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RELATIONSHIP AMONG EVAPORATION FLUX OF GROUNDWATER, DEPTH OF WATER TABLE AND NEGATIVE PRESSURE HEAD IN BARE SOIL

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Journal of Hydrodynamics 2000年第4期12卷 52-58页

作者： qian, J.z. zhu, X.Y. zhou, N.q. Li, G.Y. Dep. of Earth Sci. Nanjing Univ. Nanjing 210093 China

Evaporation of ground water is a part of moisture circulation in the field. And it is a main natural form in which water transmits from the ground water to the soil water and atmosphere water. According to the simulated experiments, we study the relationship among the evaporation, depth of groundwater table and negative pressure. By theoretical analysis of the experimental results, the main conclusions are drawn as follows. There are two abrupt points in every q-H curve. The locations of the abrupt points are separately in step with the height of top of the capillary fringe and the height of maximal capillary rise in the soil section. When the depth of water table H is small, the evaporation flux of ground water is large. While the depth of water table exceeds the maximal capillary rise of media in vadose zone, the capillary rise breaks up and evaporation flux of groundwater is small. The water content ratio in ground surface tends to be zero and the surface of soil tends to be drought. These conclusions show that the maximal capillary rise of media in vadose zone is an important value in regulating rational depth of ground water to reduce the evaporation of ground water and to increase effective quantity of water resources. In the meantime, these conclusions are of important theoretical and practical significance to reduce the evaporation of ground water, to prevent and cure the salinization of soil, and to make full use of and protect water resources in the northern plains in China.

关键词： Capillarity Evaporation Soils

STABILITY OF MICROSTRUCTURES DURING COOLING PROCESSES OF Al LIqUID METAL

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中国有色金属学会会刊：英文版 1998年第4期8卷 2-7页

作者： Liu, RS Li, JY zhou, z Dong, KJ Peng, P Xie, q zheng, CX Hunan Univ Dept Phys Changsha 410012 Peoples R China Hunan Univ Dept Chem Changsha 410012 Peoples R China

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关键词： stability microstructure liquid metal rapid cooling computer simulation

One-dimensional non-Darcy flow in a semi-infinite porous media:a multiphase implicit Stefan problem with phases divided by hydraulic gradients

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Acta Mechanica Sinica 2017年第5期33卷 855-867页

作者： G.q.zhou Y.zhou X.Y.Shi State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology School of Mechanics and Civil Engineering China University of Mining and Technology JiangSu Collaborative Innovation Center for Building Energy Saving and Construct Technology

One-dimensional non-Darcy flow in a semi-infinite porous media is investigated. We indicate that the non-Darcy relation which is usually determined from experimental results can always be described by a piecewise linear function, and the problem can be equivalently transformed to a multiphase implicit Stefan problem. The novel feature of this Stefan problem is that the phases of the porous media are divided by hydraulic gradients, not the excess pore water pressures. Using the similarity transformation technique, an exact solution for the situation that the external load increases in proportion to the square root of time is developed. The study on the existence and uniqueness of the solution leads to the requirement of a group of inequalities. A similar Stefan problem considering constant surface seepage velocity is also investigated, and the solution, which we indicate to be uniquely existent under all conditions, is established. Meanwhile, the relation between our Stefan problem and the traditional multiphase Stefan problem is demonstrated. In the end, computational examples of the solution are presented and discussed. The solution provides a useful benchmark for verifying the accuracy of general approximate algorithms of Stefan problems, and it is also attractive in the context of inverse problem analysis.

关键词： Moving boundary problem Stefan problem Analytical solution Non-Darcy flow Soil consolidation

When joggers meet robots:the past,present,and future of research on humanoid robots

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Bio-Design and Manufacturing 2019年第2期2卷 108-118页

作者： George H.z.Liu Michael z.q.Chen Yonghua Chen Department of Mechanical Engineering The University of Hong KongPokfulamHong KongPeople’s Republic of China School of Automation Nanjing University of Science and TechnologyNanjing 210094JiangsuPeople’s Republic of China

Spawned by fast-paced progress in new materials and integrate circuit technology,the past two decades have witnessed tremendous development of humanoid robots for both scientific and commercial purposes,*** response and daily life *** the root of this trend are the increasing research interests and cooperation opportunities across different laboratories and *** application-driven requirements of high effectiveness and reliability of humanoid robots led intensive research and development in humanoid locomotion and control *** spite of the progress in the area,challenges such as unnatural locomotion control,inefficient multi-motion planning,and relatively slow disturbances recovery set further requirements for the next generation of humanoid ***,the purpose of this work is to review the current development of highly representative bipedal humanoid robots and discuss the potential to move the ideas and models forward from laboratory settings into the real *** this end,we also review the current clinical understanding of the walking and running dynamics to make the robot more human-like.

关键词： Humanoid robot Walking dynamics Dynamic control Bio-inspired gait Robot efficiency Shock absorption

Basic features of the multiscale interaction between tearing modes and slab ion-temperature-gradient modes

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Chinese Physics B 2019年第12期28卷 237-247页

作者： L Wei z X Wang J q Li z q Hu Y Kishimoto Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China Southwestern Institute of Physics Chengdu 610041China Graduate School of Energy Science Kyoto UniversityGokashoUjiKyoto 1-0011Japan

Nonlinear interaction between tearing modes(TM) and slab ion-temperature-gradient(ITG) modes is numerically investigated by using a Landau fluid model. It is observed that the energy spectra with respect to wavenumbers become broader during the transition phase from the ITG-dominated stage to TM-dominated stage. Accompanied with the fast growth of the magnetic island, the frequency of TM/ITG with long/short wavelength fluctuations in the electron/ion diamagnetic direction decreases/increases respectively. The decrease of TM frequency is identified to result from the effect of the profile flattening in the vicinity of the magnetic island, while the increase of the frequencies of ITG fluctuations is due to the eigenmode transition of ITG induced by the large scale zonal flow and zonal current related to TM. Roles of zonal current induced by the ITG fluctuations in the instability of TM are also analyzed. Finally, the electromagnetic transport features in the vicinity of the magnetic island are discussed.

关键词： magnetic reconnection tearing modes magnetohydrodynamics drift waves nonlinear phenomena

Cleaning Radio Frequency Interference in Pulsar-Folded Data Based on the Conditional Random Fields with an Adaptive Prior

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Research in Astronomy and Astrophysics 2023年第10期23卷 184-191页

作者： Xue Chen J.L.Han W.q.Su z.L.Yang D.J.zhou National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory of FAST NAOCChinese Academy of SciencesBeijing 100101China

Radio astronomy observations are frequently impacted by radio frequency interference(RFI).We propose a novel method,named 2σCRF,for cleaning RFI in the folded data of pulsar observations,utilizing a Bayesian-based model called conditional random fields(CRFs).This algorithm minimizes the“energy”of every pixel given an initial *** standard deviations(i.e.,rms values)of the folded pulsar data are utilized as pixels for all subintegrations and ***-RFI data without obvious interference is treated as“background noise,”while RFI-affected data have different classes due to their exceptional rms *** initial labeling can be automated and is adaptive to the actual *** CRF algorithm optimizes the label category for each pixel of the image with the prior initial *** demonstrate the efficacy of the proposed method on pulsar folded data obtained from Five-hundred-meter Aperture Spherical radio Telescope *** can effectively recognize and tag various categories of RFIs,including broadband or narrowband,constant or instantaneous,and even weak RFIs that are unrecognizable in some pixels but picked out based on their *** results are comparable to those obtained via manual labeling but without the need for human intervention,saving time and effort.

关键词： methods:data analysis techniques:image processing (stars:)pulsars:general

MATRIX INVESTIGATION ON ISAICHEV ORIENTATION RELATIONSHIP

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Acta Metallurgica Sinica(English Letters) 1999年第2期12卷 185-190页

作者： Sheng, z.q. Xiao, H. Nuclear Power Inst of China Chengdu China

By means of TEM technique the orientation relationships of cementite, precipitated from islands of granular bainite during tempering, with ferrite have been observed. By calculating the eigenvalues and eigenvectors of transformation matrix, Isaichev relationship has been analyzed. The results indicate that Isaichev relationship is indeed the sum of Kurdjumov-Sachs relationship and Pitsch relationship, so the viewpoint that the cementite with Isaichev relationship precipitates from austenite, instead of ferrite, was confirmed. Moreover, the matrix calculation shows that three reported orientation relationships among austenite, ferrite and cementite in pearlitic transformation cannot be simultaneously valid. (Edited author abstract) 4 Refs.

关键词： Carbides Crystal orientation Eigenvalues and eigenfunctions Nuclear reactors Pearlitic transformations Phase transitions

Curvature-induced noncommutativity of two different components of momentum for a particle on a hypersurface

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Communications in Theoretical Physics 2021年第2期73卷 73-77页

作者： z Li X Yang q H Liu School for Theoretical Physics School of Physics and ElectronicsHunan UniversiyChangsha 410082China School of Materials Science and Engineering Guilin University of Electronic TechnologyGuilin541004China Synergetice Innovation Center for quantum Efects and Applications(SICqEA) Hunan Normal UniversityChangsha 410081China

As a nonrelativistic particle constrained to remain on an(N−1)-dimensional((N≥2))hypersurface embedded in an N-dimensional Euclidean space,two different components pi and pj(i,j=1,2,3,...N)of the Cartesian momentum of the particle are not mutually commutative,and explicitly commutation relations[p^(^)_(i),p^(^)_(j)](≠0) depend on products of positions and momenta in uncontrollable *** generalized Dupin indicatrix of the hypersurface,a local analysis technique,is utilized to explore the dependence of the noncommutativity on the curvatures around a local point of the *** first finding is that the noncommutativity can be grouped into two categories;one is the product of a sectional curvature and the angular momentum,and another is the product of a principal curvature and the *** second finding is that,for a small circle lying a tangential plane covering the local point,the noncommutativity leads to a rotation operator and the amount of the rotation is an angle anholonomy;and along each of the normal sectional curves centering the given point the noncommutativity leads to a translation plus an additional rotation and the amount of the rotation is one half of the tangential angle change of the arc.

关键词： constrained motion quantization hypersurface Dirac brackets geometric momentum

TESTING INEqUALITY CONSTRAINTS IN A LINEAR REGRESSION MODEL WITH SPHERICALLY SYMMETRIC DISTURBANCES

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Journal of Systems Science & Complexity 2014年第6期27卷 1204-1212页

作者： zHU Rong zhou Sherry z F Academy of Mathematics and Systems Science Chinese Academy of Sciences Department of Management Sciences City University of Hong Kong

This paper develops a Wald statistic for testing the validity of multivariate inequality constraints in linear regression models with spherically symmetric disturbances,and derive the distributions of the test statistic under null and nonnull *** power of the test is then *** evaluations are also carried out to examine the power performances of the test for the case in which errors follow a multivariate student-t(Mt) distribution.

关键词： Inequality constraint spherically symmetric distribution Wald test.