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 absolutetemperat ure(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)。
V ariations 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 nonreflective.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 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
反射回换能器。同样的水晶或等同将呼应
电冲动。这是一个调谐放大了吗
通常一个计时器触发脉冲单元
放大器。
和残疾的收据
传入的回声。持有价值定时器的飞行时间wave.that的声音
是。花费的时间听起来是常数同质材料在一个固定的
温度。距离目标可以确定乘以速度
时间和划分结果由两位得一个路径长度。数字计数器/
计时器是目前利用超声波传感器,提供直接的数字
信息传输串行或并行数据链接。
The spot size of the noncontact ultrasonic sensor is determined by the size of the
wave front of the sound energy. This size id in turn governed by the configuration of the transducer.which may have a lens incorporated to it to permit a focused spot. This spot
size may range from approximately 0. 05 to 1.0 contacting transducers discussed here.
tends to average the information received from the target.
Different form other sensors.however.the returning sound waves reflected from
varying distances to the target integrated over the spot size cause a dispersion of the item
signal which may result in trouble establishing an exact time reading.especially in cases where a constant thresholding circuit encounters varying amplitude signals. This
problem can be overcome .however.when the geometry of the workpiece is known or
when the sensor is kept normal to the workpiece. Under these circumstances.accuracies
for this type of sensor of 0. 0001 to 0. 001 in. can be achieved.
现场的非接触式的大小决定了超声波传感器的尺寸
波前的声音的能量。这个尺寸id反过来由配置的
传感器。这可能有一个镜头融入到其中,它允许一个集中位置。这地方
大小可以从大约0。05到1.0联系这里讨论换能器。
倾向于平均收到的信息从目标。
其他sensors.however形式不同。返回的声波反射
不同距离的目标集成在现货大小造成的分散项目
信号,它可能导致麻烦建立具体时间阅读。特别的情况下,有一个常数电路遇到不同幅度信号的阈值。这
此问题是可以克服的。当几何形状的工件是已知或
当传感器保持正常的工件。在这些circumstances.accuracies
对于这种类型的传感器为0。0001年到0。可以达到001英寸。
现场的非接触式的大小决定了超声波传感器的尺寸
波前的声音的能量。这个尺寸id反过来由配置的
传感器。这可能有一个镜头融入到其中,它允许一个集中位置。这地方
大小可以从大约0。05到1.0联系这里讨论换能器。
倾向于平均收到的信息从目标。
其他sensors.however形式不同。返回的声波反射
不同距离的目标集成在现货大小造成的分散项目
信号,它可能导致麻烦建立具体时间阅读。特别的情况下,有一个常数电路遇到不同幅度信号的阈值。这
此问题是可以克服的。当几何形状的工件是已知或
当传感器保持正常的工件。在这些circumstances.accuracies
对于这种类型的传感器为0。0001年到0。可以达到001英寸。
Standoff distances in the range of a fraction of an inch to tens of feet are possible
with ultrasonic transducers.again.as previously inferred.with a ling standoff distance
and a lower-frequency sound wave·resolution mist be compromised. In a machining application.accuracies mentioned in the previous paragraph may be realized with standoff distances in the range of a fraction of an inch to several inches. Like the eddy
current probe.the ultrasonic sensor has the added benefit of being able to detect material defects. Unlike the eddy current probe.however.this sensor's sound energy
can penetrate more deeply into the material and.by utilizing clever time discrimination
of the resultant echoes.surface measurements may be distinguished from subsurface
material defects.allowing the sensor to be used for both dimensional mensuration and
material integrity of the workpiece.
距离外范围在不到一英寸到数万英尺是可能的
transducers.again超声波。正如前面推断。与一个灵对峙距离
和一个最新的声波·决议被攻陷的薄雾。在加工
应用程序。前项精度可能实现
距离外范围在不到一英寸到几英寸。像艾迪
电流探测器。超声波传感器的额外的好处还能发觉
材料的缺陷。与涡流probe.however。这种传感器的声音的能量
可以深入到材料和。通过利用巧妙的时间歧视
由此出现的回声。地面测量可能是区别于地下
材料的缺陷。允许传感器用于两维测定和
材料工件的完整性。
第七章课后
3.Resolution and accuracy of the sensor are determined by the quality requirements
of the part itself. Resolution is the smallest increment of distance that the sensor
can resolve. In cases where the machine tool encoders are used to read location,
the resolution may be determined by the encoders themselves.
传感器的分辨率和准确性所决定的质量要求
本身的一部分。决议的少量增加距离传感器
可以解决。下机床编码器是用于读取的位置,
该决议也可能取决于自己的编码器。
4. Laset'(Readihg Material)As discussed earlier，sensors can be broken down into four divisions:contact，
noncontact，direction and indirect. No one sensor can be described as being the
best overall，independent of application，since in-process sensing is heavily application dependent.
Laset”(Readihg材料),正如前面所讨论的,传感器可以被分成四个部门:接触,
非接触、方向和间接的。没有一个传感器可以被描述为是
最好最全面的、独立的应用程序,因为进程内感应严重
依赖于应用程序的。
第七章Laset'(Readihg Material)
Several measurement methodologies.all noncontact.are possible using light sources. The utilization of laser light sources has made these methods increasingly
sensitive due to the intensity.monochromaticity.and directionality of the laser beam.
This is happening while the cost of laser light source is decreasing. The two primary approaches to be discussed in this section are the laser triangulator and the shadow
technique.
A traditional device improved by the use of a laser.the interferometer.can be used
as an extremely accurate measurement sensor;however.it is not really suitable for on-
machine use because of its higl:一cost requirement for stability and a secular reflecting surface. In an interferometer configuration.the lasers light beam is divided with a beam
sputter into a measurement beam and a reference beam. The measurement beam is shone
on the object. The reflected return beam is compared with the reference beam through a
phase detector. Since in-phase light waves add constructively.the interferometer acts in
principle like an optical encoder using the monochromatic light beam as an encoder
scale. This enables it to determine relative motion to and from the object under
measurement by counting light…fringes?caused by the alter nating bands from the constructive and destructive interference. Multifrequency and Doppler techniques·
which do not count such fringes.permit absolute measurements.
几种测量方法。所有非接触。可以使用光
来源。利用激光光源使得这些方法越来越多
由于intensity.monochromaticity敏感。激光束的和方向性。
这正在发生,而费用的激光光源正在减少。这两个主要
方法本部分中讨论激光triangulator和阴影
技术。
一个传统的设备改进通过使用激光。干涉仪。可以使用
作为一个十分精确的测量传感器;然而。它不太适合在- - -
机器使用,因为其higl:一cost要求稳定和长期的反映
表面。在干涉仪的配置。激光光束除以一束
溅射到测量梁和参考光束。测量光束照射
在对象上。反射的光束返回比参考光通过一个
相位检测器。自同步光波建设性地添加。干涉仪的行为
原理像光学编码器使用单色光束作为一个编码器
规模。这使它来确定相对运动和从下的对象
通过计算'fringes测量光的'caused交替的乐队
建设性的和破坏性的干扰。多频和多普勒技术·
这不算这样的边缘。允许绝对测量。
Using the interferometer approach.practical resolutions to 0. 000001 in.
achievable with a standoff distance of a fraction of an inch and no theoretical upper limit.
In reality·intensity of ht laser·refraction of the light·and changes in the speed of light
over long distances through the medium(the latter due to thermally induced changes in
density in the primary medium.air)limit n the standoff to several feet. For reasons
discussed here .mainly lack of ruggedness and sensitivity.the laser interferometer has
not found widespread use as an in-process measurement sensor. However, because of its extreme accuracy and resolution·the interferometer is being utilized to set up and calibrate machine tools and coordinate measuring machines. Improvements in this technique.such as those made by Hewlett-packard to reduce the sensitivity to atmospheric changes.are making interferometer usage more widespread.
The two laser-based techniques that have been applied successfully as sensors operate on different principles.although both use the laser as a light source. The laser
shadow gauge senses the blockage of a beam of scanned light .whereas the laser triangulator measures a spatial shift in reflected or scattered light to provide a
measurement. Both type of sensors have a high degree of accuracy with reasonable
standoff distances and small spot sizes.
使用干涉仪的方法。实际的决议为0。000001年。
达到靶距的一小部分一英寸,没有理论上限。
在现实中·强度的激光的ht·折射光·和改变光的速度
远距离通过介质(后者由于热引起的变化
在初选medium.air密度)限制n对峙到几英尺。原因
这里所讨论的。主要是缺乏个性和灵敏度。激光干涉仪已经
没有找到广泛用作一个进程内测量传感器。然而,因为它的
极端的准确度和分辨率·干涉仪是被用来设置和
校准机器工具和坐标测量机等。改善这
技术。比如那些由惠普降低敏感性
大气变化。正在使用更为普遍。干涉仪
这两个激光技术,已经成功应用于传感器
使用不同的原则。虽然两者都使用激光作为光源。激光
影子判断感官的封锁一束光扫描。而激光triangulator措施空间转变散射光反射或提供
测量。两种类型的传感器具有高度的合理的准确性
距离外和小斑点大小。
Because of the configuration of this type of sensor.only features which are strictly
convex can be measured. ()they features may be shadowed by the part geometry itself. preventing measurement. Accuracies down to 0. 000 Ol are achievable with this type of noninterferometric system. The field of view of the sensor is limited to the size of the
lenses utilized.which for commercial units may range from 2 to 6. If larger objects of
variable size must be measured.the sensors may be adapted to a positioning system.
Where objects of fixed size larger than the lenses are encountered.a configuration of
multiple sensors or single sensors with beamsplitters and mirrors may be constructed.
The standoff distance of the shadow gauge is relatively large compared with that of
other noncontacting sensors. This distance can be in the range of 10 in. for the accuracy previously stated. Although theoretically very large.the standoff distance is limited by
the accuracy of the lenses used to refract the light into parallel rays over the field of
view. Moreover.at large distances conditions that affect the interferometer, such as atmospheric disturbances.will also affect this type of system
由于配置这种类型的传感器。只有这些特性被严格
凸是可以衡量的。()他们功能可能被蒙上阴影部分几何图形本身。
预防措施。降至0精度。000年是可以达到的Ol与这种类型的
noninterferometric系统。观测的区域传感器是有限的规模
利用镜头。这对于商业单位可以从2到6。如果大对象的
变量的大小必须加以衡量。传感器可能适合一个定位系统。
固定大小的对象的地方大于镜头所遇到的。一个配置的
多个传感器或单一传感器和分光镜和镜子可以构建。
对峙的距离是相当大的影子判断相比较
其他noncontacting传感器。这个距离可以在10英寸的范围的准确性
前面提到的。虽然从理论上讲非常大。对峙距离是受限的
镜头使用的准确性将光线折射成平行的光线的田野上的
视图。此外。远距离条件影响干涉仪,如
大气扰动。还将影响这种类型的系统二
An advantage of this approach is that it is not affected by surface condition or
reflectivity as many light-based systems are. In a machining application.it can be
readily used in a cylindrical grinding or turning operation. Although it is bulkier than
other sensors·through the use of mirrors it is possible to direct the beam immediately
behind the cutting tool.minimizing delays in obtaining measurements data. Since clear
and translucent cutting fluids can refract the light at the workpiece edge.an air stream
or other means must be used to remove cutting fluids for highly accurate measurements.
These type of systems are relatively insensitive to the presence of cutting fluids and
chips(unless they completely and continuously block the light path)since clever averaging and false-signal refection techniques have been implemented by the manufacturers.
The system can provide a measurement as fast as the mirror can scan the beam.
The effective rate may be several hundred measurements a second. This rate.however.
is reduced depending on the measurement environment and the accuracy required.which determines the degree of signal refection required. The effective spot size is the width of
the laser beam.which might typically be 0. 030in. For an HeNe laser used in this
application. The sensor will tend to average a measurement.as opposed to a micrometer
used for an outer-diameter measurement.which would read the peak. Also.imperfect alignment of the facets of each reflecting surface in the rotating mirroring provides a
dither of the beam.which tends to average the measurement.
这种方法的一个优点是,它不受地表条件或
尽可能多的光学系统的反射率。在加工的应用程序。它可以
容易使用,或者将一个圆柱形的磨削操作。尽管这是很笨重的
其他传感器·通过使用镜子可以立即直接光束
在刀具。最小化延迟获得测量数据。自从清楚
和半透明的切削液可以折射光线在工件边缘。一个空气流
或者其他手段必须用来去除切削液对高度准确的测量。
这些类型的系统相对不敏感的存在和切削液
芯片(除非他们完全和不断阻挡紫外线的路径),因为聪明的
平均和false-signal映衬技术已经实现的
制造商。
该系统可以提供一个测量的速度一样快的镜子能够扫描波束。
实际利率可能几百测量第二。这rate.however。
降低取决于测量环境和准确性required.which吗
确定程度的信号需要小吃。有效点的宽度是大小
激光光束。这通常可以0。030年。对于一个氦氖激光中使用
应用程序。该传感器将倾向于平均测量。相对于一微米
用于一个outer-diameter测量。这将阅读高峰。也。不完美的结合方面的每个反射表面在旋转镜像提供了一个梁的优柔寡断。这往往平均测量。
Since the laser shadow gauge is normally supplied as a system and not only a sen-
sor .the cost is generally higher than that of most sensors. However, the units are easy
to align.provide a high degree of accuracy .are relatively impervious to machining con-
ditions(assuming that cutting fluids are not flooding the measurement area).and pro-
vide a direct digital output which can normally be interfaced to a computer or machine
tool control via a serial interface.
The laser triangulation technique.as the name https://www.doczj.com/doc/571318597.html,es a laser light source and
the geometric principle of triangulation to make a distance measurement. The laser is commonly oriented normal to the surface and uses scattered light as opposed to direct reflection.
Because this sensor is light based .the light path must be unobscured and lenses
kept clean when used in an machining application. The triangulator has been demonstrated in process control applications and is supplied commercially. There is a
trend among makers of coordinate measuring machines to equip the machines with this
type of sensor.which will allow the machines to scan surfaces and measure point at a
much higher rate.
因为激光影子判断通常是一个系统,而不是为只有森-
法师。成本通常高于大多数的传感器。然而,单位是容易的
对齐。提供一个高度的准确性。相对不受加工con -
条件(假设切削液并非洪水测量面积)。和pro -
真空直接数字输出通常可以如何与计算机或机器
工具控制通过一个串行接口。
激光三角测量。正如其名称所暗示的。利用激光光源和
三角几何原理使一个距离测量。激光是
面向一般正常地表,并使用散射光而不是直接的
反射。
因为这是基于光传感器。光路必须用和镜头
保持清洁时所用的一种加工应用。这个triangulator一直
演示了在过程控制应用程序和商业提供。有一个
在制造商的趋势坐标测量机等机械装备与这个
类型的传感器。这将允许机器扫描表面和测点在吗
更高的税率。
第八章课后
3.A simple air sensor consists of a regulated source of air.an adjustable restric-
tion .and a nozzle with an orifice.with an object.the workpiece.blocking the
nozzle .the pressure across the restriction is zero.
4.Available sensors have a variety of characteristics that must be understood before application. The major characteristics.physical size.resolution.accuracy.type
of signal output.signal processing requirements.effective spot size are outlined
herein.
3。一个简单的空气传感器由一个监管的空气来源。一个可调节restric——
标量。和一个喷嘴与一个孔。与一个对象。工件。阻断
喷嘴。压力在限制是零。
4。传感器可有各种特征,之前,应当首先了解
应用程序。主要特点。物理size.resolution.accuracy.type
输出的信号。信号处理的要求。概述了有效点大小
第八章Video Camera
Perhaps the newest .most flexible noncontacting sensor.and the one with the most
potential for future.is the video camera-based measurement sensor. These sensors are
normally categorized under the title of machine vision. The technology categorized is
based on a video camera(vidicon) and a computer-based image analyzer. The technology
of the components is fairly mature.dating back to television and the digital computer.
Ironically .machine vision has been used in an industrial setting only within the past five
years. Its use is primarily due to the availability of stable solid-state vidicons.faster.
less expensive minicomputers.and image processing algorithms. A significant advantage
of this approach is that an entire scene can be captured in an instant.allowing a
multitude of measurements to be made without moving the sensor. The main
disadvantage stems from the volume of data that must be processed by the image analyzer .resulting in either a slow response or a requirement for an extremely fast
processor. Although a camera can acquire only a two-dimensional sc ne.structured
lighting approaches combined with triangulation can be implemented to allow the video
camera-base sensor to collect measurements in three dimensions.
也许是最新的。最灵活的noncontacting传感器。而最
未来。是视频摄像头测量传感器。这些传感器
通常分类》的书名下机器视觉。这项技术的分类是
基于摄像机(摄像机)和一个以计算机为基础的图像分析仪。这项技术
是相当成熟的组件。回溯到电视和数字计算机。
具有讽刺意味的是。机器视觉已经应用在工业环境只有在过去5个
年。它的使用主要是由于供应稳定的固态vidicons.faster。
更便宜的小型计算机。和图像处理算法。一个重要的优势
这种方法的整个场景中可以获得即时。允许
众多的测量数据就没有移动传感器。主要
劣势源于的数据量必须处理的图像
分析器。导致判罚反应迟缓或要求极快
处理器。尽管摄像机可以获得只有一个二维的sc ne.structured
照明方法结合三角可以实现允许视频
camera-base传感器收集的测量在三维空间。
The component parts of a machine vision sensor are simply a vidicon.interface.and computer. In practice .a configuration as shown in Figure 1 would be implemented. The
video camera views the workpiece under measurement through an optical system. normally a magnifying lens. The sensing element is a solid-state photodiode array·
although.in principle .a conventional vidicon tube can be utilized. The sold-state sensor
has many advantages.including lower cost.ruggedness.less sensitivity to blooming.
wider dynamic light range.greater image stability.smaller size.less weigh.and ease of
interfacing .the spacing of the photodiodes is typically on the order of 0. 001 to 0. 005
in. , which would limit the resolution of the sensor. For this reason, magnifying optics
are usually used to achieve resolutions in the range of 0. 0001 to 0. 0l in. , which would
normally be required in manufacturing environment.
The camera is connected to a frame grabber.which is a specialized.higl:一、peed
memory designed to collect and store single or multiple images.called frames.from the
camera. For each frame the grabber stores.it must have a capacity of at least the same
number of photodiodes as the camera has in its array. The individual diodes are called
pixels.for picture elements. The frame grabber.in turn.must accommodate the same
number of pixels. Since the photodiode itself merely provides a light level as an analog signal .this
must
be converted to a digital value for the memory and the digital
computer.
This conversion is normally done by means of an analog-to-digital converter.
The a/d converter resides in either the camera or the frame grabber. The resolution of
the converter determines the number of levels of light that can be resolved. This range
of levels is normally termed the gray scale and the typical resolution is 8 bits.
机器的组成部分,只不过是一vidicon.interface.and视觉传感器
计算机。在实践中。一个配置如图1所示会被实施。这个
摄像机视图下的工件测量通过光学系统。
通常一个放大的镜头。传感元素是一个固态二极管阵列·
虽然。原则上。一个传统的摄像机管可以利用。sold-state传感器的
有很多优势。cost.ruggedness包括更低。更少的敏感性盛开。
光范围更为广泛的动态。更大的图像稳定。小的尺寸。更少的权衡。和易用性
接口。间隔的光敏二极管通常以0。001年到0。 005年
在。,这将限制的分辨率传感器。出于这个原因,放大光学
通常用来实现决议在范围为0。0001年到0。 l在0。,
通常应在生产环境。
这个相机是连接到一个框架夺人眼球。这是一个specialized.higl:一、小便吗
内存用于收集和存储单个或多个图像。称为帧。从
相机。对于每帧夺人眼球的商店。它必须有能力至少是相同的
数量的光敏二极管相机在其数组。个人二极管被称为
像素。对于图像元素。夺人眼球的框架。反过来。必须容纳相同
数量的像素。自从光二极管本身只是提供一个模拟信号。这水平
必须
可以转换为一个数字值的内存和数字
计算机。
这种转换是做通常通过模拟数字转换器。
a / d转换器驻留在任何相机或框架夺人眼球。该决议的
转换器层级的数量决定的光,是可以解决的。这个范围
所谓的水平通常是灰色的刻度和典型的决议是8位。
The frame grabber is connected to an image analyzer.which is another piece of
specialized circuitry designed to unburden the digital computer from handling all the data collected from the camera. Repetitively·higl:一、peed processing of the data can be performed by the image analyzer breaking the picture down into features for further
analysis.including measurement by a less costly computer of moderate speed. Operations that the image analyzer might handle include averaging.convolution.edge
detection.thresholding.and windowing. Operations for image analysis originally developed at SRI and GM spurred use of the video camera for inspection purposes.
To utilize the camera as a measurement sensor.features in the field of view of the
camera must be located. This is normally done through edge detection. Edge detection.
as the name implies.is used to locate the edge(light-to-dark transition) of an object so
that it can be used as a measurement point itself or so that may be used with other points
to describe a feature such as a line.circle.arc.or ellipse. For objects that cannot be
contained within one field of view.points obtained in one frame can be used to reference
other views. Edge detection is a differentiation process usually done by examining a
small region of pixels for their light-to-dark transition in the vicinity of the edge. Since differentiation is inherently a noisy process. normally it is combined with some averaging.statistical.or convolution techniques to…clean up?the image. After edge
detection.the resultant image can be subtracted from a threshold to establish a clean
edge.
夺人眼球的框架已经连接到一个图像分析仪。这是一块吗
专门的电路设计来解除数字计算机从处理所有的数据
收集了从相机。重复·higl:一、尿湿处理的数据可以
执行图像分析仪打破那张画取下来功能,进一步
分析。包括测量一个低成本电脑温和的速度。
操作的图像分析器可能会包括averaging.convolution.edge处理
detection.thresholding。和窗口。操作图像分析最初
在斯里兰卡和通用汽车开发刺激使用视频摄像机进行检查的目的。
利用摄像机为测量传感器。特性的的视野
相机必须位于。这通常是通过边缘检测。边缘检测。
正如其名称所暗示的。用于定位边(light-to-dark过渡)的一个对象
它可以作为一个测量点本身或者以便可以用于其他的点
描述一个line.circle.arc等特征。或椭圆。为对象,不能
包含在一个领域的观点。分在一个框架获得可以用于参考
其他的视图。边缘检测是一种差异化流程通常由检查
小区域像素的为他们的light-to-dark过渡附近的边缘。自从
分化本质上是一个嘈杂的过程。通常它是结合一些
averaging.statistical。或卷积技术来'clean伦理学的形象了。边缘后
检测。生成的映像可以减去一个阈值建立一个清洁
边缘。
After points on the edges are found·they can be fit-for example·by using a least
squares approacl:一into lines that describe the object. A least squares approach has the advantage that it is an averaging process which aids in removing random variation that might affect feature location. The features can then be passed up to the computer.
where measurements can be made by subtraction of absolute feature locations of preselected points. Where objects are too large for the field of view of the camera and
lens combination.the computer can combine images into data that describe the entire
object. Features of the object might also be directly compared with entities from a
computer-aided design database.for example.
Because of limitations in the size of photodiode arrays and a reduction in field of
view due to the magnifying lens required to get proper resolution.in many cases a
positioning system is also required for a video camera sensor. When a large object is measured·the camera is moved in the vicinity of the points to be measured. In some
cases a third axis of motion may be required to focus the camera. Again.when.when magnifying optics are used.the depth of field of the system.like the field of view.is
reduced. When few points must be measured.the image can be windowed to improve
the response time of a measurement.windowing reduces the area of interest in the scene
to the area where the point to be measured is expected to be found .thus reducing
processing time greatly.
点之后的边缘是他们可以fit-for发现··通过使用至少例子
广场approacl:一into线路,描述对象。一个最小二乘方法的
优势:它是一个过程,帮助消除我们在平均随机变异特征定位的可能影响。这个特性可以被传递到计算机。
在测量可以由减法的绝对位置的特性
预选点。对象的地方太大的视野相机和吗
透镜结合。计算机可以结合图像数据,描述整个
对象。对象的功能也可以直接与实体从
计算机辅助设计数据库。例如。
因为大小的限制,在光电二极管阵列和减少的领域
视图由于放大的镜头必须得到妥善解决。在许多情况下,
定位系统都需要一个视频摄像头传感器。当一个大型对象
测量·照相机是搬到附近的点来衡量。在一些
例第三轴的运动可能需要把照相机的焦点。Again.when.when
使用光学放大。田野的深度的系统。像view.is领域
减少。当几个点必须加以衡量。图像可以被改进
响应时间的测量的。窗口减少了现场感兴趣的地方
所在位置的点来衡量预计将发现。从而减少
处理时间极大。
Accuraciesin the range of 0. 0001 in. can be achieved with a video camera-based
sensor. Standoff distances may range from 0. 05 to several inches.with the former
number typical of a microscope objective lens. ()they optical solutions are available in
the form of macro focusing telescope lenses where standoff distances on the order of feet
may be obtain with magnification. Limitations due to spot size associated with other
sensors do not exit .since the camera can view a whole scene at once. As with other
light-based sensors.limitations due to dirty lenses and objects blocking the lens such as
coolant and chips apply to this camera-based sensor.
An extension of this sensor which permits determination of three-dimensional information involves the use of structured light scenes. In the general case.when
mapping a three-dimensional scene onto a plane.a ray of light emanating from a point on
a close object may be mapped onto the same pixel in the cameras photodiode array as a
ray emanating from a point displaced from the first on a distant object. this confusion
must be resolved in order to obtain a distance measurement. To do this.another type of structured light application can be used to make measurements in three dimensions from
an unknown scene. In this application a shuttered.structured lighting system has been
developed to control the illumination of the being measured.thereby permitting a one-
for-one mapping from the three-dimensional scene to the two-dimensional image. to
accelerate the data processing.a binary sot routine was utilized to analyze structured light patterns from the shutter.
Accuraciesin范围为0。 0001英寸会取得视频摄像头
传感器。距离外可能的范围是从0。05到几英寸。与前
典型的数量显微镜物镜处。()他们光学解决方案是可用的
这个形式的宏观聚焦望远镜镜片,距离外以英尺
可以获得与放大。由于现货大小限制伴随其他
传感器不退出。因为这个摄像头可以查看一次整个场面。与其他
光学传感器。由于肮脏的镜头和局限性等对象挡住了镜头
冷却剂和芯片应用于这个摄像头传感器。
这种传感器的扩展允许三维的决心
信息涉及使用结构光的场景。在一般case.when
映射一个三维场景上一架飞机。一束光来自一个点上
亲密的对象可以映射到同一像素的相机二极管阵列作为
射线来自一个点的位置上的第一个遥远的物体。这种混淆
必须解决以获得一个距离测量。要做到这一点。另一种类型的
结构光的应用程序可以被用来制造三维测量从
一个未知的场景。在这个应用程序中一个关闭的。结构化照明系统
开发了控制测量的照明。从而让一
从三维场景鞋映射到二维的图像。到
加快数据处理。一个二进制说常规是用来分析结构光模式从快门。
The video camera-based measurement sensor is extremely flexible for in-process measurements. Its accuracy is well within the range for all but the most demanding
applications and is certainly comparable to that of other contacting and noncontacting
sensors. The camera can be configured with a variety of lenses and light sources to accommodate different field-of-view and standoff requirements. The primary disadvantages of this type of measurement sensor at this time are its https://www.doczj.com/doc/571318597.html,plexity.
and response time for complicated scenes;however.this will change as the technology
matures and less expensive higl:一、peed computers become available along with specialized
very high speed integrated circuit chips to perform the image analysis functions.
视频摄像头测量传感器是非常灵活的过程
测量。其准确性是正常范围只有最苛刻的
应用程序和肯定是与其他联系和noncontacting
传感器。摄像机可以配置为使用各种各样的眼镜和光源来
适应不同视场和对峙的需求。主要
这种类型的缺点的测量传感器是其https://www.doczj.com/doc/571318597.html,plexity。
对于复杂的场景和响应时间;然而。这将改变随着技术
成熟,减少昂贵的higl:一,撒尿的电脑可用以及专业
高速集成电路芯片来执行图像分析功能。
第九章课后
3.All electronic voltmeters use a do meter movement for their readout. Consequently.the
ac signal input must be converted from ac to do before it can be displayed. The
conversion must be such that the true rms value of the waveform is retained. There are
a number of ways to do the conversion.
4.The equivalent resistance of a set of inter-connected resistors is the value of the
single resistor that can be substituted for the entire set without affecting the
current that flows in the rest of any circuit of which it is a part.
第九章课后
3。所有的电子电压表一样使用做米运动的读数。Consequently.the
交流信号被转换的输入必须从ac之前可以显示。这个
转换必须是这样,真正的均方根值的波形留存。有
许多方法来执行转换。
4。电阻的等效电阻的一组互相连接的价值
单一的电阻,可以代替该组没有影响
电流流过其它电路的一个部分。
第九章Rectifier Meters
Half-wave Rectifier Meters Basically，the
conversion
of ac to do is done using rectifier diode is a
one-way electronic value that essentially shears off the negative peak of the waveform when used alone thus converting the
、、ave
shape to a pulsating do waveform
aS
illustrated in Figure 1(b>.The process is called half
、、ave
rectification because only half the original
sme、、ave
exists after it takes place. The integrated circuit operational amplifier is
candidate
for ac
conversions
using diode rectification. Connecting a
an ideal
rectifier
series with the
to do
meter
circuit of an
op-amp voltage-follower voltmeter.
as illustrated
Figure 2 .converts the
nn
11
instrument into a half-wave
rectifier
signal
voltmeter.
In this design.the ac
aC
is
input to the attenuator stage through coupling
capacitor〔’，.The coupling capacitor is provided at the input of the ac voltmeter to block unwanted do voltages from affecting the measurement. As with the do electronic Half-wave整流器米基本上,
转换
交流是通过使用整流二极管是一个
单向电子价值本质上剪掉消极的峰值的波形单独使用的时候因此转换
、、ave
形状变成脉动波形做
作为
图1所示(b >。这个过程叫做一半
、、ave
因为只有一半的原始整改
中小企业,ave
存在发生之后。集成电路是运算放大器
候选人
ac
转换
用二极管整流。连接
一个理想的
整流器
系列有
做
米
电路的
运算放大器voltage-follower电压表。
如
图2。转换
nn
11
仪器变成一个half-wave
整流器
信号
电压表。
在这个设计。ac
aC
是
输入衰减阶段通过耦合
电容器〔”,。耦合电容提供了输入交流电压表来阻止
不必要的做从影响测量误差的电压。与做电子
voltmeter·the attenuator stage provides the instrument with a wide selection of input
voltage ranges using a simple switching arrangement. The attenuated waveform is input
directly to the noninverting input of the op amp. The output of the amplifier is returned
to the inverting input.thus setting the gain of the amplifier at unity. A rectifier may also be connected to the input of the op amp.where it converts the
ac to do before it is impressed across the meter. 13y placing the rectifier before the op
amp .the amplifier deals only with do values.and the bandwidth of the amplifier is not a
critical factor in instrument design. This design is not as desirable as that of Figure 2
because of the nonlinearity properties inherent to solid-state rectifier diodes. Backward diodes.which are variations of tunnel diodes.are an exception and work well with this configuration for measuring low-value.higl:一frequency ac voltages.
Analog meters are average-voltage-responding instruments. The average value of
the half-wave-rectified output is given by:
电压表·仪器,具有衰减阶段提供了多种可供选择的输入
使用一个简单的切换电压范围安排。削弱的波形是输入
直接向noninverting输入运算放大器的输出放大器的返回
反向输入。从而设定的增益放大器在团结。一种整流器也可以被连接到输入op amp.where它转换
ac之前它是内的读数的印象。13 y放置整流器op之前
安培。放大器只处理做的值。和带宽放大器的不是
仪器设计的关键因素。这个设计是不令人满意的,图2
由于非线性性质固体整流器固有二极管。向后
二极管。这包括隧道二极管。是一个例外,工作好吗
配置用于测量低价值。higl:一frequency ac电压。
模拟米是average-voltage-responding仪器。的平均价值
half-wave-rectified的输出到:
E-,.;一昼一0. 318E-,
兀
Since
then
E、=1. 41E
F_
t丫只
0. 318(1. 41)E}-,}=0. 45E
nr
E于
F_
t丫只
0. 45 The coefficient 2. 22 is called the form factor
"this means that when a
meter reads an
E
value
which is the ratio of E}-,}/E:=2. 22.
of 100 volts，it is actually measuring:
F_
2 .22
一斗5 V
The form factor allows
average values.
us to
calibrate the meter scale in ER-, while actually measuring
Unfortunately，the forward voltage drop V,
across the rectifier
ln
circuit of
Figure 4 is a source
of error. When correctly forward-biased，a silicon
the
diode
typically
has a forward voltage drop V,- of 0. 7 V. V,
in(、reases
I, falls to
taken into
a very low level(below the knee of the
slightly with increase in I,，and if
characteristic curve)there can be
account in design calculations，
tts vartattons cannot. To avoid the errors.the voltage follower feedback loop to the inverting terminal is
taken from the cathode of the rectifier instead of from the amplifier output. demonstrated in Figure 3. The result is that the half-wave rectified output precisely
follows the positive half cycle of the input voltage. There is no V,- voltage drop from
input to output because the inverting terminal follows the input to the noninverting
terminal. With the inverting input referenced to the rectifier cathode.the voltage to the
meter always equals the voltage at the amplifier input. Such a circuit configuration is commonly referred to as a precision rectifier circuit.
Note that capacitors〔’:.〔’.and〔’，are connected across the attenuator resistors in Figure 4. These capacitors are normally employed in ac voltmeter attenuators to
compensate for the input capacitance of the operational amplifier. Input capacitance
problems also occur in oscilloscopes. 映
Low-level ac voltages too small for normal display
must
before being rectified and applied to the meter. The circuit shown
accurately
in Figure 5
amplified
combines
amplification with half
we see that the circuit
wave rectification.
Ignoring the rectifier diode for the moment
isa
noninverting amplifier with a gain factor of:
Inclusion of the diode
(、a useS
cycles ignored.
amplification is
Again .the
the positive half cycles to be amplified and the negative half表单元素允许
平均值。
我们
校准仪表规模在ER -,而实际测量的
不幸的是,向前的电压降V,
整个整流器
ln
电路的
图4是一个源
的错误。当正确forward-biased,硅
这个
二极管
通常
有一个向前的电压降V,- 0。7诉V,
在(,reases
我,落
带进
一个非常低的水平(膝盖以下的
在我稍微增加,,如果
特性曲线)可能存在
账户的设计计算、
tts vartattons不能。为了避免错误。反馈回路的电压追随者反向终端
来自阴极整流器而不是从放大器的输出。
图3中演示。结果是,half-wave整流输出准确
遵循正半周期输入电压。没有V,——从电压降
因为反向输入输出终端遵循noninverting的输入
终端。反向引用与输入整流器阴极。电压的
米总是等于电压在放大器输入。这样一个电路配置
通常被称为一个精密整流电路。
注意,电容器〔”:。〔”。和〔',是连接在电阻器在衰减
图4。这些电容器通常采用交流电压表衰减器来
补偿输入电容的运算放大器。输入电容
问题也发生在示波器。映
低级ac电压太小正常显示
必须
之前被修正并应用到米。显示电路
准确
在图5
放大
结合
扩展和一半
我们看到,电路
波整流。
忽略了整流二极管的时刻
isa
noninverting放大器增益的一个因素:
包容的二极管
(,一个使用
周期忽略。
放大是
再一次。
正半周期放大和负半
configuration of the feedback loopguarantees that the
precise and that
nn
rectifier volt drop is involved in the measurement. full-wave rectifier meters When full-wave rectification is used.both the positive and negative peaks of the
waveform are converted into do signals.as shown in Figure 6. Generally.the full-wave
rectifier is of the bridge type. A bridge rectifier passes the positive.diodes D. and D
conduct .causing current to flow through the meter from the negative meter terminal to
the positive. When the input goes negative.diodes D, and D, are reversebiased.and
diodes Dz and D;j conduct current through the meter. Because of their arrangement.Dz
and D;j force the current to again flow through the meter from the negative meter
terminal to the positive. The resulting current flow is a series of positive half cycles
without any intervening spaces.
When a full-wave rectifier is used.the form factor is only 1. 11.because
E-;一遇一U. 636E-,
E、-
1 .414E
兀
"therefore
E.;-
U. 636 X 1.41E-,}-
U. 9E As indicated earlier.the rectifier-type ac voltmeter is calibrated to read the
effective.or rms.value of the measured average voltage.
The circuit in Figure 7 employs a full-wave bridge rectifier to convert the ac signal
to dc. This circuit is basically a voltage-to-current converter with rectification. In this design.the voltage drop across R;j is always equal to the input voltage.
配置的反馈,loopguarantees
精确,
nn
整流器volt的下降是参与测量。当full-wave full-wave整流器米矫正法是利用。两个积极和消极的山峰
波形信号被转换成做。如图6所示。一般。full-wave的
整流器是桥的类型。一个桥式整流传递积极的。二极管D和D
行为。造成电流流动通过水表终端,从负面米
积极的。当输入是负面的。二极管D和D,是reversebiased.and
二极管Dz和D;j进行电流通过米。因为他们的arrangement.Dz
和D;j迫使当前再次流透过米从负米
终端向积极的方面。由此产生的电流是一系列的正半周期
中间却没有空格。
当一个full-wave整流装置的使用。这个形式因素是只有1。11.,因为
E -;一遇一U。636 E -,
E -
1 .414E
兀
“因此
e .;-
美国636 X 1.41 E -,} -
正如前面指出美国9 E。rectifier-type交流电压表的校准来阅读
有效的。或rms。测量的价值平均电压。
在图7的电路采用了一个full-wave桥式整流交流信号转换
对直流。这条赛道基本上是一个voltage-to-current转换器整改。在这个
设计。R上的电压降;j总是等于输入电压。
第十章课后
3.As with the analog multimeter·the digital multimeter(I>MM)is capable of
measuring voltage.current.and resistance. Basically.the DMM is an electronic
voltmeter that can be configured to express current and resistance measurements
Lesson 1 力学的基本概念 1、词汇： statics [st?tiks] 静力学；dynamics动力学；constraint约束；magnetic [m?ɡ＇netik]有磁性的；external [eks＇t?:nl] 外面的, 外部的；meshing啮合；follower从动件；magnitude [＇m?ɡnitju:d] 大小；intensity强度，应力；non-coincident [k?u＇insid?nt]不重合；parallel [＇p?r?lel]平行；intuitive 直观的；substance物质；proportional [pr?＇p?:??n?l]比例的；resist抵抗，对抗；celestial [si＇lestj?l]天空的；product乘积；particle质点；elastic [i＇l?stik]弹性；deformed变形的；strain拉力；uniform全都相同的；velocity[vi＇l?siti]速度；scalar[＇skeil?]标量；vector[＇vekt?]矢量；displacement代替；momentum [m?u＇ment?m]动量； 2、词组 make up of由……组成；if not要不，不然；even through即使，纵然； Lesson 2 力和力的作用效果 1、词汇： machine 机器；mechanism机构；movable活动的；given 规定的，给定的，已知的；perform执行；application 施用；produce引起，导致；stress压力；applied施加的；individual单独的；muscular [＇m?skjul?]]力臂；gravity[ɡr?vti]重力；stretch伸展，拉紧，延伸；tensile[tensail]拉力；tension张力，拉力；squeeze挤；compressive 有压力的，压缩的；torsional扭转的；torque转矩；twist扭，转动；molecule [m likju:l]分子的；slide滑动; 滑行；slip滑，溜；one another 互相；shear剪切；independently独立地，自立地；beam梁；compress压；revolve (使)旋转；exert [iɡ＇z?:t]用力，尽力，运用，发挥，施加；principle原则, 原理，准则，规范；spin使…旋转；screw螺丝钉；thread螺纹； 2、词组 a number of 许多；deal with 涉及，处理；result from由什么引起；prevent from阻止，防止；tends to 朝某个方向；in combination结合；fly apart飞散； 3、译文： 任何机器或机构的研究表明每一种机构都是由许多可动的零件组成。这些零件从规定的运动转变到期望的运动。另一方面，这些机器完成工作。当由施力引起的运动时，机器就开始工作了。所以，力和机器的研究涉及在一个物体上的力和力的作用效果。 力是推力或者拉力。力的作用效果要么是改变物体的形状或者运动，要么阻止其他的力发生改变。每一种
数学专业英语课后答案
2.1数学、方程与比例 词组翻译 1.数学分支branches of mathematics，算数arithmetics，几何学geometry，代数学algebra，三角学trigonometry，高等数学higher mathematics，初等数学elementary mathematics，高等代数higher algebra，数学分析mathematical analysis，函数论function theory，微分方程differential equation 2.命题proposition，公理axiom，公设postulate，定义definition，定理theorem，引理lemma，推论deduction 3.形form，数number，数字numeral，数值numerical value，图形figure，公式formula，符号notation(symbol)，记法/记号sign，图表chart 4.概念conception，相等equality，成立/真true，不成立/不真untrue，等式equation，恒等式identity，条件等式equation of condition，项/术语term，集set，函数function，常数constant，方程equation，线性方程linear equation，二次方程quadratic equation 5.运算operation，加法addition，减法subtraction，乘法multiplication，除法division，证明proof，推理deduction，逻辑推理logical deduction 6.测量土地to measure land，推导定理to deduce theorems，指定的运算indicated operation，获得结论to obtain the conclusions，占据中心地位to occupy the centric place 汉译英 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。 Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。
第二章第一篇 To say that we live in an age of electronics is an understatement. From the omnipresent integrated circuit to the equally omnipresent digital computer, we encounter electronic devices and systems on a daily basis. In every aspect of our increasingly technological society— whether it is science, engineering, medicine, music, maintenance, or even espionage—the role of electronics is large, and it is growing. 谈论关于我们生活在一个电子学时代的论调是一种空泛的论调。从无处不在的集成电路到同样无处不在的数字计算机，我们在日常活动中总会遇到电子设备和电子系统。在我们日益发展的科技社会的方方面面——无论是在科学、工程、医药、音乐、维修方面甚至是在谍报方面——电子学的作用是巨大的，而且还将不断增强。 In general, all of the tasks with which we shall be concerned can be classified as "signal-processing“tasks. Let us explore the meaning of this term 一般说来，我们将要涉及到的工作被归结为“信号——处理”工作，让我们来探究这个术语的含义吧。 A signal is any physical variable whose magnitude or variation with time contains information. This information might involve speech and music, as in radio broadcasting, a physical quantity such as the temperature of the air in a room, or numerical data, such as the record of stock market transactions. The physical variables that can carry information in an electrical system are voltage and current. When we speak of "signals", therefore, we refer implicitly to voltages or currents. However, most of the concepts we discuss can be applied directly to systems with different information-carrying variables. Thus, the behavior of a mechanical system (in which force and velocity are the variables) or a hydraulic system (in which pressure and flow rate are the variables) can often be modeled or represented by an equivalent electrical system. An understanding of the behavior of electrical systems, therefore, provides a basis for understanding a much broader range of phenomena. 信号就是其与时间有关的量值或变化包含信息的任何物理变量。这种信息或许像无线电广播的演讲和音乐，或许是像室内温度的物理量，或许像股市交易记录的数字数据。在电气系统中能够载有信息的物理变量是电压和电流。因此当我们谈到“信号”，我们不言而喻指的是电压和电流，然而，我们要讨论的大多数概念是可以被直接应用于载有不同信息的变量的系统，因此，一个机械系统（在这个系统中力和速度是其变量）或者液压系统（在这个系统中压力和流速是其变量）的性能通常可以用一个等效的电气系统来模拟或表示。因此，我们对于电气系统性能的理解为理解更宽领域的现象打下了一个基础。 A signal can carry information in two different forms. In an analog signal the continuous variation of the voltage or current with time carries the information. An example, in Fig.2-l, is the voltage produced by a thermocouple pair when the two junctions are at different temperatures. As the temperature difference between the two junctions varies, the magnitude of the voltage across the thermocouple pair also varies. The voltage thus provides an analog representation of the temperature difference. 一个信号可以以两种形式来承载信息。在一个模拟信号中电压或电流随时间而产生的连续变化载有信息。在图2-1中，当一对热电偶的接头处于不同的温度时由热电偶所产生的电压就是一个例子。当两个接头之间的温度差改变时，一对热电偶两端的电压也将改变。于是电压就提供了温度差的模拟表现形式 The other kind of signal is a digital signal. A digital signal is one that can take on values within two discrete ranges. Such signals are used to represent ON-OFF or YES-NO information. An ordinary household thermostat delivers a digital signal tocontrol the furnace. When the
1.机械设计过程 机械设计的最终目标是生产一种满足客户需求的有用产品，而且这种产品安全，高效，可靠，经济，实用。当回答这个问题时，广泛地思考，我将要设计的产品或系统的客户是谁？ 在产品设计之前，了解所有客户的期望和期望是至关重要的。营销专业人员经常被用来管理客户期望的定义，但是设计师可能会把他们作为产品开发团队的一部分。 许多方法被用来确定客户想要什么。一种被称为质量功能部署或QFD的流行方法寻求（1）识别客户期望的所有特征和性能因素，以及（2）评估这些因素的相对重要性。QFD过程的结果是产品的一组详细功能和设计要求。 考虑设计过程如何配合为客户提供令人满意的产品所必须发生的所有功能以及在产品的整个生命周期中为产品提供服务也很重要。事实上，重要的是考虑产品在使用寿命后如何处置。影响产品的所有这些功能的总和有时被称为产品实现过程或PRP。PRP中包含的一些因素如下： ?营销功能来评估客户的要求 ?研究确定可在产品中合理使用的可用技术 ?可以包含在产品中的材料和组件的可用性 ?产品设计和开发 ?性能测试 ?设计文件 ?供应商关系和采购职能 ?考虑全球材料采购和全球营销 参加工作的技能 ?物理工厂和设施可用
?制造系统的能力 生产计划和生产系统的控制 ?生产支持系统和人员 ?质量体系要求 ?销售操作和时间表 ?成本目标和其他竞争性问题 ?客户服务要求 ?产品在生产，操作和处置过程中的环境问题 ?法律要求 ?金融资本的可用性 你可以添加到这个列表吗？您应该能够看到，产品的设计只是综合过程的一部分。在本文中，我们将更加注意设计过程本身，但必须始终考虑设计的可生产性。产品设计和制造过程设计的同时考虑通常被称为并行工程。 2.机械设计所需的技能 产品工程师和机械设计师在日常工作中使用广泛的技能和知识。这些技能和知识包含在以下内容中： ?素描，技术制图和计算机辅助设计 ?材料的性质？材料加工*和制造过程 ?化学的应用，如腐蚀防护，电镀和喷漆 静力学动力学材料的强度，运动学和机制 流体力学，热力学和传热 ?流体动力，电气现象的基本原理和工业控制
2.1 数学、方程与比例 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。 Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。 Equations are of very great use. We can use equations in many mathematical problems. （8）解方程时要进行一系列移项和同解变形，最后求出它的根，即未知量的值。To solve the equation means to move and change the terms about without making the equation untrue, until the root of the equation is obtained, which is the value of unknown term. 2.2 几何与三角 （1）许多专家都认为数学是学习其他科学技术的必备基础和先决条件。 Many experts recognize that mathematics is the necessary foundation and prerequisite of studying other science technology. （2）西方国家的专家认为几何起源于巴比伦和埃及人的土地测量技术，其实中国古代的数学家对几何做了许多出色的研究。 The western experts think that geometry had its origin in the measurements by the Babylonians and Egyptians of their lands. Infect, the ancient Chinese mathematicians made much remarkable study for geometry. （3）几何的学习使学生在思考问题时更周密和审慎，他们将不会盲目接受任何结论。 In studying geometry, the student is taught to think clearly and critically and he is led away from the practice of blind acceptance of any conclusions. （4）数学培养学生的分析问题的能力，使他们能应用毅力、创造性和逻辑推理来解决问题。
Most people can formulate a mental picture of a computer, but computers do so many things and come in such a variety of shapes and sizes that it might seem difficult to distill their common characteristics into an all-purpose definition. At its core, a computer is a device that accepts input, processes data, stores data, and produces output, all according to a series of stored instructions. Computer input is whatever is put into a computer system. Input can be supplied by a person, by the environment, or by another computer. Examples of the kinds of input that a computer can accept include the words and symbols in a document, numbers for a calculation, pictures, temperatures from a thermostat, audio signals from a microphone, and instructions from a computer program. An input device, such as a keyboard or mouse, gathers input and transforms it into a series of electronic signals for the computer. In the context of computing, data refers to the symbols that represent facts, objects, and ideas. Computers manipulate data in many ways, and we call this manipulation processing. The series of instructions that tell a computer how to carry out processing tasks is referred to as a computer program, or simply a "program." These programs form the software that sets up a computer to do a specific task. In a computer, most processing takes place in a component called the central processing unit (CPU), which is sometimes described as the"brain" of the computer. A computer stores data so that it will be available for processing. Most computers have more than one location for storing data, depending on how the data is being used. Memory is an area of a computer that temporarily holds data that is waiting to be processed, stored, or output. Storage is the area where data can be left on a permanent basis when it is not immediately needed for processing. Output is the results produced by a computer. Some examples of computer output include reports, documents, music, graphs, and pictures. An output device displays, prints, or transmits the results of processing. Computers are versatile machines, which are able to perform a truly amazing assortment of tasks, but some types of computer are better suited to certain tasks than other types of computers. Computers can be categorized as personal computer, handheld computers, workstations, mainframes, supercomputers , and servers. 大多数人可以制订一个电脑精神的图片，但电脑做很多事情，出现这样的形状和大小不同，它似乎难以提炼成一个全能的定义，它们的共同特点。在其核心，一台计算机是一种装置，它接受输入，处理数据，存储数据，并产生输出，根据对所有存储一系列指示。 什么是计算机输入到计算机系统的压力。输入可提供的一人，由环境，或由另一台计算机。对输入的各种例子，一个计算机可以接受包括文字和符号的文件，规定计算，图片，从恒温器的温度数字，音频信号从一个麦克风，从电脑程序指令。一个输入设备，如键盘或鼠标，集输和转换成一个电子信号的计算机的一系列。 在计算中，数据是指以符号代表的事实，对象和想法。计算机操作在很多方面的数据，我们称之为操作处理。一系列的指令，告诉计算机如何进行处理任务，被称为一个计算机程序，或只是一个“程序”。这些方案形成了软件，建立了计算机做特定的任务。在计算机中，大部分处理发生在一个组件的地方称为中央处理单元（CPU），有时为“大脑的计算机”来形容。 计算机存储数据，以便它会被用作处理可用。大多数计算机有多个用于存储数据的位置，这取决于数据如何被使用。内存是计算机的一个领域，数据是暂时持有等待处理，存储或输出。在数据存储，是可以在一个地区长期离开时，没有立即处理所需。 输出是由电脑产生的结果。电脑输出的一些例子包括报告，文件，音乐，图形，图片。输出设备显示，打印，或传送的处理结果。 电脑是多功能机，它能够执行各种各样的任务十分惊人，但某些类型的计算机更适合比其他类型的计算机的某些任务。计算机可以被归类为个人电脑，掌上电脑，工作站，大型机，超级计算机和服务器。
“数学专业英语一次函数专题”教学设计 1. 教学内容及解析 教学内容：与直角坐标系及一次函数相关的英语文献资料 内容解析：本节内容应从两个方面去考虑. 一方面，从数学知识的角度，本节所涉及的是从平面直角坐标系到一次函数的数学知识，都是学生学过的基础知识及其应用，是对于这些知识的拉练式复习，并作为后面用英语叙述解答相关问题知识基础；另一方面，从语言的角度，学生会接触到大量没有接触过，但他们却很熟悉的英语词汇及短语，主动学习的学生可以在老师的指导下快速理解其含义并加入到自己的知识体系中，但需要花时间巩固，是需要读、写、说来巩固的内容. 这也正是本节的重点和难点所在. 2. 教学目标及解析 教学目标：①能根据已有的数学知识和给出的单词对照表，将给出的相关数学定理及结论的英语版本翻译为中文；②能理解并解答用英语表述的相关数学问题；③能将解决数学问题的过程用英语进行书面表述；④初步了解用英语表达与直角坐标系及一次函数相关数学理论的范式. 目标解析：学生掌握基本词汇，并能阅读与本节内容相关的英语文献，是学习和使用数学专业英语的最基本要求，学生需要在学习的过程中逐渐由接受，即阅读或聆听，逐渐向输出，即书面和口头表达的方向发展. 为达到此目标，学生需要在课前独立完成对于本节需要的单词的学习，并阅读一系列简短的相关数学文献，并在这个过程中初步体会数学专业英语的表达范式；在课堂上，在教师的指导下对自己的认知进一步补充，并进行一定量的练习，暴露自己的问题，在教师的帮助下修正问题，完善认知. 3. 教学问题诊断分析 学生在进行语言表达时，往往受到母语的限制，对于非母语的表达方式的接受能力一时难以习惯，而数学对于表达能力则有更高的要求，要求叙述简洁、逻辑清晰，因此本教学设计强调学生在有相当阅读量的积累后，通过自主练习，逐渐感受用英语表达数学理论的基本范式. 教师在教学过程中的主要任务在于为学生提供合适的学习资料，在学生学习的过程中给予提示与指导，及时指出学生的问题并予以纠正. 对于语言的学习，阅读量的积累是至关重要的，教师在课堂上的讲解、学生在课堂上的练习，都只是学习的一部分环节，如果需要帮助学生正确掌握表达数学理论的范式，尽量不留死角，就必须保证课前预习和课后复习的有效性，预习复习材料的充足性，这对教师的教学资料的积累和学生自主学习能力，都是一个挑战. 4. 教学支持条件分析 学情条件：初二8班是实验班，学生有较强的学习热情和好奇心，也知道课前预习、课上参与学习活动、课后复习的重要性，在曾经的数学课程教学中，也有一定的课前预习，课堂讨论的传统，对于本教学设计的各个环节，是可以理解教师的用意，并遵循教师的指导进行学习活动. 在知识层面上，学生已经系统学习过一次函数相关的知识，课程中提供的学习资料都是学生熟悉的数学知识；学生在英语学习上，已经有多年的积累，对于英语语法的学
第一章第一篇sectiong Two variables u(t) and i(t) are the most basic concepts in an electric circuit, they characterize the various relationships in an electric circuitu(t)和i(t)这两个变量是电路中最基本的两个变量，它们刻划了电路的各种关系。 Charge and Current The concept of electric charge is the underlying principle for explaining all electrical phenomena. Also, the most basic quantity in an electric circuit is the electric charge. Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C). 电荷和电流电荷的概念是用来解释所有电气现象的基本概念。也即，电路中最基本的量是电荷。电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。 We know from elementary physics that all matter is made of fundamental building blocks known as atoms and that each atom consists of electrons, protons, and neutrons. We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10-19C, while a proton carries a positive charge of the same magnitude as the electron. The presence of equal numbers of protons and electrons leaves an atom neutrally charged. 我们从基础物理得知一切物质是由被称为原子的基本构造
1.2 总线互连 总线是连接两个或多个设备的通信通路。总线的关键特征是，它是一条共享传输介质。多个设备连接到总线上，任一个设备发出的信号可以为其他所有连接到总线上的设备所接收。如果两个设备同时传送，它们的信号将会重叠，引起混淆。因此，一次只能有一个设备成功地（利用总线）发送数据。 典型的情况是，总线由多条通信通路或线路组成，每条线(路)能够传送代表二进制1和0的信号。一段时间里，一条线能传送一串二进制数字。总线的几条线放在一起能同时并行传送二进制数字。例如, 一个8位的数据能在8条总线线上传送。 计算机系统包含有多种不同的总线，它们在计算机系统层次结构的各个层次提供部件之间的通路。连接主要计算机部件(处理机, 存储器, I/O)的总线称为系统总线。系统总线通常由50~100条分立的(导)线组成。每条线被赋予一个特定的含义或功能。虽然有许多不同的总线设计，但任何总线上的线都可以分成三个功能组：数据线、地址线和控制线。此外可能还有为连接的模块提供电源的电源线。 数据线提供系统模块间传送数据的路径，这些线组合在一起称为数据总线。典型的数据总线包含8、16或32根线，线的数量称为数据总线的宽度。因为每条线每次传送1位，所以线的数目决定了每次能同时传送多少位。数据总线的宽度是决定系统总体性能的关键因素。 地址线用于指定数据总线上数据的来源和去向。例如，如果处理机希望从存储器中读一个字的数据，它将所需要字的地址放在地址线上。显然，地址总线的宽度决定了系统最大可能的存储器容量。 控制线用来控制对数据线和地址线的访问和使用。由于数据线和地址线被所有部件共享，因此必须用一种方法来控制它们的使用。控制信号在系统模块之间传送命令和定时信息。定时信息指定了数据和地址信息的有效性，命令信号指定了要执行的操作。 大多数计算机系统使用多总线，这些总线通常设计成层次结构。图1.3显示了一个典型的高性能体系结构。一条局部总线把处理机连接到高速缓存控制器，而高速缓存控制器又连接到支持主存储器的系统总线上。高速缓存控制器集成到连接高速总线的桥中。这一总线支持连接到：高速LAN、视频和图形工作站控制器，以及包括SCSI 和FireWire的局部外设总线的接口控制器。低速设备仍然由分开的扩充总线支持，用一个接口来缓冲该扩充总线和高速总线之间的通信流量。 PCI 外部设备互连是流行的高带宽的、独立于处理机的总线，它能够作为中间层或外围设备总线。当前的标准允许在66MHz频率下使用多达64根数据线，其原始传输速率为528MB/s, 或4.224Gbps。PCI被设计成支持各种各样基于微处理机的配置，包括单处理机和多处理机的系统。因此，它提供了一组通用的功能。PCI使用同步时序以及集中式仲裁方案。 在多处理机系统中，一个或多个PCI配置可通过桥接器连接到处理机的系统总线上。系统总线只支持处理机/高速缓存单元、主存储器以及PCI桥接器。使用桥接器使得PCI独立于处理机速度，又提供快速接收和传送数据的能力。 2.1 光存储介质：高密度存储器 2.1.1 光盘 光盘技术最终可能使磁盘和磁带存储淘汰。用这种技术，磁存储器所用的读/写头被两束激光代替。一束激光通过在光盘上刻制微小的凹点，对记录表面进行写；而另一束激光用来从光敏感的记录表面读取数据。由于光束容易被偏转到光盘上所需要的位置，所以不需要存取臂。 对用户而言，光盘正成为最有吸引力的选择。它们(光盘)对环境变化不太敏感，并且它们以每兆字节比磁盘低得多的存储器价格提供更多的直接存取存储器。光盘技术仍在出现，并且还需要稳定；然而，目前有三种主要类型的光盘。它们是CD-ROM、WORM盘和磁光盘。 CD-ROM 1980年引入的，非常成功的CD，或紧密盘是设计来提高音乐的录音重放质量的光盘。为了制作一张CD，把音乐的模拟声音转换成等价的数字声音，并且存储在一张4.72英寸的光盘上。在每张光盘上可以用数字格式（用20亿数字位）记录74分钟的音乐。因为它的巨大存储容量，计算机工业的企业家们立刻认
1.我们可以把钢再次加热到临界温度以下的某一温度，然后在慢慢让其冷却。We can heat the steel again to a temperature below the critical temperature, then cool it slowly. 2.无论任何简单的机床，都是由单一元件即通称为机械零件或部件组成的。However simple, any machine is a combination of individual components generally referred to as machine elements or parts. 3.这些金属不都是好的导体。 All these metals are not good conductors. 4. 在做带电实验的时候，再怎么小心都不为过。 You can't be too careful in performing an experiment. 5.利用发电机可以把机械能转变成电能。 The mechanical energy can be changed back into electrical energy by means of a generator or dynamo. 6.假定电源输入的电压保持不变。 Assume that the voltage input of the power supply remains the same. 7.化石燃料是发电过程中最为频繁使用的能源。 Fossil fuels are most frequently used source daring the power generation process. 8单个机械零件的可靠性成为评估整台机器使用寿命的基本因素。 The individual reliability of machine elements becomes the basis for estimating the overall life 9.说我们生活在一个电子时代，这一点都不夸张。 It's no exaggeration to say that we live in an electronic age. 10.发动机的转速不应超过最大允许值。 Engine revolution should not exceed the maximum permissible. 11.如能从大型核电站获得成本极低的电力，电解氢的竞争能力就会增强。（Electrolytic hydrogen）。 If extremely low-cost power were ever to become available from large nuclear power plants, electrolytic hydrogen would become competitive. 12.电子技术提供了一种新的显示时间的方法。 A new way of displaying time has been given by electronics. 13.远距离输电需要高压，安全用电需要低压。 High voltage is necessary for long transmission line while low voltage for safe use. 14.铝的电阻大约是同等尺寸的铜的1.5倍。 The resistance of aluminum is approximately half again as great as that of copper for the same dimensions = size 15.In fact,it is impossible for no force to be exerted on a body,since in this world everything is subject to the for ce of gravity. 事实上，物体不受外力作用是不可能的，因为在这个世界上任何物体都要受到重力的作用。 16.In a thermal power plant,all the chemical energy is not
2.1数学、方程与比例 词组翻译 1.数学分支branches of mathematics，算数arithmetics，几何学geometry，代数学algebra，三角学trigonometry，高等数学higher mathematics，初等数学elementary mathematics，高等代数higher algebra，数学分析mathematical analysis，函数论function theory，微分方程differential equation 2.命题proposition，公理axiom，公设postulate，定义definition，定理theorem，引理lemma，推论deduction 3.形form，数number，数字numeral，数值numerical value，图形figure，公式formula，符号notation(symbol)，记法/记号sign，图表chart 4.概念conception，相等equality，成立/真true，不成立/不真untrue，等式equation，恒等式identity，条件等式equation of condition，项/术语term，集set，函数function，常数constant，方程equation，线性方程linear equation，二次方程quadratic equation 5.运算operation，加法addition，减法subtraction，乘法multiplication，除法division，证明proof，推理deduction，逻辑推理logical deduction 6.测量土地to measure land，推导定理to deduce theorems，指定的运算indicated operation，获得结论to obtain the conclusions，占据中心地位to occupy the centric place 汉译英 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。 Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。 Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。