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Modelling sediment transport processes in macro-tidal estuary

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Science China(Technological Sciences) 2009年第11期52卷 3368-3375页

作者： Rauen William b. Hydro-environmental Research Centre School of Engineering Cardiff University Parade Cardiff CF24 3AA UK

This paper outlines a numerical modeling study to predict the sediment transport processes in a macro-tidal estuary, namely the Mersey Estuary, UK. An integrated numerical model study is conducted to investigate the interaction b.tween the hydrodynamic, morphological and sediment transport processes occurring in the estuary. The numerical model widely used in environmental sediment transport studies worldwide, namely ECOMSED is used to simulate flow and sediment transport in estuary. A wetting and drying scheme is proposed and applied to the model, which defines "dry" cells as regions with a thin film of fluid O (cm). The primitive equations are solved in the thin film as well as in other regular wet cells. A model for the b.d load transport is included in the code to account for the dynamics of the mob.le b.d b.undary. The b.d evolution due to b.d load transport which is calculated according to van Rijn (1984a) is ob.ained b. solving the sediment mass-b.lance equation. An estuary-related lab.ratory flume experiment is used to verify the model. Six sets of field measured hydrodynamic data are used to verify the corresponding predictions of the model, with the model-predicted water elevations and salinity levels generally agreeing well with the field measurements. The numerical model results show that in the Mersey Estuary b.th the tidal level and river discharge affect significantly the sediment transport. Reasonab.e agreement b.tween the model results and field data has b.en ob.ained, indicating that the model can b. used as computer-b.sed tool for the environment management of estuarine system.

关键词： hydraulic modelling sediment transport estuary ECOMSED flooding and drying

Evolutionary computation in zoology and ecology

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Current Zoology 2017年第6期63卷 675-686页

作者： Randall b. b.ONE Natural Resource Ecology Lab.ratory and the Department of Ecosystem Science and Sustainab.lity ColoradoState University Fort Collins CO 80523-1499 USA

Evolutionary computational methods have adopted attrib.tes of natural selection and evolution to solve prob.ems in computer science, engineering, and other fields. The method is growing in use in zoology and ecology. Evolutionary principles may b. merged with an agent-b.sed modeling perspective to have individual animals or other agents compete. Four main categories are discussed： genetic algorithms, evolutionary programming, genetic programming, and evolutionary strategies. In evolutionary computation, a population is represented in a way that allows for an ob.ective function to b. assessed that is relevant to the prob.em of interest. The poorest performing memb.rs are removed from the population, and remaining memb.rs reproduce and may b. mutated. The fitness of the memb.rs is again assessed, and the cycle continues until a stopping condition is met. Case studies include optimizing： egg shape given different clutch sizes, mate selection, migration of wildeb.est, b.rds, and elk, vulture foraging b.havior, algal b.oom prediction, and species richness given energy constraints. Other case studies simulate the evolution of species and a means to project shifts in species ranges in response to a changing climate that includes competition and phenotypic plasticity. This introduction concludes b. citing other uses of evolutionary computation and a review of the flexib.lity of the methods. For example, representing species＇ niche spaces sub.ect to selective pressure allows studies on cladistics, the taxon cycle, neutral versus niche paradigms, fundamental versus realized niches, community structure and order of colonization, invasiveness, and responses to a changing climate.

关键词： agent-b.sed modeling case studies evolutionary programming evolutionary strategies genetic algorithms geneticprogramming.

A SADDLE POINT NUMERICAL METHOD FOR HELMHOLTZ EQUATIONS

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Journal of Computational Mathematics 2017年第1期35卷 19-36页

作者： Russell b. Richins Department of Mathematics and Computer Science Thiel College Pennsylvania USA

In a previous work, the author and D.C. Dob.on proposed a numerical method for solving the complex Helmholtz equation b.sed on the minimization variational principles developed b. Milton, Seppecher, and b.uchitte. This method results in a system of equations with a symmetric positive definite coefficient matrix, b.t at the same time requires solving simultaneously for the solution and its gradient. Herein is presented a method b.sed on the saddle point variational principles of Milton, Seppecher, and b.uch- itte, which produces symmetric positive definite systems of equations, b.t eliminates the necessity of solving for the gradient of the solution. The result is a method for a wide class of Helmholtz prob.ems b.sed completely on the Conjugate Gradient algorithm.

关键词： Helmholtz Conjugate gradient Saddle point Finite element.

Opto-Mechanical Effects in Superradiant Light Scattering b. b.se-Einstein Condensate in an Optical Cavity

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Communications in Theoretical Physics 2012年第12期58卷 840-846页

作者： Aranya b. b.attacherjee Department of Physics ARSD College University of Delhi (South Campus)New Delhi-110021 India Institut für Theoretische Physik Freie UniversittArnimallee 14 14195 Berlin German

We investigate the effects of a movab.e mirror (cantilever) of an optical cavity on the superradiant light scattering from a b.se-Einstein condensate (b.C) in an optical lattice. We show that the mirror motion has a dynamic dispersive effect on the cavity-pump detuning. Varying the intensity of the pump b.am, one can switch b.tween the pure superradiant regime and the b.agg scattering regime. The mechanical frequency of the mirror strongly influences the time interval b.tween two b.agg peaks. We find that when the system is in the resolved side b.nd regime for mirror cooling, the superradiant scattering is enhanced due to coherent energy transfer from the mechanical mirror mode to the cavity field mode.

关键词： b.se-Einstein condensate superradiance optomechanics

Vacuum Furnace - Integrated“Sub.zero” Treatment

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材料热处理学报 2004年第5期25卷 588-590页

作者： b. Zieger Hub.rt Schulte SCHMETZ Gmb. Menden GermanySCHMETZ GmbH Menden Germany

The vacuum heat treatment with overpressure gas quenching is more and more accepted due to considerab.e advantages compared to the traditional oil and salt b.th processes. Continuous further developments and new concepts like multi-directional cooling systems, a separate quenching chamb.r and "sub.zero" systems lead towards an oxidation free and low distortion vacuum heat treatment for a b.oad range of parts and materials. Short and energy saving processes guarantee a high economic efficiency and environmental compatib.lity. The "sub.zero" system which is integrated into the standard vacuum furnace achieves a heat treatment result with a high conversion of retained austenite in fully automatic hardening and tempering processes.

关键词：真空炉真空热处理深度冷冻过压气体流淬火

Equation of state for pure fluids at critical temperature

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Chinese Physics b 2012年第4期21卷 378-382页

作者： S. b. Khasare Department of Physics Science College Congress NagarNagpur-440010India

In this paper, we employ the concept of prob.b.lity for creating a cavity with diameter d in fluid along with the perturb.tion and variation approach, and develop an equation of state （EOS） for a hard sphere （HS） and Lennard Jones （L J） fluids. A suitab.e axiomatic form for surface tension S（r） is assumed for the pure fluid, with r as a variab.e. The function S（r） has an arb.trary parameter rn. S（r） = A ＋ b.d/r）/[1 ＋ m（d/r）]. We use the condition in terms of radial distrib.tion function G（λd,η） containing the self-consistent parameter λ and the condition of continuity at r = d/2 to determine A and b. A different EOS can b. ob.ained with a suitab.e choice of rn and the EOS has a lower root-mean-square deviation than that of b.rker-Henderson b.2 for LJ fluids.

关键词： equation of state Lenard Jones potential hard-sphere potential liquid mixture

The Consideration of Overlapping Lines in the Calculation of Radiative Power Emitted from CH_4 Thermal Plasma

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Plasma Science and Technology 2012年第12期14卷 1073-1078页

作者： R. b.NALLAL b. LIANI Theoretical Physics Lab.ratory Abou Bekr Belkaid University cole prparatoire des Sciences et Techniques

Net emission coefficients of radiation were calculated for isothermal plasma of methane as a function of the plasma temperature 5,000 - 30,000 K and the arc radius 0 mm to 10 mm at atmospheric pressure. Calculations take into account continuum and line radiations, special attention has also b.en given to the influence of overlapping spectral lines. The line shapes in our calculations are given b. convolution of Doppler and Lorentz profiles, resulting in a simplified Voigt profile. In the case of a hydrogen profile, we used the Vidal tab.es, and the four first Lyman lines and the four first b.lmer lines were considered. This calculation was carried out on the assumption of local thermodynamic equilib.ium and in a nondiffusive environment. The net emission coefficient calculation for pure argon plasma was compared with the experimental results of Evans in our previous work. We used the escape factor, and our results were higher than those of the experiment. In this paper, we explain why, using the escape factor, the radiation is overestimated. The net emission coefficient ob.ained from a real spectrum was compared with Essoltani work＇s which used the line-b.-line method for pure argon plasma.

关键词： thermal plasma radiation net emission coefficient ab.orption coefficient

Study of nucleon resonances in a chiral quark model via η productions

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Chinese Physics C 2009年第12期33卷 1389-1392页

作者：何军 b. Saghai Institute of Modern Physics Chinese Academy of Sciences Institut de Recherche sur les lois Fondamentales de l’Univers IRFU CEA/Saclay 91191 Gif-sur-Yvette France

In this report we investigate Wmeson productions on the proton via electromagnetic and hadron prob.s in a chiral quark model approach. The ob.ervab.es, such as, differential cross section and b.am asymmetry for the two productions are calculated and compared with the experiment. The five known resonances S11（1535）,S11（1650）, P13（1720）, D13（1520）, and F15（1680） are found to b. dominant in the reaction mechanisms in b.th channels. Significant contrib.tion ＂missing resonances, no evidence is found within πp→ηn are also presented. from a new S11 resonances are deduced. For the so-called the investigated reactions. The partial wave amplitudes for

关键词： N* chiral quark model photoproduction

The discovery of magnetotactic/magnetosensitive b.cteria

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Chinese Journal of Oceanology and Limnology 2009年第1期27卷 1-2页

作者： Richard b. FRANKEL Department of Physics California Polytechnic State University San Luis Obispo

Magnetotactic b.cteria orient and migrate along magnetic field lines in aquatic hab.tats. The first paper on this phenomenon was written b. Richard P. b.akemore （b.akemore, 1975; 1982）.

关键词： magnetotaxis magnetosensitivity b.cteria discovery