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毕业设计(论文)外文资料翻译学院(系)：计算机科学与工程专业：计算机科学与技术姓名：杨玉婷学号：120602127外文出处：[1]Jérôme Vouillon,Vincent Balat.From bytecode to JavaScript: the Js_of_ocaml compiler[J].Softw.Pract.Exper.,2014,44（8）:Pages 951-955附件：1.外文资料翻译译文；2.外文原文。

1.外文翻译译文：总结：我们目前从OCaml字节码编译器的设计与实现JavaScript。

编译器首先将字节码转换为静态单赋值的中间表示上进行优化，在生成的JavaScript。

我们相信，以字节而不是一个高层次的语言输入是一个明智的选择。

虚拟机提供了一个非常稳定的原料药。

这样的编译器是很容易维护的。

它也方便使用，它可以添加到现有的开发工具的安装。

已经编译好的库可以直接使用，无需重新安装任何东西，最后，一些虚拟机是几种语言的目标。

字节码编译为JavaScript可以重新审视所有这些语言的Web浏览器一次。

1。

简介我们提出了一个编译器将字节码转换为JavaScript OCaml[1][2]。

这个编译器可以交互式Web应用程序客户端在ocaml.javascript是唯一的语言，很容易在大多数Web浏览器和浏览器的API提供了直接访问。

（其他平台，如Flash 和Silverlight，并没有广泛使用和集成。

）因此，强制性语言开发Web应用程序，它将能够使用各种Web浏览器上的JavaScript语言有趣：可适用于某些任务，但可以在其他语言其他情况下更合适。

特别是，能够使用相同的语言，无论是在浏览器和服务器，使它可以共享代码，并降低了语言之间的阻抗不匹配的两个层次。

例如，表单验证必须在服务器上进行，以提供安全的原因，并且在客户端上进行，以向用户提供早期反馈。

超声波加工中英文对照外文翻译文献

超声波加工中英文对照外文翻译文献超声波加工中英文对照外文翻译文献(文档含英文原文和中文翻译)超声波加工综述摘要超声波加工适合切削不导电、脆性材料，例如工程陶瓷。

与其他非传统加工，如激光束、电火花加工等不同，超声波加工不会导致工件表面热损伤或显著的残余应力，这对脆性材料尤其重要。

超声波加工的基本原理，包括材料去除原理，各类操作参数对材料切除率、刀具磨损、工件精确度要求都有叙述，并着重表述了在加工工程陶瓷上的应用，制造复杂的三维立体陶瓷的问题也在叙述当中。

1 概述超声波加工及其应用超声波加工是一种非传统机械切削技术，通常与低材料去除率有关，它并不被加工材料的导电率和化学特性所限制，它用于加工金属和非金属材料，非常适合于脆性大，硬度高于40HRC[6–12]的材料，比如无机玻璃、硅片、镍、钛合金等等 [13–24]，有了它，76um 的小孔也能加工，但是被加工的孔深度与直径之比限制在 3 比 1 之内 [8, 12]。

超声波加工的历史可以追溯到 1927 年，R. W. Wood 和 A. L. Loomis 发表的论文，1945年。

有关于超声波的第一项专利给了 L. Balamuth，现在超声波加工已经分化很多领域，超声波钻削、超声波切削、超声波尺寸加工、超声波研磨技术和悬浮液钻孔法，然而，在 20世纪 50 年代初只普遍知道超声波冲磨或 USM[8,25, 28, 30, 31]。

在超声波加工中，高频率的电能通过换能器/增幅器被转变为机械振动，之后通过一个能量集中装置被传送出去, 例如变幅杆/刀具组件[1, 17, 18, 30, 32]。

这导致刀具沿着其纵向轴线以振幅 0-50μm 高频率振动（通常≥20KHz）[16, 33, 34]，典型额定功率范围从50～3000W[35]不等，在某些机器上可以达到 4kw。

一个受控静负载被施加于刀具和磨料悬浮液（由研磨材料的混合物组成、例如碳化硅，碳化硼等等，悬浮在水或油中）被泵传送到切削区域，刀具的振动导致磨料颗粒悬浮在刀具和工件表面间，通过微型片冲击工件表面从而去除材料[19]。

外文翻译--反思模型应用于高等教育

毕业论文（设计）外文翻译A reﬂective essaying model for higher educationAbstractPurpose–The purpose of this paper is to outline a reﬂective essaying model as a useful way of encouraging learning in higher education. It aims to deﬁne reﬂective essaying as the fre e and serious play of mind on an interesting topic in an attempt to learn.Design/methodology/approach –Reﬂective essaying is ﬁrst introduced as a unifying concept in the model. Second, the model is introduced and justiﬁed especially in connection with De Montaigne’s invention of the essai as a process of trying out opinions and testing responses. Third, the role of teachers as essaying mentors is discussed. Fourth, mentoring for essaying is examined as a learning transaction which exempliﬁes Dewey’s trans actional theory of experience and knowing.Findings–Reﬂective essaying is promoted as an important way of letting students try to learn. Reﬂective mentors should promote student learning through reﬂective essaying which would encourage students to develop their own criticality.Practical implications– The paper has implications for both teachers and students. Teachers are urged to become more like mentors and less like didactic instructors. As mentors they should be encouraging students to see academic writing as trying out, as essaying, as experimenting with, and as learning through the ideas and materials they reﬂect upon..Originality/value–The paper is original in its approach in that it draws on a wide range of historical and contemporary sources on essaying in order to re-evaluate and resurrect essaying as an experimental process of learning.Keywords Teaching, Mentoring, Higher educationPaper type ViewpointTo be playful and serious at the same time is possible, and it deﬁnes the ideal mental condition. Absence of dogmatism and prejudice, presence of intellectual curiosity and ﬂexibility, are manifest in the free play of mind upon a topic (Dewey, 1991, p. 218).My idea of reﬂective essaying in higher education may be summarized as the free and serious play of mind on an interesting topic in an att empt to learn. This deﬁnition combines four major elements: the concept of academic freedom; the university as a (safe?) place for being free, serious and playful; the use of reﬂective thinking (“mind”) to help us (students and teachers) answer important questions; and the use of the essaying process as an attempt to learn. Reﬂective essaying is also in this sense an attempt at genuine contagious communication (Dewey, 1991, p. 224). What the school educator in Dewey wanted was the creation of a community of thought and purpose between students and society. But university educators should help students move beyond unreﬂective socialization towards a more critically reﬂective stage of individuation in order to become sceptical about the current consensus (Rorty, 1999).Also, where Dewey believed that a “pure interest in truth coincides with love of the free play of thought” (Dewey, 1991, p. 219), Rorty (1999, p. 117) argued that “if you take care of political, economic, cultural and academic freedom, then truth will take care of itself”. Where Dewey wanted a “community of thought and purpose” to promote a“narrative of freedom and hope” Rorty (1999 pp. 122-3) believed that universities should “remain bastions of academic freedom”. And what better way is there in higher education than by offering students and academics the freedom to write critically reﬂective essays about the issues which concern the communities and societies in which they live?In a forthcoming essay (Badley, 2009a) I argue that the university should be the best place for teachers to enact the freedom to speak and write and for students to learn their own ways of speaking and writing. The democratic university should provide as much free space as possible for students and teachers to try to develop their own sense of who they are and what their lives are for. In the rest of this paper I want, ﬁrst, to introduce and emphasize the idea of reﬂective essaying as a unifying concept in the overall model. Second, I brieﬂy outline a suggested model of reﬂective essaying and learning in higher education. Third, I consider the role of university educators asessaying mentors. And fourth, I discuss mentoring for essaying as an important learning transaction.Reﬂective essaying as a unifying conceptI use the term “essaying” rather than “essay writing” to emphasize the importance of the essay process rather than the essay form. It is the process of essaying – attempting to communicate knowing and understanding – which I propose as a valuable contribution to learning. Elsewhere I write about why we should also value the essay form (see Badley, 2009b). Indeed essays and essay writing are clearly at the heart of education (see, for example, Warburton, 2006). Further, writing in general is so central to the development of critical thinking in higher education (see Moon, 2008, p. 133) that reﬂective essaying should be taken more seriously.Essaying since De Montaigne –who invented the essai as a form –has been a process of trying out opinions and of testing responses to different subjects and situations (see Cohen, 1958). De Montaigne never meant his essaying to be exercises in especially skilful composition and development. Instead his ideas and judgements “merely grope their way forward, faltering, tripping, and stumbling” (see De Montaigne, 1580, pp. 47-50). As teachers we should, I think, also encourage students to try out and test their essaying as exercises in groping and stumbling since that is all any of us can seriously (and playfully) expect.Whilst the essay is u sually deﬁned as a short composition on any particular subject (Shorter Oxford Dictionary, n.d.) I stress essaying as attempting or trying out an exposition on a topic rather than, say, claiming a ﬁnal, deﬁnitive, analysis. Essaying includes arguing, describing, explaining and narrating and therefore overlaps with the production of articles, criticism, history, letters, reviews and reports (Kostelanetz, 1975). But it is not necessarily the case that essayists simply document what they know before they begin to write since they often discover or construct new thoughts in the course of the essaying process. Indeed reﬂective essaying is often a matter of interpreting our experiences as we write whilst reﬂexive essaying is where we interpret our previous reﬂections in different ways. Both reﬂectivity and reﬂexivity still relate t o A reﬂective essaying model 249experience. Reﬂective or reﬂexive essayists have to try to convince others that their (serious and playful) reﬂections are at least plausible.Also because essayists try to say something useful about a topic they also try to honour “theideals of clarity, accuracy, and force” (Kostelanetz, 1975, p. 2). They may even follow the classical form, after De Montaigne, in which a subject or thesis, echoing the essay’s title, is announced in the opening paragraph. There then follows a series of paragraphs which provide supporting arguments, illustrations, even digressions and anecdotes, as well as possible objections and refutations. Finally, the opening points are usually reiterated in the ﬁnal sentences (Kostelanetz, 1975).However, since De Montaigne, an open-ended approach to essaying has been developed which expresses a more conversational tone. Here “the author’s confusions remain as evident as his conclusions, while the reader must work harder than usual in drawing the necessary linkages and deﬁnitions” (Kostelanetz, 1975, p. 4). Many contemporary essayists, perhaps rejecting the academic value of objectivity, “emphasize authorial voice and informal tone” in order to achieve “the lucid, direct,orderly and vivid ﬂow of conversation, which conversation, itself interrupted and half-hearted, seldom attains” (Kostelanetz, 1975, p. 5). Further “what distinguishes the true essayist from the academic scholar is that the latter is enslaved to his circumscribed subject, while the essayist is inclined to let his mind roam free, his remarks typically tending to be more suggestive than exhaustive” (Kostelanetz, 1975,p. 6). The word “essay” implies not only “a libera l outlook” but also “a willingness to experiment” and most essays are written without consciousness of form (Kostelanetz, 1975). Indeed modern essaying may now be regarded as offering as many alternative forms of exposition and presentation as modern conceptual art (see the numerous examples in Kostelanetz, 1975). Further, “even exact scientists are writing with an ease and intimacy of conversational style that a generation ago would have led their scientiﬁc brethren to view them with suspicion” (Johnson, 1927, p. 12).My chief concern here is to regard reﬂective essaying as a unifying concept in university learning because it encourages writers – both novices and experts – to interpret their experiences as they write. These essayists become critically reﬂec tive learners when they “explore their experiences in order to lead to new understandings and appreciations” (Boud et al., 1985, p. 19). Indeed reﬂection may be summarized as a process of connecting and coordinating existing knowledge with new evidence (see Maclellan, 2004). Reﬂective essaying is critical reﬂection when it helps us transform what we already think we know into new knowledge. Reﬂective essaying allows us, affectively and cognitively, to inquire into our existing knowledge and pastexperience in order to gain new insights and understanding. Unfortunately, in her study of the academic essay, Maclellan found that “only a few scripts” showed evidence of critical reﬂection (Maclellan, 2004, p. 87).Reﬂective essaying in higher education: a suggested modelIn order to learn through writing reﬂective essays students need to be encouraged to see essaying as a series of inter-connecting processes rather than as a simple linear sequence. Students need to assemble material for their essays especially through reading but that reading also has to be a form of critical reﬂection where they engage with, deconstruct and critique the material rather than merely accept and reproduce it. Critically reﬂective r eading and de-constructing thereby contribute to reﬂective ET 51,4 250learning. It is not just a reiteration of existing knowledge but a critical and interpretive analysis of that knowledge. Reﬂective learning through reﬂective essaying may therefore be seen as the result of processing the complex issues of the material considered (see Moon, 2008, p. 128).Whilst students/writers are critically selecting and analysing their selected material they are also effectively beginning the process of reﬂective essay ing. This is where they try to construct their arguments in order to convince their actual or imagined audience of the usefulness or value of their approach and of the case they are making. Such essaying as construction is another overlapping episode of reﬂective learning.Within and then beyond this episode writers/students are also engaged in further reﬂection, re-construction and learning as they re-focus on their original material and on their de-constructed material. Re-construction is reﬂexive revisio n which is also reﬂexive re-learning.Reﬂective essayists also attempt to share their arguments and ideas with their audience by adapting what they have to say to what they believe or think is their audience’s main interest or concern. In this sense reﬂect ive essaying is also a form of co-constructing and further re-learning. It is also an attempt to offer the audience a more coherent, more integrated, more organised and even more transformed essay of arguments, ideas and suggestions.This process of reﬂect ive essaying and learning may be summarized as a series of emphases rather than as a set of stages. Each element in the process is itself a set of internal processes with which student-writers, operating effectively, engage in order to progress or even transform theirlearning. The model as outlined is not a linear sequence. Instead it is intended to emphasize reﬂective essaying as a series of dynamic,inter-connected yet layered internal processes of reﬂecting and learning.The model is based on a Deweyan view of learning from experience. The experience of reading and writing is an attempt to make connections, backwards and forwards (hence the arrows in Figure 1), between the texts read and the writing produced in order to consider the doubts, issues, problems and questions raised. Writing – essaying – then becomes a form of learning by doing, learning by trying, learning by experimenting, in order to set down what writers think they know and understand by the questions posed. Such writing helps writers cons truct or make “the connections of things”. Each piece of writing becomes an essay, an attempt, a try, to set down a plausible answer to a speciﬁc problem. Writers –novices or experts –may even manage to persuade others that their essay is an authentic individual attempt to write something useful about the topic under discussion (see Dewey, 1916; Badley, 2008译文：反思模型应用于高等教育摘要目的：本文的目的是勾勒出一个反思性文章模型作为一种有用的方式鼓励学习高等教育。

汽车电子毕设设计外文文献翻译(适用于毕业论文外文翻译+中英文对照)

Ultrasonic ranging system designPublication title: Sensor Review. Bradford: 1993.Vol.ABSTRACT: Ultrasonic ranging technology has wide using worth in many fields, such as the industrial locale, vehicle navigation and sonar engineering. Now it has been used in level measurement, self-guided autonomous vehicles, fieldwork robots automotive navigation, air and underwater target detection, identification, location and so on. So there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging system in hand, satisfy the request of the engineering personnel for the ranging precision, the bound and the usage, a portable ultrasonic ranging system based on the single chip processor was developed.Keywords: Ultrasound, Ranging System, Single Chip Processor1. IntroductiveWith the development of science and technology, the improvement of people’s standard of living, speeding up the development and construction of the city. Urban drainage system have greatly developed their situation is construction improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system.Co mfort is very important to people’s lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robots, the robot is designed to clear the culvert sewage to the core. Control system is the core component of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder.2. A principle of ultrasonic distance measurementThe application of AT89C51:SCM is a major piece of computer components are integrated into the chip micro-computer. It is a multi-interface and counting on the micro-controller integration, and intelligence products are widely used in industrial automation. and MCS-51 microcontroller is a typical and representative.Microcontrollers are used in a multitude of commercial applications such as modems, motor-control systems, air conditioner control systems, automotive engine and among others. The high processing speed and enhanced peripheral set of these microcontrollers make them suitable for such high-speed event-based applications. However, these critical application domains also require that these microcontrollers are highly reliable. The high reliability and low market risks can be ensured by a robust testing process and a proper tools environment for the validation of these microcontrollers both at the component and at the system level. Intel Plaform Engineering department developed an object-oriented multi-threaded test environment for the validation of its AT89C51 automotive microcontrollers. The goals of this environment was not only to provide a robust testing environment for the AT89C51 automotive microcontrollers, but to develop an environment which can be easily extended and reused for the validation of several other future microcontrollers. The environment was developed in conjunction with Microsoft Foundation Classes(AT89C51).1.1 Features* Compatible with MCS-51 Products* 2Kbytes of Reprogrammable Flash MemoryEndurance: 1,000Write/Erase Cycles* 2.7V to 6V Operating Range* Fully Static operation: 0Hz to 24MHz* Two-level program memory lock* 128x8-bit internal RAM* 15programmable I/O lines* Two 16-bit timer/counters* Six interrupt sources*Programmable serial UART channel* Direct LED drive output* On-chip analog comparator* Low power idle and power down modes1.2 DescriptionThe AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with 2Kbytes of flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51 instruction set and pinout. By combining a versatile 8-bit CPU with flash on a monolithic chip, the Atmel AT89C2051 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.The AT89C2051 provides the following standard features: 2Kbytes of flash,128bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator and clock circuitry. In addition, the AT89C2051 is designed with static logicfor operation down to zero frequency and supports two software selectable power saving modes. The idle mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The power down mode saves the RAM contents but freezer the oscillator disabling all other chip functions until the next hardware reset.1.3 Pin Configuration1.4 Pin DescriptionVCC Supply voltage.GND Ground.Prot 1Prot 1 is an 8-bit bidirectional I/O port. Port pins P1.2 to P1.7 provide internal pullups. P1.0 and P1.1 require external pullups. P1.0 and P1.1 also serve as the positive input (AIN0) and the negative input (AIN1), respectively, of the on-chip precision analog comparator. The port 1 output buffers can sink 20mA and can drive LED displays directly. When 1s are written to port 1 pins, they can be used as inputs. When pins P1.2 to P1.7 are used as input and are externally pulled low, they will source current (IIL) because of the internal pullups.Port 3Port 3 pins P3.0 to P3.5, P3.7 are seven bidirectional I/O pins with internal pullups. P3.6 is hard-wired as an input to the output of the on-chip comparator and is not accessible as a general purpose I/O pin. The port 3 output buffers can sink 20mA. When 1s are written to port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of various special features of the AT89C2051 as listed below.1.5 Programming the FlashThe AT89C2051 is shipped with the 2 Kbytes of on-chip PEROM code memory array in the erased state (i.e., contents=FFH) and ready to be programmed. The code memory array is programmed one byte at a time. Once the array is programmed, to re-program any non-blank byte, the entire memory array needs to be erased electrically.Internal address counter: the AT89C2051 contains an internal PEROM address counter which is always reset to 000H on the rising edge of RST and is advanced applying a positive going pulse to pin XTAL1.Programming algorithm: to program the AT89C2051, the following sequence is recommended.1. power-up sequence:Apply power between VCC and GND pins Set RST and XTAL1 to GNDWith all other pins floating , wait for greater than 10 milliseconds2. Set pin RST to ‘H’ set pin P3.2 to ‘H’3. Apply the appropriate combination of ‘H’ or ‘L’ logic to pins P3.3, P3.4, P3.5,P3.7 to select one of the programming operations shown in the PEROM programming modes table.To program and Verify the Array:4. Apply data for code byte at location 000H to P1.0 to P1.7.5.Raise RST to 12V to enable programming.5. Pulse P3.2 once to program a byte in the PEROM array or the lock bits. The byte-write cycle is self-timed and typically takes 1.2ms.6. To verify the programmed data, lower RST from 12V to logic ‘H’ level and set pins P3.3 to P3.7 to the appropriate levels. Output data can be read at the port P1 pins.7. To program a byte at the next address location, pulse XTAL1 pin once to advance the internal address counter. Apply new data to the port P1 pins.8. Repeat steps 5 through 8, changing data and advancing the address counter for the entire 2 Kbytes array or until the end of the object file is reached.9. Power-off sequence: set XTAL1 to ‘L’ set RST to ‘L’Float all other I/O pins Turn VCC power off2.1 The principle of piezoelectric ultrasonic generatorPiezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate. When it’s two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibration resonance, ultrasound is generated. Conversely, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver.The traditional way to determine the moment of the echo’s arrival is based on thresholding the received signal with a fixed reference. The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the object’s nature, size and distance from the sensor. Further, the time interval from the echo’s starting point to the moment when it surpasses the threshold changes with the intensity of the echo. As a consequence, a considerable error may occur even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2.2 The principle of ultrasonic distance measurementUltrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received by the receiverimmediately stop the clock. Ultrasound in the air as the propagation velocity of 340m/s, according to the timer records the time t, we can calculate the distance between the launch distance barrier(s), that is: s=340t / 23. Ultrasonic Ranging System for the Second Circuit DesignSystem is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip selection of 875, economic-to-use, and the chip has 4K of ROM, to facilitate programming.3.1 40 kHz ultrasonic pulse generated with the launchRanging system using the ultrasonic sensor of piezoelectric ceramic sensorsUCM40, its operating voltage of the pulse signal is 40kHz, which by the single-chip implementation of the following procedures to generate.puzel: mov 14h, # 12h; ultrasonic firing continued 200msHere: cpl p1.0; output 40kHz square wavenop;nop;nop;djnz 14h, here;retRanging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a 40kHz pulse output signal, after amplification transistor T, the drive to launch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location.3.2 Reception and processing of ultrasonicUsed to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltage-controlled oscillator center frequency of f0=1/1.1R8C3, capacitor C4 determinetheir target bandwidth. R8-conditioning in the launch of the high jump 8 feet into a low-level, as interrupt request signals to the single-chip processing.Ranging in front of single-chip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port single-chip, while single-chip P1.3 and P1.4 received input IC3A, interrupted by the process to identify the source of inquiry to deal with, interrupt priority level for the first left right after. Part of the source code is as follows:Receivel: push pswpush accclr ex1; related external interrupt 1jnb p1.1, right; P1.1 pin to 0, ranging from right to interrupt service routine circuitjnb p1.2, left; P1.2 pin to 0, to the left ranging circuit interrupt service routinereturn: SETB EX1; open external interrupt 1pop accpop pswretiright: …; right location entrance circuit interrupt service routineAjmp Returnleft: …; left ranging entrance circuit interrupt service routineAjmp Return3.3 The calculation of ultrasonic propagation timeWhen you start firing at the same time start the single-chip circuitry within the timer T0, the use of timer counting function records the time and the launch of ultrasonic reflected wave received time. When you receive the ultrasonic reflected wave, the receiver circuit output a negative jump in the end of INT0 or INT1 interrupt request generates a signal, single-chip microcomputer in response to external interrupt request, the implementation of the external interrupt service subroutine, read the time difference, calculating the distance. Some of its source code is as follows:RECEIVE0: PUSH PSWPUSH ACCCLR EX0; related external interrupt 0MOV R7, TH0; read the time valueMOV R6, TL0CLR CMOV A, R6SUBB A, #0BBH; calculate the time differenceMOV 31H, A; storage resultsMOV A, R7SUBB A, # 3CHMOV 30H, ASETB EX0; open external interrupt 0\POP ACCPOP PSWRETIFor a flat target, a distance measurement consists of two phases: a coarse measurement and a fine measurement:Step 1: Transmission of one pulse train to produce a simple ultrasonic wave.Step 2: Changing the gain of both echo amplifiers according to equation, until the echo is detected.Step 3: Detection of the amplitudes and zero-crossing times of both echoes.Step 4: Setting the gains of both echo amplifiers to normalize the output at, say 3 volts. Setting the period of the next pulses according to the: period of echoes. Setting the time window according to the data of step 2.Step 5: Sending two pulse trains to produce an interfered wave. Testing the zero-crossing times and amplitudes of the echoes. If phase inversion occurs in the echo, determine to otherwise calculate to by interpolation using the amplitudes near the trough. Derive t sub m1 and t sub m2.Step 6: Calculation of the distance y using equation.4、The ultrasonic ranging system software designSoftware is divided into two parts, the main program and interrupt service routine. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control.Interrupt service routines from time to time to complete three of the rotation direction of ultrasonic launch, the main external interrupt service subroutine to read the value of completion time, distance calculation, the results of the output and so on.5、ConclusionsRequired measuring range of 30cm-200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility. Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error. Therefore, it can be used not only for mobile robot can be used in other detection system.Thoughts: As for why the receiver do not have the transistor amplifier circuit, because the magnification well, integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequency.6、Parking sensor6.1 Parking sensor introductionReversing radar, full name is "reversing the anti-collision radar, also known as" parking assist device, car parking or reversing the safety of assistive devices, ultrasonic sensors(commonly known as probes), controls and displays (or buzzer)and other components. To inform the driver around the obstacle to the sound or a moreintuitive display to lift the driver parking, reversing and start the vehicle around tovisit the distress caused by, and to help the driver to remove the vision deadends and blurred vision defects and improve driving safety.6.2 Reversing radar detection principleReversing radar, according to high-speed flight of the bats in thenight, not collided with any obstacle principles of design anddevelopment. Probe mounted on the rear bumper, according to different price and brand, the probe only ranging from two, three, four, six, eight,respectively, pipe around. The probe radiation, 45-degree angle up and downabout the search target. The greatest advantage is to explore lower than the bumper of the driver from the rear window is difficult to see obstacles, and the police, suchas flower beds, children playing in the squatting on the car.Display parking sensor installed in the rear view mirror, it constantlyremind drivers to car distance behindthe object distance to the dangerous distance, the buzzer starts singing, allow the driver to stop. When the gear lever linked into reverse gear, reversing radar, auto-start the work, the working range of 0.3 to 2.0 meters, so stop when the driver was very practical. Reversing radar is equivalent to an ultrasound probe for ultrasonic probe can be divided into two categories: First, Electrical, ultrasonic, the second is to use mechanical means to produce ultrasound, in view of the more commonly used piezoelectric ultrasonic generator, it has two power chips and a soundingboard, plus apulse signal when the poles, its frequency equal to the intrinsic oscillation frequency of the piezoelectric pressure chip will be resonant and drivenby the vibration of the sounding board, the mechanical energy into electrical signal, which became the ultrasonic probe works. In order to better study Ultrasonic and use up, people have to design and manufacture of ultrasonic sound, the ultrasonic probe tobe used in the use of car parking sensor. With this principle in a non-contactdetection technology for distance measurement is simple, convenient and rapid, easyto do real-time control, distance accuracy of practical industrial requirements. Parking sensor for ranging send out ultrasonic signal at a givenmoment, and shot in the face of the measured object back to the signal wave, reversing radar receiver to use statistics in the ultrasonic signal from the transmitter to receive echo signals calculate the propagation velocity in the medium, which can calculate the distance of the probe and to detect objects.6.3 Reversing radar functionality and performanceParking sensor can be divided into the LCD distance display, audible alarm, and azimuth directions, voice prompts, automatic probe detection function is complete, reversing radar distance, audible alarm, position-indicating function. A good performance reversing radar, its main properties include: (1) sensitivity, whether theresponse fast enough when there is an obstacle. (2) the existence of blind spots. (3) detection distance range.6.4 Each part of the roleReversing radar has the following effects: (1) ultrasonic sensor: used tolaunch and receive ultrasonic signals, ultrasonic sensors canmeasure distance. (2) host: after the launch of the sine wave pulse to the ultrasonic sensors, and process the received signal, to calculate the distance value, the data and monitor communication. (3) display or abuzzer: the receivinghost from the data, and display the distance value and provide differentlevels according to the distance from the alarm sound.6.5 Cautions1, the installation height: general ground: car before the installation of 45 ~55: 50 ~ 65cmcar after installation. 2, regular cleaningof the probe to prevent the fill. 3, do not use the hardstuff the probe surface cover will produce false positives or ranging allowed toprobe surface coverage, such as mud. 4, winter to avoid freezing. 5, 6 / 8 probe reversing radar before and after the probe is not free to swap may cause the ChangMing false positive problem. 6, note that the probe mounting orientation, in accordance with UP installation upward. 7, the probe is not recommended to install sheetmetal, sheet metal vibration will cause the probe resonance, resulting in false positives.超声测距系统设计原文出处：传感器文摘布拉福德：1993年超声测距技术在工业现场、车辆导航、水声工程等领域具有广泛的应用价值，目前已应用于物位测量、机器人自动导航以及空气中与水下的目标探测、识别、定位等场合。

计算机科学与技术外文翻译英文文献中英对照

附件1：外文资料翻译译文大容量存储器由于计算机主存储器的易失性和容量的限制, 大多数的计算机都有附加的称为大容量存储系统的存储设备, 包括有磁盘、CD 和磁带。

相对于主存储器，大的容量储存系统的优点是易失性小，容量大，低成本, 并且在许多情况下, 为了归档的需要可以把储存介质从计算机上移开。

术语联机和脱机通常分别用于描述连接于和没有连接于计算机的设备。

联机意味着，设备或信息已经与计算机连接，计算机不需要人的干预，脱机意味着设备或信息与机器相连前需要人的干预，或许需要将这个设备接通电源，或许包含有该信息的介质需要插到某机械装置里。

大量储存器系统的主要缺点是他们典型地需要机械的运动因此需要较多的时间，因为主存储器的所有工作都由电子器件实现。

1. 磁盘今天，我们使用得最多的一种大量存储器是磁盘，在那里有薄的可以旋转的盘片，盘片上有磁介质以储存数据。

盘片的上面和（或）下面安装有读/写磁头，当盘片旋转时，每个磁头都遍历一圈，它被叫作磁道，围绕着磁盘的上下两个表面。

通过重新定位的读/写磁头，不同的同心圆磁道可以被访问。

通常，一个磁盘存储系统由若干个安装在同一根轴上的盘片组成，盘片之间有足够的距离，使得磁头可以在盘片之间滑动。

在一个磁盘中，所有的磁头是一起移动的。

因此，当磁头移动到新的位置时，新的一组磁道可以存取了。

每一组磁道称为一个柱面。

因为一个磁道能包含的信息可能比我们一次操作所需要得多，所以每个磁道划分成若干个弧区，称为扇区，记录在每个扇区上的信息是连续的二进制位串。

传统的磁盘上每个磁道分为同样数目的扇区，而每个扇区也包含同样数目的二进制位。

（所以，盘片中心的储存的二进制位的密度要比靠近盘片边缘的大）。

因此，一个磁盘存储器系统有许多个别的磁区, 每个扇区都可以作为独立的二进制位串存取，盘片表面上的磁道数目和每个磁道上的扇区数目对于不同的磁盘系统可能都不相同。

磁区大小一般是不超过几个KB; 512 个字节或1024 个字节。

毕业设计(论文)外文资料翻译(学生用)

毕业设计外文资料翻译学院：信息科学与工程学院专业：软件工程姓名： XXXXX学号： XXXXXXXXX外文出处： Think In Java (用外文写)附件： 1.外文资料翻译译文；2.外文原文。

附件1：外文资料翻译译文网络编程历史上的网络编程都倾向于困难、复杂，而且极易出错。

程序员必须掌握与网络有关的大量细节，有时甚至要对硬件有深刻的认识。

一般地，我们需要理解连网协议中不同的“层”（Layer）。

而且对于每个连网库，一般都包含了数量众多的函数，分别涉及信息块的连接、打包和拆包；这些块的来回运输；以及握手等等。

这是一项令人痛苦的工作。

但是，连网本身的概念并不是很难。

我们想获得位于其他地方某台机器上的信息，并把它们移到这儿；或者相反。

这与读写文件非常相似，只是文件存在于远程机器上，而且远程机器有权决定如何处理我们请求或者发送的数据。

Java最出色的一个地方就是它的“无痛苦连网”概念。

有关连网的基层细节已被尽可能地提取出去，并隐藏在JVM以及Java的本机安装系统里进行控制。

我们使用的编程模型是一个文件的模型；事实上，网络连接（一个“套接字”）已被封装到系统对象里，所以可象对其他数据流那样采用同样的方法调用。

除此以外，在我们处理另一个连网问题——同时控制多个网络连接——的时候，Java内建的多线程机制也是十分方便的。

本章将用一系列易懂的例子解释Java的连网支持。

15.1 机器的标识当然，为了分辨来自别处的一台机器，以及为了保证自己连接的是希望的那台机器，必须有一种机制能独一无二地标识出网络内的每台机器。

早期网络只解决了如何在本地网络环境中为机器提供唯一的名字。

但Java面向的是整个因特网，这要求用一种机制对来自世界各地的机器进行标识。

为达到这个目的，我们采用了IP（互联网地址）的概念。

IP以两种形式存在着：(1) 大家最熟悉的DNS（域名服务）形式。

我自己的域名是。

所以假定我在自己的域内有一台名为Opus的计算机，它的域名就可以是。

外文翻译--基于51单片机温度报警器的设计(适用于毕业论文外文翻译+中英文对照)

外文翻译--基于51单片机温度报警器的设计(适用于毕业论文外文翻译+中英文对照)XXX: Design of a Temperature Alarm Based on 51 MCUDepartment: n EngineeringMajor: Measurement and Control Technology and nClass:Student ID:Name:Supervisor:Date:A microcontroller。

also known as a single-chip computer system。

XXX its ns being integrated on a small chip。

it has most of the components needed for a complete computer system。

such as CPU。

memory。

internal and external bus systems。

and mostof them also have external storage。

At the same time。

it integrates XXX interfaces。

timers。

real-time clocks。

etc。

The most XXX integrate sound。

image。

ork。

and complex input-output systems on a single chip.XXX used in the industrial control field。

Microcontrollers XXX CPUs inside the chip。

The original design concept was to integrate a large number of peripheral devices and CPUs on a chip to make the computer system XXX's Z80 was the first processor designed according to this concept。

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西京学院本科毕业设计(论文)外文资料翻译教学单位：机电工程系专业：机械设计制造及其自动化学号： 0700010143姓名：于江成外文出处： Embedded Microcomputer Systems:Real Time Interfacing2011年3月译文一：单片机系统广义地说，微处理系统是用于处理信息的，这种信息可以是电话交谈，仪器读数或企业帐户，但是各种情况下都涉及相同的主要操作：信息处理、存储和传递。

在常规的电子设计中，这些操作都是以功能平台方式组合起来的，例如计数器，无论是电子还是机械的，都要存储当前值，并按要求将该值增1。

诸如采用计数器的电子钟之类的任一系统要使其存储和处理能力遍布整个系统，因为每个计数器都能存储和处理一些数字。

当前微处理化系统与上述的常规方法不同，它将处理，存储和传输三个功能分离形成不同的系统单元。

这种形成三个主要单元的分离方法是冯-诺依曼在20世纪40年代所设想出来的，并且是针对微计算机的设想。

从此几乎所有制成的计算机都是用这种结构设计的，尽管包含宽广的物理形式，从根本上来说他们均是具有相同的基本设计。

在微处理器系统中，处理是由微处理器本身完成的。

存储是利用存储器电路，而进入和出自系统的信息传输则是利用特定的输入/输出（I/O）电路。

要在一个微处理器化时钟中找出执行计数功能的一个特殊硬件是不可能的，因为时间存储在存储器中，而在固定的时间间隔下由微处理器控制增值。

但是，规定系统运转过程的软件包含实现计数器功能的单元。

由于系统几乎完全由软件所定义，所以对微处理器结构和其辅助电路这种看起来非常抽象的处理方法使其在应用时非常灵活。

这种设计过程主要是软件工程，而且在生产软件时，就会遇到产生于常规工程中相似的构造和维护问题。

图1.1 微型计算机的三个组成部分图1.1显示出了微型计算机中这三个单元是如何按照机器中的信息通信方式而联接起来的。

该系统由微处理器控制，它管理自己与存储器和输入/输出单元的信息传输。

外部的连接与工程系统的其余部分（即非计算机部分）有关。

尽管图中显示的只有一个存储单元，实际中有RAM和ROM两种不同的存储器被使用。

由于概念上的计算机存储器更像一个公文柜，上述的“存储器”一词是非常不恰当的；信息存放在一系列已标号的“箱子”中，而且可按问题由“箱子”的序列号进行信息的参考定位。

微计算机常使用RAM（随机存取存储器），在RAM中数据可被写入，并且在需要时可被再次读出。

这种数据能以任一所希望的次序从存储器中读出，不必按写入时的相同次序，所以有“随机”存取存储器。

另一类型ROM（只读存储器）用来保持不受微处理器影响的固定的信息标本；这些标本在电源切断后不会丢失，并通常用来保存规定微处理器化系统运转过程的程序。

ROM可像RAM 一样被读取，但与RAM不一样的是不能用来存储可变的信息。

有些ROM在制造时将其数据标本放入，而另外的则可通过特殊的设备由用户编程，所以称为可编程ROM。

被广泛使用的可编程ROM可利用特殊紫外线灯察除，并被成为E PROM，即可察除可编程只读存储器的缩写。

另有新类型的期器件不必用紫外线灯而用电察除，所以称为电可察除可编程只读存储器EEPROM。

微处理器在程序控制下处理数据，并控制流向和来自存储器和输入/输出装置的信息流。

有些输入/输出装置是通用型的，而另外一些则是设计来控制如磁盘驱动器的特殊硬件，或控制传给其他计算机的信息传输。

大多数类型的I/O装置在某种程度下可编程，允许不同形式的操作，而有些则包含特殊用途微处理器的I/O装置不用主微处理器的直接干预，就可实施非常复杂的操作。

假如应用中不需要太多的程序和数据存储量，微处理器、存储器和输入/输出可全被包含在同一集成电路中。

这通常是低成本应用情况，例如用于微波炉和自动洗衣机的控制器。

当商品被大量地生产时，这种单一芯片的使用就可节省相当大的成本。

当技术进一步发展，更强更强的处理器和更大更大数量的存储器被包含形成单片微型计算机，结果使最终产品的装配成本得以节省。

但是在可预见的未来，当需要大量的存储器或输入/输出时，还是有必要继续将许多集成电路相互联结起来，形成微计算机。

微计算机的另一主要工程应用是在过程控制中。

这是，由于装置是按特定的应用情况由微机编程实现的，对用户来说微计算机的存在通常就更加明显。

在过程控制应用中，由于这种设备以较少的数量生产，将整个系统安装在单个芯片上所获取的利益常比不上所涉及的高设计成本。

而且，过程控制器通常更为复杂，所以要将他们做成单独的集成电路就更为困难。

可采用两种处理，将控制器做成一种通用的微计算机，正像较强版本的业余计算机那样；或者做成“包裹”式系统，按照像电磁继电器那样的较老式的技术进行设计，来取代控制器。

对前一种情况，系统可以用常规的编程语言来编程，正如以后要介绍的语言那样；而另一种情况，可采用特殊用途的语言，例如那种使控制器功能按照继电器相互连接的方法进行描述。

两种情况下，序均能存于RAM，这让程序能按应用情况变化时进行相应的变化，但是这使得总系统易受掉电影响而工作不正常，除非使用电池保证供电连续性。

另一种选择是将程序在ROM中，这样他们就变成电子“硬件”的一部分并常被称为“固件”。

尽管大规模集成电路的应用使小型和微型计算机的差别变得“模糊”，更复杂的过程控制器需要小型计算机实现他们的过程。

各种类型的产品和过程控制器代表了当今微计算机应用的广泛性，而具体的结构取决于对“产品”一词的解释。

实际上，计算机的所有工程和科学上的应用都能指定来进行这些种类的某一或某些工作。

而在本设计中压力和压力变送器当某一力加到某一面积上，就形成压力，假如这力是1牛顿均匀地加在1平方米的面积上，这压力被定义为1帕斯卡。

压力是一种普遍的工艺状态，它也是这个星球上的一个生活条件：我们生活在向上延伸许多英里的大气海洋的底部。

空气物质是有重量的，而且这种下压的重量形成大气压。

水，是生活的必需品，也是在压力之下提供给我们中的大多数人。

在典型的过程工厂中，压力影响沸点温度、凝固点温度、过程效率、消耗和其他重要因数。

压力的测量和控制，或者压力的不足—真空，在典型的过程控制中是极为重要的。

工厂中的工作仪器通常包括压力计、精密纪录仪、以及气动和电动的压力变送器。

压力变送器实现压力测量并产生正比于所传感压力的气动或电信号输出。

在过程工厂中，将控制仪表远远放在过程的附近是不现实的，并且大多数测量是不容易从远处传来的。

压力测量是一个例外，但是，如果要离测量点几百英尺外指示或记录某种危险化学品的高压，就会有来自这个压力所载的化学品所引发的危险。

为了消除这一问题，开发了一种信号传输系统。

这种系统常常可是气动或者电动的。

使用这种系统，就可以在某一地点安装大多数的指示、记录和控制仪器。

这也是最少数量的操作者有效的运行工厂成为现实。

当使用气动传送系统时，测量信号就由变送器将比例为0%～100%的测量值转换为气动信号。

变送器安装在靠近过程中的测量点上。

变送器输出—对气动变送器是输出压力—通过管道传给记录或控制仪表。

气动变送器的标准输出范围是20～100kPa，这信号几乎在全球使用。

当使用电子压力变送器时，压力就被转换成电流或电压形式的电信号。

其标准范围对电流来说是4～20mA DC，对电压信号来说是1～5V DC。

当今，另一种电信号形式变的越来越常用，就是数字或离散信号。

基于计算机或微处理器的仪器或控制系统的应用正推动这类信号的应用不断增加。

有时，分析获取描述传感器/变送器特性的参数是很重要的。

当量程已知，去获取增益就非常简单。

假定电子压力传感器的量程为0～600kPa ，增益定义为输出变化除以输入变化。

这里，输出的电信号（4～20mA DC ），而输入的过程压力（0～600kPa ），这样增益就为：此外我们在本设计中还必须对温度进行测量，温度测量在工业控制中是很重要的，因为它作为系统或产品状态的直接指标，或者作为如反应率、能量流、涡轮机效率和润滑质量等间接指标。

现行的温度分度已使用了约200年，最初的仪器是基于气体和液体的热膨胀。

现在尽管有许多其他类型的仪器在使用，这些填充式系统仍常用于直接的温度测量。

有代表性的温度传感器包括：填充式热系统、玻璃液体温度计、热电偶、电阻温度探测器、热敏电阻、双金属器件、光学和辐射高温计和热敏涂料。

电气系统的优点包括高的精度和灵敏度，能实现开关切换或扫描多个测量点，可在测量元件和控制器之间长距离传输，出现事故时可调换元件，快速响应，以及具有测量高温的能力。

其中热电偶和电阻温度探测器则被最广泛的使用。

kPamA kPa mA kPa kPa mA mA Kr 027.0600160600420==--=原文一：Microcomputer SystemsElectronic systems are used for handing information in the most general sense; this information may be telephone conversation, instrument read or a company‟s accounts, but in each case the same main type of operation are involved: the processing, storage and transmission of information. in conventional electronic design these operations are combined at the function level; for example a counter, whether electronic or mechanical, stores the current and increments it by one as required. A system such as an electronic clock which employs counters has its storage and processing capabilities spread throughout the system because each counter is able to store and process numbers.Present day microprocessor based systems depart from this conventional approach by separating the three functions of processing, storage, and transmission into different section of the system. This partitioning into three main functions was devised by V on Neumann during the 1940s, and was not conceived especially for microcomputers. Almost every computer ever made has been designed with this structure, and despite the enormous range in their physical forms, they have all been of essentially the same basic design.In a microprocessor based system the processing will be performed in the microprocessor itself. The storage will be by means of memory circuits and the communication of information into and out of the system will be by means of special input/output(I/O) circuits. It would be impossible to identify a particular piece of hardware which performed the counting in a microprocessor based clock because the time would be stored in the memory and incremented at regular intervals but the microprocessor. However, the software which defined the system‟s behavior would contain sections that performed as counters. The apparently rather abstract approach to the architecture of the microprocessor and its associated circuits allows it to be very flexible in use, since the system is defined almost entirely software. The design process is largely one of software engineering, and the similar problems of construction and maintenance which occur in conventional engineering are encountered when producing software.The figure1.1illustrates how these three sections within a microcomputer are connected in terms of the communication of information within the machine. The system is controlled by the microprocessor which supervises the transfer of information between itself and the memory and input/output sections. The external connections relate to the rest (that is, the non-computer part) of the engineering system.Fig.1.1 Three Sections of a Typical MicrocomputerAlthough only one storage section has been shown in the diagram, in practice two distinct types of memory RAM and ROM are used. In each case, the word …memory‟ is rather inappropriate since a computers memory is more like a filing cabinet in concept; information is stored in a set of numbered …boxes‟ and it is referenced by the serial number of the …box‟ in question.Microcomputers use RAM (Random Access Memory) into which data can be written and from which data can be read again when needed. This data can be read back from the memory in any sequence desired, and not necessarily the same order in which it was written, hence the expression …random‟ access memory. Another type of ROM (Read Only Memory) is used to hold fixed patterns of information which cannot be affected by the microprocessor; these patterns are not lost when power is removed and are normally used to hold the program which defines the behavior of a microprocessor based system. ROMs can be read like RAMs, but unlike RAMs they cannot be used to store variable information. Some ROMs have their data patterns put in during manufacture, while others are programmable by the user by means of special equipment and are called programmable ROMs. The widely used programmable ROMs are erasable by means of special ultraviolet lamps and are referred to as EPROMs, short for Erasable Programmable Read Only Memories. Other new types of device can be erased electrically without the need for ultraviolet light, which are called Electrically Erasable Programmable Read Only Memories,EEPROMs.The microprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output devices. Some input/output devices are general-purpose types while others are designed for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing different modes of operation, while some actually contain special-purpose microprocessors to permit quite complex operations to be carried out without directly involving the main microprocessor.The microprocessor processes data under the control of the program, controlling the flow of information to and from memory and input/output devices. Some input/output devices are general-purpose types while others are designed for controlling special hardware such as disc drives or controlling information transmission to other computers. Most types of I/O devices are programmable to some extent, allowing different modes of operation, while some actually contain special-purpose microprocessors to permit quite complex operations to be carried out without directly involving the main microprocessor.The microprocessor , memory and input/output circuit may all be contained on the same integrated circuit provided that the application does not require too much program or data storage . This is usually the case in low-cost application such as the controllers used in microwave ovens and automatic washing machines . The use of single package allows considerable cost savings to e made when articles are manufactured in large quantities . As technology develops , more and more powerful processors and larger and larger amounts of memory are being incorporated into single chip microcomputers with resulting saving in assembly costs in the final products . For the foreseeable future , however , it will continue to be necessary to interconnect a number of integrated circuits to make a microcomputer whenever larger amounts of storage or input/output are required.Another major engineering application of microcomputers is in process control. Here the presence of the microcomputer is usually more apparent to the user because provision is normally made for programming the microcomputer for the particularapplication. In process control applications the benefits lf fitting the entire system on to single chip are usually outweighed by the high design cost involved, because this sort lf equipment is produced in smaller quantities. Moreover, process controllers are usually more complicated so that it is more difficult to make them as single integrated circuits. Two approaches are possible; the controller can be implemented as a general-purpose microcomputer rather like a more robust version lf a hobby computer, or as a …packaged‟ system, signed for replacing controllers based on older technologies such as electromagnetic relays. In the former case the system would probably be programmed in conventional programming languages such as the ones to9 be introduced later, while in the other case a special-purpose language might be used, for example one which allowed the function of the controller to be described in terms of relay interconnections, In either case programs can be stored in RAM, which allows them to be altered to suit changes in application, but this makes the overall system vulnerable to loss lf power unless batteries are used to ensure continuity of supply. Alternatively programs can be stored in ROM, in which case they virtually become part of the electronic …hardware‟ and are often referred to as firmware. More sophisticated process controllers require minicomputers for their implementation, although the use lf large scale integrated circuits …the distinction between mini and microcomputers, Products and process controllers of various kinds represent the majority of present-day microcomputer applications, the exact figures depending on one‟s interpretation of the word …product‟. Virtually all engineering and scientific uses of microcomputers can be assigned to one or other of these categories. But in the system we most study Pressure and Pressure Transmitters. Pressure arises when a force is applied over an area. Provided the force is one Newton and uniformly over the area of one square meters, the pressure has been designated one Pascal. Pressure is a universal processing condition. It is also a condition of life on the planet: we live at the bottom of an atmospheric ocean that extends upward for many miles. This mass of air has weight, and this weight pressing downward causes atmospheric pressure. Water, a fundamental necessity of life, is supplied to most of us under pressure. In the typical process plant, pressure influences boiling point temperatures, condensing point temperatures, process efficiency, costs, and other important factors. The measurementand control of pressure or lack of it-vacuum-in the typical process plant is critical.The working instruments in the plant usually include simple pressure gauges, precision recorders and indicators, and pneumatic and electronic pressure transmitters.A pressure transmitter makes a pressure measurement and generates either a pneumatic or electrical signal output that is proportional to the pressure being sensed.In the process plant, it is impractical to locate the control instruments out in the place near the process. It is also true that most measurements are not easily transmitted from some remote location. Pressure measurement is an exception, but if a high pressure of some dangerous chemical is to be indicated or recorded several hundred feet from the point of measurement, a hazard may be from the pressure or from the chemical carried.To eliminate this problem, a signal transmission system was developed. This system is usually either pneumatic or electrical. And control instruments in one location. This makes it practical for a minimum number of operators to run the plant efficiently.When a pneumatic transmission system is employed, the measurement signal is converted into pneumatic signal by the transmitter scaled from 0 to 100 percent of the measurement value. This transmitter is mounted close to the point of measurement in the process. The transmitter output-air pressure for a pneumatic transmitter-is piped to the recording or control instrument. The standard output range for a pneumatic transmitter is 20 to 100kPa, which is almost universally used.When an electronic pressure transmitter is used, the pressure is converted to electrical signal that may be current or voltage. Its standard range is from 4 to 20mA DC for current signal or from 1 to 5V DC for voltage signal. Nowadays, another type of electrical signal, which is becoming common, is the digital or discrete signal. The use of instruments and control systems based on computer or forcing increased use of this type of signal.Sometimes it is important for analysis to obtain the parameters that describe the sensor/transmitter behavior. The gain is fairly simple to obtain once the span is known. Consider an electronic pressure transmitter with a range of 0～600kPa.The gain isdefined as the change in output divided by the change in input. In this case, the output is electrical signal (4～20mA DC) and the input is process pressure (0～600kPa). Thus the gain. Beside we must measure Temperature Temperature measurement is important in industrial control, as direct indications of system or product state and as indirect indications of such factors as reaction rates, energy flow, turbine efficiency, and lubricant quality. Present temperature scales have been in use for about 200 years, the earliest instruments were based on the thermal expansion of gases and liquids. Such filled systems are still employed, although many other types of instruments are available. Representative temperature sensors include: filled thermal systems, liquid-in-glass thermometers, thermocouples, resistance temperature detectors, thermostats, bimetallic devices, optical and radiation pyrometers and temperature-sensitive paints.Advantages of electrical systems include high accuracy and sensitivity, practicality of switching or scanning several measurements points, larger distances possible between measuring elements and controllers, replacement of components(rather than complete system), fast response, and ability to measure higher temperature. Among the electrical temperature sensors, thermocouples and resistance temperature detectors are most widely used.kPamA kPa mA kPa kPa mA mA Kr 027.0600160600420==--=译文二：AT89C51的介绍描述AT89C51是一个低电压，高性能CMOS8位单片机带有4K字节的可反复擦写的程序存储器（PENROM）。