TechWatch – VacMaglev train

Posted in Sustainable development, Transportation by ths1104 on 21/05/2011


The VacMagLev train is a as-yet-unbuilt Maglev train circulating in vacuum tubes.

Vodpod videos no longer available.


  • No friction between the trains and the tracks (magnetic levitation)
  • No air drag (vacuum)
  • > High speed: up to 20,000 km/h [?] (no penalty of sonic boom)
  • > Low operating cost (energy costs to move the train, maintain the vacuum, cool and power the magnets are low compared to energy costs of conventional trains [1]) ?
  • Low greenhouse gases emissions (electric)
  • Possibility of regenerative breaking
  • Possibility of automation
  • Quiet operation (vacuum)
  • Safe


  • High construction cost. For partial-vaccum tunnels, it costs US$2.95 million/km more than target Maglev lines price in China (US$24.6 million), or 12% of increase [6,7].
  • High centripetal forces if bended tubes ? (problem is inherent to any mode of transportation)


  • A laboratory at Southwest Jiaotong University, Sichuan, China, is working on a prototype with an average speed of 500 to 600 km/h running in partial-vacuum tunnels [5].
  • Suissmetro proposed to connect in Swiss cities with a VacMaglev running in partial-vacuum tunnels at up to 600 km/h [2].
  • F. P. Davidson and Y. Kyonati have proposed a VacMaglev transoceanic line using a tube floating 300 m below the ocean surface and anchored with cables, allowing to go from New York to London in less than one hour [3].
  • Dr. J. Powell has since 2001 led investigation of a concept using a VacMaglev system for space launch [4].


  • ” Establishing a Small-Diameter Vacuum-Enhanced MagLev (SDVEML) system would allow for virtually limitless transportation of materials, at significantly lower costs.” – D. Wade,  the Buckminster Fuller Challenge 2011, website.
  • “Passengers […] having paid $54 [can] travel in 54 minutes from the centre of New York to the centre of Los Angeles – R. M. Salter,  Meeting of the American Association for the Advancement of Science, 1978, link.
  • “The new technology […] is expected to be put into operation after ten years.” – Z. Yaoping,  academician of the Chinese Academy of Sciences and Chinese Academy of Engineering, [5].
  • “Speed in initial ET3 systems is 600km/h for in state trips, and will be developed to 6,500 km/h for international travel that will allow passenger or cargo travel from New York to Beijing in 2 hours.” – ET3, website.
  • “ET3 can be built for 1/10th the cost of High Speed Rail, or 1/4th the cost of a freeway.” – ET3, website.
  • “ET3 can provide 50 times more transportation per kWh than electric cars or trains.” – ET3, website.
  • “Vactrains could use gravity to assist their acceleration.” – R. Salter, LA Times, 06/11/1972.
  •  “The theoretical limit of the speed of the VacMaglev train is up to 20,000 km/h.” – Z. Yaoping ?
  • “In peak hours, a Swissmetro runs every 6 minutes with speeds up to 500km/h […].” – Suissmetro, website.


[1] Comparison between conventional train and vacmaglev train, ET3 website
[2] Suissmetro website
[3] Transatlantic Tunnel, Extreme Engineering. (video)
[4] Startram project website
[5] “China develops record-breaking 600kph maglev trains“, Q. Li,, 08/02/2010
[6] “Laboratory working on train to run at 1,000kph“,, 08/03/2010
[7]”Shanghai maglev gets official approval“, M. Qing, China Daily, 04/27/2006


How to check if the radioactivity is normal ?

Posted in Science by ths1104 on 18/03/2011

Lots of information about radiation levels are available. But at first glance, these data seem incomprehensible to anyone who didn’t have an advanced degree in nuclear physics [1]. Here is a simple tutorial to calculate the biological impact of a given radiation exposure.

  1. Pick up your radiation measurement source :
    Tsukuba 1
    Tsukuba 2
    Tokyo (Hongo, Komaba, Kashiwa)
    Tokyo (Shinjuku)
    Average Japan by area
    Crowd-sourced from all over Japan
  2. If the measure is in microsievert per hour (uSv/h), divide by 1000. You obtain a value in millisievert per hour (mSv/h).
  3. Multiply by the time of exposure in hour. You obtain a value in millisievert (mSv).
  4. Calculate the biological impact of the exposition to the radiation with the chart below.


  1. We take average value for Tokyo area (line 13) given by Japanese government on March 17th : 0.05 uSv/h.
  2. We divide by 1000 : 0.05/1000 = 0.00005 mSv/h.
  3. The time of exposure is 24 hours so we multiply by 24. 0.00005*24 = 0.0012 mSv. If we multiply this value by 365 to compare it with annual values, we obtain : 0.0012*365 = 0.438 mSv.
  4. Following the chart, the radiation dose received for an annual exposition to this radiation level is equivalent to the one received for an annual exposition to the natural background (~0.48 mSv). There is no need to take any emergency measure.

Biological impact of radiation exposition



[1] “As foreigners flee, Japanese lament lack of info“, Megan Towey, CBS News
[2] Pdf here : Radiation levels

Please send me your other radiation level sources. Please translate this post into Japanese. Please broadcast !

[UPDATE: 05/14/2011]

Online volunteering

Posted in Internet, Social by ths1104 on 05/03/2011

I recently posted this on The Internet Wishlist,

I got some interesting feedbacks. Here is the summary:

  • – This is exactly what I was looking for. It is powered by the UNDP which is a guarantee of seriousness. The interface is rather classical but clear.  I really wonder why NGOs are not taking more advantages of this website. I even could find some technical projects I would be able to volunteer.
  • Catchafire – It could be what I was searching for but it only serves organizations in the Greater New York City area. Moreover I couldn’t find any technical project.
  • Nabuur – It focuses on helping communities by putting them directly in contact with specialists. The projects proposed are not necessarily supervised by a NGO so volunteers should take care when applying.
  • Social actions – This is a kind of search engine for online volunteering. Nevertheless, the interface is not clear, a lot of results are linking to donation websites and it is difficult to find concrete projects.
  • If I ran the world – The concept behind this site is to connect people who need something and people who want to help. It doesn’t seem that there are projects proposed by NGOs but the way they connect people is interesting. “If I ran the world, I would…”
  • Sparked – Similar to Aardvark in the way they identify common interests of people to connect them. They just need more projects/people. Great interface. Have a look !
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