Weblog Seb Harrevelt

An awesome weblog

The one filled with words, pictures ánd a puzzle

Yellow!

It has been a long time since I wrote my last post and meanwhile a lot has happened. So prepare yourself for some ultra-mega-spectacular summary of these last few weeks.

  • 10th of June: done at TNO.
  • “free” time for the next 3-4 weeks.
  • start with my thesis project.

Bam.

Finishing the report for TNO still took a lot of time, which resulting in a busy last work day. But when it was over, it was over. And I could finally have some “free”-time.

In those 3-4 weeks of having no obligatory tasks, it still did not feel like vacation. This was mainly due to an assignment that I had to finish for my last course. Although I enjoyed myself, this creeping thought of having this assignment kind of killed the whole “freedom” feeling.

Eventually I had to start working on this assignment. I assumed that it would be ‘easy’ and I would get it done in no-time, but it turned out to be the other way… Because of my attitude I procastinated a lot which resulted in me working very hard in the last two weeks to really complete it on time.
I know it was my own choice to do it this way and I could have handled it differently but I just wanted to start my thesis project as soon as possible.

And now, the rollercoaster-ride called the “thesis project” has started and will be done in 9 months (approximately/hopefully). Which means that after that time I should have made up my mind on where and what I want to work/live on/in.

It is strange how fast it all goes. The hardest part for me now is to choose where I would like to work. Which comes down to the question: “what kind of stuff do I want to do for 40 hours a week?”
I think you can never really have a ‘good’ answer to that question until you just try something. So that’s probably what will happen over time.

Oh, before I forget! This time I would include a puzzle. According to Wikipedia, a puzzle can be a game, problem or a toy that tests a person’s ingenuity. And this word represents the quality of being clever, orginial or inventive.

The “problem” I have found is:
You are going to visit your grandmother on Mother’s day. You want to give her two cakes. However, to get to her house you must cross seven bridges. At each bridge is a troll who demands ½ of all of your cakes as the price to pass. However, this troll, being a nice troll, feels bad and gives you back 1 of the cakes that he took.

So actually, you could consider this more of a riddle than a puzzle… But maybe riddles are a subset of puzzles… Anyway, if you have read all of this: thank you for reading this!
If you only scrolled down to see look at the pictures and read the puzzle: Well, that is also fine. I mean, you probably had better things to do. Or atleast, that’s what I hope.

 

 

The one with filled with words, pictures and no puzzles.

Welcome, welcome, welcome, welcome, …, welcome, welcome, welcome, …, welcome, welcome, …, welcome,

As you all know, the last couple of weeks the Netherlands/Holland/Dutchland had some really nice weather! Which is good if you want to train a lot for some 1/4 triathlon (like I do). But, of course, there is also a downside.

As I am writing this, I am sitting at my desk, inside…, behind my computer…, with the iron curtains closed…. and no possibility to open a window… I am still trying to think of a way where you can combine a desk-job with being inside and outside. It would be even better if the work you do outside is somewhat physically challenging and still counts as ‘work’.
For now, I have not found a solution to this problem… (If you have found the answer to this, let me know! Sitting inside gets really boring…)

Speaking of solutions, my Matlab file keeps getting more complex/better/awesome’r and is actually solving physical relevant “problems”. These problems aren’t actually problems, when you compare the things you see on the news, they are just a tool to impress your colleagues with your Matlab/smartness-skills.

 

stuff

That is how I feel when I solved another problem.

Now you might be wondering.. oh, what did Seb do? Why is he talking about all this stuff? Well.. just for a quick `heads up’. My intern at TNO consist of simulating the airflow inside a Greenhouse with the Lattice Boltzmann Method. Which is some new fancy method that is mildly awesome and can simulate quite complex stuff.

These last days I’ve been trying to model the relative humidity inside a greenhouse. Which I’ve been somewhat successful in, but I’m not sure yet.
Here is an impression of what I’m looking at most of the time:

CurrentSimulations

(Click on it for a better view)

This is a simulation of a square that is heated from below. It looks nice, but I’m not sure whether it has any use.

In whatever way, anyhow, anyway, -random-, in either way, the intern at TNO is quite alright! (By the way, those first few words are all synonyms).
Yes, you have to be inside all day, yes it might get boring sometimes. But when you are working, you are not alone. You always have your colleagues that can cheer you up, or distract you when you are all out of concentration.

My final presentation will be on the second of June, so my time here is almost over. And I think I’ll miss the people here. The `ambience’ and the way of working appeals to me, not a lot people seem stressed and for most people the quote `work to live, don’t live to work’ applies.

Oh, and check out this video:

[vimeo]http://vimeo.com/80318195[/vimeo]

The one with some sunshine

Well hello there!

For all those people that were thinking: “wow, his last post was really really really long… I’m never gonna read all of that!”
This one is significantly shorter 🙂

First things first! There are finally some results from my intern at TNO. Look at them below…

[youtube]https://www.youtube.com/watch?v=JrjW9WUXs6M[/youtube]

Besides this good news, there is even more good news! But also some bad news… Let me first talk about the good news. As you’ve all noticed, the weather is really really nice. Which is a good ánd bad thing.
Because when you must be inside all-day-long, it kinda sucks. But! In the afternoon/weekend I don’t have to study/work at all, so then I can be outside all the time 🙂

So, because the weather was so nic… suddenly I realize that I’m doing a typical Dutch ‘thing’ now… talking about the weather… Really, if you ever meet someone from the Netherlands, start talking about the weather. They will instantly love you, because you can “relate” to them.
Anyway, because of several reasons, I went cycling last weekend. Not just for fun, no, I had my first ‘serious’ cycling-competition. If you want you can see me here in action (if you don’t, close your eyes really fast now!) :


(Picture was taken by fotokoos.nl)

Although it didn’t go as I’m used to… In retrospect, looking at how much I’ve trained on the bike this year, I did quite alright.

But now the bad news. And I will keep this short…
Because it took so long to get some results at TNO, they didn’t want to proceed with the project I’m on. So one moment you have something and the other moment.. it is all gone 🙁  There is only one upside I can think of right now.. and that is that I can be more in the sun. But that’s about it…

 

 

EDIT: April fool’s!

Oh and for those that were wondering whát you are seeing in the short movie… that should represent the speed (not velocity) at a certain point in the greenhouse. Where the floor (bottom) was heated. As you can see, it moves around quite fast, this is due the fact that I have not optimized some parameters. So it not a good representation of the world, yet.

The one with the not so boring life

Yeah, you’ve read that right… I kinda like this way of life!

This is my fifth week that I am doing my intern now and I start to get used to it… What I’m definitely not getting used to, is
being sick. These last weeks I became sick.. twice!
For the last, like 5 years, I was never sick.. and suddenly two times in a row.

That combined with doing an intern is quite intense and it also crancks up the difficulty to produce results. But after all these weeks, I start to get something.
For those who have read my last blog and checked out the link.. my result are similar to that produces by the matlab file of the Rayleigh -Bernard convection. I have changed the shape of the computational domain and some boundary conditions.

The main goal in this project is to eventually model the behaviour of the climate inside a greenhouse. The project would (for me) be a succes if I could also model condensation, but that can become quite difficult.

I hope that at the end of this month I can post a video with my awesome results. But for now, there is still a lot of reading to do. I never expected that I would need to put in so much effort into this project to gain some results.
It is a weird feeling, somehow I feel quite useless.. but then again, there is no real ‘norm’ to test my progress to.. that is just all in my head.

Yeah, there have been a lot of moments that I feel like the guy in the above picture.. As I’ve already said, the amount of problems you face are numerous but on the ‘good’ side, there are also a lot of solutions!
The trick, for me, is to keep switching between reading theory, trying different solutions and stay focussed on what you are doing. Especially when you are working with Matlab a lot, things can get confusing quite fast.
For example, there were some days that I was plotting my simulation. But I had no idea what kind of values I was seeing, how large my domain was or how fast the air was moving in my domain.
At that point you just know you have to take a step back and start ‘from scratch’.

I PASSED MY LAST EXAM

So, phew, finally.. it is all over! Okey, I have one oral exam left.. but the terrifying-breath-taking-heart-racing-exams are over!

 

Oh  and by the way, I just wanted to let you know… Besides the 40-hour-working-weeks, you can still have a “normal” life. Which was my biggest fear before starting this intern. There is even a big benefit! When you get home from work (and it is friday) you have a full weekend of doing anything you like!
Of course, you have  to get ready for monday.. so..

898

At last, I want to end this (pretty) long post with this video. I saw this on Youtube some days/weeks ago and it really amazed me. Mostly because my hands got really sweaty, yours probably too.

[youtube]http://www.youtube.com/watch?v=eUD-Au5O-30[/youtube]

The one with the start of a new life

Hello there!

After a tiresome 14 hour bus ride, we were finally at the faculty EWI again. Last week was one of the most awesome experiences in a long time. Learning how to (snow)board is really… awesome.

It is even better when you really get the hang of it, without any lessons! But before I continue with this, let us go back to the previous post.
Because I wanted to make a comment on the video I posted. First of all, the whole movie is a moving piece of art. The colors, composition and sound in every scene is sublime.

Second, as you can see, there is a nice contrast between those who make the product and the ones that buy it. The makers make sure that nothing is spilled, everything is clean and well organised.
While on the other hand, those who buy everything, seem chaotic, greedy and inefficiënt. And in the end, they need a quick fix to repair their own created problems.

Thus far my comment on Samsara, now on to more fun (read: mathematical) subjects!

To start off, my exam of the course Stochastic Processes. It has been more than a week since I made it and I am still not sure about it.
Sometimes I reason in a way that I think I passed it, but knowing that the teacher is quite strict in notation/precision I sometimes doubt my previous statement…
Enfin, I can’t change anything now so we will see in a week or two.

The second mathematical topic is about my intern at TNO that I started today!

I woke up around 7:45 am, slept really bad, dreamt weird and felt feverish. After a shower and some breakfast it went a bit better, but I still couldn’t breath through by nose and my eyes had a hard time staying open.
Probably some side effects from last week (boarding, partying, cold outside, warm inside, long nights, long days..)

Jumped on my bike, drove to TNO, walked in the building by 9:00 am… right on time.
The following hours were filled with meeting new people, shaking hands and some chit-chat. After the lunch I could finally ‘start’ with my project.

It still is a little bit vague what my goal will be.. but it revolves around the Lattice Boltzman Method. For a quick example, check out this site

 http://wiki.palabos.org/numerics:matlab_samples

The idea behind this (semi-)resent method is that you don’t look at a bunch of control volumes, rather you look at the particles that bounce around. Together with some assumptions on the movements of theses particles, a neat method follows from this.
This is called the lattice boltzman method and can be used to solve dynamic fluid problems.

Another model that can be used to calculate the movement of fluids, are the Navier-Stokes equations. This model has been around for several more years and there already exist a lot of solvers for this problem.
But, this lattice boltzman method might be ‘better’ in certain situation. The situation I will be in, is the environment of a greenhouse.
It is desireable to have a certain percentage of airhumidity in these buildings, such that the plants can grow as fast as possible.
This model, combined with certain regulators inside the greenhouse, should be able to control the airhumidity. At this moment, the Navier-Stokes equations are still used.. but as I already said, this “new” method might be better in this situation.

In the comming weeks/months I will keep posting my progress and (hopefully) some results.

Now I promised to talk also talk about politics and my graduation project.. I will do the latter next time and the former is summarized in this video:

[youtube]http://www.youtube.com/watch?v=effb2JYiKXM[/youtube]

Bye!

The one with the lack of time

Hello there!

Didn’t had the time to make a full blog this month.. 🙁 Having my exam in just a few hours, after that I’m off to France for a week.. and then we’ve already arrived in february!

But! Before I go, I want to share something today.. Check out this video

[vimeo]http://vimeo.com/73234721[/vimeo]

It is from the movie Samsara, hope you enjoy it 🙂

To give you an idea what I will be talking about in the next (full) blog, here are some topics:

– Last month, of course;

– A bit about the movie Samsara;

– How my last exam went;

– The amount of times I fell during snowboarden (that’s what I will do next week in France);

– My first day at TNO (which starts at 10 februari 9:00 AM sharp!)

– My opinion on politics

– At last, a few lines about my graduation project.

Au revoir!

The one with no useful title

aaaaand there goes another month. The end of the year is near! If it weren’t for the invention of the calendar, I would not believe it.

But before we start talking about the end of the year.. let’s begin with where we left off. Because a couple days after my last blog post, the TU Delft organised the Master Event for the second time this year.
(http://www.tudelft.nl/en/study/master-of-science/come-en-meet-us/master-event/)

At this event, a lot of student from the TU Delft come to the auditorium to get more information about the master they might want to do. It is mainly used to gain more knowledge about the different choices you can make after you finish your Bachelor.

Since I am in the second year of the Applied Mathematic master, it was my job to inform the students about my master. Which is quite fun to do! Especially when people are already really enthousiastic about math and want to hear more about the job opportunities.

– Oh, by the way! I passed the course Bio Environmental Statisics with a nice grade 🙂 Two more courses left! –

Later in the month november a friend from my rowing crew… (Did I already mention that I am a former rower? Which I have done intensively for 2 years at Proteus-Eretes? Well… now you know)… celebrated his 25th aniversiry with a 25-diner. So, the whole crew went to his parents for a delicious diner and some good wine.  It was really nice to see everyone again, because it is hard to keep in touch when you are studying and having all kind of other obligations.

 

And some days after that.. we entered the month december.. the last one of the year. The month with the celebration of St. Nicholas, Christmas days, snow (?) and lots of family time.

This year there was (again) a lot of commotion around the whole ‘celebration’ of St. Nicholas. Maybe most of you already know it, but just to give a summary of the situation:

– St. Nicholas is one person and is white;

– He has a lot of accomplices, called ‘zwarte pieten’ and they are ‘painted’ brown/black.

And that is where the trouble starts. I do not want to go into this any deeper, you can choose the side you want to be in.. or just don’t bother at all and leave it be.

The night with my family (+the girlfriend of my brother!) on the 5th of december was a lot of fun. Got some really well thought presents, like a book about mathematics… Always a good gift.

I could go on and tell you about all the other stuff I did.. but I rather share a nice video.. It is about running.

[youtube]http://www.youtube.com/watch?v=6F7T1EGSoMQ[/youtube]

With this video I would like to introduce the end of this post. The last post of 2013. Good luck with making your new years resolutions, but never forget that you don’t need a ‘new year’ to change your habits. If you really want to make a change, start today. Start now.

 

The one with useful information

Hello there!

It has already been a month since the last time I posted something, time really goes fast when you’re “studying”… Well lets see what has been going on lately.. Oh yeah, I have survived another exam period! Which was not that hard to do, just sit and study, but this time I also had to do a presentation for the course Bio Environmental Statistics.

This presentation was about the results you had obtain from a project you had to work on (by yourself). We were with only four people (in the whole course) so everyone got a different project, hence a different data-set since this course was all about statistics (as the course name already tells).
My data-set was about two group of mice, one group consisted of ‘regular’ mice while the other were germ free mice. This means that the latter group could not reproduce (if I am correct). However, all mice had a certain chance of getting a (non-lethal) lung tumor. The idea behind the experiment was to check whether one group of mice would have a higher chance of getting this lung tumor.

First, I must say that this was quite interesting and hard to do! For me, this was the first time I would do a statistical project on my own with a real data set. So you cannot expect neat models and nice answers. After some struggling I eventually had some results for both the groups. The conclusion was that one would expect that the germ-free mice ‘obtained’  the tumor earlier than the regular mice.

This conclusion came from the distribution I fitted to both the data-sets. But before I could fit a distribution to the data-set I had to do all sorts of non-parametric approaches to get a good guess of which distribution would fit best. This was all done in the setting of a current status model.
All together I learned a whole lot and in a few days I will have an oral examination for this course, the exams of my other two courses will be done in January.

More fun (study related) news!

I finally managed to get an internship at the company… TNO. I hope those guys don’t read this, but actually they were my second choice. Last summer I first tried to get an internship at Ortec (finance), but this did not work out… So I was glad I’ve already had a backup plan and had some contact with TNO beforehand.
Most of the time it is not that hard to get an internship at a company. But there are some thing that you might want to think about before you contact a company.

First of all, why do you want to get there? What drives you to work for them and why do you like to do that? After that, when you have send your resume and motivation letter and you do get an invitation for an interview, then keep in mind how the company thinks.
They want to know what their gain is, why would they benefit of your presence? Does your education level agrees with theirs? Do you have any future plans involving them, would you like to work with them when you’re done with your study?
Besides the questions, realize that this interview is just a conversation between you and some grown-up people. The main goal (for them) is to know if you are good enough and will fit in the companies ‘culture’. And for you, well, you have to make up your own plans/reasons why you want/need that internship.

 

KABLAM

Well I better get back to studying because.. eh.. hmm.. I’ll just open my book and stare at it.

The one with the introduction

Hello dear reader,

a “few” hours have passed and now I finally have/make the time to create my first blog. Before I continue, let me introduce myself by telling my name.
I am Seb Harrevelt.
At this moment I am still 22 years old, or 1182 weeks old, or 8276 days old. What I really really like to do is to workout/sport, at this moment it is some
combination of running/swimming/cycling. I would also like to let you know that my favorite food is risotto…
Since you already know that I study ‘Applied Mathematics’, you now know almost every (important) thing about me!

What you did not know is that I am in the second year of my master. In general, the first year of the master consists of (self chosen) courses and in the
second year you can do an internship and eventually graduate.
There are some other choices you can make, but most people do this.

At this moment I still need to do two courses, do an internship and graduate (of course). Besides these obligations I am also thinking about my future,
as in what to do after my graduation. This is still some vague idea that I have, where there is no certainty whatsoever. Let’s hope that this changes
throughout the year.

In the semester I follow three courses (yeah, that is one more than I need to do.. but I just like this one in particular). The names of the courses are
Stochastic Processes, Bio Environmental Statistics and Computational Fluid Dynamics (CFD). All together I have 7-8 hours of college, it is really not
that much. On Monday and Tuesday I don´t have any lectures at all!
But that doesn´t mean that I have nothing to do, oh no, not even close. In the/my master it is very common to have few lectures but you have to
work a lot on your own/at home.

Later on I will tell you something more about the type of courses they are. For now it is good to know that two of them involve statistics (as you can read..)
and the other (CFD) is about finding/computing numerical  solution to (eliptic/hyperbolic) problems.

Let us look at a picture:

 

The very last thing that I would like to add to this first post.. is that the second year of the master is fun and scary at the same time. The idea
that you are almost done with your study, almost need to find a job, almost need to leave your home and find one yourself, and so on..
is kinda scary.
But at the other hand, I can start “applying” all the things that I have learned in my study. The knowledge I have gathered is getting really
useful and the things I can do are getting somewhat meaningful. Which is really nice to see.

That’s it for now!

PS: Next Sunday (20th of  October) I will run the half marathon in Amsterdam, last year I almost won the race.. came in second:

 

Hello world!

Hello this will be my first blog as an ‘Applied Mathematician’!

 

For now, this is it. Later on, like in a few hours or so, I will add more (useful) text.

 

© 2011 TU Delft