Tunnelling Effect

In quantum mechanics, quantum tunnelling (or the tunnel effect) is a nanoscopic phenomenon in which a particle violates the principles of classical mechanics by penetrating a potential barrier or impedance higher than the kinetic energy of the particle.^[1] A barrier, in terms of quantum tunnelling, may be a form of energy state analogous to a "hill" or incline in classical mechanics, which classically suggests that passage through or over such a barrier would be impossible without sufficient energy.
On the quantum scale, objects exhibit wave-like behaviour; in quantum theory, quanta moving against a potential energy "hill" can be described by their wave-function, which represents the probability amplitude of finding that particle in a certain location at either side of the "hill". If this function describes the particle as being on the other side of the "hill", then there is the probability that it has moved through, rather than over it, and has thus "tunnelled".

By 1928, George Gamow had solved the theory of the alpha decay of a nucleus via tunnelling. Classically, the particle is confined to the nucleus because of the high energy requirement to escape the very strong potential. Under this system, it takes an enormous amount of energy to pull apart the nucleus. In quantum mechanics, however, there is a probability the particle can tunnel through the potential and escape. Gamow solved a model potential for the nucleus and derived a relationship between the half-life of the particle and the energy of the emission.

Alpha decay via tunnelling was also solved concurrently by Ronald Gurney and Edward Condon. Shortly thereafter, both groups considered whether particles could also tunnel into the nucleus.

After attending a seminar by Gamow, Max Born recognized the generality of quantum-mechanical tunnelling. He realized that the tunnelling phenomenon was not restricted to nuclear physics, but was a general result of quantum mechanics that applies to many different systems. Today the theory of tunnelling is even applied to the early cosmology of the universe.

Quantum tunnelling was later applied to other situations, such as the cold emission of electrons, and perhaps most importantly semiconductor and superconductor physics. Phenomena such as field emission, important to flash memory, are explained by quantum tunnelling. Tunnelling is a source of major current leakage in Very-large-scale integration (VLSI) electronics, and results in the substantial power drain and heating effects that plague high-speed and mobile technology.

Another major application is in electron-tunnelling microscopes (see scanning tunnelling microscope) which can resolve objects that are too small to see using conventional microscopes. Electron tunnelling microscopes overcome the limiting effects of conventional microscopes (optical aberrations, wavelength limitations) by scanning the surface of an object with tunnelling electrons.

Quantum tunnelling has been shown to be a mechanism used by enzymes to enhance reaction rates. It has been demonstrated that enzymes use tunnelling to transfer both electrons and nuclei such as hydrogen and deuterium. It has even been shown, in the enzyme glucose oxidase, that oxygen nuclei can tunnel under physiological conditions

Line Follower ROBOT

This Robot use two motors control rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of comparator, LM324 is low logic and the other the output is high.
Microcontrollor AT89C2051 and H-Bridge driver L293D were used to control direction and speed of motor.

CIRCUIT DIAGRAM OF INFRARED SENSORS AND COMPARATORS

Position of sensors, left hand side is side view and right hand side is top view.
Software
Software for write to AT89C2051 is robot1.hex ,which was written by C-language ,the source code is robot1.ccompiled by using MC51 in TINY model with my start up code robot.asm .

NANOTECHNOLOGY improves battery life

Researchers at the Shenyang National Laboratory for Materials Science in China have been investigating how to improve the kind of rechargeable batteries that are used in mobile phones, MP3 players, personal digital assistants and laptop computers.

They found that after 20 cycles of the semi-cell experiments, the sugar-coated Si-CNT composite material achieved a discharge capacity of 727 mAh per g. In contrast, the charge capacity of the simple sugar-coated particles had dropped to 363 mAh per g.

Hui-Ming Cheng and colleagues have turned to carbon nanotubes (CNTs) to help them use silicon (Si) as the battery anode but avoid the material's usual problem of large volume change during alloying and de-alloying that can lead to faster capacity loss.

Li-Ion batteries suffer from degradation, especially when they get too hot or too cold, and eventually lose the capacity to be fully recharged. The problem of the slow degradation of Li-Ion batteries is usually due to the formation of a solid electrolyte interphase film that increases the batteries' internal resistance and prevents a full recharge.

The researchers grew carbon nanotubes on the surface of tiny particles of silicon using a technique known as chemical vapour deposition, in which a carbon-containing vapour decomposes and then condenses on the surface of the silicon particles forming the nanoscopic tubes.

They then coated these particles with carbon released from sugar at a high temperature in a vacuum. A separate batch of silicon particles produced using sugar but without the CNTs was also prepared.

With the Si-CNT anode material to hand, the team then investigated how well it functioned in a prototype Li-Ion battery and compared the results with the material formed from sugar-coated silicon particles.

The growth of carbon nanotubes on silicon suppresses the structure destruction of the composite during charge cycling, resulting in the improvement of cyclability, according to the researchers.

Researchers demonstrate ‘AVALANCHE EFFECT’ in solar cells

Proof that the ‘avalanche effect’ by electrons occurs in specific, very small semi conducting crystals could pave the way for cheap high-output solar cells.

Researchers at TU Delft and the FOM Foundation for Fundamental Research on Matter have discovered this phenomenon.

Solar cells provide opportunities for future large-scale electricity generation. However, there are currently significant limitations, such as the relatively low output of most solar cells (typically 15%) and high manufacturing costs.

One possible improvement could develop from a solar cell made of semiconducting nanocrystals which could lead to theoretical maximum output of 44%.

In conventional solar cells, one photon can release precisely one electron. The creation of these free electrons ensures that the solar cell works and can provide power.

The more electrons released, the higher the output of the solar cell.

In some semiconducting nanocrystals, however, one photon can release two or three electrons, hence the term 'avalanche effect'.

The avalanche effect was first measured by researchers at the Los Alamos National Laboratories in 2004. Since then, the scientific world has raised doubts about the value of these measurements. Does the avalanche effect really exist or not?

Within the Joint Solar Programme TU Delft’s Prof Laurens Siebbeles has now demonstrated that the avalanche effect does indeed occur in lead selenide (PbSe) nanocrystals.

It has been established, however, that the effect in this material is smaller than previously assumed. Siebbeles claims his results are more reliable than those of other scientists due to more careful and more detailed measurement using ultra-fast laser methods.

Siebbeles believes that this research paves the way for further unravelling the secrets of the avalanche effect.

INTEGRATED CIRCUITS

The first integrated circuit

In electronics the integrated circuits( also known as IC microcircuit,microchip etc.,) is a miniaturized circuit(consists of mainly semiconductor devices and also passive elements) that have been manufactured in the surface of thin substrate of semiconductor material. Now a days the integrated circuit devices are use all electronic devices like computer mobiles etc.There are many generations of this circuit. This was first invented by Jack kilby

for more information on generation refer the magazine

Engineering Quotes

Scientists investigate that which already is;
Engineers create that which has never been.
Albert Einstein

Engineers like to solve problems. If there are no problems handily available, they will create their own problems
Scott Adams

Scientists dream about doing great things. Engineers do them.
James A. Michener

Engineering is an activity other than purely manual and physical work which brings about the utilization of the materials and laws of nature for the good of humanity.
R. E. Hellmund

Engineering is the art of organizing and directing men and controlling the forces and materials of nature for the benefit of the human race.
Henry G. Stott

Inventing is the mixing of brains and materials. The more brains you use, the less materials you need.
Charles F. Kettering

In mathematics, you know where you are, but don't know where you might be. In physics, you don't know where you are, let alone where you might be.

-----------Come get inspired