Archives March 2013

A battery, sometimes called a cell, is a device that.' converts chemical energy into electrical energy. When two or more cells are joined together in such a way that the currents produced from each flow in the same direction, they are known as a battery of cells. There are two basic types of batteries: the primary, nonrechargeable battery, where the electricity stops when the chemicals are used up, and the secondary (or storage) battery, which can be recharged. The battery originated with Alessandro Volta (1745-1827) who, in 1799, invented the "voltaic pile," a pile of silver and zinc disks, separated by pieces of fabric saturated with sea water, that supplied an electric current when connected by a wire. His work was based on that of Luigi Galvani, who had noticed that a dead frog's legs twitched when they came into contact with two different types of metal. Each cell had more...

"Pacific island societies used an upside-down triangular sail, attached to a single vertical pole." Thomson Gale, The World of Invention (2006) For thousands of years sails have been used to harness the wind. By 3500 B.C.E., ancient Egyptian vessels were being blown up the Nile by the prevailing wind before returning under oars, and the Phoenicians pioneered the development of hardier vessels for sea voyages. However, these vessels used square-rigged sails to catch the wind and carry them along with it. In order to progress into the wind the sail must instead be used as an aerofoil to produce a lifting force perpendicular to the wind passing over it. The sail can be angled toward the wind and a component of the lift force generated gives forward thrust to the vessel, thus allowing modern craft to sail within a few degrees of the very direction from which the wind is more...

The first X-rays were produced by accident—a by- product emission from gas discharge tubes. The high voltage that is applied between the anode and cathode of the tube accelerates the ionized atoms of the gas into the metal cathode. This releases high- energy electrons, and when these electrons hit the glass wall of the tube. X-rays are emitted. X-ray tubes use exactly the same physical processes but here the cathode is specially shaped so that a parallel beam of electrons is emitted through a window. Metal targets produce both a continuum of X-rays and a line spectrum. These "K lines" are formed by outer shell electrons falling into the inner K-shell. Metals such as molybdenum, copper, cobalt, iron, chromium, and tungsten are used for the cathode, each producing a K line of a different wavelength. William Coolidge (1873-1975), an inventor and physicist working for General Electric in Schenectady, New York, more...

While many inventions are deemed "accidental discoveries," the air-cushioned sole was, in fact, the result of a real mishap rather than a metaphorical one. In 1945 the young Bavarian doctor Klaus Maertens had a skiing accident, and in order to speed up his recovery he devised a shock-absorbing shoe. Its sole has cushions of trapped air that constantly stimulate the muscles and tendons of the person wearing it. The principle of pressure and counter pressure mimics the effects of an elastic insole, thereby protecting the joints. Two years later, Maertens and a friend, engineer Dr. Herbert Funck, set up a company to sell the shoes. But while his innovation—marketed as orthopedic footwear—was well received by the medical world, it was not considered fashionable. That changed when Maertens and Funck placed ads in international trade magazines. Bill Griggs—a producer of army and working boots in Northamptonshire, England— spotted one of them more...

"If you succeed, you'll be a hero. if you fail, so what? You'll just go to work on a different project." Tom Stanley "motivating" the MOSFET team Some words, such as laser and radar, are so common that most of us are unaware of their humble origins as acronyms. Others, despite being worthy of recognition, have not made the leap to public fame; the MOSFET is definitely within this category. A MOSFET (metal oxide semiconductor field effect transistor) has no moving parts. We can roughly understand its form and function by thinking of a sandwich composed of three types of material, generally referred to by the letters N P N. If wires are connected to the two N components of our sandwich, the current does not flow. This is due to the different electrical properties of the P layer. How do we get the current to flow? Strangely we first more...

Surgeons using keyboards, joysticks, and the like can make movements that control advanced surgical robots—such as "Da Vinci"" and "Zeus®"—in the performance of long-distance, unassisted surgery. On September 7, 2001, Jacques Marescaux of the University of Strasbourg, France, and the IRCAD European Institute of Telesurgery, and Michael Gagner, chief of the Department of Laparoscopic Surgery at Mount Sinai Medical Center in New York, removed the gallbladder of a sixty-eight-year-old woman in Strasbourg, more than 3,700 miles (6,000 km) from the Surgeons. Other medical staff stood by in Strasbourg but did not have to intervene. "Operation Lindbergh," as it was dubbed, required a high-speed optical-fiber network to relay the information. The time lag between the surgeons initiating a movement and watching the result on their display was one eighth of one second. The operation was performed laparoscopically: a camera and instruments were inserted into the patient through small incisions. The operation more...

If by the grace of God I win a lottery. I will be full of joy. To offer my gratitude towards Him first of all I would visit a tern pie along with my family members to make an offering. I will not meet any visitor to congratulate me, because it is sure that they will definitely expect something from me in return. They will tell about their pathetic conditions and miseries of life on some pretext or the other. They will expect some financial assistance from me to meet their miseries of lives through the money I have by winning a lottery through their good wishes. My relatives, friends and well-wishers will be living in fool's paradise if they think that I shall be giving a grand feast to them-1 know an old saying that fools make a feast and wise man eat them, and I don't wish to more...

It is amazing, how advancing technology has influenced what would seem to be the simple task of selling apples in supermarkets. Not so long ago, the checkout cashier was expected to know the difference between apple varieties such as Granny Smith and Golden Delicious, and charge the customer accordingly. When, for various reasons, this became too arduous, each apple was provided with a little sticker (known as a P. L. U., or price look-up). But these were time-consuming and expensive to apply, and provided too little information. Further, if they were too sticky they were difficult to remove, and if they were not sticky enough they fell off. In 2002 the American laser expert Greg Drouillard offered a solution, patenting his idea of tattooing the skin of the apple with a laser-scannable barcode. The barcode would inform a computer, as to the type of apple, where it came from, when more...


"The four building blocks of the universe are fire, water, gravel, and vinyl." Dave Barry, author and humorist Since it was first made, polyvinyl chloride (PVC) has been one of the most widely used plastics. The molecule was first discovered by accident in the 1800s by two chemists, each of whom left flasks of chemicals out in the sun and noticed that a white solid formed in them. However, it was not until 1926 that Waldo Semon (1898-1999) made the crucial breakthrough. He blended this material with additives, known as plasticizers, so that a useful product was formed, and the plasticized PVC, often shortened to "vinyl," was born. Until this point, people had not seen any value in the product—in Semon's own words, "People thought of PVC as worthless back then. They'd throw it in the trash." The new plastic quickly became used for a myriad of different applications and more...


Archive


You need to login to perform this action.
You will be redirected in 3 sec spinner

Free
Videos