篇一：测控技术与仪器专业英语课后阅读翻译(1,5~10)
第1章课后
Underwater Acoustic Signal
In the operation of a sonar system the operator is repeatedly faced with the problem of detecting a signal which is obscured by noise. This signal may be an echo resulting from a transmitted signal over which the operator has some control, or it may have its origin in some external source. These two modes of operation arise in radar surveillance and in disciplines for techniques and for illustrations of the basic principles.
Since there are many ways in which one can think about signal detection , it is desirable to define a term to denote special cases . The word detection will be used when the question to be answered is, ?Are one or more signals present?? when the system is designed to provide an answered to this question , either deterministic or probabilistic, one speaks of hypothesis testing. The case of a single signal occurs so often that many system are designed to provide only two answers, ?Yes , a signal is present,? or ?No, there is no signal.? One can make the problem more complicated by endeavoring to classify the signal into categories. Decisions of this latter kind will be referred to as target
classification.
Normally a piece of detection equipment is designed to operate in a fixed mode and the parameters such as integrating time of rectifier circuits or persistence of the oscilloscope tube for visual detection cannot be changed readily. There will always be some uncertain signals, which the observer will be hesitant to reject or accept. In these cases the operator might have the feeling that if the integrating time of the detector or the persistence of the oscilloscope tube were longer, he could reach a decision about the existence of the signal. Wald(1950) has formulated this intuitive feeling into a theory of detection. When one is able to vary deliberately the interval over which one stores data in the
reception system in order to achieve a certain level of certainty, one speaks of sequential detection. Frequently it is desirable to determine not only the presence or absence of the signal but also one or more parameters associated with the signal . The parameters of interest can vary widely from a simple quantity such as time of arrival or target bearing to the recovery of the completewaveform . When a system is designed to recover one or more parameters associated with thesignal , one speaks of signal extraction.
The word signal was not defined and it was assumed that the reader had an intuitive felling for the word. Some elaboration may be in order since the definition of signal subjective and depends on theapplication . One may say that ?signal? is what one wants to observe and noise is anything that obscures the observation. Thus, a tuna fisherman who is searching the ocean with the aid of sonar equipment will be overjoyed with sounds that are impairing the performance of a nearby sonar system engaged in tracking a submarine. Quite literally, one man?s signal is another man?s noise.
Signals come in all shapes and forms. In active sonar system one may use simple sinusoidal signals of fixed duration and modulations thereof. There are impulsive signals such as those made with
explosions or thumpers. At the other extreme one may make use of pseudorandom signals. In passive systems, the signals whose detection is sought may be noise in the conventional meaning of the word; noise produced by propellers or underwater swimmers, for example. It should be evident that one of our problem will be the formulation of mathematical techniques that can be used to describe the signal. Although the source in an active sonar search system may be designed to transmit a signal known shape, there is no guarantee that the return signal whose detection is sought will be similar. In fact , there are many factors to change the signal. The amplitude loss associated with inverse spherical
spreading is most unfortunate for the detection system nut it does not entail any distortion of the wave shape . (Incidentally, where the wave can be approximated locally as a plane wave.) The acoustic medium has an attenuation factor , which depends on the frequency . This produces a slight distortion of the wave shape and a corresponding change in the energy spectrum of the pulse. The major changes in the waveform result from acoustic boundaries and inhomogeneities in the medium.
When echoes are produced by extended targets such as submarines, there are two distinct ways in which echo structure is affected. First, there is the interference between reflections from the different leads to a target strength that fluctuates rapidly with changes in the aspect. Secondly, there is the
elongation of the composite echo due to the distribution of reflecting features along the submarines. This means that the duration of the composite echo is dependent in a simple manner on the aspect angle. If T is the duration of the echo from a point scatterer, and L is the length of the submarine, the duration of the returned echo will be T=(2L/c)cosA ,where A is the acute angle between the major axis of the submarine and the line joining the source and the submarine. C is the velocity of sound in the water. Of course, LcosA must be replaced by the beam width of the submarine when A is near.
A final source of pulse distortion is the Doppler shifts produced by the relative motions between the source, and the target (or detector in passive listening) may each have a different velocity relative to the bottom, the variety of effects may be quite large.
水下声波信号
在声纳操作过程中，操作员经常需要对受噪声干扰的信号进行检波。干扰信号可能来自操作员发出信号的反射波或者外部声源的信号。这两种类型的干扰对主动声纳和被动声纳都会造成很大影响。类似的情况在雷达监测、工程类和图像类专业的基本原理都会涉及到。
当你想到信号检测时有多种方法，那么定义一个术语来表示特殊情况便是可行的。当问题的答案是“当前有一个还是一个多个信号？”时，检波一词将被使用。一个系统被设计来为这种问题提供答案--无论是必然性还是偶然性，这就需要谈及假设检验；当一个信号反复出现的情况下，许多系统只被设计提供两个答案：“是的，当前有一个信号”或“不，当前没有信号”。力图将信号分类会使问题复杂化，因为后者的结论将涉及到目标分类。
一般来说，一种检波仪器只被设计在固定的类型和参数下工作，不容易被改变，例如时间积分检波电路和光学检测的辉光示波管。当出现不明信号时，观察者在拒绝或接收信号方面有所迟疑。在这种情况下，操作员会有种感觉如果检波电路或者示波管能够延长时间那么他就能下结论该信号是否存在。沃尔德（1950）在他的检波理论系统阐述了这种直觉。如果（一个检测检测方法）能够主动去改变时间间隔并在接收系统里储存数据以便达到确定的某一水平，这就是顺序检测。
一般不仅能够确定信号存在与否，而且还能确定一个或多个与信号关联的参数。在还原完整波形时我们所感兴趣的参数在各简单分量间有很大差别，例如信号的到达时间和相位。 当一个系统被设计来提取一个或多个信号参数时，这就是信号抽取。
信号一词并没有明确的定义，只是在读者对它有直观了解时的一种假设。有些较为详细的解释为了对信号一词进定义可能导致是比较主观的或者狭隘与所应用的条件。也许你会说信号就是你想观察到的而噪声就是对观察者产生干扰的信号。但是，一个渔民在用声纳设备搜索海洋时，附近用来追踪潜艇的声纳干扰导致的信号削减常常会使他欣喜若狂。毫不夸张地说，一个人的信号将会是另一个人的噪声。
信号的形式和构成是多种多样的。在主动声纳系统中，可以利用相关的固定宽度和调制正弦信号。类似的有脉冲信号，例如爆炸或者撞击。在一些极端的情况可以利用伪随机信号。在被动声纳系统中，例如螺旋桨或潜泳者发出的噪声。很明显，如何利用数学公式的方法来描述一个信号成为了我们所面临的问题。
即是在主动声纳系统中的超声波发射器传播已知波形的信号，但无法保证检测后查找出来的反射信号也是类似的波形。振幅和反向球面传播信号失去关联是检波系统最不利的情况，因为它无法承担任何波形畸变。（偶然地，这种事件的乐观情况并不适用于2维波，除非它传播到足够远的地方，可以近似认为是平面波。）声波的传导介质会对其造成衰减，（衰减的程度）取决于声波的频率。这就造成了少量的波形失真和对脉冲波形能谱造成相当的改变。主要的改变还是由于波形的边缘效应和传播介质的不均匀所引起的。
当反射波是由外部物体例如潜艇所发出的，这时反射波的结构主要受两种不同方式的影响，第一，由两种反射信号之间的干扰导致外界声源的强度与跟随相位的改变迅速波动，第二，合成反射波的延伸是沿着（来自）潜艇反射的散布特征，这就意味着持续时间取决于相位角的简单特征。如果T是反射波由一个点扩散的持续时间，L是潜艇的长度，那么反射波的回射时
间就是 ， 是潜艇主轴和声纳拖曳线之间的夹角（锐角），C则是声音在水中的传播速率。当然，当 接近的时候 必须用潜艇的宽度代入。
最后一个造成脉冲波形失真的原因声源，船体，介质，目标之间相对运动所造成的多普勒效应。由于声源，介质，目标（或者被动接收器的探测端）相对于船体都有不通的速度向量，所以各种因素的影响之间的区别也很大。
第五章课后
A random erroris due to acontrolled，
large number of independent small effects that cannothe identified orit is a statistical quantity. As such，iteach replication of the observations. If a large number of readings is
will vary for the same quantity.the scatter of the data about a mean value can be evaluated.
The scatter generally follows a guassian distribution about a mean value.which
is assumed to be the true value.
Accuracy is the deviation of the output from the calibration input or the true
value. If the accuracy of a voltmeter is 2% full scale as described in the preceding section·the maximum deviation i、士2units for all readings.
一个随机误差是由于控制,大量的独立影响小,不能他发现或
这是一个统计量。因此,它每个复制的观察。如果大量的读数是 同样数量的不同而不同。散射的数据值可以评估。散高斯分布通常遵循关于意味着value.which被认为是真正的价值。准确性是偏差的输出的输入或真正的校准价值。如果把电压表的准确性2%全面描述在前面的
部分·最大偏差我,士2units所有阅读资料。
第五章.Noncontact Temperature Measurement
Any object at any temperature above absolute zero radiates energy. This radiationvaries both in intensity and in spectral distribution with temperature.Hence.temperature may be deduced by measuring either the intensity or the spectrum of theradiation.
The total energy density radiating from an ideal?blackbody?(more on that later) isgiven by the Stefan-boltzmann law·E=6T'·where E is energy density in W/cmz.6 Isthe Stefan-boltzmann constant(5. 6697 X 10 'z W/cmz K?)and T is the absolutetemperature(K).In other words·the total radiated energy is proportional to the fourthpower of the absolute temperature.
A11 objects.particularly ideal blackbody objects.also absorb incident radiation.
(Uiven time to equilibrate.and presuming they are insulated from the heating or cooling
effects of surrounding air or other materials.they will eventually reach a point where
they absorb and radiate energy at equal rates. ()ne consequence of this is that if an object
(a temperature sensor.for example) is an ideal blackbody.is perfectly insulated.and is
flooded on its entire surface with radiation from a radiating source.it will eventually
reach an equilibrium sources and blackbody calibration sources are available).the temperature of the sensor is a measure of the temperature of the radiating object.
任何物体在任何温度高于绝对零度的辐射能量。这种辐射无论是在不同强度和在光谱分布和温度。因此。通过测量温度可以推导出要么强度或频谱的辐射。总能量密度辐射从理想'blackbody”(稍后详细介绍)
鉴于法律的Stefan-boltzmann·E = 6 T '·E在是能量密度在W / cmz。 6Stefan-boltzmann的常数(5。 6697 X 10 ' z W / cmz K”)和T是绝对的温度(K)。换句话说·总辐射能量是成正比的第四
绝对温度的力量。A11对象。特别是理想黑体对象。也会吸收入射辐射。(Uiven时间一致。和他们隔绝放肆的加热或冷却周围空气的影响或其他材料。他们最终会达到一个临界点他们吸收和辐射能量在相同的利率。()东北的后果是,如果一个对象(一个温度传感器。例如)是一种理想的黑体。是完全绝缘。和是在整个表面淹没与辐射发射源。它最终将达到平衡来源和黑体校正源可用),温度传感器是一个测量辐射的温度对象。
An infrared radiation thermometer may be created in a manner similar to that inFigure 1 the radiated energy from the hot(or cold) object is focused on a temperaturesensor.whose temperature then is indicative of the intensity of the radiation falling uponit. The sensor should be small and low mass for reasonable response time. Thermistorsoffer high sensitivity for low temperature measurements while thermocouples providethe operating range necessary for high levels of radiated energy. In some designs.thesensor is insulated from ambient conditions by placing it in a vacuum. The sensor's output is amplified.linearized.and fed to an output indicator or recorder.
The optics are apt to be a bit different than shown in diagram. In mostapplications.particularly at lower temperatures.much of the radiation will be farinfrared.which is not passed well by most glasses. It may be preferable to use areflective concave mirror to focus the incoming energy.rather than a lens. There mayalso be a red or infrared filter over the inlet to keep down interference due to strayambient light. For higher temperature use it may be necessary to reduce the totalincoming energy using a gray filter.shutter.or other obstruction. The Stefan-boltzmann law.and the proper operation of thesethermometers.presumes that theradiation is coming from a perfect blackbody' radiator. to oversimplify(and it is not ourintention here to which does not reflect any radiation which may fall upon it. Allincident energy is absorbed. A non-blackbody object which reflects external radiation will also reflect internally generated radiation.lowering the amount of energy radiated atany given temperature.
红外辐射温度计可以创建的方式类似,在图1的辐射能量从热(或冷)对象都聚焦在一个温度传感器。其温度然后表明辐射强度落它。应该是小的传感器和低质量为合理的响应时间。热敏电阻提供高灵敏度低温度的测量而热电偶提供必要的工作范围为高水平的辐射能量。在一些designs.the传感器是隔绝外界条件下通过将它放置在真空中。传感器的amplified.linearized输出。 和美联储到输出指标或录音机。光学往往稍有不同,图中所示。在大多数应用程序。特别是在较低的温度下。大部分的辐射将远红外线。这不是大多数眼镜了。这可能比使用 凹面镜反射来聚焦入射能量。而不是一个镜头。也许也是一个红色或红外过滤器在进口为了压制干扰由于流浪 环境光。温度较高的使用可能需要减少总传入的能源使用灰色filter.shutter。 或其他阻塞Stefan-boltzmann的法律。 和适当的操作这些温度计。是假定辐射是来自一个完美的黑体的散热器。粗略的(和它不是我们的 这里的意愿,没有反映出任何辐射可能落在它。所有入射能量被吸收。一个non-blackbody对象反映外部辐射 也将反映出内部产生的辐射。降低辐射的能量在任何给定的温度。
Any surface has a reflectivity and an emissivity. Reflectivity，r，is simply the ratioof reflected energy to incident energy:a perfect reflector has a reflectivity of one;ablackbody，zero. Emissivity，。，turns out to b simply。=1一re,fZecl:二:Cy reflectivity. Aperfect blackbody has emitted by an object at a given temperature is proportional to itsemissivity:a reflectivity object has emissivity(we expect more heat from a rough，blackradiator than from a smooth，polished one). All this has a serious impact on radiation thermometry. An infrared radiationthermometer calibrated against a blackbody radiator will read seriously low when aimedat a reflective object .Most commercial radiation thermometers include a controlallowing the user to dial in the emissivity of the object being measured，plus a table oftypical emissivity values.Mist organic and nonmetallic materials have emissivity values.Most organic and nonmetallic materialshave emissivities between 0. 85 and 0. 95，whilemetals range roughly between 0. 1 and 0. 5(interestingly，both white and black paintshave similar emissivitie、一between 0. 9-at temperatures up to 1000C).
任何表面具有反射率和发射率。反射率r,是简单的比率反射入射能量的能量:一个完美的反射器有一个反射率的;一个黑体,零。辐射率(。其实,b简单。= 1一re,fZecl:二:Cy反射率。一个完美的黑体物体所发出了在给定温度是成正比的辐射率:反射率对象有辐射率(我们希望更多的热量从粗糙的、黑色的散热器比从光滑、磨光的一个)。 所有这一切都有严重影响辐射测温。红外辐射对一个黑体温度计校准散热器将认真读书目的时低在反思对象。大多数商业辐射温度计包括控制允许用户来定下的热辐射特性被测对象,再加上一个表典型的辐射值。雾有机和非金属材料有辐射值。大多数有机和非金属材料有emissivities介于0。85年和年0。95年的时候,金属范围大致在0。1和0。5(有趣的是,两个白色和黑色颜料也有类似的emissivitie,一between 0。 9-at温度可达1000摄氏度)。
Variations in emissivitiy can cause serious errors，especially with metal surfaces.Highly polished surfaces have lower emissivity still farther. As an oxidation or coatingof the surfaces raises emissivity still farther. As an example，the emissivity of stainlesssteel at 8000C is when polished，0. 5 when rough machined，0. 7 when rough machinedand lightly oxidized and 0. 8 to 0. 9 when heavily oxidized. If at all possible， the surfaceto be measured should be painted.oxidized.or otherwise made black and noeflective.Liquid metals.a frequent application for infrared thermometry.are not as variable ittheir emissivity.but may be affected by layers of slag on their surface. It is a good ideato calibrated the infrared reading by making a contact temperature measurement or.it the case of liquid metal.by plunging in a thermocouple as described in the previoussection.
Also affecting the readings are atmospheric attenuation. Water vapor stronglyattenuates certain infrared wavelengths while dust smoke.and particulate matter wilattenuate the radiation between the source and the sensor. Such problems are apt to bemost troublesome in industrial applications.
emissivitiy变化可以导致严重的错误,尤其是在金属表面。高度抛光表面发射率低到更远。作为氧化或涂层 表面发射率的提高到更远。作为一个例子,辐射率的不锈钢钢铁8000 C是当抛光,0。5当粗糙的加工,0。7当粗糙的加工和轻氧化,0。8为0。9当严重氧化。如果可能的话,应该painted.oxidized surfaceto被测量。 或用其他的黑色和以及非反射。液态金属。一个频繁的应用程序为红外测温。不像变量
他们的发射率。但可能会受层渣在其表面。这是一个好主意对校准红外阅读通过使接触or.it温度测量
此案的液态金属。在一个热电偶大跌之前描述的那样部分。阅读资料也影响大气衰减。水蒸气强烈衰减某些波长红外线虽然灰尘烟。和颗粒物会衰减之间的辐射来源和传感器。这类问题是容易的摘要在工业应用中最麻烦的。
The dependence of the measurement upon emissivity can be reduce by the use otwo-color pyrometry. As was mentioned at the start of this section.both the intensityand the spectral distribution of the radiation vary with temperature. The radianintensity at any wavelength.几.is given by:
’C }以
J-一一一，二二一一二二干下尸一一一丁
expl l,}/入1一1Where J is the radiant energy·。is the emissivity·} is the wavelength·and T is theabsolute temperature(K).On the assumption that emissivity is not a function owavelength(this assumption isnot entirely true)the ratio of intensities at twcwavelengths becomes: 测量的依赖性在辐射率可以减少使用o
双色印铁测温。就像前面说过的在这一部分的开始。磁性的强度和光谱分布的辐射随温度。弧度
在任何wavelength.几强度。 给出:' C }以
J-一一一,二二一一二二干下尸一一一丁expl l,} /入1一1这里J是辐射能·.辐射率·}的是波长·和T是吗 绝对温度(K)。假设辐射率不是一个函数o波长(这种假设并不完全正确)的比例在twc公司的强度波长变得:测量的依赖性在辐射率可以减少使用o双色印铁测温。就像前面说过的在这一部分的开始。磁性的强度和光谱分布的辐射随温度。弧度在任何wavelength.几强度。 给出:' C }以
J-一一一,二二一一二二干下尸一一一丁expl l,} /入1一1这里J是辐射能·.辐射率·}的是波长·和T是吗 绝对温度(K)。假设辐射率不是一个函数o波长(这种假设并不完全正确)的比例在twc公司的强度波长变得:几.几
/巨expCC=/J}，T>一y
/巨expCC=/J}=T)一y
一一
大一大
Which may be simplified to
=(consl)只exp
大一大
where
cn77s/
〔丫)7了sC
(几:/几)’
C}(lid。一1/J},)
第6章课后习题
3.Uncertainty is generally stated as a number·indicating the tolerance from the true value of the measurand. T he tolerance is only estimated. It represents theconfidence level of the investigator in the results.since the true value of themeasurement is unknown. he purpose of the sensor is to obtain dimensional information from theworkpiece. 。不确定性是一般表述数量表示宽容的·过热蒸气的真实价值。他宽容只是估计T。它代表了信心水平的调查员在结果中。自从的真正价值
测量是未知的。他的目的是获取维度信息的传感器从theworkpiece。
4. It is like a transducer in many instances because it converts oneenergy form to another. This other energy form is always an electrical signal.since we are considering sensors which provide an
篇二：测控技术与仪器专业英语课后阅读翻译
第五章课后
A random erroris due to acontrolled，
large number of independent small effects that cannothe identified orit is a statistical quantity. As such，iteach replication of the observations. If a large number of readings is
will vary for the same quantity.the scatter of the data about a mean value can be evaluated.
The scatter generally follows a guassian distribution about a mean value.which
is assumed to be the true value.
Accuracy is the deviation of the output from the calibration input or the true
value. If the accuracy of a voltmeter is 2% full scale as described in the preceding section·the maximum deviation i、士2units for all readings.
一个随机误差是由于控制,大量的独立影响小,不能他发现或
这是一个统计量。因此,它每个复制的观察。如果大量的读数是 同样数量的不同而不同。散射的数据值可以评估。散高斯分布通常遵循关于意味着value.which被认为是真正的价值。准确性是偏差的输出的输入或真正的校准价值。如果把电压表的准确性2%全面描述在前面的
部分·最大偏差我,士2units所有阅读资料。
第五章.Noncontact Temperature Measurement
Any object at any temperature above absolute zero radiates energy. This radiationvaries both in intensity and in spectral distribution with temperature.Hence.temperature may be deduced by measuring either the intensity or the spectrum of theradiation.
The total energy density radiating from an ideal?blackbody?(more on that later) isgiven by the Stefan-boltzmann law·E=6T'·where E is energy density in W/cmz.6 Isthe Stefan-boltzmann constant(5. 6697 X 10 'z W/cmz K?)and T is the absolutetemperature(K).In other words·the total radiated energy is proportional to the fourthpower of the absolute temperature.
A11 objects.particularly ideal blackbody objects.also absorb incident radiation.
(Uiven time to equilibrate.and presuming they are insulated from the heating or cooling
effects of surrounding air or other materials.they will eventually reach a point where
they absorb and radiate energy at equal rates. ()ne consequence of this is that if an object
(a temperature sensor.for example) is an ideal blackbody.is perfectly insulated.and is
flooded on its entire surface with radiation from a radiating source.it will eventually
reach an equilibrium sources and blackbody calibration sources are available).the temperature of the sensor is a measure of the temperature of the radiating object.
任何物体在任何温度高于绝对零度的辐射能量。这种辐射无论是在不同强度和在光谱分布和温度。因此。通过测量温度可以推导出要么强度或频谱的辐射。总能量密度辐射从理想'blackbody”(稍后详细介绍)
鉴于法律的Stefan-boltzmann·E = 6 T '·E在是能量密度在W / cmz。 6Stefan-boltzmann的常数(5。 6697 X 10 ' z W / cmz K”)和T是绝对的温度(K)。换句话说·总辐射能量是成正比的第四
绝对温度的力量。A11对象。特别是理想黑体对象。也会吸收入射辐射。(Uiven时间一致。和他们隔绝放肆的加热或冷却周围空气的影响或其他材料。他们最终会达到一个临界点他们吸收和辐射能量在相同的利率。()东北的后果是,如果一个对象(一个温度传感器。例如)是一种理想的黑体。是完全绝缘。和是在整个表面淹没与辐射发射源。它最终将达到平衡来源和黑体校正源可用),温度传感器是一个测量辐射的温度对象。
An infrared radiation thermometer may be created in a manner similar to that inFigure 1 the radiated energy from the hot(or cold) object is focused on a temperaturesensor.whose temperature then is indicative of the intensity of the radiation falling uponit. The sensor should be small and low mass for reasonable response time. Thermistorsoffer high sensitivity for low temperature measurements while thermocouples providethe operating range necessary for high levels of radiated energy. In some designs.thesensor is insulated from ambient conditions by placing it in a vacuum. The sensor's output is amplified.linearized.and fed to an output indicator or recorder.
The optics are apt to be a bit different than shown in diagram. In mostapplications.particularly at lower temperatures.much of the radiation will be farinfrared.which is not passed well by most glasses. It may be preferable to use areflective concave mirror to focus the incoming energy.rather than a lens. There mayalso be a red or infrared filter over the inlet to keep down interference due to strayambient light. For higher temperature use it may be necessary to reduce the totalincoming energy using a gray filter.shutter.or
other obstruction. The Stefan-boltzmann law.and the proper operation of thesethermometers.presumes that theradiation is coming from a perfect blackbody' radiator. to oversimplify(and it is not ourintention here to which does not reflect any radiation which may fall upon it. Allincident energy is absorbed. A non-blackbody object which reflects external radiation will also reflect internally generated radiation.lowering the amount of energy radiated atany given temperature.
红外辐射温度计可以创建的方式类似,在图1的辐射能量从热(或冷)对象都聚焦在一个温度传感器。其温度然后表明辐射强度落它。应该是小的传感器和低质量为合理的响应时间。热敏电阻提供高灵敏度低温度的测量而热电偶提供必要的工作范围为高水平的辐射能量。在一些designs.the传感器是隔绝外界条件下通过将它放置在真空中。传感器的amplified.linearized输出。 和美联储到输出指标或录音机。光学往往稍有不同,图中所示。在大多数应用程序。特别是在较低的温度下。大部分的辐射将远红外线。这不是大多数眼镜了。这可能比使用 凹面镜反射来聚焦入射能量。而不是一个镜头。也许也是一个红色或红外过滤器在进口为了压制干扰由于流浪 环境光。温度较高的使用可能需要减少总传入的能源使用灰色filter.shutter。 或其他阻塞Stefan-boltzmann的法律。 和适当的操作这些温度计。是假定辐射是来自一个完美的黑体的散热器。粗略的(和它不是我们的 这里的意愿,没有反映出任何辐射可能落在它。所有入射能量被吸收。一个non-blackbody对象反映外部辐射 也将反映出内部产生的辐射。降低辐射的能量在任何给定的温度。
Any surface has a reflectivity and an emissivity. Reflectivity，r，is simply the ratioof reflected energy to incident energy:a perfect reflector has a reflectivity of one;ablackbody，zero. Emissivity，。，turns out to b simply。=1一re,fZecl:二:Cy reflectivity. Aperfect blackbody has emitted by an object at a given temperature is proportional to itsemissivity:a reflectivity object has emissivity(we expect more heat from a rough，blackradiator than from a smooth，polished one). All this has a serious impact on radiation thermometry. An infrared radiationthermometer calibrated against a blackbody radiator will read seriously low when aimedat a reflective object .Most commercial radiation thermometers include a controlallowing the user to dial in the emissivity of the object being measured，plus a table oftypical emissivity values.Mist organic and nonmetallic materials have emissivity values.Most organic and nonmetallic materialshave emissivities between 0. 85 and 0. 95，whilemetals range roughly between 0. 1 and 0. 5(interestingly，both white and black paintshave similar emissivitie、一between 0. 9-at temperatures up to 1000C).
任何表面具有反射率和发射率。反射率r,是简单的比率反射入射能量的能量:一个完美的反射器有一个反射率的;一个黑体,零。辐射率(。其实,b简单。= 1一re,fZecl:二:Cy反射率。一个完美的黑体物体所发出了在给定温度是成正比的辐射率:反射率对象有辐射率(我们希望更多的热量从粗糙的、黑色的散热器比从光滑、磨光的一个)。 所有这一切都有严重影响辐射测温。红外辐射对一个黑体温度计校准散热器将认真读书目的时低在反思对象。大多数商业辐射温度计包括控制允许用户来定下的热辐射特性被测对象,再加上一个表典型的辐射值。雾有机和非金属材料有辐射值。大多数有机和非金属材料有emissivities介于0。85年和年0。95年的时候,金属范围大致在0。1和0。5(有趣的是,两个白色和黑色颜料也有类似的emissivitie,一between 0。 9-at温度可达1000摄氏度)。
Variations in emissivitiy can cause serious errors，especially with metal surfaces.Highly polished surfaces have lower emissivity still farther. As an oxidation or coatingof the surfaces raises emissivity still farther. As an example，the emissivity of stainlesssteel at 8000C is when polished，0. 5 when rough machined，0. 7 when rough machinedand lightly oxidized and 0. 8 to 0. 9 when heavily oxidized. If at all possible， the surfaceto be measured should be painted.oxidized.or otherwise made black and noeflective.Liquid metals.a frequent application for infrared thermometry.are not as variable ittheir emissivity.but may be affected by layers of slag on their surface. It is a good ideato calibrated the infrared reading by making a contact temperature measurement or.it the case of liquid metal.by plunging in a thermocouple as described in the previoussection.
Also affecting the readings are atmospheric attenuation. Water vapor stronglyattenuates certain infrared wavelengths while dust smoke.and particulate matter wilattenuate the radiation between the source and the sensor. Such problems are apt to bemost troublesome in industrial applications.
emissivitiy变化可以导致严重的错误,尤其是在金属表面。高度抛光表面发射率低到更远。作为氧化或涂层 表面发射率的提高到更远。作为一个例子,辐射率的不锈钢钢铁8000 C是当抛光,0。5当粗糙的加工,0。7当粗糙
的加工和轻氧化,0。8为0。9当严重氧化。如果可能的话,应该painted.oxidized surfaceto被测量。 或用其他的黑色和以及非反射。液态金属。一个频繁的应用程序为红外测温。不像变量
他们的发射率。但可能会受层渣在其表面。这是一个好主意对校准红外阅读通过使接触or.it温度测量
此案的液态金属。在一个热电偶大跌之前描述的那样部分。阅读资料也影响大气衰减。水蒸气强烈衰减某些波长红外线虽然灰尘烟。和颗粒物会衰减之间的辐射来源和传感器。这类问题是容易的摘要在工业应用中最麻烦的。
The dependence of the measurement upon emissivity can be reduce by the use otwo-color pyrometry. As was mentioned at the start of this section.both the intensityand the spectral distribution of the radiation vary with temperature. The radianintensity at any wavelength.几.is given by:
’C }以
J-一一一，二二一一二二干下尸一一一丁
expl l,}/入1一1Where J is the radiant energy·。is the emissivity·} is the wavelength·and T is theabsolute temperature(K).On the assumption that emissivity is not a function owavelength(this assumption isnot entirely true)the ratio of intensities at twcwavelengths becomes: 测量的依赖性在辐射率可以减少使用o
双色印铁测温。就像前面说过的在这一部分的开始。磁性的强度和光谱分布的辐射随温度。弧度
在任何wavelength.几强度。 给出:' C }以
J-一一一,二二一一二二干下尸一一一丁expl l,} /入1一1这里J是辐射能·.辐射率·}的是波长·和T是吗 绝对温度(K)。假设辐射率不是一个函数o波长(这种假设并不完全正确)的比例在twc公司的强度波长变得:测量的依赖性在辐射率可以减少使用o双色印铁测温。就像前面说过的在这一部分的开始。磁性的强度和光谱分布的辐射随温度。弧度在任何wavelength.几强度。 给出:' C }以
J-一一一,二二一一二二干下尸一一一丁expl l,} /入1一1这里J是辐射能·.辐射率·}的是波长·和T是吗 绝对温度(K)。假设辐射率不是一个函数o波长(这种假设并不完全正确)的比例在twc公司的强度波长变得:几.几
/巨expCC=/J}，T>一y
/巨expCC=/J}=T)一y
一一
大一大
Which may be simplified to
=(consl)只exp
大一大
where
cn77s/
〔丫)7了sC
(几:/几)’
C}(lid。一1/J},)
第6章课后习题
3.Uncertainty is generally stated as a number·indicating the tolerance from the true value of the measurand. T he tolerance is only estimated. It represents theconfidence level of the investigator in the results.since the true value of themeasurement is unknown. he purpose of the sensor is to obtain dimensional information from theworkpiece. 。不确定性是一般表述数量表示宽容的·过热蒸气的真实价值。他宽容只是估计T。它代表了信心水平的调查员在结果中。自从的真正价值
测量是未知的。他的目的是获取维度信息的传感器从theworkpiece。
4. It is like a transducer in many instances because it converts oneenergy form to another. This other energy form is always an electrical signal.since we are considering sensors which provide an electrical signal to be used asfeedback to the process or machine control.
它就像一个传感器在许多情况下,因为它转换为一个能源形式到另一个。这其他能源形式总是一个电信号。 因为我们正在考虑传感器提供一个电信号作为反馈过程或机器的控制。
第六章Eddy Current(Readihg Material)
The eddy current sensor is similar in concept and performance to the capacitive
sensor. It does have some differences·though·that may make it more suitable in some
applications. The major difference between the two sensors is the principle of operation.
The eddy current sensor utilizes an electromagnetic field as opposed to the capacitive electric field. It is the electromagnetic field that makes this noncontacting
sensor much less sensitive to the effect of excited by a high-frequency alternating-current
source. The resultant alternating magnetic field emanating from the coil generates eddy
currents in the near surface of the material being inspected. These currents.in turn.
create their own magnetic field.which couples to the coil.superimposing a current on
the driving current. Demodulating circuitry detects this current signal.which can be
calibrated to derive a distance is possible since the field strengths are a function of the distance from the sensor to the target.
电涡流传感器在概念上是类似和性能的电容
传感器。它有一些差异··但可能更适合在一些
应用程序。这两者之间最大的不同在于传感器操作的原则。
电涡流传感器利用电磁场的反对
电容式电场。这是使这noncontacting电磁场
传感器不太敏感的影响高频交流电兴奋不已
源。由此产生的交变磁场散发的线圈生成艾迪
电流的近表面的材料被检查。这些电流。反过来。
创建他们自己的磁场。这夫妇线圈。叠加一个电流
驱动电流。检测电流信号的解调电路。可以
校准中派生出的距离是可能的因为这个领域的优势是一个函数
距离从传感器到目标。
Progressing required for the analog output of this type of sensor is identical to that
for the capacitive sensor. Resolution is limited by the A/D converter. Spot size.range.
and standoff distance are comparable to those available in a capacitive device. A conductive work piece is required to support the induced currents. Concerning spot size.the eddy current probe has limitations in terms of how small a
coil.with enough turns to generate a sufficient magnetic field.can be wound. Since
fringe fields have an effect on the output.the eddy current probe is also limited to
constant-geometry situations where these errors can be determined and calibrated out.
Since this device depends on eddy currents.which are a near-surface phenomenon·there
are other variables peculiar to this sensor that must understood.
The strength of the induced magnetic field is a function of the condition of the
material. Because different materials have different resistivities.the sensor must be
calibrated for a specific material. In addition.other material characteristics such as
porosity and density affect the output. Near-surface conditions including defects such as
cracks or inclusions alter the output and may be indistinguishable from changes in the
distance being measured. Indeed.the primary use of this type of sensor is for surface
and near-surface material defects.to which it is very sensitive. iJltrasound
Sound waves can be utilize by ranging to obtain dimensional information. The configuration of the sensor involves a transmitter of sound energy and receiver. In many
cases the transmitter and receiver are in the same unit. Distance information is obtained
by measuring the transit time required for the echo the return. Since the speed of sound
in the medium is known, distance can be determined directly from time-of-flight information.
进步的模拟输出所需的这种类型的传感器是一致的
电容式传感器的。决议是有限的,由A / D转换器。size.range现货。
和靶距同电容装置中可用。一个
导电工件必须支持诱发的电流。关于现货大小。电涡流探测器方面的限制如此小的一段
线圈。有足够的转向生成足够的磁场。可以伤口。自从
边缘领域影响输出。电涡流探头也仅限于
constant-geometry这些错误的情况下可以确定和校准出来。
因为这个设备取决于涡流。这是一个近地表现象?
其他变量所特有的,这种传感器,必须理解。
强度的感应磁场是一个函数的状况
材料。因为不同的材料有不同的电阻率。传感器必须
校准,为特定的材料。此外。其他材料等特点
孔隙率和密度影响输出结果。近地表条件包括等缺陷
裂缝或包裹体改变输出和可能与改变
距离被测量。事实上。主要使用这种类型的传感器是表面的
和近地表材料缺陷。它是非常敏感的。iJltrasound
声波可以利用测距获取维度信息。传感器的配置包括发射机和接收机的声音的能量。在许多
情况下,发送器和接收器在同一个单元。距离信息被获取
通过测量交通所需时间回声返回。因为声音的速度
在中是已知的,距离可以直接从tofms决定
信息。
Ultrasonic energy.which is beyond the audible frequency range.is normally utilized since the wavelength of audible sound energy is relatively long compared with
the resolution required for most dimensional measurements.For higl:一resolution applications.with measurement resolutions finer than 0. 1 in. , a liquid couplant (typically water) is required because the sound energy at the higher frequencies is highly
attenuated in air. In an inprocess measurement application.water-or oil-based cutting
fluids can serve as a coupling medium. The workpiece under measurement need not be
immersed as a continuous stream of liquid can adequately convey the sound. The transmitter/receiver for an ultrasonic sensor is typically
The crystal itself is mechanically damped in order to attenuate
a piezoelectric crystal.
oscillation and avoid
masking the weak incoming echoes. The pulser is a fast.higl:一voltage switch that drives
the transducer with a short rise time pulse that is converted into a mechanical pressure
wave. The longitudinal sound wave is conveyed by the medium to the target.where it is
reflected back to the transducer. The same crystal or an identical one converts the echo
to an electrical impulse.which is amplified by a tuned
A timer is generally triggered by the pulse unit
amplifier.
and disabled by receipt of the
incoming echo. The value held by the timer is the time of flight of the sound wave.that
is.the time it takes the sound is constant for homogenous materials at a fixed temperature.the distance to the target can be determined by multiplying the speed by
the time and dividing the result by two to get a single path length. Digital counter/
timers are presently utilized with ultrasonic sensors and provide direct digital information for transmission over serial or parallel data links.
超声能量。那是超越声的频率范围内。通常是
利用自波长的声波能源相对比较长相比
该决议要求对大多数尺寸测量。对于higl:一resolution
应用程序。测量分辨率这些比0。1。,液体耦合剂
(通常是水)是有必要的,因为在高频率的声音的能量是高度
在空气中减毒活疫苗。在一个inprocess测量应用程序。水油性切削
液体可以作为一个耦合介质。在测量工件不需要
作为一个连续的流浸入液体可以充分表达的声音。这个发射器/接收器进行超声波传感器通常是
水晶本身是机械阻尼为了减弱
压电晶体。
振荡和避免
屏蔽弱传入的回声。是一个快速的脉冲源。higl:一voltage开关,驱动器
该传感器与短脉冲上升时间将被转换成一个机械压力
波。纵向声波是靠中长期目标。它在哪里
篇三：测控技术与仪器专业英语阅读翻译
Underwater Acoustic Signal
In the operation of a sonar system the operator is repeatedly faced with the problem of detecting a signal which is obscured by noise. This signal may be an echo resulting from a transmitted signal over which the operator has some control, or it may have its origin in some external source. These two modes of operation arise in radar surveillance and in disciplines for techniques and for illustrations of the basic principles.
Since there are many ways in which one can think about signal detection , it is desirable to define a term to denote special cases . The word detection will be used when the question to be answered is, ‘Are one or more signals present?’ when the system is designed to provide an answered to this question , either deterministic or probabilistic, one speaks of hypothesis testing. The case of a single signal occurs so often that many system are designed to provide only two answers, ‘Yes , a signal is present,’ or ‘No, there is no signal.’ One can make the problem more complicated by endeavoring to classify the signal into categories. Decisions of this latter kind will be referred to as target classification.
Normally a piece of detection equipment is designed to operate in a fixed mode and the
parameters such as integrating time of rectifier circuits or persistence of the oscilloscope tube for visual detection cannot be changed readily. There will always be some uncertain signals, which the observer will be hesitant to reject or accept. In these cases the operator might have the feeling that if the integrating time of the detector or the persistence of the oscilloscope tube were longer, he could reach a decision about the existence of the signal. Wald(1950) has formulated this
intuitive feeling into a theory of detection. When one is able to vary deliberately the interval over which one stores data in the reception system in order to achieve a certain level of certainty, one speaks of sequential detection.
Frequently it is desirable to determine not only the presence or absence of the signal but also one or more parameters associated with the signal . The parameters of interest can vary widely from a simple quantity such as time of arrival or target bearing to the recovery of the complete
waveform . When a system is designed to recover one or more parameters associated with thesignal , one speaks of signal extraction.
The word signal was not defined and it was assumed that the reader had an intuitive felling for the word. Some elaboration may be in order since the definition of signal subjective and depends on theapplication . One may say that ‘signal’ is what one wants to observe and noise is anything that obscures the observation. Thus, a tuna fisherman who is searching the ocean with the aid of sonar equipment will be overjoyed with sounds that are impairing the performance of a nearby sonar system engaged in tracking a submarine. Quite literally, one man’s signal is another man’s noise.
Signals come in all shapes and forms. In active sonar system one may use simple sinusoidal signals of fixed duration and modulations thereof. There are impulsive signals such as those made with explosions or thumpers. At the other extreme one may make use of pseudorandom
signals. In passive systems, the signals whose detection is sought may be noise in the conventional meaning of the word; noise produced by propellers or underwater swimmers, for example. It
should be evident that one of our problem will be the formulation of mathematical techniques that can be used to describe the signal.
Although the source in an active sonar search system may be designed to transmit a signal known
shape, there is no guarantee that the return signal whose detection is sought will be similar. In fact , there are many factors to change the signal. The amplitude loss associated with inverse spherical spreading is most unfortunate for the detection system nut it does not entail any distortion of the wave shape . (Incidentally, where the wave can be approximated locally as a plane wave.) The acoustic medium has an attenuation factor , which depends on the frequency . This produces a
slight distortion of the wave shape and a corresponding change in the energy spectrum of the pulse. The major changes in the waveform result from acoustic boundaries and inhomogeneities in the medium.
When echoes are produced by extended targets such as submarines, there are two distinct ways in which echo structure is affected. First, there is the interference between reflections from the different leads to a target strength that fluctuates rapidly with changes in the aspect. Secondly, there is the elongation of the composite echo due to the distribution of reflecting features along the submarines. This means that the duration of the composite echo is dependent in a simple manner on the aspect angle. If T is the duration of the echo from a point scatterer, and L is the length of the submarine, the duration of the returned echo will be T=(2L/c)cosA ,where A is the acute angle between the major axis of the submarine and the line joining the source and the submarine. C is the velocity of sound in the water. Of course, LcosA must be replaced by the beam width of the submarine when A is near.
A final source of pulse distortion is the Doppler shifts produced by the relative motions between the source, and the target (or detector in passive listening) may each have a different velocity relative to the bottom, the variety of effects may be quite large.
水下声波信号
在声纳操作过程中，操作员经常需要对受噪声干扰的信号进行检波。干扰信号可能来自操作员发出信号的反射波或者外部声源的信号。这两种类型的干扰对主动声纳和被动声纳都会造成很大影响。类似的情况在雷达监测、工程类和图像类专业的基本原理都会涉及到。当你想到信号检测时有多种方法，那么定义一个术语来表示特殊情况便是可行的。当问题的答案是“当前有一个还是一个多个信号？”时，检波一词将被使用。一个系统被设计来为这种问题提供答案--无论是必然性还是偶然性，这就需要谈及假设检验；当一个信号反复出现的情况下，许多系统只被设计提供两个答案：“是的，当前有一个信号”或“不，当前没有信号”。力图将信号分类会使问题复杂化，因为后者的结论将涉及到目标分类。一般来说，一种检波仪器只被设计在固定的类型和参数下工作，不容易被改变，例如时间积分检波电路和光学检测的辉光示波管。当出现不明信号时，观察者在拒绝或接收信号方面有所迟疑。在这种情况下，操作员会有种感觉如果检波电路或者示波管能够延长时间那么他就能下结论该信号是否存在。沃尔德（1950）在他的检波理论系统阐述了这种直觉。如果（一个检测检测方法）能够主动去改变时间间隔并在接收系统里储存数据以便达到确定的某一水平，这就是顺序检测。
一般不仅能够确定信号存在与否，而且还能确定一个或多个与信号关联的参数。在还原完整波形时我们所感兴趣的参数在各简单分量间有很大差别，例如信号的到达时间和相位。
当一个系统被设计来提取一个或多个信号参数时，这就是信号抽取。
信号一词并没有明确的定义，只是在读者对它有直观了解时的一种假设。有些较为详
细的解释为了对信号一词进定义可能导致是比较主观的或者狭隘与所应用的条件。也许你会说信号就是你想观察到的而噪声就是对观察者产生干扰的信号。但是，一个渔民在用声纳设备搜索海洋时，附近用来追踪潜艇的声纳干扰导致的信号削减常常会使他欣喜若狂。毫不夸张地说，一个人的信号将会是另一个人的噪声。
信号的形式和构成是多种多样的。在主动声纳系统中，可以利用相关的固定宽度和调制正弦信号。类似的有脉冲信号，例如爆炸或者撞击。在一些极端的情况可以利用伪随机信号。在被动声纳系统中，例如螺旋桨或潜泳者发出的噪声。很明显，如何利用数学公式的方法来描述一个信号成为了我们所面临的问题。
即是在主动声纳系统中的超声波发射器传播已知波形的信号，但无法保证检测后查找出来的反射信号也是类似的波形。振幅和反向球面传播信号失去关联是检波系统最不利的情况，因为它无法承担任何波形畸变。（偶然地，这种事件的乐观情况并不适用于2维波，除非它传播到足够远的地方，可以近似认为是平面波。）声波的传导介质会对其造成衰减，（衰减的程度）取决于声波的频率。这就造成了少量的波形失真和对脉冲波形能谱造成相当的改变。主要的改变还是由于波形的边缘效应和传播介质的不均匀所引起的。
当反射波是由外部物体例如潜艇所发出的，这时反射波的结构主要受两种不同方式的影响，第一，由两种反射信号之间的干扰导致外界声源的强度与跟随相位的改变迅速波动，第二，合成反射波的延伸是沿着（来自）潜艇反射的散布特征，这就意味着持续时间取决于相位角的简单特征。如果T是反射波由一个点扩散的持续时间，L是潜艇的长度，那么反射波的回射时间就是 ， 是潜艇主轴和声纳拖曳线之间的夹角（锐角），C则是声音在水中的传播速率。当然，当 接近的时候 必须用潜艇的宽度代入。
最后一个造成脉冲波形失真的原因声源，船体，介质，目标之间相对运动所造成的多普勒效应。由于声源，介质，目标（或者被动接收器的探测端）相对于船体都有不通的速度向量，所以各种因素的影响之间的区别也很大。
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《测控技术与仪器专业英语阅读翻译》出自：百味书屋
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