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.