1,708 research outputs found
On the second-order temperature jump coefficient of a dilute gas
We use LVDSMC simulations to calculate the second-order temperature jump
coefficient for a dilute gas whose temperature is governed by the Poisson
equation with a constant forcing term. Both the hard sphere gas and the BGK
model of the Boltzmann equation are considered. Our results show that the
temperature jump coefficient is different from the well known linear and steady
case where the temperature is governed by the homogeneous heat conduction
(Laplace) equation
Place de la Radiotherapie dans la prise en charge therapeutique du sarcome de kaposi epidemique
Les auteurs abordent la prise en charge thérapeutique du sarcome de Kaposi associé au VIH, qui pose des problèmes d’indications thérapeutiques, certains auteurs émettant l’idée que les traitements antirétroviraux seuls pourraient suffire pour son traitement. Sur la base d’une expérience de près de dix ans pendant lesquels 720 patients ont été pris en charge, les auteurs passent d’abord en revue les différentes présentations cliniques du sarcome de kaposi associé au VIH. Ils proposent ensuite les indications thérapeutiques, et donnent enfin un peu plus longuement les modalités de la radiothérapie qu’ils proposent pour ces malades.MOTS CLES: Sarcome de Kaposi épidémique – Présentations cliniques – Indications thérapeutiques- Radiothérapi
Fluctuations of g-factors in metal nanoparticles: Effects of electron-electron interaction and spin-orbit scattering
We investigate the combined effect of spin-orbit scattering and
electron-electron interactions on the probability distribution of -factors
of metal nanoparticles. Using random matrix theory, we find that even a
relatively small interaction strength %(ratio of exchange constant and mean
level %spacing \spacing ) significantly increases -factor
fluctuations for not-too-strong spin-orbit scattering (ratio of spin-orbit rate
and single-electron level spacing 1/\tau_{\rm so} \spacing \lesssim 1), and
leads to the possibility to observe -factors larger than two.Comment: RevTex, 2 figures inserte
Volumetric formulation of lattice Boltzmann models with energy conservation
We analyze a volumetric formulation of lattice Boltzmann for compressible
thermal fluid flows. The velocity set is chosen with the desired accuracy,
based on the Gauss-Hermite quadrature procedure, and tested against controlled
problems in bounded and unbounded fluids. The method allows the simulation of
thermohydrodyamical problems without the need to preserve the exact
space-filling nature of the velocity set, but still ensuring the exact
conservation laws for density, momentum and energy. Issues related to boundary
condition problems and improvements based on grid refinement are also
investigated.Comment: 8 figure
Utilizing the Individual Placement and Support Model in the Recovery Process of Individuals with Serious Mental Illness
Individuals with serious mental illness (SMI) have a high unemployment rate when compared to individuals without mental illness. Qualitative studies have shown that many individuals with SMI desire to work and see employment as an important step in their recovery processes, but they need assistance in securing and maintaining employment. A supported employment approach that research has proven effective with the SMI population is the individual placement and support (IPS) model. Tested against other vocational rehabilitation methods, IPS results in more competitive employment outcomes. This paper reviews the literature on SMI, compares the IPS process to other employment programs, addresses counterarguments, documents the model’s impact, and provides examples of its implementation
Experimental verification of parameters in automobile crankshaft modelling for vibration analysis
In the interest of utilized more stable automobile components at high speed for reduction the vibration of mechanical system, dynamic characteristics analysis plays a vital role in complex mechanical parts. This paper introduces a clarified approach on statistical investigation and modal analysis methodology to study, predict and accurate crankshaft natural frequencies by using design of experiment (DOE). In this research, first, simulation had been done with MSC Nastran/ Patran to find out the natural frequencies in each mode shape of crankshaft as well as the verification with experiment was carried out. In order to less inaccuracy, numerous simplified crankshaft models were created by using these as input and DOE was established to acquire precise parameters of optimized crankshaft design as the second phase. This method can be further used for the optimizing the structural parameters and would provide some value basis to qualitative measure of parameters and determination of optimized structure. In Conclusion, modal verification accuracy between experimental and simulation has improved
Dynamique de croissance et taux de mortalité de Rhizophora spp. dans les mangroves de l'estuaire du Rio del Rey: Site de Bamusso (Sud-Ouest Cameroun)
Objectifs : L’objectif des présents travaux est de clarifier le stock du peuplement de Rhizophora ssp. du site par la détermination de ses paramètres de structure spatiale et d'évaluer sa croissance annuelle.Méthodologie et résultats : La méthode d'étude est celle des transects. Deux transects de 100mx10m distantes de 5km orientés WNW-ESE et perpendiculaires au principal chenal ont été établis au hasard .Chaque transect était subdivisé en trois placettes de 20mx10m et chaque placettes scindé en deux sous placettes de 20mx5m. Les mesures (Diamètre et hauteur) ont été effectuées à l'intérieur de chaque sous placette pendant trois campagnes (2009, 2012, 2014). Les résultats montrent que les diamètres moyens pour le transect1(T1) sont de 4,76 ± 0,23cm; 5,09± 0,25cm et 5,43±0,28cm contre 26,53 ± 1,72cm; 24,66 ± 1,90cm et 25,26 ± 1,93cm pour le transect2 (T2) respectivement pour 2009; 2012 et 2014. Les hauteurs moyennes varient de 4,51 ± 0,16 m (2009); 4,74 ± 0,18m (2012) et 4,98 ± 0,2m (2014) pour T1 contre 20,20± 1,22m; 18,86 ± 1,35 m et 19,29 ±1,39m pour T2. L'analyse de la croissance du peuplement montre que les diamètres d'exploitation du bois de la mangrove affectionnée par les riverains se situent dans l'intervalle (5-30cm). Le test d'ANOVA montre une différence significative (P<0,05) pour les paramètres, de structure et une différence non significative (P>0,05) de la croissance annuelle entre T1 et T2.Conclusion et application des résultats : Cette étude a montré un taux de mortalité relativement faible (m=2,27%) qui présage d'une pression anthropique faible sur cet écosystème. L'étude de la dynamique réalisée permet de recommander ce site dans le processus REDD+ pour le calcul du carbone bleu indispensable dans la lutte contre le phénomène de changement climatique. Mots clés: Transect, Diamètre; Hauteur; Nombre d'individus, BamussoGrowth dynamic and death rate of Rhizophora spp. within mangrove's forest of Rio del Rey estuary (South-West Cameroon)Objective: This study was conducted to clarify the stock of Rhizophora ssp and to assess its growth within the study area.Methodology and results: Transect method was carried out during this study. So, two transects of 100 m in length, 10 m in width and 0.1 ha in area each distance to 5km oriented WNW-ESE and perpendicular to themain channel were established randomly . Each transect was divided in three plots of 20mx10m each and each plot separated in two subplots of 20mx5m each. Measures (Diameter and height) were collected within each subplot during three data collections campaigns (2009,2012,and 2014). The results show that mean diameters of transect1(T1) were 4.76 ± 0.23cm; 5.09± 0.25cm and 5.43±0.28cm to 26.53 ± 1.72cm; 24.66 ± 1.90cm and 25.26 ± 1.93cm for transect2 (T2) respectively in 2009; 2012 et 2014. Mean height values were 4.51 ± 0.16 m (2009); 4.74 ± 0.18m (2012) and 4.98 ± 0.2m (2014) for T1 to 20.20± 1.22m; 18.86 ± 1.35 m and 19.29 ±1.39m for T2. Study of growth show that used diameters of mangrove woods by neighborhood are inside class 5-30cm. The one-way ANOVA test showed a significant difference (P<0.05) for structure parameters and no significant difference (P>0,05) for annual growth between T1 and T2.Conclusion and application of findings: This study showed a relatively weak annual death rate of trees (m=2.27%) dues to a weak anthropogenic pressure in this ecosystem. This dynamic study will recommend the site to the REDD+ process in order to estimate its blue carbon stock important to fight against climate change.Key words: Transect, Diameter, Height, Number of individuals, Bamuss
Full-field measurements of strain localisation in sandstone by neutron tomography and 3D-volumetric Digital Image Correlation
AbstractRecent studies have demonstrated that the combination of x-ray tomography during triaxial tests (“in-situ” tests) and 3D- volumetric Digital Image Correlation (3D-DIC) can provide important insight into the mechanical behaviour and deformation processes of granular materials such as sand. The application of these tools to investigate the mechanisms of failure in rocks is also of obvious interest. However, the relevant applied confining pressures for triaxial testing on rocks are higher than those on sands and therefore stronger pressure containment vessels, i.e., made of thick metal walls, are required. This makes in-situ x-ray imaging of rock deformation during triaxial tests a challenge. One possible solution to overcome this problem is to use neutrons, which should better penetrate the metal-walls of the pressure vessels. In this perspective, this work assesses the capability of neutron tomography with 3D-DIC to measure deformation fields in rock samples. Results from pre- and post-deformation neutron tomography of a Bentheim sandstone sample deformed ex-situ at 40MPa show that clear images of the internal structure can be achieved and utilised for 3D-DIC analysis to reveal the details of the 3D strain field. From these results the character of the localised deformation in the study sample can thus be described. Furthermore, comparison with analyses based on equivalent x-ray tomography imaging of the same sample confirms the effectiveness of the method in relation to the more established x-ray based approach
Boundary conditions at a fluid - solid interface
We study the boundary conditions at a fluid-solid interface using molecular
dynamics simulations covering a broad range of fluid-solid interactions and
fluid densities, and both simple and chain-molecule fluids. The slip length is
shown to be independent of the type of flow, but rather is related to the fluid
organization near the solid, as governed by the fluid-solid molecular
interactions.Comment: REVtex, to appear in Physical Review Letter
Magnetic-field dependence of energy levels in ultrasmall metal grains
We present a theory of mesoscopic fluctuations of g tensors and avoided
crossing energies in a small metal grain. The model, based on random matrix
theory, contains both the orbital and spin contributions to the g tensor. The
two contributions can be experimentally separated for weak spin-orbit coupling
while they merge in the strong coupling limit. For intermediate coupling,
substantial correlations are found between g factors of neighboring levels.Comment: 9 pages, 5 figure
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