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Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits. The equations provide a mathematical model for electric, optical, and radio technologies, such as power generation, electric motors, wireless communication, lenses, radar, etc. They describe how electric and magnetic fields are generated by charges, currents, and changes of the fields. The equations are named after the physicist and mathematician James Clerk Maxwell, who, in 1861 and 1862, published an early form of the equations that included the Lorentz force law. Maxwell first used the equations to propose that light is an electromagnetic phenomenon. The modern form of the equations in their most common formulation is credited to Oliver Heaviside.
Communications security is the discipline of preventing unauthorized interceptors from accessing telecommunications in an intelligible form, while still delivering content to the intended recipients.
In telecommunications, a cryptochannel is a complete system of crypto-communications between two or more holders or parties. It includes: (a) the cryptographic aids prescribed; (b) the holders thereof; (c) the indicators or other means of identification; (d) the area or areas in which effective; (e) the special purpose, if any, for which provided; and (f) pertinent notes as to distribution, usage, etc. A cryptochannel is analogous to a radio circuit.
In metadata, the term data element is an atomic unit of data that has precise meaning or precise semantics. A data element has:
- An identification such as a data element name
- A clear data element definition
- One or more representation terms
- Optional enumerated values Code (metadata)
- A list of synonyms to data elements in other metadata registries Synonym ring
Electromagnetic compatibility (EMC) is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy which may cause unwanted effects such as electromagnetic interference (EMI) or even physical damage to operational equipment. The goal of EMC is the correct operation of different equipment in a common electromagnetic environment. It is also the name given to the associated branch of electrical engineering.
In military telecommunications, electronic support (ES) or electronic support measures (ESM) gather intelligence through passive "listening" to electromagnetic radiations of military interest. They are an aspect of electronic warfare involving actions taken under direct control of an operational commander to detect, intercept, identify, locate, record, and/or analyze sources of radiated electromagnetic energy for the purposes of immediate threat recognition or longer-term operational planning. Thus, electronic support provides a source of information required for decisions involving electronic protection (EP), electronic attack (EA), avoidance, targeting, and other tactical employment of forces. Electronic support data can be used to produce signals intelligence (SIGINT), communications intelligence (COMINT) and electronics intelligence (ELINT).
Electro–optics is a branch of electrical engineering, electronic engineering, materials science, and material physics involving components, electronic devices such as lasers, laser diodes, LEDs, waveguides, etc. which operate by the propagation and interaction of light with various tailored materials. It is closely related to photonics, the branch of optics that involves the application of the generation of photons. It is not only concerned with the "electro–optic effect", since it deals with the interaction between the electromagnetic and the electrical states of materials.
In telecommunications, a facility is defined by Federal Standard 1037C as:
- A fixed, mobile, or transportable structure, including (a) all installed electrical and electronic wiring, cabling, and equipment and (b) all supporting structures, such as utility, ground network, and electrical supporting structures.
- A network-provided service to users or the network operating administration.
- A transmission pathway and associated equipment.
- In a protocol applicable to a data unit, such as a block or frame, an additional item of information or a constraint encoded within the protocol to provide the required control.
- A real property entity consisting of one or more of the following: a building, a structure, a utility system, pavement, and underlying land.
Foreign instrumentation signals intelligence, FISINT (Foreign Instrumentation Signature INTelligence) is intelligence from the interception of foreign electromagnetic emissions associated with the testing and operational deployment of foreign aerospace, surface, and subsurface systems. Since it deals with signals that have communicational content, it is a subset of Communications Intelligence (COMINT), which, in turn, is a subset of SIGINT. Unlike general COMINT signals, the content of FISINT signals is not in regular human language, but rather in machine to machine (instrumentation) language or in a combination of regular human language and instrumentation language. FISINT is also considered as a subset of MASINT (measurement and signature intelligence).
Electromagnetic warfare or electronic warfare (EW) is warfare involving the use of the electromagnetic spectrum or directed energy to control the spectrum, attack an enemy, or impede enemy operations. The purpose of electromagnetic warfare is to deny the opponent the advantage of—and ensure friendly unimpeded access to—the EM spectrum. Electromagnetic warfare can be applied from air, sea, land, or space by crewed and uncrewed systems, and can target communication, radar, or other military and civilian assets.
The near field and far field are regions of the electromagnetic (EM) field around an object, such as a transmitting antenna, or the result of radiation scattering off an object. Non-radiative near-field behaviors dominate close to the antenna or scatterer, while electromagnetic radiation far-field behaviors predominate at greater distances.
The Rossi X-ray Timing Explorer (RXTE) was a NASA satellite that observed the time variation of astronomical X-ray sources, named after physicist Bruno Rossi. The RXTE had three instruments — an All-Sky Monitor, the High-Energy X-ray Timing Experiment (HEXTE) and the Proportional Counter Array. The RXTE observed X-rays from black holes, neutron stars, X-ray pulsars and X-ray bursts. It was funded as part of the Explorer program and was also called Explorer 69.
In physics, mathematics and statistics, scale invariance is a feature of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor, and thus represent a universality.
In physics and engineering, surface power density is power per unit area.
The Fast Auroral SnapshoT Explorer was a NASA plasma physics satellite, and was the second spacecraft in the Small Explorer program (SMEX). It was launched on 21 August 1996, from Vandenberg Air Force Base aboard a Pegasus XL launch vehicle. The spacecraft was designed and built by NASA's Goddard Space Flight Center (GSFC). Flight operations were handled by GSFC for the first three years, and thereafter were transferred to the University of California, Berkeley's Space Sciences Laboratory.
Command and control is a "set of organizational and technical attributes and processes ... [that] employs human, physical, and information resources to solve problems and accomplish missions" to achieve the goals of an organization or enterprise, according to a 2015 definition by military scientists Marius Vassiliou, David S. Alberts, and Jonathan R. Agre. The term often refers to a military system.
The following outline is provided as an overview of and topical guide to social science:
The following outline is provided as an overview of and topical guide to applied science:
The ISEE-1 was an Explorer-class mother spacecraft, International Sun-Earth Explorer-1, was part of the mother/daughter/heliocentric mission. ISEE-1 was a 340.2 kg (750 lb) space probe used to study magnetic fields near the Earth. ISEE-1 was a spin-stabilized spacecraft and based on the design of the prior IMP series of spacecraft. ISEE-1 and ISEE-2 were launched on 22 October 1977, and they re-entered on 26 September 1987.
The ISEE-2 was an Explorer-class daughter spacecraft, International Sun-Earth Explorer-2, was part of the mother/daughter/heliocentric mission. ISEE-2 was a 165.78 kg (365.5 lb) space probe used to study magnetic fields near the Earth. ISEE-2 was a spin-stabilized spacecraft and based on the design of the prior IMP series of spacecraft. ISEE-1 and ISEE-2 were launched on 22 October 1977, and they re-entered on 26 September 1987.
References
- ↑ Directive 2014/30/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to electromagnetic compatibility, Article 3 (Definitions), paragraph 8.
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22. (in support of MIL-STD-188).- This article incorporates public domain material from Dictionary of Military and Associated Terms . United States Department of Defense.
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