Statement of Purpose
I am writing to apply for graduate study in the Department of Mechanical Engineering at UC-Berkeley. My intense interest is in heat transfer related to the emerging areas of MEMS and materials processing, as well as fluid mechanics and combustion. I want to become a world-class researcher in these areas. （首先点明兴趣所在，开头尚可）
A top student from the University of Science and Technology of China (USTC), which is one of the most prestigious universities in China, I am proud of my very strong background in my chosen field and great potential for study and research, which are both key factors to a successful graduate study as well as a successful research career. （prestigious universities这个词语用滥了，建议修改。）
The best proof of my potential for study is the fast rise of my academic rank in my first year in USTC. The first semester in USTC was a depression period for me and I did poorly in most subjects. However, after finding out the problems with my study as well as personal affairs, I spent the second semester in diligent and highly effective study, and my rank in the class soared from the second half of the class to No. 2, this became a story in my class at the time. Since then, I have always kept being one of the top students. My excellent performance in study brought me many awards and my overall rank of the four years is No.3 out of 67 students. （最后一句话非常冗长）
During the study, I always try to make in-depth exploration of regular courses, rather than just earn A’s or B’s in the final exams. For example, in Numerical Heat Transfer, we were required to compare several schemes through solving a transient two-dimensional heat conduction problem. Through careful programming and many numerical tests, I made new observations concerning the effects of relaxation factors and a phenomenon, which I named as “false convergence”. In addition to regular schemes, I also employed the Low-Storage Runge-Kutta schemes proposed by J.H.Williamson, hoping to improve the accuracy of temporal discretization. However, they showed no superiority to other schemes. After carefully analyzing the results, I came to realize that the inherent discontinuity of boundary conditions in this problem limited the accuracy, and a specific scheme has its specific range of application. In addition to regular studies, I have been involved in research projects at an early stage of my undergraduate study. These research projects spanned such diverse subjects as energy conversion, heat transfer, and fluid mechanics. （两个同样的叙述方法，很不好！）
My early research was mainly related to energy systems. As a sophomore, I assisted Dr. Guoquan Qiu in the construction of a kind of novel solar energy collector, and I experimented with it. This first involvement in research gave me preliminary knowledge about “what engineering really is”.（应该解释一下这个博士, a kind of没有必要这么拖沓）
Later, in Dr. Hong Ye’s lab, I took part in the design of a heat pump system which had promising applications in food industry to efficiently desiccate vegetables. I did a large portion of the work in design, construction, experimentation, system analysis and improvement. And the final results were very good. （相同句式重复太多，像were very good， very much之类含糊的词语最好不要用。.）
Later, my interest shifted to biomedical engineering, whose interdisciplinary nature attracted me very much. I joined in Professor Shuxia Cheng’s group, whose research focused on the preservation of cells and tissues, measurements of physical properties of organisms, and other research projects directed at immediate medical applications. I attended the group meetings frequently, and offered my ideas toward many problems. Later, I was assigned the task to calculate the fluid flow and mass transfer in a dialyses system. This was the first project on which I worked independently. It required dealing with two coupling boundary conditions in calculation. I devised a SIMPLE-like method and successfully overcame the difficulties. My work was finally summarized in a technical report and became a part of the Ph.D. thesis of a member in the lab. It should be mentioned that this work was completed when I haven’t finished the courses of Numerical Heat Transfer and Viscous Fluid Mechanics. And now, with added knowledge in these fields, I have renewed interest in biomedical engineering.
Experiences in Professor Cheng’s group made me well aware of the importance of fluid mechanics in engineering systems, so later I devoted great efforts to that field. Through extensive reading, I have kept abreast with the latest developments in fluid mechanics such as Lattice-Boltzmann Methods, ENO & WENO schemes, high-order compact schemes, etc. Currently, I am attending graduate courses in Advanced Fluid Dynamics and Applied Mathematics, participating in Professor Yiliang Chen’s seminar on PDF methods, and attending an elective on fluid flows in MEMS. I believe a sound understanding of fluid mechanics can greatly benefit the research of other disciplines such as heat transfer. （文章的问题在于没有中心句子，实际上，红色字体才是最终要的，）
My interest in microscale heat transfer came from Professors Bu-Xuan Wang and Xiao-Feng Peng’s work in boiling heat transfer in microchannels. Their description of boiling systems using statistical methods really fascinated me. Professor Chang-Lin Tien’s seminal work in the basic mechanism of microscale heat transfer further motivated me to go into this field. This field is full of exciting opportunities and challenges, and is constantly drawing ideas from physics, materials science, electrical and mechanical engineering. A sound understanding of transport phenomena in micro scales can greatly push forward the progress of heat transfer as well as related engineering applications. （不够生动，说法类似）
Therefore, I choose Berkeley, the Mecca of heat transfer researchers in the world, to further my studies and research. With my broad background, solid foundations, and above all, keen interest in this field, I am confident that I can succeed in my graduate studies.
After obtaining the Ph.D. degree, I will
come back to China and continue my research in this area.
I believe that coming into this prosperous field will be one of the most
significant decisions in my life and a graduate experience in Berkeley
will greatly benefit both my own career and my country.