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Academic literature on the topic 'Approximation de la masse effective'

Author: Grafiati

Published: 4 June 2021

Last updated: 12 February 2022

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Journal articles on the topic "Approximation de la masse effective"

1

Uechi, Schun T., and Hiroshi Uechi. "The Density-Dependent Correlations among Observables in Nuclear Matter and Hyperon-Rich Neutron Stars." Advances in High Energy Physics 2009 (2009): 1–15. http://dx.doi.org/10.1155/2009/640919.

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The conservingσ-ω-ρmean-field approximation with nonlinear interactions of hadrons has been applied to examine properties of nuclear matter and hyperonic neutron stars. The nonlinear interactions that will produce density-dependent effective masses and coupling constants of hadrons are included in order to examine density correlations among properties of nuclear matter and neutron stars such as binding energy, incompressibility,K, symmetry energy,a4, hyperon-onset density, and maximum masses of neutron stars. The conditions of conserving approximations in order to maintain thermodynamic consistency to an approximation are essential for the analysis of density-dependent correlations.

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Franz, Christian, Marcel Giar, Markus Heinemann, Michael Czerner, and Christian Heiliger. "Band Structure and Effective Masses of Zn1-xMgxO." MRS Proceedings 1494 (2012): 57–63. http://dx.doi.org/10.1557/opl.2012.1709.

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ABSTRACTWe analyze the influence of the Mg concentration on several important properties of the band structure of Zn1-xMgxO alloys in wurtzite structure using ab initio calculations. For this purpose, the band structure for finite concentrations is defined in terms of the Bloch spectral density, which can be calculated within the coherent potential approximation. We investigate the concentration dependence of the band gap and the crystal-field splitting of the valence bands. The effective electron and hole masses are determined by extending the effective mass model to finite concentrations. We compare our results with experimental results and other calculations.

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Hejlová, A., and J. Blahovec. "The modified CPEM (cooked potato effective mass) method: an instrumental assessment of potato sloughing." Czech Journal of Food Sciences 28, No. 5 (October 14, 2010): 407–11. http://dx.doi.org/10.17221/225/2008-cjfs.

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The cooked potato effective mass (CPEM) method for potato sloughing assessment involves cooking the potato flakes on the sieve in a stirred water bath and periodically determining their effective mass during cooking. The final cooking curve divided into the cooking and breaking parts provides two parameters: the cooking time (CT) is the time required for starting disintegration, while the slope of the breaking part (SBP) describes the disintegration rate. The method enables a detailed analysis of the cooking properties in relation to the tuber density. The modified analysis of the cooking curve is based on polynomial approximation of the breaking part. It provides the time of cooking (CT<sub>max</sub>) required to reach the maximal disintegration rate (MDR). These new parameters represent an alternative to the existing ones, their values are easier to obtain from the individual cooking curves, and therefore they can serve as a base for further development of the CPEM tests.  

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SHU, SONG, and JIA-RONG LI. "THE CJT CALCULATION IN STUDYING NUCLEAR MATTER BEYOND MEAN FIELD APPROXIMATION." Modern Physics Letters A 23, no. 21 (July 10, 2008): 1769–80. http://dx.doi.org/10.1142/s0217732308025814.

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We have introduced the Cornwall–Jackiw–Tomboulis (CJT) resummation scheme in studying nuclear matter. Based on the CJT formalism and using Walecka model, we have derived a set of coupled Dyson equations of nucleons and mesons. Neglecting the medium effects of the mesons, the usual mean field theory (MFT) results can be obtained. The beyond MFT calculations have been performed by thermodynamic consistently determining the meson effective masses and solving the coupled gap equations for nucleons and mesons together. The numerical results for the nucleon and meson effective masses at finite temperature and chemical potential in nuclear matter are discussed.

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Bouhassoune, Mohammed, and Arno Schindlmayr. "Ab InitioStudy of Strain Effects on the Quasiparticle Bands and Effective Masses in Silicon." Advances in Condensed Matter Physics 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/453125.

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Usingab initiocomputational methods, we study the structural and electronic properties of strained silicon, which has emerged as a promising technology to improve the performance of silicon-based metal-oxide-semiconductor field-effect transistors. In particular, higher electron mobilities are observed inn-doped samples with monoclinic strain along the [110] direction, and experimental evidence relates this to changes in the effective mass as well as the scattering rates. To assess the relative importance of these two factors, we combine density-functional theory in the local-density approximation with theGWapproximation for the electronic self-energy and investigate the effect of uniaxial and biaxial strains along the [110] direction on the structural and electronic properties of Si. Longitudinal and transverse components of the electron effective mass as a function of the strain are derived from fits to the quasiparticle band structure and a diagonalization of the full effective-mass tensor. The changes in the effective masses and the energy splitting of the conduction-band valleys for uniaxial and biaxial strains as well as their impact on the electron mobility are analyzed. The self-energy corrections withinGWlead to band gaps in excellent agreement with experimental measurements and slightly larger effective masses than in the local-density approximation.

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RAJASHABALA, S., and K. NAVANEETHAKRISHNAN. "EFFECTIVE MASSES FOR DONOR BINDING ENERGIES IN QUANTUM WELL SYSTEMS." Modern Physics Letters B 20, no. 24 (October 20, 2006): 1529–41. http://dx.doi.org/10.1142/s0217984906011633.

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The donor ionization energies in a quantum well and quantum dot with finite and infinite barriers are estimated for different well dimensions. Using the effective mass (EM) approximation, calculations are presented with constant effective mass and position dependent effective masses that are different for finite and infinite cases. Our results reduce to an approximate form used by X. H. Qi et al., Phys. Rev. B58 (1998) 10578 in the finite barrier model and that of L. E. Oliveira and L. M. Falicov, Phys. Rev. B34 (1986) 8676 in the infinite barrier case. Results are presented by taking the GaAs quantum well as an example. The use of constant effective mass of 0.067m0 is justified for well dimensions ≥a* where a* is an effective Bohr radius which is about 100 Å. While Qi et al. found a maximum of 22% variation in the binding energies due to mass variation, we obtained nearly 100% variation when mass variations are included correctly.

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BLOSSIER, B., G. VON HIPPEL, N. GARRON, and T. MENDES. "NONPERTURBATIVE HQET AT ORDER 1/m." International Journal of Modern Physics D 19, no. 08n10 (August 2010): 1661–66. http://dx.doi.org/10.1142/s0218271810017858.

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We summarize the first results for masses and decay constants of bottom-strange (pseudo-scalar and vector) mesons from nonperturbatively renormalized heavy-quark effective theory (HQET), using lattice-QCD simulations in the quenched approximation.

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LIU, JIN-LONG, and JING ZHU. "VALENCE ENERGY LEVEL STRUCTURE OF Si1-xGex/Si QUANTUM DISK." International Journal of Modern Physics B 23, no. 27 (October 30, 2009): 5251–59. http://dx.doi.org/10.1142/s0217979209053758.

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In the framework of the effective mass approximation, we develop a method to study the valence energy level structure of a Si 1-x Ge x/ Si quantum disk system in the adiabatic approximation using an exact diagonalization technique. The effects of strain, finite offset, and the difference between effective masses of holes in different materials are taken into account. The influences of both the height and the radius of the disk, and the content of Ge on the valence energy level structure of the quantum disk system are discussed. Our theoretical results are useful for researching and making low-dimensional semiconductor optoelectronic devices.

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Faizan, M., Hayat Ullah, S. H. Khan, Shahid M. Ramay, Salem A. S. Qaid, Asif Mahmood, and Manzar Ali. "Carrier effective masses and thermoelectric properties of novel Ag3AuSe2 and Ag3AuTe2 compounds." International Journal of Modern Physics B 31, no. 32 (December 18, 2017): 1750253. http://dx.doi.org/10.1142/s0217979217502538.

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The carrier effective masses as well as thermoelectric and electronic properties of ternary chalcogenides compounds of the form Ag3AuX2(X = Se, Te) have been studied using first-principles method based on density functional theory. For the treatment of exchange-correlation energy, we have used the generalized gradient approximation (GGA) by Perdew, Burke and Ernzerhof (PBE-GGA) and Wu–Cohen (WU-GGA) schemes. Both the compounds (Ag3AuSe2 and Ag3AuTe2) are direct bandgap semiconductors. The p-type nature of these compounds is confirmed by the effective mass calculations. In thermoelectric measurements, different parameters (electrical conductivity, carrier concentration, Seebeck coefficient, thermal conductivity and thermoelectric power) are calculated. It is found that all these parameters increase with the increase in temperature for both the compounds. The obtained results for these compounds such as the direct bandgap nature and their high value of the thermoelectric power make them valuable candidates for different device applications.

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Vintaikin, B. Е., O. V. Kondakov, and K. G. Ivanov. "Determining Anisotropic Material Properties by Means of Simulating Transmission in a Planar Waveguide." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 83 (2019): 51–63. http://dx.doi.org/10.18698/1812-3368-2019-2-51-63.

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The paper presents investigation results concerning a magneto-optic effect occurring in the far infrared range in bismuth. The investigation involves recording transmission in a planar waveguide located in a variable magnetic field. We ran a numerical simulation of the magneto-optic spectrum shapes in the relaxation-time approximation and determined a set of parameters for the electron energy spectrum in bismuth in the effective mass tensor approximation. We found that there is a discrete function describing how relaxation time and charge carrier concentration depend on the magnetic field magnitude. The function stems from the presence of electrons with different effective masses, which are concentrated in the three equivalent L points of the Brillouin zone, and holes in the T point of the Brillouin zone, which have topologically unconnected anisotropic constant energy surfaces

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Dissertations / Theses on the topic "Approximation de la masse effective"

1

Luisier, Mathieu. "Quantum transport beyond the effective mass approximation /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17016.

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Gnadjro, Dossou. "Nombres d'ondes, masses volumiques et modules effectifs de milieux composites formés d'une matrice poro-élastique contenant des inclusions de forme cylindrique." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMLH16/document.

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On étudie la propagation d’ondes acoustiques dans un milieu poreux obéissant à la théorie de Biotet contenant une distribution aléatoire de cavités cylindriques et celle d’une onde acoustique dans un fluide contenant une distribution polydisperse aléatoire de sphères poreuses. Dans le premier cas on utilise la généralisation de Conoir-Norris de la formule de Linton-Martin. En effet, elle permet de prendre en compte le phénomène de la conversion entre les trois ondes (deux longitudinales et une transversale) se propageant naturellement dans un milieu poreux de Biot contenant une distribution aléatoire de cavités. Des expressions analytiques sont trouvées pour les nombres d’onde effectifs des ondes cohérentes dans la limite de Rayleigh (régime basse fréquence). Les approximations des masses volumiques et modules des milieux hétérogènes sont fournies jusqu’à l’ordre de c2 en concentration. Le cas limite des cavités fluides aléatoires dans une matrice élastique est également discuté. Dans le deuxième cas on détermine les nombres d’ondes, modules et masses volumiques effectifs pour des distributions polydisperses de sphères poroélastiques. Pour y parvenir, les formules récentes du nombre d’onde effectif données par Linton et Martin dans le cas dilué monodisperse ont été modifiées. Compte tenu de l’incertitude entourant la prédiction de la distribution en taille des obstacles, trois densités de probabilité différentes sont étudiées et comparées : uniforme, Schulz et log-normal. Plus précisément, la limite de Rayleigh (régime de basse fréquence) est prise en compte lorsque les longueurs d’onde peuvent être supposées très grandes par rapport à la taille des obstacles. Dans cette limite, des formules simplifiées des concentrations sont fournies en fonction du paramètre caractérisant la dispersion en taille
We study the propagation of acoustic waves in a porous medium obeying the Biot theory and containing a random distribution of cylindrical cavities and that of an acoustic wave in a fluid containing a random polydisperse distribution of porous spheres. In the first case we use the generalization by Conoir-Norris of the Linton-Martin formula. It allows to take into account the phenomenon of the conversion between the three waves (two longitudinal and one transverse) naturally propagating in a porous Biot medium containing a random distribution of cavities. Analytical expressions are found for the effective wavenumbers of coherent waves in the Rayleigh limit (low frequency regime). The approximations of the densities and heterogeneous media modules are presented up to the order of c2 in concentration. The limiting case of random fluid cavities in an elastic matrix is also discussed. In the second case the effective wavenumbers, moduli and density are determined for polydisperse distributions of poroelastic spheres. To achieve this, the recent formulas of the effective wave number given by Linton and Martin in the dilute monodisperse case have been modified. Given the uncertainty for predicting the distribution in size of obstacles, three different probability densities are studied and compared: uniform, Schulz and lognormal. More precisely, the Rayleigh limit is taken into account when the wave lengths can be assumed to be very large compared to the size of the obstacles. Within this limit, simplified formulas for concentrations are provided depending on the parameter characterizing the size dispersion

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Morgan, David C. "A Gaussian approximation to the effective potential." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26500.

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This thesis investigates some of the properties of a variational approximation to scalar field theories: a trial wavefunctional which has a gaussian form is used as a ground state ansatz for an interacting scalar field theory - the expectation value of the Hamiltonian in this state is then minimized. This we call the Gaussian Approximation; the resulting effective potential we follow others by calling the Gaussian Effective Potential (GEP). An equivalent but more general finite temperature formalism is then reviewed and used for the calculations of the GEP in this thesis. Two scalar field theories are described: ϕ⁴ theory in four dimensions (ϕ⁴₄) and ϕ⁶ theory in three dimensions (ϕ⁶₃). After showing what the Gaussian Approximation does in terms of Feynman diagrams, renormalized GEP's are calculated for both theories. Dimensional Regularization is used in the renormalization and this this is especially convenient for the GEP in ϕ⁶₃ theory because it becomes trivially renor-malizable. It is noted that ϕ⁶₃ loses its infrared asymptotic freedom in the Gaussian Approximation. Finally, it is shown how a finite temperature GEP can be calculated by finding low and high temperature expansions of the temperature terms in ϕ⁶₃ theory.
Science, Faculty of
Physics and Astronomy, Department of
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4

Jourdana, Clément. "Modélisation mathématique et simulation numérique pour des dispositifs nanoélectroniques innovants." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00645802.

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Dans cette thèse, nous nous intéressons à la modélisation et la simulation de dispositifs nanoélectroniques innovants. Premièrement, nous dérivons formellement un modèle avec masse effective pour décrire le transport quantique des électrons dans des nanostructures très fortement confinées. Des simulations numériques illustrent l'intérêt du modèle obtenu pour un dispositif simplifié mais déjà significatif. La deuxième partie est consacrée à l'étude du transport non ballistique dans ces mêmes structures confinées. Nous analysons rigoureusement un modèle de drift-diffusion et puis nous décrivons et implémentons une approche de couplage spatial classique-quantique. Enfin, nous modélisons et simulons un nanodispositif de spintronique. Plus précisement, nous étudions le renversement d'aimantation dans un matériau ferromagnétique multi-couches sous l'effet d'un courant de spin.

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5

Koh, Meng hock. "Fission-barriers and energy spectra of odd-mass actinide nuclei in self-consistent mean-field calculations." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0208/document.

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Alors qu’il existe de nombreux calculs microscopiques de barrières de fission pour des noyaux composés pair-pairs, il n’y a cependant que relativement peu de tels calculs pour des noyaux de masse impaire. Ceci est dû aux complications induites par la brisure de la symétric de reversement du sens du temps au niveau du champ moyen qui est engendrée par la présence d’un nucleon non apparié. Pour éviter cette difficulté, des calculs existants pour des noyaux de masse impaire ont tout simplement négligé ces effets de brisure de la symétrie de reversement du sens du temps.Dans ce travail, on se donne pour but d’améliorer la description des barrières de fission, aussi bien que des propriétés spectroscopiques du niveau fondamental et de l’état isomérique de fission,pour quelques isotopes de masse impaire dans la région des actinides en prenant en compte de tels effets. Ceci a été réalisé dans le cadre du formalisme de Skyrme–Hartree–Fock plus BCS avec blocking en adaptant ce formalisme à la brisure de la symétrie considérée. L’interaction résiduelle d’appariement a été approchée par une force de séniorité dont les paramètres ont été ajustés pour reproduire les différences de masse pair-impair de quelques noyaux de la région des actinides.Les énergies des têtes de bande rotationnelle de basse énergie ont été calculées dans le cadre du modèle unifié de Bohr-Mottelson pour quatre noyaux bien déformés (235U, 239Pu, 237Np, 241Am)produisant un bon accord qualitatif avec les données pour les noyaux impairs en neutrons. L’accord significativement moins bon obtenu pour les noyaux impairs en protons pourrait résulter de l’usage de l’approximation de Slater pour l’interaction d’échange de Coulomb. Les énergies de déformation de deux noyaux impairs en neutrons (235U, 239Pu) ont été calculées pour quelques configurations de particule individuelle, jusqu’après la barrières de fission externe. La symétrie axiale a été imposée tandis que la brisure de la symétrie droite-gauche (ou de parité intrinsèque) a été permise dans la région de la seconde barrière. Les hauteurs des barrières de fission pour ces noyaux impairs dépendent significativement des configurations de particule individuelle. Un accord qualitatif avec les données disponibles pour les hauteurs de barrières des noyaux impairs considérés et leurs voisins pair-pairs a été généralement obtenu
While there have been numerous microscopic calculations on fission barriers of even-even compoundnuclei, there are however, relatively few such work dedicated to odd-mass nuclei. This is dueto the complications posed by the breaking of the time-reversal symmetry at the mean-field leveldue to the presence of an unpaired nucleon. In order to circumvent this difficulty, previous fission barriercalculations of odd-mass nuclei have been performed by neglecting the effect of time-reversalsymmetry breaking. This work aims to improve on the description of fission barriers as well asthe spectroscopic properties of ground and fission-isomeric state, of some odd-mass actinide nucleiby taking the effect of time-reversal symmetry breaking into account. This has been perfomedwithin a Skyrme-Hartree-Fock-plus-BCS framework with blocking, where the BCS formalism hasbeen adapted to accomodate this symmetry breaking. The Skyrme nucleon-nucleon effective forcehas been used with various sets of parameters (SIII, SkM*, SLy5*). The residual pairing interactionhas been approximated by seniority forces whose neutron and proton parameters have beenfitted to reproduce the odd-even mass differences of some actinide nuclei. The low-lying rotationalband-head energies evaluated within the Bohr-Mottelson unified model have been determined forfour well-deformed odd-nuclei (235U, 239Pu, 237Np, 241Am) yielding a good qualitative agreementto the data for odd-neutron nuclei. The agreement was significantly less good for the odd-protonnuclei, possibly due to the use of the Slater approximation for the exchange Coulomb interaction.The deformation energies of two odd-neutron nuclei (235U and 239Pu) have been calculated forsome single-particle configurations up to a point beyond the outer fission-barrier. Axial symmetrynuclear shape has been assumed while a breaking of the left-right (or intrinsic parity) symmetryhas been allowed around the outer fission-barrier. The fission-barrier heights of such odd-neutronnuclei depend significantly on the particle configurations. A special attention has been paid tothe very important rotational correction to deformation energies. In particular, the correction ofthe moment of inertia calculated from the usual Belyaev expression was considered. Overall, aqualitative agreement with available data on fission-barrier heights for the considered odd-neutronnuclei and their even neighbours has been obtained

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Steuding, Rasa, Jörn Steuding, Kohji Matsumoto, Antanas Laurinčikas, and Ramūnas Garunkštis. "Effective uniform approximation by the Riemann zeta-function." Department of Mathematics of the Universitat Autònoma de Barcelona, 2010. http://hdl.handle.net/2237/20429.

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Jourdana, Clément. "Mathematical modeling and numerical simulation of innovative electronic nanostructures." Toulouse 3, 2011. http://www.theses.fr/2011TOU30200.

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Dans cette thèse, nous nous intéressons à la modélisation et la simulation de dispositifs nanoélectroniques innovants. Premièrement, nous dérivons formellement un modèle avec masse effective pour décrire le transport quantique des électrons dans des nanostructures très fortement confinées. Des simulations numériques illustrent l'intérêt du modèle obtenu pour un dispositif simplifié mais déjà significatif. La deuxième partie est consacrée à l'étude du transport non ballistique dans ces mêmes structures confinées. Nous analysons rigoureusement un modèle de drift-diffusion et puis nous décrivons et implémentons une approche de couplage spatial classique-quantique. Enfin, nous modélisons et simulons un nanodispositif de spintronique. Plus précisement, nous étudions le renversement d'aimantation dans un matériau ferromagnétique multi-couches sous l'effet d'un courant de spin
In this PhD thesis, we are interested in the modeling and the simulation of innovative electronic nanodevices. First, we formally derive an effective mass model describing the quantum motion of electrons in ultra-scaled confined nanostructures. Numerical simulations aim at testing the relevance of the obtained model for a simplified (but already significant) device. The second part is devoted to non-ballistic transport in these confined nanostructures. We rigorously analyse a drift-diffusion model and afterwards we describe and implement a classical-quantum spatial coupling approach. In the last part, we model and simulate a spintronic nanodevice. More precisely, we study the magnetization switching of a ferromagnetic material driven by a spin-current

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Bonnet, Florian. "Effective theories and neutrino physics." Paris 11, 2009. http://www.theses.fr/2009PA112068.

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Adjali, Mohamed Iqbal. "The soliton of the effective chiral action in the two-point approximation." Thesis, University of Oxford, 1991. http://ora.ox.ac.uk/objects/uuid:afd6bb9e-acef-4325-8d02-aaa02e456629.

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In this thesis, we study the "two-point approximation" for highly non-local effective actions, in the particular case of the Chiral Soliton Model of the nucleon. The nucleon in this model is regarded as being made of three valence quarks bound together by a meson field in a soliton form. Mesons are treated in mean field theory and the vacuum energy due to one-quark loops is included. The theory is defined with a finite cut-off in momentum space, consistent with an effective theory for the low-energy description of the strong interactions. We use the two-point approximation to calculate the vacuum correction to the chiral soliton energy for a variety of soliton profile functions, investigating the effect of different regularisation schemes. Results are little influenced by the choice of the cut-off, and are within 20% of exact calculations, done with the full inclusion of the Dirac sea. We then perform a dynamical calculation of the chiral soliton by including sea-quark effects self-consistently in the two-point approximation. We find a typical 20% (or less) deviation in the soliton energy from exact calculations. We apply a further "pole" approximation which leads to a significant algebraic simplification in the self-consistent equations. We show, in particular, that a simple numerical fit of the pole form to the two-point cut-off function yields essentially indistinguishable results from the latter. We finally calculate some static nucleon observables in the two-point approximation and find general agreement with exact calculations. In view of the results obtained, we may hope that the pole form of the twopoint approximation may prove to be a generally useful approach to similar problems involving highly non-local actions.

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Shrestha, Surendra Prakash. "An effective medium approximation and Monte Carlo simulation in subsurface flow modeling." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38642.

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Books on the topic "Approximation de la masse effective"

1

Luisier, Mathieu. Quantum transport beyond the effective mass approximation. Konstanz: Hartung-Gorre, 2007.

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2

Morawetz, Klaus. Approximations for the Selfenergy. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797241.003.0010.

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The systematic expansion of the selfenergy is presented with the help of the closure relation of chapter 7. Besides Hartree–Fock leading to meanfield kinetic equations, the random phase approximation (RPA) is shown to result into the Lennard–Balescu kinetic equation, and the ladder approximation into the Beth–Uehling–Uhlenbeck kinetic equation. The deficiencies of the ladder approximation are explored compared to the exact T-matrix by missing maximally crossed diagrams. The T-matrix provides the Bethe–Salpeter equation for the two-particle correlation functions. Vertex corrections to the RPA are presented. For a two-dimensional example, the selfenergy and effective mass are calculated. The structure factor and the pair-correlation function are introduced and calculated for various approximations.

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Morawetz, Klaus. Multiple Impurity Scattering. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797241.003.0005.

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Furnished with basic ideas about the scattering on a single impurity, the motion of a particle scattered by many randomly distributed impurities is approached. In spite of having a single particle only, this system already belongs to many-body physics as it combines randomising effects of high-angle collisions with mean-field effects due to low-angle collisions. The averaged wave function leads to the Dyson equation. Various approximations are systematically introduced and discussed ranging from Born, averaged T-matrix to coherent potential approximation. The effective medium and the effective mass as wave function renormalisations are discussed and the various approximations are accurately compared.

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4

Li, Yongcheng. Effective medium approximation and deposition of colloidal particles in fibrous and granular media. 1998.

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J, Liandrat, and Institute for Computer Applications in Science and Engineering., eds. On the effective construction of compactly supported wavelets satisfying homogenous boundary conditions on the interval. Hampton, VA: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1996.

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Bruhn, Mark J. Intentionality and Constraint in Conceptual Blending. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190457747.003.0005.

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This chapter proposes a systems-theoretic adjustment to conceptual blending theory with respect to the so-called generic space. In creative conceptualization, the generic space is not an optional by-product of conceptual mappings across previously and otherwise constituted input spaces, but rather their effective cause, and not by selecting for them but by massively constraining against anything not them. As a first approximation of the blend’s targeted or intended meaning, the generic space functions as an indispensable “proto-blend” that sets the parameters and satisfaction conditions for the resulting conceptual network. This underappreciated point is elaborated through case studies of three well-known and increasingly complex creative blends: a sentence-level metaphor (“This surgeon is a butcher!”), an extemporaneous discourse exchange (from the live radio talk show “Loveline”), and a highly iconic lyric poem (Richard Wilbur’s “Piazza di Spagna, Early Morning”).

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Vernizzi, Graziano, and Henri Orland. Complex networks. Edited by Gernot Akemann, Jinho Baik, and Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.43.

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This article deals with complex networks, and in particular small world and scale free networks. Various networks exhibit the small world phenomenon, including social networks and gene expression networks. The local ordering property of small world networks is typically associated with regular networks such as a 2D square lattice. The small world phenomenon can be observed in most scale free networks, but few small world networks are scale free. The article first provides a brief background on small world networks and two models of scale free graphs before describing the replica method and how it can be applied to calculate the spectral densities of the adjacency matrix and Laplacian matrix of a scale free network. It then shows how the effective medium approximation can be used to treat networks with finite mean degree and concludes with a discussion of the local properties of random matrices associated with complex networks.

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Eriksson, Olle, Anders Bergman, Lars Bergqvist, and Johan Hellsvik. Atomistic Spin Dynamics. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198788669.001.0001.

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The purpose of this book is to provide a theoretical foundation and an understanding of atomistic spin-dynamics, and to give examples of where the atomistic Landau-Lifshitz-Gilbert equation can and should be used. The contents involve a description of density functional theory both from a fundamental viewpoint as well as a practical one, with several examples of how this theory can be used for the evaluation of ground state properties like spin and orbital moments, magnetic form-factors, magnetic anisotropy, Heisenberg exchange parameters, and the Gilbert damping parameter. This book also outlines how interatomic exchange interactions are relevant for the effective field used in the temporal evolution of atomistic spins. The equation of motion for atomistic spin-dynamics is derived starting from the quantum mechanical equation of motion of the spin-operator. It is shown that this lead to the atomistic Landau-Lifshitz-Gilbert equation, provided a Born-Oppenheimer-like approximation is made, where the motion of atomic spins is considered slower than that of the electrons. It is also described how finite temperature effects may enter the theory of atomistic spin-dynamics, via Langevin dynamics. Details of the practical implementation of the resulting stochastic differential equation are provided, and several examples illustrating the accuracy and importance of this method are given. Examples are given of how atomistic spin-dynamics reproduce experimental data of magnon dispersion of bulk and thin-film systems, the damping parameter, the formation of skyrmionic states, all-thermal switching motion, and ultrafast magnetization measurements.

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Horing, Norman J. Morgenstern. Interacting Electron–Hole–Phonon System. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0011.

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Chapter 11 employs variational differential techniques and the Schwinger Action Principle to derive coupled-field Green’s function equations for a multi-component system, modeled as an interacting electron-hole-phonon system. The coupled Fermion Green’s function equations involve five interactions (electron-electron, hole-hole, electron-hole, electron-phonon, and hole-phonon). Starting with quantum Hamilton equations of motion for the various electron/hole creation/annihilation operators and their nonequilibrium average/expectation values, variational differentiation with respect to particle sources leads to a chain of coupled Green’s function equations involving differing species of Green’s functions. For example, the 1-electron Green’s function equation is coupled to the 2-electron Green’s function (as earlier), also to the 1-electron/1-hole Green’s function, and to the Green’s function for 1-electron propagation influenced by a nontrivial phonon field. Similar remarks apply to the 1-hole Green’s function equation, and all others. Higher order Green’s function equations are derived by further variational differentiation with respect to sources, yielding additional couplings. Chapter 11 also introduces the 1-phonon Green’s function, emphasizing the role of electron coupling in phonon propagation, leading to dynamic, nonlocal electron screening of the phonon spectrum and hybridization of the ion and electron plasmons, a Bohm-Staver phonon mode, and the Kohn anomaly. Furthermore, the single-electron Green’s function with only phonon coupling can be rewritten, as usual, coupled to the 2-electron Green’s function with an effective time-dependent electron-electron interaction potential mediated by the 1-phonon Green’s function, leading to the polaron as an electron propagating jointly with its induced lattice polarization. An alternative formulation of the coupled Green’s function equations for the electron-hole-phonon model is applied in the development of a generalized shielded potential approximation, analysing its inverse dielectric screening response function and associated hybridized collective modes. A brief discussion of the (theoretical) origin of the exciton-plasmon interaction follows.

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Book chapters on the topic "Approximation de la masse effective"

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Hamaguchi, Chihiro. "Wannier Function and Effective Mass Approximation." In Basic Semiconductor Physics, 65–80. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04656-2_3.

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Hamaguchi, Chihiro. "Wannier Function and Effective Mass Approximation." In Graduate Texts in Physics, 125–51. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66860-4_3.

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Hamaguchi, Chihiro. "Wannier Function and Effective Mass Approximation." In Basic Semiconductor Physics, 73–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03303-2_3.

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Sverdlov, Viktor. "Electron Subbands in Silicon in the Effective Mass Approximation." In Computational Microelectronics, 123–29. Vienna: Springer Vienna, 2010. http://dx.doi.org/10.1007/978-3-7091-0382-1_10.

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Jacak, Lucjan, Arkadiusz Wöjs, and Paweł Hawrylak. "Description of an Exciton in a Quantum Dot Within the Effective-Mass Approximation." In Quantum Dots, 141–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-72002-4_10.

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Barletti, Luigi, Giovanni Frosali, and Omar Morandi. "Kinetic and Hydrodynamic Models for Multi-Band Quantum Transport in Crystals." In Multi-Band Effective Mass Approximations, 3–56. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01427-2_1.

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Schliwa, Andrei, Gerald Hönig, and Dieter Bimberg. "Electronic Properties of III-V Quantum Dots." In Multi-Band Effective Mass Approximations, 57–85. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01427-2_2.

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Tomić, Stanko, and Nenad Vukmirović. "Symmetries in Multiband Hamiltonians for Semiconductor Quantum Dots." In Multi-Band Effective Mass Approximations, 87–126. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01427-2_3.

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Veprek, Ratko G., and Sebastian Steiger. "Finite Elements for k⋅p Multiband Envelope Equations." In Multi-Band Effective Mass Approximations, 129–54. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01427-2_4.

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O’Reilly, Eoin P., Oliver Marquardt, Stefan Schulz, and Aleksey D. Andreev. "Plane-Wave Approaches to the Electronic Structure of Semiconductor Nanostructures." In Multi-Band Effective Mass Approximations, 155–89. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-01427-2_5.

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Conference papers on the topic "Approximation de la masse effective"

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ZIANNI, X., and A. G. NASSIOPOULOU. "INTERBAND TRANSITIONS IN Si NANOSTRUCTURES WITHIN EFFECTIVE MASS APPROXIMATION." In Physics, Chemistry and Application of Nanostructures - Reviews and Short Notes to Nanomeeting 2003. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812796738_0005.

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Soojin Lee, Woon Jo Cho, Yang Do Kim, Il Ki Han, Won Jun Choi, Jae Gwan Park, Eun Kyu Kim, and Jung Il Lee. "Photolumineseence analysis of white-emitting si nanoparticles using effective mass approximation method." In Digest of Papers. 2004 International Microprocesses and Nanotechnology Conference, 2004. IEEE, 2004. http://dx.doi.org/10.1109/imnc.2004.245799.

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Lee, Y., K. Kakushima, K. Shiraishi, K. Natori, and H. Iwai. "Systematic Study on Size Dependences of Transport Parameters for Ballistic Nanowire-FET with Effective Mass Approximation." In 2009 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2009. http://dx.doi.org/10.7567/ssdm.2009.e-7-5.

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Ziegler, Anne, and Mathieu Luisier. "Phonon confinement effects in diffusive quantum transport simulations with the effective mass approximation and k·p method." In 2017 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD). IEEE, 2017. http://dx.doi.org/10.23919/sispad.2017.8085255.

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Rideau, D., M. Feraille, M. Szczap, C. Tavernier, and H. Jaouen. "On the validity of the effective mass approximation and the luttinger k.p model in confined and strained 2D-holes-systems." In 2008 9th International Conference on Ultimate Integration on Silicon (ULIS). IEEE, 2008. http://dx.doi.org/10.1109/ulis.2008.4527141.

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Tien, Meng-Hsuan, Tianyi Hu, and Kiran D’Souza. "Efficient Reduced-Order Modeling and Response Approximation for Cracked Structures." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67379.

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Analysis of the influence of cracks on the dynamics of structures is critical for design, failure prognosis, and structural health monitoring. Predicting the dynamics of complex cracked structures is computationally challenging for two reasons: (1) the model size is generally large, and (2) the piecewise-linear nonlinearity caused by contact eliminates the use of linear analysis tools. Recently, a technique referred to as X-Xr approach was developed to efficiently reduce the model size of cracked structures. The method employs relative coordinates to describe the motion of crack surfaces such that an effective model reduction can be achieved using Craig-Bampton component mode synthesis. More recently, a method referred to as the generalized bilinear amplitude approximation (generalized BAA) was developed to approximate the amplitude and frequency of piecewise-linear nonlinear systems. This paper modifies the generalized BAA method and combines it with the X-Xr approach to efficiently predict the dynamics of complex cracked structures. The combined method is able to estimate the amplitude and frequency of cracked systems with a reduced computational effort. The proposed approach is demonstrated on a three degree of freedom spring-mass system and a cracked cantilever beam.

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Ohno, Ken-Ichi, Manabu Shimoda, and Tatsuo Sawada. "Characteristic Parameters of a Tuned Magnetic Fluid Damper Under Magnetic Fields." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37533.

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Damping parameters of a tuned magnetic fluid damper [TMFD] using a tuned mass damper [TMD] analogy model are obtained from approximation to frequency responses of experiments used some sort of magnetic fluids in a cylindrical container. An effective mass is changed by a magnetic field from downside, however a significant change of surface shape of magnetic fluids causes strange changing tendency. It was found that other parameters are changed according to the surface shape.

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Bohn, Dieter, and Michael Wolff. "Improved Formulation to Determine Minimum Sealing Flow – Cw, min – for Different Sealing Configurations." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38465.

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Steadily increasing HP turbine inlet temperatures underline the need for effective sealing and cooling technologies. This paper presents a new approximation to determine the minimum sealing air flow Cw,min for sealing efficiencies of different rim seal geometries in the upstream cavity of an axial turbine stage. In contrast to the iteration method of Phadke and Owen the approximation does not require the knowledge of Cw,min. Only with information about the main stream and the geometry of the sealing configuration the minimum sealing air can be estimated. The approximation is based on experimental results performed in a 1.5 stage axial turbine at rotating speeds up to 9000 rpm with different Reynolds numbers 8·105 < Rec1 < 1.5·106 and 4.5·105 < Reu < 8·105 as well as different cooling gas mass flows. In order to get results, regarding the physical phenomena connected to hot gas ingestion, different measurement techniques were applied. Results of CO2 concentration measurements as well as steady pressure measurements are used for the approximation. Different sealing geometries were investigated: 1st a simple axial gap between a flat rotor disk and a flat stator disk, commonly used for industrial gas turbines, 2nd an axial lip of the rim seal on the stator combined with flat rotor disk, often found in aero engine applications, 3rd an axial lip of the rim seal on each stator and rotor and 4th a double lip on stator and single lip on rotor side. The results of Cw,min show very well the linear behavior as in the equation given by Phadke and Owen. Nevertheless the results of the approximation show a strong dependency of the gradient of the Cw,min due to the seal geometry. The gradient of Cw,min of the first geometrical configuration without any sealing lips is about 10 times higher than the gradient of configuration four with altogether 3 sealing lips. The other two configurations are in between these extremes. The result of the 2D–3D approximation with a polynomial equation η=exp∑i=02∑j=02∑k=01(Pi,j,k·(1/Cw)i·Cp1j·Gck) extend the rule of Phadke and Owen. This formulation gives the capability to optimize the sealing mass flow for different sealing configurations.

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Moretti, Vincenzo, Maurizio De Angelis, Nicola Ranieri, and Ivan Roselli. "Numerical Analysis of a MDOF Structure Protected With TMD Techniques." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77725.

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In the present paper a complete numerical study of a 1:5 scaled four-storey steel-frame structure with the application of Tuned Mass Dampers (TMD) is reported. In particular, Passive Tuned Mass Dampers (PTMD), Semi-Active Tuned Mass Dampers (SATMD), and Hybrid Tuned Mass Dampers (HTMD) were considered and compared. The initial aim of this work was to define a Simplified Equivalent Model to be conveniently utilized for simulations instead of a realistic Prototype Numerical Model in order to estimate the designing parameters of the devices with good approximation and sensible time calculation saving. Subsequently, the feasibility, the reliability and the effectiveness of the considered seismic control techniques were also assessed. The results of the numerical analysis showed how the use of a simplified model allows to estimate the designing parameters with accuracy. More importantly, the numerical results showed to what extent the several TMD techniques revealed to be effective for the seismic response reduction.

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Rechenberger, Sven, and David Mair. "Vibration Control of Piping Systems and Structures Using Tuned Mass Dampers." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65448.

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Vibrations of piping systems and structures pose significant operational and commercial risks. Due to their inherently low mechanical damping, these systems exhibit resonance frequencies with high dynamic amplification factor. When subject to external forces from flow turbulences, pressure pulsation or mechanical equipment, these systems can respond with large amplitude vibration. Tuned mass dampers (TMD) provide effective means of controlling resonant vibration and offer two major advantages compared to other vibration control means: Firstly, the vibration reduction can be accurately predicted even if the forcing function remains unknown, leading to increased reliability of the proposed solution. Secondly, the need for hot work during installation can be avoided, resulting in reduced safety risks and less disruption to plant operations. Although TMDs are widely used in civil and mechanical engineering, they are not commonly considered when controlling vibrations in the piping industry. One reason for this may be the absence of industry design guidelines. This paper provides simple mathematical models for the design and analysis of TMDs using Microsoft Excel spreadsheet calculations. A method for the approximation of mechanical systems’ dynamic behavior based on site measurements or finite element analyses is described, and practical guidance for the TMD design process provided. A series of examples shows how TMDs can be optimized to provide robust control of resonant vibrations.

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