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*** plane-wave prestack time migration for AVO analysis

Applied Geophysics 2008年第3期5卷 212-218页

作者：王棣程玖兵郑晓东王华忠马在田中国石油勘探开发研究院物探技术研究所北京学院路20号100083 同济大学海洋与地球科学学院上海市四平路1239号200092

To support amplitude variation with offset （AVO） analysis in complex structure areas, we introduce an amplitude-preserving plane-wave prestack time migration approach based on the double-square-root wave equation in media with little lateral velocity variation. In its implementation, a data mapping algorithm is used to obtain offset-plane-wave data sets from the common-midpoint gathers followed by a non-recursive phase-shift solution with amplitude correction to generate common-image gathers in offset-ray-parameter domain and a structural image. Theoretical model tests and a real data example show that our prestack time migration approach is helpful for AVO analysis in complex geological environments.

关键词： plane-wave prestack time migration amplitude-preserving common-image gather

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HYBRID LINEAR AND QUADRATIC FINITE ELEMENT MODELS FOR 3D HELMHOLTZ PROBLEMS

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Acta Mechanica Solida Sinica 2013年第6期26卷 603-618页

作者： Q.H.Zhang K.Y.Sze Guangdong Province Key Laboratory of Computational Science Sun Yat-Sen University Department of Mechanical Engineering The University of Hong KongPokfulam

In this paper, linear and quadratic finite element models are devised for the three- dimensional Helmholtz problem by using a hybrid variational functional. In each element, contin- uous and discontinuous Helmholtz fields are defined with their equality enforced over the element boundary in a weak sense. The continuous field is based on the C° nodal interpolation and the discontinuous field can be condensed before assemblage. Hence, the element can readily be in- corporated seamlessly into the standard finite element program framework. Discontinuous fields constructed by the plane-wave, Bessel and singular spherical-wave solutions are attempted. Nu- merical tests demonstrate that some of the element models are consistently and considerably more accurate than their conventional counterparts.

关键词： finite element hybrid Helmholtz Bessel plane-wave spherical-wave radial basis function

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Study on H atoms diffusion and adsorption properties of MgH_2-V systems

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Science China(Technological Sciences) 2008年第7期51卷 979-988页

作者： ZHOU DianWu1,2, LIU JinShui3 & PENG Ping3 1 State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China 2 College of Mechanical and Automatic Engineering, Hunan University, Changsha 410082, China 3 College of Materials Science and Engineering, Hunan University, Changsha 410082, China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha China College of Mechanical and Automatic Engineering Hunan University Changsha China College of Materials Science and Engineering Hunan University Changsha China

Based on experimental results that VH0.81/MgH2 interface was found during the process of mechanically milling MgH2+5at.%V nanocomposite, H atoms diffusion and adsorption properties of MgH2-V systems have been investigated by using a first-principles plane-wave pseudopotential method based on the density functional theory. The results are as follows. When VH/MgH2 interface is formed due to V alloying MgH2 phase, the vacancy formed by H atoms near VH phase region is more stable than that without V alloying, while vacancy near MgH2 phase region is less stable than that without V alloying. During the process of H atoms diffusion after V alloying, the max migration barrier energy of H atoms in MgH2-V systems is reduced compared with that of MgH2 phase, which means that H atoms diffuse easily. When H diffuses into VH from MgH2 across VH/MgH2 interface, among three substitutions such as the replacement of H for V vacancy, or interstitial site or V atoms, the replacement of H for V vacancy has the strongest diffusion ability, next interstitial site, and finally V atoms site. As far as H adsorbed on different surfaces of VH phase is concerned, physical adsorption is carried out more easily than chemical adsorption, and the behavior of H atoms adsorbed on the surface near VH phase region can be found more easily than that near MgH2 phase region.

关键词： plane-wave pseudopotential theory magnesium hydride diffusion adsorption

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Thermoelastic waves in a fractional-order initially stressed micropolar diffusive porous medium

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Journal of Ocean Engineering and Science 2021年第4期6卷 376-388页

作者： Anand Kumar Yadav Shishu Niketan Model Senior Secondary School Sector 22-DChandigarhIndia

The research article is the analysis of wave propagation in an initially stressed micropolar fractional-order derivative thermoelastic diffusion medium with *** governing equations in the context of generalized fractional-order derivative thermo-elasticity are formulated and the velocity equations are *** plane wave solution of these equations indicates the existence of six plane waves,namely coupled longitudinal displacement(cL),coupled thermal(cT),coupled mass diffusion(cMD),coupled longitudinal void volume fraction(cV),coupled transverse displacement(cT D),and coupled transverse micro-rotational(cT M)*** sets of coupled waves(cL),(cT),(cMD)and(cV)are found to be dis-persive,attenuating and influenced by the presence of thermal,diffusion and voids parameters in the *** speeds of coupled transverse displacement(cT D),and coupled transverse micro-rotational(cT M)waves are not affected by thermal,diffusion and void *** speeds of the plane waves,cL,cT,cMD,and cV are computed for a particular material and plotted against the thermal parameter,fre-quency,initial stress,diffusion and void parameters.

关键词： Micropolar Thermodiffusion Void Fractional-order thermoelasticity Initial stress plane-wave

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Hyperthermia Dosing and Depth of Effect

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Open Journal of Biophysics 2018年第1期8卷 31-48页

作者： Oliver Szasz Gyula Peter Szigeti Tamas Vancsik Andras Szasz Department of Biotechnics St. Istvan University Budapest Hungary Institute of Human Physiology and Clinical Experimental Research Semmelweis University Budapest Hungary Department of Pathology and Experimental Cancer Research Semmelweis University Budapest Hungary

The penetration depth in the electromagnetic heating could be a crucial factor of its application, when the deep heating is the goal. The capacitive coupling is one of the most popular heating techniques in radiofrequency (RF) heating applications. The matching of the target defines the penetration possibilities. The current matched solution has deeper mathematically defined penetration in RF region than the capacitive plane-wave solution. The same power of application request high voltage with relatively low current for plane-wave inducing, while in current matching it has low voltage with high current. The effective depth of the action in the two solutions do not identical, the penetration defined by the intensity of 1/e portion of the incident beam is higher in the current-matched techniques.

关键词： Oncothermia Capacitive Coupling plane-wave Matching Current Matching Penetration-Depth

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