Lecture 2 Phase properties and relations
Lecture 2
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3.1 OHM’s Law
Ohm’s law states that the voltage u across a resistor is directly proportional t the to th current t i flowing fl i th through h th the resistor.
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Propagation properties and self-reconstruction of a zimuthally polarized non-diffractingbeams
Propagation properties and self-reconstruction of azimuthally polarizednon-diffracting beamsMeng He,Ziyang Chen,Shunhong Sun,Jixiong Pu nCollege of Information Science and Engineering,Huaqiao University,Xiamen,Fujian361021,Chinaa r t i c l e i n f oArticle history:Received27August2012Received in revised form2December2012Accepted8December2012Available online9January2013Keywords:Azimuthally polarizationNon-diffracting beamsSelf-reconstructiona b s t r a c tAzimuthally polarized(AP)non-diffracting beams are investigated theoretically and experimentally in thispaper.We generate the AP non-diffracting beams by passing laser beams through a polarization converterand an axicon.Both the non-diffracting and the self-reconstruction phenomenon are studied theoreticallyand experimentally.The azimuthally polarized beams with non-diffracting and self-reconstruction proper-ties may have wide applications in manyfields such as particle trapping and manipulation.&2013Elsevier B.V.All rights reserved.1.IntroductionIn the past several years,cylindrical vector beams(i.e.,laser beamswith cylindrical symmetry in polarization)have attracted muchattention due to their important applications,such as optical trapping,singular optics,optical data storage,optical inspection and metrologyetc.[1–12].Azimuthally polarized beams,which are an importantclass of laser modes whose state of polarization is cylindrical,havebeen investigated in detail by many researchers[1–7].Recently,anon-diffracting‘‘dark channel’’with a long DOF has been achieved bytight focusing of a double-ring-shaped azimuthally polarized beam[3].In another study,the generation of a non-diffracting transversallypolarized beam by highly focusing an azimuthally polarized beamwith a high-NA lens and a multibelt spiral phase hologram has beenanalytically demonstrated[4].The studies demonstrate that azimuth-ally polarized laser beams can be applied in optical tweezersfor particle trapping and manipulation[10–12].On the other hand,increasing interest has been paid to non-diffracting beams because oftheir potential applications[13–25].One example of non-diffractingbeams is Bessel beams,which were introduced by Durnin[13].Idealforms of such beams are impossible to realize,as they would have aninfinite extent and carry infinite power[13].However,finite approx-imations of these beams can be realized that propagate over extendeddistances in a diffraction-free manner.Bessel–Gauss beams wereintroduced as a more realistic representation of Bessel-like beamsthat can be achieved in actual experiments[14].Bessel–Gauss beamcan be obtained by propagating Gaussian beam through an axicon[19,20].When illuminated by a Gaussian beam with a waist sizesmaller than the hard aperture of the axicon,virtually the wholeinput intensity is converted into an approximation to a Besselbeam.The axicon-generated beam is a close approximation to aBessel beam over a limited propagation distance.However,theintensity of the central maximum is not constant with propagationbut varies smoothly.The central maximum propagates withoutappreciable spreading(i.e.,it is non-diffracting)over this distance.Besides the non-diffracting,self-reconstruction is another fasci-nating property of Bessel beams.The self-reconstruction of thezero-order Bessel beam in free space was fully demonstrated andexplained by Bouchal et al.[23]in1998.Furthermore,Tao et al.[24]investigated the self-reconstruction property of the fractional Besselbeam(FBB)for three-dimensional optical trapping applications andtheir experimental results showed that the FBB can overcome a blockof obstacles and regenerate itself after a characteristic distance.Forthe fascinating property,Bessel beams are useful in optical micro-scopy[15],interboard optical data distribution[16],and opticaltrapping etc.[17].However,to the best of our knowledge,the self-reconstruction properties of AP non-diffracting beams have not beenstudied so far.In this paper,we extend the azimuthally polarizationbeams to non-diffracting case.Analytical formulae of AP beamspassing through an axicon are derived.The properties of AP non-diffracting beams on propagation in free space and passing throughobstacles are illustrated numerically.Some interesting conclusionsare obtained.Contents lists available at SciVerse ScienceDirectjournal homepage:/locate/optcomOpticsCommunicationsFig.1.Experimental setups for generating AP non-diffracting beams.0030-4018/$-see front matter&2013Elsevier B.V.All rights reserved./10.1016/j.optcom.2012.12.019n Corresponding author.Tel.:þ8613599220838.E-mail address:jixiong@(J.Pu).Optics Communications294(2013)36–422.TheoryIt is assumed that the transverse profile of the electric field of the azimuthally polarized beam is given by the expression [6]E 0r ðÞ¼A z Âr exp Àr 2,ð1Þwhere A is a random amplitude,w is the beam radius at z ¼0.In this work,the azimuthally polarized non-diffracting beams (AP non-diffracting beams)were generated by passing the azi-muthally polarized beams through an axicon.The transmittance function of the axicon can be expressed ast ðr Þ¼exp ½Àik n À1ðÞg r ,r r R0,r 4R,(ð2Þwhere k ¼2p /l is the wave number,l is the wave length,n is the refractive index of the axicon,and g is the taper angle of theaxicon.Fig. 2.Theoretical intensity distribution of AP non-diffracting beams,where l ¼632.8Â10À6mm,w ¼2mm,n ¼1.50,g ¼0.51,z ¼300mm.The arrows repre-sent the polarization direction.(For interpretation of the references to color in this figure caption,the reader is referred to the web version of thisarticle.)Fig.3.Theoretical intensity distribution of AP non-diffracting beams through polaroid polarizer with different angle of,where (a)y ¼01;(b)y ¼451;(c)y ¼901;(d)y ¼1351,respectively.The other parameters are the same as in Fig.1.The arrow represents the direction of polaroid polarizer.M.He et al./Optics Communications 294(2013)36–4237In the Cartesian coordinate system,the local azimuthal and radial components can be expressed by the following trans-formations e !r ¼e !x cos j þe !y sin je !j ¼e !y cos j Àe !x sin j :8<:ð3ÞAccording to the Collins formula [26],the y component ofazimuthally polarized beam through an axicon in free space can be expressed asE y r ,y ,z ÀÁ¼Ài lexp ikz ðÞZ 2p 0Z 10z U r U cos jÂexp Àr 2wexp Àik n À1ðÞg rÂÃÂexp ik r 2þr 2ÀÁ2z"#exp Àik r rz cos j Ày ÀÁ !rdrd j :ð4ÞFor simplicity,it is assumed that A ¼1.By introducing thefollowing formulae:exp ik r r z cos j Ày ÀÁ !¼X i lJ lk r r zexp il j Ày ÀÁÂÃ,ð5Þcos y ¼1exp i y ðÞþexp Ài y ðÞÂÃ,ð6Þsin y ¼Ài 2exp i y ðÞÀexp Ài y ðÞÂÃ,ð7ÞZ 2pexp ði m j Þd j ¼2p ,m ¼00,m a 0,(ð8Þwhere J l k r r =z ÀÁdenotes a Bessel function of the first kind,of order l .Eq.(4)can be further simplifiedasFig.4.(a)Intensity distribution in r–z plane;(b)intensity distribution of AP non-diffracting beams within the propagation range z ¼200mm–800mm;and (c)intensity distribution of AP non-diffracting beams within the propagation range z ¼800mm–1400mm.The other calculation parameters are same as that in Fig.1.M.He et al./Optics Communications 294(2013)36–4238E y r ,z ÀÁ¼Àk ðÞexp ikz ðÞexpik r 22zcos y ÂZ 10r 2w exp Àr 2w exp Àik n À1ðÞg r ÂÃexp ikr 22z J 1k r rz dr :ð9ÞSimilarly,the x component can be expressed as follows:E x r ,z ÀÁ¼k U exp ikz ðÞexpik r 2sin y ÂZ10r 2w exp Àr 2w2 exp Àik n À1ðÞg r ÂÃexpikr 22z J 1k r rzdr :ð10ÞThe cross section intensity distribution of AP non-diffractingbeams can be calculated by following formula:I r ,z ÀÁ¼E x r ,z ÀÁ 2þE y r ,z ÀÁ 2:ð11Þ3.Generation and propagation of AP non-diffracting beamsFig.1illustrates the experimental setups for generation AP non-diffracting beams.As shown in the figure,a Gaussian beam from aHe–Ne laser is expanded (f 1¼150mm and f 2¼300mm),and then is incident into a Radial Polarization Converter (RPC).The AP non-diffracting beam is produced by passing the AP beam through an axicon.The intensity distributions are recorded by theCCD.Fig.5.(a)Intensity distribution in r–z plane;(b)intensity distribution of AP non-diffracting beams within the propagation range z ¼100mm–500mm;and (c)intensity distribution of AP non-diffracting beams within the propagation ange z ¼500mm–700mm.g ¼1.01,the other calculation parameters are same as that in Fig.1.M.He et al./Optics Communications 294(2013)36–4239Fig.2shows the numerical simulation of the intensity dis-tribution of AP non-diffracting beams.The red arrows stand for the polarized direction of the beams.To better illustrate the polarized property,we present the cross sections of intensity distribution of AP non-diffracting beams through different angle (y,the angle with the horizontal direction)of polaroid polarizer. The white arrows in the Fig.3represent the polarized direction of the polaroid with(a)y¼01;(b)y¼451;(c)y¼901;(d)y¼1351, respectively.The results of Fig.3verified the azimuthally polar-ized property of the beams.The intensity distribution of AP non-diffracting beams through different taper angles of the axicon with g¼0.51and 1.01are shown in Figs.4and5,where(a)shows2D plot of intensity distribution in r–z plane,and(b)and(c)plot the normalized transverse profiles of intensity at different propagation distances. It can be seen in Fig.4(b)(g¼0.51)that all curves overlapped within the propagation range z¼200mm–800mm,indicating the non-diffracting property of the beam.The non-diffracting prop-erty disappears with distance larger than800mm,as shown in Fig.4(c).From the curves in Fig.5(b)and(c),it can be obtained that the non-diffracting range of the axicon with g¼1.01is z¼100mm–500mm.It can be concluded by comparing the results of Figs.4and5that the non-diffracting range decreases with the increasing taper angle of the axicon.This result is consistent with the previous researches[19].The experimental intensity distribution of the AP non-diffracting beams with l¼632.8Â10-6mm,w¼2mm,n¼1.50,g¼0.51and z¼300mm is presented in Fig.6.A polaroid polarizer is introduced after the axicon to detect the azimuthally polarized property of the beams.From Fig.7,we can see the AP non-diffracting beams through different angle of polaroid polarizer with(a)y¼01;(b)y¼451;(c) y¼901;(d)y¼1351,respectively.These experimental observations are consistent with the theoretical results in Fig.3.Fig.7.Experimental intensity distribution of AP non-diffracting beams through different angle of polaroid polarizer,where(a)y¼01;(b)y¼451;(c)y¼901;(d)y¼1351, respectively.The other parameters are the same as in Fig.1.The arrow represents the direction of polaroidpolarizer.Fig. 6.Experimental intensity distribution of AP non-diffracting beams withpropagation distance of z¼300mm,the other calculation parameters are sameas that in Fig.1.M.He et al./Optics Communications294(2013)36–42404.Self-reconstruction of the AP non-diffracting beams Self-reconstruction is an unusual property of Bessel beams,and has been extensively studied over the years [23–25].It is now understood that if an obstruction is placed within the validity region of a Bessel beam,it will self-reconstruct after some distance Z min .The distance Z min is the length of the shadow region behind the obstacle and it is approximately given as [25]Z min %Dtan n À1ðÞg ÂÃ%D n À1ðÞg ,ð12Þwhere D is the diameter of the obstruction,n is the refractive indexof the axicon,and g is the taper angle of the axicon.Furthermore,if the obstruction is placed off the optical axis,the self-reconstruction distance will become longer.To illustrate that AP non-diffracting beams also possess the ability of self-reconstruction upon encountering an obstruction,we used a sector-shaped obstacle with a ¼0.2p and r ¼1mm to block the AP non-diffracting beams,where a and r were the central angle and radius of the sector-shaped obstacle.Numerical simulations of the intensity distribution at the focal plane of the axicon are performed in the top row of Fig.8.It can be found that the ring-shaped intensity distribution is destroyed in a short propagation distance,while is reconstructed for a long propaga-tion distance.The region blocked by the sector-shaped obstacle which is overshadowed as observed began to self-reconstruct in Fig.8(a)at a distance of 100mm.Approximately at a distance 200mm from the obstruction we notice that the beam is partially reconstructed,as illustrated in Fig.8(b).And at a distance 300mm from the obstruction we notice a complete reconstruction of the beam,as illustrated in Fig.8(c).The complete reconstruction intensity patterns are similar to those of non-obstructed beams in Fig.2.If we use a circular-shaped obstacle with r ¼1mm (D ¼2mm)to block the AP non-diffracting beams,the shadow region is calculated to be Z min E 229mm after the obstructionusing the conventional reconstruction Eq.(12),this Z min is larger than that obtained by sector-shaped obstacle (Z min E 100mm).Clearly,the reconstruction distance depends on the dimension of the obstruction,the lagrer the obstruction is,the longer the reconstruction distance will be.The related experimental observations of the intensity distribu-tion of the blocked AP non-diffracting beams at three different positions are also given in the bottom row of Fig.8.As is obvious,the non-diffracting field disturbed by the obstacle is reconstructed to its initial intensity profile in the far region.The experimental observations are well consistent with the theoretical results.The results in Fig.8clearly indicate the self-reconstruction property of AP non-diffraction beams.5.ConclusionsThe AP non-diffracting beams have been generated and inves-tigated experimentally and theoretically.The beam propagates without diffraction within a certain distance,depending on the taper angle of the axicon.Besides that,the self-reconstruction characteristic of AP non-diffracting beams is verified.Such AP non-diffracting beams may have potential applications in particle trapping etc .AcknowledgmentsThis research was supported by the National Natural Science Foundations of China (Grant Nos.60977068and 61178015).References[1]K.S.Youngworth,T.G.Brown,Optics Express 7(2000)77.[2]C.J.R.Sheppard,S.Saghafi,Optics Letters 24(1999)1543.[3]B.Tian,J.Pu,Optics Letters 36(2011)2014.Fig.8.Cross section of intensity distribution at different positions of AP non-diffracting beams through the sector-shaped obstacle:theoretical (top)and experimental (bottom),where (a)z ¼100mm;(b)z ¼200mm;and (c)z ¼300mm,respectively.The dash line represents the sector-shaped obstacle.The other parameters are the same as in Fig.1.M.He et al./Optics Communications 294(2013)36–4241[4]G.H.Yuan,S.B.Wei,X.C.Yuan,Optics Letters36(2011)3479.[5]X.Hao,C.Kuang,T.Wang,X.Liu,Optics Letters35(2010)3928.[6]D.P.Brown,A.K.Spilman,T.G.Brwon,R.Borghi,S.N.Volkov,E.Wolf,OpticsCommunications281(2008)5287.[7]Q.Zhan,Advances in Optics and Photonics1(2009)1.[8]R.Dorn,S.Quabis,G.Leuchs,Physical Review Letters91(2003)233901.[9]Z.Chen,D.Zhao,Optics Letters37(2012)1286.[10]R.Peng,B.Yao,S.Yan,W.Zhao,M.Lei,Journal of the Optical Society ofAmerica B26(2009)2242.[11]Yuichi Kozawa,Shunichi Sato,Optics Express18(2010)10828.[12]T.A.Nieminen,N.R.Heckenberg,H.Rubinsztein-Dunlop,Optics Letters33(2008)122.[13]J.Durnin,Journal of the Optical Society of America A4(1987)651.[14]F.Gori,G.Guattari,C.Padovani,Optics Communications64(1987)491.[15]F.O.Farrbach,P.Simon,A.Rohrbach,Nature Photonics4(2010)780.[16]R.P.MacDonald,S.A.Boothroyd,T.Okamoto,J.Chrostowski, B.A.Syrett,Optics Communications122(1996)169.[17]V.Garces-Chavez,D.McGloin,H.Melville,W.Sibbett,K.Dholakia,Nature419(2002)145.[18]B.Lu,W.Huang,B.Zhang,Optics Communications119(1995)6.[19]G.Chen,H.Lin,J.Pu,Journal of Optoelectronics Laser22(2011)946.[20]J.Arlt,K.Dholakia,Optics Communications177(2000)297.[21]M.Anguiano-Morales, A.Martinez,M.D.Iturbe-Castillo,S.Chavez-Cerda,Applied Optics46(2007)8284.[22]Y.Lin,W.Seka,J.H.Eberly,H.Huang,D.L.Brown,Applied Optics31(1992)2708.[23]Z.Bouchal,J.Wagner,M.Chlup,Optics Communications151(1998)207.[24]S.H.Tao,X.Yuan,Journal of the Optical Society of America A21(2004)1192.[25]I.A.Litvin,M.G.McLaren,A.Forbes,Optics Communications282(2009)1078.[26]S.A.Collins,Journal of the Optical Society of America60(1970)1168.M.He et al./Optics Communications294(2013)36–42 42。
6603_Lecture2(3)
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Semester A, 2010
Wireless Communication Technologies
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电气工程及其自动化专业英语第二章课文翻译
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。
电力电子专业英语单词汇总
电力电子专业英语单词汇总电路的基本概念及定律电源 source电压源 voltage source电流源 current source理想电压源 ideal voltage source理想电流源 ideal current source伏安特性 volt-ampere characteristic电动势 electromotive force电压 voltage电流 current电位 potential电位差 potential difference欧姆 Ohm伏特 Volt安培 Ampere瓦特 Watt焦耳 Joule电路 circuit电路元件 circuit element电阻 resistance电阻器 resistor电感 inductance电感器 inductor电容 capacitance电容器 capacitor电路模型 circuit model参考方向 reference direction参考电位 reference potential欧姆定律Ohm’s law基尔霍夫定律Kirchhoff’s law基尔霍夫电压定律Kirchhoff’s voltage law（KVL）基尔霍夫电流定律Kirchhoff’s current law（KCL）结点 node支路 branch回路 loop网孔 mesh支路电流法 branch current analysis网孔电流法 mesh current analysis结点电位法 node voltage analysis电源变换 source transformations叠加原理 superposition theorem网络 network无源二端网络 passive two-terminal network有源二端网络 active two-terminal network戴维宁定理Thevenin’s theorem诺顿定理Norton’s theorem开路（断路）open circuit 短路 short circuit开路电压 open-circuit voltage短路电流 short-circuit current交流电路直流电路 direct current circuit (dc)交流电路 alternating current circuit (ac)正弦交流电路 sinusoidal a-c circuit平均值 average value有效值 effective value均方根值root-mean-squire value (rms)瞬时值 instantaneous value电抗 reactance感抗 inductive reactance容抗 capacitive reactance法拉 Farad亨利 Henry阻抗 impedance复数阻抗 complex impedance相位 phase初相位 initial phase相位差 phase difference相位领先 phase lead相位落后 phase lag倒相，反相 phase inversion频率 frequency角频率 angular frequency赫兹 Hertz相量 phasor相量图 phasor diagram有功功率 active power无功功率 reactive power视在功率 apparent power功率因数 power factor功率因数补偿 power-factor compensation串联谐振 series resonance并联谐振 parallel resonance谐振频率 resonance frequency频率特性 frequency characteristic幅频特性amplitude-frequency response characteristic相频特性 phase-frequency response characteristic 截止频率 cutoff frequency品质因数 quality factor通频带 pass-band带宽 bandwidth (BW)滤波器 filter一阶滤波器 first-order filter二阶滤波器 second-order filter低通滤波器 low-pass filter高通滤波器 high-pass filter带通滤波器 band-pass filter带阻滤波器 band-stop filter转移函数 transfer function波特图 Bode diagram傅立叶级数 Fourier series三相电路 three-phase circuit三相电源 three-phase source对称三相电源 symmetrical three-phase source对称三相负载 symmetrical three-phase load相电压 phase voltage相电流 phase current线电压 line voltage线电流 line current三相三线制 three-phase three-wire system三相四线制 three-phase four-wire system三相功率 three-phase power星形连接 star connection(Y-connection)三角形连接triangular connection(D- connection ,delta connection)中线 neutral line电路的暂态过程分析暂态 transient state稳态 steady state暂态过程，暂态响应 transient response换路定理 low of switch一阶电路 first-order circuit三要素法 three-factor method时间常数 time constant积分电路 integrating circuit微分电路 differentiating circuit磁路与变压器磁场magnetic field磁通 flux磁路 magnetic circuit磁感应强度 flux density磁通势 magnetomotive force磁阻 reluctance电动机直流电动机 dc motor交流电动机 ac motor异步电动机 asynchronous motor同步电动机 synchronous motor三相异步电动机 three-phase asynchronous motor 单相异步电动机 single-phase asynchronous motor 旋转磁场 rotating magnetic field定子 stator转子 rotor转差率 slip起动电流 starting current起动转矩 starting torque 额定电压 rated voltage额定电流 rated current额定功率 rated power机械特性 mechanical characteristic继电器-接触器操纵按钮 button熔断器 fuse开关 switch行程开关 travel switch继电器 relay接触器 contactor常开(动合)触点 normally open contact常闭(动断)触点 normally closed contact时间继电器 time relay热继电器 thermal overload relay中间继电器 intermediate relay可编程操纵器（PLC）可编程操纵器 programmable logic controller语句表 statement list梯形图 ladder diagram半导体器件本征半导体intrinsic semiconductor掺杂半导体doped semiconductorP型半导体 P-type semiconductorN型半导体 N--type semiconductor自由电子 free electron空穴 hole载流子 carriersPN结 PN junction扩散 diffusion漂移 drift二极管 diode硅二极管 silicon diode锗二极管 germanium diode阳极 anode阴极 cathode发光二极管 light-emitting diode (LED)光电二极管 photodiode稳压二极管 Zener diode晶体管（三极管） transistorPNP型晶体管 PNP transistorNPN型晶体管 NPN transistor发射极 emitter集电极 collector基极 base电流放大系数 current amplification coefficient 场效应管 field-effect transistor (FET)P沟道 p-channelN沟道 n-channel结型场效应管 junction FET（JFET）金属氧化物半导体 metal-oxide semiconductor (MOS)耗尽型MOS场效应管depletion mode MOSFET （D-MOSFET）增强型MOS场效应管enhancement mode MOSFET （E-MOSFET）源极 source栅极 grid漏极 drain跨导 transconductance夹断电压 pinch-off voltage热敏电阻 thermistor开路 open短路 shorted基本放大器放大器 amplifier正向偏置 forward bias反向偏置 backward bias静态工作点 quiescent point (Q-point)等效电路 equivalent circuit电压放大倍数 voltage gain总的电压放大倍数 overall voltage gain饱与 saturation截止 cut-off放大区 amplifier region饱与区 saturation region截止区 cut-off region失真 distortion饱与失真 saturation distortion截止失真 cut-off distortion零点漂移 zero drift正反馈 positive feedback负反馈 negative feedback串联负反馈 series negative feedback并联负反馈 parallel negative feedback共射极放大器 common-emitter amplifier射极跟随器 emitter-follower共源极放大器 common-source amplifier共漏极放大器 common-drain amplifier多级放大器 multistage amplifier阻容耦合放大器resistance-capacitance coupled amplifier直接耦合放大器 direct- coupled amplifier输入电阻 input resistance输出电阻 output resistance负载电阻 load resistance动态电阻 dynamic resistance负载电流 load current旁路电容 bypass capacitor耦合电容 coupled capacitor直流通路 direct current path交流通路 alternating current path 直流分量 direct current component交流分量 alternating current component变阻器（电位器）rheostat电阻（器）resistor电阻（值）resistance电容（器）capacitor电容（量）capacitance电感（器，线圈）inductor电感（量），感应系数inductance正弦电压 sinusoidal voltage集成运算放大器及应用差动放大器 differential amplifier运算放大器 operational amplifier(op-amp)失调电压 offset voltage失调电流 offset current共模信号 common-mode signal差模信号 different-mode signal共模抑制比 common-mode rejection ratio (CMRR) 积分电路 integrator（circuit）微分电路 differentiator（circuit）有源滤波器 active filter低通滤波器 low-pass filter高通滤波器 high-pass filter带通滤波器 band-pass filter带阻滤波器 band-stop filter波特沃斯滤波器 Butterworth filter切比雪夫滤波器 Chebyshev filter贝塞尔滤波器 Bessel filter截止频率 cut-off frequency上限截止频率 upper cut-off frequency下限截止频率 lower cut-off frequency中心频率 center frequency带宽 Bandwidth开环增益 open-loop gain闭环增益 closed-loop gain共模增益 common-mode gain输入阻抗 input impedance电压跟随器 voltage-follower电压源 voltage source电流源 current source单位增益带宽unity-gain bandwidth频率响应 frequency response频响特性（曲线）response characteristic波特图 the Bode plot稳固性stability补偿 compensation比较器 comparator迟滞比较器 hysteresis comparator阶跃输入电压step input voltage仪表放大器 instrumentation amplifier隔离放大器 isolation amplifier对数放大器 log amplifier反对数放大器antilog amplifier反馈通道 feedback path反向漏电流 reverse leakage current相位phase相移 phase shift锁相环 phase-locked loop(PLL)锁相环相位监测器 PLL phase detector与频 sum frequency差频 difference frequency波形发生电路振荡器 oscillatorRC振荡器 RC oscillatorLC振荡器 LC oscillator正弦波振荡器 sinusoidal oscillator三角波发生器 triangular wave generator方波发生器square wave generator幅度 magnitude电平level饱与输出电平（电压） saturated output level功率放大器 power amplifier交越失真 cross-over distortion甲类功率放大器 class A power amplifier乙类推挽功率放大器class B push-pull power amplifierOTL功率放大器output transformerless power amplifierOCL功率放大器output capacitorless power amplifier直流稳压电源半波整流 full-wave rectifier全波整流 half-wave rectifier电感滤波器 inductor filter电容滤波器 capacitor filter串联型稳压电源 series (voltage) regulator开关型稳压电源 switching (voltage) regulator集成稳压器 IC (voltage) regulator晶闸管及可控整流电路晶闸管 thyristor单结晶体管 unijunction transistor（UJT）可控整流 controlled rectifier可控硅 silicon-controlled rectifier峰点 peak point谷点 valley point操纵角 controlling angle导通角 turn-on angle门电路与逻辑代数二进制 binary二进制数 binary number十进制 decimal十六进制 hexadecimal 二-十进制 binary coded decimal （BCD）门电路 gate三态门tri-state gate与门 AND gate或者门 OR gate非门 NOT gate与非门 NAND gate或者非门 NOR gate异或者门 exclusive-OR gate反相器 inverter布尔代数 Boolean algebra真值表 truth table卡诺图 the Karnaugh map逻辑函数 logic function逻辑表达式 logic expression组合逻辑电路 combination logic circuit译码器 decoder编码器 coder比较器 comparator半加器 half-adder全加器 full-adder七段显示器 seven-segment display时序逻辑电路 sequential logic circuitR-S 触发器 R-S flip-flopD触发器 D flip-flopJ-K触发器 J-K flip-flop主从型触发器 master-slave flip-flop置位 set复位 reset直接置位端direct-set terminal直接复位端direct-reset terminal寄存器 register移位寄存器 shift register双向移位寄存器bidirectional shift register 计数器 counter同步计数器 synchronous counter异步计数器asynchronous counter加法计数器 adding counter减法计数器 subtracting counter定时器 timer清除（清0）clear载入 load时钟脉冲 clock pulse触发脉冲 trigger pulse上升沿 positive edge下降沿 negative edge时序图 timing diagram波形图 waveform单稳态触发器 monostable flip-flop双稳态触发器 bistable flip-flop无稳态振荡器 astable oscillator晶体 crystal 555定时器 555 timer模拟信号 analog signal数字信号 digital signalAD转换器analog -digital converter (ADC)DA转换器 digital-analog converter (DAC)半导体存储器只读存储器 read-only memory（ROM）随机存取存储器 random-access memory（RAM）可编程ROM programmable ROM（PROM）常见英文缩写解释（按字母顺序排列）：ASIC: Application Specific Integrated Circuit. 专用ICCPLD: Complex Programmable Logic Device. 复杂可编程逻辑器件EDA: Electronic Design Automation. 电子设计自动化FPGA: Field Programmable Gate Array. 现场可编程门阵列GAL: Generic Array Logic. 通用阵列逻辑HDL: Hardware Description Language. 硬件描述语言IP: Intelligent Property. 智能模块PAL: Programmable Array Logic. 可编程阵列逻辑RTL: Register Transfer Level. 寄存器传输级描述）SOC: System On a Chip. 片上系统SLIC: System Level IC. 系统级ICVHDL: Very high speed integrated circuit Hardware Description Language. 超高速集成电路硬件描述语言。
机电专业英语讲义.ppt.Convertor
机电专业英语复习资料一 1.1 Bipolar junction transistorsToday, industrial electronic systems employseveral devices that are described by the term transistor. Each type of transistor has different characteristics and operational conditions that are used to distinguish it from others.每种晶体管都有区别于其它种类的特征和工作环境。
In the first part of this discussion, we are concerned with the . Structurally, this transistor is described as bipolar because it has two different current-carrier polarities.首先探讨双极型晶体管。
从结构上看，这种晶体管被称为双极是因为它具有两种不同的电流载流子电极。
Holes are positive current carriers, whereas electrons are negative current carriers.空穴是正的载流子，电子是负的电流载流子。
Two distinct kinds of semiconductor crystals are connected together by a common element. 两种截然不同的半导体晶体通过公共元件连接在一起。
The structure of this device is similar to that of two diodes connected back to back, with one crystal being common to both junctions. The center material is usually made thinner than the two outside pieces. 该器件的结构类似于背靠背连接的两个二极管的结构，一个晶体同时属于两个结。
电力专业英文
电力系统power system发电机generator励磁excitation励磁器excitor电压voltage电流current升压变压器step-up transformer 母线bus变压器transformer空载损耗no-load loss铁损iron loss铜损copper loss空载电流no-load current有功损耗active loss无功损耗reactive loss输电系统power transmission system高压侧high side输电线transmission line高压high voltage低压low voltage中压middle voltage功角稳定angle stability稳定stability电压稳定voltage stability暂态稳定transient stability电厂power plant能量输送power transfer交流AC直流DC电网power system落点drop point开关站switch station调节regulation高抗high voltage shunt reactor 并列的apposable裕度margin故障fault三相故障three phase fault分接头tap切机generator triping高顶值high limited value静态static (state) 动态dynamic (state)机端电压控制AVR电抗reactance电阻resistance功角power angle有功（功率）active power电容器Capacitor电抗器Reactor断路器Breaker电动机motor功率因数power-factor定子stator阻抗impedance功角power-angle电压等级voltage grade有功负载: active load PLoad无功负载reactive load档位tap position电阻resistor电抗reactance电导conductance电纳susceptance上限upper limit下限lower limit正序阻抗positive sequence impedance负序阻抗negative sequence impedance零序阻抗zero sequence impedance 无功（功率）reactive power功率因数power factor无功电流reactive current斜率slope额定rating变比ratio参考值reference value电压互感器PT分接头tap仿真分析simulation analysis下降率droop rate传递函数transfer function框图block diagram受端receive-side同步synchronization保护断路器circuit breaker摇摆swing阻尼damping无刷直流电机Brusless DC motor刀闸(隔离开关) Isolator机端generator terminal变电站transformer substation永磁同步电机Permanent-magnet Synchronism Motor异步电机Asynchronous Motor三绕组变压器three-column transformer ThrClnTrans双绕组变压器double-column transformer DblClmnTrans固定串联电容补偿fixed series capacitor compensation双回同杆并架double-circuit lines on the same tower单机无穷大系统one machine - infinity bus system励磁电流Magnetizing current补偿度degree of compensation电磁场:Electromagnetic fields失去同步loss of synchronization装机容量installed capacity无功补偿reactive power compensation故障切除时间fault clearing time极限切除时间critical clearing time 强行励磁reinforced excitation并联电容器shunt capacitor<下降特性droop characteristics线路补偿器LDC(line drop compensation) 电机学Electrical Machinery自动控制理论Automatic Control Theory电磁场Electromagnetic Field微机原理Principle of Microcomputer 电工学Electrotechnics电路原理Principle of circuits电机学Electrical Machinery电力系统稳态分析 Steady-State Analysis of Power System电力系统暂态分析Transient-State Analysis of Power System电力系统继电保护原理 Principle of Electrical System's Relay Protection电力系统元件保护原理 Protection Principle of Power System 's Element电力系统内部过电压Past Voltage within Power system模拟电子技术基础Basis of Analogue Electronic Technique数字电子技术Digital Electrical Technique电路原理实验Lab. of principle of circuits电气工程讲座Lectures on electrical power production电力电子基础Basic fundamentals of power electronics 高电压工程High voltage engineering电子专题实践Topics on experimental project of electronics 电气工程概论Introduction to electrical engineering电子电机集成系统Electronic machine system电力传动与控制 Electrical Drive and Control电力系统继电保护Power System Relaying Protection主变压器main transformer升压变压器step-up transformer降压变压器step-down transformer工作变压器operating transformer备用变压器standby transformer公用变压器common transformer三相变压器three-phase transformer单相变压器single-phase transformer带负荷调压变压器on-load regulating transformer 变压器铁芯transformer core变压器线圈transformer coil变压器绕组transformer winding变压器油箱transformer oil tank变压器外壳transformer casing变压器风扇transformer fan变压器油枕transformer oil conservator(∽drum变压器额定电压transformer reted voltage变压器额定电流transformer reted current变压器调压范围transformer voltage regulation rage配电设备power distribution equipment SF6断路器SF6 circuit breaker开关switch按钮button隔离开关isolator,disconnector 真空开关vacuum switch刀闸开关knife-switch接地刀闸earthing knife-switch 电气设备electrical equipment 变流器current converter电流互感器current transformer 电压互感器voltage transformer 电源power source交流电源AC power source直流电源DC power source工作电源operating source备用电源Standby source强电strong current弱电weak current继电器relay信号继电器signal relay电流继电器current relay电压继电器voltage relay跳闸继电器tripping relay合闸继电器closing relay中间继电器intermediate relay时间继电器time relay零序电压继电器zero-sequence voltage relay 差动继电器differential relay闭锁装置locking device遥控telecontrol遥信telesignalisation遥测telemetering遥调teleregulation断路器breaker,circuit breaker少油断路器mini-oil breaker,oil-mini-mum breaker高频滤波器high-frequency filter组合滤波器combined filter常开触点normally opened contaact常闭触点normally closed contaact并联电容parallel capacitance保护接地protective earthing熔断器cutout,fusible cutout电缆cable跳闸脉冲tripping pulse 合闸脉冲closing pulse一次电压primary voltage二次电压secondary voltage并联电容器parallel capacitor无功补偿器reactive power compensation device 消弧线圈arc-suppressing coil母线Bus,busbar三角接法delta connection星形接法Wye connection原理图schematic diagram一次系统图primary system diagram二次系统图secondary system diagram两相短路two-phase short circuit三相短路three-phase short circuit单相接地短路single-phase ground short circuit短路电流计算calculation of short circuit current 自动重合闸automatic reclosing高频保护high-freqency protection距离保护distance protection横差保护transverse differential protection纵差保护longitudinal differential protection 线路保护line protection过电压保护over-voltage protection母差保护bus differential protection瓦斯保护Buchholtz protection变压器保护transformer protection电动机保护motor protection远方控制remote control用电量power consumption载波carrier故障fault选择性selectivity速动性speed灵敏性sensitivity可靠性reliability电磁型继电器electromagnetic无时限电流速断保护instantaneously over-current protection跳闸线圈trip coil工作线圈operating coil制动线圈retraint coil主保护main protection后备保护back-up protection定时限过电流保护definite time over-current protection三段式电流保护the current protection with three stages反时限过电流保护inverse time over-current protection 方向性电流保护the directional current protection零序电流保护zero-sequence current protection阻抗impedance微机保护Microprocessor Protection电力行业词汇（中英）保护特性protection feature标准的机组数据显示 (Standard Measurement And Display Data) 波形waveform采样频率sampling frequency采样周期sampling period参数值parameter values测量信号measurement signal超高压输电线supervltage transmission power line超速故障停机 Overspeed Shutdowns初探primary exploration大容量发电机组large capacity generating set大小相等，方向相反equal and opposite in direction怠速-快速运行选择键 Idle Run – Normal Run Selector Switch 单相/三相电压 Voltage by One/Three Phase (Volt.)等效于equivalent等值波阻抗equivalent value wave impedance低油压故障停机 Low Oil Pressure Shutdowns电力系统the electrical power system电力系统自动化power system automation电瓶电压表 Battery Voltage Meter电位electric potential电压electric voltage电压源voltage source动作速度speed of action短路故障short trouble反传算法backpropagation algorithm仿真simulation仿真数据simulation data非线性系统nonlinear system负荷状态load conditions负载电流百分比显示 Percentage of Current load(%)附加网络additional network附加系统add-ons system副教授associate professor高精度high accuracy高水温故障停机 High Coolant Temperature Shutdowns给定的given工频power frequency功率因数 Power Factor (PF)故障点trouble spot机油油压表 Oil Pressure Gauge机组运行小时表 Genset Running Hour Meter机组运行正常 Normal Running继电保护relaying protection减法运算subtraction抗干扰能力antijamming capability可靠动作action message冷却水温度表 Coolant Temperature Gauge隶属函数membership function灵敏性sensitivity每相电流 Current by Phase (AMP)门槛值threshold level模糊规则fuzzy rule模糊控制fuzzy control模糊神经网络fuzzy-neural network模糊推理fuzzy reasoning模糊推理矩阵fuzzy reasoning matrix偏移量side-play mount频率 Frequency(HZ)其它故障显示及输入 Other Common Fault Alarm Display and起动失败停机 Fail to Start Shutdowns千阀 Reactive Power (KVAr)千伏安 Apparent Power (KVA)千瓦 Active Power (KW)求和器summator区内故障troubles inside the sample space全面地all sidedly三角形隶属度函数Triangle-shape grade of membership function 神经网络neural network神经元neuron输出千瓦/兆瓦小时 Output kWh/MWh输电距离electricity transmission输电线路故障transmission line malfunction算法algorithm投运commissioning误动作malfunction相减运算additive operation小波变换wavelet transformation谐波电流harmonic current行波travelling wave行波保护Traveling wave protection行波继电器travelling wave relay行波信号travelling wave signal修改的modified学报 journal延迟变换delayed transformation延迟时间delay time研究方向 research direction样本集合 sample set样本空间sample space运行-停机-摇控启动选择键 Local Run-Stop-Remote Starting Selector Switch 运行转速 Running RPM暂态分量transient state component暂态行波transient state travelling wave中国电力 China Power中线电流 Neutral Current (N Amp)子系统subsystem自适应控制方法adaptive control process自适应系统adaptive system自学习功能selflearning function最高/低电压及电流 Max/Min. Current and Voltage电力专业术语英汉对照表电力专业术语英汉对照表突然损失发电机或线路：sudden loss of a generator or transmission line. 负荷突然增加或减少：sudden load increases or decreases短路和开关操作：short circuits and switching operations.三相和对地短路：three-phase and line-to-ground faults短路器：circuit breaker暂态过电压和电流：transient overvoltages and currents雷击：lightning strikes电涌放电器：surge arrester相量：phasor，通常用复数phasors瞬时功率：instantaneous power特别地：In particular,正弦电压或电流：A sinusoidal voltage or current [u]at[/u] constant frequency最大值：maximum value有效值：effective value平均值：average value坐标系实轴：real axis坐标系虚轴：imaginary axis相量图：phasor diagram [u]for[/u] …无源元件：passive elements电阻、电感、电容、电抗：resistor, inductor, and capacitor, reactance, 感性、容性：inductive, capacitive有功功率：real power or active power无功功率：reactive power功率因数：power factor功率因数角：power factor angleA single-phase source delivers 100kW to a load operating at a power factor of 0.8 lagging.AC relay 交流继电器Abnormal information 异常信息abnormal load 不规则负荷absorption capacitor 吸收电容器active load 有功负荷active loss 有功损耗active power 有功active power balance 有功电力平衡Adaptive control 自适应控制Air conditioning loads 空调负荷Alert state 警戒状态alternating current 交流alternating current commentator motor 交流换向器电动机alternating field 交变场Analytical solution 解析法angle stability 功角稳定Angular velocity 角频率asynchronous 异步的Asynchronous Motor 异步电机Asynchronous operation of a synchronous machine 同步电机异步运行ABC Automatic bias compensation 自动偏压补偿automatic field-suppressing 自动灭磁Automatic generator control 自动发电控制Automatic supervision function 自检功能Automatic voltage regulator 自动电压调节器recloser 自动重合闸Available transfer capability 可传输能力Backbone 主网架Backup protection 后备保护Base load set 基本负荷机组basic theory of circuitry 电路基本理论blackout 停电Brittle, fragile 脆弱Bulk power system 大型电力系统bulk transmission system 大容量输电系统Bundled conductor 分裂导线bus bar 母线Cable 电缆Capability curves 运行极限图cascading failure 连锁故障condenser 调相机Conditional stability of a power system 电力系统条件稳定性Constant active power load 恒功率负荷Constant energy loads 恒能量负荷Contingency screening and ranking 事故筛选与排序continuous current generator 直流发电机conversion equipment 换流设备Converter 整流器copper loss 铜耗Corona 电晕critical clearing time 极限切除时间Critical voltage 临界电压curve fitting 曲线拟合Customer power 定制电力daily load curves 日负荷曲线damping 阻尼DC converter 直流换流器degree of compensation 补偿度destabilizing perturbation 不稳定扰动digital sampling control 数字采样控制DC Direct current 直流direct current transmission 直流输电Distribution network配电网Distribution voltage regulator 配电电压调整Disturbance 扰动Dynamic analysis method 动态分析方法dynamic reactive power compensation 动态无功补偿Dynamic simulation 动态仿真dynamic stability 动态稳定DVR Dynamic voltage restorer 动态电压恢复器earth fault 接地故障Economic loading schedule 经济承载计划Effective short circuit ratio 有效短路比electric apparatus 电气设备，电气装置，；电机；电器electric drive 电力传动electrical braking 电气制动Electrical islanding 电器孤岛electronic commutation 电子换向，电子整流emergency state 紧急状态EMS energy management system 能量管理系统Epoch angle 初相角equal incremental cost rule 等微增率准则equal-area criterion 等面积定则Equilibrium 平衡Equilibrium point 平衡点equivalent circuit 等值电路equivalent network 等值电网excitation 励磁excitation control 励磁控制Fast fault clearing 快速故障切除装置Fault clearance time 故障清除时间Fault location 故障定位Ferror-resonance 铁磁谐振field regulator 励磁调节器Filter 滤波器fixed series capacitor compensation 固定串联电容补偿flexibility 灵活性FACTS Flexible AC transmission system 柔性交流输电Frequency drift 频率漂移frequency response characteristics 频率特性Fundamental frequency temporary voltage 基频短时过电压fuzzy identification 模糊识别generation capacity 装机容量generation mix 多能源发电Generation schedule 发电计划Generation shedding 切机Generator capability curve 发电机运行极限图Generator Q-V curve 发电机Q-V曲线generator terminal 机端generator tripping 切机Governor power flow 调速器潮流harmonic 谐波harmonic distortion 谐波畸变High pass filter 高通滤波器High performance excitation system 高性能励磁系统high voltage shunt reactor 高抗High-side voltage control 高压侧电压控制Hunting of interconnected synchronous machines 并联同步电机振荡hydro generation 水力发电厂Induction motor 感应电动机Inherent stability of a power system 电力系统固有稳定性Initial mechanical power 初始机械转矩In-phase (voltage)control 纵向电压调节instability criterion 不稳定性判据installed capacity 装机容量Insulation fault 绝缘故障intangible depreciation 无形损耗integrated system 综合系统interconnected systems 互联系统internal combustion 内燃机Interrupt 开断Inverter 逆变站Inverter control 逆变器控制iron loss 铁耗isolator 刀闸（隔离开关）LDC LDC(line drop compensation) 线路补偿器Line Commutation 电网换流Line drop compensation 线路压降补偿Load characteristic 负荷特性load curve 负荷曲线load disconnection 切负荷Load diversity 负荷不同时性Load dynamics 负荷动态Load factor 负荷率load forecasting 负荷预测Load patterns 负荷形式Load rejection 甩负荷load reserve 负荷备用load saturation curve 负载饱和曲线Load shedding 切负荷LTC Load tap changing 有载调压Load testing 负荷测试Load-ability curve 负荷能力曲线load-frequency and load-voltage characteristics 负荷特性Loss of synchronism 同步失稳low frequency oscillation 低频振荡low water condition year 枯水年lower limit 下限Magnetic and electric field 电磁场magnetizing current 励磁电流Management forecast of a system 电力系统预测负荷Mature power system 饱和电力系统mean absolute deviation 平均绝对偏差measurement of phase sequence and phase angle 相序和相位测量mechanical stability against short circuit 动稳定性MSC Mechanically switched capacitors 机械投切电容器Mid-term stability 中期电压稳定Modal analysis 模型分析modulator 调制器Negative (sequence) component 负序分量negative damping负阻尼negative sequence impedance 负序阻抗feeder 馈电线Network maximum power transfer 网络最大传输能力network optimization 电网优化Neutral 中性点Nodal admittance matrix 节点导纳矩阵no-load current 空载电流nonlinear control 非线性控制nonlinear model 非线性模型one machine - infinity bus system 单机无穷大系统Online security assessment 在线安全估计OLTC On-load tap changing 有载调压Operating point 运行点optical operation collapse prevention 灾变防治optimal control 最优控制optimal power flow 最优潮流ORF optimal reactive power 无功优化optimization of reactive power distribution 无功功率最优分布Optimum load 经济负荷Optimum power flower 有功潮流优化oscillation 振荡Oscillatory instability 振荡不稳定Oscillatory voltage instability 振荡性电压失稳outage 断电Outage state 停运状态Out-of-step operation 失步运行Over-excitation limiter 过励磁限制器Overload capacity 过载能力Over-voltage 过电压parallel AC/DC 交直流并联Past Voltage within Power system 电力系统内部过电压Per Unit 标幺值Per unit system 标幺制系统perturbation theory 小扰动理论Positive (sequence) component 正序分量positive sequence impedance 正序阻抗Post-disturbance stability 扰动后电压稳定Post-transient stability 暂态后电压稳定Potential 电位potential distribution 电位分布Power circle diagram 功率圆Power factor 功率因数Power flow simulation 潮流仿真power frequency voltage 工频电压Power instability 功率不稳定性power line/over head 功率损线power plant 发电厂Power quality 电能质量Power shortfall 电力短缺Power system abnormality 电力系统异常Power system fault 电力系统故障Power system management 电力系统管理Power system planning 电力系统规划Power system stability 电力系统稳定性Power transmission line 输电线power(load) flow 电力潮流power-angle 功角power-factor 功率因数Power-regulation coefficient of load 负荷的功率调节系数primary power-system 一次系统pulse 脉动Power quality 电能质量quick action 速动，快动，快作用quick action valve 速动阀，快动阀门Radial operation 辐射运行Radial system 辐射型系统reactive compensation equipment 无功补偿装置reactive component 无功分量reactive load 无功负荷reactive loss 有功损耗reactive power 无功reactive power absorption 无功功率吸收reactive power compensation 无功补偿reactive power dispatch 无功调度reactive power distribution 无功分布reactive power flow 无功潮流Reactive power margin 无功功率裕度reactive power source 无功电源reactive-load compensation equipment 无功补偿设备reactor 电抗器receiving system 接收系统Rectifier 整流站Redundant equipment 冗余Region of attraction 吸引域reinforced excitation 强行励磁Reinforcement of a system 电力系统改造relay failure disoperation 误动作reliability 可靠性Reliability criteria 可靠性准则reliability evaluation 可靠性评估reliability of transmission system 输电系统可靠性remote kilowatt-hour-meter reading 远方自动抄表retarding/synchronizing torque 阻滞转矩/同步转矩robust 鲁棒性Rotor 转子Rotor angle stability 功角稳定性rotor coil 转子线圈Schematic 示意图secondary power-system 二次系统security monitoring 安全监视Self-(or mutual) induction 自（互）感Self-synchronization 自同步series capacitor 串联电容器series compensation 串联补偿Severe voltage dip 电压跌落严重Short circuit capacity 短路容量Short circuit ratio 短路比SC shunt capacitor 并联电容器shunt commutator motor 并励换向器式电动机shunt reactor 并联电抗器simulation analysis 仿真分析Skin effect 集肤效应Slip 转差stability 稳定性Stability limit of a system state variable 系统状态变量稳定极限Stability margin of a system state variable 系统状态变量稳定裕度Stability zone 稳定区Stall-prone motor 堵转电机State estimation 状态估计State transition diagram 状态转移图Static models 稳态模型SVC static var compensator 静止无功补偿器，静止无功补偿装置SVG static var generator 静止无功发生器Static voltage stability analysis 静态电压稳定分析方法Stator 定子steady short-circuit current 稳态短路电流steady state operation 稳态运行steady-state analysis 稳态分析steady-state analysis of power system 电力系统稳态分析Steady-state load characteristic 静态负荷特性steady-state stability 静态稳定Steady-state stability of a power system 电力系统静态稳定性stochastic modeling 随机模型(统计建模)Sub synchronous resonance 次同步谐振substation 变电站Sufficient resilience 足够的恢复能力SCADA Supervisory control and data acquisition system 监视控制和数据收集系统Supply-interruption costs 停电费用Surge impedance 波阻抗surge impedance loading 冲击阻抗Surge voltage 冲击电压swing 摇摆Swing curve 摇摆曲线switching station with single bus 单母线配电站Switchyard 开关站Synchronism restoration 再同步synchronize 同步Synchronous condenser 同步调相机Synchronous operation of a machine 电机同步运行Synchronous time 同步时间SPC System protection centre 系统保护中心System black start generator 系统黑启动发电机System demand control 系统需量控制SPT System protection terminals 系统保护终端System reliability 系统可靠性System robustness 系统的鲁棒性tap 分接头Tap changer instability 分接头不稳定性Terminal voltage 端电压The time-overload limit of transmission lines 输电线路过载时间限制Thermal capacity 热容量Thermal limit 热极限Thermostatically-controlled heating loads 温控加热负荷threefold line of defense 三道防线three-phase fault 三相故障three-phase ungrounded fault 三相非接地短路故障Time frame 时间框架Tolerance 容差topological structure 拓扑结构Torque-slip curve 转矩-转差曲线Transfer limits 传输极限transformer amplifier 变压器耦合放大器Transient angle instability 瞬时功角失稳Transient load characteristic 暂态负荷特性transient overreach 暂态超越Transient rotor angle stability 暂态功角稳定transient stability 暂态稳定Transient voltage stability 暂态电压稳定transient-state analysis of power system 电力系统暂态分析transmission and distribution energy losses 线损Transmission grid 输电网transmission line 输电线Transmission losses 输电损耗transmission network 输电网trigger amplifier 触发放大器turbine generation 汽轮发电厂two-step earth-fault protection 二级接地保护ULTC blocking ULTC闭锁ULTC under load tap changer 有载调压变压器Under-frequency load shedding 低频减载Under-voltage load shedding 低压减载unit commitment 开停机计划UPFC United power flow controller 联合潮流控制器unstable equilibrium point 不稳定平衡点unstable oscillation 不稳定运行unsymmetrical short-circuit 不对称短路upper limit 上限urgency control system 紧急控制系统Utilization time of power losses 最大功率损耗等值时间v-curve V形曲线vibration absorber 减振器，消振器，振动吸收器voltage collapse 电压崩溃VCPI Voltage Collapse Proximity Indicator 电压崩溃邻近指标Voltage control 电压控制Voltage control area 电压控制区域voltage curve 电压曲线Voltage fluctuation 电压波动voltage grade 电压等级Voltage instability mechanisms 电压失稳机理voltage profile 电压分布Voltage reduction 电压降低voltage regulation 电压调整Voltage security 电压安全Voltage sensitive load 电压灵敏性负荷Voltage sensitivity 电压灵敏性Voltage stability 电压稳定Voltage stability factor 电压稳定因子Voltage stability limit 电压稳定极限Voltage stability margin 电压稳定裕度voltage stresses 电压强度Voltage-weak point 弱电压节点V-Q curves V-Q曲线vulnerability 脆弱性Weather sensitive loads 对天气变化灵敏的负荷WAPS Wide Area Protection System 广域保护系统wireless radio-controlled 无线控制zero (sequence) component 零序分量zero sequence reactance 零序电抗abnormal overload 异常过载，事故过载active power 有功功率ampere-hour efficiency 充电效率aperiodic damping 非周期阻尼arithmetic circuitry 运算电路capacitive voltage transformer 电容式电压互感器closed electric circuit 闭合电路de-energizing circuit 去激电路，去励磁电路distribution network 配电网earthing arrangement 接地系统electrical phase angle 电相（位）角electronic transducer 电子式互感器end pressure 端部压力energy conversion factor 能量转换系数equivalent admittance 等效导纳equivalent generator 等效发电机equivalent parameter 等效参数，等值参数equivalent reactance 等效电抗，等值电抗equivalent resistance 等效电阻，等值电阻excitation characteristic 励磁特性extended uncertainty 扩展不确定度faulty line selection 故障选线Ferro resonance 铁磁谐振field inspection 现场检验fully energized 全激励，满励磁fundamental frequency 基本频率，基频high tension lead 高压引线insulation 绝缘interrupt mode 中断模式inverter 逆变器Laplace's transformation 拉普拉斯变换，拉氏变换leakage magnetic flux 漏磁通load of normal running 正常运行负荷measuring apparatus 测量装置mechanical strength 机械强度monitoring apparatus 监控装置negative feedback amplifier 负反馈放大器neutral 中性点neutral lead 中性点引出线nodal admittance matrix 节点导纳矩阵open-circuit characteristic 开路特性，空载特性optimal allocation 最佳分配，最优配置optimal design 优化设计output end 输出端phase-frequency 相频physics distributing 物理分布polarity check 极性检测potential transformer 电压互感器power factor 功率因数power rush 功率冲击，功率骤增practical capacity 实际容量proportional gain 比例增益reactance amplifier 电抗耦合放大器reactive power absorption 无功功率吸收reactive power compensation 无功补偿realistic model 仿真模型resonance characteristic 谐振特征rotor winding 转子绕组，转子线圈running load 运行负载rupturing current 切断电流safety impedance 安全阻抗sampling function 采样函数sampling period 采样周期scheduling algorithm 调度算法secondary wiring mode 二次接线方式shielding windings 屏蔽绕组single-phase rotor 单相转子the stability and reliability 稳定性和可靠性three phase current transformers 三相电流互感器time to chipping 截断时间track-and-hold amplifier 跟踪保持式放大器transfer admittance 转移导纳transformer amplifier 变压器耦合放大器transient signal 暂态信号transistor amplifier 晶体管放大器voltage feedback amplifier 电压反馈放大器wave analyzer 波形分析器wavelet transform 小波变换。
Lecture2
Broadband signaling – Data is carried on high frequency carrier waves – Carrying capacity of medium divided into number of sub-channels, such as video, low speed data, high speed data, voice, etc. – allows medium to satisfy several communication needs.
ELEC3506 Data Communications and Internet by Dr Kumudu Munasinghe
16
Phase Shift Keying (PSK)
Phase of the carrier signal is varied to represent binary 1 or 0. Amplitude and Frequency remains constant. The simplest is Binary PSK
ELEC3506 Data Communications and Internet by Dr Kumudu Munasinghe
2
Transmission Medium
ELEC3506 Data Communications and Internet by Dr Kumudu Munasinghe
Fundamental Concepts Digital and Analog Signals Signal Encoding and Modulation Multiplexing Switching Transmission Media Propagation Modes Network Topologies
新世纪大学英语综合教程1-第二版-课文详解-LectureNotesU1
Electro nic Teachin g Portfol ioBook OneUnit One: College LifePart I Get StartedSection A Discuss ion▇Sit in groupsof threesor fours and discuss the followi ng questio ns.1.You may have imagine d what college life would be like beforeyou becamea college student. Has itturnedout to be what you expecte d? Provide example s in support of your answers.2.Wheneve r you think about college life, what are some of the thingsthat come to mind? Followi ng theexample s given, make a list of such thingsin the followi ng table. Share your answers with your group members and comment on each of the items you have listedas you go along.College Lifeassignm entsdeadlin es…3.How do you like your college life so far? Give example s.4.What do you think is the most importa nt thing to achieve at college? Explain.▇ Answers for referen ce:1. Possibl e positiv e comment s on college life may include the followi ng:academi c atmosph ere, good student accommo dation s, modernfacilit ies for teachin g and researc h, qualifi ed profess ors, nice classma tes, etc.Possibl e negativ e comment s on college life may include the followi ng:hard to get adjuste d to the new environ ment, academi c pressur e, homesic kness, problem s in interpe rsonal relatio nships, poor food, etc.2.College Life assignm ents deadlin estuitionproject sfriends hip roommat esteststeacher sclassma tes graduat ion gradesacademi c pressur e3. Possibl e example s are: carefre e and colorfu l life, academi c environ ment, friends hip, a door leading to the outside world, etc.However, college life may also be boringfor some student s, because most of their time is spent on study, and they are far away from home, etc.4. Possibl e answers are: academi c excelle nce, develop ing communi cative skillsand interpe rsonal relatio nshipsSection B Quotes▇Study the followi ng quotesabout educati on and see if you acceptthe ideas express ed in the quotes.Ralph Waldo Emerson⊙The thingstaughtin schools and college s are not an educati on, but the means to an educati on.— Ralph Waldo EmersonInterpr etatio n:Wedon’tgotoschoolor college to learn, but to seek the way to learn.About R. W. Emerson(1803–1882): R. W. Emerson,a US poet and writerwho had great influen ce on thereligio us and philoso phical thought of his time.W. B. Y eats⊙ Educati on is not the filling of a pail, but the lightin g of a fire.— W. B. Y eatsInterpr etatio n:Instead of stuffin g student s with knowled ge, real educati on aims at bringin g out what is insidestudent s andcultiva ting their potenti al.About W. B. Y eats (1865–1939): W. B. Y eats, an Irish writerof poems and plays, whose early work is oftenbased on old Irish stories. He is conside red one of the most importa nt Irish writers, and he won the Nobel Prizefor Literat ure in 1923.Galileo⊙ You cannotteach a man anythin g; you can only help him find it withinhimself.—GalileoInterpr etatio n:Teachin gdoesn’treallyhelp anyone, but it helps a personfind out what he/she is good at.About Galileo(1564–1642): Galileo, an Italian astrono mer, mathema tician, and physici st whose manydiscove ries had a great influen ce on modernscience. He discove red mountai ns and craters (月球表面的环形山) on the surface of the Moon, and his study of the changes in the appeara nce of V enus (金星) provedthat it was movingaroundthe Sun. He also discove red that if you drop objects of differe nt weights from a high place, they fall at the same speed. He was punishe d by the inquisi tion (宗教法庭) because he believe d that the Sun, not the Earth, was the centreof the univers e.Section C Watchin g and Discuss ion▇Watch the followi ngvideoclip“HowtoSelectYour College major”anddothetasksthatfollow:插入视频片段：―HowtoSelect.wmv‖1.Fill in the missing words accordi ng to what you hear from the video clip.Hi, this is Laura Turner,andtodayI’mgoingtota lk to you about how to selectyour college major. I would like to tell you that if you selectsomethi ngthatyouloveandthatyou’repassion ate about, everyth ing’sgoingtobefineandyou’regoingtogetagreatjobwith your degree, but of coursethis is not complet ely true. However, whenyou’regoingtocollege, your primary reasonfor going to college is to educate yoursel f, which means to make yoursel f a betterpersonboth intelle ctuall y, spiritu ally, mentall y, all of these things.2.Discuss the topic with your group members:What are the recomme nded concern s in selecti ng a college major accordi ng to the video clip? And how did you chooseyour current major?▇Answers for referen ce:Accordi ng to the video clip, the main concern s shouldbe: first, to choosesomethi ng you reallyenjoy;second, to choosesomethi ng your schoolis well known for.Script:Hi, this is Laura Turner,andtodayI’mgoingtotalktoyouabouthowtoselectyour college major. I would like to tell you that if you selectsomethi ngthatyouloveandthatyou’repassion ate about,everyth ing’sgoingtobefineandyou’regoingtogetagreatjobwithyourdegree, but of coursethis is not complet ely true. However,whenyou’re going to college, your primary reasonfor going to college is to educate yoursel f, which means to make yoursel f a betterpersonboth intelle ctuall y, spiritu ally, mentall y, all of these things. So, wheneve r you chooseyour major, I would say yes, do choosesomethi ng that you enjoy, because reallyif you are just in it to get a degreethat will get you a high-payingjobandyou’renotreallypassion ate about this and you want to be an Enginee ring Major just becauseyouknowthat’sg oing to make you into a high earning person, that may be the wrong reasonto study it becauseyou’regoingtoget overwhe lmed over time because a degreetakes, it’sfouryearsoutofyourlifethatyou’regoingtobestudyin g this thing. There has to be somethi ng beyondmoney, and beyondthejobthat’sgoingtokeepyou interes ted. So I would suggest picking somethi ng that you love as well as, hopeful ly, it will besomethi ng that will get you a job. Also, my other point is, pick somethi ng that your schoolis well known for, somethi ng in your school, the major in your schoolthat actuall y has reallygreat profess ors to teach you. If you have a great English Departm ent, if you have a great History Departm ent, andyou’repassion ate about those things, study with profess ors who are great and they can help turn a littlebit of interes t in a subject matterinto a lifelon g love of it. So good luck with choosin g your major wisely.Part II Listenand RespondSection A Word Bankfreshma n n. infml a student in the first year at college or univers ity〖非正式〗大学一年级新生in general for the most part; commonl y, usually一般说来anticip ationn. the feeling one has when expecti ng somethi ng pleasan t to happen期望；预期discove ry n. a fact or thing that has been discove red被发现的事实、事物definit ely ad. without doubt; clearly无疑地，确实地impress ion n. [(on)] an image or effectthat is produce d in the mind by a person, event,experie nce, etc. [常与on连用] [人、事件、经历等留下的]印象；感想head off move towards; go to朝……前进，向……去related a. [(to)] connect ed in some way [常与to连用]有关系的workloa d n. the amountof work that a personor machine is expecte d to do in a particu larperiodof time人或机器在一定时期的工作量，工作负担challen ge n. (somethi ng with) the quality of demandi ng competi tive action, interes t, orthought挑战性；具有挑战性的事物amountn. [(of)] a collect ion or mass conside red as a unit in terms of its size, number, etc.[常与of连用]总数，数额，数量deadlin e n. a date or time beforewhich somethi ng must be done or complet ed截止日期；最后期限frustra tion n. the feeling of being annoyed, upset or impatie nt沮丧；失望previou s a. happeni ng or existin g beforethe one mention ed 在先的，在前的，以前的patienc e n. [U] the ability to acceptpain, trouble, anythin g that causesannoyan ce,without complai ning or losingone’sself-control忍痛的能力，忍受力，耐性diverse a. differe nt (from each other); showing variety各不相同的，各种各样的relatio nshipn. [(between, with)] a friends hip or connect ion between people[常与between或with连用]友谊；关系so to speak as one might say 可谓，可以说，简直是respons ibilit y n. [U] [常与for连用]责任（心）；责任感，可信赖性anticip ate vt. think likelyto happen, expect预期，期望mission n. the particu lar work which one believe sitisone’sdutytodo职责；使命inspiri ng a. that gives one the urge or ability to do great things激励人心的；启发灵感的careern. a job or profess ion for which one is trained and which one intends to followforpartorthewholeofone’slife职业；一生的事业Section B Task One: Focusin g on the Main Ideas1. Choosethe best answerto complet e each of the followi ng sentenc es accordi ng to the informa tion contain ed in the listeni ng passage.1)In this monolog ue the speaker mainlytalks about ________.A)stories about college lifeB)t he life of college freshme nC)c arefre e life of college student sD)differe nces between college and high school2)Accordi ng to the speaker, the freshma n experie nce will ________.A)enablestudent s to find true friends hipB)l eave a deep impress ion on every studentC)d ecidewhat a student can do in the futureD)teach student s the importa nce of respons ibilit y▇Key:1) B) 2) C)2. Read the followi ng stateme nts and decidewhether each of them is true or false based on the informa tion contain ed in the listeni ng passage. Write T for True and F for False in the space given beforeeach stateme nt.1)________ Freshma n experie nce is an unforge ttable experie nce to college student s.2)________Stude nts will feel just as comfort able in their first year at college as in their previou s years whenthey were in high schoolor back at home.3)________ Student s are able to find very good friends at college.4)________ Learnin g to be respons ible for oneself at college is very importa nt.5)________ Freshme n shouldnot be concern ed with their futurecareers.▆Key:1)T2) F3)T4)T5) FSection C Task Two: Zooming in on the DetailsListento the recordi ng again and fill in each of the blanksaccordi ng to what you have heard.1)The freshma n year at college is, general ly speakin g, a time filledwith _____________, some anxiety, and_________________________________.2)The workloa d will be ______________ and the major challen ges of college work are a large amountof___________________ and the short ______________.3)College Friends hip will be among the _____________________________ and_______________________ ofone’slife. It’salwaysexcitin g to discove r how________________________________ college relatio nships can be.4)Student s shouldremembe r that they are at college with an _____________________: they shouldn’twastetime on ___________________________.5)Going to college is not just to get a degree: it is to find out ___________________ and____________________________________.▇ Answers for referen ce:1)The freshma n year at college is, general ly speakin g, a time filledwith anticip ation,some anxiety, andwonderf ul discove ries.2)The workloa d will be heavier and the major challen ges of college work are a large amountof readingand writing and the short deadlin es.3)College friends hip will be among the most satisfy ing and long-term ofone’slife. It’salwaysexcitin g todiscove r how wonderf ully diverse college relatio nships can be.4)Student s shouldremembe r that they are at college with an anticip ated mission; they shouldn’twastetimeon meaning less things.5)Going to college is not just to get a degree; it is to find out who you are and what you are reallymadefor.Script:I am now a fourth-year student at college, but I can never forgetmy freshma n year here. In general, it is a time filledwith anticip ation, some anxiety, and wonderf ul discove ries.College is a lot differe nt from high school. Your freshma n experie nce will definit ely make an impress ion on you. So, what can you expectas you head off into the wonderf ul world of highereducati on?Thefirstthingyou’llnoticeis the workloa d. It will be heavier than you ever experie nced before. The major challen ges of college work are the large amountof reading and writing, and the short deadlin es. A related effectthat can be brought on by the workloa d is doubt, frustra tion, and possibl y lonelin ess. You’llbeaway from the comfort s and friends hips your home provide d for you over the previou s years.Duringthe freshma n year, you’llbemakinga lot of new friends. But you shouldcontinu e to be yoursel f. Selectyour friends with the same care and patienc e you have alwaysshown. Believe it or not, your college friends hips will be among the most satisfy ing and long-term of your life. It’salwaysexcitin g to discove r how wonderf ully diverse college relatio nships can be.Y ou’llalsobeonyourown—you’llbeyourownboss24 hours a day, so to speak. But, remembe r, with freedom comes respons ibilit y. You shouldalwaysremembe r that you are at college with an anticip ated mission. Don’twasteyourtimeonmeaning less things.Duringthe freshma n year, you may even start thinkin g about your future. Maybe a certain profess or is especia lly inspiri ng. Perhaps your schoolhas some great researc h going on. If some area of study attract s you, find out all you can about it. It might be the beginni ng of your lifetim e career. Going to college is not just to get a degree— it is to find out who you reallyare and what you are reallymade for.Part III Read and ExploreT ext ASection A Discove ring the Main IdeasExercis e 1. Write down the main idea of the followi ng paragra phs in the space provide d.1)Para 2: ____________________________________________________________________________________________________________________________.2)Para 3: ____________________________________________________________________________________________________________________________.3)Para 4: ____________________________________________________________________________________________________________________________.4)Para 5: ____________________________________________________________________________________________________________________________.5)Para 6: ____________________________________________________________________________________________________________________________.▆ Answers for referen ce:1)Para 2: Top student s attainacademi c excelle nce by masteri ng a few basic princip les that otherscaneasilylearn.2)Para 3: Top student s learn to be organiz ed.3)Para 4: Top student s know how to schedul e their time properl y.4)Para 5: Top student s are very serious about schooland very activein class.5)Para 6: Student s benefit from group study.Exercis e 2: Read the followi ng stateme nts and then decidewhether each of them is true or false based on the informa tion in the text. Write T for True and F for False in the space provide d beforeeach stateme nt.1)______Being brightdoes not necessa rily make one a straigh t-A student.2)______A top student knows how to balance between what is more importa nt and what is lessimporta nt.3)______One student thinksthat learnin g a new word while brushin g his teeth helps him learn thenew word best.4)______A messy student may waste a lot of time.5) ______Profess ors may concent rate more on the neatnes s of an assignm ent than on its content.6) ______Student s benefit more from group study than from individ ual study.7)______Pressur e from parents is good for student s.▆ Answers for referen ce:1)T2)T3) F The student does so in order to save time.4)T5) F The student who turns in neat work is a step closerto a high score.6)T7)F Encoura gement ratherthan pressur e from parents helps student s a lot.Exercis e 3: Summari ze the basic princip les that top student s masterand apply in their studyin g and put them down in the space provide d.Basic Princip les That Top Student s Masterand Applya.b.c.d.▆Answers for referen ce:Basic Princip les that Top Student s Masterand Applya. set priorit iesb. study anywher e or everywh erec. studyatone’spreferr ed timed. be consist entSection B In-depth StudyWorking towards academi c excelle nce constit utes one of the most importa nt parts of college life and is the goal of most college student s. Straigh t-A student s, in this respect, can be of great help by sharing their secrets in achievi ng academi c excelle nce. Read the followi ng text to find out what some of these secrets are.Secrets of Straigh t-A Student s1 A profess or of educati on who has conduct ed major studies of super-achievi ng student s reveale d that top gradesdo not alwaysgo to the brighte st student s. Accordi ng to him, other educati on experts and top student s themsel ves, it is far more importa nt for a student to know how to make the most of his or her innateabiliti es.2 The student s at the top of the c lass attainacademi c excelle nce by masteri ng a few basic princip les that otherscan easilylearn.To begin with, top student s know how to set their priorit ies right. Study time is never comprom ised for phone calls, televis ion program mes or snacks.In other words, it is alwaysplac edabove recreat ion. In additio n, top student s make a point of studyin g anywher e or everywh ere. A top student who is also a top athlete memoris es biology terms as he works out every day. Another student learnsa new word every morning while brushin g his teeth. Among all the student s intervi ewed, every one agreedthat study times are strictl y a matterof persona l prefere nce. Some thriveat night when all is silent. Otherspreferto study as soon as they come home from schoolwhen the lessons are fresh in their minds. However, all agreedthat consist ency is a main factorif one is to perform well at all times.3 A student must also learn to be organis ed. For example, a top student who is activel y involve d in his schoolband, track and field, rugby associa tion and debateteam disclos ed that he keeps his thingsintheir properplacesbecause he simplycannotaffordtime-wasting searche s. Another student immedia tely files theday’snotesincolour-coded folders so that they are availab le for reviewnearing examina tion time. Another techniq ue advocat ed by top student s is to read effecti vely. This include s speed-reading, improvi ngone’smemoryor retenti on ability, and activel y askingquestio ns that will lead to a full underst anding of the author’smessage.4 It is also importa nt for student s to know how to schedul e their time. They must know how to pace each assignm ent or project accordi ng to their daily timetab le and work ability so that they might not be overwhe lmed by the tasks at hand. Being able to set timetab les not only allowsstudent s more time to reviewand polishtheir work, it also prevent s them from procras tinati ng. Top student s believe that a secretof their success is the takingdown of good notes duringlessons and using them for revisio n. One student reveale d that she writesnotes from the text on one side of her noteboo k and those from her teacher s’lecture s on the other side. This allowsher to reviewboth aspects of each lessonat once. The student also reveale d that instead of wasting time whisper ing to friends and getting ready to rush out of the class just beforethe bell rings, she uses those few minutes to jot down a two or three-sentenc e summary of the lesson’sprincip al points. She then scans the notes to refresh her memorybeforethe nextday’sc lass.5 Another winning formula which teacher s promote lies in a student’sability to hand in neat work. Accordi ng to one profess or, the student who turns in neat work is already on the way to scoring an A. In the classro om context, it is equally importa nt for student s to speak up and ask questio ns. This is perhaps the best way for a student to c larify any doubts.Classro om partici pation also demonst ratesa student’sintelle ctualcuriosi ty. As a student concise ly puts it, ―Bettergradescome from betterunderst anding.‖6 The value of studyin g togethe r was demonst ratedin an experim ent conduct ed at one top univers ity. The study reveale d that student s who discuss ed homewor k and problem s togethe r, tried differe nt approac hes and explain ed their solutio ns to one another scoredhigherthan those who laboure d on their own. The experim ent also illumin ated the value of hypothe ticaltests conduct ed among the student s and on their own. This means that student s frame tentati ve test questio ns based on their notes and give each other or themsel ves written examina tionsthe day beforea test. Experts confirm ed that student s who devisepossibl e test questio ns often find many of the same questio ns duringthe real examina tion and thus score higher.7 Another techniq ue employe d by top student s is to do more than the assigne d homewor k. A student reveale d that if her teacher gives five problem s, she will underta ke ten. In the student’swords, ―Partoflearnin g is practis ing. The more you practis e,themoreyoulearn.‖Lastbutnotleast,al l experts and top student s agree that the most importa nt ―secret‖ of super-achieve rs lies in the crucial contrib utionby parents. From infancy, super-achieve rs were taughtthe importa nce of learnin g by their parents. The latterset high standar ds for their childre n and held them to those standar ds. They encoura ged their childre n in their studies but did not underta ke the work for them. Instead of pressur ing their childre n, these parents were alwaysloving, gentleand took pains to explain and motivat e. They impress ed the lessons of respons ibilit y on their childre n, and the childre n deliver ed.（此课文没有更新，不需要配图说明。
Three levels of understanding physical relativity Galileo's relativity, Up-to-date Galileo'
Three levels of understanding physical relativity: Galileo’s relativity, Up-to-dateGalileo’s relativity and Einstein’s relativity: A historical survey.Bernhard RothensteinPolitehnica University of Timisoara, Physics Dept., Timisoara, Romania E-mail: bernhard_rothenstein@Corina NafornitaPolitehnica University of Timisoara, Communications Dept., Timisoara, RomaniaAbstractWe present a way of teaching Einstein’s special relativity. It starts with Galileo’s relativity, the learners know from previous lectures. The lecture underlines that we can have three transformation equations for the space-time coordinates of the same event, which lead to absolute clock readings, time intervals and lengths (Galileo’s relativity), to absolute clock readings but to relative time intervals and lengths (up-to-date Galileo transformations) and to relative clock readings time intervals and lengths.1. First level of understanding physical relativity: absolute clock reading, time intervals and lengthsThe student who starts learning Einstein’s special relativity knows physics at a Newton-Galileo level, i.e. he is convinced that:A. The true laws of physics are the same in all inertial reference frames and so it is impossible to distinguish between the state of motion and the state of rest of a laboratory by experiments we perform confined in it.B. Relative motion does not desynchronize clocks once synchronized (brought to display the same time when they are instantly located at the same point in space) i.e. time and time intervals are absolute.C. Measuring the length of the same rod observers in relative uniform motion obtain the same value i.e. lengths (space distances between two events) are absolute.D. Distances measured perpendicular to the direction of relative motion have the same magnitude for all inertial observers in relative motion.E. The coordinates of the same event, when measured from two inertial reference frames in relative motion transform in accordance with the following equationsv x x t ′′=+ (1) y y ′= (2)t t ′= (3)where (,,)x y t and (),,x y t ′′′ are the space-time coordinates of the same event in theand in the reference frames respectively. The two frames are in the standard arrangement, v representing the velocity of (K XOY ))(K X O Y ′′′′()K X O Y ′′′′ relative to(K XOY ) in the positive direction of the overlapped ()OX O X ′′ axes. Equations (1), (2) and (3) lead to the addition law for the ()OX O X ′′ components of the velocity of the same particle v x x u u t ′′=+ (4)and toy u u y ′= (5)for the components. We remind that an event represents a physical occurrence that could take place at a given point in space at a given time. The coordinates of the point where the event takes place represent its space coordinates whereas its time coordinate equates the reading of the clock located where the event takes place. We use for defining an event the notation (OY O Y ′′)(),,E x y t in andin respectively.(K XOY ))(),,E x y t ′′′′(K X O Y ′′′′The art of the instructor who just starts to teach special relativity is to convince the learners that statements B, C and E hold only in the case when the involved velocities are small when we compare them with the velocity at which light propagates through empty space. However, he underlines that physicists hardly believe in statement A, which was not yet infirmed.F. The student also knows that in all the experiments performed in a given inertial laboratory (Michelson, Foucault) we measure the two way velocity of light . Doing that, we measure the time interval between the emission and the reception of a light signal that reflects itself on a mirror, located at a known distance from the source of light. Galileo describes such an experiment but with a negative result because the clocks he used where not able to measure very short time intervals.c G. There is no experimental evidence for the fact that light propagates forward at the same velocityf c at which it propagates backward , b c f c and representing the one-way velocity of light.b c H. Inertial observers in relative motion, equipped each with a co-moving light source obtain measuring the two-way velocity of light emitted by that source, the same value as a direct consequence of statement A. c2. The second level of understanding relativity: Absolute clock readings, relative time intervals and lengthsAt that new level of understanding relativity we consider that the propagation of light is isotropic (f b c c =). In order to underline the important part played by clocks (devices able to generate a periodic phenomenon characterized by a strictly constant period) we consider that at each point of the OX axis of the ()K XOY reference frame we find a clock and let (,0)i i i C x y =0(0,0C x y )== be a clock located at the origin O of the reference frame. Let also be (K XOY ))0(0,0i i C x y ′′′== a clock located at the origin a clock located at the origin (O 0,x y ′′′==)0O ′ of the ()K X O Y ′′′′ reference frameand commoving with it. All the clocks mentioned so far are identical. At whenthe origins of the two frames and implicitly the clocks and 0t t ′==0C 0C ′ are instantly located at the same point in space we synchronize the two clocks by simple comparison fixing them to display the same zero time.Let be a source of light located at (0,0L x y ==)()O 0,0 and at rest relative to. When clock reads source (K XOY )0C e t L emits a light signal in the positivedirection of the OX axis. Let be the reading of clock r t (,0)i i C x y = when the light signal arrives at its location. Ifi r e xt t c=+ (6)we say that we have synchronized the two clocks in accordance with a procedure proposed by Einstein. Under such conditions, all the clocks display the same runningtime. The moving clock arrives successively in front of different clocks. Let i C 0C ′i C ,1e t ′ be the reading of clock when it is instantly located in front of clock that reads . A fundamental assumption in Galileo’s relativity (statement B) is that thereadings of the two clocks are equal to each other i.e. 0C ′(,0i i C x )r t .r r t t ′= (7)Consider now that we attach a mirror M ′ to clock 0C ′. Source L ′ emits a light signal when clock reads . The mirror located in front of source 0C 0e t =L reflects it instantly back. At a time , source e t L emits a second light signal. When it arrives at the locationof the mirror clock reads , whereas a clock 0C ′,1e t ′(),0C x in front of which it is instantly located reads . In accordance with statement B we have ,1e t ,1,1e et t ′=. The obvious equation(),1,1v e e t c t t e =− (8)equates the distance traveled by the mirror with the distance traveled by the second light signal and leads to the following relationship between the two clock readings,1v 1e e tt c=−. (9)The reflected light signal arrives back at the location of clock when it reads . It is obvious that now 00C r t (),1,1v e r e t c t t =− (10)from where we obtain,1v 1r e t t c ⎛=+⎜⎝⎠.⎞⎟ (11)We illustrate the experiment described above using a classical space-time diagram (Figure 1).Figure 1: We present an experiment, which enables us to find out the location and the reading of a moving clock using a classical space-time diagram. We use a classical space-time diagram that enables us to represent on it the geometric locus of the successive positions occupied by the moving clock and by the light signals propagating in the positive or in the negative direction of the axis. OXInstructors use such diagrams in teaching classical kinematics in order to define the instantaneous position of a particle at a given point of the OX axis (x ) at a given time t. We use it to illustrate the geometric locus of the successive positions occupied by a moving particle, as well. Such a diagram presents two perpendicular axes on which we measure the instantaneous space coordinate (x ) of a particle (space axis) and the productXv e t 0between the velocity of light through empty space c and the time when the particle occupies the mentioned position (time axis) respectively. t The following equation()vx ct c= (12)describes the motion of the mirror and of the clock 0C ′, attached to it. Theirs successive positions on the space-time diagram are located on the straight line , which makes with the time axis of the diagram an angle 0GL C ′θ given byvtg .cθ= (13)The successive positions occupied by the light signals emitted at and respectively are located on the geometric loci GL(c ) and GL() respectively, which make an angle 0t =e t ,e c t c θ with the positive direction of the time axis given bytg 1c ccθ== (14)Light signals emitted in the negative direction of the axis appear on the space-time diagram as geometric loci that make an angle with its time axis (GL() and GL()).OX 045c θ−=−c −,r c t −We consider now that we find the mirror (),0M x somewhere on the axis when a clock attached to it reads t whereas a clock OX ′(),0C x in front of which it is instantlylocated reads t . Source emits a light signal when clock reads . It arrives at the location of clock when it reads t . The mirror reflects it instantly back and itarrives at the location of clock when it reads . From the obvious equations L 00C e t (,0)C x 0C r t()e x c t t =− (15)and()r x c t t =− (16) we obtain(2r e c)x t t =− (17)(1.2r e t t t =−) (18) The important result is that using a single clock an observer located in front of the source could detect the position of the mirror 0C L (),0M x at a time , simply measuring the times and when the source emitted the light signal and when it returned back toit. We illustrate the experiment in Figure 2. t e t r tXFigure 2: We present a classical space-time diagram used in order to illustrate how twoinertial observers in relative motion could determine the reading and the location of a clock located somewhere on the overlapped OX(O’X’) axes.We find at the origin of the ()K X O Y ′′′′ reference frame a source of light . Theclassical space-time diagram we show in Figure 2 tells us that in order to illuminate the mirror at the same position on the OX axis, source L ′L ′ should emit the light signal at atime receiving it back at a time ,1,1e e t t ′=,1,1r r t t ′=. In accordance with statement A we should have (,1,12r e c)x t t ′′′=− (19)(,1,112e r t t t )′′′=+ (20)The results obtained performing the experiment illustrated in Figure 1 enable us to consider that (equations (9) and (11)),1,11e e e tt t c′==− (21) and that,1,1.v 1e r r tt t c′==+ (22)v tGL(−),r c tExpressing the right hand side of (17) and (18) as a function of times measured in and taking into account (19) and (20) we obtain successively (K X O Y ′′′′) ()()(),1,1,1,1vv 222r e r e r e c c x t t t t t t x t ′′′′′=−=−++=+′ (23)()()(),1,1,1,1211v .222r e r e r e t t t t t t t t c c vx ′′′′′=+=++−=+′ (24)We call equations (23) and (24) up-to-date Galileo transformations and they lead to the following addition law of velocities orientated in the positive direction of the overlapped axes()OX O X ′′22v v v v 1x x x u x x t u t t u c c′′′++===′′++ (25)in which we recognize Einstein’s addition law of the corresponding components. If then (25) leads to x u c ′=x u c = as well in accordance with Einstein’s postulate: Measuring the velocity at which light propagates in empty space, observers from different inertial reference frames obtain for it the same value c . For the ()OY O Y ′′component of the velocity we obtain22.v v 1yy xu y y u t t x u c c ′′===′′′++ (26)As we see, there are some problems with (25) and (26) because they do not fulfill the fundamental condition imposed by Einstein= (27)in the case when in both reference frame observers measure the velocity of a light signal.3. What is wrong with the up-to-date Galileo transformations? Third level of understanding relativity: relative clock readings, time intervals and lengthsWe concentrate on equation (24). For 0x ′= it leads to the result0t t ′== (28)i.e. the readings of clocks and 0C ′(v ,0C x t y )== when they are instantly located at the same point in space are equal to each other, a hypothesis with which we started the derivation of the up-to-date Galileo transformations. We say that two events are simultaneous in a given reference frame when they take place there at the same time. Asan example, events and 111(,,)E x y t ′′′′222(,,)E x y t ′′′′ are simultaneous in the reference frame and take place at different two points in space. The up-to-date Galileotransformations lead to the conclusion that the two events are no longer simultaneous ifwe detect them from the reference frame. Event ()K X O Y ′′′′(K XOY )1E ′ and detected from have the following time coordinates2E ′(K XOY )12vt t x c 1′′=+(29)22v.t t x c2′′=+ (30) As a consequence, the time separation between the two events is in ()K XOY(21212vt t t x x c )′′∆=−=− (31) being proportional with the space separation between the two events in . That is a paradoxical situation because absolute time readings and relative simultaneity are irreconcilable physical conditions.()K X O Y ′′′′In order to remove the paradox we look for a correct relationship between the readings of two clocks in relative motion when they are instantly located at the same point in space, in our case clocks and (,)C x y (0,C x y d )′′′==. We consider the synchronization ofclocks and C in the 0(0,0)C ′(0,)d ′()K X O Y ′′′′) reference frame (Figure 3a) and in the reference frame (Figure 3b).(K XOYFigure 3a: Synchronization of two clocks at rest in the ()K X O Y ′′′′ reference frame.(0,C ′ct ′00O ,,C C ′′ X, X ′L ′Figure 3b: Synchronization of the two clocks at rest in ()K X O Y ′′′′ as detected from thereference frame.()K XOYWhen clock reads , a source of light 0(0,0)C ′0t ′=()0,0L ′ located at O and at rest in emits a light signal in the positive direction of the O Y ′(K X O Y ′′′′)′′ axis. Arriving at thelocation of clock C , stopped and reading(0,)d ′dc, the light signal starts it. After that procedure, clocks C and C display the same running time and we say that we synchronized them in accordance with a synchronization procedure proposed by Einstein.′d ′)d (0,)When detected from the reference frame, clock C (K XOY (0,)′ is instantly located infront of clock synchronized with clock in accordance with the synchronization procedure proposed by Einstein. When clock C x y reads , clock has advanced with in the positive direction of the axis whereas the light signal, which performed the synchronization, traveled a distance ct . Because of the invariance of distances measured perpendicular to the direction of relative motion, Pythagoras’ theorem leads to (,)C x y 0(0,0)C (,)t (0,)C d ′v t OX 222222v c t t c t ′=+ (32)from wheret ′=()0,C d ct ′0O,C LX, X ′O ,C ′′We underline that (33) holds only in the case when one of the involved clocks has a space coordinate. In order to lead to the result imposed by (31) equation (24) should read0x ′=t =In order to lead to (25) equation (23) should readx ′′=(35)With (2) and (34) equation (26) takes the correct shape21y x y u t c==+ (36)We have now all the elements for deriving all the relativistic effects, encountered in relativistic kinematics.4. ConclusionsAs a moral of our historical survey we can consider that some times, a physicist finds himself in a similar situation to that of a tailor who has to fix the coat, which he has tailored (the theory) in such a way that it matches the client’s body (mother nature). Commonly speaking, he cuts there and ads elsewhere. Rigorously, he looks for a tailoring method which enables him to consider all the peculiarities of the body and which may ensure the success from the first “fitting”. Good experimental results and experimentally proved postulates ensure the success from the first fitting.Telling the learners that we have used in our derivations the “police radar” and the “radar detection procedure” we could make them more receptive.。
射频-lecture2
CMOS RF IC Design (Radio Frequency Integrated Circuit) 2005-6Institute of Microelectronics1Contents:z Introductionz Transmission Line Theoryz Smith Chartz Impedance Matchingz Inductorz Varactorz Active Devicez System requirementz LNA designz Mixer designz VCO designz PA design2005-6Institute of MicroelectronicsLecture 2: Smith Chart & impedancetransformation2005-6Institute of Microelectronics3No Kirchhoff’s voltage and currentlaws in RF circuit2005-6Institute of MicroelectronicsThe Smith Chartz The Smith Chart was developed in 1939 by Philip Smith at the Bell Telephone Laboratories z The Smith chart is a plot of the reflection coefficient, Γ, in the complex planez It can be used to convert reflection coefficients (Γ) to normalized impedance (z=Z/Z0) andadmittances (y=Y/Y0), and vice versa.z Nearly all computer aided design programs utilize the Smith Chart for the analyses of high frequency circuits.2005-6Institute of Microelectronics2005-6Institute of Microelectronicsz Traveling wave hits the boundary z H-field flips with respect to the E-field2005-6Institute of Microelectronicsz Traveling wave hits the boundaryVoltage at load: Vi+Vr, Current at load: Ii-Ir Load impedance:ZL = (Vi+Vr)/(Ii-Ir)2005-6Institute of Microelectronics Characteristic impedance Z0:Load impedance:The Smith ChartDefine reflection coefficient:Γ=V r/V i No reflection: Г=0Z0((1+V r/V i)/(1-V r/V i))=Z L=(Z L-Z0)/(Z L+Z0)No reflection: Z L=Z0ΓInfinite load impedance: Z L=∞, Г=1Zero load impedance: Z L=0, Г=-12005-6Institute of Microelectronics2005-6Institute of Microelectronics The Smith Chart:)()()()(000z j z j z j z j e e Z V z I e eV d V ββββ+−++−+Γ−=Γ+=2005-6Institute of MicroelectronicsThe Smith Chart)](1[)()1()(0200d Z d Ae e Z V d I dj d j Γ−=Γ−=−++ββdj dj dj dj ed eV d A d d A ee V d V ββββ2020)()()](1)[()1()(−++−++Γ=Γ=Γ+=Γ+=)1()1()()()(20200dj dj dj d j in e e V e e V Z d I d V d Z ββββ−+−+Γ−Γ+==:)(1)(1)(0d d Z d Z in Γ−Γ+=2005-6Institute of MicroelectronicsSee page 72 –a clear smith chart2005-6Institute of MicroelectronicszNo reflection: Z L =Z 0Infinite load impedance: Z L =∞, Г=1Zero load impedance: Z L =0,Г=-12005-6Institute of Microelectronics2005-6Institute of MicroelectronicsConformal Mapping -Γand zjxr Z Z z wheree z z L L j L L +==Γ=+−=Γ0/||11θjxr jx r j jv u ir +++−=Γ+Γ=+=Γ)1()1(2005-6Institute of MicroelectronicsThe r circles2222222222222222221111111111211112)1(1⎥⎥⎦⎤⎢⎢⎣⎡+=Γ+⎥⎥⎦⎤⎢⎢⎣⎡+−Γ⎥⎥⎦⎤⎢⎢⎣⎡+++−=Γ+⎥⎥⎦⎤⎢⎢⎣⎡+−Γ+=Γ+Γ++Γ−⎥⎥⎦⎤⎢⎢⎣⎡++⎥⎥⎦⎤⎢⎢⎣⎡+−+Γ−Γ−=Γ+Γ+Γ−Γ+Γ−Γ−Γ−=rr r r r r r r r r rr rr r r r r r r r r r i r i r i r r i r i r r ir irCircles with radiusequals to 1/(1+r), and centre coordinates (r/(1+r), 0)The r circles2005-6Institute of MicroelectronicsThe x circle[][][]222222222221)1(1)1()1(2121)1(2⎥⎥⎦⎤⎢⎢⎣⎡=−Γ+−Γ=+Γ−Γ+−ΓΓ=Γ+−ΓΓ+Γ−Γ=x x xx x xx i r i i r iir ir iCircles with radiusequals to 1/x, and centre coordinates (1, 1/x)The x circlesThe r/x circlesInductance increaseCapacitance decrease 2005-6Institute of Microelectronics2005-6Institute of MicroelectronicsImpedance coordinates2005-6Institute of MicroelectronicsAdmittance transformationAdmittance Coordinatesz in=1+j1↔y in=1/2-j1/2, see page 80 2005-6Institute of Microelectronics2005-6Institute of Microelectronics Admittance Coordinates Rotate whole smith chart by 180。
电气专业英语section 2-2 中英
在随后的方程中，读者可以使用变量A、B和C两个可能
的值0和1来验证每个表达式的正确性。
Use A = 0, B = 0, C = 0; A = l, B = 0, C = 0; and so on, in each expression. The associative rules state how variables may be grouped.
布尔和其他研究者致力于发展一种证明逻辑上或数学中
命题的真假问题的系统方法，而我们只关心数字设备输出 的正确性。
Section 2 Boolean Algebra for Digital Systems
True and false can be equated with one and zero, high and low, or on and off. These are the only two states of electrical voltage from a digital element.
associative
[ə’səuʃjətiv]联合的，结合的 commutative [kə’mju:tətiv] 交换的，代替的 distributive [dis’tribjutiv]分发的，分配的
布尔代数与任何代数一样，具有结合律、交换律和分配
律。
To show the features of the algebra we use the variables A, B, C, and so on.
可以制造各种各样的逻辑门并将它们相互连接起来，完
成计算机和决策过程所需要的各种基本功能。
In developing digital systems the easiest procedure is to put together conceptually the gates and connections to perform the assigned task in the most direct way.
Lecture 2
e(k) is white noise and q=[a1, …ana, b0,….bnb, c1,….cnc, d1, ….dnd]T is the parameter vector.
Input System + Error e(t) System Output y(t)
Model Model Output ym(t)
How System Identification is applied
• System identification can be decomposed into following problems:
How System Identification is Applied?
Experiment Design A priori Knowledge Model Structure Input/Output Data Parameter Estimation N
Validation Y Final Model
•
Examples of Mathematical Models:
– – – – –
Algebraic equations Ordinary differential equations Partial differential equations Finite-difference equations Transfer functions, impulse responses and state variable models etc.
电气工程及其自动化专业英语第一章课文翻译
电气工程及其自动化专业英语第一章课文翻译第一章第一篇sectiongTwo 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 CurrentThe 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部分组成的，并且每个原子是由电子，质子和中子组成的。
《柳树醒了》(一)孙桂芳(修改稿)
《柳树醒了》主体备课人说课稿龙源学校孙桂芳一、说课标(一)识字与写字识字写字是阅读和写作的基础，是第一学段的教学重点。
引导孩子喜欢学习汉字，有主动识字的愿望。
关注学生日常识字的兴趣，激发学生识字写字的积极性，运用多种识字教学方法和形象直观的教学手段，创设丰富多彩的教学情境，提高识字教学效率。
写字教学要掌握汉字的基本笔画和常用的偏旁部首，能按笔顺规则用硬笔写字，注意间架结构。
重视对学生写字姿势的指导，引导学生掌握基本的书写技能，养成良好的书写习惯。
对识字与写字的要求应有所不同，要贯彻多认少写的识字教学原则，讲究教学方法，以减轻学生负担。
(二)阅读学习用普通话正确、流利、有感情地朗读课文和默读课文。
在阅读中引导学生结合上下文和生活实际了解课文中词句的意思，在阅读中积累词语。
阅读教学应注重培养学生具有感受、理解、欣赏和评价的能力。
阅读文章能够展开想象，获得初步的情感体验，感受语言的优美。
向往美好的情境，关心自然和生命，对感兴趣的人物和事件有自己的感受和想法，并乐于与人交流。
培养广泛的阅读兴趣，扩大阅读面，增加阅读量。
(三)写话对写话有兴趣，写自己想说的话。
在写话中乐于运用阅读和生活中学到的词语。
学习使用逗号、句号、问号、感叹号。
(四)口语交际学讲普通话，逐步养成讲普通话的习惯。
能复述大意和自己感兴趣的情节。
能较完整地讲述小故事，能简要讲述自己感兴趣的见闻。
有表达的自信心。
积极参加讨论，敢于发表自己的意见。
(五)综合性学习对周围事物有好奇心，能就感兴趣的内容提出问题，观察大自然，用口头或图文等方式表达自己的观察所得。
热心参加校园、社区活动。
结合活动，用口头或图文等方式表达自己的见闻和想法。
基于对以上课程标准的理解，我对一年级下册《柳树醒了》一课的个人主体备课如下：二、说教材《柳树醒了》是人教版小学语文一年级下册第一单元中的第一篇课文，该单元以“多彩的春天”为主题展开，包括《识字》1、《柳树醒了》、《春雨的色彩》、《邓小平爷爷植树》、《古诗两首》5课。
机电专业英语.Lesson 2
High-carbon
steel: Tools made from highcarbon steels, 0.80 to 1.3%, are used for small-quantity production of wood parts or machining soft materials such as freecutting steels and brass. It is important that the operational temperatures be kept below 400℉ because the material loses its hardness above this temperature. For this reason coolants should be used freely.
High-speed
steels may be made by the powder metallurgy process. This process uses no binder. In that respect it differs from the carbides. The materials are melted, atomized into powdered particles, compacted, sintered, and heat treated to desired hardness. These HSS have better tool properties than those of conventional HSS materials.
It should be noted that some hardened materials will retain their hardness after being subjected to high temperatures during the cutting operation and cooled to room temperature. Such tool materials are ceramics, carbides, cast materials, and highspeed steel(HSS) up to 1000℉. Carbon steel loses its hardness almost immediately upon being cooled from elevated to room temperature.
电子信息与通信工程专业英语课文翻译3.2
3.2 数字信号处理1 简介数字信号处理是21世纪用于科学和工程领域最强大的技术之一，它使一个广阔的领域发生了革命性的改变：通信，医学影像，雷达或声纳，高保真音乐复制，石油勘测，以上只是列举几个。
每个领域都有它自身独特的算法（algorithm），数学运算（mathematic），专用工艺（specialized technique）。
数字信号处理在计算机科学方面有别于其他领域，因为他采用一种特殊的数据类型：信号。
现代社会中，我们的身边充满各种类型的信号。
有些信号是天然形成的，但大多数是人为制造的。
有些信号是必要的（语音），有些是宜人的（音乐），而有些信号在某个特定的场合是不需要或不必要的。
在大多数情况下，这些信号来源于人对真实世界的感觉，比如地震的震动，视觉图像，声音波形等。
数字信号处理是一种数学工具，是一种用来处理那些将上述信号转换成数字形式后的信号的算法和技术。
这包括一系列目的，如：视觉图像的优化处理，语音识别和生成，数据压缩存储和传输等。
在工程范围内，信号是信息的载体，既有益又有害。
信号处理中最简单的形式是从一连串相互矛盾的信息中提取和增强有用信息。
信息的有用和无用往往只是主管和客观的区别。
因此信号处理往往依赖于应用程序。
傅里叶分析和滤波器设计是信号处理时常用的方法。
他们的原则简单描述如下。
2 傅里叶分析函数的傅里叶表示，即将函数表示成正弦和余弦信号的叠加，这种方法已经广泛用于微分方程的解析法和数值法求解过程以及通信信号的分析和处理。
傅里叶变换的效用在于它能够在时域范围内分析它的频率内容。
变换的第一步是将时域上的函数转换为时域表示。
（The transform works by first translating a function in the time domain into a function in the frequency domain）。
然后就可以分析信号的频率内容了。
因为变换函数的傅里叶系数代表各个正弦和余弦函数在各自对应频率区间的分配。
最新自动化专业英语》-作者：王军-孙舒-重庆大学出版社-教材部分课文翻译
Unit 1现在工业电子系统使用的是被称为晶体管的装置。
每一类型的晶体管有区别于其他晶体管的不同特点和操作条件。
在讨论的第一部分，我们来关注双极性晶体管。
从结构上看，这个晶体管被描述为双极性的，是因为它有两个不同的电流载体极性。
空穴是阳极电流载体，而电子是阴极电流载体。
这两个不同性质的半导体晶体通过一个公共部分连接在一起。
这个装置的结构类似于两个二极管背靠背连接，其中一个晶体充当另外两个晶体的公共部分。
中间的材料通常被做得比外面的两片都要薄。
图1.1表示的是此晶体管的结构，原件名称，和不同双极性晶体管的语义符号。
一个双极性晶体管主要被用做放大器来限制流经它的电流。
电流从电源流入发射极，经过基极，再流出集电极。
集电极的电流量通常被定义为晶体管的输出量。
集电极电流由基极电流中的一小部分控制。
这个关系被描述为电流增量或β。
数学表达式如下：电流增量=集电极电流÷基极电流公式中希腊字母Δ表示变化的值。
它用来表示当有交流输入时晶体管的响应。
这种类型的状态被称为动态特性。
公式中的Δ的省略部分表示直流或静态工作条件。
所有从发射极进入晶体管的电流被定义为发射极电流。
集电极电流Ic通常小于Ie。
Ie和Ic的不同归因于基极电流。
从数学角度看，Ib=Ie－Ic例1-1；确定一个双极性晶体管的Ie为11mA,Ic为10.95mA;解；。
（省略）图1.2表示的是一个简单NPN型硅晶体管的电路连接图。
这个电路是以正向偏置的发射极和反向偏置的集电极为基础的。
我们把直流电源的负极连接到发射极，把正极通过Rb连接到基极来达到发射极的正向偏置。
我们把电源正极通过电阻Rl连接到集电极，形成集电极的反向偏置。
我们通过发射极的正向电压来控制流经Rl的集电极电流。
在一个简单的PN结中，正向偏置导致其导通，反向偏置导致其不导通。
在晶体管中，这种规律不能直接应用因为两个结都包含在里面。
例如，当发射极正向偏置时，会导致大量的Ie流入基极。
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54
55
Volume-mass relations
Volumetric properties: porosity, void ratio, degree of saturation Gravimetric properties: water content, soil density
Porosity, n, is the ratio of the volume of voids, VV, to the total volume, V
Young-Laplace方程
交界面——非饱和土
Capillary in soil
The capillary phenomenon is illustrated by the rise of a water surface in a capillary tube The weight of the water column is transferred to the tube through the contractile skin
What’s that in saturated soils? The pressure difference Du=(ua-uw), is referred to as matric suction
Water pressure, uw = ua - uw Air pressure, ua
44
Development of an unsaturated soil by the withdrawal of the air–water interface at different stages of matric suction
45
Water in soil
重力水
自由水
毛细水
在重力作用下可在土中自由 流动 • • 动
献，因而对强度也没有影响
所以孔隙水压力对变形、强度没有直接影响，故称为中性 应力 So we have the concept of effective stress, s-uw
38
Contractile skin
It can withstand tensile stresses so it exerts soil stresses throughout the soil mass. Shear strength or ? Required to consider four-phase when understanding stress state analysis
Capillary tubes showing the airwater interfaces at different radii of curvature 25
水头 h (Water Head, unit: m)
Water head profile (under static hydraulic equilibrium)
毛细现象——Young-Laplace方程
毛细现象——Young-Laplace方程 （自学）
1806年，Young-Laplace利用势能理论推导
了基质吸力与交界面几何形状关系的双 曲率模型公式 取任意气-水交界面上的一点O为研究对 象，假设其达到了力学平衡
积分
毛细现象——Young-Laplace方程
T s,w
14
Surface tension at soil-air-water interface
表面张力
交界面——两个水滴之间的平衡
阀门打开会出现什么现象？
交界面——两个水滴之间的平衡
小水滴曲率半径R1小于大水滴的曲率半径R2 ，其内的水压
力大于大水滴。因此阀门打开时，大水滴变得更大，小水 滴变lso be written as a percentage of total volume: Soil particle Contractile skin Water porosity
The volume of the contractile skin can be assumed to be negligible. The porosity with respect to the water phase, nw, is equivalent to the volumetric water content, qw.
毛细现象——毛细上升高度
表面张力作用使得毛细管内水上升，上升高度与孔径大小有关
容器中交界面平直，基质吸力趋近于0：
毛细管内，基质吸力为：
从而有：
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Capillary height
30
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Capillary in soil
Simple cylindrical model
The radius or opening of the tube is a significant factor controlling the capillary rise.
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土壤水
强结合水 土粒表面结合水 土中水 弱结合水 土孔隙中的水 重力水或自由水 非结合水 液态水 毛细水
固态水(冰)
气态水(水蒸气)
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矿物中的结合水
Matric suction
At negative pressures, the water is under tension
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41
42
Think over the capillary phenomenon
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Unsaturated soils
Due to the presence of Contractile skin, ua is not equal to uw if change ua or uw What’s happen?
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结合水
双电层决定了土粒表面结合水膜的厚度
结合水膜中的扩散层 （位于弱结合水区域）
有重要影响
土的性质
扩散层厚度 土的塑性 增加 增加 减小 降低
胀缩性
强度
增加
降低
降低
增加
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双电层厚度
离子浓度增加
Ca2+ VS Na+
随离子浓度增加，双电层厚度线性递减
应用：为什么用生石灰处理膨胀土？
What will happen?
ua = uw ?
Air pressure, ua
Air
T s,w
Water pressure, uw
Merc 12
Pressure difference
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Matric suction (基质吸力)
Due to the presence of contractile skin, the pore-water pressure is different with the pore-air pressure in unsaturated soils
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表面张力 (surface tension, Ts)
定义：展开或收拢物质相交界面上单位面积时所需的能量 单位：J/m2，N/m
Contractile skin
Surface tension Ts
Unbalanced force in the contractile skin
Ts: Surface tension The tensile force per unit length along the contractile skin (N/m)
毛细上升高度
Guo et al. 2013, Global geology
毛细上升高度
Pore-water and pore-air phase in unsaturated soils
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Pore-water pressure in saturated soils
水压力的作用
● 一个颗粒处于孔隙水包围之中，当孔隙水压力发生变化 时，颗粒是否会发生移动？ ● 当土体受到剪应力时，水压力对土体抗剪有没有作用？
颗粒之间的接触力发生改变是否会导致土体颗粒 移动？
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Pore-water pressure in saturated soils
它在各个方向相等，只能使土颗粒本身受到等向压力，不会
使土颗粒移动并导致孔隙体积发生变化。由于颗粒本身压 缩模量很大，故土粒本身压缩变形极小 水不能承受剪应力，对土颗粒间摩擦、土粒的破碎没有贡
4 phases model of unsaturated soils
Capillary in unsaturated soils
Suction and humidity
Assignments
2
State of unsaturated soils
3
Pore-water and pore-air phase in unsaturated soils
2Ts (ua u w ) r
The surface tension associated with the contractile skin results in a reaction force on the walls of the capillary tube.
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4 phases in unsaturated soils
毛细水
毛 细 管
毛细现象
空气
l 固体
T
hc
水 ua-uw = 湿润角 T = 界面张力 d = 毛管直径 ua-uw = 压力差
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d=2r
Contractile skin
Contractile skin presents at the interface between pore-water and pore-air