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David L. Fried
David L. Fried (April 13, 1933 – May 5, 2022) was an American scientist, best known for his contributions to optics. Fried described what has come to be known as the Fried Parameter, or r0 (often pronounced ''r-naught'', but also ''r-zero''). The Fried Parameter is a measure of the strength of the turbulence in the atmosphere of Earth. The turbulence causes what is known as ''seeing'' in astronomy and usually limits the optical resolution of ground-based telescopes and the detail in their images of astronomical objects. The Fried Parameter describes the smallest diameter of a telescope aperture at which the image fidelity starts to suffer significantly from turbulent airflows in the atmosphere of Earth. The Fried Parameter may change quickly on the time scale of minutes, or less. Typical values for the Fried Parameter in the visible spectrum may range from less than one centimeter (you can detect turbulence with your eye) to some tens of centimeters at good astronomical sites. L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientist
A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branches of science, area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophical study of nature called natural philosophy, a precursor of natural science. Though Thales (circa 624-545 BC) was arguably the first scientist for describing how cosmic events may be seen as natural, not necessarily caused by gods,Frank N. Magill''The Ancient World: Dictionary of World Biography'', Volume 1 Routledge, 2003 it was not until the 19th century in science, 19th century that the term ''scientist'' came into regular use after it was coined by the theologian, philosopher, and historian of science William Whewell in 1833. In modern times, many scientists have Terminal degree, advanced degrees in an area of science and pursue careers in various Sector (economic), sectors of the economy such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Master Of Science
A Master of Science ( la, Magisterii Scientiae; abbreviated MS, M.S., MSc, M.Sc., SM, S.M., ScM or Sc.M.) is a master's degree in the field of science awarded by universities in many countries or a person holding such a degree. In contrast to the Master of Arts degree, the Master of Science degree is typically granted for studies in sciences, engineering and medicine and is usually for programs that are more focused on scientific and mathematical subjects; however, different universities have different conventions and may also offer the degree for fields typically considered within the humanities and social sciences. While it ultimately depends upon the specific program, earning a Master of Science degree typically includes writing a thesis. The Master of Science degree was first introduced at the University of Michigan in 1858. One of the first recipients of the degree was De Volson Wood, who was conferred a Master of Science degree at the University of Michigan in 1859. Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Roughness
Surface roughness, often shortened to roughness, is a component of surface finish (surface texture). It is quantified by the deviations in the direction of the normal vector of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is smooth. In surface metrology, roughness is typically considered to be the high-frequency, short-wavelength component of a measured surface. However, in practice it is often necessary to know both the amplitude and frequency to ensure that a surface is fit for a purpose. Roughness plays an important role in determining how a real object will interact with its environment. In tribology, rough surfaces usually wear more quickly and have higher friction coefficients than smooth surfaces. Roughness is often a good predictor of the performance of a mechanical component, since irregularities on the surface may form nucleation sites for cracks or corrosion. On the other hand, roughness may pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emissivity
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is not visible to human eyes. A portion of the thermal radiation from very hot objects (see photograph) is easily visible to the eye. The emissivity of a surface depends on its chemical composition and geometrical structure. Quantitatively, it is the ratio of the thermal radiation from a surface to the radiation from an ideal black surface at the same temperature as given by the Stefan–Boltzmann law. The ratio varies from 0 to 1. The surface of a perfect black body (with an emissivity of 1) emits thermal radiation at the rate of approximately 448 watts per square metre at room temperature (, ). All real objects have emissivities less than 1.0, and emit radiation at correspondingly lower rates. Emissivities are important in several conte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectance
The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic structure of the material to the electromagnetic field of light, and is in general a function of the frequency, or wavelength, of the light, its polarization, and the angle of incidence. The dependence of reflectance on the wavelength is called a ''reflectance spectrum'' or ''spectral reflectance curve''. Mathematical definitions Hemispherical reflectance The ''hemispherical reflectance'' of a surface, denoted , is defined as R = \frac, where is the radiant flux ''reflected'' by that surface and is the radiant flux ''received'' by that surface. Spectral hemispherical reflectance The ''spectral hemispherical reflectance in frequency'' and ''spectral hemispherical reflectance in wavelength'' of a surface, denoted and respectively, are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands. A more common definition in radio-frequency engineering is the range between 1 and 100 GHz (wavelengths between 0.3 m and 3 mm). In all cases, microwaves include the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations. The prefix ' in ''microwave'' is not meant to suggest a wavelength in the micrometer range. Rather, it indicates that microwaves are "small" (having shorter wavelengths), compared to the radio waves used prior to microwave te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light which is ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar (light detection and ranging). Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum. Alternatively, temporal coherence can be used to produce ultrashort pulses of ligh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonetics
Autonetics was a division of North American Aviation that produced various avionics but is best known for their inertial navigation systems used in submarines and intercontinental ballistic missiles. Its 188-acre facility in Anaheim, California, with 36,000 employees, was the city's largest employer. Through a series of mergers, Autonetics is now part of Boeing. Origin Autonetics originated in North American Aviation's Technical Research Laboratory, a small unit in the Los Angeles Division's engineering department, in 1945. In 1946, the laboratory won an Army Air Forces contract to develop a 175 to 500 mile range glide missile. The work and the lab expanded, and by June 1948, all of the Aerophysics Laboratory was consolidated at Downey, California. The evolution of the Navaho missile program then resulted in the establishment of Autonetics as a separate division of North American Aviation in 1955, first located in Downey, moving to Anaheim, California in 1963. Divisions Autonetics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rockwell International
Rockwell International was a major American manufacturing conglomerate involved in aircraft, the space industry, defense and commercial electronics, components in the automotive industry, printing presses, avionics and industrial products. Rockwell International's predecessor was Rockwell Manufacturing Company, founded in 1919 by Willard Rockwell. In 1968, Rockwell Manufacturing Company included 7 operating divisions manufacturing industrial valves, German 2-cycle motors, power tools, gas and water meters. In 1973, it was combined with the aerospace products and renamed Rockwell International. At its peak, Rockwell International was No. 27 on the Fortune 500 list, with assets of over $8 billion, sales of $27 billion and 115,000 employees. History Rockwell Manufacturing Company Boston-born Willard Rockwell (1888–1978) made his fortune with the invention and successful launch of a new bearing system for truck axles in 1919. He merged his Oshkosh, Wisconsin-base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RCA Astro-Electronics Division
Lockheed Martin Space is one of the four major business divisions of Lockheed Martin. It has its headquarters in Littleton, Colorado, with additional sites in Valley Forge, Pennsylvania; Sunnyvale, California; Santa Cruz, California; Huntsville, Alabama; and elsewhere in the United States and United Kingdom. The division currently employs about 16,000 people, and its most notable products are commercial and military satellites, space probes, missile defense systems, NASA's Orion spacecraft, and the Space Shuttle external tank. History The Lockheed Missile Systems Division was established in Van Nuys, California, in late 1953 to consolidate work on the Lockheed X-17 and X-7. The X-17 was a three-stage solid-fuel research rocket designed to test the effects of high mach atmospheric reentry. The X-17 was also used as the booster for the Operation Argus series of three high-altitude nuclear tests conducted in the South Atlantic in 1958. The Lockheed X-7 (dubbed the "Flying Stove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware River and Pennsylvania; and on the southwest by Delaware Bay and the state of Delaware. At , New Jersey is the fifth-smallest state in land area; but with close to 9.3 million residents, it ranks 11th in population and first in population density. The state capital is Trenton, and the most populous city is Newark. With the exception of Warren County, all of the state's 21 counties lie within the combined statistical areas of New York City or Philadelphia. New Jersey was first inhabited by Native Americans for at least 2,800 years, with the Lenape being the dominant group when Europeans arrived in the early 17th century. Dutch and Swedish colonists founded the first European settlements in the state. The British later seized control o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Brunswick, New Jersey
New Brunswick is a city (New Jersey), city in and the county seat, seat of government of Middlesex County, New Jersey, Middlesex County, in the U.S. state of New Jersey.New Jersey County Map New Jersey Department of State. Accessed July 10, 2017. The city is the home of Rutgers University. The city is both a regional commercial hub for Central Jersey, central New Jersey and a prominent and growing commuter town for residents commuting to New York City within the New York metropolitan area. New Brunswick is on the Northeast Corridor, Northeast Corridor rail line, southwest of Manhattan. The city is located on the southern banks of the Raritan River in the Raritan Valley region. For 2020 United States census, 2020, New Brunswick had a population of 55,266 residents, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
