|
George A. Campbell
George Ashley Campbell (November 27, 1870 – November 10, 1954) was an American engineer. He was a pioneer in developing and applying quantitative mathematical methods to the problems of long-distance telegraphy and telephony. His most important contributions were to the theory and implementation of the use of loading coils and the first wave filters designed to what was to become known as the image method. Both these areas of work resulted in important economic advantages for the American Telephone and Telegraph Company (AT&T). Education Campbell was educated at the McCollom Institute in New Hampshire and then at MIT, where he graduated in 1891. He then received a master's degree from Harvard University in 1893. He was awarded a fellowship which enabled him to spend three years on graduate work; one year studying advanced mathematics under Felix Klein at Göttingen, one year studying electricity and mechanics under Ludwig Boltzmann in Vienna, and one year studying under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hastings, Minnesota
Hastings ( ) is a city mostly in Dakota County, Minnesota, Dakota County, Minnesota, of which it is the county seat, with a portion in Washington County, Minnesota, Washington County, Minnesota, United States. It is near the confluence of the Mississippi River, Mississippi, Vermillion, and St. Croix River (Wisconsin-Minnesota), St. Croix Rivers. The population was 22,154 at the 2020 United States census, 2020 census. It is named for the first elected governor of Minnesota, Henry Hastings Sibley. The advantages of Hastings's location that led to its original growth are that it is well-drained, provides a good riverboat port, and is close to a hydropower resource at the falls of the Vermillion River (Minnesota), Vermillion River. Other sites closer to the river confluence are either too swampy (Dakota County) or too hilly (Washington County and Pierce County, Wisconsin). U.S. Route 61 in Minnesota, U.S. Highway 61 and Minnesota State Highways Minnesota State Highway 55, 55 and Mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Poincaré
Jules Henri Poincaré (, ; ; 29 April 185417 July 1912) was a French mathematician, Theoretical physics, theoretical physicist, engineer, and philosophy of science, philosopher of science. He is often described as a polymath, and in mathematics as "The Last Universalist", since he excelled in all fields of the discipline as it existed during his lifetime. He has further been called "the Carl Friedrich Gauss, Gauss of History of mathematics, modern mathematics". Due to his success in science, along with his influence and philosophy, he has been called "the philosopher par excellence of modern science". As a mathematician and physicist, he made many original fundamental contributions to Pure mathematics, pure and applied mathematics, mathematical physics, and celestial mechanics. In his research on the three-body problem, Poincaré became the first person to discover a chaotic deterministic system which laid the foundations of modern chaos theory. Poincaré is regarded as the cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attenuation
In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates. Hearing protection device, Hearing protectors help reduce Sound power, acoustic flux from flowing into the ears. This phenomenon is called acoustic attenuation and is measured in decibels (dBs). In electrical engineering and telecommunications, attenuation affects the Wave propagation, propagation of waves and signals in electrical circuits, in optical fibers, and in air. Attenuator (electronics), Electrical attenuators and optical attenuators are commonly manufactured components in this field. Background In many cases, attenuation is an exponential function of the path length through the medium. In optics and in chemical spectroscopy, this is known as the Beer–Lambert law. In engineering, attenu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capacitance
Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related notions of capacitance: ''self capacitance'' and ''mutual capacitance''. An object that can be electrically charged exhibits self capacitance, for which the electric potential is measured between the object and ground. Mutual capacitance is measured between two components, and is particularly important in the operation of the capacitor, an elementary linear electronic component designed to add capacitance to an electric circuit. The capacitance between two conductors depends only on the geometry; the opposing surface area of the conductors and the distance between them; and the permittivity of any dielectric material between them. For many dielectric materials, the permittivity, and thus the capacitance, is independent of the potential ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. The interval of time between events is called the period. It is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times per minute (2 hertz), its period is one half of a second. Special definitions of frequency are used in certain contexts, such as the angular frequency in rotational or cyclical properties, when the rate of angular progress is measured. Spatial frequency is defined for properties that vary or cccur repeatedly in geometry or space. The unit of measurement of frequency in the International System of Units (SI) is the hertz, having the symbol Hz. Definitions and units For cyclical phenomena such as oscillations, waves, or for examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Newton, Massachusetts
West Newton is one of the thirteen villages within the city of Newton in Middlesex County, Massachusetts, United States. Among the oldest of the thirteen Newton villages, the West Newton Village Center is a National Register Historic District. The postal ("Zip") code 02465 roughly matches the village limits. Location West Newton is located in the north central part of Newton and is bordered by the town of Waltham on the north and by the villages of Auburndale on the west, Newton Lower Falls on the extreme southwest, Newtonville on the east, and Waban on the south. Railroad Station The West Newton train stop is located near an inn (now small shops) that served as a stagecoach stop. The original station structure was destroyed in the construction of the Massachusetts Turnpike, although the station itself still exists as a stop on the commuter rail. West Newton Square West Newton Square, the town center of West Newton, is home to many local businesses and venues. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jamaica Plain
Jamaica Plain is a Neighborhoods in Boston, neighborhood of in Boston, Massachusetts, United States. Settled by Puritans seeking farmland to the south, it was originally part of Roxbury, Massachusetts, Roxbury. The community seceded from Roxbury during the formation of West Roxbury, Massachusetts, West Roxbury in 1851 and became part of Boston when West Roxbury was annexed in 1874.Local Attachments : The Making of an American Urban Neighborhood, 1850 to 1920 (Creating the North American Landscape), by Alexander von Hoffman, The Johns Hopkins University Press (1996), In the 19th century, Jamaica Plain became one of the first streetcar suburbs in America and home to a significant portion of Boston's Emerald Necklace of parks, designed by Frederick Law Olmsted. In 2020, Jamaica Plain had a population of 41,012 according to the United States Census. History Colonial era Shortly after the founding of Boston and Roxbury, Massachusetts, Roxbury in 1630, William Heath's family and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed-element Model
In electrical engineering, the distributed-element model or transmission-line model of electrical circuits assumes that the attributes of the circuit ( resistance, capacitance, and inductance) are distributed continuously throughout the material of the circuit. This is in contrast to the more common lumped-element model, which assumes that these values are lumped into electrical components that are joined by perfectly conducting wires. In the distributed-element model, each circuit element is infinitesimally small, and the wires connecting elements are not assumed to be perfect conductors; that is, they have impedance. Unlike the lumped-element model, it assumes nonuniform current along each branch and nonuniform voltage along each wire. The distributed model is used where the wavelength becomes comparable to the physical dimensions of the circuit, making the lumped model inaccurate. This occurs at high frequencies, where the wavelength is very short, or on low-frequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumped-element Model
The lumped-element model (also called lumped-parameter model, or lumped-component model) is a simplified representation of a physical system or circuit that assumes all components are concentrated at a single point and their behavior can be described by idealized mathematical models. The lumped-element model simplifies the system or circuit behavior description into a topology. It is useful in electrical systems (including electronics), mechanical multibody systems, heat transfer, acoustics, etc. This is in contrast to distributed parameter systems or models in which the behaviour is distributed spatially and cannot be considered as localized into discrete entities. The simplification reduces the state space of the system to a finite dimension, and the partial differential equations (PDEs) of the continuous (infinite-dimensional) time and space model of the physical system into ordinary differential equations (ODEs) with a finite number of parameters. Electrical systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Stone Stone
John Stone Stone (September 24, 1869 – May 20, 1943) was an American mathematician, physicist and inventor. He initially worked in telephone research, followed by influential work developing early radio technology, where he was especially known for improvements in tuning. Despite his often advanced designs, the Stone Telegraph and Telephone Company failed in 1908, and he spent the remainder of his career as an engineering consultant. Biography Early years Stone was born in Dover (now Manakin) village, in Goochland County, Virginia, the son of Charles Pomeroy Stone, an American Civil War Union general and engineer, and Annie Jeannie toneStone. From 1870 until 1883, General Stone held the post of Chief of Staff to the khedive of Egypt, and, while growing up in Cairo, John Stone Stone became fluent in Arabic, French, German and Spanish in addition to English. His father tutored him in mathematics, and following the family's return to the United States, Stone attended C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heaviside Condition
A transmission line which meets the Heaviside condition, named for Oliver Heaviside (1850–1925), and certain other conditions can transmit signals without dispersion and without distortion. The importance of the Heaviside condition is that it showed the possibility of dispersionless transmission of telegraph signals.In some cases, the performance of a transmission line can be improved by adding inductive loading to the cable. The condition A transmission line can be represented as a distributed-element model of its primary line constants as shown in the figure. The primary constants are the electrical properties of the cable per unit length and are: capacitance ''C'' (in farads per meter), inductance ''L'' (in henries per meter), series resistance ''R'' (in ohms per meter), and shunt conductance ''G'' (in siemens per meter). The Heaviside condition is satisfied when :\frac = \frac. The series resistance and shunt conductivity cause losses in the line; for an ideal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oliver Heaviside
Oliver Heaviside ( ; 18 May 1850 – 3 February 1925) was an English mathematician and physicist who invented a new technique for solving differential equations (equivalent to the Laplace transform), independently developed vector calculus, and rewrote Maxwell's equations in the form commonly used today. He significantly shaped the way Maxwell's equations are understood and applied in the decades following Maxwell's death. His formulation of the telegrapher's equations became commercially important during his own lifetime, after their significance went unremarked for a long while, as few others were versed at the time in his novel methodology. Although at odds with the scientific establishment for most of his life, Heaviside changed the face of telecommunications, mathematics, and science. Early life Heaviside was born in Camden Town, London, at 55 Kings Street (now Plender Street), the youngest of three children of Thomas, a draughtsman and wood engraver, and Rachel Elizabeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
