Cleanup article date March 2008 Bohm diffusion is the diffusion of Plasma physics plasma across a magnetic field . Description Bohm diffusion is charactrerized with a diffusion coefficient equal to math D Bohm frac 1 16 , frac k BT eB math , where B is the magnetic field strength, T is the temperature, and e is the elementary charge . It was first observed in 1949 by David Bohm , E. H. S. Burhop , and Harrie Massey while studying magnetic arcs for use in isotope separation . ref D. Bohm The characteristics ... there are exceptions where the diffusion rate is lower, otherwise there would be no hope of achieving ... the exact value of the diffusion coefficient is uncertain within a factor of 2 or 3. Lyman ... Diffusion across a Magnetic Field, Physics of Fluids, Vol. 3, pp. 659 660 1960 . ref Generally diffusion can be modelled as a random walk of steps of length and time . If the diffusion is collisional, then is the mean free path and is the inverse of the collision frequency. The diffusion coefficient ... with the thermal velocity v sub th sub between collisions, and the diffusion coefficient takes the form D v sub th sub . Evidently the classical collisional diffusion is maximum when the collision frequency ... of order unity, Bohm diffusion is always greater than classical diffusion. In the common low collisionality regime, classical diffusion scales with 1 B , compared with the 1 B dependence of Bohm diffusion. This distinction is often used to distinguish between the two. In light of the calculation above, it is tempting to think of Bohm diffusion as classical diffusion with an anomalous collision rate that maximizes the transport, but the physical picture is different. Anomalous diffusion is the result ... velocity equal to E B . These eddies play a similar role to the gyro orbits in classical diffusion ... T e . The turbulent diffusion constant D v is then independent of the scale length and is approximately ... Diffusion Category Plasma physics pt Difus o de Bohm ru ... more details
Unreferenced stub auto yes date December 2009 Momentum diffusion refers to the diffusion , or spread of momentum between particles atom s or molecule s of matter , usually in the liquid state. In the case of the laminar flow of a liquid past a solid surface, momentum diffuses across the boundary layer which forms at the boundary where the solid meets the liquid. The gradient in this case occurs between the liquid in contact with the surface, which does not move at all and has zero momentum see no slip condition , and the liquid far away from the wall, which has momentum proportional to the speed at which it is flowing. The rate of transport is governed by the viscosity of the fluid and the momentum gradient. DEFAULTSORT Momentum Diffusion Category Diffusion Category Fluid dynamics Fluiddynamics stub ... more details
The diffusion equation is a partial differential equation which describes density fluctuations in a material undergoing diffusion . It is also used to describe processes exhibiting diffusive like behaviour, for instance the diffusion of alleles in a population in population genetics . Statement The equation ... r and time t and D , r is the collective diffusion coefficient for density at location r and represents the vector differential operator del . If the diffusion coefficient depends on the density ... definite matrix , the equation describes Anisotropy anisotropic diffusion, which is written for three dimensional diffusion as Equation box 1 equation math frac partial phi mathbf r ,t partial t sum ... origin The Fick s law of diffusion particle diffusion equation was originally derived by Adolf Fick in 1855. ref A. Fick, Ueber Diffusion , Pogg. Ann. Phys. Chem. 170 4. Reihe 94 , 59 86 1855 . ref Derivation The diffusion equation can be derived in a straightforward way from the continuity equation .... The diffusion equation can be obtained easily from this when combined with the phenomenological .... Discretization see also Discrete Gaussian kernel The diffusion equation is continuous ... tensor diffusion equation, in standard discretization schemes. Because direct discretization of the diffusion .... The rewritten diffusion equation used in image filtering math frac partial phi mathbf r ,t partial ... diffusion algorithm can be written as an image convolution with a varying kernel stencil of size 3 3 in 2D and 3 3 3 in 3D. See also Heat equation Fick s law of diffusion Fick s law of diffusion Second law Fick s Second Law Radiative transfer equation and diffusion theory for photon transport in biological ... in Solids. Oxford Clarendon Press 3. Crank, J. 1956 . The Mathematics of Diffusion. Oxford Clarendon Press 4. Thambynayagam, R. K. M 2011 . The Diffusion Handbook Applied Solutions for Engineers McGraw Hill External links http www.ee.byu.edu cleanroom DopConCalc.phtml Diffusion Calculator for Impurities ... more details
File Diffusion welding animation.gif thumb right Animation of the Diffusion Welding process Diffusion welding DFW is a solid state welding process by which two metal s which may be dissimilar can be bonded together. Diffusion involves the migration of atom s across the joint, due to concentration gradients. The two materials are pressed together at an elevated temperature usually between 50 and 70 of the melting point . The pressure is used to relieve the void that may occur due to the different surface topographies. The method was invented by the Soviet scientist N.F. Kazakov in 1953. ref cite web url http www.msm.cam.ac.uk phase trans 2005 Amir bond.html title Diffusion Bonding of Materials last Kazakov first N.F year 1985 publisher Pergamon Press ref Specific tooling is made for each welding application to mate the welder to the workpieces. ref http www.welding advisers.com Diffusion welding.html ref Applications DFW is usually used on sheet metal structures. Typical materials that are welded include titanium , beryllium , and zirconium . It is usually used on low volume workpieces mainly for aerospace , Nuclear power nuclear , and electronics industries. In many military aircraft diffusion bonding will help to allow for the conservation of expensive strategic materials and the reduction of manufacturing costs. Some aircraft have over 100 diffusion bonded parts, including fuselage s, outboard and inboard actuator fittings, landing gear trunnions, and nacelle frames. Notes Reflist Further reading Kalpakjian, Serope, Schmid, Steven R. Manufacturing Engineering and Technology, Fifth Edition , pp. 996 998 External links http www.key to metals.com Article51.htm Cast Nonferrous Solid State Welding, at http www.keytometals.com page.aspx?ID Home&LN EN Key to Metals http www.msm.cam.ac.uk phase trans 2005 Amir bond.html An excellent discussion of diffusion bonding by Amir Shirzadi for the UK Centre for Materials Education DEFAULTSORT Diffusion Welding Category Welding ... more details
Image Surface diffusion hopping.gif thumb 288px right Figure 1. Model of a single adatom diffusing across ... diffusion is a general process involving the motion of adatom s, molecule s, and atomic clusters ... adjacent adsorption sites on a surface, as in figure 1. Just as in bulk diffusion , this motion is typically ... display diffusion behavior that deviates from the conventional model of nearest neighbor jumps. ref Antczak, Ehrlich 2007, p.39 ref Tunneling diffusion is a particularly interesting example of an unconventional ... tunneling effect. Various analytical tools may be used to wikt elucidate elucidate surface diffusion ... diffusion are limited to well below the melting point of the substrate materials science substrate .... ref Antczak, Ehrlich 2007, p. 50, 59 ref Surface diffusion rates and mechanisms are affected by a variety ..., p. 109 ref As such, the principles of surface diffusion are critical for the chemical industry chemical ... salts used in photographic film . ref name Shust109 Kinetics Image Diffusion energy landscape.png thumb 300px right Figure 2. Diagram of the energy landscape for diffusion in one dimension. x is displacement ... adsorption sites E sub diff sub is the barrier to diffusion. Surface diffusion kinetics can be thought ... , the potential energy barrier to diffusion. Equation 1 describes the relationship math Gamma nu e E ... be smaller than the energy of desorption for diffusion to occur, otherwise desorption processes .... The manner in which diffusion takes place is dependent on the relationship between E sub diff ... factor approaches unity and E sub diff sub ceases to be a meaningful barrier to diffusion. This case, known as mobile diffusion , is relatively uncommon and has only been observed in a few ... of Fick s law of diffusion Fickian diffusion it is possible to extract both the and E sub diff sub from an Arrhenius plot of the logarithm of the diffusion coefficient, D , versus 1 T . For cases where more than one diffusion mechanism is present see below , there may be more than one E ... more details
Image M6 Diffusion Pump.jpg right 250 px thumb Six inch oil diffusion pump. Diffusion pumps use a high ... Physik volume 46 pages 357 author Gaede, W. doi 10.1002 andp.19153510304 title Die Diffusion der Gase ... as diffusion than by conventional fluid dynamics . Gaede used the name diffusion pump since his design ... with it to the exhaust. ref cite journal author D. G. Avery and R. Witty title Diffusion pumps a critical ... might be more precisely described as gas jet pump , since diffusion plays a role also in other high vacuum pumps. In modern text books, the diffusion pump is categorized as a vacuum pump Momentum transfer momentum transfer pump. The diffusion pump is widely used in both industrial and research applications. Most modern diffusion pumps use silicone oil or polyphenyl ethers as the working fluid ... pages 729 doi 10.1038 122729c0 issue 3080 bibcode 1928Natur.122..729B ref Oil diffusion pumps The oil diffusion pump is operated with an oil of low vapor pressure. Its purpose is to achieve higher ... sup 9 sup mbar , diffusion pumps today can produce pressures approaching 10 sup 10 sup mbar when properly used with modern fluids and accessories. The features that make the diffusion pump attractive ... pumping speed when compared with other types of pump used in the same vacuum range. Diffusion pumps ... an outlet pressure around 0.1 mbar. Image Calutron diffusion pumps.jpg left thumb 250 px Diffusion pumps used on the Calutron mass spectrometer s during the Manhattan Project . Image Diffusion pump schematic.svg thumb right 250 px Diagram of an oil diffusion pump The high speed jet is generated by boiling ... action. The outside of the diffusion pump is cooled using either air flow or a water line. As the vapor jet impacts the outer cooled shell of the diffusion pump, the working fluid condenses and is recovered ... pressure, flowing out through the diffusion pump outlet, where they are compressed to ambient ... s, diffusion pumps have no moving parts and as a result are quite durable and reliable. They can ... more details
Noref date August 2011 Numerical diffusion is a difficulty with computer simulation s of continua such as fluid s wherein the simulated medium exhibits a higher diffusivity than the true medium. This phenomenon can be particularly egregious when the system should not be diffusive at all, for example an ideal fluid acquiring some spurious viscosity in a numerical model. Explanation In Eulerian method Eulerian simulations , time and space are divided into a discrete grid and the continuous differential equation s of motion such as the Navier Stokes equation are discretization discretized into finite difference equation s. The discrete equations are in general more diffusion diffusive than the original differential equations, so that the simulated system behaves differently than the intended physical system. The amount and character of the difference depends on the system being simulated and the type of discretization that is used. Most fluid dynamics or Magnetohydrodynamics magnetohydrodynamic simulations seek to reduce numerical diffusion to the minimum possible, to achieve high fidelity but under certain circumstances diffusion is added deliberately into the system to avoid mathematical singularity singularities . For example, shock wave s in fluids and current sheet s in plasma physics plasma s are in some approximations infinitely thin this can cause difficulty for numerical codes. A simple way to avoid the difficulty is to add diffusion that smooths out the shock or current sheet. Higher order numerical methods including spectral methods tend to have less numerical diffusion than low order methods. Example As an example of numerical diffusion, consider an Eulerian simulation using an explicit time advance of a drop of green dye diffusing through water. If the water is flowing ... due to this sideways transfer. This numerical effect takes the form of an extra high diffusion rate. When numerical diffusion applies to the components of the momentum vector, it is called numerical ... more details
Diffusion is the process by which a new idea or new product business product is accepted by the market . The rate of diffusion is the speed that the new idea spreads from one consumer to the next. Adoption is similar to diffusion except that it deals with the psychological processes an individual goes through, rather than an aggregate market process. In economics it is more often named technological change . Theories There are several theories that purport to explain the mechanics of diffusion Two step flow of communication The two step hypothesis information and acceptance flows, via the media, first to Opinion leadership opinion leaders , then to the general population the trickle down effect products tend to be expensive at first, and therefore only accessible to the wealthy social strata in time they become less expensive and are diffused to lower and lower strata The Everett Rogers Diffusion of innovations theory for any given product category, there are five categories of product ... to software diffusion. The rate of acceptance of technology is determined by factors such as ease ... right thumb 260px The Diffusion of innovation diffusion curves of many household innovations, from the Federal Reserve Bank of Dallas, 1998 According to Everett M. Rogers, the rate of diffusion is influenced ... types of diffusion rate models Penetration models use test market data to develop acceptance ... states. Stochastic models recognize that many elements of the diffusion process are unknown but explicitly incorporate probabilistic terms. See also Bass diffusion model Coolhunting Diffusion anthropology Diffusion of innovations Early adopter marketing Marketing Marketing management Marketing plan ... model Comments and observations . In V. Mahajan & Y. Wind Eds. , Innovation Diffusion Models ... of Their Evolution 2005 New York Penguin. Rogers, Everett M. New Product Adoption and Diffusion . Journal of Consumer Research . Volume 2 March 1976 pp. 290 301. Rogers, Everett M. Diffusion of Innovations ... more details
context date October 2009 Spin diffusion describes a situation wherein the individual nuclear spin physics spins undergo continuous exchange of energy. ref name durham http www.dur.ac.uk a.m.kenwright kenwright spindiff.html EPS2 Spin Diffusion Bot generated title ref This permits Spin polarization polarization differences within the sample to be reduced on a timescale much shorter than relaxation time relaxation effects. ref name durham Notes references Category Quantum field theory Nuclear stub ... more details
refimprove date March 2010 Image Scheme facilitated diffusion in cell membrane en.svg thumb 300px right Facilitated diffusion in cell membrane, showing ion channel s and carrier proteins Not to be confused with diffusion . Facilitated diffusion is not a type of diffusion thermal motion but a type of transport process. Facilitated diffusion also known as facilitated transport or passive mediated transport is a process of passive transport as opposed to active transport , with this passive transport aided by integral membrane proteins. Facilitated diffusion is the spontaneous passage of molecules or ions across a biological membrane passing through specific transmembrane integral proteins. The facilitated diffusion may occur either across biological membrane s or through aqueous compartments of an organism. ref name isbn0 471 41759 9 cite book author Pratt, Charlotte Amerley Voet, Donald Voet, Judith G. title Fundamentals of biochemistry upgrade publisher Wiley location New York year 2002 pages 264 266 isbn 0 471 41759 9 oclc doi accessdate ref Polar molecules and charged ions are dissolved in water but they can not diffuse freely across the plasma membrane due to the hydrophobe hydrophobic nature of the fatty acid tails of phospholipid s that make up the lipid bilayer s. Only small nonpolar molecules, such as oxygen can diffuse easily across the membrane. All polar molecules are transported across cell membrane membranes by proteins that form transmembrane channels. These channels are gated so they can open and close, thus regulating the flow of ions or small polar molecules. Larger molecules are transported by transmembrane carrier proteins, such as permease s that change ... binding protein . The metabolites are not changed because no energy is required for facilitated diffusion ... Facilitated Diffusion Description and Animation Membrane transport Category Diffusion Category Transport proteins ca Difusi facilitada fr Diffusion facilit e nl Gefaciliteerde diffusie pl Dyfuzja ... more details
orphan date December 2011 A diffusion map is a Machine learning machine learning algorithm for dealing .... year 2006 title Diffusion maps url http www.pnas.org content 102 21 7426.long journal Applied and Computational Harmonic Analysis ref and Diffusion Maps and Geometric Harmonics . ref cite journal last Lafon first S.S. year 2004 title Diffusion Maps and Geometric Harmonics journal PhD thesis, Yale ... Principle Component Analysis PCA and Multi Dimensional Scaling MDS , diffusion mapping is a non linear ... local similarities at different scales, the diffusion map gives a global description of the data set. Compared with other methods, diffusion maps are robust to noise perturbation and are computationally inexpensive. Definition of Diffusion Map As explained in An Introduction to Diffusion ... to Diffusion Maps journal Techniques ref diffusion maps can be defined in four steps. Connectivity Diffusion maps try to find a relation between distance in the feature space and probability ... be guided by the application that one has in mind. Diffusion Process With the definition of connectivity between two points, we can define the diffusion matrix math L math which is also a version of Laplacian ... of math t math , we observe the data set at different scales. This is the diffusion process. The diffusion ... structure of the data set have high probability. Diffusion Distance The diffusion distance at time ... Diffusion Process Now, we can give the definition of diffusion map as math Psi t x lambda 1 t psi ... 2005 title Diffusion Maps, Spectral Clustering and Eigenfunctions of Fokker Planck Operators url ... Eigenvalues and eigenvectors eigenvectors and eigenvalues , we get the diffusion map from the original ... framework of a diffusion map is as Step 1. Given the similarity matrix L Step 2. Form the normalized ... Step 4. Use diffusion map to get the embedding matrix Y Application The paper Diffusion Maps, Spectral ... that reproduces the diffusion induced by a Fokker Planck equation . It is also explained that when ... more details
Diffusion maps,introduced by R.R. Coifman and S. Lafon in ref name DifussionMap ref name Diffusion ,is a machine ... MDS , diffusion maps is a non linear method and focus on discovering the underlying manifold that the data is embedded. By integrating local similarities at different scales, diffusion maps gives a global description of the data set. Compared with other methods, diffusion maps is robust to noise perturbation and is computationally inexpensive. Definition of Diffusion Maps Follow by ref name Introduction , Diffusion Maps can be defined in four steps. Connectivity Diffusion maps leverages the relationship between heat diffusion and random walk Markov Chain . The basic observation is that if we take ... choice should be guided by the application that one has in mind. Diffusion Process With the definition of connectivity between two points, we can define the diffusion matrix math L math it is also a version ... values of math t math , we observe the data set at different scales. This is the diffusion process. Diffusion process reveals the global geometric structure of a data set as paths along the true geometric structure of the data set have high probability. Diffusion Distance The diffusion distance at time ... y math here math w y math is a weighted function which can often treated as math w y 1 math Diffusion Process Now, we can give the definition of diffusion map as math Psi t x lambda 1 t psi 1 x , lambda ... get the diffusion map from the original data to a k dimension space which is embedded in the original space. Algorithm The basic algorithm framework of Diffusion Map is as Step 1. Given the similarity ... and eigenvalues of math M t math Step 4. Use Diffusion Map to get the embedding matrix Y Application ... the diffusion induced by a Fokker Planck equation.Also, they explained that when the data approximate ... and therefore provides a separation of the statistics and the geometry of the data. Since Diffusion ... points in the manifold the data is embedded. Based on diffusion map, there are many applications ... more details
Diagnostic infobox Name Diffusion MRI Image Illus dti.gif Caption DTI Color Map ICD10 ICD9 MeshID D038524 OPS301 OtherCodes Diffusion MRI or dMRI is a Magnetic Resonance Imaging MRI method which came into existence .... Breton title Imagerie de diffusion in vivo par r sonance journal C R Acad Sci Paris year 1985 volume ..., J title Self diffusion NMR imaging using stimulated echoes journal Journal of Magnetic Resonance ... last Taylor first D G coauthors Bushell, M C title The spatial mapping of translational diffusion coefficients ... issue 4 pages 345 349 doi 10.1088 0031 9155 30 4 009 pmid 4001161 ref It allows the mapping of the diffusion ... diffusion in tissues is not free, reflecting interactions of molecules with many obstacles, such as macromolecules ... diffusion MRI images of the normal and diseased brain were made public in 1985. ref cite journal last ... to diffusion and perfusion in neurologic disorders journal Annual Meeting of the RSNA, Chicago ... SMRM meeting, London year 1985 ref During the last 25 years, diffusion MRI has been extraordinarily ... matter disorders, as diffusion tensor imaging DTI can reveal abnormalities in white matter fiber structure and provide outstanding maps of brain connectivity ref Hagmann et al, Understanding Diffusion MR Imaging Techniques From Scalar Diffusion weighted Imaging to Diffusion Tensor Imaging and Beyond ... emerged, diffusion functional MRI DfMRI as it was suggested that with dMRI one could also get images ... detection of neuronal activation in the human brain with diffusion MRI journal Proceedings of the National ... ref Finally, the method of diffusion MRI has been shown to be also sensitive to perfusion, as the movement ..., Laval Jeantet, M title Separation of diffusion and perfusion in intravoxel incoherent motion MR imaging ... doi 10.1148 radiol.2493081301 ref In diffusion weighted imaging DWI , each image voxel three dimensional pixel has an image intensity that reflects a single best measurement of the rate of water diffusion ... traditional MRI measurements such as T1 or T2 relaxation rates. A variant of diffusion weighted ... more details
Knudsen diffusion is a means of diffusion that occurs in a long pore with a narrow diameter 2 50 nm because molecules frequently collide with the pore wall. ref cite web url http sinnott.mse.ufl.edu Backgrounds theo02 diff.html title Transport in Small Pores accessdate 2009 10 20 ref Consider the diffusion of gas molecules through very small capillary pores. If the Porosity pore diameter is smaller than the mean free path of the diffusing gas molecules and the density of the gas is low, the gas molecules collide with the pore walls more frequently than with each other. This process is known as Knudsen flow or Knudsen diffusion. The Knudsen number is a good measure of the relative importance of Knudsen diffusion. A Knudsen number much greater than one indicates Knudsen diffusion is important. In practice, Knudsen diffusion applies only to gases because the mean free path for molecules in the liquid state is very small, typically near the diameter of the molecule itself. The diffusivity for Knudsen diffusion is obtained from the self diffusion coefficient derived from the kinetic theory of gases. ref cite book first James R. last Welty first2 Charles E. last2 Wicks first3 Robert E. last3 Wilson first4 Gregory L. last4 Rorrer title Fundamentals of Momentum, Heat and Mass Transfer ... lambda u over 3 lambda over 3 sqrt 8 kappa NT over pi M A math For Knudsen diffusion, path length .... However there may be instances where both Knudsen diffusion and molecular diffusion math D AB ... to zero, the equation reduces to, math frac 1 D Ae frac 1 D AB frac 1 D KA math Knudsen self diffusion In the Knudsen diffusion regime, the molecules do not interact with one another, so that they move ... Diffusion in Rough Nanoporous Media url http www.uni leipzig.de diffusion pdf MalekCoppens JCP 031.pdf ref See also Knudsen Flow Knudsen number Diffusion Atomic diffusion Mass diffusivity References reflist Category Diffusion de Knudsen Diffusion fa pl Dyfuzja Knudsena pt Difus o ... more details
Merge from Barrier metal date October 2009 A diffusion barrier is a thin layer usually micrometres thick of metal usually placed between two other metals. It is done to act as a barrier to protect either one of the metals from corrupting the other. ref Citation last Cahn first Robert W. title Physical metallurgy page 1355 publisher Elsevier year 1996 volume 1 edition 4th url http books.google.com books?id IuEq0S4sO0wC&lpg PA1355 isbn 9780444898753 . ref Adhesion of a electroplating plated metal layer to its substrate requires a physical interlocking, inter diffusion of the deposit or a chemical bond ing between plate and substrate in order to work. The role of a diffusion barrier is to prevent or to retard the inter diffusion of the two superposed metals. Therefore, to be effective, a good diffusion barrier requires inertness with respect to adjacent materials. To obtain good adhesion and a diffusion barrier simultaneously, the bonding between layers needs to come from a chemical reaction of limited range at both boundaries. Materials providing good adhesion are not necessarily good diffusion barriers and vice versa. Consequently there are cases where two or more separate layers must be used to provide a proper interface between substrates. Selection While the choice of diffusion barrier depends on the final function, anticipated operating temperature and service life are critical parameters to select diffusion barrier materials. Many thin film metal combinations have been evaluated for their adhesion and diffusion barrier properties. Aluminum provides good conductivity Disambiguation needed date June 2011 thermal or electrical? , adhesion and reliability because of its oxygen reactivity and the self passivation properties of its oxide. Copper also easily reacts with oxygen but its oxides have poor adhesion properties. As for gold its virtue relies in its inertness, and ease ... used to form diffusion barriers for specific applications. Conductive ceramic s can be also used ... more details
Gnawa Diffusion is a France French and Algeria n Gnawa music band based in Paris , France . ref http www.timesonline.co.uk tol sport related reports article668436.ece Fashion Tribes , The Times . ref The group s lead singer, Amazigh literally meaning Free Man in Berber languages Tamazight , is the son of the Algeria n writer and poet Kateb Yacine . Although there is a strong Gnawa influence, the band is noted for its mix of reggae and roots music. Gnawa Diffusion is very popular in Algeria and is also well known in many other countries including Morocco and France. The band s lyrics are in Arabic language Arabic , berber languages Tamazight , French language French and English language English . Gnawa Diffusion started their career in 1993 with the release of the album L gitime diff rence . Members of the band Amazigh Kateb vocal and gimbri Mohamed Abdenour mandolin , banjo , krakebs , choir Pierre Bonnet bass guitar bass Philippe Bonnet drums Salah Meguiba Keyboard, oriental percussion , choir Pierre Feugier guitar , choir, krakebs Abdel Aziz Maysour Amar Chaoui percussionist, choir The lead singer s lyrics are often controversial. Themes range from discussions of poverty in Algeria or corruption in government to denunciations of global military actions and perceived imperialism. Nevertheless, in spite of a strong political direction, this band also has more entrancing numbers which focus on self determination and improvement. Discography 2007 Fucking Cowboys D JAMAZ Production 2003 Souk System Warner Music Group Warner 2002 DZ Live Next Musique 1999 Bab el Oued Kingston Musisoft ref http allmusic.com album bab el oued kingston r450221 review Review , Allmusic ref 1997 Algeria Melodie 1993 L gitime diff rence References reflist External links http www.gnawa diffusion.com ... gnawa diffusion 551.php French interview. Category Algerian musical groups de Gnawa Diffusion fr Gnawa Diffusion ru Gnawa Diffusion tr Gnawa Diffusion ... more details
orphan date February 2010 Diffusion curves are Vector graphics vector graphic primitives for creating smooth shaded images. Each diffusion curve partitions the 2D computer graphics 2D graphics space through which it is drawn, defining different colors on either side. When Rasterisation rendered , these colors then spread into the regions on either side of the curve in a way analogous to diffusion . The colors may also be defined to vary smoothly along the curve and the sharpness of the color transition from one side of the curve to the other may also be specified. ref name Orzan2008 cite journal title Diffusion Curves A Vector Representation for Smooth Shaded Images url http artis.imag.fr Publications 2008 OBWBTS08 diffusion curves.pdf format PDF last Orzan first Alexandrina coauthors Adrien Bousseau, Holger Winnem ller, Pascal Barla, Joë lle Thollot, David Salesin journal ACM Transactions on Graphics Proceedings of SIGGRAPH 2008 volume 27 year 2008 accessdate 2009 05 25 ref Diffusion curves have been discussed in relation to being a possible addition to the SVG specification. ref cite web url http www.svgopen.org 2008 papers 104 SVG in KDE title SVG in KDE Freedom of Beauty last Rusin first Zack publisher svgopen.org year 2008 accessdate 2009 05 25 ref Motivations In the original paper introducing the concept of diffusion curves, Orzan et al. describe two main motivations for them. ref name Orzan2008 Freehand Drawing Artists traditionally begin by sketching lines and shapes that represent the major, and some of the lesser, colour boundaries of the envisioned work. The use of diffusion curves supports this practice accurately as color would be added later, up to and between these sketched lines, so the lines color values are specified and their diffusion like behaviors produce an image in a manner similar to the way a traditional artist works with brushes or other ... detection integrate well with the construction of diffusion curves and so they can facilitate ... more details
In image processing and computer vision , anisotropic diffusion , also called Perona Malik diffusion .... ref name Perona Malik 1987 ref name Perona Malik 1990 ref name Sapiro 2001 Anisotropic diffusion resembles ... more and more blurred images based on a diffusion process. Each of the resulting images ... the width of the filter increases with the parameter. This diffusion process is a linear and space invariant transformation of the original image. Anisotropic diffusion is a generalization of this diffusion .... As a consequence, anisotropic diffusion is a non linear and space variant transformation of the original ... to as anisotropic diffusion by Perona and Malik even though the locally adapted filter is isotropic, but it has also been referred to as inhomogeneous and nonlinear diffusion ref name Weickert review or Perona Malik diffusion ref name J hne Hau ecker 2000 by other authors. A more general ... smoothing ref name lin94 ref name AlmLin00 or coherence enhancing diffusion ref name Weickert 1998 ... diffusion equation where the diffusion coefficient, instead of being a constant scalar, is a function .... Anisotropic diffusion is normally implemented by means of an approximation of the generalized diffusion equation each new image in the family is computed by applying this equation to the previous image. Consequently, anisotropic diffusion is an iterative process where a relatively simple set ... be a family of gray scale images, then anisotropic diffusion is defined as math frac partial I partial ... operator and math c x,y,t math is the diffusion coefficient. math c x,y,t math controls the rate of diffusion and is usually chosen as a function of the image gradient so as to preserve edges in the image. Pietro Perona and Jitendra Malik pioneered the idea of anisotropic diffusion in 1990 and proposed two functions for the diffusion coefficient math c left nabla I right e left nabla ... in the image. Motivation Let math M math denote the manifold of smooth images, then the diffusion ... more details
unreferenced date March 2011 Infobox Company company name Diffusion Pictures company logo Deleted image removed Image Diffusion Pictures logo 2.jpg company type Private foundation London , United Kingdom 2006 location London key people Nick Crossley , co founder br Jono Stevens , co founder industry Motion picture s, television homepage http diffusionpictures.co.uk diffusionpictures.co.uk Diffusion Pictures is a distributor of feature films in the United Kingdom . Formed in late 2006, its first two releases, Funny Ha Ha and Mutual Appreciation , were both from United States American director Andrew Bujalski . Diffusion then released Reprise by Norway Norwegian director, Joachim Trier and Lars Von Trier s film, The Boss of it All . The company s other releases include a documentary on Francis Bacon , the film from Beastie Boys Beastie Boy , Adam Yauch , Gunnin for That No. 1 Spot Gunnin For That 1 Spot and Azazel Jacobs Momma s Man . Films Funny Ha Ha 2007 Mutual Appreciation 2007 Reprise film Reprise 2007 The Boss of It All 2007 Bacon s Arena 2008 Gunnin for That No. 1 Spot Gunnin For That 1 Spot 2008 Momma s Man 2008 External links http www.diffusionpictures.co.uk Official website http www.facebook.com profile.php?id 698791780&ref name Diffusion Facebook http www.myspace.com diffusionpictures Diffusion MySpace Category Companies established in 2006 Category Film distributors Category Media companies of the United Kingdom film company stub ... more details
Rotational diffusion is a process by which the Statistical mechanics equilibrium statistical distribution of the overall orientation of particles or molecules is maintained or restored. Rotational diffusion is the counterpart of translational diffusion, which maintains or restores the equilibrium statistical ... Diffusion equation diffusion constants can give insight into the overall mass and its ..., there should be three rotational diffusion constants the eigenvalues of the rotational diffusion ... fluorescences Translation et diffusion de mol cules ellipsoidales journal Le Journal de Physique volume 7 issue 7 pages 1 11 ref . If two eigenvalues of the diffusion tensor are equal, the particle diffuses as a spheroid with two unique diffusion rates and three time constants. And if all eigenvalues are the same, the particle diffuses as a sphere with one time constant. The diffusion tensor may ... Einstein relation of translational diffusion , but often this is inaccurate and direct measurement is required. The rotational diffusion tensor may be determined experimentally through fluorescence ... it may be very difficult to characterize the full diffusion tensor, for example measuring two diffusion rates can sometimes be possible when there is a great difference between them, e.g. ... the rotational diffusion tensor to very high precision. Basic equations of rotational diffusion For rotational diffusion about a single axis, the mean square angular deviation in time math t math is math langle theta 2 rangle 2 D r t math where math D r math is the rotational diffusion coefficient ... f r math is the frictional drag coefficient. The relationship between the rotational diffusion coefficient ... diffusion. The rotational frictional drag coefficient for a sphere of radius math R math is math ... of Fick s law A rotational version of Fick s law of diffusion can be defined. Let each rotating molecule ... math tau l frac 1 D mathrm rot l l 1 math See also Diffusion equation Perrin friction factors Rotational ... more details
Refimprove date April 2009 In cryptography , confusion and diffusion are two properties of the operation of a secure cipher which were identified by Claude Elwood Shannon Claude Shannon in his paper Communication Theory of Secrecy Systems , published in 1949. In Shannon s original definitions, confusion refers to making the relationship between the plaintext and the ciphertext as complex and involved as possible diffusion refers to the property that the Redundancy information theory redundancy in the statistics of the plaintext is dissipated in the statistics of the ciphertext . In other words, the uniform distribution discrete non uniformity in the distribution of the individual letters and pairs of neighbouring letters in the plaintext should be redistributed into the non uniformity in the distribution of much larger structures of the ciphertext, which is much harder to detect. Diffusion means that the output bits should depend on the input bits in a very complex way. In a cipher with good diffusion, if one bit of the plaintext is changed, then the ciphertext should change completely, in an unpredictable or pseudorandom manner. In particular, for a randomly chosen input, if one flips the i th bit, then the probability that the j th output bit will change should be one half, for any i and j this is termed the Avalanche effect strict avalanche criterion . More generally, one may require that flipping a fixed set of bits should change each output bit with probability one half. One aim of confusion is to make it very hard to find the key even if one has a large number of plaintext ... bit of the key should change the ciphertext completely. The simplest way to achieve both diffusion ... diffusion and confusion. See also Substitution permutation network References Claude E. Shannon, Communication ... key cryptography ca Confusi i difusi de Diffusion Kryptologie fa fr Confusion et diffusion it Confusione e diffusione simple Confusion and diffusion ... more details
Diffusion capacitance is the capacitance due to transport of charge carrier s between two terminals of a device, for example, the diffusion of carriers from anode to cathode in forward bias mode of a diode or from emitter to base forward biased p n junction junction in active region for a transistor . In a semiconductor device with a current flowing through it for example, an ongoing transport of charge by diffusion at a particular moment there is necessarily some charge in the process of transit through the device. If the applied voltage changes to a different value and the current changes to a different value, a different amount of charge will be in transit in the new circumstances. The change in the amount of transiting charge divided by the change in the voltage causing it is the diffusion capacitance. The adjective diffusion is used because the original use of this term was for junction diodes, where the charge transport was via the diffusion mechanism. See Fick s laws of diffusion . To implement this notion quantitatively, at a particular moment in time let the voltage across the device be math V math . Now assume that the voltage changes with time slowly enough that at each moment the current is the same as the DC current that would flow at that voltage, say math I I V math the quasistatic approximation . Suppose further that the time to cross the device is the forward transit time math tau F math . In this case the amount of charge in transit through the device at this particular moment, denoted math Q math , is given by math Q I V tau F math . Consequently, the corresponding diffusion capacitance math C diff math . is math C diff begin matrix frac dQ dV end matrix begin matrix frac dI V dV end matrix tau F math . In the event the quasi static approximation does not hold, that is, for very fast voltage changes occurring in times shorter than the transit time math ... http ece www.colorado.edu bart book pncap.htm Junction capacitance DEFAULTSORT Diffusion Capacitance ... more details
Diffusion creep refers to the Deformation mechanics deformation of crystalline solids by the diffusion of Vacancy defect vacancies through their crystal lattice . ref Passchier & Trouw 1998 p. 257 ref Diffusion creep results in plastic deformation rather than brittle failure of the material. Diffusion creep is more sensitive to temperature than other deformation mechanism s. It usually takes place at high homologous temperature s i.e. within about a tenth of its absolute melting temperature . Diffusion creep is caused by the migration of Crystallographic defect crystalline defects through the lattice ... to net accumulation of defects at the faces of maximum compression by diffusion. A flow of vacancies ... rheologically more difficult substance and enhancing deformation. Types of diffusion creep Diffusion ... creep . When a crystal deforms by diffusion creep to accommodate space problems from simultaneous ... flow granular or superplastic flow . ref Twiss & Moores 2000, p. 394 ref Diffusion creep can also be simultaneous ... material moves along grain boundaries. While in Coble creep the particles move by dry diffusion, in pressure ... m math In which A is the constant of diffusion, Q the activation energy of the mechanism, R the gas ... are different for each deformation mechanism. For diffusion creep, the value of n is usually around ... by Coble creep than materials with small grains. Traces of diffusion creep It is difficult to find clear microscale evidence for diffusion creep in a crystalline material, since little structures have been identified as definite proof. A material that was deformed by diffusion creep can have flattened ... may be taken as evidence for diffusion creep. ref Gower & Simpson 1992 ref Diffusion creep is a mechanism by which the volume of the crystals can increase. Larger grain sizes can be a sign that diffusion ... engineering diffusion dislocation creep material sciences References reflist 30em Literature Gower ... rocks evidence for diffusion creep , Journal of Structural Geology 14 , p. 301 314. Passchier ... more details
background radiation temperature anisotropy in terms of the angular scale or multipole moment . Diffusion ... bonometto227228 In modern cosmology cosmological theory, diffusion damping , also called photon diffusion damping , collisionless damping ,CAN T FIND A SOURCE TO SUPPORT THIS is a physical process ... , during the epoch of recombination cosmology recombination , Photon diffusion diffusing photons .... It is a damping by diffusion, not of diffusion. ref name hu physics2 Hu, Sugiyama & Silk 1996 04 28 , p. 2 ref ANOTHER newer STORY? Photon diffusion is one of two effects which damp small ... of diffusion damping is calculated by a mathematical expression for the damping factor , which ... in the CMB. ref name jungman24 The strength of the diffusion damping is chiefly governed by the distance photons travel before being scattered diffusion length . What affect the diffusion length are primarily ... sorts of diffusion damping. The evolution of a plasma may also affect the damping process. ref name hu1213 The scale on which diffusion damping works is called the Silk scale and its value corresponds ... the Silk mass and it corresponds to the mass of the galaxies. ref name madsen99101 Introduction Diffusion ... There is no significant diffusion damping for electrons, which cannot diffuse nearly as far as photons can in similar circumstances. Thus all damping by electron diffusion is negligible when compared to photon diffusion damping. ref name padmanabhan171172 Padmanabhan 1993 06 25 , p. 171&ndash 2 ref ... in anisotropy is the damping of diffusion damping. Diffusion damping thus damps temperature and density ... 2001 06 15 , p. 256 ref Photon diffusion was first described in Joseph Silk s 1968 paper entitled ... in Astrophysical Journal The Astrophysical Journal . As such, diffusion damping is sometimes also ... ref name hu nature15 Hu 1994 06 28 , p. 15 ref Silk damping vs. diffusion damping need in depth section Magnitude The magnitude of diffusion damping is calculated as a damping factor or suppression ... more details
Error diffusion is a type of halftone halftoning in which the quantization image processing quantization residual is distributed to neighboring pixel s that have not yet been processed. Its main use is to convert a multi level image into a binary file binary image, though it has other applications. Unlike many other halftoning methods, error diffusion is classified as an area operation, because what ... , do not have these complications. Error Diffusion has the tendency to enhance edges in an image ... analog version of error diffusion. Enter the digital era Floyd Steinberg dithering Floyd and Steinberg described a system for performing error diffusion on digital images based on a simple kernel math ... & 7 & 5 & 3 1 & 3 & 5 & 3 & 1 end array right math Algorithm Description Error diffusion takes a monochrome ... diffusion involves reducing the number of quantization states to just two per channel. This makes ... is two per channel, unless otherwise stated. One dimensional error diffusion The simplest form ... pixel in the image and the process repeats. Two dimensional error diffusion One dimensional error diffusion tends to have severe image artifacts that show up as distinct vertical lines. Two dimensional error diffusion reduces the visual artifacts. The simplest algorithm is exactly like one dimensional error diffusion, except half the error is added to the next pixel, and one quarter of the error ... error diffusion. Color error diffusion The same algorithms may be applied to each of the red, green ... lightness, hue and saturation channels, so that a higher weight for error diffusion ... of these perceptive channels, if they don t scale linearly with the human vision, so that error diffusion ... error. Error diffusion with several gray levels Error Diffusion may also be used to produce ... to dark the error diffusion algorithm tends to make the next generated pixel be black. Dark to light ... effect at the expense of gray level reproduction accuracy. This results in error diffusion having a higher ... more details
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