Cosmic microwave background radiation - Cosmic microwave background radiation Cosmic microwave background radiation June 2001 The Cosmic Microwave Background Radiation is a form of electromagnetic radiation that fills the whole of the universe. It has the characteristics of black body radiation at a temperature of 2.726 kelvins. It has a frequency in the microwave range. Table of contents showTocToggle("show","hide") 1 Big Bang Evidence? 2 Features 3 Theory 4 Experiments 5 Skeptics 6 See also 7 Bibliography 8 References and external links Big Bang Evidence? This radiation is regarded as the best available evidence of the Big Bang theory -- it gives a snapshot of the Universe when the temperature dropped enough to allow electrons and protons to form hydrogen atoms, thus making the universe transparent to radiation. When it originated some 300,000.
Keyboard technology - excellent response. Most IBM keyboards up into the PS/2 line were of this type, and considered to be among the best of breed, although some complained that they were "clackity." Hall effect keyboard Hall effect keyboards use magnets and "Hall Effect" sensors instead of an actual switch. When a key is depressed, it moves a magnet, which is detected by a solid-state Hall-Effect sensor. These keyboards are extremely reliable, able to accept millions of keystrokes before failing. They are used for ultra-high reliability applications, in locations like nuclear powerplants or aircraft cockpits. They are also sometimes used in industrial environments. These keyboards can be easily made totally waterproof. They also resist large amounts of dust and contaminants. Because a magnet and sensor is required for each key, as well as custom.
Kitchen - (outdoor areas in which food is prepared are generally not considered to be kitchens). It may have a furnace and/or a microwave oven, and small appliances such as a toaster, mixer and blender. Within homes, the kitchen can be the center of other activities as well, depending on its size, furnishing, and equipment (see also major appliance), for example washing up (with or without dishwasher), washing and drying laundry (often with a washing machine), normal and refrigerated food storage, and eating. The kitchen is sometimes the most comforting room in a house, where family and visitors tend to congregate, instead of in the living room. In restaurants, hotels, and other public establishments, the kitchen generally is required by law to meet certain standards of public health, and is inspected periodically by.
Klystron - vacuum tube (evacuated electron tube) used as an oscillator or amplifier at microwave frequencies to produce high-power radio signals. In the klystron, an electron beam is velocity modulated (periodically bunched) to produce large amounts of power. They can produce high frequency high amplitude signals that most solid-state devices are incapable of. They are used in radar, satellite and wideband high power communication, and high- power physics (particle accelerators). See also: Magnetron.
Klystron tube - tube that produces microwaves in usable quantity, quality and power. see Microwave.
Kraft Dinner - box of Kraft Dinner, which is meant to serve four, comes with macaroni pasta and a package of dehydrated cheese. To this one adds milk and butter. It can be made either on a stove or in a microwave. While the box says it feeds four many can consume an entire box at once. While many love it it has frequently been decried for its neon orange cheese, its lack of nutritional value, and the artificiality of its ingredients. Kraft Dinner was introduced in Canada and the United States in 1937. It became extremely successful during World War II when most types of food, such as meat, milk, and eggs, were severely rationed. Kraft Dinner, containing only artificial ingredients, escaped these restrictions. Canada has always been the world's largest per capita.
Ku band - ("kay yoo band") is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 10.9 to 12.75 GHz. The Ku band is primarily used for satellite communications, particularly for satellite backhauls from remote locations back to a television network's studio for editing and broadcasting. Direct broadcast satellite signals occupy the upper portion of the Ku band, from 12.2 to 12.75 GHz. See also: C band, Ka band.
Jagadis Chandra Bose - physicist at Presidency College in Calcutta, India, who pioneered the investigation of microwave optics in the later 1800's. He invented radio communication before Marconi. Many of his instruments are still on display and remain largely usable now, over 100 years later. They include various antennas, polarizers, and waveguides, all of which remain in use in modern forms today. He was also known as an excellent teacher who believed in the use of classroom demonstrations, a trait apparently picked up while studying with Lord Rayleigh at Cambridge. He influenced many later Indian physicists, including Satyendra Bose (no relation) who later went on to be an influential figure in 20th century physics. Later he turned his attention to plant physiology, where he gained a new sort of fame with continued claims that plants.
Velvet Glove missile - CF-100 started in 1954, with the aircraft flying from Trenton to fire over Picton. The site was later used to launch models of the Arrow for aerodynamics testing. Testing of the Velvet Glove then moved to an operational setting at Cold Lake, Alberta. The final missile design was about ten feet long and just under a foot in diameter. It used four fins at the tail for steering, and was guided by a semi-active radar homing device in the nose, located behind a conical nose cone. An advanced microwave radar proximity fuse fired the 60 pound warhead..
VHSIC Hardware Description Language - of bit called bit_vector and of character called string. A problem not solved by this edition, however, was "multi-valued logic", where a signal's drive strength (none, weak or strong) and unknown values are also considered. This required IEEE standard 1164, which defined the 9-value std_logic. The second issue of IEEE 1076, in 1993, made the syntax more consistent, allowed more flexibility in naming, extended the character type to match the full 8-bit ASCII definition, added the xnor operator, etc. More recently, the language has been extended by introducing signed and unsigned types to facilitate arithmetical operations; analog and mixed-signal circuit design extensions; VITAL (VHDL Initiative Towards ASIC Libraries); microwave circuit design extensions. Discussion VHDL is in fact a fairly general-purpose programming language, provided that you have a simulator on which to.
July 1 - of the First Battle of the Somme. On this first day, 20,000 soldiers of the British Army are killed, and 40,000 wounded. Lasts until November; about one million casualties. 1931 - Official opening of Milan Central Station 1923 - Canadian Parliament suspends all Chinese immigration. 1935 - Regina, Saskatchewan police and Royal Canadian Mounted Police ambush strikers participating in On-to-Ottawa-Trek. 1958 - Nationwide television broadcasts via microwave begin in Canada 1962 - Independence of Rwanda and Burundi. 1963 - Zip code introduced for United States mail 1966 - First colour television transmission in Canada, from Toronto. 1968 - Nuclear non-proliferation treaty signed by about sixty countries in Geneva Switzerland 1980 - O Canada officially becomes the national anthem of Canada. 1991 - The Warsaw Pact is officially dissolved. 1996 - Version.
IEEE 802.11 - n) are service enhancement and extensions, or corrections to previous specifications. 802.11b was the first widely accepted wireless networking standard, followed, paradoxically, by 802.11a and 802.11g. The frequencies used are in the microwave range. Table of contents showTocToggle("show","hide") 1 Protocols 1.1 802.11legacy 1.2 802.11b 1.3 802.11a 1.4 802.11g 1.5 Overview 2 Certification 3 Standards 4 Community networks 5 Security 6 See also 7 External Links Protocols 802.11legacy The original version of the standard IEEE 802.11 released in 1997 and sometimes called "802.11legacy" specifies two data rates of 1 and 2 Megabits per second (Mbit/s) to be transmitted via infrared (IR) signals or in the ISM band at 2.4 GHz. IR has been dropped from later revisions of the standard, because it couldn't succeed against the well established IrDA protocol and had.
Individual - drunk state, the body was considered not to hold the same individual as in the sober state. One may assume that momentary madness can happen to everyone (something like a computer crash). The normal individual is considered absent from the body during that state of madness, and therefore not responsible. (Compare with temporary insanity and automatism). For example, in 1795 in England, a young woman who had taken good care of her ill mother for many years, suddenly killed her. It was considered that a momentary madness was caused by severe fatigue from her hard work. Especially the days before the awful event had been very hard, because of her mother's condition. The woman was not prosecuted. She later married and had children and never committed any crime. In 1999 in.
Infrared - wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation has wavelengths between 700 nm and 1 mm. IR is often subdivided into near-IR (NIR, 0.7-5 µm in wavelength), mid-IR (MIR (also intermediate-IR (IIR)), 5 - 30 µm) and far-IR (FIR, 30 - 1000 µm). However, these terms are not precise, and are used differently in the various study. Infrared radiation is often linked to heat, since objects at room temperature or above will emit radiation mostly concentrated in the mid-infrared band (see black body). Uses Infrared is used in night-vision equipment, when there is insufficient visible light to see an object. The radiation is detected and turned into.
Integrated Sachs Wolfe effect - effect is something that happens to fluctuations in the temperature of the cosmic microwave background, according to the standard Big Bang model, unless the Universe is perfectly flat and the cosmological constant is zero. It is due to the gravitational redshift induced by photons falling into and climbing out of very dense regions of space, called potential wells, in between the Earth and the surface of last scattering (close to the particle horizon). The naive sachs wolfe effect is also due to gravitational redshift, but is the effect only at the surface of last scattering itself..
Heinrich Rudolf Hertz - which is the basis for the invention of radio. He died in Bonn, Germany. His nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Hellmuth Hertz invented medical ultrasonography. See also People Wilhelm Röntgen Hans Christian Ųrsted Guglielmo Marconi Gustav Ludwig Hertz Hermann von Helmholtz James Clerk Maxwell Nikola Tesla Wilhelm Röntgen Lists and histories Electromagnetism timeline Timeline of mechanics and physics List of physicists Radio history Wireless telegraphy List of people on stamps of Germany List of physics topics Electromagnetic radiation Frequency Hertz Microwave X-ray Photoelectric effect Radar Luminiferous aether Other University of Bonn University of Karlsruhe Radio.
Heterodyne repeater - and operate using line-of-sight propogation from the tops of mountains, tall buildings and towers, giving small mobile and handheld radios radio coverage for hundreds of miles. Note: Heterodyne repeaters are used, for example, in microwave systems, to avoid undesired feedback between the receiving and transmitting antennas. Synonym IF repeater. Source: from Federal Standard 1037C and from MIL-STD-188.
Heat transfer - pressure differences. Radiation carries heat through the emission and absorption of photons (electromagnetic radiation). For room temperature objects, the majority of photons emitted (and involved in radiative heat transfer) are in the infrared spectrum, but this is by no means the only frequency range involved in radiation. Hotter objects transfer heat in the visible spectrum or beyond. Whenever EM radiation is emitted and then absorbed, heat is transferred. This principle is used in microwave ovens, laser cutting, and RF hair removal. The electrons of a metallic solid conduct nearly all of the heat through the solid. Electrons also conduct electric current through conductive solids, and the thermal and electrical conductivities of most metals have about the same ratio. A good electrical conductor, such as copper, also conducts heat well. The Peltier.
History of astronomy - Galilei and Kepler. The latter of these was the first to provide a system which described correctly the details of the motion of the planets with the Sun at the center. He didn't understand the reasons behind the laws he wrote down, however, and it was left to Newton's invention of celestial dynamics and his law of gravitation, the final explanation of the motions of the planets. Astrophysics was only possible once it was understood that the elements that made up the "celestial objects" were the same that made up the Earth, and that the same laws of physics applied. Stars were found much later to be far away objects, and with the advent of spectroscopy it was proved that they were similar to our own sun, but with a range.
Home Box Office - was the first cable network to originate as a non-terrestrial broadcast TV network. HBO went on the air in 1965 and was originally transmitted via terrestrial microwave towers. In 1976, HBO became the first TV network to broadcast its signals via satellite when it showed the "Thrilla From Manila" boxing match between Muhammad Ali and Joe Frazier. In 1986, HBO also became the first satellite network to encrypt its signal from unauthorized viewing. Later, HBO was one of the first cable TV networks to broadcast an HDTV version of its channel. HBO is currently owned by AOL Time Warner. See also: HBO Latino..
