Some random stuff & links...

Only recently (2007/07/13) started this page, so it is pretty scant for now...


Cost of energy


Some orbital stuff


Ray tracing

  • Refractivity of atmosphere in Radio: here

    General statistics, per country: nationmaster.com


    Crime statistics:

  • USA, 2005 Berkeley in 2005, pop. 102 191, 570 violent crimes, 3 murders, 18 rapes, 354 robberies, 195 aggravated assaults, 7,976 property crime, 1,229 burglaries, 5,503 larcenies/thefts, 1,244 car (all motor vhc) thefts, 25 arsons. --> One the average, a Berkeley resident has a 3/1000 chance per year of being robbed (and 42.1% (USA average) of robberies are done with firearms). --> If one lives 10 years in Berkeley, one has a 1.4% chance of being robbed at gunpoint.
  • Robberies worldwide: World average is 1/1000, US has 1.4/1000, Canada 0.8/1000, Switzerland 0.3/1000
  • UCPD , UCPD crime alerts

    "Housing in the Bay Area:"

    Since the 60's, has increased ~25-30 times. Salaries 5x, Bay Area population 5x.

    "Air requirements:"

  • ISS: ~1 kg (~1 cubic meter) of air/day... per person?
  • Scuba diver: ~20 liters/min (higher requirements, as it is not recycled at all)

    Exchange rates

  • Daily historical data
  • XE.com: +free 5mins data charts (JAVA applet)
  • x-rates.com
  • Swiss franc loosing ground to Euro because of "Carry Trade": IHT article. Normally, a currency whose Central Bank has lower interest rate should gain with respect to other currencies.
  • My "Carry trade" explanation: some financial institutions borrow lots of CHF (at 2.75%) in Switzerland, and buy Euros (which they lend in the Eurozone at 4%) with them. So the Euro rises with respect to CHF (or CHF shrinks with respect to Euro). Yearly gain in Euros is: (0.04-0.0275)*X_CHF*CHF2Euro. Yearly gain in CHF is: X_CHF*(0.04*CHF2Euro*Euro2CHF-0.0275). ... So, somebody who lives in the Eurozone makes 1.25% of his capital a year, and one who lives in CH a bit less (due to having to convert money twice, once in each direction -- loss of perhaps ~8% of 1.25%). It seems less complicated to leave money at bank, although being in debt might offer tax advantages...
  • Exchange rates: forecast

    Tsiolkovsky Rocket Equation

    deltaV = Ve ln(Mi/Mf)
    For a payload (1+x) times heavier, the available deltaV is reduced by Ve ln(1+x), or about (x Ve) for x << 1. A rocket using LOX/LH2 (like the Shuttle) (ISP = 455 s or Ve=~4.5 km/s), loses about ~.45 km/s in deltaV for x=0.1, or 3.2 km/s for x=2....

    Inflation rates:

    An inflation rate of 7.2% means a douling of prices every 10 years. A rate of 3% (EU max.) means prices are 34% higher every 10 years (takes 23.5 years for prices to double). At the end of 2006, Switzerland had an inflation rate (increase in consumer prices) of 1.2% (0.5% in 2003!), the USA 2.5%, Canada 2%, UK 3%, France 1.5%. (From indexmundi.com )

    Gravity gradient in Low Earth Orbit:

    Two masses m1 and m2, connected by a rigid tube of length d. The whole apparatus is at distance r from Earth's center. A torque due to the gravity gradient will make the apparatus align with the gravity gradient (unless it was perfectly horizontal, but this is an unstable situation, as can be seen from the formulae to follow). The torque (moment of force) is: M = GM/r^2 d sin(theta)/2 [ m1/( 1-d/2/r*cos(theta) ) - m2/( 1+d/2/r*cos(theta) )] . (theta is angle between axis and vertical, and m1 is the lower od the two masses). If m1=m2=m, this exact expression can be simplified and approximated by M~=GM/r^3 md^2 sin(2*theta)/2 . In LEO (r=6370km + 600km), and for m1=m2=m=100kg and d=10m, one has a maximum torque (theta=45 degrees) of 3.6 10^-7 [N.m].

    Country information:

    www.indexmundi.com

    Swiss Mortgage interest rates (+ other stuff):

  • UBS
  • cash.ch

  • Car stuff:

  • Air drag: Roll friction is ~constant with speed, air drag goes as v^2. Both are equal around 50 km/h.
  • According to xxx (forgot reference!), "aggressive driving" reduces car mileage by up to 33% on highways, and up to 5% in cities.
  • ZIPCAR!

  • Global security:

  • GlobalSecurity.org:

  • AVS/AHV:

  • Memento
  • Basically, I get from 1105 to 2210 CHF/month if I've contributed every year. Otherwise, reduce by 1/44th for every missed year.
  • The present value of all AVS/AHV payouts can be computed as follows: PV = Sum from j=0 to n2-1 of A/(1+i)^(n1+j) = A q^n1 Sum(q, from 0 to n2-1) = A (q^n1 - q^(n1+n2))/(1-q), where n1=number of years to retirement age (65), n2=number of years I'll live after retirement age, A = annual payout (from 1105 to 2210 CHF/months times 12), i=swiss inflation rate (supposed constant), q=1/(1+i)
  • In 2007: PV/A=8.31 for i=3%, and PV/A=19.3 for i=1%. Taking that last, the PV of a the minimal 1105 CHF/month payout is CHF 256000.-
  • If I miss a year, the loss is 1/44th of that amount: PVloss = 5818.-: I'd better pay, if the cost is less than that...
  • Can I participate from abroad? From here and here, it looks like I can from non-EU countries, although I would have to pay 9.8% of my salary...? (Current minimum is 824.-) Alas, from my infoset#2, it looks like if I miss a year, then I'm toast until I return to CH...
  • 2007/11/27: assuming I make 80K CHF a year on the average, paying (and not loosing a year) will be worth while if Swiss inflation rate is below about 2%. If I make 150K CHF a year on the average, paying will be worth while only if the average Swiss inflation rate is below 0.5%... (see program avs.pro) Also, for the above calculations, I haven't considered the fact that investing that money somewhere (some financial institutions, stocks, ...) will probably be more advantageous...
  • 2007/11/27: 9.8% x RAMD x exp(r t), where t=30 years, and r=5% yields 35136 for RAMD=80K and 65880 for RAMD=150 K. I am really better off investing this money (if I have it), instead of giving it to the AVS facultatif... (basically same story for RAMD=50K)

  • Latin:

  • Later Latin Society : go to "verb conjugation list" link -> "memento" ("souviens-toi") is the imperative form of the verb memini, meminisse (to remember), and has been transformed into a noun in English and French (amongst other languages). There is no ground for its plural form to be "mementi", except if you're italian, I guess.
  • In vero libertas. In veritate libertas. In veritate scientiaque libertas.

  • Integrals:

  • Wolfram Integrator

  • Space Launches:

  • From Wikipedia: 2007

  • Credit Cards in CH:

  • article TSR 2006
  • Tableau (2 pages) (fin 2006)

  • Comptes libre-passage en Suisse:

  • www.mon2epillier.ch
  • Compte libre-passage UBS

  • Swiss German:

  • Swiss German

  • Bank rates

  • bankrate.com

  • Bullet firing

  • Into water: basically, below a 8 feet, all bullets from normal rifles/pistols/.50AP have lost their lethality (loss of speed or disintegration), even if fired vertically. There are some underwater guns which are lethal up to 17m.
  • In Vacuo: Yes, as both the gun powder and primer cap detonated by the hammer carry their own fuel and oxidant.

  • Nuclear stuff

  • A 1 GWt reactor (operating with less than 20% enriched U) generates about 1Kg Pu/day --> one nuke every 6 days. (Reference forgotten...) Experimental/research reactors have much less (CIRUS in India (40MW) was supplied by Canada, and nukes where made with US heavy water).
  • The 12 large pieces of the Cosmo954 satellite which crashed into northern Canada in 1978 emitted about 110 rems/hr of combined radiation. (I.e. a few hours of exposition is enough to kill.)

  • Flash point, fire point, autoignition of gases:

  • Look at Wikipedia for details.
  • Flash point: lowest temperature where vapor pressure high enough for the gas to be flammable. Gasoline/diesel/jet fuel have a flash point above <-40C / >62C / >38C. and autoignition temperatures of 246C/210C/210C (numbers can be highly variable).
  • Fire point (larger than flash point): temperature where combustion goes on for at least 5 seconds, even if igition source is removed.
  • Autoignition temperature: self-explanatory (there is a nice equation for that one...). Paper has an autoignition temperature of 451F (233C).

    In case of a spill, diesel has a harder time burning than gasoline...


  • [Space]flight

  • NASA sounding rocket handbook: here.
  • Rocket: Black Brant
  • A nice web page on Hydrazine: astroprof, Mars Society page (actually plagiarized from former, looks like)
  • Manned spaceflight: Spacefacts.de
  • Encyclopedia Astronautica
  • Le grand Saut ; profile1 and profile2 by PSH (thegreatjump.pro)
  • Hyper-velocity impacts, Impact depth, Debris or Whipple Shielding

  • RADAR

  • RADAR equation: Pd = Pt G σ / (4 π)^2 / R^4
  • I.e radar range goes as square root of Pt, 4th root of σ ...
  • I read somewhere on the web that the A-50 Mainstay can detect (track?) a σ = 3 m^2 fighter at up to about 240 km.
  • F-22 Raptor has σ = 0.01 m^2 or so (about same as a bird) (i.e. radar range is 4.16 times less)

  • Atmosphere

  • Atmosheric escape rule of thumb: from here: If Vavg is larger than 0.2xVescape, then more than 1/2 of that type of gas will be gone after a billion years. Otherwise, more than 1/2 will remain after a billion years.

  • Axis And Allies

  • My TripleA stuff

  • Geneva Convention, Universal Declaration of Human Rights

  • Geneva Convention
  • Universal Declaration of Human Rights

  • Sayings:

  • "(Con)queror, ergo sum" (I complain , therefore I am, ~1990, latin version ~2006)
  • "Vexo (offendo), ergo sum" (I annoy , therefore I am, ~1990, latin version: ~2006)
  • "Principles are for those who can afford them" (~2000?)
  • "In vero libertas" or "In veritate libertas" (2010)

  • Why can't the Space Shuttle on an HST mission reach the ISS in case of emergency:

  • HST orbit: inclination 28.5 deg, 563 to 568 km altitude (about 7.534 km/s)
  • ISS orbit: inclination 51.64 deg, 350 to 362 km altitude (or even bigger variations) (about 7.65 km/s)
  • From Eq. 3.68 of this excellent website: DeltaV = sqrt( Vi^2 + Vf^2 -2*Vi*Vf*cos(theta) ), one can determine that the DeltaV required to move from one orbit to the other is 3.05 km/s. Space Shuttle has only 0.7 km/s...

  • SPACE and ASTRONOMY:

  • Spooky images from space

  • NEW SCIENTIST LINKS:

    (started on 2008/12/15)
  • Greeks had it all: clocks, robots, computers...: here
  • Spacesuit gallery (mostly US)
  • 13 things that do not make sense

  • Earth:

  • Richter 9 = 2x10^18 J. The Richter scale is log10, in units of the largest horizontal amplitude recorded. Energy goes as this amplitude to the 1.5 power. I.e. from 9 to 10 on the RIchter scale means 30 times more energy.