On April 9th, senator Fulbright is remembered (go to http://www.ThankYouFulbright.org for more information, or for submitting a thank you note yourself). I've taken this information from the Thank You Fulbright website:
Senator Fulbright was born on April 9, 1905. The Anniversary of his birth is our one-a-year chance to give thanks.
As Fulbright scholars, our lives and professional careers have benefited because of a Fulbright grant.
Between now and April 9, Fulbright scholars, grantees and alums from around the world can submit their thank you notes to the countries that hosted them or sent them on an international Fulbright experience.
The Fulbright program is funded by governments. In each of us, the governments invested tens of thousands of dollars for our professional development, and our careers benefited from it, so it is appropriate for us to say thank you.
And for the occasion, I've added my Thank You note here as well: To the Ambassador of Belgium to the United States,
How do I even start to express my gratitude towards the wonderful experiences I enjoyed as a Fulbrighter?
In 2008 - 2009, I spent a year in Atlanta, at the Georgia Institute of Technology. Even though I was thrilled to the core for this opportunity, I had no clue of what this year would bring me. I can try to sum it up in this random and widely ranging list: a broader and deeper understanding of my field of study, the passion for research, life-changing travel experiences, the love of my life, a broader perspective of life, the universe and everything - all drenched with large coffees, endless homework notes and random gatherings of all possible nationalities.
It's been a year to remember, and year that shaped me. From the lecture rooms to the coffee places, from the university campus to the heart of the city, from the city to the state of Georgia with its mountains and swamps, from the Southeast to the West coast - I wanted to experience it all, learn from it and grow. To be an ambassador of my quirky surrealist home-country and at the same rate, take in all the sights and sounds of my newer home, became my second nature.
Ever learning, ever trying to deeper understand everything at hand: engineering, but also the vibe of the enormous city that I landed - and from there escaping and setting out to explore even more. I earned my nickname Eva the explorer, and made exploring a purpose itself.
All this, just a fraction, in a nutshell of 365 days only - but enough to leave all previous assumptions touched and questioned. Endlessly I would like to repeat this mantra: "Thank you, thank you"
And again - thank you - for the impact it had on the course of my life is undisputed.
First lecture - ever
on Thursday, March 29, 2012
This month marked another milestone in my PhD learning process - I had my first ever lecture. Of course I was scared, of course I was nervous, but I do think it was a very valuable experience.
Here's what I learned:
1. Preparing takes a lot of time
I measured roughly 30 hours of preparation for the 2 hour lecture (altough that's still better than the old adage that an minute of public speaking requires an hour of preparation). Most of this time was spent at home, during evenings and weekends - when I am typically slower because I am already tired or because I am trying to get some loads of laundry done at the same time.
However, I started it off all wrong (I think). I spent too much time with the material itself. In fact, I fully studied the entire chapter on the topic from the previous course, and then I fully studied the entire chapter that I was going to lecture. I could as well have done just the chapter I needed to lecture - because that is what I actually needed.
2. Cooking up an example is really hard
Coming up with an example was a massive time-drain. I kept trying out different things, from different course books that I own, without really finding a good example. I ended up pulling out an old homework of mine, and manipulating that example until it finally "worked". And still I felt there is room for improvement in there.
3. How to actually do it
Another massive time-drain in my preparation was the question "how am I going to do this?". I googled around a bit about lecturing, and I frowned and scratched my hair a few times - with very little result. I ended up with a hybrid solution of making slides and using notes for writing on the blackboard. I did enjoy not having to draw all the sketches on the blackboard, but just being able to project them, but I think I could explain the material better if I'd take the time to sketch and explain what I am sketching - instead of just projecting it and assuming the students will catch the thought.
4. Timing the lecture itself
That was the hardest part: I went too fast in the beginning and I needed more time for the example than I originally thought. Lesson for next time: bring less material but take more time to explain all of it.
5. The aftermath
I'm amazed to see how much I've learned from it (it sounds cheesy, but it's true). For another course which I TA, I notice that I am much faster at helping the students because I now have the material going through all my veins. Studying and understanding the material is one thing, lecturing it gives you a whole new perspective and level of understanding of the material.
Here's what I learned:
1. Preparing takes a lot of time
I measured roughly 30 hours of preparation for the 2 hour lecture (altough that's still better than the old adage that an minute of public speaking requires an hour of preparation). Most of this time was spent at home, during evenings and weekends - when I am typically slower because I am already tired or because I am trying to get some loads of laundry done at the same time.
However, I started it off all wrong (I think). I spent too much time with the material itself. In fact, I fully studied the entire chapter on the topic from the previous course, and then I fully studied the entire chapter that I was going to lecture. I could as well have done just the chapter I needed to lecture - because that is what I actually needed.
2. Cooking up an example is really hard
Coming up with an example was a massive time-drain. I kept trying out different things, from different course books that I own, without really finding a good example. I ended up pulling out an old homework of mine, and manipulating that example until it finally "worked". And still I felt there is room for improvement in there.
3. How to actually do it
Another massive time-drain in my preparation was the question "how am I going to do this?". I googled around a bit about lecturing, and I frowned and scratched my hair a few times - with very little result. I ended up with a hybrid solution of making slides and using notes for writing on the blackboard. I did enjoy not having to draw all the sketches on the blackboard, but just being able to project them, but I think I could explain the material better if I'd take the time to sketch and explain what I am sketching - instead of just projecting it and assuming the students will catch the thought.
4. Timing the lecture itself
That was the hardest part: I went too fast in the beginning and I needed more time for the example than I originally thought. Lesson for next time: bring less material but take more time to explain all of it.
5. The aftermath
I'm amazed to see how much I've learned from it (it sounds cheesy, but it's true). For another course which I TA, I notice that I am much faster at helping the students because I now have the material going through all my veins. Studying and understanding the material is one thing, lecturing it gives you a whole new perspective and level of understanding of the material.
A setup for half-scale slab shear experiments
on Wednesday, March 28, 2012
Last week, I describe the general ideas behind testing a slab with just one steel plate while in reality cars and trucks in many different varieties are loading the structure. I'll now be going into detail on a few particularities in the setup. As with most of my blog posts, I *try* to write it in such a way that anyone even slightly interested in my work could follow. If you're a structural engineer/researcher and you want a solid background on my experiments, you can check out my research page or get in touch with me - I'd love to share and exchange ideas (one of my reasons for blogging, that is).
In this post, I'll write about the test setup which we used in our first series of experiments. 30 specimens were tested in this setup, and in total almost 130 experiments were done in this setup. Here's how it looks like:
Now there are a few things that I would like to point out in here:
1. The specimen
The concrete slab we test is half-scale of a sold slab bridge. That means that we are looking at a span length of 3,6m and a depth of 30cm. If you'd like to read up on how we make these specimens, here's a picture-heavy post about the slabs.
2. The frame
It's steel - we need a whole steel frame around the load to actually apply the load that can destroy the concrete.
3. The load itself
We increase the load level by using a hydraulic jack, connected to the steel plates which are used to model the tire contact area. Here's how it looks like from close by:
Some researchers have studied the differences between steel plat and rubber pouches filled with water (more like a real tire), to study the difference in an experimental setup. We've opted for the standard solution of steel plates - it gives results at the safe side.
4. The support
Since a concrete slab is not perfectly straight, we need an interface, a buffer layer to smooth it all out. We've used a layer of felt and a layer of plywood:
However, for our colleagues who are using complex computer models (non-linear finite element calculations) to simulate the behavior of the slab during the tests, our choice for felt seems to be quite an obstacle. By now, we've been testing and squeezing the felt in many different ways, but it turns out to be a difficult material to model.
5. The "continuous" support
A real bridge has more than two supports, and that means that the intermediate supports will have a moment at the location of the support. We've used prestressing bars, tied to the strong floor of the laboratory to hold back the rotation of the slab over the support - and thus creating a moment there were we need it. In the picture below, there are the ends of the 3 bars, all with a load cell to measure the force in the bar, and the red box beam which distributes the load over the width of the specimen. Also, note that underneath the concrete specimen, you can see that the prestressing bars keep going down - in fact, they go down through the strong floor all the way to the basement.
6. The measurements
Look at the smaller black lines you see over the concrete slab, parallel to the support and over the span length. Those are parts of the measurement frame: we use lasers to measure the displacements at several positions, to know how the slab reacts to the load. To hold the lasers into their fixed position, they are mounted on these smaller steel frames.
That basically sums up the most important elements of my first test setup. For our second series of tests, we had to make a few changes, but I'll get back to that in another post.
In this post, I'll write about the test setup which we used in our first series of experiments. 30 specimens were tested in this setup, and in total almost 130 experiments were done in this setup. Here's how it looks like:
Now there are a few things that I would like to point out in here:
1. The specimen
The concrete slab we test is half-scale of a sold slab bridge. That means that we are looking at a span length of 3,6m and a depth of 30cm. If you'd like to read up on how we make these specimens, here's a picture-heavy post about the slabs.
2. The frame
It's steel - we need a whole steel frame around the load to actually apply the load that can destroy the concrete.
3. The load itself
We increase the load level by using a hydraulic jack, connected to the steel plates which are used to model the tire contact area. Here's how it looks like from close by:
4. The support
Since a concrete slab is not perfectly straight, we need an interface, a buffer layer to smooth it all out. We've used a layer of felt and a layer of plywood:
5. The "continuous" support
A real bridge has more than two supports, and that means that the intermediate supports will have a moment at the location of the support. We've used prestressing bars, tied to the strong floor of the laboratory to hold back the rotation of the slab over the support - and thus creating a moment there were we need it. In the picture below, there are the ends of the 3 bars, all with a load cell to measure the force in the bar, and the red box beam which distributes the load over the width of the specimen. Also, note that underneath the concrete specimen, you can see that the prestressing bars keep going down - in fact, they go down through the strong floor all the way to the basement.
6. The measurements
Look at the smaller black lines you see over the concrete slab, parallel to the support and over the span length. Those are parts of the measurement frame: we use lasers to measure the displacements at several positions, to know how the slab reacts to the load. To hold the lasers into their fixed position, they are mounted on these smaller steel frames.
That basically sums up the most important elements of my first test setup. For our second series of tests, we had to make a few changes, but I'll get back to that in another post.
Finding time for writing
on Monday, March 26, 2012
About a year ago, I wrote about decisions and priorities, and I referred to the urgent-important matrix which can help you prioritize your tasks. My top priority is writing my thesis and getting my doctoral degree - but it seems to be harder than I thought to find time for writing my thesis.
A year deeper into the program, and I can only say that the list of tasks has increased even more. It seems to me that there is some sort of a snowball effect. I realized I wanted to have written the first 4 chapters of my thesis by the end of March, but I only managed to draft the introduction chapter (something which roughly took me 2,5 hours during evenings). It seems like I don't get to writing in my office hours, because there are too many urgent/important things to be finished. Reports need to be written, meetings prepared and held, and then there a "few" sideprojects that I took on, which seem to quietly eat up all the crumbs of time I might have left in the day.
But to finish a PhD, you have to write the thesis. Because my thesis deadline is over a year away from now (that is, if I don't want to apply for an extension or end up with unemployment money), it's easy to keep on pushing it to the back and try to deliver all the other work prior to get serious about the writing.
As of now, my strategy has been to write from home in the evenings and during the weekends. Even though the evening hours are typically not my best writing hours because I am already slightly tired by then, I do enjoy not being disturbed while writing. The large disadvantage so far has been the fact that I am mostly writing on my personal laptop, a 5-year-old machine which would prefer to retire than to have another thesis pushed out of himself. I also don't have the same versions of MS Office on my laptop as on my office computer. I bought a download from a more recent version of MS Office through a webshop, but so far we're 1 week after the purchase and I only get errors and their support team is incredibly slow at responding. (And I hate having spent money on something which doesn't work!).
Another strategy I tried was going earlier to the university. The initial goal was to have my mails and other smaller tasks out of the way earlier in the morning, but I've contemplated reserving the first two hours for writing.
Alternatively, I might consider hiding in the library, or going to a coffee place for writing. I'm still trying to find the best way to get the writing done, and the biggest challenge in there seems to be to find the time for writing.
A year deeper into the program, and I can only say that the list of tasks has increased even more. It seems to me that there is some sort of a snowball effect. I realized I wanted to have written the first 4 chapters of my thesis by the end of March, but I only managed to draft the introduction chapter (something which roughly took me 2,5 hours during evenings). It seems like I don't get to writing in my office hours, because there are too many urgent/important things to be finished. Reports need to be written, meetings prepared and held, and then there a "few" sideprojects that I took on, which seem to quietly eat up all the crumbs of time I might have left in the day.
But to finish a PhD, you have to write the thesis. Because my thesis deadline is over a year away from now (that is, if I don't want to apply for an extension or end up with unemployment money), it's easy to keep on pushing it to the back and try to deliver all the other work prior to get serious about the writing.
As of now, my strategy has been to write from home in the evenings and during the weekends. Even though the evening hours are typically not my best writing hours because I am already slightly tired by then, I do enjoy not being disturbed while writing. The large disadvantage so far has been the fact that I am mostly writing on my personal laptop, a 5-year-old machine which would prefer to retire than to have another thesis pushed out of himself. I also don't have the same versions of MS Office on my laptop as on my office computer. I bought a download from a more recent version of MS Office through a webshop, but so far we're 1 week after the purchase and I only get errors and their support team is incredibly slow at responding. (And I hate having spent money on something which doesn't work!).
Another strategy I tried was going earlier to the university. The initial goal was to have my mails and other smaller tasks out of the way earlier in the morning, but I've contemplated reserving the first two hours for writing.
Alternatively, I might consider hiding in the library, or going to a coffee place for writing. I'm still trying to find the best way to get the writing done, and the biggest challenge in there seems to be to find the time for writing.
The PhD Movie
on Saturday, March 24, 2012
If you're a PhD student, you certainly know PhD Comics. Equally funny, there is the PhD Movie. Yesterday, a screening was held on our campus by Promood, and as a fan of the comics, I simply had to go and watch it (even though it was in the middle of the day).
To sum it all up: highly recommended! There are so many situations in there which are familiar to what it is really like. Although doing a PhD in the Netherlands is a bit different from doing a PhD in the US (we don't have qualifying exams for example, and our buildings aren't open 24/7 so pulling an allnighter in the lab is impossible), the general ideas and feelings are the same for everyone.
Also, recommended for everyone having a PhD student in their family, or for recruiters trying to understand why they should or shouldn't hire someone with a PhD degree - because it certainly is a third level of education unlike any other education experience prior to the doctoral study.
To sum it all up: highly recommended! There are so many situations in there which are familiar to what it is really like. Although doing a PhD in the Netherlands is a bit different from doing a PhD in the US (we don't have qualifying exams for example, and our buildings aren't open 24/7 so pulling an allnighter in the lab is impossible), the general ideas and feelings are the same for everyone.
Also, recommended for everyone having a PhD student in their family, or for recruiters trying to understand why they should or shouldn't hire someone with a PhD degree - because it certainly is a third level of education unlike any other education experience prior to the doctoral study.
Using the iPhone to battle insomnia
on Thursday, March 22, 2012
Insomnia is an old friend of mine. As a child, I would get out of bed in the middle of the night and knock my parents' bedroom door to let them know that I couldn't sleep. (And typically my mom would tell me: "Just close your eyes and sleep!"). So I usually ended up in bed, with my eyes closed and then thinking to myself: "OK, here we are, what am I missing now?".
Months pass by in which sleeping is not a problem at all, and then suddenly the old friend is back and prevents me from falling asleep, or makes me wake up at night wondering if it is daytime yet.
In recent stressful weeks, I have experienced it all over again. As compared to my childhood days, it now has an extra component: I now know that I "have to" sleep, because my hours are limited (the alarm clock will ring soon), and if I am too tired I can't get much work done - and if I don't get the work done that I need to do, I will start thinking about that the next evening, instead of just falling asleep.
Now that I got an iPhone, I've tried using it to help me sleep better. Here's a quick overview of what I've used so far:
1. Sleep Cycle
I've only used this app for the last 2 nights, and I haven't used it as an alarm clock yet - I've only been using it to track the quality of my sleep. Usually, when I wake up in the morning I have a vague idea that I woke up 2 or 3 times during the night. Now, I can use this app to actually study which part of the night I am in deep sleep, when I am dreaming, and how many times I wake up. I'll try to use these stats to see if there is a pattern: do I wake up around the same time every night, and can I find an indication of the necessary conditions to get a better quality of sleep (less times I wake up and more deep sleep)?
2. eSleepLite
With this app, you can combine some relaxing sounds, plug in the earphones, and fall asleep. I've used it last week, and it indeed has helped me to fall asleep faster. Usually, I keep listening to the sounds in my apartment building, but this app simply blocks out all the noise and replaces it with relaxing sounds. You can put a sleep timer, so I used it for 2 hours or 3 hours to help me fall asleep and sleep through the first hours in which people keep walking around in the building (typically, the building gets really calm around 2am, so I used the app until roughly that time of the night.
Disadvantage of this app: it can't run in the background, so I can't combine it with Sleep Cycle.
3. Naturespace
Similar to eSleepLite, this gives calming sounds. The quality of the sounds is richer, but the amount of options is much more limited. However, this program can run in the background, so I can actually combine it with Sleep Cycle.
4. Silva Relax
So far, I've only once used this app, but it managed to kill a migraine which would have otherwise either sent me to bed or to heavy medication. After a stressful day, I think 20 minutes of relaxation exercise are better spent than 20 minutes of mindn umbing internet surfing.
Months pass by in which sleeping is not a problem at all, and then suddenly the old friend is back and prevents me from falling asleep, or makes me wake up at night wondering if it is daytime yet.
In recent stressful weeks, I have experienced it all over again. As compared to my childhood days, it now has an extra component: I now know that I "have to" sleep, because my hours are limited (the alarm clock will ring soon), and if I am too tired I can't get much work done - and if I don't get the work done that I need to do, I will start thinking about that the next evening, instead of just falling asleep.
Now that I got an iPhone, I've tried using it to help me sleep better. Here's a quick overview of what I've used so far:
1. Sleep Cycle
I've only used this app for the last 2 nights, and I haven't used it as an alarm clock yet - I've only been using it to track the quality of my sleep. Usually, when I wake up in the morning I have a vague idea that I woke up 2 or 3 times during the night. Now, I can use this app to actually study which part of the night I am in deep sleep, when I am dreaming, and how many times I wake up. I'll try to use these stats to see if there is a pattern: do I wake up around the same time every night, and can I find an indication of the necessary conditions to get a better quality of sleep (less times I wake up and more deep sleep)?
2. eSleepLite
With this app, you can combine some relaxing sounds, plug in the earphones, and fall asleep. I've used it last week, and it indeed has helped me to fall asleep faster. Usually, I keep listening to the sounds in my apartment building, but this app simply blocks out all the noise and replaces it with relaxing sounds. You can put a sleep timer, so I used it for 2 hours or 3 hours to help me fall asleep and sleep through the first hours in which people keep walking around in the building (typically, the building gets really calm around 2am, so I used the app until roughly that time of the night.
Disadvantage of this app: it can't run in the background, so I can't combine it with Sleep Cycle.
3. Naturespace
Similar to eSleepLite, this gives calming sounds. The quality of the sounds is richer, but the amount of options is much more limited. However, this program can run in the background, so I can actually combine it with Sleep Cycle.
4. Silva Relax
So far, I've only once used this app, but it managed to kill a migraine which would have otherwise either sent me to bed or to heavy medication. After a stressful day, I think 20 minutes of relaxation exercise are better spent than 20 minutes of mindn umbing internet surfing.
From real traffic on a bridge to a square steel plate
on Wednesday, March 21, 2012
Often, when people look at my experiments and my test setup, they are confused when I tell them that I am studying a bridge under traffic loads. How can a little steel plate of 300mm x 300mm or 200mm x 200mm help me to understand how a bridge behaves under traffic? Of course, there are several simplifications that we need to make to come to this point, and, likewise, we are indeed looking at a model of reality, what all the limitations a model has.
So, how do we go from a real bridge with trucks and cars and all that to a test slab with a steel plate?
1. From real traffic to load models
Real traffic consists of many different types of vehicles in different sizes, shapes and weights.We can measure the real traffic (you might have noticed that there are measurement points in the roads of the highways which study the traffic). To calculate a bridge with all these different vehicles would be a daunting task. Therefore, our typical engineering approach (which you also find reflected in the codes that tell you how to design a structure) is to use a load model. That load model is a simplified version of the real traffic. For different cases, there are different load models, and certainly your structure needs to fulfill all the structural requirements for all the different load cases it can be subjected to.
A typical load case works like this: it smooths out the cars and trucks over all of the lanes, in such a way that the load is smeared out over the entire surface (as if all the lanes would be packed and packed with cars, the case you have during a traffic jam). Next, you might consider that the rightmost lane has heavier traffic, and this makes you end up with a load which is again smoothed out, but only over the rightmost lane. This load together with the previous one (over all the lanes) will have a higher value than the value you have over all the lanes, because its whole purpose was to model the fact that the heavy trucks are on the right lane.
Then, we place some design trucks on the bridge that we are looking at. These design trucks are, in European practice, 4 squares that you draw on the deck of the bridge and in which you place a load. We consider the wheels to be 400mm x 400mm, at 1,2m distance along the span length and at 2m distance along the width. The first lane has the heaviest design truck, and the next lanes have increasingly less heavy design trucks. To study the worst case scenario, it is necessary to find the most unfavorable location of these design trucks all together on the bridge deck.
2. From load models to a loading plate
If you study the problem of the shear capacity of solid slab bridges, you will find that the contribution of the wheels of this design truck which I just explained is a major contribution to the occurring load. Because the wheels of the design truck are modeled as squares of 400mm x 400mm, it is also not really clear how to spread this load. If you look at the support, it is clear from engineering judgment that the effect of this concentrated load will have flared out a bit (you can compare this to throwing a rock in a pond - the water will ripple and the ripples will touch a larger length once they reach the borders of the pond, provided that it is a reasonably sized pond). The question for these wheel loads remains then how much they can be smeared out over the length of the support.
With all these issues at hand, we've determined that it is most interesting to look at the part of the load model that comes from the design truck. In some experiments done in Switzerland, 4 load plates are used to model the design truck just like we use it in the code. However, to study some basic phenomena, it is necessary to make another extra simplification.
And that last round of simplifications includes studying just one of the wheels of the design truck. Because the slabs I test in our laboratory are scale models, we also scaled the size of the wheel: we've used steel plates of 200mm x 200mm as well as steel plates of 300mm x 300mm.
And so, a little steel plate can hold in itself a whole simplification procedure of trucks and cars.
So, how do we go from a real bridge with trucks and cars and all that to a test slab with a steel plate?
1. From real traffic to load models
Real traffic consists of many different types of vehicles in different sizes, shapes and weights.We can measure the real traffic (you might have noticed that there are measurement points in the roads of the highways which study the traffic). To calculate a bridge with all these different vehicles would be a daunting task. Therefore, our typical engineering approach (which you also find reflected in the codes that tell you how to design a structure) is to use a load model. That load model is a simplified version of the real traffic. For different cases, there are different load models, and certainly your structure needs to fulfill all the structural requirements for all the different load cases it can be subjected to.
A typical load case works like this: it smooths out the cars and trucks over all of the lanes, in such a way that the load is smeared out over the entire surface (as if all the lanes would be packed and packed with cars, the case you have during a traffic jam). Next, you might consider that the rightmost lane has heavier traffic, and this makes you end up with a load which is again smoothed out, but only over the rightmost lane. This load together with the previous one (over all the lanes) will have a higher value than the value you have over all the lanes, because its whole purpose was to model the fact that the heavy trucks are on the right lane.
Then, we place some design trucks on the bridge that we are looking at. These design trucks are, in European practice, 4 squares that you draw on the deck of the bridge and in which you place a load. We consider the wheels to be 400mm x 400mm, at 1,2m distance along the span length and at 2m distance along the width. The first lane has the heaviest design truck, and the next lanes have increasingly less heavy design trucks. To study the worst case scenario, it is necessary to find the most unfavorable location of these design trucks all together on the bridge deck.
2. From load models to a loading plate
If you study the problem of the shear capacity of solid slab bridges, you will find that the contribution of the wheels of this design truck which I just explained is a major contribution to the occurring load. Because the wheels of the design truck are modeled as squares of 400mm x 400mm, it is also not really clear how to spread this load. If you look at the support, it is clear from engineering judgment that the effect of this concentrated load will have flared out a bit (you can compare this to throwing a rock in a pond - the water will ripple and the ripples will touch a larger length once they reach the borders of the pond, provided that it is a reasonably sized pond). The question for these wheel loads remains then how much they can be smeared out over the length of the support.
With all these issues at hand, we've determined that it is most interesting to look at the part of the load model that comes from the design truck. In some experiments done in Switzerland, 4 load plates are used to model the design truck just like we use it in the code. However, to study some basic phenomena, it is necessary to make another extra simplification.
And that last round of simplifications includes studying just one of the wheels of the design truck. Because the slabs I test in our laboratory are scale models, we also scaled the size of the wheel: we've used steel plates of 200mm x 200mm as well as steel plates of 300mm x 300mm.
And so, a little steel plate can hold in itself a whole simplification procedure of trucks and cars.
The writer's little helper
on Monday, March 19, 2012
Even though I have frequently seen #phdchat community members mentioning how useful they find 750words, I never really gave it a try. I thought it would be totally the same as writing longhand in a diary, which I try to do a few times per week, but recently I decided to try it out anyway.
The real reason to get started with 750words, is that my long-distance fiancé and I were looking for a place where we can write longer things to get a better insight into eachothers' thoughts and needs at a certain day or moment. We decided to open an account together and take turns in writing there.
Here's what I've come to appreciate so far, and why it is an improvement from my handwritten diary entries:
1. 750 words
Slightly a bit of a lame bullet point, but it really is about writing 750 words. I don't think I get to write that many words when I write longhand on paper. And the fact that you need to write 750 words before the entry is "done", helps you to go a little deeper and explore what worries you or excites you at a certain day or moment. It gives me a place an opportunity to figure out what is really on the bottom of my thoughts and why I am stressed out sometimes.
2. Write more, write faster
Writing is like training a muscle - first it is difficult (it takes you ages to complete your first paper or first abstract), but afterwards it becomes easier. You'll end up finding it simply easier to put together a sentence and get the writing done.
At 750 words, the website tracks your speed of writing (x words/min on average), as well as the total time it takes you to write your 750 words. My fastest entry so far was yesterday's 12 minutes. I think 750 words is an excellent place to practice writing and organizing your thoughts. Even though I write as I go there, without stopping the flow of words, I'm positive that this will help me on learning to write more and faster - something that will come in very useful since I just started writing my thesis.
3. Stats
One of the features that I appreciate most about 750 words is that it analyses your entry and shows you some lovely stats. You can find a nice description of how the service works here, from which I also used the following example from the stats. Since I am sharing my account with my fiancé, I find it also very interesting to compare our stats. Although it is obviously different from day to day, looking at the stats from both of us over a longer period of time does show some of the very differences between me and him.While most of my entries are mostly introverted, the majority of his entries are mostly extroverted - a reflection of our very characters.
The real reason to get started with 750words, is that my long-distance fiancé and I were looking for a place where we can write longer things to get a better insight into eachothers' thoughts and needs at a certain day or moment. We decided to open an account together and take turns in writing there.
Here's what I've come to appreciate so far, and why it is an improvement from my handwritten diary entries:
1. 750 words
Slightly a bit of a lame bullet point, but it really is about writing 750 words. I don't think I get to write that many words when I write longhand on paper. And the fact that you need to write 750 words before the entry is "done", helps you to go a little deeper and explore what worries you or excites you at a certain day or moment. It gives me a place an opportunity to figure out what is really on the bottom of my thoughts and why I am stressed out sometimes.
2. Write more, write faster
Writing is like training a muscle - first it is difficult (it takes you ages to complete your first paper or first abstract), but afterwards it becomes easier. You'll end up finding it simply easier to put together a sentence and get the writing done.
At 750 words, the website tracks your speed of writing (x words/min on average), as well as the total time it takes you to write your 750 words. My fastest entry so far was yesterday's 12 minutes. I think 750 words is an excellent place to practice writing and organizing your thoughts. Even though I write as I go there, without stopping the flow of words, I'm positive that this will help me on learning to write more and faster - something that will come in very useful since I just started writing my thesis.
3. Stats
One of the features that I appreciate most about 750 words is that it analyses your entry and shows you some lovely stats. You can find a nice description of how the service works here, from which I also used the following example from the stats. Since I am sharing my account with my fiancé, I find it also very interesting to compare our stats. Although it is obviously different from day to day, looking at the stats from both of us over a longer period of time does show some of the very differences between me and him.While most of my entries are mostly introverted, the majority of his entries are mostly extroverted - a reflection of our very characters.
Contents of my job
on Sunday, March 18, 2012
The idea I used to have of a PhD student, is of someone who spends endless hours behind his computer, focused on one single task. The reality turned out to be rather different for me: hardly ever I get to spend a whole day on one single task, and typically I am juggling several tasks and trying to keep a bunch of projects on the rails.
Recently, I wrote a brief description of what the contents of my job are all about, so I wanted to share it here on the blog as well:
- Experimental research on slabs: continuously supported slabs of 2,5m x 5m x 0,3m. In total 38 specimens were cast and tested up to failure, and as of now, I did 160 experiments (and, along the road, something like a 2000 concrete cubes were tested to determine the cube compressive strength and the splitting tensile strength of the concrete at different points in time).
- Education: I just had my first lecture last week (in Concrete Structures II), I am teaching assistant for prestressed concrete and I supervise MSc thesis students.
- Calculate: I predict the capacity based on the current design codes, I check the forces with linear finite element calculations (most MSc thesis students work with non-linear finite element calculations - and we can learn a lot from that, so that might be something I will be spending some time on in the near future, provided that I can find some time), and monte carlo simulations to better assess the probability of failure.
- Case studies: some extra smaller tasks on existing bridges, as well as developing tools for the Ministry to quickly assess a large amount of the existing bridges. That assessment is an "OK" or a "needs more complicated calculations".
- The science part: writing papers, making posters, do some little tasks for committees here and there, get in touch with other researchers, go to conferences
Recently, I wrote a brief description of what the contents of my job are all about, so I wanted to share it here on the blog as well:
- Experimental research on slabs: continuously supported slabs of 2,5m x 5m x 0,3m. In total 38 specimens were cast and tested up to failure, and as of now, I did 160 experiments (and, along the road, something like a 2000 concrete cubes were tested to determine the cube compressive strength and the splitting tensile strength of the concrete at different points in time).
- Education: I just had my first lecture last week (in Concrete Structures II), I am teaching assistant for prestressed concrete and I supervise MSc thesis students.
- Calculate: I predict the capacity based on the current design codes, I check the forces with linear finite element calculations (most MSc thesis students work with non-linear finite element calculations - and we can learn a lot from that, so that might be something I will be spending some time on in the near future, provided that I can find some time), and monte carlo simulations to better assess the probability of failure.
- Case studies: some extra smaller tasks on existing bridges, as well as developing tools for the Ministry to quickly assess a large amount of the existing bridges. That assessment is an "OK" or a "needs more complicated calculations".
- The science part: writing papers, making posters, do some little tasks for committees here and there, get in touch with other researchers, go to conferences
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