有关工程试验的论文范文初中英语作文

有关工程试验的论文范文初中英语作文

One day， I saw the book on such a funny thing: If under certain conditions， plastic bottles will be their "water"， blowing I think this is very interesting experiment， they intend to do their own time， to figure out why the bottle will "drink" bubble In accordance with the book on the tips of my better prepare the following materials: a few of the flexible straw， a platter， a glass of tap water， a cup of hot water， a cup of ice water， adhesive tape， rubber cement， ink， a large plastic After everything is ready， I start to do the The first step， I used rubber cement to seal the bottle， and then inserted into a The second step， I put adhesive tape with another straw straw with the first linking the root， so that it can tap into the The third step is to look for the experimental situation will be， I put the ink back into the water dyed The fourth step， I put the bottle into a large plate and then bending straw， insert cup Only four more than the pre-preparation step， the next step in the experimental situation to First， I carefully poured with hot water bottle in the plastic wall， did not start one movement， so I continue to上浇water bottle while watching the glass movement， and pretty soon， actually begins from the straw in the bubble! Next on the bottle， "drink" I have been part of the refrigerator ice out of the ice water， poured瓶壁to go， seems to start one I continue to be patient to repeat the action just as he eyes a Hard work pays off， ah， drops from a straw in a true blue ink， the bottle， "drink" again! My experiment a success! Included in this experiment is a scientific reason热胀冷缩has the characteristics of When the hot irrigated to the outside wall of plastic bottles， the bottle thermal expansion of the air， went to the glass， which increases stress， put a cup of water pressure to get out bubbles on a straw; and when the ice water outside the wall of water into the bottle， the bottle the air was cooling， the pressure inside the small， water will run into the I also know a lot about life热胀冷缩the situation， really funny， love the students use their brains， let us explore together!

With the rapid development of China's market economy and the further development of the trend of economic globalization， the construction industry can occupy a favorable competitive position in the fierce market competition is becoming increasingly The construction quality management and control of the level of direct relationship to the industry's competitive position can be effectively promoted， visible， scientific and rational management system for the construction of sustainable development goals with a unique This paper attempts to study the quality management and control of the construction industry， and on how to improve the overall management system of the construction industry to make a scientific

What kind of interesting work are other Civil Engineers doing right now?I'm working on an excavation for a building that is part of a Physics E We blasted our way 80ft deep into The hole is 300ft by 130ft or there We are currently installing Lots of untensioned and tensioned rock I work for the contractor who is doing the Its very interesting project， but also very The Engineering firm who designed the project is from Chicago， and they didn't send anyone to the site before they designed it， and they did a really piss poor job of The geology was nothing like they thought it would be (big surprise)， but thats what happens when local engineers are not involved I They had 20 bore holes drilled， for a 3 mile road and the building Then they changed the site layout so the final design was not even in one of the bore They missed by 300 We built them a 3 mile road to the site， and it was designed like a Chicago street， and not 3 miles of road floated over Even though there is a septic system for the building site， there design included a sanitary sewer， with concrete manholes and the It was fun because there is no sanitary sewer on ether side of the Lazy engineering is a very very terrible thing to have to deal

有关工程试验的论文范文初中英语

I’m looking forward to the coming of my winter In order to have a good time in the vacation， I have made a plan for At first， my mother must ask me to do If I don’t follow her words， I wouldn’t have peace in the following days until I finish my So the first thing I will do in the winter holiday is to finish my And then I will take full use of my time to go out play with my friends， because I will have to help my mother to prepare for the Spring Festival when it’s in the Three days before Spring Festival， I will go to my grandmother’s home for a visit with my After the Spring Festival I am going to travel with my As for where to go， I don’t have any plan Maybe we will go to Harbin to the Being the southern local person， I have never seen snow and eager to see it After the trip， I think I have to go back to This is my plan for the coming winter What’s yours?具体的范文模板链接：-x2_2CflQcQ1AO88Tg?pwd=jn88 提取码: jn88

众所周知，词语搭配逐渐开始在语言学及应用语言学领域占据一个比较重要的地位。如今搭配成为语料库语言学领域较为繁荣的方而。很多研究人员在这一领域有兴趣，语料库现在依赖于现代计算机技术，它可以运行数千万字的文本。现在，基于语料库的研究都集中在对数量足够大的自然语言词汇重复模式方面的深入探讨。本文将基于语料库讨论商务英语中关键词汇的词语搭配。论文共分为五个部分。在第一部分中，将把本论文的研究背景详细阐述，同时也将明确指出本论文的目的和意义。同时也会对论文的组织结构进行概述。‘文献回顾中，总结了语料库和语料库语言学相关的文献，提供了搭配的相关信息以及它的具体定义和关键词等。这是我们研究的基础数据收集程序。通过计算列出数据，同时处理结果，并以科学和系统的方式加以分析。词表将被计算出来后，根据结果和比较，同时确定关键字。对于选择出来的四个关键词将被讨论，集中在词语搭配方面。最后，对商务英语语料库中的关键词的搭配研究会作出一个总结，同时并为进一步研究该建议。It is well-known that collocations are gradually beginning to occupy a relatively important place in the field of linguistics and applied Nowadays collocations become the flouring area of corpus A lot of researchers are interested in this Corpora now relies on the modern computer technology， which can make the running texts of tens and thousands millions words Recently， corpus-based research has focused on the importance of recurring patterns of lexis by looking at cUbktbTA蛛bUCz%^Lh

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【篇一】 Two days ago， a heavy snow And now， the snow stopped and it’s time for This morning， I go to outside door and make snowman with my We prepare some tools and then we We did it many times before， so it’s We pull snow together and shape Last， we make a face for it， eyes， nose， ears and It’s very funny and we are 前两天，一场大雪来了。现在，雪停了，是玩的时候了它。今天早上，我走出门外，和我的朋友一起堆雪人。我们准备了一些工具，然后我们就开始了。我们以前做过很多次了，所以很容易。我们把雪弄在一起和做成形状。最后，我们做出了一个脸，眼睛，鼻子，耳朵和嘴。这是非常有趣的，我们是快乐的。更多优秀英语作文尽在：【分享君英语作文网】，百度直接输入就可找到！！！

有关工程试验的论文范文初中生英语

转帖]关于防雷接地问题的探讨中国科学院电工研究所 马宏达　　摘 要：本文讨论了配电网接地制式与建筑物电气设备的电磁兼容问题；接地网的电阻值及接地网的结构在防雷中的作用；外部防雷和内部防雷两个子系统的放电过程；指出了接地技术中的宣传误导。　　关键词：建筑物防雷雷电电磁脉冲防护 LEMP 防雷接地 电子(逻辑)接地　　1、供电系统接地方式与室内电磁兼容的关系　　配电网接地系统的制式关系到电网的运行安全和建筑物的供电安全[1、2]。西方国家特别重视供电质量，对电源频率和电压质量都有严格的要求；他们对智能建筑物内的电磁兼容问题也很重视，重要建筑物广泛采用屏蔽电缆的供电方式。现在我国智能建筑物的设计已经注意到这一点。现在大城市中的配电变压器已经采用小电阻接地方式，电源线已经广泛采用TN-S和TN-C-S系统，俗称三相五线制；在室内注意按综合布线的规范敷设电气线路。　　如果把三相电源系统的火线比做上水管道，则N线有如下水管道，它输送的电流有闪光灯和闸流管等电气设备产生的杂波，还有电源系统故障时产生的过电流等。这样电源自成闭合系统，PE线只是起到接地固定电位的作用，平时并无电流流过。如果把N线与PE线合并，这些杂波电流和过电流就会在地线中产生浮动电压，使电子设备遭受损坏和不能正常工作。所以，N线必须绝缘敷设，PE线必须独立敷设，这正是三相五线制供电系统建立的意义。检查N线与PE线是否绝缘良好的办法是测量PE线内的电流，正常情况下PE线内不应该有电流。我们在故宫防雷工程中测量某宫殿的防雷接地时，发现接地电阻表摇摆不定，从而发现N线与PE线有搭接的故障。PE线的作用就是，平时作为电子地(逻辑接地)和设备的保安接地，在雷击时兼做防雷接地。　　三相四线制的PEN线也有保安接地的作用，但是它不能做电子接地，因为它平时将有杂散电流通过，不能保证电子设备的稳定运行。例如：1993年在北京西便门立交桥东北侧曾有一片平房(商店)发生火灾，原因是有一辆高架货车把电线挂断，发生单相电弧接地事故，而该商店的电气开关未能立即开断，这片平房顶棚内的电线因过电流而熔化并引发火灾。我国农村地区要特别警惕这种架空线配电建筑物的安全问题。IEC防雷标准和我国现行建筑物防雷标准选用SPD的U1ma时，只考虑220／380V电网中性点接地方式，而没有考虑其上一级10kV电网的中性点的接地制式。以至常选用440V、470V的U1ma，这样做是不妥当的。我国多数配电网是采用中性点绝缘或经消弧线圈接地的方式，这些电网发生单相接地故障可能运行几个小时，此时相电压变为线电压，使SPD烧毁。我国水利电力部和机械工业部根据本国情况考虑荷电率制定的避雷器国家标准GBll02-2000，对220V级MOV规定U1ma=600V，相问MOV的U1ma =1200V。这样做既能减少SPD烧毁，又能有效地防雷才是合理的。　　建筑物雷害事故统计表明：80～90％的事故是由电气线路引入的，直接雷击的事故并不多。在山区和农村中建筑物的供电用架空线直接引入不是好办法；建议参考文献[3]，改用铁管穿线屏蔽敷设(见图1)：进线杆前连接一段长度大干15m的架空伸长地线兼做避雷线(见图2)，此段线路的作用是增加屏蔽铁管前主线路的电感，使1#SPD(氧化锌避雷器)便于启动，在进线杆前再连接2#SPD，进线杆的铁脚和铁管的上端联合接地。　　图1 建筑物架空线引入时的防雷措施　　图2 在电杆上做架空伸长地线及避雷线的示意图　　2、取决接地电阻大小的要素　　经验表明，接地体的电阻主要决定于它与地的接触电阻。我们在打接地棒后立即测量其接地电阻值时测得某一数值；只要抓住接地棒的上端摇一摇，再测时其接地电阻值将增加。这是因为接地棒与其附近的土壤脱离的缘故。在钻孔埋接地体的时候，灌水和填土后其接地电阻值将有一变化时期。开始其接地电阻值小，后来变大(土壤与接地体脱离)，长时期后又变小(因土壤压实)。用碳棒和碳质模块做接地体时其接地电阻值并不如计算那样理想，但是如果在它们的周围涂以LRCP降阻剂则可较理想地达到预期的接地电阻值。这些都说明接地体与地的接触电阻是决定接地电阻的重要因素。　　接地网的接地电阻与接地网的面积S的开方成反比，在接地网内再补充打接地棒和接地桩，对于降低接地电阻的作用不大。因为接地网的周边接地棒对其中心有屏蔽作用。而且，电子地的稳定不是单*降低接地电阻值所能解决的，重要的是要想法降低接地网的电感和使接地联线中没有电流(此时，接地线的电感电压降占重要地位)。解决的办法是用星形接法连接仪器设备；如果还有困难，接地联线用绝缘线，把接地线用铁管套起来，屏蔽铁管的两端与其附近PE线相连。其道理是使接地线的电压不能耦合到电子回路中去。内部防雷的系统中要避免采用开关型和间隙型过电压保护器，这些间隙在放电时电压急剧截断将引发电路中分布电容和电感的震荡过程，使电子设备遭到损坏。　　3、接地网的结构及其防雷性能的分析　　在雷击建筑物时，在钢筋混凝土的结构钢筋内将有震荡电流产生。这些震荡电流将感应室内电气线路产生二次电流。这些二次电流将造成电气设备的损坏。采用SPD限制作用在电气设备上的电压是内部防雷的任务，接地网的等电位连接措施使这二次电流回路中的电流不会很大，用8/20μs电流波形检验。　　防雷导体流经的雷电流是一次电流，它是排出建筑物的外部放电过程。内部防雷子系统与外部防雷子系统之间虽有电路上的联系，但是各自自成系统，要分别计算不能够混淆，否则将发生严重的计算错误。采用电缆段进线和穿铁管屏蔽进线的防雷方法，是防止雷电流经SPD向电源系统反灌的重要措施。　　建筑物的基础接地和其周围的埋地接地网是安全散流和整体电位浮动的保证条件。如果防雷接地体是独立的或是室外的一条接地带，则不能保证建筑物的屏蔽条件。对此北京电力科学院的科学家曾经做过屏蔽理论推算和实验检验[4、5]。文[5]探讨了高电压试验室的接地，它的道理可以运用在建筑物防雷中，它说明了减少接地网电感的道理和穿线铁管是屏蔽的有效措施。　　笔者在某通讯站测量其天线阵地和机房的接地电阻，两座机房接地用的是室外接地带，天线阵地用的是接地网。测量结果发现：机房和天线接地网的联合接地电阻值比单独的天线接地网的接地电阻值还要大，大出的部分是接地带所形成的连线电阻。所以机房的接地一定要做成围绕机房的周圈式的接地网，不能用机房外的接地带来代替。　　埋地接地网CBN与设备连接网EBN的作用和要求不同，参看图3。　　图3 公用连接网CBN与设备连接网EBN的原理示意图　　笔者个人的看法是：　　(1)公用连接网CBN的作用是安全散流和保证等电位。它必须采用周圈式接地带，其外围可敷设一些接地棒。埋地是散流的重要条件，在土壤电阻率比较低的地方打接地棒对降低接地电阻有效；但是在土壤电阻率比较高、没有地下水的山地，打接地棒很难，对降低接地电阻的作用也不明显。　　(2)埋地接地网是保证建筑物在雷击时整体地电位浮动(屏蔽作用)的必要条件，如果接地体或接地带敷设在建筑物之外，它不能起到屏蔽的作用。接地网比独立接地体和接地带有更大的电容，在雷电先导形成和向地面发展的过程中，接地网上将感应产生大量的感应电荷，这些电荷与雷电先导电荷的符号相反，在主放电过程中它们复合，在接地导体中放出能量(变为热能)，这样产生的雷击电压将比独立避雷针小，有利于整体的防雷效果。　　(3)设备连接网EBN的作用是保证等电位的条件，它本身要有一定的低电感的要求，这与安装的电子设备情况有关，也与设备接地线的连接方法(S星形或M网形)有关。　　(4)EBN接地连线的电感是造成干扰和危险地电位浮动的根源。所以使电子地稳定的关键条件是使接地连线中的电流为零。要达到这一点就是要从地网CBN的中心部位在电梯井中引上接地线，并与各层楼板的等电位连接板和PE线相连接，要求严格的房间应敷设单独的等电位接地板(如用铁板拉网)。　　(5)建筑物内的等电位状态也不像静电学等电位那样理想，大楼内还有杂散电流在钢筋中分布。在大楼内各种电气线路都要受到杂散电流的电磁耦合作用。杂散电流在接地网上的电压降(主要是电感分量)就是接地系统不同点的暂态电位差。这个电位差很难直接测量。实际上，更有实际意义的是所谓的开环电压和闭环电流如图4所示。　　图4 开环电压和闭环电流示意图　　图4中，Uab为接地网A、B两点间的电位差。电子仪器外壳对EBN的地、或仪器外壳对电源的电位差即是开环电压。假如仪器的外壳在控制室内接地，则仪器电缆外皮(屏蔽层)中流过的电流称为闭环电流。它是决定电子仪器受到共模干扰大小的一个量。开环电压决定了仪器受到的过电压的大小，而闭环电流则决定了共模干扰的大小。　　(6)人们只有明确了内部防雷和外部防雷两个子系统中电磁震荡的过程及其特性才能提出有效的抗干扰的办法，原则上是合理地运用隔离与连接的措施，消除不希望的电磁耦合，其中用铁管穿线屏蔽电气线路外，把冗余的电气线路的两端全部短路并接地，这两项措施经常是很重要的。　　4、接地电阻测量的困惑　　现在城市中建筑物的密度很大，地下管网很多，钢筋混凝土建筑物的接地网接地电阻的测量实际上很难测准。因为接地电阻测量的拉线距离必须大于接地网直径的4～5倍，这一点很难做到。实际上接地电阻的测量是在接地网的网眼中进行的，这与接地电阻的定义是不一致的，其测量的结果是不可信的，(其总的趋势是测量结果偏小，有时甚至成为负值)。现在广泛采用的高频接地电阻测量仪和脉冲接地电阻测量仪所测接地电阻与工频接地电阻不同，它没有标准定义的接地电阻的意义，但是它对接地线断线的检测有参考意义，笔者曾经专门讨论过这个问题[6]　　5、防止华而不实的炒作行为　　(1)我不赞成用铜材做接地体，接地体的尺寸是由机械强度和腐蚀因素决定的，不是由热稳定条件决定的。铜是一种战略物资，我们不应把它大量地埋在地下。西方国家现在都已改用钢管做接地体了，我们却宣传用铜作接地体。这无非要提高防雷装置的造价，增加用户的成本，给施工方带来利益。　　(2)不要听信某些防雷公司的宣传，在接地网的当中打接地桩，那样做是无效的。电子地的稳定问题不仅在于接地电阻值的大小，关键在于要使接地线上没有电流。类似“打接地桩”的宣传是一种误导。　　(3)还要注意接地措施导致的环境污染问题和对附近钢铁构筑物的腐蚀效应问题。

你是哪个省的啊 看看如果可以的话 可以给你一份全面的

Today I learnt more about project hope in class and I was deeply I found that there were many students from poor areas who had dropped out of school because they had difficulty in their families，and Liu sanzi is just one of I really wanted to help him return to school ，so that he could get proper education and study happily without worrying about his family ，like I talked to my parents about this，and they also agreed with my idea to help We decided to try our best to raise money for And I had also written a letter to him，expressing my feelings and encouraging We decided to sent the money and my letter to him right What a fantastic day!I hope he will be able to go to school with our help as soon as 今天我在课堂上了解到很多的有关希望工程的事，我被深深地感动我发现有很多贫困地区的学生辍学，因为他们有他们的家庭困难，刘三资就是一个真正的I希望能帮助他重返校园，使他能得到适当的教育和研究，不担心他的家人和我们一样，愉快地。我跟我的父母，对此，他们也同意我的想法，以帮助We决定要尽力提高And钱，我也给他写了一信，表达我的感情和鼓励We决定发送的钱，我给他的信What一个梦幻般的一天！，我希望他能够尽快到学校去与我们的帮助。

有关工程试验的论文范文初中英语版

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捏鸡蛋　　不知大家有没有尝试过捏鸡蛋，可能有的人会觉得这没有意义，因为谁都知道鸡蛋薄薄的壳，一碰就碎，有多少人知道这其中鲜为人知的奥秘。　　那时我在家上网查资料，看到了一个有趣的故事，上面说：“一个大力士能徒手打碎一块砖，可是有个人叫他把鸡蛋捏破，大力士拿起鸡蛋使劲捏了半天，却怎么也捏不破。”我看了半信半疑，决定找个机会试验一下。　　这天，妈妈答应中午给我做我最爱吃又最有营养的番茄炒蛋，想到那甜甜的番茄，滑滑的鸡蛋，我便口水直流。到了中午，我主动请缨要去帮妈妈，妈妈答应了，让我去打两个鸡蛋。我先从冰箱里拿了两个鸡蛋，然后拿了一个大碗，看着鸡蛋，我心想:试验的好机会来了。第一个鸡蛋，我按平常的方法打到碗里去，一敲就破的鸡蛋让我对那个故事产生了更多怀疑。第二个鸡蛋，为了防止捏碎鸡蛋时蛋黄洒一地，我刻意把鸡蛋对准碗中心这时，我的心“砰砰”直跳，手心都冒出了汗。鸡蛋破碎那一幕仿佛出现在我的眼前，我双眼一闭，然后等待鸡蛋破裂的声音响起。但令我吃惊的是，当我睁开眼睛，鸡蛋竟然没破。第一回合的“失利”没有让我气馁，我准备进行第二回合第二回合，我吸取了“教训”，我这次用两只手把鸡蛋紧紧握在手里，然后咬紧牙关，瞪大眼睛，使出全身力量去捏鸡蛋尽管我使出了九牛二虎之力，可在我认为这回鸡蛋“必死无疑”的时候，它却安然无恙地在我手中这让我又懊恼又惊奇，我只好去问在旁边的妈妈　　妈妈听了我的话后，语重心长的对我说:“孩子，这其实是一个科学原理。鸡蛋壳虽然很薄，但它是一个椭圆形，当你去捏它时，它就会把你使出的力量全部均匀的分布在鸡蛋各个地方，所以它能承受很大的力量，一些建筑物就是运用这个原理建成的。”听了妈妈的话，我恍然大悟。　　其实这个世界真的非常奇妙，我相信只要大家爱发现，爱观察，爱劳动，就能与科学邂逅。当今社会可以说已经离不开科学了，相信我们明亮的眼睛能发现许多奇妙的事物。

常见的如消息、通讯、特写、报告文学、游记、日记、参观记、回忆录，以及一部分书信等

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有关工程试验的论文范文大全初中英语

初中英语作文范文 How to make friends It’s hard to make friends if you stay alone all the It’s easier to make friends when you have similar Don’r be afraid to show people what you are really good Talk about the things you like and do Look at people in the eyes when you talk to Be a good Let people talk about themselves before talking about Be friendly to a lot of Try to help your friends when they are in trouble because a friend in need is a friend That way you’ll have a bigger group to choose from and have more chances to make 初中英语作文范文My view on televisionTelevision has come into our life for many We can’t live happily without Jt can give us the latest information and It can open up our eyes and enlarge our We can get happiness from the plays on We’ll be boring all day if there is no Television programs are After a whole day’s hard worlk we can sit before the television and drink a cup of How wonderful it is!Television is also bad for people’s It’s bad for you to watch TV too long， especially bad for your It is true that watching TV can influence our However， it depends on what we 初中英语作文范文My view on school uniformAt our school ， we have to wear uniforms every The problem is that all my classmates think the uniforms are We think young people should look smart and so we would like to wear our own Our teachers believe that if we did We would concentrate more on our clothes than our We We should feel more comfortable and thate is good for If we can’t do that， we should be allowed to design our own We also think everyone should be different from That would be a good way to keep both teachers and students 初中英语作文范文My opinions on volunteeringWe are middle school students and we are busy with our So some people think we should concentrate more on our If we volunteer to help others， it’s a waste of But I think volunteering is I not only feel good about helping others but also get to spend time doing what I love to And from volunteering I have learned many things that I have never learned in So if I have an oppoutunity， I’d like to visit old people’s home to clean up for I’d also like to help sick kids in I love kids and I plan to put my love to good use by working in In a word， I’d like to help people who need If everyone helps out a bit， the world will be more 初中英语作文范文Small kinds Human beings are advanced animals in the Some animals are very For example ， if you are kind to a dog ， it will It will tail to So if you are kind to others， they will also be kind to You have lots of chances to give your small kindness if you see a disabled person working in the You can help him to cross the If you meet a stranger， you can show him the If he or she asks you questions， you should be kind to answer That is you give small kindness to Maybe it seems to you a piece of cake， but it is very important to people in If you do this， the others will do it to Be kind to others， and they will be kind to 初中英语作文范文My opinion on InternetHello， everyone! As you know， many students like to work on the I Of course， it can bring us many good We can learn more knowledge outside our books， practice our spoken English with someone else and look up some useful At the same time， it can bring us some bad things as Some students have made too many friends， seen some bad information that is not good for us and spent too much time on We should know what to do and what not to That’s my Thank you for listening! 初中英语作文范文Internet shopping Internet shopping is a new way of It offers a lot of The most important one is You can shop whenever you like because the online shops are open 24 hours a And you don’t have to queue with And it is often cheaper to buy goods through the Internet and it is also easy to find what you are looking There are some disadvantages， You can not see the products or check their Besides you can not enjoy walking around the shops and talking with your 8Should We Keep the Students in School All the Time?Hello，Wether we should keep the students in school all the time is a hot topic among educationists，teachers and Some teachers think that in order to let the students have more time for their lessons and develop their good behaviors，the schools are supposed to be sealed off，so the students can't go out and have to stay at But some teachers and the students hold a different They believe that would cause some The students will have no time for relax，doing something they like，and that would do harm to their health，as well as their To my mind，I don't think it's a good way to keep the students in school all day Students，like every one of us，need time and places for playing。Please do not keep the students in school all the time，for our students and education，That's all，thank 9Friendship As the old saying goes(正如老话所言)， a life without a friend is a life without a （生活没有了朋友就像没有了太阳）But some people may say，we teenagers may let our friends talk us into doing bad So as to pleased their so called "friend"This is because we teenagers are lack of the self-control I like staying with Because friends are always give me a helping hand when in Of course， I will treasure（珍惜） my friendship no matter 10In modern society， people tend to be self- Yet in my opinion， helping others should still be First of all， when you give a hand to a person in need， not only will he be free from the trouble but you will also feel good helping Apart from that， helping others facilitates an efficient After the threshold of the new century of information explosion， it's not enough to perform on one's own any Teamgeist and cooperation are gaining Thus from the above mentioned two reasons， i hold the opinion that helping others benefit the 还有四篇发不上来，要的话留邮箱吧

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回答 需要什么类型的？ 自我介绍的英语作文一My name is Linda SMy first name is Linda，My last name is SI am fourteen years I like playing sports，such as football，ping-I have two footballs and many ping-pong My favorite subject is PE，because I can play happily with my friends，I think it is very I want to be a runner，like Liu XMy favortie animal is panda，she is kind of shy and 提问 Some rules I should obey on my way to school 英语作文怎么写 回答 The roods in our city are usually very busy There are a lot of cars， trucks， vans and buses on the So， we must obey the traffic As a driver， you mustn’t drive too fast， or you may not get home Try not to work long hours， or you may be too tired and sleepy to It’s easy to have an accident at this time You mustn’t drink ， It’s very dangerous to drive after Be careful when the weather is Obey the traffic rules， happy and safe every The roods in our city are usually very busy There are a lot of cars， trucks， vans and buses on the So， we must obey the traffic As a driver， you mustn’t drive too fast， or you may not get home Try not to work long hours， or you may be too tired and sleepy to It’s easy to have an accident at this time You mustn’t drink ， It’s very dangerous to drive after Be careful when the weather is Obey the traffic rules， happy and safe every da I am often very afraid to cross large wide I always go to the traffic light and use the crosswalk，but many times I have been frightened。 When the light changes to green，I still need to look both directions to check the traffic On many occasions a speeding motorcycle or bicycle or once a truck drove past the red light and across the pedestrian's When I have my bicycle，I get off and walk across the street，but always someone crosses the red Once at the intersection near National Taiwan University I saw an accident：a taxi had stopped for the light，and another truck came from behind and did not For safety，it is very important for everyone to obey the traffic 【参考译文】横过大宽马路时，我常会害怕。我总是看着信号灯，走人行横道。仅管这样，我还是被吓着了几次。当信号灯换成绿灯时，我还是要朝两边看一下。很多时候，超速行驶的摩托车或自行车甚至是卡车，都闯红灯穿过人行横道。当我骑车时，我就会下来，推着车子步行过马路，但总有人闯红灯。一次，在靠近购物广场的那个十字路口，我见到了一起交通事故：一辆出租车停在那儿等红灯，但是它后面的卡车没停。所以，从安全计，每个人都遵守交通规则是很重要的。 更多4条 

土木工程结构试验 论文 班级：XXXXXXX 姓名：XXXXXXX 学号：XXXXXXX 结构试验铰支座试验在建筑试验中，很多的数据、理论都是通过大量的实验得到的。在做试验的过程中，就不可避免的需要考虑试验的环境、装置的固定、现场环境的条件模拟等等一系列问题。在谈及到试验装置的固定时，人们通常会根据结构试验的目的的不同，根据不同的思路设计试验装置的支座。其中的一种思路就是结构试验的铰支座。结构试验中的支座是支承结构、正确传递作用力和模拟实际荷载图式的设备，通常还要承受操作时的振动与地震载荷。铰支座即为物体与所需固定位置连接方式为铰接的支座。在结构设计中，常见的支座或边界条件为简支边界条件采用铰支座实现，一般铰支座有如下的几种形式。活动铰支座活动铰支座容许架设在支座上的构件自由转动和在一个方向上移动。它提供一个竖向的支座反力，不能传递弯矩，也不能传递水平力，不能阻止物体沿支承面方向移动，也不能限制物体绕销钉转动，但能限制物体沿支承面负法线向运动。它比下面要介绍的固定铰支座更加精确，因为简单滚轴支座在水平方向滚动时，在与试件接触的位置时刻变化着，导致了试件的支承位置变化，即支座反力作用点发生变化。活动铰支座的支座反力是通过销钉中心，垂直于支撑面，但由于其上所受的力不能确定，所以具体指向还是不能确定，应具体问题具体分析。下图就是活动铰支座的简图。固定铰支座容许架设在支座上的构件自由转动但不能移动的支座叫做固定铰支座。从理论上来讲，固定铰支座应能承受水平力，但在梁类构件的试验中，只要一个支座为活动铰支座，另一个支座的水平力通常很小，小到可以忽略不计。但在实际情况中它提供一个竖向的支座反力，不能传递弯矩，也不能传递水平力。在连续梁的静载试验中，只有一个支座为固定铰支座，其余均为活动铰支座。为了避免试件制作误差和支座安装误差引起初始沉降，连续梁的铰支座高度应可调。固定铰支座的受力是通过销钉中心，但力的指向不能确定。所以，一般在计算中我们习惯用两个正交的力（通常都是水平方向和竖直方向的两个力）来代替这个力。梁柱试件的铰支座除了上面说的活动铰支座和固定铰支座这两种形式外铰支座还有一种形式，那就是柱式试件的铰支座。柱或墙的试验所采用的支座也属于固定铰支座。在柱受压实验中，对压力作用点有比较高的定位要求。在长柱试验机上进行偏心受压的静载试验，偏心距是试验中的一个主要控制因素。试验机的压板采用大曲率半径的圆弧支座，不能满足柱式试验机的压板上还要安装铰支座。铰支座的分类还很很多，不同的分类方法会得到不同的构造形式。例如作用方式不同有滚动铰支座、固定铰支座、球铰支座和刀口支座（固定铰支座的一种特定形式）几种。一般都用钢制。 简支构件和连续梁支座 这类构件一般一端为固定铰支座，其他为滚动支座。安装时各支座轴线应彼此平行并垂直于试验构件的纵轴线，各支座间的距离取为构件的计算跨度。为了减少滚动摩擦力，钢滚轴的直径宜按荷载大小根据下表选用。但在任何情况下滚轴直径不应小于 钢滚轮的上、下应设置垫板，这样不仅能防止试件和支域的局部受压破坏，并能减小滚动摩擦力。垫板的宽度一般不小于试件立承处的宽度，垫板的长度按构件挤压强度计算且不小于构件实际支承长度。垫板的厚度h可接受三角形分布荷载作用的悬壁梁计算且不小于当需要模拟梁的嵌固端支座时，在试验室内，可利用试验台座用拉杆锚固。只要保证支座与拉杆间的嵌固长度，即可满足试验要求。 四角支承板和四边支承板的支座 在配置四角支承板支座时应安放一个固定滚珠，对四边支承板，滚珠间距不宜过大，宜取板在支承处厚度的3-5倍。此外，对于四边简支板的支座应注意四个角部的处理，当四边支承板无边梁时，加载后四角会翘起，因此，角部应安置能受拉的支座。板、壳支座的布置方式如图所示。 受扭构件两端的支座 对于梁式受扭构件试验，为保证试件在受扭平面内自由转动，支座形式可如图所示，试件两端架设在两个能自由转动的支座上，支座转动中心应与试件转动中心重合，两支座的转动平面应相互平衡，并应与试件的扭轴相垂直。 受压构件两端的支座进行柱与压杆试验时，构件两端应分别设置球型支座或双层正交刀口支座。球铰中心应与加载点重合，双层刀口的交点应落在加载点上。目前试验柱的对中方法有两种：几何对中法和物理对中法。从理论上讲物理对中法比较好，但实际上不可能做到整个试验过程中永远处于物理对中状态。因此，较实用的办法是，以柱控制截面处（一般等截面往为柱高度的中点）的形心线作为对中线，或计算出试验时的偏心距，按偏心线对中。进行柱或压杆偏心受压试验时，对于刀口支座，可以通过调节螺丝来调整刀口与试件几何中线的距离，以满足不同偏心矩的要求。 在试验机中做短柱抗压承载力试验时，由于短柱破坏时不发生纵向挠曲，短拉两端面不发生相对转动；因此，当试验机上下压板之一已有球铰时，短往两端可不另加设刀口。这样处理是合理的，且能和混凝土棱柱强度试验方法一致。