09 July 2009

Hearing aid

The invention: Miniaturized electronic amplifier worn inside the ears of hearing-impaired persons. The organization behind the invention: Bell Labs, the research and development arm of the American Telephone and Telegraph Company Trapped in Silence Until the middle of the twentieth century, people who experienced hearing loss had little hope of being able to hear sounds without the use of large, awkward, heavy appliances. For many years, the only hearing aids available were devices known as ear trumpets. The ear trumpet tried to compensate for hearing loss by increasing the number of sound waves funneled into the ear canal. A wide, bell-like mouth similar to the bell of a musical trumpet narrowed to a tube that the user placed in his or her ear. Ear trumpets helped a little, but they could not truly increase the volume of the sounds heard. Beginning in the nineteenth century, inventors tried to develop electrical devices that would serve as hearing aids. The telephone was actually a by-product of Alexander Graham Bell’s efforts to make a hearing aid. Following the invention of the telephone, electrical engineers designed hearing aids that employed telephone technology, but those hearing aids were only a slight improvement over the old ear trumpets. They required large, heavy battery packs and used a carbon microphone similar to the receiver in a telephone. More sensitive than purely physical devices such as the ear trumpet, they could transmit a wider range of sounds but could not amplify them as effectively as electronic hearing aids now do. Transistors Make Miniaturization Possible Two types of hearing aids exist: body-worn and head-worn. Body-worn hearing aids permit the widest range of sounds to be heard, but because of the devices’ larger size, many hearing impaired persons do not like to wear them. Head-worn hearing aids, especially those worn completely in the ear, are much less conspicuous. In addition to in-ear aids, the category of head-worn hearing aids includes both hearing aids mounted in eyeglass frames and those worn behind the ear. All hearing aids, whether head-worn or body-worn, consist of four parts: a microphone to pick up sounds, an amplifier, a receiver, and a power source. The microphone gathers sound waves and converts them to electrical signals; the amplifier boosts, or increases, those signals; and the receiver then converts the signals back into sound waves. In effect, the hearing aid is a miniature radio. After the receiver converts the signals back to sound waves, those waves are directed into the ear canal through an earpiece or ear mold. The ear mold generally is made of plastic and is custom fitted from an impression taken from the prospective user’s ear. Effective head-worn hearing aids could not be built until the electronic circuit was developed in the early 1950’s. The same invention— the transistor—that led to small portable radios and tape players allowed engineers to create miniaturized, inconspicuous hearing aids. Depending on the degree of amplification required, the amplifier in a hearing aid contains three or more transistors. Transistors first replaced vacuum tubes in devices such as radios and phonographs, and then engineers realized that they could be used in devices for the hearing-impaired. The research at Bell Labs that led to the invention of the transistor rose out of military research duringWorldWar II. The vacuum tubes used in, for example, radar installations to amplify the strength of electronic signals were big, were fragile because they were made of blown glass, and gave off high levels of heat when they were used. Transistors, however, made it possible to build solid-state, integrated circuits. These are made from crystals of metals such as germanium or arsenic alloys and therefore are much less fragile than glass. They are also extremely small (in fact, some integrated circuits are barely visible to the naked eye) and give off no heat during use. The number of transistors in a hearing aid varies depending upon the amount of amplification required. The first transistor is the most important for the listener in terms of the quality of sound heard. If the frequency response is set too high—that is, if the device is too sensitive—the listener will be bothered by distracting background noise. Theoretically, there is no limit on the amount of amplification that a hearing aid can be designed to provide, but there are practical limits. The higher the amplification, the more power is required to operate the hearing aid. This is why body-worn hearing aids can convey a wider range of sounds than head-worn devices can. It is the power source—not the electronic components—that is the limiting factor. A body-worn hearing aid includes a larger battery pack than can be used with a head-worn device. Indeed, despite advances in battery technology, the power requirements of a head-worn hearing aid are such that a 1.4-volt battery that could power a wristwatch for several years will last only a few days in a hearing aid. Consequences The invention of the electronic hearing aid made it possible for many hearing-impaired persons to participate in a hearing world. Prior to the invention of the hearing aid, hearing-impaired children often were unable to participate in routine school activities or function effectively in mainstream society. Instead of being able to live at home with their families and enjoy the same experiences that were available to other children their age, often they were forced to attend special schools operated by the state or by charities. Hearing-impaired people were singled out as being different and were limited in their choice of occupations. Although not every hearing-impaired person can be helped to hear with a hearing aid— particularly in cases of total hearing loss—the electronic hearing aid has ended restrictions for many hearing-impaired people. Hearingimpaired children are now included in public school classes, and hearing-impaired adults can now pursue occupations from which they were once excluded. Today, many deaf and hearing-impaired persons have chosen to live without the help of a hearing aid. They believe that they are not disabled but simply different, and they point out that their “disability” often allows them to appreciate and participate in life in unique and positive ways. For them, the use of hearing aids is a choice, not a necessity. For those who choose, hearing aids make it possible to participate in the hearing world.

Hard disk

The invention: A large-capacity, permanent magnetic storage device built into most personal computers. The people behind the invention: Alan Shugart (1930- ), an engineer who first developed the floppy disk Philip D. Estridge (1938?-1985), the director of IBM’s product development facility Thomas J. Watson, Jr. (1914-1993), the chief executive officer of IBM The Personal Oddity When the International Business Machines (IBM) Corporation introduced its first microcomputer, called simply the IBM PC (for “personal computer”), the occasion was less a dramatic invention than the confirmation of a trend begun some years before. A number of companies had introduced microcomputers before IBM; one of the best known at that time was Apple Corporation’s Apple II, for which software for business and scientific use was quickly developed. Nevertheless, the microcomputer was quite expensive and was often looked upon as an oddity, not as a useful tool. Under the leadership of Thomas J. Watson, Jr., IBM, which had previously focused on giant mainframe computers, decided to develop the PC. A design team headed by Philip D. Estridge was assembled in Boca Raton, Florida, and it quickly developed its first, pacesetting product. It is an irony of history that IBM anticipated selling only one hundred thousand or so of these machines, mostly to scientists and technically inclined hobbyists. Instead, IBM’s product sold exceedingly well, and its design parameters, as well as its operating system, became standards. The earliest microcomputers used a cassette recorder as a means of mass storage; a floppy disk drive capable of storing approximately 160 kilobytes of data was initially offered only as an option. While home hobbyists were accustomed to using a cassette recorder for storage purposes, such a system was far too slow and awkward for use in business and science. As a result, virtually every IBM PC sold was equipped with at least one 5.25-inch floppy disk drive. Memory Requirements All computers require memory of two sorts in order to carry out their tasks. One type of memory is main memory, or random access memory (RAM), which is used by the computer’s central processor to store data it is using while operating. The type of memory used for this function is built typically of silicon-based integrated circuits that have the advantage of speed (to allow the processor to fetch or store the data quickly), but the disadvantage of possibly losing or “forgetting” data when the electric current is turned off. Further, such memory generally is relatively expensive. To reduce costs, another type of memory—long-term storage memory, known also as “mass storage”—was developed. Mass storage devices include magnetic media (tape or disk drives) and optical media (such as the compact disc, read-only memory, or CDROM). While the speed with which data may be retrieved from or stored in such devices is rather slow compared to the central processor’s speed, a disk drive—the most common form of mass storage used in PCs—can store relatively large amounts of data quite inexpensively. Early floppy disk drives (so called because the magnetically treated material on which data are recorded is made of a very flexible plastic) held 160 kilobytes of data using only one side of the magnetically coated disk (about eighty pages of normal, doublespaced, typewritten information). Later developments increased storage capacities to 360 kilobytes by using both sides of the disk and later, with increasing technological ability, 1.44 megabytes (millions of bytes). In contrast, mainframe computers, which are typically connected to large and expensive tape drive storage systems, could store gigabytes (millions of megabytes) of information. While such capacities seem large, the needs of business and scientific users soon outstripped available space. Since even the mailing list of a small business or a scientist’s mathematical model of a chemical reaction easily could require greater storage potential than early PCs allowed, the need arose for a mass storage device that could accommodate very large files of data. The answer was the hard disk drive, also known as a “fixed disk drive,” reflecting the fact that the disk itself is not only rigid but also permanently installed inside the machine. In 1955, IBM had envisioned the notion of a fixed, hard magnetic disk as a means of storing computer data, and, under the direction of Alan Shugart in the 1960’s, the floppy disk was developed as well. As the engineers of IBM’s facility in Boca Raton refined the idea of the original PC to design the new IBM PC XT, it became clear that chief among the needs of users was the availability of large-capability storage devices. The decision was made to add a 10-megabyte hard disk drive to the PC. On March 8, 1983, less than two years after the introduction of its first PC, IBM introduced the PC XT. Like the original, it was an evolutionary design, not a revolutionary one. The inclusion of a hard disk drive, however, signaled that mass storage devices in personal computers had arrived. Consequences Above all else, any computer provides a means for storing, ordering, analyzing, and presenting information. If the personal computer is to become the information appliance some have suggested it will be, the ability to manipulate very large amounts of data will be of paramount concern. Hard disk technology was greeted enthusiastically in the marketplace, and the demand for hard drives has seen their numbers increase as their quality increases and their prices drop. It is easy to understand one reason for such eager acceptance: convenience. Floppy-bound computer users find themselves frequently changing (or “swapping”) their disks in order to allow programs to find the data they need. Moreover, there is a limit to how much data a single floppy disk can hold. The advantage of a hard drive is that it allows users to keep seemingly unlimited amounts of data and programs stored in their machines and readily available. Also, hard disk drives are capable of finding files and transferring their contents to the processor much more quickly than a floppy drive. A user may thus create exceedingly large files, keep them on hand at all times, and manipulate data more quickly than with a floppy. Finally, while a hard drive is a slow substitute for main memory, it allows users to enjoy the benefits of larger memories at significantly lower cost. The introduction of the PC XT with its 10-megabyte hard drive was a milestone in the development of the PC. Over the next two decades, the size of computer hard drives increased dramatically. By 2001, few personal computers were sold with hard drives with less than three gigabytes of storage capacity, and hard drives with more than thirty gigabytes were becoming the standard. Indeed, for less money than a PC XT cost in the mid-1980’s, one could buy a fully equipped computer with a hard drive holding sixty gigabytes—a storage capacity equivalent to six thousand 10-megabyte hard drives.

Gyrocompass

The invention: The first practical navigational device that enabled ships and submarines to stay on course without relying on the earth’s unreliable magnetic poles. The people behind the invention: Hermann Anschütz-Kaempfe (1872-1931), a German inventor and manufacturer Jean-Bernard-Léon Foucault (1819-1868), a French experimental physicist and inventor Elmer Ambrose Sperry (1860-1930), an American engineer and inventor From Toys to Tools A gyroscope consists of a rapidly spinning wheel mounted in a frame that enables the wheel to tilt freely in any direction. The amount of momentum allows the wheel to maintain its “attitude” even when the whole device is turned or rotated. These devices have been used to solve problems arising in such areas as sailing and navigation. For example, a gyroscope aboard a ship maintains its orientation even while the ship is rolling. Among other things, this allows the extent of the roll to be measured accurately. Moreover, the spin axis of a free gyroscope can be adjusted to point toward true north. It will (with some exceptions) stay that way despite changes in the direction of a vehicle in which it is mounted. Gyroscopic effects were employed in the design of various objects long before the theory behind them was formally known. A classic example is a child’s top, which balances, seemingly in defiance of gravity, as long as it continues to spin. Boomerangs and flying disks derive stability and accuracy from the spin imparted by the thrower. Likewise, the accuracy of rifles improved when barrels were manufactured with internal spiral grooves that caused the emerging bullet to spin. In 1852, the French inventor Jean-Bernard-Léon Foucault built the first gyroscope, a measuring device consisting of a rapidly spinning wheel mounted within concentric rings that allowed the wheel to move freely about two axes. This device, like the Foucault pendulum, was used to demonstrate the rotation of the earth around its axis, since the spinning wheel, which is not fixed, retains its orientation in space while the earth turns under it. The gyroscope had a related interesting property: As it continued to spin, the force of the earth’s rotation caused its axis to rotate gradually until it was oriented parallel to the earth’s axis, that is, in a north-south direction. It is this property that enables the gyroscope to be used as a compass. When Magnets Fail In 1904, Hermann Anschütz-Kaempfe, a German manufacturer working in the Kiel shipyards, became interested in the navigation problems of submarines used in exploration under the polar ice cap. By 1905, efficient working submarines were a reality, and it was evident to all major naval powers that submarines would play an increasingly important role in naval strategy. Submarine navigation posed problems, however, that could not be solved by instruments designed for surface vessels. Asubmarine needs to orient itself under water in three dimensions; it has no automatic horizon with respect to which it can level itself. Navigation by means of stars or landmarks is impossible when the submarine is submerged. Furthermore, in an enclosed metal hull containing machinery run by electricity, a magnetic compass is worthless. To a lesser extent, increasing use of metal, massive moving parts, and electrical equipment had also rendered the magnetic compass unreliable in conventional surface battleships. It made sense for Anschütz-Kaempfe to use the gyroscopic effect to design an instrument that would enable a ship to maintain its course while under water. Yet producing such a device would not be easy. First, it needed to be suspended in such a way that it was free to turn in any direction with as little mechanical resistance as possible. At the same time, it had to be able to resist the inevitable pitching and rolling of a vessel at sea. Finally, a continuous power supply was required to keep the gyroscopic wheels spinning at high speed. The original Anschütz-Kaempfe gyrocompass consisted of a pair of spinning wheels driven by an electric motor. The device was connected to a compass card visible to the ship’s navigator. Motor, gyroscope, and suspension system were mounted in a frame that allowed the apparatus to remain stable despite the pitch and roll of the ship. In 1906, the German navy installed a prototype of the Anschütz- Kaempfe gyrocompass on the battleship Undine and subjected it to exhaustive tests under simulated battle conditions, sailing the ship under forced draft and suddenly reversing the engines, changing the position of heavy turrets and other mechanisms, and firing heavy guns. In conditions under which a magnetic compass would have been worthless, the gyrocompass proved a satisfactory navigational tool, and the results were impressive enough to convince the German navy to undertake installation of gyrocompasses in submarines and heavy battleships, including the battleship Deutschland. Elmer Ambrose Sperry, a New York inventor intimately associated with pioneer electrical development, was independently working on a design for a gyroscopic compass at about the same time. In 1907, he patented a gyrocompass consisting of a single rotor mounted within two concentric shells, suspended by fine piano wire from a frame mounted on gimbals. The rotor of the Sperry compass operated in a vacuum, which enabled it to rotate more rapidly. The Sperry gyrocompass was in use on larger American battleships and submarines on the eve ofWorldWar I (1914-1918). Impact The ability to navigate submerged submarines was of critical strategic importance in World War I. Initially, the German navy had an advantage both in the number of submarines at its disposal and in their design and maneuverability. The German U-boat fleet declared all-out war on Allied shipping, and, although their efforts to blockade England and France were ultimately unsuccessful, the tremendous toll they inflicted helped maintain the German position and prolong the war. To a submarine fleet operating throughout the Atlantic and in the Caribbean, as well as in near-shore European waters, effective long-distance navigation was critical. Gyrocompasses were standard equipment on submarines and battleships and, increasingly, on larger commercial vessels during World War I, World War II (1939-1945), and the period between the wars. The devices also found their way into aircraft, rockets, and guided missiles. Although the compasses were made more accurate and easier to use, the fundamental design differed little from that invented by Anschütz-Kaempfe.

05 July 2009

Geothermal power

The invention: Energy generated from the earth’s natural hot springs. The people behind the invention: Prince Piero Ginori Conti (1865-1939), an Italian nobleman and industrialist Sir Charles Parsons (1854-1931), an English engineer B. C. McCabe, an American businessman Developing a Practical System The first successful use of geothermal energy was at Larderello in northern Italy. The Larderello geothermal field, located near the city of Pisa about 240 kilometers northwest of Rome, contains many hot springs and fumaroles (steam vents). In 1777, these springs were found to be rich in boron, and in 1818, Francesco de Larderel began extracting the useful mineral borax from them. Shortly after 1900, Prince Piero Ginori Conti, director of the Larderello borax works, conceived the idea of using the steam for power production. An experimental electrical power plant was constructed at Larderello in 1904 to provide electric power to the borax plant. After this initial experiment proved successful, a 250-kilowatt generating station was installed in 1913 and commercial power production began. As the Larderello field grew, additional geothermal sites throughout the region were prospected and tapped for power. Power production grew steadily until the 1940’s, when production reached 130 megawatts; however, the Larderello power plants were destroyed late inWorldWar II (1939-1945). After the war, the generating plants were rebuilt, and they were producing more than 400 megawatts by 1980. The Larderello power plants encountered many of the technical problems that were later to concern other geothermal facilities. For example, hydrogen sulfide in the steam was highly corrosive to copper, so the Larderello power plant used aluminum for electrical connections much more than did conventional power plants of the time. Also, the low pressure of the steam in early wells at Larderello presented problems. The first generators simply used steam to drive a generator and vented the spent steam into the atmosphere. Asystem of this sort, called a “noncondensing system,” is useful for small generators but not efficient to produce large amounts of power. Most steam engines derive power not only from the pressure of the steam but also from the vacuum created when the steam is condensed back to water. Geothermal systems that generate power from condensation, as well as direct steam pressure, are called “condensing systems.” Most large geothermal generators are of this type. Condensation of geothermal steam presents special problems not present in ordinary steam engines: There are other gases present that do not condense. Instead of a vacuum, condensation of steam contaminated with other gases would result in only a limited drop in pressure and, consequently, very low efficiency. Initially, the operators of Larderello tried to use the steam to heat boilers that would, in turn, generate pure steam. Eventually, a device was developed that removed most of the contaminating gases from the steam. Although later wells at Larderello and other geothermal fields produced steam at greater pressure, these engineering innovations improved the efficiency of any geothermal power plant. Expanding the Idea In 1913, the English engineer Sir Charles Parsons proposed drilling an extremely deep (12-kilometer) hole to tap the earth’s deep heat. Power from such a deep hole would not come from natural steam as at Larderello but would be generated by pumping fluid into the hole and generating steam (as hot as 500 degrees Celsius) at the bottom. In modern terms, Parsons proposed tapping “hot dryrock” geothermal energy. (No such plant has been commercially operated yet, but research is being actively pursued in several countries.) The first use of geothermal energy in the United States was for direct heating. In 1890, the municipal water company of Boise, Idaho, began supplying hot water from a geothermal well. Water was piped from the well to homes and businesses along appropriately namedWarm Springs Avenue. At its peak, the system served more than four hundred customers, but as cheap natural gas became available, the number declined. Although Larderello was the first successful geothermal electric power plant, the modern era of geothermal electric power began with the opening of the Geysers Geothermal Field in California. Early attempts began in the 1920’s, but it was not until 1955 that B. C. McCabe, a Los Angeles businessman, leased 14.6 square kilometers in the Geysers area and founded the Magma Power Company. The first 12.5-megawatt generator was installed at the Geysers in 1960, and production increased steadily from then on. The Geysers surpassed Larderello as the largest producing geothermal field in the 1970’s, and more than 1,000 megawatts were being generated by 1980. By the end of 1980, geothermal plants had been installed in thirteen countries, with a total capacity of almost 2,600 megawatts, and projects with a total capacity of more than 15,000 megawatts were being planned in more than twenty countries. Impact Geothermal power has many attractive features. Because the steam is naturally heated and under pressure, generating equipment can be simple, inexpensive, and quickly installed. Equipment and installation costs are offset by savings in fuel. It is economically practical to install small generators, a fact that makes geothermal plants attractive in remote or underdeveloped areas. Most important to a world faced with a variety of technical and environmental problems connected with fossil fuels, geothermal power does not deplete fossil fuel reserves, produces little pollution, and contributes little to the greenhouse effect. Despite its attractive features, geothermal power has some limitations. Geologic settings suitable for easy geothermal power production are rare; there must be a hot rock or magma body close to the surface. Although it is technically possible to pump water from an external source into a geothermal well to generate steam, most geothermal sites require a plentiful supply of natural underground water that can be tapped as a source of steam. In contrast, fossil-fuel generating plants can be at any convenient location.

Genetically engineered insulin

The invention: Artificially manufactured human insulin (Humulin) as a medication for people suffering from diabetes. The people behind the invention: Irving S. Johnson (1925- ), an American zoologist who was vice president of research at Eli Lilly Research Laboratories Ronald E. Chance (1934- ), an American biochemist at Eli Lilly Research Laboratories What Is Diabetes? Carbohydrates (sugars and related chemicals) are the main food and energy source for humans. In wealthy countries such as the United States, more than 50 percent of the food people eat is made up of carbohydrates, while in poorer countries the carbohydrate content of diets is higher, from 70 to 90 percent. Normally, most carbohydrates that a person eats are used (or metabolized) quickly to produce energy. Carbohydrates not needed for energy are either converted to fat or stored as a glucose polymer called “glycogen.” Most adult humans carry about a pound of body glycogen; this substance is broken down to produce energy when it is needed. Certain diseases prevent the proper metabolism and storage of carbohydrates. The most common of these diseases is diabetes mellitus, usually called simply “diabetes.” It is found in more than seventy million people worldwide. Diabetic people cannot produce or use enough insulin, a hormone secreted by the pancreas. When their condition is not treated, the eyes may deteriorate to the point of blindness. The kidneys may stop working properly, blood vessels may be damaged, and the person may fall into a coma and die. In fact, diabetes is the third most common killer in the United States. Most of the problems surrounding diabetes are caused by high levels of glucose in the blood. Cataracts often form in diabetics, as excess glucose is deposited in the lens of the eye. Important symptoms of diabetes include constant thirst, excessive urination, and large amounts of sugar in the blood and in the urine. The glucose tolerance test (GTT) is the best way to find out whether a person is suffering from diabetes. People given a GTT are first told to fast overnight. In the morning their blood glucose level is measured; then they are asked to drink about a fourth of a pound of glucose dissolved in water. During the next four to six hours, the blood glucose level is measured repeatedly. In nondiabetics, glucose levels do not rise above a certain amount during a GTT, and the level drops quickly as the glucose is assimilated by the body. In diabetics, the blood glucose levels rise much higher and do not drop as quickly. The extra glucose then shows up in the urine. Treating Diabetes Until the 1920’s, diabetes could be controlled only through a diet very low in carbohydrates, and this treatment was not always successful. Then Sir Frederick G. Banting and Charles H. Best found a way to prepare purified insulin from animal pancreases and gave it to patients. This gave diabetics their first chance to live a fairly normal life. Banting and his coworkers won the 1923 Nobel Prize in Physiology or Medicine for their work. The usual treatment for diabetics became regular shots of insulin. Drug companies took the insulin from the pancreases of cattle and pigs slaughtered by the meat-packing industry. Unfortunately, animal insulin has two disadvantages. First, about 5 percent of diabetics are allergic to it and can have severe reactions. Second, the world supply of animal pancreases goes up and down depending on how much meat is being bought. Between 1970 and 1975, the supply of insulin fell sharply as people began to eat less red meat, yet the numbers of diabetics continued to increase. So researchers began to look for a better way to supply insulin. Studying pancreases of people who had donated their bodies to science, researchers found that human insulin did not cause allergic reactions. Scientists realized that it would be best to find a chemical or biological way to prepare human insulin, and pharmaceutical companies worked hard toward this goal. Eli Lilly and Company was the first to succeed, and on May 14, 1982, it filed a new drug application with the Food and Drug Administration (FDA) for the human insulin preparation it named “Humulin.” Humulin is made by genetic engineering. Irving S. Johnson, who worked on the development of Humulin, described Eli Lilly’s method for producing Humulin. The common bacterium Escherichia coli is used. Two strains of the bacterium are produced by genetic engineering: The first strain is used to make a protein called an “A chain,” and the second strain is used to make a “B chain.” After the bacteria are harvested, the Aand B chains are removed and purified separately. Then the two chains are combined chemically. When they are purified once more, the result is Humulin, which has been proved by Ronald E. Chance and his Eli Lilly coworkers to be chemically, biologically, and physically identical to human insulin. Consequences The FDA and other regulatory agencies around the world approved genetically engineered human insulin in 1982. Humulin does not trigger allergic reactions, and its supply does not fluctuate. It has brought an end to the fear that there would be a worldwide shortage of insulin. Humulin is important as well in being the first genetically engineered industrial chemical. It began an era in which such advanced technology could be a source for medical drugs, chemicals used in farming, and other important industrial products. Researchers hope that genetic engineering will help in the understanding of cancer and other diseases, and that it will lead to ways to grow enough food for a world whose population continues to rise.