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MUSIC-Based Pilot Decontamination and Channel Estimation in Multiuser Massive MIMO System

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Journal of Electronic Science and Technology 2020年第3期18卷 266-275页

作者： wei-Chiang wu Department of Electrical Engineering Da-Yeh UniversityChanghua 51591

This paper addresses the problem of channel estimation in a multiuser multi-cell wireless communications system in which the base station(BS)is equipped with a very large number of antennas(also referred to as"massive multiple-input multiple-output(MIMO)").We consider a time-division duplexing(TDD)scheme,in which reciprocity between the uplink and downlink channels can be *** estimation is essential for downlink beamforming in massive MIMO,nevertheless,the pilot contamination effect hinders accurate channel estimation,which leads to overall performance *** from the asymptotic orthogonality between signal and interference subspaces for non-overlapping angle-of arrivals(AOAs)in the large-scale antenna system,we propose a multiple signals classification(MUSIC)based channel estimation algorithm during the uplink *** and numerical results verify complete pilot decontamination and the effectiveness of the proposed channel estimation algorithm in the multiuser multi-cell massive MIMO system.

关键词： Massive multiple-input multiple-output(MIMO) multiple signals classification(MUSIC) multiuser MIMO(MU-MIMO) pilot contamination time-division duplexing(TDD)

Anomaly detection by exploiting the tracking trajectory in surveillance videos

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Science China(Information Sciences) 2020年第5期63卷 197-199页

作者： Zixuan XUE wei wu Faculty of Information Technology Beijing University of Technology State Key Laboratory of Virtual Reality Technology and Systems Beihang University

Surveillance systems have become increasingly ubiquitous, which has led to a requirement to detect anomalies for efficiently preventing terrorism and reducing crimes. The increasing number of surveillance networks has imposed major technical challenges on intelligent anomaly detection because of the inconsistent appearance of pedestrians owing to posture deformation and clutter in video

关键词： Anomaly detection by exploiting the tracking trajectory in surveillance videos frame

Discrete DNA Three-dimensional Nanostructures： the Synthesis and Applications

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Chinese Journal of Polymer Science 2017年第1期35卷 1-1,2-24页

作者： Xiao-rong wu Chen-wei wu 张川 School of Chemistry and Chemical Engineering State Key Laboratory of Metal Matrix Composites Shanghai Key Laboratory of Electrical Insulation and Thermal Ageing Shanghai Jiao Tong University

Structural DNA nanotechnology, an emerging technique that utilizes the nucleic acid molecule as generic polymer to programmably assemble well-defined and nano-sized architectures, holds great promise for new material synthesis and constructing functional nanodevices for different purposes. In the past three decades, rapid development of this technique has enabled the syntheses of hundreds and thousands of DNA nanostructures with various morphologies at different scales and dimensions. Among them, discrete three-dimensional （3D） DNA nanostructures not only represent the most advances in new material design, but also can serve as an excellent platform for many important applications. With precise spatial addressability and capability of arbitrary control over size, shape, and function, these nanostructures have drawn particular interests to scientists in different research fields. In this review article, we will briefly summarize the development regarding the synthesis of discrete DNA 3D nanostructures with various size, shape, geometry, and topology, including our previous work and recent progress by other groups. In detail, three methods majorly used to synthesize the DNA 3D objects will be introduced accordingly. Additionally, the principle, design rule, as well as pros and cons of each method will be highlighted. As functions of these discrete 3D nanostructures have drawn great interests to researchers, we will further discuss their cutting-edge applications in different areas, ranging from novel material synthesis, new device fabrication, and biomedical applications, etc. Lastly, challenges and outlook of these promising nanostructures will be given based on our point of view.

关键词： DNA self-assembly DNA 3D nanostructure Nanocarrier Biosensor Nanomedicine

Toward the Energy Efficiency of Resource Allocation Algorithms for OFDMA Downlink MIMO Systems

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Journal of Electronic Science and Technology 2019年第4期17卷 357-370页

作者： wei-Chiang wu the Department of Electrical Engineering Da-Yeh University

The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access(OFDMA)based systems has recently attracted significant ***,most studies focus on maximizing the system throughput and spectral *** the green radio is essential in 5G and future networks,the energy efficiency becomes the major *** this paper,we develop four resource allocation schemes in the downlink OFDMA network and the main focus is on analyzing the energy efficiency of these ***,we employ the advanced multi-antenna technology in a multiple input-multiple output(MIMO)*** first scheme is based on transmit spatial diversity(TSD),in which the vector channel with the highest gain between the base station(BTS)and specific antenna at the remote terminal(RT)is chosen for *** second scheme further employs spatial multiplexing on the MIMO system to enhance the *** space-division multiple-access(SDMA)scheme assigns single subcarrier simultaneously to RTs with pairwise“nearly orthogonal”spatial *** the fourth scheme,we propose to design the transmit beamformers based on the zero-forcing(ZF)criterion such that the multi-user interference(MUI)is completely *** analyze the tradeoff between the throughput and power consumption and compare the performance of these schemes in terms of the energy efficiency.

关键词： Energy efficiency multiple input-multiple output(MIMO) multi-user resource allocation orthogonal frequency division multiple access(OFDMA) space-division multiple-access(SDMA) spatial multiplexing

Data mining to effect of key alloying elements on corrosion resistance of low alloy steels in Sanya seawater environmentAlloying Elements

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Journal of Materials Science & Technology 2021年第5期64卷 222-232页

作者： Xin wei Dongmei Fu Mindong Chen wei wu Dequan wu Chao Liu School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China Beijing Engineering Research Center of Industrial Spectrum Imaging University of Science and Technology BeijingBeijing 100083China SINOPEC Research Institute of Safety Engineering Qingdao266100China Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China

In this paper,the relationship model between seawater environment,chemical composition and corrosion potential of low alloy steel is established and the distribution of corrosion potential of low alloy steel with changes in key alloying elements is *** research was carried out with the following steps:Firstly,the relationship model between corrosion potential of low alloy steel and its influencing factors was established by data dimension reduction and artificial neural network(ANN).Secondly,key alloying elements of experimental steels were selected out by Pearson correlation analysis,then the corrosion resistance element model was visualized to show the effect of key alloying elements on corrosion potential of low alloy ***,corrosion potential of low alloy steel with the change of key alloying elements was classified and visualized by classification *** mining results can reflect the validity of the proposed mining methods to a certain extent and provide an intuitive data basis for the development of high-quality and low-cost low alloy steels.

关键词： Low alloy steel Corrosion potential Key alloying elements Corrosion-resistant alloy Artificial neural network Data-driven model

A Multiple-Relaxation-Time Lattice Boltzmann Model for Natural Convection in a Hydrodynamically and Thermally Anisotropic Porous Medium under Local Thermal Non-Equilibrium Conditions

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Journal of Thermal Science 2020年第3期29卷 609-622页

作者： YANG Bo wu wei LI Maodong ZHAI wei Guangzhou Special Pressure Equipment Inspection and Research Institute Guangzhou 510663China School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou 510640China

To investigate the natural convective process in a hydrodynamically and thermally anisotropic porous medium at the representative elementary volume(REV)scale,the present work presented a multiplerelaxation-time lattice Boltzmann method(MRT-LBM)based on the assumption of local thermal non-equilibrium conditions(LTNE).Three sets of distribution function were used to solve the coupled momentum and heat transfer *** set was used to compute the flow field based on the generalized non-Darcy model;the other two sets were used to solve the temperature fields of fluid and solid under the *** describe the anisotropy of flow field of the porous media,a permeability tensor and a Forchheimer coefficient tensor were introduced into the ***,a heat conductivity tensor and a special relaxation matrix with some off-diagonal elements were selected for the thermal ***,by selecting an appropriate equilibrium moments and discrete source terms accounting for the local thermal non-equilibrium effect,as well as choosing an off-diagonal relaxation matrix with some specific elements,the presented model can recover the exact governing equations for natural convection under LTNE with anisotropic permeability and thermal conductivity with no deviation terms through the Chapman-Enskog ***,the proposed model was adopted to simulate several benchmark *** agreements with results in the available literatures can be achieved,which indicate the wide practicability and the good accuracy of the present model.

关键词： lattice Boltzmann method natural convection in anisotropic porous medium local thermal non-equilibrium

Desulfurizer desulphurization kinetics by the injection method

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Journal of University of Science and Technology Beijing 2008年第4期15卷 375-378页

作者： wei wu Zhijun Han Yanbin Hu wei wu2 Metallurgical Technology Institute Central Iron ＆ Steel Research Institute Beijing 100081 China

To obtain a better desulphurization effect in hot metal, suitable desulfurizers should be selected first according to thermodynamics. However, the effect of desulphurization is also strongly affected by kinetics. The conditions of different desulfurizers （Mg, CaC2, and lime） penetrating into hot metal, the rising up velocity in iron melt, residence time, and dissolving time are theoretically calculated and analyzed. The results are helpful to select the desulphurization process and equipment and to improve the desulphurization effect.

关键词： hot metal desulphurization desulphurization kinetics injection

Multiple magnetic transitions in single crystals of Ce12Fe57.5As41 and La12Fe57.5As41

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Science China(Physics,Mechanics & Astronomy) 2018年第12期61卷 53-57页

作者： wei wu Jianlin Luo Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Quantum Matter Beijing 100084China

Measurements of magnetic and transport properties were performed on needle-shaped single crystals of Ce_(12)Fe_(57.5)As_(41)and La_(12)Fe_(57.5)As_(41).The availability of a complete set of data enabled a side-by-side comparison between these two rare earth *** compounds exhibited multiple magnetic orders within 2-300 K and metamagnetic transitions at various *** transitions with Curie temperatures of 100 and 125 K were found for Ce_(12)Fe_(57.5)As_(41)and La_(12)Fe_(57.5)As_(41),respectively,followed by antiferromagnetic type spin reorientations near Curie *** magnetic properties underwent complex evolution in the magnetic field for both *** antiferromagnetic phase transition at about 60 K and 0.2 T was observed merely for Ce_(12)Fe_(57.5)As_(41).The field-induced magnetic phase transition occurred from antiferromagnetic to ferromagnetic structure.A strong magnetocrystalline anisotropy was evident from magnetization measurements of Ce_(12)Fe_(57.5)As_(41).A temperature-field phase diagram was present for these two rare earth *** addition,a logarithmic temperature dependence of electrical resistivity was observed in the two compounds within a large temperature range of 150-300 K,which is rarely found in 3D-based *** may be related to Kondo scattering described by independent localized Fe 3d moments interacting with conduction electrons.

关键词： multiple magnetic phase transitions metamagnetic transition Kondo scattering

Application of Al-free deoxidizer in rail steel manufacture

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Journal of University of Science and Technology Beijing 2008年第5期15卷 534-537页

作者： wei wu Liu Liu Metallurgical Technology Research Department Central Iron ＆ Steel Research Institute Beijing 100081 China

Because there are a lot of influences of alumina inclusions on the performance of rail steel,it is reasonable to adopt the deoxidization method with Al-free deoxidizer. According to the characteristics of Al-free deoxidization process,the control of aluminum content,the deoxidization with ladle furnace（LF） slag,the deoxidization process under vacuum by carbon,and the inclusions modification technology by calcium treatment were studied. All of them were applied to practical production. The results indicate that the adoption of Al-free deoxidization process leads to the total oxygen content in the steel below 20 ppm,which meets the requirement of clean rail steel.

关键词： rail steel deoxidizer refining oxygen activity