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Archive for June, 2009

My first LaTeX equation!

Posted by Syeilendra Pramuditya on June 21, 2009

Baru aja nyobain nulis persamaan pake LaTeX, n ini dia persamaan LaTeX pertamaku!!

Sungguh saat2 yg bersejarah.. hihihi… :mrgreen:

q_0'=\frac{\pi c_p w \Delta T}{2\widetilde{H} \sin\left(\frac{\pi H}{2\widetilde{H}} \right)}

Persamaan apa hayo..??

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Helium density in pellet-clad gap of nuclear fuel rod

Posted by Syeilendra Pramuditya on June 20, 2009

Please let me know if you found any mistake , thanks.

The gap between nuclear fuel pellet and inner wall of the cladding of typical PWR fuel rods is filled with Helium gas. When performing neutronic calculation, the density of this gas is needed as an input for the calculation. We can estimate this Helium density by using the ideal gas equation, as described below.

The ideal gas equation [Ref.1]:


Now let’s do some benchmark calculation for Helium under Standard Temperature and Pressure (STP) condition, the data are:

  • T = 273.15 K [Ref.2]
  • p = 101325 Pa [Ref.2]
  • M Helium = 4.002602E-3 kg/mol [Ref.3]
  • R = 8.314472 J/(K.mol) [Ref.1]



The value according to Wikipedia [Ref.3] is 0.1786 g/L, which is in a very good agreement with our calculated value.

So all we need now are the value of Helium pressure and (average) temperature inside the pellet-clad gap. Some typical value of those data for PWR fuel rods are as follow:

  • p = 3 MPa
  • T = 650 K



So Helium density inside pellet-clad gap is roughly about 0.00222185 g/cc.


  1. http://en.wikipedia.org/wiki/Ideal_gas_law
  2. http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure
  3. http://en.wikipedia.org/wiki/Helium

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Surely you MUST read this before you decide to be a Ph.D candidate!

Posted by Syeilendra Pramuditya on June 14, 2009

Ph.D life

Source: http://www.cs.purdue.edu/homes/dec/essay.phd.html

The Basics

A Doctor of Philosophy degree, abbreviated Ph.D., is the highest academic degree anyone can earn. Because earning a Ph.D. requires extended study and intense intellectual effort, less than one percent of the population attains the degree. Society shows respect for a person who holds a Ph.D. by addressing them with the title “Doctor”.

To earn a Ph.D., one must accomplish two things. First, one must master a specific subject completely. Second, one must extend the body of knowledge about that subject.

Mastering A Subject

To master a subject, a student searches the published literature to find and read everything that has been written about the subject. In scientific disciplines, a student begins by studying general reference works such as text books. Eventually, the student must also search scholarly journals, the publications that scientists use to exchange information and record reports of their scientific investigations.

Each university establishes general guidelines that a student must follow to earn a Ph.D. degree, and each college or department within a university sets specific standards by which it measures mastery of a subject. Usually, in preparing for Ph.D. work in a given field, a student must earn both a Bachelor’s and Master’s degree (or their equivalent) in that field or in a closely related field. To demonstrate complete mastery of the subject, a student may be required to complete additional graduate-level courses, maintain a high grade average, or take a battery of special examinations. In many institutions, students must do all three.

Because examinations given as part of a Ph.D. curriculum assess expert knowledge, they are created and evaluated by a committee of experts, each of whom holds a Ph.D. degree.

Extending Knowledge

The essence of a Ph.D., the aspect that distinguishes Ph.D. study from other academic work, can be summarized in a single word: research. To extend knowledge, one must explore, investigate, and contemplate. The scientific community uses the term research to capture the idea.

In scientific disciplines, research often implies experimentation, but research is more than mere experiments — it means interpretation and deep understanding. For Computer Scientists, research means searching to uncover the principles that underlie digital computation and communication. A researcher must discover new techniques that aid in building or using computational mechanisms. Researchers look for new abstractions, new approaches, new algorithms, new principles, or new mechanisms.

To complete a Ph.D., each student must present results from their research to the faculty in a lengthy, formal document called a dissertation (more popularly referred to as a thesis). The student must then submit their dissertation to the faculty and defend their work an oral examination.

Relationship To Products

In some cases, the results of scientific research can be used to develop new products or improve those that exist. However, scientists do not use commercial success or potential commercial profits as a measure of their work; they conduct investigations to further human understanding and the body of knowledge humans have compiled. Often, the commercial benefits of scientific research are much greater in the long-term than in the short-term.

Research Activities

Computer Science research can include such diverse activities as designing and building new computer systems, proving mathematical theorems, writing computer software, measuring the performance of a computer system, using analytical tools to assess a design, or studying the errors programmers make as they build a large software system. Because a researcher chooses the activities appropriate to answer each question that arises in a research investigation, and because new questions arise as an investigation proceeds, research activities vary from project to project and over time in a single project. A researcher must be prepared to use a variety of approaches and tools.

A Few Questions To Ask

Many of you are trying to decide whether to pursue a Ph.D. degree. Here are a few questions you might ask yourself.

1. Do you want a research career?

Before enrolling in a Ph.D. program, you should carefully consider your long-term goals. Because earning a Ph.D. is training for research, you should ask yourself whether a research position is your long-term goal. If it is, a Ph.D. degree is the standard path to your chosen career (a few people have managed to obtain a research position without a Ph.D., but they are the exception, not the rule). If, however, you want a non-research career, a Ph.D. is definitely not for you.

2. Do you want an academic position?

A Ph.D. is the de facto “union card” for an academic position. Although it is possible to obtain an academic position without a Ph.D., the chances are low. Major universities (and most colleges) require each member of their faculty to hold a Ph.D. and to engage in research activities. Why? To insure that the faculty have sufficient expertise to teach advanced courses and to force faculty to remain current in their chosen field. The U.S. State Department diplomatic protocol ranks the title “professor” higher than the title “doctor”. It does so in recognition of academic requirements: most professors hold a Ph.D., but not all people who hold a Ph.D. degree are professors.

3. Do you have what it takes?

It is difficult for an individual to assess their own capabilities. The following guidelines and questions may be of help.

In your college and graduate courses, were you closer to the top of your class or the bottom? How well did you do on the GRE or other standardized tests?
Are you prepared to tackle a project larger than any you have undertaken before? You must commit to multiple years of hard work. Are you willing to reduce or forego other activities?
Research discoveries often arise when one looks at old facts in a new way. Do you shine when solving problems? Do you like “brain teasers” and similar puzzles? Are you good at solving them? In school, did you find advanced mathematics enjoyable or difficult?
Intense curiosity:
Have you always been compelled to understand the world around you and to find out how things work? A natural curiosity makes research easier. Did you fulfill minimum requirements or explore further on your own?
Most students are unprepared for Ph.D. study. They find it unexpectedly different than course work. Suddenly thrust into a world in which no one knows the answers, students sometimes flounder. Can you adapt to new ways of thinking? Can you tolerate searching for answers even when no one knows the precise questions?
By the time a student finishes an undergraduate education, they have become accustomed to receiving grades for each course each semester. In a Ph.D. program, work is not divided neatly into separate courses, professors do not partition tasks into little assignments, and the student does not receive a grade for each small step. Are you self-motivated enough to keep working toward a goal without day-to-day encouragement?
If you choose to enroll in a Ph.D. program, you will compete with others at the top. More important, once you graduate, your peers will include some of the brightest people in the world. You will be measured and judged in comparison to them. Are you willing to compete at the Ph.D. level?
Compared to coursework, which is carefully planned by a teacher, Ph.D. study has less structure. You will have more freedom to set your own goals, determine your daily schedule, and follow interesting ideas. Are you prepared to accept the responsibility that accompanies the additional freedoms? Your success or failure in Ph.D. research depends on it.


A few warnings:

Students sometimes enroll in a Ph.D. program for the wrong reasons. After a while, such students find that the requirements overwhelm them. Before starting one should realize that a Ph.D. is not:

Prestigious in itself
Almost everyone who has obtained a Ph.D. is proud of their efforts and the result. However, you should understand that once you graduate, you will work among a group of scientists who each hold a Ph.D. degree. (One faculty member used to chide arrogant graduate students by saying, “I don’t see why you think it’s such a great accomplishment — all my friends have a Ph.D!”).
A guarantee of respect for all your opinions
Many students believe that once they earn a Ph.D. people will automatically respect all their opinions. You will learn, however, that few people assume a Ph.D. in one subject automatically makes you an authority on others. It is especially true in the science communicaty; respect must be earned.
A goal in itself
A Ph.D. degree prepares you for research. If all you want is a diploma to hang on the wall, there are much easier ways to obtain one. After you graduate, you will have occasion to compare your record of accomplishment to those of other scientists. You will realize that what counts is the research work accumulated after a scientist finishes their formal education.
A job guarantee
When an economy slows, everyone can suffer. In fact, some companies reduce research before they reduce production, making Ph.D.s especially vulnerable. Furthermore, once a person earns a Ph.D., many companies will not hire that person for a non-research position. As in most professions, continued employment depends on continued performance.
A practical way to impress your family or friends
Your mother may be proud and excited when you enroll in a Ph.D. program. After all, she imagines that she will soon be able to brag about her child, “the doctor.” However, a desire to impress others is insufficient motivation for the effort required.
Something you can “try” to find out how smart you are
Sorry, but it just doesn’t work that way. Unless you make a total commitment, you will fail. You will need to work long hours, face many disappointments, stretch your mental capabilities, and learn to find order among apparently chaotic facts. Unless you have adopted the long-range goal of becoming a researcher, the day-to-day demands will wear you down. Standards will seem unnecessary high; rigor will seem unwarranted. If you only consider it a test, you will eventually walk away.
The only research topic you will ever pursue
Many students make the mistake of viewing their Ph.D. topic as a research area for life. They assume each researcher only works in one area, always pursues the same topic within that area, and always uses the same tools and approaches. Experienced researchers know that new questions arise constantly, and that old questions can become less interesting as time passes or new facts are discovered. The best people change topics and areas. It keeps them fresh and stimulates thinking. Plan to move on; prepare for change.
Easier than entering the work force
You will find that the path to successful completion of a Ph.D. becomes much steeper after you begin. The faculty impose constraints on your study, and do not permit unproductive students to remain in the program.
Better than the alternatives
For many students, a Ph.D. can be a curse. They must choose between being at the top among people who hold a Masters degree or being a mediocre researcher. The faculty sometimes advise students that they must choose between being “captain of the B team” or a “benchwarmer” on the A team. Everyone must decide what they want, and which profession will stimulate them most. But students should be realistic about their capabilities. If you really cannot determine where you stand, ask faculty members.
A way to make more money
While we haven’t heard any statistics for the past couple of years, graduate students used to estimate the “payoff” using the starting salaries of Ph.D. and M.S. positions, the average time required to obtain a Ph.D., the value of stock options, and current return on investments. For a period of at least five years that we know, the payoff was clearly negative. Suffice it to say that one must choose research because one loves it; a Ph.D. is not the optimum road to wealth.

The good news:

Despite all our warnings, we are proud that we earned Ph.D. degrees and proud of our research accomplishments. If you have the capability and interest, a research career can bring rewards unequaled in any other profession. You will meet and work with some of the brightest people on the planet. You will reach for ideas beyond your grasp, and in so doing extend your intellectual capabilities. You will solve problems that have not been solved before. You will explore concepts that have not been explored. You will uncover principles that change the way people use computers.

The joy of research:

A colleague summed up the way many researchers feel about their profession. When asked why he spent so many hours in the lab, he noted that the alternatives were to go home, where he would do the same things that millions of others were doing, or to work in his lab, where he could discover things that no other human had ever discovered. The smile on his face told the story: for him, working on research was sheer joy.


Source: http://twofish.wordpress.com/2006/07/26/becoming-a-phd

What does being a Ph.D. mean?  People aren’t Ph.D.’s assume that it’s just a like a masters or undergraduate degree, where you go through the factory assembly line and come out at the other end with a piece of paper that gets you some money and prizes.

But that’s not the case.  You don’t *get* a Ph.D., you *become* a Ph.D.  If you have a Ph.D., it’s not a statement about a piece of paper or certification, it’s a statement about who you are, what you have seen, and how you look at the world.  The certification really doesn’t matter much.  My degree is almost useless as a ticket for money and prizes, but it is a statement about who I am and what I’ve seen.  If you want to erase my degree, go ahead, I don’t think it matters that much.

Being a Ph.D. affects all of my relationships.  It affected who I married, and what my children are like.  I can’t separate my “work life” or my “school life” from my “personal life.”  As you can see, being a Ph.D. affects my feeling toward other people, and it’s part of my marriage.  My wife is a Ph.D. candidate in early childhood education.  An essential part of our marriage involves professional collaboration and respect.  I learn about educational theory from her.  She uses me as a peer briefer to look over her data.  We’ve created more together than children, we’ve created some new insights as to how the world works.  (See next year when her dissertation comes out.)  The professional collaboration I have with my wife is part of our love, it’s part of our marriage, it’s part of how we are, and it’s something that people on the outside of academia don’t quite understand.

Let me give you an example of how bizarre my world might seem to someone who isn’t living in it.  Right now I’m studying the dynamics of volatility smiles.  I’m getting any grades or certifications from this.  I’m not taking any formal courses.  I’m just reading and learning.  Now the stuff I’m reading is also stuff that MFE’s can read, but suppose some were to tell me that the obstensible purpose for what I’m reading is “useless.”  In other words, someone tells me that I’m destined not to have a job on Wall Street.

I….  wouldn’t…. care……

If it turns out that it is *impossible* for me to make any money on what I’m studying.  I’d still study it about as hard.  Because it is interesting.  It’s cool math.  It challenges my mind.  It makes me a better person when I understand how foreign exchange volatility smiles work.  And in my life, the important thing isn’t destination, it’s the journey.  When I think I understand something, my first reaction is to go and find something new that I don’t understand.  When I seem to have mastered a skill, I go and find something I’m incompetent at.
None of that has anything to do with whether or not I become a quant or not, and it’s really hard to explain to headhunters and HR people.


Source: http://www.lysator.liu.se/~matca/phd

The cost of a PhD

There is a cost to everything and the PhD is no exception. I experienced a slipped disc and associated loss of nerve function. Two years later (2000), I still haven’t gotten all of it back. For those who do a lot of programming, it is common with neck and shoulder problems. Of course, staring at a monitor for eight hours a day (or more, much more), will not be good for your eye sight. Then you have the problem that being a PhD is more of a lifestyle than a job; you mix work and free time in such a way that you end up having only work. This is not good, as it leads to higher stress. High stress levels during prolonged time will have such effects as reducing your empatic ability, make you develop depressions, diabetes, etc. I’ve experienced all of those.

My advice to PhD students

Learn to say ‘NO!’.
It is very important that you are able to set limits on your work load, because nobody else will. For example, when you meet your professor one evening and he says ‘There is a conference you should attend. The deadline for an extended abstract of 600 words is at 2400 tonight.’ you have the right to say ‘There is no possibility that I can meet that deadline.’ – and you should.
Working hours
Keep a strict tally of how many hours you work and when. Outside the university, some computer consulting companies have made a point of 6 hours a day. When you find out that you are working 60 hours a week, stop. In the university world, your time is free at no cost to others; from my experience the university do not care if you burn out.
Really do take your vacation. Some PhD students, including me, claimed to take vacation but just kept on working. It is essential for your health to have a change and relax.
Avoid the ‘Grad student algorithm’.
This is an expression from the days of fractal coding of images. It means that you take a picture, a workstation and a grad student and lock them into a room until the job is done. It is the repetitive nature of the task which is really annoying; you are a highly talented and skilled person and you should not be doing “manual” labour.
Stay fit!
You only have one body and it must last you a lifetime. As a PhD, you will most probably work long hours, live under stress, spend too much time at a keyboard, etc. Then you need physical exercise or you will end up a wreck. Spend some time investigating what a slipped disk and diabetes, really means.
Insist on a decent workplace
You need a desk that can be raised so you can work standing up at times. The best working position is usually your next – keep it dynamic and don’t get stuck. You need a personalised chair, too. The left-over from the last inhabitant will most certainly not fit your body.
Run yourself.
Your supervisor will provide some guidance, but you need to be the main force behind your work. You will have to take the initiatives and keep the project moving forward.
Stay focused
It is very easy to get sidetracked – and it is hard to say what is really a sidetrack and what is a fruitful investigation, especially in advance.


Some related articles:

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Calculation code for microscopic nuclear cross section

Posted by Syeilendra Pramuditya on June 13, 2009

Code package:


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Calculation code for spherical nuclear reactor

Posted by Syeilendra Pramuditya on June 13, 2009

Shortlink: http://wp.me/p61TQ-eG

Software License Agreement

This software is given “as is”. The author holds its copy rights, one can download, copy, use, modify, and spread it free of charge, provided that the original sources (the author and this webpage) are properly cited. The author assumes no responsibility, implicit or explicit, for any possible loss or damage due to the use of this software.

By downloading the software, you agree to accept this agreement.

The governing equation being used is the steady state neutron diffusion equation:



Numerical schemes being used are:

  • Central finite difference for flux calculation
  • Gauss-Siedel and S.O.R for flux calculation
  • Power method for criticality calculation

Code package:

Flowchart of the code:


Some previews:



Due to imperfection in the conversion process, document might not be correctly displayed, you can download the original document in MS Word (doc) format on Scribd (free registration is required).

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