cleanup jargon date October 2011 An electrochemicalgradient is a gradient of electrochemical potential , usually for an ion that can move across membrane . The gradient consist of two parts, the electrical potential and a difference in the chemical concentration across a membrane. The difference of electrochemical ... or active transport across a membrane is determined by the electrochemicalgradient. In mitochondria ... . An electrochemicalgradient has two components. First, the electrical component is caused ... ATP to make a sodium ion gradient and a potassium ion gradient. The electrochemical potential is used ... 2005 , for Biology 113 at the Ohio State University DEFAULTSORT ElectrochemicalGradient Category Cellular ... gradient across a cell membrane , and electrostatic energy , which accounts for an ion s tendency to move under influence of the transmembrane potential . Overview Electrochemical potential is important ... the thermodynamically favourable direction for an ion s movement across a membrane. An electrochemicalgradient is analogous to the water pressure across a hydroelectric dam . Membrane transport ... can be used to create electrochemical gradients. Chemistry The term is typically applied in contexts ... electricity battery electrode. In a battery, an electrochemical potential arising from the movement ... reaction can produce is sometimes called the standard electrochemical potential of that reaction ... across the membrane is decided by the difference in its electrochemical potential on either side of the membrane ... between the two sides of the membrane i.e. the transmembrane potential . A solute s electrochemical ... for more than one permeant ion species . Electrochemical potential is measured in the laboratory ... gradients The proton gradient can be used as intermediate energy storage for heat production .... The electrochemical potential difference between the two sides of the membrane in mitochondria ... gradient . This is used by fermenting bacteria which do not have an electron transport chain, and hydrolyze ... more details
of steepness of a line Slope other uses In vector calculus , the gradient of a scalar field is a vector ... magnitude mathematics magnitude is that rate of increase. A generalization of the gradient ... corresponding gradient is represented by blue arrows. Interpretations File Gradient of a Function.tif thumb 350px Gradient of the 2 d function math f x,y xe x 2 y 2 math is plotted as blue arrows over ... time. At each point in the room, the gradient of math T math at that point will show the direction the temperature rises most quickly. The magnitude of the gradient will determine how fast the temperature ..., y math is math H x, y math . The gradient of math H math at a point is a vector pointing in the direction ... is given by the magnitude of the gradient vector. The gradient can also be used to measure how ... as follows. If the hill height function math H math is differentiable function differentiable , then the gradient ..., the dot product of the gradient of math H math with a given unit vector is equal to the directional ... 350px The gradient of the function f x , y &minus cos sup 2 sup x cos sup 2 sup y sup 2 sup depicted as a projected vector field on the bottom plane The gradient or gradient ... , del . The notation math operatorname grad f math is also commonly used for the gradient. The gradient ... v f x . math In a rectangular coordinate system, the gradient is the vector field whose components ... directions. When a function also depends on a parameter such as time, the gradient often ... unit vectors. For example, the gradient of the function math f x,y,z 2x 3y 2 sin z math ... to represent the gradient as a row vector or column vector of its components in a rectangular coordinate system. Gradient and the derivative or differential Linear approximation to a function The gradient ... nabla f x 0 cdot x x 0 math for math x math close to math x 0 math , where math nabla f x 0 math is the gradient ... of math f math at math x math . The gradient is therefore related to the differential by the formula ... more details
is used. See also Electrochemicalgradient Membrane potential Concentration cell References ...In electrochemistry , the electrochemical potential , math bar mu math , sometimes abbreviated to ECP ... and electric charge electrostatics . Electrochemical potential is expressed in the unit of Joule ... , electrons , etc. has an electrochemical potential a quantity with units of energy at any given location ..., a species will try to move from areas with higher electrochemical potential to areas with lower electrochemical potential in equilibrium, the electrochemical potential will be constant everywhere ... them into a single potential , the electrochemical potential , which can directly give the net ... for example, two glasses of water have the same electrochemical potential for a certain chemical ... equal to the electrochemical potential difference between the two regions. Conflicting terminologies ... potential and electrochemical potential of an electron . However, in the two fields, the definitions of these two terms are sometimes swapped. In electrochemistry, the electrochemical potential ... the chemical potential is equal to the electrochemical potential minus the local electric potential energy of the electron. ref See, for example, Electrochemical Methods by Bard and Faulkner, 2nd ... constant across a device in equilibrium while the electrochemical potential is equal to the chemical ... definitions. Definition and usage In generic terms, electrochemical potential is the mechanical ... potential, where the substance is in a specified phase. Electrochemical potential can be expressed as math bar mu i mu i z iF Phi math , where math bar mu i math is the electrochemical potential ..., math z i math 0 and so math bar mu i mu i math . Electrochemical potential is important in biological ... . In cell membranes , the electrochemical potential is the sum of the chemical potential and the membrane potential . Incorrect usage The term electrochemical potential is sometimes used to mean an electrode ... more details
Infobox Organization name Electrochemical Society image image border size caption formation 1902 type headquarters Pennington, New Jersey Pennington , New Jersey location membership 8,000 language English leader title Executive Director leader name Calvo, Roque J. key people num staff budget website http www.electrochem.org The Electrochemical Society ECS is a learned society professional association based in the United States that supports scientific inquiry in the field of electrochemistry and solid state science and technology. It was founded in 1902 as the American Electrochemical Society . ECS currently has over 8,000 members in 70 countries. Journals, magazines, database Journal of the Electrochemical Society Electrochemical and Solid State Letters ECS Transactions ECS Digital Library Awards The society grants a number of awards ref cite web url http www.electrochem.org awards title The ECS Awards Program publisher The Electrochemical Society accessdate 16 January 2011 ref including the Heinz Gerischer Award ref cite web url http www.electrochem.org awards section rules euro gerischer rules.htm title European Section Gerischer Award publisher The Electrochemical Society accessdate 16 January 2011 ref and the Olin Palladium medal. References reflist External links http www.electrochem.org ECS website DEFAULTSORT Electrochemical Society Category Chemistry societies Category Organizations established in 1902 sci org stub fa it Electrochemical Society ... more details
Electrochemical kinetics is a field of electrochemistry studying the rate of electrochemical processes. Due to electrochemical phenomena unfolding at the interface between an electrode and an electrolyte, there are accompanying phenomena to electrochemical reaction which contribute to the overall reaction rate. Contributors to this field are Alexander Frumkin , Max Volmer , Julius Tafel , etc. Notes references Bibliography cite book surname Vetter name Klaus J. title Electrochemical kinetics theoretical aspects editor Academic Press cited edition year 1967 id cid Vetter url http books.google.it books?id KyWFAAAAIAAJ Category Electrochemistry fr Cin tique lectrochimique it Cinetica elettrochimica ... more details
Electrochemical engineering is the branch of engineering dealing with the technological applications of electrochemical phenomena ref http electrochem.cwru.edu encycl art e03 engineering.htm ref such as synthesis of chemicals, electrowinning and refining of metals, batteries and fuel cells , sensors, surface modification by electrodeposition and etching, separations, and corrosion . It is an overlap between electrical engineering and chemical engineering. One of the pioneers of this field of engineering was Charles Frederick Burgess . History This branch of engineering emerged gradually from chemical engineering. The works of Carl Wagner Wagner 1962 and Veniamin Levich Levich 1962 influenced the emergence of electrochemical engineering, because their work inspired so many others. Several individuals, including Tobias, Ibl, and Hine, established engineering training centers and, with their colleagues, developed important experimental and theoretical methods of study. Notes and references references See also Photoelectrochemistry Magnetoelectrochemistry Electrochemical energy conversion Chemotronics Bioelectronics Electrochemical cell Galvanic cell Isotope electrochemistry Bibliography Geoffrey A. Prentice Electrochemical Engineering Principles Edition 1 , Prentice Hall 1997 External links http electrochem.cwru.edu encycl art e03 engineering.htm Electrochemistry Encyclopedia http www.amazon.com dp 3540643869 Electrochemical Engineering Technology http www.tec.ch.tum.de Technical electrochemistry http www.9thesee.gr index.html European Symposium on Electrochemical Engineering Category Electrochemistry Category Chemical engineering de Verfahrenstechnik Elektrochemische Verfahrenstechnik fr G nie lectrochimique it Ingegneria elettrochimica ro Inginerie electrochimic ... more details
Orphan date February 2009 unreferenced date October 2006 The electrochemical window of a substance is the voltage range between which the substance doesn t get oxidized nor redox reduced . When the substance of interest is water, it is often referred to as the water window . This range is important for the efficiency of an electrode, out of this range, water gets electrolysed , spoiling the electrical energy that is intended for another electrochemical reaction. Materials Platinum very expensive boron doped CVD diamond films on titanium or niobium 3.5 1.5 V undoped, diamond does not conduct electricity Category electrochemistry ja Citation Brummer S B and Turner M J 1977 Electrochemical considerations for safe electrical stimulation of the nervous system with platinum electrodes IEEE Trans. Biomed. Eng. 24 59 63 ... more details
Electrochemical noise ECN is the generic term given to fluctuations of Electric current current and potential difference potential . When associated with corrosion is the result of stochastic pulses of current generated by sudden film rupture, crack propagation, discrete events involving metal dissolution and hydrogen discharge with gas bubble formation and detachment. The technique of measuring electrochemical noise uses no applied external signal for the collection of experimental data. The ECN technique measures the signal perturbations which are low level fluctuations of the corrosion potential between two nominally identical electrodes which can be used in the mechanistic determination of corrosion type and speed. The fluctuations are usually of low amplitude , less than 1 millivolt mV and of low frequency bandpass filtered Root mean square RMS value Direct current DC and high frequency Alternating current AC components removed . The noise corresponds with the low level frequency noise differential of the ZRA signal but has a much lower amplitude when general corrosion is involved. The technique considers the reactions occurring at the metal solution interface and suggests two currents flowing on each electrode as a result of the anodic and cathodic reactions. Once regarded as a source of bias and error that compromised electrochemical measurements it is now regarded as a rich source of information. The technique is widely used within the Corrosion engineering world as a useful Corrosion Monitoring technique. EN phenomena belongs to the general category of random low ... of solution resistance on electrochemical noise resistance measurements A theoretical analysis journal publisher volume issue page doi 2 citation last Dawson first J.L. title Electrochemical ... Electrochemical Noise Impedance Analysis of Iron in Chloride Media journal volume issue page doi 4 ASTM G199 09 ASTM G199 09 Standard Guide for Electrochemical Noise Measurement DEFAULTSORT Electrochemical ... more details
File Electrochemical Grinding.jpg thumb Electrochemical ginding process Electrochemical grinding is a process that removes electrically conductive material by grinding with a Electric charge negatively charged abrasive grinding wheel, an electrolyte fluid, and a positively charged workpiece. ref name Benedict cite first Gary F. last Benedict title Nontraditional manufacturing processes Volume 19 of Manufacturing engineering and materials processing publisher CRC Press year 1987 isbn 0824773527 pages 153 160 url http books.google.com books?id xdmNVSio8jUC&pg PA153 ref Materials removed from the workpiece stay in the electrolyte fluid. Electrochemical grinding and electrochemical machining are similar but a wheel is used instead of a tool shaped like the contour of the workpiece. Process characteristics Prose date February 2010 The wheels and workpiece are electrically conductive. Wheels used last for many grindings typically 90 of the metal is removed by electrolysis and 10 from the abrasive grinding wheel. ref cite url http books.google.com books?id E u9ARrm37oC&pg PA465 title Industrial electrochemistry authors Derek Pletcher, Frank Walsh publisher Springer isbn 0412304104 year 1990 pages 464 466 ref Capable of producing smooth edges without the burrs caused by mechanical grinding. ref Valenti, Michael, Making the Cut, Mechanical Engineering, American Society of Mechanical Engineers, 2001. http www.memagazine.org backissues membersonly nov01 features makcut makcut.html, accessed 2 23 2010 ref Does not produce appreciable heat that would distort workpiece. ref name Valenti, Making the Cut. Valenti, Making the Cut. ref Decomposes the workpiece and deposits them into the electrolyte ... supplies coolant in conventional grinding. The fluid works with the wheel to form electrochemical ... electrochemical grinding begins. ref name McGeough Disadvantages Electrochemical grinding loses ... www.tskenma.com en technology egr.php Benefits of EGR for Stainless Steel DEFAULTSORT Electrochemical ... more details
The electrochemical regeneration of activated carbon based adsorption adsorbents involves the removal of molecules adsorbed onto the surface of the adsorbent with the use of an electric current in an electrochemical cell restoring the carbon s adsorptive capacity. Electrochemical regeneration represents an alternative to activated carbon Regeneration thermal regeneration commonly used in waste water treatment applications. Common adsorbents include powdered activated carbon PAC , granular activated carbon GAC and activated carbon fibre. Regeneration for adsorbent re use In waste water treatment ... regeneration techniques such as electrochemical regeneration. Electrochemically regenerating ... of pollutant molecules, the carbon is transferred to an electrochemical cell to either the anode or the cathode in which electrochemical regeneration can occur. Principles There are several mechanisms by which passing a current through the electrochemical cell can encourage pollutant ... coauthors Flora, J. R. V title Effects of electrochemical treatment of granular activated ... that the main mechanisms are based on desorption induced regeneration as electrochemical effects ..., H title Regeneration of phenol saturated activated car bon in an electrochemical reactor journal Journal ... before adsorption adsorptive capacity after adsorption and electrochemical regeneration times 100 ... adsorbents able to regenerate 100 of their adsorptive capacity through electrochemical regeneration. ref Cite journal last Brown first N authorlink coauthors Roberts, E. P. L title Electrochemical ... and electrochemical regeneration journal Water Research volume 38 issue 13 pages 3067 3074 ... number of commercially available carbon based adsorption electrochemical regeneration systems. One ... continuous adsorption regeneration system that uses electrochemical regeneration to adsorb and destroy ... electrochemical regeneration wastewater treatment technique ref References reflist Category ... more details
Image ElectrochemCell.png thumb 250px right A demonstration electrochemical cell setup resembling the Daniell cell . The two half cells are linked by a salt bridge carrying ions between them. Electrons flow in the external circuit. An electrochemical cell is a device used for generating an electromotive force voltage and current from electrochemistry chemical reactions , or the reverse, inducing a chemical reaction by a flow of current. The current is caused by the reactions releasing and accepting electron s at the different ends of a conductor. A common example of an electrochemical cell is a standard 1.5 volt Battery electricity battery . Batteries are composed of usually multiple Galvanic cell s. An electrochemical cell consists of two half cells. The two half cells may use the same electrolyte, or they may use different electrolytes. Each half cell consists of an electrode , and an electrolyte . The chemical reactions in the cell may involve the electrolyte, the electrodes or an external substance as in fuel cell s which may use hydrogen gas as a reactant . In a full electrochemical cell, ions, atoms, or molecules from one half cell lose electrons Redox oxidation to their electrode while ions, atoms, or molecules from the other half cell gain electrons Redox reduction from their electrode. A salt bridge is often employed to provide electrical contact between two half cells with very different electrolytes&mdash to prevent the solutions from mixing. This can simply be a strip of filter paper soaked in saturated potassium nitrate V solution. Other devices for achieving separation of solutions are porous pots and gelled solutions. A porous pot is used in the Bunsen cell below between the electrodes . image bunsen cell.jpg thumb left 200px The Bunsen cell , invented by Robert ... http www.answers.com topic electrolytic cell 1 title Electrolytic cell publisher Answers.com ref An electrochemical ... Ritter Battery electricity Battery Electrochemical potential Nicad Nickel Cadmium battery Alkaline ... more details
Electrochemical fluorination ECF , or electrofluorination , is a foundational organofluorine chemistry method for the preparation of fluorocarbon based organofluorine compound s. ref name Ullmann G. Siegemund, W. Schwertfeger, A. Feiring, B. Smart, F. Behr, H. Vogel, B. McKusick Fluorine Compounds, Organic in Ullmann s Encyclopedia of Industrial Chemistry 2005, Wiley VCH, Weinheim. DOI 10.1002 14356007.a11 349 ref The general approach represents an application of electrosynthesis . The fluorinated chemical compounds produced by ECF are useful because of their distinctive solvating properties and the relative inertness of carbon fluorine bond s. Two ECF synthesis routes are commercialized and commonly applied, the Simons Process and the Phillips Petroleum Process. Additionally, it is also possible to electrofluorinate in various organic media. ref name Drake Fred G. Drakesmith Electrofluorination of Organic Compounds Topics in Current Chemistry,Vol. 193, Springer, Berlin Heidelberg, 1997. ref Prior to the development of these methods, fluorination with fluorine , a dangerous oxidant , was a dangerous and wasteful process. Also, ECF can be cost effective but it may also result in low yields. Simons Process The Simons Process entails electrolysis of a solution of an organic compound in a solution of hydrogen fluoride . An individual reaction can be described as R sub 3 sub C&ndash H HF R sub 3 sub C&ndash F H sub 2 sub In the course of a typical synthesis, this reaction occurs once for each C&ndash H bond in the precursor. The cell potential is maintained near 5&ndash 6 Volts V ... of the Electrochemical Society. ref cite journal author J. H. Simons title The Electrochemical Process for the Production of Fluorocarbons journal Journal of the Electrochemical Society year ... for anhydrous conditions. ref cite journal author Lino Conte, GianPaolo Gambaretto title Electrochemical .... The technology is sometimes called CAVE for Carbon Anode Vapor Phase Electrochemical Fluorination ... more details
Cleanup link rot date October 2011 Electrochemical machining ECM is a method of removing metal by an electrochemical process. It is normally used for mass production and is used for working extremely hard materials or materials that are difficult to machine using conventional methods. ref name Todd, H. Robert 1994 p. 198 199 Todd, H. Robert Allen, K. Dell Alting, Leo 1994 , Manufacturing Processes Reference Guide 1st ed. , Industrial Press Inc., p. 198 199, ISBN 0 8311 3049 0. ref Its use is limited to electrical conductivity electrically conductive materials. ECM can cut small or odd shaped angles, intricate contours or cavities in hardness hard and exotic metals, such as titanium aluminide s, Inconel , Waspaloy , and high nickel , cobalt , and rhenium alloys. ref name valenti Valenti, Michael, Making the Cut. Mechanical Engineering, American Society of Mechanical Engineers, 2001. http www.memagazine.org backissues membersonly nov01 features makcut makcut.html accessed 2 23 2010 ref Both external and internal geometries can be machined. ECM is often characterized as reverse electroplating , in that it removes material instead of adding it. ref name valenti It is similar in concept to electrical discharge machining EDM in that a high current is passed between an electrode and the part, through an electrolyte electrolytic material removal process having a negatively charged electrode cathode , a conductive fluid electrolyte , and a conductive workpiece anode however, in ECM there is no tool wear. ref name Todd, H. Robert 1994 p. 198 199 The ECM cutting tool is guided along the desired path close to the work but without touching the piece. Unlike EDM, however, no sparks are created. High metal removal rates are possible with ECM, with no thermal or mechanical stresses being ... Technologies and equipment for high precision electrochemical processing Metalworking navbox machopen DEFAULTSORT Electrochemical Machining Category Machining de Elektrochemisches Abtragen es Mecanizado ... more details
In physics , chemistry and biology , a potential gradient is the local derivative rate of change of the potential with respect to displacement, i.e. spatial derivative, or gradient. This quantity frequently occurs in equations of physical processes because it leads to some form of flux . In electrical engineering it refers specifically to electric potential gradient, which is equal to the electric field . Definition Elementary algebra calculus Fundamentally the expression for a potential gradient F in one dimension takes the form ref Essential Principles of Physics, P.M. Whelan, M.J. Hodgeson, 2nd Edition, 1978, John Murray, ISBN 0 7195 3382 1 ref math F frac delta phi delta x , math where is some type of potential , and x is displacement not distance , in the x direction. In the limit of infinitesimal displacements, the ratio of differences becomes a ratio of differential of a function differentials math F frac rm d phi rm d x , math In three dimensions, the resultant potential gradient ..., which can be compactly and neatly written in terms of the gradient operator mathematics operator , math bold F nabla phi , math Vector calculus The mathematical nature of a potential gradient arises ... space. For any conservative vector field F , there exists a scalar field , such that the gradient ... can be shown to be conservative, it is equal to the gradient in gravitational potential math mathbf ... gradient and field are opposite in direction, as the potential gradient increases, the gravitational ... field has identical properties to the gravitational field it is the gradient of the electric potential ... to the gradient in electric potential, a time dependent term must be added ref Introduction to Electrodynamics ... vector potential . Chemistry main Electrode potentials In an Electrochemistry Electrochemical ... standard conditions . The potential gradient is relatively abrupt, since there is an almost ... terms Category Fundamental physics concepts Category Vector calculus pl Gradient potencja u ... more details
Wiktionarypar gradient The Gradient is the rate of variation of a numerical quantity. It may refer to Slope or Grade slope grade , referring to the inclination of a road or other geographic features Image gradient , a gradual change or blending of color Color gradient Texture gradient Mathematics Gradient , in vector calculus, a vector field representing the maximum rate of increase of a scalar field or a multivariate function and the direction of this maximal rate. Gradient descent Gradient theorem Gradient method Conjugate gradient method Nonlinear conjugate gradient method Stochastic gradient descent Biology diffusion Concentration gradient , the ratio of solute concentration between two adjoining regions Potential gradient , the difference in electric charge between two adjoining regions Fluid dynamics and earth science Density gradient Pressure gradient Temperature gradient Geothermal gradient Sound speed gradient Wind gradient See also lookfrom gradient intitle gradient Graduation disambiguation Fade disambiguation disambig bs Gradijent vor cs Gradient de Gradient eo Gradiento io Gradiento homonimo ja pl Gradient simple Gradient disambiguation tl Gradient ... more details
In optimization mathematics optimization , gradient method is an algorithm to solve problems of the form math min x in mathbb R n f x math with the search directions defined by the gradient of the function at the current point. Examples of gradient method are the gradient descent and the conjugate gradient . See also col begin col break Gradient descent method Conjugate gradient method Derivation of the conjugate gradient method Nonlinear conjugate gradient method Biconjugate gradient method Biconjugate gradient stabilized method References cite book year 1997 title Optimization Algorithms and Consistent Approximations publisher Springer Verlag isbn 0 387 94971 2 author Elijah Polak Optimization algorithms DEFAULTSORT Gradient Method Category First order methods Category Optimization algorithms and methods Category Numerical linear algebra Category Gradient methods fr Algorithme du gradient ja ... more details
In vector calculus , the surface gradient is a Vector geometric vector differential operator that is similar to the conventional gradient . The distinction is that the surface gradient takes effect along a surface. For a surface math S math in a scalar field math u math , the surface gradient is defined and notated as ref R. Shankar Subramanian, http web2.clarkson.edu projects subramanian ch490 notes Boundary 20Conditions 20in 20Fluid 20Mechanics.pdf Boundary Conditions in Fluid Mechanics . ref math nabla S u nabla u mathbf hat n mathbf hat n cdot nabla u math where math mathbf hat n math is a unit Surface normal normal to the surface. Examining the definition shows that the surface gradient is the conventional gradient with the component normal to the surface removed subtracted , hence this gradient is tangent to the surface. In other words, the surface gradient is the orthographic projection of the gradient onto the surface. The surface gradient arises whenever the gradient of a quantity over a surface is important. In the study of capillary surface s for example, the gradient of spatially varying surface tension doesn t make much sense, however the surface gradient does and serves certain purposes. References Reflist Category Vector calculus bs Povr inski gradijent ... more details
Multiple issues unreferenced December 2009 orphan December 2009 wikify December 2009 Gradient related is a term used in multivariable calculus to describe a direction. A direction sequence math d k math is gradient related to math x k math if for any subsequence math x k k in K math that converges to a nonstationary point, the corresponding subsequence math d k k in K math is bounded and satisfies math limsup k rightarrow infty, k in K nabla f x k d k 0. math A gradient related direction is usually encountered in the gradient based iterative optimisation of a function math f math . At each iteration math k math the current vector is math x k math and we move in the direction math d k math , thus generating a sequence of directions. It is easy to guarantee that the directions we generate are gradient related, by for example setting them equal to the gradient at each point. DEFAULTSORT Gradient Related Category Vector calculus ... more details
In computer graphics, a color gradient sometimes called a color ramp or color progression specifies a range of position dependent color s, usually used to fill a region. ref cite book title SVG Essentials isbn 0596002238 last Eisenberg first J. David year 2002 publisher O Reilly Media pages 364 page 107 ref For example, many window managers allow the screen background to be specified as a gradient. The colors produced by a gradient vary continuously with position, producing smooth color transitions. Linear gradients File linear gradient.svg right A linear color gradient is specified by two points, and a color at each point. The colors along the line through those points are calculated using linear interpolation , then extended perpendicular to that line. In digital imaging systems, colors are typically interpolated in an RGB color space , often using gamma compression gamma compressed RGB color values, as opposed to linear. Circular gradients File radial gradient.svg right A circular gradient is specified as a circle that has one color and a focus the center of the circle that has another. Colors are calculated by linear interpolation based on distance from the focus. References reflist See also Wikibooks Colors Color gradient Image gradient Color banding Posterization Diffusion curve Category Computer graphics graphics software stub de Farbverlauf fr D grad de couleur nl Kleurengradi nt pl Gradient grafika ... more details
In mathematics , a skew gradient of a harmonic function over a simply connected domain with two real dimensions is a vector field that is everywhere orthogonal to the gradient of the function, and has the same Magnitude mathematics magnitude that the gradient has. Definition The skew gradient can be defined using complex analysis and the Cauchy Riemann equations . Let math f z x,y u x,y iv x,y math be a complex valued analytic function, where u , v are real valued scalar functions of the real variables x , y . A skew gradient is defined as math nabla perp u x,y nabla v x,y math and from the Cauchy Riemann equations , it is derived that math nabla perp u x,y frac partial u partial y , frac partial u partial x math Properties The skew gradient has two interesting properties. It is everywhere orthogonal to the gradient of u, and of the same length math nabla u x,y cdot nabla perp u x,y 0 , rVert nabla u rVert rVert nabla perp u rVert math References Refbegin Peter Olver, http www.math.umn.edu olver pdn.html Introduction to Partial Differential Equations, ch. 7, p. 232 Refend Category Differential calculus Category Generalizations of the derivative Category Linear operators in calculus Category Vector calculus ... more details
In atmospheric sciences meteorology , climatology and related fields , the pressure gradient typically ... gradient is a dimensional quantity expressed in Units of measurement units of pressure ... coordinate system coordinates of the location of interest, then the pressure gradient ... Strictly speaking, the concept of pressure gradient is a local characterization of the air more generally of the fluid under investigation . The pressure gradient is defined only at those spatial scales ... s including the Earth s atmosphere Earth s , the pressure gradient is a vector pointing roughly downwards ... or Norm mathematics norm of the pressure gradient in the troposphere is typically of the order 9 Pa m or 90 hPa km . The pressure gradient often has a small but critical horizontal component, which is largely responsible for the wind circulation. The horizontal pressure gradient is a 2 dimensional vector resulting from the projection of the pressure gradient onto a local horizontal plane. Near the Earth s surface , this horizontal pressure gradient is typically pointing towards high pressure ... on the weather situation. At mid latitude s, the typical horizontal pressure gradient may take on values ..., the pressure gradient constitutes one of the main forces acting on the air to make it move as wind. Note that the pressure gradient force points from high towards low pressure zones, it is thus oriented in the opposite direction from the pressure gradient itself. Sound waves and shock wave s are events ... also Gradient Isobar meteorology Isobar Geopotential height Geostrophic wind Primitive equations Temperature gradient References Edward N. Lorenz 1967 The nature and theory of the general circulation ... wg1 index.htm IPCC Third Assessment Report Category Atmospheric dynamics ca Gradient de pressi es Gradiente barom trico nl Drukgradi nt ja pl Gradient ci nienia pt Gradiente de press o ru simple Pressure gradient uk ... more details
Stream gradient is the grade slope grade measured by the ratio of drop in a stream per unit distance, usually expressed as Foot length feet per mile or metre s per kilometre . Hydrology and geology A high gradient indicates a steep slope and rapid volumetric flow rate flow of water i.e. more ability to erode whereas a low gradient indicates a more nearly level stream bed and sluggishly moving water, that may be able to carry only small amounts of very fine sediment . High gradient streams tend to have steep, narrow V shaped valley s, and are referred to as young streams. Low gradient streams have wider and less rugged valley s, with a tendency for the stream to meander . Fluvial Erosion A stream that flows upon a uniformly erosion erodible substrate will tend to have a steep gradient near its source, and a low gradient nearing zero as it reaches its base level . Of course, a uniform substrate would be rare in nature hard layers of rock geology rock along the way may establish a temporary base level, followed by a high gradient, or even a waterfall , as softer materials are encountered below the hard layer. Human dam s, glaciation , changes in sea level , and many other factors can also change the normal or natural gradient pattern. Topographic mapping On topographic map s, stream Grade slope gradient can be easily approximated if the scale of the map and the contour intervals are known. Contour lines form a V shape on the map, pointing upstream. By counting the number of lines ... by the length of the stream segment you can determine the stream gradient. Because stream gradient is customarily given in feet per 1000 feet, one should then measure the amount a stream segment rises and the length of the stream segment in feet, then multiply feet per foot gradient by 1000 ... crossed on a map with ten foot contours, the gradient is approximately 5.7 feet per 1000 feet, a fairly steep gradient. See also Channel types Relief ratio Rapid s waterfall Types Types of waterfall ... more details
to indicate the direction of the gradient. Dark areas indicate higher values An image gradient is a directional ... from images. In graphics software for digital image editing , the term gradient is used for a gradual ... progression . Mathematically, the gradient of a two variable function here the image intensity ... s in the horizontal and vertical directions. At each image point, the gradient vector points in the direction of largest possible intensity increase, and the length of the gradient vector corresponds ... gradient, but is still of sufficient quality to be of practical use in many applications. More precisely ... the corresponding image gradient, and it uses only integer values for the coefficients which weight the image intensities to produce the gradient approximation. The gradient of the image is one of the fundamental building blocks in image processing . For example the Canny edge detector uses image gradient ... Computer vision File Intensity image with gradient images.png thumb 400px alt Left Black and white picture of a cat. Center The same cat, displayed in a gradient image in the x direction. Appears similar to an embossed image. Right The same cat, displayed in a gradient image in the y direction. Appears similar to an embossed image. On the left, an intensity image of a cat. In the center, a gradient image in the x direction measuring horizontal change in intensity. On the right, a gradient image in the y direction measuring vertical change in intensity. Gray pixels have a small gradient black or white pixels have a large gradient. Image gradients can be used to extract information from images. Gradient images are created from the original image generally by convolving with a filter, one of the simplest being the Sobel filter for this purpose. Each pixel of a gradient image measures the change ... of direction, gradient images in the x and y directions are computed. One of the most common uses is in edge detection. After gradient images have been computed, pixels with large gradient values ... more details
Unreferenced stub auto yes date December 2009 An environmental gradient is a gradual change in abiotic factors through space or time . Environmental gradients can be related to factors such as altitude, temperature, depth, ocean proximity and soil humidity. Species Abundance ecology abundance s usually change along environmental gradients in a more or less predictive way. However, the species abundance along an envronmental gradient is not only determined by the abiotic factor but, also by the change in the biotic interaction s along the environmental gradient. At an ecotone , species Abundance ecology abundance s change relatively quick compared to the environmental gradient. The species distribution along environmental gradients has been studied intensively due to large databases of species presence data e.g. Global Biodiversity Information Facility GBIF Environmental Gradients are linked to Connectivity and natural disturbance when considering river systems. A river restoration scheme must consider all of these factors before undertaking a program as these three factors are what leads to a larger biodiversity. Each species are not found in every type of habitat or in every part of the world. Within the environment there are multiple factors which affects organisms. The organisms in the polar region can not survive the climate at the equator. See also Biome , cline biology , thermocline . DEFAULTSORT Environmental Gradient Ecology stub Category Ecology ... more details
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