How come Andhra is left out of the mining loot story ? It is good for the nation if we learn to keep environmental and...
The UN environment report states that Ganga would disappear by 2030.There would be no need to train engineers or even Ganga...
A report published in the Journal of the Federation of American Societies for Experimental Biology suggests that babies of...
RESEARCHERS in the US have developed
an easy, risk-free method to find buried
landmines. All you have to do, they say,
is fire a special bullet into the ground
from a helicopter and the bullet will do
the rest. The 'special' bullet emits a
radar pulse as it grinds to a halt, thus
providing an effortless way to find not
only landmines but minerals, oil and
various other buried natural resources.
Ground-penetrating radar is potentially one of the most accurate ways of
locating landmines. A radar emits pulses
of radio waves into the ground, and
their reflections are analysed by a computer. But little radiation actually penetrates the soil - most is reflected back
by the ground because of the sudden
disparity in the density between the air
and the soil. This implies that such
ground radar systems need large power
supply to generate waves or pulses
strong enough to penetrate the ground.
This makes these systems bulky - a
major drawback in mine detection as
most of the minefields are located in
remote corners of the world.
To bypass these obstacles, electrical
engineers Thomas Engel and William
Normally from the University of
Missouri in Columbia, USA, with us $5
million in funding from the us army,
designed a bullet that emits a powerful
burst of radio waves once it is under the
ground. The duo's final aim is to design
a radar bullet that can be fired straight
down from a helicopter hovering some
100 metres (in) above the ground. The
bullet will produce a pulse of radio
waves as it pierces the ground, and the
reflections from any landmine within a
15-m radius will be detected by an
antennae mounted on the helicopter
hovering overhead. "You do not have to
be on the ground - stepping on mines
- to use it," says Engel. Once the mines
have been located, they can either be
destroyed or have their positions
marked accurately so they can be eliminated later. Of course, in case the bullet
hit a mine itself, it would explode.
The radar pulse is generated from
the bullet's kinetic energy by a process
known as magnetic flux compression.
Inside Engel and Normally's radar bullet
is a metal cylinder, surrounded by a
tightly-wound coil of wire. As the bullet
leaves the gun, a battery passes a current
through the coil, thus generating a magnetic field in the cylinder. When the bullet smashes into the ground, the abrupt
deceleration forces the cylinder out of
the coil. This sudden movement of the
metal cylinder through the magnetic
field induces a large pulse of current
in the coil. The coil then acts like an
antenna, converting the pulse into a
short burst of high-frequency radiation.
The light-weight system is portable,
and can be easily fitted to any helicopter.
In tests conducted so far, Engel has
found their 30-millimetre bullet emits
a four kilowatt radar pulse - much
more powerful than any other ground penetrating radar - from 20 centimetres down.