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BIVARIATE FRACTAL INTERPOLATION FUNCTIONS ON RECTANGULAR DOMAINS

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Journal of Computational mathematics 2002年第4期20卷 349-362页

作者： Xiao-yuan Qian (department of applied mathematics, Dalian university of technology, Dalian 116024, china) department of applied mathematics Dalian University of Technology Dalian 116024

Non-tensor product bivariate fractal interpolation functions defined on gridded rectangular domains are constructed. Linear spaces consisting of these functions are introduced. The relevant Lagrange interpolation problem is discussed. A negative result about the existence of affine fractal interpolation functions defined on such domains is obtained.

关键词： fractal bivariate functions interpolation

Three-Dimensional and Cross-sectional Characteristics of Normal Grain Growth Based on Monte Carlo Simulation

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International Journal of Minerals,Metallurgy and Materials 1998年第3期12卷 129-133,139页

作者： Xiaoyan Song Guoquan Liu(Material Science and Engineering School, university of Science and technology Beijing, Beijing 100083, china)(department of Materials Science and Engineering, hebei university of technology, tianjin 300130, china) Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China departments of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China

An appropriate Monte Carlo method was developed to simulate the three-dimensional normal grain growth more completely. Comparative investigation on the three-dimensional and the cross-sectional characteristics of normal grain growth was done. It was found that the time exponent of grain growth determined from cross-section exhibits the same rule of increasing slowly with time and approaching the theoretical value n = 0.5 of steadygrain growth as the three-dimensional (3-D) system. From change of the number of grains per unit area with timemeasured in cross-section, the state of 3-D normal grain growth may be predicted. The gtain size distribution incross-section is different from that in 3-D system and can not express the evolution characteristic of the 3-D distribution. Furthermore, there exists statistical connection between the topological parameters in cross-section and thosein three-dimensions.

关键词： Monte Carlo simulation normal grain growth three-dimension cross-section characteristics

Inflow conditions for spatial direct numerical simulation of turbulent boundary layers

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 1106-1115页

作者： HUANG ZhangFeng & ZHOU Heng department of Mechanics,tianjin university,tianjin 300072,china Liu-Hui Center of applied mathematics,Nankai university and tianjin university,tianjin 300072,china department of Mechanics Tianjin University Tianjin China Liu-Hui Center of applied mathematics Nankai University and Tianjin University Tianjin China

The inflow conditions for spatial direct numerical simulation(SDNS) of turbulent boundary layers should reflect the characteristics of upstream turbulence,which is a puzzle. In this paper a new method is suggested,in which the flow field obtained by using temporal direct numerical simulation(TDNS) for fully developed turbulent flow(only flow field for a single moment is sufficient) can be used as the inflow of SDNS with a proper transformation. The calculation results confirm that this method is feasible and effective. It is also found that,under a proper time-space transformation,all statistics of the fully developed turbulence obtained by both temporal mode and spatial mode DNS are in excellent agreement with each other,not only qualitatively,but also quantitatively. The normal-wise distributions of mean flow profile,turbulent Mach number and the root mean square(RMS) of the fluctuations of various variables,as well as the Reynolds stresses of the fully developed turbulence obtained by using SDNS,bear similarity in nature.

关键词： inflow conditions spatial direct numerical simulation turbulent boundary layer similarity

“有效降低全社会物流成本”研讨会专家观点综述

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中国流通经济 2024年第5期38卷 3-17页

作者：本刊编辑部《中国流通经济》编辑部

2024年2月24日,习近平总书记主持召开中央财经委员会第四次会议,指出物流是实体经济的“筋络”,强调必须有效降低全社会物流成本,增强产业核心竞争力,提高经济运行效率。基于此,2024年4月24日,北京物资学院党委宣传部、杂志社、科研处... 详细信息

2024年2月24日,习近平总书记主持召开中央财经委员会第四次会议,指出物流是实体经济的“筋络”,强调必须有效降低全社会物流成本,增强产业核心竞争力,提高经济运行效率。基于此,2024年4月24日,北京物资学院党委宣传部、杂志社、科研处联合主办了“有效降低全社会物流成本”研讨会。本次研讨会邀请我国流通物流领域的专家学者,围绕物流服务实体经济和人民群众、物流成本构成、交通运输体系改革、统一高效物流市场构建和现代商贸流通体系完善等问题,发表观点,为探索有效降低全社会物流成本可行路径,构建现代流通体系提供理论支持和实践指导。本刊编辑部对专家阐述的主要观点进行了归纳整理,以飨读者。

关键词：全社会社会物流成本新质生产力流通体系降本增效

Grassmann geometry on symmetric spaces

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Chinese Science Bulletin 1999年第1期44卷 41-44页

作者： JIN Quanqindepartment of mathematics, hebei university, Baoding 071002, china department of mathematics, Nankai university, tianjin 300071,china department of mathematics Hebei University Baoding China department of mathematics Nankai University Tianjin China

A duality principle between Grassmann geometries on compact symmetric spaces and those on noncompact symmetric spaces is proved, which greatly facilitates the study of Grassmann geometry on symmetric spaces. Those Gra... 详细信息

关键词： symmetric spaces Grassmann geometry Cartan decomposition orthogonal symmetric Lie algebra totally geodesic submanifold.

A Win-Win Undergraduate Graduation Design Model for Students, Teachers, and Training Platforms

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Journal of Contemporary Educational Research 2024年第8期8卷 142-146页

作者： Xiaoqing Zhang Lili Wang Tian Zhao hebei Science and technology Normal university Qinhuangdao 066000Hebei ProvinceChina

Undergraduate graduation design is an important link in the process of undergraduate training,and university platforms have invested a lot of manpower and material resources for this ***,while carrying out student training,it has gradually become the consensus of most university platforms to achieve a win-win situation for teachers and training platforms in order to achieve optimization of resource allocation and motivation of student *** discussion and practice,this paper proposes a set of undergraduate graduation design training concepts and training modes with a win-win situation for students,teachers,and training platforms.

关键词： Graduation design Thesis Undergraduate teaching Research project Platform construction

Effect of As Interstitial Diffusionon on the Properties of Undoped Semi-insulating LECGaAs

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Rare Metals 2001年第3期20卷 187-191页

作者： Ruixia Yang, Fuqiang Zhang, Nuofu Chen 1) hebei university of technology, tianjin 300130, china 2) Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, china 河北工业大学天津 300130 中科院半导体所北京 100083

Annealing was carried out at 950 and 1120 degreesC under various As pressure for undoped (ND) semi-insulating (SI) LECGaAs. The effects of annealing on native defects and electrical properties were investigated. Experimental results indicate that, after an annealing at 950 degreesC for 14 h under low As pressure, the Hall mobility decreases and the resistivity increases dramatically for the samples. These changes in electrical properties are due to the generation of intrinsic acceptor defects, and the generation of the intrinsic acceptor defects originates from the outdiffusion of As interstitial at high temperature. The generation of the intrinsic defects and these changes in electrical properties can be suppressed by increasing the applied As pressure during annealing. The concentration of the main donor defect E12 (AsGaVGa) can be decreased by about one order of magnitude by an evacuated annealing at 1120 degreesC for 2-8 h followed by a fast cooling. The decrease in E12 concentration can also be suppressed by increasing the As pressure during annealing.

关键词： semi-insulating GaAs intrinsic acceptor defects As interstitial indiffusion As pressure annealing

A cross-monotonic cost sharing method for the facility location game with service installation costs

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Science china mathematics 2009年第11期52卷 2530-2536页

作者： XU DaChuan department of applied mathematics,Beijing university of technology,Beijing 100124,china department of applied mathematics Beijing University of Technology Beijing China

In this paper,we consider the metric uncapacitated facility location game with service installation costs. Our main result is an 11-approximate cross-monotonic cost-sharing method under the assumption that the install... 详细信息

关键词： facility location game cross-monotonic cost-sharing method linear programming relaxation

The Degree of Symmetry of Certain Compact Smooth Manifolds II

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Chinese Annals of mathematics,Series B 2007年第2期28卷 195-204页

作者： Bin XU department of mathematics, university of Science and technology of china, Hefei 230026, china Chern Institute of mathematics, Nankai university, tianjin 300071, china department of mathematics, Johns Hopkins university, Baltimore, MD 21218, USA. department of mathematics University of Science and Technology of China Hefei China Chern Institute of mathematics Nankai University Tianjin China department of mathematics Johns Hopkins University Baltimore USA

We give the sharp estimates for the degree of symmetry and the semi-simple degree of symmetry of certain compact fiber bundles with non-trivial four dimensional fibers in the sense of cobordism, by virtue of the rigidity theorem of harmonic maps due to Schoen and Yau (Topology, 18, 1979, 361-380). As a corollary of this estimate, we compute the degree of symmetry and the semi-simple degree of symmetry of CP2×V, where V is a closed smooth manifold admitting a real analytic Riemannian metric of non-positive curvature. In addition, by the Albanese map, we obtain the sharp estimate of the degree of symmetry of a compact smooth manifold with some restrictions on its one dimensional cohomology.

关键词：紧光滑流形对称度纤维丛调和映射刚性理论配边