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SIMULATION OF SOLUTE TRANSPORT IN A PARALLEL SINGLE FRACTURE WITH LBM/MMP MIXED METHOD

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Journal of Hydrodynamics 2008年第3期20卷 365-372页

作者： TAN ye-fei ZHOU Zhi-fang College of Civil Engineering Hohai University NanJing 210098 China

This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have several advantages over the LBM and Moment Propagation （MP） mixed method which leads to negative concentrations under some conditions in computation. The disadvantage of LBM/MP has been overcome to a certain extent. Also, this work presents an LBM solution of modeling single fractures with uniformly or randomly distributed grains, which can provide a new path of applying the LBM in solute transport simulation in fractures.

关键词： Lattice Boltzmann Method (LBM) Modified Moment Propagation (MMP) method LBM/MMP mixed method single fracture solute transport rough fracture

Screening Effect in Isotropic Gaussian Processes

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Acta Mathematica Sinica,English Series 2020年第5期36卷 512-534页

作者： Jing Yu BAO fei ye Ying YANG Department of Mathematical Sciences Tsinghua UniversityBeijing 100062.P.R.China School of Statistics Capital University of Economics and BusinessBeijing 100026P.R.China

The screening effect is the phenomenon that optimal linear prediction of a spatial process on an unobserved location mostly depends on nearby *** is,the optimal predictor based on just nearby observations yields a good approximation of which based on the whole large ***,the approximation does not always perform well since the screening effect may not hold in all *** determine when the screening effect holds is an important issue in spatial *** paper provides some sufficient conditions for ensuring an asymptotic screening effect in Rd based on the spectral density of the underlying isotropic Gaussian process and the geometries of nearby *** results apply to isotropic processes with an arbitrary degree of *** we are predicting at origin,the conditions are(1)the spectral density is nearly a constant in balls of finite radius far from the origin,(2)the positions of nearby observations do not fall on a curve with non-zero intercept whose degree is less or equal to the order of mean square differentiability of the *** conditions are easy to verify in *** rates of the asymptotic screening effect are also *** rates depend on the rate of decrease of the spectral *** studies on the screening effect for finite samples are also provided.

关键词： Spatial statistics spectral analysis kriging screening effect

Fast Algorithm for Inverse Two-Dimensional S Transform and Its Application in Time-Frequency Filtering for SAR Image Despeckling

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Chinese Journal of Electronics 2016年第1期25卷 100-105页

作者： GAO fei ZHANG ye WANG Jun SUN Jinping School of Electronic and Information Engineering Beihang University

S transform is a time-frequency representation which has been applied in various fields, yet suffers the problem of time and resource consumption. In order to overcome this problem and facilitate its application in image analysis, we introduce a fast algorithm for inverse twodimensional S transform. A two-dimensional S transform time-frequency filter for Synthetic aperture radar(SAR)image despeckling is proposed on the basis of this fast algorithm. Synthetic and actual SAR images are both used to quantitatively evaluate its performance. The proposed algorithm is compared with several classical algorithms with better results both in speckle noise reduction and detail preservation.

关键词： Time-frequency representation Fast al gorithm Two-dimensional S transform Time-frequency filter Synthetic aperture radar(SAR) image Speckle noise reduction

An overview of the mission and technical characteristics of Change'4 Lunar Probe

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Science China(Technological Sciences) 2017年第5期60卷 658-667页

作者： ye PeiJian SUN ZeZhou ZHANG He LI fei China Academy of Space Technology Beijing 100094 China Institute of Spacecraft System Engineering Beijing 100094 China

Change＇4 Lunar Probe will softly land on the farside of the Moon for the first time of all mankind and carry out in-situ and rovering exploration. In this paper, the scientific significance and engineering difficulties of Change＇4 are introduced and the probe＇s general design, including the aspects of landing site selection, relay communication, trajectory design of relay satellite is explained. Besides, four key technologies, namely safe landing strategy on complex terrain, orbit design and control of libration point 2, relay communication on L2, radioisotope thermoelectric generator （RTG） and electric-thermal utilization, as well as how to realize them are also discussed. Finally the prospect of the prominent technological breakthrough of Change＇4 is described.

关键词： Change'4 farside relay communication libration point South-Pole Aitken Basin RTG

Development of sandwich joining piece to fabricate segmented half-Heusler/skutterudite thermoelectric joints

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Rare Metals 2021年第7期40卷 1966-1970页

作者： Wei-An Wang Xiao-Ya Li Yun-fei Xing ming Gu Long-Hui Fang ye-Feng Bao Jin-Hui Fan School of Mechanical and Electrical Engineering Hohai UniversityChangzhou 213022China The State Key Lab of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China School of Mechanical Engineering Donghua UniversityShanghai 201620China

Sn/Ni-Sn/Sn sandwich joining piece was developed and applied to fabricate segmented half-Heusler/skutterudite thermoelectric joints,and high-temperature service behavior of the joints was *** microstructure and contact resistance of the joint before and after aging were *** joints are well bonded and no cracks appear at the interfaces of the joint before and after aging,which can be attributed to the formation of high-melting point intermetallic *** electrical resistance crosses the joining layer smoothly and the contact resistance is *** results show that the sandwich joining piece is effective and flexible,and promising for the preparation of segmented thermoelectric devices.

关键词： Sandwich joining piece Segmented thermoelectric joint Microstructure Contact resistance

Power spectral properties of the soft spectral states in four black hole transients

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Research in Astronomy and Astrophysics 2021年第7期21卷 143-154页

作者： Dong-ming Mao Wen-fei Yu Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China University of Chinese Academy of Sciences Beijing 100049China

The X-ray variability in the soft X-ray spectral state of black hole binaries is primarily characterized by a power-law noise(PLN), which is thought to originate from the propagation of the modulation in the mass accretion rate of a standard accretion disk flow. Such a PLN has also been revealed in the disk spectral component in the hard and the intermediate states in several black hole binaries. Here we present an investigation of the Rossi X-ray Timing Explorer(RXTE) observations of four black hole transients in which soft spectral states were observed twenty times or more. We show that in the soft spectral state, the PLN index varied in a large range between –1.64 and –0.62, and the fractional rms variability calculated in the 0.01 – 20 Hz frequency range reached as large as 7.67% and as low as 0.83%. Remarkably,we have found evidence of an inclination dependence of the maximal fractional rms variability, the averaged fractional rms variability and the fractional rms variability of the median in the sample based on current knowledge of inclination of black hole binaries. An inclination dependence has only been predicted in early magnetohydrodynamic simulations of isothermal disks limited to a high-frequency regime. In theory,the noise index is related to the physics of inward propagation of disk fluctuations, while the fractional rms amplitude reflects the intrinsic properties of the magnetohydrodynamic nature of the accretion *** results therefore suggest that X-ray variability in the soft state can be used to put constraints on the properties of the accretion flow as well as the inclination of the accretion disk.

关键词： X-rays:general X-rays:binaries X-rays:individual:4U 1630-47 H 1743-322 XTE J1817-330 XTE J1859+226

Kinematics of Non-axially Positioned Vesicles through a Pore

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Chinese Journal of Polymer Science 2020年第7期38卷 776-783,I0008页

作者： Yun-Long Han ming-ming Ding Rui Li Tong-fei Shi School of Materials Science and Engineering Changchun University of Science and TechnologyChangchun 130022China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China

We employ finite element method to investigate the kinematics of non-axially positioned vesicles through a *** complete the coupling between fluid flow and the vesicle membranes,we use the fluid structure interactions with the arbitrary Lagrangian Eulerian *** results demonstrate that the vesicles show different deformations in migration process,in turn an oblique ellipse-shape,slipper-shape,*** find that the rotation angle of non-axially positioned vesicles mainly shows the trend of increase,besides the small fluctuation induced by deformation ***,when the vesicles move towards the axis of the channel,the rotation angle exhibits a decrease because of the decrease of the shear ***,rotation of axially positioned vesicles hardly occur due to symmetrical shear *** results further indicate that the rotation is faster nearby the pore for non-axially positioned *** work answers the mapping between the positions of vesicles and deformed states,as well as the change of rotation angle and rotation velocity,which can provide helpful information on the utilization of vesicles in pharmaceutical,chemical,and physiological processes.

关键词： Vesicles Narrow pore Rotation angle Rotation velocity

APPLICATION OF LARGE SCALE TURBULENT SIMULATION FOR WATER QUALITY MODELLING OF THE YANGTZE RIVER

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Journal of Hydrodynamics 1993年第2期5卷 1-12页

作者： Deng, Lian-mu ye, ming Yangtze Water Resources Protection Inst Hubei China

Large scale turbulent structures play an important role in mass transport of natural river turbulence diffusion, After adopting the theory of Large Scale Turbulent Simulation to natural rivers, some 1-D stream quality models, such as QUAL-II, have been widely applied to large, middle and small rivers in China with reasonable success. Moreover, on this basis, 2-D and 3-D river quality models have also been developed. Both 2-D and 3-D models used upwind scheme plus Peaceman-Rachford's alternating scheme in the first one and Douglas' scheme in the second one. These models have also been successfully applied to the Yangtze River as well as some middle and small rivers in China.

关键词： Computer simulation Diffusion Dispersions Mathematical models Turbulent flow Water quality

Effects of the Recombination of Nucleons into α-Particles on the R-process in Proto-magnetar Wind

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Chinese Physics Letters 2012年第6期29卷 303-306页

作者： CHEN Yan-Jun YUAN ye-fei Department of Physics and Electronic Science Changsha University of Science and TechnologyChangsha 410114 Center for Astrophysics University of Science and Technology of ChinaHefei 230026

We take the recombination of nucleons to α-particles into account in proto-magnetar winds and evaluate its effects on r-process *** proto-magnetar winds are described in the time-independent Newtonian magnetohydrodynamic wind *** is found that stellar rotation and strong magnetic fields significantly affect the properties of the ***,the fact that the recombination of nucleons can enhance the wind entropy by approximately twenty percent and somewhat reduce the expansion timescale indicates that the effects of this recombination on the r-process can not be ignored.

关键词： process rotation Newtonian