1、测控技术和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 iswill vary for the same quantity.the scatter of the data about a
2、 mean value can be evaluated.The scatter generally follows a guassian distribution about a mean value.whichis assumed to be the true value.Accuracy is the deviation of the output from the calibration input or the truevalue. If the accuracy of a voltmeter is 2% full scale as described in the precedin
3、gsectionthe 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
4、 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 idealblackbody(more on that later
5、) isgiven by the Stefan-boltzmann lawE=6Twhere 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 wordsthe total radiated energy is proportional to the fourthpower of the absolute temperature. A11 objects.particularly id
6、eal blackbody objects.also absorb incident radiation.(Uiven time to equilibrate.and presuming they are insulated from the heating or coolingeffects of surrounding air or other materials.they will eventually reach a point wherethey absorb and radiate energy at equal rates. ()ne consequence of this is
7、 that if an object(a temperature sensor.for example) is an ideal blackbody.is perfectly insulated.and isflooded on its entire surface with radiation from a radiating source.it will eventuallyreach an equilibrium sources and blackbody calibration sources are available).thetemperature of the sensor is
8、 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-boltzmannE = 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
9、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) obje
10、ct 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 operatin
11、g range necessary for high levels of radiated energy. In some designs.thesensor is insulated from ambient conditions by placing it in a vacuum. The sensorsoutput 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 mos
12、tapplications.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 kee
13、p 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 perfec
14、t 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 radiationwill also reflect internally generated radiation.lowering the amount of energy
15、 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
16、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，
17、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 reflectiv
18、ity 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 c
19、ommercial 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
20、 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
21、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，
22、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 lightl
23、y 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 nonreflective.Liquid metals.a frequent application for infrared thermometry.are not as variable ittheir emissivity.but may be affected by layers of
24、slag on their surface. It is a good ideato calibrated the infrared reading by making a contact temperature measurement or.itthe case of liquid metal.by plunging in a thermocouple as described in the previoussection. Also affecting the readings are atmospheric attenuation. Water vapor stronglyattenua
25、tes 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。
26、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 em
27、issivity 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
28、energy。is the emissivity is the wavelengthand T is theabsolute temperature(K).On the assumption that emissivity is not a function owavelength(this assumption is not 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waveleng
29、th.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
30、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wherecn77s/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 numberindicating the tolerance from the true value of the measurand. T he tolerance is only estimated. It represents theconfidence level
31、 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
32、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 capacitivesensor. It does have some differencesthoughthat may make it
