Category Physics

What is Fly-by-wire?

The term ‘Fly-by-wire’ is applied to automatic computer controlled operation of an aircraft. Instead of conventional mechanical controls operated manually by the pilot, this modern technology uses computers to control all the flight operations of an aircraft. It is extremely reliable, accurate and free from human errors. In this technology, electrical, electronic and computer systems fully replace conventional mechanical systems required for, say, turning the rudder or wing flaps of an aircraft. However, hydraulic or pneumatic systems required for, say, applying brakes to wheels, are only partially replaced. Continue reading “What is Fly-by-wire?”

What is Computer virus?

A computer virus is a self-replicating computer program or a segment of code that inserts copies of itself into other programs, thus infecting them. As a result, the original programs cannot run smoothly, thereby totally disrupting the functioning of the computer.

When an infected program is run on a computer, the hidden virus is activated and attempts to inject itself into additional programs. This process is analogous to the biological process of virus spreading from cell-to-cell within an organism. Very much like the biological virus, a single computer virus can spread to any number of compatible computer systems if provided with a pathway for infection.

The virus infects a system through sharing of infected diskette or through communication links, like local area networks or programs transmitted from distant systems.

Some of the commonly destructive manifestations of a computer virus include erasure of recorded data, rendering of entire device drives unreadable, interfering with communication and breaking the security cordon of the host computer. The virus may also create other problems such as display of unusual messages or plotting the text backward. Some of the well-known viruses are Pakistani Brain, Lehigh, Friday the 13th, Christmas and Bloody.

What are Composites?

Composites are materials made by combining two or more substances— one called the reinforcement and the other matrix— in such a way that the resultant product has better strength and property than the individual components. Weakness of one component is overcome by the strength of other component. Wood is the best example of a naturally occurring composite. It is composed of cellulose fibres as reinforcement in a lignin matrix. Similarly, in fibre-reinforced plastics glass fibre reinforcement is embedded in a plastic matrix to provide a much stronger product. The reinforcement, which could be a gas, particle or fibre, provides strength and stiffness to the composite. The matrix which could be any polymeric material, such as resin, or a metal or ceramic, holds the reinforcement and helps even distribution of the applied load within the composite. For best results the reinforcement and matrix should be compatible with each other. Normally, composites are made up of two dissimilar materials such as glass fibre and plastic but the same material can also be used both as the reinforcement and matrix, such as in ceramic-ceramic composites. Today, composites have become a part of our everyday life. They are also widely used in the aerospace industry as they provide an ideal combination of strength and light weight.

 

What is Catalytic converter?

Catalytic converter is a device, fitted onto the exhaust pipes of petrol-driven automobiles which help reduce the emission of environmentally damaging gases from the automobiles. The exhaust fumes of petrol-driven automobiles using unleaded petrol contain gases like the nitrogen oxides, carbon monoxide and benzene which are harmful to health when inhaled. The catalytic converter helps convert these gases into harmless carbon dioxide, steam and nitrogen. The converter is made up of grids of ceramics or metal coated with catalysts like platinum, vanadium or rhodium. When the exhaust gases pass over it, the catalyst brings about chemical reactions converting the harmful gases into harmless ones. The converter cannot be used in automobiles using leaded petrol because the lead which is used in the fuel as an anti-knocking agent can inactivate the catalyst and render the device useless.

What is CAT scan?

Cat scan (Computerized Axial Tomography), sometimes also referred as CT scan, is a technique of obtaining X-ray pictures of thin slices of the body without even putting a scalpel to it. The technique comes to help in locating or identifying tumours or blocked blood vessels in such soft tissues as the brain or in large organs such as the liver which cannot be photographed by the usual X-ray techniques.

CAT scanning is a modification of the usual X-ray technique. In CAT, the part of the body to be scanned is placed inside a ring. The ring has an X-ray gun at one side and a detector on the opposite side. The X-ray beam from the gun is received by the detector after passing through the body.

 

Continue reading “What is CAT scan?”

What is CAD/CAM?

CAD and CAM are abbreviations for ‘Computer Aided Design’ and ‘Computer Aided Manufacture’ respectively. Both are basically computer programs — sets of instructions —used to create drawings or to assist in manufacture of goods. Through a CAD program rough sketches are initially made on a computer screen by using a light pen or a mouse, which can further be finalized in exact details. The final drawings can thereafter be stored in computer memory in entirety or in parts for future use. Alterations or updating can subsequently be easily made in the final drawings. CAD programs are sometimes made for specific purposes such as designing printed circuit boards and computer chips. A CAM program, on the other hand, is used in the manufacture of goods in industries. For instance, computer-driven lathes, drills, welding machine or robotically operated production lines can be employed in factories to speedily manufacture a wide range of precision produced goods.