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Analytical solution of ground-borne vibration due to a spatially periodic harmonic moving load in a tunnel embedded in layered soil

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第7期24卷 637-652页

作者： Lihui XU meng ma Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China

In this study,we propose a novel coupled periodic tunnel–soil analytical model for predicting ground-borne vibrations caused by vibration sources in *** problem of a multilayered soil overlying a semi-infinite half-space was solved using the transfer matrix *** account for the interactions between the soil layer and tunnel structure,the transformation characteristics between cylindrical waves and plane waves were considered and used to convert the corresponding wave potentials into forms in terms of the Cartesian or cylindrical coordinate *** induced ground-borne vibration was obtained analytically by applying a spatially periodic harmonic moving load to the tunnel *** accuracy and efficiency of the proposed model were verified by comparing the results under a moving constant and harmonic load with those from previous ***,the response characteristics under a spatially periodic harmonic moving load were identified,and the effects of a wide range of factors on the responses were systematically *** numerical results showed that moving and Doppler effects can be caused by a spatially periodic harmonic moving *** critical frequency and frequency bandwidth of the response are affected by the load type,frequency,velocity,and wavenumber in one periodicity *** the tunnel depth is an efficient way to reduce ground-borne *** effect of vibration amplification on the free surface should be considered to avoid excessive vibration levels that disturb residents.

关键词： Coupled tunnel-soil model Spatially periodic load Transfer matrix method Wave transformation Parametric analysis

A beamforming design for weighted sidelobe power leakage minimization

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Science China(Information Sciences) 2016年第6期59卷 144-152页

作者： Cheng FENG meng ma Bingli JIAO School of Electronics Engineering and Computing Sciences Peking University

In this paper, a beamforming scheme for minimizing the weighted sidelobe power leakage while maintaining the norm of the weight vector at unity is proposed. The proposed criterion is very flexible because weighting factors are added to the sidelobes in the object function, and the weighting factors can be adjusted according to any design purpose, e.g., to minimize the interference within a direction of arrival(Do A) range. To acquire the minimum sidelobe power leakage, we first express the sidelobe power through the sidelobe coefficient matrix. Afterwards, the minimization problem can be treated as the 2-norm minimization of the sidelobe coefficient matrix. The optimal weighting vector design is then derived by singular value decomposition(SVD).Simulation results show that the proposed beamformer can decrease the sidelobe power leakage and efficiently suppress interference with barely any increase in the sidelobes; moreover, this beamforming scheme provides good robustness in consideration of the DOA mismatch.

关键词： beamforming weighted sidelobe power leakage 2-norm singular value decomposition(SVD) direction of arrival(Do A)

Carbonaceous and nitrogenous disinfection by-product formation in the surface and ground water treatment plants using Yellow River as water source

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Journal of Environmental Sciences 2012年第7期24卷 1204-1209页

作者： Yukun Hou Wenhai Chu meng ma College of Environmental Science and Engineering Tongji University Shanghai 200092 China Zhengzhou Water Supply Corporation Zhengzhou 450013 China

This work investigated the formation of carbonaceous and nitrogenous disinfection by-products （C-DBPs, N-DBPs） upon chlorination of water samples collected from a surface water and a ground water treatment plant （SWTP and GWTP） where the conventional treatment processes, i.e., coagulation, sedimentation, and filtration were employed. Twenty DBPs, including four trihalomethanes, nine haloacetic acids, seven N-DBPs （dichloroacetamide, trichloroacetamide, dichloroacetonitrile, trichloroacetonitrile, bromochloroace- tonitrile, dibromoacetonitrile and trichloronitromethane）, and eight volatile chlorinated compounds （dichloromethane （DCM）, 1,2-dichloroethane, tetrachloroethylene, chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4- trichlorobenzene） were detected in the two WTPs. The concentrations of these contaminants were all below their corresponding maximum contamination levels （MCLs） regulated by the Standards for Drinking Water Quality of China （GB5749-2006） except for DCM （17.1 ~tg/L detected vs. 20 μg/L MCL）. The SWTP had much higher concentrations of DBPs detected in the treated water as well as the DBP formation potentials tested in the filtered water than the GWTP, probably because more precursors （e.g., dissolved organic carbon, dissolved organic nitrogen） were present in the water source of the SWTE

关键词： carbonaceous disinfection by-products nitrogenous disinfection by-products formation potential free chlorine watertreatment plant

Dynamic response analysis of train-induced vibration impact on the Probhutaratna pagoda in Beijing

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 223-243页

作者： Li Minghang ma meng Cao Zhonglei Xia Qian Liu Weining School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Xi'an University of TechnologyXi’an 710048China

Train-induced vibration exhibits a potential dynamic impact on historic buildings and especially on those with high historical and cultural *** the long-term reciprocating load of train vibrations,structural fatigue damage can occur,and thus,a significant problem involves effectively evaluating and mitigating vibration impact on historic buildings while developing a rail transit *** the present study,train-induced vibration impact and dynamic behavior of Probhutaratna pagoda in the suburb of Beijing,which has a history of approximately 1000 years,was *** examine the dynamic behavior of the Probhutaratna pagoda and determine the weakest position in its architectural damage under train loads,its dynamic characteristics were *** free vibration modes were identified based on the dynamic measurement ***,a finite element(FE)model of the Probhutaratna pagoda was constructed and the models and train-induced structural responses were compared with measured ***,the structural dynamic responses to moving train loads were analyzed in *** results indicate the following conclusions.(1)The dominant frequency of the ambient vibration is below 4 Hz,and the dominant frequency of the train-induced vibration is between 8 and 16 Hz.(2)The first,second,and third order natural frequencies are 1,3.25,and 6 Hz,respectively,in the west-east direction,and are 1,3.25,and 6.25 Hz,respectively,in the north-south direction.(3)The two weakest locations(A and B)of the Probhutaratna pagoda are observed at the spire bottom and west gate of the first *** location A,the maximum principal stress reached 243.6 N/m^2 and the corresponding maximum tensile strain reached 3.74×10^-7.

关键词： historic building vibration measurement numerical simulation train-induced vibration modal identification

A Networking Solution on Uplink Channel of CoFrequency and Co-Time System

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China Communications 2016年第S2期13卷 183-188页

作者： Bingli Jiao Sanjun Liu Yiming Lei meng ma School of Electronics Engineering & Computer Science Peking University

Co-frequency and co-time full duplex(CCFD) is an attractive technology for the future wireless communication because of its high spectral ***,applications of CCFD to mobile network can suffer from strong base station to base station(B2B)*** this paper,the authors proposed a design that uses centralized base station(BS)transmit antenna and distributed BS receive antennas,each of which consists of an antennary to perform beamforming that can nullify the B2 B *** addition,we proposed a combination algorithm that uses the zero forcing method to cascade the recursive least square(RLS) method for reducing the necessary number of the bits taken to the digital *** enables the faster convergence and,thus,allows the transmission of more information bits,compared to the conventional method,for mobile *** simulation results confirm this approach for practical application.

关键词： co-frequency and co-time full duplex cellular networks beamform RLS

Incorporating Lasso Regression to Physics-Informed Neural Network for Inverse PDE Problem

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 385-399页

作者： meng ma Liu Fu Xu Guo Zhi Zhai National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong UniversityXi’an710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an710049China Department of Electrical and Computer Engineering University of Massachusetts LowellLowellMA 01854USA

Partial Differential Equation(PDE)is among the most fundamental tools employed to model dynamic *** PDE modeling methods are typically derived from established knowledge and known phenomena,which are time-consuming and ***,discovering governing PDEs from collected actual data via Physics Informed Neural Networks(PINNs)provides a more efficient way to analyze fresh dynamic systems and establish *** study proposes Sequentially Threshold Least Squares-Lasso(STLasso),a module constructed by incorporating Lasso regression into the Sequentially Threshold Least Squares(STLS)algorithm,which can complete sparse regression of PDE coefficients with the constraints of l0 *** further introduces PINN-STLasso,a physics informed neural network combined with Lasso sparse regression,able to find underlying PDEs from data with reduced data requirements and better *** addition,this research conducts experiments on canonical inverse PDE problems and compares the results to several recent *** results demonstrated that the proposed PINN-STLasso outperforms other methods,achieving lower error rates even with less data.

关键词： Physics-informed neural network inverse partial differential equation Lasso regression scientific machine learning

Co-Channel Interference Suppression Techniques for Full Duplex Cellular System

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China Communications 2015年第S1期12卷 18-27页

作者： XIN Yongchao ma meng ZHAO Zijun JIAO Bingli School of Electronics Engineering and Computer Science Peking University

Co-frequency and co-time full duplex(CCFD) is a promising technique for improving spectral efficiency in next generation wireless communication systems. However, for the applications of CCFD in a cellular network, severe co-channel interference is an essential problem. Specifically, there are two significant interferences, i.e., inter-terminal interference(ITI) and inter-cell interference(ICI), which lead to an obvious performance degradation. In this paper, two techniques are proposed for suppressing the ITI and ICI in a CCFD cellular system, respectively. The first technique is obtained by modeling the three-node CCFD system as the Z-channel. After deriving the sum-capacity of the Z-channel, a sum-capacity-achieving scheme based on successive interference cancellation(SIC) is proposed. The second technique is designed by combining the fractional frequency reuse scheme with CCFD. The performance gains of the proposed two techniques in terms of signalto-interference plus noise ratio(SINR) and sumcapacity are analyzed. Simulation results show that the proposed scheme can achieve significant interference suppression performance and higher system capacity, especially for cell edge users.

关键词： co-frequency and co-time full duplex(CCFD) fractional frequency reuse(FFR) successive interference cancellation(SIC) Z-channel

A High Spectral Efficiency System Enabled by Free Window with Full Duplex

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China Communications 2015年第9期12卷 93-99页

作者： Feng Cheng Cui Hongyu ma meng Jiao Bingli School of Electronics Engineering and Computer Science Peking University

This paper studies the capacity issues of a wireless communication system that implements single channel full duplex(SCFD) communication at the base station(BS), thereby the mobile stations share the channel via time division duplex(TDD). The system makes use of the same setup as has been used in previous studies of SCFD, but unlike these previous systems, the new system uses water-filling to maximize the spectral efficiency of the uplink channel. The concept of a free window is introduced to the duplex model for measuring, intuitively, the effective bandwidth of the bi-directional communication. The capacity gain is calculated and numerical results show the advantage of the proposed system over that of conventional TDD.

关键词： spectral efficiency free window time division duplex full duplex water-filling

Layered multicast congestion control by particle swarm optimization in heterogeneous environment

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The Journal of China Universities of Posts and Telecommunications 2011年第3期18卷 85-91页

作者： ma Hai-yuan meng Xiang-ru ma Zhi-qiang LI Jin-liang The Telecommunication Engineering Institute Air Force Engineering University Xi'an 710077 China

To enhance multicast throughput in heterogeneous environment, a new layered multicast congestion control scheme is proposed. With the goal of maximizing global satisfaction of the whole group, allocating sending rate in each layer is formulated to an optimization problem. Since the problem is noncovexity, the sender uses particle swarm optimization to search a set of optimal layers rates. The new scheme also eliminates ＇lowest-first＇ phenomenon by proposing a feedbacks suppression algorithm named equal-probability sampling （EPS）. Upon EPS all the receivers send feedbacks at equal probability without bias. Simulation results prove that the new scheme can enhance global satisfaction and multicast throughput efficiently, compared with the traditional layered multicast congestion control scheme based on representatives.

关键词： layered multicast congestion control particle swarm optimization feedbacks suppression