lab8-2
实验报告(二)
北京信息科技大学信息管理学院实验报告课程名称java程序设计实验项目实验二类和对象实验仪器PC、jdk、jcreator专业_______ _________班级/学号________ ___学生姓名_______ __________实验日期实验地点成绩_______________________指导教师_____李春强_____________return p;}int getPower(int q){return q;}}Lab2_2：public class TV {void play(){System.out.println("正在播放动物世界");}}public class Family {TV homeTV;void buyTV(TV tv){tv=this.homeTV;System.out.println("购买一台电视");}}public class MainClass {public static void main(String args[]){ TV haierTV=new TV();Family zhangsanFamily =new Family();zhangsanFamily.buyTV(haierTV);haierTV.play();}}Lab2_3：public class Land {public static void main(String args[]){ Village.WaterAmount=200;System.out.println("水井中有水"+Village.WaterAmount+"升");Village v1=new Village();Village v2=new Village();int m=50;System.out.println("v1从水井中取水"+m+"升");v1.WaterAmount-=m;System.out.println("v2发现水井中有水"+Village.WaterAmount+"升");System.out.println("v2从水井中取水"+m+"升");v2.WaterAmount-=m;System.out.println("v1发现水井中有水"+Village.WaterAmount+"升");}}public class Village {public static int WaterAmount;}Lab2_4：import wukong.xiyou.*;public class SunRise{public static void main(String args[]){SquraEquation sq=new SquraEquation();sq.getRoot(100);System.out.println("此数的平方根为"+"sq.getRoot()");}}package java.wukong.xiyou;public class SquraEquation{public double getRoot(double num){ return Math.sqrt(num);}}1.实验名称、实验目的、实验内容、实验要求由教师确定，实验前由教师事先填好，然后作为实验报告模版供学生使用；2.实验准备由学生在实验或上机之前填写，教师应该在实验前检查；3.实验过程由学生记录实验的过程，包括操作过程、遇到哪些问题以及如何解决等；4.实验总结由学生在实验后填写，总结本次实验的收获、未解决的问题以及体会和建议等；5.源程序、代码、具体语句等，若表格空间不足时可作为附录另外附页。
LAB的作业程序
B實驗流程 B實驗流程
委托單位填寫 實驗委托單
委托部門主管簽核
實驗人員評估 及主管簽核
實驗
NG Yes
NG
QE&工程分析 工程分析 R&D確認 確認
Yes
繼續實驗 實驗中止
量測結果及報告B實驗流程 B Nhomakorabea驗流程1.PQA Test:
Plan從MFG借出產品並 (1)QE人員依照PQA Test Schedule&PQA Test Plan從MFG借出產品並 )QE人員依照PQA 人員依照 與實驗委托單一起送至實驗室. 與實驗委托單一起送至實驗室. 實驗室工作人員依實驗委托單&PQA (2)實驗室工作人員依實驗委托單&PQA Test Schedule & PQA Test Plan所要求的測試項目進行檢測 所要求的測試項目進行檢測. Plan所要求的測試項目進行檢測. (3)實驗室工作人員在實驗中發現的不良現象將會立即知會給相關部 門知悉,並將其列入Bug List中 門知悉,並將其列入Bug List中,且每日都會更新當日測試進度給 相關部門. 相關部門. 實驗完畢後,實驗室將提供相應的測試報告.測試機台將交由QE QE或 (4)實驗完畢後,實驗室將提供相應的測試報告.測試機台將交由QE或 委托者做後續處理. 委托者做後續處理.
Lab ORT Bug List
3.各種表單的填寫 3.各種表單的填寫
3-3.Test Item
Lab Test Item
4.可靠度的認識 4.可靠度的認識
定義: 定義: 過各種環境試驗、 可靠度試驗則是透 過各種環境試驗、統計方法技巧 化或壽命， 與加速試驗理論之運用來概估產品之可靠度變 化或壽命， 可作為產品品質與成本評估之重要指標與依據 PQA : Product Quality Assurance ORT: On going Reliability Test 產品品質保證 可靠度實驗
面试运维的面试题目(3篇)
第1篇一、基础理论题1. 请简要介绍Linux操作系统的特点及其在运维工作中的应用。
解析：Linux操作系统具有开源、稳定、安全性高、可定制性强等特点。
在运维工作中，Linux操作系统被广泛应用于服务器、存储、网络等领域，如Web服务器、数据库服务器、文件服务器等。
2. 什么是IP地址？请解释IPv4和IPv6地址的区别。
解析：IP地址是互联网中用于标识设备位置的数字标识。
IPv4地址采用32位表示，分为A、B、C、D、E五类，其中A、B、C类地址用于公共网络，D类地址用于多播，E类地址为保留地址。
IPv6地址采用128位表示，采用冒号分隔的十六进制形式，旨在解决IPv4地址耗尽的问题。
3. 请解释TCP/IP协议栈中的TCP和UDP协议的区别。
解析：TCP（传输控制协议）是一种面向连接的、可靠的、基于字节流的传输层协议，适用于传输大量数据、需要保证数据完整性的场景。
UDP（用户数据报协议）是一种无连接的、不可靠的、基于数据报的传输层协议，适用于传输少量数据、对实时性要求较高的场景。
4. 请解释DNS域名解析的过程。
解析：DNS（域名系统）是一种将域名转换为IP地址的系统。
域名解析过程如下：（1）本地DNS缓存查询：首先，DNS服务器会检查本地缓存中是否有对应的域名解析记录。
（2）递归查询：如果本地缓存中没有记录，DNS服务器会向根域名服务器查询顶级域名服务器（如.com、.cn等）的IP地址。
（3）迭代查询：顶级域名服务器返回相应的权威域名服务器的IP地址，DNS服务器再次查询该权威域名服务器。
（4）获取IP地址：权威域名服务器返回对应的IP地址，DNS服务器将IP地址返回给客户端。
5. 请解释HTTP协议的工作原理。
解析：HTTP（超文本传输协议）是一种应用层协议，用于在Web浏览器和服务器之间传输数据。
HTTP协议的工作原理如下：（1）客户端发送请求：客户端（如浏览器）向服务器发送HTTP请求，包括请求方法（如GET、POST）、URL、协议版本、请求头等信息。
LabX Laboratory Software 2 连接实验室仪器说明书
Power Your Titration Benchwith LabX®L a b o r a t o r y S o f t w a r e2C o n n e c t Y o u r L a bSingle SoftwareFor Many Laboratory InstrumentsThe new LabX ® from METTLER TOLEDO offers a great new possibility to con-nect your titrators, balances, density meters and refractometers, melting point instruments and Quantos systems all with one single software. This uniform software and interface means less training and also helps toincrease your efficiency. With a unique approach, LabX allows you to work from either the instrument or PC or both and if required, with complete compliance.Reducing redundant software for different instruments helps you save time and money spent on maintenance and support. Use LabX to increase the efficiency of your workflow and eliminate waste by using LabX for your pa-perless lab documentation. Inte-grate LabX with 3rd party software such as LIMS, ERP , etc. for a fully integrated process.LabX offers many tools to help you optimize your workflow in the laboratory and increase efficiency. Connect your METTLER TOLEDO instruments to LabX and benefit from simplified operation, efficient method editing with the graphical layout, fast sample series modi-fications and tailored reports.Less training also means less time and money spent educat-ing your workforce. LabX offers the same concept of use for all instruments. Beyond that, users will recognize similar workflow concepts throughout the instrument terminals for fast adaptation to new instruments and seamless integration.Cost EffectiveWorkflow Optimization Less Training3LabX offers you all the conve-nience of centrally managed software. With one database all users have access to the same data, which can be restricted to the appropriate access accord-ing to your user management. Create your SOP methods once and all the instruments from dif-ferent laboratories will always have access to the latest version.Central Management4Work from PC or Titrator or Both For Flexible OperationAll methods and series are stored in one database. Thus the meth-ods and sample series that you create in LabX or at the instru-ment are always available wher-ever you are. Beyond that, the ti-trator and workbench intelligently display solely those methods and sample series that can be run by the selected titrator model.Each instrument connected to LabX has its own workbench correlating to that instrument. It offers all the components needed to run your daily tasks and the tools to monitor your sample series and results. Use the sta-tistics view for quick and easy inspection of results to see if they are within established limits.LabX offers you full flexibility for the way you want to work. Either start your analysis at the instrument or from the PC and have constant access to both your current sample analysis and latest results. No matter where you are use LabX Mail to receive a tailored message with the latest results, when a sample changer is ready to test new samples or when results are out of specification.LabX anticipates the different demands of users and the way they like to work. Thus, LabX of-fers you full flexibility wherever you work. For example: start your sample series at the titrator and move to other daily tasks. Open up the workbench from your office and monitor the same series you previously started.Methods & Series WorkbenchFlexible Operation F u l l F l e x i b i l i t y5Have access to your results from the titrator or your PC. Use search folders to structure results from different analyses. LabX offers you a sample and a series based view of your results to match your needs. Each series offers the statistics tab for a quick and simple overview of the results. Use LabX to simplify sample changer operation with thetransparent and easy-to-manage sample series tables. Track the state of your series from any LabX connected PC in your laboratory. Alter your series by adding or inserting urgent samples while operating.Whether you are on the go or cur-rently not located next to your titra-tor or LabX network, use LabX Mail to have messages or results sent to you. Increase your efficiency by receiving tailored messages: e.g. “Results out of specifications” or “Ready for more samples”.Results Automation LabX Mail6Execute Your Daily TasksWith One Click®Use the Scheduler to automati-cally start tasks, e.g. begin Karl Fischer pretitrations just before coming into the lab for the day. Or schedule LabX to do the daily sensor calibration for you. Periodically take samples of production-line baths to observe the correct ion concentrations.Execute your tasks with One Click. Simply create a shortcut to methods, sample series, series sequences, tasks or manual op-erations, e.g. drain your beaker to waste, and have direct access to your most common analyses. All the shortcuts you create at the workbench are also displayed at the titrator and vice versa.Excellence Balances connected to LabX have a dedicated entry point for titration tasks that re-quire weighing. Simply pick the task and the balance will guide you through the samples. Start your titration and add more sample weights as you‘re test-ing for improved productivity.One Click is a well-recognized concept of METTLER TOLEDO instruments. LabX offers you the same concept and helps to easily distribute shortcuts for different users over various instruments. To facilitate your workflow, LabX offers the task scheduler and SmartCodes ™ to automate youranalyses. Use SmartSample ™ for secure and efficient titration weighing.O n e C l i c k A p p r o a c hSchedule TasksShortcuts Simple Weighing7Remove transcription and order-ing errors as well as improve effi-ciency with the new SmartSample RFID technology workflow. Identify and weigh your titration samples at an Excellence Analytical Bal-ance with the SmartSample kit. Enter the sample identification (ID) at the balance to make sure the ID and weight are properly as-signed to the physical sample. Fully automate the selection of the correct method and transcription of samples IDs with a barcode or SmartSample RFID tag. Thus, eliminate sample order errors by reading the sample information as you test it, as well as ensur-ing the right method is selected for each product. Use the auto-mated 1D and 2D barcode reader with InMotion ™ Autosamplers.SmartSample ™ SmartCodes ™8R e g u l a t o r y C o m p l i a n c eTraceable and CompliantEnsured with LabX®Work from the instrument or PC and LabX will ensure that you are fully compliant with regulatory standards such as FDA 21 CFR Part 11. Use the services offered from METTLER TOLEDO for software verification (IPac) or full validation of your system with the Validation Manuals I & II. A sophis-ticated user management, electronic signatures and release process for methods and reports are additional handy features of LabX that support your daily reporting.Centrally set up the user manage-ment with users and assign rights to roles. Instruments connected to LabX have the same user man-agement, i.e. use the same login at the instrument and PC, to offer full traceability whether you work at the instrument or in LabX. Enforce your own account poli-cies to meet company or regula-tory guidelines and standards.The LabX Initial Software verifica-tion Package (IPac) is a service product of METTLER TOLEDO to ensure successful software instal-lation and proper operation at the installation site. Use the IPac to meet your standards for quality management and documentation. IPac contents are:– Installation Qualification (IQ)– Operational Qualification (OQ)– General System Suitability TestFor software validation in ac-cordance with regulatory bodies such as FDA, METTLER TOLEDO offers onsite validation support with the Validation Manuals I and II. Validation Manual I of-fers the necessary documenta-tion for vendor qualification and Validation Manual II for the validation of the software including installation and opera-tional qualification (IQ & OQ).User ManagementIPac Validation Manual I and II9The Regulation option of LabX server provides all the necessary tools to meet the FDA regulation (21 CFR Part 11) for data ma-nagement and storage. All rele-vant actions taken at the instru-ment or PC are recorded in the audit trail of LabX for full traceabi-lity and flexibility, no matter where you work.To differentiate between devel-opment and the final version of methods, report templates and other objects can be approved and then released. Use the flexible views at the titrator and LabX to display only the released method for daily use or switch to the lat-est amended method for any further modifications needed.Define your electronic signa-ture policies according to your standards. For example, make sure that new methods follow your own review and approval process before they are released for your daily applications in the lab. Reviewed objects such as methods, results or reports, etc. are protected from any alteration.Regulatory Compliance Propose & ReleaseElectronic Signature10M o d u l a r A p p r o a c hBuild the SystemThat Perfectly Matches Your NeedsLabX ® offers a modular licensing approach to meet your needs today and in the future. Choose the starter pack that suits your requirements and add optional licenses to match your customized needs. Integrate additional instruments to your LabX system by simply activating the relevant instru-ment license key in LabX.Titration Starter PacksIncluded Optional11automatically into LabX creating tasks or even start the analyses directly. Import and export data directly in CSV and XML formats. Exporting and importing was never more powerful and able to meet your needs.Straight fingerprint reader. With the regulation option combined with the user management option, your system will be audit-ready at any time.system integration option allows bi-directional integration. Centrally start and control tasks directly from your ELN or LIMS. These 3rd party systems are able to send tasks directly to the METTLER TOLEDO instrument touchscreen terminal.freely customize reports with all details and options, such as charts, plots, and tables.* Only available with LabX Serverrights each user or role is given. Login to all your instruments and PCs on your LabX net-work with the same username and password or fingerprint via the LogStraight™ fingerprint reader.OptionsName DescriptionPart bX IPacLabX Initial Software verification Package (IPac) ensures successful software installation51710898LabX Validation Manual I All information necessary for the qualification of METTLER TOLEDO as the software supplier (vendor qualification)30003640LabX Validation Manual II Starterpack TitrationAll instructions and forms necessary for the validation of the software (IQ, OQ).30097758LabX ® Servicesfor efficient LabX system qualification and validation/LabXTitrationMultiparameter Analysis with One Click ®Today’s quality control and testing labs have a multitude of tests to be per-formed on a single sample and often have multiple samples to run at the same time. Combining tests with a multiparameter system can op-timize accuracy and reproducibility while saving valuable time and en-suring proper correlation of results to sample identification.Benefits of a Multiparameter Analysis System:• Efficient high sample throughput• Robust system layout and smart security checks for reliable unattended operation • Simple and ergonomic operation – pleasant to work with, short learning period • Optimized for fast, accurate and repeatable tests, and cleaning • Secure data handling thanks to our powerful LabX ® software• Onsite METTLER TOLEDO service installation, qualification and training See what METTLER TOLEDO can do to optimize your lab with a Multipa-rameter Analysis system: /titration-multiparameterFor more informationMettler-Toledo AG, Analytical CH-8603 Schwerzenbach, Schweiz Tel. +41 44 806 77 11Fax +41 44 806 72 40Subject to technical changes© 10/2013 Mettler-Toledo AG, 30100354Marketing Titration / MarCom AnalyticalQuality certificate. Development, production and testing according to ISO 9001.Environmental management system according to ISO 14001.“European conformity”. The CE conformity mark provides you with the assurance that our products comply with the EU directives.One Click is a Registered Trademark of METTLER TOLEDO in Switzerland, the European Union, Russia and bX is a Registered Trademark of METTLER TOLEDO inSwitzerland, USA, China, Germany and a further 13 countries.。
外研版高考英语一轮总复习课后习题 选修6 Module 2 语言运用题组——求精准
选修6 Module2语言运用题组——求精准(30mins)Ⅰ.完形填空(河南开封第一次模拟考试)Are all inventors scientists?No.Anyone can make a(n) 1 .All it takes is a(n) 2 and some hard work.A person must be willing to try again and again 3 the invention works.That’s just what happened to James Murray Spangler in 1907.Spangler was a cleaner at a department store.He 4 to work every night after the closing.He 5 his job,but it was a lot of work to clean all that space.He was 6 .He wished that there was a better way to clean the store’s floor.Each night as he worked,he thought about the 7 .What kind of machine could he make?After a while,some ideas formed in his head.He got a group of 8 ,including an old box,a tape,a pillowcase,an electric fan,a broom handle,and a paint roller.Then he spent weeks fitting them together.He tried it at home.It9 !At last,he was ready to take his invention to the 10 .A police officer was walking down the street.He glanced at the department store window.He saw Spangler 11 his invention.The officer went to the owner’s house,12 the owner that Spangler was doing something with a(n) 13 machine that made a lot of noise.He thought that Spangler had lost his mind.The 14 rushed to the store.He told Spangler that he was fired for messing around 15 doing his job.Spangler told him that he was doing his job 16 than ever before.He asked the store owner to let him show how his machine worked. 17 ,the man agreed.He was 18 when Spangler moved his machine over dirt and gum wrappers.They 19 !Spangler had just built the first vacuum cleaner.The next year he sold his invention to a firm named Hoover.Before long vacuum cleaners were as 20 as stoves in homes.1.A.observation B.mistakeC.planD.invention2.A.topic B.theory C.idea D.excuse3.A.though B.until C.once D.after4.A.started B.failed C.agreed D.decided5.A.found B.liked C.quit D.knew6.A.ashamed B.frightenedC.worriedD.exhausted7.A.accident B.discoveryC.problemD.eachines B.objectsC.picturesD.books9.A.worked B.changed C.stopped D.arrived10.A.store B.hotel b D.station11.A.showing B.improvingingD.designing12.A.threatening B.convincingC.showingD.telling13.A.old B.cool C.huge D.strange14.A.janitor B.policemanC.ownerD.customer15.A.instead of B.because ofC.thanks toD.as for16.A.worse B.better C.slower D.busier17.A.Excited B.SatisfiedC.CuriousD.Afraid18.A.confused B.shockedC.disappointedD.amused19.A.disappeared B.continuedC.droppedD.moved20.A.simple B.safeC.convenientmonⅡ.语法填空(福建福州诊断性联考)Our ancestors did it out of necessity,but we are returning to their ways out of a desire to preserve the planet 1.future generations.Clair Jackson investigates the return of our make-do-and-mend and it turns out that “fast” fashion has been replaced by a “slow” fashion 2.(move).A report that 300,000 tons of 3. (use) clothing ends up in UK landfill every year has led to a comeback ofmake-do-and-mend,encouraging increasing numbers of people to take a renewed interest in maintenance,4. (buy) second-hand clothes and to choose quality over quantity.“There used to be a feeling of shame attached to wearing second-hand clothes,” reflects Anita Taylor,a shop owner.“We’re now meeting people 5. are sourcing their clothes from agencies such as ours,having been committed to not buying anything new for a year.”In days gone by,wearing a 6. (visible) mended jacket would have been considered an embarrassment,but now it may be prized for 7. (it) beauty and practicality.Despite the growing interest in mending,basic sewing skills—particularly among younger generations—8. (be) surprisingly scarce(不足的).If you really can’t fix something,you can always repurpose it.By the way,it’s all 9. matter of taste.No matter 10. my mother-in-law may say,I happen to like my silver bracelet made out of an old fork very much.选修6 Module2 语言运用题组——求精准Ⅰ.【语篇导读】本文是一篇记叙文。
2024高考巴蜀圆锥曲线解答题解析
2024高考巴蜀圆锥曲线解答题解析一、解答题1．（23-24高三下·重庆·阶段练习）已知抛物线()2:20E y px p =>，O 是坐标原点，过()4,0的直线与E 相交于A ，B 两点，满足OA OB ⊥．(1)求抛物线E 的方程；(2)若()0,2P x 在抛物线E 上，过()4,2Q -的直线交抛物线E 于M ，N 两点，直线PM ，PN 的斜率都存在，分别记为1k ，2k ，求12k k ⋅的值．3【点睛】方法点睛：求定值问题常见的方法有两种：（1）从特殊入手，求出定值，再证明这个值与变量无关；（2）直接推理、计算，并在计算推理的过程中消去变量，从而得到定值．2．（23-24高三下·重庆·阶段练习）已知抛物线2:4,,C x y M N =为抛物线C 上两点，,M N 处的切线交于点()00,P x y ，过点P 作抛物线C 的割线交抛物线于,A B 两点，Q 为AB 的中点.(1)若点P 在抛物线C 的准线上，（i ）求直线MN 的方程（用含0x 的式子表示）；（ii ）求PMN 面积的取值范围.(2)若直线MQ 交抛物线C 于另一点D ，试判断并证明直线ND 与AB 的位置关系.【答案】(1)（i ）012y x =【详解】（1）（i ）设点221212,,,44x x M x N x ⎛⎫⎛⎫ ⎪ ⎪⎝⎭⎝⎭，因为抛物线2:4C x y =，得12y x '=，则()21111:42MP x l y x x x -=-，整理得2111124y x x x =-①，()22221:42NP x l y x x x -=-，整理得2221124y x x x =-②，联立①②得()0120121214x x x y x x ⎧=+⎪⎪⎨⎪=⎪⎩，因为点P 在抛物线C 的准线上，即直线1y =-上，所以124x x =-，设直线MN 的方程为y kx b =+，斜率必存在，联立24=+⎧⎨=⎩y kx bx y ，消去y 得2440x kx b --=，所以212012Δ161604244k b x xk x x x b ⎧=+>⎪+==⎨⎪=-=-⎩，得0121k x b ⎧=⎪⎨⎪=⎩.所以直线MN 的方程为0112y xx =+；（ii ）由（i ）得21x x -=（2）直线ND 与AB 平行，证明：直线AB 斜率必存在，设消去y 得20444x kx kx -++=则()2034340161610444k kx x x k x x kx ⎧-+>⎪+=⎨⎪=+⎩，得则直线(21:4MQ x l y k x x '-=-()2122011214442x k k x x x k x ----=-整理得()(221284k x x k ---则2211112842D kx k x kx x x k x -+-=-则2101284142D kx k kx y k x ⎛-+-= -⎝【点睛】方法点睛：对于直线和圆锥曲线相交的问题，我们一般联立方程，然后用韦达定理来解决问题，特别是当一个交点知道的情况下，3．（23-24高三下·重庆·阶段练习）已知()()122,0,2,0C C -，动点P 满足1PC 与2PC 的斜率之积为定值14.(1)求动点P 的轨迹Γ的方程；(2)过点()4,0M 的直线l 与曲线Γ交于,A B 两点，且,A B 均在y 轴右侧，过点A 作直线:1l x '=的垂线，垂足为D .（i ）求证：直线BD 过定点；（ii ）求MBD 面积的最小值.【答案】(1)(22104x y y -=≠(2)（i ）证明见解析；（ii ）3【分析】（1）设动点P 的坐标，由题意列式并化简，即可得答案；（2）（i ）设直线方程:l x my =结合题意有(2212212240Δ644884124m m m m y y m y y m ⎧-≠⎪=-⎪⎪-⎨+=⎪-⎪⎪⋅=<-⎩解得22m -<<，且122my y =又直线BD 的方程为1y y -=令0y =，则()122111y x x y y -=--()(122121235422=y y y y y y y y ++-=-4．（23-24高三上·重庆·阶段练习）已知点00(,)P x y 是椭圆E :221(0)a b a b +=>>上的动点，离心率2e =设椭圆左、右焦点分别为12,F F ，且12|||4|PF PF +=(1)求椭圆E 的标准方程；(2)若直线12,PF PF 与椭圆C 的另一个交点分别为A ，B ，问PAB 面积是否存在最大值，若存在，求出最大值；若不存在，请说明理由.【点睛】方法点睛：圆锥曲线中最值或范围问题的常见解法：（1）几何法，若题目的条件和结论能明显体现几何特征和意义，（2）代数法，若题目的条件和结论能体现某种明确的函数关系，则可首先建立目标函数，再求这个函数的最值或范围．5．（23-24高三上·重庆·期中）已知椭圆C :()2210a b a b+=>>的左、右焦点分别为()()121,01,0F F -,，椭圆C 上一动点A 在第二象限内，点A 关于x 轴的对称点为点B ，当AB 过焦点1F 时，直线2AF 过点30,4⎛⎫⎪⎝⎭.(1)求椭圆C 的方程；(2)点B 与焦点2F 所在直线交椭圆C 于另一点P ，直线AP 交x 轴于点T ，求TAB △面积最大时，点A 横坐标的值.【答案】(1)22143x y +=(2)13-设直线PB 的方程为1x my =+，联立得()2234690m y my ++-=，由于直线则12122269,343m y y y y m m -+=-=++直线PA 的方程为(21121y y y y x x ++=-令0y =，得(1121212y my y x y x x y y ==++即(4,0)T ；()()1114||432TABS x AB x =-⋅=-6．（23-24高三上·重庆渝中·阶段练习）已知椭圆C ：()2210a b a b +=>>的上、下顶点分别为A ，B ，左顶点为D ，ABD △(1)求椭圆C 的方程；(2)过椭圆外一点(),0M m 的直线交椭圆于P ，Q 两点，已知点P 与点P '关于x 轴对称，直线P Q '与x 轴交于点K ；若AKB ∠是钝角，求m 的取值范围．【点睛】方法点睛：求解椭圆的方程，关键是求得所以需要两个条件，如本题中，等边三角形以及等边三角形的面积，一共两个条件，用这两个条件列方程组，即可求得,a 7．（23-24高三上·重庆渝中·阶段练习）如图3所示，点1F ，A 分别为椭圆2222:1(0)x y E a b a b+=>>的左焦点和右顶点，点F 为抛物线2:16C y x =的焦点，且124OF OA OF ==（O 为坐标原点）.(1)求椭圆E 的方程；(2)过点1F 作直线l 交椭圆E 于B ，D 两点，连接AB ，AD 并延长交抛物线的准线于点M ，N ，求证：1MF N ∠为定值.8．（23-24高三上·重庆渝中·阶段练习）已知椭圆()22:10x y C a b a b +=>>的离心率为e =，且经过点()1,e .(1)求椭圆C 的方程；(2)若A ，F 分别为椭圆C 的上顶点和右焦点，直线()3:0l y kx k =->与椭圆C 交于点B ，D ，F 到直线AB ，AD 的距离分别为1d 和2d ，求证：12d d =.。
Lab2 命令解释程序的使用
实验二命令解释程序的使用一、实验目的掌握UNIX或LINUX环境下命令解释程序的使用能对编写简单的C程序，进行编译运行和调试。
二、实验内容输入LINUX相关命令后记录系统输出简单的C程序，进行编译运行和调试三、实验步骤1命令操作1)浏览目录和文件的各种属性ls –l、2)显示文件内容cat、more、3)改变文件和目录的权限chmod、4)显示当前目录pwd、5)文字统计wc、6)查看时间命令date 、time、7)帮助命令help、8)查看与删除进程命令ps, kill、9)查看在线用户who、2GNU gccGCC 是GNU提供的C 和C++ 编译器。
实际上，GCC 能够编译三种语言：C、C++ 和Object C（C 语言的一种面向对象扩展）。
利用gcc命令可同时编译并连接C 和C++ 源程序。
如果你有两个或少数几个C 源文件，也可以方便地利用GCC 编译、连接并生成可执行文件。
gcc 命令的基本用法如下：gcc [options] [filenames]gcc的主要选项：⏹-ansi 只支持ANSI 标准的C 语法。
这一选项将禁止GNU C 的某些特色，例如asm 或typeof 关键词。
⏹-c 只编译并生成目标文件。
⏹-DMACRO 以字符串“1”定义MACRO 宏。
⏹-DMACRO=DEFN 以字符串“DEFN”定义MACRO 宏。
⏹-E 只运行C 预编译器。
⏹-g 生成调试信息。
GNU 调试器可利用该信息。
⏹-IDIRECTORY 指定额外的头文件搜索路径DIRECTORY。
⏹-LDIRECTORY 指定额外的函数库搜索路径DIRECTORY。
⏹-lLIBRARY 连接时搜索指定的函数库LIBRARY。
⏹-m486 针对486 进行代码优化。
⏹-o FILE 生成指定的输出文件。
用在生成可执行文件时。
⏹-O0 不进行优化处理。
⏹-O 或-O1 优化生成代码。
⏹-O2 进一步优化。
人教版三年级秋季学期英语单词拼写专题练习题
人教版三年级秋季学期英语单词拼写专题练习题班级：_____________ 姓名：_____________【单词拼写】1. 把下面的字母重新排列组成新单词，并写出汉语意思。
（1）r e h t o m （2）a l y p（3）n i s g （4）g l u h a2. 根据中文提示写出相对应的单词。
（1）小汽车c r（2）船b at（3）风筝k te3. 根据汉语提示填空。
（1）I''d like some (水) .（2）(鱼肉) is great and I like it.（3）That''s a (蛋糕).（4）I like (米饭).（5）Do you like (牛奶)？4. 单词拼写。
（1）我________(主格) （2）再见________（3）你的________ （4）怎样________5. 将下列单词补充完整并写出汉语意思。
1. b ___ ___ k ( )2. d ___ ___ k ( )3. n ___ m ___ ( )4. b ___ y ( )5. g ___ rl ( )6. p ___ n ( )7. ch ___ ___ r ( ) 8. p ___ n ___ il ( ) 9. sc ___ ___ ___ l ( ) 10. t ___ ___ ch ___r ( ) 11. t ___ o ( ) 12. f ___ ___ r ( ) 13. o ___ e ( ) 14. f ___ ___ e ( )6. 补全单词。
1. g ____meA. aB. eC. i2. t____oA. aB. wC. i3. da____A. eB. y C .i4. j____mpA. uB. eC. i5. w____lkA. eB. aC. u7. 看图，描述画片中的动物。
I like .Look at this .Its is .Its are big, too.8. 看图写单词。
氨气喷泉虚拟实验报告(3篇)
第1篇一、实验目的1. 通过虚拟实验，了解氨气喷泉实验的原理和操作步骤。
2. 掌握氨气喷泉实验的关键因素及其对实验结果的影响。
3. 增强对氨气性质的认识，提高化学实验操作技能。
二、实验原理氨气（NH3）极易溶于水，当氨气与水接触时，氨气会迅速溶解于水中，导致烧瓶内压强迅速降低。
此时，外界大气压会将烧杯中的水压入烧瓶，形成喷泉现象。
实验过程中，氨气喷泉的形成与氨气的溶解度、实验装置的气密性等因素密切相关。
三、实验材料与仪器1. 虚拟实验软件：氨气喷泉实验虚拟平台2. 实验装置：烧瓶、滴管、烧杯、玻璃管、橡皮塞等四、实验步骤1. 打开虚拟实验软件，熟悉实验界面和操作方法。
2. 按照实验要求，设置实验参数，如氨气的初始浓度、烧瓶体积等。
3. 将烧瓶、滴管、烧杯、玻璃管、橡皮塞等实验装置连接好，确保装置气密性良好。
4. 将烧瓶倒置在烧杯中，通过滴管向烧瓶中加入适量的氨气。
5. 观察氨气喷泉的形成过程，记录喷泉现象及持续时间。
6. 分析实验结果，探讨影响氨气喷泉实验的关键因素。
五、实验结果与分析1. 实验结果显示，当氨气与水接触时，喷泉现象明显，喷泉持续时间较长。
2. 实验过程中，发现以下因素对氨气喷泉实验结果有显著影响：- 氨气的初始浓度：氨气浓度越高，喷泉现象越明显，持续时间越长。
- 烧瓶体积：烧瓶体积越小，喷泉现象越明显，持续时间越长。
- 实验装置的气密性：装置气密性越好，喷泉现象越明显，持续时间越长。
- 实验环境温度：温度越高，氨气溶解度越小，喷泉现象越明显，持续时间越长。
六、实验讨论1. 氨气喷泉实验是一种直观、有趣的化学实验，能够帮助学生更好地理解氨气的性质。
2. 通过虚拟实验，可以降低实验操作难度，提高实验安全性。
3. 在实际实验过程中，应注意以下事项：- 确保实验装置气密性良好，避免实验过程中发生泄漏。
- 控制氨气浓度，避免实验过程中氨气过量释放，影响实验效果。
- 注意实验安全，避免氨气中毒。
人教版高中英语选择性必修第四册课后习题 Unit 5 Section Ⅲ
SectionⅢUsingLanguage,AssessingYourProgress&VideoTime课后训练一起提高一、用适当的介词或副词填空1.You must be careful when thinking how to choose a career.2.It is obvious that his words have a great influencethe children.3.They are good friends,but they have nothingcommon.4. spite of the bad weather,the farmers are still working in the field.5.You’d better make goo d use of each minute to studythe sake of your future.6.In order to get a key university,the boy is working much harder than others.7.I’m writing to apply the position advertised on the website.二、用所给单词的适当形式填空1.The old man is admiring the old vase (acquire) froma merchant.2.He said that the programme (finance) by him was intended for the disabled.3.As a wise (employ),he always treats the workers ina polite manner.4.Your task is (supervise) the students from that famous school.三、完成句子1.第一次见到他,我就认为他是个诚实可靠的人。
ReducingSubstances,Urine
Lab Dept: Urine/Stool Test Name:REDUCING SUBSTANCES, URINE General InformationLab Order Codes:URS Synonyms: Urine Reducing Substance; Carbohydrate, urine; Disaccharidescreening; Monosaccharide screeningCPT Codes: 81002 – urinalysis, by dip stick or tablet, non-automated, without microscopyTest Includes:Reducing substance in urine LogisticsTest Indications: Useful for detecting any reducing substance in urine which may bepresent as a result of an inherited metabolic disorder.Lab Testing Sections: Urinalysis612-813-6280Phone Numbers:Minneapolis: Saint Paul: 651-220-6550Test Availability:Daily, 24 hours Turnaround Time:2 hours Special Instructions: Send to lab within 30 minutes of collection. SpecimenSpecimen Type:Urine Container:Urine cup Draw Volume:12 mL (Minimum: 1 mL) urine Processed Volume:Entire volume submittedCollection: A specimen collected by catheterization is optimal; however, a clean-catch or mid-stream specimen is also acceptable. Random, voidedspecimens will be accepted, but are the least desirable and are notrecommended if a urine culture is also being requested. In all cases, afirst morning specimen is most desirable.Special Processing: Transport immediately since glucose and other reducing substancesare consumed by bacteria. Refrigerate specimen if it cannot betransported or processed immediately.Patient Preparation: Collect a clean-catch urine specimen as follows:Males: Clean glans with soap and water. Rinse area with wet gauzepads. While holding foreskin retracted, begin voiding. After several mL’shave passed, collect midstream portion without stopping flow of urine.Place the cap on the cup and tighten securely. Refrigerate specimenafter collection and promptly forward to the lab.Females: Thoroughly clean urethral area with soap and water. Rinsearea with wet gauze pads. While holding labia apart, begin voiding.After several mL’s have passed, collect midstream portion withoutstopping the flow of urine. Place the cap on the cup and tightensecurely. Refrigerate specimen after collection and promptly forward tothe lab.Note: Indicate type of specimen (catheterized or void) and time ofcollection on the label.Sample Rejection: <1 mL urine submitted, contamination with feces; urine in cotton balls;specimen decomposition (e.g., pH >9.0); bacterial overgrowth;mislabeled or unlabeled specimensInterpretiveReference Range: NegativeCritical Values: N/ALimitations: Clinitest is not specific for glucose and will react with sufficientquantities of any reducing substance in the urine. These includelactose, fructose, galactose, and pentoses.Methodology: Clinitest®, Copper Reduction Tablet TestContraindications:Interfering Substances:Creatinine/Urine AcidMay cause false positive Homogentisic Acid Positive Ascorbic Acid (large amounts) False trace positive (false positive, brown color) Cephalosporins (Keflin, etc) Negative L-Dopa (large amounts) False positive Nalidixic Acid False positive Probenecid False positive x-ray dye (diatrizoates) Black color Hydrogen peroxide May inhibit positive testNote: Other drugs implicated in copper reduction are amino acids, caronamide, choral, chloroform, chloramphenicol, formaldehyde, hippuric acid, isoniazid, thiazides, oxytetracycline, p-aminosalicylic acid, penicillin, phenols, streptomycin, phenothiazine and sulfonamides. Bruist NR, British Medical Journal 2:745 Clinitest® Package Insert, Bayer Corporation, Diagnostic Division References: Strasinger SK (1989) Urinalysis and Body Fluids, 2nd ed, FA Davis Company。
dft2
DFT IIV1.0,November21,2003Dmitriy Shutin,dshutin@inw.tugraz.atSignal Processing and Speech Communication Laboratory,http://spsc.inw.tugraz.at/ Institute of Communications and Wave Propagation,Graz University of TechnologyInffeldgasse16c/IIRequired equipment:•PC with Code Composer Studio&Matlab installed•Texas Instruments DSP board•Oscilloscope Agilent54622D•Signal generator Agilent33120A•Headset•Cables1Practical partThe practical part of the work consists of several tasks that will be performed on the Texas Instruments DSP board.Detailed explanations how these tasks are to be accomplished are provided below.This part of the laboratory covers the following topics:1.Quantization effects infixed-point FFT computations.2.Fast convolution vs.direct realization of the convolution equation.3.Cyclic convolution.Experiment1Quantization effects in thefixed-point FFT computations.1.Setup the signal generator to produce a sinusoid with100mV amplitude and1kHz fre-quency.ing CCS load dft2/task1/lab2Experiment2Fast convolution vs.direct realization of the convolution equation.1.Setup the signal generator to produce the sinusoid with200mV amplitude and1kHzfrequency.2.In CCS,load the dft2/task2task2convolution.c,is contained in convolution.c.The fast clpx() functions,and a single loop.We will measure the performace of these three blocks sep-aratly,and then add the results together.To add a function to the profiler,simply right-click it and select Profile function→In Your Name Session.In the pro-filing window you will see the corresponding function being added to the list.To add the source code lines containing the loop instructions to the profiling area perform the following steps:select the Ranges tab in the profiler window,select the code lines by clicking in the gray selection margin to the left of the for()command and drag the coursor down to the end of the loop line.Drag-and-drop the highlighted area to the profile view window.Among different statistical parameters displayed in the profiling window,the most interesting for us is Incl.Average-the average number of CPU cycles needed for one execution of the profile area,including the execution time(cycle counts)of any subroutines called from within the profile area.We will use this value to measure the performance of the algorithm.5.Now,double-click Include→blocks.h andfind the#define CONVBLOCK line.Thisline defines the length of the block,read from the input buffer,and the resulting FFT length needed for the fast convolution.Set CONVBLOCK to16points.Then,double-click Include→filt.h andfind the#define FILT line.Here you will specify thefilter length.Set FILT to10points.6.Now you are ready to make some measurements.Rebuild and run the program onceagain.Wait until Count in the profiling window reaches10and stop the program.Note the Incl.Average value for this experiment.Clear the values in profiling window for the next experiment by right-clicking it and selecting Clear All.7.Measure Incl.Average for CONVBLOCK=16,32,64,128,256,512and FILT=10,50,100.Plot Incl.Average as a function of CONVBLOCK.Hint:use log2to rescale the X-and log10to rescale the Y-axes.8.Once youfinished the fast convolution measurements,performe the same for the directconvolution.In CCS,load the dft2/task2task29.Close the old profiling window by right-clicking on the panel and selectin Close from thedrop-down list.Then,create the new profiling window,following the same procedure.Double-click convolution.c,find the void eq ptr[])line, right-click it and select Profile function→In Your Name Session.10.By varying CONVBLOCK and FILT just as you did for the fast convolution,measure thecorresponding Incl.Average values.11.Plot Incl.Average as a function of CONVBLOCK for differentfilter lengths.Plot the curvesfor the direct convolution against the corresponding curves for the fast convolution.What could be inffered from these plots?Explain you answer.Experiment3Cyclic convolution vs.linear convolution1.Connect an audio source(CD-player or a sound card)to the DSP input and the headsetto its output.ing the CCS load the dft2/task task3.pjt project,rebuild the program butdo not run it yet.3.Go to the beginning of the main.cfile.The lines short filter[]={}definefilters withdifferent number of coefficients.The number offilter coefficients is declared in filt.h in the variable FILT.This number should ALWAYS。
LabSolutions 入门指南
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基于KeYmaera X的实验室2：跟随领导者说明书
Lab2:Follow the Leader15-424/15-624/15-824Logical Foundations of Cyber-Physical SystemsTA:Katherine Cordwell(***************.edu)Betabot Due Date:Friday,September27th BEFORE12:00noon with NO late days,worth20points Veribot Due Date:Thursday,October3th,11:59PM(2late days,max6per semester),worth80points Lab Resources:https:///course/lfcps19/lab2.zipUpdate!KeYmaera X is undergoing active development and we will sometimes release updates in between labs as our favorite usersfind bugs.So,here is a quick guide to updating KeYmaera X!Check if you need to update.To do so,ensure that you are connected to the Internet and then start KeYmaera X.Check the footer of any page on the KeYmaera X web interface.The footer should either say“KeYmaera X...(latest)”or else it should tell you that a new version is available(e.g.,“version4.7.2is now available...”)Whenever you notice it is time to update,complete these steps:1.Shut down KeYmaera X2.Delete your keymaerax.jar3.Download the latest keymaerax.jar from:/keymaerax.jarUsually,that is all you have to do.The release notes at:/download.html#News contains all of the changes made in each release and should also tell you about any incompatibilities.For the upgrade from KeYmaera X4.7.1to KeYmaera X4.7.2,we have(among other small things)slightly improved the UI.1Event-triggered Highway DrivingFigure1:Lead and control carIn this problem,you will design a hybrid program(HP)to model a controlled car(ctrl)following a lead car(lead)along a straight road.The requirements for the model are listed below in text;you should write a HP that appropriately models these requirements.•The lead car should keep a constant and non-negative velocity(i.e.,vel lead≥0).1•The driver of the controlled car can only choose to accelerate at rate A,where A>0,or brake at rate −B,where B>0.The choice of acceleration A should only be available to the driver when it is safe,a condition that you will have to define,while the choice to brake should always be available.•The controlled car has continuous access to the lead car’s position and velocity(i.e.,the controller you design should be event-triggered).•Assume the cars are infinitesimal points.In other words,a crash occurs only if the position of the controlled car exceeds the position of the lead car(i.e.,a crash occurs only if pos ctrl>pos lead).•Your controller must always have a transition,otherwise the safety property would be vacuously true in some(or all)cases.For example,the safety theorem[?false]safe holds vacuously for any postcondition safe because the test?false always fails.To avoid this,make sure your tests work like if-then-else statements.If you guard control decisions with a series of tests like:(?φ1;α1)∪...∪(?φn;αn)∪β,make sure the conditionsφi’s are exhaustive,i.e.,in every state,at least one of the guards is true,or that you havea fallback optionβwhich is always available.1.(Betabot).Write your answers to these three questions in lab2.txt with brief explanations:•What is a good safety condition for this system?•Under which initial conditions would the system satisfy your safety condition?For example,ifthe cars already start at pos ctrl>pos lead then they have already crashed before your controllercould do anything at all to save the day!•What would be a good criteria for claiming that your model is efficient?2.(Betabot).Fill in the missing parts of the HP in the given templatefile.Alsofill in your safetyand initial conditions from the previous part as logical formulas in the template.Save thisfile as L2Q1.kyx.While a proof is not required at the Betabot due date,you should strive to get the model and controller correct,because that will give you a better basis for the Veribot that you will be proving.3.(Veribot).Use KeYmaera X to prove that the HP you designed satisfies your safety condition andexport the proof in L2Q1.kyx.4.(Veribot).Bonus:Drivers get uncomfortable when their car gets too close to the car ahead.Updateyour safety condition to require that the cars never come within a constant distance c of each other.Update your model to satisfy this requirement and prove it safe in KeYmaera X.Submit the resulting file as L2Q1bonus.kyx.Only attempt the bonus problem after successfully proving safety without the buffer.You will only get bonus credit if your model without the buffer is proved successfully in the Veribots submission. 2Time-triggered Highway DrivingIn this problem,you will increase thefidelity of your model by changing some of the modeling assumptions. First,the lead car is now allowed to arbitrarily either accelerate at rate A or brake at rate−B.Second, when your(controlled)car chooses an acceleration,it may be stuck with that choice for some time.You will therefore need to design a time-triggered controller instead of an event-triggered one.Your model will now have a“stopwatch”which must be set to0before each continuous evolution.•The lead car may accelerate or brake arbitrarily at rate A or−B respectively.The controlled car never has access to the lead car’s acceleration.2•In the event-triggered controller,your car could only accelerate at rate A or brake at rate−B.This means that once it comes to a stop,it has no option but to accelerate.If acceleration is not safe,then the controller has no control options and the safety property would become vacuously true.To address this issue and avoid vacuously true theorems,in this problem you are additionally allowed to set your car’s acceleration to0.•The controlled car has intermittent access to the lead car’s position and velocity.The time between updates is variable,but is guaranteed to be less than time T(i.e.,your controller must be time-triggered).•The safety property should never be vacuously true(i.e.,the transition semantics of your hybrid program should not be empty).Ensure that the tests you use for guarding control decisions are exhaustive.1.(Betabot).Using the given template,design a time-triggered controller and model the system as ahybrid program.Then,write a dL formula expressing safety under suitable initial conditions for this new controller.Submit thisfile as L2Q2.kyx.2.(Veribot).Use KeYmaera X to prove that your time-triggered controller is safe.Export the proof inL2Q2.kyx.3.(Veribot).Question:Compare and contrast the Event-triggered and Time-triggered highway driving.Describe their relationship.Which was easier to prove safe?Which would be easier to implement?Why and what caused these differences?Submit your answer to this question in lab2.txt.4.(Veribot).Question:Suppose now that the lead car has faulty brakes.When it decides to brake,itcould be braking at any one of rates−B,−B2,−B4or−B8instead.Is your controller still safe?Explainwhy or why not.Submit your answer to this question in lab2.txt.3Submission ChecklistThis lab and all remaining labs in this course may be submitted in groups of two.If you are working with a partner,then you must submit afile called andrewids.txt containing both of your Andrew IDs.To make the grading infrastructure happy,please put them on a single line separated by a space,e.g.:kcordwel aplatzerMake sure you submit thisfile when working in a group.Otherwise,one of you will not get credit because there is no record of your submission.Additionally,ONLY one of you should submit on Autolab so that we do not end up grading your submissions twice.For both Betabot and Veribot submissions,remember to check the Autograder’s output on Autolab to ensure that yourfiles were submitted in the right format,parse correctly,etc.If you are working in a group, please also ensure that the Autograder correctly reports your Andrew IDs in its output,e.g.: ==>Group Andrew IDs:kcordwel,aplatzerUse the provided templates,and do not forget tofill in the section at the top.It gives us important information when grading your submission!31.Initial submission(Betabot).Submit a zipfile on Autolab containing your preliminary.kyxfilesfor each of the tasks as well as the Betabot discussionfile.This will enable us to give you feedback halfway through the assignment,so that you do not get stuck!If you want,you can include some small comments about your approach and questions you might have.While a proof is not required at the Betabot due date,you should,nevertheless,strive to get the model and controller correct,because that will give you a better basis for the Veribot that you will be proving.It will also result in a higher Betabot grade and allow us to provide more useful feedback.The Betabot zipfile should contain:•L2Q1.kyx•L2Q2.kyx•lab2.txt(with your answer to Q1.1)•andrewids.txt(only if working in pairs)2.Final submission(Veribot).Thefinal submission works the same way,except you submit.kyxfiles which contain both the model and the proof and your Veribot discussionfile.To receive full credit, proofs must be complete(i.e.,a successful“Proof Result”window appears after running the tactic you have submitted).The Autograder for this lab(and all remaining labs)will not check that your proof works auto-matically because the models and proofs are a lot more complicated.Thus,you will not see any ==>Succeeded at proving...lines in its output.The Veribot zipfile should contain:•L2Q1.kyx•L2Q2.kyx•L2Q1bonus.kyx(only for bonus credit)•lab2.txt(with your answer to Q2.3and Q2.4)•andrewids.txt(only if working in pairs)4。
基于八节点二次壳单元的等效结构应力法
基于八节点二次壳单元的等效结构应力法龚琼琼;王成;王效贵【摘要】基于八节点二次壳单元的节点力和节点力矩,导出了焊趾截面上的分布线力与分布线力矩,进而分别针对闭合焊缝和非闭合焊缝对线力和线力矩进行了单元集成.以T型焊接接头为研究对象,验证了基于八节点二次壳单元的焊趾结构应力对单元类型与网格尺寸的不敏感性,并根据已有结果验证了其有效性.对RHS管接头T 型焊缝两条焊趾的结构应力进行了计算,发现若圆弧拐角处的网格过于稀疏将引起单元中间节点的结构应力产生较大波动,该问题可以通过网格加密得以解决;利用等效结构应力与主S-N曲线,对RHS管接头的疲劳失效位置与疲劳寿命进行了预测,数值结果与实验测试数据基本吻合.【期刊名称】《浙江工业大学学报》【年(卷),期】2014(042)005【总页数】5页(P554-558)【关键词】等效结构应力法;焊接接头;结构应力;二次壳单元【作者】龚琼琼;王成;王效贵【作者单位】浙江工业大学机械工程学院,浙江杭州310014;浙江工业大学机械工程学院,浙江杭州310014;浙江工业大学机械工程学院,浙江杭州310014【正文语种】中文【中图分类】TG405焊接是常见的结构连接方式，广泛应用于车辆工程、航天航空、海洋与船舶工程以及机械工程等众多领域.焊接接头是焊接结构中最容易发生疲劳失效的部位，原因在于该部位存在较大的应力集中，并常伴有残余拉应力和各种焊接缺陷.焊接接头的疲劳强度将直接决定整个焊接结构的使用是否安全，因此对焊接接头进行疲劳强度分析十分必要.传统焊接接头疲劳评估方法各有其局限性[1-2]：名义应力法依赖于焊接接头形式和载荷类型，对于实际复杂的焊接接头会出现无法归类的问题；局部应力法解决了名义应力法的局限性，但焊缝的局部参数如焊趾半径、焊趾倾角具有随机性，无法有效应用于实际的焊接结构；热点应力法对网格尺寸和网格划分方式有严格的要求，难以准确预测焊缝处的疲劳寿命.Dong及其合作者[3-6]提出了一种预测焊接结构疲劳寿命的等效结构应力法，该方法首先将有限元计算得到的焊趾处的节点力转化为分布线力，然后基于结构力学基本原理由线力计算结构应力，进而在断裂力学框架内给出了考虑焊趾缺口、板厚尺寸和加载模式等因素影响的等效结构应力转化方程，最后基于主S-N曲线和等效结构应力即可预测焊趾疲劳寿命.等效结构应力法对网格尺寸和单元类型均不敏感，预测的疲劳寿命和失效位置与试验结果有很好的一致性，具有广阔的工程应用前景，且已被ASME VIII Division 2—2010标准采用[7-9].前述文献集中于研究四节点线性壳单元和三维实体单元，尚未见关于八节点二次壳单元的系统研究工作.笔者首先导出了八节点二次壳单元的节点力与分布线力的关系式，然后基于结构力学基本原理给出了由线力和线力矩表示的结构应力表达式.然后，利用T型焊接接头考核基于二次壳单元结构应力的有效性，并验证了单元类型与网格尺寸的不敏感性.最后，对RHS管接头的疲劳失效位置与疲劳寿命进行了预测，数值结果与实验测试数据基本吻合.1 基于二次壳单元的等效结构应力法基于结构力学基本理论，结构应力σs由膜应力σm和弯曲应力σb两部分组成[3].对于壳单元，基于图1所示的局部坐标系x′y′z′，焊趾截面A-A上的结构应力可表示为(1)式中：δ为焊趾截面A-A与参考面B-B的距离；fx′和fz′为参考面B-B上的分布线力；my′为参考面B-B上的分布线力矩;t为壳单元的厚度.当参考面B-B与焊趾截面A-A重合时，式(1)可简化为(2)图1 焊趾壳单元的结构应力计算Fig.1 Structural stress of a shell element adjacent to a weld toe结构应力集中系数Ks为Ks=σs/σn(3)式中σn为垂直于A-A截面的名义正应力.采用八节点二次壳单元分析焊接接头，某代表性焊趾壳单元如图2所示.以C为原点，AB边为自然坐标轴，则点A，C，B的形函数可由自然坐标ξ表示为(4)图2 线力分布示意图Fig.2 Distribution of line force焊趾截面AB上任意点的局部y′坐标，可表示为(5)式中：，，分别为局部坐标系o′x′y′下单元节点A，C，B的局部y′坐标值.焊趾截面上的分布线力和分布线力矩，可表示为如下统一形式f(ξ)=NAfA+NCfC+NBfB(6)式中：fA，fC，fB分别为节点A，C，B上的线力或线力矩.计算结构应力所需的分布线力和分布线力矩，可基于功等效原理由节点力和节点力矩导出，即(7)式中：FA，FC，FB分别为局部坐标系o′x′y′下节点A，C，B上的单元节点力或节点力矩.将式(4)代入式(7)，化简后得(8)式中lAB为焊趾单元沿焊缝方向的长度.式(8)与ASME VIII Division 2-2010标准[10]中给出的单元节点力与线力的关系式具有相同的形式.一般情况下，连续焊缝的焊趾可划分为n个二次壳单元，如图3所示.对于非闭合焊缝，有2n+1个焊趾节点.将单元节点力或节点力矩集成，可得(9)对于闭合焊缝，则有2n个焊趾节点.将单元节点力或节点力矩集成，可得(10)图3 焊趾二次壳单元的剖分示意图Fig.3 Second-order shell element of a weld toe基于壳单元有限元分析结果，计算结构应力的步骤：通过有限元计算得到整体坐标系下焊趾处的节点力，经过坐标转换得到局部坐标系下的节点力，然后通过式(9)或式(10)求出分布线力和分布线力矩，代入式(2)后求出结构应力.Hiroko和Dong[4]以结构应力为控制参数计算应力强度因子，在考虑焊趾缺口、板厚尺寸和加载模式等影响因素的基础上，基于断裂力学分析确定与疲劳寿命直接相关的应力参数，最终导出的等效结构应力为(11)式中：Δσs表示结构应力范围；ΔSs表示等效结构应力范围；t为板厚；m为Paris疲劳裂纹速率公式(ΔK)n中的指数n(取值为3.6)；I(r)=0.294r2+0.846r+24.815为载荷弯曲比r=σb/(σm+σb)的无量纲函数.对近50年来的上千个焊接接头疲劳试验结果进行了处理，并由线性回归统计分析确定出用于疲劳寿命评估的主S-N曲线.在存活率为50%时，主S-N曲线可表示为lgN=12.185 448-3.055 953lgΔSs(12)2 结构应力的计算2.1 T型接头图4为T型焊接接头受力分析模型.水平放置母板的厚度为t，长度为40t，宽度为5t.竖直放置附板的厚度为t，高度为7t，宽度为5t.焊缝倾角为45°，焊脚长度均为t.水平母板的左端固定，右端面施加均布拉力，并且限制右端面附近区域沿板厚方向的线位移；竖直附板的上端面固定.母板与附板的弹性模量均为210 GPa，泊松比为0.3.图4 T型焊接接头的受力分析模型Fig.4 Analytical model of T-weld joint基于壳单元的T型焊接接头的有限元建模过程如图5所示[7].对于非焊缝区，取母板与附板的中面建立壳单元分析模型，壳单元厚度均为t.对于焊缝区，过焊趾点A作竖直垂线与母板中面相交于M，过焊趾点D作水平垂线与附板中面相交于点N，连线MN表示焊缝的横截面.过点A作线段MN的垂线AC，线段AC的长度即为焊缝壳单元的厚度，当焊缝倾角为45°时厚度为t/.图5 T型焊接接头的壳单元建模示意图Fig.5 Modeling of T-weld joint by shell element为了考察单元类型对焊趾处结构应力集中系数的影响，采用了线性壳单元(S4R)和二次壳单元(S8R)；为了考虑单元大小对焊趾处结构应力集中系数的影响，针对两种壳单元分别划分了边长为0.25t×0.25t，1.00t×1.00t，1.67t×2.06t的四边形焊趾单元网格.对于S8R有限元模型，基于从结果ODB文件中提取的焊趾单元节点力和节点力矩计算结构应力；对于S4R有限元模型，则由文献[3]中的方法求解结构应力.然后，把结构应力与名义应力代入式(3)，即可求出T型焊接接头的焊趾结构应力集中系数，结果如图6所示.显然，无论是S4R壳单元还是S8R壳单元，三种不同尺寸的有限元网格得到的结构应力集中系数基本一致，不但说明结构应力对单元类型和网格尺寸都不敏感，而且验证了基于二次壳单元的结构应力计算公式的有效性.图6 T型接头焊趾的结构应力集中系数Fig.6 Structural stress concentration factor of T-weld joint toe2.2 方形空心截面管接头SAE FD&E委员会于2003年公布了方形空心截面(RHS)管焊接接头模型[4].RHS接头由101.6 mm×101.6 mm和50.8 mm×152 mm方形截面空心管焊接而成，管长分别为600 mm和364 mm，空心管的壁厚t为7.9 mm.焊缝为T型单边焊，焊缝倾角为45°，焊脚长度为t.材料的弹性模量为210 GPa，泊松比为0.3.基于T型焊接接头的壳单元建模方法(图5)，建立如图7所示的RHS接头的有限元分析模型.把正方形截面管左端通过MPC Beam命令刚性耦合到截面的中心点，在中心点正上方317.5 mm处定义一个参考点，并将中心点与参考点刚性耦合，RHS接头的另外两端固定，在参考点上沿x方向施加17.8 kN的对称交变载荷.T 型焊接接头的分析已经验证了焊趾结构应力的网格不敏感性，因此仅用大小为t的S8R壳单元对RHS接头进行网格划分.图7 RHS管接头的有限元分析模型Fig.7 Finite element model of RHS joint由于是对称循环加载和线弹性分析，Fx=17.8 kN和Fx=-17.8 kN作用下同一焊趾截面的结构应力绝对值相等.当Fx=17.8 kN时，提取ODB结果中焊趾单元的节点力和节点力矩，由其求出的结构应力分布如图8(a)所示，虚线所示焊趾位于101.6 mm×101.6 mm截面上(记为焊趾A)，实线所示焊趾位于50.8 mm×152.4 mm截面上(记为焊趾B).对比沿焊趾A和焊趾B的结构应力分布可见：结构应力最大值出现在焊趾B的圆弧拐角处.拐角处沿焊趾A的结构应力分布的局部放大图见8(b)，三角形符号代表划分5 个壳单元时的结果，而实线对应于90个壳单元的情况.由于焊趾在圆弧拐角处的曲率较大，相邻壳单元法向的夹角也相应较大，导致中间节点处的结构应力相对于角节点出现明显波动，显然该问题可通过在该处采用较细的网格划分得以解决.图8 焊趾的结构应力分布Fig.8 Structural stress distributions of weld toes结构应力范围为Fx=17.8 kN时求得结构应力的两倍，即Δσs=2σs.把Δσs代入式(11)，可求出等效结构应力范围ΔSs.把ΔSs代入式(12)，则可得到存活率为50%时的焊趾疲劳寿命.由于Δσs和ΔSs满足线性关系，显然由ΔSs预测的危险截面与Δσs的预测结果完全一致，也就是说疲劳失效位置为焊趾B的圆弧拐角处，疲劳寿命为8.2×104个加载循环.RHS管接头的疲劳寿命试验共测试了12个试样，疲劳寿命的最大值、最小值和平均值分别为2.0×105，3.0×104，7.5×104，疲劳失效位置都发生在图8所示的焊趾B的圆弧拐角处[4].由上述分析可知：等效结构应力法预测的疲劳失效位置与试验结果完全一致，存活率为50%时的疲劳寿命预测值介于试验结果的最大值与最小值之间，且与平均值非常接近.3 结论首先导出了基于八节点二次壳单元的分布线力与分布线力矩，然后基于结构力学基本理论得到了焊趾截面上的结构应力表达式.通过T型焊接接头的分析，验证了基于八节点二次壳单元的结构应力计算公式的有效性，而且发现单元类型与网格尺寸对结构应力影响极小.对RHS管接头的研究表明：基于八节点二次壳单元的等效结构应力法可以准确地预测焊趾的疲劳失效位置与疲劳寿命.参考文献：[1] 袁熙，李舜酩．疲劳寿命预测方法的研究与现状[J]．航空制造技术，2005(12)：80-84．[2] 周张义，李芇，黄运华．基于热点应力的焊缝疲劳强度评定研究[J]．内燃机车，2008(7)：1-10．[3] DONG P． A structural stress definition and numerical implementation for fatigue analysis of welded joints[J]．International Journal of Fatigue，2001，26：865-876．[4] HIROKO K， DONG P． Equilibrium-equivalent structural stress approach to fatigue analysis of a rectangular hollow sectionjoint[J]．International Journal of Fatigue，2005，27：85-94．[5] DONG P， HONG J K． The master S-N curve approach to fatigue evaluation of offshore and marine structures[C]．Vancouver：The American Society of Mechanical Engineers，2004：1-9．[6] DONG P， HONG J K， CAO Z． Stresses and stress intensities at notches：“anomalous crack growth” revisited[J]．International Journalof Fatigue，2003，25(9/10/11)：811-825．[7] DONG P， HONG J K， DE-JESUS A M P． Analysis of recent fatigue data using the structural stress procedure in ASME Div 2Rewrite[J]．Journal of Pressure Vessel Technology，2007，129：355-362．[8] ASME Boiler and Pressure Vessel Committee on Pressure Vessels．ASME VIII division 2—2010 ASME boiler and pressure vesselcode[S]．New York：The American Society of Mechanical Engineers，2010．[9] 武奇，邱慧清，郑洋．基于壳单元的焊接接头的结构应力求解[J]．焊接学报，2010，31(7)：22-26．。