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Analysis of the characteristics of the harmonics coefficient J_2 of the Earth's gravity field in different periods

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Chinese Science Bulletin 2012年第14期57卷 1626-1630页

作者： qu WeiJing wu Bin Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The characteristics of the geopotential coefficient J2 in different periods are analyzed using satellite laser ranging data spanning the last 27 *** satellites used in the analysis are Lageos1 and *** variations in J2 are obtained by determining the dynamic *** results show that there are strong seasonal and long-term *** different data spans,the seasonal variations agree well in terms of both amplitude and *** all the data,the amplitude and phase of the annual term are 2.5 10-10 and 127°,respectively,while the amplitude and phase of the semiannual term are 0.94 10-10 and 213°,*** the case of long-term variation,the secular variation in J2(J2) is-2.2 10-11 a-1 from 1984 to 2010.J2 differs for the different periods because of interannual variations,such as the "1998 anomaly".Another anomaly may have taken place during *** the cause of the anomaly is unknown,it is an important observational constraint on the shape of the Earth.

关键词：地球重力场谐波系数特征卫星激光测距长期变化季节变化年际变化形状约束

Influence of boron contents on properties of AlMgB films prepared by RF magnetron sputtering

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Rare Metals 2012年第2期31卷 164-167页

作者： qu, Wenchao wu, Aimin wu, Zhanling Bai, Yizhen Jiang, Xin School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China School of Physics and Optoelectronic Technology Dalian University of Technology Dalian 116024 China Institute of Materials Engineering University of Siegen Siegen D-57076 Germany

Ternary AlMgB thin films were synthesized on silicon (100) substrate at 573 K by radio frequency (RF) magnetron sputtering method using one Al/Mg co-target and one boron target. The thickness of the as-deposited thin film was controlled to 500 nm by adjusting deposition time. The influences of sputtering powers on the elemental contents and structural and mechanical properties were investigated by electron probe microanalysis (EPMA), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and nanoindentation system. At the same time, the ball-on-disk tribometer was used to measure the friction behavior of the films. Experimental results indicate that the as-deposited boron-rich films are primarily amorphous structure and possess a dramatic high hardness up to 39 GPa with 99.03 at.% boron. Obviously, it has exceeded the hardness value of 32 GPa of pure AlMgB 14 bulk material prepared by sintering method. Furthermore, the friction coefficients of the thin films exhibit an average value as low as 0.3, which is considered as the effect of self-lubricating.

关键词： AlMgB magnetron sputtering elemental content properties

Shared aperture metasurface antenna for electromagnetic vortices generation with different topological charges

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Chinese Physics B 2021年第8期30卷 337-344页

作者： He Wang Yong-Feng Li Shao-bo qu Department of Basic Sciences Air Force Engineering UniversityXi'an 710051China

Vortex beams carrying orbital angular momentum(OAM)have aroused great interest of both scientific and engineering ***,generating OAM with different topological charges in a shared aperture is regarded as a potential route to expanding the communication capacity,which yet is an academic challenging *** this work,a paradigm of designing metasurface-based shared aperture antenna for generating polarization-dependent vortex beams with distinct topological charges is *** unit cells that can tailor different resonance phase profiles in two orthogonal orientations are used to assemble a metasurface *** a proof-of-concept,a planar reflector antenna is designed with two Vivaldi sources,which can generate x-and y-polarized vortex beams with topological charges of l=-1 and l=-2,*** the simulation results and the measurement results are in good agreement,which demonstrates the feasibility of our ***,this work provides a new route to achieving vortex beams carrying different topological charges in the same frequency band,which may have potential applications in communication systems.

关键词： metasurface electromagnetic vortex antenna orbital angular momentum

Simulation Analyses of Two On-Ramp Lane Arrangements

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Journal of the Operations Research Society of China 2020年第3期8卷 375-390页

作者： Xu Wang Xiao-bo qu Pan Li Griffith School of Engineering Griffith UniversityGold CoastQLD 4222Australia Department of Architecture and Civil Engineering Chalmers University of TechnologySE-41296 GothenburgSweden School of Urban Rail Transportation Soochow UniversitySuzhou 215131JiangsuChina

Ramps are vital pieces of infrastructure connecting city traffic networks to *** performance of a ramp is to some extent determined by the on-ramp lane *** this paper,our primary aim is to evaluate the performance in terms of travel time and vehicle emissions for two on-ramp lane arrangements:added lane and zip *** estimate the travel time and CO_(2) emissions on the basis of the speed,and acceleration of vehicles in accordance with the improved comprehensive modal emission model(CMEM),and then analyse the impacts of traffic volume and heavy goods vehicles(HGVs)on travel time and *** impacts of main road traffic flow on travel time and emissions for the two on-ramp lane arrangements are analysed under scenarios with traffic volumes of 800,1000,1200,1400,1600 and 1800 vehs/h/***,the relationships between travel time,emissions and various proportions of HGVs(2%,4%,6%,8%and 10%)for both on-ramp lane arrangements are evaluated as *** eventually present emission contour charts for the two onramp lane arrangements based on the possible combinations of traffic volumes and HGV percentages.

关键词： On-ramp lane arrangement comprehensive modal emission model(CMEM) Micro-traffic simulation model Travel time CO_(2)emissions Traffic volume heavy goods vehicles(HGVs)

Reconfigurable Transmitter Coil Structure for Highly Efficient and Misalignment-insensitive Wireless Power Transfer Systems in Megahertz Range

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Chinese Journal of Electrical Engineering 2019年第2期5卷 56-62页

作者： Lihao wu bo Zhang School of Electric Power South China University of TechnologyGuangzhou 510641China

The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size *** this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-sparse configuration is proposed to achieve a high quality factor(Q-factor)and uniform magnetic field,which ensures high efficiency and improves the misalignment tolerance for several-megahertz WPT ***,a closed-form expression for the Q-factor is provided and analyzed for coil *** using this method,a TX-coil with an outer diameter of 100 mm and a wire diameter of 1.5 mm is designed and tested at 1 *** element method simulations and experimental results demonstrate that the Q-factor is increased by about 8%in comparison with evenly spaced planar spiral coils,which is achieved while ensuring a relatively uniform magnetic field.

关键词： High quality factor planar spiral coil structure optimization uniform magnetic field wireless power transfer

Pointwise characterizations of curvature and second fundamental form on Riemannian manifolds

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Science China Mathematics 2018年第8期61卷 1407-1420页

作者： Fengyu Wang bo wu Center for Applied Mathematics Tianjin University Department of Mathematics Swansea University School of Mathematical Sciences Fudan University

Let M be a complete Riemannian manifold possibly with a boundary?*** any C^1-vector field Z,by using gradient/functional inequalities of the(reflecting)diffusion process generated by L:=?+Z,pointwise characterizations are presented for the Bakry-Emery curvature of L and the second fundamental form of?M if it *** characterizations extend and strengthen the recent results derived by Naber for the uniform norm‖RicZ‖∞on manifolds without boundaries.A key point of the present study is to apply the asymptotic formulas for these two tensors found by the first author,such that the proofs are significantly simplified.

关键词： curvature second fundamental form diffusion process path space

SIMULATIONS OF MECHANICAL BEHAVIOR OF POLYCRYSTALLINE COPPER WITH NANO-TWINS

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Acta Mechanica Solida Sinica 2008年第3期21卷 189-197页

作者： bo wu Yueguang Wei State-Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Mechanical behavior and microstructure evolution of polycrystalline copper with nano-twins were investigated in the present work by finite element simulations. The fracture of grain boundaries are described by a cohesive interface constitutive model based on the strain gradient plasticity theory. A systematic study of the strength and ductility for different grain sizes and twin lamellae distributions is performed. The results show that the material strength and ductility strongly depend on the grain size and the distribution of twin lamellae microstructures in the polycrystalline copper.

关键词： nanocrystalline twinned copper mechanical behavior cohesive model finite element simulation

A Note on the Perturbed Compound Poisson Risk Model with a Threshold Dividend Strategy

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Acta Mathematicae Applicatae Sinica 2009年第2期25卷 205-216页

作者： bo Li Rong wu School of Mathematical Sciences and LPMC Nankai University Tianjin 300071 China

In this paper, we consider the Perturbed Compound Poisson Risk Model with a threshold dividend strategy （PCT）. Integro-differential equations （IDE） for its Cerber-Shiu functions and dividend payments function are ... 详细信息

关键词： Gerber-Shiu function threshold dividend strategy expected discounted payments function integro-differential equation

Biocatalytic Synthesis of Pyruvate from DL-lactate with Enzymes in Pseudomonas sp.

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Chinese Chemical Letters 2002年第12期13卷 1213-1216页

作者： Jing Song GU Ping XU Yin bo qu State Key Laboratory of Microbial Technology Shandong UniversityJinan 250100 The school of Chemistry and Environmental Engineering Jinan UniversityJinan 250002

A novel method of preparing pyruvate from DL-lactate catalyzed by enzymes from a bacterial strain of Pseudomonas sp. SM-6 was proposed. Catalytic processes of cell-free extract enzymes and immobilized enzymes were ev... 详细信息

关键词： Pyruvate DL-lactate biocatalyst enzyme Pseudomonas.