专业英语课文

11单元

?Unit 11 Typical Measurement Technology

1 Altitude Measurement

?1高度测量

?Accurate monitoring of aircraft cruising height is required in order to reduce vertical separation to minimum standard. Interest here focuses on the measurement of the distance between aircraft level and the sea surface level. This distance can be estimated onboard via barometric altimeters or it can be measured—either onboard or in ground stations—via electronic radio wave systems. The indication of the first equipment is referred to as pressure altitude, or simply altitude, whereas that of the second category is referred to as geometric height or simply height. 飞机巡航高度精确的控制要求以减少垂直分离到最低的标准。重点感兴趣的测量飞机之间的距离水平和海平面水平。这个距离估计通过机载altimeters气压或者它能在地面stations-via measured-either或机载电子无线电波系统。第一个设备或信封上注明所称为压力的高度,或简单地高度,而第二类的称为几何高度或简单的高度。

? The altitude information at air traffic control (ATC) centers is based on pressure altitude measurement that the aircraft transponder system sends after it receives an appropriate interrogation——known as mode C interrogation——transmitted by a secondary surveillance radar. Actually, the altitude information is an atmospheric pressure measurement transformed to altitude indication through a formula expressing the pressure/altitude relationship. When a flight level is cleared for an aircraft, it actually means that the pilot must keep flying on an isobaric surface. However, the altimetry system may present systematic errors (biases) that are different for each airplane, and that significantly affect safety. Thus, the altimetry system performance as well as the aircraft height keeping performance must be monitored by an independent radar or satellite system. 信息的高度,在空中交通管制中心(ATC)根据压高度测量,飞机的应答机系统发给后都把它珍藏一个适当的审讯——被称为模式C讯问——通过二级监视雷达。实际上,高度的大气压力测量信息转化为高度通过公式显示表达压力/高度的关系。当一个飞行高度是允许飞机时,实际上就意味着飞行员必须不停地飞在一个isobaric表面。然而,altimetry系统系统误差可能出现偏差)(飞机的不同而有所区别,明显影响安全。因此,altimetry系统性能以及飞机高度保持性能均须由独立的雷达或卫星电视系统

? 2.Thickness Measurement 2。厚度测量

?One can measure thickness on many scales .The galaxy is spiral disk about 100 Em(1020m)thick.. 你可以测量厚度,在许多尺度螺旋星系的约100 Em(1020m磁盘)深?The solar system is pancake-like ,about 1 Tm(1012 m) thick .The rings of Saturn are about 10 km thick .Closer to home ,Earth‘s atmosphere is a spherical shell about 40 km thick ;the weather occurs in the troposphere ,about 12 km thick .The outermost shell of the solid Earth is the crust，about 35 km thick .The ocean has a mean depth of 3.9 km .In the Antarctic，the recently discovered objects

believe to be microfossils indicative of ancient Martian life are less than 100 nm thick .In terms of the man-made environment，industry must contend with thickness varying from meters，for construction projects，to millimeters on assemble lines，to micrometers and nanometers for the solid-state，optical，and coatings industries .Perhaps the most familiar way of measuring thickness is by mechanical means，such as by ruler or caliper .Other means are sometimes called for ,either because both sides of an object are not accessible ,the dimension is either too big or too small for calipers ,the object is too fragile ,too hot ,or too cold for direct contact , or the object is in motion on an assemble line--it may not even be a solid .Thickness may also be a function of position ,as either the object may have originally been made with nonuniform thickness ,deliberately or not ,or the thickness may have become nonuniform with time due either to corrosion ,cracking ,or some other deterioration .The thickness may also be changing with time due to deliberate growth or etching ,as example for thin films .Thus it follows that ,in more general terms ,measuring thickness might require measuring the topography or height profile of two surfaces and taking the different .Alternatively ,the measurement technique may produce a reading directly related to the difference. 太阳系的薄烤饼似的,约需 1 Tm(1012米,厚的土星环10公里厚.Closer带回家,地球大气层中约40公里球壳厚;天气发生的对流层中,大约12公里最厚的外壳,固体地球是地壳厚,大约35公里,海洋的平均深度39公里在南极洲,最近发现在对象认为是化石代表古老火星生命在小于100海里厚条款的人造环境,行业必须满足不同厚度从米,建设项目上,毫米组装系列,以便和奈米的固态的跳动、光学、涂料行业最熟悉的方法也许测量厚度用机械的方法,例如由尺还是卡尺是意味着有时被称为,要么因为双方不能获取物体的尺寸,要么是太大或太小都为卡钳,对象很脆,太热或太冷,或直接接触的目的是在运动中,在一个生产线——它并不会在立体图形厚度也可以是一个函数的位置,无论是对象最初可能已经与均匀厚度、故意与否,厚度随时间可能已经变得不均匀腐蚀,要么由于裂,或其他一些恶化,厚度随时间的变化也可能是由于故意生长或腐蚀、为例对薄膜,紧随其后的工作,在更广泛的来说,测量厚度可能需要测量地形或高度两个平面的概况,以不同的.Alternatively、测量技术可能会引起阅读直接关系到的不同

? 3.Distance measurement 3。距离测量

?The tools and techniques of distance measurement are possibly one of humankind's longest-running inventive pursuits .This chapter concerns itself with methods to measure a relatively small segment of this range-from centimeters to kilometers .Even within this limited segment ,it would hardly be possible to list ,much less describe ,all of the distance measurement approaches that have been devised .Nevertheless ,the small sampling of technologies that are covered here should be of help to a broad range of readers.

?Distance measurement , at its most basic ,is concerned with determining the length of a unidimensional line joining two points in three-dimensional space . Oftentimes , a collection of distance measurements is called for ,so that shape ,the orientation , or the changes

in position of an object can be resolved . therefore , one must consider not only the measurement of distances ,but also their spatial and temporal distributions .The terminology “ranging” will be used in reference to systems that perform single sensor-to-target measurement ,”range-imaging” for systems that collect a dense map or grid of spatially distributed range measurement ,and “position tracking” for systems that record the time history of distance measurement to one or several targets . 工具和技术的距离测量的可能是人类漫长的发明之一。这一章中牵涉到的方法来评估一小部分这range-from公分到公里在这有限的段苦恼,这没有什么可以列表,更不用说描述,所有的距离测量方法设计然而,小抽样技术,在这里盖应该帮助广泛的读者距离测量,在最基础的,涉及确定的长度是一个一维线连接两个点三维空间。很多时候,一家集距离测量,要求的形状、取向、或变化的对象的位置都能得到解决。因此,我们必须考虑不仅是测量距离,而且他们的时空分布,术语“范围”将用于参考sensor-to-target测量系统,进行单range-imaging”,“系统,集密集的地图或者网格分布范围空间的方法,以及“位置跟踪”为系统,记录时间历史的距离测量一个或多个目标

? 4.Level Measurement 4。液位测量

?Level is defined as the filling height of a liquid or bulk material, for example, in a tank or reservoir. Generally , the position of the surface is measured relative to a reference plane, usually the tank bottom. If the product’s surface is not flat (e.g., with foam ,waves , turbulences ,or with coarse-grained bulk material) level usually is defined as the average height of a bounded area. 水平是指液体充填高度或散装资料,例如,在一个容器或水库。一般来说,表面的位置测量相对于参考平面,通常在罐底部。如果产品的表面不是平的(例如,有泡沫,波浪,动荡,或用细粒散装材料水平通常是指有界区域的平均高度。

? Various classic and modern methods exist to measure product level in process and storage tanks in the chemical, petrocheical , pharmaceutical ,water, and food industries, in mobile tanks on vehicles and ships, but also in natural reservoirs like seas, dams, lakes ,and oceans. Typical tank heights are approximately between 0.5 m and 40m.

?Two different tasks can be distinguished:(1)continuous level measurement (level indication ,LI) ,and (2) level switches (LS) (e.g., to detect an alarm limit to prevent overfilling). Fig. 11.1 shows the principal operational modes of level measurement .Every continuous system can also be used as a programmable switch .Many level devices are mounted on top of the tank and measure primarily the distance d between their mounting position and the product’s surface .The level L is then calculated ,defining the tank height h as constant, as shown in fig.11.1 and expressed as:

?L=h -d种各样的古典与现代的测量方法存在产品水平和储罐基础施工过程中在化工、petrocheical、医药、水、食品等行业,在移动调车、船,而且

在自然水库大坝、海洋、像湖泊和海洋。典型的坦克高度约0.5米之间4000万欧元。两种不同的任务,可以分为:(1)持续的水平测量(要求等级标志,李;及(2)最小的液位开关(例如:用于检测报警限制,以防止量)。图11.1显示液位测量主要运行方式下的每一处连续系统也可作为一个可编程的开关。许多级设备安装在上面的坦克和测量距离d之间的主要产品的固定点位置的物体,水平计算出L是坦克,定义了高度h为常数,显示在fig.11.1和表示为:我= h - d

13单元

While we appear to prefer the total objectivity of a mathematically formulated method of signal processing, it is now well proven that the AI methods often are better choices to use in terms of better speed of performance and often lower cost of processing.

当我们似乎更喜欢信号处理数学方法的整体客观性，现在证明，为了得到更好的速度性能和低成本的处理，人工智能方法经常是更好的选择。

Often they are the only solution since the algorithmic approach cannot be deployed because of the lack of a suitable mathematical formulation or powerful enough processor to run the algorithm.

经常当算法因为缺乏适合的数学表达式和足够强大处理器去运行算法而不能展开时，他们是唯一的解决方案。

Signal processing in the modern instrument, therefore, will often make use of many different methods. This account is an introduction to the characteristics of the various forms and is written to assist selection. Space limitations prevent presentation of each kind in detail.

account 账目解释利益报告叙述估计

因此，在现代仪器中的信号处理通常会使用许多不同的方法。这个说明只是对各种形式特征的一个介绍并被书写出来以帮助选择。空间的限制阻止了各种方法的详细介绍。

Overview of Algorithmic Methods

算法综述

Traditionally the most popular method used to develop mapping models is that of mathematical modeling.

传统上用于开发映射模型中最受欢迎的方法是数学建模。The mathematical model is usually what is sought, as it provides the highest level of understanding about the subject and the most precise representation of the behavior.

探索数学模型以提供课题最高水平理解和性能最精确的表达。

The major disadvantage of mathematical models is that they can quickly become so complex that implementation of these models in measurement systems is often impractical.

数学模型主要的缺点是迅速变得复杂，以致在测量系统中这些模型运行通常是不能实现的。

In this class, the single, or set of multiple, input signal(s) to the data processor is converted to the output form using tightly formulated mathematical description.

在这类，单一的或多个输入信号的数据处理通过密切使用数

学描述转化为输出形式。

his relationship is called the algorithm. Strict relationships hold; the relationship is said to be formal, meaning that for any given input the output will always be the same. The algorithm supports only one interpretation.

这种关系被称为所谓的算法。严格关系约束，关系可以说是有条理的，也就是说，对于任意给定输入输出将永远是一样的。算法只提供一种诠释。

This method of signal processing is the most highly developed method and is certainly one to aim for because it is devoid of ambiguity.

信号处理的方法是最高速发展的方法，必然以毫无歧义为目标的。

All will agree on how it will respond. It carries a comforting level of understanding and, thus, acceptance.

所有方法对如何响应取得了一致意见。它能达到一个令人欣慰的理解水平，从而接受它。

Algorithmic methods can be very accurate, traceable, and can be calibrated with relative ease and agreement.

计算方法可以是非常精确的，可描述的，并能较容易地调整并达成一致。

They are the basis of many instrumentation systems. The origin of

their use in instrumentation goes back to the early days of computing using, first, mechanical computational machines (late 1800s to around 1930) and then analog electric devices (early 1900s to 1960s), all of which were mostly replaced by the use of digital computers commencing around 1950.

他们是许多仪器系统的基础。在仪器中，他们使用的起源可追溯到的早期的计算机使用，首先，机械计算机器(19世纪后期到1930年)，然后到模拟电子设备(20世纪初到20世纪60年代)，所有这些都从大约1950年开始由于数字计算机的使用而被代替。

All of these algorithmic methods of processing can be simplistically regarded as embodiments of a mathematical equation inside a suitable technological machine.

所有的这些处理方法可以简单地看成是一个包含适当的技术设备的数学方程具体化。

As the demands complexity and performance requirements grew over time, so the did the demands on the detail of the algorithm and the means to model it inside a computational machine.

随着时间过去，由于需求复杂性和性能要求的增长，所以在计算机器里对算法细节和模型方法有要求。

Mathematical description eventually reaches limits of definition as the models push the boundaries of mathematical methods and human development. Too often, this arises before adequate detail is able to be

built into the model. The algorithm is then an inadequate model of the need.

当模型推动数学描述方法和人类发展的界限，数学描述最终到达定义极限。通常，适当的细节能够被构造进模型之前产生。算法是由于模型不足而产生的需要。

As the algorithm increases in complexity, the processing power needed must be increased to maintain both fidelity and speed of processing.

随着算法复杂度的增长，处理能力必须提高以保持精确和处理速度。

Despite great advances being made in algorithm development and in computer power, the algorithmic methodology eventually encountered mathematical and technological barriers in many fields.

尽管在算法的发展和计算能力上得到进步，在许多领域算法的方法论最终遇到数学上和技术上的壁垒。

The method is seen to not always be the best to use because of lack of an adequate algorithm or the high cost of computing.

研究方法因为缺乏适当的算法或由于高成本的计算不能得到最好地使用

In instrumentation, another factor also arises. Fast, detailed processing brings with it the need for increasing electrical bandwidth requirements in signal transmission. This increases implementation costs and also eventually reaches technological constraints.

在仪器上，另外一个因素也出现。在信号传输上快速的具体处理导致需要增加电气带宽要求。增加的施工成本也最终达到技术限制。

Fortunately the solutions that may overcome these limiting constraints in many circumstances were developing in other fields under the general name of artificial intelligence (now called applied intelligence in engineering), as new forms of mathematics and in other fields, such as decision theory.

幸运的是在很多情况下可以克服这些约束限制的解决方案在人工智能的其他领域中发展(现在称为“工程上的人工智能)，作为数学和其他领域的新形式，如决策论。

Principally, a key limitation of the algorithmic method is that its unforgiving level of formalism carries with it a depth of processing exactitude that is often not warranted.

主要来说，一个算法的关键的局限性是它形式主义过于苛刻的水平极大地影响了它处理精度的深度。

Other methods have emerged that allow vaguely subjective, as opposed to tightly objective, processing to be applied to good effect.

其他方法表现出允许含糊的主观，而不是严谨的客观，应用效果良好。

There AI methods have gradually gained acceptance to the degree that many are now routinely used and are supported by dedicated

applications software and electronic integrated circuitry.

人工智能方法在一定程度上逐渐获得接受，以至于现在许多被日常使用，并受专门应用软件和电子集成电路支持。

At first, these many alternatives were seen to be isolated methods. Gradually, the literature has shown trends to merge them in pairs.

首先，许多选择被看做是独立的方法。渐渐地，文献显示出成双融合的趋势。

Their use in a more widely mixed form is still limited. This account seeks to give a comprehensive appreciation of the commonly met AI processing methods by placing them into relative perspective.

在一个更广泛的混合形式中使用仍然受到限制。通过把他们放在一个相对的角度上，这个说明试图给出一些常见的人工智能的处理方法的综合评价。

It is interesting to contemplate that natural world computing in animals does not appear to make much use of algorithmic methods, but does make extensive use of the methods presented here in the AI class.

令人感兴趣的是认为在动物实验中自然界计算似乎不会大量使用的算法，但这里提供了在人工智能中广泛使用的算法。

The paradigm invoked here is that experience has shown that informal methods based on knowledge-based systems (KBS) can produce mappings of many inputs to one by use of less than completely formal description.

这里是调用的范例展示了这样的经验，基于知识系统(KBS)的一些常用方法可以通过使用不完整的形式描述产生多种输入到一个输出映射。

The AI methods can yield surprisingly efficient solutions to previously unsolved needs. They often can outperform algorithmic methods or carry out a similar task with far less computing power.

人工智能方法能提供惊人的有效方案去解决以前未解决的需求。他们往往比计算方法好或是用更少的计算能力就可执行类似任务。

They are all associated with multiple input processing and can be applied to forming decisions from data supplied by sensors. Each situation has to be judged on the balance between use of computing effort and effective processing.

他们与多重输入处理有关并应用于将通过传感器提供的数据形成决策。每个情况通过平衡计算量的使用和有效的处理进行判断。On the downside, they lack formality and thus may be very hard to calibrate and authenticate. They, not having adequate scientific foundation and a solid formal base of operation, are not easily accepted as “sound”.

不利的一面是他们缺乏形式，因此可能很难进行调整和验证。他们没有充足的科学基础和坚实的正式运行基础，不能轻易地认为是“可靠的”而被接受。

They are often hard to comprehend by a second party, for their description is not always adequately documented or done to any agreed convention. As their principles vary widely, they must be well understood before application is developed.

他们往往很难被另一流派理解，因为他们的描述并没有充分的文件可证明或做任何约定公约所规定。随着他们的原理广泛改变，他们必须在广泛应用之前被深入了解。

For all of these negative factors, they often are able to provide “more performance for less cost”and thus will be increasingly adopted.

对于所有这些不利因素,他们往往能提供“更多的性能以得到低成本”，从而越来越多地采用。

Their rising level of use should not suggest the algorithmic methods will become obsolete, but more that the instrument designer now has a much larger set of processing tools available.

使用的持续升级并不表明算法成为过时，但现在仪器设计者有更多的可用处理工具。

14单元

? 1.Station站点

? A station represents a single communicating element on a network system.Each user of the network must access the communication capablility of the network via

a station.Each station will typically have some

implementation of the open systems interconnection (OSI) network reference model as the means of utilizing the network system. 一个车站为一个沟通网络系统元素网络必须

的每个用户访问交流capablility通过网络的一个车站每个站

将会实施有一些有特色开放系统互连(OSI)网络方式的参考模

型,利用网络系统

? 2.Media Access 2。媒体访问Media access is the method by which individual stations determine when they

are permitted to transmit ,or “use”the media. Media access control (MAC) is a function that is usually performed in the data link layer of the OSI reference model .Some well-known methods of media access

?control include carrier sense multiple access with collision detection (CSMA/CD) and token passing.CSMA/CD systems (such as Ethernet) allow all stations on a network equal access.Each station must “listen” to the network to determine periods of inactivity before transmitting .Any station wishing to use the媒体访问方法确定个人站当他们允许传送、或“使用”媒体。媒体访问控制(MAC)是一种功能,通常是由在数据链路层的OSI参考模型的方法。一些知名媒体访问控制包括载波监听多址和碰撞检测(CSMA / CD)和令牌传球CSMA / CD系统(如以太网)让所有的工作站网络平等的机会每站必须“听”到网络,以确定时间的不活动,在发射信号愿意采用任何车站netwok may begin transmitting providing the network is inactive when it checks for activity.If multiple stations attempt to transmit simultaneously,a collision occurs.This is detected by all transmitting stations,which all must immediately stop transmitting and each wait a randomly determined period of time,before attempting to use the network again.Controller area network (CAN) ,for example,uses a variant of CSMA/CD for media access.Token-passing systems have a logical “token”

which is exchanged among stations via network messaging.The station that holds the token has permission to transmit.All other网络可能开始传输提供网络是消极的当它检查活动如果多个站,试图同时传输发生碰撞这是所有检测传输都必须立即停止所有发送和每个等随机决定一段时间,之前先试图利用网络了. 控制器局域网(能),例如,使用CSMA / CD的各种不同的媒体访问Token-passing系统具有相同的逻辑”

令牌”,是在以网络信息交换站车站时,保持令牌被允许传送所有其他stations are only permitted to receive messages.Stations wishing to transmit but not having the token must wait until the station holding the token passes it on.Another commonly used method of media access control is masterslave. In this method,one station on the network (designated the master) is generally in charge of,and originates, all communications.Slaves only respond to the master,and only respond when the master initiates communications with them via sending a message to the slave.Profibus-FMS(see below) is an example of a protocol which uses both token passing (in some cases)and master-slave(in some cases)to control media access空间站只被允许接收信息电台希望传送但实际上没有记号必须等到车站记号传递着另一个常用方法的媒体访问控制是适应主从式。

在该方法中,网络上的一个火车站大师(指定)是通常负责,渊源,所有的通信只有对奴隶主人,并且只有当主人的提升者的反应与他们沟通通过发送消息给奴隶Profibus-FMS(见下文)是一种典型的协议表示既使用通过(在某些情况下)和主从(在某些情况下,以控制媒体访问

13单元

Most sensors and instruments can produce continuous

measurements in time or sequential measurements at fixed or variable time intervals. The temporal patterns resulting from such measurements are usually referred to as signals. Signals can either be continuous or discrete in time. The main objective of spectral analysis is to provide an estimate of the distribution of signal power at different frequencies. Spectral analysis and correlation techniques are an aid to the interpretation of and to the systems that generate them. These methods are now used for the analysis and interpretation of measurements performed in medicine geophysics vibration analysis, communications, and several other areas.大多数传感器和仪器可以产生连续测量在时间或顺序测量时间间隔固定或变量。时态模式造成这样的测量通常称为信号。信号可以是连续的或离散的。光谱分析的主要目的是提供一个估计的信号功率在不同频率的分布。谱分析和相关技术是一个援助的解释和系统,生成它们。这些方法目前用于测量在医学的分析和解释地球物理振动分析,沟通,和其他几个地区。

Although the original concept of a signal involves measurements as a function of time this term has been generalized to include measurements along other dimensions, e. g. , distance. In addition, signals can have multiple dimensions-the instantaneous velocity of an airplane can be regarded as a four-dimensional signal since it depends on time and three spatial coordinates.

虽然包括信号测量的原始概念作为时间的函数这学期已经推广

到包含测量其他维度,e . g。距离。此外,信号可以有多个物体的瞬时速度飞机可以被视为一个四维的信号,因为这取决于时间和三个空间坐标。

With the growing availability of signal-processing computer packages and dedicated instruments, most readers will perform spectral analysis and correlation at the "touch of a button,”visualizing results on a screen or as a computer plot. These "black-box" systems are useful for saving time and money, but users should be aware of the limitations of -the fundamental techniques and circumstances in which inappropriate use can lead to misleading results. This chapter presents the basic concepts of spectral analysis and correlation based on the fast Fourier transform (FFT) approach. FFT algorithms allow the most efficient computer implementation or methods to perform spectral analysis and correlation and have become the most popular option. Nevertheless, other approaches. Such as parametric techniques wavelet transforms, and time-frequency analysis are also available. These will be briefly discussed and the interested reader will be directed to the pertinent literature for application that might benefit from alternative approaches.与信号处理电脑包和专用工具的日益普及,大多数读者进行光谱分析

和相关性在触摸一个按钮,“可视化结果在屏幕上或电脑阴谋。这些“黑箱”系统有助于节省时间和金钱,但是用户应该知道的局限性——基本技术和环境不当使用可能会导致误导的结果。本章提出了光谱分析的基本概念和相关基于快速傅里叶变换(FFT)的方法。允许最有效的计算机实现FFT算法或方法进行光谱分析和相关性,并已成为最受欢迎的选择。然而,其他方法。如参数小波变换技术和时频分析也可以。这些将简要讨论和感兴趣的读者将被引导至相关文献应用程序可能受益于替代方法。

Practical applications of spectral and correlation analysis are performed on discrete-time signals. These are obtained either from a sequence of discrete measurements or from the transformation of a continuous signal to digital format using an analog-to-digital converter (ADC). When the latter is adopted to allow computer analysis of an originally continuous signal, two main characteristics of the ADC need to be considered .He first is the number of bits available to represent each sample, as this will determine the resolution and accuracy of the sampled signal. The second important consideration is the sampling interval △t. From the Nyquist theorem, the maximum value of △t most be such that the sampling frequency fs = l／△t is at least twice the highest

frequency of interest in the original signal. If this rule is not followed, spectral and correlation estimations might be considerably distorted by a phenomenon called aliasing. Low-pass filtering before ADC is always recommended to limit the bandwidth of the continuous signal to allow the correct choice of fs or △t. In practice, the sampling frequency is usually much higher than the minimum required by the Nyquist theorem to provide a better visual representation of the sampled data.实际应用的光谱和相关分析进行离散时间信号。这些是获得序列的离散测量或从连续信号的转换到数字格式使用一个模拟-数字转换器(ADC)。当采用后者允许原连续信号的计算机分

析,ADC需要考虑的两个主要特征。他第一次是可用的比特数来表示每个样本,因为这将决定采样信号的分辨率和精度。第二个重要的考虑因素是采样间隔△t。尼奎斯特定理,△t的最大价值大多数是这样,

采样频率f = l /△t至少是对原始信号最高频率的两倍。如果没有这个规则,光谱和相关估计可能大大扭曲了称为混淆的现象。低通滤波在ADC总是推荐之前连续信号的带宽限制,允许fs或△t的正确的选择。在实践中,采样频率通常远高于最低要求的奈奎斯特定理提供更好的抽样数据的可视化表示。

Let Xn represent a discrete-time signal with samples at n=0,1,2,..,N-l. The Fourier theorem states that it is possible to decompose Xn as a sum of cosine and sine waveforms of different frequencies using an appropriate combination of amplitude coefficients. 让Xn代表一个离散时间信号样本在n = 0,1,2,…,需要。傅里叶定理指出,可以分解Xn笔余弦和正弦波形的不同频率使用一个适当的幅度系数的组合。

16单元

1.Overview

In the 1950's, we began to look again at differential equation models and Kalman, Bellman, and others introduced the state-space concept which lead t0 6'optimal control" which had been introduced earlier by Weiner and Phillips. Sampled data systems were introduced to handle control systems which used digital computers. These developments are often cited as the beginning of "modern control. 1。概述

在1950年,我们开始重新审视微分方程模型和卡尔曼,更夫,其他状态空间概念,介绍了铅t0 6 'optimal控制”维纳和菲利普斯早些时

候推出。介绍了采样数据系统来处理控制系统采用数字计算机。这些发展常常被引用为“现代控制的开始。

In the 1960's, we began to address the problem of designing control systems for situations which varied with time (as the system ages, or as it's operating environment changes) .Adaptive systems were designed which (1) measure their operation relative to an "index of performance" and (2) then modify controller parameters to approach optimal values (for whatever operating conditions may be present). Successful adaptive systems have been built for many applications, and there are no doubt many future control problems that will be solved with this powerful methodology.在1960年,我们开始解决这一问题的设计控制系统的情况下随时间(系统年龄,或操作环境变化)。自适应系统的设计(1)测量其操作相对于一个“性能指数”,(2)然后修改控制器参数接近最优值(不管操作条件可能出现)。成功的自适应系统已经建立对于许多应用程序,并毫无疑问有很多未来的控制问题,将与这个强大的解决方法。

Adaptive control systems readjust themselves to different operating conditions, however an adaptive controller does not "learn" from it's experiences. Even though the adaptive controller many adjust itself for optimal performance in a given circumstance, it must re-adjust itself

again if it should return to the same circumstance. On the other hand, if "learning" were incorporated into an "intelligent" control system, then it could utilize it's past experience and more quickly achieve optimal performance, especially for "familiar" circumstances. This challenge (among others) has served to stimulate our current interest in "intelligent" control systems.自适应控制系统调整自己不同的操作条件,然而

一个自适应控制器并不“学习”的经历。尽管许多调整为最佳性能自适应控制器在一个给定的情况下,必须重新调整本身又是否应该回到相同的情况。另一方面,如果“学习”被纳入一个“智能”控制系统,然后可以利用它的过去经验和更快地实现最优性能,尤其是对“熟悉”的情况下。这一挑战(等)曾来刺激我们当前的“智能”控制系统的兴趣。

Intelligent system attempt to incorporate functions which are normally contained in Iiving beings; adaptation, learning, planning under large uncertainty, coping with unexpected changes handling large amounts of (possibly conflicting) information, self- reliance, and so on. In addition to accommodating variable plants and unexpected changes in operating conditions, intelligent control is also directed toward improving our ability to accurately model non-linear systems. (We have a rich inventory of control technology that