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From FrozenToothpaste.com
From my point of view, something bugs me. This video cries out “WE ARE IN CRISIS!”, it reminds me this quote from Michael Chricton:
Arda
Since this Blog is about stuff as the title shows( btw I really should consider major changes in this blog. Come on what’s a blog about stuff, how cheesy is thatJ ) , it’s time to dedicate this post to “stuff” itself. Or, maybe to its story.
“The Story about Stuff” is a documentary about the production-consumption and disposal process of every item that we use in our lives. The narrator Annie Leonard, a former Greenpeace employee with a envorinanmental studies degree, is the one who introduces us this story about what goes wrong in our production-consumption cycle and how we can improve it.
Link to: The Story of Stuff
The 20-minute documentary is definetly worth of watching( Animations rule!). Video looks nice persuasive but I wonder if that story is actually the right one?
Actually, there are many critiques to the Story, a quick research in Google and I found interesting results
First, start with the good news. The new school of thinking that Leonard suggest, are mostly accepted without any hesitations. In other words, there’s nothing wrong with “Green Chemistry, Zero Waste, Closed Loop Production, Renewable Energy, Local living Economies”.
Whereas the arguments of Leonard seem to attract more opposite views. For example:
From FrozenToothpaste.com
“Not everything about manufacturing is “toxic.” Make no mistake, I think there are plenty of dangerous chemicals in the things we produce, but you’re playing fast-and-loose with reality if you’re going to say that manufacturing is the simple practice of putting toxic chemicals onto stuff to produce toxic products.”
From Andybrain.com
“ Annie Leonard raised the freak-out level: We dip our pillows in BFR (brominated flame retardants), a horribly toxic man-made chemical, and we sleep on them!
Not knowing anything about BFRs, I did some research on this. I found two things:
One, BFRs are used primarily in electronics and electronics plastics. Things like computer circuit boards, the plastic casing around a TV set, around the rubber sheaths encasing wires in a computer, that kind of thing. And the BFRs are chemically bonded to those components. That means they’re not flying into the air, we’re not breathing them in.
Two, I was unable to find any evidence of companies dipping pillows or pillowcases in BFRs before selling them.”There is even an Alternate Story of Stuff video series. It critiques Story of Stuff, on Youtube.
From my point of view, something bugs me. This video cries out “WE ARE IN CRISIS!”, it reminds me this quote from Michael Chricton:
“The media did not make extensive usage of terms such as crisis, cataclysm,plague or disaster. For example during 1980’s, the word crisis appeared in news reports about as often as the word budget. In addition prior to 1989, adjectives such as dire, unprecedented, dreaded were not common in television reports or newspaper headlines. But then it all changed.
These terms started to become more and more common. The word catastrophe was used five times more often in 1995 than 1985. Its use doubled again by the year 2000. And the stories changed too. There was a heightened emphasis on fear, worry, danger, uncertainty, panic. “
Long word short, media sells catastrophe news and people buy it. That’s the thing that annoys me, I really can’t decide now. Does Anne Leonard really tells us the truth or sells some part of it?
I think the main problem about the Story of Stuff video is that, it lacks detail and explanation. I know, it's a full 20 minutes, but she needed to explain her points more. I guess she tought so, too. As of March 2010 the book of Story about Stuff is available. I hope this time we may really understand the story about stuff.
Arda
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Test the Signifance of Regression : It’s a basic F test. You do test to check whether regression analysis is really helping you explain a significant amount of variance on the response variable.
Diagnostics and Remedial Measures based on Selected Predictor variables
Validation of the Model : You initally save some of the observations and not include them in regression. Let’s say with 400 observations you calculated an apropriate regression line and for 100 samples you look at how does your regression line fits.
Well, you can use many statistical softwares for regression but I guess SPSS and Minitab are the most popular ones. I first started with SPSS thinking that it’s much more popular software and knowledge of Spss would be a plus because its widely used. At the beginning it looks simple, it is indeed but for some simple tasks Spss is just a waste of time.
I hope this blog post helps you in your analysis.
Posted on 4:36 PM by 4 8 15 16 23 42 and filed under
industrial engineering
Again last semester, for my Statistical Inference Course I was supposed to perform Multiple Regression Analysis on a dataset. In this post, I will share my notes on finding the data and steps of the study and about software selection.
1. Finding the Data:
At the beginning I thought it’s a great oppurtunity to investigate Global Warming. In regression analysis, you try to explain one variable as the function of others and make inferences. So you have several variables namely predictor variables( the ones you use in prediction of the response variable) and one response variable( the one you are interested in).
Coming back to Global Warming example, my initial idea was trying to predict temperature by using C02 level, deforrestation level etc. Why didn’t I do it? Maybe “searching for hours for these data and not finding as I wanted” is the reason.
The challenging part in finding data was that for each different data the sources are different. You have to find different official data from different sources since they are not published together in most of the cases. I could find Temperature Data but I was close to finding CO2 but 2 more problems:
1. There is need to organize the data / Time- Consuming + Time- Consuming+ Time- Consuming
2. I needed more predictor variables (10 would be enough but I had only 2) since in the analysis you decide on whether to keep or omit some variables.
So I gave up my idea on global warming which as a subject looked pretty interesting but finding data and organizing them seemed challenging thinking of the above problems. So what I did? Found a sample dataset.
Coming up with a data yourself, and organizing is not really the purpose of regression analysis. In most of the cases, you are supposed to apply regression techniques on a dataset, no matter what your dataset is. Apparently there are statistics websites presenting datasets for statistical purposes. The great part about that is they present you many sets and you can choose among them which one you are interested in.
http://lib.stat.cmu.edu/ is an example statistical website. (The one I found mydataset) The datasets presented here, are not made up to give nice results, instead they are taken from studies or research papers some time ago.
http://bus.utk.edu/Stat/DataMining/files.htm : This site also gives dataset which you may use for regression. I got the impression that Senic dataset is a very famous one and could be used without hesitation.
You may look at these websites also:
2. Steps of Multiple Linear Regression Analysis
Test the Signifance of Regression : It’s a basic F test. You do test to check whether regression analysis is really helping you explain a significant amount of variance on the response variable.
Diagnostics and Remedial Measures based on all predictor variables : Initially start with the full model where you put all your data. By looking at residual plots you decide whether assumptions below are violated or not, and if they are by transformations you try to correct them.
· Multicolinearity Between Predictor Variables
· Linearity of Error Terms
· Constant Variance of Error Terms
· Independence of Residuals
· Normality of Residuals
Selection of Significant Predictor Variables: After you made sure that full model satisfies all the regression assumtions, in a whole set of available variables you take the ones which helps you analyze a significant amount of variance on Y(response variable). You can either use Stepwise, Forward Selection or Backward Elimination in deciding which variables to include in your model.
Diagnostics and Remedial Measures based on Selected Predictor variables
· Linearity of Error Terms
· Removing Outliers
· Constant Variance of Error Terms
· Normality of Error Terms
Validation of the Model : You initally save some of the observations and not include them in regression. Let’s say with 400 observations you calculated an apropriate regression line and for 100 samples you look at how does your regression line fits.
3. Which Software to Use:
Well, you can use many statistical softwares for regression but I guess SPSS and Minitab are the most popular ones. I first started with SPSS thinking that it’s much more popular software and knowledge of Spss would be a plus because its widely used. At the beginning it looks simple, it is indeed but for some simple tasks Spss is just a waste of time.
For example you want to plot all the residual plots and copy them to Ms Word, Excel etc. , in Spss you have to copy manually each graph manually and it takes time. Editing Graphs,or plotting mutliple graphs in Spss is not easy either.
So I looked to Minitab and Result: Minitab Rules! You can plot variables against each other very easily and save them all in .jpg files. Plus it seems to me that in Minitab you have more options in regression, so I would definitely suggest you to use Minitab. Also, trial version of Minitab is available for 30 days( Way enough for regression projectJ ).
I hope this blog post helps you in your analysis.
End of Course-Related Blog Post Series!!
{ at least for a while}
Arda
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This method is criticized in literature since the algorithm performance depends on a value of M and also it necessitates problem to be in the standard form. Converting a problem in a non standard form to the standard form results in increase in both the number of variables and the constraints (That’s a major drawback!). Yet, efficient methods exist which can accomplish this conversion with the least increase in the problem, the problem still enlarges. Therefore, many sources offer a different method for initial solution. They mostly focus on bounded simplex method but that was out of scope for our project and seemed more difficult.
Posted on 5:04 AM by 4 8 15 16 23 42 and filed under
industrial engineering
Last semester I took IE 501- Linear Programming and Extensions Course. At the beginning I thought the ‘Extensions’ would mean solving large-scale Lp problems in different areas, it turned out that the term ‘extensions’ is in the sense that you dig in the theory of linear programming. The course focused mostly on simplex algorithm in a much deeper way. In undergrad, you learn how to implement this algorithm but in graduate study you learn to combine linear algebra and simplex, thus you study simplex in a much wider way. It seems like having studied simplex before would be a plus for this course, interestingly it does not a make a significant difference, because you look at it in a very different perspective.
1. Coding Simplex in Matlab
For a term project we were supposed to code simplex in Matlab and solve almost 100 BIG instances (maybe I should say giant). In other words, create a Solver like linprog of Matlab. Our objective was solve all instances with our solver, correctly and fastly possible. The project group with lowest average Cpu time in solving instances would get the highest grade.
Matlab is easy to learn and there are many tutorials and websites available in internet in which you can possible find answers to almost all matlab related questions. In many cases, I think Matlab Help is the most clear and comprehensive source.
Coding simplex algorithm is not very very hard to do but as you cover all assumptions( degeneracy, full rank, stardization) it gets challenging. It’s better to write at first the most basic form and that make additions or changes to the code afterwards.
George B. Dantzig (1914-2005), inventor of the simplex method
One of my major loss of time was to use zillions of functions in the Code. I don’t mean the Matlab Built-in functions or anything, it’s just I separated my code in parts (function optimalitycheck, function calculate_new_solution). The simplex code is not very long, and although using functions for different operations seem like a neat way in debugging etc., it actually caused me to look at every function when there is a problem with the code. Waste of Time! So long word short, I’ve used 3 functions in the main code: (1) initial feasible solution, (2) basis update, (3) minimum/maximum ratio test .
Since we wanted our code to solve instances fast, we used Matlab built-in functions (like find, min etc.), which perform better/faster than the for loops that you could write. But for speeding up the code, the first thing you should check for are the unnecessary for loops. Other than that, there are some tricks like using logical indexing, but focus on ‘for loops’, they are the killer ones of your code.
2.Finding an Initial Dual Feasible Solution
The Simplex algorithm has 2 major methods of reaching to optimality. Primal simplex and Dual Simplex Method. In both cases, you have to find an initial solution and than execute second phases of the algorithms and find optimality/infeasibility/unboundedness. For primal simplex method, finding a primal feasible basis/solution is easy. The easiest way is to adding artificial constraints and removing them from the basis, iteration by iteration. Internet is full of sources on primal phase 1 algorithm. Whereas, finding a dual-feasible solution is different.
I spent DAYS to search on how to find a dual-feasible (a basis which is not primal feasible and assures primal optimality). There are websites which explaines how to find a suitable basis for bounded simplex( in which there are upper and lower bounds on variables) but I couldn’t find a single source showing how to do it for standart simplex.
****
A little break.
(I type all the possible keywords to attract a similar drowning person to the answer)
Dual Feasible Initial Basis/ Feasible Dual Initial Basis/ Initial Feasible Dual Basis/ Initial Dual Feasible Basis/ Dual Feasible Initial Solution/ Feasible Dual Initial Solution / Initial Feasible Dual Solution / Initial Dual Feasible Solution / Basis For Dual Simplex/ Dual Simplex Initial Basis
Sorry for the break. The show continues…
****
So we used artificial constraint technique described by Bazaraa. (Books still have stuff not found in Internet)
This method consists of basically adding an artificial constraint(2) to the original problem in which a primal feasible basis is available(can be calculated via phase1 primal simplex) and extending the basis. Then after one primal simplex iteration, the basis becomes primal infeasible and dual feasible. Aloha!
Here is the pseudo code of the algorithm:
If pseudo code above seem complex to you, you can always check out Bazaraa’s textbook where this technique is described with a numerical example.
That method was the most practical to implement for our case.
Finally, some notes on solving the BIG instances with our algorithm. Ok, our algorithm was working perfect with small instances (the ones we could revise by looking at iterations when we are not too lazy/ or shortly TOWCRBLAIWANTL) but when it comes to Giant instances sometimes our code couldn’t find a solution. Since they are not TOWCRBLAIWANTL, we couldn’t possible look at all iterations and find out where it screws up. I guess, the bigger the problem’s size is, or the more there are multiplications, there comes rounding errors, which result in absurd results. Also we thought it can do with the epsilon value we assigned, but blaming Matlab could be a suitable thought alsoJ.
Anyways, I hope these information would help someone and you don’t waste your time like I did.
I’d be glad if you leave a comment if you find this post useful.
For that someone should read this post except me.
For that this blog should be discoverable
fprintf(‘Hear this Google!’);
end
end
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Posted on 4:50 AM by 4 8 15 16 23 42 and filed under
industrial engineering
This January I was pretty busy with my course projects. In graduate level, the projects are generally more difficult than in undergrad and the projects are really detailed.
It’s not that I didn’t like the courses I took last semester but the time to focus on projects was insufficient, therefore I got really tired. I spent so much time to reach some information and I remember typing similar keywords to google for hours and not getting useful information. So I thought I could summarize my projects and give some details which took me a lot of effort and time to reach.
Hopefully, someone who suffers the same problem as I did, may find these blogposts useful. (And this blog would really serve a purpose )
So I will write 2 blogposts and give details about my Linear Programming and Regression Projects.
My knowledge is all yours.
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In the 6th day I were totally convinced that the bays of Marmaris are marvelous.
This is a picture from the Selimiye bay:
Basically in the 6th day we went from above to below.
The photo above belongs to Bozukkale Bay, which was our final destination before returning Albatros Marina, where the trip started.
At the end of this cold February Sailing Trip, I’m glad I did it. I got wet, cold and maybe got exposed to tough weather conditions; still I learnt a lot, had fun and my motivation for sailing multiplied.
I had almost no experience with a big boat, and a Dufour 40 ain’t like a 23 Feet Gorbon. I had never stayed in a boat, and I had doubts whether it would be annoying after some days. Seven days after, I think life on the boat is really enjoyable (as long as you have working toilet and drinking water).
About Sailing Trip Blog Posts: Writing these posts were a lot difficult than I expected cause I only know Sailing terms in turkish. And writing these when you are tired really affects your writing skills. Sorry, if I made any grammatical errors or formed meaningless sentences.
Posted on 11:49 AM by 4 8 15 16 23 42 and filed under
sailing
It’s better to wrap up two last days together, since in the last day mostly “end of trip” theme was around. In the 6th day I were totally convinced that the bays of Marmaris are marvelous.
This is a picture from the Selimiye bay:
At the end of this cold February Sailing Trip, I’m glad I did it. I got wet, cold and maybe got exposed to tough weather conditions; still I learnt a lot, had fun and my motivation for sailing multiplied.
I had almost no experience with a big boat, and a Dufour 40 ain’t like a 23 Feet Gorbon. I had never stayed in a boat, and I had doubts whether it would be annoying after some days. Seven days after, I think life on the boat is really enjoyable (as long as you have working toilet and drinking water).
Le Fin
About Sailing Trip Blog Posts: Writing these posts were a lot difficult than I expected cause I only know Sailing terms in turkish. And writing these when you are tired really affects your writing skills. Sorry, if I made any grammatical errors or formed meaningless sentences.
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Ok, I admit I was not that sweet. Still, after costume change/upgrade, I felt a lot better and enjoy the day.
Posted on 11:44 AM by 4 8 15 16 23 42 and filed under
sailing
When we woke up, sun was welcoming us to the new day. Normally you think a sunny day would be kind of warm, right? NO . NO . NO.
Before the trip, they told us to not carry a sweater for each day and they were right. We all wore the same things all day and even at night, because it can be very cold and since our day clothes are the thickest ones.
I brought 2 sweatshirts to the boat, which were insufficient. In February, if your clothes get wet, they will stay wet (Lesson learnt). My first sweater got wet to the maximum in the first day (vomit festival). So I had to wear the other sweater each day. I didn’t feel skinky or anything but if that one got wet also, I wouldn’t have another one which kind of sucked. (Move away quickly if you see anything fluid-likeJ )
Coming back to Day 3, it was the coldest day of the trip despite the sun. My uniform didn’t keep me warm enough to let me think anything except “it’s damn cold!”. So I went to my room, and put on anything that is not much wet (dry was a strong word in these conditions).
So I kind of looked like Marshmallow Man from Ghostbusters:
We anchored in Dirsek Bay for lunch. Well, honestly anchoring was a lot harder considering the fact that anchor rode fell off without our control and we had to pull all the steel rode in. It was good practice because all the crew wanted to pursue career in weightliftingJ.
We didn’t want to spend the night in Dirsek Bay, and we wanted to do some more sailing. I guess we exegerated a little because the night fell when we were out in the sea, abay from safe bays. Sailing a night is very different from daytime, it is riskier and much more difficult. Yet we had working GPS and hopefully we were not that far from Selimiye Bay. So after putting on lifesavers, using projector and gps we managed to anchor in a safe bay.
In the first days, for dinner we were having classical easy to prepare food like macaroni or scramble-eggs. As days went by, we discovered that some of the crew were really good at cooking so our simple dinners transformed to feasts.
Todays menu:
- · Noodle
- · Really really good Salad (Not because I prepared it myselfJ )
- · Tiramisu
- · Turkish Coffee
Yummmy. I got hungry again.
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Posted on 11:37 AM by 4 8 15 16 23 42 and filed under
sailing
Keywords of the day:
Rain, Hail, Horror, Marina, Bath , Happiness
Here comes the story:
We left Bozburun early in the morning to go to Marti Marina which is a very popular especially in summer. We were ahead of our schedule, so we thought let’s hangout for a while in the open since we have time. Well, sometimes in sailing you never know what to expect.
The wind got stronger and stronger and it started raining really hard. All of a sudden, the waves in the sea took a different form, as if we were in the middle of a hurricane. Plus hail started to fall which made it worse. We had to reef the sails with one hand and cover our faces with the other. Adrenaline!
Looking afterwards, I kind of enjoy now for what I’ve been through, yet at that moment I was only hoping weather to change.
Surviving the weather zone, we could finally reach Marti Marina. Hot water is really a miracle on earth.
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Posted on 11:33 AM by 4 8 15 16 23 42 and filed under
sailing
To compensate the first 2 rainy and windy days, climate has decided to make a gesture on the third day. Sunny warm weather, less wind but suitable to use spinnaker we all had really enjoyed the day.
I could explain that day a little more visually:
We reached Bozburun and had dinner in a fine restaurant. My motivation is at tops.
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Posted on 5:54 AM by 4 8 15 16 23 42 and filed under
sailing
After 10-hour sleep, I was reborn and back alive. We took our fixed main sail, had some breakfast (scrambled eggs) and left the marina in the hopes of a better day.
The weather was again windy and rainy but the waves were smaller compared to the day before. No trouble for our stomachs.
Before the trip, I had only 1 hour to prepare and no time for shopping. I didn’t have windproof pants, some proper shoes or gloves. I was WET WET WET!!!!!
Who wants some adrenaline? The spinnaker was nearly falling to sea, we catched it at the last minute. When it is wet, spinnaker weighs a lot such that 5 guys could only carry it.
8 hours of sailing and we reached Serce Bay, a very lovely bay indeed.
In the trip along with us, there were 3 other boats. We were sailing together and communicating via VHS. We heard that one of the boats had some trouble when they started their motor in the bay. A black fluid was leaking from their engine and no one knew the reason. Again the solution was to dive in and check the blades. Well, a giant plastic bag was stuck in the blades of the engine!!! After it’s removed, everything works perfect.
We had macaroni for dinner and some soup. You know what, after all day sailing every hot meal is a feast.
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Posted on 5:12 AM by 4 8 15 16 23 42 and filed under
sailing
To go to Marmaris, you first go to Dalaman by plane and then you have a one-hour drive. My flight was very early and I couldn’t get any sleep at all (Lesson Learnt: Always sleep before a sailing trip).
Since we plan to spend a whole week on the boat, a group went to shopping for vital supplies. Chocolate bars, chips and alcohol are very important in our survival as the shopping bags show. One-week supplies for 8 people cost almost 500 Euros and to give you an idea we took 25 water bottles of 5 liters.
All the supplies are taken, the paperwork finished we were ready to sail at noon.
We untied the ropes but wait, a rope was stuck to motor fan. In order to leave the marina all the rope must be set free of the motor or motor could be damaged.
Solution: One must dive in the sea (Rainy day in February) and cut the rope.
Victim: Our captain of courseJ
At last, we could leave the marina and get on the way. The weather was very windy, that was not the problem, but the waves on the sea have caused trouble in our stomachs.
40 minutes sleep + hunger + giant waves for 3 hours = VOMIT
I was not the only one of course; half of the crew has vomited. We were all wet, all kind of panicked of the harsh weather conditions and most of us were tired.
Most importantly at that moment, we would all prefer to watch tv in the house, than sail there. I kept asking myself why I was in this trip.
And then, we noticed our main sail was ripped. When a sail on the boat is ripped you have to fix it, otherwise it could be dangerous. You may not control it, yet it may be unusable. So we decided to turn back to Albatros Marina, the place where we left off 3 hours ago.
After a hard day, we were all begging for some hot soup and some food. When our stomachs were full, and our clothes were dry, we thought:
It wasn’t that hard, was it?
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Finally the semester is over. After all the finals to take, projects to finish, and reports to write I finally start enjoying some vacation for myself.
Here is our map:
Posted on 4:50 AM by 4 8 15 16 23 42 and filed under
sailing
Finally the semester is over. After all the finals to take, projects to finish, and reports to write I finally start enjoying some vacation for myself.
For my vacation plans, the most interesting one is a sailing trip I am planning to go. I started sailing almost 3 years ago but I couldn’t continue all the time for various reasons, mostly due to the sailing club I was going to. Although I enjoyed their company, I thought they lacked professionalism and proper organization.
Hopefully, my new university has a very good sailing club, they have tons of activities and they work very hard. 3 times a year, in different seasons, they organize one-week trips to beautiful sailing spots of Turkey and you spend whole week sailing, which is great.
It’s a great experience because you eat, sleep, hang out on the boat and you learn to live like a sailor.
For the first time I am going to a sailing trip and I am planning to write a couple of words each day about it.
We are going to Marmaris and we are planning to sail between famous bays of Marmaris. Mostly we will stay in bays and other times in marinas.
Here is our map:
Our boat is a Dufour 40, it looks pretty cool in the Youtube commercial video below (although ours is older, dirtier and a little smelly)
Let the trip begin……
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Busy busy busy!!!
Posted on 2:56 PM by 4 8 15 16 23 42 and filed under
I hate finals. I hate project deadlines. I hate especially when there are both in the same time.
Anyways, until 26 January, I will be studying for my 2 finals and 3 projects. In graduate level, although you take a few classes, they expect you much much much more.
I hope I will survive and keep on blogging.
A bientot
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Posted on 3:37 AM by 4 8 15 16 23 42 and filed under
New Year 2010!!!
It has almost been one year since I've been blogging( I have only written 10 posts or something!) and 2009 has been an important year for me.
The most importantly I am graduaded from university and got my industrial engineering degree. That's a major step I guess. After zillions of applications, I decided to go for a masters degree in industrial engineering also. So basically, I went from here
To there
With its magnificent view of the bosphorus and its great location, my old scool had a really nice small, warm feeling. Though it's better to change school after a while and observe the differences. I like my new university, although its very challenging, and I think that I've made a good choice.
With this new university, I started to stay on dorm first time in my life. I go to home at weekends and time passes tooooo quickly. Still, I guess I like that also.
In 2010, I plan to write more posts, share more and get the blog going. I am gonna make a list about my plans for the blog very soon.
Thoughts will be provided
in 2010
Happy new year!
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