Archives January 2013

"It was effectively ironclad against bullets, and could at a pinch cross a thirty-foot trench..." H.G. Wells, The Land Ironclads, 1908 In the early 1900s, the stalemate of trench warfare sparked military powers to look for alternative methods of breaking through enemy lines. Before World War I, motorized vehicles were still uncommon, and the current designs were unsuitable for combat. It was the British military, in 1914, that created the first tanks. They included tracks to make moving over muddy terrain easy and were fitted with internal- combustion engine, bulletproof casing, and mounted, revolving machine guns. Surprisingly it was the navy rather than the army that oversaw the deployment of the new war vehicles during World War I. Before being put into service, the first tanks were demonstrated to two future British prime ministers— David Lloyd George and Winston Churchill. Amazed at the machines' ability to mow through barbed wire more...

Strike can be defined as the denial to do work by an organized group of workers, then they are said to have been gone on strike. The associations of the workers raise some demands before the management and stops working up to its fulfillment. There is not a common opinion of people regarding these strikes. Some are of the view that strikes should be declared illegal and should be stopped with iron hands. But some have other opinion about it. They say that they are the natural off springs of our industrial system. Before industrialization   workers were at the mercy of their masters but after industrialization unions of workers came into existence to safeguard the interests of the workers, in the previous days the worker had to compromise with dictates of his master, but same is not now. The realization of unity among workers gave way for the formation more...

To those few weeks spent on the highest point of my native land I owe many happy years of work...” C. T. R. Wilson, on receiving the Nobel Prize in 1927 In September 1894, Charles Thomson Rees Wilson (1869-1959) climbed to the summit of the Scottish mountain, Ben Nevis. He was so impressed by the effects of sunlight upon the clouds that he decided to try to reproduce them in his laboratory. His work was based on that done by John Aitken, the engineer who had created artificial clouds in a laboratory container. Aitken had found that if you put water vapor into a glass jar, a cloud would form if the air was unfiltered— that is, dusty. The water molecules in the air were treating the dust particles as tiny nucleation points onto which they could condense, forming a cloud. Air pressure inside the container could be reduced by more...

India is a country of different communities belonging to different religions. So almost every day we see a festival being celebrated with joy and fun. The festivals make our life colorful and charming. There are some religious festivals, some are based on seasons and some are of nations Importance. They are celebrated with great Joy and fun The Indian religious festivals are Diwali and Dussehra, Id-ul- Fitr and Id-ul Zuha, X'mas day and the New Year's day, Mahavir Jayanti, Buddha Jayanti, Guru Nanak's Birthday etc. Though these festivals are marked by different communities, yet they are celebrated by all without any ill-will and communal hatred. Festivals promote the feelings of communal harmony  Holi, Baisakhi and Basant are important seasonal festivals. Holi is a festival of colours. It marks the end of the winter season. Baisakhi is the seasonal festival of the Punjab. It is celebrated at the end of harvesting more...

Electronic paper has many of the properties of paper; thin, flexible, and readable from a wide angle, but it also has the distinct advantage of being reusable. In the 1970s Xerox PARC had developed a personal computer, and Nicholas K. Sheridon had the task of developing a display that improved on the then very dimly lit cathode ray displays. In 1974 Sheridon developed the Gyricon, which—although it was never used as a monitor because the PC project was dropped—formed the foundations of e-paper. The Gyricon, Greek for rotating image, consists of a thin, flexible sheet of plastic peppered with oil-filled wells containing small beads. Each bead, colored white on one half and a contrasting color (usually black) on the other, is charged with positive and negative ends that corresponded to the two colors. When an electrical current is applied to the Gyricon, the beads rotate in a predicted manner displaying more...

Pongal is the harvest festival of Tamil Nadu. It is celebrated for four days in the mid-January commencing from the last day of the Tamil month Margazhi. The sun, the earth and the cattle are worshipped by farmers as thanks giving for a Bounteous Harvest. People of Tamil Nadu took gay and enthusiastic with lots of hopes and aspirations. They clean their houses and decorate it with festoons before four or five days of festive occasion. They all try to complete these decorations on the eve of Pongal- ‘Bogi'. They decorate the earthen vessels of big sizes with kumkum and swastika. After the preparations are made, either the eldest or the youngest member of the family fills the pot with rice, water and some milk as per tradition. According to the belief associated with this festival, rice is cooked either in the courtyard or in the open fields instead of more...

If you can make the photons of a laser light that hits atoms have more energy than those that leave the atoms, then the atoms get colder. The trick is to tune the energy of a laser photon to a value that is slightly below that of the energy of an electronic transition in the atom. Due to the Doppler red-shift of the photons, those atoms moving toward the beam absorb more photons than those moving in the opposite direction. Emitted photons leave the atom in random directions, and the result is a general loss of momentum and kinetic energy. The atoms get colder because temperature is proportional to the kinetic energy. The atoms need to be at very low concentrations. The idea, was first suggested in 1975 by Theodore Hansch and Arthur Schawlow at Stanford University in California. Ten years later, Steven Chu of AT&T Bell Labs put it more...

"The first magnetic slurry coating on the first disk drive was poured... from a Dixie cup." Barry Rudolph, IBM vice president For most of the twentieth century, the primary medium for data entry, storage, and processing was the punched card. In the 1930s, IBM hired teacher and inventor Reynold B. Johnson (1906-1998) to develop the IBM 805 test-scoring machine to convert pencil marks on forms into punched cards. Twenty years later, Johnson led the team that developed the technology that made the vast majority of punched cards obsolete—the hard disk.      Unlike punched cards and magnetic tape, in which data must be accessed sequentially, hard disk drives provide access to all data almost simultaneously. Some computers in the late 1940s stored data on the outside of magnetic drums, but this left most of the internal space unused. Johnson and his team sought to store data on a stack of more...

“.. you don't have to think about it... you just wear it and it takes orders directly from your muscles.” Robert A. Heinlein, novelist The powered exoskeleton is a good case of life imitating art. Robert A. Heinlein's 1959 novel Starship Troopers described warriors in powered suits. The idea was used again in the Marvel Comic Iron Man, with a man inside a powerful homemade iron suit. The idea struck a chord, and General Electric took up the task of turning it into reality. By 1965 they had produced "Hardiman," the first powered exoskeleton. The idea behind the device was to produce a robot that reacted to the natural muscle movements of the wearer, It was designed to act like a "second skin," albeit one that weighed as much as a car. Hardiman was a 3/4-ton monster, designed to lift 1,500 pounds(680 kg). Unfortunately the team never managed to get more...

In 1923 Juan de la Cierva (1895-1936) pioneered the first autogyro. These machines appear superficially similar to helicopters, but with a single unpowered rotor. Early autogyros were less maneuverable than helicopters and were unable to take off or descend vertically. The invention of the autogyro predated the helicopter and so paved the way for vertical flight. Autogyro rotors are not powered, unlike those of a helicopter, and thus work in a similar way to spinning "helicopter" seed pods such as those of the box elder tree, Acer negundo. These seeds are aerodynamically shaped to spin as they fall, allowing the seed to disperse much further; autogyro rotors autorotate in the same way. The power or thrust of the autogyro comes from a powered propeller (or in later designs a jet engine) meaning that most do require some takeoff runway, but normally only tens of feet. As they can land in more...