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Experimental study on cyclic deformation properties of saturated Fujian sand at different loading frequencies

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Underground Space 2023年第6期13卷 150-165页

作者： Chong Yue Ke Liang Chengshun xu Xiuli Du Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education Beijing University of TechnologyBeijing 100124China

In this study,a series of undrained cyclic torsional shear tests were conducted to investigate the effect of cyclic loading frequency f on the pre-liquefaction(shearing contractive(SC)period and initial shearing dilative(ISD)period)and post-liquefaction(late shearing dilative(LSD)period)deformation properties of saturated Fujian *** secant shear modulus G and damping ratioλin the entire cyclic loading process,and the unloading tangent shear modulus G_(L1)and flow deformation tangent shear modulus GL2 in the ISD and LSD periods were adopted to quantitatively characterize the evolution of hysteresis loop with an increase in shear strain amplitude *** test results show that the effect of f on G of saturated Fujian sand in the SC period is not ***,all the G-γ_(a),G_(L1)-γ_(a),and GL2-ca curves in the ISD and LSD periods showed a downward trend with an increase in *** study also proposes a modified method for calculatingλto compensate for the analytical error caused by the non-closure of hysteresis *** with the classical curves that mainly applied in geotechnical engineering,theλfirst increases and then decreases with the increase ofγ***,theλevaluated by the modified method is approximately 10%–15%more than theλevaluated by the traditional method when theλreaches its peak value.

关键词： Sand liquefaction Cyclic loading frequency Hysteresis loop shape Shear modulus Damping ratio

Numerical Analysis of Welding Residual Stress and Distortion in Laser+GMAW Hybrid Welding of Aluminum Alloy T-Joint

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 352-360页

作者： Guoxiang xu Chuansong WU xuezhou MA xuyou WANG Key Laboratory of Advanced Welding Technology of Jiangsu Province Jiangsu Univeristy of Science and Technology Institute of Advanced Welding Technology Shandong University Harbin Welding Institute China Academy of Machinery Science & Technology

A 3-D finite element model is developed to predict the temperature field and thermally induced residual stress and distortion in laser＋GMAW hybrid welding of 6061-T6 aluminum alloy T-joint. And the characteristics of residual stress distribution and deformation are numerically investigated. In the simulation, the heat source model takes into account the effect of joint geometric shape and welding torch slant on the heat flux distribution and a sequentially coupled thermo-mechanical method is used. The calculated results show that higher residual stress is distributed in and surround the weld zone. Its peak value is very close to the yield strength of base metal. Besides, a large deformation appears in the middle and rear part of the weldment.

关键词： Hybrid welding Residual stress Welding distortion Aluminum alloy T-joint Numerical simulation

The prediction on in-line vortex-induced vibration of slender marine structures

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Acta Mechanica Sinica 2012年第5期28卷 1303-1308页

作者： Wan-Hai xu Xi-Feng Gao Jie Du State Key Laboratory of Hydraulic Engineering Simulation and Safety School of Civil EngineeringTianjin University

The in-line （IL） vortex-induced vibration （VIV） that occurs frequently in ocean engineering may cause severe fatigue damage in slender marine structures. To the best knowledge of the authors, in existing literatures, there is no efficient analytical model for predicting pure IL VIV. In this paper, a wake oscillator model capable of analyzing the IL VIV of slender marine structures has been developed. Two different kinds of van der Pol equations are used to describe the near wake dynamics related to the fluctuating nature of symmetric vortex shedding in the first excitation region and alternate vortex shedding in the second one. Some comparisons are carried out between the present model results and experimental data. It is found that many phenomena observed in experiments could be reproduced by the present wake oscillator model.

关键词： Vortex-induced vibration Wake oscillatormodel In-line Slender marine structures

Flow-pattern-altered syntheses of core–shell and hole–shell microparticles in an axisymmetric microfluidic device

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Acta Mechanica Sinica 2021年第9期37卷 1378-1386,I0001页

作者： Duo Wang xu Zheng Xiaodong Chen Guoqing Hu State Key Laboratory of Fluid Power and Mechatronic Systems Department of Engineering MechanicsZhejiang UniversityHangzhou310027China State Key Laboratory of Nonlinear Mechanics(LNM) Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China

Droplet-based microfluidics offers unique advantages to create platforms that fabricate functionalized particles with increased accessibility,robustness,and *** we present a three-phase microfluidic device that can control the flow pattern to directly generate either core–shell or hole–shell *** major benefits of this device are the ease of controlling the morphology of the compound droplets by the flow rates and thus the microstructure of the synthesized *** transition between flow patterns enables the generation of either core–shell particles or Janus particles in a single *** further show the versatility of the proposed device in fabrication of functionalized particles:the hole size of the hole–shell microparticle can be fine-tuned while its outer diameter is kept constant,and by adding Fe_(3)O_(4) nanoparticles into the photocurable phase,the obtained magnetoresponsive microparticle can move rotationally or translationally under an external magnetic *** anticipate that the present method could facilitate the fabrication of the functional microparticles for diverse applications.

关键词： Microfluidics Droplet Microparticle Janus particle

Multi-objective optimization of p-xylene oxidation process using an improved self-adaptive differential evolution algorithm

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Chinese Journal of Chemical Engineering 2017年第8期25卷 983-991页

作者： Lili Tao Bin xu Zhihua Hu Weimin Zhong College of Engineering Shanghai Polytechnic University School of Mechanical Engineering Shanghai University of Engineering Science Key Laboratory of Advanced Control and Optimization for Chemical Processes Ministry of Education East China University of Science and Technology

The rise in the use of global polyester fiber contributed to strong demand of the Terephthalic acid （TPA）. The liquid-phase catalytic oxidation of p-xylene （PX） to TPA is regarded as a critical and efficient chemical process in industry [ 1 ]. PX oxidation reaction involves many complex side reactions, among which acetic acid combustion and PX combustion are the most important. As the target product of this oxidation process, the quality and yield of TPA are of great concern. However, the improvement of the qualified product yield can bring about the high energy consumption, which means that the economic objectives of this process cannot be achieved simulta- neously because the two objectives are in conflict with each other. In this paper, an improved self-adaptive multi-objective differential evolution algorithm was proposed to handle the multi-objective optimization prob- lems. The immune concept is introduced to the self-adaptive multi-objective differential evolution algorithm （SADE） to strengthen the local search ability and optimization accuracy. The proposed algorithm is successfully tested on several benchmark test problems, and the performance measures such as convergence and divergence metrics are calculated. Subsequently, the multi-objective optimization of an industrial PX oxidation process is carried out using the proposed immune self-adaptive multi-objective differential evolution algorithm （ISADE）. Optimization results indicate that application oflSADE can greatly improve the yield of TPA with low combustion loss without degenerating TA quality.

关键词： p-Xylene oxidation Operation condition optimization Multi-objective optimization Self-adaptive differential evolution

Highlights in focus issue on prostate cancer

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Chinese Journal of Cancer Research 2013年第6期25卷 784-785页

作者： Eunice X.xu Editorial Office Translational Andrology and Urology

In September 2013, the Translational Andrology and Urology （FAU） launched a focus issue on“Prostate Cancer”, which was guest-edited by Dr. Jer-Tsong Hsieh and Dr. Ganesh Raj from University of Texas Southwestern M... 详细信息

关键词： USA Highlights in focus issue on prostate cancer TAU

Dynamic Positioning Capability Analysis for Marine Vessels Based on A DPCap Polar Plot Program

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China Ocean Engineering 2018年第1期32卷 90-98页

作者： WANG Lei YANG Jian-min xu Sheng-wen State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Shipand Deep-Sea Exploration(CISSE) Shanghai 200240China

Dynamic positioning capability(DPCap) analysis is essential in the selection of thrusters, in their configuration, and during preliminary investigation of the positioning ability of a newly designed vessel dynamic positioning *** analysis can help determine the maximum environmental forces, in which the DP system can counteract in given headings. The accuracy of the DPCap analysis is determined by the precise estimation of the environmental forces as well as the effectiveness of the thrust allocation logic. This paper is dedicated to developing an effective and efficient software program for the DPCap analysis for marine vessels. Estimation of the environmental forces can be obtained by model tests, hydrodynamic computation and empirical formulas. A quadratic programming method is adopted to allocate the total thrust on every thruster of the vessel. A detailed description of the thrust allocation logic of the software program is given. The effectiveness of the new program DPCap Polar Plot(DPCPP)was validated by a DPCap analysis for a supply vessel. The present study indicates that the developed program can be used in the DPCap analysis for marine vessels. Moreover, DPCap analysis considering the thruster failure mode might give guidance to the designers of vessels whose thrusters need to be safer.

关键词： DPCap analysis thrust allocation logic quadratic programming method

Wing walls for enhancing the seismic performance of reinforced concrete frame structures

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 411-423页

作者： Yang Weisong Guo xun xu Weixiao Yuan Xin School of Civil Engineering Qingdao University of Technology Qingdao 266033 China Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone Qingdao 266033 China Institute of Disaster Prevention Sanhe 06520 China Sichuan Provincial Architectural Design and Research Institute Chengdu 610000 China

A building retrofitted with wing walls in the bottom story, which was damaged during the 2008 M8.0 Wenchuan earthquake in China, is introduced and a corresponding 1/4 scale wing wall-frame model was subjected to shake table motions to study the seismic behavior of this retrofitted structural system. The results show that wing walls can effectively protect columns from damage by moving areas that bear reciprocating tension and compression to the sections of the wing walls, thus achieving an extra measure of seismic fortification. A ‘strong column-weak beam＇ mechanism was realized, the flexural rigidity of the vertical member was strengthened, and a more uniform distribution of deformation among all the stories was measured. In addition, the joint between the wing walls and the beams suffered severe damage during the tests, due to an area of local stress concentration. A longer area of intensive stirrup is suggested in the end of the beams.

关键词： story walls flexural shake columns suffered sections drift reinforced frames

Fluid-based Slotting Optimization for Automated Order Picking System with Multiple Dispenser Types

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 529-538页

作者： LIU Peng WU Yaohua ZHOU Chen xu Na School of Control Science andEngineering Shandong University Jinan 250061 China School of Industrial and Systems Engineering Georgia Institute of Technology Atlanta GA 30332 USA Business School Shandong Jianzhu University Jinan 250101 China

Slotting strategy heavily influences the throughput and operational cost of automated order picking system with multiple dispenser types, which is called the complex automated order picking system （CAOPS）. Existing research either focuses on one aspect of the slotting optimization problem or only considers one part of CAOPS, such as the Low-volume Dispensers, to develop corresponding slotting strategies. In order to provide a comprehensive and systemic approach, a fluid-based slotting strategy is proposed in this paper. The configuration of CAOPS is presented with specific reference to its fast-picking and restocking subsystems. Based on extended fluid model, a nonlinear mathematical programming model is developed to determine the optimal volume allotted to each stock keeping unit （SKU） in a certain mode by minimize the restocking cost of that mode. Conclusion from the allocation model is specified for the storage modules of high-volume dispensers and low-volume dispensers. Optimal allocation of storage resources in the fast-picking area of CAOPS is then discussed with the aim of identifying the optimal space of each picking mode. The SKU assignment problem referring to the total restocking cost of CAOPS is analyzed and a greedy heuristic with low time complexity is developed according to the characteristics of CAOPS. Real life application from the tobacco industry is presented in order to exemplify the proposed slotting strategy and assess the effectiveness of the developed methodology. Entry-item-quantity （EIQ） based experiential solutions and proposed-model-based near-optimal solutions are compared. The comparison results show that the proposed strategy generates a savings of over 18% referring to the total restocking cost over one-year period. The strategy proposed in this paper, which can handle the multiple dispenser types, provides a practical quantitative slotting method for CAOPS and can help picking-system-designers make slotting decisions efficiently and

关键词： slotting complex automated order picking system restocking cost dispenser