NCE-3-L48-Text
国际音标发音规则综合版
英语音标发音表英语国际音标共48个音素,其中元音音素20个,辅音音素28个。
对于初学者来说,若采用集中教学,要学会48个音素的发音并区别开。
确实不易。
笔者对音标的教学采用了相对集中的方法,即从字母名称教学过渡到部分音标教学。
26个字母发音表元音字母和辅音字母分类表语音知识:1) 字母:语言的书写形式。
元音字母只有a,e,i(y),o,u2) 音素:音的最小的单位。
英语中有48音素。
即20个元音音素和28个辅音音素.3) 元音:发音响亮,是乐音;口腔中气流不收阻碍;是构成音节的主要音。
英语中有20元音。
4) 辅音:发音不响亮,是噪音;口腔中气流受到阻碍;不是构成音节的主要音。
英语中有28辅音。
5) 音节:由元音和辅音构成的发音单位。
ap'ple,stu'dent,tea'cher,un'der'stand。
6) 开音节:a) 辅音+元音+辅音+e name bike home due;b) 辅音+元音he,go,hi。
7) 闭音节:a) 辅音+元音+辅音bad,bed,sit,hot,cup;b)元音+辅音it。
8) 重读音节:单词中发音特别响亮的音节。
读音规则1) 重读音节(见元音和辅音的例句)。
2) 非重读音节[ ] banana,student,today,after,[i] orange,secret,evening,very,Monday。
特殊读音1)音的连读:前面的词以元辅音结尾,后面的单词以元音开头,这样结尾的辅音要和开头的元音连读。
not at all,half an hour,I love you and all、after all。
2)失去爆破:辅音爆破音或摩擦音后面跟的是爆破音、破擦音和摩擦等,前面的辅音要失去爆破。
good girl,good student,good job,expression,school,extreme。
3)音的同化:两个特殊的音碰到一起,会发出变异成特殊的音。
新概念英语第四册课后习题答案
新概念英语第四册课后习题答案Unit 1 CABDD BDAAC AB Unit 2 BCBDC ACAAD BC Unit 3 CABDA CDABA CD Unit 4 ACCAB BCDAA BD Unit 5 CABAB DACBB DD Unit 6 CACCC AAADB AA Unit 7 DCABA BACDA AC Unit 8 BDABD BAABC BC Unit 9 CDBAA CABAC AD Unit 10 CAABD CBBDC AA Unit 11 AABDD DADDB DD Unit 12 CABAC CDACA AB Unit 13 ACDAC BDABC AD Unit 14 DBDCC ACCBD BD Unit 15 CADCD DBACA CA Unit 16 ABCCA DDBAB AC Unit 17 BBADA BBDCD CA Unit 18 BABCD CDCCC BA Unit 19 BBCAD AABDD BC Unit 20 BCADC CCBDB CA Unit 21 BDBBA ADDAB CA Unit 22 CDACB ADBCD AB Unit 23 CADCC DCABC AC Unit 24 AACCB CADDA CD Unit 25 DBADD CACDB CA Unit 26 CBCBA CDDAB AC Unit 27 BCDCC ACCDD DA Unit 28 ADCDA BCADA BD Unit 29 CCADD CCADA BC Unit 30 CABDD BCCAC DC Unit 31 AABAD BADDC BD Unit 32 BDCBA DBDCA BC Unit 33 BDBAD BCCDC BA Unit 34 DCACB DACDB CA Unit 35 CBCAC ABBDC CD Unit 36 ACBCC ACCDB AC Unit 37 CABAC DBCDC BD Unit 38 CAABB ACBDD AB Unit 39 BCADA BDDBD BC Unit 40 DCDAC ADDDA DB Unit 41 ACACD CBBBD BC Unit 42 BCCBD BDADC AC Unit 43 DBABC CDDAC BB Unit 44 AAAAB BBBDC BA Unit 45 CADAC CACDC DC Unit 46 BBDBD ABCDA BD Unit 47 CAADB CACDB BC Unit 48 CCBCC CCDBA AB新概念4 笔记/nce/24278_2.shtmlUnit 1 Finding fossil man一、重点单词解释1、recount:v.叙述注意读音,重音在后。
Crouzet Syrelec控制继电器系列说明书
CONTROL RELAYSCrouzet offers several variations of Syrelec control relays.Five models for liquid level controls, 3 phase 230V, 380V, 440V and 480V for phase loss or reversal protection, current and voltage detection and control, motion detection, and alternating relays are also available.If a standard control requires modification or a special product is needed to meet your exact needs, please call us or the Crouzet Sales Representative nearest you.Crouzet has controls to meet your CE, UL, and CSA requirements.SERIES FUNCTIONFEATURES SERIES F U N C T I O N FEATURES NNR SeriesLiquid LevelControlPC Board liquid levelcontrol.Pumpup/Pump down.4.7 to47K ohm sensitivity.SPDT 10A output relay3.62˝ x 2.16˝Liquid LevelControlNR SeriesLLC PumpDownNRU SeriesLLC Pump UpPlug-in or Din-Railmount.4.7 to 100Kohm sensitivity.1.89˝H x 1.89˝W x3.9˝LLiquid LevelControl PumpDownLiquid LevelControl PumpUpEN SeriesEND SeriesLiquid LevelControlLiquid LevelControlDin-Rail/surface mount.Pump up/Pump down.5K to 100K ohm sensi-tivity.80mmH x22.5mmW x 100mmLIR.T SeriesCurrentControl RelayMonitorsCurrent withRelay OutputPlug-in or Din-Railmount.Adjustableinhibit time for start up.LED Relay output indi-cator.3mAmp to7Amps-AC, 5mA to10Amps DC.1.89˝H x1.89˝W x 3.9˝LEIL EIH EITSeriesCurrentControl RelayMonitorsCurrent withRelay OutputDin-Rail/surfacemount.Adjustable timeinhibits.2mAmp to10Amps AC/DC.forEIL/EIH .01 to100Amps for EITw/transformer.80mmHx 22.5mmW x 100mmLUR SeriesVoltageControl RelayMonitorsVoltage withRelay OutputPlug-in or Din-Railmount .1 to 400 VoltsAC/DC.With latchingfunction selectable.LED output indication.1.89˝H x 1.89˝W x3.9˝LCTD/CTHSeriesT emperatureControllersP, PI, PIDOn/OffAuto TuningHeat/CoolSingle and dual displaymodels.Thermocoupleand RTD inputs.Auto-tuning for PID mod.Soft start function.WRL SeriesPhaseMonitorPhase ControlRelayMonitors:- PhaseSequence- Loss of Phase- Under VoltagePlug-in or Din-Railmount.3 x 230 VAC, 3x 380 VAC, 3 x 480VAC, 1.89˝H x 1.89˝Wx 3.9˝LHDU SeriesVoltageControl RelayMonitorsVoltage.With RelayOutput.With LCDDisplay..2 to 600 Volt AC/DC v o l t-age monitoring ra n g e.O v er and under v o l t a g ef u n c t i o n s.With LCD dis-p l a y.S h o ws actual ands e t p o i n t s.Din-Rail mount.81mmH x 36mmW x81m m LFW SeriesPhaseMonitorMonitors:- Phase Loss- PhaseReversal- UndervoltageDin-Rail or surface mount.3 x 230 VAC, 3 x 380VAC, 3 x 480 VAC, 3 x600 VAC.45mm widee n c l o s u r e.A d j u s t a b le timei n h i b i t.LED power on andr e l a y status.79mmH x45mmW x 100mmLEUL,EUHSeriesVoltageControl RelayMonitorsVoltage withRelay OutputD i n-R a i l/s u r f ace mount.A d j u s t a b le time inhibit..2 to 600 Volts AC/D C.S e l e c t a b le latching fe a-t u r e.80mmH x22.5mmW x 100mmLJR SeriesAlternatingRelayDuplexAlternatingRelayPlug-in style.Designedfor dual pump system.Selector switch ver-sions available.1.89˝Hx 1.89˝W x 3.9˝LMCI SeriesCurrentControl RelayMonitorsCurrent.WithRelay Output.With Built-inTr ansformer1 to 20Amp AC/DC cur-rent monitoring ra n g e.Built-in tra n s f o r m e r.R e l a youtput-SPDT Over andunder current functions.81mmH x 17.5mmW x83m m LF3I SeriesMotorProtectionRelayMotorProtection forPhase LossPhaseUnbalanceCurrent Surge8 to 630Amp currentra n g e.LED diagnostics.A d j u s t a b le trip timers.Phase loss test s w i t c h.Front panel reset.79m m Hx 45mmW x 95mmLFWIT SeriesMotorProtectionRelayMotor Protectionfor Phase LossPhase UnbalancePhase Rev e r s a lCurrent SurgeO v e r h e a t i n g7 to 630Amp currentrange.LED diagnos-tics.Adjustable triptimers Phase loss testswitch.Front panelreset.80mmH x78mmW x 99mmLHDI SeriesCurrentControl RelayMonitorsCurrent.WithRelay Output.With LCDDisplay.2mA to 10Amp;AC/D Ccurrent monitoring r a n g e.O v er and under currentf u n c t i o n s.With LCD dis-p l a y.S h o ws actualand setpoints.D i n-R a i lm o u n t.81mmH x36mmW x 66mmL83311CONTROLS&SENSORS Toll Free 1-800-526-5376Fax 201-337-1862201-337-1000Control Relays845Toll Free 1-800-526-5376Fax 201-337-1862201-337-1000Protective Relays & Alternating RelaysAdjustableProduct Number Product Number Operating Voltage UndervoltagePlug-inCase Socket Surface-Mount 50/60 Hz Drop-out Range(8 pin octal socket)Case*208/240V 180-230VPMP24070169-D PMD240480V 360-460V PMP480**70175PMD480PHASE MONITOR RELAYSProvides microprocessor-based protection for 3 phase systems against phase loss, phase rever-sal, phase unbalance, and under voltage.These devices are designed to be compatible with most Wye or Delta systems.In Wye systems, a connection to a neutral is not required.Phase Monitoring Relays protect against unbalanced voltages or single phasing regardless of any regenerative voltages.The relay is energized when the phase sequence and all voltages are correct.Any one of four fault conditions will de-energize the relay.Re-energization is automatic upon correction of the fault condition.An LED indicates normal and tripped conditions.The per-cent phase unbalance is adjustable from 2-10%, and the undervoltage drop-out can be set at 75-95% of operating voltage.The adjustable time delay dropout on undervoltage (0.1-20 sec-onds) eliminates nuisance tripping caused by momentary voltage fluctuations.Output :10A SPDT (PMP) or DPDT (PMD) @ 240VAC/30VDC.Dimensions :PMP-1.7”x 2.4”x 3.5”.PMD-1.8”x 2.75”x 4.4”.PMP Plug-in PMD Surface-Mount File LR45565File LR45565File E109461Provides protection to equipment where an over or under voltage condition is potentially damaging.They monitor either AC single phase (50-400hz) or DC (independent of polarity) voltages.No supply (input) voltage is required.The pick-up voltage setting is user-adjustable from 85-115% of the nominal voltage rating.The drop-out voltage setting is fixed at 3% below the pick-up voltage setting.The relay energizes when the monitored voltage is above the pick-up setting.The relay de-energizes when the monitored voltage is below the drop-out setting.The time delay on drop-out is fixed at 50ms.Output :10A DPDT @ 240VAC/30VDC.Dimensions :1.7”x 2.4”x 2.9”.ALTERNATING R ELAYSUsed in special applications where the optimization of load usage is required by equalizing the run time of two loads.They are also used where additional capacity is required in case of excess load requirements.This alternating action is initiated by a control switch, such as a float switch, manual switch, timing relay, pressure switch, or other isolated contact.Each time the initiating switch is opened, the output relay contacts will change state, thus alternating the two loads.Tw o LED indicators show the status of the output relay.As listed, these units come with a three position selector switch.This allows the unit to alternate the two loads as normal, or lock the relay to one load or the other.By locking the Alternating Relay to one load, the other load can be removed for service without rewiring the first load for continuous operation.The selector switch has a low profile to prevent any accidental changes in status.Output :10A SPDT or DPDT Cross-Wired @ 240VAC/30VDC.Dimensions :1.7”x2.4”x 2.9”.Product NumberControlSPDT DPDT Cross-Voltage Contacts Wired Contacts Socket File E109461SPDT DPDT Cross-WiredNominalPick-up Drop-Out Product VoltageVoltage Range Voltage Range Number Socket 24V AC21-27V AC 20-26V AC VMP024A 120V AC102-138V AC 99-134V AC VMP120A 240V AC204-276V AC 198-267V AC VMP240A 12V DC10-14V DC 9-13V DC VMPO12D 24V DC 21-27V DC 20-26V DC VMP024D 8 PIN OCTAL 70169-D File E109461File LR45565**Requires 600V-rated socket* No socket required for PMD240 or PMD4801 1C O N T R O L S &S E N S OR S。
LABELMATE User_CAT-3-CE 使用说明书
MAINTENANCE:Periodically clean residue off Tension Roller C with a slightly damp cloth inorder to maintain friction between the Roller and the material being rewound. IMPORTANT INFORMATION:•This product is a label rewinder. It is only to be used to rewind or unwind labels of the recommended dimensions and weight in an indoor, dry environment.•The machine has to be unplugged before any manipulation.•The machine is to be used on a flat surface, if the surface is not flat, it is to be fixed using the holes in the base plate.•Do not leave the power cable in a passageway.•The ambient light of the working area needs to be sufficient to avoid any risk.•The rewinder can be used in ambient temperatures of +2°C to 40°C.•Connection of the machine to the power source must respect local and European legislations.ZCAT-3Zero Tension Loop Controlled Label RewinderRemove all parts from the shipping container and verify contents. PACKAGE CONTENTS:•User Manual (this document)•Allen Wrench•ZCAT-3 Drive Unit•Power Supply Module•LABELMATE “Quick-Chuck” ™ Quick-Locking Core Chuck•12” Plastic Flange Plate•Tensioning Roller•Loop Sensor•(Optional PC-1 Counter purchased separately)Retain the Shipping Container and Packaging for Storage and TransportSPECIFICATIONS:Weight of the machine: 16.8Kg.Max. Label Roll Weight:12Kg.Max. Label Roll Diam:300mmStart/Stop:ON/OFF Power SwitchPower Supply: Input: 120-220VAC inOutput: 24VDC.© LABELMATE – User_CAT-3-CE – 05/17 – Original user manual. ●KEEP MANUAL IN A SAFE PLACE FOR FUTURE REFERENCE ●SET-UP:1.Remove the two Phillips screws from the hollow end of the QUICK-CHUCK. Placethe Label Flange Plate on the QUICK-CHUCK by placing the hole of the Flange Plate over the Boss of the QUICK-CHUCK, and reaffixing the two screws through the Flange-Plate and into the QUICK-CHUCK.2.Slide the hollow end of the QUICK-CHUCK onto the ZCAT Motor Shaft allowing forclearance to the Chassis and Motor Screws. Tighten the Allen Screw of the QUICK-CHUCK onto the flat part of the Motor Shaft until it is tight.3.Set the unit in place near the printer.4.Verify that the “RUN/STOP” switch is in the “STOP” position, and tha t the TorqueAdjust Knob is turned counterclockwise all the way down.5.Place an empty label core onto the QUICK-CHUCK of the ZCAT Rewinder andpress snugly in place against the Label Flange Plate.6.Turn the red knob of the QUICK-CHUCK clockwise to expand the QUICK-CHUCKand affix the empty core firmly in place. REWINDING LABELS:7.Thread the material being printed onto the ZCAT as shown in “Figure A”:(a) Over Rod A(b) Underneath Roller B(c) Over and around the top of Tensioning Roller C(d) Under and around the bottom of Roller D(e) Tape the leading edge of the material onto the empty core that is onthe QUICK-CHUCK.(f) Using the supplied Allen Key, loosen the set-screw of Outer Guide Ring Fand position the Guide Ring next to the material being rewound. Retightenthe set-screw.(g) Loosen the thumb-screw of Outer Guide Ring E and position the Guide Ringnext to the material being rewound. Retighten the thumb-screw.(Note: the Inner Guide Rings that are positioned against the black metalchassis of the Rewinder on Rod A, and Rollers B and D require very littleadjustment, if any, and should be aligned with the face of the Label FlangePlate.)(h) Push down the material being printed between the printer and Rod Ato form a tensionless loop of material as seen in “Figure A”.8.Plug the Power Plug at the end of the wire on the Power Supply Module into theUnit’s Power Input Jack. Plug the Power Supply into an appropriate AC power outlet.9.Flip the Master Power Rocker Switch on the rear of the ZCAT to the “Power On”position.10.Adjust the angle of Sensor G so that it points at the desired location on thetensionless loop of material. The angle of the sensor determines the depth of the loop. Note: The Rewinder will continue to turn as long as the eye of the sensor can “see” the material in the tensionless loop.)11.Select either the “HIGH” or “LOW” Torque Setting with the switch on the top ofthe unit.12.Select the desired rewind direction with the switch on the top of the unit.13.Flip the “RUN/STOP” switch to “RUN”.14.Turn the black knob of Tensioning Roller C to adjust/achieve the desired tensionof the material being rewound.15.Gradually turn the Torque Adjust Knob clockwise until the desired rewind speedis achieved.。
基于Logistic映射的动态密钥加密算法
基于Logistic映射的动态密钥加密算法一l学术.技术口I勺动态密钥加密算法,马亮.学院,陕西西安710055)巧性和非周期性等特点,展现出优良的密码学性能.该加密算法t制序列,结合DNA序列变迁重组算法和DES算法对64位明文分基攻击和选择密文攻击等多种攻击手段.IgorithmBasedonLogisticMapn.MALiang'(Schoolofman~emenQX//anUn/vers/tyofArchitect#reandTechnology,Xi'an7/0055,P.冠.chin3)Abstract:haoticsequencewiththefeaturesofrandomness,theextremesensitivityoftheinitia lconditions,ergodicityandaperiodictraversalsensitivity,showexcellentcryptographyperformance.Theencryptionalgorithmproducesc haoticsequencethroughzLogisticmap,andthechaoticsequenceismappedtothe64binarysequence,whichencryptsa64plaintextblockcombining DESalgorithmandDNAsequencemigrationrecombinantalgorithm.DESinitialkeyisinthemodeofdynamicchangeThealgorithmcanef fectivelyresistmanymeansofattacksuchas exhaustiveattackandchosenciphertextattackKeywords:Chaoticencryption;Logisticmap;DNAsequencemigrationrecombinantchang es1引言随着互联网和计算机技术的迅猛发展,大量的敏感信息通过网络传输,因此信息的安全性显得愈发重要.而加密是解决网络信息安全的关键技术,信息的保密性,完整性,可用性和抗抵赖性,都需要采用加密技术来实现.黑客攻击手段的多样化,高效性,对传统的加密算法构成了严重的威胁.DES(DataEncryptionStandard)是现代密码学中分组密码的典型代表,被广泛应用于金融财政等重要机构. DES自公布以来,经受了各种密码分析攻击,但随着计算机和网络技术的发展,最终在穷举密钥攻击下被破译,原因是它的密钥空间太小.虽然DES被破译,由于其深厚的社会基础和商用资源,提高其安全性能仍然是人们热衷研究的一项工作.设想如果能找到一种合理方案,使得DES的密钥空间任意拓展,则其安全性的问题就能得到很好的解决.混沌是确定性系统中的一种貌似随机的运动,它不同于一般的随机性,而是指非线性系统在没有外界随机因素的情况下,因系统的状态对初始条件的敏感依赖性而产生的一种内在的随机过程.在混沌现象中,只要初始条件稍有不同,其结果就大相径庭,难以预测.混沌系统迭代产生的时间序列对初始条件敏感,结构复杂难以分析和预测,可以提供具有良好的随机性,相关性,复杂性的伪随机序列,混沌时间序列理论上具有类随机性,破坏了相关分析的适用性,保密性得以加强.DNA,即脱氧核糖核酸,存在于每个细胞组织中,是遗传信息的载体.近年来,DNA技术发展迅速,不但影响到生命,医学领域,对信息科学也带来了举世的注目.DNA分子中的遗传密码相当于存储的数据,DNA分子问通过生化反应,从一种基因代码转变成另一种基因代码.文献【l1深入分析了DNA序列处理中的切片重组技术, 研究了这种技术在加密中的应用.2混沌系统基本特性2.1混沌序列的特性及在加密领域中的应用.混沌是自然界和人类社会普遍存在的一种现象.混沌理论是现代科学和现代技术,特别是计算机技术相结合的-- 产物.自从Lorenz于1963年在大气科学的研究中首先提0 出了混沌的概念后,混沌在各个领域都得到了不同程度的运混沌系统具有以下明显的特性:一(1)随机性,只要选取的参数在混沌区,方程所输出薯的序列即为混沌的.(2)确定性,混沌是由确定性方程产生的,只要方程董参数和初值确定就可以重现混沌现象.尽管{i;}出现随机的性质,但它可由确定性方程给定,即{x+.}可由{≮i.}导出.(3)遍历性,混沌运动的遍历性是指混沌变量能在一曩!:堡塑堑堕堡riWV~N!nSc;org.Gn/|定范围内按其一定的规律不重复地遍历所有状态.(4)对初值的敏感性,初值{xn}的微小的差异,{X}将有很大的差异.混沌系统所具有的这些基本特性恰好能够满足Shannon在他的经典论文中所提出的密码系统设计的两个基本原则一扩散和混淆原则.信息论的奠基人,美国数学家Sha/inon指出:若能以某种方式产生一随机序列,这一序列由密钥所确定,任何输入值的一个微小变化对输出都具有相当大的影响,则利用这样的序列就可以进行加密.混沌系统恰恰符合这种要求.2.2Logistic映射的性质Logistic映射是最典型的,也是研究的最广泛的动力系统,其定义如下=,1f卜.)(1)其中:0≤,≤4为分又参数.混沌动力学的研究表明,当3.5699456…<,≤4时,Logistic映射处于混沌状态,即产生的序列{x,k=0,l,2,3…}是非周期的,不收敛的,且对初始值非常敏感.当--4时,该映射是满射,产生的混沌序列在区间(0,1)上具有遍历性.这点正是Logistic映射用于密码学的优势.3DES算法和DNA序列变迁重组算法3.1DES算法DES是一种对称分组加密算法,加密和解密过程完全对称.DES算法的输入是64位的分组明文,使用64位的初始密钥对明文进行l6轮完全相同的变换.64位的明文通过一个初始置换,然后被分成左半部分和右半部分, 各32位长.右半部分经过扩展变换由32位扩展成48位序列.64位初始密钥经过一系列置换和移位后变换成48 位子密钥,再与明文的右半部分相结合通过变换函数f的作用后,输出32位序列.该序列和明文的左半部分异或作为明文新的右半部分,而变换前的右半部分作为明文新的左半部分,这一系列的步骤构成了一轮变换,重复操作16次便实现了DES的16轮运算.最后左右部分合在一起经过一个末置换完成算法.3.2DNA序列变迁重组算法DNA序列由A,G,C,T4种碱基排列而成.如果用0—1序列表示这4种碱基,可以按照一定的组合选择一个规则,这里我们用这样的规则表示A,G,C,T序列,即00-A,01-C,10-G,1I-T.例如,二进制序列01001111,表示为DNA序列就是CATT.茜2007-12i下面给出DNA序列变迁重组算法的基本框架:步骤l将Gi,i--0,l,2,…,N-1,个体排列成A,G,C,T组成的连续的序列L;步骤2将序列中的碱基C变迁为碱基G;步骤3令GO中"l"的个数为Mi步骤4如果M为偶数,则连续切分L,切分N块,每块M/2个碱基,接着继续连续切分L,切分N块,每块4一M/2个碱基,然后前后N块对应组合起来.步骤5如果M为奇数,则首先将序列中的碱基G变迁为碱基A,然后连续切分L,切分N块,每块(M+1)/2个碱基,接着继续连续切分L,切分N块,每块4一(M+1) /2个碱基,然后前后N块对应组合起来.步骤6算法结束.例如,对于N-4的碱基序列,每个G为8位,则序列总计l6个碱基.假设为ACCGTGATTAACATCA,序列中的碱基C首先变迁为碱基G,则变换后的结果为AGGGTGATTAAGATGA设M=2,则首先以每块1个碱基切分L得到4块,分别是A,G,G,G.继续切分,每块3个碱基,得到4块,分别是TGA,TTA,AGA,TGA.前后组合得到新的N个个体,依次为ATGA,GTTA,GAGA,GTGA.4混沌加密算法实现4,1混沌加密算法具体实现DES算法的64位初始密钥是固定不变的,对每64位明文采用相同的初始密钥加密.本算法通过在加密端和解密端构造参数相同的Logistic映射,初始值作为原始密钥. 利用Logistic映射产生混沌序列,为了得到更好的随机序列,兼顾加密速度的要求Logistic映射迭代1000次后取密钥流.将初始迭代1000次后将得到的混沌序列数字离散化.选择每一个混沌实数序列小数点后有效位数的任意三位,譬如7,8,9位组成三位数整数对255取余.将这样的8个混沌实数序列离散化的结果作为一组正好是64 位二进制数字.对于混沌离散化后得到的64位二进制数字,统计其中1的个数.若1的个数为偶数个,则将其作为DES算法的初始64位密钥,每加密64位明文数据变换一次初始密钥, 真正实现一次一密加密;若1的个数为奇数个,则将该64 位二进制数字通过DNA序列变迁重组算法重组,将重组的结果直接与64位明文数据异或.具体算法步骤如下: (1)输入Logistic映射初值作为原始密钥并初始迭代1000次;(2)读取明文串,每64位为一组读入;(3)判断加密完成否,若完成退出,否则转(4);(4)将Logistic映射每迭代8次产生的混沌序列离散化为64位二进制序列.通常产生的实数混沌序列有效数字有l6位, 在离散化的过程中,为了进一步增强序列的随机性,选择3位有效数字的方式并不惟一,在编程的时候根据具体情况灵活选择(5)统计64位二进制序列中数字l的个数(6)若n为偶数则将64位二进制序列作为DES算法的初始密钥加密64位明文数据.若n为奇数则将64位二进制序列通过DNA序列变迁重组算法重组,将重组后的结果直接与64位明文数据异或产生密文,转(2).算法流程图如图(1)所示:解密时采用相同的算法即可正确解密获得原始明文.图1混沌算法加密流程图4算法仿真与分析选取Logistic映射初值xO=O.406719,,--4.在计算机上仿真结果如下:■黧(a)加密前(b)加密后(c)正确解密后(d)错误解密后图2仿真结果图2中(a)是原始图像,(b)为加密后图像,加密后的图像变得杂乱无章,(C)为正确解密后的图像,和原始图像毫无差异.而(d)是采用错误密钥解密后的图像,仅将解密密钥变成0.406717,和正确解密密钥0.406719差别很小,无法正确还原原始图像.可见该算法对初值的极度敏感性.算法特性分析:(1)由仿真实验可知该混沌加密对初值具有极度敏感性,从理论上讲混沌初值的选取是无穷的,因此可以提供极大的密钥空间.采用穷举攻击几乎是不可能的.在实际运用中,初始密钥空间的大小受计算机精度限制,即初值的取值范围是受限的.可根jl学术.技术门据实际应用情况设计相应精度的硬件和软件,以满足不同}等级的安全性要求.(2)采用Logistic映射产生的混沌序:列作为DES算法的初始密钥,每加密64位明文数据变换|初始密钥,密钥处于动态变化中,攻击者很难得到统计学j的数据,可有效地防止频率攻击.(3)64位二进制序列通过DNA序列变迁重组算法重组后与明文异或属于流密码加密的范畴,而DES加密则属于典型的分组密码加密. 该算法将两者有机地结合在一起,而具体采用那种方式加密明文分组则通过二进制序列中l的个数来控制,控制方择明文攻击时也要分辨哪些密文是通过DES加密得到的,增加了破译的难度.(4)为了使该算法实际中得到改善需要找到一个理想的混沌系统,产生更加随机的混沌序列,真正实现"一次一密"加密.参考文献:[1]关涛,邵志清等.基于DNA序列切片重组技术的信息加密算法[J].计算机工程,2005,51[2]吴祥兴,陈忠等.混沌学导论[M].上海:上海科学技术文献出版社,1996[5]陈关荣,汪小帆.动力系统的混沌化[M].上海交通大学出版社2006[4]美BruceSchneier着吴世忠,祝世雄等译.应用密码学协议,算法与c语言源程序[M].机械工业出版社,2005[5]李红达,冯登国.基于复合离散混沌动力系统的序列密码算法[J].软件,2005,I4(5):992997[6]权安静.基于超混沌序列的分组密码算法及其应用【J].南京邮电学院,2005,8(4):80—84.[7]丘水生.混沌吸引子的周期轨道理论研究(I)[J].电路与系统,2005,8(6):1—5.[8]高俊山,孙百瑜,韩伟.基于混沌理论的控制轨道函数构造[J].电机与控制,2002,(2):I50一I55.[9]LiShujun,MouXuanqin,CaiYuanlong.Improvingsecurityofa chaoticencryptionapproach[J].PhysicsLettersA,200I,(29O 127—155[10]MartinHasler,GianlucaMazzini.Specialissueonapplication ofnonlineardynamicstoelectronicandinformationengineering[d]. ProceedingsofthelEEE,200290(5):651—64O.作者简介:陆秋琴(1966一),女,西安建筑科技大学管理学院副教授,研究方向:电子商务与网络安全;马亮(1982一),硕士研究生,现就读于西安建筑科技大学管理学院,研究方向为信息对抗与网络安全. 收稿日期:2007—07—09 11::!堡壁塑塞墨www.nse:org?on\.。
Step-Down Switching Regulators
Step-Down Switching RegulatorsJim WilliamsA substantial percentage of regulator requirements involve stepping down the primary voltage. Although linear regulators can do this, they cannot achieve the effi ciency of switching based approaches 1. The theory supporting step-down (“buck”) switching regulation is well established, and has been exploited for some time. Convenient, easily applied ICs allowing implementation of practical circuits are, however , relatively new. These devices permit broad application of step-down regulation with minimal complexity and low cost. Additionally, more complex functions incorporating step-down regulation become realizable.Basic Step Down CircuitF igure 1 is a conceptual voltage step-down or “buck” circuit. When the switch closes the input voltage appears at the inductor . Current fl owing through the inductor-ca-pacitor combination builds over time. When the switchINFigure 1. Conceptual Voltage Step-Down (“Buck”) Circuitopens current fl ow ceases and the magnetic fi eld around the inductor collapses. Faraday teaches that the voltage induced by the collapsing magnetic fi eld is opposite to the originally applied voltage. As such, the inductor’s left side heads negative and is clamped by the diode. The capaci-tors accumulated charge has no discharge path, and a DC potential appears at the output. This DC potential is lower than the input because the inductor limits current during the switch’s on-time. Ideally, there are no dissipative ele-ments in this voltage step-down conversion. Although the output voltage is lower than the input, there is no energylost in this voltage-to-current-to-magnetic fi eld-to-cur-rent-to-charge-to-voltage conversion. In practice, thecircuit elements have losses, but step-down effi ciency is still higher than with inherently dissipative (e.g., voltage divider) approaches. Figure 2 feedback controls the basic circuit to regulate output voltage. In this case switch on-time (e.g., inductor charge time) is varied to maintain the output against changes in input or loading.INFigure 2. Conceptual Feedback Controlled Step-Down RegulatorPractical Step-Down Switching RegulatorFigure 3, a practical circuit using the L T ®10742 IC regulator , shows similarities to the conceptual regulator . Some new elements have also appeared. Components at the L T1074’s “V COMP ” pin control the IC’s frequency compensation, stabilizing the feedback loop. The feedback resistors are selected to force the “feedback” pin to the device’s internal 2.5V reference value. F igure 4 shows operating waveforms for the regulator at V IN = 28V with a 5V , 1A load.L , L T , L TC, L TM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.Note 1: While linear regulators cannot compete with switchers, they can achieve signifi cantly better effi ciencies than generally supposed. See L TC Application Note 32, “High Effi ciency Linear Regulators,” for details.Note 2: See Appendix A for details on this device.T race A is the V SW pin voltage and T race B is its current. Inductor current 3 appears in T race C and diode current is T race D. Examination of the current waveforms allows determination of the V SW and diode path contributions to inductor current. Note that the inductor current’s waveform occurs on top of a 1A DC level. Figure 5 shows signifi cant duty cycle changes when V IN is reduced to 12V . The lower input voltage requires longer inductor charge times to maintain the output. The L T1074 controls inductor charge characteristics (see Appendix A for operating details), with resulting waveform shape and time proportioning changes.F igure 6 compares this circuit’s effi ciency with linear regulators in a common and important situation. Effi cient regulation under varying AC line conditions is a frequent requirement. The fi gure assumes the AC line has been transformed down to acceptable input voltages. The input voltages shown correspond to the AC line voltages given on the horizontal axis. Effi ciency for the LM317 and L T1086 linear regulators suffers over the wide input range.Note 3: Methods for selecting appropriate inductors are discussed in Appendix B.L1V INFigure 3. A Practical Step-Down Regulator Using the L T1074Figure 4. Waveforms for the Step-Down Regulator at V IN = 28V and V OUT = 5V at 1AAC LINE VOLTAGE800E F F I C I E N C Y (%)20406090100110120AN35 F06130801001030507090140Figure 6. Efficiency vs AC Line Voltage for the LT1074. LT1086 and LM317 Linear Regulators are Shown for ComparisonFigure 5. Waveforms for the Step-Down Regulator at V IN = 12V and V OUT = 5V at 1AA = 20V/DIVB = 1A/DIV D = 1A/DIVHORIZ = 5μs/DIVAN35 F04C = 0.2A/DIV ON 1A DC LEVELA = 20V/DIVB = 1A/DIV D = 1A/DIVHORIZ = 5μs/DIVAN35 F05C = 0.2A/DIV ON 1A DC LEVELThe L T1086 is notably better because its lower dropout voltage cuts dissipation over the range. Switching pre-regulation 4 can reduce these losses, but cannot equal the L T1074’s performance. The plot shows minimum effi ciency of 83%, with some improvement over the full AC line excursion. Figure 7 details performance. Effi ciency approaches 90% as input voltage rises. This is due to minimization of the effects of fi xed diode and L T1074 junc-tion losses as input increases. At low inputs these losses are a higher percentage of available supply, degrading effi ciency. Higher inputs make the fi xed losses a smaller percentage, improving effi ciency. Appendix D presents detail on optimizing circuitry for effi ciency.Note 4: See Reference 1.Dual Output Step-Down RegulatorFigure 8, a logical extension of the basic step-down con-verter , provides positive and negative outputs. The circuit is essentially identical to Figure 3’s basic converter with the addition of a coupled winding to L1. This fl oating winding’s output is rectifi ed, fi ltered and regulated to a –5V output. The fl oating bias to the L T1086 positive voltage regulator permits negative outputs by assigning the regulator’s output terminal to ground. Negative output power is set by fl ux pick-up from L1’s driven winding. With a 2A load at the +15 output the –5V output can supply over 500mA. Because L1’s secondary winding is fl oating its output may be referred to any point within the breakdown capability of the device. Hence, the secondary output could be 5V or , if stacked on the +15 output, 20V .Negative Output RegulatorsNegative outputs can also be obtained with a simple 2-ter-minal inductor . Figure 9 demonstrates this by essentially grounding the inductor and steering the catch diodes negative current to the output. A1 facilitates loop closure by providing a scaled inversion of the negative output to the L T1074’s feedback pin. The 1% resistors set the scale factor (e.g., output voltage) and the RC network around A1 gives frequency compensation. Waveforms for this circuit are reminiscent of Figure 5, with the exception that diodeINPUT VOL TAGEE F F I C I E N C Y (%)608010024AN35 F0740205070903010012101614202226183028Figure 7. Efficiency Plot for Figure 3. Higher Input Voltages Minimize Effects of Saturation Losses, Resulting in Increased EfficiencyL1: PULSE ENGINEERING, INC. #PE-6505028VINPUTAN35 F08Figure 8. Coupled Inductor Provides Positive and Negative Outputscurrent (T race D) is negative. T races A, B and C are V SW voltage, inductor current and V SW current respectively.Figure 11, commonly referred to as “Nelson’s Circuit,” provides the same function as the previous circuit, but eliminates the level-shifting op amp. This design accom-plishes the level shift by connecting the L T1074’s “ground” pin to the negative output. Feedback is sensed from circuit ground, and the regulator forces its feedback pin 2.5V above its “ground” pin. Circuit ground is common to input and output, making system use easy. Operating waveforms are essentially identical to Figure 10. Advantages of the previous circuit compared to this one are that the L T1074 package can directly contact a grounded heat sink and that control signals may be directly interfaced to the ground referred pins.The inductor values in both negative output designs are notably lower than in the positive case. This is necessitatedby the reduced loop phase margin of these circuits. Higher inductance values, while preferable for limiting peak cur-rent, will cause loop instability or outright oscillation.Current-Boosted Step-Down RegulatorF igure 12 shows a way to obtain signifi cantly higher output currents by utilizing effi cient energy storage in the L T1074 output inductor . This technique increases the duty cycle over the standard step-down regulator allowing more energy to be stored in the inductor . The increased output current is achieved at the expense of higher output voltage ripple.The operating waveforms for this circuit are shown in Figure 13. The circuit operating characteristics are similar to that of the step-down regulator (Figure 3). During the V SW (T race A) “on” time the input voltage is applied to one end of the coupled inductor . Current through the V SW pin (T race B) ramps up almost instantaneously (since inductor current (T race F) is present) and then slows as energy is stored in the core. The current proceeds into the inductor (T race D) and fi nally is delivered to the load. When the V SW pin goes off, current is no longer available to charge the inductor . The magnetic fi eld collapses, causing the V SW pin voltage to go negative. At this point similarity with the basic regulator vanishes. In this modifi ed version the output current (T race F) receives a boost as the magnetic fi eld collapses. This results when the energy stored in12V INPUT–5V OUTPUTFigure 9. A Negative Output Step-Down RegulatorFigure 10. Figure 9’s WaveformsA = 20V/DIVB = 1A/DIV D = 4A/DIVHORIZ = 5μs/DIVAN35 F10C = 4A/DIVthe core is transferred to the output. This current step circulates through C1 and D2 (T race E), somewhat increas-ing output voltage ripple. Not all the energy is transferred to the “1” winding. Current (T race C) will continue to fl ow in the “N” winding due to leakage inductance. A snubber network suppresses the effects of this leakage inductance. For lowest snubber losses the specifi ed tapped inductor is bifi lar wound for maximum coupling.Post Regulation-Fixed CaseIn most instances the L T1074 output will be applied directly to the load. Those cases requiring faster transient responseor reduced noise will benefi t from linear post regulation. In F igure 14 a 3-terminal regulator follows the L T1074 output. The L T1074 output is set to provide just enough voltage to the L T1084 to maintain regulation. The L T1084’s low dropout characteristics combined with a high circuit input voltage minimizes the overall effi ciency penalty.OUT VFigure 11. Nelson’s Circuit...A (Better) Negative Output Step-Down Regulator5V OUT10AVFigure 12. “Current Boosted” Step-Down Regulator. Boost Current is Supplied By Energy Stored in the Tapped InductorFigure 13. AC Current Flow for the Boosted RegulatorA = 50V/DIVB = 5A/DIVD = 10A/DIVE = 10A/DIVF = 10A/DIVHORIZ = 2μs/DIV AN35 F10C = 10A/DIVPost Regulation-Variable CaseSome situations require variable linear post regulation. F igure 15 does this with little effi ciency sacrifi ce. The L T1085 operates in normal fashion, supplying a variable 1.2V to 28V output. The remainder of the circuit forms a switched mode pre-regulator which maintains a small, fi xed voltage across the L T1085 regardless of its output voltage. A1 biases the L T1074 to produce whatever voltage is necessary to maintain the “E diodes” potential across the L T1085. A1’s inputs are balanced when the L T1085 output is “E diodes” above its input. A1 maintains this condition regardless of line, load or output voltage conditions. Thus, good effi ciency is maintained over the full range of output voltages. The RC network at A1 compensates the loop. Loop start-up is assured by deliberately introduc-ing a positive offset to A1. This is done by grounding A1’s appropriate balance pin (5), resulting in a positive 6mV offset. This increases amplifi er drift, and is normally considered poor practice, but causes no measurable error in this application.As shown, the circuit cannot produce outputs below the L T1085’s 1.2V reference. Applications requiring output adjustability down to 0V will benefi t from option “A” shown on the schematic. This arrangement replaces L1 with L2. L2’s primary performs the same function as L1 and its coupled secondary winding produces a negative bias output (–V). The full-wave bridge rectifi cation is necessitated by widely varying duty cycles. A2 and its at-tendant circuitry replace all components associated withthe L T1085 V ADJ pin. The L T1004 reference terminates the 10k to 250k feedback string at –1.2V with A2 provid-ing buffered drive to the L T1085 V ADJ pin. The negative bias allows regulated L T1085 outputs down to 0V . The –V potential derived from L2’s secondary varies consider-ably with operating conditions. The high feedback string values and A2’s buffering ensure stable circuit operation for “starved” values of –V .Low Quiescent Current RegulatorsMany applications require very wide ranges of power sup-ply output current. Normal conditions require currents in the ampere range, while standby or “sleep” modes draw only microamperes. A typical laptop computer may draw 1 to 2 amperes running while needing only a few hundred microamps for memory when turned off. In theory, any regulator designed for loop stability under no-load condi-tions will work. In practice, a converter’s relatively large quiescent current may cause unacceptable battery drain during low output current intervals. Figure 16’s simple loop effectively reduces circuit quiescent current from 6mA to only 150μA. It does this by utilizing the L T1074’s shutdown pin. When this pin is pulled within 350mV of ground the IC shuts down, pulling only 100μA. Comparator C1 combines with the L T1004 reference and Q1 to form a “bang-bang” control loop around the L T1074. The L T1074’s internal feedback amplifi er and voltage reference are by-passed by this loop’s operation. When the circuit output (T race C, Figure 17) falls slightly below 5V C1’s output (T race A) switches low, turning off Q1 and enabling theL1V IN5V OUTFigure 14. Linear Post-Reglator Improves Noise and T ransient ResponseL1: PULSE ENGINEERING, INC. #PE-51516L2: PULSE ENGINEERING, INC. #PE-6505035V INPUTOUTAN35 F15OPTION “A”(FOR OUTPUT DOWN TO 0V)SEE TEXT FOR DISCUSSIONL112V INPUT5V OUTFigure 15. Adjustable Linear Post-Regulator Maintains Efficiency Over Widely Varying Operating ConditionsFigure 16. A Simple Loop Reduces Quiescent Current to 150μAL T1074. The V SW pin (T race B) pulses at full duty cycle, forcing the output back above 5V . C1 then biases Q1 again, the L T1074 goes into shutdown, and loop action repeats.The frequency of this on-off control action is directly load dependent, with typical repetition rates of 0.2Hz at no load. Short on-times keep duty cycle low, resulting in the small effective quiescent current noted. The on-off operation combines with the LC fi ltering action in the regulator’s V SW line to generate an output hysteresis of about 50mV (again, see Figure 17, T race C).The loop performs well, but has two potential drawbacks. At higher output currents the loop oscillates in the 1kHz to 10kHz range, causing audible noise which may be objec-tionable. This is characteristic of this type of loop, and is the reason that ICs employing gated oscillators invariably produce such noise. Additionally, the control loops opera-tion causes about 50mV of ripple on the output. Ripple frequency ranges from 0.2Hz to 10kHz depending upon input voltage and output current.Figure 18’s more sophisticated circuit eliminates these problems with some increase in complexity. Quiescent current is maintained at 150μA. The technique shown is particularly signifi cant, with broad implication in battery powered systems. It is easily applied to a wide variety of regulator requirements, meeting an acknowledged need across a wide spectrum of applications.Figure 18’s signal fl ow is similar to Figure 16, but ad-ditional circuitry appears between the feedback divider and the L T1074. The L T1074’s internal feedback amplifi er and reference are not used. Figure 19 shows operatingFigure 17. The Low Quiescent Current Loop’s WaveformsV IN–+12VFigure 18. A More Sophisticated Loop Gives Better Regulation While Maintaining 150μA Quiescent CurrentA = 10V/DIVB = 10V/DIV HORIZ = 100μs/DIVAN35 F17C = 0.1V/DIV AC-COUPLED ON 5V DC LEVELwaveforms under no-load conditions. The output (T race A) ramps down over a period of seconds. During this time comparator A1’s output (T race B) is low, as are the 74C04 paralleled inverters. This pulls the V C pin (T race D) low, forcing the regulator to zero duty cycle. Simultaneously, A2 (T race C) is low, putting the L T1074 in its 100μA shutdown mode. The V SW pin (T race E) is off, and no inductor current fl ows. When the output drops about 60mV , A1 triggers and the inverters go high, pulling the V C pin up and biasing the regulator . The Zener diode prevents V C pin overdrive. A2 also rises, taking the IC out of shutdown mode. The V SW pin pulses the inductor at the 100kHz clock rate, causing the output to abruptly rise. This action trips A1 low, forcing the V C pin back low and shutting off V SW pulsing. A2 also goes low, putting the L T1074 into shutdown.This “bang-bang” control loop keeps the 5V output within the 60mV ramp hysteresis window set by the loop. Note that the loop oscillation period of seconds means the R1-C1time constant at V C is not a significant term. Because the L T1074 spends almost all of the time in shutdown, very little quiescent current (150μA) is drawn.Figure 20 shows the same waveforms with the load in-creased to 2mA. Loop oscillation frequency increases to keep up with the load’s sink current demand. Now, the V C pin waveform (T race D) begins to take on a fi ltered ap-pearance. This is due to R1-C1’s 10ms time constant. If the load continues to increase, loop oscillation frequency will also increase. The R1-C1 time constant, however , is fi xed. Beyond some frequency, R1-C1 must average loop oscillations to DC. At 7mA loading (Figure 21) loop fre-quency further increases, and the V C waveform (T race D) appears heavily fi ltered.Figure 22 shows the same circuit points at 2A loading. Note that the V C pin is at DC, as is the shutdown pin. Repetition rate has increased to the L T1074’s 100kHzFigure 19. Low Quiescent Current Regulator’s Waveforms with No Load (T races B, C and E Retouched for Clarity)Figure 20. Low Quiescent Current Regulator’s Waveforms at 2mA LoadingFigure 21. Low Quiescent Current Regulator’s Waveforms at 7mA Loading Figure 22. Low Quiescent Current Regulator’s Waveforms at 2A LoadingA = 0.1V/DIV AC-COUPLEDB = 20V/DIV HORIZ = 0.5 SECOND/DIVAN35 F19C = 20V/DIVD = 2V/DIVE = 10V/DIVA = 0.1V/DIV AC-COUPLEDB = 20V/DIV HORIZ = 20ms/DIVAN35 F20C = 20V/DIVD = 2V/DIVE = 10V/DIVA = 0.1V/DIV AC-COUPLEDB = 20V/DIV HORIZ = 10ms/DIVAN35 F21C = 20V/DIVD = 2V/DIVE = 10V/DIVA = 0.2V/DIV AC-COUPLEDB = 20V/DIV HORIZ—TRACES A AND E = 10μs/DIV TRACES B, C, D = 5ms/DIVAN35 F22C = 20V/DIVD = 2V/DIVE = 20V/DIVclock frequency. Figure 23 plots what is occurring, with a pleasant surprise. As output current rises, loop oscilla-tion frequency also rises until about 23Hz. At this point the R1-C1 time constant fi lters the V C pin to DC and the L T1074 transitions into “normal” PWM operation. With the V C pin at DC it is convenient to think of A1 and the inverters as a linear error amplifi er with a closed-loop gain set by the R2-R3 feedback divider . In fact, A1 is still duty cycle modulating, but at a rate far above R1-C1’s break frequency. The phase error contributed by C2 (which was selected for low loop frequency at low output currents) is dominated by the R1-C1 roll off and the C3 lead into A1. The loop is stable and responds linearly for all loads beyond 10mA. In this high current region the L T1074 is desirably “fooled” into behaving like a conventional step-down regulator .A formal stability analysis for this circuit is quite complex, but some simplifi cations lend insight into loop operation. At 250μA loading (20kΩ) C2 and the load form a decay time constant exceeding 30 seconds. This is orders of magnitude larger than R2-C3, R1-C1, or the L T1074’s 100kHz commutation rate. As a result, C2 dominates the loop. Wideband A1 sees phase shifted feedback, and very low frequency oscillations similar to Figure 19’s occur 5. Although C2’s decay time constant is long, its charge time constant is short because the circuit has low sourc-ing impedance. This accounts for the ramp nature of the oscillations.Increased loading reduces the C2-load decay time con-stant. Figure 23’s plot refl ects this. As loading increases,the loop oscillates at a higher frequency due to C2’s de-creased decay time. When the load impedance becomes low enough C2’s decay time constant ceases to dominate the loop. This point is almost entirely determined by R1 and C1. Once R1 and C1 “take over” as the dominant time constant the loop begins to behave like a linear system. In this region (e.g., above about 10mA, per Figure 23) the L T1074 runs continuously at its 100kHz rate. Now, C3 becomes signifi cant, performing as a simple feedback lead 6 to smooth output response. There is a fundamental trade-off in the selection of the C3 lead value. When the converter is running in its linear region it must dominate the loops time lag generated hysteretic characteristic. As such, it has been chosen for the best compromise between output ripple at high load and loop transient response.Despite the complex dynamics transient response is quite good. Figure 24 shows performance for a step from no load to 1A. When T race A goes high a 1A load appears across the output (T race C). Initially, the output sags al-most 200mV due to slow loop response time (the R1-C1 pair delay V C pin (T race B) response). When the L T1074 comes on response is reasonably quick and surprisingly well behaved considering circuit dynamics. The multi-time constant recovery 7 (“rattling” is perhaps more appropriate) is visible in T race C’s response.Note 5: Some layouts may require substantial trace area to A1’s inputs. In such cases the optional RC network around A1 ensures clean transitions at A1’s output.Note 6: “Zero Compensation” for all you technosnobs out there.Note 7: Once again, “multi-pole settling” for those who adore jargon.OUTPUT (mA)L O O P F R E Q U E N C Y (H z )4812162468AN35 F23101220Figure 23. Figure 18’s Loop Frequency vs Output Current. Note Linear Loop Operation Above 10mAFigure 24. Load T ransient Response for Figure 18A = 10V/DIVB = 2V/DIVHORIZ = 5ms/DIVAN35 F24C = 0.2V/DIV ON 5V DC LEVELF igure 25 plots effi ciency versus output current. High power effi ciency is similar to standard converters. Low power effi ciency is somewhat better , although poor in the lowest ranges. This is not particularly bothersome, as power loss is very small.The loop provides a controlled, conditional instability instead of the usually more desirable (and often elusive) unconditional stability. This deliberately introduced char-acteristic dramatically lowers converter quiescent current without sacrifi cing high power performance.a toroidal DC/DC converter comprised of L1, Q1 and Q2. Q1 and Q2 receive out of phase square wave drive from the 74C74 ÷ 4 fl ip-fl op stage and the L T1010 buffers. The fl ip-fl op is clocked from the L T1074 V SW output via the Q3 level shifter . The L T1086 provides 12V power for A1 and the 74C74. A1 biases the L T1074 regulator to produce the DC input at the DC/DC converter required to balance to loop. The converter has a voltage gain of about 20, resulting in high voltage output. This output is resistively divided down, closing the loop at A1’s negative input. Frequency compensation for this loop must accommodate the signifi -cant phase errors generated by the L T1074 confi guration, the DC/DC converter and the output LC fi lter . The 0.47μF roll-off term at A1 and the 100Ω-0.15μF RC lead network provide the compensation, which is stable for all loads.Figure 27 gives circuit waveforms at 500V output into a 100W load. T race A is the L T1074 V SW pin while T race B is its current. T races C and D are Q1 and Q2’s drain waveforms. The disturbance at the leading edges is due to cross-current conduction, which lasts about 300ns—a small percent-age of the cycle. T ransistor currents during this interval remain within reasonable values, and no overstress or dissipation problems occur . This effect could be eliminated with non-overlapping drive to Q1 and Q28, although there would be no reliability or signifi cant effi ciency gain. The 500kHz ringing on the same waveforms is due to excita-tion of transformer resonances. These phenomena are not deleterious, although L1’s primary RC damper is included to minimize them.All waveforms are synchronous because the fl ip-fl op drive stage is clocked from the L T1074 V SW output. The L T1074’s maximum 95% duty cycle means that the Q1-Q2 switches can never see destructive DC drive. The only condition allowing DC drive occurs when the L T1074 is at zero duty cycle. This case is clearly non-destructive, because L1 receives no power .Figure 28 shows the same circuit points as Figure 27, but at only 5mV output. Here, the loop restricts drive to the DC/DC converter to small levels. Q1 and Q2 chop just 70mV into L1. At this level L1’s output diode drops look large, but loop action forces the desired 0.005V output.OUTPUT CURRENTE F F I C I E N C Y (%)6080100 2.0AN35 F254020507090301000.51.01.52.5Figure 25. Efficiency vs Output Current for Figure 18. Standby Efficiency is Poor , But Power Loss Approaches Battery Self-DischargeWide Range, High Power , High Voltage Regulator BEFORE PROCEEDING ANY FURTHER, THE READER IS WARNED THAT CAUTION MUST BE USED IN THE CONSTRUCTION, TESTING AND USE OF THIS CIRCUIT . HIGH VOL TAGE, LETHAL POTENTIALS ARE PRESENT IN THIS CIRCUIT . EXTREME CAUTION MUST BE USED IN WORKING WITH AND MAKING CONNECTIONS TO THIS CIRCUIT . REPEAT : THIS CIRCUIT CONTAINS DANGER-OUS, HIGH VOL TAGE POTENTIALS. USE CAUTION.Figure 26 is an example of the L T1074 making a complex function practical. This regulator provides outputs from mil-livolts to 500V at 100W with 80% effi ciency. A1 compares a variable reference voltage with a resistively scaled version of the circuit’s output and biases the L T1074 switching regulator confi guration. The switcher’s DC output drivesNote 8: For an example of this technique see L TC Application Note 29, Figure 1.T 28V I N100μS O L I T A N T A L U F i g u r e 26. L T 1074 P e r m i t s H i g h V o l t a g e O u t p u t O v e r 100d B R a n g e w i t h P o w e r a n d E f f i c i e n c y .D A N G E R ! L e t h a l P o t e n t i a l s P r e s e n t —S e e T e x tThe L T1074’s switched mode drive to L1 maintains high effi ciency at high power , despite the circuits wide output range 9.Figure 29 shows output noise at 500V into a 100W load. Q1-Q2 chopping artifacts and transformer related ringing are clearly visible, although limited to about 80mV . The coherent noise characteristic is traceable to the synchro-nous clocking of Q1 and Q2 by the L T1074.A 50V to 500V step command into a 100W load produces the response of Figure 30. Loop response on both edgesis clean, with the falling edge slightly underdamped. This slew asymmetry is typical of switching confi gurations, because the load and output capacitor determine negative slew rate. The wide range of possible loads mandates a compromise when setting frequency compensation. The falling edge could be made critically or even over damped, but response time for other conditions would suffer . The compensation used seems a reasonable compromise.Note 9: A circuit related to the one presented here appears in the L TC Application Note 18 (Figure 13). Its linear drive to the step-up DC/DC converter forces dissipation, limiting output power to about 15W . Similar restrictions apply to Figure 7 in Application Note 6.Figure 27. Figure 26’s Operating Waveforms at 500V Output into a 100W LoadFigure 28. Figure 26’s Operating Waveforms at 0.005V OutputFigure 29. Figure 26’s Output Noise at 500V into a 100W Load. Residue is Composed of Q1-Q2 Chopping Artifacts and T ransformer Related Ringing. DANGER! Lethal Potentials Present—See TextFigure 30. 500V Step Response with 100W Load (Photo Retouched for Clarity). DANGER! Lethal Potentials Present—See TextA = 50V/DIVB = 5A/DIVHORIZ = 10μs/DIVAN35 F27C = 50V/DIVD = 50V/DIVA = 5V/DIVB = 50mA/DIVHORIZ = 10μs/DIVAN35 F28C = 0.1V/DIVD = 0.1V/DIVA = 0.05V/DIV AC-COUPLED ON 500V LEVELHORIZ = 20μs/DIVAN35 F29A = 100V/DIVHORIZ = 50ms/DIVAN35 F30。
AE特效简介
1.55MM1.1 55m m Col or Gr ad(颜色渐变)1.2 55mm D efocu s (散焦)1.3 55m m Fau x Fli m(模仿胶片效果)1.455mmFluor escen t (荧光)1.5 55m m Fog(雾)1.6 55mm I nfra-red (在红色下面)1.7 55m m Mis t(薄雾)1.8 55mm ND G rad(渐变)1.9 55mm Ni ght V ision(夜视)1.10 55mm Sele ctive Soft Focu s(选择性的软焦点)1.11 55m m Ski n Smo other(外表面平整)1.12 55mm T int(偏色)1.13 55mm W arm/C ool(暖色/冷色)2.AEFla me(火焰)3.Bori s3.1 Bo ris F ire(火焰效果)3.2Boris FX 33.2.1 Bo ris A rtist’s Po ster(艺术海报)3.2.2 Bo ris B lur (模糊)3.2.3 Bori s Dir ectio nal B lur (方向模糊)3.2.4 Bo ris G aussi an Bl ur (高斯模糊)3.2.5 Bor is Un sharp Mask(锐利的遮罩)3.2.6 Bori s Bri ghtne ss-Co ntras t (亮度-对比度)3.2.7 Bo ris C olorBalan ce (颜色平衡)3.2.8 Bor is Co lor C orrec tion(颜色修正)3.2.9 B orisCompo site(合成)3.2.10 Bo ris C orrec t Sel ected Colo r (修改选择的颜色)3.2.11Boris Hue-Sat-L ightn ess (色调-饱和度-亮度)3.2.12 B orisInver t Sol arize(反转曝光)3.2.13 Bori s Lev els G amma(标准的伽马值)3.2.14 Bor is Mu ltiTo ne Mi x (多通道混合)3.2.15 Bo ris P oster ize (多色调分色)3.2.16Boris RGBBlend(RGB混和)3.2.17 Bor is Ti nt-Tr 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ouds(流动的云)3.2.47 B orisNoise Map(噪点地图)3.2.48 B orisAlpha Pixe l Noi se(通道像素噪点)3.2.49 B orisRGB E dges(RGB边缘)3.2.50Boris RGBPixel Nois e(RGB像素噪声)3.2.51 B orisScatt erize(模拟毛玻璃的效果)3.2.52 B orisSpray Pain t Noi se(喷漆噪点)3.2.53 Bor is Fl at 3D Text(扁平的三维字体[不支持中文])3.2.54Boris 3D T ext(三维字体[不支持中文])3.3 Bor is Co ntinu um3.3.1BC 3D Text(三维文字)3.3.2 B C Boo st Bl end(推进混合)3.3.3 BCBurnt Film(燃烧的电影)3.3.4BC Cl ouds(流动的云)3.3.5 BC Come t(彗星)3.3.6 BC Comp osite(合成)3.3.7 BCDVE(模拟三维效果)3.3.8 B C Fir e(火)3.3.9 BCJitte r(频谱曲线抖动)3.3.10 BC Loop er(循环)3.3.11BC Pa rticl e Sys tem(粒子系统)3.3.12 BC Post erize Time(相片时间)3.3.13BC Ra in(下雨)3.3.14BC Se quenc er(音序器)3.3.15 BC S now(下雪)3.3.16 BC S parks(火花)3.3.17 BC Star s(星星)3.3.18 B C Sup er Bl end(超级混合)3.3.19 BC Temp oralBlur(时间模糊)3.3.20 B C Tra ils(轨迹)3.3.21 BC V eloci ty Re map(速度测试图)3.3.22 B C Z S paceI(Z空间1)3.3.23 BC Z Spac e I I(Z空间2)4.Colo rmap(颜色地图)5.Compo siteWizar d5.1 CW Comp osite Colo r Mat cher(复合颜色匹配器)5.2 C W Del uxe E dge F inder(华丽的边缘查找器)5.3 CW D eluxe Edge Find er EZ(华丽的边缘查找器E Z)5.4 CW Deno iser(放射状处理)5.5 CWEdgeBlur(边缘模糊)5.6 CW E dge B lur E Z(边缘模糊EZ)5.7CW Ma tte F eathe r(剪影羽化)5.8 CW Matt e Fea therEZ(剪影羽化EZ)5.9 CW M atteFeath er Sh arp(剪影羽化锐利)5.10 CW Mira cle A lphaClean er(通道清洁)5.11CW Re-Matt er(重置剪影)5.12CW Sm oothScree n(光滑屏幕)5.13 C W Spi ll Ki ller(溢出杀手)5.14 CWSpill Kill er EZ(溢出杀手EZ)5.15CW Su per B lur(超级模糊)5.16 CW S uperCompo und B lur(超级混合模糊)5.17 CW Supe r Rac k Foc us(超级变焦)5.18CW Wi re/Ri g Zap per(线框/钻探器)5.19 CW Zone HLS(环绕HLS)6.Cono a(多种三维标准体)是一个简易三维插件,能制作一些简单的立方体、球体和锥体,并能附上简单的纹理. 7.Coyco re7.1 C ult E ffect s 1.57.1.1 CE 3D G lasse s (三维眼睛)7.1.2 CE B asicFill(基本填充)7.1.3 CE Cell Patt ern(蜂房图案)7.1.4 CEChang e Col or HL S(改变选择的颜色)7.1.5 CE Chan nelin g(渠道)7.1.6 CE Chec ker(棋盘格)7.1.7 CE C ircle(圆形)7.1.8 CEColor Comp osite(颜色合成)7.1.9 C E Col or Li nk(颜色链接)7.1.10 CEColor Pick er(颜色拾取)7.1.11 CEColor Soli d(颜色固化)7.1.12 CE C olors Quad(颜色四方格)7.1.13CE Di ffere nce(差异)7.1.14 CE F ireUp(火上)7.1.15 CE Grid(网格)7.1.16 CE Ligh tning(闪电)7.1.17 CE Magn ify(夸大效果)7.1.18 CE Nois e Alp ha(噪点通道)7.1.19 CENoise HLS(噪点HLS)7.1.20CE No ise H LS Au to(噪点HLS自动)7.1.21CE No ise T urbul ent(骚乱的噪波)7.1.22 C E Noi se Tu rbule nt II(骚乱的噪波2)7.1.23 CEOptic s Com pensa tion(光学补偿)7.1.24 C E Pai nt(绘画)7.1.25CE Ra dialShado w(放射状的投影)7.1.26 CE Roug hen E dges(让边缘变粗糙)7.1.27 CE T urbul ent D ispla ce(汹涌的置换)7.2CultEffec ts Xt ras 7.2.1 CE S et Ch annel(设置通道)7.2.2 C E Vie w Cha nnel(显示通道)8.Digie ffect s8.1 Di giEff ect A urori x V2.08.1.1 3D Lig hting 2(光线彩色浮雕)8.1.2 Ag edFil m 2(老电影的效果)8.1.3 B ulgix 2(类似于凸出的效果)8.1.4Chaot ic No ise 2(混乱的噪波)8.1.5Chaot ic Ra inbow 2(混乱的五彩缤纷)8.1.6 C olorSpotL ights 2(彩色聚光灯)8.1.7 Ear thqua ke 2(震动)8.1.8 Elec trofi eld 2(电磁感应)8.1.9 F litte r 2(碎屑)8.1.10 Frac tal N oise2(彩色不规则噪波2)8.1.11Infin ity W arp 2(无限扭曲)8.1.12Infin ity Z one 2(无限环绕)8.1.13Inter ferix 2(专用干扰图1)8.1.14 I nterp heroi d 2(专用干扰图2)8.1.15Inter phero n 2(专用干扰图2)8.1.16Light Zoom2(强光的纵深效果)8.1.17 N oiseBlend er 2(噪点搅拌机)8.1.18SoapF ilm 2(皂膜)8.1.19 Sp otLig hts 2(聚光灯)8.1.20 S trang e Neb ulae2(奇异的星云)8.1.21 Til os 2(阵列)8.1.22 Tur bulen t Flo w 2(湍流)8.1.23 Vide oLook 2(电视干扰信号)8.1.24 W arpoi d 2(拉伸效果)8.1.25 Wh irlix 2(旋转扭曲效果)8.1.26 W oodMa ker 2(木纹)8.2DigiE ffect Berz erk V1.5 8.2.1 Bliz zard(风雪)8.2.2 Bump Maker(制作凹凸贴图)8.2.3 Cont ouris t(轮廓线)8.2.4 *******lize r(结晶器)8.2.5 C ycloW arp(螺旋)8.2.6Edgex(边缘锐化)8.2.7 F ogBan k(浓雾)8.2.8 Gr avity Well(重力旋涡)8.2.9 La ser(激光器)8.2.10 New sprin t(新闻用纸)8.2.11 Nigh tBloo m(夜间华)8.2.12OilPa int(油画)8.2.13 Pear ls(珍珠)8.2.14Persp ectro n(特殊的扭曲)8.2.15 Rip ploid(荡起的波纹)8.2.16 Spin tron(怪异的扭曲)8.2.18StarF ield(飞舞的星星)8.2.19Still Noise(静态噪点)8.2.20VanGo ughis t(美术笔触)8.3 Ci ne Lo ok Fi lmres V1.18.3.1 DE Cine Look(胶片调色)8.3.2 DE Film Damag e(胶片处理)8.4 Ci nemot ion 8.4.1 DE A dapti ve No ise(适应的噪点)8.4.2 DE Band ing R educe r(条带还原)8.4.3DE Fi lm Mo tion(运动电影)8.4.4 DE Grai n Red ucer(颗粒还原)8.4.5 DE Inte rlace Alia singReduc er(交错产生器)8.4.6 DELette rbox(宽银幕产生器)8.4.7DE Se lecti ve HS B Noi se(选择HSB噪点)8.4.8 D E Sel ectiv e HSB Post erize(选择HS B多色调分色)8.4.9DE Se lecti ve RG B Noi se(选择RGB噪点)8.4.10DE Se lecti ve RG B Pos teriz e(选择R GB多色调分色)8.5 D eleri um8.5.1DE Bu bbles(泡沫)8.5.2 DECamer a Sha ke(摄像机抖动)8.5.3 DEChann el De lay(通道延迟)8.5.4 DECOP B lur(优化模糊)8.5.5 DEElect rical Arcs(闪电)8.5.6 DEFairy Dust(仙女的灰尘)8.5.7DE Fi lm Fl ash(影片闪烁)8.5.8 DEFire(火)8.5.9DE Fi reWor ks(火焰发射器)8.5.10 DE Flic ker a nd St robe(闪光灯)8.5.11 DE Flow Moti on(流动)8.5.12DE Fo g Fac tory(雾工厂)8.5.13 DE Fram ing G radie nts(画面渐变)8.5.14 DE Glow er(炽热体)8.5.15 DE G raysc aler(灰度处理)8.5.16 D E HLS Disp lace(HLS置换)8.5.17DE Hy per H armon izer(绚丽的彩带)8.5.18DE Le ns Fl ares(镜头光斑)8.5.19 D E Loo se Sp rocke ts(任意按链锯齿移动)8.5.20 DE M ultig radie nt(多极渐变)8.5.21 DEMuzzl e Fla sh(枪火)8.5.22DE Ne xus(连接点)8.5.23 DEPuffy Clou ds(膨胀的云)8.5.24 DERainFall(下雨)8.5.25 DERetin al Bl oom(网状张开)8.5.26 DE Sche matic Grid s(示意性网格)8.5.27 DEShowChann els(显示通道)8.5.28 DE Sket chist(变脏)8.5.29 DE Smok e(升起的烟)8.5.30 DE S now S torm(暴风雪)8.5.31 DE Sola rize(过度曝光)8.5.32 D E Spa rks(焰火)8.5.33 DE S pecul ar Li ghtin g(镜面高光)8.5.34 DE T hermo graph(热录像仪)8.5.35DE Tu rbule nt No ise(紊乱的噪波)8.5.36 D E Vid eo Ma lfunc tion(电视故障)8.5.37 D E Vis ual H armon izer(原子曲线)8.5.38 D E Wav e Dis place(波浪置换)9.Digi tal A narch y Ele ments9.1 Scr een T ext(屏幕文字)9.2TextGrid(文字网格)9.3 Text Matr ix(超级文字)10.D igita l Fil m Too ls10.1CS Co lor C orrec t(颜色修正)10.2 C S Com posit e(合成)10.3 CSDefoc us(散焦)10.4 CS Fast Blur(快速模糊)10.5 CS Fram e Ave rager(画面中和器)10.6 C S Gra in(增加颗粒)10.7CS Ho ldout Comp osite(持续合成)10.8 CS Ligh t Com posit e(灯光合成)10.9 C S Mat h Com posit e(数学合成)10.10CS Ma tte G enera tor(无光发生器)10.11 CS Matt e Rep air(剪影修理)10.12 CSNon-A dditi ve Mi x(非附加混合)10.13 CS P asteColor(粘贴颜色)10.14 C S Sel ectiv e Col or Co rrect(选择颜色修正)10.15 CS S elect ive S oft F ocus(选择软焦点)11.eFX Pro是一个模拟真实火焰和烟雾的粒子系统12.E volut ion 12.1 Card Danc e (卡片跳舞)12.2CardWipe(卡片翻转)12.3 Ca ustic s(焦散)12.4 Foa m (气泡)12.5 Mu ltipl ane(多图层变换)12.6 Rad io Sh ape(模拟无线电波的形状)12.7 Radi o Sta r(模拟星形无线电波)12.8 Wa ve Wo rld(波浪世界)13.Eye C andy13.1 Ant imatt er(反物质)13.2 C arve(倒角)13.3Chrom e(铬合金)13.4 Cu tout(挖剪图像)13.5 Fir e(火焰)13.6 Fur(毛发)13.7 Glas s(玻璃)13.8 Glo w(辉光)13.9 HSB Nois e(HSB躁点)13.10 Inne r Bev el(向内倒角)13.11 Jigg le(摇动)13.12 M otion Trai l(拖尾)13.13 Ou ter B evel(向外倒角)13.14 Pe rspec tiveShado w(透视投影)13.15Smoke(烟)13.16 Squi nt(重影)13.17 S tar(星形)13.18Swirl(旋涡)13.19 Wea ve(编织)14.Fil mFX 14.1 Colo r Tim ing(颜色调整)14.2 Film Stoc k(库存胶片)15.Fi nal E ffect s Com plete15.1 Fi nal E ffect s(简称F e)15.1.1 FE B all A ction(球状运动)15.1.2FE Bu bbles(泡沫)15.1.3 FE Colo r Off set(颜色位移)15.1.4 FE Comp osite(合成)15.1.5 FE FloMotio n(失真运动)15.1.6 FE G riddl er(矿筛)15.1.7FE Im age W ipe(图像擦除)15.1.8 FE Kale ida(发音体)15.1.9 FELens(透镜)15.1.10 FE Ligh t Bur st 2.5(灯光爆裂)15.1.11 FELight Swee p(扫光)15.1.12FE Pa ge Tu rn(翻页)15.1.13 FE P artic le Sy stems(粒子系统)15.1.14 FE P artic le Sy stems II(粒子系统2)15.1.15FE Pa rticl e Sys temsLE(粒子系统LE)15.1.16FE Pi xel P olly(像素剥离)15.1.17FE Ra dialScale Wipe(反射状的缩放擦拭)15.1.18 F E Rai n(下雨)15.1.19FE Sc ale W ipe(缩放擦除)15.1.20 F E Sca tteri ze(分散)15.1.21 FE S lant(倾斜)15.1.22 FE Slan t Mat te(倾斜剪影)15.1.23 FE Snow(下雪)15.1.24 F E Sph ere(球体)15.1.25 FEStarBurst(星爆式)15.1.26FE Th resho ld(阀值)15.1.27 FE T hresh old R GB(RG B阀值)15.1.28 F E Til er(瓦盖)15.1.29 FE T wiste r(缠绕)15.2 Nex t Eff ect(简称Ne)15.2.1 FE Adva nced3D(高级三维)15.2.2 FEBendIt(弯曲)15.2.3FE Cy linde r(圆柱体)15.2.4FE Dr izzle(毛毛雨)15.2.5 F E For ce Mo tionBlur(强大的运动模糊)15.2.6 FEHair(毛发)15.2.7 FELight Rays(体积光)15.2.8 F E Mr. Smoo thie(圆滑)15.2.9 FEPower Pin(透视点)15.2.10 F E Rep eTile(放射状模糊)15.2.11 FESimpl e Wir e Rem oval(擦除金属丝)15.2.12 FE W ide T ime(放慢)15.3 S tudio Effe cts(简称Se)15.3.1 FE Alph a Map(Alph a贴图)15.3.2 FE Bend er(弯曲)15.3.3FE Bl obbyl ize(滴状斑点)15.3.4 FE Burn Film(燃烧的胶片)15.3.5 FE G lass(玻璃)15.3.6 FEGlass Wipe(擦拭玻璃)15.3.7FE Gl ue Gu n(喷胶枪)15.3.8FE Gr id Wi pe(删格擦拭)15.3.9 FEJaws(狭口)15.3.10 FE Ligh t Wip e(扫光)15.3.11FE Mr. Mer cury(水银先生)15.3.12FE Pa rticl e Wor ld(粒子世界)15.3.13 FE Ripp le Pu lse(涟漪发生器)15.3.14FE Sm ear(涂污)15.3.15 FESplit(切开)15.3.16 F E Spo tligh t(聚光灯)15.3.17 FE T ime B lend(时间混合)15.3.18FE Ti me Bl end F X(时间混合FX)15.3.19 F E Ton er(调色剂)16.Fo rge F reeFo rmF orgeFreeForm(自由变换)是一款用来制作自由变换效果的插件,为制作图形变形效果提供了极大的方便。
Edexcel BTEC Level 3 Nationals 发行版2-2011 电子设备维修与修复
Aim and purposeThe aim of this unit is to provide the learner with the knowledge, understanding and skills required to carry out service and repair on electrical systems within land-based equipment. The learner will need to ensure they comply with current legislation and guidelines to complete this unit. This unit aims to introduce learners to skills and knowledge in the service and repair of electrical systems and how these can be applied in practice. It is designed for learners in centre-based settings looking to progress into the sector or onto further/ higher education.Unit introductionIn this unit learners will develop an understanding of the fundamentals of electrical maintenance and the knowledge and skills required when carrying out electrical maintenance activities. In carrying out these activities learners will developing knowledge and skills in selecting fault-finding techniques and diagnose faults. Learners will also develop the skills needed to dismantling, reassemble and carry out routine maintenance on electrical equipment and circuits such as motors and control systems.Learners will need to demonstrate an understanding of safe working practices when carrying out fault location and maintenance activities and take the necessary safeguards to protect their own safety and that of others in the workplace.Learning outcomesOn completion of this unit a learner should:1 Be able to perform service and repair operations on electrical systems and their components used inland-based equipment2 Know the construction, function and operation of electrical systems and circuits and their components.Unit content1Be able to perform service and repair operations on electrical systems and their components used in land-based equipmentElectrical risks: welding, short circuit, battery open circuit, overcharging, reverse polarityDismantling and assembly: use of manufacturers’ service manuals; parts lists and drawings; approved working proceduresRemoval and replacement: eg damaged wires and cables, electrical units/components, termination and connection, soldering and de-soldering; appropriate tools and equipment; approved working procedures Inspection and maintenance routines: maintenance routines eg power supplies and/or batteries, onelectrical equipment and circuit components, devices and systems, wiring harnesses, connectors and connections, earthing; inspection and functional testing eg voltage, current, continuity, resistance, battery, condition, continuity, wear, overheating, missing or loose fittings, carrying out adjustments as necessary;recording of condition; the use of maintenance manuals and documentationTypes of instruments: eg multimeter, light meter, Power ProbeFault diagnosis techniques: eg use of fault-finding aids, functional charts, diagrams, trouble shooting charts, six point (collect evidence, analyse evidence, locate fault, determine and remove cause, rectify fault, check system), half split, input/output, unit substitution, emergent sequence, component data sheets, operation and maintenance manuals, software-based records and data, visual examination, unit substitution, fault/ repair reporting, final test handover proceduresRepairs to manufacturers’ specifications: eg starting systems, charging systems, safety and/or circuitprotection systems, ignition systems, spark ignition systems, lighting systems, instrumentation systems, ancillary systemsProblem: eg short circuit, open circuit, high resistance, intermittent, partial failure/out-of-specification output, complete breakdownsReport findings: eg scheduled maintenance report, corrective maintenance report, other company-specific report, job cards, maintenance log2Know the construction, function and operation of electrical systems and circuits and their componentsSystem components: electrical supply eg cables and connectors, batteries; lead acid, gel, maintenance free, dry cell; transformers, rectifiers, contactors; circuit components eg capacitors, circuit boards, switches, solenoids, thermistors, devices eg overload protection device, relays, sensors; use of maker’s catalogue or database for selecting replacementsIdentification of components and function: series and parallel connections, power supply and battery types, circuit protect devices, fixed and/or variable resistors, diodes, relays switches, wire types and sizes, electrical consumersIdentification and interpretation of circuit diagrams to include the following: electrical component symbols, colour coding, wire identification and sizing, series and parallel connections; alternating and direct current and the common voltages in usePrinciples, construction and function of electrical circuits and their component types: starter circuits eginertia, pre-engaged; cold start circuits eg heat start, safety start, ignition circuits; charging circuits eg alternators, rectifiers, lighting circuits eg indicators, brake lights, side, head, dip, marker lights, work lights;Instrumentation circuits eg fuel, temperature, tachometer, hour meter. spark ignition circuits eg spark generation; ancillary circuits eg wiper motors, stop circuits, ventilation, horn, switches, actuators; safety and/or circuit protection circuits eg battery isolation safety isolation, fuses and fuseable links, thermal switches, over – under voltage switching, relays, RCCB, earth bonding, double insulationAssessment and grading criteriaIn order to pass this unit, the evidence that the learner presents for assessment needs to demonstrate that they can meet all the learning outcomes for the unit. The assessment criteria for a pass grade describe the level of achievement required to pass this unit.Assessment and grading criteriaTo achieve a pass grade the evidence must show that the learner is able to:To achieve a merit grade theevidence must show that, inaddition to the pass criteria,the learner is able to:To achieve a distinction gradethe evidence must show that,in addition to the pass andmerit criteria, the learner isable to:P1identify electrical circuitsand components andtheir functions fromwiring diagrams and visualrecognition[IE, CT]M1explain the relationshipbetween component faultsand the malfunction of a givenelectrical systemD1compare and contrast twofault diagnosis techniqueswhen carrying outmaintenance work on anelectrical system.P2perform tests usingequipment and practicesto measure and verifythe correct operation ofelectrical systems and theircomponents[SM, IE, TW]P3identify and rectify faultsin electrical systems andcomponents[RL, EP]P4maintain the integrity ofelectrical systems[EP, IE]P5remove, dismantle, rectify faults, repair and reinstateelectrical components andcircuits to manufacturer’sspecifications and standards[EP, IE, TW]Assessment and grading criteriaTo achieve a pass grade the evidence must show that the learner is able to:To achieve a merit grade theevidence must show that, inaddition to the pass criteria,the learner is able to:To achieve a distinction gradethe evidence must show that,in addition to the pass andmerit criteria, the learner isable to:P6identify and interpretelectrical circuit diagrams[IE]M2explain the importanceof applying safe workingpractices when carrying outmaintenance on an electricalsystem.P7summarise Ohm’s law, itsapplication and principles[IE]P8compare the specification,safe maintenance andcharging of different types ofbattery[RL,IE,TW,CT]P9describe the principles,construction and function ofelectrical circuits and theircomponents[CT]P10describe how to remove,dismantle, test, verify, repairand reinstate electrical circuitsand their components[CT, RL]P11outline risks posed toelectrical systems andcomponents by otheractivities or incidents.[IE, RL, SM, EP CT]PLTS: This summary references where applicable in the pass criteria, in the square brackets, the elements of the personal, learning and thinking skills. It identifies opportunities for learners to demonstrate effective application of the referenced elements of the skills.Key IE – independent enquirersCT – creative thinkers RL – reflective learnersTW – team workersSM – self-managersEP – effective participatorsEssential guidance for tutorsDeliveryAll centres must comply with the requirements of relevant, current legislation and codes of practice the Prevention of Accidents to Children in Agriculture Regulations 1998. Learners must be made aware of, and have access to, relevant health and safety legislation and know the importance of the use of risk assessments appropriate to each situation. Appropriate risk assessments must precede all practical machinery activities and learners must work in a safe manner at all times when using equipment or working with machinery. Learners must be supervised at all times and tutors must not ask learners to undertake tasks that are beyond their physical capabilities.Delivery of this unit will involve practical assessments, written assessment, visits to suitable collections and will link to industrial experience placements.The unit provides an opportunity for learners to work in teams or groups when diagnosing component or system faults. Delivery of this unit should focus on learners developing diagnostic and practical skills, together with an understanding of electrical components and systems maintenance.The learning outcomes are ordered logically and it would be reasonable to develop them sequentially throughout the unit. In this way, learners will be able to apply health and safety system and component operation to diagnostic, testing and maintenance techniques. All learning outcomes suit to a practical approach rather than too much time spent in theory lessons. For example, a short introduction to a component (or range of components), the function of the component within the larger system, the tools necessary to carry out the maintenance task together with any safety considerations, followed by practice. Learners need a broad overview of the different electrical components and systems so they can select and apply the correct maintenance, diagnostic and testing techniquesLearners will need to ensure they comply with current legislation and guidelines to complete this unit. Evidence may be collected from well-planned investigative assignments or reports of workshop activities. Evidence can be accumulated through learners building up a portfolio from investigations, case studies and maintenance operations through a tutor-led series of assignments, realistic maintenance exercises and tests. Outline learning planThe outline learning plan has been included in this unit as guidance and can be used in conjunction with the programme of suggested assignments.The outline learning plan gives an indication of the volume of learning it would take the average learner to achieve the learning outcomes. It is indicative and is one way of achieving the credit value. Learning time should address all learning (including assessment) relevant to the learning outcomes, regardless of where, when and how the learning has taken place.Topic and suggested assignments/activities and/assessmentElectrical basics: include Ohm’s law, what is needed in a circuit, series and parallel circuits.Assignment 1: Electrical Health and Safety (P10, P11, M2)Assignment 2: Maintenance of Electrical Equipment (P1, P2, P4, P5)practical activities to cover unit content as required.Topic and suggested assignments/activities and/assessmentAssignment 3: Electrical Theory (P6, P7, P9)recognising components, working with circuit diagrams, understanding ohm’s law and its application. Assignment 4: Batteries (P8)how batteries work, types of battery, battery application, the future of battery technology.Assignment 5: Electrical Fault Finding (P3, M1, D1)practical assessment activities that capture evident as described in unit content.Unit review.AssessmentFor P1, P2, P3, P4 and P5 learners are required to demonstrate practices and use of equipment to identify, measure and rectify faults in electrical systems and their components/circuits. All practical tasks and tutor feedback needs to be recorded using appropriate documentation.For P6, P7, P8, P9, P10 and P11, learners must provide information relating to operational task procedures relating to the service and repair of electrical systems. Evidence may be a by way of project assignment, observed practical test or pictorial presentation with notes using appropriate software, slides or OHPs.For M1, M2 and D1, learners must provide detailed information on electrical fault diagnosis, malfunctions and safe working practices. Evidence could be in the form of a report, test or presentation.Programme of suggested assignmentsThe following table shows a programme of suggested assignments that cover the pass, merit and distinction criteria in the grading grid. This is for guidance and it is recommended that centres either write their own assignments or adapt any Edexcel assignments to meet local needs and resources.Criteria covered Assignment title Scenario Assessment methodP10, P11, M2Electrical Healthand Safety Electrics can be dangerous and workingon vehicle electrics can damage thecomponents beyond repair. Look atthe risks involved with electrical system maintenance and repair.Assignment.P1, P2, P4, P5Maintenanceof ElectricalEquipment As with other systems, electrical systemsneed maintenance and repair. Carryout tests, maintenance and repairs toelectrical systems and components.Portfolio of evidence.P6, P7, P9Electrical Theory Electrical systems can become verycomplex. It is essential that youunderstand circuit diagrams and thetheory of electric systems.Open book test.P8Batteries Though vehicle electrics have changedrastically over a short period of time,the same cannot be said for the humblebattery. Investigate the different types ofvehicle battery with a view to the future.Investigative report.P3, M1, D1Electrical FaultFinding Quick fault diagnosis will saveconsiderable time, effort and expense.Use fault-finding techniques to identifysystem faults and rectify them.Practical assessment.Links to National Occupational Standards, other BTEC units, other BTEC qualifi cations and other relevant units and qualifi cationsThis unit forms part of the BTEC land-based sector suite. This unit has particular links with: Level 2 Level 3LEO22 Service and Repair Electrical Systems on Land-based Equipment Undertake and Review Work-related Experience in the land-based IndustriesEssential resourcesCentres delivering this unit must have access to land-based vehicle standard components and systems, testing instruments and rigs. This unit relies heavily on the learner being able to investigate the manufactured specification of components and service manuals.Employer engagement and vocational contextsVisits to vehicle electric specialist firms in relation to fault finding would be of benefit to learners as well as visitsto manufacturing organisations or similar with a focus on electrical components, their installation and service requirements. Learners will be made aware of the vast range and scope of electrical components and sensors used in the land-based engineering sector.Indicative reading for learnersT extbooksHealth and Safety Executive – Essentials of Health & Safety at Work (HSE, 1995) ISBN 071760716X Adams J – Electrical Safety: A Guide to the Causes and Prevention of Electrical Hazards(Institution of Electrical Engineers, 1994) ISBN 085296806XWebsites RS is Europe’s leading distributor of electronic,electrical and industrial components. is an online community dedicated toproviding visitors the ability to research, share, anddiscuss solutions and tips for completing day-to-daytasks and projects. Health and Safety ExecutiveDelivery of personal, learning and thinking skills (PLTS)The following table identifies the PLTS opportunities that have been included within the assessment criteria of this unit:Skill When learners are …Independent enquirers carrying out fault finding electrical systemsCreative thinkers carrying out fault finding on electrical systemsReflective learners making comparisons between components and systemsT eam workers gathering test dataSelf-managers investigating faultsEffective participators gathering test data.Although PLTS opportunities are identified within this unit as an inherent part of the assessment criteria, there are further opportunities to develop a range of PLTS through various approaches to teaching and learning. Skill When learners are …Independent enquirers planning and carrying out research activities related to the unitevaluating and carrying out extended thinkingCreative thinkers asking questions to extend their thinking during lectures and practical sessionstrying out alternatives or new solutionsReflective learners identifying opportunities for their own achievementsT eam workers assisting in group activitiesSelf-managers setting own targets for accurate completion of workasking for assistanceEffective participators encouraging debate.Functional Skills – Level 2Skill When learners are …ICT – Use ICT systemsusing ICT-based systems to define component functionality Select, interact with and use ICT systemsindependently for a complex task to meet avariety of needsUse ICT to effectively plan work andevaluate the effectiveness of the ICT systemthey have usedManage information storage to enableefficient retrievalFollow and understand the need for safetyand security practicesT roubleshootSelect and use ICT to communicate andexchange information safely, responsibly andeffectively including storage of messages andcontact listsMathematicsdescribing Ohm’s law and its applicationUnderstand routine and non-routineproblems in a wide range of familiar andunfamiliar contexts and situationsIdentify the situation or problem and themathematical methods needed to tackle itusing electrical fault-finding techniquesSelect and apply a range of skills to findsolutionsEnglishdiscussing fault-finding techniques.Speaking and listening – make a range ofcontributions to discussions and makeeffective presentations in a wide range ofcontextsReading – compare, select, read andunderstand texts and use them to gatherinformation, ideas, arguments and opinions。
multisim的文本文件的函数 -回复
multisim的文本文件的函数-回复“Multisim的文本文件的函数”是指在Multisim软件中使用的一系列函数,用于读取、写入和处理文本文件。
Multisim是一款强大的电子电路模拟软件,它集成了多种功能,包括电路设计、仿真和测试。
通过使用文本文件的函数,用户可以方便地读取和处理电路设计过程中所产生的数据。
本文将逐步介绍Multisim中文本文件的函数及其用法,以帮助读者更好地理解和应用这些函数。
首先,我们需要了解Multisim软件中文本文件的基本概念。
文本文件是一种常用的数据存储格式,它以文本的形式保存数据,以便于人们阅读和编辑。
Multisim支持的文本文件类型包括txt、csv等。
通过使用Multisim的文本文件的函数,我们可以从文本文件中读取数据,或者将数据写入到文本文件中。
Multisim中的文本文件函数主要有以下几个常用的函数:FileOpen、FileLoad、FileSave、File readline、FileWriteLine等。
我们将逐一介绍这些函数及其用法。
首先是FileOpen函数。
这个函数用于打开一个文本文件,并返回一个文件对象。
它的语法格式如下:FileOpen(filename, mode)其中,filename是要打开的文件名,mode是打开文件的模式,可以是“r”表示读取模式,或者是“w”表示写入模式。
示例如下:file = FileOpen("data.txt", "r")这个示例会打开一个名为data.txt的文本文件,并返回一个文件对象。
接下来是FileLoad函数。
这个函数用于从文本文件中加载数据。
它的语法格式如下:FileLoad(file)其中,file是之前使用FileOpen函数打开的文件对象。
示例如下:data = FileLoad(file)这个示例会将文件中的数据加载到变量data中。
然后是FileSave函数。
EN301489-3中文资料(List Unclassifed)中文数据手册「EasyDatasheet - 矽搜」
应用
EPOS设备,条码扫描器
数据记录器 工业遥测和遥控 在建设环境监测和控制 高端安全和火灾报警器
DGPS系统 车辆数据上载/下载
技术摘要
尺寸:33×23×10毫米 工作频率:151.300MHz 电源电压范围:100mW发射器3.8V - 15V,接收器:3.0V-15V 电源电压范围:10毫瓦发射机3.0V - 15V,接收器:3.0V-15V 消耗电流:80毫安发送@ 100mW,8毫安接收 数据比特率:10kbps最大值. (标准模块) RSSI输出为-60dBm范围 10kbps,-120dBm灵敏度(12 dB信纳)
typ.
max. units notes
-120
dBm
-115
dBm
-127
dBm
60
dB
kHz
85
dB
60
dB
70
dB
2
65
dB
-70
dBm
3
-60
dBm
3
5
kHz
400
mV P-P
7
0.8
V
TBD
%
TBD
pF
TBD
ms
2
10
ms
TBD
ms
TBD
ms
0.1 ms
8
50
80
%
8
侧视图(通过CAN)
侧视图(带CAN)
10 mm
RF GND 1 天线2 RF GND 3
4 5 无引脚 6 7 8 0电压 9
顶视图(不能够)
30.48 mm 33 mm
图 4: BiM1引 脚 和 维 43mm
18 0电压 17 Vcc 16 RX选择 15 TX选择 14 TXD 13 AF 12 RXD 11 RSSI 10 0电压
Pearson BTEC Level 3 Nationals (QCF) 信息技术系统分析与设计规范
Unit 11: Systems Analysis and DesignUnit code: F/601/7278QCF Level 3: BTEC NationalCredit value: 10Guided learning hours: 60Aim and purposeThe aim of this unit is to enable learners to gain an understanding of the principles of systems analysis and equip them with the skills to analyse business requirements and design solutions to meet business needs.Unit introductionSystems analysis informs the development of large or small, but often complex, systems and the interactions within those systems. It provides structured processes that help to ensure designs are reliable. In this unit, learners will gain an understanding of the principles and stages involved in systems analysis and the associated documentation involved in both the analysis and design stages. One key stage involves the determination of requirements and the writing of the requirements specification. Clear statements and understanding of the requirements are essential to ensuring that an appropriate solution is designed. In addition, the specification will provide the basis for later testing and evaluation.The unit looks at why organisations undertake systems analysis as well as the benefits of carrying out such a formal process. A wide variety of methodologies are used, however they are all based on similar fundamental principles.Learners will become familiar with a limited number of lifecycle models and the associated terminology involved in the analysis and investigation of a system.Learners will develop a detailed knowledge and understanding of different methodologies and their benefits and uses in particular situations.It is expected that learners will undertake an actual systems analysis and design activity. It is not expected, however, that learners will create the system or test it as part of this unit. Other units can be linked to this unit to carry through the design work to the implementation stage.Learning outcomesOn completion of this unit a learner should:1 Understand the principles of systems analysis and design2 Be able to carry out a structured analysis of business systems requirements3 Be able to design business systems solutions.Unit content1 Understand the principles of systems analysis and designPrinciples: development lifecycle models; developmental tools and techniques; key driversDevelopment lifecycle models: Waterfall; other eg Spiral, Rapid Applications Development (RAD); benefits;stages eg initiation and feasibility, investigation, requirements analysis and specification, design (logical and physical), build systems, testing, implementation, maintenanceDevelopmental tools and techniques: any contemporary methodology for systems analysis and design;typical eg activity diagrams, dataflow diagrams, computer-aided software engineering tools (CASE) Key drivers: business need, eg need for growth, company acquisition, need to increase productivity, legal requirementsStructured analysis: benefits eg reduced risk of projects running over-budget or over-time, good quality software that meets requirements, manageable projects, maintainable systems and code, resilient systems2Be able to carry out a structured analysis of business systems requirements Investigation: techniques eg interview, questionnaire, meeting, observation, document analysis, data analysis; sensitivity in collecting information and observing individuals at workAnalysis: as related to the chosen methodology;cost benefit analysisRequirements specification: contents eg scope, inputs, outputs, processes, costs and benefits,recommendations, alternative solutions3 Be able to design business systems solutionsDesign: inputs and outputs eg screens and report design; data eg data flow diagrams, data dictionaries, entity relationship diagrams; process descriptors eg decision tables, flow charts, structured English Constraints: on the design eg costs, organisational policies, timescale, legacy systems, availablehardware platformsAssessment and grading criteriaIn order to pass this unit, the evidence that the learner presents for assessment needs to demonstrate that they can meet all the learning outcomes for the unit. The assessment criteria for a pass grade describe the level of achievement required to pass this unit.PLTS: This summary references where applicable, in the square brackets, the elements of the personal, learning and thinking skills applicable in the pass criteria. It identifies opportunities for learners to demonstrate effective application of the referenced elements of the skills.Essential guidance for tutorsDeliveryEmphasis should be placed on developing learners to understand the role and principles of systems analysis and design, including the creation of clear documentation and the reasons behind the development of lifecycle methodologies. Systems analysis is a hard concept for learners to grasp and without an understanding of why it is necessary, for example to carry out a cost benefit analysis or produce a data flow diagram; learning can become unrelated and ‘difficult’.Unless the centre has access to a variety of employers who can provide opportunities and information that can be used for assessment purposes, it is likely that much of the learning will be based on case studies. Where possible, case studies should be detailed and learners should be able to pose questions that allow them to gain further insights and access the higher grades.A ‘bite size’ approach could work well, although a general overview of the whole process should be used to introduce the subject. The individual elements of the systems lifecycle can then be covered. Some theory about different models and methodologies needs to be included.Learners will need to practise for all stages and a sufficient amount of time should be allocated. While the stages beyond design should be covered as outlined in the unit content, these elements are not assessed. Assessment of building and testing systems occurs in other units. Linking this unit to others such as Unit 18: Database Design could aid teaching and learning and give learners a more holistic experience.Outline learning planThe outline learning plan has been included in this unit as guidance and can be used in conjunction with the programme of suggested assignments.The outline learning plan demonstrates one way in planning the delivery and assessment of this unit.AssessmentIt is suggested that this unit is assessed using three assignments as summarised in the Programme of suggested assignments table.Learners will need a scenario or case study detailing an organisation’s (real or invented) activities. It is important that the scenario is as broad as possible to enable learners to meet all the assessment criteria. If at all feasible it would be beneficial for them to carry out their own research with a suitable organisation. The scenario suggested here is that of a small delivery business whose database system is outdated and staff have reverted to semi-manual systems. Deliveries are being delayed or, worse, completely missed. The business has employed a systems analyst to investigate the requirement and design a system to meet these needs.Suggested Assignment 1 – What Is Systems Analysis?The suggested scenario for this theoretical element of the assessment is a presentation to a group of new BTEC IT learners to introduce the subject of systems analysis. Learners need not deliver the presentation, it may be produced as a self-running or interactive presentation, as long as the content is clear and sufficient and meets the grading criteria.P1 requires an explanation of the principles of systems analysis. The unit content will inform the content. For P2, learners need only outline the stages of one development lifecycle but for M1, they must consider other models and why different models are used. This should be supported by examples.In explaining the benefits of systems analysis for P3, learners should start with the key drivers and use the unit content as a guide.Suggested Assignment 2 – What Do We Need?For P4, it is expected that learners will have used appropriate techniques to gather the informationthey need to produce a requirements specification. A scenario that allows for the gathering of multiple responses (eg a customer or staff survey) would enable learners to develop questionnaires as well as using interviews. Evidence can be in the form of witness statements, interview notes and completed questionnaires.P5 is the requirements specification. This will contain elements as appropriate to the chosen methodology and must give a clear picture of the inputs, outputs, processes, scope and constraints of the system requirement, with a recommended solution.For M2, alternative solutions should be suggested with valid reasons for their inclusion.For D1, learners should include an analysis of costs and benefits. This does not need to include precise costs but all elements that should be factored into a cost benefit analysis must be included.Suggested Assignment 3 – And the Solution Is …Following the requirements analysis, learners must now produce detailed design documentation. Again this will depend on the methodology used and may include, for example, data flow diagrams, ERDs, top-down design, structured English. For P6, it should be clear from the documentation how a basic solution would be implemented.For M3, there should be an explanation of any constraints on the system design and for D2, learners should have worked independently, and produced thorough and detailed documentation.Programme of suggested assignmentsThe table below shows a programme of suggested assignments that cover the pass, merit and distinction criteria in the assessment and grading grid. This is for guidance and it is recommended that centres either write their own assignments or adapt any Pearson assignments to meet local needs and resources.Links to other BTEC unitsThis unit forms part of the BTEC in IT sector suite. This unit has particular links with the following unit titles in the IT suite:Essential resourcesLearners will need access to industry-standard software, plus hardware capable of running the software (including a printer).Delivery of personal, learning and thinking skillsThe table below identifies the opportunities for personal, learning and thinking skills (PLTS) that have been included within the pass assessment criteria of this unit.Although PLTS are identified within this unit as an inherent part of the assessment criteria, there are further opportunities to develop a range of PLTS through various approaches to teaching and learning.Functional Skills – Level 2。
matlab 指定区域nc变量格点数 -回复
matlab 指定区域nc变量格点数-回复Matlab是一种功能强大的数值计算和数据分析工具,它可以处理各种类型的数据,包括NetCDF(Network Common Data Form)数据格式。
NetCDF是一种用于存储科学数据的文件格式,经常用于气候、天气模拟、地球科学和其他领域的数据存储和分析。
在处理NetCDF数据时,有时需要指定特定区域的网格点,以便进行进一步的分析和计算。
本文将介绍如何在Matlab中指定区域的NetCDF变量格点数,并提供一步一步的操作指南。
在开始之前,首先确保你已经安装了Matlab软件,并且具备基本的Matlab编程基础。
如果你还没有准备好这些,可以先学习Matlab的基本知识和语法。
第一步:加载NetCDF数据首先,我们需要加载NetCDF数据文件。
在Matlab中,可以使用ncread 函数来读取NetCDF文件中的变量。
语法如下:data = ncread(filename, varname)其中,filename是NetCDF文件的路径和文件名,varname是要读取的变量名。
该函数将返回一个多维数组,其中包含了指定变量的全部数据。
第二步:查看NetCDF数据的维度信息在指定区域的网格点数之前,我们需要先了解NetCDF数据的维度信息。
可以使用ncinfo函数来查看NetCDF文件的信息。
语法如下:info = ncinfo(filename)该函数将返回一个结构体数组,其中包含了NetCDF文件的详细信息,包括变量和维度等。
我们可以通过查看维度信息来确定要指定的区域。
对于二维数据(如经纬度数据),通常会有两个维度,分别表示经度和纬度。
可以通过info.Dimensions来获取维度信息,其中包含了维度的名称和长度。
第三步:选择指定区域的网格点数一般情况下,我们可以通过指定经纬度范围来选择区域。
假设我们要选择一个矩形区域,其经纬度范围分别为[lon_min, lon_max]和[lat_min,lat_max]。
新概念三第1课课件p
NCE3LESS0N1Made by EllaWordsPuma「pjuma]用于进行时)看见;看出;注意到;发现我终于在人群中看见了我的朋友.邻居们发现有烟从这所房子里冒出来。
没有人留意到那是一支假枪。
我很快就看出错误所在了。
(对比赛对手)让子,让步我们让对手两个球。
满是…斑点他的衬衣上满是油点。
同义词:find:强调发现的结果find out:查出事实真相discover:做出重大发现notice:注意到observe:观察watch:观察语动中的人或画面Spot[spot]spot.他当场就回答了那个问题。
当场进行的违章停车罚款处罚minutes.几分钟之内辆救护车便赶到现场心现场才艮道•原地跑步是一种很好的锻炼口采访者的问题使他很下不来台Evidence|'evidans|根据;证明;证据你有证据支持这种说法吗?房间里有搏斗过的痕迹(法庭证据,证词,人证,物证我被要求出庭作证。
显眼;显而易见•在今天的示威集会上警察随处可见。
accumulate |ekju:mj9leit|积累;积聚books.我好像已经收集了很多书。
fortune.她投资精明,积累了一笔财富2.(数量)渐增长•债务开始增加口|9(kju:mj9'leijn|财富的积累有毒化学物质的积聚[___一I _|^zwwwvwwGather vt.聚集,把某人召集在某处——The teacher gathered his students in the classCollect vt.搜集,采集——Do you collect stamps?Yes,I collect stamps as iny hobby. Assemble v.集合,集会/装配——A large number of people assemble on the square.Hoard vt.大量的储存(—hoard up u store up储藏)——The squirrel hoards up nuts for the cold winteramass vt.积聚(主要用于诗歌和文学作品)——The clouds amassed above the hills.oblige la'blaid^l(以法律、义务等)强迫,迫使法律规定父母必须送子女入学白我不得不请他们吃饭。
新概念第一册Lesson83-84共70页高教书苑
Why?
The room is very untidy. Because they are
packing their suitcase.
3. What are Carol and Tom going to do?
They are going to have a holiday.
4. When are they going to leave?
↓
have是助动词,无实义
高级教育
35
❖ 否定形式:
❖ hasn't/haven't + 动词的过去分词
❖ 疑问形式:
❖ 把 has/have 提前 ❖ I have had dinner. ❖ 否:I haven‘t had dinner. ❖ 疑:Have you had dinner? ❖ 肯:Yes,I have./ ❖ 否:No,I haven't.
高级教育
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2. 谈论过去发生的某事,但对现在造 成了影响
e.g. She has broken her arm, so she can’t play basketball. 她伤了她的胳膊, 所以她不能打篮球 了.
高级教育
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3. 过去开始的某事,现在还在继续.
e.g. He has lived in China for 20 years. 他已经在中国住了20年了. He has lived in China since 1993.
❖ TOM: Let's go into the living room, Carol.
❖
We can have 高o级u教r育coffee there.
25
❖ CAROL: Excuse the mess, Sam.
sublime text 3 default filetype -回复
sublime text 3 default filetype -回复这篇文章将一步一步回答关于Sublime Text 3默认文件类型的问题。
Sublime Text 3是一种流行的文本编辑器,常用于编写代码、编辑文本文件和进行日常写作。
它的一个重要特性是可以通过设置默认文件类型来自动将文件识别为特定的编程语言或标记语言。
在默认设置中,Sublime Text将根据文件的扩展名来确定文件类型。
但有时候,你可能希望手动指定文件类型,或者修改默认文件类型的映射。
首先,让我们了解如何通过扩展名来自动识别文件类型。
在Sublime Text 3中,打开任何你想编辑的文件,然后点击菜单栏上的View(视图)选项。
在View下拉菜单中,你将发现一个Syntax(语法)选项,将鼠标悬停在上面,会弹出一个子菜单,显示所有可用的语法。
点击适合你当前文件类型的语法选项,Sublime Text即会自动将该文件类型设置为默认语法。
例如,如果你正在编辑一个Python文件,点击"Python"选项,Sublime Text 将自动切换到Python语法,并为你提供相应的代码高亮和自动补全功能。
如果你发现Sublime Text未能正确识别文件类型,或者你想手动指定文件类型,你可以按照以下步骤进行设置。
首先,打开一个文件,然后点击菜单栏中的View(视图)选项。
在View下拉菜单中,选择Syntax(语法)选项,然后移动鼠标光标到最底部的"Open all with current extension as…"(将当前扩展名的所有文件打开为...)子菜单。
再次移动鼠标光标,会弹出一个子菜单,显示与你当前文件扩展名匹配的语法选项。
选择适合你当前文件类型的语法选项,Sublime Text会将该文件类型设置为默认语法,并将所有具有相同扩展名的文件与该语法关联。
另一种方法是通过修改Sublime Text的设置文件来自定义默认文件类型映射。
Schneider Electric M340 BMXART0814 产品数据册说明书
T h e i n f o r m a t i o n p r o v i d e d i n t h i s d o c u m e n t a t i o n c o n t a i n s g e n e r a l d e s c r i p t i o n s a n d /o r t e c h n i c a l c h a r a c t e r i s t i c s o f t h e p e r f o r m a n c e o f t h e p r o d u c t s c o n t a i n e d h e r e i n .T h i s d o c u m e n t a t i o n i s n o t i n t e n d e d a s a s u b s t i t u t e f o r a n d i s n o t t o b e u s e d f o r d e t e r m i n i n g s u i t a b i l i t y o r r e l i a b i l i t y o f t h e s e p r o d u c t s f o r s p e c i f i c u s e r a p p l i c a t i o n s .I t i s t h e d u t y o f a n y s u c h u s e r o r i n t e g r a t o r t o p e r f o r m t h e a p p r o p r i a t e a n d c o m p l e t e r i s k a n a l y s i s , e v a l u a t i o n a n d t e s t i n g o f t h e p r o d u c t s w i t h r e s p e c t t o t h e r e l e v a n t s p e c i f i c a p p l i c a t i o n o r u s e t h e r e o f .N e i t h e r S c h n e i d e r E l e c t r i c I n d u s t r i e s S A S n o r a n y o f i t s a f f i l i a t e s o r s u b s i d i a r i e s s h a l l b e r e s p o n s i b l e o r l i a b l e f o r m i s u s e o f t h e i n f o r m a t i o n c o n t a i n e d h e r e i n .Product data sheetCharacteristicsBMXART0814analog input module M340 - 8 inputs -temperatureMainRange of product Modicon M340 automation platform Product or component typeAnalog input module Electrical connection 2 connectors 40 ways Input output isolation Isolated Input levelLow level Analogue input number 8Analogue input typeThermocouple -50...+1769 °C thermocouple S Thermocouple -50...+1769 °C thermocouple R Thermocouple -270...+400 °C thermocouple T Thermocouple -270...+1370 °C thermocouple K Thermocouple -270...+1000 °C thermocouple E Thermocouple -200...+900 °C thermocouple L Thermocouple -200...+760 °C thermocouple J Thermocouple -200...+600 °C thermocouple U Thermocouple +270...+1300 °C thermocouple N Thermocouple +130...+1820 °C thermocouple B Temperature probe -60...+180 °C Ni 1000Temperature probe -60...+180 °C Ni 100Temperature probe -200...+850 °C Pt 1000 IEC Temperature probe -200...+850 °C Pt 100 IEC Temperature probe -100...+450 °C Pt 1000 UL/JIS Temperature probe -100...+450 °C Pt 100 UL/JIS Temperature probe -100...+260 °C Cu 10Resistor 4000 Ohm 4 wires Resistor 4000 Ohm 3 wires Resistor 4000 Ohm 2 wires Resistor 400 Ohm 4 wires Resistor 400 Ohm 3 wires Resistor 400 Ohm 2 wires Voltage +/- 80 mV Voltage +/- 640 mV Voltage +/- 40 mV Voltage +/- 320 mV Voltage +/- 160 mV Voltage +/- 1.28 VComplementaryAnalog/Digital conversion Sigma delta 16 bits Analogue input resolution 15 bits + sign Input impedance10 MOhmPermitted overload on inputs+/- 7.5 V +/- 80 mV +/- 7.5 V +/- 640 mV +/- 7.5 V +/- 40 mV +/- 7.5 V +/- 320 mV +/- 7.5 V +/- 160 mV +/- 7.5 V +/- 1.28 V Common mode rejection 120 dB 50/60 Hz Differential mode rejection 60 dB 50/60 Hz Cold junction compensation External by Pt100 probe Type of filterFirst order digital filtering Nominal read cycle time200 ms with thermocouple400 ms with temperature probeMeasurement error 1.3 °C Ni 1000 0...60 °C0.12 % of full scale 4000 Ohm 25 °C0.12 % of full scale 400 Ohm 25 °C0.05 % of full scale +/- 80 mV 25 °C0.05 % of full scale +/- 640 mV 25 °C0.05 % of full scale +/- 40 mV 25 °C0.05 % of full scale +/- 320 mV 25 °C0.05 % of full scale +/- 160 mV 25 °C0.05 % of full scale +/- 1.28 V 25 °C<= 0.3 % of full scale 400 Ohm 0...60 °C<= 0.2 % of full scale 4000 Ohm 0...60 °C<= 0.2 % of full scale +/- 40 mV 0...60 °C<= 0.15 % of full scale +/- 80 mV 0...60 °C<= 0.15 % of full scale +/- 640 mV 0...60 °C<= 0.15 % of full scale +/- 320 mV 0...60 °C<= 0.15 % of full scale +/- 160 mV 0...60 °C<= 0.15 % of full scale +/- 1.28 V 0...60 °C+/- 5 °C thermocouple T 0...60 °C+/- 5 °C thermocouple N 0...60 °C+/- 5 °C thermocouple K 0...60 °C+/- 5 °C thermocouple E 0...60 °C+/- 5 °C thermocouple B 0...60 °C+/- 4.5 °C thermocouple U 0...60 °C+/- 4.5 °C thermocouple S 0...60 °C+/- 4.5 °C thermocouple R 0...60 °C+/- 4.5 °C thermocouple L 0...60 °C+/- 4.5 °C thermocouple J 0...60 °C+/- 4 °C Cu 10 25 °C+/- 4 °C Cu 10 0...60 °C+/- 3.7 °C thermocouple T 25 °C+/- 3.7 °C thermocouple N 25 °C+/- 3.7 °C thermocouple K 25 °C+/- 3.7 °C thermocouple E 25 °C+/- 3.5 °C thermocouple B 25 °C+/- 3.2 °C thermocouple S 25 °C+/- 3.2 °C thermocouple R 25 °C+/- 3 °C thermocouple L 25 °C+/- 3 °C Ni 100 0...60 °C+/- 2.8 °C thermocouple J 25 °C+/- 2.7 °C thermocouple U 25 °C+/- 2.1 °C Pt 1000 25 °C+/- 2.1 °C Pt 100 25 °C+/- 2.1 °C Ni 100 25 °C+/- 2 °C Pt 1000 0...60 °C+/- 2 °C Pt 100 0...60 °C+/- 0.7 °C Ni 1000 25 °CTemperature drift30 ppm/°C Pt 100030 ppm/°C Pt 10030 ppm/°C Ni 10030 ppm/°C Cu 1030 ppm/°C +/- 80 mV30 ppm/°C +/- 640 mV30 ppm/°C +/- 40 mV30 ppm/°C +/- 320 mV30 ppm/°C +/- 160 mV30 ppm/°C +/- 1.28 V25 ppm/°C thermocouple U25 ppm/°C thermocouple T25 ppm/°C thermocouple S25 ppm/°C thermocouple R25 ppm/°C thermocouple N25 ppm/°C thermocouple L25 ppm/°C thermocouple K25 ppm/°C thermocouple J25 ppm/°C thermocouple E25 ppm/°C thermocouple B25 ppm/°C Ni 100025 ppm/°C 4000 Ohm25 ppm/°C 400 OhmRecalibration InternalDetection type Open circuit thermocouple UOpen circuit thermocouple TOpen circuit thermocouple SOpen circuit thermocouple ROpen circuit thermocouple NOpen circuit thermocouple LOpen circuit thermocouple KOpen circuit thermocouple JOpen circuit thermocouple EOpen circuit thermocouple BOpen circuit Pt 1000Open circuit Pt 100Open circuit Ni 1000Open circuit Ni 100Open circuit Cu 10Maximum wiring resistance500 Ohm 4 wires Pt 1000500 Ohm 4 wires Ni 100050 Ohm 4 wires Pt 10050 Ohm 4 wires Ni 10050 Ohm 4 wires Cu 10200 Ohm 3 wires Pt 1000200 Ohm 3 wires Ni 1000200 Ohm 2 wires Pt 1000200 Ohm 2 wires Ni 100020 Ohm 3 wires Pt 10020 Ohm 3 wires Ni 10020 Ohm 3 wires Cu 1020 Ohm 2 wires Pt 10020 Ohm 2 wires Ni 10020 Ohm 2 wires Cu 10Measurement resolution80/2exp14 mV +/- 80 mV640/2exp14 mV +/- 640 mV4000/2exp14 mV 4000 Ohm40/2exp14 mV 400 Ohm40/2exp14 mV +/- 40 mV320/2exp14 mV +/- 320 mV160/2exp14 mV +/- 160 mV1280/2exp14 mV +/- 1.28 V0.1 °C thermocouple U0.1 °C thermocouple T0.1 °C thermocouple S0.1 °C thermocouple R0.1 °C thermocouple N0.1 °C thermocouple L0.1 °C thermocouple K0.1 °C thermocouple J0.1 °C thermocouple E0.1 °C thermocouple B0.1 °C Pt 10000.1 °C Pt 1000.1 °C Ni 10000.1 °C Ni 1000.1 °C Cu 10Maximum conversion value+/- 102.5 % +/- 80 mV+/- 102.5 % +/- 640 mV+/- 102.5 % +/- 40 mV+/- 102.5 % +/- 320 mV+/- 102.5 % +/- 160 mV+/- 102.5 % +/- 1.28 V+/- 100 % 4000 Ohm+/- 100 % 400 OhmStatus LED 1 LED red I/O1 LED red ERR1 LED per channel green channel diagnostic1 LED green RUNProduct weight0.165 kgCurrent consumption150 mA at 3.3 V DCEnvironmentAmbient air temperature for operation0...60 °CRelative humidity10...95 % without condensationIP degree of protection IP20Protective treatment TCEnvironmental characteristic3C4 conforming to EN/IEC 60721-3-33C3 conforming to EN/IEC 60721-3-3Dimensions DrawingsModules Mounted on RacksDimensions(1)With removable terminal block (cage, screw or spring).(2)With FCN connector.(3)On AM1 ED rail: 35 mm wide, 15 mm deep. Only possible with BMXXBP0400/0400H/0600/0600H/0800/0800H rack.Connections and SchemaWiring DiagramBelow example shows a probe configuration with:●Channel 0/4: Thermocouple ●Channel 1/5: 2-wires RTD ●Channel 2/6: 3-wires RTD ●Channel 3/7: 4-wires RTDMS+Thermocouple + input MS-Thermocouple - inputEX+RTD probe current generator + output EX-RTD probe current generator - output NC Not connectedDtC The CJC sensor detection input is connected to CJ+ if the sensor type is DS600. It is not connected (NC) if the sensor type is LM31.NOTE: The CJC sensor is needed for TC only.。
新概念英语4答案
新概念英语4答案【篇一:新概念英语第四册课后习题答案】txt>unit 1 cabdd bdaac ab unit 25 dbadd cacdb caunit 2 bcbdc acaad bc unit 26 cbcba cddab acunit 3 cabda cdaba cd unit 27 bcdcc accdd daunit 4 accab bcdaa bd unit 28 adcda bcada bdunit 5 cabab dacbb dd unit 29 ccadd ccada bcunit 6 caccc aaadb aa unit 30 cabdd bccac dcunit 7 dcaba bacda ac unit 31 aabad baddc bdunit 8 bdabd baabc bc unit 32 bdcba dbdca bcunit 9 cdbaa cabac ad unit 33 bdbad bccdc baunit 10 caabd cbbdc aa unit 34 dcacb dacdb caunit 11 aabdd daddb dd unit 35 cbcac abbdc cdunit 12 cabac cdaca ab unit 36 acbcc accdb acunit 13 acdac bdabc ad unit 37 cabac dbcdc bdunit 14 dbdcc accbd bd unit 38 caabb acbdd abunit 15 cadcd dbaca ca unit 39 bcada bddbd bcunit 16 abcca ddbab ac unit 40 dcdac addda dbunit 17 bbada bbdcd ca unit 41 acacd cbbbd bcunit 18 babcd cdccc ba unit 42 bccbd bdadc acunit 19 bbcad aabdd bc unit 43 dbabc cddac bbunit 20 bcadc ccbdb ca unit 44 aaaab bbbdc baunit 21 bdbba addab ca unit 45 cadac cacdc dcunit 22 cdacb adbcd ab unit 46 bbdbd abcda bdunit 23 cadcc dcabc ac unit 47 caadb cacdb bcunit 24 aaccb cadda cd unit 48 ccbcc ccdba ab新概念4 笔记 /nce/24278_2.shtmlunit 1 finding fossil man一、重点单词解释1、recount:v.叙述注意读音,重音在后。
常用英语前缀
常用英语前缀Ⅰ.前缀re-re-是最常用的前缀之一。
它可以加在名词或动词前面,构成新的名词或动词。
re-表示以下三方面的意义:1.表示"回"或"向后"的意思。
例如:return(回来,返回)recall(回忆,召回)retract(缩回,取回)2.表示"再"、"重新"、"重复"的意思。
例如:review(复习)reunion(团圆,重聚)restart(重新开始)reconstruction (重建)3.表示"相反"、"反对"的意思。
例如:rebel(反叛,谋反)reverse(反转,颠倒)resist(反抗,抵抗)Ⅱ.前缀de-与dis-前缀de-来自拉丁语,意为"away from",所以这个前缀的意义之一就是"离开"、"出"。
它构成的词有一定规律性,常表"离开"这一深层概念,而且常与介词from等搭配,例如:dethrone(废黜)deport(驱逐出境)deduce(推断)derail(脱轨)Delete his name from the list of members.把他的名字从成员名单上除去。
The train will depart from platform 2.这列火车将从2号站台发车。
另外,前缀de-还表示"除去"、"取消"以及"否定"、"非"、"相反"的意思。
例如:decamp(撤营)decode(解码)deforest(砍伐森林)decolonize(非殖民化)devaluation(贬值)He has been degraded from public office.他已经被解除公职。
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Lesson 48 The silent villageLecturer: 辰辰In this much-travelled world, there are still thousands of places which are inaccessible to tourists. We always assume that villagers in remote places are friendly and hospitable. But people who are cut off not only from foreign tourists, but even from their own countrymen can be hostile to travellers. Visits to really remote villages are seldom enjoyable -- as my wife and I discovered during a tour through the Balkans.We had spent several days in a small town and visited a number of old churches in the vicinity. These attracted many visitors, for they were not only of great architectural interest, but contained a large number of beautifully preserved frescoes as well. On the day before our departure, several bus loads of tourists descended on the town. This was more than we could bear, so we decided to spend our last day exploring the countryside. Taking a path which led out of the town, we crossed a few fields until we came to a dense wood. We expected the path to end abruptly, but we found that it traced its way through the trees. We tramped through the wood for over two hours until we arrived at a deep stream. We could see that the path continued on the other side, but we had no idea how we could get across the stream. Suddenly my wife spotted a boat moored to the bank. In it there was a boatman fast asleep. We gently woke him up and asked him to ferry us to the other side. Though he was reluctant to do so at first, we eventually persuaded him to take us.The path led to a tiny village perched on the steep sides of a mountain. The place consisted of a straggling unmade road which was lined on either side by small houses. Even under a clear blue sky, the village looked forbidding, as all the houses were built of grey mud bricks. The village seemed deserted, the only sign of life being an ugly-looking black goat on a short length of rope tied to a tree in a field nearby. Sitting down on a dilapidated wooden fence near the field, we opened a couple of tins of sardines and had a picnic lunch. All at once, I noticed that my wife seemed to be filled with alarm. Looking up I saw that we were surrounded by children in rags who were looking at us silently as we ate. We offered them food and spoke to them kindly, but they remained motionless. I concluded that they were simply shy of strangers. When we later walked down the main street of the villager, we were followed by a silent procession of children. The village which had seemed deserted, immediately came to life. Faces appeared at windows. Men in shirt sleeves stood outside their houses and glared at us. Old women in black shawls peered at us from doorways. The most frightening thing of all was that not a sound could be heard. There was no doubt that we were unwelcome visitors. We needed no further warning. Turning back down the main street, we quickened our pace and made our way rapidly towards the stream where we hoped the boatman was waiting.The villages straggle in the mountains.His beard straggles because he hasn't shaven for a week. Straggly 'Dilapidated [di'læpideitid]Dilapidate [di'læpideit]After the war, the place became dilapidated.admitadmissionpermitpermissionl Sardine庸碌无能的人you are really sardinelike sardinesThe commuters were packed into metro like sardines in a can. The stranger dressed in rags is a beggara rag of 衣衫褴褛、There is not a rag of evidence. 没有证据from rags to riches 从穷到富一夜暴富He went from rags to riches in only three years.on the ragThe little girl is on the rag.She motioned to the waiter.He motioned to me to sit down.He opened the door and motioned me to come in.I approached him, but he motioned me away.the approac h es ofIt happened during the procession. 事情发生在行进途中。
a crowd ofa herd ofa group ofa covey of 指人很多一堆堆神马的stare atgaze atpeer at 盯着看without a peer 无以伦比In my heart, my girlfriend is without a peer.peer assessment (同学间)互评We have to quicken our pace.My pulse quickened when I saw the frightful sight.accelerate the reformreform and opening upspeed up the tempo of the four modernizations 加速四个现代化建设The village contained one street and looked forbidding. Apart from a goat, it seemed deserted, so they sat down and had a picnic. Looking up, they suddenly found themselves surrounded by children in rags. The children were silent and motionless. As they walked down the street followed by the children, the village came alive with faces in windows and people watching them silently from doorways. The visitors were clearly unwelcome. They hurried back down to the stream and the boatman.。