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Improved Calculation of Turbulence Parameters Based on Six Tropical Cyclone Cases:Implication to Wind Turbine Design in Typhoon-Prone Areas

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Journal of Meteorological Research 2019年第5期33卷 895-904页

作者： Binglan WANG zhiqiang he Lili SONG Wenchao CheN Beijing Jiutian Weather Technology Co. Ltd.Beijing 100081 Public Meteorological Service Center China Meteorological AdministrationBeijing 100081 North China Regional Meteorological Center Civil Aviation Administration of ChinaBeijing 100621 Guangdong Meteorological Disaster Prevention Technology Service Center Guangzhou 510080

In view of the absence or insufficiency of tropical cyclone(TC) turbulence parameters in current design standards of wind turbines, in this paper, TC turbulence parameter models with roughness length involved are developed based on six landfall TCs observed from meteorological towers located on various underlying surfaces, so as to provide references for the wind turbine design under TC conditions. Firstly, the roughness length values are examined in order to reduce the effect on turbulence parameters of the various underlying surfaces. On this basis, the reference turbulence intensity is normalized by the roughness length. The related turbulence parameters are parameterized, including the turbulence standard deviation and the turbulence spectrum;and the turbulence parameters available under TC conditions for turbulence turbine design are presented finally. Comparisons of the wind parameter models presented in this paper with those used in current turbine design standards suggest that the former can represent TC characteristics more accurately. In order to withstand TCs, we suggest that the turbulence parameter models recommended in this paper be included in future wind turbine design standards under TC conditions.

关键词： tropical cyclone turbulence parameter models wind turbine

Lattice reduction aided belief propagation for massive MIMO detection

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Science China(Information Sciences) 2019年第4期62卷 127-139页

作者： Senjie ZHANG zhiqiang he Kai NIU Shi JIN Hong CheNG Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications National Mobile Communications Research Laboratory Southeast University Intel Labs China

Efficient massive MIMO detection for practical deployment, which is with spatially correlated channel and high-order modulation, is a challenging topic for the fifth generation mobile communication(5G). In this paper, lattice reduction aided belief propagation(LRA-BP) is proposed for massive MIMO detection. LRA-BP applies the message updating rules of Markov random field based belief propagation(MRF-BP) in lattice reduced MIMO system. With the lattice reduced, well-conditioned MIMO channel,LRA-BP obtains better message updating and detection performance in spatially correlated channel than MRF-BP. Log-domain arithmetic is used in LRA-BP for computational complexity reduction. Simulation result shows that LRA-BP outperforms MRF-BP with 3–10 dB in terms of required SNR for 1% packet error rate in spatially correlated channel for 256-QAM. We also show that LRA-BP requires much lower complexity compared with MRF-BP.

关键词： massive MIMO MIMO detection belief propagation graph-based detection lattice reduction Markov random field

Ergodic Rate Analysis on Applying Antenna Selection in D2D Communication Underlaying Cellular Networks

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China Communications 2017年第11期14卷 167-184页

作者： Senjie Zhang Yuyang Wang zhiqiang he Shi Jin Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications Beijing 100876 China The University of Texas at Austin USA National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China

By reusing the spectrum of a cellular network, device-to-device(D2D) communications is known to greatly improve the spectral efficiency bypassing the base station(BS) of the cellular network. Antenna selection is the most cost efficient scheme for interference management, which is crucial to D2D systems. This paper investigates the achievable rate performance of the D2D communication underlaying the cellular network where a multiple-antenna base station with antenna selection scheme is deployed. We derive an exact closed-form expression of the ergodic achievable rate. Also, using Jensen's inequality, two pairs of upper and lower bounds of the rate are derived and we validate the tightness of the two sets of bounds. Based on the bounds obtained, we analyze the ergodic achievable rate in noise-limited scenario, interference-limited high SNR scenario and larger-scale antenna systems. Our analysis shows that the presence of D2D users could be counter-productive if the SNR at cellular UE is high. Further analysis shows that the relationship between the ergodic rate and the number of antennas it positive, but keeps decreasing as the antenna number increasing. These show the inefficiency of antenna selection in D2D interference management.

关键词： antenna selection D2D communication ergodic achievable rate Jensen’s inequality massive MIMO

Improving Expectation Propagation with Lattice Reduction for Massive MIMO Detection

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China Communications 2018年第12期15卷 49-54页

作者： Senjie Zhang Shi Jin Chao-Kai Wen zhiqiang he Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications National Mobile Communications Research Laboratory Southeast University Institute of Communications Engineering Sun Yat-sen University

Efficient massive MIMO detection for practical deployment, which is with spatially correlated channel and high-order modulation, is a challenging topic for the fifth generation mobile communication(5 G). In this paper, we propose a lattice reduction aided expectation propagation(LRA-EP) algorithm for massive MIMO detection. LRA-EP applies expectation propagation in lattice reduced MIMO system to approach the distribution of lattice reduced constellation point by iterative refinement on its parameters(mean and covariance). The parameter refinement is based on the lattice reduced, well-conditioned MIMO channel. Numerical result shows that LRA-EP outperforms classic EP based MIMO detection(EPD) with 5～7 dB in terms of required signalto-noise ratio(SNR) for 1% packet error rate in spatially correlated channel for 256-QAM. We also show that LRA-EP has lower computation complexity than EPD.

关键词： MIMO detection lattice reduction expectation propagation massive MIMO

Study of Texture Segmentation and Classification for Grading Small hepatocellular Carcinoma Based on CT Images

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Tsinghua Science and Technology 2021年第2期26卷 199-207页

作者： Bei Hui Yanbo Liu Jiajun Qiu Likun Cao Lin Ji zhiqiang he School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054China West China Biomedical Big Data Center West China HospitalSichuan UniversityChengdu 610041China Department of Radiology of Peking Union Medical College Hospital Beijing 100032China Department of Radiology West China HospitalSichuan UniversityChengdu 610041China

To grade Small hepatocellular Car Cinoma(SHCC)using texture analysis of CT images,we retrospectively analysed 68 cases of Grade II(medium-differentiation)and 37 cases of Grades III and IV(high-differentiation).The grading scheme follows 4 stages:(1)training a Super Resolution Generative Adversarial Network(SRGAN)migration learning model on the Lung Nodule Analysis 2016 Dataset,and employing this model to reconstruct Super Resolution Images of the SHCC Dataset(SR-SHCC)images;(2)designing a texture clustering method based on Gray-Level Co-occurrence Matrix(GLCM)to segment tumour regions,which are Regions Of Interest(ROIs),from the original and SR-SHCC images,respectively;(3)extracting texture features on the ROIs;(4)performing statistical analysis and *** segmentation achieved accuracies of 0.9049 and 0.8590 in the original SHCC images and the SR-SHCC images,*** classification achived an accuracy of 0.838 and an Area Under the ROC Curve(AUC)of *** grading scheme can effectively reduce poor impacts on the texture analysis of SHCC *** may play a guiding role for physicians in early diagnoses of medium-differentiation and high-differentiation in SHCC.

关键词： grading of Small hepatocellular Car Cinoma(SHCC) Gray-Level Co-occurrence Matrix(GLCM) texture clustering super-resolution reconstruction

Study on intercarrier interference in mobile MIMO-OFDM based on the geometrical one-ring model

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High Technology Letters 2012年第1期18卷 20-25页

作者： Li Juhu Zhi Xiyun he zhiqiang Wu Weiling Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing 100876P.R.China

This paper investigates the distribution of intercarrier interference （ICI） in multiple-input multiple-output orthogonal frequency division multiplexing （MIMO-OFDM） systems based on the geometrical one-ring model. Using the spatial and temporal correlation of a geometrical one-ring model, a close-formed expression of intercarrier interference due to the Doppler effect caused by the movement of receiver is derived under the isotropic scattering conditions and non-isotropic scattering conditions. The analytical results are verified by Monte Carlo simulations. We use the generated channels to investigate MIMO-OFDM intercarrier interference under various channel parameters. It can be shown that more than 95% oflCI power comes from five neighboring subcarriers.

关键词： intercarrier interference (ICI) one-ring model spatial and temporal correlation isotropicscattering non-isotropic scattering

Robust THP Design with the Presence of Errors in CSIT Acquisition

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China Communications 2010年第2期7卷 78-86页

作者： Wang Xuzhen Niu Kai he zhiqiang Yu Guangwei Li Hui Inforrnation Theoryand Technology Education and Research Center Beijing University of Posts and Telecommunications Beijing 100876 China The Pilot College Beijing University of Technology Beijing 101101 China

In this paper, a robust THP is proposed for broadcast channel in multi-user multi-input multi-output (MU-MIMO) system, in which the channel uncertainty caused by feedback delay and mobile speed is taken into account. In order to acquire the imperfect channel state information at transmitter (CSIT), a dynamic CSIT model is introduced where the channel temporal and spatial correlations are considered. By utilizing the unchanged channel statistics and accurate outdated feedback channel information jointly, the imperfect CSIT is obtained as the channel estimate and error covariance. Based on the obtained imperfect CSIT, a Minimum Mean-Square Error (MMSE) Tomlinsion-Harashima precoding (THP) is designed and the closed-form solution is derived by the Lagrangian multiplier approach under total power constraint. Simulation results are provided to indicate the preferable performances of the robust THP. Performance analysis with respect to feedback delay and mobile speed is also given.

关键词： MU-MIMO channel estimate imperfect channel state

Effects of Annealing Processes on CuxSi(1-x) Thin Films

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Journal of Wuhan University of Technology(Materials Science) 2016年第1期31卷 31-34页

作者：章嵩 WU Jun he zhiqiang 涂溶 SHI Ji ZHANG Lianmeng State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070China Department of Metallurgy and Ceramics Science Tokyo Institute of Technology Tokyo 152-8552 Japan Institute for Materials Research Tohoku University Sendal 980-8577 Japan

The CuxSi（1-x） thin films have been grown by pulsed laser deposition（PLD） with in situ annealing on Si（001） and Si（111）,*** transformation of phase was detected by X-ray diffraction（XRD）.The results showed that the as-deposited films were composed of Cu on both Si（001） and Si（111）.The annealed thin films consisted of Cu ＋η ＂-Cu3Si on Si（001） while Cu ＋η＇-Cu3Si on Si（111）,respectively,at annealed temperature（Ta）= 300-600℃.With the further increasing of Ta,at Ta= 700℃,there was only one main phase,η＂-Cu3Si on Si（001） while η＇-Cu3Si on Si（111）,*** annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing Ta detected by field emission scanning electron microscope（FESEM）.It was also showed that the grain size would enlarge with increasing annealing time（ta）.

关键词： CuxSi1-x thin films PLD phase surface morphology

Bioresponsive nanogated ensemble based on structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports

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Chinese Chemical Letters 2019年第3期30卷 779-782页

作者： Zhiyong Zhang A.Runa Jie Wu Han Zhang Xia Li zhiqiang he Inner Mongolia Power Research Institute

By taking advantage of recent advances in aptamer biology and nanotechnology, we developed a general approach for the design and fabrication of bioresponsive controlled delivery systems. It utilized the structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports, which enables the control of cargo release from the inside of the mesoporous nanoparticles specifically in the presence of target molecule.

关键词： Mesoporous silica DNA aptamer Controlled release Bioresponsive Nanoparticle assembly