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3D automatic segmentation method for retinal optical coherence tomography volume data using boundary surface enhancement 被引量:1
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作者 Yankui Sun Tian Zhang +1 位作者 Yue Zhao Yufan He 《Journal of Innovative Optical Health Sciences》 SCIE EI CAS 2016年第2期41-58,共18页
With the introduction of spectral-domain optical coherence tomography(SD-OCT),much larger image datasets are routinely acquired compared to what was possible using the previous generation of time-domain OCT.Thus,there... With the introduction of spectral-domain optical coherence tomography(SD-OCT),much larger image datasets are routinely acquired compared to what was possible using the previous generation of time-domain OCT.Thus,there is a critical need for the development of three-dimensional(3D)segmentation methods for processing these data.We present here a novel 3D automatic segmentation method for retinal OCT volume data.Brie°y,to segment a boundary surface,two OCT volume datasets are obtained by using a 3D smoothingfilter and a 3D differentialfilter.Their linear combination is then calculated to generate new volume data with an enhanced boundary surface,where pixel intensity,boundary position information,and intensity changes on both sides of the boundary surface are used simultaneously.Next,preliminary discrete boundary points are detected from the A-Scans of the volume data.Finally,surface smoothness constraints and a dynamic threshold are applied to obtain a smoothed boundary surface by correcting a small number of error points.Our method can extract retinal layer boundary surfaces sequentially with a decreasing search region of volume data.We performed automatic segmentation on eight human OCT volume datasets acquired from a commercial Spectralis OCT system,where each volume of datasets contains 97 OCT B-Scan images with a resolution of 496512(each B-Scan comprising 512 A-Scans containing 496 pixels);experimental results show that this method can accurately segment seven layer boundary surfaces in normal as well as some abnormal eyes. 展开更多
关键词 Optical coherence tomography boundary surface enhancement retinal layer segmentation OCT volume data
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COMPACT FOUR-COMPONENT 2-D FDFD METHOD WITH EQUIVALENT SURFACE IMPEDANCE BOUNDARY CONDITION FOR MULTILAYER METAL-COATED WAVEGUIDE 被引量:1
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作者 赵伟 赵永久 +2 位作者 邓宏伟 姜万顺 宁曰民 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2010年第3期275-279,共5页
A compact four-component two-dimensional (2-D) finite-difference frequency domain (FDFD) method with the equivalent surface impedance boundary condition is used to analyze the dispersion characteristics of multila... A compact four-component two-dimensional (2-D) finite-difference frequency domain (FDFD) method with the equivalent surface impedance boundary condition is used to analyze the dispersion characteristics of multilayer metal-coated waveguides. According to the equivalent surface impedance boundary condition,the relationship between transverse field components on the boundary can be easily depicted. Once the eigen equation is solved,the propagation constant can be obtained as the eigen value for a given frequency. Results of the proposed method agaree well with those of high frequency structure simulator(HFSS). 展开更多
关键词 WAVEGUIDES eigen equation equivalent surface impedance boundary condition propagation constant
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2D-Manifold Boundary Surfaces Extraction from Heterogeneous Object on GPU 被引量:3
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作者 王明 冯结青 《Journal of Computer Science & Technology》 SCIE EI CSCD 2012年第4期862-871,共10页
The conventional isosurface techniques are not competent for nleshing a heterogeneous object because they assume that the object is homogeneous. Thus the visualization method taking the heterogeneity into account is d... The conventional isosurface techniques are not competent for nleshing a heterogeneous object because they assume that the object is homogeneous. Thus the visualization method taking the heterogeneity into account is desired. In this paper, we propose a novel algorithm to extract the boundary surfaces from a heterogeneous object in one pass, whose remarkable advantage is free of the number of materials contained. The heterogeneous object is first classified into a series of homogeneous material components. Then each component is enclosed with a 2D-manifold boundary surface extracted via our algorithm. The information important to the heterogeneous object is also provided, such as the interface between two materials, the intersection curve where three materials meet and the intersection point where four materials meet. To improve the performance, the algorithm is also designed and implemented on GPU. Experimental results demonstrate the effectiveness and efficiency of the proposed algorithm. 展开更多
关键词 heterogeneous object ISOsurface interface boundary surface GPU
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ASYMPTOTIC BEHAVIOR FOR A CLASS OF ELLIPTICEQUIVALUED SURFACE BOUNDARY VALUE PROBLEM WITH DISCONTINUOUS INTERFACE CONDITIONS 被引量:6
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作者 CAI ZHIJIE(Institute of Mathematics, Fudan University, Shanghai 200433.) 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 1995年第3期237-250,共14页
Spontaneous potential well-logging is one of the important techniques in petroleum exploitation. A spontaneous potential satisfies an elliptic equivalued surface boundary value problem with discontinuous interface con... Spontaneous potential well-logging is one of the important techniques in petroleum exploitation. A spontaneous potential satisfies an elliptic equivalued surface boundary value problem with discontinuous interface conditions. In practice, the measuring electrode is so small that we can simplify the corresponding equivalued surface to a point. In this paper, we give a positive answer to this approximation process:when the equivalued surface shrinks to a point, the solution of the original equivalued surface boundary value problem converges to the solution of the corresponding limit boundary value problem. 展开更多
关键词 Spontaneous potential well-logging equivalued surface boundary value problem asymptotic behavior
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Some Characteristics of the Surface Boundary Layer of a Strong Cold Air Process over Southern China 被引量:2
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作者 刘熙明 程雪玲 +2 位作者 吴琼 傅敏宁 曾庆存 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第1期210-218,共9页
In southern China, cold air is a common weather process during the winter season; it can cause strong wind, sharp temperature decreases, and even the snow or freezing rain events. However, the features of the atmosphe... In southern China, cold air is a common weather process during the winter season; it can cause strong wind, sharp temperature decreases, and even the snow or freezing rain events. However, the features of the atmospheric boundary layer during cold air passage are not clearly understood due to the lack of comprehensive observation data, especially regarding turbulence. In this study, four-layer gradient meteorological observation data and one-layer, 10-Hz ultrasonic anemometer-thermometer monitoring data from the northern side of Poyang Lake were employed to study the main features of the surface boundary layer during a strong cold-air passage over southern China. The results show that, with the passage of a cold air front, the wind speed exhibits low-frequency variations and that the wind systematically descends. During the strong wind period, the wind speed increases with height in the surface layer. Regular gust packets are superimposed on the basic strong wind flow. Before the passage of cold air, the wind gusts exhibit a coherent structure. The wind and turbulent momentum fluxes are small, although the gusty wind momentum flux is slightly larger than the turbulent momentum flux. However, during the invasion of cold air, both the gusty wind and turbulent momentum fluxes increase rapidly with wind speed, and the turbulent momentum flux is larger than the gusty wind momentum flux during the strong wind period. After the cold air invasion, this structure almost disappears. 展开更多
关键词 cold air surface boundary layer gusty wind descending motion
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Large eddy simulation of turbulence in ocean surface boundary layer at Zhangzi Island offshore 被引量:2
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作者 LI Shuang SONG Jinba +1 位作者 HE Hailun HUANG Yansong 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2013年第7期8-13,共6页
This study uses a large eddy simulation (LES) model to investigate the turbulence processes in the ocean surface boundary layer at Zhangzi Island offshore. Field measurements at Zhangzi Island (39°N, 122°... This study uses a large eddy simulation (LES) model to investigate the turbulence processes in the ocean surface boundary layer at Zhangzi Island offshore. Field measurements at Zhangzi Island (39°N, 122°E) during July 2009 are used to drive the LES model. The LES results capture a clear diurnal cycle in the oceanic turbulence boundary layer. The process of the heat penetration and heat distribution characteristics are analyzed through the heat flux results from the LES and their differences between two diurnal cycles are discussed as well. Energy balance and other dynamics are investigated which show that the tide-induced shear production is the main source of the turbulence energy that balanced dissipation. Momentum flux near the surface shows better agreement with atmospheric data computed by the eddy correlation method than those computed by bulk formula. 展开更多
关键词 ocean surface boundary layer large eddy simulation TURBULENCE momentum flux heat flux
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Evaluation of Haney-Type Surface ThermalBoundary Conditions Using a CoupledAtmosphere and Ocean Model 被引量:1
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作者 Peter C. Chu 陈玉春 吕世华 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2001年第3期355-375,共21页
A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition... A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat fluxQ to air/sea temperature difference ΔT by a relaxation coefficientk. The model was initiated from the National Centers for Environmental Prediction (NCEP) atmospheric observations for 1 December 1977, and from the National Ocean Data Center (NODC) global climatological mean December temperature and salinity fields at 1°x 1° resolution. The time step is 7.5 minutes. We integrated the model for 450 days and obtained a complete model-generated global data set of daily mean downward net surface fluxQ, surface air temperatureT A, and sea surface temperatureT O. Then, we calculated the cross-correlation coefficients (CCC) betweenQ and ΔT. The ensemble mean CCC fields show (a) no correlation betweenQ and ΔT in the equatiorial regions, and (b) evident correlation (CCC≥0.7) betweenQ and ΔT in the middle and high latitudes. Additionally, we did the variance analysis and found that whenk=120 W m?2K?1, the two standard deviations, σQ and σκδT , are quite close in the middle and high latitudes. These results agree quite well with a previous research (Chu et al., 1998) on analyzing the NCEP re-analyzed surface data, except that a smaller value ofk (80 W m?2K?1) was found in the previous study. Key words Air-sea coupled system - Ocean surface fluxes - Surface thermal boundary condition 展开更多
关键词 Air-sea coupled system Ocean surface fluxes surface thermal boundary condition
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Time–space dependent fractional boundary layer flow of Maxwell fluid over an unsteady stretching surface 被引量:1
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作者 Shengting Chen Liancun Zheng +1 位作者 Bingyu Shen Xuehui Chen 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2015年第6期262-266,共5页
Fractional boundary layer flow of Maxwell fluid on an unsteady stretching surface was investigated. Time-space dependent fractional derivatives are introduced into the constitutive equations of the fluid. We developed... Fractional boundary layer flow of Maxwell fluid on an unsteady stretching surface was investigated. Time-space dependent fractional derivatives are introduced into the constitutive equations of the fluid. We developed and solved the governing equations using explicit finite difference method and the L1- algorithm as well as shifted Grunwald-Letnikov formula. The effects of fractional parameters, relaxation parameter, Reynolds number, and unsteadiness parameter on the velocity behavior and characteristics of boundary layer thickness and skin friction were analyzed. Results obtained indicate that the behavior of boundary layer of viscoelastic fluid strongly depends on time-space fractional parameters. Increases of time fractional derivative parameter and relaxation parameter cause a decrease of velocity while boundary layer thickness increase, but the space fractional derivative parameter and fractional Reynolds number have the opposite effects. 展开更多
关键词 Maxwell fluid boundary layer Fractional derivatives Unsteady stretching surface
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Dependence of the AGCM Climatology on the Method of Prescribing Surface Boundary Conditions and Its Climatological Implication
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作者 林朝晖 毕训强 +1 位作者 王会军 曾庆存 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1999年第4期593-607,共15页
By using IAP 9L AGCM, two sets of long-term climatological integration have been performed with the two different interpolation procedures for generating the daily surface boundary conditions. One interpolation proced... By using IAP 9L AGCM, two sets of long-term climatological integration have been performed with the two different interpolation procedures for generating the daily surface boundary conditions. One interpolation procedure is the so-called “traditional” scheme, for which the daily surface boundary conditions are obtained by linearly interpolating between the observed monthly mean values, however the observed monthly means cannot be preserved after interpolation. The other one is the “new” scheme, for which the daily surface boundary conditions are obtained by linearly interpolating between the “artificial” monthly mean values which are based on, but are different from the observed ones, after interpolating with this new scheme, not only the observed monthly mean values are preserved, the time series of the new generated daily values is also more consistent with the observation. Comparison of the model results shows that the differences of the globally or zonally averaged fields between these two integrations are quite small, and this is due to the compensating effect between the different regions. However, the differences of the two patterns (the global or regional geographical distributions), are quite significant, for example, the magnitude of the difference in the JJA mean rainfall between these two integrations can exceed 2 mm/ day over Asian monsoon regions, and the difference in DJF mean surface air temperature can also exceed 2?C over this region. The fact that the model climatology depends quite strongly on the method of prescribing the daily surface boundary conditions suggests that in order to validate the climate model or to predict the short-term climate anomalies, either the “new? interpolation scheme or the high frequency surface boundary conditions (e.g., daily or weekly data instead of the monthly data) should be introduced. Meanwhile, as for the coupled model, the daily coupling scheme between the different component climate models ( e.g., atmospheric and oceanic general circulation models) is preferred in order to partly eliminate the “climate drift” problem which may appear during the course of direct coupling. 展开更多
关键词 Linear interpolation Model climatology Atmospheric general circulation model (AGCM) surface boundary condition
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Influence of Irregular Coastlines on a Tornadic Mesovortex in the Pearl River Delta during the Monsoon Season. Part Ⅰ:Pre-storm Environment and Storm Evolution 被引量:1
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作者 Lanqiang BAI Dan YAO +4 位作者 Zhiyong MENG Yu ZHANG Xianxiang HUANG Zhaoming LI Xiaoding YU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第6期1115-1131,共17页
The Pearl River Delta(PRD),a tornado hotspot,forms a distinct trumpet-shaped coastline that concaves toward the South China Sea.During the summer monsoon season,low-level southwesterlies over the PRD’s sea surface te... The Pearl River Delta(PRD),a tornado hotspot,forms a distinct trumpet-shaped coastline that concaves toward the South China Sea.During the summer monsoon season,low-level southwesterlies over the PRD’s sea surface tend to be turned toward the west coast,constituting a convergent wind field along with the landward-side southwesterlies,which influences regional convective weather.This two-part study explores the roles of this unique land–sea contrast of the trumpet-shaped coastline in the formation of a tornadic mesovortex within monsoonal flows in this region.Part I primarily presents observational analyses of pre-storm environments and storm evolutions.The rotating storm developed in a lowshear environment(not ideal for a supercell)under the interactions of three air masses under the influence of the land–sea contrast,monsoon,and storm cold outflows.This intersection zone(or“triple point”)is typically characterized by local enhancements of ambient vertical vorticity and convergence.Based on a rapid-scan X-band phased-array radar,finger-like echoes were recognized shortly after the gust front intruded on the triple point.Developed over the triple point,they rapidly wrapped up with a well-defined low-level mesovortex.It is thus presumed that the triple point may have played roles in the mesovortex genesis,which will be demonstrated in Part II with multiple sensitivity numerical simulations.The findings also suggest that when storms pass over the boundary intersection zone in the PRD,the expected possibility of a rotating storm occurring is relatively high,even in a low-shear environment.Improved knowledge of such environments provides additional guidance to assess the regional tornado risk. 展开更多
关键词 TORNADO mesovortex surface boundary land–sea contrast MONSOON
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Convective heat and mass transfer in MHD mixed convection flow of Jeffrey nanofluid over a radially stretching surface with thermal radiation 被引量:6
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作者 M.BILAL ASHRAF T.HAYAT +1 位作者 A.ALSAEDI S.A.SHEHZAD 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期1114-1123,共10页
Mixed convection flow of magnetohydrodynamic(MHD) Jeffrey nanofluid over a radially stretching surface with radiative surface is studied. Radial sheet is considered to be convectively heated. Convective boundary condi... Mixed convection flow of magnetohydrodynamic(MHD) Jeffrey nanofluid over a radially stretching surface with radiative surface is studied. Radial sheet is considered to be convectively heated. Convective boundary conditions through heat and mass are employed. The governing boundary layer equations are transformed into ordinary differential equations. Convergent series solutions of the resulting problems are derived. Emphasis has been focused on studying the effects of mixed convection, thermal radiation, magnetic field and nanoparticles on the velocity, temperature and concentration fields. Numerical values of the physical parameters involved in the problem are computed for the local Nusselt and Sherwood numbers are computed. 展开更多
关键词 Jeffrey nanofluid mixed convection flow radially stretching surface convective boundary conditions magnetic field
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4-component 2-D CFDFD method in analysis of lossy circular waveguide with fractal rough surface
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作者 邓宏伟 赵永久 +2 位作者 刘冰 姜万顺 宁曰民 《Journal of Shanghai University(English Edition)》 CAS 2011年第3期185-189,共5页
In this paper, equivalent surface impedance boundary condition (ESIBC), which takes fractal parameters (D, G) into SIBC, is implemented in the 4-component 2-D compact finite difference frequency domain (2-D CFDFD... In this paper, equivalent surface impedance boundary condition (ESIBC), which takes fractal parameters (D, G) into SIBC, is implemented in the 4-component 2-D compact finite difference frequency domain (2-D CFDFD) method to an- alyze the propagation characteristics of lossy circular waveguide with fractal rough surface based on Weierstrass-Mandelbrot (W-M) function. Fractal parameters’ effects on attenuation constant are presented in the 3 mm lossy circular waveguide, and the attenuation constants of the first three modes vary monotonically with scaling constant (G) and decrease as the fractal dimension (D) increasing. 展开更多
关键词 FRACTAL ROUGHNESS 2-D compact fimte difference frequency domain (2-D CFDFD) equivalent surface impedance boundary condition (ESIBC) attenuation constant
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Finite-difference time-domain modeling of curved material interfaces by using boundary condition equations method
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作者 卢佳 周怀春 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第9期198-206,共9页
To deal with the staircase approximation problem in the standard finite-difference time-domain(FDTD) simulation,the two-dimensional boundary condition equations(BCE) method is proposed in this paper.In the BCE met... To deal with the staircase approximation problem in the standard finite-difference time-domain(FDTD) simulation,the two-dimensional boundary condition equations(BCE) method is proposed in this paper.In the BCE method,the standard FDTD algorithm can be used as usual,and the curved surface is treated by adding the boundary condition equations.Thus,while maintaining the simplicity and computational efficiency of the standard FDTD algorithm,the BCE method can solve the staircase approximation problem.The BCE method is validated by analyzing near field and far field scattering properties of the PEC and dielectric cylinders.The results show that the BCE method can maintain a second-order accuracy by eliminating the staircase approximation errors.Moreover,the results of the BCE method show good accuracy for cylinder scattering cases with different permittivities. 展开更多
关键词 finite-difference time-domain curved surface staircase error boundary condition equation
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The effect of G?rtler instability on hypersonic boundary layer transition
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作者 Min Yu Xiang-Jiang Yuan 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2016年第2期97-99,共3页
The evolution of Gortler vortices and its interaction with other instabilities are investigated in this paper. Both the Mack mode and the Gortler mode exist in hypersonic boundary-layer flows over concave surfaces, an... The evolution of Gortler vortices and its interaction with other instabilities are investigated in this paper. Both the Mack mode and the Gortler mode exist in hypersonic boundary-layer flows over concave surfaces, and their interactions are crucially important in boundary layer transition. We carry out a direct numerical simulation to explore the interaction between the GOrtler and the oblique Mack mode. The results indicate that the interaction between the forced Gortler mode and the oblique Mack mode promotes the onset of the transition. The forced oblique Mack mode is susceptible to nonlinear interaction. Because of the development of the GOrtler mode, the forced Mack mode and other harmonic modes are excited. 展开更多
关键词 Concave surface Gortler instability Mack mode boundary layer transition
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An Alternative Method to Study Wave Scattering by Semi-infinite Inertial Surfaces
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作者 R.Gayen Ranita Roy 《Journal of Marine Science and Application》 2013年第1期31-37,共7页
A new method to solve the boundary value problem arising in the study of scattering of two-dimensional surface water waves by a discontinuity in the surface boundary conditions is presented in this paper. The disconti... A new method to solve the boundary value problem arising in the study of scattering of two-dimensional surface water waves by a discontinuity in the surface boundary conditions is presented in this paper. The discontinuity arises due to the floating of two semi-infinite inertial surfaces of different surface densities. Applying Green's second identity to the potential functions and appropriate Green's functions, this problem is reduced to solving two coupled Fredholm integral equations with regular kernels. The solutions to these integral equations are used to determine the reflection and the transmission coefficients. The results for the reflection coefficient are presented graphically and are compared to those obtained earlier using other research methods. It is observed from the graphs that the results computed from the present analysis match exactly with the previous results. 展开更多
关键词 Fredholm integral equations inertial surface reflection coefficient water wave scattering boundary value problem
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Deformation and failure mechanism of slope in three dimensions 被引量:20
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作者 Yingfa Lu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2015年第2期109-119,共11页
Understanding three-dimensional (3D) slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering. In this paper, the mecha-nisms of progressi... Understanding three-dimensional (3D) slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering. In this paper, the mecha-nisms of progressive failure with thrust-type and pull-type landslides are described in detail. It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development, and a critical stress state element (or the soil slice block) exists between the post-failure stress state and the pre-peak stress state regions. In this regard, two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides, based on the characteristics of shear stress and strain (or tensile stress and strain). Accordingly, a new joint constitutive model (JCM) is proposed based on the current stability analytical theories, and it can be used to describe the mechanical behaviors of geo-materials with softening properties. Five methods, i.e. CSRM (comprehensive sliding resistance method), MTM (main thrust method), CDM (comprehensive displacement method), SDM (surplus displacement method), and MPM (main pull method), for slope stability calculation are proposed. The S-shaped curve of monitored displacement vs. time is presented for different points on the sliding surface during progressive failure process of landslide, and the rela-tionship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve. The comparisons between the predicted and observed loadedis-placement and displacementetime relations of the points on the sliding surface are conducted. The classification of stable/unstable displacementetime curves is proposed. The definition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide (simplified as“collapse body”) is only involved in the main sliding direction, and the strike and the dip are the same as the collapse body. The rake angle is taken as the direction of the sum of sliding forces or the sum of displacements in collapse body, in which the main slip direction is dependent on progressive defor-mation. The reason of non-convergence with finite element method (FEM) in calculating the stability of slope is also numerically analyzed, in which a new method considering the slip surface associated with the boundary condition is proposed. It is known that the boundary condition of sliding surface can be described by perfect elasto-plastic model (PEPM) and JCM, and that the stress and strain of a landslide can be described properly with the JCM. 展开更多
关键词 Failure mechanism New joint constitutive model(JCM) Stability analyses boundary method by sliding surface
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Effects of concurrent grain boundary and surface segregation on the final stage of sintering: the case of Lanthanum doped yttriastabilized zirconia 被引量:2
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作者 M.M.Gong S.Dey +4 位作者 L.J.Wu C.H.Chang H.Li R.H.R.Castro F.Liu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第3期251-260,共10页
Dopants play a critical role in tailoring the microstructure during sintering of compacts. These dopants may form solid solution within the bulk, and/or segregate to the grain boundaries(GBs) and the solidvapor inte... Dopants play a critical role in tailoring the microstructure during sintering of compacts. These dopants may form solid solution within the bulk, and/or segregate to the grain boundaries(GBs) and the solidvapor interfaces(free surfaces), each causing a distinct energetic scenario governing mass transports during densification and grain growth. In this work, the forces controlling the dopant distribution, in particular the possibility of concurrent segregation at both surfaces and GBs, are discussed based on the respective enthalpy of segregation. An equation is derived based on the minimum Gibbs energy of the system to determine enthalpy of segregation from experimental interface energy data, and the results applied to depict the role of La as a dopant on the interface energetics of yttria stabilized zirconia during its final stage of sintering. It is shown that La substantially decreases both GB and surface energies(differently)as sintering progresses, dynamically affecting its driving forces, and consequent grain growth and densification in this stage. 展开更多
关键词 Grain boundary(GB) segregation surface segregation Enthalpy of segregation GB energy surface energy
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Radiation efects on MHD stagnation point flow of nano fluid towards a stretching surface with convective boundary condition 被引量:5
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作者 Noreen Sher Akbar S.Nadeem +1 位作者 Rizwan Ul Haq Z.H.Khan 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第6期1389-1397,共9页
The aim of the present paper is to study the numerical solutions of the steady MHD two dimensional stagnation point flow of an incompressible nano fluid towards a stretching cylinder.The effects of radiation and conve... The aim of the present paper is to study the numerical solutions of the steady MHD two dimensional stagnation point flow of an incompressible nano fluid towards a stretching cylinder.The effects of radiation and convective boundary condition are also taken into account.The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis.The resulting nonlinear momentum,energy and nano particle equations are simplifed using similarity transformations.Numerical solutions have been obtained for the velocity,temperature and nanoparticle fraction profles.The influence of physical parameters on the velocity,temperature,nanoparticle fraction,rates of heat transfer and nanoparticle fraction are shown graphically. 展开更多
关键词 Convective boundary condition Nanoparticles Numerical solutions Radiation effects Stagnation point Stretching surface
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Improved treatments for evaluating horizontal magnetic components through the 3-D FDM in E-polarization induction problems
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作者 CHEN Po-fang(陈伯舫) 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第5期519-525,共7页
To improve the accuracy of the numerical evaluation through the 3-D finite difference method, the surface boundary conditions are added to modify the old program. The author has tested the new program by making calcul... To improve the accuracy of the numerical evaluation through the 3-D finite difference method, the surface boundary conditions are added to modify the old program. The author has tested the new program by making calculations for the model constructed by Wanamaker, et al (1984). The comparison between the numerical results obtained from this paper and those by Wannamaker, et al (1984) indicates that a pronounced improvement is realized in the evaluation of the horizontal magnetic components. Moreover, better calculations for the vertical magnetic components are also obtainable by using the new program. 展开更多
关键词 numerical modeling 3-D finite difference method surface boundary conditions
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Solutions for Toda System on Riemann Surface with Boundary
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作者 Xiao Bao ZHU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2011年第8期1501-1520,共20页
In this paper, we study the solutions for Toda system on Riemann surface with boundary. We prove a sufficient condition for the existence of solution of Toda system in the critical case.
关键词 Toda system Riemann surface with boundary
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