The Threshold between Micro and Macro Environments Abstract

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前缀macro- micro- mal的用法

•
micro
百万分之一
+
+
gram
克
=
=
microgram
百万分之一克
microgram['maɪkroɡræ m] n.百万分之一 eg.Ingesting（吃下，吸入） even a microgram of lead can harm a child.
• micro + economics = microeconomics
eg:Rob maintains a macrobiotic diet and does not eat packaged （包装的）foods.
macrobiotics n. 长寿学；延年益寿的饮食法
• macro
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evolution = macroevolution
• 宏观的 + 演化 = 长时间的演化 • macroevolution['mæ kro,ɛvə'lʊʃən]宏观演化；长时间的演化 • eg.Monkey tails changing into human tailbones is a result of ~ • macroevolutionary a. 宏观演化大的 • evolution n. 进化；演变；进展
异常的 + 功能运转 = 运转失灵
malformation['mæ lfɔr'meʃən] v.发生故障；运
转失灵 eg.My camara malformationed on my vacation so I have no photo of this trip.
• mal
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nutrition

美国伦布科技 Agilent 16800 Series Portable Logic Analyze

Agilent 16800 SeriesPortable Logic AnalyzersData SheetQuickly debug, validate,and optimize your digitalsystem – at a price thatfits your budget.Features and benefits•250 ps resolution (4 GHz) timingzoom to find elusive timing problemsquickly, without double probing•15” display, with available touchscreen, allows you to see more dataand navigate quicklymeasurements and displays of yourlogic analyzer and oscilloscope datalet you effectively track downproblems across the analog anddigital portions of your design•Eight models with34/68/102/136/204 channels,up to 32M memory depth andmodels with a pattern generatorprovide the measurement flexibilityfor any budget•Application support for every aspectof today’s complex designs – FPGAdynamic probe, digital VSA (vectorsignal analysis) and broad processorand bus support2Selection Guide for 16800 Series Portable Logic AnalyzersModels with a built-in pattern generator give you more measurement flexibility1Pattern generator available with 16821A, 16822A and 16823A.Choose from eight models to get the measurement capability for your specific applicationProbes are ordered separately. Please specify probes when ordering to ensure the correct connection between your logic analyzer, pattern generator, and the device under test.Agilent 16800 Series portable logic analyzers offer the performance, applications, and usability your digital development team needs to quickly debug, validate, and optimize your digital system – at a price that fits your budget.The logic analyzer’s timing and state acquisition gives you the power to:•Accurately measure precise timing relationships using4GHz (250ps) timing zoomwith 64K depth•Find anomalies separated in time with memory depthsupgradeable to 32M•Buy what you need today and upgrade in the future. 16800Series logic analyzers comewith independent upgrades for memory depth and state speed •Sample synchronous buses accurately and confidentlyusing eye finder. Eye finderautomatically adjuststhreshold and setup andhold to give you the highestconfidence in measurementson high-speed buses•Track problems from symptom to root cause across severalmeasurement modes byviewing time-correlated datain waveform/chart, listing,inverse assembly, source code, or compare display •Set up triggers quickly andconfidently with intuitive,simple, quick, and advancedtriggering. This capabilitycombines new triggerfunctionality with an intuitiveuser interface•Access the signals that holdthe key to your system’sproblems with the industry’swidest range of probingaccessories with capacitiveloading down to 0.7 pF•Monitor and correlate multiplebuses with split analyzercapability, which providessingle and multi-bus support(timing, state, timing/state orstate/state configurations)Accurately measure precisetiming relationships16800 Series logic analyzers letyou make accurate high-speedtiming measurements with 4GHz(250ps) high-speed timing zoom. Aparallel acquisition architectureprovides high-speed timingmeasurements simultaneouslythrough the same probe used forstate or timing measurements.Timing zoom stays active all thetime with no tradeoffs. View dataat high resolution over longerperiods of time with 64-K-deeptiming zoom.Figure 1. With eight models to choose from, you can get alogic analyzer with measurement capabilities that meetyour needs.3Automate measurement setup and quickly gain diagnostic clues16800 Series logic analyzers make it easy for you to get up and running quickly by automating your measurement setup process. In addition, the logic analyzer’s setup/hold window (or sampling position) and threshold voltage settings are automatically determined so you can capture data on high-speed buses with the highest accuracy. Auto Threshold and Sample Position mode allow you to...•Obtain accurate and reliable measurements•Save time during measurement setup•Gain diagnostic clues and identify problem signalsquickly•Scan all signals and buses simultaneously or just a few•View results as a composite display or as individual signals•See skew between signals and buses•Find and fix inappropriate clock thresholds•Measure data valid windows•Identify signal integrityproblems related to rise times,fall times, data valid windowwidths Identify problem signals overhundreds of channels simultaneouslyAs timing and voltage marginscontinue to shrink, confidencein signal integrity becomes anincreasingly vital requirementin the design validation process.Eye scan lets you acquire signalintegrity information on allthe buses in your design, undera wide variety of operatingconditions, in a matter ofminutes. Identify problem signalsquickly for further investigationwith an oscilloscope. Results canbe viewed for each individualsignal or as a composite ofmultiple signals or buses.Extend the life of your equipmentEasily upgrade your 16800 Serieslogic analyzer. “Turn on”additional memory depth andstate speed when you need more.Purchase the capability youneed now, then upgrade as yourneeds evolve.Figure 2. Identify problem signals quickly by viewing eye diagrams across all buses and signals simultaneously.4578910A Built-in Pattern Generator Gives You Digital Stimulus and Responsein a Single InstrumentSelected 16800 Series models (16821A, 16822A and 16823A)also include a 48-channel pattern generator to drive down risk early in product development. With a pattern generator you can:•Substitute for missing boards,integrated circuits (ICs) or buses instead of waiting for missing pieces •Write software to createinfrequently encountered test conditions and verify that the code works – before complete hardware is available •Generate patterns necessary to put a circuit in a desired state,operate the circuit at full speed or step the circuit through a series of states •Create a circuit initialization sequence Agilent 16800 Series portable logic analyzers with a pattern generator offer a variety offeatures that make it easier for you to create digital stimulus tests.Vectors up to 48 bits wideVectors are defined as a “row” of labeled data values, with each data value from one to 48 bits wide. Each vector is output on the rising edge of the clock.Create stimulus patterns for the widest buses in your system.Depth up to 16 M vectorsWith the pattern generator, you can load and run up to 16Mvectors of stimulus. Depth on this scale is most useful when coupled with powerful stimulus generated by electronic design automation tools, such as SynaptiCAD’sWaveFormer and VeriLogger.These tools create stimulus using a combination of graphicallydrawn signals, timing parameters that constrain edges, clock signals,and timing and Boolean equations for describing complex signal behavior. The stimulus also can be created from design simulation waveforms. The SynaptiCAD tools allow you to convert .VCD files into .PGB files directly, offering you an integrated solution that saves you time.Synchronized clock outputYou can output data synchronized to either an internal or external clock. The external clock is input via a clock pod, and has nominimum frequency (other than a 2ns minimum high time).The internal clock is selectable between 1MHz and 300MHz in 1-MHz steps. A Clock Out signal is available from the clock pod and can be used as an edge strobe with a variable delay of up to 8ns.Initialize (INIT) block for repetitive runsWhen running repetitively, the vectors in the initialize (init)sequence are output only once,while the main sequence isoutput as a continually repeating sequence. This “init” sequence is very useful when the circuit or subsystem needs to be initialized.The repetitive run capability is especially helpful whenoperating the pattern generator independent of the logic analyzer.“Send Arm out to…” coordinates activity with the logic analyzerVerify how your system responds to a specific stimulus sequence by arming the logic analyzer from the pattern generator. A “Send Arm out to…” instruction acts as a trigger arming event for the logic analyzer or other test equipment to begin measurements. Arm setup and trigger setup of the logic analyzer determines the action initiated by “Send Arm out to…”.Figure 3. Models with a built-in pattern generator give you more measurement flexibility.“Wait for External Event…” forinput patternThe clock pod also accepts a 3-bit input pattern. These inputs are level-sensed so that any number of “Wait for External Event”instructions can be inserted into a stimulus program. Up to four pattern conditions can be defined from the OR-ing of the eight possible 3-bit input patterns. A “Wait for External Event” also can be defined to wait for an Arm. This Arm signal can come from the logic analyzer. “Wait for External Event…” allows you to executea specific stimulus sequence only when the defined external event occurs.Simplify creation of stimulus programs with user-defined macros and loops User macros permit you to define a pattern sequence once, then insert the macro by name wherever it is needed. Passing parameters to the macro will allow you to create a more generic macro. For each call to the macro you can specify unique values for the parameters.Loops enable you to repeat a defined block of vectors for a specified number of times. Loops and macros can be nested, except that a macro cannot be nested within another macro. At compile time, loops and macros are expanded in memory to alinear sequence.Convenient data entry andediting featureYou can conveniently enterpatterns in hex, octal, binary,decimal, and signed decimal(two’s complement) bases. Tosimplify data entry, you can viewthe data associated with anindividual label with multipleradixes. Delete, Insert, and Copycommands are provided for easyediting. Fast and convenientPattern Fills give the programmeruseful test patterns with a fewkey strokes. Fixed, Count, Rotate,Toggle, and Random patterns areavailable to help you quicklycreate a test pattern, suchas “walking ones.” Patternparameters, such as step size andrepeat frequency, can be specifiedin the pattern setup.ASCII input file format: your designtool connectionThe pattern generator supportsan ASCII file format to facilitateconnectivity to other tools in yourdesign environment. Because theASCII format does not support theinstructions listed earlier, theycannot be edited into the ASCIIfile. User macros and loops alsoare not supported, so the vectorsneed to be fully expanded in theASCII file. Many design tools willgenerate ASCII files and outputthe vectors in this linear sequence.Data must be in hex format, andeach label must represent a set ofcontiguous output channels.ConfigurationThe pattern generator operateswith the clock pods, data pods,and lead sets described later inthis document. At least one clockpod and one data pod must beselected to configure a functionalsystem. You can select from avariety of pods to provide thesignal source needed for your logicdevices. The data pods, clock podsand data cables use standardconnectors. The electricalcharacteristics of the data cablesare described for users withspecialized applications who wantto avoid the use of a data pod.Direct connection to yourtarget systemYou can connect the patterngenerator pods directly to astandard connector on your targetsystem. Use a 3M brand #2520Series or similar connector. Theclock or data pods will plug rightin. Short, flat cable jumpers canbe used if the clearance aroundthe connector is limited. Use a 3M#3365/20, or equivalent, ribboncable; a 3M #4620 Series orequivalent connector on thepattern generator pod end of thecable, and a 3M #3421 Series orequivalent connector at yourtarget system end of the cable.Probing accessoriesThe probe tips of theAgilent10474A, 10347A, 10498A,and E8142A lead sets plugdirectly into any 0.1-inch gridwith 0.026-inch to 0.033-inchdiameter round pins or 0.025-inchsquare pins. These probe tipswork with the Agilent5090-4356surface mount grabbers andwith the Agilent5959-0288through-hole grabbers, providingcompatibility with industrystandard pins.A Built-in Pattern Generator Gives You Digital Stimulus and Response in a Single Instrument3-STATE IN TTLPattern generator cable pin outsData cable (Pod end)Clock cable (Pod end)2122Unleash the Complementary Power of a Logic Analyzer and an Oscilloscope Seamless scope integrationwith View ScopeEasily make time-correlatedmeasurements between Agilentlogic analyzers and oscilloscopes.The time-correlated logic analyzerand oscilloscope waveforms areintegrated into a single logicanalyzer waveform display foreasy viewing and analysis. Youcan also trigger the oscilloscopefrom the logic analyzer (or viceversa), automatically de-skew thewaveforms and maintain markertracking between the twoinstruments. Perform thefollowing more effectively:•Validate signal integrity•Track down problems caused by signal integrity•Validate correct operation of A/D and D/A converters •Validate correct logical and timing relationships betweenthe analog and digital portions of a designConnectionThe Agilent logic analyzer and oscilloscope can be physically connected with standard BNC and LAN connections. Two BNC cables are connected for cross triggering, and the LAN connection is used to transfer data between the instruments. The View Scope correlation software is standard in the logic analyzer’s application software version 3.50 or higher. The View Scope software includes:•Ability to import some or all of the captured oscilloscopewaveforms•Auto scaling of the scopewaveforms for the best fit inthe logic analyzer displayFigure 4. View Scope seamlessly integrates your scopeand logic analyzer waveforms into a single display.2324Acquisition and analysis tools provide rapid insight into your toughest debug problemsYou have unique measurement and analysis needs. When you want to understand what your target is doing and why, you need acquisition and analysis tools that rapidly consolidate data into displays that provide insight into your system’s behavior.Figure 5. Perform in-depth time, frequency and modulation domain analysis on your digital baseband and IF signals with Agilent’s 89600 Vector Signal Analysis software.Save time analyzing your unique design with a turnkey setup Agilent Technologies and our partners provide an extensive range of bus and processor analysis probes. They provide non-intrusive, full-speed,real-time analysis to accelerate your debugging process.•Save time making bus-and processor-specificmeasurements withapplication specific analysisprobes that quickly andreliably connect to yourdevice under test•Display processor mnemonicsor bus cycle decode•Get support for acomprehensive list ofindustry-standard processorsand buses252627ProgrammabilityYou can write programs to control the logic analyzer application from remote computers on the local area network using COM or ASCII. The COM automation serveris part of the logic analyzer application. This software allows you to write programs to control the logic analyzer. All measurement functionality is controllable via the COM interface.The B4608A Remote ProgrammingInterface (RPI) lets you remotelycontrol a 16800 Series logicanalyzer by issuing ASCIIcommands to the TCP socketon port 6500. This interface isdesigned to be as similar aspossible to the RPI on 16700Series logic analysis systems,so that you can reuse existingprograms.The remote programminginterface works through the COMautomation objects, methods,and properties provided forcontrolling the logic analyzerapplication. RPI commands areimplemented as Visual Basicmodules that execute COMautomation commands, translatetheir results, and return propervalues for the RPI. You can use theB4606A advanced customizationenvironment to customize andadd RPI commands.Figure 6. 16800 Series programming overview2816800 Series Interfaces2930Figure 9. 16800 Series back panelFull profile PCI card expansion slotExternal display portParallel portSerial port10/100 Base T LAN 2.0 USB ports (4)Clock inTrigger out Trigger in Keyboard Mouse AC power Figure 8. 16800 Series front panelOn/Off power switch 15 inch built-in color LCD display, Touch Screen available General purpose knob Run/stop keys Touch screen on/off (if ordered)16800 Series Physical CharacteristicsDimensionsPower 16801A 115/230 V, 48-66 Hz, 605 W max 16802A 115/230 V, 48-66 Hz, 605 W max 16803A 115/230 V, 48-66 Hz, 605 W max 16804A 115/230 V, 48-66 Hz, 775 W max 16806A 115/230 V, 48-66 Hz, 775 W max 16821A 115/230 V, 48-66 Hz, 775 W max 16822A 115/230 V, 48-66 Hz, 775 W max 16823A 115/230 V, 48-66 Hz, 775 W max Weight Max net Max shipping 16801A 12.9 kg 19.7 kg (28.5 lbs)(43.5 lbs)16802A 13.2 kg 19.9 kg (28.9 lbs)(43.9 lbs)16803A 13.7 kg 20.5 kg (30.3 lbs)(45.3 lbs)16804A 14.2 kg 21.0 kg (31.3 lbs)(46.3 lbs)16806A 14.6 kg 21.4 kg (32.1 lbs)(47.1 lbs)16821A 14.2 kg 20.9 kg (31.2 lbs)(46.2 lbs)16822A 14.2 kg 21.1 kg (31.6 lbs)(46.6 lbs)16823A14.5 kg 21.3 kg (32.0 lbs)(47.0 lbs)Instrument operating environment Temperature 0˚ C to 50˚ C (32˚ F to 122˚ F)Altitude To 3000 m (10,000 ft)Humidity8 to 80% relative humidity at 40˚ C (104˚ F)Figure 7. 16800 Series exterior dimensionsFigure 10. 16800 Series side view330.32(13.005)Dimensions: mm (inches)28.822(11.347)443.23(17.450)Agilent 1184A TestmobileThe Agilent 1184A testmobile gives you a convenient means of organizing and transporting your logic analyzer and accessories.The testmobile includes the following:•Drawer for accessories(probes, cables, power cords)•Keyboard tray with adjustable tilt and height•Mouse extension on keyboard tray for either right or lefthand operation•on uneven surfaces••Load limits:Total: 136.4 kg (300.0 lb.)Figure 11. Agilent 1184A testmobile cartFigure 12. Agilent 1184A testmobile cart dimensions3132Stationary shelfThis light-duty fixed shelf isdesigned to support 16800 Series logic analyzers. The shelf can be used in all standard Agilent racks. The stationary shelf is mounted securely into placeusing the supplied hardware and is designed to sit at the bottom of the EIA increment. Features of the stationary shelf include:•Snap-in design for easy installation •Smooth edgesRack accessoriesSliding shelfThe sliding shelf provides a flat surface with full product accessibility. It can be used in all Agilent racks to support 16800Series logic analyzers. The shelf and slides are preassembled for easy installation. Features of the sliding shelf include:•Snap-in design for easy installation •Smooth edgesConsider purchasing the steel ballast (C2790AC) to use with the sliding shelf. The ballast provides anti-tip capability when the shelf is extended.Figure 15. Sliding shelf (J1526AC)Figure 14. Stationary shelf (J1520AC)Figure 13. Sliding shelf installed in rackEach 16800 Series portable logicanalyzer comes with one PS/2keyboard, one PS/2 mouse,accessory pouch, power cord and1-year warranty standard.Selecting a logic analyzer to meet your application and budget is as easy as 1, 2, 3333435。

Highly birefringent suspended-core photonic microcells for refractive-index sensing

$Highly birefringent suspended-core photonic microcells for refractive-index sensing$

Highly birefringent suspended-core photonic microcells for refractive-index sensingChao Wang,1,2Wa Jin,1Changrui Liao,3Jun Ma,1Wei Jin,1,a)Fan Y ang,1Hoi Lut Ho,1and Yiping Wang 31Department of Electrical Engineering,The Hong Kong Polytechnic University,Hong Kong,China 2The Hong Kong Polytechnic University Shenzhen Research Institute,Shenzhen 518057,China 3Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province,Shenzhen University,Shenzhen 518060,China(Received 18June 2014;accepted 1August 2014;published online 12August 2014)An in-line photonic microcell with a highly birefringent suspended microﬁber core is fabricated by locally heating and pressurizing selected air-holes of an endless single mode photonic crystal ﬁber.The microﬁber core has rhombus-like cross-sectional geometry and could achieve a high birefrin-gence of up to 10À2.The microﬁber core is ﬁxed at the center of the microcell by thin struts attached to an outer jacket tube,which protects and isolates the microﬁber from environmental con-taminations.Highly sensitive and robust refractive index sensors based on such microcells areexperimentally demonstrated.VC 2014AIP Publishing LLC .[/10.1063/1.4892962]Optical microﬁbers with two-fold geometric symmetryhave attracted considerable interests recently.These micro-ﬁbers possess the properties of conventional circular-shaped microﬁber such as strong evanescent ﬁled,tight optical con-ﬁnement,small size and light weight,1and at the same time exhibit high birefringence,which would enable useful appli-cations such as highly sensitive refractive-index (RI)sen-sors,2,3optical wavelength ﬁlters,3,4birefringent ﬁber coil resonator,5and polarization converters.6The birefringence of a microﬁber is affected by the geo-metric aspect ratio,the size of microﬁber,and the RI contrast between the core and cladding.For a microﬁber with air-cladding,the birefringence gets higher with larger aspect ra-tio and approaches a maximum value when the cross-sectional dimension is about the wavelength-scale.7So far,highly birefringent (Hi-Bi)microﬁbers have been fabricated by tapering non-cylindrical ﬁbers such as rectangular ﬁber 7,8and D-ﬁber 9or by etching cylindrical ﬁbers with traveling micro-droplets of hydroﬂuoric acid.10In this Letter,we report Hi-Bi microﬁber with a rhombus-like cross-sectional shape.As illustrated in Fig.1,the microﬁber is housed inside a photonic microcell made by locally inﬂating selected air-holes 11of a photonic crystal ﬁber (PCF).The two ends of the microﬁber are automatically and adiabatically connected PCF pigtails from which the microcell is fabricated.The expanded holes are sufﬁciently large to prevent leakage of the evanescent ﬁeld,while the jacket tube protects the microﬁber from external contamina-tions and makes the device much more robust as compared with a bare air-clad microﬁber.The air-region between the jacket and the microﬁber provides a contamination-free plat-form for light-matter interaction through the evanescent ﬁeld of an optical mode propagating in the suspended micro ﬁber core.The fabrication of the photonic microcell follows a three-step process:At ﬁrst,four air-holes at one end of thePCF,as illustrated in Fig.2(a),are selectively opened by use of a femtosecond laser-assisted selective opening tech-nique.12The other end of the PCF is spliced to a single mode ﬁber (SMF)to seal all the air-holes at this end.Second,high pressure gas is applied to the four selected air-columns of the PCF via the openings.Gas pressures in other air-columns remain at atmospheric pressure.Finally,the pressurized air-columns are locally inﬂated via a heating/tapering process.11During this process,the pressurized columns expand while other columns collapse gradually and eventually the central core is isolated from other part of the ﬁber by a large air region,with extremely thin struts which support the core.The micrographs of a typical microcell at the suspended core region and the transition region are given in Figs.2(b)and 2(c),respectively.The rhombus-like core (microﬁber)is supported by four struts connected to the outer jacket tube and the thicknesses of the struts are thinner than 300nm.The microﬁber geometry is formed as the result of asymmetric stretching of the struts that have different thicknesses and has a high aspect ratio of $2,exhibiting high birefringence.To minimize the loss occurring in transition,the struts with sub-wavelength width should be formed before the unpres-surized air-holes are completely collapsed.This is done by controlling the gas pressure so that the expansion rate of selected air-holes is much faster than the collapsing rate of the remaining air-holes.However,if the applied pressureisFIG.1.Schematic of a photonic microcell with a suspended highly birefrin-gent microﬁber core.a)Email:eewjin@.hk0003-6951/2014/105(6)/061105/4/$30.00VC 2014AIP Publishing LLC 105,061105-1APPLIED PHYSICS LETTERS 105,061105(2014)too high,controlling of the expansion would become difﬁ-cult,especially when the wall-thickness of the jacket tube becomes thin and high gas pressure would blow up the microcell very quickly.In our experiments,gas pressures in the range from 6to 9bars were used,and the insertion loss of the microcell in the wavelength range from 1250to 1650nm is $0.2dB.The cross-sectional shape of the microﬁber core may be modeled approximately by an ellipse with a long to short axis ratio of a/b ¼2,as indicated in the inset of Fig.2(b).The four curved sides of the microﬁber are parts of four iden-tical ellipses with long/short axis ratio of 2,and the mini-mum horizontal and vertical separations between ellipses,which correspond to the thicknesses of the struts,are set to be one-twentieth of the short and long axes,respectively.Based on this model,we numerically calculated the phase birefringence B(k )¼j n x (k )2n y (k )j by use of the COMSOL software.Here,n x and n y represent,respectively,the effec-tive RI of the two polarization states of the fundamental HE 11mode.The calculated results are shown in Fig.3.In air,the Hi-Bi microﬁber exhibits a theoretical maxi-mal birefringence B max of $3.5Â10À2when the normalized core radius r N ¼r eq /k is around 0.257,where k is the opera-tion wavelength and the equivalent radius r eq is deﬁned as (a Áb)1/2.At k ¼1550nm,the largest birefringence B max would be obtained when the radius r eq is $400nm.The bire-fringence decreases with increasing ambient RI around the microﬁber,as shown in Fig.3(a).The peak birefringence B max and the corresponding normalized core radius (r N )as functions of n amb are shown in Fig.3(b).Based on the results in Fig.3(a),the group birefringence G was calculated by using G ¼B Àk Á(dB/d k )and shown in Fig.3(c).The maxi-mum theoretical group birefringence G max reaches $8.2Â10À2at r N %0.19for n amb ¼1.The group birefringence of the Hi-Bi microﬁber was measured by use of a Sagnac loop interferometer (SLI)illus-trated in Fig.4(a).The loop coupler is a 3-dB coupler and multiple side-holes were drilled on the outer-jacket of the microcell for liquid and gas ﬁlling.A polarization controller (PC)was used in the loop to maximize the fringe contrast.Fig.4(b)shows the measured transmission spectra of a pho-tonic microcell with a rhombus-like microﬁber core when the cell is ﬁlled with air and a RI liquid with n ¼1.3.The length and the radius of the microﬁber are,respectively,L %1cm and r eq %1.6l m.Interference fringes were observed and the fringe spacing is related to the group birefringence (G)and length (L)of the microﬁber by Dk %j k 2/G ÁL j .13At the wavelength of $1550nm,G value of the micro-ﬁber in air was determined to be $4.8Â10À3and $1.5Â10À3when the microcell is ﬁlled with the RI liquid.These results are in agreement with the simulation results in Fig.3(c).By monitoring the wavelength at one of the fringe dips as shown in Fig.4(b),the Hi-Bi microﬁber microcell may be used as a sensor to measure the RI of the surrounding mate-rial.The sensitivity (S)may be expressed as S ¼d k /dn amb ¼(k /G)Á(dB/dn amb ).2Due to the existence of G ¼0point (refer to Fig.3(c)),the sensitivity around the sign reversing point could be signiﬁcantly increased.The black and blue lines in Fig.4(c)are,respectively,the calculated sensitivity and fringe space around the wavelength of 1550nm as functions of microﬁber radius (r eq )and ambient RI (n amb ).The fringe space is deﬁned as the wavelength sep-aration between adjacent attenuation dips.For a larger n amb value,the higher sensitivity region becomes broader and shifts toward larger r eq values.This would allow high sensi-tivity RI sensors with relatively larger and practicalsizedFIG.2.(a)Schematic of photonic crys-tal ﬁber endface with four air-holes (la-beled as white circles)opened for pressurization while all other air-holes are sealed.Cross-sectional micro-graphs of a photonic microcell with a highly birefringent (Hi-Bi)microﬁber core at (b)the suspended core region and (c)the transition region.Inset of (b):model of Hi-Bi microﬁber used for theoreticalcalculation.FIG.3.(a)Calculated phase birefringence of the highly birefringent microﬁber as a function of normalized core radius r N (deﬁned as (a Áb)1/2/k ),for different ambient refractive index (n amb ).(b)Shift of birefringence peak with ambient refractive index.(c)Calculated group birefringence as a function of normalized core radius.microﬁbers.However,the fringe space (D k )also increases with ambient RI and hence would require a longer length of microﬁber to ensure at least one fringe dip is located in the operating wavelength range of the source.The innate chambers around the Hi-Bi microﬁber pro-vide a compact and isolated space for conﬁning small vol-ume of sample materials and for exploiting light-matter interaction via evanescent ﬁeld of the microﬁber.The ﬁlling and emptying of the chambers can be achieved by the micro-channels fabricated on the jacket tube.The inset of Fig.4(a)shows the micro-channels fabricated on the microcell by use of a femtosecond infrared laser micromachining system.As examples of potential applications,the Hi-Bi microcell which is RI-sensitive was tested for temperature and gas pressure measurement by use of the SLI set up shown in Fig.4(a).Temperature measurements were carried out with a liquid-ﬁlled Hi-Bi microcell with its spectra shown in Fig.4(b).The RI liquid used was made by R.P.Cargille Lab.,Inc.,and has a RI of n ¼1.3at room temperature and a thermo-optic coefﬁcient dn/dt ¼À3.34Â10À4/ C.The liquid-ﬁlled sample was placed in a column oven (ECOMLCO-102)and tested from 25to 95 C.The wave-lengths of the dips change linearly as shown in Fig.5(a)and the dip-a2,which was always present within the wavelength range from 1450to 1650nm,exhibited a high temperature sensitivity of $3nm/ C,corresponding to a RI sensitivity of $9.1Â103nm/RIU.This RI sensitivity is shown as the red dot in Fig.4(c)and agrees well with the theoretical prediction.Measurement of gas pressure was carried out with a sim-ilar Hi-Bi microcell.The fringe spectrum of this microcell was also measured with the SLI and shown in the inset of Fig.5(b).Eight through-holes with diameter of 3–5l m are dilled on the microcell’s jacket tube and on each strut to equalize gas pressure inside and outside the microcell.Then,the microcell was sealed inside a gas chamber made of a glass tube with bore size of $600l m,which was connected to a high pressure nitrogen gas cylinder via a T-tube.Pressurizing the gas within the gas chamber changes the RI of the gas 14and results in a change in the birefringence of the microﬁber.The responses of the dip wavelengths to pres-sure from 1bar to 9bars are shown in Fig.5(b).The pressure sensitivity of the microcell is $300pm/bars,corresponding to a RI sensitivity of $1.5Â103nm/RIU.The RI sensitivity is also shown in Fig.4(c)as the un-ﬁlled circle and agrees with the theoretical prediction.It would be possible to improve the RI sensitivity by further optimizing the dimen-sions of the Hi-Bi microﬁber to make it closer to the maxi-mum sensitivity point.It should be pointed out that the Hi-Bi microcell is com-posed of pure silica which has a low thermo-optic coefﬁ-cient 15and the effect of temperature-induced silica RI change would have very little effect on the measurement results in Fig.5.To verify this,we tested the temperature response of a microcell sample without material ﬁlling.The microcell was ﬁrst annealed at 1000 C for 5h and then tested from 25to 1000 C.As shown in Fig.5(c),the dip wavelength responded linearly to temperature with a very low temperature sensitivity of 3.5pm/C.FIG.4.(a)Experimental setup of the Sagnac loop interferometer.Inset:micrograph of the through-holes on the jacket tube of the highly birefringent (Hi-Bi)microcell.SMF:single mode ﬁber;PC:polarization controller;BBS:broad band source;and OSA:optical spectrum analyzer.(b)Measured transmission spec-tra of a Hi-Bi microﬁber with ambient refractive index n amb ¼1(black)and 1.3(gray).(c)Calculated refractive index sensitivity (black)and fringe space (blue)around the wavelength of 1550nm with different n amb .Red dots represent samples made in experiments for refractive indexsensing.FIG.5.(a)Measured temperature response of a highly birefringent (Hi-Bi)microcell ﬁlled with a refractive index liquid of n ¼1.3.(b)Measured gas pressure response of a Hi-Bi microcell ﬁlled with nitrogen gas.(c)Measured temperature response of a Hi-Bi microcell without material ﬁlling (up to 1000 C).As compared with traditional prism-based RI sensors, optical-ﬁber RI sensors offer the advantages of compactness, remote detection capability,and operation in harsh environ-ment.Different opticalﬁber sensors such asﬁber gra-tings,16,17in-ﬁber cavity,18multimode interferometer,19and four-wave mixing20have been reported;the Hi-Bi micro-ﬁber-based sensors have demonstrated competitively high RI sensitivity($104nm/RIU)with additional advantage of low temperature cross-sensitivity($10À7RIU/ C).However, the bare microﬁber-based devices are vulnerable to contami-nation21and not easy to handle.The current microcell tech-nology provides a way for embedding a Hi-Bi microﬁber within an enclosed compartment and overcomes the prob-lems associated with the use of optical microﬁbers. Furthermore,the tiny in-ﬁber cavity surrounding the micro-ﬁber provides a good platform for strong light-matter inter-action in a reduced space-scale,which would be useful for nanoliter-volume spectroscopy22and bio-chemistry sensing.23In conclusion,a Hi-Bi rhombus-like-shaped microﬁber was fabricated and examined theoretically and experimen-tally.The microﬁber is embedded inside a jacket tube to form a photonic microcell and adiabatically connects to PCF pigtails at both ends.The birefringence of such micro-ﬁber could reach up to the order of10À2and exhibits high sensitivity to ambient RI and low sensitivity to tempera-ture.Such photonic microcells are compact and robust, have low loss,and are ideal platforms for sensors and func-tionalized in-ﬁber devices.Based on such microcells,RI, temperature,and gas pressure sensors are experimentally demonstrated,and the RI sensitivity is$104nm/RIU around n¼1.3.This work was supported by the Natural Science Fundament of China(Grant No.61290313)and the Hong Kong Polytechnic University(Grant No.G-YK62).1L.Tong,F.Zi,X.Guo,and J.Lou,mun.285(23),4641(2012). 2J.Li,L.-P.Sun,S.Gao,Z.Quan,Y.-L.Chang,Y.Ran,L.Jin,and B.-O. Guan,Opt.Lett.36(18),3593(2011).3W.Jin,C.Wang,H.Xuan,and W.Jin,Opt.Lett.38(21),4227(2013).4W.Jin,H.Xuan,and W.Jin,Opt.Lett.39(12),3363(2014).5T.Lee,N.G.R.Broderick,and G.Brambilla,mun.284(7),1837 (2011).6H.Xuan,J.Ma,W.Jin,and W.Jin,Opt.Express22(3),3648(2014).7H.F.Xuan,J.Ju,and W.Jin,Opt.Express18(4),3828(2010).8Y.Jung,G.Brambilla,K.Oh,and D.J.Richardson,Opt.Lett.35(3),378 (2010).9F.Beltr a n-Mej ıa,J.H.Os o rio,C.R.Biazoli,and C.M.B.Cordeiro, J.Lightwave Technol.31(16),2756(2013).10J.C.Mikkelsen and J.K.S.Poon,Opt.Lett.37(13),2601(2012).11C.Wang,W.Jin,J.Ma,Y.Wang,H.Lut Ho,and X.Shi,Opt.Lett. 38(11),1881(2013).12J.Ju,H.Feng Xuan,W.Jin,S.Liu,and H.Lut Ho,Opt.Lett.35(23),3886 (2010).13M.Antkowiak,R.Kotynski,T.Nasilowski,P.Lesiak,J.Wojcik,W. Urbanczyk,F.Berghmans,and H.Thienpont,J.Opt.A:Pure Appl.Opt. 7(12),763(2005).14E.R.Peck and B.N.Khanna,J.Opt.Soc.Am.56(8),1059(1966).15M.J.Weber,Handbook of Optical Materials(CRC Press LLC,2002).16W.Liang,Y.Huang,Y.Xu,R.K.Lee,and A.Yariv,Appl.Phys.Lett. 86(15),151122(2005).17L.Rindorf and O.Bang,Opt.Lett.33(6),563(2008).18C.R.Liao,T.Y.Hu,and D.N.Wang,Opt.Express20(20),22813(2012). 19C.Li,S.-J.Qiu,Y.Chen,F.Xu,and Y.-Q.Lu,IEEE Photonics Technol. Lett.24(19),1771(2012).20M.H.Frosz,A.Stefani,and O.Bang,Opt.Express19(11),10471(2011). 21M.Fujiwara,K.Toubaru,and S.Takeuchi,Opt.Express19(9),8596(2011). 22Y.Cao,W.Jin,L.Hoi Ho,and Z.Liu,Opt.Lett.37(2),214(2012).23S.Heng,M.-C.Nguyen,R.Kostecki,T.M.Monro,and A.D.Abell,RSC Adv.3,8308(2013).。

Two-Phase Flow Patterns and Flow-Pattern Maps-Fundamentals and Applications

Lixin Cheng Laboratory of Heat and Mass Transfer(LTCM),Faculty of Engineering(STI),École Polytechnique Fédérale de Lausanne(EPFL),Station9,Lausanne CH-1015,Switzerlande-mail:lixincheng@Gherhardt Ribatski Department of Mechanical Engineering, Escola de Engenharia de São Carlos(EESC),University of São Paulo(USP), São Carlos,São Paulo13566-590,Brazile-mail:ribatski@p.brJohn R.Thome Laboratory of Heat and Mass Transfer(LTCM),Faculty of Engineering(STI),École Polytechnique Fédérale de Lausanne(EPFL),Station9,Lausanne CH-1015,Switzerlande-mail:john.thome@epﬂ.ch Two-Phase Flow Patterns and Flow-Pattern Maps: Fundamentals and Applications A comprehensive review of the studies of gas-liquid two-phaseﬂow patterns andﬂow-pattern maps at adiabatic and diabatic conditions is presented in this paper.Especially, besides other situations,this review addresses the studies on microscale channels,which are of great interest in recent years.First,a fundamental knowledge of two-phaseﬂow patterns and their application background is brieﬂy introduced.The features of two-phaseﬂow patterns andﬂow-pattern maps at adiabatic and diabatic conditions are reviewed,including recent studies for ammonia,new refrigerants,and CO2.Then,fun-damental studies of gas-liquidﬂow patterns andﬂow-pattern maps are presented.In the experimental context,studies ofﬂow patterns andﬂow-pattern maps in macro-and mi-croscale channels,across tube bundles,at diabatic and adiabatic conditions,under mi-crogravity and in complex channels are summarized.In addition,studies on highly vis-cous Newtonianﬂuids(non-Newtonianﬂuids are beyond the scope of this review)are also mentioned.In the theoretical context,modeling ofﬂow-regime transitions,speciﬁc ﬂow patterns,stability,and interfacial shear is reviewed.Next,ﬂow-pattern-based heat transfer and pressure drop models and heat transfer models for speciﬁcﬂow patterns such as slugﬂow and annularﬂow are reviewed.Based on this review,recommendations for future research directions have been given.͓DOI:10.1115/1.2955990͔1IntroductionGas-liquid two-phaseﬂows at both adiabatic and diabatic con-ditions are very complex physical processes since they combinethe characteristics of deformable interface,channel shape,ﬂowdirection,and,in some cases,the compressibility of one of thephases.In addition to inertia,viscous and pressure forces presentin a single-phaseﬂow and two-phaseﬂows are also affected bythe interfacial tension forces,the wetting characteristics of theliquid on the tube wall͑contact angle͒,and the exchange of mass,momentum,and energy between the liquid and vapor phases.De-pending on the operating conditions,such as pressure,tempera-ture,mass velocity,adiabatic or diabaticﬂow,channel orientation ͑the effect of gravity,which in nonvertical channels tends to pull the liquid to the bottom of the channel͒,andﬂuid properties ͑widely different combinations of different classes ofﬂuids such as air-water,steam-water and liquid and vapor phases of refriger-ants͒,various gas-liquid interfacial geometric conﬁgurations occurin two-phaseﬂow systems.These are commonly referred to asﬂow patterns orﬂow regimes.Many differentﬂow patterns havebeen deﬁned by various researchers͓1–4͔,and the nature of theﬂow patterns varies with channel geometry and size͑macro-andmicroscale͒,ﬂuid physical properties,ﬂow orientation,ﬂow pa-rameters,adiabatic or diabatic condition,etc.Furthermore,tran-sient two-phaseﬂows andﬂow oscillations are also important top-ics but are beyond the scope of the present review.speedﬂow͑as in criticalﬂow͒partial vaporization of the liquidmay occur even though there is no heat addition.Gas dissolutionor desorption in the liquid phase may also contribute in some instances to mass exchange in gas-liquidﬂows,especially forﬂu-oroinerts.One example of adiabatic two-phaseﬂows is the trans-portation of gas-oil mixtures in pipelines.Diabatic two-phase ﬂows with heat transfer occur duringﬂow boiling,ﬂow conden-sation,or gas-liquid two-phaseﬂows with heat addition or re-moval.These are confronted in steam generators,boiling water reactors,boiling and condensation of refrigerants used in air con-ditioning,refrigeration and heat pump systems,petrochemical processes,and so on.Without knowing the localﬂow patterns, one cannot correctly calculate the thermal/hydraulic design pa-rameters.In fact,the physical mechanisms controlling two-phase pressure drops and heat transfer coefﬁcients are intrinsically re-lated to the localﬂow patterns͓1–4͔,͓10–23͔,and thusﬂow-pattern prediction is an important aspect of two-phase heat trans-fer and pressure drops.To predict localﬂow patterns,two-phaseﬂow-pattern maps are used.These are generally two-dimensional graphs with transition criteria to separate the areas corresponding to the variousﬂow regimes.Over the past decades,numerous studies ofﬂow patterns have been conducted for various tube conﬁgurations such as in-side vertical,horizontal,and inclined channels͑macro-and micro-channels͒and other complex geometries such as inside enhanced tubes,in compact heat exchangers,across tube bundles,and under microgravity conditions,for which numerousﬂow-pattern maps have been proposed.Mostﬂow-pattern maps have been developed for adiabatic conditions,e.g.,the Hewitt and Roberts͓5͔ﬂow-pattern map for vertical upﬂow and the Baker͓6͔,Taitel and Dukler͓7͔,Hashitume͓8͔,and Steiner͓9͔ﬂow maps for horizon-talﬂow,just to name a few.Regarding diabaticﬂow-pattern maps, they should include the effect of heatﬂux and dryout on theﬂow-pattern transition boundaries and revert to an adiabatic map when the heatﬂux tends to zero.In principle,adiabatic two-phaseﬂow maps are not applicable to diabatic conditions,although this is often done.Such extrapolation of adiabaticﬂow maps to diabatic conditions is,in general,not reliable and also lacks the inﬂuence of heat transfer on the localﬂow patterns and their transitions. With respect to diabatic two-phaseﬂows,one of the earliest di-abaticﬂow-pattern maps is that of Kattan–Thome–Favrat͓10–12͔, which was developed according to their experimental observa-tions and heat transfer data forﬁve refrigerants͑R-134a,R123, R402a,R404a,and R502͒under evaporation conditions.Their ﬂow map was then the basis of theirﬂow boiling heat transfer model for evaporation in horizontal tubes in the fully stratiﬁed,Published online July30,2008.Transmitted by Assoc.Editor J.N.Reddy.stratiﬁed-wavy,intermittent,and annularﬂow regimes and for an-nularﬂow with partial dryout at the top of the tube.Physically,itis connected to the local heat transfer characteristics and mecha-nisms by use of simpliﬁed two-phaseﬂow structures to accountfor any dry perimeter predicted to occur and may be applied toboth adiabatic and diabatic conditions.Since then,a number ofmodiﬁedﬂow maps have been developed for differentﬂuids such as R134a,R407c,R22,R410A,ammonia͑R717͒,and CO2͑R747͒under evaporation and/or condensation conditions͓13–23͔on the basis of the Kattan–Thome–Favratﬂow map.These will bediscussed in Secs.2–4.The vast majority of technical calculations on two-phaseﬂows are made without any reference whatsoever toﬂow patterns. Nearly all two-phase pressure drop correlations in the literature and reference books are purely empirical without reference to the ﬂow patterns that they cover.These include such leading methods as those of Martinelli and Nelson͓24͔,Lockhart and Martinelli ͓25͔,Chisholm͓26͔,Grönnerud͓27͔,Müller-Steinhagen and Heck͓28͔,and Friedel͓29͔.Furthermore,most of the leading ﬂow boiling heat transfer correlations do not contain any informa-tion on theﬂow patterns,such as those of Chen͓30͔,Shah͓31͔, Gungor and Winterton͓32͔,and Kandlikar͓33͔.Such methods are typically most accurate for annularﬂow,but in fact they cannot themselves identify when this regime occurs,nor do they use explicitly an annularﬂow structure in the prediction method. This poses the following question:Areﬂow patterns andﬂow-pattern maps helpful in practical design?Certainly,this seems to be the case.The relationships for two-phase pressure drops are likely to be signiﬁcantly different for aﬂow consisting of a dis-persion of bubbles͑bubblyﬂow͒than for aﬂow consisting of a liquidﬁlm on the channel wall with a central gas core͑annular ﬂow͒.Recent work has demonstrated that two-phase pressure drops can be more accurately predicted by giving attention to speciﬁcﬂow patterns in a generalﬂow-pattern-based model ͓22,34–36͔.Furthermore,models that have a sound theoretical basis are more likely to be reliable and generally applicable than those that are purely empirical.Calculation methods based on ﬂow patterns andﬂow-pattern maps accounting for two-phase ﬂow structure effects will ultimately supersede those ignoring the inﬂuence of theﬂow regimes.For heat transfer,the aforemen-tionedﬂow-pattern-based heat transfer models͓10–23͔provide more accurate heat transfer predictions and attempt to intrinsically relate the heat transfer mechanisms to the localﬂow patterns. Therefore,ﬂow patterns andﬂow-pattern maps play an important role in improving the prediction models for two-phase pressure drops and heat transfer coefﬁcients.The earliest papers onﬂow patterns andﬂow-pattern maps date back to the early1950s,and after that an avalanche of papers have been published on this subject.Numerous research reviews on ﬂow patterns have been presented by different authors.Rouhani and Sohal͓37͔presented an overall literature review covering commonly observedﬂow regimes in horizontal and vertical pipes, different types ofﬂow pattern maps,experimental techniques for direct and indirect determination ofﬂow regimes,ﬂow-regime transition criteria based on correlations and theoretical deriva-tions,and also the effects of wall roughness,heatﬂux,andﬂow accelerations onﬂow-regime transitions.Collier and Thome͓1͔, Carey͓2͔,Hewitt͓3͔,and Thome͓4͔also provided summaries or reviews on two-phaseﬂow patterns andﬂow maps.Generally, they provided an introduction to the fundamental knowledge for conventional size channels with various orientations,such as hori-zontal,vertical,and inclined channels.However,they did not pro-vide information on two-phaseﬂow patterns andﬂow maps in microscale channels.Therefore,this review also addresses the studies on microscale channels.In recent years,emphasis has been put on the characteristics of two-phaseﬂow and heat transfer in small and microscaleﬂow passages due to the rapid development of microscale devices ͓38–48͔.Due to the signiﬁcant differences of transport phenom-ena in microscale channels as compared to conventional size channels or macroscale channels,one very important issue should be clariﬁed about the distinction between microscale and macros-cale channels.However,a universal agreement is not clearly es-tablished in the literature.Instead,there are various deﬁnitions on this issue.Shah͓45͔deﬁned a compact heat exchanger as an exchanger with a surface area density ratioϾ700m2/m3.This limit trans-lates into a hydraulic diameter ofϽ6mm.According to this deﬁ-nition,the distinction between macro-and microscale channels is 6mm.Mehendale et al.͓46͔deﬁned various small and mini heat ex-changers in terms of hydraulic diameter D h:•micro heat exchanger:D h=1–100␮m•meso heat exchanger:D h=100␮m–1mm•compact heat exchanger:D h=1–6mm •conventional heat exchanger:D hϾ6mmAccording to this deﬁnition,the distinction between macro-and microscale channels is somewhere between1mm and6mm. Based on engineering practice and application areas such as refrigeration industry in the small tonnage units,compact evapo-rators employed in automotive,aerospace,air separation,and cryogenic industries,cooling elements in theﬁeld of microelec-tronics,and microelectromechanical systems͑MEMS͒,Kandlikar ͓38͔deﬁned the following ranges of hydraulic diameters D h, which are attributed to different channels:•conventional channels:D hϾ3mm•minichannels:D h=200␮m–3mm •microchannels:D h=10–200␮mAccording to this deﬁnition,the distinction between small and conventional size channels is3mm.There are several important dimensionless numbers,which are used to represent the feature ofﬂuidﬂow in microscale channels. According to these dimensionless numbers,the distinction be-tween macro-and microscale channels may be classiﬁed as well. Triplett et al.͓47͔deﬁnedﬂow channels with hydraulic diameters D h of the order of,or smaller than,the Laplace constant L,L=ͱ␴g͑␳L−␳G͒͑1͒as microscale channels,where␴is the surface tension,g is the gravitational acceleration,and␳L and␳G are,respectively,liquid and gas/vapor densities.Kew and Cornwell͓43͔earlier proposed the conﬁnement num-ber Co for the distinction of macro-and microscale channels,Co=1D hͱ4␴g͑␳L−␳G͒͑2͒which is actually based on the deﬁnition of the Laplace constant. Based on a linear stability analysis of stratiﬁedﬂow and the argument that neutral stability should consider a disturbance wavelength of the order of channel diameter,Brauner and Moalem-Maron͓48͔derived the Eotvös number Eöcriterion for the dominance of surface tension for microscale channels,Eo¨=͑2␲͒2␴͑␳L−␳G͒D h2gϾ1͑3͒The deﬁnition of a microscale channel is quite confusing be-cause there are different criteria available as described above. Cheng and Mewes͓42͔made a comparison of these different criteria for microscale channels.Figure1shows their comparable results for water and CO2,which shows the big difference among these criteria.So far,the distinction of microscale channels is still in dispute.In this review,the distinction between macro-and mi-croscale channels by the threshold diameter of3mm is adopted due to the lack of a well-established theory but is in line with those recommended by Kandlikar͓38͔.Using this threshold diam-eter enables more relevant studies to be included.So far,there is a little information on two-phaseﬂow patterns at microgravity conditions and in complex conﬁgurations such as tube bundles,enhanced channels,U-bends,heat exchangers,and so on.In addition,only a limited number of studies have been done on two-phaseﬂow patterns during condensation.Further-more,a number of theoretical studies have been performed on speciﬁcﬂow patterns andﬂow-pattern instabilities.Therefore,the present paper aims to address many of these related topics and to provide a comprehensive review of what has been learned from this research.It should be mentioned that only Newtonian and highly viscous Newtonianﬂuids are addressed here͑non-Newtonianﬂuids are beyond the scope of this review͒.In what follows,different aspects ofﬂow patterns in a general scope areﬁrst presented,and published literatures are mentioned in accordance to their relevance to the speciﬁc topics.Then,sev-eral leadingﬂow-pattern maps will be presented together with a discussion of their limitations and future requirements.Following this,a detailed review of the studies classiﬁed according to spe-ciﬁc topics will be presented.Finally,attention will be turned to ﬂow-pattern-based heat transfer and pressure drop models.2Schematics of Two-Phase Flow Patterns and Flow-Pattern MapsFirst,because of the variety of names and deﬁnitions ofﬂow patterns,a discussion ofﬂow patterns in vertical and horizontal tubes for adiabatic and diabatic conditions is presented.Then, several leadingﬂow-pattern maps are presented and their limita-tions are discussed.2.1Flow Patterns.In this section,ﬂow patterns for adiabatic and diabatic conditions are described and discussed by category. Vertical Adiabatic Two-Phase Flows.Figure2͑a͒shows the most commonly observed two-phaseﬂow patterns in a vertical tube.Bubblyﬂow occurs when a relatively small quantity of gas or vapor is mixed with a moderateﬂow rate of liquid.Increasingbubbles separated by liquid slugs.Each of these bubbles occupiesnearly the entire channel cross section except for a thin liquidlayer on the wall,and their length is typically one to two times thechannel diameter.An increase in both gas and liquidﬂow rateswill lead to an unstableﬂow pattern,which is called churnﬂow.Arelatively higher gasﬂow rate generates a wispy-annularﬂow pat-tern,which is not observed or recognized as such in many studies.Very high gasﬂow rates may cause some of the liquidﬂow to beentrained as droplets carried along with the continuous gas phasein annularﬂows.At even higher gasﬂow rates,all the liquid issheared from the wall to form the mistﬂow regime.Horizontal Adiabatic Two-Phase Flows.Figure2͑b͒shows themost commonly observedﬂow patterns for cocurrentﬂow of gasand liquid in a horizontal tube.Two-phaseﬂow patterns in a hori-zontal tube are similar to those in a vertical tube,but distributionof the liquid is inﬂuenced by gravity.In general,mostﬂow pat-terns in horizontal tubes show a nonsymmetrical structure,whichis due to the effect of gravity on the different densities of thephases.This generates a tendency toward stratiﬁcation in the ver-tical direction,with the liquid having a tendency to occupy thelower part of the channel and the gas,the upper part.Stratiﬁedﬂow is usually observed at relatively lowﬂow rates of gas and Fig.1Comparison of various deﬁnitions of threshold diam-eters for microscale channels:…a…water and…b…CO2by Chengand Mewes†42‡Fig.2…a…Schematic ofﬂow patterns in vertical upward gas-liquid cocurrentﬂow;…b…schematic ofﬂow patterns in horizon-tal gas-liquid cocurrentﬂow†1‡liquid.As the gas and liquid ﬂow rates are increased,the smooth interface of the liquid becomes rippled and wavy.This pattern is called a stratiﬁed-wavy ﬂow.If the liquid ﬂow rate is further in-creased while the vapor ﬂow is maintained low,an intermittent ﬂow pattern will develop in which gas pockets or plugs are en-trapped in the main liquid ﬂow and then a plug ﬂow will develop.If ﬂow rates of gas and liquid increase together,a so called slug ﬂow regime will develop.The main distinction between slug and plug ﬂow is in the more pronounced nature of intermittent liquid mass separated by a larger gas bubble.With further increase in the gas ﬂow alone,annular ﬂow will develop.The gas ﬂow in the core of an annular ﬂow may entrain a portion of the liquid phase in the form of droplets,and in some cases the liquid ﬁlm may also entrain some small bubbles.At relatively large liquid ﬂow rates,with little gas ﬂow,one would observe the so called dispersed bubble ﬂow in which the liquid phase is in the dispersed form of the scattered bubbles.At very high gas ﬂow rates,the mist ﬂow is reached,which can begin at the top perimeter where the annular ﬁlm is the thinnest and then progress downstream to the bottom perimeter.Flow Patterns in Inclined Channels .There are relatively few experimental observations on ﬂow patterns in inclined tubes,not-withstanding the technical importance of such ﬂows.Hewitt ͓3͔summarized this topic brieﬂy.In short,ﬂow patterns in inclined channels seem to have the same basic structures as in vertical and horizontal ﬂows except for the limitation or total suppression of the churn regime.Flow Patterns in Other Applications .A limited amount of in-formation is available in the literature in a variety of other speciﬁc applications,which are necessarily mentioned here,such as verti-cal downward ﬂow and tube bundles.Collier and Thome ͓1͔pre-sented a brief introduction for rectangular channels,internal grooves,helical inserts,obstructions,expansions,contractions,bends,coils,and annuli.Rounhani and Sohal ͓37͔presented a brief summary of downward cocurrent ﬂow.Relatively few stud-ies on ﬂow patterns in cocurrent downward ﬂow are reported in the literature.However,all of the ﬂow patterns of cocurrent up-ward ﬂow may also appear in the downward ﬂow situations.Hewitt ͓3͔presented a brief summary of ﬂow patterns in complex geometries such as in rod bundles and inside shell and tube heat exchangers.Thome ͓4͔provided some detailed information on ﬂow patterns and ﬂow maps for two-phase ﬂows over horizontal tube bundles.However,there is a scarcity of information on these topics.Flow Patterns in Countercurrent Flows .There is very little published information regarding ﬂow patterns in countercurrent ﬂow situations.Rounhani and Sohal ͓37͔also presented a brief summary of countercurrent ﬂows.In general,ﬂow regimes in countercurrent ﬂows have a very limited range of existence due to the fact that a continuous increase in the ﬂow rate of either phase would lead to so called ﬂooding,which means that the passage of the other phase would be blocked and cocurrent ﬂow would be established.In horizontal channels,countercurrent ﬂow may exist only as a stratiﬁed-smooth or stratiﬁed-wavy ﬂow.In vertical channels,it exists only for downward liquid ﬂow against rising vapor.The observed patterns are limited to annular,churn,and plug ﬂows.So far,there is a scarcity of information on this topic.Flow Patterns at Diabatic Conditions .At diabatic conditions,two-phase heat transfer coefﬁcients and pressure drops are closely related to the local ﬂow patterns and vice versa.Therefore,ﬂow patterns are very important in the heat transfer and pressure drop predictions.For ﬂow boiling ͑evaporation ͒,consider a vertical tube heated uniformly over its length with a low heat ﬂux and fed with sub-cooled liquid at its base at such a rate that the liquid is totally evaporated over the length of the tube.Figure 3shows the ﬂow patterns in diagrammatic form,the various ﬂow patterns that may be encountered over the length of a vertical tube heated by a uniform heat ﬂux,together with the corresponding heat transfer regimes.Figure 4shows a schematic representation of a horizon-tal tubular channel heated by a uniform heat ﬂux and fed with subcooled liquid.Flow patterns formed during evaporation in a horizontal tube may be inﬂuenced by departures from thermody-namic and hydrodynamic equilibrium.Asymmetric phase distribu-tions and stratiﬁcation introduce additional complications.Impor-tant points to note from a heat transfer viewpoint are the possibility of intermittent drying and rewetting of the upper sur-faces of the tube in slug and wavy ﬂows and the progressive dryout over long tube lengths of the upper circumference of the tube wall in annular ﬂow.At higher inlet liquid velocities,the inﬂuence of gravity is less obvious,the phase distribution be-comes more symmetrical,and the ﬂow patterns become closer to those as in vertical ﬂow.For condensation,Fig.5illustrates the ﬂow patterns typically observed during condensation inside a horizontal tube ͓49͔.At the inlet,ﬁlm condensation around the circumference of the tube pro-Fig.3Schematic of ﬂow patterns and the corresponding heat transfer mechanisms for upward ﬂow boiling in a vertical tube †1,2‡Fig.4Schematic of ﬂow patterns and the corresponding heat transfer mechanisms and qualitative variation of the heat trans-fer coefﬁcients for ﬂow boiling in a horizontal tube †1,2‡duces an annularﬂow,with some droplets entrained in the central high velocity vapor core.As condensation continues,the vapor velocity falls and reduces the inﬂuence of vapor shear on the condensate,and the inﬂuence of gravity forces increases.At high ﬂow rates,slug and bubbleﬂows are eventually reached,while at lowﬂow rates large magnitude waves and then stratiﬁedﬂow are formed.2.2Flow-Pattern Maps.Flow-pattern maps may be classi-ﬁed primarily into two types:empiricalﬂow-pattern maps,whichare generallyﬁtted to the observedﬂow-pattern database and the-oretical or semitheoreticalﬂow-pattern maps whose transitions are predicted from physical models of theﬂow phenomena.Theoret-ical or semitheoreticalﬂow-pattern maps are developed according to theﬂow structure and are sometimes related to heat transfer mechanisms and diabatic ually,only twoﬂow parameters are used to deﬁne a coordinate system on which the boundaries between the differentﬂow patterns are charted,such as the superﬁcial gas and liquid velocities.Transition boundaries are then proposed to distinguish the location of the variousﬂow re-gimes as in a classical map.Mostﬂow maps are only valid for a speciﬁc set of conditions and/orﬂuids,although efforts are made to propose generalizedﬂow maps.In this section,only several leadingﬂow-pattern maps are presented.Generally,ﬂow-pattern maps for other applications such as microscale channels,en-hanced heat transfer tubes,compact heat exchangers,and tube bundles and at microgravity conditions have been proposed by modiﬁcation of these leadingﬂow maps.Empirical Flow-Pattern Maps.One of the best known empiri-calﬂow-pattern maps for horizontalﬂow is that of Baker͓6͔shown in Fig.6.It was based on observations of cocurrentﬂow of gaseous and condensate petroleum products in horizontal pipes and was constructed with two parameter groupsG G/␭and G L␺͑where G G and G L are gas and liquid mass velocities,respec-tively͒,taking into account their physical properties by introduc-ing the following parameters:␭=ͩ␳G␳A␳L␳Wͪ1/2͑4͒␺=ͩ␴W␴ͪͫͩ␮L␮Wͪͩ␳W␳Lͪ2ͬ1/3͑5͒where␳A,␳W,␴W,and␮W are the density of air,the density ofwater,the surface tension of water,and the dynamic viscosity ofwater,respectively,at1atm pressure and room temperature while␳L,␳G,␴,and␮L are the liquid density,gas density,surface ten-sion,and liquid viscosity,respectively.The correction factors␭and␺had previously been used for correlating data onﬂoodingpoints in distillation columns.Although Baker’sﬂow map coordi-nates include these apparently relevant variables for scaling a va-riety of different conditions,later investigations have shown thatthis map does not adequately predict horizontalﬂow regimes innumerous situations,as pointed out by Rounhani and Sohal͓37͔.One of the leading empiricalﬂow-pattern maps for vertical up-ﬂows is that of Hewitt and Roberts͓5͔shown in Fig.7.On thismap,the coordinates are the superﬁcial momentumﬂuxes of therespective phases.Both air-water and steam-water data could berepresented in terms of this plot,which thus covers a reasonablywide range ofﬂuid physical properties.All the transitions areassumed to depend on the phase momentumﬂuxes.Wispy-annularﬂow is a subcategory of annularﬂow,which occurs athigh massﬂux when the entrained drops are said to appear aswisps or elongated droplets.Generally,the accuracy in determining transition lines on aﬂowmap is in part dependent on the number of experiments carried outand on the adopted coordinate systems as well.There are manyother coordinate systems forﬂow-pattern maps used by differentinvestigators,for example,superﬁcial gas and liquid velocitiesu GS and u LS͑m/s͒,and mass velocities G͑kg/m2s͒versus vaporqualities x.According to Troniewski and Ulbrich͓50͔,the coor-dinates used inﬂow maps may be divided into three groups:͑1͒Phase velocities orﬂuxes:gas and liquid superﬁcial veloci-ties u GS and u LS͑m/s͒or gas and liquid superﬁcial massﬂuxes G GS and G LS͑kg/m2s͒and gas and liquid massﬂowrates M G and M L͑kg/s͒.Use of these parameters,while Fig.5Schematic ofﬂow patterns for horizontal gas-liquidcocurrentﬂow in condensation†49‡Fig.6The Baker†6‡ﬂow-pattern map for horizontal gas-liquidcocurrentﬂowFig.7The Hewitt and Roberts†5‡ﬂow-pattern map for verticalupward gas-liquid cocurrentﬂowundoubtedly being the most convenient,does not ensure creation of a universal ﬂow-pattern map for different two-phase mixtures.͑2͒Quantities referring to the two-phase ﬂow homogeneousmodel are the transformations of the parameters from group ͑1͒such as total velocity u T ,total mass ﬂux G T ,Froude number based on total velocity Fr T ,void fraction ␧,and quality x ,and they are only useful for the description of some ﬂow-pattern maps.͑3͒Parameters including the physical properties of phases suchas liquid and gas Reynolds numbers Re L and Re G ,Baker correction factors ␭and ␺,gas and liquid kinetic energies E G and E L ,and others;this formulation gives the best pos-sibility for attaining a universal ﬂow-pattern map.A summary of the coordinates used in ﬂow maps can be found in Refs.͓50,51͔.Theoretical or Semitheoretical Flow-Pattern Maps .There have been various attempts at a theoretical or semitheoretical descrip-tion of ﬂow-pattern transitions.For such a description to be suc-cessful,it should be suitable for extrapolation to a wide range of conditions.Perhaps the most comprehensive treatment of ﬂow-pattern transitions in horizontal ﬂow on a semitheoretical basis is that of Taitel and Dukler ͓7͔.It has been proven successful in predicting a fairly wide range of system conditions.Figure 8shows the Taitel and Dukler ﬂow-pattern map.The parameter groups,which are based on semitheoretical derivations for differ-ent ﬂow-pattern transitions in horizontal or slightly inclined chan-nels ͑␪is the angle of inclination ͒,are as follows:X =ͫ͑dp /dz ͒L ͑dp /dz ͒Gͬ1/2͑6͒Fr =G G͓␳G ͑␳L −␳G ͒Dg cos ␪͔1/2͑7͒T =͉ͫ͑dp /dz ͒L ͉g ͑␳L −␳G ͒cos ␪ͬ1/2͑8͒K =FrͫG L D ␮Lͬ1/2͑9͒where X is the Martinelli parameter,͑dp /dz ͒L is the frictional pressure gradient as if the liquid in the two-phase ﬂow were ﬂow-ing alone in the tube,͑dp /dz ͒G is the frictional pressure gradient as if the gas in the two-phase ﬂow were ﬂowing alone in the tube,Fr is theFroude number,D is the tube diameter,g is the accelera-tion due to gravity,␳L is the liquid density,␳G is the gas density,and ␮L is the liquid viscosity.They suggested the K versus X coordinate with a theoretically derived boundary curve,C ,for transition from stratiﬁed-smooth to stratiﬁed-wavy ﬂow.The Fr versus X relationship was proposed for the transitions between stratiﬁed-wavy,annular-dispersed ͑droplets ͒,dispersed bubble,and intermittent ͑plug or slug ͒ﬂows.The theoretically determined transition curves A and B ͑at X =1.6͒between the said regimes were also given in those coordinates.Finally,T versus X was proposed for deﬁning the transition between dispersed bubble and intermittent ͑plug or slug ͒ﬂow regimes with the transition line D .The transition curves shown in Fig.8are for the case of zero inclination angle ͑horizontal ͒.All the transition criteria used by Taitel and Dukler have some theoretical bases,although they are sometimes rather tenuous.As pointed out by Hewitt ͓3͔,it should be remembered that there is an essential arbitrariness in the inter-pretation of ﬂow-pattern data,and thus it is unlikely that perfect prediction methods will ever emerge.Diabatic Flow-Pattern Maps .In the case of diabatic two-phase ﬂows such as ﬂow boiling ͑evaporation ͒and condensation,very few maps have been proposed.Important factors inﬂuencing these ﬂows and their transitions are nucleate boiling,evaporation or condensation of liquid ﬁlms on what could otherwise be dry parts of the perimeter,and acceleration or deacceleration of the ﬂows.For example,nucleate boiling in an annular ﬁlm tends to increase the ﬁlm’s thickness and change the void proﬁle near the wall,or vigorous nucleate boiling in an otherwise stratiﬁed ﬂow can com-pletely wet the upper perimeter,thus increasing liquid entrainment in the vapor core.It is desirable that diabatic ﬂow-pattern maps include the inﬂuences of heat ﬂux,dryout,etc.,on the ﬂow-pattern transition boundaries.One such map is that of Kattan–Thome–Favrat ͓10–12͔for evaporation inside horizontal channels.This was developed based on ﬁve refrigerants ͑pure ﬂuids R134a and R123,the azeotropic refrigerant mixture R502,and two near azeo-tropic mixtures R402A and R404A ͒under ﬂow boiling conditions by modiﬁcation of the Steiner map ͓9͔,which in turn is a modiﬁed Taitel–Dukler ﬂow map ͓7͔.Figure 9shows the Kattan–Thome–Favrat ﬂow-pattern map ͑solid lines ͓͒10–12͔compared to the Steiner map ͓9͔͑dashed lines ͒evaluated for R410A at T sat =5°C in a 13.84mm internal diameter tube at different heat ﬂuxes ͓36͔.In the Kattan–Thome–Favrat ﬂow map,stratiﬁed,stratiﬁed-wavy,intermittent,annular,bubbly,and mist ﬂows are encountered.The map includes a diabatic method for predicting the anticipation of the onset of dryout at the top of the tube in evaporating annularFig.8The Taitel and Dukler †7‡ﬂow-pattern map for horizontal gas-liquid cocurrent ﬂow:coordinates of curves A and B are Fr versus X ,coordinates of curve C are K versus X ,and coordinates of curve D are T versus X。

光纤通信英文版常见中英对照单词表

AAbsorption coefficient 吸收系数ac alternating current 交变电流交流Acoustic phonon 声学声子Active component 有源器件AM amplitude modulation 幅度调制AM，FM，PM：幅度/频率/相位调制AON all-optical network 全光网络AOTF acoustic optic tunable filter 声光调制器APD avalanche photodiode 雪崩二极管AR coatings antireflection coatings 抗反膜ASE amplified spontaneous emission 放大自发辐射ASK amplitude shift keying 幅移键控ASK/FSK/PSK 幅/频/相移键控ATM asynchronous transfer mode 异步转移模式Attenuation coefficient 衰减系数Attenuator 衰减器Auger recombination：俄歇复合AWG arrayed-waveguide grating 阵列波导光栅BBand gap：带隙Band pass filter 带通滤波器Beam divergence 光束发散BER bit error rate 误码率BER：误码率BH buried heterojunction 掩埋异质结Binary representation 二进制表示方法Binary 二进制Birefringence 双折射Birefringence双折射Bitrate-distance product 比特距离的乘积Block diagram 原理图Boltzman statistics：玻尔兹曼统计分布BPF band pass filter 带通滤波器Bragg condition 布拉格条件Bragg diffraction 布拉格衍射Brillouin scattering 布里渊散射Brillouin shift 布里渊频移Broad area 宽面Buried heterostructure 掩埋异质结CC3 cleaved-coupled cavity 解理耦合腔Carrier lifetime：载流子寿命CATV common antenna cable television 有线电视CDM code division multiplexing 码分复用Characteristics temperature 特征温度Chirp 啁啾Chirped Gaussian pulse 啁啾高斯脉冲Chromatic dispersion 色度色散Chromatic dispersion 色度色散Cladding layer：包层Cladding 包层CNR carrier to noise ratio 载噪比Conduction band：导带Confinement factor 限制因子Connector 连接头Core cladding interface 纤芯包层界面Core-cladding interface 芯层和包层界面Coupled cavity 耦合腔CPFSK continuous-phase frequency-shift keying 连续相位频移键控Cross-phase modulation 交叉相位调制Cross-talk 串音CSO Composite second order 复合二阶CSRZ：载波抑制归零码Cutoff condition 截止条件CVD chemical vapour deposition 化学汽相沉积CW continuous wave 连续波Cylindrical preform：预制棒DDBR distributed Bragg reflector 分布布拉格反射DBR: distributed Bragg reflector 分布式布拉格反射器dc direct current 直流DCF dispersion compensating fiber 色散补偿光纤Depressed-cladding fiber: 凹陷包层光纤DFB distributed feedback 分布反馈DFB: Distributed Feedback 分布式反馈Differential gain 微分增益Differential quantum efficiency 微分量子效率Differential-dispersion parameter：微分色散参数Diffusion 扩散Digital hierarchy 数字体系DIP dual in line package 双列直插Direct bandgap：直接带隙Directional coupler 定向耦合器Dispersion compensation fiber：色散补偿光纤Dispersion decreasing fiber：色散渐减光纤Dispersion parameter：色散参数Dispersion shifted fiber 色散位移光纤Dispersion slope 色散斜率Dispersion slope：色散斜率Dispersion-flatten fiber：色散平坦光纤Dispersion-shifted fiber：色散位移光纤Double heterojunction 双异质结Double heterostructure：双异质结Doubly clad：双包层DPSK differential phase-shift keying 差分相移键控Driving circuit 驱动电路Dry fiber 无水光纤DSF dispersion shift fiber 色散位移光纤DWDM dense wavelength divisionmultiplexing/multiplexer密集波分复用/器DWDM: dense wavelength division multiplexing密集波分复用E~GEDFA erbium doped fiber amplifier 掺铒光纤激光器Edge emitting LED 边发射LEDEdge-emitting 边发射Effective index 有效折射率Eigenvalue equation 本征值方程Elastic scattering 弹性散射Electron-hole pairs 电子空穴对Electron-hole recombination 电子空穴复合Electron-hole recombination：电子空穴复合Electrostriction 电致伸缩效应Ethernet 以太网External cavity 外腔External quantum efficiency 外量子效率Extinction ratio 消光比Eye diagram 眼图FBG fiber-bragg grating 光纤布拉格光栅FDDI fiber distributed data interface 光纤数据分配接口FDM frequency division multiplexing频分复用FDM：频分复用Fermi level 费米能级Fermi level：费米能级Fermi-Dirac distribution：费米狄拉克分布FET field effect transistor 场效应管Fiber Manufacturing：光纤制作Field radius 模场半径Filter 滤波器Flame hydrolysis 火焰裂解FM frequency modulation 频率调制Forward-biased ：正向偏置FP Fabry Perot 法布里-珀落Free spectral range 自由光谱范围Free－space communication 自由空间光通信系统Fresnel transmissivity 菲涅耳透射率Front end 前端Furnace 熔炉FWHM full width at half maximum 半高全宽FWHM: 半高全宽FWM four-wave mixing 四波混频Gain coefficient 增益系数Gain coupled 增益耦合Gain-guided semiconductor laser 增益波导半导体激光器Germania 锗GIOF graded index optical fiber 渐变折射率分布Graded-index fiber 渐变折射率光纤Group index 群折射率GVD group-velocity dispersion 群速度色散GVD: 群速度色散H~LHBT heterojunction-bipolar transistor异质结双极晶体管HDTV high definition television 高清晰度电视Heavy doping：重掺杂Heavy-duty cable 重型光缆Heterodyne 外差Heterojunction：异质结HFC hybrid fiber-coaxial 混合光纤/电缆Higher-order dispersion 高阶色散Highpass filter 高通滤波器Homodyne 零差Homojunction：同质结IC integrated circuit 集成电路IM/DD intensity modulation with direct detection 强度调制直接探测IM/DD: 强度调制/直接探测IMD intermodulation distortion 交互调制失真Impulse 冲激Impurity 杂质Index-guided 折射率导引Indirect bandgap：非直接带隙Inelastic scattering 非弹性散射Inhomogeneous非均匀的Inline amplifier 在线放大器Intensity noise 强度噪声Intermodal dispersion：模间色散Intermode dispersion 模间色散Internal quantum efficiency：内量子效率Intramodal dispersion: 模内色散Intramode dispersion 模内色散Intrinsic absorption 本征吸收ISDN integrated services digital network 综合业务数字网ISI intersymbol interference 码间干扰Isotropic 各向同性Jacket 涂层Jitter 抖动Junction：结Kinetic energy：动能Lambertian source 朗伯光源LAN local-area network 局域网Large effective-area fiber 大有效面积发光Laser threshold 激光阈值Laser 激光器Lateral mode 侧模Lateral 侧向Lattice constant：晶格常数Launched power 发射功率LD laser diode 激光二极管LD：激光二极管LED light emitting diode 发光二极管LED: 发光二极管L-I light current 光电关系Light-duty cable 轻型光缆Linewidth enhancement factor 线宽加强因子Linewidth enhancement factor 线宽增强因子Linewidth 线宽Longitudinal mode 纵模Longitudinal model 纵模Lowpass filter 低通滤波器LPE liquid phase epitaxy 液相外延LPE：液相外延M~NMacrobending 宏弯MAN metropolitan-area network 城域网Material dispersion 材料色散Material dispersion：材料色散Maxwell’s equations 麦克斯韦方程组MBE molecular beam epitaxy 分子束外延MBE：分子束外延MCVD Modified chemical vapor deposition改进的化学汽相沉积MCVD：改进的化学汽相沉积Meridional rays 子午光线Microbending 微弯Mie scattering 米氏散射MOCVD metal-organic chemical vapor deposition金属有机物化学汽相沉积MOCVD：改进的化学汽相沉积Modal dispersion 模式色散Mode index 模式折射率Modulation format 调制格式Modulator 调制器MONET Multiwavelength optical network 多波长光网络MPEG motion-picture entertainment group视频动画专家小组MPN mode-partition noise 模式分配噪声MQW multiquantum well 多量子阱MQW: 多量子阱MSK minimum-shift keying 最小频偏键控MSR mode-suppression ratio 模式分配噪声MSR: Mode suppression ratio 模式抑制比Multimode fiber 多模光纤MZ mach-Zehnder 马赫泽德NA numerical aperture 数值孔径Near infrared 近红外NEP noise-equivalent power 等效噪声功率NF noise figure 噪声指数Nonradiative recombination 非辐射复合Nonradiative recombination：非辐射复合Normalized frequency 归一化频率NRZ non-return to zero 非归零NRZ：非归零码NSE nonlinear Schrodinger equation 非线性薛定额方程Numerical aperture 数值孔径Nyquist criterion 奈奎斯特准则O P QOC optical carrier 光载波OEIC opto-electronic integrated circuit 光电集成电路OOK on-off keying 开关键控OOK：通断键控OPC optical phase conjugation 光相位共轭Optical mode 光模式Optical phase conjugation 光相位共轭Optical soliton 光孤子Optical switch 光开关Optical transmitter 光发射机Optical transmitter：光发射机OTDM optical time-division multiplexing 光时分复用OVD outside-vapor deposition 轴外汽相沉积OVD：轴外汽相沉积OXC optical cross-connect 光交叉连接Packaging 封装Packet switch 分组交换Parabolic-index fiber 抛物线折射率分布光纤Passive component 无源器件PCM pulse-code modulation 脉冲编码调制PCM：脉冲编码调制PCVD：等离子体化学汽相沉积PDF probability density function 概率密度函数PDM polarization-division multiplexing 偏振复用PDM：脉冲宽度调制Phase-matching condition 相位匹配条件Phase-shifted DFB laser 相移DFB激光器Photon lifetime 光子寿命PMD 偏振模色散Polarization controller 偏振控制器Polarization mode dispersion：偏振模色散Polarization 偏振PON passive optical network 无源接入网Population inversion：粒子数反转Power amplifier 功率放大器Power-conversion efficiency 功率转换效率PPM：脉冲位置调制Preamplifer 前置放大器PSK phase-shift keying 相移键控Pulse broadening 脉冲展宽Quantization noise 量化噪声Quantum efficiency 量子效率Quantum limit 量子极限Quantum limited 量子极限Quantum noise 量子噪声RRA raman amplifier 喇曼放大器Raman scattering 喇曼散射Rate equation 速率方程Rayleigh scattering 瑞丽散射Rayleigh scattering 瑞利散射Receiver sensitivity 接收机灵敏度Receiver 接收机Refractive index 折射率Regenerator 再生器Repeater spacing 中继距离Resonant cavity 谐振腔Responsibility 响应度Responsivity 响应度Ridge waveguide laser 脊波导激光器Ridge waveguide 脊波导RIN relative intensity noise 相对强度噪声RMS root-mean-square 均方根RZ return-to-zero 归零RZ: 归零码SSAGCM separate absorption, grading, charge, and multiplication吸收渐变电荷倍增区分离APD的一种SAGM separate absorption and multiplication吸收渐变倍增区分离APD的一种SAM separate absorption and multiplication吸收倍增区分离APD的一种Sampling theorem 抽样定理SBS 受激布里渊散射SBS stimulated Brillouin scattering 受激布里渊散射SCM subcarrier multiplexing 副载波复用SDH synchronous digital hierarchy 同步数字体系SDH：同步数字体系Self-phase modulation 自相位调制Sellmeier equation：塞米尔方程Sensitivity degradation 灵敏度劣化Sensitivity 灵敏度Shot noise 散粒噪声Shot noise 散粒噪声Single-mode condition 单模条件Sintering ：烧结SIOF step index optical fiber 阶跃折射率分布SLA/SOA semiconductor laser/optical amplifier 半导体光放大器SLM single longitudinal mode 单纵模SLM: Single Longitudinal mode单纵模Slope efficiency 斜率效率SNR signal-to-noise ratio 信噪比Soliton 孤子SONET synchronized optical network 同步光网络SONET：同步光网络Spectral density：光谱密度Spontaneous emission：自发辐射Spontaneous-emission factor 自发辐射因子SRS 受激喇曼散射SRS stimulated Raman scattering 受激喇曼散射Step-index fiber 阶跃折射率光纤Stimulated absorption：受激吸收Stimulated emission：受激发射STM synchronous transport module 同步转移模块STM：同步转移模块Stripe geometry semiconductor laser 条形激光器Stripe geometry 条形STS synchronous transport signal 同步转移信号Submarine transmission system 海底传输系统Substrate:衬底Superstructure grating 超结构光栅Surface emitting LED 表面发射LEDSurface recombination：表面复合Surface-emitting 表面发射TTCP/IP transmission control protocol/internet protocol传输控制协议/互联网协议TDM time-division multiplexing 时分复用TDM：时分复用TE transverse electric 横电模Ternary and quaternary compound：三元系和四元系化合物Thermal equilibrium：热平衡Thermal noise 热噪声Thermal noise 热噪声Threshold current 阈值电流Timing jitter 时间抖动TM transverse magnetic 横磁Total internal reflection 全内反射Transceiver module 收发模块Transmitter 发射机Transverse 横向Transverse mode 横模TW traveling wave 行波U ~ ZVAD vapor-axial epitaxy 轴向汽相沉积VAD：轴向沉积Valence band：价带VCSEL vertical-cavity surface-emitting laser垂直腔表面发射激光器VCSEL: vertical cavity surface-emitting lasers 垂直腔表面发射激光器VPE vapor-phase epitaxy 汽相沉积VPE：汽相外延VSB vestigial sideband 残留边带Wall-plug efficiency 电光转换效率WAN wide-area network 广域网Waveguide dispersion 波导色散Waveguide dispersion：波导色散Waveguide imperfection 波导不完善WDMA wavelength-division multiple access 波分复用接入系统WGA waveguide-grating router 波导光栅路由器White noise 白噪声XPM cross-phase modulation 交叉相位调制YIG yttrium iron garnet 钇铁石榴石晶体Zero-dispersion wavelength 零色散波长Zero-dispersion wavelength：零色散波长。

核磁共振分子运动学分析实验指导说明书

Diffusion experiments with Vnmrj 2.2C and 2.2D.E. Alvarado. University of Michigan. 04/12/10The diffusion coefficient of a molecule in solution depends on its effective molecular weight, size and shape, and can be used to estimate its relative molecular size (its hydrodynamic radius). It has applications in organic and inorganic chemistry3,5, for example to determine molecular weight in polymers, biopolymers and other aggregated materials. It can also be used to study molecular interactions and complexation processes in chemistry and to determine association constants. Recently, a method to estimate the molecular mass of small molecules in dilute aqueous and organic solutions was developed8.The present manuscript refers to diffusion experiments with Vnmrj 2.2C and 2.2D and Chempack 4.1. The software contains several pulse sequences for different experiments. Check the Vnmr manual for details. Here we will use the the pulse sequence DgcsteSL_cc (DOSY gradient compensated stimulated echo with spin lock and convection compensation), which is an enhancement of the classical PGSE (Pulsed Gradient Spin-Echo) pulse sequence.The PGSE pulse sequence, as originally proposed by Stejskal and Tanner 40 years ago is perhaps the easiest to understand, see the Figure 1 below. Briefly, after applying a 90° pulse, the nuclear spins of the sample will start precessing along the main magnetic field and dephase according to their absorption frequencies at this field. Then, a magnetic field gradient of strength gzlvl1 and duration gt1 is applied along the z axis of the tube and the spins will now be dephased due to their location in the gradient. After a short delay, a 180° pulse is applied that has the effect of inverting the precession direction. If the spins have not undergone translational motion along the z axis, the second applied gradient will be identical to the first, canceling its effect and the spins refocus (produce a spin- echo). However, if there was motion the effective magnetic field experienced by the spins during the second gradient will be different to the first and the spins will not completely refocus. The resulting signal will have a decreased intensity. The amount of attenuation is proportional to the displacement along the z axis, the gradient strength and the diffusion delay. Many other, more complex pulse sequences are available6,10,11, with portions aimed at increasing sensitivity and reducing artifacts, but they all follow the same principle.Figure 1. Classic PGSE pulse sequence.To measure molecular diffusion in a solution, a series of spectra with increasing gradient strengths must be recorded, Figure 2. By fitting the intensity (or integration) of the peaks to the Stejskal-Tanner function as described later, the diffusion constants can be calculated. And from the diffusion coefficients it is possible to calculate the hydrodynamic radius via the Stokes-Einstein equation2.This document contains only enough information to setup a basic experiment with Varian's Vnmrj software and analyze the results. Extensive discussions of diffusion experiments and its applications can be found in thechemical literature, in the references below and in advanced NMR texts.Figure 2. Sections of a DgcsteSL_cc experiment of a solution of sucrose in D2O. The anomeric hydrogen of sucrose at 5.42 ppm is shown on the left while the residual HDO signal at 4.79 ppm is shown on the right. Notice the sigmoidal shape of the decay and how the HDO signal decays faster.Experiment setupSome recommendations: If your solvent is organic, it is advisable to have TMS in solution so it can be used as a reference in the calculation8. If it is D2O, the residual solvent signal (HDO) can be used as the reference. It is very important to regulate and have a very stable and homogeneous temperature. Extreme (low and high) temperatures may produce convection currents inside the tube that are difficult to avoid and lead to errors. During the experiment, the parameters should be chosen so that the intensities of the signals of interest decay from 100% to about 20%.After inserting the sample and loading the shims, shim the magnet quickly (you will need to reshim later) and take a quick spectrum. Reduce the spectral width to your sample's needs and take a new spectrum. Display the optimized spectral width, transmitter offset, and gain (type sw?tof?gain?) and write down the results. When measuring diffusion on nuclei other than proton, the following parameters are also reset by the setup macro and the correct values will need to be reentered: tn, dn, tpwr and pw (set pw to the 90º value of the nucleus you want to measure). From the Experiments menu or from the Experiment Panel (on the Holding tab at the left side of vnmrj) select DgcsteSL_cc. Set sw, tof and gain to the values you just found (and do the same for the other parameters if the nucleus is not H1). Set the desired temperature, for example by typing “temp=25 su” on the command line, and while the temperature is stabilizing, adjust the remaining parameters that follow. Most of the parameters can be set from the Acquire, Pulse Sequence panel shown below.Of particular importance for this experiment are three parameters. The D iffusion delay (del) is the amount of time allowed for the molecules to diffuse. Larger molecules will move slower and may require long periods of time for an accurate measurement, while small molecules move faster and require short diffusion delays. If the diffusion delay is set too short, the peaks will not have enough time to decay sufficiently for an accurate determination; and if it is too long, the signals will decrease in intensity to zero well before the end of the experiment and the last few spectra will contain only noise. Additionally, the diffusion delay should not be too long because signal intensity also decreases due to relaxation during this delay and thermal convection processes have more time to interfere with the experiment. It is for those reasons that in general the diffusion delay should be between 50 and 200 ms. If more time is required, it is better to increase the diffusion gradient length (gt1) instead. For example, a gradient length of 2 ms with a delay of 400 ms is equivalent to a gradient of 4 ms with a delay of 200 ms. Good values to start for medium size organic molecules in low viscosity solvents are: diffusion gradient length = 2 ms, diffusion delay = 200 ms. Double the gradient length for water and other viscoussolvents. Change the values of these parameters in the parameter panel as shown.For this and other diffusion experiments we have to collect a series of spectra where the diffusion gradient (whose length we just defined above) has increasing gradient strengths. This is accomplished by setting up in an array the values of the Diffusion gradient level (gzlvl1) from 0 to the maximum value allowed by the gradient amplifier. In our Inovas and 400MRs the maximum value is 2048. These numbers are in an arbitrary scale without units provided by a digital-to-analog converter (DAC). The calibration for these DAC numbers to gauss/cm was performed by the NMR Facility staff and is shown in the parameter panel as “DAC to G”. For example, in our Inova 500 with the “id” probe, DAC_to_G has been calibrated with D2O at 25 °C and has a value of 0.00961 gauss/cm·DAC. Thus the maximum gradient for this probe/instrument is 19.7 gauss/cm or 1.97 T/m. To setup the array you can either click on [Setup coarse gradient array] or on [Setup DOSY using conditions above]. The first sets up an array of only 8 gradients while the second sets up an array using the Number of increments shown above (15 is the default). The coarse array is useful for running a quick experiment to determine if the diffusion delay and diffusion length are appropriate to the sample.Before starting the experiment select Alternate gradient signs on odd scans and Lock gating during gradients. If solvent presaturation is needed, check one of the options d1 only, del only or both and set the saturation frequency (it has to be determined before this experiment in a presaturation experiment). Do not increase the power to more than 5. Set the number of scans desired (nt), the relaxation delay (d1) and check the experimental time. When everything is what you want, click on [Acquire] to start the acquisition. ProcessingMost of the processing can be done from the Process, DOSY process panel shown below. First, enable a line broadening of 0.3 or 0.5 and click on [Process all spectra]. Carefully phase the first spectrum and verify that the phasing is consistent for all spectra in the array using the buttons. Select integral mode and manually cut the integral into regions. Apply a baseline correction to all the spectra in the array with [Baseline correct all spectra]. This step is very important to obtain more accurate peak intensities or integrals. Select the peaks to use in the calculation with the minimum threshold tool . When you click on [Calculate full DOSY] the calculations will be performed and the results displayed in tabular form and a 2D dosy spectrum will be shown. Notice that the calculation is always done with the value of DAC_to_G that was read from the configuration files when the spectrum was acquired. If you run your own calibration and want to re-calculate the diffusioncoefficients using your own value, click on [Recall original NMR spectra] and then, on the command line type: setvalue('DAC_to_G', your_gcal, 'processed') where your_gcal is your DAC_to_G calibration. Then click on [Calculate Full DOSY] again.Also notice that if the 2D display is being shown and you click on [Calculate Full DOSY] again, the data gets corrupted and you will have to reload and reprocess you spectrum again. If you want to recalculate a different section of the spectrum or use different parameters, click on [Recall original NMR spectra] first.After the calculation, you can display the line fitting of an individual peak in the spectrum to the Stejskal-Tanner equation by entering a peak number in Peak #_ and clicking on [Show fit for Peak # above]. The actual data will be shown along with the fitted curve and a curve showing the differentials between the two. This is useful to determine if one or more of the individual spectra contains data that deviates considerably from the trend and may need to be discarded. When this happens, the [Calculate Full DOSY with dialog] can be useful. This button allows individual spectra to be omitted from the analysis. Remember to click on [Recall original NMR spectra] first.According to the manual, the Calibration Flag option corrects systematic errors in the experiment. Unfortunately, the manual doesn't mention how these errors are corrected.In general, the interface to this one and other diffusion experiments is very buggy; be cautious. For example, the “Fiddle” buttons (for deconvolution) do not work. The Use Integral Values option does not work. And do not click on the [Plot DOSY] button; not only it doesn't work, but it also freezes Vnmrj.Manual analysisWhile Vnmrj's analysis routines give you a quick and easy way to calculate diffusion coefficients from the spectra, you will get better control of the analysis by measuring peak heights or integrals and doing your own calculations. Stejskal and Tanner have shown that the intensity of the signals in diffusion experiments is described by the following equation:ln(I/I0) = -γ2 δ2 G2(∆ - δ/3) Dwhere:I = intensity or integral of the peak at a given GI0 = intensity or integral of the peak at G = 0γ = magnetogyric constant of the nucleus (for 1H, γ = 2.675 x 108 T-1 s-1 )δ = diffusion gradient length (parameter gt1)∆ = diffusion delay (parameter del)G = gradient field strength (gzlvl1[n] * DAC_to_G)D = diffusion coefficientWith the list of integrals or intensities, a Stejskal-Tanner attenuation plot can be constructed (see Figure 3). This is a plot of ln(I/I0) vs. G2 , and from the slope of this plot the diffusion coefficient D can be extracted. Alternatively, the data can also be fitted directly to the equation I = I0 exp[ -(γδ g)2 (∆ – δ/3) D] using line fitting programs like QtiPlot, Origin, Scientist, SigmaPlot, etc.Figure 3. Stejskal-Tanner plot of a solution of a ruthenium coordination complex in CD2Cl2 at25 C. From the plot, the diffusion coefficients of TMS and of the compound were measured as23.3x10-10 and 9.0x10-10 m2/s respectively. Having TMS in the solution allows the determination ofthe solution's viscosity and of the compound's hydrodynamic radius8. The measured compound'sradius gives an insight into its dimerization process (A ↔ AA).To produce a list of integrals, transform the spectra, select integral regions, carefully correct the bias and slope of the integrals and perform baseline correction as described before. Display the Process, Integration panel (shown below), select Partial under Integral Display Mode, position vnmrj's cursor on top of one of the integrals, select Single Peak under Normalize Area To:, type in a number in Integral Area and click on [Set Integral Value]. The list of integrals for the current spectrum only, normalized to the value entered will be shown on the right side of the panel. You can now generate a list of integrals for all the spectra with the macro UMdli. With this macro you can have the list printed or emailed to you in a format convenient to copy and paste to a line fitting program.With the difussion coefficient, the hydrodynamic radius of a compound in solution can be calculated from the Stokes-Einstein equation:r H =kbT 6 Dwherek b = Boltzman constant, 1.3806 x 10-23 kg m2 s-2 K-1T = temperatureη = viscosity of the solution at temperature TD = diffusion coefficientCalibrationThe parameter DAC_to_G must be calibrated to do the calculations. This parameter is a conversion for the units of the gradient amplifier (DAC units) to gradient in gauss/cm. The parameter has already been calibrated in our spectrometers but you may wish to verify it or recalibrate it yourself. This is done with a sample of known diffusion coefficient like HDO in D2O (the residual solvent peak in D2O). Regulate the temperature and allow at least 10 minutes to equilibrate, run a diffusion experiment and after Fourier transformation and baseline correction select Use Peak Heights, expand the region around the HDO peak and type“dosy_grad_calib” to recalibrate. The macro will ask for the expected value of the peak in units of 10-10m2/s (e.g., for HDO at 25 °C enter 19.02). Known values4 can be found in the table below. Use a diffusion gradient length of 2 ms, a diffusion delay of 100 ms and a long relaxation delay of at least 10 seconds for D2O at 25 °C (it is better to use D2O doped with 0.1 mg/mL GdCl3 so that a shorter delay can be used). TypeDAC_to_G? to print the new calculated value.Sample Diffusion coefficient410% D2O in 90% H2O at 25 °C22.7 x10-10 m2/sHDO in D2O at 5 °C10.34 x10-10 m2/sHDO in D2O at 25 °C19.02 x10-10 m2/sHDO in D2O at 45 °C30.27 x10-10 m2/ssucrose in D2O at 25 °C 4.4 x10-10 m2/s (this lab 01/18/10)References[1] C.S. Johnson Jr. Prog. Nucl. Mag. Res. Spectrosc.34, 203-256 (1999).[2]P.S. Pregosin. Prog. Nucl. Mag. Res. Spectrosc.49, 261-288 (2006)[3]Y. Cohen, L. Avram and L. Frish. Angew. Chem. Int. Ed.44, 520-554 (2005)[4] B. Antalek. Concepts Magn. Reson. 14, 225-258 (2002)[5][P.S. Pregosin, P.G. Anil Kumar and I. Fernandez. Chem. Rev.105, 2977-2998 (2005)[6]M.D. Pelta, H. Barjat, G.A. Morris, A.L. Davis and S.J. Hammond. Magn. Reson. Chem. 36, 706-714(1998).[7]Chemical Properties Handbook. C.L. Yaws, Ed. McGraw-Hill 1999. (online access;/knovel2/Toc.jsp?BookID=49)[8] C. A. Crutchfield and D. J. Harris. J. Magn. Reson.185, 179-182 (2007)[9]Stefano Chimichi in http://www.chimorg.unifi.it/public/chimichi/nmrsolv.html[10]Varian manual, Vnmrj 2.2C: “NMR Spectroscopy, User Guide” Chapter 10.[11]J.C. Cobas, P. Groves, M. Martín-Pastor, A. De Capua. Curr. Anal. Chem. 1, 289-305 (2005). Appendix 1. Useful constantsSolvent Temp,°C Viscosity (η), kg · s-1 · m-1D2O20 1.2467 x 10-325 1.095 x 10-3H2O20 1.0016 x 10-3250.8909 x 10-3CDCl325?0.55 x 10-3200.57 x 10-3CD2Cl2250.417 x 10-3200.436 x 10-3CH3OH200.59 x 10-3CD3OD200.52 x 10-3 Acetone-d6200.34 x 10-3 DMSO-d620 2.4 x 10-3 Toluene-d8200.58 x 10-3 Benzene-d6200.69 x 10-3 Acetonitrile-d3200.39 x 10-3 Pyridine-d5200.97 x 10-3From http://www.chimorg.unifi.it/public/chimichi/nmrsolv.html and other sources.Some conversion constants:1 Pa·s (Pascal-second) = 1 kg s-1 m-11 P (1 poise) = 1 g·cm−1·s−1.The relation between poise and pascal-seconds is:10 P = 1 kg·m−1·s−1 = 1 Pa·s,1 cP = 0.001 Pa·s = 1 mPa·s.Appendix 2. For versions previous to vnmrj 2.2C/chempack 4.1.Earlier versions of vnmrj contain even more bugs than 2.2C; be careful. Essentially you can follow the same procedures described here but you will have to enter all parameters manually. The full list of parameters and other information about the experiment can be found in the manual page (go to the Process/Text Output panel and click on [Sequence Manual] ). Run DgcsteSL_cc and verify or modify the parameters (suggested starting values are in parenthesis):Parameter Typical value Commentdel0.1-0.5 (0.2)diffusion delay (in seconds)gt10.001-0.005 (0.002)Diffusion gradient length (in seconds)gzlvl110-2000Diffusion gradient level, arrayed (in dac units)d13-5 (5.0)relaxation delay (seconds)nt8*n (8)number of transientsspin0sample spinning must be offss8steady state transientslb0.5line broadeningSet up a linear array of gzlvl1 values (Menu: Acquisition>Parameter arrays). Typically 20 values, from 10 to 2000 in increments of 100. In principle, the first value should be 0 but in practice this value gives unpredictable results; use 10 instead. Use the command array('gzlvl1', 20, 0, 100)gzlvl1[1]=10 to setup the array or set it up from the menu Acquisition > Parameter Arrays.When the experiment is finished, transform and phase the first or second spectrum. Integrate the spectrum and define all integration regions (even those not needed). Apply a baseline correction to all the spectra in the array manually or with UMbc. Normalize one region to 1 or to 100 and create a list of integrals for all the spectra in the array with the UMdli macro. Process the data manually.。

疲劳讲座4-疲劳特性表征

Log g 应力幅
b1 1
S C N 1
b
b2
1
疲劳极限
L 总寿命 Log
疲劳特性表征
北京航空航天大学航空推进系
Using S-N Curve to Predict Fatigue Life
S-N Curve Method: A empirical method using alternating stress as d damage parameter to predict di f fatigue i f failure il cycles l
金属疲劳理论与分析系列讲座
金属疲劳特性表征 Ch Characterizing t i i Fatigue F ti Behaviors
（疲劳理论-Fatigue Theory）
疲劳建模的方法-Fatigue Modeling 疲劳寿命的物理数学模型
疲劳特性表征第四讲
北京航空航天大学航空推进系
Why Characterizing?
北京航空航天大学航空推进系
S-N 曲线法思路
S-N 曲线法 (名义应力法) 是以交变应力为主要参量预测零部件疲劳失效循环数的一种经验方法。
名义应力

从试样中测出材料的 S S-N N 曲线考虑实际零件和试样的差别，修正 S-N 曲线考虑试验加载和实际加载的区别应用雨流技术对应力信号进行循环周计数结合 Miner 损伤累积法则计算疲劳寿命
S-N curves are derived from tests on samples of the material to be characterized (often called coupons) where a regular sinusoidal stress is applied by a testing machine which also counts the number of cycles to failure. This process is sometimes known as coupon testing. g Each coupon test generates a point on the plot though in some cases there is a runout where the time to failure exceeds that available for the test (see censoring). Analysis y of fatigue g data requires q techniques q from statistics, especially survival analysis and linear regression.

关于反战英语作文高中

关于反战英语作文高中在写一篇关于反战的高中英语作文时，我们可以着眼于反战的重要性、战争的影响以及促进和平的方式等方面展开。

以下是一篇参考范文，旨在探讨这些主题：The Urgency of Anti-War Movements: A Call for Global Peace。

War has long been a haunting specter in human history, leaving behind scars that mar generations. As we stand atthe threshold of the 21st century, the urgency to cultivate a culture of peace has never been more pressing. The detrimental impacts of war, both on a micro and macro level, highlight the imperative need for anti-war movements to flourish.Firstly, the human toll of warfare cannot be overstated. From the devastation of lives lost on the battlefield tothe trauma inflicted upon civilians caught in the crossfire, war exacts a heavy price on humanity. The images of war-ravaged cities and displaced populations serve as stark reminders of the true cost of armed conflict. Anti-war movements advocate not just for the cessation of violence but for the protection of human dignity and the right tolive in peace.Moreover, the economic repercussions of war reverberate far beyond the battlefield. Scarce resources diverted to fund military campaigns could otherwise be allocated tovital social programs such as education, healthcare, and poverty alleviation. The opportunity cost of war is immense, hindering progress and perpetuating cycles of poverty and inequality. Anti-war activism underscores the need to prioritize diplomacy and peaceful resolution of conflicts, thereby redirecting resources towards human development.On a global scale, the environmental impact of warfare poses a grave threat to our planet. The wanton destructionof ecosystems through bombings and the deployment of chemical weapons not only devastates local environments but also contributes to broader ecological degradation. Anti-war initiatives recognize the intrinsic link between peaceand environmental sustainability, advocating for policies that protect both human communities and the natural world.To effectively champion the cause of peace, anti-war movements must transcend national boundaries and foster international solidarity. Collaborative efforts among nations, backed by civil society organizations and grassroots activism, are instrumental in promoting dialogue and negotiation over militarization. Education plays a pivotal role in cultivating a culture of peace, empowering individuals to become advocates for conflict resolution and social justice.In conclusion, the imperative to oppose war and advocate for peace is rooted in our shared humanity. Anti-war movements embody the aspirations of countless individuals striving for a future free from the ravages of conflict. As we navigate the complexities of a globalized world, let us heed the lessons of history and worktirelessly towards a more just and peaceful world for all.This essay underscores the critical importance of anti-war activism in fostering a culture of peace and cooperation. By examining the multifaceted impacts of war and the role of grassroots movements in effecting change, we gain valuable insights into the transformative power of collective action.。

通信工程师：TD网络优化试题预测(题库版)

通信工程师：TD网络优化试题预测（题库版）1、填空题位置更新属于（）的特定程序，每个GSMPLMN的覆盖区都被分为许多个（）.正确答案：MM；位置区2、单选Mobis比Abis的好处之一是（）A.在BSC打包寻呼（江南博哥）消息B.降低了BTS设备的造价C.处理测量报告、功率控制、TA控制都在BTS完成，减少了RSL消息D.没有好处正确答案：C3、单选（）负责实现7号信令消息与IP协议的转换A.GMSCB.HLRC.VLRD.IWMSCE.SME正确答案：D4、单选XCDR板内有30个负责语音编码的DSPSUBSYSTEM，如果其中的一个DSP坏了，XCDR将如何将此信息通知MSC（）A.与MSC相连的2M线B.无法通知MSCC.MTLD.先经XBL通知BSC，再由BSC经MTL通知MSC正确答案：D5、多选关于语音业务无线接通率描述正确的是（）。

A.RRC连接建立成功率和RAB指派成功率联合起来使用表示无线接通率B.RRC连接建立成功率＝RRC连接建立成功次数/RRC连接建立尝试次数*100%C.RAB连接建立成功意味着UE与网络建立了信令连接，而RRC建立成功则是成功为用户分配了用户平面的连接D.RAB建立成功率可分为CS域RAB建立成功率，PS域RAB建立成功率正确答案：A, B, D6、单选在华为BTS参数中，“同心圆属性”的参数取值范围是（）A.圆环B.无C.外圆D.内圆E.内圆、外圆、无正确答案：E7、单选我国GSM900的上行频段是（）MHzA.905~915B.910~925C.915~925D.915~930E.900~920正确答案：A8、填空题摩托罗拉PowerControl参数中，“bts_power_control_allowed”参数名称是（），参数设置及其影响是（）。

正确答案：基站功率控制开关/；打开基站功率控制可以减少下行干扰9、判断题Abis接口上的信令流，经过Abis接口E1/STM-1接口模块交换到Ater接口或者Pb接口。

中国特色英语词汇

关于国家大事及政治的一些英语词汇For four years in a row（连续四年）a year-on-year increase（比上年增加）reform and opening up policy（改革开放政策）social programs（社会事业）per capita（每人的，人均的）after adjusting for inflation（扣除价格因素）moderately prosperous society（小康社会）macroeconomic regulatory（宏观调控）new socialist countryside（社会主义新农村）pursuant to the law（依法）rural migrant workers in cities（农民工）surplus production capacity（生产力过剩）opened to traffic（通车）energy conservation（节能）state-owned enterprises（国有企业）civil servant（公务员）made breakthroughs（取得突破）compulsory education（义务教育）miscellaneous fees（杂费）boarding schools（寄宿制学校）distance education（远程教育）secondary vocational schools（中等职业学校）incorporated villages（行政村）unincorporated villages（自然村）After years of effort（经过多年努力）basic cost of living allowances（最低生活保障）autonomous regions（自治区）free our minds（解放思想）keep pace with the times（与时俱进）Chinese socialism（中国特色社会主义）social harmony（社会和谐）special administrative regions（特别行政区）prudent fiscal policy.（稳健的财政政策）boosting domestic demand（扩大内需）cutting-edge（前沿）displaced residents（（三峡）移民）non-publicly funded schools（民办学校）school year（学年）communicable diseases（传染病）social safety net（社会保障）discharged military personnel（退伍军人）pyramid schemes（传销）pilot project（试点）Income Tax（所得税）futures market（期货市场）high value-added（高附加值）high-end（高端）cutthroat competition（恶性竞争）combat corruption（反腐）hand over foot（大手大脚）plug up loopholes（堵塞漏洞）People's Armed Police（武警）starting point and objective（出发点和落脚点）socialist market economy（社会主义市场经济）Scientific Outlook on Development（科学发展观）harmonious socialist society（社会主义和谐社会）tailor measures to suit local conditions（因地制宜）South-to-North Water Diversion Project（南水北调）administrative examination and approval（行政审批）follow a realistic and pragmatic approach（实事求是）exercise activities for the general public（全民健身活动）large-scale development of the western region（西部大开发）processing industry for agricultural products（农产品加工业）municipalities directly under the central government（直辖市）primary, secondary and tertiary industry（第一第二第三产业）deliver a good report to the people.（向人民交出满意的答卷）socialist cultural and ethical progress（社会主义精神文明建设）give full play to the initiative of each.（充分发挥各自的积极性）registering the third consecutive annual increase（连续三年增加）physically and mentally challenged persons（残疾人，肢残和智残）resource-conserving and environmentally friendly society.（资源节约型和环境友好型社会）ensure that all of the people share in the fruits of reform and development.（让全体人民共享改革发展的成果）中国特色词汇翻译1. 元宵节：Lantern Festival2. 刺绣：embroidery3. 重阳节：Double-Ninth Festival4. 清明节：Tomb sweeping day5. 剪纸：Paper Cutting6. 书法：Calligraphy7. 对联：(Spring Festival) Couplets8. 象形文字：Pictograms/Pictographic Characters9. 人才流动：Brain Drain/Brain Flow10. 四合院：Siheyuan/Quadrangle11. 战国：Warring States12. 风水：Fengshui/Geomantic Omen13. 铁饭碗：Iron Bowl14. 函授部：The Correspondence Department15. 集体舞：Group Dance16. 黄土高原：Loess Plateau17. 红白喜事：Weddings and Funerals18. 中秋节：Mid-Autumn Day19. 结婚证：Marriage Certificate20. 儒家文化：Confucian Culture21. 附属学校：Affiliated school22. 古装片：Costume Drama23. 武打片：Chinese Swordplay Movie24. 元宵：Tangyuan/Sweet Rice Dumpling (Soup)25. 一国两制：One Country, Two Systems26. 火锅：Hot Pot27. 四人帮：Gang of Four28. 《诗经》：The Book of Songs29. 素质教育：Essential-qualities-oriented Education30. 《史记》：Historical Records/Records of the Grand Historian31. 大跃进：Great Leap Forward (Movement)32. 《西游记》：The Journey to the West33. 除夕：Chinese New Year’s Eve/Eve of the Spring Festival34. 针灸：Acupuncture35. 唐三彩：Tri-color Pottery of the Tang Dynasty/ The Tang Tri-colored pottery36. 中国特色的社会主义：Chinese-charactered Socialist/Socialist with Chinesecharacteristics37. 偏旁：radical38. 孟子：Mencius39. 亭/阁：Pavilion/ Attic40. 大中型国有企业：Large and Medium-sized State-owned Enterprises41. 火药：gunpowder42. 农历：Lunar Calendar43. 印/玺：Seal/Stamp44. 物质精神文明建设：The Construction of Material Civilization and SpiritualCivilization45. 京剧：Beijing Opera/Peking Opera46. 秦腔：Crying of Qin People/Qin Opera47. 太极拳：Tai Chi48. 独生子女证：The Certificate of One-child49. 天坛：Altar of Heaven in Beijing50. 小吃摊：Snack Bar/Snack Stand51. 红双喜：Double Happiness52. 政治辅导员：Political Counselor/School Counselor53. 春卷：Spring Roll(s)54. 莲藕：Lotus Root55. 追星族：Star Struck56. 故宫博物院：The Palace Museum57. 相声：Cross-talk/Comic Dialogue58. 下岗：Lay off/Laid off59. 北京烤鸭：Beijing Roast Duck60. 高等自学考试：Self-taught Examination of Higher Education61. 烟花爆竹：fireworks and firecracker62. 敦煌莫高窟：Mogao Caves63. 电视小品：TV Sketch/TV Skit64. 香港澳门同胞：Compatriots from Hong Kong and Macao65. 文化大革命：Cultural Revolution66. 长江中下游地区：The Mid-low Reaches of Yangtze River67. 门当户对：Perfect Match/Exact Match68. 《水浒》：Water Margin/Outlaws of the Marsh69. 中外合资企业：Joint Ventures70. 文房四宝（笔墨纸砚）："The Four Treasure of the Study" "Brush, Inkstick,Paper, and Inkstone",两会热词在近日开幕的全国政协会议上，政协委员纷纷建言献策，反腐倡廉、医疗改革、食品药品安全、收入分配、就业问题、环境保护、住房问题、教育公平、社会保险、司法公正等问题成为关注的焦点。

A description of micro- and macroscale damage of concrete structures

.2. ~~dros~t~ case. This kind of compressive load affects the microporous structure of the cement matrix. It leads to the collapse of the porous regions and then to the consolidation of the material. There is first a decrease in the stiffness followed by an increase, when the number of contacts inside the material is important; at the same time, the volume decreases. 2.2.3. General case: c~ass~cation. The uniaxial results have pointed out the presence in microcrack growth of mode I. Experimental and other computational results[4] show that the existence of mode I is linked to the existence of positive strains (extensions). When mode I exists the behavior of the material shows an instability, the importance of which is in accordance with the intensity of tensile stresses and then there is a dissymmet~ between the uniaxial tensile and compressive behaviors. When the load does not allow extensions, mode I does not exist and the friction between the lips of the microcracks which grow in modes II or III leads to a ductile behavior. We suggest then[5] the classification given in Fig. 2 which links the type of loading, the local damage mode and the type of behavior. 3. A CONTINUOUS DAMAGE MODEL FOR CONCRETE

FLUENT中常见的单词

abort 异常中断, 中途失败, 夭折, 流产, 发育不全，中止计划[任务] accidentally 偶然地, 意外地accretion 增长activation energy 活化能active center 活性中心addition 增加adjacent 相邻的aerosol浮质(气体中的悬浮微粒,如烟,雾等), [化]气溶胶, 气雾剂, 烟雾剂ambient 周围的, 周围环境amines 胺amplitude 广阔, 丰富, 振幅, 物理学名词annular 环流的algebraic stress model(ASM) 代数应力模型algorithm 算法align 排列，使结盟, 使成一行alternately 轮流地analogy 模拟，效仿analytical solution 解析解anisotropic 各向异性的anthracite 无烟煤apparent 显然的, 外观上的，近似的approximation 近似arsenic 砷酸盐assembly 装配associate 联合，联系assume 假设assumption 假设atomization 雾化axial 轴向的battlement 城垛式biography 经历bituminous coal 烟煤blow-off water 排污水blowing devices 鼓风(吹风)装置body force 体积力boiler plant 锅炉装置（车间）Boltzmann 玻耳兹曼Brownian rotation 布朗转动bulk 庞大的bulk density 堆积密度burner assembly 燃烧器组件burnout 燃尽capability 性能，（实际）能力，容量，接受力carbon monoxide COcarbonate 碳酸盐carry-over loss 飞灰损失Cartesian 迪卡尔坐标的casing 箱，壳，套catalisis 催化channeled 有沟的，有缝的char 焦炭、炭circulation circuit 循环回路circumferential velocity 圆周速度clinkering 熔渣clipped 截尾的clipped Gaussian distribution 截尾高斯分布closure (模型的)封闭cloud of particles 颗粒云cluster 颗粒团coal off-gas 煤的挥发气体coarse 粗糙的coarse grid 疏网格，粗网格coaxial 同轴的coefficient of restitution 回弹系数；恢复系数coke 碳collision 碰撞competence 能力competing process 同时发生影响的competing-reactions submodel 平行反应子模型component 部分分量composition 成分cone shape 圆锥体形状configuration 布置，构造confined flames 有界燃烧confirmation 证实, 确认, 批准conservation 守恒不灭conservation equation 守恒方程conserved scalars 守恒标量considerably 相当地consume 消耗contact angle 接触角contamination 污染contingency 偶然, 可能性, 意外事故, 可能发生的附带事件continuum 连续体converged 收敛的conveyer 输运机convolve 卷cooling wall 水冷壁correlation 关联(式)correlation function 相关函数corrosion 腐蚀，锈coupling 联结, 接合, 耦合crack 裂缝，裂纹creep up （水）渗上来，蠕升critical 临界critically 精密地cross-correlation 互关联cumulative 累积的curtain wall 护墙，幕墙curve 曲线custom 习惯, 风俗, <动词单用>海关, (封建制度下)定期服劳役, 缴纳租税, 自定义, <偶用作>关税v.定制, 承接定做活的cyano 氰（基），深蓝，青色cyclone 旋风子，旋风，旋风筒cyclone separator 旋风分离器[除尘器]cylindrical 柱坐标的cylindrical coordinate 柱坐标dead zones 死区decompose 分解decouple 解藕的defy 使成为不可能demography 统计deposition 沉积derivative with respect to 对…的导数derivation 引出, 来历, 出处, (语言)语源, 词源design cycle 设计流程desposit 积灰，结垢deterministic approach 确定轨道模型deterministic 宿命的deviation 偏差devoid 缺乏devolatilization 析出挥发分，液化作用diffusion 扩散diffusivity 扩散系数digonal 二角(的), 对角的，二维的dilute 稀的diminish 减少direct numerical simulation 直接数值模拟discharge 释放discrete 离散的discrete phase 分散相, 不连续相discretization [数]离散化deselect 取消选定dispersion 弥散dissector 扩流锥dissociate thermally 热分解dissociation 分裂dissipation 消散, 分散, 挥霍, 浪费, 消遣, 放荡, 狂饮distribution of air 布风divide 除以dot line 虚线drag coefficient 牵引系数，阻力系数drag and drop 拖放drag force 曳力drift velocity 漂移速度driving force 驱[传, 主]动力droplet 液滴drum 锅筒dry-bottom-furnace 固态排渣炉dry-bottom 冷灰斗，固态排渣duct 管dump 渣坑dust-air mixture 一次风EBU---Eddy break up 漩涡破碎模型eddy 涡旋effluent 废气，流出物elastic 弹性的electro-staic precipitators 静电除尘器emanate 散发, 发出, 发源，[罕]发散, 放射embrasure 喷口，枪眼emissivity [物]发射率empirical 经验的endothermic reaction 吸热反应enhance 增，涨enlarge 扩大ensemble 组，群，全体enthalpy 焓entity 实体entrain 携带，夹带entrained-bed 携带床equilibrate 保持平衡equilibrium 化学平衡ESCIMO-----Engulfment（卷吞）Stretching（拉伸）Coherence（粘附）Interdiffusion-interaction （相互扩散和化学反应）Moving-observer（运动观察者）exhaust 用尽, 耗尽, 抽完, 使精疲力尽排气排气装置用不完的, 不会枯竭的exit 出口，排气管exothermic reaction 放热反应expenditure 支出，经费expertise 经验explicitly 明白地, 明确地extinction 熄灭的extract 抽出，提取evaluation 评价，估计，赋值evaporation 蒸发(作用)Eulerian approach 欧拉法facilitate 推动，促进factor 把…分解fast chemistry 快速化学反应fate 天数, 命运, 运气，注定, 送命，最终结果feasible 可行的，可能的feed pump 给水泵feedstock 填料fine grid 密网格，细网格finite difference approximation 有限差分法flamelet 小火焰单元flame stability 火焰稳定性flow pattern 流型fluctuating velocity 脉动速度fluctuation 脉动，波动flue 烟道（气）flue duck 烟道fluoride 氟化物fold 夹层块forced-and-induced draft fan 鼓引风机forestall 防止fouling 沾污fraction 碎片部分，百分比fragmentation 破碎fuel-lean flamefuel-rich regions 富燃料区，浓燃料区fuse 熔化，熔融gas duct 烟道gas-tight 烟气密封gasification 气化(作用)gasifier 气化器generalized model 通用模型Gibbs function Method 吉布斯函数法Gordon 戈登governing equation 控制方程gradient 梯度graphics 图gross efficiency 总效率hazard 危险header 联箱helically 螺旋形地heterogeneous 异相的heat flux 热流(密度)heat regeneration 再热器heat retention coeff 保热系数histogram 柱状图homogeneous 同相的、均相的hopper 漏斗horizontally 卧式的，水平的hydrodynamic drag 流体动力阻力hydrostatic pressure 静压hypothesis 假设humidity 湿气，湿度，水分含量identical 同一的，完全相同的ignition 着火illustrate 图解，插图in common with 和…一样in excess of 超过, 较...为多in recognition of 承认…而，按照in terms of 根据, 按照, 用...的话, 在...方面incandescent 白炽的，光亮的inception 起初induced-draft fan 强制引风机inert 无活动的, 惰性的, 迟钝的inert atmosphere 惰性气氛inertia 惯性, 惯量inflammability 可燃性injection 引入，吸引inleakage 漏风量inlet 入口inlet vent 入烟口instantaneous reaction rate 瞬时反应速率instantaneous velocity 瞬时速度instruction 指示, 用法说明(书), 教育, 指导, 指令intake fan 进气风扇integral time 积分时间integration 积分interface 接触面intermediate 中间的，介质intermediate species 中间组分intermittency model of turbulence 湍流间歇模型intermixing 混合intersect 横断，相交interval 间隔intrinsic 内在的inverse proportion 反比irreverse 不可逆的irreversible 不可逆的，单向的isothermal 等温的, 等温线的,等温线isotropic 各向同性的joint 连接justify 认为Kelvin 绝对温度，开氏温度kinematic viscosity 动粘滞率, 动粘度kinetics 动力学Lagrangian approach 拉格朗日法laminarization 层流化的Laminar 层流Laminar Flamelet Concept 层流小火焰概念large-eddy simulation (LES) 大涡模拟leak 泄漏length scale 湍流长度尺度liberate 释放lifetime 持续时间，（使用）寿命，使用期literature 文学(作品), 文艺, 著作, 文献lining 炉衬localized 狭小的logarithm [数] 对数Low Reynolds Number Modeling Method 低雷诺数模型macropore 大孔隙(直径大于1000埃的孔隙) manipulation 处理, 操作, 操纵, 被操纵mass action 质量作用mass flowrate 质量流率Mcbride 麦克布利德mean free paths 平均自由行程mean velocity 平均速度meaningful 意味深长的，有意义的medium 均匀介质mercury porosimetery 水银测孔计, 水银孔率计mill 磨碎，碾碎mineral matter 矿物质mixture fraction 混合分数modal 众数的，形式的, 样式的, 形态上的, 情态的, 语气的[计](对话框等)模式的modulus 系数, 模数moisture 水分，潮湿度molar 质量的, [化][物]摩尔的moment 力矩，矩，动差momentum 动量momentum transfer 动量传递monobloc 单元机组monobloc units 单组mortar 泥灰浆mount 安装，衬底Monte Carlo methods 蒙特卡罗法multiflux radiation model 多(4/6)通量模型multivariate [统][数]多变量的,多元的negative 负Newton-Rephson 牛顿—雷夫森nitric oxide NO2node 节点non-linear 非线性的numerical control 数字控制numerical simulation 数值模拟table look-up scheme 查表法tabulate 列表tangential 切向的tangentially 切线tilting 摆动the heat power of furnace 热负荷the state-of-the-art 现状thermal effect 反应热thermodynamic 热力学thermophoresis 热迁移，热泳threshold 开始, 开端, 极限tortuosity 扭转, 曲折, 弯曲toxic 有毒的，毒的trajectory 轨迹,弹道tracer 追踪者, 描图者, (铁笔等)绘图工具translatory 平移的transport coefficients 输运系数transverse 横向，横线triatomic 三原子的turbulence intensity 湍流强度turbulent 湍流turbulent burner 旋流燃烧器turbulization 涡流turnaround 完成two-scroll burner 双涡流燃烧器unimodal [统](频率曲线或分布)单峰的,(现象或性质) 用单峰分布描述的validate 使…证实validation 验证vaporization 汽化Variable 变量variance 方差variant 不同的，变量variation 变更, 变化, 变异, 变种, [音]变奏, 变调vertical 垂直的virtual mass 虚质量viscosity 粘度visualization 可视化volatile 易挥发性的volume fraction 体积分数, 体积分率, 容积率volume heat 容积热vortex burner 旋流式燃烧器vorticity 旋量wall-function method 壁面函数法water equivalent 水当量weighting factor 权重因数unity （数学）一uniform 不均匀unrealistic 不切实际的, 不现实的Zeldovich 氮的氧化成一氧化氮的过程zero mean 零平均值zone method 区域法。

电子工程师常用英语词汇手册

英文电子专业词汇（新手必备）1 backplane 背板2 Band gap voltage reference 带隙电压参考3 bench top supply 工作台电源4 Block Diagram 方块图5 Bode Plot 波特图6 Bootstrap 自举7 Bottom FET Bottom FET8 bucket capacitor 桶形电容9 chassis 机架10 Combi-sense Combi-sense11 constant current source 恒流源12 Core Saturation 铁芯饱和13 crossover frequency 交叉频率14 current ripple 纹波电流15 Cycle by Cycle 逐周期16 cycle skipping 周期跳步17 Dead Time 死区时间18 DIE Temperature 核心温度19 Disable 非使能，无效，禁用，关断20 dominant pole 主极点21 Enable 使能，有效，启用22 ESD Rating ESD额定值23 Evaluation Board 评估板24 Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. 超过下面的规格使用可能引起永久的设备损害或设备故障。

建议不要工作在电特性表规定的参数范围以外。

25 Failing edge 下降沿26 figure of merit 品质因数27 float charge voltage 浮充电压28 flyback power stage 反驰式功率级29 forward voltage drop 前向压降30 free-running 自由运行31 Freewheel diode 续流二极管32 Full load 满负载33 gate drive 栅极驱动34 gate drive stage 栅极驱动级35 gerber plot Gerber 图36 ground plane 接地层37 Henry 电感单位：亨利38 Human Body Model 人体模式39 Hysteresis 滞回40 inrush current 涌入电流41 Inverting 反相42 jittery 抖动43 Junction 结点44 Kelvin connection 开尔文连接45 Lead Frame 引脚框架46 Lead Free 无铅47 level-shift 电平移动48 Line regulation 电源调整率49 load regulation 负载调整率50 Lot Number 批号51 Low Dropout 低压差52 Miller 密勒53 node 节点54 Non-Inverting 非反相55 novel 新颖的56 off state 关断状态57 Operating supply voltage 电源工作电压58 out drive stage 输出驱动级59 Out of Phase 异相60 Part Number 产品型号61 pass transistor pass transistor62 P-channel MOSFET P沟道MOSFET63 Phase margin 相位裕度64 Phase Node 开关节点65 portable electronics 便携式电子设备66 power down 掉电67 Power Good 电源正常68 Power Groud 功率地69 Power Save Mode 节电模式70 Power up 上电71 pull down 下拉72 pull up 上拉73 Pulse by Pulse 逐脉冲（Pulse by Pulse）74 push pull converter 推挽转换器75 ramp down 斜降76 ramp up 斜升77 redundant diode 冗余二极管78 resistive divider 电阻分压器79 ringing 振铃80 ripple current 纹波电流81 rising edge 上升沿82 sense resistor 检测电阻83 Sequenced Power Supplys 序列电源84 shoot-through 直通，同时导通85 stray inductances. 杂散电感86 sub-circuit 子电路87 substrate 基板88 Telecom 电信89 Thermal Information 热性能信息90 thermal slug 散热片91 Threshold 阈值92 timing resistor 振荡电阻93 Top FET Top FET94 Trace 线路，走线，引线95 Transfer function 传递函数96 Trip Point 跳变点97 turns ratio 匝数比，＝Np / Ns。

MicroandMacro4

（3）资源自由流动。
（4）市场信息畅通。
Characteristics of perfect
competition
A large number of buyers and sellers of the commodity , so that no one firm can affect the market price through its own action.
Consider the following diagram
Demand for Goods and services
Market Price
Supply of Goods and services
Consumers
Producers
Supply of Factor Services
Factor Prices
No seller or buyer has control over price.
Characteristics of perfect competition
There are no real examples of perfect competition although a number of economists suggest that the Canadian wheat market comes closer than most. There are thousands of sellers and ultimately millions of buyers.
Characteristics of perfect competition
The product once graded is homogenous, all those who are in the market are specialists with good knowledge and individual farmers can usually sell all they want to at the market price.

存款利率市场化与中国宏观经济波动_基于TVAR模型的实证研究_陆军（ＰＤ..

金融论坛２０１４年第５期（总第２２１期）存款利率市场化与中国宏观经济波动—基于ＴＶＡＲ模型的实证研究——陆军陈郑［摘要］本文运用门限向量自回归（TVAR）模型在宏观层面上对中国存款利率约束与宏观经济波动的非线性关联进行实证研究。

研究发现：（1）中国在1996年1月至2013年11月期间的大部分时间都处于存款利率有约束状态，而存款利率约束在总体上减少了产出的波动；（2）存款利率有约束时，货币供应量等数量型冲击对产出影响幅度更小、持续时间更短，利率等价格型冲击对经济增长的作用周期更长，紧缩性的利率政策对经济的抑制效果更为明显；（3）存款利率无约束时，数量型冲击总体上持续性更强，价格型冲击则容易引起经济增长短期内大幅波动。

［关键词］存款利率约束；利率市场化；宏观经济波动；数量型冲击；价格型冲击［文章编号］1009-9190（2014）05-0013-09［JEL分类号］Ｅ３２；Ｅ５２［文献标志码］AThe Liberalization of Deposit Interest Rate and China’s Macroeconomic Fluctuation—An Empirical Study Based on TVAR Model——LU Jun CHEN Zheng［Abstract］This paper uses the Threshold Vector Autoregression(TVAR)model to verify the nonlinear relationship in macro level between the regulation of deposit interest rate and China’s macroeconomic fluctuation.It is found that,(1)in China,there exists the regulation of deposit interest rate in most of the period during1996.01~2013.11,and the regulation reduces the fluc－tuation of output overall;(2)when deposit interest rate is regulated,quantitative impacts,such as money supply,on output are smaller and last for a shorter time,but price-based impacts,such as interest rate,on economic growth last for a longer time and the inhibiting effects of tightening interest rate policy on economy are more obvious;(3)when deposit rates are not regulated, quantitative impacts last for a longer time overall,and price-based impacts are likely to cause great fluctuations in economic growth in the short term.［Key words］regulation of deposit interest rate;liberalization of interest rate;macroeconomic fluctuation;quantitative impact; price-based impact一、引言利率市场化即为利率自由化的过程，当一国利率水平及其结构主要由市场供求以及经济活动中的风险程度、通货膨胀程度、经济性质等市场因素共同决定时，即实现了利率市场化。

基于多层模型的“两客一危”车辆行驶状态评价系统

基于多层模型的“两客一危”车辆行驶状态评价系统①曹　磊, 裴莉莉, 高　尧, 李　伟, 户媛姣(长安大学信息工程学院, 西安 710064)通讯作者: 李　伟, E-mail: **************.cn摘　要: 随着我国道路运输行业的快速发展, “两客一危”车辆大幅度增长, 给道路出行和乘客的生命财产安全带来了极大的考验. 本文基于海量“两客一危”车辆行驶数据提出了多层模型的“两客一危”车辆行驶状态评价系统. 首先,对行驶数据进行特征筛选、异常值清洗、归一化等处理. 然后, 在宏观和微观两个层面上分别使用聚类分析模型和动态阈值模型对车辆行驶数据进行分析. 最后通过将聚类分析的结果与动态阈值的分析结果相结合即可实现对车辆行驶状态以及驾驶员的驾驶习惯的综合评价. 研究结果表明, 本文提出的多层模型能够对车辆行程路况以及车辆驾驶员驾驶习惯进行较为准确的评估, 可为“两客一危”车辆的管理监督部门以及车辆运输企业提供合理的安全生产的科学依据和数据支持.关键词: 两客一危; 数据挖掘; 聚类分析; 多层模型引用格式: 曹磊,裴莉莉,高尧,李伟,户媛姣.基于多层模型的“两客一危”车辆行驶状态评价系统.计算机系统应用,2021,30(1):94–100. /1003-3254/7759.htmlDriving Status Evaluation System of Special Transportation Vehicle Based on Multi-Layer ModelCAO Lei, PEI Li-Li, GAO Yao, LI Wei, HU Yuan-Jiao(School of Information Engineering, Chang’an University, Xi’an 710064, China)Abstract : With the rapid development of road transportation industry in China, special transportation vehicles have increased significantly, which has brought great challenges to road travel and the safety of passengers’ lives and property.Based on massive special transportation vehicle driving data, this study proposes a multi-layer model of special transportation vehicle driving state evaluation system. Firstly, the data is processed for feature selection, outlier cleaning,and normalization. Then, the cluster analysis model and the dynamic threshold model are used to process vehicle driving data at the macro and micro layers, respectively. Finally, the results of cluster analysis and dynamic threshold analysis are combined to achieve a comprehensive evaluation of the vehicle’s driving status. The research results show that the multi-layer model proposed in this paper can make a more accurate assessment of the vehicle’s travel conditions and driving habits of vehicle drivers. It can provide reasonable scientific basis and data support for the management and supervision departments of special transportation vehicles and the vehicle transportation enterprises.Key words : special transportation vehicle; data mining; clustering analysis; multi-layer model计算机系统应用 ISSN 1003-3254, CODEN CSAOBNE-mail: ************.cn Computer Systems & Applications,2021,30(1):94−100 [doi: 10.15888/ki.csa.007759] ©中国科学院软件研究所版权所有.Tel: +86-10-62661041① 基金项目: 陕西省交通运输厅2018年度交通科研项目(18-31X); 长安大学中央高校基本科研业务费专项资金(300102249102, 300102240201)Foundation item: Transportation Scientific Research Project of Shaanxi Provincial Transportation Department in 2018 (18-31X); The Fundamental Research Funds for the Central Universities of China of Chang’an University (300102249102, 300102240201)收稿时间: 2020-05-21; 修改时间: 2020-06-16, 2020-07-10; 采用时间: 2020-07-14; csa 在线出版时间: 2020-12-31随着我国道路运输行业的快速发展, “两客一危”道路运输车辆数量出现大幅度的增长, 在方便人们出行、促进地区经济水平发展的同时, 也给道路出行和乘客的生命财产安全带来了极大的考验[1].然而, 由于“两客一危”车辆的特殊性、高风险性,以及路网中“两客一危”车辆数据的相对独立性和地区差异[2], 各地区(省)对于活动在本省境内的“两客一危”车辆缺乏系统性研究和管理, 没有能够充分挖掘大数据背景下研究分析的方法和优势, 对于“两客一危”重点车辆的跟踪监测、分析、分布与风险预测没有进行深入挖掘, 从而不利于政府等监管部门的监督和决策.另一方面, 交通安全是交通领域的关键问题. 交通安全条件由驾驶员, 车辆和驾驶环境决定. 先前的研究表明, 超过90%的交通事故与不安全的驾驶行为有关.驾驶行为在驾驶风险分析中起着重要作用. 但是, 在现实生活中很难衡量驾驶风险[3]. 因此驾驶模拟器通常用于调查各种实验环境中的驾驶行为[4]. 诸如自然驾驶研究(NDS)和DriveCam系统之类的一些车辆仪表技术已被广泛用于监测驾驶行为和运动学特征[5]. 现有的大多数危险驾驶行为分析都依赖于碰撞数据或自我报告的问卷调查[6]. 张辉等[7]通过设计分心模拟驾驶试验来采集驾驶人眼动特征数据, 进行驾驶员的分心状态判别. 侯海晶等[8]利用搭载了眼动仪的驾驶模拟器才采集驾驶员感知与操作的数据, 利用这些数据对驾驶员的驾驶风格进行分类. 薛清文等[9]通过采集高精度车辆轨迹数据评估驾驶员的整体驾驶状态, 利用LGBM (Light Gradient Boosting Machine)算法对危险驾驶行为进行识别. 为了充分探索交通事故中的驾驶行为, 重要的是要保持真实驾驶情况下的驾驶行为习惯.对于危险驾驶行为的研究, 交通事故数据传统上是主要或唯一的数据源, 但是交通事故在广义上来说是一个小概率事件, 其所包含的信息很少, 因此主动采取有效交通安全措施的方法已被忽略. 其次, 多层次或多结构的模型能够发现数据中所忽略的对交通安全的影响因素, 对数据的多维度挖掘. 最后, 国内很少将积累的“两客一危”车辆大数据用于道路安全以及危险驾驶研究.为了填补上述研究空白, 本研究的研究目的主要分为以下两点. 第一个目标是从宏观水平上分析不同类型的卡车驾驶员的驾驶习惯和危险驾驶的倾向. 第二个目标是通过在微观层次上对车辆进行动态监控,在这两个水平的基础上建立一个多级模型来对“两客一危”的车辆进行监控和管理. 该研究与现有研究的不同之处在于同时考虑了以下方面:1) 采用真实的“两客一危”车辆驾驶数据(并不是来源于模拟器产生的实验数据), 并根据多个指标发现识别潜在的危险驾驶行为;2) 使用大规模数据集, 本文使用的数据集以5 s的间隔记录货车和客车的行车速度, 车辆位置, 车辆信息相关的数据;3) 建立反映“两客一危”车辆驾驶员危险驾驶倾向的多层次模型.1 数据集构建1.1 数据集概述本文使用的数据为陕西省境内2018年9月至2019年2月共6个月的“两客一危”车辆的行驶数据,其中每天包含大约25 000辆车的行驶信息, 每个车辆每天的行程为一个单独的数据文件, 其中包含的数据项如表1所示.表1 车辆行驶数据字段解释数据项示例单位说明地图经度65 470 092/纠偏后的经度地图纬度20194431/纠偏后的纬度GPS时间20190224/195533年月日/时分秒/GPS速度22km/h/方向229度/事件5//报警编码///GPS经度65467020//GPS纬度20195274//海拔80//行驶记录仪速度28km/h/里程0km/错误类型0/0正常;1经度错误2纬度错误3:时间错误:4速度错误;5:方向错误系统时间20190225/080913年月日/时分秒/1.2 数据采样与可视化在原始数据集中, 随机选择不同日期(包含节假日、工作日)、不同天气状况、一天内不同时段、不同颜色牌照以及不同道路状况的多类车辆行驶数据对驾驶员的驾驶行为进行分析. 本文共选择了9000辆2021 年第 30 卷第 1 期计算机系统应用“两客一危”车辆的行程(单位: 天)进行研究.在对字段的筛选中取出与驾驶员危险驾驶行为相关的车辆位置信息, 例如车辆的GPS 速度, 车辆时间信息与车辆的方向信息. 其中车辆的位置信息用于判断车辆行驶道路类型, 速度、时间与方向信息用于评判驾驶员的驾驶状态, 在对数据字段进行筛选采样之后, 对现有字段中每辆车每天行程(运行时间大于2小时)的速度变化信息与方向变化信息计算方差,形成新的字段. 9000辆车的速度方差与方向方差部分数据可视化结果如图1所示.20406080100120140160180速度方差方向方差图1 方差示例数据1.3 零值与异常值清洗从数据可视化图中可以发现, 数据中包含大量的零值, 而这些零值表示这些车辆的没有处在行驶状态,因此需要对这些零值进行清洗, 清洗后的数据如图2所示.速度方差方向方差020406080100120140160180图2 零值清洗后数据同时, 在这些数据中还有一些由于传感器的误差或者其他原因产生的异常数据, 使用箱型图的方法可以有效检测到这些异常值, 对去除零值后的数据进行箱型图可视化如图3所示.图3中的“+”表示数据中的异常值, 将这些异常值从原数据中清洗掉, 还有7895辆车的行驶状态数据, 之后再对清洗后的数据示例进行可视化如图4所示.图3 箱型图检测异常值结果020406080100120140160180速度方差方向方差图4 数据清洗后结果1.4 数据归一化从零值与异常值清洗后的数据可视化图中可以看出, 车辆行驶的速度方差和方向方差的数据分布不均衡, 且波动相差较大这将在之后的距离计算中对计算结果产生影响, 因此需要对数据进行归一化处理, 本文使用的归一化方法为min-max 归一化方法, 如式(1):V i V ′i 其中, 是真实值, 是规范化之后的值.对归一化后的数据进行可视化如图5所示.速度方差方向方差020406080100120140160180图5 归一化数据可视化从图5中可以看出数据的分布已经比较均衡, 之后以此数据作为输入样本对驾驶情况进行聚类分析.2 多层模型构建本文采用多层次的模型来对“两客一危”车辆驾驶员的驾驶行为进行分析评价, 多层次主要体现在宏观计算机系统应用2021 年第 30 卷第 1 期与微观两个层次. 宏观层面上对驾驶员的一次行程信息进行分析以评判其驾驶平稳性, 微观层面对驾驶员驾驶车辆在不同速度下的危险驾驶行为进行识别. 多层模型的结构如图6所示.图6 “两客一危”车辆行驶状态多层评价模型2.1 宏观层次聚类分析模型对车辆行驶数据的宏观层次分析可以使用聚类的方法. 聚类分析是一种无监督的学习技术, 可将一组物理或抽象对象划分为几个相似的聚类以获得全局数据图或对特定聚类进行进一步分析. 通过聚类生成的类是一组数据对象, 与原始组中的其他对象(基于相似性进行聚类)相比, 它们具有更大的相似性. 相似性由研究对象的属性值确定, 相对距离是一种常用的措施.本文选择基于相对距离的聚类算法K-means 对数据进行聚类, 该方法能够将数据划分为预定数量的聚类(假设有足够多的不同情况).基于距离的算法依靠距离度量(函数)来度量数据点之间的相似度. 距离度量的标准是欧氏距离、余弦或快速余弦距离. 根据所使用的距离度量将数据点分配给最近的群集,该算法认为两个数据对象的距离越近, 相似度就越大; 距离越远, 相似度就越小. 它基于样本空间中最有代表性的点, 迭代地将所有数据样本划分为不同的类别, 使聚类出来的每个簇的聚合度最高,簇间的分离度最高. 对于距离度量本文采用欧式距离计算方法计算, 公式如式(2)所示:x i x j 其中, 和为计算距离的两个点, m 为样本维度数,n 为当前维度.K-means 算法因其算法框架清晰简单易懂, 处理大数据集的算法相对可扩展且高效的优点其才得到大量的应用; 当数据集的类密集且类与类之间的差异明显时, 该算法处理的效果最好. 使用该算法对数据进行聚类分析的首要任务就是给出要生成的类的数目k ,k 值是否合适可以通过计算SSE (簇内误差平方和)来评价. SSE-Kmeans 聚类算法中的核心思想是:1) 在聚类分析中随着数据簇数k 的增加, 样本拆分变得更加复杂并且精细, 而且每个类别的聚合强度逐渐增加, 因此平方误差和SSE 自然降低.2) 如果k 小于真实簇的数量, 则k 的增加将大大增加每个簇的内聚性, 因此SSE 的下降程度将会很大.并且当k 达到真实簇的数量时, 再通过增加k 的值得到的聚合程度的增加将会迅速变小, 因此随着k 值的持续增加, SSE 的下降率迅速下降并逐渐趋于平稳. 也就是说, SSE 和聚类类别数k 之间的关系呈肘形, 其中肘形图中肘部对应的k 值就是数据中真实簇的数量.对于一个特定的d 维数据集合D =(x 1, x 2, …, x n ),SSE-Kmeans 算法的步骤如图7所示.图7 SSE-Kmeans 算法步骤2.2 微观层次动态阈值评判对车辆行驶数据的微观层次分析中使用动态阈值的分析方法. 在车辆危险行驶状态的评判及等级划分的研究中, 当前学者多采用固定阈值的方法, 但是车辆在不同速度的情况下危险驾驶的评判应当也不相同, 如速度越快急转向的评判阈值应该越小, 因此基于速度的车辆危险行驶状态的动态阈值评判更符合实际情况.Han 等[10]利用车辆黑匣子收集了速度、加速度及横摆角速度数据, 识别了急加速、急减速、急转弯、突然换道4种车辆危险行驶状态, 并提出了基于不同速度区间的阈值划分方法, 如表2和图8所示.2021 年第 30 卷第 1 期计算机系统应用表2 微观模型动态阈值速度(km/h)急加速(g)急减速(g)急转向(°)突然换道(°)0–90.220.61/1310–190.220.61/1220–290.210.61/1130–390.20.61/940–490.190.5812.7950–590.150.5810.7860–690.150.5810.77.570–790.140.5510.7780–890.130.5510.5 6.590–0.120.5410.56.50−910−1920−2930−3940−49急加速急减速急转向突然换道50−5960−6970−7980−8990−图8 动态阈值分布图本文使用上述阈值对“两客一危”车辆每条记录的行驶状态进行评判并记录, 并结合宏观模型对车辆行驶平稳状态的评估得到车辆的总体评价[11–13]. 接下来主要介绍宏观层次模型的应用.3 数据聚类分析对数据使用SSE-Kmeans 聚类算法进行聚类首先需要确定簇的个数(即k ), k 值可以通过簇内误差平方和(within-cluster SSE)确定, SSE 的计算方法如式(3)所示:x (i )µ(j )其中, 表示第i 个数据点, 表示j 簇的中心, n 和m 表示样本的维度.对归一化数据进行SSE 计算结果如图9所示.图9中可以看出当k 值为4时, 正好是手肘的位置,即为最佳聚类簇数. 使用SSE-Kmeans 算法对数据进行聚类, 得到结果如图10所示.图10中每一个颜色代表一个数据簇, “X”符号代表每类数据点的中心.同时采用基于密度的聚类方法DBSCAN (Eps =0.5,nPts =10)对数据进行聚类可以得到的结果如图11所示.1234k5678图9 SSE 与k 值的关系0.10.20.30.40.5速度平稳性0.60.70.80.9 1.0Cluster 1Cluster 2Cluster 3Cluster 4Centroids图10 SSE-Kmeans 算法聚类结果图速度平稳性0.20.40.60.81.0图11 DBSCAN 算法聚类结果图从图11可以看出, DBSCAN 算法将数据聚类为一类. 与图10对比可知, 当数据量的类密集时, 基于密度的聚类算法DBSCAN 对行驶平稳性数据的聚类效果并没有基于相对距离的算法SSE-Kmeans 对行驶平稳性数据的聚类效果好[14,15]. 因此本文将对SSE-Kmeans 算法的聚类结果进行分析与讨论.计算机系统应用2021 年第 30 卷第 1 期4 结果分析与讨论图10中每类的数据点数及每类数据点占总数据点的比例如图12所示.188134441612917123数据类别(b) 占比情况4 1 2 3 491 712%161 220%344 444%188 124%图12 每类数据的分布情况与所占比例对聚类结果从每类数据点的特点进行分析可以得出以下结论:1) 第1类数据点(图10中绿色点)代表了这些车辆中行驶最为平稳的一些个体, 这些个体在一天的行程中速度和方向的变化都较为稳定, 因此处在这一类的车辆驾驶员潜在危险驾驶的倾向性特别低.2) 第2类数据(图10中黄色点)则代表了车辆速度平稳性较好但方向平稳性较差的个体, 说明这些车辆在这一天的行程中有可能行驶在弯道较多路况较差的道路上, 虽然其方向平稳性较差, 但是速度变化稳定,因此这一类的车辆驾驶员的危险驾驶倾向比较低.3) 第3类数据(图10中蓝色点)代表了车辆方向平稳性较好但速度平稳性较差, 说明这些车辆在这一天的行程中有可能行驶在弯道较少路况较好的道路上,但由于其速度平稳性较差即速度变化较大, 好在其方向的变化性较小, 因此处在这一类的车辆驾驶员的危险驾驶倾向也比较低.4) 第4类数据(图10中红色点)代表了车辆方向平稳性较差且速度平稳性也较差或者方向平稳性较好但速度平稳性差的车辆, 说明这些车辆在这一天的行程中有可能以很差的速度平稳性行驶在路况不好的道路上, 或者以很差的速度平稳性行驶在路况较好的道路上, 但是由于路况较好时车速也更快其危险驾驶行为造成的后果也更严重, 因此这种特点都说明处于这一类的车辆驾驶员的危险驾驶倾向比较高.结合上面的分析结果, 可以发现88%的车辆都处于低, 或者较低的危险驾驶倾向区域, 其中有24%的车辆在这一天的行程中速度和方向的平稳性均比较低,剩余的12%的车辆在这一天的行程中含有较高的危险驾驶行为的倾向. 聚类结果分布如图13.速度平稳性00.10.20.30.4Cluster 1Cluster 2Cluster 3Cluster 4Centroids0.50.60.70.80.9 1.0图13 聚类结果分布图此外, 据图13的分布情况可以看出, 车辆数据点中的大部分都集中在数据分布图的右下方, 陕西省内的“两客一危”车辆主要行驶在弯道较少路况较好的道路上, 因此应该主要关注这些车辆的速度以及加速度的变化即可.当需要对某车辆的行驶平稳性进行评价时, 在宏观层面上首先计算其行程方向与速度数据方差, 之后判断其属于哪一类数据簇, 那么其行驶状态就具有那一类数据的特点. 同时在微观层面上对其行驶过程中的急加速、急减速、急转向、突然换道次数进行计算.结合两个层面上的分析结果对车辆的形式状态以及驾驶员的驾驶习惯进行全面准确的评估.5 结语本文采用陕西省内的“两客一危”车辆的行驶GPS 数据, 提出了用以评价“两客一危”车辆行驶状态的多层次模型, 其中多层次模型包含宏观评价模型与微观评价模型, 宏观模型基于SSE-Kmeans算法对车辆行程的速度与方向方差进行聚类分析从而评价车辆行程行驶状态稳定性, 微观模型主要通过动态阈值的方法2021 年第 30 卷第 1 期计算机系统应用评价车辆行驶中急加速、急减速、急转向的次数. 且这些评价均与实际情况相符, 能够较为准确地对车辆行驶状态进行评价. 对于管理部门而言, 能够根据该结果及时对有危险驾驶倾向的驾驶员做出提醒并重点监测, 提高车辆的安全驾驶程度, 降低“两客一危”车辆的事故发生率, 从而保障人民的生命财产安全, 提高运输效率、应急处置和政策决策能力.参考文献陈小妮, 郭骁炜. 建设交通运输安全生产“两客一危”车辆智能监管平台的探析. 公路, 2019, 64(8): 255–259.1唐亮. 信息化条件下营运车辆安全监管关键技术研究[博士学位论文]. 重庆: 重庆大学, 2012.2Eboli L, Guido G, Mazzulla G, et al. 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基于单轴受压的岩石三轴应变指标确定方法研究

• 3437 •
D1 =
16 10 − 3ν M 3 (1 − ν 2 ) ，f = λ 45 2 −ν V
(8b)
D1df / d(σ j + σ k ) = −
式中： f 为微裂纹密度，λ 为随机分布的币状微裂纹半径，λ 3 为 λ 3 的平均值，M 为微裂纹数目，V 为基体体积。岩石材料弹性模量的变化采用细观的微裂纹密度的变化衡量或采用宏观损伤统计模型的应力、应变表示，2 种方法得到的以有效模量表示的损伤结果应该一致。联立式(7)，(8a)可得
⎡ 1 ⎛ ε ⎞m ⎤ E DE = 1 − = 1 − exp ⎢ − ⎜ i ⎟ ⎥ E m ⎝ εc ⎠ ⎥ ⎢ ⎣ ⎦
(7)
式中： DE 为岩石受荷载时的统计损伤变量， DE 值的大小反映了岩石材料内部损伤的程度；a 为材料物理力学性质的参数，反映了材料对外在荷载的响应特征；E 为岩石的弹性模量； E 为岩石的有效弹性模量； ε c 为极限应变； σ c 为极限应力。按细观损伤力学的Taylor方法，可以得到 E / E 与微裂纹密度间的关系[9
～14]
为
⎤ f ⎥ = (1 + D1 f ) −1 (8a) ⎦
)(10 − 3ν ) = 1+ E ⎢ 2 −ν ⎣ 45
式中： f ′ 为三轴受压下岩石的微裂纹密度； σj， σk
其中，
第 28 卷
增2
赖
勇，等. 基于单轴受压的岩石三轴应变指标确定方法研究
(10)
由式(20)，(21)可得
(20) (21)
即
⎡ ⎛ ε ⎞m ⎤ E / E = exp ⎢ − ⎜ i ⎟ ⎥ = (1 + D1 f )−1 ⎢ ⎝a⎠ ⎦ ⎥ ⎣