stiefels.net

Timeline: Response Times by Cell Phone Type

admin — Sun, 20 Sep 2009 10:39:23 +0000

Here is a funny little (not so serious) statistic about iPhone users and their response times:
After sending an invitation to about 20 people with the request of responding within 72 hours I kept track of the timestamps when the answers arrived.
Just for the sake of curiosity I separated the answers into two groups: People with iPhones and people with other cell phones.

And here is the result in form of a timeline:

Biking Around the Region

admin — Wed, 09 Sep 2009 13:04:13 +0000

After several weeks of laziness it was again time for little bike tour around the region.

Apple Store Hamburg Grand Opening

admin — Sun, 30 Aug 2009 19:26:54 +0000

Yesterday, the brand new [Apple Store in Hamburg](http://www.apple.com/de/retail/alstertal/) had its grand opening. I don't know how many people came to be part of this event but there were a lot!
We arrived at about 8am, 2 hours before the store opened its doors for the public. The first guy in the line said that he was waiting since 1am.

Exactly at 10am all the store employees started going crazy and cheered for every visitor like he won a jackpot.
The store is a typical mall-type store with only one floor and no room for bigger events like live performances. None the less, this store is quite impressive and an important step for Apple to gain more presence in Germany. Next stop, [Frankfurt](http://html.ifoman.com.s3.amazonaws.com/chronology.html)?

More photos [here](http://www.flickr.com/photos/mrtentacle/sets/72157622186139612/) and [here](http://www.flickr.com/photos/stohl/sets/72157622062510787/).

[youtube]brhNhAf3e0g[/youtube]

CUDA port of OpenSteer now public

admin — Sun, 23 Aug 2009 19:31:56 +0000

During the last months I was busy writing my bachelor's thesis about parallelizing the [OpenSteer](http://opensteer.sf.net) toolkit using [NVIDIA's CUDA](http://www.nvidia.com/object/cuda_home.html) technology to make use of the power of today's GPUs.

OpenSteer is an open-source toolkit to test and simulate [steering behaviors of autonomous characters](http://www.red3d.com/cwr/steer/) in animations or video games. Steering behaviors are responsible
to navigate a character around its world in a natural way while reacting on influences of its environment, for example to avoid collisions with obstacles.

The source code of this port is now available on [github](http://github.com/simonboots/OpenSteerCUDA/).
My bachelor's thesis about this project is also available and can be found [here](http://www.stiefels.net/wp-content/uploads/2009/08/Parallelizing-the-OpenSteer-toolkit-using-GPUs.pdf).

On Vacation (with iPhone)

admin — Thu, 20 Aug 2009 18:21:30 +0000

I just came back from a very nice vacation I spent in New York City.
This city is amazing and there is so much to see and to do. One of the best vacations I've ever done.

Two weeks earlier during packing I thought about leaving my MacBook Pro at home. After all, it is a vacation and I don't want to spent too much time with it. But then I realized that there is almost nothing that would require a notebook during vacation when I take my iPhone with me.

Answering e-mails, web surfing, twittering ([Tweetie](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=296415944&mt=8)), chatting ([BeejiveIM](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=291720439&mt=8)), navigating ([OffMaps](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=313854422&mt=8)), calculating tips ([Tipulator](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=284935446&mt=8)), checking the Metro trains ([New York Subway](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=301912130&mt=8)), SSHing ([TouchTerm Pro](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=296468040&mt=8)), sending digital postcards ([Postage](http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=312231322&mt=8)) and playing games are all perfectly doable with the iPhone.
Well, perfectly doable when a prepaid data plan would exist in the US. But all the service providers we asked seem to have no need to offer one. That's just sad.

There is only one compromise I had to accept: I had no chance sending pictures I made with my digital camera without a computer. However, handling 12 megapixel images on the iPhone surely wouldn't have been much fun anyway. And there are very nice [Apple Stores](http://www.apple.com/retail/fifthavenue/) in New York with lots of Macs on which I could've done that.

So I decided to leave the MBP at home. And it all worked out well. Sometimes you have to exercise yourself in patience but there are lots of free WiFi hotspots. So the missing data plan was no big deal at all. It even saved us some money.

This experience again made it clear to me that sooner or later traditional computers will only be necessary for complex tasks. For every day living devices like the iPhone are almost sufficient. The iPhone is already a very good companion on the go. Perhaps we will see some sort of "iTablets" replacing the traditional personal computers in the living room in the near future...?

Pro Git book now available

admin — Wed, 29 Jul 2009 10:44:10 +0000

The Pro Git book, written by Scott Chacon and published by [Apress](http://apress.com/) is [now available](http://progit.org) for free. A printed version will be released [soon](http://www.amazon.com/gp/product/1430218339?ie=UTF8&tag=prgi-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1430218339).
Scott also [published](http://github.com/progit/progit) the "source code" of the book under a [Creative Commons license](http://creativecommons.org/licenses/by-nc-sa/3.0/us/).

New Project: Visualization of the Best-Fit Placement Heuristic

admin — Sun, 19 Jul 2009 11:00:45 +0000

Often one has to solve the problem of arranging objects so that they use as less room as possible. In the days before Christmas, for example, people try to utilize the expensive wrapping paper fully in order to save to money for a second roll. Depending on the arrangement of the presents this may work, or not. In the industry, a can factory tries to stamp different sized cans out of a roll of sheet metal. To minimize the waste (and to save money) the company has to think about the cutting of the metal sheet.
Both of these examples describe a problem known as the [two-dimensional cutting stock problem](http://en.wikipedia.org/wiki/Cutting_stock_problem).

Although there is no algorithm available which produces an optimal solution to this problem several heuristics can identify usable solutions within an acceptable timeframe.
One of these heuristics is the *Best-Fit* heuristic (described [here](http://or.journal.informs.org/cgi/content/abstract/52/4/655)), developed by [E. K. Burke](http://www.cs.nott.ac.uk/~ekb/), [G. Kendall](http://www.cs.nott.ac.uk/~gxk/) and [G. Whitwell](http://www.cs.nott.ac.uk/~gxw/home-gxw.shtml) of the [University of Nottingham](http://www.nottingham.ac.uk/).

[This project](/projects/visualization-of-the-best-fit-placement-heuristic/) visualizes the different steps the *Best-Fit* heuristic performs in order to gain an acceptable solution (placing rectangles in a way so that waste is reduced) for a given set of different sized rectangles.

**Update:** Source code is [now available](http://github.com/simonboots/BestFitPlacementHeuristic/).

Projects Moved to Github

admin — Sat, 11 Jul 2009 14:33:01 +0000

Just want to let you know that I've moved the repositories of some of my projects to [github](http://github.com/simonboots). I think they are better off there as they are here.
The [project](/projects) pages have already been updated.

More projects coming soon...

Still Alive

admin — Sat, 11 Jul 2009 14:16:45 +0000

It's been almost 2 months since I last wrote something on this blog. Don't worry, I'm still alive.
The last few weeks I've been busy writing my bachelor's thesis and that's why I had to neglect some things. One of them was keeping this blog updated.
Fortunately, this is over now and I hope to find some more time to write blog posts again.

Germany’s Plan to Implement Internet Filters by Law

admin — Thu, 14 May 2009 08:57:54 +0000

There is a nice article written by Johnny Haeusler from [spreeblick.com](http://www.spreeblick.com) about our (Germany's) government's plans to filter the internet using the excuse of fighting against child abuse.

Fighting against child abuse... sounds right, doesn't it? Sure! But just putting stop signs in front of those disgusting webpages (by using DNS redirections) does surely NOT help ANY child. This crime has to be fought against at the roots - the families that abuse their childs. Implementing internet filters by law is a very dangerous plan - and it will (maybe not tomorrow or next year) be used to censor the Internet.

Even if you don't live in Germany, I think it can't hurt to see what's going on right now in the land of poets and "thinkers".
Johnny's [article](http://www.spreeblick.com/2009/05/13/germanys-plan-to-implement-internet-filters-by-law/) is written in english, so please take a few minutes and read it. Thanks!