Archives February 2013

A person possesses two types of courage, one is physical and other is mental. Physical courage encourages the man to do works of risk like rocket manufacturing, launching satellites. It encourages man to discover the other planets of the universe and all types of laborious works. Moral or mental courage is found in man only. It enables man to select right or wrong and to act according to his will. As moral courage is a rare virtue. By help of this moral courage he selects the right path, may it be opposite to public opinion. He may have to face many troubles for the right path he has selected. In comparison to physical courage, moral courage is far superior. A man with a moral courage always does right under all circumstances. For the development of the society they may have to face criticism and opposition but he never bows to more...

It may not be the most eye-catching of names, but the superheterodyne receiver vastly improved radio technology in the early twentieth century by filtering out unwanted radio signals. The "superhet," as it is commonly called, is the invention of Edwin Howard Armstrong (1890-1954). While working on ways to amplify radio signals during World War I, he hit upon a cunning idea. An incoming radio signal is mixed with an internal signal generated by the receiver (known as a local oscillator). The two signals are multiplied together. This creates two new signals: One is the sum of the two originals, and one is the difference. So, if you have an incoming radio frequency at 5 MHz and a local oscillator at 4 MHz, signals will be seen at 9 MHz and 1 MHz, This is known as heterodyning. A filter can be used to remove any signal that does not fit more...

Hybrid vehicles have two different types of engines running in parallel—usually a gasoline or diesel engine to provide most of the motive force and an electric motor, powered by batteries, for additional assistance. The main advantages of hybrids are a reduction in carbon dioxide emissions and increased fuel efficiency due to the use of regenerative braking to recharge the battery (these batteries are sometimes referred to as onboard rechargeable energy storage systems). Fuel can also be saved by switching off the gasoline or diesel engine when coasting or stationary in traffic. The major breakthrough was made by Victor Wouk (1919-2005), the brother of the novelist Herman Wouk. Victor, an electrical engineer, was spurred into action by the Federal Clean Car Incentive Program of 1970. After founding a company called Petro-Electric Motors Ltd. with a chemist friend, Charles Rosen, in 1974 they adapted a Buick Skylark as a gasoline/electric hybrid that more...

“... next to agriculture, [shelter] is the most necessary to man. One must eat, one must have shelter." Philip Johnson, architect The earliest evidence for built shelter appears to have been constructed by Homo heidelbergensis, who lived in Europe between around 800,000 B.C.E. and 200,000 B.C.E. Anthropologists are uncertain whether these were ancestors of Homo sapiens (humans) or Homo neanderthalensis (Neanderthals) or both. At the French site of Terra Amata, which dates back around 400,000 years, archeologists have found what they believe to be the foundations of large oval huts. One of these shows evidence of fire in a hearth, although other archeologists postulate that natural processes could be responsible. Archeology on sites from hundreds of thousands of years ago is complicated. Claims of the discovery of built shelters in Japan from more than 500,000 years ago were discredited in 2000. In fact, all evidence for humans in Japan before 35,000 more...

Modern   meteorology   depends   hugely   on radiosondes, and hundreds of these balloon-borne instrument packages are released daily from weather stations all over the world. The sonde collects data up to a height of 18 miles (30 km), while being tracked in position using radar. The real-time data is continuously transmitted back to Earth by radio and the position of the sonde as time passes indicates the wind speed. Rising at the rate of about 0.2 miles (0.3 km) per minute, the flight usually takes about two hours. Silk weather balloons were first used to collect data in 1892 by the French scientist Gustave Hermite. In 1901 these were replaced by sealed rubber balloons. These burst when they reached a height of 12 miles (20 km), and the instrument package parachuted to the ground. The rest was left somewhat to chance because the flight records were picked up more...

Gyrocompasses have two great advantages over magnetic needle compasses: They point to the spin pole of Earth as opposed to the magnetic pole; and they are completely unaffected by the ferrous metal of a ship's hull or the magnetic fields produced by electrical currents running through nearby wires. Their main component is a motorized, fast-spinning, damped, gimballed wheel. When this wheel is not spinning exactly in the plane containing Earth's spin axis, an interaction between the angular momentum of the wheel and the angular momentum of Earth produces a restoring torque that pushes the wheel back into the true north-south orientation. A ship's gyrocompass is mounted in a complex set of gimbals that isolate the instrument from the ever- present pitching, yawing, and rolling. Aircraft gyrocompasses are even more complicated due to the higher velocity of the plane and the speedy changes in altitude during takeoff and landing. German scientist more...

"Gould [asked to use] the walkie-talkie idea... and he gave Dick Tracy that two-way wristwatch" Alfred J. Gross Walkie-talkies are the portable two-way radios that paved the way for mobile phones by showing the public the joys of talking to faraway people while walking around. In World War II they allowed troops to communicate and, since then, the police, the coast guard, and even children playing games have used them to relay information. Their exact origins are rather hazy though. Once radios had been invented, the next big thing was making them smaller and more portable and there is much disagreement over exactly when a two-way radio became a walkie-talkie, In 1937 a man called Don Hings, born in England and raised in Canada, built a waterproof two-way field radio. This radio weighed almost 12 pounds (5.5 kg) and was about the size of a toaster, but was definitely portable more...

India is a land of holy cities. Most of the important places of pilgrimage in India are located along the banks of the great rivers like the Ganga, Brahmputra, Godavari and Kaveri. Bathing in these rivers is considered a meritorious act. With the expansion of public transportation in the 20th century, it has become now easier for the people to visit these spots to partake of the divine. In fact, in India pilgrimage is the preferred form of tourism, which may be called religious tourism. The most significant religious place is Varanasi, which is also known as Kashi in south eastern Uttar Pradesh on the north bank of the Ganga, it is sacred to Hindus, Buddhist and Jains. They flock to the ghats or steps, leading from temples down to the banks of the sacred Ganga in their search for an auspicious site for death, cremation or immersion of ashes. more...

The game of cricket started in England first, but now it is played all over the globe and is very popular.  The game became very popular by the 18th century and a London club was formed in 1700. The Hambledon Club started in 1750 and at its ground, at Broachalf Penny Down, country cricket originated. Thomas Lord started a ground in Dorest Square in 1787 which was moved to St. John's Wood in 1814, and became the headquarters of the Marylebone Cricket  Club (M.C.C.), the ruling authority of the game. Gentlemen vs. Players, Oxford vs. Cambridge, and Eton vs. Harrow matches started about this time, and cricket took its present form. Cricket has achieved great popularity as can be seen from the jampacked stadia all over the world. There is always a clamour for tickets and yet many do not get any chance to enter. The game is played mainly more...

The deterioration of the environment by natural or human forces is known as environmental degradation. Natural happenings like heavy rain, floods, storms, earthquakes, volcanoes etc. are not under human control and they play havoc with environment time to time by making the land unfit for cultivation. Here man is helpless. He can do nothing except to see the havoc. But when man himself plays a vital role in degrading the environment in which he lives, then the problem becomes more serious. Needless to say that environmental degradation is one of the major global issues. The overuse of resources be it land or water and the industrialization process are the major causes of this phenomenon. Man has been felling the tress for his various purposes. He never minds if this process goes on without check it will lead to soil erosion, floods, silting of irrigation canals and cultivated lands, which finally more...