(1) Translate the following sentences into Chinese.1.As with series resonance, the greater the resistance in the circuit the lower the Q and, accordingly, the flatter and broader the resonance curve of either line current or circuit impedance.
对于串联谐振，电路中的电阻愈大Q值就愈低，相应地线路电流或电路阻抗的谐振曲线也就愈平、愈宽。2.A wire carrying a current looks exactly the same and weighs exactly the same as it does when it is not carrying a current.
一根带电的导线其外表与重量都与不带电导线完全一样。3.Click mouse on the waveform and drag it to change the pulse repetition rate, or directly enter a new value of the period in the provided dialogue box, while keeping the pulse width unchanged.
在波形上点击鼠标并拖动来改变脉冲重复频率，或者在提供的对话框中直接输入新的周期值，而保持脉冲宽度不变。4.Electronics is the science and the technology of the passage of charged particles in a gas, in a vacuum, or in a semiconductor. Please note that particle motion confined within a metal only is not considered electronics.
电子学是一门有关带电粒子在气体、真空或半导体中运动的科学技术。注意，在本书中粒子运动仅限于金属的情况不属于电子学。5.Hardware technologies have played vital roles in our ability to use electronic properties to process information, but software and data processing aspects have not developed at the same speed.
硬件技术在我们使用电子特性来处理信息的能力中一直起着重要作用，而软件及数字处理方面却没能与硬件同步发展。6.However, in a properly designed DC amplifier the effect of transistor parameter variation, other than Ico, may be practically eliminated if the operation point of each stage is adjusted so that it remains in the linear operation range of the transistor as temperature varies.
然而在设计得当的直流放大器中，若调节每一级的工作点使之在温度变化时保持在晶体管线性区，就能在实际上消除Ico以外的晶体管参数变化所造成的影响。
Unit 2 Exercises
(1) Translate the following sentences into Chinese.1.If analog signals are to be transmitted digitally, they first have to be sampled at a specified rate and further converted to discrete amplitude samples by quantization.
如果要以数字方式传输模拟信号，首先必须以一定的频率对信号进行采样，然后通过量化进一步将它们转换为离散的幅度样本。2.Linear filters amplify or attenuate selected spatial frequencies, can achieve such effects as smoothing and sharpening, and usually form the basis of re-sampling and boundary detection algorithms. 线性滤波器放大或衰减选择的空间频率，能够实现像平滑和锐化这些效果，通常是重采样和
边缘检测算法的基础。
3.Stability and repeatability are fundamental attributes of digital circuits, however, and the necessary accuracy can be obtained in a digital version of the modulator by an appropriate choice of word length to represent the signals.
不过稳定性和可重复性是数字电路的基本性质，在数字式调制器中必要的精度可通过适当地选择代表信号的字长而获得。4.The first observation is made on the fundamental relationship between the nature of system
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and the periodicity of its frequency response: a continuous system has an aperiodic frequency response, while a discrete system has a periodic frequency response.
从系统性质和它频率响应的周期性之间的基本关系中首先可以看到：连续系统有非周期性的频率响应，而离散系统有周期性的频率响应。5.The main function of the receiver is to extract the input message signal from the degraded version of the transmitted signal coming from the channel.
接收器的主要功能是从由信道传输来的退化了的信号中提取出输入消息。
Unit 3 Exercises
(1) Translate the following sentences into Chinese.1.A very commonly used method of microwave measurements is based on the study of a standing wave pattern formed along the line because of the interference of incident and reflected waves.一个很常用的微波测量方法是基于对驻波图型的研究，这种驻波是由入射波和反射波之间的干涉而沿着传输线形成的。2.Computations show a reduction of 6dB in the EM field intensity with the distance doubled, and an increase of 3dB in the intensity with the transmitted power doubled. This result provides verification to the algorithm used.
计算表明，当距离增大一倍时，电磁场强度减小6分贝；而发射功率增大一倍时，场强则增加3分贝。这一结果验证了所用算法的正确性。3.Like transfer of heat by conduction, convection and radiation, microwave heating can be considered as another mode of heat transfer, in which heat is produced directly at the location of the dielectric losses.
就像通过传导、对流、辐射来传递热量一样，微波加热可以看作热传递的另一种方式，即热量直接产生于发生介电损耗的地方。4.Operation of the radar is based on the measurement of the time it takes for a pulse transmitted from an antenna to get reflected by the object to be detected and to return at the antenna and the receiver.雷达的工作是基于对天线发出的脉冲被所要探测的目标反射，（然后）回到天线和接收机所需时间的测量。5.Other motivations for using CAD in circuit design includes the wish to acquire confidence in a design that was accomplished by other means, and, not least in importance, a sense of curiosity or perhaps a desire to discover the unexpected.
在电路设计中使用CAD的其它动机包括：想要验证用别的方法设计出来的电路；满足好奇心或者可能是想发现预想不到的现象。后一个动机并非是最不重要的。（取得信心，并非最不重要，意料之外的事）6.The spacing between the repeating amplifiers is a function of the cable attenuation and the system bandwidth so that the gain provided by these amplifiers compensates for the loss introduced by the cable.
中继放大器之间的间距是电缆衰减和系统带宽的函数，以便这些放大器提供的增益补偿电缆引起的损耗。7.When the cut-off frequency is no less than the maximal frequency of the original signal, nor is it greater than the difference between the sampling frequency and the maximal frequency, the original signal may be completely rebuilt.
当截止频率不小于原始信号的最高频率，也不大于采样频率和最高频率之差，原始信号可以完整地重建。8.While the politics of the last one hundred years centered around Industrial Age technology, the
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politics of the future will be based on Information Age concerns oriented towards the storage, protection and exchange of information.
尽管近百年来的政治活动是以工业时代的技术为中心的，未来的政治活动将基于信息时代的事物，面向信息的存储、保护和交换。
Unit 4 Exercises
(1) Translate the following passages into Chinese.1.Communication may be broadly defined as the transfer of information from one point to another. When the information is to be conveyed over any distance a communication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information on to an electromagnetic wave which acts as a carrier for the information signal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier waves operating at radio frequencies as well as microwave and millimeter wave frequencies. However, communication may also be achieved by using an electromagnetic carrier that is selected from the optical range of frequencies.
通信可以广义地定义为从一处到另一处的信息传递。当要将信息传输到任何距离以外时就需要有一个通信系统。在通信系统内部，信息的传输经常通过将信息叠加或调制到作为信号载体的电磁波上来实现。经调制的载波然后被传送到要求的目的地，在那里被接收，原始信号通过解调被恢复出来。为了实现这一过程，已经利用工作在射频、微波以及毫米波频率上的电磁载波开发了复杂的技术。不过通信也可以用光波频段上的电磁载波来实现。2.Electronic communications is the transfer and movement of data between locations through the use of computers. An electronic communication system includes the equipment needed to support the movement of information, the communication lines and media to carry the information, the computer software and programs to control the flow of information, the personnel to plan, implement, and operate communications, and the management of all these resources. Electronic communications establishes links between people as well as computers.
电子通信就是通过使用计算机在不同的地点之间传输数据。一个电子通信系统包括：支持信息流动所需要的设备，承载信息的通信线路和媒介，控制信息流的计算机软件和程序，计划、实施、操作通信系统的人员，以及对所有这些资源的管理。电子通信建立起人和人、计算机和计算机之间的联系。3.First generation communications systems can be characterized by the use of analog transmission techniques, and the use of simple multiplex access techniques such as frequency division multiple access (FDMA). They suffered from a low user capacity, and security problems due to the simple radio interface used. Second generation systems were introduced in the early 1990’s, and all use digital technology. This provided an increase in the user capacity of around three times, achieved by compressing the voice waveforms before transmission. Third generation systems are an extension on the complexity of second-generation systems and are to be introduced after the year 2000. The system capacity will be increased to over ten times original first generation systems, achieved by using complex multiplex access techniques such as code division multiplex access (CDMA), or an extension of TDMA, and by improving flexibility of services available.
第一代通信系统以模拟传输技术和简单复用技术如频分复用为特征。这些系统用户容量低，而且因为使用简单的无线电接口而存在安全问题。第二代通信系统于20世纪90年代初开始引入，全部使用数字技术。通过在传输前将话音波形压缩使得用户容量提高了三倍。第三代通信系统是对第二代
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Therefore the subcarrier frequencies in the base band are fn = n/T, (n = 0, 1, ... , N1). Denoting the n-th modulating symbol as X(n), the OFDM waveform within a symbol duration can be expressed as: time a系统在复杂性方面的扩展，预计于2000年以后启用。通过使用复杂的复用技术如CDMA或TDMA的扩展，并提高服务的灵活性使得系统容量比原来的第一代系统提高10倍。4.For each combination of communication (modulation/detection) type, channel fading model, and diversity type, the average bit error rate (BER) and/or symbol error rate (SER) of the system is obtained and represented by an expression in a form that can readily be evaluated. All cases considered correspond to real practical channels, and in many instances the BER and SER expressions obtained can be evaluated numerically on a hand-held calculator.对于通信（调制/检测）类型、信道衰落模型、分集类型的每一种组合，得到系统的平均误码率（BER）和符号错误率（SER），并以容易求值的形式表示。所有考虑的相应于实际信道的情况，以及许多情况下得到的BER和SER表达式均可用手持计算器来计算。5.Modulation is the systematic variation of some attribute of a carrier waveform such as the amplitude, phase, or frequency in accordance with a function of the message signal. It is used in communication systems for matching signal characteristics to channel characteristics, for reducing noise and interference, for simultaneously transmitting several signals over a single channel, and for overcoming some equipment limitations. A considerable portion of this book is devoted to the study of how modulation schemes are deigned to achieve the above tasks. The success of a communication system depends to a large extent on the modulation.调制是载波波形的某些属性，例如幅度、相位和频率，根据消息信号的函数有规则的变化。它用于通信系统以使信号特性匹配信道特性，减少噪声和干扰，在单个信道上同时传输多个信号，并克服某些设备的限制。本书相当大部分内容是研究如何设计调制方案以实现上述任务。一个通信系统的成功很大程度上依赖于调制。Unit 5 Exercises (1) Translate the following passage into Chinese.OFDM consists of a large number of subcarriers equally spaced in a frequency band, each may be digitally modulated by a same scheme such as PSK, QAM, etc., or by different schemes. A serially transmitted sequence is divided into a number of sections, each having N symbols, and the N symbols in each section are used to modulate N carriers for simultaneous transmission. Therefore OFDM is essentially a parallel modulation system. When the number of subcarriers is sufficiently large, the system can resist multipath interference. This is because that, in the time domain, a symbol duration longer than the multipath delay can be chosen, while in the frequency domain, each symbol only occupies a small portion of the channel’s frequency band. Thus, the effect of multipath fading spreads over many symbols, resulting in slight distortion to many symbols rather than complete destroy of a few symbols. In this way, correct demodulation is not affected so that the signal can be accurately recovered at the receiver. In an OFDM system, the principle of choosing the subcarrier interval is to make the subcarriers mutually orthogonal within the entire symbol period. Thus, even if spectral overlap exists between the subcarriers, the symbols can still be recovered without loss. In order to realize maximum spectral efficiency, the interval between subcarriers is usually chosen to equal the reciprocal of the symbol duration T. ndnx(t)X(n)expj2t,0tTTn0 AN1ll things in their being are good for4ng at aSampling this waveform at t = T/N yields somethin(1)kTN1nkx(k)X(n)expj2X(n)expj2,k1,2,,N1Nn0Nn0N1nx(t)X(n)expj2t,0tTTn0在t = T/N 时刻采样这个波形得到：N1N1 beingIt is observed from the above expression that x(k) and X(n) form a discrete Fourier transform pair, therefore the baseband OFDM waveform can be generated from the discrete Fourier transform of N modulating symbols. When N=2m where m is an integer, the fast algorithm of IDFT is easy to implement.OFDM由大量在频率上等间隔的子载波构成。每个子载波可用同样的方案，如PSK，QAM等，或者用不同的方案数字调制。将串行传输的符号序列分成许多段，每一段有N个符号，每段的N个符号被用来分别调制N个载波同时发送。因此，OFDM本质上是一个并行调制系统，当载波数足够大时，这种系统具有抗多径干扰的能力。这是因为在时域上符号周期能选取得比多径延迟时间长，而在频域上每个符号只占整个信道带宽的一小部分，因此多径衰落的影响被分散到许多符号上，其结果是许多符号都发生轻度的畸变，而不是使某些符号被完全破坏。这样，不影响正确的解调，信号能在接收器中准确地恢复。在OFDM系统中，选择子载波间隔的原则是使子载波在整个符号周期内相互正交，这样。即使在子载波间存在频谱部分重叠，符号仍能无损失地恢复。为了实现最大的频谱效率，子载波之间的间隔通常选取为符号周期的倒数。因此基带子载波频率为fn = n/T, (n = 0, 1, ... , N1)，第n个调制符号记为X(n)，在一个符号周期内的OFDM波形可表示： are good for5 thkTN1nkx(k)X(n)expj2X(n)expj2,k1,2,,N1Nn0Nn0从上面的表示中可以看到，x(k) 和X(n)构成了一对离散傅里叶变换，因此基带OFDM波形可根据N个调制符号的离散傅里叶变换来生成。当N=2m，其中m为整数，IDFT的快速算法很容易实现。Unit 6 Exercises (1) Translate the following sentences into Chinese.1.Communication is the transmission of information from one point to another. This transmission requires the ability to vary signals with time in a manner which is unpredictable to the receiver.通信就是信息从一点传送到另一点。这种传送要求信号随时间发生的变化不能在接收端预测。2.It is true of any communication system that the shape and amplitude of the transmitted signal will be continuously degraded by the introduction of noise, and the attenuation along the transmission path.传输的信号会不断地被噪声的引入和线路上的衰减所损伤，对任何通信系统都是如此。3.Since the very beginning, communications systems have consisted of three major parts, namely, the equipment, the medium, and the protocol. It is still the case today. However, the close link of telecommunications with the computer technology has brought about tremendous changes in communications, from the concepts, to the contents and the methods.4.从一开始通信系统就由设备、媒介和协议三个要素组成。至今依然如此。然 算机技术的紧密联系使得通信从概念到内容和手段都发生了重大的变化。5.The availability of such a large collection of system performance curves in a single compilation allows the researcher or system designer to perform trade-off studies among the various communication type/fading channel/diversity combinations so as to determine the optimum choice in the eirng at a time and All things in somethin(2)(1)(2) face of his or her available constraints.
在一本书中提供如此大量的系统性能曲线，使研究者或系统设计者能在各种通信类型、衰落信道、分集组合之间进行比较研究，从而在他或她所面临的限制之下做出最佳的选择。6.The channel provides the electrical connection between the information source and the user. The channel can have many different forms such as a microwave radio link over free space, a pair of wires, or an optical fiber.
信道提供信息源和用户之间的电路联接。信道可以有许多不同的形式，比如自由空间里的微波联接，一对电线，或者一根光纤。7.The degradation of the transmitted signal is a result of signal distortion due to imperfect response of the channel and due to undesirable electrical signals (noise) and interference. Noise and signal distortion are two basic problems of electrical communication.
传输信号的退化是信号失真的结果，而这种失真又是由信道的非理想响应及不想要的电信号（噪声）和干扰引起的。噪声和信号畸变是电子通信的两个基本问题。
Unit 8 Exercises
(1) Translate the following sentences into Chinese.1.Early in the twentieth century, it was found that light could cause atoms to emit electrons and that, when light released an electron from an atom, the energy possessed by the electron very greatly exceeded that which the atom could, according to the electromagnetic wave theory, have received.
在二十世纪早期，人们发现光能够使原子放出电子，而且当光从原子中释放一个电子时，电子所包含的能量大大超过由电磁波理论得到的原子所接收的能量。2.Pulse broadening determines the minimum separation between adjacent pulses, which in turn determines the maximum information-carrying capacity of the optical fiber.
脉冲的展宽决定了相邻脉冲之间的最小间隔，这一间隔进而又决定了光纤的最大信息容量。3.If one were to transmit such information without impressing it on an optical carrier but instead on a radio frequency (RF) carrier a bit higher than the maximum rate, the transmission wavelength of the RF carrier would be centimeters or larger.
如果传输这样的信息不是将它加载到光纤上，而是加载在略高于最大速率的射频载波上，则此射频载波就会是厘米波或是波长更长一些的波。4.The smallness of the optical wavelength, therefore, allows for the miniaturization of transmit and receive modules, which should allow considerable reduction in size, weight, and cost of optical communication systems with respect to microwave/radio wave counterparts.
光波波长之小使发射和接收模块得以小型化，这就使光通信系统的尺寸、重量以至价格与相应的微波、无线电波通信系统相比都大为降低。5.Although all the advantages of coherent optical communication systems have yet to be brought to fruition, another property of optical radiation has made today’s optical communication systems not desirable for applications.
虽然相干光通信系统的所有优点还有待于落实在具体成果中，光辐射的另一性质却使目前的光通信系统不利于应用。6.When coupled with light’s short wavelength which allows for miniature sources and detectors and micron-sized waveguides, direct detection schemes have allowed for small, lightweight, high bandwidth systems which are competitive in many areas, most notably to the present telecommunications transmission, although a myriad of other applications are continually opening up.
光的波长很小，可以使用小型的光源和检测器以及微米级的波导，于是用直接检测方案可实现在许多领域具有竞争力的小巧的宽带系统，这些领域中特别引人注目的是当前电信传输中的应用，尽管
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Unit 11 Exercises
1.In a television scanning generator using a pair of free-running relaxation oscillators, free-running frequencies of the oscillators are set slightly below the horizontal and vertical pulse rates, and the stripped pulses are used to trigger the oscillators prematurely and thus to synchronize them to the line and half-frame rates.
在采用一对自由张弛振荡器的电视扫描发生器中，振荡器的自由频率被设置得略低于水平和垂直（扫描）频率，分离出来的脉冲被用来提前触发振荡器从而使它们与行频和半帧频（场频）同步。
Unit 12 Exercises
1.Referring to the figure, we see that signal processing techniques are needed for preprocessing, pattern recognition techniques are needed for segmentation, feature extraction, and classification, and artificial intelligence techniques are needed for structure analysis, knowledge-acquisition and representation (world model), and control structure (interaction among the blocks).
参考图，我们看到信号处理技术是预处理所需要的，模式识别技术是分割、特征提取以及分类所需要的，而人工智能技术则是结构分析、知识获取及表示（世界模型）以及控制结构（块间交互）所需要的。2.The picture elements across a line are converted to the video signal and low-pass filtered with an electrical filter. This smoothing removes the discrete structure in the horizontal dimension.
沿着一条直线的图像像素被转换成视频信号，然后由一个电子滤波器进行低通滤波。这一平滑处理可消除水平方向的离散结构。
Unit 13 Exercises
(1) Translate the following sentences into Chinese.1.The preceding chapters have described how the automatic computer performs, but have not described how the automatic computer can be put to use to do data handling work to serve an organization, nor why such work is done in the way that it is.
前面的章节讲述了自动计算机是如何工作的，但没有讲述自动计算机如何能用于数据处理工作以服务于一个机构，也没有讲述这种工作为什么用这种方法实现。2.While the subject of coding often carries with it an air of secrecy, a more important motive in many coding systems is the improved efficiency in conveying information.
如果说编码这一主题常带有一种秘密的色彩，那么许多编码系统的一个更重要的目的则是为了提高信息传递的效率。
无数其他应用也在不断涌现出来。7.As mentioned previously, these applications have tended to open up more slowly than originally predicted, as cost was really not much of a consideration in telecommunications, where equipment costs are swamped by other considerations.如前所述，（线路）成本并非电信系统中真正重要的考虑因素，通信设备的成本主要受到其他因素的制约，因此这些应用比预料的出现得慢。8.As wavelengths decrease to approach the size of circuit components, circuit elements are no longer lumped as such, and leads can act as reflective components and/or antennas and lumped elements as electromagnetic resonators.
随着波长减小到接近于电路元件的尺寸，电路单元就不再是集总的，导线可起到反射元件以及（或）天线的作用，集总单元则成为电磁谐振器。
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Dynamic range: up to 128 or more gray levels can be present on digital images whereas only
1530 discernible on film products.Reproducibility: a copy of a copy of a copy of a digital image contains exactly the same data
as the original, whereas a forth-generation photographic product is substantially degraded in comparison with the original.
Although these are advantages, the compelling advantage for the applications community derives from the accessibility of the data to computer manipulation. To generate a general-purpose film product is essentially to choose a compromise among competing requirements from agronomists, hydrologists, foresters, geologists, urban planners, and other user groups; it is not optimized for any one. Digital images lend themselves to custom tailoring by the user for his or her application in a way that film products cannot.
数字图像处理包括了多种多样的技术和数学工具，每一项应用都涉及到一系列的处理步骤。这些步骤是以大量不同次序排列的各种模块，每一模块通常容许一些参数值的技术指标，从而进一步扩大了为获得预期结果而可能采取的处理方案的选择范围。与模拟图像（即胶片）相比，数字图像的主要优点在于数据的质量和数据可供计算机进行处理这两方面。质量方面的优越性实际上是以下两种优越性的综合：动态范围：数字图像可表现128级或更多的灰度，而胶片产品只能分辨15至30级；重现性：一幅数字图像多次复制后仍与原件包含完全相同的信息，而一幅第四代的照片与原件相比却大大地退化（损伤）了。
Unit 16 Exercises
(1) Translate the following sentences into Chinese.1.In recent years, there has been a tremendous increase in the use of digital computers and special-purpose digital circuitry for performing varied signal processing functions that were originally achieved with analog equipment.
近年来为实现各种信号处理功能，数字计算机和专用数字电路的使用有了巨大的增长，这些处理功能原先都是用模拟设备实现的。2.In the beginning, computers were used to process only numerical information, but majority of our information is non-numerical in nature and very little is known about its description and processing.一开始计算机只是被用来处理数值信息，而我们的大多数信息都是非数值性质的，而且人们对这些信息的描述和处理所知甚少。
Unit 14 Exercises
(1) Translate the following sentences into Chinese.1.The importance of early brain development in setting the foundations for language is apparent in babies younger than 6 months.
大脑的早期发展对于奠定语言基础的重要性在六个月以下的婴儿中是显而易见的。
Unit 15 Exercises
(1) Translate the following passage into Chinese.
Because digital image processing does encompass such a wide variety of techniques and mathematical tools, each application involves a sequence of processing steps. These steps are modules that can be arranged in an enormous number of different sequences, and each module generally admits the specification of parameter values that further expand the range of possible manipulation schemes to achieve the desired results. The major advantages of digital images as compared with analog (i.e. film) images are the quality of the data and the accessibility of that data to computer manipulation. The quality advantage is really an aggregate of two advantages:
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Unit 17 Exercises
(1) Translate the following passages into Chinese.1.For the first time ever the landscape is changing, as high volume personal computer multimedia applications proliferate. First affected were monitors, which for some time have offered higher-than-broadcast speed and resolution. One can expect cameras to follow, with high-speed, high-resolution devices driven by consumer digital still camera technology and lower-resolution, ultra low cost units driven by entertainment, internet conferencing, and perceptual user interface applications.
随着大量个人计算机多媒体应用的急剧增加，情况首次发生了变化。最早受到影响的是显示器，相当长时间以来它已经能够提供比广播级更高的分辨率和速度。人们可期待照相机/摄像机也随之跟上，包括由民用数字照相机所推动的高速度、高分辨率器件，娱乐业、互联网远程会议和用户视觉界面应用所推动的低分辨率和极低价格的设备。2.If you already have the fastest CPU in a particular family and still want more performance, then it may be more cost-effective to add system RAM or cache RAM than to put in a processor from a different family. Adding system memory can bring significant performance increases at a relatively low cost, assuming you configure the memory correctly. In addition to added cache and system RAM, a faster and larger hard drive can save you time when running applications dependent on heavy drive access and data throughput. Adding a graphics accelerator card can help, too, especially if you are looking for a way to stay awake while your system redraws images.
如果你已经有了某一系列中最快的CPU而还想要更多的性能，那么增加系统RAM或高速缓存RAM也许比插入一枚另一系列的处理器更合算。特别是如果你是一名Windows用户，假设你正确地配置内存，则增加系统内存可以较低的代价带来可观的性能提高。除了增加高速缓存或系统
RAM，一个更快和更大的硬盘可在运行依赖于大量读写硬盘和有大量数据吞吐时节省你的时间。增加一个图形加速器也是有益的，如果你使用Windows，而且发现你在寻找某种途径使你在系统重显图象时能保持“清醒”，则尤其是如此。3.In university environments, MATLAB has become the standard instructional tool for introductory courses in applied linear algebra, as well as advanced courses in other areas. In industrial settings, MATLAB is used for research and to solve practical engineering and mathematical problems. Typical uses include general purpose numerical computation, algorithm prototyping, and special purpose problem solving with matrix formulations that arise in disciplines such as automatic control theory, statistics, and digital signal processing (time-series analysis).
在大学环境里，它已成为应用线性代数导论以及其他领域中许多高级课程的标准教学工具。在工业界，MATLAB被用于研究和解决实际的工程和数学问题。典型的应用包括通用数值计算、算法原型测试以及使用矩阵公式的专门问题的解决，这些问题是在自动控制理论、统计、数字信号处理（时间序列分析）等学科中提出来的。4.Multimedia is a generic term for “multimedia computing” or “interactive multimedia”. The computer and software are used to control and navigate through the communications links, not only one at the time, but several simultaneously. Computer systems have been most developed in using vision and hearing to interface between the digital and analogue worlds, e.g., still and moving images, text and graphics use the visual senses, and audio uses hearing. Multimedia is defined as visual, audio and textual information which can be presented, separately or simultaneously, to convey and present information interactively to users. It is technically easy to digitize the analogue forms of these common media and handled by computers now widely available and inexpensive to be accessible to most users.
多媒体是表示“多媒体计算”或“交互式多媒体”的一般术语。计算机和软件被用于控制并通过不止一条通信链接同时进行浏览。在利用视觉和听觉在数字和模拟世界之间进行交互方面，计算机系
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It is rare that the optimization will be achieved in only one step, and usually many iterations around the analysis-error-adjustment loop will be required for obtaining a satisfactory result.
只经过一步就达到优化的情况是罕见的，为了得到满意的结果通常要围绕“分析－误差－调节”的循环进行多次迭代。
统已得到极大的发展，例如对静止和活动图像、文本和图形使用视觉，对音频使用听觉。多媒体被定义为可以分别或同时展现的视频、音频、文本信息，用以交互式地将信息传递和展示给用户。技术上很容易将这些普通媒体的模拟形式用计算机实现数字化并加以处理，计算机现在已十分普遍，其价格便宜，大多数用户都能使用。5.The essential capability of any multimedia computer system is the ability to convert the analogue signal to a digital format and to compress this information using standard algorithms. The power of the CPU will determine whether this process can be carried out in real-time or whether it has to be done off-line. Originally this power only existed in UNIX systems, but more recently it has become available in PCs and Macintosh. The compression process is necessary otherwise the quantity of data to be stored and transmitted would be excessive. Most PCs have until recently depended upon hardware encoding/decoding systems, but the speed of current processors is such that software compression systems have been developed. The advantage of the software systems is that the compatibility and interoperability issues can be handled more easily, and the cost of the equipment is not raised by the need to purchase expensive hardware devices.
任何多媒体计算机的基本功能是将模拟信号转换成数字格式，并用标准算法将此信息压缩的能力。CPU处理能力将决定是否能实时完成此过程还是必须离线执行。原先只有UNIX系统才有这种实时能力，但近年来PC和Macintosh也能胜任（有这种能力）了。压缩是必须的，否则要存储和传送的数据量太大。直到不久前大多数PC还依赖硬件编解码系统，而目前的处理器速度已使软件编解码系统的开发成为可能。软件系统的优点在于可更方便地处理兼容性和协同工作问题，而且不会因购置昂贵的硬件而提高设备成本。
Unit 19 Exercises
(1) Translate the following paragraphs into Chinese.1.Artificial Intelligence is a branch of science that helps machines find solutions to complex problems in a human-like fashion. This generally involves borrowing characteristics from human intelligence, and applying them as algorithms in a computer friendly way. Computers are fundamentally well suited to performing mechanical computations using fixed rules. This allows machines to perform simple monotonous tasks efficiently and reliably, which humans are not suited to. Unlike humans, however, computers have trouble in understanding specific situations, and adapting to new situations. Artificial Intelligence aims to improve machine behavior in tackling such complex tasks. Humans have an interesting approach to problem-solving, based on abstract thought, high-level reasoning and pattern recognition. Artificial Intelligence can help us understand this process by recreating it, then potentially enabling us to enhance it beyond our current capabilities.
人工智能是一个科学分支，它可以帮助机器找到像人那样解决复杂问题的解。这通常包括从人的智能中借用一些特征，应用这些特征开发出便于计算机实现的算法。计算机原则上适合于按照固定的编程规则进行机械性的计算，这使得机器能够有效而可靠地执行简单单调的任务，这正是人所不擅长的。然而不同于人，计算机难以理解特定的情形，适应的新情况。人工智能的目标就是改进机器的性能以对付这种复杂的任务。人类具有一种解决问题的有趣能力，这种能力是基于抽象思维、高级推理和模式识别的。人工智能可以通过重建这一过程来帮助我们理解它，进而使我们的能力有可能超越当前的水平。
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