and active soft switch technology, mainly including zero voltage switch/zero current switch (ZVS/ZCS) resonance, quasi resonant, zero voltage/zero current pulse width modulation technology (ZVS/ZCS - PWM) and zero voltage transition/zero current transition pulse width modulation (PWM) ZVT/ZCT - technical, etc. By means of soft switch technology can effectively reduce switch loss and switch stress, help converter transformation efficiency.(3) Power factor correction technology (IC simplifies PFC). At present mainly divided into IC simplifies PFC technology passive and active IC simplifies PFC technology using IC simplifies PFC technology two kinds big, IG simplifies PFC technology can improve AC - DC change device input power factor, reduce the harmonic pollution of power grid.(4) Modular technology. Modular technology can meet the needs of the distributed power system, enhance the system reliability.(5) Low output voltage technology. With the continuous development of semiconductor manufacturing technology, microprocessor and portable electronic devices work more and more low, this requires future DC - DG converter can provide low output voltage to adapt microprocessor and power supply requirement of portable electronic devicesPeople in switching power supply technical fields are edge developing related power electronics device, the side of frequency conversion technology, development of switch between mutual promotion push switch power supply with more than two year growth toward light, digital small, thin, low noise and high reliability, anti-interference direction. Switching power supply can be divided into the AC/DC and DC/DC two kinds big, also have AC/AC DC/AC as inverter DC/DC converter is now realize modular, and design technology and production process at home and abroad, are mature and standardization, and has approved by users, but the AC/DC modular, because of its own characteristics in the process of making modular, meetmore complex technology and craft manufacture problems. The following two types of switch power supply respectively on the structure and properties of this.Switching power supply is the development direction of high frequency, high reliability, low consumption, low noise, anti-jamming and modular. Because light switch power, small, thin key techniques are changed, so high overseas each big switch power supply manufacturer are devoted to the development of new high intelligent synchronous rectifier, especially the improvement of secondary devices of the device, and power loss of Zn ferrite (Mn) material? By increasing scientific and technological innovation, to enhance in high frequency and larger magnetic flux density (Bs) can get high magnetic under the miniaturization of, and capacitor is a key technology. SMT technology application makes switching power supply has made considerable progress, both sides in the circuit board to ensure that decorate components of switch power supply light, small, thin. The high frequency switching power supply of the traditional PWM must innovate switch technology, to realize the ZCS ZVS, soft switch technology has become the mainstream of switch power supply technical, and greatly improve the efficiency of switch power. For high reliability index, America's switch power producers, reduce by lowering operating current measures such as junction temperature of the device, in order to reduce stress the reliability of products made greatly increased．Modularity is of the general development of switch power supply trend can be modular power component distributed power system, can be designed to N + 1 redundant system, and realize the capacity expansion parallel. According to switch power running large noise this one defect, if separate the pursuit of high frequency noise will increase its with the partial resonance, and transform circuit technology, high frequency can be realized in theory and can reduce the noise, but part of the practical application of resonant conversion technology still have a technical problem, so in this area still need to carry out a lot of work, in order to make the technology to practional utilization.Power electronic technology unceasing innovation, switch power supply industry has broad prospects for development. To speed up the development of switch power industry in China, we must walk speed of technological innovation road, combination with Chinese characteristics in the joint development path, for the high-speed development of national economy to make the contribution.中文智能开关电源随着电子技术的高速发展，电子系统的应用领域越来越广泛，电子设备的种类也越来越多，电子设备与人们的工作、生活的关系口益密切。

电气工程的外文文献(及翻译)文献一：Electric power consumption prediction model based on grey theory optimized by genetic algorithms本文介绍了一种基于混合灰色理论与遗传算法优化的电力消耗预测模型。

该模型使用时间序列数据来建立模型，并使用灰色理论来解决数据的不确定性问题。

通过遗传算法的优化，模型能够更好地预测电力消耗，并取得了优异的预测结果。

此模型可以在大规模电力网络中使用，并具有较高的可行性和可靠性。

文献二：Intelligent control for energy-efficient operation of electric motors本文研究了一种智能控制方法，用于电动机的节能运行。

该方法提供了一种更高效的控制策略，使电动机能够在不同负载条件下以较低的功率运行。

该智能控制使用模糊逻辑方法来确定最佳的控制参数，并使用遗传算法来优化参数。

实验结果表明，该智能控制方法可以显著降低电动机的能耗，节省电能。

文献三：Fault diagnosis system for power transformers based on dissolved gas analysis本文介绍了一种基于溶解气体分析的电力变压器故障诊断系统。

通过对变压器油中的气体样品进行分析，可以检测和诊断变压器内部存在的故障类型。

该系统使用人工神经网络模型来对气体分析数据进行处理和分类。

实验结果表明，该系统可以准确地检测和诊断变压器的故障，并有助于实现有效的维护和管理。

文献四：Power quality improvement using series active filter based on iterative learning control technique本文研究了一种基于迭代研究控制技术的串联有源滤波器用于电能质量改善的方法。

英文文献科技类原文及翻译（电子电气自动化通信…）74ArticleCreating a Debugging and Profiling Agent with JVMTIArticles IndexThe Java Virtual Machine Tool Interface (JVMTI) provides a programming interface that allowsyou, the software developer, to create software agents that can monitor and control your Javaprogramming language applications. JVMTI is new in the Java 2 Software Development Kit(SDK), Standard Edition, version 1.5.0. It replaces the Java Virtual Machine Profiling Interface(JVMPI), which had been included as an experimental feature of the Java 2 SDK since version1.1. JVMTI is described in JSR-163.This article illustrates how to use JVMTI to create a debugging and profiling tool for Java applications. Such a tool, also called an agent, uses the functionality exposed by the interfaceto register for notification of events as they occur in the application, and to query and controlthe application. JVMTI documentation is available here. A JVMTIagent can be useful for debugging and tuning an application. It can illustrate aspects of the application, such asmemory allocation, CPU utilization, and lock contention.Even though JVMPI is experimental, it is being used by many Java technology developers, and inseveral commercially-available Java application profilers. Pleasenote that developers are strongly encouraged to use JVMTI instead of JVMPI. JVMPI will be discontinued in the very near future.JVMTI improves upon the functionality and performance of JVMPI in many ways. For example:JVMTI relies on a callback for each event. This is more efficientthan the JVMPI design of usingevent structures, which needed to be marshalled and unmarshalled.JVMTI contains four times as many functions as JVMPI (including many more functions toobtain information about variables, fields, methods, and classes).For a complete index of the JVMTIfunctions, see the Function Index page.JVMTI provides notification for more types of events than does JVMPI, including exceptionevents, field access and modification events, and breakpoint and single-step events.Some of the JVMPI events that were never fully utilized, such as arena new and delete, or thatcan be better obtained through bytecode instrumentation, or the JVMTI functions themselves, (suchas heap dump and object allocation) have been dropped. A description of the events is available atthe Event Index page.JVMTI is capability-based, whereas JVMPI was "all or nothing" with corresponding performance impact.JVMPI heap functionality did not scale.JVMPI had no error return information.JVMPI was deeply invasive on VM implementations with resulting maintenance issues andperformance impacts.JVMPI is experimental and will be discontinued very soon.In the remainder of this article, we present a simple agent that uses JVMTI functions to extractinformation from a Java application. The agent must be written in native code. The sampleagent shown here is written in the C programming language. You can download the complete sample agent code here. The following paragraphs describe how an agent is initialized, andhow the agent uses JVMTI functions to extract information about a Java application, as well ashow to compile and run the agent. The sample code and compilation steps are specific toUNIX environments, but can be modified for use with Windows. Theagent described here can be used to analyze the threads and to determine JVM memory usage in any Java application.A simple program written in the Java programming language, called SimpleThread.java, is included and can be downloaded here. We use ThreadSample.java to demonstrate the expected output from the agent.The functionality of JVMTI is much more extensive than we can detail here, but the codein this article should provide a starting place for developing profiling tools to meet your ownspecific needs.Agent InitializationThis section describes the code that is used to initialize the agent. To begin with, the agent must include the jvmti.h file with the statement: #include <jvmti.h>.In addition, the agent must contain a function called Agent_OnLoad, which is invoked when the library is loaded. The Agent_OnLoad functionis used to set up functionality that is1required prior to initializing the Java virtual machine (JVM). The Agent_OnLoad signature looks like this:JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {.../* We return JNI_OK to signify success */return JNI_OK;}In our sample code, we must enable several capabilities for theJVMTI functions andevents that we will be using. It is generally desired, and in some cases required, to add these capabilities in the Agent_OnLoad function. The capabilities necessary for each function orevent are described in the Java Virtual Machine Tool Interface pages. For example, to use the InterruptThread function, the can_signal_thread capability must be true. We set all of the capabilities needed for our sample code to true, and then add them to the JVMTI environment using the AddCapabilities function:static jvmtiEnv *jvmti = NULL;static jvmtiCapabilities capa;jvmtiError error;...(void)memset(&capa, 0, sizeof(jvmtiCapabilities));capa.can_signal_thread = 1;capa.can_get_owned_monitor_info = 1;capa.can_generate_method_entry_events = 1;capa.can_generate_exception_events = 1;capa.can_generate_vm_object_alloc_events = 1;capa.can_tag_objects = 1;error = (*jvmti)->AddCapabilities(jvmti, &capa);check_jvmti_error(jvmti, error, "Unable to get necessary JVMTIcapabilities.");...In addition, the Agent_OnLoad function is often used to register for notification of events. Inour sample code, we enable several events, such as VM Initialization Event, VM Death Event, andVM Object Allocation, in Agent_OnLoad with the SetEventNotificationMode function as follows:error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, (jthread)NULL);error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, JVMTI_EVENT_VM_DEATH, (jthread)NULL);error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, JVMTI_EVENT_VM_OBJECT_ALLOC, (jthread)NULL);check_jvmti_error(jvmti, error, "Cannot set event notification");...Note that in our example, NULL is passed as the third parameter, which enables the eventnotification globally. If desired, some events can be enabled or disabled for a particular thread.Each event for which we register must also have a designatedcallback function, which willbe called when the event occurs. For example, if a JVMTI Event oftype Exception occurs, our example agent sends it to the callback method, callbackException().This is done using the jvmtiEventCallbacks structure and SetEventCallbacks function:jvmtiEventCallbacks callbacks;...(void)memset(&callbacks, 0, sizeof(callbacks));callbacks.VMInit = &callbackVMInit; /* JVMTI_EVENT_VM_INIT */callbacks.VMDeath = &callbackVMDeath; /* JVMTI_EVENT_VM_DEATH */callbacks.Exception = &callbackException;/* JVMTI_EVENT_EXCEPTION */ callbacks.VMObjectAlloc = &callbackVMObjectAlloc;/*JVMTI_EVENT_VM_OBJECT_ALLOC */error = (*jvmti)->SetEventCallbacks(jvmti,&callbacks,(jint)sizeof(callbacks));check_jvmti_error(jvmti, error, "Cannot set jvmti callbacks");We also set up a global agent data area for use throughout our code. /* Global agent data structure */typedef struct {/* JVMTI Environment */jvmtiEnv *jvmti;jboolean vm_is_started;/* Data access Lock */jrawMonitorID lock;} GlobalAgentData;static GlobalAgentData *gdata;In the Agent_OnLoad function, we perform the following setup:/* Setup initial global agent data area* Use of static/extern data should be handled carefully here. * We need to make sure that we are able to cleanup after * ourselves so anything allocated in this library needs to be * freed in theAgent_OnUnload() function.*/static GlobalAgentData data;(void)memset((void*)&data, 0, sizeof(data));gdata = &data;/* Here we save the jvmtiEnv* for Agent_OnUnload(). */ gdata->jvmti = jvmti;...We create a raw monitor in Agent_OnLoad(), then wrap the code ofVM_INIT, VM_DEATH and EXCEPTION with JVMTI RawMonitorEnter() and RawMonitorExit() interfaces. /* Here we create a raw monitor for our use in this agent to* protect critical sections of code. */error = (*jvmti)->CreateRawMonitor(jvmti, "agent data", &(gdata->lock));/* Enter a critical section by doing a JVMTI Raw Monitor Enter */ static voidenter_critical_section(jvmtiEnv *jvmti){ jvmtiError error;error = (*jvmti)->RawMonitorEnter(jvmti, gdata->lock);check_jvmti_error(jvmti, error, "Cannot enter with raw monitor");}/* Exit a critical section by doing a JVMTI Raw Monitor Exit */static voidexit_critical_section(jvmtiEnv *jvmti){ jvmtiError error;error = (*jvmti)->RawMonitorExit(jvmti, gdata->lock);check_jvmti_error(jvmti, error, "Cannot exit with raw monitor");}Agent_OnUnload will be called by the VM when the agent is about tobe unloaded. Thisfunction is used to clean-up resources allocated during Agent_OnLoad. /* Agent_OnUnload: This is called immediately before the shared library * is unloaded. This is the last code executed.*/JNIEXPORT void JNICALL Agent_OnUnload(JavaVM *vm){/* Make sure all malloc/calloc/strdup space is freed */}Analyzing Threads Using JVMTIThis section describes how to obtain information about user threads running in the JVM. Aswe have discussed, when the JVM is started, the startup function Agent_OnLoad in the JVMTIJVMTI_EVENT_VM_INIT is generated and sent to the callbackVMInit routine in our agent code. agent library is invoked. During VM initialization, a JVMTI Event of type Once the VM initialization event is received (that is, the VMInit callback is invoked), the agent can complete its initialization. Now, the agent is free to call any Java Native Interface (JNI) orJVMTI function. At this time, we are in the live phase and we will enable the Exception events(JVMTI_EVENT_EXCEPTION) in this VMInit callback routine. error = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE, JVMTI_EVENT_EXCEPTION, (jthread)NULL);Exception events are generated whenever an exception is first detected in a Javaprogramming language method. The exception may have beenthrown by a Java programminglanguage or native method, but in the case of native methods, the event is not generated until theexception is first seen by a Java programming language method. If an exception is set and clearedin a native method, no exception event is generated.For the purpose of demonstration, the sample Java application used is shown below. Themain thread creates five threads, each of which throws an exception before exiting. Once theJVM is started, a JVMTI_EVENT_VM_INIT is generated and sent to the agent code forprocessing, as we have enabled VMInit and Exception events in our agent code. Later, when our Java thread throws an exception, aJVMTI_EVENT_EXCEPTION is sent to the agent code. The agent code then analyzes the thread information, and displays the current thread name, the thread group it belongs to, monitors owned by this thread, thread state, thread stack trace,and all the user threads in the JVM.public class SimpleThread {static MyThread t;public static void main(String args[]) throws Throwable{t = new MyThread();System.out.println("Creating and running 10 threads...");for(int i = 0; i < 5; i++) {Thread thr = new Thread(t,"MyThread"+i);thr.start();try {thr.join();} catch (Throwable t) {}}}}class MyThread implements Runnable {Thread t;public MyThread() {}public void run() {/* NO-OP */try {"a".getBytes("ASCII");throwException();Thread.sleep(1000);} catch (ng.InterruptedException e){e.printStackTrace();} catch (Throwable t) {}}public void throwException() throws Throwable{throw new Exception("Thread Exception from MyThread"); }}Let us take a look at the JVMTI agent code that is executed when an exception is thrown inside a Java application.throw new Exception("Thread Exception from MyThread");A JVMTI exception event is generated and sent to the Exception callback routine in our agent code. The agent must add the capability can_generate_exception_events to enable the exception event. We use the JVMTI GetMethodName interface to display the method name and signature of the routine from which the exception was generated.err3 = (*jvmti)->GetMethodName(jvmti, method, &name, &sig, &gsig);printf("Exception in Method:%s%s\n", name, sig);We use the JVMTI GetThreadInfo and GetThreadGroupInfo interfaces to display the current thread and group details.err = (*jvmti)->GetThreadInfo(jvmti, thr, &info);if (err == JVMTI_ERROR_NONE) {err1 = (*jvmti)->GetThreadGroupInfo(jvmti,info.thread_group,&groupInfo);...if ((err == JVMTI_ERROR_NONE) && (err1 == JVMTI_ERROR_NONE )){printf("Got Exception event, Current Thread is : %s and Thread Group is: %s\n",((==NULL) ? "": ), );}}This causes the following to be output on your terminal:Got Exception event, Current Thread is : MyThread0 and Thread Group is: mainWe can get information about the monitors owned by the specified thread by using the JVMTI GetOwnedMonitorInfo interface. This function does not require the thread to besuspended.err = (*jvmti)->GetOwnedMonitorInfo(jvmti, thr, νm_monitors,&arr_monitors);printf("Number of Monitors returned : %d\n", num_monitors);We can get state information for a thread using the JVMTI GetThreadState interface. The thread state can be one of the following values:Thread has been TerminatedThread is AliveThread is runnableThread sleepingThread is waiting for NotificationThread is in Object WaitThread is in NativeThread is SuspendedThread is Interruptederr = (*jvmti)->GetThreadState(jvmti, thr, &thr_st_ptr);if ( thr_st_ptr & JVMTI_THREAD_STATE_RUNNABLE ) {printf("Thread: %s is Runnable\n", ((==NULL) ? "" :));flag = 1;}Displaying All User Threads in the JVM Using JVMTIThe JVMTI function GetAllThreads is used to display all live threads known to the JVM. Thethreads are Java programming language threads attached to the VM. The following code illustrates this:/* Get All Threads */err = (*jvmti)->GetAllThreads(jvmti, &thr_count, &thr_ptr); if(err != JVMTI_ERROR_NONE) {printf("(GetAllThreads) Error expected: %d, got: %d\n",JVMTI_ERROR_NONE, err);describe(err);printf("\n");}if (err == JVMTI_ERROR_NONE && thr_count >= 1) {int i = 0;printf("Thread Count: %d\n", thr_count);for ( i=0; i < thr_count; i++) {/* Make sure the stack variables are garbage free */(void)memset(&info1,0, sizeof(info1));err1 = (*jvmti)->GetThreadInfo(jvmti, thr_ptr[i], &info1);if (err1 != JVMTI_ERROR_NONE) {printf("(GetThreadInfo) Error expected: %d, got: %d\n",JVMTI_ERROR_NONE, err1);describe(err1);printf("\n");}printf("Running Thread#%d: %s, Priority: %d, context class loader:%s\n",i+1,,info1.priority,(info1.context_class_loader == NULL ? ": NULL" : "Not Null"));/* Every string allocated by JVMTI needs to be freed */ err2 =(*jvmti)->Deallocate(jvmti, (void*));if (err2 != JVMTI_ERROR_NONE) {printf("(GetThreadInfo) Error expected: %d, got: %d\n",JVMTI_ERROR_NONE, err2);describe(err2);printf("\n");}}}This causes the following to be output on your terminal:Thread Count: 5Running Thread#1: MyThread4, Priority: 5, context class loader:Not NullRunning Thread#2: Signal Dispatcher, Priority: 10, context class loader:NotNullRunning Thread#3: Finalizer, Priority: 8, context class loader:: NULL Running Thread#4: Reference Handler, Priority: 10, context class loader:: NULLRunning Thread#5: main, Priority: 5, context class loader:Not Null Obtaining a JVM Thread StacktraceThe JVMTI interface GetStackTrace can be used to get information about the stack of athread. If max_count is less than the depth of the stack, themax_count number of deepest frames are returned, otherwise the entire stack is returned. The thread need not be suspendedto call this function.The following example causes up to five of the deepest frames to be returned. If there areany frames, the currently executing method name is also printed./* Get Stack Trace */err = (*jvmti)->GetStackTrace(jvmti, thr, 0, 5, &frames, &count);if (err != JVMTI_ERROR_NONE) {printf("(GetThreadInfo) Error expected: %d, got: %d\n",JVMTI_ERROR_NONE, err);describe(err);printf("\n");}printf("Number of records filled: %d\n", count);if (err == JVMTI_ERROR_NONE && count >=1) {char *methodName;methodName = "yet_to_call()";char *declaringClassName;jclass declaring_class;int i=0;printf("Exception Stack Trace\n");printf("=====================\n");printf("Stack Trace Depth: %d\n", count);for ( i=0; i < count; i++) {err = (*jvmti)->GetMethodName(jvmti, frames[i].method, &methodName, NULL, NULL);if (err == JVMTI_ERROR_NONE) {err = (*jvmti)->GetMethodDeclaringClass(jvmti,frames[i].method, &declaring_class);err = (*jvmti)->GetClassSignature(jvmti, declaring_class, &declaringClassName, NULL);if (err == JVMTI_ERROR_NONE) {printf("at method %s() in class %s\n", methodName, declaringClassName);}}}This causes the following to be output on your terminal: Number of records filled: 3Thread Stack Trace=====================Stack Trace Depth: 3at method throwException() in class LmyThread; at method run() in class LMyThread;at method run() in class Ljava/lang/Thread;Analyzing the Heap Using JVMTIThis section describes the portion of the sample code thatillustrates how to obtaininformation about heap usage. For example, we have registered for VM Object Allocationevents as described in the section titled "Agent Initialization". This will notify us when the JVMhas allocated an object that is visible to the Java programming language, and which is notdetectable by other instrumentation mechanisms. This is an important difference from JVMPI,which sent an event when any object was allocated. In JVMTI, no event is sent foruser-allocated objects, since it is expected that bytecode instrumentation can be used instead.For example, in the SimpleThread.java program, we will not be notified of the allocation ofMyThread or Thread objects. An article demonstrating the use of bytecode instrumentation to obtain this information will be published separately.The VM Object Allocation event is useful for determining information about objectsallocated by the JVM. In the Agent_OnLoad method, we registered callbackVMObjectAllocas the function to be called when the VM Object Allocation event was sent. The callbackfunction parameters contain information about the object that has been allocated, such as theJNI local reference to the class of the object and the object size. With the jclass parameter, object_klass, we can use the GetClassSignature function to obtain information about the name of the class. We can print the object class and its size as shown below. Note that toavoid excessive output, we only print information about objects that are greater than 50 bytes./* Callback function for VM Object Allocation events */static void JNICALL callbackVMObjectAlloc(jvmtiEnv *jvmti_env, JNIEnv* jni_env, jthread thread,jobject object, jclass object_klass, jlong size) {...char *className;...if (size > 50) {err = (*jvmti)->GetClassSignature(jvmti, object_klass, &className, NULL);if (className != NULL) {printf("\ntype %s object allocated with size %d\n", className, (jint)size);}...We use the GetStackTrace method as described above to print thestack trace of the thread that is allocating the object. As that section describes, we obtain frames to a specified depth. The frames are returned as jvmtiFrameInfo structures, which contain each frame's jmethodID (that is, frames[x].method). The GetMethodName functioncan map the jmethodID to that particular method's name. Finally, in this example, we also use the GetMethodDeclaringClass and GetClassSignature functions to obtain the name of the class from which the method was called.char *methodName;char *declaringClassName;jclass declaring_class;jvmtiError err;//print stack tracejvmtiFrameInfo frames[5];jint count;int i;err = (*jvmti)->GetStackTrace(jvmti, NULL, 0, 5, &frames, &count);if (err == JVMTI_ERROR_NONE && count >= 1) {for (i = 0; i < count; i++) {err = (*jvmti)->GetMethodName(jvmti, frames[i].method, &methodName, NULL, NULL);if (err == JVMTI_ERROR_NONE) {err = (*jvmti)->GetMethodDeclaringClass(jvmti, frames[i].method,&declaring_class);err = (*jvmti)->GetClassSignature(jvmti, declaring_class,&declaringClassName, NULL);if (err == JVMTI_ERROR_NONE) {printf("at method %s in class %s\n", methodName, declaringClassName);}}}}...Note that memory allocated to the char arrays by these functions should be freed when weare finished with them:err = (*jvmti)->Deallocate(jvmti, (void*)className);err = (*jvmti)->Deallocate(jvmti, (void*)methodName);err = (*jvmti)->Deallocate(jvmti, (void*)declaringClassName);...The output from this code will look like this:type Ljava/lang/reflect/Constructor; object allocated with size 64at method getDeclaredConstructors0 in class Ljava/lang/Class; at method privateGetDeclaredConstructors in class Ljava/lang/Class; at method getConstructor0 in class Ljava/lang/Class; at method getDeclaredConstructor in class Ljava/lang/Class; at method run in class Ljava/util/zip/ZipFile$1;The returned name for primitive classes is the type signature character of the correspondingprimitive type. For example, ng.Integer.TYPE is "I". In our callback method for VM Object Allocation, we also use the IterateOverObjectsReachableFromObject function to demonstrate how we can obtainadditional information about the heap. In our example, we pass as a parameter the JNIreference to the object that was just allocated, and the functionwill iterate over all objects thatare directly and indirectly reachable from this newly allocated object. For each object that isreachable, another callback function is defined which can describe that reachable object. Inour example, the callback function passed to the IterateOverObjectsReachableFromObject function is calledreference_object:err = (*jvmti)->IterateOverObjectsReachableFromObject(jvmti, object, &reference_object, NULL);if ( err != JVMTI_ERROR_NONE ) {printf("Cannot iterate over reachable objects\n");}...The reference_object function is defined as follows:/* JVMTI callback function. */static jvmtiIterationControl JNICALLreference_object(jvmtiObjectReferenceKind reference_kind,jlong class_tag, jlong size, jlong* tag_ptr,jlong referrer_tag, jint referrer_index, void *user_data) {...return JVMTI_ITERATION_CONTINUE;}...In our example, we use the IterateOverObjectsReachableFromObject function to calculate both the combined size of all objects reachable from the newly allocated objects, as wellas what types of objects they are. The object type is determinedfrom the reference_kindparameter. We then print this information to receive output similar to the following: This object has references to objects of combined size 21232 This includes 45 classes, 9 fields, 1 arrays, 0 classloaders, 0 signers arrays, 0 protection domains, 19 interfaces, 13 static fields, and 2 constant pools.Note that similar iteration functions available in JVMTI allow youto iterate over the entireheap (both reachable and unreachable objects), over the root objects and all objects that aredirectly and indirectly reachable from the root objects, or over all objects in the heap that areinstances of a specified class. The technique for these functions is similar to that describedpreviously. During the execution of these functions, the state ofthe heap does not change: noobjects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threadsattempting to resume the execution of Java programming language code, and threads attempting toexecute JNI functions, are typically stalled. In the objectreference callback functions, no JNIfunctions can be used, and no JVMTI functions can be used exceptthose which are specificallyallowed.Compiling and Executing the Sample CodeTo compile and run the code for the sample application described here, do the following:1. Set JDK_PATH to point to the J2SE 1.5 distribution.JDK_PATH="/home/xyz/j2sdk1.5.0/bin"2.3. Build the shared library using the C compiler. We used Sun Studio 8 C compiler.CC="/net/compilers/S1Studio_8.0/SUNWspro/bin/cc"echo "...creating liba.so"${CC} -G -KPIC -o liba.so-I${JDK_PATH}/include -I${JDK_PATH}/include/solaris a.c4.5. To load and run the agent library, you can use one of thefollowing command-line argumentsduring VM startup.-agentlib:<jvmti-agent-library-name>-agentpath:/home/foo/jvmti/<jvmti-agent-library-name> 6. and thenyou can run the sample Java application as follows:echo "...creating SimpleThread.class"${JDK_PATH}/bin/javac -g -d . SimpleThread.javaecho "...running SimpleThread.class"LD_LIBRARY_PATH=. CLASSPATH=. ${JDK_PATH}/bin/java -showversion -agentlib:aSimpleThread7.Note: The sample agent code was built and tested on Solaris 9 Operating System. ConclusionIn this article we demonstrated some of the interfaces that JVMTI provides for monitoring andmanagement of the JVM. The JVMTI specification (JSR-163) is intended to provide a VMinterface for the full breadth of tools that need access to VM state, including but not limited to: profiling, debugging, monitoring, thread analysis, and coverage analysis tools. Developers are advised not to use JVMPI interfaces to develop tools or debuggingutilities, as JVMPI is unsupported and experimental technology.JVMTI should beconsidered for writing any profiling and managing tools for Java virtual machines.See Also。