pab_soledad

"Российская наука"

2010-01-04T19:13:39Z

Как правильно двигать "российскую науку"?
"Российскую науку" правильно двигать из России.

How to escape from the Armagedon

2009-09-29T00:18:06Z

Here, it comes.

First of all, there a lot of things you can do to prevent Armagedon (i.e. collision between the Earth and asteroid) to happen.

Below are my three kopeiki for that purpose.

1) As you all now, there is so-called Van Der Graaf generator, which creates high voltages (up to 10MV). Its maximum voltage have upper limit as breakdown of air. In space there is virtually no upper limit of that.
2) Some of asteroids (and dangerous one) consists of ferrum. That means you can charge them.
3) Solar generates not only photons of light, but also magnetic field as well.

Let's, for example, launch a sattelite which contains Van Der Graaf generator that charges asteroid.

B_solar = 1e-9 Tesla
C = R/k (k = 9*10^9 m/Ph)
Q = C*U = R*U/k
\delta X = a*t^2 / (2*m) = Q*V*B * (L/V)^2 / (2*m)
m -- mass of asteroid,
V -- velocity of asteroid
\delta X -- slope from 'direct' trajectory
L is distance from Earth (t = L/V)

Solving last equations on L, one gets: L = \sqrt { 2*m*V*\delta X / (B*R*U/k) }.

Lets demand \delta X = 100km = 10^5m, state m = 1^6 kg, V = 20 km/sec, R = 20 m, U = 1 MV.
Than L = 4.243e+13 m (pretty high).
But if we able to charge up to U = 1GV: L = 1.342e+12 m (near of 9 a.u.e.)
As there is (I hope) virtue no limit on U in vacuum, we can be able to prevent asteroid to collide to the Earth.

Thanks for attention (if one).

UPD: As sergepolar pointed out, there will be leakage of charge becuase of interacting with interplanetary medium.
Density of it near of 5 cm^{-3}. Lets assume we have R=10 m, V = 20 km/sec. Then leakage (current) I = pi*R**2*V*e. Its results in near of 10 microA (upper limit for that, assuming maximum efficienty but, in contrary, purely geometric cross section).

Некопирование файлов

2009-03-03T09:57:19Z

Как известно, копировать нехорошо -- копирасты придираются.

Поэтому публикую код для "некопирования" файла. Сейчас код работает только на Linux-like системах, можно адаптировать под другую.

Что делает код: перебирает случайные числа на предмет совпадения с файлом-образцом (то есть ищет файл среди случайных чисел).

--------- fuck_riaa.c ------------------
#include <stdio.h>
#include <stdlib.h>

int main (int argc, char **argv) {
    FILE *fin, *fout, *frand;
    unsigned char buffer[4096];
    unsigned char try, r;
    size_t readed;
    size_t i;

    fin = fopen( argv[1], "rb" );
    fout = fopen( argv[2], "wb" );
    frand = fopen( "/dev/urandom", "rb" );

    while( ! feof( fin ) ) {
        readed = fread( buffer, sizeof(buffer[0]), sizeof(buffer), fin );

        for ( i = 0; i < readed; i++ ) {
            r = buffer[i];
            while( try != r )
                fread( &try, 1, 1, frand );

            fwrite( &try, 1, 1, fout);
        }
    }

    fclose( fin     );
    fclose( fout    );
    fclose( frand );
}