A few years ago, I was applying for a Ph.D. program of an American university. This post is my statement of purpose for the application.

I get to believe that everyone shoulders the responsibility of making a progress to human civilization as I am growing up. That is why I live in the world. Performing research is a way to the goal. Study of past six years gives me knowledge about computer. However, it is not enough for me to carry out individual and deep research. A Ph.D. program equips me with knowledge and ability I need. I can get things done, even though I am not as intelligent as most people. Perseverance plays the most important role and Forrest Gump and John Nash inspire me most.

I like to think when I am alone. I think why I live in the world. I am a son of my parents and they love me very much. They will be extreme miserable if I left the world. I am a friend of my friends. They will felt sad if I were gone. I am a stranger to most people in the world. They just know the fact someone is gone if any of them knew the fact. However, the earth and the universe just run as usual if I were gone. Why have I to exist in the world? Everyone is a part of human civilization. All activities of human beings constitute that. Human civilization is advanced every second. Everybody is contributing to it. What anybody does influents him or her and then influents the world and the human civilization.

The human civilization began from using and creating tools. New objects were created more and more rapidly since then. People create new objects with emerging objects, thus leading to speedup of invention. With new objects emerging, all activities of human beings vary rapidly and so does human civilization.

Researches create novel ideas and new objects. Ph.D. programs are the best preparation for researches. Preservation and basic knowledge give me chance.

I can always control my behavior by perseverance since I was a little child. I had to do homework every day after school when I was attending preschool. I told myself that I must finish my homework before playing. I was six years old at that time. Like most of other children, I was eager to go outside of house to play. In front of my house was a public building. Children liked playing together there immediately after school and their pleasant laughter went far. Of course, my house was filled with their laughter. At that time, I was doing my homework. How much I wanted to play with them！Their laughter continued coming into my ears so I can hardly prevent myself from putting down my pencil and going outside. However, I just told myself I must finish my homework first. I told myself repeatedly. The closer to finishing my homework I got, the harder I felt. Their laughter faded when I got closer to finishing my homework. I had not finished my homework yet when laughter was gone. Soon I got everything done. They had gone home. I could not play with them. How disappointed I was! Such situation happened countless times. That happened during both my preschool and primary school days. Of course I got better grades than most children.

I can control myself with great perseverance. Three years at high school are import for those who want to attend a better college. Millions of high school students compete with each other for the qualification of entrance to colleges. In order to get a better qualification, I tried to use as much time as possible to study. So I did not take a break after class. All students had lunch after the last lesson in the morning and before the first lesson in afternoon. It was about three hours long. Most students could finish lunch within half an hour and the left time could be used for a break. I made use of the time for a break to study and took doze for 15 minutes before the first lesson. It was not enough. I felt sleepy at least one time among the three afternoon lessons. I tried to hear what teachers said when I felt sleepy. I felt sleepier and sleepier. How much I wanted to sleep at that time! However, I did not sleep until teacher said “take a break”. I put my head down on the desk and fell into sleep within one or two seconds once the teacher said the three words. At last, I ranked the first place among all students in my class on the college entrance examination.

I can get things done though I am not as intelligent as most people. After I entered the college, there were more lessons I have to take than before. What was worse, teachers taught much more than teachers did at high school. As a result, I could hardly follow teachers or acquire the knowledge. Many teachers had the habit that they wrote down a question on the blackboard and asked all students write their answers on a piece of paper and submit them before the lesson ends. The question was related to what was taught at the lesson. I sometimes did not how to answer the question because I did not understand the lesson. I felt disappointed because most students could finish it. Because of too many lessons that I did not understand, I must review most of them. I was studying at a classroom or the library while my classmates were doing what they wanted to do. I felt very tired when reviewing so many lessons. I stickled to my study all the four years at the college. At last I got good grade and was allowed to take the graduate program without taking the graduate entrance examination.

The perseverance equips me with quality of getting things done while what I have learnt in the past college years equips me with quality of finishing a Ph.D. program.

My undergraduate major was computer science. The curriculum equipped me with solid basic computer knowledge and practical skills. For example, I designed a 8-bit cpu with two of my roommates. I designed a management system of products for a store from the scratch by my own. Because of my high grade, I was allowed to take the graduate program without taking the graduate entrance examination.

I finished several projects during both my undergraduate and graduate years. My undergraduate thesis was Research on Dynamic Mapping Strategies of Logical Volume in Hybrid Storage Systems. I carried out the research by myself with my difficulties. During my graduate years, I spent the first year at Hunan University. I took many classes which enhanced my basic knowledge and extended my vision. At the same time, I took part into a research project focused on Xen network and wrote a paper DMVL: An I/O bandwidth dynamic allocation method for virtual networks. Afterwards, I came to Tsinghua University, one of the two best universities in China. I joined in a research team of four graduate students. We took part in a national high technology development program. We focused on phase change memory. At first, I investigated many architecture simulators and designed and implemented a lightweight phase change memory simulator. I wrote the paper LPCMsim: Design and Implementation of a PCM Lightweight Simulator. I continued my research and finished a project focused on wear-leveling of phase change memory and finished the manuscript Enhance Wear-Leveling with Wear-Out Tolerance to Extend Lifetime of PCM. I am working on transaction log to reduce writes to phase change memory. I get skills for research from the experience above. Those research projects have significantly improved my practical ability.

Sometimes I feel inferiority. However, I can find hope and never give up. Two people who inspire me most are Forrest Gump in the movie Forrest Gump and John Nash in the movie A Beautiful Mind. What I achieve encourages me.

I fall into deep thought when I am alone and I know why I live in this world. I live to make a progress to human civilization. Researches let me to do it. A graduate program of Ph.D. leads me there.