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finite-difference modeling of Maxwell viscoelastic media developed from perfectly matched layer

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Petroleum Science 2023年第5期20卷 2759-2772页

作者： Ruo-long Song College of Physics Jilin UniversityChangchun130012JilinChina

In numerical simulation of wave propagation,both viscoelastic materials and perfectly matched layers(PMLs)attenuate *** wave equations for both the viscoelastic model and the PML contain convolution ***,convolution operator is intractable in finite-difference time-domain(fDTD)method.A great deal of progress has been made in using time stepping instead of convolution in *** incorporate PML into viscoelastic media,more memory variables need to be introduced,which increases the code complexity and computation *** modifying the nonsplitting PML formulation,I propose a viscoelastic model,which can be used as a viscoelastic material and/or a PML just by adjusting the *** proposed viscoelastic model is essentially equivalent to a Maxwell *** with existing PML methods,the proposed method requires less memory and its implementation in existing finite-difference codes is much *** attenuation and phase velocity of P-and S-waves are frequency independent in the viscoelastic model if the related quality factors(Q)are greater than *** numerical examples show that the method is stable for materials with high absorption(Q=1),and for heterogeneous media with large contrast of acoustic impedance and large contrast of viscosity.

关键词： finite difference Viscoelastic model Nonsplitting perfectly matched layer

Magnetic interaction in the metamaterial/magnet system

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Chinese Physics B 2014年第8期23卷 537-539页

作者： M.K.Alqadi f.y.Alzoubi Department of Physics Jordan University of Science and Technology

The stability of the magnetic dipole and the metamaterial with negative permeability are investigated. Analytical expressions of the interaction force and stiffness of the magnetic line and metamaterial with negative permeability are derived. The repulsive force between the magnetic line and the metamaterial exceeds the value of the maximum force in the magnet-superconductor system.

关键词： metamaterial interaction energy negative permeability

Conjugate Heat Transfer for free Convection along a Vertical Plate fin

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Journal of Thermal Science 2010年第4期19卷 337-345页

作者： Kai-long Hsiao Department of Digital Entertainment and Game Design Diwan University

In this study,a new and effective improved Semi-Analytic and Semi-Empirical formula f(Pr)= (0.749999437Pr^(1/2))/((0.609+1.221Pr^(1/2)+1.238Pr)^(1/4))has been proposed to solve a conjugate problem with free convection in the incompressible laminar boundary layer flow and heat conduction in a solid wall for the flow passing a flat plate fin. A combination of flat-plate flow and flat-plate fin heat conduction has been considered in the present *** -difference solutions for the interface temperature profiles and the heat transfer rates have been presented over the entire thermo-fluid-dynamic field for Prandtl numbers from 0.001 to ***,the similar flow field has been solved by the Runge-Kutta method and the shooting methods,then the correlation equation of the local heat transfer coefficient have been ***,the empirical formula has been substituted into the fin temperature heat conduction calculation processes to obtain the iterative solutions of the conjugate problems.

关键词： Conjugate heat transfer free convection Vertical plate fin finite difference Runge-Kutta method Shooting method.

Editorial:Secure and Safe Meta Control for Cyber Physical Systems

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IEEE/CAA Journal of Automatica Sinica 2023年第12期10卷 2177-2178页

作者： Qing-long Han IEEE the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourneVIC 3122Australia

Welcome to the twelfth issue of 2023 in the IEEE/CAA Journal of Automatica Sinica(JAS).In the sixth issue of2023,I systematically addressed the latest development of Meta Vehicles,and sorted out some important contributions published in the IEEE/CAA JAS focusing on control,estimation,and optimization of automated vehicles with reliability,security,efficiency,and intelligence.

关键词： Secure automated estimation

Dislocation ordering and texture strengthening of naturally aged Al-Cu-Mg alloy

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Journal of Materials Science & Technology 2022年第23期118卷 1-14页

作者： f.Liu Z.y.Liu G.y.He L.N.Ou School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Metal Materials Science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

Stability of grain structure,dislocation ordering and strengthening mechanisms of the naturally aged AlCu-Mg alloy after solution treatment are investigated by using optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD),X-ray diffraction(XRD) and transmission electron microscope(TEM).Results show that {100},{100},{110} and {110}slip systems can be activated after solution treatment,which can promote the formation of {110}Goss *** combination effect of T-Al_(20)Cu_(2) Mn_(3) phase and Goss-oriented grains with large Taylor factor makes the solution-treated alloys display excellent stability of grain *** enhanced yield strength of the alloy is ascribed to grain-refine strengthening,dispersed particles strengthening,dislocation strengthening and texture *** coarsening of the second phase is responsible for softening of the alloy after annealing at 400 ℃+solution treatment at 475 ℃.

关键词： Al-Cu-Mg alloy Dislocation ordering Goss texture Grain structure stability Texture strengthening

Effect of drainage on CO_2, CH_4, and N_2O fluxes from aquaculture ponds during winter in a subtropical estuary of China

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Journal of Environmental Sciences 2018年第3期30卷 72-82页

作者： Ping yang Derrick y.f Lai Jia f.Huang Chuan Tong School of Geographical Sciences Fujian Normal University Key Laboratory of Humid Sub-tropical Eco-geographical Process of Ministry of Education of China Fujian Normal University Department of Geography and Resource Management and Centre for Environmental Policy and Resource ManagementThe Chinese University of Hong Kong

Aquaculture ponds are dominant features of the landscape in the coastal zone of ***,aquaculture ponds are drained during the non-culture period in ***,the effects of such drainage on the production and flux of greenhouse gases（GHGs）from aquaculture ponds are largely *** the present study,field-based research was performed to compare the GHG fluxes between one drained pond（DP,with a water depth of 0.05 m）and one undrained pond（UDP,with a water depth of 1.16 m）during one winter in the Min River estuary of southeast *** the entire study period,the mean CO2flux in the DP was（0.75±0.12）mmol/（m^2·hr）,which was significantly higher than that in the UDP of（-0.49±0.09）mmol/（m^2·hr）（p0.01）.This indicates that drainage drastically transforms aquaculture ponds from a net sink to a net source of CO2in *** CH4and N2O emissions were significantly higher in the DP compared to those in the UDP（CH4=（0.66±0.31）vs.（0.07±0.06）mmol/（m^2·hr）and N2O=（19.54±2.08）vs.（0.01±0.04）μmol/（m^2·hr））（p〈0.01）,suggesting that drainage would also significantly enhance CH4and N2O *** in environmental variables（including sediment temperature,p H,salinity,redox status,and water depth）contributed significantly to the enhanced GHG emissions following pond ***,analysis of the sustained-flux global warming and cooling potentials indicated that the combined global warming potentials of the GHG fluxes were significantly higher in the DP than in the UDP（p〈0.01）,with values of739.18 and 26.46 mg CO2-eq/（m^2·hr）,*** findings suggested that drainage of aquaculture ponds can increase the emissions of potent GHGs from the coastal zone of China to the atmosphere during winter,further aggravating the problem of global warming.

关键词： Aquaculture pond Drainage management Greenhouse gas flux Global warming Min River estuary

Comparative in vitro Study on Pure Metals(fe,Mn,Mg,Zn and W) as Biodegradable Metals

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Journal of Materials Science & Technology 2013年第7期29卷 619-627页

作者： J.Cheng B.Liu y.H.Wu y.f.Zheng Center for Biomedical Materials and Tissue Engineering Academy for Advanced Interdisciplinary StudiesPeking University State Key Laboratory for Turbulence and Complex System and Department of Materials Science and Engineering College of EngineeringPeking University

five pure metals including fe, Mn, Mg, Zn and W have been investigated on their corrosion behavior and in vitro biocompatibility by electrochemical measurement, static immersion test, contact angle measurement, cytotoxicity and hemocompatibility tests. It is found that the sequence of corrosion rate of five metals in Hank＇s solution from high to low is： Mg 〉 fe 〉 Zn 〉 Mn 〉 W. fe, Mg and W show no cytotoxicity to L929 and ECV304 cells, Mn induces significant cytotoxicity to both L929 and ECV304 cells, and Zn has almost no inhibition effect on the metabolic activities of ECV304 while largely reduces the cell viability of L929 cells. The hemolysis percentage of five pure metals is lower than 5% except for Mg and platelets adhered on Zn has been activated and pseudopodia-like structures can be observed while platelets on the other four metals keep normal.

关键词： Biodegradable metals Cytotoxicity Corrosion Biocompatibflity

NUMERICAL SOLUTIONS fOR A NEARLy CIRCULAR CRACK WITH DEVELOPING CUSPS UNDER SHEAR LOADING

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Acta Mechanica Solida Sinica 2011年第5期24卷 439-449页

作者： N.M.A.Nik long L.f.Koo Z.K.Eshkuvatov Department of Mathematics faculty of ScienceUniversity Putra Malaysia Institute for Mathematical Research University Putra Malaysia

In this paper, we study the behavior of the solution at the crack edges for a nearly circular crack with developing cusps subject to shear loading. The problem of finding the resulting force can be written in the form of a hypersingular integral equation. The equation is then trans-formed into a similar equation over a circular region using conformal mapping. The equation is solved numerically for the unknown coefficients, which will later be used in finding the stress intensity factors. The sliding and tearing mode stress intensity factors are evaluated for cracks and displayed graphically. Our results seem to agree with the existing asymptotic solution.

关键词： nearly circular crack numerical method Galerkin method stress intensity factors hypersingular integral equation shear loading conformal mapping

Local Strain Energy Density Applied to Bainitic functionally Graded Steels Plates Under Mixed-Mode(Ⅰ+Ⅱ) Loading

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 164-172页

作者： H.Salavati y.Alizadeh f.Berto Department of Mechanical Engineering Amirkabir University of Technology Department of Management and Engineering University of Padova

In this paper, the averaged value of the strain energy density （SED） over a control volume is used to predict the critical load of V-notched specimens made of functionally graded steels （fGSs） under mixed-mode loading. The studied fGSs contain ferritic and austenite phases in addition to bainitic layer produced by electroslag remelting. The mechanism- based strain gradient plasticity theory is used to determine the flow stress （yield stress or ultimate stress） of each layer. The young＇s modulus and the Poisson＇s ratio have been assumed to be constant, while other mechanical properties vary exponentially along the specimen width. The control volume is centered in relation to the maximum principal stress present on the notch edge and assumes a crescent shape. The points belonging to the volume perimeter are obtained numerically. In the present contribution, the effects of notch radius and notch depth on the SED and the critical load are studied. The notch radius varies from 0.2 to 2.0 mm, and the notch depth varies from 5 to 7 ram. By using the SED approach and finite element simulations, the critical load is determined, and the obtained results show a sound agreement with the experimental results.

关键词： functionally bainitic graded steel Strain energy density Mechanism-based strain gradientplasticity theory Critical load Notch radius Notch depth