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991.
Chérif Amrouche Huy Hoang Nguyen 《Mathematical Methods in the Applied Sciences》2008,31(18):2147-2171
This paper is devoted to some mathematical questions related to the three‐dimensional stationary Navier–Stokes equations. Our approach is based on a combination of properties of Oseen problems in ?3. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
992.
Studies on the deposition of acid and of ecotoxic heavy metals with precipitates from the atmosphere
H. W. Nürnberg P. Valenta V. D. Nguyen M. Gödde E. Urano de Carvalho 《Fresenius' Journal of Analytical Chemistry》1984,317(3-4):314-323
Summary For the input of ecotoxic heavy metals (Cd, Pb, Cu, Zn and Ni) from the atmosphere into terrestrial and aquatic ecosystems their wet deposition with rain (and snow) has been established as the deposition type of predominant significance. The wet deposition situation in the Federal Republic of Germany has been observed systematically since 1980 with a network of automated samplers of own construction distributed over the various regions of the country (German Wet Deposition Program). These regions include rural areas from the North Sea coast to the Alps as well as urban agglomerations, industrial zones and locations with particular heavy metal emissions. The analysis of the heavy metals is carried out by differential pulse stripping voltammetry or for Ni by adsorption differential pulse voltammetry. At the same time the determination of the H+-concentration by electrometric high precision pH-measurements provides for the observation period 1980–1982 a survey on the acid deposition in the various regions of the Federal Republic of Germany. Based on reliable experimental data the main contours and the dimensions of the present burden by the deposition of acid rain and the wet deposition of ecotoxic heavy metals emerge.
Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday
Guest scientist from Univ. Fed. do Ceara, Fortaleza, Brasil 相似文献
Untersuchungen über die Deposition von Säure und ökotoxischen Schwermetallen mit Niederschlägen aus der Atmosphäre
Zusammenfassung Für den Eintrag ökotoxischer Schwermetalle (Cd, Pb, Cu, Zn und Ni) aus der Atmosphäre in terrestrische und aquatische Ökosysteme hat sich die Naßdeposition als die vorherrschende Depositionsart erwiesen. Die Situation hinsichtlich der Naßdeposition in der Bundesrepublik Deutschland wird seit 1980 systematisch mit einem über das gesamte Bundesgebiet verteilten Netz automatischer Sammler eigener Entwicklung verfolgt (Deutsches Naßdepositionsprogramm). Die untersuchten Regionen schließen ländliche Gebiete von der Nordseeküste bis zu den Alpen ein sowie Ballungsräume, Industriezonen und Orte mit besonderer Schwermetallemission. Die Schwermetallanalyse erfolgt mit differentieller Pulsinversvoltammetrie oder für Ni mit differentieller Adsorptions-Pulsvoltammetrie. Gleichzeitig resultiert auf Grund präziser elektrometrischer pH-Messungen ein Überblick über die Säuredeposition in den verschiedenen Regionen des Bundesgebietes für den Beobachtungszeitraum 1980–1982. Basierend auf zuverlässigen experimentellen Daten ergaben sich die wesentlichen Konturen und die Dimensionen der gegenwärtigen Belastung der Bundesrepublik durch die Deposition von saurem Regen und die Naßdeposition ökotoxisch wirksamer Schwermetalle.
Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday
Guest scientist from Univ. Fed. do Ceara, Fortaleza, Brasil 相似文献
993.
The Solution Domain Decomposition method of Nguyen and Paik [J. Sci. Comput. 4 , 357 (1993)] originally developed in a pseudospectral context is extended for use with finite difference techniques to solve partial differential equations. The essential idea behind this method lies in an application of the superposition principle, which allows interactions between adjacent subdomains to be decoupled and the resulting equations to be solved in parallel. Several tests are performed to assess its accuracy and efficiency based on a model problem arising from thermal convection inside a fluid-saturated porous cavity with heating from a side. The results reveal a well adaptation of the methodology into the framework of finite differences. © 1995 John Wiley & Sons, Inc. 相似文献
994.
995.
Nguyen Nhu Dat 《Czechoslovak Journal of Physics》1989,39(9):1048-1058
The nonlinear dielectric function of a direct band gap semiconductor is calculated using non-equilibrium Green's function technique. The interaction between the semiconductor and the intense radiation field is assumed to occur via excitons. As an example we calculate the polariton dispersion relation and the intensity-dependent changes of refraction index for GaAs.The author would like to thank Prof. Nguyen Van Hieu for projecting the problem and helpful discussions. 相似文献
996.
997.
Graphs with Prescribed Mean Curvature on Poincare Disk 总被引:1,自引:0,他引:1
We establish the existence and uniqueness of a solution of aquasilinear elliptic equation in the unit disk of R2. Usingthis result, we obtain the existence of graphs with prescribedcurvature on the Poincaré disk. 相似文献
998.
Nguyen Tien Zung 《Letters in Mathematical Physics》1995,33(3):187-193
The main perpose of this letter is to give a topological classification of stable nondegenerate singularities of smooth integrable Hamiltonian systems. Namely, we show that all such singularities can be decomposed diffeomorphically, after a finite covering, to the direct product of simplest (codimension 1 and codimension 2 focus-focus) singularities. 相似文献
999.
V. I. Belyavskiĭ Yu. V. Kopaev Nguyen Ngoc Tuan 《Journal of Experimental and Theoretical Physics》2007,105(4):726-737
In a weakly doped quasi-two-dimensional antiferromagnet with a Fermi contour in the form of small pockets, the Coulomb repulsion gives rise to a doubly ordered superconducting state of coexisting condensates with a large pair momentum and a zero one. The pairing with the large momentum determines the superconducting transition temperature, below which the order with zero momentum coexists as an induced order until the temperature corresponding to the initiation of the phonon pairing mechanism is reached. The superconductivity-induced orbital current density wave eliminates the pairing-repulsion-caused zero points from the two-gap quasiparticle spectrum and leads to a deviation of the relative phase of the superconducting order parameter components from π. 相似文献
1000.