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John Call Cook
John Call Cook (April 7, 1918 – October 12, 2012) was an American geophysicist who played a crucial role in establishing the field of ground-penetrating radar and is generally regarded as contributing the fundamental research to develop the field. Cook is also known for demonstrating that aerial surveys can map surface radioactivity to enable much more efficient prospecting for uranium ore, for inventing electrostatic detection of hazardous ice crevasses, and for developing other novel techniques in remote sensing. During most of his professional career, Cook specialized in the techniques of remote sensing and the detection of underground objects. Early years John Call Cook was born on April 7, 1918 in Afton, Wyoming, to Carl and Ella Cook. Carl made his living as an attorney and farmer, and was himself the son of Phineas Wolcott Cook and number 4 wife, Johanna. During his teens, John constructed various devices including a spark-gap device, a batteryless crystal radio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afton, Wyoming
Afton is a town in Lincoln County, Wyoming, United States. The population was 1,911 at the 2010 census. Afton is home to the world's largest arch made of elk antlers. Spanning across the four lanes of U.S. Highway 89, the arch consists of 3,011 elk antlers and weighs 15 tons. History The first settlement at Afton was made in 1885. The community takes its name from the River Afton, in Ayrshire, Scotland. Geography Afton is the largest city in Star Valley, a grassland valley in forested mountains. According to the United States Census Bureau, the town has a total area of , all land. A periodic spring is Afton's main water supply, which cycles on and off during the summer, fall, and winter at 12 to 18 minute intervals. During the spring the flow never stops due to increased water supply from the melting snowpack. At full flow the Intermittent Spring discharges up to 285 gallons per second. It is located five miles east of Afton, a short hike from the end of Swift Creek Road. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Radio
A crystal radio receiver, also called a crystal set, is a simple radio receiver, popular in the early days of radio. It uses only the power of the received radio signal to produce sound, needing no external power. It is named for its most important component, a crystal detector, originally made from a piece of crystalline mineral such as galena. This component is now called a diode. Crystal radios are the simplest type of radio receiver and can be made with a few inexpensive parts, such as a wire for an antenna, a coil of wire, a capacitor, a crystal detector, and earphones (because a crystal set has insufficient power for a loudspeaker). However they are passive receivers, while other radios use an amplifier powered by current from a battery or wall outlet to make the radio signal louder. Thus, crystal sets produce rather weak sound and must be listened to with sensitive earphones, and can receive stations only within a limited range of the transmitter. The rectifying prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Oxygen
Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which has continued to the present. Physical properties Liquid oxygen has a pale blue color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet. Liquid oxygen has a density of , slightly denser than liquid water, and is cryogenic with a freezing point of and a boiling point of at . Liquid oxygen has an expansion ratio of 1:861 under and , and because of this, it is used in some commercial and military aircraft as a transportable source of breathing oxygen. Because of its cryogenic nature, liquid oxygen can cause the materials it touches to become extremely brittle. Liquid oxygen is also a very powerful oxidizing agent: organic materials will burn rapidly and energetically in liquid o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid-propellant Rocket
A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid rocket propellant, liquid propellants. Liquids are desirable because they have a reasonably high density and high Specific impulse, specific impulse (''I''sp). This allows the volume of the propellant tanks to be relatively low. It is also possible to use lightweight centrifugal turbopumps to pump the rocket propellant from the tanks into the combustion chamber, which means that the propellants can be kept under low pressure. This permits the use of low-mass propellant tanks that do not need to resist the high pressures needed to store significant amounts of gasses, resulting in a low mass ratio for the rocket. An inert gas stored in a tank at a high pressure is sometimes used instead of pumps in simpler small engines to force the propellants into the combustion chamber. These engines may have a higher mass ratio, but are usually more reliable, and are therefore used widely in satellites for orbit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Rocket Society
The American Rocket Society (ARS) began its existence on , under the name of the American Interplanetary Society. It was founded by science fiction writers G. Edward Pendray, David Lasser, Laurence Manning, Nathan Schachner, and others. Pendray corresponded with Willy Ley of the German rocket society, Verein für Raumschiffahrt, and visited him in 1931. The members originally conducted their own rocket experiments in New York and New Jersey. The society printed its own journal. The AIS did pioneering work in testing the design requirements of liquid-fueled rockets, with a number of successful test launches of ARS rockets occurring in this period and pointing the way to the United States space program. Its name was changed to American Rocket Society on . In 1936, the American Rocket Society and its member Alfred Africano were awarded the Prix d'Astronautique by the Société astronomique de France (French Astronomical Society) in recognition of their pioneering tests with liquid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Jamming And Deception
Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information. Concepts that blanket the radar with signals so its display cannot be read are normally known as jamming, while systems that produce confusing or contradictory signals are known as deception, but it is also common for all such systems to be referred to as jamming. There are two general classes of radar jamming, mechanical and electronic. Mechanical jamming entails reflecting enemy radio signals in various ways to provide false or misleading target signals to the radar operator. Electronic jamming works by transmitting additional radio signals towards enemy receivers, making it difficult to detect real target signals, or take advantage of known behaviors of automated systems like radar lock-on to confuse the system. Various counter-countermeasures can sometimes he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chaff
Chaff (; ) is the dry, scaly protective casing of the seeds of cereal grains or similar fine, dry, scaly plant material (such as scaly parts of flowers or finely chopped straw). Chaff is indigestible by humans, but livestock can eat it. In agriculture it is used as livestock fodder, or is a waste material ploughed into the soil or burned. Etymology "Chaff" comes from Middle English ''chaf'', from Old English , related to Old High German ''cheva'', "husk". Grain chaff In grasses (including cereals such as rice, barley, oats, and wheat), the ripe seed is surrounded by thin, dry, scaly bracts (called glumes, lemmas and paleas), forming a dry husk (or hull) around the grain. Once it is removed it is often referred to as chaff. In wild cereals and in the primitive domesticated einkorn,Potts, D. T. (1996) ''Mesopotamia Civilization: The Material Foundations'' Cornell University Press. p. 62. . emmer and spelt wheats, the husks enclose each seed tightly. Before the grain can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hanscom Air Force Base
Hanscom Air Force Base (AFB) is a United States Air Force base located predominantly within Bedford, Massachusetts, with portions extending into the adjoining towns of Lincoln, Concord and Lexington. The facility is adjacent to Hanscom Field which provides general aviation and charter service. Hanscom AFB is the part of the Air Force Life Cycle Management Center, one of six centers under Air Force Materiel Command (AFMC). The Air Force Life Cycle Management Center is the single center responsible for total life cycle management of Air Force weapon systems and is headquartered at Wright-Patterson AFB, Ohio. The host unit at Hanscom is the 66th Air Base Group (66 ABG) assigned to AFMC. Overview A non-flying base, Hanscom Air Force Base is named after Laurence G. Hanscom (1906–1941), a pilot, aviation enthusiast, and State House reporter who was killed in a plane crash at Saugus, Massachusetts. Hanscom was a reporter for the Boston Globe, Worcester Telegram & Gazette and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-17 Bomber
The Boeing B-17 Flying Fortress is a four-engined heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Relatively fast and high-flying for a bomber of its era, the B-17 was used primarily in the European Theater of Operations and dropped more bombs than any other aircraft during World War II. It is the third-most produced bomber of all time, behind the four-engined Consolidated B-24 Liberator and the multirole, twin-engined Junkers Ju 88. It was also employed as a transport, antisubmarine aircraft, drone controller, and search-and-rescue aircraft. In a USAAC competition, Boeing's prototype Model 299/XB-17 outperformed two other entries but crashed, losing the initial 200-bomber contract to the Douglas B-18 Bolo. Still, the Air Corps ordered 13 more B-17s for further evaluation, then introduced it into service in 1938. The B-17 evolved through numerous design advances but from its inception, the USAAC (later, the USAAF) promoted the aircraft as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gasholder
A gas holder or gasholder, also known as a gasometer, is a large container in which natural gas or town gas is natural gas storage, stored near atmospheric pressure at room temperature, ambient temperatures. The volume of the container follows the quantity of stored gas, with pressure coming from the weight of a movable cap. Typical volumes for large gas holders are about , with diameter structures. Gas holders now tend to be used for balancing purposes to ensure that gas pipes can be operated within a safe range of pressures, rather than for actually storing gas for later use. Etymology Antoine Lavoisier devised the first gas holder, which he called a pneumatic chemistry#Gasometer, ''gazomètre'', to assist his work in pneumatic chemistry. It enabled him to weigh the gas in a pneumatic trough with the precision he required. He published his ''Traité Élémentaire de Chimie'' in 1789. James Watt Junior collaborated with Thomas Beddoes in constructing the pneumatic medicine, p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
K Band (IEEE)
The IEEE K-band is a portion of the radio spectrum in the microwave range of frequencies from 18 to 27-Gigahertz (GHz). The range of frequencies in the center of the K-band between 18- and 26.5-GHz is absorbed by water vapor in the atmosphere due to its resonance peak at 22.24-GHz, . Therefore these frequencies experience high atmospheric attenuation and cannot be used for long distance applications. For this reason the original K-band has been split into three bands, Ka-band, K-band, and Ku-band as detailed below. The K stands for Kurz which stems from the German word for short. Subdivisions Because of the water vapor absorption peak in the center of the band, the IEEE K-band is conventionally divided into three sub-bands: * Ku-band: K-under band, 12–18-GHz, mainly used for satellite communications, direct-broadcast satellite television, terrestrial microwave communications, and radar, especially police traffic-speed detectors. * K-band 18–27-GHz: Due to the 22-GHz wate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-band
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approximately 7.0–11.2 GHz. In radar engineering, the frequency range is specified by the Institute of Electrical and Electronics Engineers (IEEE) as 8.0–12.0 GHz. The X band is used for radar, satellite communication, and wireless computer networks. Radar X band is used in radar applications including continuous-wave, pulsed, single- polarization, dual-polarization, synthetic aperture radar, and phased arrays. X band radar frequency sub-bands are used in civil, military, and government institutions for weather monitoring, air traffic control, maritime vessel traffic control, defense tracking, and vehicle speed detection for law enforcement. X band is often used in modern radars. The shorter wavelengths of the X band allow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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