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Teledeltos
Teledeltos paper is an electrically conductive paper. It is formed by a coating of carbon on one side of a sheet of paper, giving one black and one white side. Western Union developed Teledeltos paper in the late 1940s (several decades after it was already in use for mathematical modelling) for use in spark printer based fax machines and chart recorders. Teledeltos paper has several uses within engineering that are far removed from its original use in spark printers. Many of these use the paper to model the distribution of electric and other scalar fields. Use Teledeltos provides a sheet of a uniform resistor, with isotropic resistivity in each direction. As it is cheap and easily cut to shape, it may be used to make one-off resistors of any shape needed. The paper backing also forms a convenient insulator from the bench. These are usually made to represent or model some real-world example of a two-dimensional scalar field, where is it is necessary to study the field's distri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spark Printer
Spark printing is an obsolete form of computer printing and before that fax and chart recorder printing which uses a special paper coated with a conductive layer over a contrasting backing, originally black carbon over white paper but later aluminium over black paper. Printing on this paper uses pulses of electric current to burn away spots of the conductive layer. Typically, one or more electrodes are swept across the page perpendicular to the direction of paper motion to form a raster of potential burnt spots. Western Union developed the paper for this printing technology in the late 1940s, under the trademark "Teledeltos". The Western Union "Deskfax" fax machine, announced in 1948, was one of the first printers to use this technology. Spark printing was a simple and inexpensive technology. The print quality was relatively poor, but at a time when conventional printers cost hundreds of pounds, spark printers' sub-£100 price was a major selling point. The other major down ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Die Casting
Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter, and tin-based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used. The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high-volume production. Manufacture of parts using die casting is relatively simple, involving only four main steps, which keeps the incremental cost per item low. It is especially suited for a large quantity of small- to medium-sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by a very good surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field for a system of charged particles. Electric fields originate from electric charges and time-varying electric currents. Electric fields and magnetic fields are both manifestations of the electromagnetic field, one of the four fundamental interactions (also called forces) of nature. Electric fields are important in many areas of physics, and are exploited in electrical technology. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. It is also the force responsible for chemical bonding between atoms that result in molecules. The electric field is defined as a vector field that associates to each point in space the electrostatic ( Coulomb) for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conductive Paint
Conductive ink is an ink that results in a printed object which conducts electricity. It is typically created by infusing graphite or other conductive materials into ink. There has been a growing interest in replacing metallic materials with nanomaterials due to the emergence of nanotechnology. Among other nanomaterials, graphene, and carbon nanotube-based conductive ink are gaining immense popularity due to their high electrical conductivity and high surface area. Recently, more attention has been paid on using eco-friendly conductive ink using water as a solvent as compared to organic solvents since they are harmful to the environment. However, the high surface tension of water prevents its applicability. Various natural and synthetic surfactants are now used to reduce the surface tension of water and ensure uniform nanomaterials dispersibility for smooth printing and wide application.{{cite journal , last1=Khan , first1=Junaid , last2=Mariatti , first2=M. , title=Effect of natur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conductive
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases. In order for current to flow within a closed electrical circuit, it is not necessary for one charged particle to travel from the component producing the current (the current source) to those consuming it (the loads). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge ''its'' neighbor, and on and on until a particle is nudged into the consumer, thus powering it. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heatsink
A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. In computers, heat sinks are used to cool CPUs, GPUs, and some chipsets and RAM modules. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature. A heat sink is designed to maximize its surface area in contact with the cooling medium surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink. Heat sink attachment methods and thermal interface materials also affect the die temperature of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stanley Hooker
Sir Stanley George Hooker, CBE, FRS, DPhil, BSc, FRAeS, MIMechE, FAAAS, (30 September 1907 – 24 May 1984) was a mathematician and jet engine engineer. He was employed first at Rolls-Royce where he worked on the earliest designs such as the Welland and Derwent, and later at Bristol Aero Engines where he helped bring the troubled Proteus turboprop and the Olympus turbojet to market. He then designed the famous Pegasus vectored thrust turbofan used in the Hawker Siddeley Harrier. Early life Stanley George Hooker was born at Sheerness and educated at Borden Grammar School. He won a scholarship for Imperial College London to study mathematics, and in particular, hydrodynamics. He became more interested in aerodynamics, won the Busk studentship in aeronautics in 1928 and moved to Brasenose College, Oxford where he received his DPhil in this area in 1935. Rolls-Royce In late 1937, while working at the Admiralty he applied for a job at Rolls-Royce, and after being interview ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compressibility
In thermodynamics and fluid mechanics, the compressibility (also known as the coefficient of compressibility or, if the temperature is held constant, the isothermal compressibility) is a measure of the instantaneous relative volume change of a fluid or solid as a response to a pressure (or mean stress) change. In its simple form, the compressibility \kappa (denoted in some fields) may be expressed as :\beta =-\frac\frac, where is volume and is pressure. The choice to define compressibility as the negative of the fraction makes compressibility positive in the (usual) case that an increase in pressure induces a reduction in volume. The reciprocal of compressibility at fixed temperature is called the isothermal bulk modulus. Definition The specification above is incomplete, because for any object or system the magnitude of the compressibility depends strongly on whether the process is isentropic or isothermal. Accordingly, isothermal compressibility is defined: :\beta_T=-\frac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Flow
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species (mass transfer in the form of advection), either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system. Heat conduction, also called diffusion, is the direct microscopic exchanges of kinetic energy of particles (such as molecules) or quasiparticles (such as lattice waves) through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Engineering
Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and maintain mechanical systems. It is one of the oldest and broadest of the engineering branches. Mechanical engineering requires an understanding of core areas including mechanics, dynamics, thermodynamics, materials science, structural analysis, and electricity. In addition to these core principles, mechanical engineers use tools such as computer-aided design (CAD), computer-aided manufacturing (CAM), and product lifecycle management to design and analyze manufacturing plants, industrial equipment and machinery, heating and cooling systems, transport systems, aircraft, watercraft, robotics, medical devices, weapons, and others. Mechanical engineering emerged as a field during the Industrial Revolution in Europe in the 18th century; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Current Source
A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. A current source is the dual of a voltage source. The term ''current sink'' is sometimes used for sources fed from a negative voltage supply. Figure 1 shows the schematic symbol for an ideal current source driving a resistive load. There are two types. An ''independent current source'' (or sink) delivers a constant current. A ''dependent current source'' delivers a current which is proportional to some other voltage or current in the circuit. Background , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align="center" , Voltage source , Current source , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align="center" , Controlled voltage source , Controlled current source , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align=" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process. Drawing is a similar process, using the tensile strength of the material to pull it through the die. It limits the amount of change that can be performed in one step, so it is limited to simpler shapes, and multiple stages are usually needed. Drawing is the main way to produce wire. Metal bars and tubes are also often drawn. Extrusion may be continuous (theoretically producing indefinitely long material) or semi-continuous (producing many pieces). It can be done with hot or cold material. Commonly extruded materia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
