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Shock Stock
Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emergency ** Cardiogenic shock, resulting from dysfunction of the heart ** Distributive shock, resulting from an abnormal distribution of blood flow *** Septic shock, a result of severe infection *** Toxic shock syndrome, a specific type of severe infection *** Anaphylactic shock ** Hemorrhagic shock, from a large volume of blood loss ** Neurogenic shock, due to a high spinal cord injury disrupting the sympathetic nervous system * Cold shock response of organisms to sudden cold, especially cold water * Electric shock ** Defibrillation, electric shock to restore heart rhythm ** Electroconvulsive therapy or shock treatment, psychiatric treatment * Hydrostatic shock, from ballistic impact * Insulin shock or diabetic hypoglycemia, from too m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
English Numerals
English number words include numerals and various words derived from them, as well as a large number of words borrowed from other languages. Cardinal numbers Cardinal numbers refer to the size of a group. In English, these words are numerals. If a number is in the range 21 to 99, and the second digit is not zero, the number is typically written as two words separated by a hyphen. In English, the hundreds are perfectly regular, except that the word ''hundred'' remains in its singular form regardless of the number preceding it. So too are the thousands, with the number of thousands followed by the word "thousand". For the number one thousand it may be written 1 000 or 1000 or 1,000, for larger numbers they are written for example 10 000 or 10,000 for ease of human reading. The use of the , as a separator is avoided in some languages as it is used for a decimal placement, for example with money. As a result some style guides recommend avoidance of the comma (,) as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmotic Shock
Osmotic shock or osmotic stress is physiologic dysfunction caused by a sudden change in the solute concentration around a cell, which causes a rapid change in the movement of water across its cell membrane. Under hypertonic conditions - conditions of high concentrations of either salts, substrates or any solute in the supernatant - water is drawn out of the cells through osmosis. This also inhibits the transport of substrates and cofactors into the cell thus “shocking” the cell. Alternatively, under hypotonic conditions - when concentrations of solutes are low - water enters the cell in large amounts, causing it to swell and either burst or undergo apoptosis. All organisms have mechanisms to respond to osmotic shock, with sensors and signal transduction networks providing information to the cell about the osmolarity of its surroundings; these signals activate responses to deal with extreme conditions. Cells that have a cell wall tend to be more resistant to osmotic shock becau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock (economics)
In economics, a shock is an unexpected or unpredictable event that affects an economy, either positively or negatively. Technically, it is an unpredictable change in exogenous factors—that is, factors unexplained by an economic model—which may influence endogenous economic variables. The response of economic variables, such as GDP and employment, at the time of the shock and at subsequent times, is measured by an impulse response function. Types of shocks A technology shock is the kind resulting from a technological development that affects productivity. If the shock is due to constrained supply, it is termed a supply shock and usually results in price increases for a particular product. Supply shocks can be produced when accidents or disasters occur. The 2008 Western Australian gas crisis resulting from a pipeline explosion at Varanus Island is one example. A demand shock is a sudden change of the pattern of private expenditure, especially of consumption spending b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Shock
Thermal shock is a type of rapidly transient mechanical load. By definition, it is a mechanical load caused by a rapid change of temperature of a certain point. It can be also extended to the case of a thermal gradient, which makes different parts of an object expand by different amounts. This differential expansion can be more directly understood in terms of strain, than in terms of stress, as it is shown in the following. At some point, this stress can exceed the tensile strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will cause the object's structure to fail. Failure due to thermal shock can be prevented by: # Reducing the thermal gradient seen by the object, by changing its temperature more slowly or increasing the material's thermal conductivity # Reducing the material's coefficient of thermal expansion # Increasing its strength # Introducing built-in compressive stress, as for example in tempe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shocks And Discontinuities (magnetohydrodynamics)
In magnetohydrodynamics (MHD), shocks and discontinuities are transition layers where properties of a plasma change from one equilibrium state to another. The relation between the plasma properties on both sides of a shock or a discontinuity can be obtained from the conservative form of the MHD equations, assuming conservation of mass, momentum, energy and of \nabla \cdot \mathbf . Rankine–Hugoniot jump conditions for MHD The jump conditions across a time-independent MHD shock or discontinuity are referred as the Rankine–Hugoniot equations for MHD. In the frame moving with the shock/discontinuity, those jump conditions can be written: : \rho_1 v_ = \rho_2 v_, : B_ = B_, : \rho_1 v_^2+ p_1 + \frac=\rho_2 v_^2+ p_2 + \frac, : \rho_1 v_ \mathbf - \frac= \rho_2 v_ \mathbf - \frac, : \left(\frac\frac+\frac\right)\rho_1 v_+\frac-\frac=\left(\frac\frac+\frac\right)\rho_2 v_+\frac-\frac, : (\mathbf \times \mathbf)_ = (\mathbf \times \mathbf)_, where \rho, v, p, B are the plasma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Chlorination
Shock chlorination is a process used in many swimming pools, water wells, springs, and other water sources to reduce the bacterial and algal residue in the water. Shock chlorination is performed by mixing a large amount of sodium hypochlorite, which can be in the form of a powder or a liquid such as chlorine bleach, into the water. The common advice is that the amount added must raise the level of chlorine to 10X the level (in parts per million) of chloramines present in the pool water; this is "shocking". A lesser ratio is termed superchlorinating. Water that is being shock chlorinated should not be swum in or drunk until the sodium hypochlorite count in the water goes down to three ppm or less. Commercial sodium hypochlorite should not be mixed with commercial calcium hypochlorite, as there is a risk of explosion. Although a verb for superchlorination, "shock" is often misunderstood (through marketing and sales language) to be a unique type of product. Drawbacks While "shock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bow Shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of the stellar wind abruptly drops as a result of its approach to the magnetopause. For stars, this boundary is typically the edge of the astrosphere, where the stellar wind meets the interstellar medium. Description The defining criterion of a shock wave is that the bulk velocity of the plasma drops from "supersonic" to "subsonic", where the speed of sound cs is defined by c_s^2 = \gamma p/ \rho where \gamma is the ratio of specific heats, p is the pressure, and \rho is the density of the plasma. A common complication in astrophysics is the presence of a magnetic field. For instance, the charged particles making up the solar wind follow spiral paths along magnetic field lines. The velocity of each particle as it gyrates around a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock (fluid Dynamics)
Shock is an abrupt discontinuity in the flow field and it occurs in flows when the local flow speed exceeds the local sound speed. More specifically, it is a flow whose Mach number exceeds 1. Explanation of phenomena Shock is formed due to coalescence of various small pressure pulses. Sound waves are pressure waves and it is at the speed of the sound wave the disturbances are ''communicated'' in the medium. When an object is moving in a flow field the object sends out disturbances which propagate at the speed of sound and ''adjusts'' the remaining flow field accordingly. However, if the object itself happens to travel at speed greater than sound, then the disturbances created by the object would not have traveled and ''communicated'' to the rest of the flow field and this results in an abrupt change of property, which is termed as ''shock'' in gas dynamics terminology. Shocks are characterized by discontinuous changes in flow properties such as velocity, pressure, temperature, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oblique Shock
An oblique shock wave is a shock wave that, unlike a normal shock, is inclined with respect to the incident upstream flow direction. It will occur when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses. The upstream streamlines are uniformly deflected after the shock wave. The most common way to produce an oblique shock wave is to place a wedge into supersonic, compressible flow. Similar to a normal shock wave, the oblique shock wave consists of a very thin region across which nearly discontinuous changes in the thermodynamic properties of a gas occur. While the upstream and downstream flow directions are unchanged across a normal shock, they are different for flow across an oblique shock wave. It is always possible to convert an oblique shock into a normal shock by a Galilean transformation. Wave theory For a given Mach number, M1, and corner angle, θ, the oblique shock angle, β, and the downstream Mach number, M2, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Mount
A shock mount or isolation mount is a mechanical fastener that connects two parts elastically. They are used for shock and vibration isolation. Isolation mounts allow a piece of equipment to be securely mounted to a foundation and/or frame and, at the same time, allow it to float independently from the substrate. Uses Shock mounts can be found in a wide variety of applications. Shock mounts can be used to isolate the foundation or substrate from the dynamics of the mounted equipment. This is vital on submarines where silence is critical to mission success. Yachts also use shock mounts to dampen the noise (mainly the one transmitted throughout the structure) and increase the comfort. This is usually done through elastic supports and transmission couplings. Another common example of this are the motor and transmission mounts that are used in virtually every automobile manufactured today. Without isolation mounts, the interior noise and comfort level in today's vehicles would ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Absorber
A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Most shock absorbers are a form of dashpot (a damper which resists motion via viscous friction). Description Pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs. An automobile shock absorber contains spring-loaded check valves and orifices to control the flow of oil through an internal piston (see below). One design consideration, when designing or choosing a shock absorber, is where that energy will go. In most shock absorbers, energy is converted to heat inside the viscous fluid. In hydraulic cylinders, the hydraulic fluid heats up, while in air cylinders, the hot air is usually exhausted to the atmosphere. In other types of shock absorbers, such as electromagnetic types, the dissipated energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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