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A novel cell search scheme for OFDM cellular systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 10-17页

作者： DING Ming luo han-wen WU Yun Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China

A novel cell search scheme for OFDM cellular systems is proposed. It is based on one OFDM symbol with several identical slots as preamble, the time domain repetition structure of which can be utilized to accomplish OFDM timing/frequency synchronization. The cell ID is comprised of two parts: a sub-carrier mask index g and a sequence index x. Each sub-carrier mask activates or deactivates some of the sub-carriers, after which a differentially coded sequence is loaded on pairs of the adjacent active sub-carriers. The user equipment (UE) recognizes the mask with index g via power detection of the received frequency domain signal. Then it estimates the index x from differential demodulation followed by detection of the frequency domain se-quence. In order to improve the performance, a method of jointly estimating g and x is devised. Simulation results showed that the proposed scheme is able to support a very large number of cell IDs while maintaining a good performance even in bad multi-cell environment.

关键词： Orthogonal frequency division multiplexing (OFDM) Cell search Cell ID Multi-cell Mask

A novel MMSE based codebook construction for MIMO precoded spatial multiplexing with limited feedback

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1894-1900页

作者： SHE Feng luo han-wen WANG Xin Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China

This paper deals with the design and performance analysis of the transmission precoder optimization for multiple-input multiple-output (MIMO) systems with limited feedback of channel state information (CSI). We assume that the receiver can get perfect channel knowledge by channel estimation while the transmitter only has partial channel knowledge from limited feedback. We present a minimum mean square error (MMSE) criterion based codebook construction algorithm for MIMO pre- coded spatial multiplexing systems under a specific average power constraint. The optimal transmitter structure is employed in this paper. Simulation results show that the MMSE criteria based codebook construction algorithm with hybrid design of power allocation and precoding can achieve better performance than that of equal power allocation based codebook of previous research.

关键词： Multiple-input multiple-output (MIMO) Precoding Channel state information (CSI) Feedback

Effect of Wave Headings on the Dynamic Response of the Continuous Mating Operation of Floatover Installation

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China Ocean Engineering 2021年第1期35卷 72-83页

作者： BAI Xiao-dong luo han-bing XIE Peng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Department of Naval Architecture and Ocean Engineering Tianjin UniversityTianjin 300072China

The topside floatover installation is always a great challenge and is sensitive to environmental *** this study,experimental analysis on the mating operation of the floatover installation in different wave headings is *** continuous mating operation using the rapid transfer technique was experimentally simulated with the assistance of the jacking system and the ballast *** the continuous transfer modeling,the topsides loads were transferred onto the jacket by several consecutive steps,including the first rapid jack-down for the 30%loads,continuous 30%−70%load transfer and the second repaid jack-down for the remaining 30%*** of the barge and the topsides as well as loads on the Deck Support Unite(DSU)and the Leg Mating Unite(LMU)in different wave headings were *** results illustrated the complex motion behavior and load characteristics of the continuous transfer *** indicate that the rapid jack-down operations will lead to impact loads and larger lateral DSU *** bow quartering seas are much more dangerous as it gives rise to the larger motions and *** with the traditional steady-state modeling indicate that the continuous transfer modeling has greater advantages over the steady-state modeling on predicting the loads.

关键词： floatover installation rapid transfer technique model test different wave directions

Power duality for multi-antenna OFDM system in broadcast channel with user scheduling

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 215-224页

作者： Feng SHE han-wen luo Lei CHEN Hua XIA Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 China Datang Microelectronics Technology Co. Ltd. Beijing 100083 China

This paper deals with design and analysis of user scheduling and power allocation for multi-antenna OFDM systems with DPC,ZF-DPC,ZF-BF and TDMA transmit *** consider the general multi-user downlink scheduling problem and power minimization with multi-user rate *** to the channel state,it is shown that there is a power optimal policy which selects a subset of users in each scheduling *** present user selection algorithms for DPC,ZF-DPC,ZF-BF and TDMA for multi-antenna OFDM system in broadcast channels,and we also present the practical water-filling solution in this *** the selected users with the consideration of fairness,we derive the power optimization algorithm with multi-user rate *** also analyze the power duality of uplink-downlink for the transmit strategies of DPC,ZF-DPC and *** results show that the present user-scheduling algorithm and power minimization algorithm can achieve good power performance,and that the scheduling algorithm can guarantee fairness.

关键词： Multiple-input multiple-output (MIMO) Orthogonal frequency division multiplexing (OFDM) Broadcast channel Multi-user diversity Dirty paper coding (DPC) Downlink scheduling

Dynamic Multi-Physics Behaviors and Performance Loss of Cylindrical Batteries Upon Low-Velocity Impact Loading

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Energy & Environmental Materials 2024年第6期7卷 184-192页

作者： Qingdan Huang Yang Bai han luo Yikai Jia Chao Zhang School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710072China Key Laboratory on the Impact Protection and Safety Assessment of Civil Aviation Vehicle Taicang 215400China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China EVE Energy Co. Ltd.Huizhou 516006C

In challenging operational environments,Lithium-ion batteries(LIBs)inevitably experience mechanical stresses,including impacts and extrusion,which can lead to battery damage,failure,and even the occurrence of fire and explosion ***,it is imperative to investigate the safety performance of LIBs under mechanical *** study is grounded in a more realistic coupling scenario consisting of electrochemical cycling and low-velocity *** systematically and experimentally uncovered the mechanical,electrochemical,and thermal responses,damage behavior,and corresponding mechanisms under various *** study demonstrates that higher impact energy results in increased structural stiffness,maximum temperature,and maximum voltage ***,heightened impact energy significantly influences the electrical resistance parameters within the internal *** also examined the effects of State of Charge(SOC)and *** methodology and experimental findings will offer insights for enhancing the safety design,conducting risk assessments,and enabling the cascading utilization of energy storage systems based on LIBs.

关键词： cycling performance damaged battery lithium-ion battery low-velocity impact mechanical safety

Prediction of Long-Term Extreme Response of Fish Cage Using Environmental Contour Method

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China Ocean Engineering 2021年第3期35卷 332-343页

作者： BAI Xiao-dong GUO Wei-wei YANG Can luo han-bing State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Department of Naval Architecture and Ocean Engineering Tianjin UniversityTianjin 300072China China Water Resources Bei Fang Investigation Design and Research CO.LTDTianjin 300222China College of Shipbuilding Engineering Harbin Engineering UniversityHarbin 150001China

The fish cage design requires accurate predictions of long-term extreme loads and *** with the time-consuming full long-term analysis method integrating all the probability distribution of the short-term extremes,the environmental contour method gains much attention in predicting the long-term extreme values due to the less computational *** paper investigates the long-term extreme response of a fish cage using the environmental contour *** fish cage is numerically simulated based on the lumped-mass method and the curved beam *** on the one-dimensional(1D)and two-dimensional(2D)environmental contour,the extreme responses,including the surge and heave motions,mooring force,and vertical bending of the floater,are predicted for different return periods and compared with the full long-term analysis *** indicate that the 1D method greatly underestimates the extreme *** 2D environmental contour method with a higher percentile level,namely90%,provides reasonable estimations and seems to be suitable for the long-term value *** studies show that the mooring arrangement and the bending stiffness have great effects on the bending moment and the mooring force and the mooring line pre-tension has minor effects on the fish cage response.

关键词： fish cage long-term extreme value environmental contour method sensitivity analysis

RLS channel estimation with adaptive forgetting factor in space-time coded MIMO-OFDM systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第4期7卷 507-515页

作者： LIANG Yong-ming luo han-wen HUANG Jian-guo Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200030 China College of Marine Engineering Northwestern Polytechnical University. Xi＇an 710072 China

Considering that channel estimation plays a crucial role in coherent detection, this paper addresses a method of Recursive-least-squares (RLS) channel estimation with adaptive forgetting factor in wireless space-time coded multiple-input and multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. Because there are three different forgetting factor scenarios including adaptive, two-step and conventional ones applied to RLS channel estimation, this paper describes the principle of RLS channel estimation and analyzes the impact of different forgetting factor scenarios on the performances of RLS channel estimation. Simulation results proved that the RLS algorithm with adaptive forgetting factor (RLS-A) outperformed that with two-step forgetting factor (RLS-T) or with conventional forgetting factor (RLS-C) in both estimation accuracy and robustness over the multiple-input multiple-output (MIMO) channel, i.e., a wide-sense stationary uncorrelated scattering (WSSUS) and frequency-selective slowly fading channel. Hence, we can employ the RLS-A method by adjusting forgetting factor adaptively to track and estimate channel state parameters successfully in space-time coded MIMO-OFDM systems.

关键词： MIMO-OFDM Channel estimation RLS algorithm Adaptive forgetting factor

Biodegradable Poly(propylene carbonate)/Layered Double Hydroxide Composite Films with Enhanced Gas Barrier and Mechanical Properties

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Chinese Journal of Polymer Science 2016年第1期34卷 13-22页

作者： Gao-feng Li Wen-han luo Min Xiao 王拴紧孟跃中 State Key Laboratory of Optoelectronic Materials and Technologies/The Key Laboratory of Low-carbon Chemistry &Energy Conservation of Guangdong Province Sun Yat-sen University

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.

关键词： Poly(propylene carbonate) Layered double hydroxide Gas barrier properties Biodegradable composite Packaging

Attention-based LSTM predictive model for the attitude and position of shield machine in tunneling

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Underground Space 2023年第6期13卷 335-350页

作者： Qing Kang Elton J.Chen Zhong-Chao Li han-Bin luo Yong Liu State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan 430072China School of Civil&Hydraulic Engineering Huazhong University of Science&TechnologyWuhan 430074China Tunnel Engineering Company Wuhan Municipal Construction Group Co.LtdWuhan 430023China

Shield machine may deviate from its design axis during excavation due to the uncertainty of geological environment and the complexity of *** study therefore introduced a framework to predict the attitude and position of shield machine by combining long short-term memory(LSTM)model with attention *** data obtained from the Wuhan Rail Transit Line 6 project were utilized to verify the feasibility of the proposed *** adding the attention mechanism into the LSTM model,the proposed model can focus more on parameters with higher *** analysis based on Pearson correlation coefficient was conducted to improve the prediction efficiency and reduce the irrelevant input *** with LSTM model,LSTM-attention model has higher *** mean value of coefficient of determination(R^(2))increases from 0.625 to 0.736,and the mean value of root mean square error(RMSE)decreases from 3.31 to *** proposed LSTM-attention model can provide an effective prediction for attitude and position of shield machine in practical tunneling engineering.

关键词： LSTM Shield machine Attitude and position prediction Attention mechanism Tunnel excavation