Wednesday, 27 March 2013

The Application of Genetic Algorithm in Backcalculating Pavement Moduli of Three-Layered System Structures Using Database Approach

By Mirza Adrian NP*
Pavement structural evaluation plays an important role in road maintenance. One method to perform pavement structural evaluation is by performing Non-Destructive Test, such as Falling Weight Deflectometer, on pavement structures and performs backcalculation to calculate the pavement’s layer moduli using the acquired FWD deflection data. One approach to perform backcalculation is by using a database of pavement deflection. Using this approach, the calculation of pavement moduli is done by interpolating between enveloping moduli saved within the database. Thus, the accuracy of the results from this approach greatly depends on the data and the method of interpolation. Also, the problem of backcalculation is a complex multi-dimensional problem that has many local minima within the solution space. To avoid that, Genetic Algorithm is used because of its ability to perform global search within the solution domain.
This report studies the database approach for backcalculation and found that backcalculation can be done accurately using a database containing 37.240 pavement deflection data. This database is acquired from combining 49 asphalt moduli (E1), 40 sub-base moduli (E2), and 19 subgrade moduli (E3). This report also found that the semi-logarithmic method of interpolation is a better method to interpolate pavement deflection compared to the linear method of interpolation. The database and the interpolation method are then used to develop Genetic Algorithm based software to perform backcalculation on pavement deflection. Comparison with programme GA BackCalc for 27 real deflection data shows that the results compares favourably well even though the calculation time is quite lengthy.

Keywords: genetic algorithm, backcalculation, pavement evaluation, database

* This is an abstract for my undergraduate thesis. If you would like to see the complete text, you can contact me through my email

Friday, 4 January 2013

Letter To My Younger Self 8 Years Ago.

Dear Mirza,

Soon, on July 2004, you will move to London and start a new life. This will be a hard thing for you to cope. So I am writing this letter to you from the future hoping that it will help you in getting through this transitional phase. I hope that you read this carefully and act upon this writing accordingly.


My dear Mirza, at some points in your life, people will leave you. At some other points in your life, you will leave people. Either way, during these points in your life, you will feel very lonely. You know, that feeling that you're facing this world and all of its evil and problems on your own without friends to share your worries and stories, help your problems, or laugh at your jokes. You know, lonely.

But don't worry. From my experience, I know that it will pass. And will, eventually, come again. It is a cycle that you will feel now and again. In my (or should I say our) case, the cycle time is about four or five years. So I've grown quite used to it. But still, it strikes me (well, loneliness is not the best feeling in the world).

The frequencies of me facing this problem necessitates me to devise a way to cope with these time of my life (or in psychoanalytic diction, create a form of defence for the Ego to face reality without it experiencing much disturbance, you will learn about this later). Perhaps, if I share it here, it will be much use to you right now.

My advice is simply (well like all good advice, simple to say but not that simple in reality) to forget what you had, cherish what you have, and embrace what you will have.

Now, I know that you will disagree with all of my statement above.

You will disagree with the first point, "forget what you had". I know you will come up with the question "How can you forget those fond memories that you have with those dear friends?" to deny it. Well, my answer is this: whatever you had or experienced in the past, in the end, had past. Wallowing yourself in memories and "what had happened" does not help you to cope with the life you're about to live. And, I'm saying this from experience, you will eventually forget. You will eventually forget about people and people will also forget about you. From experience I know that the thought that people will remember people forever and ever is nothing but an illusion. And I know, if you're reading this at the initial phase of your transition, you will, out of sentimentality, disagree with me strongly. But, later - perhaps when you don't even remember ever reading this - you'll see the truth in my statements.

You will also disagree with my second point, "cherish what you have". Again, I know you will deny it with the question "What is there to cherish? I'm not enjoying anything at the moment!" To you, my answer is this: love every seconds of your life however bad yours is. Because whatever you have right now, be it heaven or hell, is the only thing you have right now. You don't have anything that you don't have right now. All you have is now. So cherish it. From observation I know this to be true, "Happiness comes to people who cherish" and "Happiness will never come to those who don't appreciate what they already have". So cherish, and I guarantee you'll be happy.

Lastly, you will also disagree with my last point, "embrace what you will have". The question that you use to deny my point this time is, "How can I embrace my currently unknown future?" My answer is this: Life will not disappoint you. Provided that one condition is fulfilled. Life will not disappoint you if, and only if, you accept whatever life gives to you. Now I know that from your point of view right now the future looks dark and full of unknowns and uncertainties. It is a very scary view indeed. But soon, and little by little, life will shine onto the darkness and reveal some amazing things, and also some awful things. My advice to you is to accept them all. Take and appreciate the amazing things. With the awful things that life gives you, also take them and learn from them. This, my dear Mirza, is the process of growing up. If you refuse some things, you will lose some of life treasures and, more importantly, lose some of life lessons. From experience, I've learned that accepting everything that life gives is a way to get a fuller life. So just accept everything, and life will not disappoint you.


My dear Mirza, this is all the advice I can give to you right now. What you are feeling right now is temporary, like all phases of life are. Just face it as best as you can. I hope, in fact I know, that you'll be alright. But at the same time also not alright. Mais, c'est la vie (I know you don't understand French right now so look it up. This phrase could be one of your life motto later).

Live well Mirza.
Best Regards,
Your Future Self.

*PS: You might want to keep this letter as you will need it again in 8 years – at the end of your college life. When you reach 2013, tell your future self that this letter is still valid and that he doesn't have to worry about a thing. Thanks.