天再高又怎样，踮起脚尖就更接近阳光。坚持下去，你是最棒的！以下是人见人爱的小编分享的考研作文【优秀5篇】，如果对您有一些参考与帮助，请分享给最好的朋友。
【关键词】轧制过程；轧辊振动；仿真计算；板厚板形控制
板厚板形控制的实质是辊缝控制，而辊系振动又影响辊缝形状。因此，建立考虑辊系振动的轧制理论模型是实现板厚板形动态控制的关键。
一、辊系横向振动方程
以四辊轧机为研究对象，假设：辊系上下对称，工作辊和支承辊两端为弹性支承，之间接触为Winkler弹性基础，考虑剪切变形引起的挠度和转动惯量对轧辊横向振动的影响，在支承辊和工作辊中分别截取一微元段进行受力分析，应用Timoshenko梁模型列出其横向振动方程。
求解此方程，即可得到在轧制力和弯辊力作用下轧辊横向振动位移函数。
二、轧制过程参数求解
以轧制中心线为轴，两工作辊的中心连线为轴，交点为坐标原点，建立坐标系，并规定轴正方向与轧制方向相反。考虑轧机辊系的动态特性及轧制过程中金属变形的动力学特性，利用金属变形动态秒流量相等理论，引入轧机辊系振动速率对轧制过程的影响。求得板带入口截面到轧辊中心连线的距离为
三、仿真计算
以某钢厂2030冷轧机组中的第二机架进行仿真计算，所用参数见表1。仿真结果如下：
图1、图2给出了板带出口厚度的波动情况，可见出口厚度沿板带宽度方向呈二次曲线分布，且在平衡位置附近随时间作往复振动。出口厚度的最大波动量约为，且板带中部波动量大于边部波动量。可知在动态轧制中，轧后板带的出口厚度并不是恒定的，而是一直在做这种比较平稳的微幅波动，而一旦这种波动的幅值超过误差范围，将会引起轧后板带的横向和纵向厚差。
图3、图4给出了单位轧制力的波动情况，可见随着轧辊的振动，单位轧制力也在不断变化。单位轧制力波动的相位与板带出口厚度波动的相位正好相反。单位轧制力沿板带宽度方向也呈二次曲线分布，且板带中部波动量大于边部波动量，单位轧制力的最大波动量约为300kN/m。由于单位轧制力是轧辊横向振动的激振力，所以其波动又会引起轧辊横向挠度的变化，并最终影响板带的板厚板形质量。
四、结论
辊系横向振动特性决定了辊缝形状，辊缝形状又反映了板带的板厚板形质量，可见轧机辊系横向振动特性直接影响到轧后板带的板厚板形质量。本文将轧机辊系横向振动引入到轧制过程中，建立的动态轧制过程模型，为实现动态板厚板形控制打下了基础。
参考文献：
[1]王桥医，谭建平。 基于辊缝动力学的板带轧机垂直振动的研究[J]. 机械科学与技术， 2003， 22（5）： 721-723
[2]孙建亮。 面向板形板厚控制的轧机系统动态建模及仿真研究[D]. 秦皇岛： 燕山大学工学博士学位论文， 2010： 1-5.
[3]王玉良。 基于辊系动力学的板带轧机动态轧制过程模型及仿真研究[D]. 秦皇岛： 燕山工学硕士学位论文， 2011：40-55
[4]铁摩辛柯S， 杨D H， 小韦孚。 工程中的振动问题[M]. 胡人礼， 译。 北京： 人民铁道出版社， 1978： 293-295
开头(描述现象)
1、Currently, the issue of ...has been brought to public attention.
近来，...的问题已经成为人们注目的焦点。
2、It is a traditional practice to...in our society。
…是传统的共识
3、In the past few years, there has been a boom/sharp growth/decline in...
在过去的几年里，…有明显的增长/下降
4、Along with the rapid growth of ...,...has become increasingly important in our daily life.
随着…的快速增长，…在日常生活中已经变得越来越重要。
5、Recently the issue of whether or not...has been in the limelight and has aroused wide concern in the public.
近来关于是否…的话题已经明确，且引起了公众的广泛关注。
求职信内容包含简单告知求职人从何处获悉空缺职位；自我介绍阐述职位所需的而自己符合的优点；盼对方早日恢复给以面试机会。
第一段：I am looking for a position in 专业 department in which I may use my training in 专业 to solve 专业 problems. I am writing the letter in purpose of applying for your recently advertised position for a staff member.
第二段：表明自己符合该职位。I am sure that I am qualified for it. First, enclosed with this letter is my resume, which further details my previous academic qualifications and working experience. Second, I am young, enthusiastic and sociable, and these personalities also make me a perfect candidate for it. Last, my hobbies include......
第三段：盼能给以面试机会并表示感谢。I wish you would give me an opportunity to be interviewed. I can be reached by calling me or the address on the envelope. I would appreciate it very much if you could consider my application favorably at your earliest convenience and give me a reply.
As is vividly depicted in the picture,简单描述图片内容。 Simple as it is, what the author intends to convey to us is thought-provoking.
Undoubtedly, the implication of the picture is to show us that importance should be attached to Chinese spirit， especially the spirit ofloving our country. On the one hand, it has been universally acknowledged thatloving our countryis beneficial to steering young people to form a correct world outlook. In addition, it also contribute the young people to shoulder the responsibility of the times. On the other hand, it must be pointed out thatloving our countryis the Chinese nation's fine tradition，which is good for the development of our country and society.
After what we have discussed above, we can easily come to the conclusion that effective measures should be taken to publicize the significance of the spirit ofloving our country.The spirit ofloving our countryshould be introduced to the people from the time when they were children, which can be achieved through the education in schools and in families. Only in this way, can our prospect become better and better.
备忘录属于广义信函中的一种，它是公司或者部门内部的通讯形式，主要用于员工之间传递信息，比如会议安排、情况通报、问题处理等。其内容要求简明准确，句式要求完整。备忘录的内容一般包括以下几个部分：
1)标题：Memo位于第一行正中间；
To：收文人，如Tom，All Faculty
From：发文人，如Li Ming
Date：日期，如January 14th，2010
Subject：主题，如Employee Training
3)正文段落：主题下面空两行写正文，不用写称呼和结尾礼词。
4)打字员姓名首字母：写在正文末行空一行的地方。如果没有的话，也可以不写。
5)附件：如果没有，则不需要。
下面我们根据一个情境来写一篇备忘录。
Directions：
You are Li Ming，president of a a memorandum(memo)to Tom，vice-president，on the employees' training on computer，telling him the need to train the employees，detailed information，and ask him to write a plan.
You should write about 100 words.
范文
Memo
To:Tom，Vice President
From:Li Ming，President
Date:January 14th，2010
Subject:Computer Training of the Staff
In order to deal with the problem of the high rate of computer illiteracy of the staff，we need to make up a plan for training our employees.
The following factors should be of all，the class runs two hours a week for ten ，the employees are supposed to be classified into different classes according to their current computer ，the company had better put the employees through the program in turn.
I would like you to write up a brief proposal covering the above you can add other details if necessary.
考生注意
第一行中间位置写上M〈ＷＷＷ．BAIHUAWEN.com〉emo，并且信头的四要素(to，from，date和subject)一个都不可缺少；另外，正文要空两行再写。