A reader asked me for some information on how the dynamic programming algorithm for the TSP works. I was surprised to find that a Google search found no good resources. Wikipedia merely acknowledges its existence: “One of the earliest applications of dynamic programming is the Held–Karp algorithm that solves the problem in time O(n22n).” Read the rest of this entry »
After being “almost ready” for way too long, the next version of OptiMap, based on Google Maps API version 3, is now launched. While I have tested most aspects of the application, there are most likely bugs, since the update touched almost all areas of the code. There are some improvements too, however:
- More robust address lookups (a lot of people experienced a “failed to geocode” error when entering many addresses. This was due to too many requests in a short period of time, and a queue-system has been added to avoid this from happening. The lookups may take slightly longer due to this.
- Progress indicator for directions lookups. Because version 3 of the Google Maps API only allows 10 waypoints in a single request (down from 25 in the previous version), this part is now a bit slower, so a progress indicator is needed.
- Tuning of the solver code based on faster browsers becoming more common. This should improve the quality of the solutions for cases with more than 15 locations.
Please help me solve any bugs that you may encounter by posting a comment on this site. Information that will be helpful when locating the bug includes:
- Browser (with version if possible)
- List of addresses or locations and a description of how to reproduce the bug
- The output that you see (error message, why you think the solution is wrong etc.)
I’ve created a map which shows the measured radiation values in Japan (note that this map is no longer online – the rest of this post is out of date). The data is scraped (credits go to Marian Steinbach) every 10 minutes (hit refresh to get the newest data). You can also click on each measurement location to see a chart of the measurements from that station over time.
Currently, there are about 200 measurement stations, but I’m having trouble finding the latitude and longitude of each measurement station. I’m sure someone who knows Japanese would have more luck…Anyway, I’m slowly working my way through the list of measurement stations, so more locations will be added continously. Any help with this would be much appreciated. Feedback and criticism is welcome, and should be added as comments to this page.
Update 2011-03-20: With the help of volunteer “hosoyamane”, a Japanese translation of the map is now available. It’s great to see volunteers pop up so fast!
Update 2011-03-20: A small spike in radiation is showing up in the stations in the Ibaraki prefecture around 10 am Japan local time this morning. However, the levels are still low (1000 nano-Gray is still 2000 times less than the average yearly dose of background radiation).
Update: The original radiation map I created is no longer maintained. Instead, users are redirected to a map created by the Institute of Information Design of Japan.
It’s gearing up for the next round of financial crisis. While our so-called leaders have enjoyed their annual back-patting exercise at Davos, I have become exceedingly alarmed by what’s currently going on in the commodities markets. Food, energy and metals have all sky-rocketed during the last five or so months. While the financial markets have seen a 20% increase during that period, and this is touted as “the crisis is over”, the prices of raw materials have increased 50-100%. These are the real inputs that the economy and indeed our lives depend on.
Let’s look at some numbers:
And what has the S&P done?
This is looking to me like a very unhealthy market. It’s like the high commodities prices of the first half of 2008 all over again. Only this time, the economy is probably a lot less resilient towards high prices. If the economy tanks again, what instruments remain to bail it out? The “wealthy” nations of the world are already running close to 0% interest rates, and are up to their ears in debt. Printing money, as has already been done, is a surefire way to boost commodities even higher. Peak oil, the climate crisis (drought brought forth some of the high grain prices seen above) and general resource depletion are all converging to shake the foundations of our debt-based consumerist society.
The Davos growthsters have only one plan: Returning to the good old years of growth by “stimulating” the economy by ever more illusional money.
I have another idea: It’s time to question that old growth gospel and stop borrowing money and natural resources from our future.
Embodied energy is the amount of energy that goes into a product during its entire life-cycle. It includes the energy required to mine and refine materials, assemble these into the final product, transport it to the consumer, and dispose of it. An analysis that considers this entire process is called a life-cycle analysis.
A 1-litre plastic (PET) bottle has an embodied energy of roughly 5.4 MJ. This is the same as leaving a 15 W lightbulb on for 100 hours (1 kilowatt-hour is 3.6 MJ, a 15 W CFL lightbulb gives light equivalent to a 75 W incandescent light bulb). Aluminium cans are about 1.7x worse than plastic bottles in this respect.
Recycling changes the picture a little. Recycled PET has an embodied energy about 20-25% lower than virgin PET. Other types of plastic can achieve reductions in embodied energy of up to 50% by recycling.
While recycling can reduce the impact of disposables (and keeps the plastic out of landfills and nature), the impact of recycled materials is still huge. Avoid disposables whenever possible!
Source: The ImpEE Project, The University of Cambridge, Recycling Plastic