SIMULATION OF THE INFLUENCE OF TRAILING EDGE SHAPE
动态电压恢复器的dq变换-综合求导检测算法
前面已经假设三相系统中仅含有正序性谐波，则对
于地，根据对称三相电路的特点，应有：
蚝＝√互Ｕ埘ｓｉｎ脚＋口一新，３）＋√互∑以ｓ血丞删＋缸一ｈ，３）’由二
角公式可得：
的电压量求导数的方法，再结合一般运算便可瞬时 分离出直流分量，主要的计算过程如下式：
阱卧赤嘲ｍ）
‰一；‰一嘉小啦－１）以；以伽ｓ枷＋㈣
同理可得：
Ｄ０
ＴｒａＩｌｓｆｏ吼ａｔｉｏｎ－Ｉｎｔｅｇｒａｔｅｄ Ｄｅｒｉｖａｔｉｏｎ Ｄｅｔｅｃｔｉｏｎ Ａ１９０ｒｉｔｔ蚰．Ｆ０ｒ
Ｄｙｎａｍｉｃ ｖｏｌｔａｇｅ Ｒｅｓｔｏｒｅｒ Ⅵｍｇ Ｓｈｕｙ．ｍｇＤｕＢｉｎ
Ｓｃｈ００１ ｏｆＥＩｅｃ倒ｃ Ｐｏｗｅｒ
Ｅｎ画ｎｅ州ｎｇ，Ｎｏｒｄｌ ｃｈｉＩｌａ Ｅ１ｅｃ血证Ｐｏｗ盯Ｕ【ｌｉｖｅｒｓ咄Ｂａｏｄｉｎｇ ０７１００３
Ｒｅｓｔｏｒｅｒ，
ＤｖＲ）可以补偿电压暂降、暂升、不对称、闪变、
滤波器来分离直流分量，为避免滤波器所带来的延
时，文献【２】对ｄｑ变换后的量求微分，微分后所得 到的量与微分前的量相加，可以瞬时求出直流分 量。但这种方法引入了微分算子，对电压采样值的 准确度要求较高；而且文中只是针对基波电压的不 平衡情况进行讨论，并没有考虑谐波分量的影响。 本文提出一种动态电压恢复器的ｄｑ变换－综合 求导检测算法，首先采用求导法无时延的由单相电
三ｌ。
，
”７ （１）
杰√劢：。血（叩＋仍。＋；ｚ）
虬；窆√撕。ｓ．ｍ（叩＋钆＋昙ｚ）＋ 主√如一ｉ“嘶Ｈ‰丢口）
式中：玩为正序第ｉ次谐波有效值（配．为正序基
ｄｑ变换．综合求导检测算法
ｄｑ变换一综合求导检测算法适用于单相电压暂
降的检测，假设ａ相发生电压暂降，其检测原理如
民航发动机凝结尾迹特征数值模拟
膨胀为环境压力。温度偏差对凝结尾迹的宽度和长度影响显著,当温度高于该高度国际标准大气(internationalstandardatmos-
phere,ISA)温度条件时,凝结尾迹的持续范围有限;温度低于ISA 温度条件时,凝结尾迹可持续100m 以上,且凝结参数可达到稳 定状态。相对湿度对凝结尾迹的影响程度低于温度偏差,相对湿度主要影响凝结尾迹的宽度和液滴平均半径。
了线性尾迹云的扩散。近十年大涡模拟的方法也逐 渐应用于尾 迹 云 的 模 拟。Paoli等[11]使 用 大 涡 模 拟 (largeeddysimulation,LES)方法详细研究了发动 机射流 排 放 后 20s内 尾 迹 云 形 成 的 过 程。Solch
收稿日期:2020-06-15 基金项目:中央高校基本科研业务费专项资金资助项目(3122018C034) 第一作者:刘聪(1988—),男,讲师,主要研究方向为民航节能减排运行技术,c_liu@
随着航 空 运 输 业 的 快 速 发 展,民 航 大 型 客 机 的 污染物排放 总 量 和 速 度 进 一 步 增 加,民 航 飞 行 活 动 对大气环境的影响越来越严重[1]。联合国政府间气 候变化专业委员会(IntergovernmentalPanelonClimateChange,IPCC)根据观测数据和模拟研究[2-3], 对民航各排 放 要 素 导 致 的 辐 射 强 迫 做 了 评 估,民 航
LIUCong,WEIZhiqiang
(CollegeofAirTrafficManagement,CivilAviationUniversityofChina,Tianjin300300,China)
Abstract:Inordertostudythejetflowfieldandthecondensationtailofacivilaviationengine,atwo-fluidcondensationmodelwas ingcomputationalfluiddynamics(CFD)numericalsimulationmethod,characteristicsofthejetflowfieldwereanalyzed,andthespacerangeandcondensationparametersofthecondensationtailwerecomparedunderdifferenttemperaturedeviationsandrelativehumidity(RH).Theresultsshowthattheairjetexpandsrapidlywithinashortdistancefromthenozzleexit. Afterabout20meters,theparametersalongflowsectionarerelativelyuniform,andthepressureexpandstotheenvironmental pressure.Thetemperaturedeviationseriouslyaffectsthewidthandlengthofthecondensationtail.Thetrailrangeislimited aboveinternationalstandardatmosphere(ISA)temperatureconditions.WhenthetemperatureislowerthantheISAtemperature condition,thetailcanpersistmorethan100meters,andthecondensationparameterscanbemorestable.TheinfluenceofrelativehumidityonthecondensationtailislowerthanISAdeviation.Relativehumiditymainlyaffectsthewidthofthetailandthe meanradiusofthedroplet. Keywords:civilaviationengine;jetflow;condensationtail;relativehumidity;ISAdeviation
企业经营模拟游戏简介
經營競賽教學法優缺點
相較於課堂講授法與個案討論法，經營競賽教學法或管理 競賽無疑是更接近實作(learning by doing)的教學方法，可 以提供那些已具備各功能部門基本知識的企管系學生一個 非常逼真的綜合應用練習
因為經營競賽在設計上模擬企業的總體運作，較適合已修 完大部分企業管理課程的高年級學生或由各有專長的學生 組隊合作，而且競賽過程是正式的、理性的、嚴肅的，不 但無法在一般的管理課程中作為輔助的學習活動，也不如 簡單明確的學習遊戲能夠引起學生動機
國內的發展
國內目前以企業營運模擬系統 ( BOSS: Business Operations Simulation System )為主要的商業化產品
國立政治大學企業管理研究所教授吳思華與光華策進基 金會於一九八四年合作發展的一套軟體，參考R. C. Henshaw & J.R.Jacson 於1973年發表之“Executive Game” 所研發
Springer-Verlag, New York, NY.
模擬
Using a symbolic model, computer simulation attempts to replicate the characteristics of the system through the use of mathematics or simple object representations.
Simulation and Simulators的差別
“a simulator is a complex device that provides a highly realistic simulation of the operational situation and provides a situation adequate for practicing and maintaining previously acquired skills”,
ENGINEERING DESIGN GUIDELINES
EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES 1.0 PURPOSEThe purpose of this procedure is to provide guidelines to be used during the preparation, control, and retention of design calculations for RTD FasTracks Projects in an effort to:A. Provide a complete, permanent record of the criteria, assumptions, functionalrequirements and technical methodology used in arriving at the design solution for aproject.B. Verify and ensure relevant codes and criteria are used appropriately.C. Verify that the plans and specifications conform to the design.D. Provide reference material for changes during the construction phase and for futurealterations to the facility.2.0 SCOPEThe minimum requirements and criteria outlined for design calculations apply to both in-house and contracted design work. This procedure contains criteria for all of RTD projects including, but not limited to, BRT, CRT, LRT, park-n-Rides and Maintenance Facilities.This procedure offers a summary of expectations, more detailed information can be found in the applicable RTD manuals referenced in Section 4.0 below.3.0 RESPONSIBILITY3.1 Engineering Technical Support Staff (ETS)The ETS staff responsibilities include:A. Write this procedure.B. Re-evaluate and update this procedure in a timely manner to accuratelyrepresent any new design documentation policy decisions.C. Review design documentation submitted by others against this procedure.3.2 Document Control StaffThe document control staff responsibilities include:A. Maintain and update library copies and distribute procedure updates toindividuals issued copies of the EDG.3.3 Contracted Consultant Design TeamThe contracted consultant design team responsibilities include:A. Prepare the design calculations in accordance with this procedure.4.0 REFERENCESA. FasTracks Project Controls Procedure Manual - DC- 2 Baseline DocumentB. ERC Design Criteria Topic listEDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINESC. RTD Quality Assurance Program Plan and QMO Program Manual (QMO Databasefor design comments)D. RTD Bus Transit Facility Design Guidelines and CriteriaE. RTD Commuter Rail Design CriteriaF. RTD Light Rail Design CriteriaG. RTD Guidance Manual for Technical Analysis, March 2001H. RTD CADD Standards ManualI. RTD Standard Drawings Manual5.0 PROCEDURES5.1 General Calculations Requirements Applicable to All Design DisciplinesA. Definitions•Design Calculations: Engineering and architectural reasoning and calculations necessary for the layout and detailing of facilities andequipment. Where calculations are not necessary, it shall include thereasoning upon which the design is based.•Design Check: an independent verification of the completeness and accuracy of the design, including the design approach, assumptions, use ofreference data and computations. It also includes verifying that the designdrawings and specifications are in conformance with the DesignCalculations.•Design Calculations Review: a thorough verification of the design checking process and a spot examination of the Design Calculations for errors oromissions.•Design Calculations Spot Check: a verification of the review process and a spot check of the Design Calculations and drawings for large errors usingengineering judgment for obvious omissions.B. Preparation of Design Calculations•The Design Calculations shall identify the functional and technical criteria applicable to the project being designed including those currently approvedby the Engineering Technical Service Group staff, Design Guidelines, anddiscipline guidelines under whose area of responsibility the type of workfalls and guidelines by the departments. Design criteria for non-RTD workshall be in accordance with utility companies, railroads, or public agencyrequirements, except where RTD requirements are more conservative, inwhich case the more stringent shall be used.•Design Calculations for each discipline shall contain a description of the following information as a minimum:¾The purpose for which the design is being done; for example, structurefor a platform; sewer work in connection with a driver relief station;trackwork for a yard expansion; AC power for a new signal tower; etc.EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES ¾The approach for designing a particular item including usage of appropriate codes, formulae, theories and logic; consistent with goodengineering and architectural principles, as well as RTD standards andpolicy. Field notes and reports on existing conditions should beincluded.¾Assumptions consistent with data or field conditions furnished.¾Sketches showing the elements being designed.¾Computations, with references to the source of the formula being used when required for clarity, etc.¾When a computer program is used, the program will be named and described. (Usually, design programs, such as those used for the CADDsystem, are commercially purchased from recognized leaders in thefield). These vendors maintain a quality assurance program forverification and validation of their product. The purchased programs areprovided with verification and validation checking documentation,performed by the vendor, to assure accuracy and suitableness of use.The output of these routines is to be checked to assure completeness ofoutput. Computer programs and their subsequent revisions shall bevalidated prior to making them available to the designers for use in thedesign process. Validation may be done by running sample problemswith known results to ensure that the programs run properly.•Design checkers shall confirm that the items identified in Section 5.1.B above have been accomplished. Additionally, they shall assure:¾The Design Calculations are legible, clear and completed professionally with all appropriate points addressed.¾ A cross reference to the design must be included if the check is an independent design or a parallel set of Design Calculations. Verify thatall references are confirmed if a line by line check is made.•The Design Calculations and the Design Check shall be performed under the responsible charge and supervision of Professional Engineer licensedto practice engineering in the State of Colorado.•The design checker shall be independent and shall have equivalent qualifications as the designer.•The Design Calculations and the Design Check shall bear the seal and signature of a Professional Engineer in responsible charge licensed in theState of Colorado.•The designated discipline team leader shall provide the assumptions and criteria upon which the design is based and is responsible for the contentand legibility of the Design Calculations.•Designs made during the construction phase shall comply with all the requirements for the original Design Calculations.C. Preparation•Design Calculations shall be done on a formal calculation sheet. Each sheet shall list the contract number, job title and subject, sheet number,number of sheets in the set, dates designed, checked and include both theEDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES designers and checkers initials. Original Design Calculations shall beindexed, bound and kept by the discipline team leader for work performedby the discipline.•Design Calculations prepared during the Construction Phase shall also be indexed and added to the original calculations by the designated disciplineteam leader.•Revised calculations for design and construction shall be prepared and labeled accordingly. Copies of the original calculations and eachsuccessive calculation revision shall be included in the design calculationpackage as described below.•On completion of the final design, the design project manager shall forward copies of all calculations to the Project Manager. All design calculationssubmitted to RTD shall be neatly and logically organized, numbered,indexed and bound with a calculation cover sheet and calculation summaryas defined in section 5.1.E below.•At the substantial completion of the Contract, copies of any calculations generated or revised during the construction phase shall be forwarded tothe Project Manager by the discipline team leader.•When calculations are based on preliminary data for early implementation of work, such calculations shall be subjected to the complete reviewprocedure and the responsible individual shall assure that a final calculationcheck is made as soon as final input data are available.D. Retention•The design project manager shall maintain custody and ready access of all design documents until after the final completion of construction andacceptance of the project.•The design project manager shall maintain a complete and orderly copy of all design documentation including retaining copies of all versions ofcalculations for a period not less than 7 years.E. Deliverables•As a minimum, calculations to support the design shall be included with the 50%, 65% and 90% design submittals respectively and as required by otheragencies affiliated with the project.•Final calculations that are required as the basis of subsequent design may, at the discretion of the Owner’s representative, be required at other times.•The Owner may also request all or part of final design calculations to support design decisions at any time during the design phase.•Design assumptions shall be clearly and concisely stated, precluding the necessity of further interpretation.•Established standards, design criteria, previously developed and approved designs, methods or solutions may be used as guidelines, and identified asto source. Sources used shall be cited.EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES •Calculations shall be orderly and complete, with enough sketches and notes to allow the work to be clearly understood. Diagrams indicating data(such as loads, flows, voltages, and dimensions) shall be included alongwith sketches of all important details not considered standard.• A calculation cover sheet shall be prepared by the originating engineer or designer before calculations are submitted for checking and review. Thecover sheet shall show the project title, task number, discipline, calculationtitle, subject, revision number and date, originator’s signature, checker’ssignature and date.• A design summary shall follow the calculation cover sheet with a brief statement of the problem, source of data, sources of formulas andreferences, intended used of calculations (advanced preliminary design,final design, etc.)•The resultant value of a calculation or solution to be used for design purposes shall be underlined and marked for identification by a double-underline extending to the right hand margin to indicate its location in thecalculations.•Calculations, except those prepared by computer software, shall be made on computational paper bearing the name of the firm or organizationspreparing the calculations. The heading of each sheet in a set ofcalculations shall include the date, designer’s initials, sheet number, totalnumber of sheets in the calculation set, task and subject of the designcalculations.•All calculations involving computer printouts shall have an accompanying calculation package containing the appropriate information as outlinedabove. In the case voluminous or large format output, computercalculations shall be prepared as a separate document, available forchecking and review.5.2 Discipline Specific Calculation RequirementsThe information listed in this section outlines the typical calculations anticipated for milestone submittals by design discipline. Submittal requirements listed in this document are not all-inclusive and are specifically not, expressed or implied, included to define or limit the Designer’s scope of work, design responsibilities, or project deliverables. Design calculations are to be prepared by competent design professionals in accordance with the standards and prudent responsibilities established by the industry, presented in a clear, concise and well organized fashion allowing a complete and thorough peer review, review for construction support or future alterations, by other competent design professionals. All calculations must be sufficient in detail to allow a complete and independent confirmation of all designs required for the project based solely on the information included within the design calculations for the project.EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES5.2.1 Architectural RequirementsA. Basic Engineering (DEIS) through Final 100% Design:•Architectural Requirements for each design phase shall be provided by and coordinated with the Architectural and Landscape Architectural staff.5.2.2 Civil - General RequirementsA. Basic Engineering (DEIS) through Final 100% Design:•For Civil requirements, see the following sections:¾ Geotechnical¾ Roadway¾ Traffic5.2.3 Drainage RequirementsA. Basic Engineering (DEIS):•Provide design inputs used in calculations, including, but not limited to: ¾runoff coefficients¾ gauge data¾precipitation and steam gauge data•Furnish hydrologic analysis used to establish design flow rates including peak flow rates and a summary of all input data (basin area, precipitationand stream gauge data, run-off coefficients, etc.) used to perform theanalysis.•Provide calculations to support all detention requirements and preliminary sizing of detention ponds.•Provide calculations to support the design year, 5-year, 100-year, and 500-year high-water-surface profiles and preliminary hydraulic analysis •Provide calculations to support the scour profile for design year and 500-year scour profile.B. Advanced Preliminary Engineering (50% Design):All information required for the BE (DEIS) design and the following:•Provide calculations for major drainage facilities in sufficient detail to obtain concept approvals from local city and county agencies and UDFCD, and toprepare conceptual designs for bridges and other structures requiringspecial structural design.•Provide hydrologic and hydraulic calculations in support of the design of major facilities. Provide HGLs for major drainageways.•Provide Flood Plain modeling including Flood Plain Elevation calculations.•Water Surface Elevation calculations.C. Final 65% Design:All information required for 50% design and the following:EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES •Prepare a final hydrology and hydraulics drainage report providing description and documentation for the analysis of the final design of all newstormwater facilities and existing facilities impacted by the project. Thereport will include:¾Storm drainage design calculations and comparison to technical criteria of the appropriate local jurisdiction.¾Irrigation facility design calculations.¾Trackway drainage design calculations.¾Park-n-Ride drainage design calculations.¾Calculations for design stormwater flows to affected major and minor drainage basins, and stormwater conveyance elements.¾Storm water detention and water quality calculations.¾Calculations to support hydraulic design for stormwater interception and conveyance systems (including open channel systems, drop structures,bridges, culverts, storm sewers, inlets, energy dissipaters, underdrains,detention facilities, and water quality treatment facilities).¾Scour calculations in support of structural foundation design.•Provide hydrologic and hydraulic calculations in support of the design of major facilities. Provide HGLs for 5-year and 100-year discharge for majorand minor drainageways.D. Final 90% Design:All information required for 65% design and the following:•Finalize designs calculations for:¾Major drainage channel improvements¾Cross-culverts and other storm water conveyance facilities.¾ Stormwater interception facilities.¾ Station drainage.¾Retention and detention basins.¾Rip-rap sizing for outfalls.E. Final 100% Design:All information required for 90 % design and the following:•All calculation related comments on the plans and specifications from RTD staff, from all review agencies (City and County engineering departmentstaff, UDFCD, FEMA, CDOT, and any other applicable regulatory agency),and from a CMGC contractor addressed in the plan set.5.2.4 Environmental / Studies / Mitigation RequirementsA. Basic Engineering (DEIS):•Calculations to support the traffic studies including present and future travel demand.•Calculations to support the Air Quality analysis.•Noise and Vibration assessment analysis calculations shall include the following:EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES ¾Calculations to support the prediction of future traffic noise and vibration levels for all alternatives.¾Calculations to support the evaluation of feasibility, cost effectiveness and reasonableness of noise and vibration abatement measures.¾Any calculations to support the recommendations regarding noise and vibration abatement measures.B. Advanced Preliminary Engineering (50% Design):•No environmental related calculations anticipated at this design phase.•C. Final 65% Design:•Analyze Noise and Vibration impacts during construction.•Calculations estimating dewatering requirements.D. Final 90% Design:•Provide property take hazardous materials ID and demolition plans.•Conduct asbestos and lead assessment surveys.•Prepare a possible recycling plan.•Provide calculations used as the basis for a soil disposal planE. Final 100% Design:•All information required for the milestone submittals during the completion of the design.5.2.5 Geotechnical RequirementsA. Basic Engineering (DEIS):•No geotechnical related calculations anticipated at this design phase.B. Advanced Preliminary Engineering (50% Design):•No geotechnical related calculations anticipated at this design phase.C. Final 65% Design:•The following is a list of calculations that are expected to be included with the design submittals:¾Traffic Loading (EDAL and ESAL18) and Pavement designs¾ Soil classifications¾Retaining wall and foundation calculations•All calculations to support the recommendations and findings presented in the final geotechnical report.•All calculations to support specification requirements.•All calculations to support construction requirements and recommendations.D. Final 90% Design:•No geotechnical related calculations anticipated at this design phase.E. Final 100% Design:•No geotechnical related calculations anticipated at this design phase.EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES5.2.6 Landscape RequirementsA. Basic Engineering (DEIS) through Final 100% Design:•Landscape Requirements for each design phase shall be provided by and coordinated with the Architectural and Landscape Architectural Department.5.2.7 Roadway RequirementsA. Basic Engineering (DEIS):•Calculations for geometric layout of horizontal and vertical alignment.•Quantity calculations of major items including earthwork.B. Advanced Preliminary Engineering (50% Design):•No roadway related calculations anticipated at this design phase.C. Final 65% Design:•The following is a list of calculations that are expected to be included with the design submittals:¾ Site Distance¾Horizontal and Vertical Curvature¾ Super-elevation¾Clear Zone¾Acceleration and Deceleration lanes¾Storage at intersections¾ Roundabout designD. Final 90% Design:•No roadway related calculations anticipated at this design phase.E. Final 100% Design:•No roadway related calculations anticipated at this design phase.5.2.8 Station & park-n-Ride RequirementsA. Basic Engineering (DEIS):•No stations/park-n-Ride related calculations anticipated at this design phase.B. Advanced Preliminary Engineering (50% Design):•No stations/park-n-Ride related calculations anticipated at this design phase.C. Final 65% Design:•No stations/park-n-Ride related calculations anticipated at this design phase.D. Final 90% Design:•No stations/park-n-Ride related calculations anticipated at this design phase.EDG – 5 DESIGN CALCULATIONSENGINEERING DESIGN GUIDELINES E. Final 100% Design:•No stations/park-n-Ride related calculations anticipated at this design phase.5.2.9 Structures RequirementsA. Basic Engineering (DEIS):•Bridge geometry calculations•Preliminary structural design calculations•Preliminary quantity calculations and cost estimateB. Advanced Preliminary Engineering (50% Design):•Revised bridge geometry calculations•Revised structural design calculations•Revised quantity calculations and cost estimateC. Final 65% Design:•No structural related calculations anticipated at this design phase.D. Final 90% Design:•Final structural design calculations•Final Independent Check calculations (The Independent Check for major CDOT structures results in two sets of complete design and quantitycalculations, and one review set of the final plans where all the informationhas been verified).•Final quantity calculations and cost estimateE. Final 100% Design:•Final bridge rating calculations•Final bridge deck elevations calculations (Field Package)5.2.10 Systems / Electrical / Mechanical RequirementsA. Basic Engineering (DEIS):•(This section is not completed yet)B. Advanced Preliminary Engineering (50% Design):•(This section is not completed yet)C. Final 65% Design:•(This section is not completed yet)D. Final 90% Design:•Corrosion control / cathodic protection calculations.E. Final 100% Design:•(This section is not completed yet)5.2.11 Trackwork RequirementsA. Basic Engineering (DEIS):•No trackwork related calculations anticipated at this design phase.EDG – 5 DESIGN CALCULATIONS ENGINEERING DESIGN GUIDELINESRev 0Page 5-11October 2007B.Advanced Preliminary Engineering (50% Design):• The following is a list of calculations that are expected to be included withthe design submittals:¾ Spiral length / Super-elevation ¾ Speed Calculations ¾ Vertical Curve length¾ Minimum Vertical and Horizontal clearance to obstructions C.Final 65% Design:• The following is a list of calculations that are expected to be included withthe design submittals: ¾ Clearance envelope¾ Platform width calculations¾ Grade crossing (rail / roadway profile and cross slopes) D.Final 90% Design:• The following is a list of calculations that are expected to be included withthe design submittals:¾ Bumping post locations (distance from bumping post to end of track) E.Final 100% Design:• No trackwork related calculations anticipated at this design phase.5.2.12 Traffic RequirementsA. Basic Engineering (DEIS):• Background traffic and future traffic conditions B. Advanced Preliminary Engineering (50% Design): • Trip Generation C.Final 65% Design:• The following is a list of calculations that are expected to be included withthe design submittals:¾ Queue length and turn lane lengths ¾ Level of Service¾ Trip distribution and traffic assignment ¾ Weaving Analysis D. Final 90% Design:• No traffic related calculations anticipated at this design phase. E.Final 100% Design:• No traffic related calculations anticipated at this design phase.5.2.13 Utility RequirementsA. Basic Engineering (DEIS):• No utility related calculations anticipated at this design phase. B.Advanced Preliminary Engineering (50% Design):• No utility related calculations anticipated at this design phase.EDG – 5 DESIGN CALCULATIONS ENGINEERING DESIGN GUIDELINESRev 0Page 5-12October 2007C.Final 65% Design:• For all utility facilities crossing, running within, or entering the RTD zone ofinfluence (including tracks, park-n-Rides, stations, and right-of-way limits), the following is a list of calculations that are expected to be included with the design submittals beginning at 65% design.¾ Dry OH Utility Relocations (Communications, Electric Distribution,Electric Transmission)• None for Communications, unless required for a variance • None for Electric Distribution, unless required for a variance• Lowest Sag Calculations for OH Electric Transmission crossingsabove the track or top of catenary pole where applicable.¾ Dry UG Utility Relocations (Communication, Electric Distribution,Electric Transmission)• Stress Influence Calculations for conduits under the trackway• Influence of Utility Collapse Depth Calculations for conduits underthe trackway¾ Wet UG Utility Relocations (Gas, Oil, Sanitary Sewer, Steam, Water)• Deflection Calculations for UG facilities crossing under thetrackway• Stress Influence Calculations for all pipes and casings under thetrackway• Influence of Utility Collapse Depth Calculations for all pipes andcasings under the trackway• Corrosion Control / Cathodic Protection Calculations for steel pipe ¾ Pressurized• Encasement Thickness Calculations • Restraining Length Calculations • Thrust Block Calculations¾ New Facilities for park-n-Rides and Stations• Facility Sizing Calculations (pipe size, pressure, flow, kv) • Tap size Calculations for water and sewer facilities• Electric Calculations (lighting loads, power requirements) • Fire Sprinkler Sizing Calculations• Lowest Sag Calculations for OH facilities• Encasement Thickness Calculations for encased UG utilities • Deflection Calculations for UG facilities• Corrosion Control / Cathodic Protection Calculations for steel pipeD. Final 90% Design:• No utility related calculations anticipated at this design phase. E. Final 100% Design:• No utility related calculations anticipated at this design phase.。
作为极限建筑空间设计依据的人体运动包络体研究
摘要城市化进程不断的发展导致了城市中心的地块不停的被分隔，因此出现了许多在空间极为局促、环境极为苛刻或使用者行为活动受到一定限制的条件下的极限建筑空间。
在此情况下，根据行为建筑学相关理论及设计方法，计算出满足使用者功能需求的最小建筑空间，显得十分重要。
然而现有的极限建筑空间的设计数据主要是根据人体百分位参数进行建筑空间以及空间中固定物的设计。
这样的设计方式，在很大程度上存在着缺少设计针对性、空间尺寸不合理、空间使用效率低、建筑能耗大等问题。
针对这一现象，本研究将首先详细阐述通过计算机编程方式模拟人体运动方式，并通过运动轨迹计算得出人体运动包络体。
人体运动包络体模拟是行为建筑学理论研究推理过程中所采用的一种模拟法。
从而克服了传统实验法存在的样本人体尺度从二维平面研究转化为三维立体空间研究。
在此基础之上，该论文将探讨现存极限建筑存在的问题以及如何在实际建筑设计中，通过计算空间使用者运动包络体得到他们的详细数据，并以此确定使用者在空间中的活动范围，作为极限建筑空间设计的重要参考依据。
这样的设计方式，可以计算出可以满足使用需求的极限建筑空间形态与体积，从而保证建筑空间可以满足使用者对使用功能的基本需求，提高建筑空间使用效率。
另一方面，人体运动包络体可以用于优化极限空间中固定物的位置与尺寸、形状，根据具体使用者的实际测量参数的进行个性化的私人定制，并保证了固定物的基本使用功能。
关键词：运动包络体；极限建筑空间；行为建筑学；模拟法；空间效率AbstractThe land in the center of the city is constantly divided for the sake of urbanization development. As a result, an increasing number of limited architectural space was designed and built. The environment of such kind of space is usually cramped. And the users’ behavior is also limited. In this case, it is of great importance to calculate the minimum size of space which can meet the basic functional needs of the users. However, the existing data for limited architectural extent, leads to an increasing number serious issues, such as lacking pertinence, unreasonable space size, low space efficiency and high energy consumption.In order to solve this issue, this essay will first simulate the movement of human body by computer programming. After that, enveloping solid will be calculated by the trail of human body. Enveloping solid simulation is a basic simulating method in the inference procedure of behavioral architecture. Compared with traditional experiments, there will be no sample quantity limitation and anthropogenic factor in simulating process. And the 2-dimensional human parameter comes to 3 dimensional.Based on which, this essay will explore the existing problems on limited architectural space design and how to use enveloping solid simulation in architecture design. In the first stage, the design data of users can be get from the process of enveloping solid simulation. And the users’ parameter shows the range of activity, which is important reference frame in design procedure. By this method, the functional needs of users can be meet. And space efficiency can also be improved. What’s more, enveloping solid can be used in optimizing the shape and location of fixtures in building as well.Keywords:enveloping solid, limited architectural space,behavioral architecture, simulation, space efficiency目录摘要 (1)Abstract (2)第1章绪论 (1)1.1课题背景及研究的目的和意义 (1)1.1.1 课题的研究背景 (1)1.1.2 课题的研究目的和意义 (2)1.2相关概念概述 (3)1.2.1 极限建筑空间的概念 (3)1.2.2 “包络体”的概念及构成概述 (3)1.3国内外研究现状及分析 (4)1.3.1 行为建筑学 (4)1.3.2 极限建筑空间 (4)1.3.3 包络体的应用及计算方式 (6)1.4研究内容、方法与框架 (11)1.4.1 课题的研究内容 (11)1.4.2 研究方法 (12)1.4.3 课题的研究框架 (14)第2章研究基础 (15)2.1人体运动学、运动解剖学 (15)2.1.1 人体运动形式 (15)2.1.2 人体运动的特性与坐标系建立 (15)2.2人体测量学与程序人体基本参数设定 (17)2.2.1 人体上肢静态尺寸测量 (17)2.2.2 程序人体基本参数设定 (18)2.3计算机编程 (19)2.3.1 模拟软件 (19)2.3.2 Toxiclibs类库引用与运动轨迹的向量表示 (19)2.3.3 HE_Mesh类库引用与包络曲面生成 (20)2.4本章小结 (20)第3章程序模拟 (21)3.1程序逻辑 (21)3.1.1 程序参数设定 (21)3.1.2 上肢运动轨迹模拟 (22)3.1.3 上肢运动包络体生成 (30)3.2不同人体参数对模拟结果的影响 (30)3.2.1 儿童（四肢长度对模拟结果的影响） (30)3.2.2 老年人（活动角度对模拟结果的影响） (33)3.2.3 残疾人（残肢对模拟结果的影响） (34)3.2.4 数据对比 (35)3.3“人体运动包络体”程序对行为建筑学研究方法的扩展 (36)3.3.1 行为建筑学研究的一般方法以及主要存在问题 (36)3.3.2 “人体运动包络体”模拟对行为建筑学研究方法的贡献 (37)3.4本章小结 (39)第4章 (40)4.1计算满足使用需求的极限建筑空间形态与体积 (40)4.1.1 满足功能需求，提高空间使用效率 (40)4.1.2 根据运动轨迹预测使用者所需的三维建筑空间 (45)4.1.3 节约能源 (49)4.2优化极限空间中固定物的位置与尺寸、形状 (50)4.2.1 包络体与极限空间中固定物的位置 (51)4.2.2 包络体与极限空间中固定物的尺寸 (55)4.2.3 包络体与固定物的三维空间组合 (57)4.3本章小结 (58)结论 (59)参考文献 (60)附录 (63) (74)致谢 (75)第1章绪论1.1 课题背景及研究的目的和意义1.1.1 课题的研究背景古代有蜗居的说法，用“蜗舍”比喻“圆舍”“蜗”字描述的是空间的形状，后来逐渐演变为居住空间狭小的意思。
高科技对旅游方面的影响英语作文
高科技对旅游方面的影响英语作文The Impact of High Technology on TourismThe rapid advancement of technology has transformed various aspects of our lives, and the tourism industry is no exception. High-tech innovations have revolutionized the way we plan, experience, and remember our travels. From the convenience of online booking to the immersive experiences enabled by virtual reality, the influence of technology on the tourism sector is undeniable.One of the most significant impacts of high technology on tourism is the way we plan and book our trips. The advent of online travel platforms has made it easier than ever to research destinations, compare prices, and book accommodations and transportation with just a few clicks. Travelers can now access a wealth of information about their desired destinations, read reviews, and make informed decisions about their travel choices. This has not only streamlined the booking process but has also empowered travelers to tailor their experiences to their specific needs and preferences.Moreover, the rise of mobile applications and digital tools has further enhanced the travel planning experience. Travelers can nowuse their smartphones to navigate unfamiliar cities, access real-time information about local events and attractions, and even translate languages on the go. These advancements have made it easier for tourists to explore new destinations with confidence and efficiency, ultimately enhancing the overall travel experience.Beyond the planning stage, high technology has also transformed the way we experience our travels. Virtual reality (VR) and augmented reality (AR) technologies have opened up new avenues for immersive experiences. Tourists can now virtually explore destinations, tour iconic landmarks, and even experience cultural events before physically arriving at their destination. This not only piques their interest and curiosity but also allows them to better plan and prepare for their trips.Furthermore, the integration of technology into tourism has also enhanced the safety and security of travelers. Innovations such as biometric identification, real-time tracking, and emergency response systems have made it easier for travelers to navigate unfamiliar environments and feel more secure during their journeys. This sense of safety and security can significantly contribute to the overall enjoyment and satisfaction of a travel experience.The impact of high technology on tourism also extends to the way we remember and share our travel experiences. The ubiquity ofsmartphones and digital cameras has made it easier than ever to capture and preserve memories of our travels. Travelers can instantly share their experiences on social media, allowing their friends and family to virtually join them on their journeys. Additionally, the rise of travel-focused social media platforms and online communities has created new opportunities for travelers to connect with like-minded individuals, exchange tips and recommendations, and even plan future trips together.However, the integration of high technology into the tourism industry is not without its challenges. Concerns about data privacy, cybersecurity, and the potential negative impact on local cultures and environments must be carefully addressed. As technology continues to evolve, it is essential for the tourism industry to strike a balance between embracing technological advancements and preserving the authentic and sustainable aspects of travel.In conclusion, the impact of high technology on the tourism industry is multifaceted and far-reaching. From the convenience of online booking to the immersive experiences enabled by virtual reality, technology has transformed the way we plan, experience, and remember our travels. While there are challenges to be addressed, the potential of high-tech innovations to enhance the tourism experience is undeniable. As the industry continues to evolve, it will be crucial for stakeholders to leverage technology in a way thatbalances innovation, sustainability, and the preservation of the unique and authentic aspects of travel.。
美国航天港
NO.198 世界建筑导报103 Spaceport America美国航天港美国航天港位于新墨西哥州沙漠类景观中，是目前世界上首座同类型建筑。
其设计旨在向第一批太空游客传达太空旅行的兴奋感，同时把对环境造成的影响最小化。
从空中看，此航天港让人想起维珍银河（Virgin Galactic）的眼睛品牌标志，并且让人联想到长条状的瞳孔，而停机坪则构成了虹膜。
从历史悠久的皇家大道走近，航天港的有机形态在景观中呈现出微妙的上升过程。
在一个高效、合理的计划下，航天港依据航天器的尺寸设计。
可访问性和隐私之间也要达到一种谨慎的平衡。
宇航员活动区域和游客空间与建筑的其他部分完全融为一体，而更敏感的区域——如控制室——是可见的，但进入权限有限。
游客和宇航员通过一条切断景观的深处通道进入建筑。
挡墙结构围成了一个展览空间，里面记录了太空探索的历史，以及有关该地区和定居者的故事。
通道的强线性轴线继续延伸进大楼，在一个有长廊的高度上到达超级机库——里面停有太空船并建有模拟室——穿过航站楼。
跑道上的玻璃立面在候机楼内组成了一个平台，供人们欣赏到达和离开地球的宇宙飞船。
该方案具有最低的隐含碳和少量的额外能源要求，旨在获得享有盛誉的LEED黄金级认证。
景观中的地势经挖掘后变低以利用地热，这缓冲了建筑所受的新墨西哥极端气候的影响，并利用盛行西风来通风；此外还通过天窗来最大限度地利用日光。
建筑采用了本土材料和区域性施工技术，在保持可持续发展的同时，又对周围环境保持敏感。
Located in the desert-like landscape of New Mexico, Spaceport is the first building of its kind in the world. Its design aims to articulate the thrill of space travel for the first space tourists while making a minimal impact on the environment. Viewed from space, the terminal evokes Virgin Galactic’s brand logo of the eye, and is suggestive of an elongated pupil, with the apron completing the iris. Approached from the historic El Camino Real trail, the terminal’s organic form appears as a subtle rise in the landscape.Organized into a highly efficient and rational plan, Spaceport has been designed to relate to the dimensions of the spacecraft. There is also a careful balance between accessibility and privacy. The astronauts’ areas and visitor spaces are fully integrated with the rest of the building, while the more sensitive zones – such as the control room – are visible, but have limited access. Visitors and astronauts enter the building via a deep channel cut into the landscape. The retaining walls form an exhibition space that documents a history of space exploration alongside the story of the region and its settlers. The strong linear axis of the channel continues into the building on a galleried level to the super hangar – which houses the spacecraft and the simulation room – through to the terminal building. A glazed facade on to the runway establishes a platform within the terminal building for coveted views out to arriving and departing spacecraft.With minimal embodied carbon and few additional energy requirements, the scheme has been designed to achieve the prestigious LEED Gold accreditation. The low-lying form is dug into the landscape to exploit the thermal mass, which buffers the building from the extremes of the New Mexico climate as well as catching the westerly winds for ventilation; and maximum use is made of daylight via skylights. Built using local materials and regional construction techniques, it aims to be both sustainable and sensitive to its surroundings.Client: New Mexico Spaceport Authority (NMSA)Location: New Mexico, USAArchitectural Lead Design: Foster + PartnersArchitecture and Engineering, Project Manager, Structural and MEP Engineer:URS CorporationArchitecture: SMPC ArchitectsEnvironmental Design: PHA ConsultSite Area: 27 880m2 including apronGross Area: 10 219 m2Design / Completion: 2006 / 2014Photography: Nigel Young / Foster + Partners业主单位：新墨西哥航天港项目地点：美国新墨西哥建筑设计：福斯特建筑事务所建筑工程/项目管理/结构及机电工程：URS公司合作单位：SMPC建筑师事务所环境设计：PHA咨询公司用地面积：27 880平方米总建筑面积：10 219平方米设计/建造：2006 / 2014年摄影：Nigel Young / 福斯特建筑事务所3104WORLD ARCHITECTURE REVIEW福斯特建筑事务所专辑 SPECIAL ISSUE ON FOSTER + PARTNERSNO.198 世界建筑导报105。
carry out a simulation study to
carry out a simulation study toSimulation studies are a valuable tool for understanding complex systems and processes, especially when it's not possible or practical to conduct real-world experiments. A simulation study can help to answer a variety of research questions by replicating the conditions of a real-world scenario in a controlled environment.To carry out a simulation study, you need to follow these general steps:Define the research question: Start by clarifying the purpose of your simulation study. What do you hope to learn by simulating this system or process? Identify the key variables and parameters that will be part of your simulation.Select the appropriate simulation software: There are various simulation software packages available, such as MATLAB, Simulink, or Python-based packages like SimPy or DEAP. Choose one that suits your needs and has the capabilities to handle your specific simulation requirements.Build the simulation model: Based on your research question, construct a mathematical model that represents the system or process you're simulating. This model should capture the essential features and dynamics of the system while abstracting away unnecessary details. Parameterize the model: Specify the values for the variables andparameters in your model. Collect data or make assumptions about these values based on prior knowledge or real-world observations.Run the simulation: Program the simulation using the selected software and execute it to generate results. The software will iteratively update the state of the system according to the defined rules and parameters. Analyze and interpret the results: Examine the data generated by the simulation, looking for patterns, trends, or other insights. Compare these findings with predictions or expectations based on your research question. Validate the results by comparing them with existing literature or real-world data if available.Draw conclusions: Draw conclusions from your analysis, answering your research question and addressing any limitations of your study. Use these insights to inform future research or provide practical guidance for decision-making in related fields.Communicate the findings: Share your results with others through presentations, reports, or academic publications. Provide a clear explanation of your methods, results, and their relevance to the field you're studying.Remember that the quality of your simulation study depends on the validity and realism of your model, as well as the choice of appropriate software and techniques for simulating your system or process.。
醉酒文案温柔浪漫英文句子
醉酒文案温柔浪漫英文句子1. "Sipping the intoxicating wine, I drown myself in the gentle waves of romance."2. "Let the shimmering wine unlock the doors of my heart, revealing its tender secrets."3. "In this drunken haze, love takes hold of my soul, painting a serene picture of romance."4. "Intoxicated by the enchanting spirits, I dance in the arms of love's sweet melodies."5. "Under the influence of this delicate wine, my heart finds solace in the embrace of romance."6. "In this intoxication, love's whispers become a symphony, resonating deep within my soul."7. "With every sip, the wine breathes life into my dreams, crafting a poetic tale of romance."8. "As the wine intoxicates my senses, love unveils its tender petals, blooming in every corner of my being."9. "In this tipsy state, every word becomes a love letter, every touch an invitation to a gentle dance."10. "Like the soft whispers of a love poem, this intoxication envelops me in a blanket of warmth and affection."11. "Drunk on the nectar of love, I bask in the gentle glow of romance'stender embrace."12. "With every glass, the wine paints a watercolor of love, embellishing every stroke with delicate affection."13. "In this intoxicating reverie, love caresses my heart, igniting a flame that dances in my eyes."14. "The wine's embrace is a gentle caress, a lover's touch that carries me to the realm of passion."15. "Under the influence of this velvet elixir, love's whispers become music to my soul, lulling me into a state of eternal bliss."16. "As the wine kisses my lips, love's essence lingers, filling the air with an intoxicating fragrance of romance."17. "In this inebriated dance, my heart sways to the rhythm of love, intoxicated by its tender touch."18. "With every sip, the wine entwines me in its embrace, taking me on a journey through the labyrinth of romance."19. "Intoxicated by love's sweet elixir, I am lost in a blissful haze, where tender moments become eternal memories."20. "In this state of intoxication, love's flames burn brighter, illuminating the path to a sea of passion."21. "With every glass, the wine whispers secrets of love, unraveling the mysteries of romance."22. "Savoring the bittersweet essence of love, the wine dances on mytongue, leaving behind a trail of delicate kisses."23. "In this mesmerizing haze, love seduces my senses, bewitching me with its gentle allure."24. "Drunk on this elixir, love paints our story on the canvas of eternity, capturing the essence of our romance."25. "Under the influence of this intoxicating wine, love's melodies serenade my heart, orchestrating a symphony of passion."26. "With every sip, the wine whispers tales of love, narrating a beautiful story of aching hearts and tender embraces."27. "Intoxicated by the magic of love, I dive into the depths of romance, surrendering to its gentle waves."28. "In this wine-induced reverie, love's kisses taste sweeter, its embraces softer, as if woven from the fabric of a thousand dreams."。
The_Trumpet_of_the_Swan_(Excerpt)_《吹小号的天鹅》（节选）
Crazy English2023.10Walking back to camp through theswamp, Sam wondered whether to tell hisfather what he had seen. “I know onething,” he said to himself. “I m going back to that little pond again tomorrow. And I d like to go alone. If I tell my father what I saw today, he will want to go with me. I mnot sure that s a very good idea.”Sam was eleven. His last name wasBeaver. He was strong for his age and hadblack hair and dark eyes like an Indian. Sam walked like an Indian, too, putting one foot straight in front of the other and making very little noise. The swampThe Trumpet of the Swan (Excerpt)《吹小号的天鹅》（节选）E. B. White56疯狂英语 （新读写）through which he was traveling was a wild place. There was no trail, and it was boggyunderfoot, which made walking difficult.Every four or five minutes, Sam tookhis compass out of his pocket and checkedhis course to make sure he was headed ina westerly direction. Canada is a big place. Much of it is a wilderness. To get lost in the woods and swamps of western Canada would be a serious matter. As he trudged(跋涉) on, the boy s mind was full of the wonder of what he had seen. Not manypeople in the world have seen the nest of a Trumpeter Swan.Sam had found one on the lonelypond on this day in spring. He had seen the two great white birds with their long white necks and black bills. Nothing he had ever seen before in all his life had made him feel quite the way he felt, on that wild little pond, in the presence of those two enormous swans. They were so much bigger than any bird he had ever seen before. The nest was also big with anumber of sticks and grasses. The female was sitting on eggs; the male glided slowly back and forth, guarding her.When Sam reached camp, tired andhungry, he found his father frying a coupleof fish for lunch. “Where have you been?” asked Mr Beaver. “Exploring,” replied Sam, “I walked over to a pond about amile and a half from here. It s the one we see from the air as we re coming in. It isn t much of a place —nowhere near as big asthis lake we re on.” “Did you see anything over there?” asked his father. “Well,” said Sam, “it s a swampy pond with a lot ofreeds and cattails (香蒲). I don t think itwould be any good for fishing. And it shard to get to; you have to cross a swamp.”“See anything?” repeated Mr Beaver. “I saw a muskrat (麝鼠),” said Sam, “and a few Red⁃winged Blackbirds.” Mr Beaver looked up from the wood stove, where thefish were sizzling in a pan.“Sam,” he said, “I know you like togo exploring. But don t forget these woods and marshes are not like the country around home in Montana. If you ever go over to that pond again, be careful you don t get lost. I don t like you crossing swamps. They re treacherous. You could step into a soggy place and get bogged down, and there wouldn t be anybody topull you out.” “I ll be careful,” said Sam.ReadingCheck 1. What did Sam see on the pond?2. What did Sam s father warn himabout?57。
足球相关的英文词汇
足球相关的英文词汇足球运动football；soccer；association football；socker；footy 世界杯足球锦标赛World Cup（Soccer Tournament）；FIFA World Cup 世界杯决赛World Cup Finals世界女子足球锦标赛Women’s World Cup朱尔斯·雷米特杯 Jules Rimet Cup5人足球five-a-side；futsal7人足球seven-a-side足球暴力soccer violence；riot；hooliganism足球运动员 football/soccer player；footballer；booter足球队 football/soccer team；eleven队员（守门员除外）field player后卫线back line后卫fullback/back；rear defender左/右后卫left/right back前卫线link line前卫half/halfback边前卫wing/outside half左/右前卫left/right half中前卫center half双中前卫twin center halves自由中卫free man/back；spare man；libero清道夫（＝自由中卫）sweeper盯人中卫 stopper拖后前卫deep-lying halfback；policeman锋线forward line前锋forward；spearhead；lineman双前锋twin forwards靠前的前锋spearhead forward边锋winger；wing；wing forward；outside；outside forward左边锋/左翼left wing/winger/flank；outside left右边锋/左翼right wing/winger/flank；outside right内锋inside (forward)；inner左/右内锋inside left/right拖后内锋withdrawn striker中锋center forward双中锋double center forwards；double spearheads拖后中锋withdrawn/deep-lying center forward攻击手striker中场队员midfielder；midfield player；link（man）前腰attacking midfielder双前腰double attacking midfielders后腰defending midfielder双后腰double defending midfielders2：核心队员key player；point man最佳球员（一场比赛后选出）Man of Match惯用左/右脚的left/right-footed左右开弓的double-footed积极拼抢的防守队员ball hawk观望队员（不积极主动的队员）ball watcher裁判员referee；ref；man in the middle巡边员linesman(已经弃用)助理裁判assistant referee第四官员the Fourth Official上半时/场first half下半时/场second half开球；比赛开始kick off实际比赛时间（由裁判掌握）official time伤停补时stoppage/injury time加时赛extra period；overtime突然死亡sudden death金球golden goal(已经弃用)银球（加时赛中进球后该半场仍赛完）silver goal 点球决胜penalty shootout（点球大战）出界outside；out of bounds掷界外球throw-in球门球goal kick角球corner；c orner kick获得罚角球权win a corner任意球free kick判给任意球award a free kick直接/间接任意球direct/indirect free kick定位球placekick；stationary ball踢定位球的队员placekicker严重犯规penal offence侵人犯规personal foul技术犯规technical foul故意犯规intentional foul越位offside非越位onside助理裁判用旗表示越位flag冲撞犯规charging从后面冲撞charging from behind合理冲撞legal/fair charge进行阻挡的队员blocker身体阻挡body check拉人犯规pushing推人犯规pushing3.打人striking小动作little trick/maneuver；concealed foul危险动作dangerous play抬腿过高foot over手球犯规handball；hands；handling磴踏犯规；踢人 hacking；stamping经常踢人的队员hacker绊人犯规tripping背后铲球tackle from behind铲球过迟（球已离开对方脚下）late tackle假摔fake a fall/an injury；simulation粗暴行动violent conduct延误比赛delay the game；hold up the game持球时间过长（守门员）excessive possession of the ball警告warning；caution；book黄牌yellow card红牌red card罚出场evict；eject；banish；send/order off the field；show the red card停赛一场suspend for a game以少打多play shorthanded以少打多的局面man down/short以多打少的局面power play；man/numerical advantage罚点球penalty kick；spot kick踢罚球；主罚take the kick罚中convert a penalty kick罚球未中miss a penalty kick踢球kick；boot踢球者kicker得球gain possession of the ball失球lose possession of the ball漏球miskick踢出界kick out踢球太高sky控球能力ball-control；ball-handling控球时间比ball possession percentage停球trap；stop大腿停球thigh trap胸部挡球chest停空中球stop volley停住空中球kill a ball凌空踢出volley凌空反弹踢出half volley抛球凌空踢出punt；drop volley拨球flick the ball4.扫踢sweeping kick颠球juggle踏步转身step over the ball弧线球curved/swerving ball；bend；curl内弧线inswinger外弧线outswinger跑动踢球running kick踢后前冲kick and rush无球跑动off-the-ball running转身踢turnaround kick脚背踢球instep kick内脚背infront外脚背outfront脚外侧敲击flick/jab kick脚尖踢球toe kick脚弓踢球kick with the inside of foot脚跟踢球heel kick传球pass一次/直接传球first-time pass/one-touch pass到位的传球spot/well-placed/pinpoint pass长传long pass短【近】传short【close】pass；三角传球triangular/delta pass短传配合short game短传三角配合short triangular passing深传deep pass沿边线传球flank pass传中center横传cross/lateral/line pass；cross横向转移传球square pass斜传球 diagonal pass传高球high/lob pass；loft；chip；pass in the air 地滚传球ground/rolling pass直传；向前传球forward pass大脚直传steep forward pass回传；向后传pass back脚后跟回传back-heel穿越through pass踢墙式二过一wall pass/ one-two推传push pass敲传（使用脚外侧）flick pass隐蔽传球trick pass快速传球brisk pass5.超前传球（有提前量的传球）lead pass助攻传球setup pass接传球receive a pass； pick up a pass接球失误fumble；mishandle运/带/盘球dribble；run with the ball运球队员dribbler带球过人beat；break through；dribble past盘带过多excessive dribbling头球head；nod；header（指一次动作）跳起顶球flying header；head with a jump侧顶head sideward善于顶球good in the air堵截block；clog断球intercept铲球；抢截tackle侧面铲球side tackle；side block tackle倒地铲球sliding/hook tackle抡脚铲球scything tackle铲倒对方tackle through the ball对方铲球时仍控制住球ride a tackle双方机会均等的球fifty-fifty ball混战scramble；melee；skirmish射门shoot；attempt at goal ；try for goal射手shooter；marksman进球find the net；hit home；drive the ball home 破门得分make/score/neta goal破门机会scoring opportunity射门得分者goalgetter助攻射中assisted goal连中三元；帽子戏法hat-trick扳成平局的进球equalizer射中次数shots on goal轻易射门得分sitter射门命中率shooting average/percentage未射中mishit射门过高high shot；sky从门柱弹回deflect from the goalpost；bounce back from the goalpost 射中无效goal disallowed近射close-range shot；close-up shot远射long shot/drive冲门gate-crashing突然射门snap shot劲射hard/heavy/crashing/cannon/shot；drive；thump补射tip-in6.转身射门pivot shot贴地射门；低射grazing shot一次射门first-time one-touch shot; one-touch shot调整/停球后射门second-touch shot小角度射门sharp-angled shot狭缝射门（指穿过防守线）slot倒地射门sliding shot凌空射门volley shot倒钩射门volley shot头球入门head/nod in a goal高吊球射门lob/hanging shot射空门free shot香蕉球banana shot、bending ball、curve kick乌龙球own/self goal射门的强烈欲望goal hunger庆祝进球goal celebration球门网左/右上角top left/right-hand corner of the net球门网左/右下角bottom left/right-hand corner of the net守门goalkeeping；goaltending救球save；retrieve；stop托救球finger-tip save鱼跃救球；扑救diving save挡开parry拳击球fist/punch the ball护球；抱死smother封住角度shut off the angle；cut down the angle；narrow the angle （守门员）出击come out视线受阻unsighted快攻；快速突破fast break/counterattack防守反击switch from defense to attack；counterattack；push up快速反击fast-switching attack；runback突破break；thrust中路突破thrust down the middle单刀直入solo drive突破对方防守split the defense破坏对方防守disorganize the defense拉开对方的防守面spread the defense正面进攻frontal attack边线进攻flank attack左/右路进攻attack on the left/right wing全面压上sweeping attack助攻assist穿过weave through插入cut in；penetrate7.下底drive down the sideline靠近对方球门线deep钳形攻势pincers movement摆脱动作evasive movement绕过防守队员（通过假动作）turn a defender侧步躲闪sidestep补位cover a position；fill a gap；plug a hole跑位run off the ball跑位意识positional sense跑动量（一场比赛）work-rate密集防守tight/close defense; tight/close marking 盯住mark up；get tight撤退retreat；withdraw后撤防守（引对方进入中场口袋）funnel back解围（踢开球门区）clear人墙（defensive）wall封死close off筑人墙set/line up a wall二夹一double-team前场opposing half后场own half进攻型足球offensive football防守型足球defensive football全攻全守型足球total football欧式足球European/Continental football拉丁美洲型足球Latin American football接/策应support接应位置supporting position分派位置assign position跟进trail制造空当create an opening边锋战术wing play紧靠边线hug the sideline控制中场control the midfield越位战术offside tactics/trap交叉移动scissors movement定位球战术（由固定队员主罚）set-piece playWM【3-4-3】阵式：WM【3-4-3】formationW阵式（WM阵式中的进攻部分）：W formationM阵式（WM阵式中的防守部分）：M formation4前锋【匈牙利】阵式：four forwards formation ；Hungarian formation 4后卫阵式 four backs formation3后卫阵式 three backs formation2-3-5阵式：2-3-5 formation；pyramid4-3-3阵式：4-3-3 formation；Catenaccio formation4-2-4[巴西]阵式：4-2-4[Brazilian] formation五人制比赛five-a-side game绕杆练习swerve around sticks足球场football field/pitch/ground训练场地training grid中线旗center flag中圈kickoff circle中场midfield；center field球门线goal line球门区goal area球门区线goal area line角球区corner area角旗corner flag罚球点penalty kick mark/spot罚球区penalty area/box/zone罚球弧penalty/restraining arc球门goal；nets球门口goalmouth球门柱goalpost；upright球门横梁goal crossbar球门框woodwork球门网goal net彩条球衣strip足球鞋football shoe首发阵容starting line-up降级relegation转会费transfer fee挂靴hang up one’s boots实际比赛时间actual playing time调整位置adjust one’s position提出警告administer the caution亚洲足球联合会AFC:Asian Football Confederation总分Aggregate score凶狠积极或主动积极的打法Aggressive play拼抢凶狠积极的队员，风格凶狠的队员Aggressive player空中球Air ball全攻型打法All-out attacking game业余足球运动员Amateur football player护踝Ankle pads预见，预料Anticipate上诉，申诉Appeal助攻Assist助理教练Assistant coach9.进攻Attack发动进攻Launch/initiate/start an attack对球门轮番攻击Attack after attack rolled towards the goal从两翼/侧进攻Attack down the flanks/wings攻方队员Attacker进攻型（攻式）足球Attacking football进攻型（攻式）打法Attacking play进攻三区；前场Attacking third防守三区；后场Defending third过渡三区（我自己起的名字，有好名字可以推荐一下）；中场Middle third 以进攻为主的；进攻型的Attack-oriented回传；向后传Back kick防线Back line防守补位Balancing the defense控制球Ball control控制球，运球Ball handling死球Ball out of play踢球技术Ball playing skill观望队员，在比赛中不积极主动的队员Ball watcher名词：禁止（参赛）Ban香蕉球Banana kick弧线射门Banana shot基本功（中国最缺少的）Basics基本功（基本技术）Basic skills晃过，过人；打败Beat射门意识强Be hungry for goal没打出最好水平Below one’s best替补席Bench倒钩Bicycle kick密集防守Blanket defense反方向（球场另一侧）Blind side堵截Block身体阻挡Body check身体接触Body contact狂轰滥炸Bombard警告Book（射门时）猛踢Boot球网右下角Bottom right-hand corner of the net反弹射门Bounce shot反弹；弹回Bounce界线Boundary line违反规则Breach of rules突破Break through突破Breakthrough10.破坏/瓦解进攻Break up an attack精彩的表演 Brilliant performance组织Build-up组织进攻Build up an attack争抢球；门前混战Bully冲击Bursting轮空Bye（法语）非洲足球联合会 CAF: confederation africaine de football 要球Call for the ball国脚Cap利用Capitalize on/upon队长Captain（守门员）持球行走Carry警告Caution中圈Central/Centre circle中心；v./n.传中Center/centre中场Centre field中锋Centre forward(CF)拖后中锋Centre forward playing deep中前卫（以前用的多）Centre halfback(CFB)中后卫Centre half(CH)中圈Centre spot中国足协CFA:Chinese Football Association争抢球Challenge for the ball换位Change position冠军Champions卫冕冠军Defending champions冲撞Charge从后面冲撞Charge from behind拉拉队队长Cheer-leader拉拉队Cheering squad平胸球/半高球Chest-high ball蹭球Chip蹭球Chip kick蹭传Chip pass选择场区和开球权Choice of ends and the kick-off解围Clearance密集防守Close defense势均力敌的比赛Close contest/ encounter/ game盯人Close marking紧逼对方进攻队员Close up on an attacker俱乐部Club俱乐部球队Club teamdive 鱼跃，假摔,play acting 表演（指假摔）take exception to 抗议stand 看台， stands 看台上的观众penalty area，禁区，penalty 点球，box 小禁区chip 突破bludgeon， drubbing 痛击capitulate 投降pounced on blunder from 抓住某人的失误the newly promoted 升班马snatch a victory 取得胜利maul 狂攻level，equalize 扳平haul down 拉倒，拽倒herald （观众）呼叫score, snap up, net 都可作及物动词（后加 N goals）意为“进球”wide （射门）偏出skipper 队长scout 球探dugout 教练席understudy 替补 (当然，substitute是正式用语)go nuts 情绪激动lob a pass 一记高空传球play-off 热身赛knockout round 淘汰阶段snuff out danger 化险为夷back-to-back defeats 连败clinch（seal） back-to-back titles 蝉联冠军cling on for a win 坚持到胜利starting line-up 首发阵容formation 阵形the final ball 临门一脚form （球队）状态bite the dust 惨败...unbeaten run (streak) （若干轮）不败suffer a hangover like ... 重蹈覆辙bounce back 反弹... points adrift 落后...分bust-up 争吵pour forward 大举压上bypass 过人mark 盯人on a regular basis 稳定的出场outings n.客战， away adj.客场的swoop for （俱乐部）对相中球员的追逐flying （球队成绩）出色talisman （原意为护身符）队里的重量级人物slip down 成绩下滑pull ... out of slump 带领球队走出低迷的状态boo 发出嘘声livid at 对...表示愤怒future looks bleak 前景暗淡05-06赛季的大黑马维冈：round off a rags to riches story splash the cash 烧钱mod 萃拥进球的队友（庆祝）comeback （比分）逆转，（球员）复出spurn opportunities 浪费机会mop up 解围ping crisp passes 作快速短传barge 冲撞goal drought 进球荒acute angel 刁的角度tuck the ball 把球送入concede 失球get in front 领先brittle 脆弱的suspension 禁赛on-loan 租借。
人类活动对沼泽的影响 国外案例
人类活动对沼泽的影响国外案例英文回答：Human Impacts on Wetlands: International Case Studies.Introduction:Wetlands are vital ecosystems that provide numerous ecological, hydrological, and socio-economic benefits. However, human activities have significantly impacted wetlands worldwide, leading to their degradation and loss. This essay explores case studies from different countries to illustrate the diverse impacts of human activities on wetlands.Case Study 1: Louisiana, USA.The Mississippi River Delta in Louisiana is one of the most rapidly disappearing coastal wetlands in the world. Human activities such as flood control, navigation, and oiland gas extraction have altered the natural hydrology and sediment supply to the delta,導致濕地損失。
氣候變遷加劇了這種損失，導致海平面上升和極端天氣事件頻率增加。
Case Study 2: Everglades, USA.The Everglades in Florida is a vast freshwater wetland that has been heavily impacted by agriculture, urban development, and water management. Excessive nutrientrunoff from agricultural areas has caused eutrophication and algal blooms in the Everglades, leading to habitat degradation and species loss. Water withdrawals for urban and agricultural use have disrupted the natural water flow patterns, further exacerbating these impacts.Case Study 3: Danube Delta, Romania.The Danube Delta is a UNESCO World Heritage Site located at the mouth of the Danube River. Human activities such as dam construction, river regulation, and agriculture have altered the hydrology and ecology of the delta. Dams have reduced sediment supply and altered the salinitygradient, leading to habitat changes and biodiversity loss. Agricultural practices have contributed to nutrient runoff and pollution, affecting water quality and ecosystem health.Case Study 4: Coorong, Australia.The Coorong is a large estuarine wetland system inSouth Australia. Barrages constructed to regulate water levels for irrigation and aquaculture have significantly altered the hydrology and salinity regime of the Coorong. This has resulted in changes in vegetation communities and habitat loss for numerous bird species, including migratory shorebirds.Case Study 5: Laguna de Culebrillas, Peru.Laguna de Culebrillas is a high-altitude wetland in the Peruvian Andes. Human activities such as mining, grazing, and agriculture have degraded the wetland, leading to water quality issues, habitat loss, and species decline. Mining operations have contaminated the wetland with heavy metals, while grazing and agricultural practices have alteredvegetation composition and hydrological processes.Conclusion:Human activities have had profound impacts on wetlands worldwide. These case studies demonstrate the diverse ways in which human actions can alter wetland ecosystems, including hydrological modifications, nutrient pollution, habitat loss, and species decline. It is crucial to implement sustainable practices and conservation measures to protect and restore wetlands, ensuring their continued ecological, hydrological, and socio-economic benefits for future generations.中文回答：人类活动对沼泽的影响，国外案例。
地形对战争的影响英语作文
地形对战争的影响英语作文The Impact of Terrain on Warfare。
Terrain plays a crucial role in the outcome of warfare. It can provide advantages to one side while posing challenges to the other. Throughout history, military leaders have recognized the importance of understanding and utilizing the terrain to gain the upper hand in battle. In this essay, we will explore the impact of terrain on warfare and how it has influenced the strategies andtactics of military operations.First and foremost, terrain can affect the movement of troops and the deployment of weapons. For example, mountainous terrain can hinder the mobility of ground forces and limit the effectiveness of heavy artillery. On the other hand, forests and jungles can provide cover for guerrilla warfare and ambush tactics. In addition, urban areas present unique challenges for military operations, as they require specialized tactics to navigate and controlthe environment.Furthermore, terrain can also influence the effectiveness of different types of weaponry. For instance, open fields are ideal for the use of cavalry and long-range artillery, while dense forests and urban areas favor close-quarters combat and infantry tactics. Additionally, bodies of water such as rivers, lakes, and coastlines can limit the movement of troops and provide natural barriers that must be overcome.Moreover, the natural features of the terrain can be used to the advantage of the defending force. Mountains, rivers, and other natural barriers can be strategically utilized to create defensive positions that are difficult to penetrate. This is evident in the ancient Chinese military strategy of using natural barriers such as the Great Wall to defend against invading forces.In addition to physical obstacles, terrain can also affect communication and logistics. Harsh weather conditions, rugged terrain, and long distances can make itchallenging to maintain supply lines and coordinate troop movements. This can significantly impact the ability of an army to sustain prolonged operations in hostile environments.In modern warfare, the impact of terrain remains a critical factor in military planning and decision-making. The use of satellite imagery, geographical information systems, and other advanced technologies has enabled military leaders to gain a better understanding of the terrain and its implications for military operations. This has led to the development of specialized training and equipment for operating in different types of terrain, such as mountain warfare and urban combat.In conclusion, the impact of terrain on warfare is undeniable. It influences the movement and deployment of troops, the effectiveness of weaponry, and the ability to communicate and sustain operations. Military leaders must take into account the terrain when planning and executing military operations, as it can provide both advantages and challenges that can ultimately determine the outcome of abattle. Understanding and leveraging the terrain is essential for achieving success in warfare.。
footprints in the mud of time雅思阅读
footprints in the mud of time雅思阅读Footprints in the Mud of TimeThe passage of time is an inevitable journey that shapes our lives and leaves behind a trail of footprints in the mud. These footprints symbolize the memories and experiences that define who we are as individuals and as a society. Just as the mud preserves the imprints of our steps, the passage of time creates a tapestry of stories and lessons that inform our present and inspire our future.In the realm of history, the footprints in the mud of time illuminate the path that humanity has walked. Every civilization has left behind its mark, telling a story of triumphs, struggles, and evolution. From the ancient Mesopotamians and Egyptians to the Greeks and Romans, their footprints in the historical mud have paved the way for modern society. Through their ingenuity and discoveries, we have gained invaluable knowledge and insight into our shared human experience.Moreover, individuals who have made indelible footprints in the mud of time have shaped the course of history. Leaders like Mahatma Gandhi, Martin Luther King Jr., and Nelson Mandela have left an enduring legacy through their activism and advocacy for justice and equality. Their courage and determination continue to inspire generations, reminding us of the power of one person's footprints to make a difference in the world.In the realm of science, footprints in the mud of time are synonymous with the progress of knowledge and understanding. Through the tireless efforts of countless scientists, our understanding of the universe hasexpanded exponentially. From Galileo Galilei's observations of the cosmos to Albert Einstein's theory of relativity and Stephen Hawking's work on black holes, these footprints have propelled us towards the frontiers of knowledge and opened doors to new possibilities.Footprints in the mud of time are not limited to historical events or scientific discoveries. They are also woven into the fabric of our personal lives. Each step we take, every decision we make, leaves an imprint on our own journey through time. Our footprints tell the story of our growth, achievements, and setbacks. They remind us of the lessons learned, the moments cherished, and the challenges overcome. Our footprints are a reflection of the choices we have made and the impact we have had on those around us.In the fast-paced world we live in, it is easy to get caught up in the chaos and forget the significance of our footprints in the mud of time. However, taking the time to reflect on our past and appreciate the footprints we have left behind can bring a sense of purpose and direction. It allows us to see the bigger picture and understand how our actions contribute to the collective narrative of humanity.The footprints in the mud of time serve as a reminder that our time on earth is limited. They encourage us to make the most of our days, to seize opportunities, and to leave a positive mark on the world. Each of us has the ability to contribute to the story of humanity, to shape the future for generations to come.In conclusion, the footprints in the mud of time are a testament to the journey of humanity and individuals alike. They represent our shared history,scientific progress, and personal growth. Let us cherish the footprints we have left behind and strive to make each step count as we continue on our own unique paths, leaving behind a legacy worth remembering.。
读后感：The Things They Carried 《士兵的重负》
Zhang, xxx18 Nov 2010English IIMrs. xxxThe Hump of LifeWar stories, they always keep people feeling bad and associate violence and cold-blood, the plot filled full of fighting and bloodshed. So it is fortunate to read this book, The Things They Carried, it is a story records about the experience of the narrator O'Brien during the Vietnam War, and the impact on privates including himself from war. The memories they got from the war and how these things affected them and their life after the war.O'Brien knits facts and stories throughout the book to give readers what is really likes fight in Vietnam, the sense of resistance in trek in the war. O'Brien named the book of The Things They Carried, and use the first chapter to describe everything they needed. This is a long list consist of necessities and near-necessities, such as C-rations, water, identify card; things which decided by their own duty, like lieutenant's compass and maps, medic's morphine and plasma, tents and explosives use for mountain field; and things carried individuals. "Ted Lavender carried six or seven ounces of premium dope... Norman Bowker carried a diary. Rat Kiley carried comic books. Kiowa, a devout Baptist, carried an illustrated New Testament" (O'Brien 3). Soldiers carried things that weighted dozens of pounds while walking on the land of Vietnam, under his writing, everything they carried, are their humps, and the aim is to sketch each "hump" in their deep heart. "To carry something was to hump it. In its intransitive form, to hump meant to walk, or march" (O'Brien 4). Lavender carries drugs, because he was scared of war, his dopes can keep him free from reality; the diary of Bowker, New Testament of Kiowa, comic books of Rat Kiley, is theirpray in the war; the pantyhose Dobbins wrapping around his neck, is his demand of life. "The pantyhose, he said, had the properties of a good-luck charm" (O'Brien 117).O'Brien gave soldiers various characters through the description of their humps, but under the baptism of Vietnamese flying dusts, their characteristic be destroyed, people become the moving items without feeling. In the chapter of In The Field, people who joined in the war, they are entirely trapped in the mud. "...the boy's face was impossible to make out... The men into identical copies of a single soldier,... As interchangeable units of command" (O'Brien 163). People lost their emotions in the war, keep them look like groups of dead.People don't know they need in the war, and they became confused with the war they were fighting for, including the narrator O'Brien, "I was drafted to fight the war I hated" (O'Brien 40). He thought they were fighting for a wrong war in wrong place with a wrong time, he writes things he doubted, "Was it a civil war? A war of national liberation or simple aggression?" (O'Brien 40). People hate war, and more about no reason or unknown reason war. In the movie Good Morning, Vietnam,The Cronauer repeats again and again "We come here to save you" (Levinson 1987). Will Vietnamese welcome a man who is from thousands of miles away and fighting on their land? They do not think like that, "You leave your home far away from here to kill our people...You are the enemy" (Levinson 1987). Always they just happen, and need to solve it. "It's obvious that no one really wants war, but sometimes that's just what happens" (Dalton). Only thing can do is to find a way to end it, or continue.War is always cruel, it lower the feelings of people, both the influence from the war is enormous. Usually people thought they can get out after the war, but actually, they cannot. Even for Norman Bowker, people who got seven medals from the war, he survived in the war, but he cannot forget the memories he got from the war, he firmly considers that a part of himself was already left in the war with Kiowa, and another part of him is dying in his home town after thewar, he cannot find the meaning of life. In the letter he sent to the writer, he said:"there's no place to go...It's almost like I got killed over in Nam...The night when Kiowa got wasted, I sort of sank down the sewage with him" (O'Brien 156). He killed himself later after he sent the letter to the author. "Norman Bowker, who three years later hanged himself in the locker room of a YMCA in his hometown in central Iowa" (O'Brien 154). Eventually he cannot get rid of his memories, cannot forget his emotions."I built this cross and I painted this painting, and you can see the embryo and the soldier's marching in the sky behind her; The skulls on the cross on the sticks go all the way around in the sky" (Dailey 2010). After the army, he returned and became a artist,"I became a commercial artist. I become that artist that I wanted to be. I come to California. The rest is history" (Dailey 2010). In the painting, he records his own feeling and review of the war. In the fiction, O'Brien writes stories as a narrator and the O'Brien of himself to describe the things in his experiences. He thought "For years I'd felt a certain smugness about how easily I had made the shift from war to peace" (O'Brien 157). But when he uses his pen to write what he experienced, he falls into the vortex of memory. There are a lot of stories that happened on him, which is he does not want to talk about. The memories he humped keep him fall in pain and embarrassment, remind him the war years ago. In the chapter of The Man I Killed, he write that he killed a man, and describes again and again of details of that men lying on the ground, everything he writes represent these are all truth, but, in the later chapter, when his daughter Kathleen asks if her father ever killed anyone, he answered "Of course not" (O'Brien 131), and he also said "...twenty years ago I watched a man die on a trail near the village of My Khe. I did not kill him. But I was was present,... My presence was guilt enough" (O'Brien 179), to present a story-truth, is better than half-truth, there are too many things people humped from the war, a lot of things only they can understand, to represent things in the war is painful, and other people can never understand these,never."I feel guilty sometimes. Forty-three years old and I'm still writing war stories. My daughter Kathleen tells me it's an obsession, that I should write about a little who finds a million dollars and spends it all on a Shetland Pony. In a way, I guess, she's right: I should forget it, but the thing about remembering is that you don't forget. You take your material where you find it, which is in your life, at the intersection of past and present" (O'Brien 34).Seems almost people in the war productions, ultimate would emerge the situation under O'Brien's writing: Because of the lonely, fear, the negative emotions formed by the war, because of the astonish, remorse, sorrow gave by died comrade, the war last became the feeling that is hard to erase in the life. "What neither these veterans nor their families knew was that many of these veterans were and are suffering from Post Traumatic Stress Disorder" (Vietnam War Veterans).In On the Rainy River, O'Brien describes "I was a coward. I went to the war" (O'Brien 61). The words said by the Vietnam boy "We are different" (Levinson 1987). There is no answer of justice or not, the war is hell, kill, be killed, and look at their comrades fall into mud.But those are not at all, under O'Brien' writing, Lieutenant Jimmy Cross, he carried the letters and pictures from a girl named Martha, the girl he loved. "In the late afternoon, after a day's march, he would dig his foxhole, wash his hands under a canteen, unwrap the letters, hold them with the tips of his fingers, and spend the last hour of light pretending.","More than anything, he wanted Martha to love him as he loved her, but the letters were most chatty, elusive on the matter of love." (O'Brien 1) O'Brien is sentiment, he describes a plot that looks like the story is out of the environment of the war. The pebble in Jimmy received letter from Martha that she had found on the Jersey shoreline. Because "It was this separate-but-together quality, she wrote." (O'Brien 8) " On the march, though the hot days of early April, he carried the pebble inhis mouth, turning it with his tongue, tasting sea salt and moisture." (O'Brien 8). He tries to forces himself put his attention on the war, but he just can make some phantom in daylight, finally make the bad result on his column. He had burned the letters of Martha, but cannot burn from his brain, the intangible things cannot burn by some simple gestures. Like grief, terror, love, longing,memories, fears, and desires, they are important, and cannot be discarded.When tear rolled down Tuan's face, and he said:"I stupid to save you in Anle" (Levinson 1987). As a Community-Vietnamese, he saved Cronauer from the danger region they captured. Why Tuan be friend with him, even he is already known they are in the adverse side? May be from the beginning, from the time Cronauer strike for Tuan from that Bar, keep Tuan believes in him, even in the final, they broke up their friendship, this memory, would be treasure in their mind."There was no music. Most of the hamlet had burned down, including her house, which was now in smoke, and the girl danced with her eyes half closed, her feet bare." (O'Brien 134) The girl uses her feet to dance the sacred dance. She cannot bring back her family, her village, and "the last thing she had is her memory" (Maher). This is the dance in the war, the dance in the memory. When the song What A Wonderful World voice sounded " I see trees of green, red roses too, I watch them bloom for me and you... I see skies of blue, clouds of white, bright blessed day, dark scared nights...what a wonderful world" (Levison 1987). The song filled beauty and relax, and the background, smoke is on the wind, the flames lit up the sky, they mix together, give people the sorrow feeling, like the sun hidden after clouds and ashes, spread light emotion of sad.The war story is not only describes about the war, is more about the things they carried on their body. What can never forget is the panic, the death, the emotions, the memories, those carried in the life. At last, a war story is about sunlight, it's about love and memory, about sorrow,it about sisters who never write back and people who never listen, about the girls who dancing with her last memory, a song that expressing the good of life.Works CitedO'Brien, Tim. The Things They Carried. New York: Boradway, 1998.Levison, Barry. Good Morning Vietnam. Perf. Robin Williams. Touchstone Pictures, 1987. xxx, xxx. The Big Red One. Xxx Academy, Los Angeles, California, Oct 2010.xxx, xxx. Vietnam Lecture. xxx Academy, Los Angeles, California, Oct 2010."Vietnam War Veterans." Vietnam War. 2009 </veterans/>.Philadelphia Website Design.16 Nov. 2010Dalton, Valerie. "Feelings on war." </media/storage/ paper280/news/2003/03/31/Opinion/Feelings.On.War-405170.shtml>. 31 Mar.2003.17 Nov.2010。
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Defining Control Strategies for MicroGridsIslanded OperationJ.A.Peças Lopes,Senior Member,IEEE,C.L.Moreira,and A.G.Madureira Abstract—This paper describes and evaluates the feasibility ofcontrol strategies to be adopted for the operation of a microgridwhen it becomes isolated.Normally,the microgrid operates ininterconnected mode with the medium voltage network;however,scheduled or forced isolation can take place.In such conditions,the microgrid must have the ability to operate stably and au-tonomously.An evaluation of the need of storage devices and loadshedding strategies is included in this paper.Index Terms—Dynamic response,energy storage,frequencycontrol,microgrid,power system dynamic stability,voltage con-trol.I.I NTRODUCTIONT HE need ofreducing emissions in the electricitygenerationfield,recent technological developments in the microgeneration domain,and electricity business restructuring are the main factors responsible for the growing interest in the use of microgeneration[1],[2].In fact,the connection of small generation units—the microsources(MS),with power ratings less than a few tens of kilowatts—to low voltage(LV) networks potentially increases reliability tofinal consumers and brings additional benefits for global system operation and planning,namely,regarding investment reduction for future grid reinforcement and expansion.In this context,a MicroGrid(MG)can be defined as an LV network(e.g.,a small urban area,a shopping center,or an in-dustrial park)plus its loads and several small modular genera-tion systems connected to it,providing both power and heat to local loads[combined heat and power(CHP)].The Consortium for Electric Reliability Technology Solutions(CERTS)initiated the research on the impact of connecting large amounts of dis-tributed energy resources(DER)to LV networks in order to en-hance the reliability of the electric power system and developed the MG concept[1].The MG is intended to operate in the fol-lowing two different operating conditions.•Normal Interconnected Mode—the MG is connected to a main MV network,either being supplied by it or injecting some amount of power into the main system.Manuscript received September12,2005;revised November3,2005. This work was supported in part by the European Union(EU)within the framework of EU Project MicroGrids Contract ENK-CT-2002-00610and in part by FCT—Fundação para a Ciência e a Tecnologia under Grant SFRH/BD/16473/2004.Paper no.TPWRS-00573-2005.The authors are with the INESC Porto—Instituto de Engenharia de Sistemas e Computadores do Porto and FEUP—Faculdade de Engenharia da Universi-dade do Porto,Porto,Portugal(e-mail:jpl@fe.up.pt;cmoreira@inescporto.pt; agm@inescporto.pt).Digital Object Identifier10.1109/TPWRS.2006.873018•Emergency Mode—the MG operates autonomously,in a similar way to physical islands,when the disconnection from the upstream MV network occurs.A.General OverviewIt will not be common tofind fully controllable synchronous generators in an MG,which are normally responsible for voltage and frequency control in conventional power systems.Most MS technologies that can be installed in an MG are not suitable for direct connection to the electrical network due to the character-istics of the energy produced.Therefore,power electronic in-terfaces(dc/ac or ac/dc/ac)are required.Inverter control is thus the main concern in MG operation.In[3]and[4],a control scheme based on droop concepts to operate inverters feeding a standalone ac system is presented.This concept was further developed in this research(using two different inverter control schemes)to allow for MG islanded operation.The feasibility of this operational concept has been preliminarily described by the authors in[5].Fault events that may lead to islanding of a distribution system are discussed in[6]assuming,however,that the MG (related in this case to an MV distribution system)comprises synchronous generators and grid power electronic interfaced generation units.In[7]and[8],the behavior of DER connected to distribution networks has also been addressed.However, the dynamics of the primary energy sources has not been considered,not allowing to obtain the full picture of the MG long-term dynamic behavior,which is largely influenced by the MS dynamics.The feasibility of the MG islanding mode concept was labo-ratory tested in a prototype installed in the National Technical University of Athens(NTUA),which comprises a photovoltaic (PV)generator,battery energy storage,loads,and a controlled interconnection to an LV grid[9].The converters used to couple the PV and the battery storage to the LV grid allow MG opera-tion either in an LV grid interconnected mode or under islanded conditions.Also,experimental tests for islanding and synchro-nization were presented in[9].The work described in this paper regards the evaluation, through numerical simulation,of the inverter-fed MG dynamic behavior under islanded operation for different load conditions and using two different control strategies.The impact of con-sidering the primary energy source dynamics and the inverters contributions to faults are issues addressed in this paper.The robustness of the tested control strategies was evaluated for large disturbances taking place in the MV network,followed by a forced islanding of the MG.Since there is little inertia in the MG,and MS have small time constants,a combination of0885-8950/$20.00©2006IEEEFig.1.MG architecture,comprising MS,loads,and control devices.load shedding strategies and the use of storage devices were investigated in order to avoid large frequency and voltage excursions during the operating emergency mode conditions. MatLab Simulink and its libraries(mainly the SimPowerSys-tems toolbox)were employed in order to develop a simulation platform suitable for identifying MG control requirements and evaluating MG dynamic behavior under several operating con-ditions.Different MS technologies were modeled and are con-sidered to operate together in the simulation platform.II.MG A RCHITECTUREThe MG concept adopted in this research involves an op-erational architecture,developed within the EU R&D Micro-grids project[2],[10],which is presented in Fig.1.It comprises an LV network,loads(some of them interruptible),both con-trollable and noncontrollable MS,storage devices,and a hier-archical-type management and control scheme supported by a communication infrastructure used to monitor and control MS and loads.The MG is centrally controlled and managed by a MicroGrid Central Controller(MGCC)installed at the MV/LV substation. The MGCC includes several key functions(such as economic managing functions and control functionalities)and heads the hierarchical control system.At a second hierarchical control level,controllers located at loads or at groups of loads[load con-troller(LC)]and controllers located at MS[microsource con-troller(MC)]exchange information with the MGCC that man-ages MG operation by providing set-points to both LC and MC. LC serve as interfaces to control loads through the application of an interruptibility concept that includes local load shedding schemes in emergency situations;MC control active and reac-tive power production levels at each MS.The amount of data to be exchanged between network con-trollers is small,since it includes mainly messages containing set-points to LC and MC,information requests sent by the MGCC to LC and MC about active and reactive powers,and voltage levels and messages to control MG switches.Also, the short geographical span of the MG may aid establishing a communication infrastructure using low-cost communications. The adoption of standard protocols and opentechnologies Fig.2.SOFC block diagram model.allows designing and developing modular solutions using off-the-shelf,low-cost,widely available,and fully supported hardware and software components.These solutions provide flexibility and scalability for future low-cost implementations.III.D YNAMIC M ODELING OF C OMPONENTSA set of models capable of simulating the response of the MG under several conditions was developed in order to analyze MG dynamic behavior.A.Microsource ModelingSeveral MS models,able to describe their dynamic behavior, have been developed from available literature,which include fuel-cells,microturbines,wind generators,and photovoltaic ar-rays.For illustration purposes,some details on the dynamic model developed for the solid oxide fuel-cell(SOFC)are given next. The fuel-cell includes a fuel processor that converts the used fuel in hydrogen,a power section,where chemical reactions take place,and a power conditioner that converts dc to ac power.The SOFC model adopted assumes several simplifications,such as fuel gases are considered to be ideal,it is sufficient to define only one single pressure value in the interior of the electrodes, the temperature in the fuel-cell is presumed to be always stable, only ohmic losses are considered,assuming that the working conditions are far away from the upper and lower extreme values of current,and the Nernst equation is assumed to be applicable. The complete model can be seen in the block diagram in Fig.2.A complete description on the SOFC dynamic model and its parameters can be found in[11]and[12].The GAST dynamic model[11]was adopted for the primary unit of microturbines,since these units are small simple-cycle gas turbines.Both high-speed single-shaft units(with a syn-chronous machine)and split-shaft units(using a power turbine rotating at3000rpm and a conventional induction generator connected via a gearbox)were modeled.The single-shaft mi-croturbine(SSMT)requires an ac/dc/ac converter for grid con-nection.A wind generator was also included in the library of MS using for that purpose an induction generator directly connected to the network and represented by afifth-order model,available in MatLab Simulink toolboxes.Concerning the PV generator,it was assumed that the array is always working at its maximum power level for a given temper-ature and irradiance.Basically,it is an empirical model based on experimental results as described in [13],where a detailed de-scription on MS modeling adopted in the MG project can also be found.B.Storage Devices ModelingDue to the large time constants of the responses of some MS,such as fuel-cells and microturbines,storage devices must be able to provide the amount of power required to balance the system following disturbances and/or signi ficant load changes.Considering the time period of interest for analyzing MG dynamic behavior,storage devices,such as flywheels and batteries,are modeled as constant dc voltage sources using power electronic interfaces to be coupled with the electrical network (ac/dc/ac converters for flywheels and dc/ac inverters for batteries).These devices act as controllable ac voltage sources (with very fast output characteristics)to face sudden system changes such as in load-following situations.In spite of acting as voltage sources,these devices have physical limita-tions and thus a finite capacity for storing energy.The active power needed to balance generation and consumption inside the MG is injected into the LV grid using a proportional to frequency deviation control approach (with a speci fied droop characteristic).C.Inverter ModelingTwo kinds of control strategies may be used to operate an in-verter.The inverter model is derived according to the following control strategies.•PQ inverter control:the inverter is used to supply a given active and reactive power set-point.•Voltage source inverter (VSI)control:the inverter is controlled to “feed ”the load with pre-de fined values for voltage and frequency.Depending on the load,the VSI real and reactive power output is de fined.In [14],more details on these control strategies can be found.It must be highlighted that,when analyzing the dynamic be-havior of the MG,inverters are modeled based only on their control functions so that fast switching transients,harmonics,and inverter losses are neglected.This is the general procedure adopted,as described in [3],[6]–[8],[14],and [15].1)PQ Inverter Control:The PQ controlled inverter operates by injecting into the grid the power available at its input.The re-active power injected corresponds to a pre-speci fied value,de-fined locally (using a local control loop)or centrally from the MGCC.The PQ inverter control is implemented as a current-con-trolled voltage source,as shown in Fig.3.Current components inphase andquadrature with the inverter terminal voltage are computed based on a method presented in [9]for power calculation in single-phase inverters.Power variations in the MS induce a dc-link voltage error,which is corrected via the PI-1regulator by adjusting the magnitude of the active current output delivered to the grid.The reactive power output is con-trolled via the PI-2regulator by adjusting the magnitude oftheFig.3.PQ inverter controlsystem.Fig.4.Frequency versus active power droops.inverter reactive current output.This inverter can be operated with a unit power factor or receive a set-point (locally or from the MGCC)for the output reactive power.2)VSI Control:The VSI emulates the behavior of a syn-chronous machine,thus controlling voltage and frequency on the ac system [3],[4],[9].The VSI acts as a voltage source,with the magnitude and frequency of the output voltage con-trolled through droops,as described in the followingequations:(1)whereand are the inverter active and reactive power out-puts,and are the droop slopes (positive quantities),andand are the idle values of the angular frequency and voltage (values of the inverter angular frequency and terminal voltage at no load conditions).When a VSI is interconnected with a stiff ac system,char-acterized by an angularfrequencyand terminalvoltage ,the voltage and frequency references are externally im-posed [9].In this case,the desired outputpowersand can be obtained in the VSI output by adjusting the idle values of the angular frequency and voltage as follows (see Fig.4):(2)Fig.5.VSI model.If a cluster of VSI operates in a standalone ac system,fre-quency variation leads automatically to power sharing,such that for a systemwith VSI,the following equalitystands:(3)withbeing the power variation in the th VSI.The fre-quency variation can be computedas(4)Similar considerations can be made for the voltage/reactive power VSI control mode based on droops [3],[4].However,as voltage has local characteristics,network cable impedances do not allow a precise sharing of reactive power among VSI.A three-phase balanced model of a VSI implementing the de-scribed droop concepts was derived from a single-phase version presented in [16]and shown in Fig.5.A complete description on VSI modeling can be found in [16]and [17].The VSI terminal voltage and current are measured in order to compute active and reactive powers.This measuring stage introduces a delay for de-coupling purposes.The output voltages are the reference signals that control the VSI switching sequence using a PWM modula-tion technique.In terms of standalone ac system operation,this control prin-ciple allows the VSI to react to system disturbances (for ex-ample,load or generation changes)based on information avail-able at its terminals [4].In this way,the operation of a stand-alone ac system like an MG does not rely on fast communica-tions between MS controllers,which could be impractical [3].However,a communication infrastructure will be available in the MG,with the purpose of allowing an optimal management,not requiring fast communication capabilities.3)Inverter Control During Transient Overloads and Short Circuits:Inverter overcurrents can be caused by transient over-loads (due to the connection of a large amount of load in is-landed mode)or by short circuits.When moving to islanded operation or when a large load is connected during islanded operation,the initial high imbalance between local load and generation may lead to large frequency deviations and transient overload of the VSI,since this unit has a fast response to this type of situations.In order to overcome this problem,the following two solutions were adopted.•Allow a temporary disconnection of less important loads (load shedding activated by under-frequency relays);•Up-rate the VSI,allowing an overload situation during a certain time interval (at least greater than the one required for load shedding activation).Due to the nature of the control of PQ inverters,they are not signi ficantly affected by transient phenomena like load changes or power variations in renewable DER.Conventional power plants comprising synchronous genera-tors directly connected to the network provide large short-circuit currents,which are very helpful for fast and ef ficient fault de-tection and elimination.However,in an MG where generation units are mainly connected to the grid through power electronic interfaces,it is dif ficult to obtain high fault currents.Solid state switching devices used in inverters are selected based on voltage,current carrying capability (under certain cooling con-ditions for a de fined switching frequency)and safe operating areas.The islanded system can ride through short-circuits if there is suf ficient oversizing of power electronic interfaces,since they have no thermal short-term overcurrent capabilities,in contrast to synchronous generators.At the same time,a novel protection scheme for the MG must be developed using different types of relays and section breakers instead of con-ventional fuses.Accordingly,the following considerations are in order.•The VSI was selected to be up-rated in order to provide a signi ficant contribution to short-circuit currents (ranging from 3–5p.u.)due to conventional overcurrent protection devices.•PQ inverters can provide only a small amount of short circuit current (1.5–2p.u.).After a short-circuit,the time interval in which large cur-rent outputs are absorbed from the VSI is dependent on the impact caused by the dynamics of induction machines (oper-ating as motors or generators).Induction machines can recover from short-circuits if the stability limit is not over-passed and enough reactive power is provided by external sources.In this case,the VSI will provide reactive power within the speci fied current limits and this behavior will be sustained until the in-duction machines recover.Thus,it is also important that the VSI are able to sustain overcurrents for a time interval larger than the one required for fault clearance.The PQ inverter control scheme allows a simple control over the output inverter current during short-circuit conditions by limiting the total gain of the PI controllers shown in Fig.2.Acting as a voltage source,the output current of a VSI tends to be very high (similarly to what happens in a conventional syn-chronous machine).In order to limit its output current,a con-trol technique such as the one presented in Fig.2is used.The main difference is that in this case,the current reference has a maximum peak value dependent on the characteristics of the solid-state switches,and its frequency is imposed by inverter frequency/active power work and Load ModelingIn this paper,the evaluation of the feasibility of MG islanded operation was performed through the analysis of the LV network dynamic behavior considering only three-phase balanced oper-ation,despite the fact that this is not the most common situation in LV distribution networks.Two load types were considered:constant impedance loads (dependent on frequency and voltage)and motor loads (induction motor with nominal power rangingbetween3and10kW).Electrical parameters of motor loads are typical values available in MatLab Simulink SimPowerSystems toolbox.As will be shown,load characteristics greatly influ-ence the dynamic behavior of the MG,mainly under short-cir-cuit conditions.Controllable loads in the MG,available for load shedding pur-poses,have also been modeled.The amount of load to be shed is defined based on the amplitude of frequency deviation.In this study,motor loads have not been considered as sheddable loads.IV.MG C ONTROL FOR I SLANDED O PERATION Islanding of the MG can take place by unplanned events like faults in the MV network or by planned actions like maintenance requirements.In this case,the local generation profile of the MG can be modified in order to reduce the imbalance between local load and generation and reduce the disconnection transient[6]. In the presence of unplanned events like faults,MG separation from the MV network must occur as fast as possible.However, the switching transient will have great impact on MG dynamics. If there are no synchronous machines to balance demand and supply,through its frequency control scheme,the inverters should also be responsible for frequency control during is-landed operation.In addition,a voltage regulation strategy is required;otherwise,the MG might experience voltage and/or reactive power oscillations[18].If a cluster of MS is operated within an MG and the main power supply(the MV network) is available,all the inverters can be operated in PQ mode, because there are voltage and frequency references.In this case,a sudden disconnection of the main power supply would lead to the loss of the MG,since there would be no possibility for load/generation balancing and therefore for frequency and voltage control.However,by using a VSI to provide a reference for voltage and frequency,it is thus possible to operate the MG in islanded mode,and a smooth moving to islanded operation can be performed without changing the control mode of any inverter[9].As previously described,the VSI can react to network disturbances based only on information available at its terminals.This working principle of a VSI provides a primary voltage and frequency regulation in the islanded MG.After identifying the key solution for MG islanded operation,two main control strategies are possible:a)single master operation (SMO)or b)multi master operation(MMO).In both cases,a convenient secondary load-frequency control during islanded operation must be considered to be installed in controllable MS.A.Single Master OperationA general overview of an SMO is shown in Fig.6.In this case,a VSI—acting as master—can be used as voltage refer-ence when the main power supply is lost being that all the other inverters operated in PQ mode(slaves).Local MS controllers can receive information from the MGCC about the generation profile and control accordingly the corresponding MS.B.Multi Master OperationAs described in Fig.7,in a multi master approach,several in-verters are operating as VSI with pre-defined frequency/active power and voltage/reactive power characteristics.The VSIcan Fig.6.Control scheme forSMO.Fig.7.Control scheme for MMO.be coupled to storage devices(batteries orflywheels)or to MS with storage devices in the dc-link(batteries,super capacitors), which are continuously charged by the primary energy source. Eventually,other PQ-controlled inverters may also coexist.The MGCC can modify the generation profile by changing the idle frequency of VSI and/or by defining new set points for control-lable MS connected to the grid through PQ-controlled inverters.C.Secondary Load-Frequency ControlEquation(4)shows that the VSI active power output is pro-portional to the MG frequency deviation.If the MG frequency stabilizes in a value different from the nominal one(due to the use of only proportional droop controls),storage devices would keep on injecting or absorbing active power whenever the fre-quency deviation differs from zero.This should be only admis-sible during transient situations,where storage devices are re-sponsible for the primary load-frequency control.Storage de-vices(batteries orflywheels with high capabilities for injecting power during small time intervals)have afinite storage capacity and can be loaded mainly by absorbing power from the LV grid. Therefore,correcting permanent frequency deviations during any islanded operating conditions should then be considered as one of the key objectives for any control strategy.In order to promote adequate secondary control aiming to re-store frequency to the nominal value after a disturbance,two main strategies can be followed:local secondary control,by using a PI controller at each controllable MS(Fig.8)or central-ized secondary control mastered by the MGCC.In both cases, target values for active power outputs of the primary energy sources are defined based on the frequency deviation error[19].Fig.8.Local secondary load-frequency control for controllablemicrosources.Fig.9.LV test network.For SMO,the target value is directly an active power set-point sent to the prime mover of a controllable MS (see Fig.2),while for MMO,the target value can be both an active power set-point for a controllable MS connected to a PQ inverter or a new value for the idle frequency of a VSI.V .S IMULATION P LATFORMA simulation platform under the MatLab Simulink environ-ment was developed in order to evaluate the dynamic behavior of the MG.An LV test network was built based on a system de fined by NTUA and used to test both presented control strate-gies (SMO and MMO).A detailed description of the test system and its electrical parameters can be found in [20].Fig.9shows the MG single-line diagram.The implementation of the LV test network under the MatLab Simulink environment is shown in Fig.10.VI.R ESULTS AND D ISCUSSIONDisconnection from the upstream MV network and load-fol-lowing in islanded operation was simulated in order to under-stand the dynamic behavior of the MG and to evaluate the ef-fectiveness of the developed control approaches.MG islanding can occur in two different situations (scheduled islanding and forced islanding)with possible faults taking place in the MV or LV grids.Due to space limitations,only results from forced islanding,due to faults in the MV grid,are described next.InFig.10.LV network for the Matlab Simulink simulation platform.this scenario,the SOFC and the SSMT are supposed to be the controllable MS used for the secondary load-frequency control using the scheme depicted in Fig.8.Two load/generation sce-narios using the single master operation strategy with a VSI and MMO were tested,with the corresponding results described next.A.Single Master OperationThe scenario is characterized by a local load of 80kW (65%of impedance type and 35%of induction motor type)and a local generation of 50kW (high load scenario).A fault in the MV sideoccurredatfollowed by MG islanding 100ms after.Due to the large initial frequency deviation,a certain amount of load is automatically shed through the activation of under-fre-quency load shedding relays in order to aid frequency restora-tion.This load is later reconnected in small load steps,to avoid load disconnection by activating the under-frequency load shed-ding relays.Load reconnection in small steps allows the evalu-ation of the MG behavior under load-following conditions (see Fig.11).The principles described for current limitation in inverters can also be observed in Fig.12for the VSI for a PQ-controlled in-verter (SOFC inverter).The reacceleration of motor loads leads to a relatively slow ramping up of the voltage after fault clearing.Motor loads and asynchronous generators absorb high currents after disturbanceFig.11.MG frequency,VSI active and reactive power,and SOFC and SSMT active power (high loadscenario).Fig.12.Detail of the VSI and SOFC terminal voltages and currents during and subsequent to the MV fault and islanding procedure (high load scenario).elimination,which lead to the activation of the short-circuit cur-rent limitation function in the VSI,as depicted in Fig.12.After fault elimination,there is a transient period for restoring normal operation of asynchronous generators,which also contributes to the impact on inverter current and voltage,as it can be observedin Fig.12after.Thus,a slower restoration of the MG voltage is observed.In this case,no motor loads were discon-nected because all of them were able to successfully reaccelerate after fault elimination.Asynchronous generators (the split-shaft microturbine and the wind generator)were not disconnected in order not to lose generation.In Fig.13are shown the time evolution of the terminal volt-ages in the VSI and SOFC and the generated reactive power in the SOFC and SSMT.The voltage/reactive power droop is the only mean used for voltage control during islanded operation.Thus,it is responsible for compensating reactive load transients as can be observed in Fig.11.Reactive power in PQ-controlled inverters is kept constant (reactive power support)due to the control scheme described in Fig.3.Fig.13.V oltages and reactive powers (high loadscenario).Fig.14.MG frequency,VSI active and reactive power,and SOFC and SSMT active power (low load scenario).A low load scenario with power being exported to the MV network was also tested.The scenario is characterized by a local load of 56kW (70%of impedance type and 30%of induction motor type)and a local generation of 73kW.Fault conditions are those previously described.The MG control strategies applied are valid for any operating conditions.The key issue for successful MG islanded operation is the management of load shedding and the state of charge of the storage devices.In this case,the MGCC should manage the state of charge of the storage so that it absorbs the power gen-eration surplus after an unpredicted system islanding,as can be observed in Fig.14.In both scenarios (high and low load condi-tions),a slow frequency restoration process that results from the large MS time constants can be observed.During this phenom-enon,the VSI is responsible for a continuous matching between load and generation.B.Multi Master OperationIn order to analyze the initial dynamic behavior of an MG under a multi master approach,the dynamics of the primary en-ergy sources can be neglected due to the high storage capacity。
她影响了我的人生作文英语
In the tapestry of life,there are threads that stand out for their vibrant hues and the profound impact they leave on the canvas.One such thread in my life is the influence of a woman who,through her actions and words, has left an indelible mark on my journey.This woman,a beacon of inspiration,has not only guided me but also profoundly shaped the person I am today.Her name is Mrs.Thompson,and she was my high school English teacher. From the moment she stepped into the classroom,her presence was commanding yet warm,inviting students to engage with her in a way that was both challenging and nurturing.Her eyes sparkled with a passion for literature and a genuine desire to ignite the same flame in her students.The first lesson I learned from Mrs.Thompson was the power of language. She would often say,Words are the tools of the mind they can build bridges or walls.This resonated deeply with me,as I was a shy teenager who struggled to express myself.Through her patient guidance,I learned to harness the power of words to articulate my thoughts and emotions. She encouraged us to read widely,from the classics to contemporary works,and to delve into the nuances of language that could convey complex ideas and emotions.One of the most significant impacts Mrs.Thompson had on my life was her emphasis on empathy and understanding through literature.She believed that reading was not just about absorbing information but about stepping into the shoes of different characters and experiencing their lives.This approach opened my eyes to the diversity of human experiences and theimportance of empathy in navigating the world.Mrs.Thompson also instilled in me the value of perseverance.There were times when the intricacies of English literature seemed overwhelming,and the essays felt insurmountable.Yet,she was always there,offering constructive feedback and encouraging me to push through the challenges.Her belief in my abilities was a driving force that helped me to develop resilience and a growth mindset.Beyond the classroom,Mrs.Thompsons influence extended to my personal life.She had a knack for identifying the unique strengths of each student and nurturing them.For me,she recognized my interest in writing and provided a platform for me to explore and develop this passion.She organized writing workshops,encouraged me to participate in essay competitions,and even invited me to join the schools literary magazine as an editor.One particular incident stands out as a testament to Mrs.Thompsons impact.During my senior year,I was selected to represent the school in a statewide essay competition.The pressure was immense,and I was on the verge of doubting my abilities.Mrs.Thompson,sensing my anxiety,pulled me aside and shared a quote by Ralph Waldo Emerson:Do not go where the path may lead,go instead where there is no path and leave a trail.Her words,coupled with her unwavering support,gave me the courage to step out of my comfort zone and embrace the challenge.The result was a victory that was not just personal but also a testament tothe power of mentorship.Mrs.Thompsons influence did not end with that victory it continued to shape my academic and professional choices.I pursued a degree in English Literature,inspired by her passion and dedication.Today,as an educator myself,I strive to emulate her example, aiming to inspire and guide my students in the same way she did for me.In conclusion,the influence of Mrs.Thompson has been a transformative force in my life.Her commitment to teaching,her belief in the power of literature,and her unwavering support have not only shaped my academic journey but also my approach to life.As I reflect on her impact,I am reminded of the profound role that mentors play in shaping the lives of others.Mrs.Thompsons legacy is a reminder that the threads we weave into the tapestry of others lives can leave a lasting and meaningful imprint.。
in the autumn of例句
in the autumn of例句In the Wake of Autumn《秋来之后》文/席慕容When moonlight once again paves the mountain trail from where you come I hope you believe thatI have already recovered from the will to escape当月光再次铺满你来时的山径希望你能够相信我已痊愈自逃亡的意念From the edge of hiding myself under a pseudonym and other similar desires From a heart of panicFrom a fate of begging自改装易容隐姓埋名以及种种渴望的边缘自慌乱的心自乞怜的命运From a plot that remains in coherent after a hundred alterationsFrom a hurt that is absolutely tender and absolutely sharp自百般更动也难以为继的剧情自这世间绝对温柔也绝对锋利的伤害When speaking of the wake of autumnno one knows better than me若说秋来没有人能比我更加明白There are always a few woodland to shed their leavesAlways some dreams to be buried总有些疏林会将叶落尽总有些梦想要从此埋没Some individualsInsisting on varying the colors and textures under the shadow of darkness 总有些生命坚持要独自在暗影里变化着色彩与肌理And now observe strictly the distance between hoping and imaging Never again will I involve the depth of events我会记得你的警告从此严守那观望与想象的距离永不再进入事件的深处Not to drench in the river of sorrowsnor to pick fruits of regrets不沾忧愁的河水不摘悔恨的果实When moonlight once again paves the mountain trail from where you depart I don't know if you are willing to believe当月光再次铺满你离去时的山径不知道你愿不愿意相信Yet I have truly recovered having learnedNot to argue for truth, just letting it fade away like the falling of leaves但是我确实已经痊愈已经学会不再替真相辩解任由它湮灭一如落叶And endlessly edit out those excess worries(Those excesses are but the withered twigs serving only to prick one's skins)并且不断删节那些多余的心事（多余的徒然在前路上刺人肌肤的枯枝）On the days in the wake of autumn, I Can almost be mistaken forA hopelessly optimistic woman在秋来之后的岁月里我几乎可以被错认是一个无可救药的乐观女子。
浙江省温州市乐清外国语学校2022-2023学年九年级上学期期末英语试题
浙江省温州市乐清外国语学校2022-2023学年九年级上学期期末英语试题学校:___________姓名：___________班级：___________考号：___________一、完形填空Sometimes my bad mood feels like quicksand, and the harder I try to climb out, the more stuck I get! That was true last week. I was reading a book. I had just come to the most“Haha! Definitely.” I laughed.“Hey!” said Craig. “That 14 you just made sounded a lot like a laugh.”Just when I think I’ll 15 be in a bad mood, I’m suddenly on the other side of it. I smiled. “Possibly.”1．A ．whoB ．whatC ．whenD ．where 2．A ．heldB ．sentC ．turnedD ．opened 3．A ．angrilyB ．silentlyC ．carelesslyD ．proudly 4．A ．nothingB ．anythingC ．somethingD ．everything 5．A ．leftB ．dancedC ．droveD ．returned 6．A ．todayB ．tonightC ．tomorrowD ．yesterday 7．A ．hopedB ．endedC ．sharedD ．started 8．A ．changeB ．chanceC ．secretD ．reason 9．A ．onlyB ．evenC ．alsoD ．still 10．A ．inB ．onC ．byD ．for 11．A ．broke upB ．broke inC ．broke downD ．broke off 12．A ．adviceB ．courageC ．surprisesD ．decisions 13．A ．lyingB ．sittingC ．jumpingD ．hanging 14．A ．poemB ．songC ．noiseD ．story 15．A ．oftenB ．alwaysC ．neverD ．hardly16．Where is the Solar Egg Frying Competition held?A．Texas.B．Austin.C．Arizona.D．South America. 17．When is the day about a drink from South America?A．June 4.B．June 11.C．September 9.D．December 13. 18．What can we learn from the three titles?A．Dates of some surprising holidays.B．Important holidays in the US.C．Places for celebrating different holidays.D．Reasons to celebrate a few holidays.Without the Internet or phones, communicating long distance is limited. Yet throughout history, cultures have developed ways to produce messages that travel miles. Morse Code is a system of communication. It uses patterns of signals to send and receive messages, often with a machine called a telegraph.A telegraph is a machine that creates different signals from different messages. These signals are then changed into electrical current. They are sent across a wire. They can travel long distances, such as across the country or ocean. Another telegraph receives these signals. The machine changes the signals back into the original message.In Morse Code, there are three types of signals. They are dots, dashes, and pauses. Dots (•) are the short noises or flashes of light. Dashes (━) are longer noises or flashes of light. Spaces (____) are the pauses. Patterns of these signals represent letters, numbers, and punctuation marks. In Morse Code, letter A is one dot and one dash, letter E is one dot, letter Iis two dots. As for consonants, letter C is one dash, one dot, one dash and one dot, letter D is one dash and two dots, Letter T is one dash.Morse Code was invented in the United States by Samuel Morse during the 1830s. People soon realized that the code could not transmit all messages in other languages. To fix this problem, a newer version called the International Morse Code was developed. International Morse Code is simpler and more exact. For example, the original Morse Code could only represent a few of the letters. The International Morse Code, on the other hand, is for all letters.19．According to Paragraph 2, how does the telegraph work?━The signals are sent across a wire.━The signals are changed back to letters.━Another telegraph receives these signals.━The telegraph changes signals to electricity.A．━━━━B．━━━━C．━━━━D．━━━━20．Look at the signals: •━━•━•━, which of the following do they mean?A．Cat.B．Act.C．Eat.D．Ted. 21．What happened after Morse Code couldn’t work in other languages?A．It became very popular.B．People stopped using it.C．The telephone was invented.D．A newer version was created. 22．What is the writing purpose of this passage?A．To explain a secret message.B．To introduce a type of phone.C．To show a way to communicate.D．To tell stories of an old machine.Cathy Hackl’s son wanted a party for his 9th birthday. He wanted to hold the party on Roblox, a website where users can play and create games. Roblox is part of the metaverse. This is a virtual-reality space. There, users can interact with other people and digital environments. Virtual reality is a three-dimensional simulation of a real-life image or environment. “They hung out and played, ” Hackl said, “Just because it happens in a virtual space doesn’t make it less real.” The term metaverse has become popular. Today, people arespending more of their lives in virtual spaces.The word metaverse comes from a science fiction book from the 1990s. But the metaverse has been around longer than that. Online communities have existed since the 1980s. We enter the metaverse through a screen. This could be through virtual reality(VR). It could also be through augmented reality(AR). Augmented reality covers computer-generated images on the real world. These experiences create a greater blending of our virtual and real lives. But these two worlds already cannot be separated and we don’t even need any headsets, such as VR glasses. Think about the Didi Taxi app. It uses location data to tell drivers where their cars are.The metaverse is an expansion of the Internet. There are lots of Internet problems to solve already. Still, many people say it has real benefits. They say it can increase social networks and improve mental health. Hackl is a metaverse expert, and she’s African. She says, “You can encourage a lot more people to join and build social relations.” For those already spending part of their life in the metaverse, that building has begun.Carrie Tatsu runs a business in the metaverse. But she wants her kids to spend time in the real world. “It’s so important for humans to be with humans in real life, ” she said, “I think as kids grow up in this space, it’s important for them to take part, go smell a flower here, walk on a trail, have a real conversation with a friend. Even though you can simulate that, the simulation is not the same. ”23．How does the writer lead in metaverse in Paragraph 1?A．By telling stories.B．By listing numbers.C．By describing people.D．By comparing facts.A．Changing.B．Entering.C．Mixing.D．Reaching. 25．What’s the structure of the passage?A．B．C．D．26．Which of the following can be the title for the passage?A．Metaverse: virtual spaces online.B．Metaverse: a science-fiction book.C．Metaverse: a popular computer game.D．Metaverse: businesses on the Internet.三、多任务混合阅读I ran back to Grandpa’s garden as fast as I could with Grandpa’s dog, Bandit. “Grandpa, I heard something strange in your woods!” I told him.“Let’s go and find out what it is, Sarah,” he took my hand. My grandpa lives alone near the woods. Sometimes I go into the woods with Bandit and pretend I am Sarah the Adventurer. But I can’t go past the big rock so that Grandpa can always see me from the garden.As we hiked toward the big rock, there was that sound! Cack-cack-cack-cack! “What is that, Grandpa?” I whispered.“It’s the first sign of spring,” he said. “How about you go past the big rock a bit to find out what it is.”“No,” I looked at Grandpa. His whole face seemed to be smiling. I wondered what an adventurer would do. “Grandpa,” I said, “I think I can do it.”Grandpa said, “It’s all right, just a little further.”As I went past the rock, suddenly there was silence. When I got closer, I heard Grandpa say, “Just sit down and watch.”I sat down but I didn’t see any animals. Just ahead of me there was a big puddle. Then I found something in the puddle. “Frogs!” I shouted.“They’re calling because it’s time for them to lay eggs. Next time we’ll check for tadpoles,” he told me.On my next visit, I went straight down to the puddle with Grandpa. To discover the frogs, I walked closer to the puddle. “Keep going, Sarah, just a little further,” Grandpa said.I took a big pace forward. I’m Sarah the Adventurer!Soon I saw some brown tadpoles. I got one tadpole home.Grandpa helped me feed it. Each time I came, it was bigger. First, its back legs came out. Then front legs. Grandpa said, “it’s time for it to return home.”This time, I was brave enough to go ahead of Grandpa. I reached into the jar and got the little tadpole. I hold it out to the water. It wouldn’t move. “It’s all right, just a little further,” I said. I touched its tail, and it jumped right into the water.As I headed back, holding Grandpa’s hand, I looked back and smiled. There wassomething special in Grandpa’s woods.27．Why did Sarah run back to Grandpa’s garden?A．Sarah fell off the big rock when climbing.B．Sarah heard a strange noise in the woods.C．Sarah heard Bandit barking at something.D．Sarah saw tadpoles jumping out ofa puddle.28．What happened after Grandpa told Sarah to sit down and watch?A．Sarah took Grandpa’s hand.B．Sarah hiked toward the big rock.C．Sarah saw several frogs in a puddle.D．Sarah pretends to be Sarah theAdventurer.29．Which of the following describes Grandpa?A．Grandpa thinks Sarah’s fears are silly.B．Grandpa is kind and patient with Sarah.C．Grandpa is worried about Sarah in the woods.D．Grandpa thinks Sarah should treat animals better.40 words. ）四、多句选词填空五、短文汉语提示填空根据短文内容和所给中文提示，用单词的正确形式完成下列短文。
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2
r
2
(9)
(10)
V表示涡的强度。它的绝对值等于涡流速度最大切向分量的绝对值。V > 0表示涡的旋转方向是逆时针 方向。在仿真中，V可以认为等于均匀流的马赫数。这保证了扰动强度随均匀流的速度呈线性分布。 初始涡的长度设定为 r0
5 103 倍的弦长。它的初始位置为 x0 0.66, y0 0.070 ，即涡心在
1600 附近的振动是由
压强信号（该压强信号在作用时间 内会引起小幅振动）上的高频小振动引起的。下游方向的噪声强度与 期望的马赫数的4次方成比例较吻合。
网格法的影响 为了确定网格法对计算结果的影响，我们再对三种形状的后缘分别使用精细网格，这种精细网格是把 原有粗糙网格的网格间距在各个方向上均二等分得到的。 图14分别展示了M＝0.3条件下的粗糙网格和精细网格上的钝头形和圆形后缘上方R ＝0.6 圆圈上的压 强信号分布。首先，从图中可看出两个网格上的曲线的第一个极值点几乎在同一水平，但是，粗糙网格上 的第二个极值点较精细网格上略大。粗糙网格上，在 1.0 T 情形下的压强信号就几乎一样。 值得注意的是，粗糙网格上初始涡的低精度解的影响与波传播的影响不能明显地区分开。 图15和16分别展示了M＝0.3时粗糙网格和精细网格上涡后缘相互作用开始（T 1.1）时的钝头形后缘 和圆形后缘附近的压强场和涡强场。 从图中可看出， 粗糙网格和精细网格上的压强图和涡强图均非常相似。 因此，我们认为，粗糙网格法在这两种情形下并不是很差。 图17分别展示了粗糙网格和精细网格上圆形后缘情形的指向性图。正如在讨论压强信号时所期望的， 精细网格上的噪声强度较小。同样可得出，在下游方向声强与马赫数4次方成比例。图18展示了M＝0.3时粗 糙网格和精细网格上三种后缘情形下的指向性。同样可以看出，精细网格法得到的值较小，但噪声强度的 定性走势在两种网格上是一致的。 实验同样得出钝头形后缘比尖角形后缘情形的声强更大。Brooks 和 Hodgson（参17）曾经测量过NACA 0012翼型在不同锐度后缘情形下的后缘噪声。 他们发现， 钝头形后缘比尖角形后缘的噪声强度普遍大约2dB。 这 相 当 于 压 强 幅 度 的 1.25 倍 ， 可 以 和 图 10 中 的 压 强 幅 度 进 行 比 较 ， 从 图 10 中 可 以 得 出
指向性和马赫数缩放律 指向性定义为相对于随着均匀流一起移动的参考基准的方位角，它与声场强度 I 有关。声场强度是
（11） 由于压强值（以下用
pc 表示）被记录在了绕后缘的圆（R=0.6， ）上，需要把它转化到移动的参考基
准 上 。 这 个 过 程 可以用 一 个 简 单 的 几 何转化 来 近 似 。 我 们 可得到 如 下 公 式 ：
外廓的边界层之外。涡心距壁面的距离约为0.015倍的弦长。图7和图8分别展示了粗糙网格和精细网格上的 初始涡的速度u和速度矢量的外廓形状。从图中可看出，粗糙网格上求解的初始涡不是很精确。
流场的发展 图9展示了在M＝0.3时钝头形后缘情况的压强场随时间的典型发展过程。由于初始流场没有初始化即 没给出正确的初始密度和压强扰动，所以在开始计算时会出现初始压强脉冲（图9a）。这个初始噪声波在 后缘处发生衍射并且在涡后缘相互作用开始前就基本离开了计算的范畴。 当T＝1.125的初始涡到达后缘时， 会产生一个压强脉冲（图9b）。这个压强波在上游方向以很明显的程度传播通过控制区域（图9c）。与此 同时，涡传导到更远的下游区并且几乎没有伴随新噪声的产生（图9d）。从图中半径R＝0.6的圆上可以看 出，用于计算指向性的压强值被记录在了该圆上。图10分别展示了在M＝0.3情况下压强信号在三种后缘上 方的圆周方向的位置。在T 0.5时的初始压强脉冲到达控制点而T 1.0时的初始压强脉冲在后缘处产生可 以辨别的衍射。大约在T 1.8时，由涡后缘相互作用引起的信号到达它的第一个极值点。圆形后缘的压强 极值点是最大的而尖角形后缘的最小。
尽管在当前研究分析时没有考虑非线性影响，但为了完整起见，扰动方程将以 PIANO 码的形式给出来 （这种形式考虑了高阶非线性项）。
（2）
(3)
(4)
表示气体比热容。当 0 时，可得到常见的线性欧拉方程。详细推导过程见参考文献 9.
数值算法： 这些方程的求解是在一个多块结构的网格上完成的。每一个方块都有一个曲线坐标 x( , , ) ，连续 变量 ( , , ) 与网格上每一个独立节点的指数值是对应的。空间导数大约精确到 4 阶 DRP 模型。关于时 间的积分可以通过 4 阶 Runge-Kutta 法来完成。根据 Tam and Webb 得到入流和出流的边界条件。 过滤： 由于采用的 DRP 方案不存在发散问题，需要消除一种有效的假想波（这种波是不可能在数值网格上求 解的） 。 通常的做法是人工选择抑制。 由于微分方程中一些额外的项不得不计算， 因此这种方法非常昂贵。 一种更为方便的方法是在流场计算过程中周期性地运用合适的数字滤波器。在 PIANO 码中，对称的 6 阶和 8 阶滤波器是有效的。6 阶（N＝3）和 8 阶（N＝4）滤波器定义如下：
(6) (7)
i 过滤量， i 是未过滤量。滤波器被运用到计算机计算 ( , , ) 空间，随后又被运用到多维空间问题
上。 为了能把这些滤波器应用到最初垂直于壁面的N层，必须确定超过壁面范围的N个坏点的数据。这里介 绍一种最简单的方法，就是镜像壁面场的值。进一步的探究需要改进坏点值的筛选方法。 在当前研究过程中，8阶滤波器在粗糙网格中没20个时间步长用一次，在精细网格中没40个时间步长 用一次。 后缘形状 首先考虑钝头形后缘的翼型。图1展示了该翼型后缘的几何形状和粗糙 CAA网格。圆形后缘（图2）是 通过把翼型上下表面用Bezier曲线（由连接点处的连续一阶导数得到）连接而产生的。尖角形后缘（图3）
0.25( i 1 2 i i 1 ) ，为了降
低某些小的振动， 的值沿上述R = 0.6的圆平滑分布。下标i代表圆上的记录位置。压强被记录在圆与网 格线的所有交点上。 图11、12和13分别展示了钝头形、圆形和尖角形后缘情况下的指向性。从图中可以看到，圆形后缘噪 声强度最大，尖角形后缘的噪声强度最小。在M＝0.3圆形后缘（图12）情况下
p 。
（1）
0 ， v v0 v ， p p0 p
是扰动量的度量。 , v和p 是扰动值。 下标 0 表示均匀流的参数， 所有的量都可以通过引入参考密度 、
参考长度 L 和参考速度 a （无穷远来流声速）而化为无量纲的形式。
y0 得到）可以得到速度场
e ln 2( r0 ) r0V e 2 ln 2
r
2
（8）
r ( x x0 ) 2 ( y y) u y V 2e ln 2 e r0 x x0 ln 2( r0 ) v x V 2e ln 2 e r0
（12）
当n=0.5时，有 圆上的角度 通过如下关系式可转化为角度 ：
（13）
（14）
＝0表示沿下游方向。求 I c ( ) 的积分式近似为：
（15）
(16) 积分边界 t0到t1 应选择在距涡后缘相互作用产生的压强信号足够远的点。 是压强信号最大值和最小值对 应的时间差，并且可以认为是涡后缘相互作用的时间的度量。根据 i
到3.2 106 。
几种情况下的升力系数见表1。在三种情况下的参考长度均取1.0。注意，钝头形和尖角形后缘的差异 主要是尖角形后缘外廓的弦长较大引起的。 图4分别展示了钝头形、圆形和尖角形后缘在M＝0.3的条件下的压强分布。由图4可看出，只有在接近 后缘的区域 c p 的差异才略微显示出来。
CAA网格和初始条件 为了确定网格法的作用，我们来比较两种CAA网格：粗糙网格和精细网格，精细网格仅仅是把粗糙网 格的网格间隔在所有方向上均二等分而得到的。图5和图6分别展示了粗糙网格上钝头形后缘和圆形后缘的 CAA计算结果。尖角形后缘的情况与钝头形后缘的情况非常接近。图中白色小圆圈表示初始涡的位置。表2 给出了不同网格的节点数目。 密度场和压强场的初始扰动置为0。从单个涡的长度 r0 （由它的坐标 x0 ， 的初始扰动。它的流动方程和速度分别为：
是通过把翼型上下表面的直线延长相交得到的。
均匀流的计算 RANS均匀流是通过DLR FLOWER码来计算的。这种代码是在一种多块网格上解N-S方程的。在应用Wilcox 的k
w 模型的两个方程时，需要把振荡影响考虑进去。侧面攻角是 60 。分别在马赫数为0.2、0.3、
6
0.4时计算均匀流动。雷诺数变化范围为 1.6 10
翼型后缘形状对气动噪声产生的影响的仿真
Markus Lummer¤, Jan W. Delfsy, and Thomas Lauke¤ German Aerospace Center (DLR), Lilienthalplatz 7, D-38108 Braunschweig
译者：邵壮 西北工业大学航天学院
i a0 i a j ( i j i j )
j 1
N
（5）
6阶滤波器的系数为：a0 = 0.6875 ; a1 = 0.46875 ; a2 = 0.1875 ; a3 = 0.03125 8阶滤波器的系数为：a0 = 0.7265625 ; a1 = 0.4375 ; a2 = 0.21875 ;a3 = 0.0625 ; a4 = 0.0078125
翼型后缘与旋涡强度的相互作用是机体噪声的一个重要来源。在本论文中，将通过二维 CAA 计算一个 现代飞机的一般翼型的后缘与单个涡的相互作用的来研究这个问题。本文的主要目的是找出不同后缘形状 对噪声场产生的影响因素。因此，除了研究原始的的钝头后缘形状外，还要研究圆形和尖角形状的后缘。 研究发现，圆形后缘产生最大的压强信号而尖角形后缘产生最小的压强信号。在流动下游方向上的噪声强 度理论上与马赫数的 4 次方成正比。为了确定网格法对结果的影响，计算过程被呈现在单格二等分的精细 网格图上。精细网格法得到更小的压强幅值，但是与采用粗糙网格相比，得到相同的定性趋势。无法计算 独立网格块的解的最可能的原因应该是在粗糙网格上不能令人满意的求解初始涡。 前言 气动噪声产生的一般机制是边界层涡与翼型后缘之间的相互作用。几种不同复杂程度的方法已经被用 来预测这种流动下噪声的产生。 其中有一种经典的分析调查法， 它建立在 Lighthill 的声学分析的基础上， Lighthill 的声学分析导出了著名的马赫数缩放定律。近年来，随着计算机和现代计算声学（CAA）的发展 应用，基于 CFD 的噪声产生与传播的数值仿真或大型涡流仿真已经实用化。虽然理论上这些方法可以得到 噪声场的全部信息，但是却非常昂贵，并不适合日常工程中使用。 下面将介绍一种相对较经济的不同方法，这种方法将流场分为均匀流、紊流和声学波动。均匀流可以 用雷诺数平均方程来近似求解，紊流波动可以用 SNGR 模型求解，声学波动可以用线性或非线性的干扰方 程来求解。这种方法源自 DLR 在 CAA 编码 PIANO 的发展。 由于非线性的影响在声学中相对较小，在研究噪声在后缘产生时只考虑均匀流中分离涡的对流是可行 的。在早期的一篇论文中，论文作者已经研究了非线性因素在单个涡与 Joukowsky 对称翼型后缘在零度攻 角下相互作用中的影响。Joukowsky 对称翼型的后缘趋于无限薄，是一个学术性的例子。在本文中，以一 架普通现代飞机的典型翼型作为研究对象，来研究涡、后缘相互作用而引起的噪声问题。 后缘噪声的产生一方面与后缘的几何形状有关，另一方面又与后缘周围均匀流场的细节情况有关。为 了确定这些影响，我们在 RANS 均匀流中用线性欧拉方程来分别求解钝头形、圆形和尖角形后缘的涡和后缘 的相互作用。 这篇论文的组织如下：首先，我们先给出用到的干扰方程，并简要介绍求解这些方程的数值方法。其 次，考虑后缘几何形状并在 RANS 均匀流中的计算得到一些信息。再次，得出 CAA 网格和 CAA 计算的初始条 件，把流场演进的简要概览以结果形式呈现出来，接着得到不同后缘和马赫数在 0.2 到 0.4 之间变化条件 下的正式图案。再次，通过二等分网格间距得到精细网格从而确定网格法的作用；接下来，对数值渗透过 程的影响作一个简要分析。最后，给出结论并作总结。 控制方程 当前研究所用到的干扰方程是线性欧拉方程，这些方程由理想气体的质量守恒定律、动量守恒和能量 守恒推导得到，假设理想气体扰动场的密度、速度和压强分别为： 、 v 和