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Grassmannian precoding MU-MIMO scheme

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The Journal of China Universities of Posts and Telecommunications 2008年第3期15卷 105-109,117页

作者： FANG Shu LI Li-hua zhang Ping Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In this article, a Grassmannian precoding multiuser multiple-input multiple-output （MU-MIMO） scheme for downlink transmission is proposed. The proposed MU-MIMO scheme will perform scheduling and precoding simultaneously at the base station, to obtain both the multiuser diversity gain and the precoding gain, to maximize the system capacity. The precoding method is related to Grassmannian precoding, which extends the point-to-point single-user Grassmannian precoding to point-to-multipoint multiuser Grassmannian precoding. It provides further significant system capacity enhancement than the single user MIMO （SU-MIMO） system and also outperforms the block dia^onalization （BD） algorithm under the same simulation environment.

关键词： multiuser MIMO cochannel interference Grassmannian precoding

Study on Nonuniform Deformation of Tailor Rolled Blank During Uniaxial Tension

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Acta Metallurgica Sinica(English Letters) 2015年第9期28卷 1198-1204页

作者： hua-Wei zhang Xiang-hua Liu Li-Zhong Liu Ping Hu Jia-Lu Wu School of Mechanical Engineering and Automation Northeastern University Research Institute of Science and Technology Northeastern University School of Automotive Engineering Dalian University of Technology

The deformation characteristics of tailor rolled blank （TRB） in the course of uniaxial tension were studied by means of analysis, test and simulation. The mechanical analytical model of TRB during uniaxial tension was set up, and the deformation formulae for the thinner side and for the thicker side were derived to quantify the deformation of TRB. On this basis, uniaxial tension tests on TRB and ordinary blanks （the thinner side and the thicker side of TRB） were conducted. Lagrange polynomial interpolation method was adopted to construct the stress-strain fields of unannealed and annealed TRBs for solving TRB material parameters, and then, uniaxial tension simulation on TRB was completed. Deformations and properties of unannealed TRB were compared with those of annealed TRB, and the thinner side and the thicker side were also compared. Finally, the research results were explained by metallurgical structure. The results show that nonuniform deformation happens in TRB during uniaxial tension, and the necking occurs on the thinner side. The agreement of analysis, test and simulation confirms the correctness of the analytical model and the deformation formulae. The findings of this paper can lay the foundation for the future study on TRB stamping formability and provide a way for TRB modeling.

关键词： Tailor rolled blank (TRB) Nonuniform deformation Uniaxial tension Annealing Metallographical

Fabrication of Hydrophilic and Sponge-like PVDF/Brush-like Copolymer Blend Membranes Using Triethylphosphate as Solvent

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Chinese Journal of Polymer Science 2014年第2期32卷 143-150页

作者： Jian-hua Wang Yong-hua zhang You-yi Xu 朱宝库 Hong Xu MOE Key Laboratory of Macromolecular Synthesis and Functionalization MOE Engineering Research Center of Membrane and Water Treatment Technology Department of Polymer Science and Engineering Zhejiang University

Porous PVDF blend membranes with good hydrophilicity and a symmetric structure were prepared by the phase inversion method using amphiphilic brush-like copolymers, P（MMA-r-PEGMA）, as hydrophilic additive and triethylphosphate （TEP） as solvent. P（MMA-r-PEGMA） was synthesized by radical polymerization in TEP. Then the obtained amphiphilic copolymer solution was mixed with PVDF and TEP to prepare the dope solution. The effects of P（MMA-r-PEGMA） content and coagulation composition on membrane morphologies were investigated using scanning electron microscopy （SEM）. The results demonstrated that, even blended with amphiphilic copolymers, a symmetric structure can be formed. Hollow fiber membranes with a mainly symmetric structure were also fabricated. The dry hollow fiber membranes showed good hydrophilicity, high flux and good rejection performance because of their hydrophilic surface and pores wall.

关键词： Poly(vinylidene fluoride) Membrane Triethylphosphate Hydrophilicity Amphiphilic copolymer.

Microstructural evolution and mechanical properties of aging high nitrogen austenitic stainless steels

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 729-736页

作者： Zhou-hua Jiang Zu-rui zhang hua-bing Li Zhen Li Qi-feng Ma School of Materials and Metallurgy Northeastern University Shenyang 110819 China

The microstructural evolution of 18Crl 8Mn2Mo0.77N high nitrogen austenitic stainless steel in aging treatment was investigated by optical microscopy （OM）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that hexagonal intergranular and cellular Cr2N with a=0.478 nm and c=0.444 nm and body-centered cubic intermetaUic X phase with a=0.892 nm precipitate gradually in the isothermal aging treatment. The matrix nitrogen depletion due to the intergranular Cr2N precipitation induces the decay of Vickers hardness, and the formation of cellular Cr2N and X phase causes the increase in the values. The impact toughness presents a monotonic decrease and SEM morphologies show the leading brittle intergranular fracture. The tensile strength and elongation deteriorate obviously except for the sample aged for 1 h in yield strength. Stress concentration occurs when the matrix dislocations pile up at the pre- cipitation and matrix interfaces, and the interracial dislocations may become precursors to the misfit dislocations, which can form small cleavage steps and accelerate the formation of cracks.

关键词： microstructural evolution aging mechanical properties austenitic stainless steel secondary phase

Testing a Four-Dimensional Variational Data Assimilation Method Using an Improved Intermediate Coupled Model for ENSO Analysis and Prediction

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Advances in Atmospheric Sciences 2016年第7期33卷 875-888页

作者： Chuan GAO Xinrong WU Rong-hua zhang Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071 University of Chinese Academy of Sciences Beijing 100029 Key Laboratory of Marine Environmental Information Technology State Oceanic AdministrationNational Marine Data and Information ServiceTianjin 300000 Laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237

A four-dimensional variational （4D-Var） data assimilation method is implemented in an improved intermediate coupled model （ICM） of the tropical Pacific. A twin experiment is designed to evaluate the impact of the 4D-Var data assimilation algorithm on ENSO analysis and prediction based on the ICM. The model error is assumed to arise only from the parameter uncertainty. The ＂observation＂ of the SST anomaly, which is sampled from a ＂truth＂ model simulation that takes default parameter values and has Gaussian noise added, is directly assimilated into the assimilation model with its parameters set erroneously. Results show that 4D-Var effectively reduces the error of ENSO analysis and therefore improves the prediction skill of ENSO events compared with the non-assimilation case. These results provide a promising way for the ICM to achieve better real-time ENSO prediction.

关键词： Four-dimensional variational data assimilation intermediate coupled model twin experiment ENSO prediction

Distributions of Neutron Exposures in AGB Stars and the Galaxy

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Chinese Journal of Astronomy and Astrophysics 2007年第2期7卷 224-234页

作者： Wen-Yuan Cui Feng-hua zhang Wei-Juan zhang Lu zhang Bo zhang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 Department of Physics Hebei Normal University Shijiazhuang 050016 Department of Modern Physics University of Science and Technology of China Hefei 230026 Graduate School of Chinese Academy of Sciences Bejing 100049

Based on the s-process nucleosynthesis model with the 13C（α, n）16O reaction occurring under radiative conditions in the interpulse phases, we investigate the characteristics of the distribution of neutron exposure in low-mass Asymptotic Giant Branch （AGB） stars. We introduce a new concept, the distribution of neutron exposures of the Galaxy （NEG）, to study the chemical evolution characteristics of the Galaxy for s-process elements. Using a chemical evolution model of the Galaxy, we develop a model for the NEG and obtain the evolution results of the NEG in different epochs. The present results appear to reasonably reproduce the distribution of neutron exposures of the solar system （hereafter NES）. The main component and the strong component in the NES are built up in different epochs. The strong component of the s-process is mainly synthesised in the low-mass and metal-poor AGB stars, and the main component is produced by the s-process in the low-mass AGB stars with higher metallicities.

关键词： Galaxy evolution- stars AGB and post-AGB- stars abundances

Acquisition of channel state information for mmWave massive MIMO: traditional and machine learning-based approaches

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Science China(Information Sciences) 2021年第8期64卷 5-20页

作者： Chenhao QI Peihao DONG Wenyan MA hua zhang Zaichen zhang Geoffrey Ye LI School of Information Science and Engineering Southeast University College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Department of Electrical and Electronic Engineering Imperial College London

The accuracy of channel state information(CSI) acquisition directly affects the performance of millimeter wave(mmWave) communications. In this article, we provide an overview on CSI acquisition,including beam training and channel estimation for mmWave massive multiple-input multiple-output *** beam training can avoid the estimation of a high-dimension channel matrix, while the channel estimation can flexibly exploit advanced signal processing techniques. In addition to introducing the traditional and machine learning-based approaches in this article, we also compare different approaches in terms of spectral efficiency, computational complexity, and overhead.

关键词： beam training channel estimation machine learning massive MIMO millimeter wave (mmWave) communications

Regulation of Ti(C,N)deposition on hot surface of refractory in blast furnace hearth

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Journal of Iron and Steel Research International 2024年第6期31卷 1423-1435页

作者： Jian Cao Cui Wang Jjan-liang zhang Ke-xin Jiao Guo-hua zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

Ti(C,N)concentration was found to be lower on the hearth sidewall of a blast furnace and increased gradually toward the bottom of the blast *** Ti(C,N)protective layer in a blast furnace is ***,the formation of a Ti(C,N)protective layer was promoted by studying the heterogeneous nucleation principle of titanium compounds on different substances and regulation measures for the deposition process of titanium compounds on refractories or *** lattice disregistry between the titanium compounds and the main components in the refractory or the main impurities in the protective layer was calculated using a two-dimensional disregistry equation to study the heterogeneous nucleation principle of titanium *** results revealed that in refractory materials,the heterogeneous nucleation of carbonitride is weak when C,SiO_(2),and Al_(2)O_(3) are used as heterogeneous nucleation substrates,and the heterogeneous nucleation of carbonitride is strong when TiO_(2) and SiC are used as heterogeneous nucleation *** nucleation phases,TiC,TiN,Ti(C_(0.3),N_(0.7)),and Ti(C_(0.5),N_(0.5))have similar heterogeneous nucleation ability in single component refractory,and the type of carbonitride has little effect on the lattice *** impurities in the protective layer as the substrate phases are not conducive to the heterogeneous nucleation of *** CaS was used as the substrate phase,the heterogeneous nucleation ability of carbonitride was the *** carbon and alumina were not conducive to the heterogeneous nucleation of carbonitride,but carbon was more unfavourable than alumina.

关键词： Ti(C,N) Lattice disregistry Lattice constant Heterogeneous nucleation Regulation measure

Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection

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Light(Science & Applications) 2021年第4期10卷 600-609页

作者： Jinchao Tong Fei Suo Tianning zhang Zhiming huang Junhao Chu Dao hua zhang School of Electrical and Electronic Engineering Nanyang Technological UniversityNanyang Avenue639798 SingaporeSingapore State Key Laboratory of Infrared Physics Shanghai Institute of Technical

High-performance uncooled millimnetre and terahertz wave detectors are required as a building block for a wide range of *** state-of-the art technologies,however,are plagued by low sensitivity,narrow spectral bandwidth,and complicated ***,we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature *** making a nanogroove array in the grown InSb layer,strong millimetre and terahertz wave surface plasmon polaritons can be generated at the InSb-air interfaces,which results in significant improvement in detecting performance.A noise equivalent power(NEP)of 2.2× 10^(-14)WHz^(-1/2) or a detectivity(D)of 2.7× 10^(12)cmHz^(1/2) W^(-1) at 1.75 mm(0.171 THz)is achieved at room *** lowering the temperature to the thermoelectric cooling available 200 K,the corresponding NEP and D'of the nanogroove device can be improved to 3.8× 10^(-15)WHz^(-1/2) and 1.6× 10^(13) cm Hz^(-1/2) w^(-1),*** addition,such a single device can perform broad spectral band detection from 0.9 mm(0.330 THz)to 9.4 mm(0.032 THz).Fast responses of 3.5μs and 780 ns are achieved at room temperature and 200 K,*** high-performance millimnetre and terahertz wave photodetectors are useful for wide applications such as high capacity communications,walk-through security,biological diagnosis,spectroscopy,and remote *** addition,the integration of plasmonic semiconductor nanostructures paves a way for realizing high performance and multifunctional long-wavelength optoelectrical devices.

关键词： wave spectral terahertz