|
Grating Cheese
A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. Gratings usually consist of a single set of elongated elements, but can consist of two sets, in which case the second set is usually perpendicular to the first (as illustrated). When the two sets are perpendicular, this is also known as a wikt:grid (as in grid paper) or a mesh. As filters A grating covering a drain (as illustrated) can be a collection of iron bars (the identical, elongated elements) held together (to ensure the bars are parallel and regularly spaced) by a lighter iron frame. Gratings over drains and air vents are used as filters, to block movement of large solids (e.g. people) and to allow movement of liquids. A register is a type of grating used in heating, ventilation, and air conditioning, which transmits air, while stopping solid objects. File:Vindobona Hoher Markt-71.JPG, Grating - drain cover, ancient Roman architecture at Vindobona, Austria. File:Mont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallel (geometry)
In geometry, parallel lines are coplanar straight lines that do not intersect at any point. Parallel planes are planes in the same three-dimensional space that never meet. ''Parallel curves'' are curves that do not touch each other or intersect and keep a fixed minimum distance. In three-dimensional Euclidean space, a line and a plane that do not share a point are also said to be parallel. However, two noncoplanar lines are called ''skew lines''. Parallel lines are the subject of Euclid's parallel postulate. Parallelism is primarily a property of affine geometries and Euclidean geometry is a special instance of this type of geometry. In some other geometries, such as hyperbolic geometry, lines can have analogous properties that are referred to as parallelism. Symbol The parallel symbol is \parallel. For example, AB \parallel CD indicates that line ''AB'' is parallel to line ''CD''. In the Unicode character set, the "parallel" and "not parallel" signs have codepoint ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridge
A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, and the material used to make it, and the funds available to build it. The earliest bridges were likely made with fallen trees and stepping stones. The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge (dating from the 13th century BC, in the Peloponnese) is one of the oldest arch bridges still in existence and use. Etymology The '' Oxford English Dictionary'' traces the origin of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Frequency
In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier transform) of the structure repeat per unit of distance. The SI unit of spatial frequency is cycles per meter (m). In image-processing applications, spatial frequency is often expressed in units of cycles per millimeter (mm) or equivalently line pairs per mm. In wave propagation, the spatial frequency is also known as ''wavenumber''. Ordinary wavenumber is defined as the reciprocal of wavelength \lambda and is commonly denoted by \xi or sometimes \nu: :\xi = \frac. Angular wavenumber k, expressed in rad per m, is related to ordinary wavenumber and wavelength by :k = 2 \pi \xi = \frac. Visual perception In the study of visual perception, sinusoidal gratings are frequently used to probe the capabilities of the visual system. In these stimu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Wave
A square wave is a non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum. In an ideal square wave, the transitions between minimum and maximum are instantaneous. The square wave is a special case of a pulse wave which allows arbitrary durations at minimum and maximum amplitudes. The ratio of the high period to the total period of a pulse wave is called the duty cycle. A true square wave has a 50% duty cycle (equal high and low periods). Square waves are often encountered in electronics and signal processing, particularly digital electronics and digital signal processing. Its stochastic counterpart is a two-state trajectory. Origin and uses Square waves are universally encountered in digital switching circuits and are naturally generated by binary (two-level) logic devices. Square waves are typically generated by metal–oxide–semiconductor fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmittance
Transmittance of the surface of a material is its effectiveness in transmitting radiant energy. It is the fraction of incident electromagnetic power that is transmitted through a sample, in contrast to the transmission coefficient, which is the ratio of the transmitted to incident electric field. Internal transmittance refers to energy loss by absorption, whereas (total) transmittance is that due to absorption, scattering, reflection, etc. Mathematical definitions Hemispherical transmittance Hemispherical transmittance of a surface, denoted ''T'', is defined as :T = \frac, where *Φet is the radiant flux ''transmitted'' by that surface; *Φei is the radiant flux received by that surface. Spectral hemispherical transmittance Spectral hemispherical transmittance in frequency and spectral hemispherical transmittance in wavelength of a surface, denoted ''T''ν and ''T''λ respectively, are defined as :T_\nu = \frac, :T_\lambda = \frac, where *Φe,νt is the spectral radiant flux ... [...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] |
Waveforms
In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.David Crecraft, David Gorham, ''Electronics'', 2nd ed., , CRC Press, 2002, p. 62 In electronics, the term is usually applied to periodically varying voltages, currents, or electromagnetic fields. In acoustics, it is usually applied to steady periodic sounds—variations of pressure in air or other media. In these cases, the waveform is an attribute that is independent of the frequency, amplitude, or phase shift of the signal. The term can also be used for non-periodic signals, like chirps and pulses. The waveform of an electrical signal can be visualized in an oscilloscope or any other device that can capture and plot its value at various times, with a suitable scales in the time and value axes. The electrocardiograph is a medical device to record the waveform of the electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-slip Grating
Anti-slip steel grating (also known as slip-resistant grating) is a type of bar grating designed to prevent slippage. Steel bar grating is manufactured in a variety of methods. Welded bar grating consists of load bars electrically fuse welded to cross bars. Pressure-locked bar grating, or swaged grating, is where steel rods are forced through and locked in load bars. Riveted bar grating is where the load bars are riveted to the cross bars. There are wide varieties of trade names for each type manufactured. Perforated sheet metal types: * Diamond-shaped serrated perforated sheet metal. Examples of trade names are Grip Strut, Diamond Grip, Ry, Diamond, Grip Span, Deck Span, Grip Track. * Round hole perforated sheet metal. Examples of trade names are Perf-o-grip, Safety-grip, Shur Grip, Ry-Grip, Open Grip and Grate Lock. * Raised dimple perforated sheet metal Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Sheet metal is one of the fundam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FRP Grating
Fiberglass reinforced plastic grating (also known as FRP grating, glass reinforced plastic grating or fiberglass grating) is a composite material manufactured by combining a matrix of resin and fiberglass. Fiberglass grating does not corrode like steel grating and is therefore used in corrosive environments to reduce maintenance costs. It is used in a variety of applications including walkways and overhead platforms. FRP grating is a structural product that can be weight-bearing between spans. Types Molded FRP grating is composed of alternating directional layers of continuous glass fiber for strength, with resin to consolidate the fibers and provide the shape and corrosion-resistance. Due to its bidirectional strength, molded grating can tolerate cutouts in the panel to allow pipe or equipment penetrations without requiring additional support around the opening. Molded grating has very high impact tolerance, as well as the highest chemical resistance of any fiberglass grating. It ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiberglass
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic. Cheaper and more flexible than carbon fiber, it is stronger than many metals by weight, non- magnetic, non-conductive, transparent to electromagnetic radiation, can be molded into complex shapes, and is chemically inert under many circumstances. Applications include aircraft, boats, automobiles, bath tubs and enclosures, swimming pools, hot tubs, septic tanks, water tanks, roofing, pipes, cladding, orthopedic casts, surfboards, and external door skins. Other common names for fiberglass are glass-reinforced plastic (GRP), glass-fiber reinforced plastic (GFRP) or GF ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity tow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Parallel (geometry)")
