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Stochastic bifurcations in the SD (smooth and discontinuous) oscillator under bounded noise excitation

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Science China(Physics,Mechanics & Astronomy) 2013年第5期56卷 1010-1016页

作者： YUE XiaoLe XU Wei wang liang Department of Applied Mathematics Northwestern Polytechnical University

Stochastic bifurcations of the SD （smooth and discontinuous） oscillator with additive and/or multiplicative bounded noises are studied by the generalized cell mapping method using digraph analysis algorithm. From the global viewpoint, stochastic bifur- cation can be described as a sudden change in shape and size of a random attractor as the system parameter valies. The evolu- tionary process of stochastic bifurcation in the SD oscillator is shown in detail. Meanwhile, we show the phenomenon that un- der stochastic excitation the shape and size of random attractor and random saddle change along with the direction of unstable manifold. A plane stochastic bifurcation diagram is included.

关键词： stochastic bifurcation SD oscillator generalized cell mapping method bounded noise

Exponential Synchronization of Impulsive Complex Networks with Output Coupling

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International Journal of Automation and computing 2013年第4期10卷 350-359页

作者： Yue-Hui Zhao Jin-liang wang College of Post and Telecommunication of Wuhan Institute of Technology Science and Technology on Aircraft Control Laboratory School of Automation Science and Electrical Engineering Beihang University

This paper proposes a new impulsive complex delayed dynamical network model with output coupling, which is totally different from some existing network models. Then, by employing impulsive delay differential inequalities, some sufficient conditions are obtained to guarantee the global exponential state synchronization and output synchronization of the impulsive complex delayed dynamical network. Finally, two numerical examples are given to demonstrate the effectiveness of the obtained results.

关键词： Impulsive complex networks output coupling state synchronization output synchronization impulsive delay differential inequalities.

Coupling hydrodynamic models with GIS for storm surge simulation： application to the Yangtze Estuary and the Hangzhou Bay, China

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Frontiers of Earth Science 2012年第3期6卷 261-275页

作者： liang wang Xiaodong ZHAO Yongming SHEN State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China China-Japan Research Center for Geo-environmental Science Pioneer Park of AcademicianDalian UniversityDalian 116622China

Storm surge is one of the most serious oceanic disasters. Accurate and timely numerical prediction is one of the primary measures for disaster control. Traditional storm surge models lack of accuracy and time effects. To overcome the disadvantages, in this paper, an analytical cyclone model was first added into the Finite-Volume Coastal Ocean Model （FVCOM） consisting of high resolution, flooding and drying capabilities for 3D storm surge modeling. Then, we integrated MarineTools Pro into a geographic information system （GIS） to supplement the storm surge model. This provided end users with a friendly modeling platform and easy access to geographically referenced data that was required for the model input and output. A temporal GIS tracking analysis module was developed to create a visual path from storm surge numerical results. It was able to track the movement of a storm in space and time. MarineTools Pro＇ capabilities could assist the comprehensive understanding of complex storm events in data visualization, spatial query, and analysis of simulative results in an objective and accurate manner. The tools developed in this study further supported the idea that the coupled system could enhance productivity by providing an efficient operating environ- ment for accurate inversion or storm surge prediction. Finally, this coupled system was used to reconstruct the storm surge generated by Typhoon Agnes （No. 8114） and simulated typhoon induced-wind field and water elevations of Yangtze Estuary and Hangzhou Bay. The simulated results show good correlation with actual surveyed data. The simple operating interface of the coupled system is very convenient for users, who want to learn the usage of the storm surge model, especially for first-time users, which can save their modeling time greatly.

关键词： storm surge Finite-Volume Coastal Ocean Model (FVCOM) temporal geographic information system(GIS) Yangtze Estuary and Hangzhou Bay Typhoon Agnes

HWD-YOLO:A New Vision-Based Helmet Wearing Detection Method

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Computers, Materials & Continua 2024年第9期80卷 4543-4560页

作者： Licheng Sun Heping Li liang wang College of Information Science and Technology Beijing University of TechnologyBeijing100124China Chinese Institute of Coal Science Beijing100013China State Key Laboratory for Intelligent Coal Mining and Strata Control Beijing100013China Engineering Research Center of Digital Community of Ministry of Education Beijing100124China

It is crucial to ensure workers wear safety helmets when working at a workplace with a high risk of safety accidents,such as construction sites and mine *** existing methods can achieve helmet detection in images,their accuracy and speed still need improvements since complex,cluttered,and large-scale scenes of real workplaces cause server occlusion,illumination change,scale variation,and perspective ***,a new safety helmet-wearing detection method based on deep learning is ***,a new multi-scale contextual aggregation module is proposed to aggregate multi-scale feature information globally and highlight the details of concerned objects in the backbone part of the deep neural ***,a new detection block combining the dilate convolution and attention mechanism is proposed and introduced into the prediction *** block can effectively extract deep featureswhile retaining information on fine-grained details,such as edges and small ***,some newly emerged modules are incorporated into the proposed network to improve safety helmetwearing detection performance *** experiments on open dataset validate the proposed *** reaches better performance on helmet-wearing detection and even outperforms the state-of-the-art *** be more specific,the mAP increases by 3.4%,and the speed increases from17 to 33 fps in comparison with the baseline,You Only Look Once(YOLO)version 5X,and themean average precision increases by 1.0%and the speed increases by 7 fps in comparison with the YOLO version *** generalization ability and portability experiment results show that the proposed improvements could serve as a springboard for deep neural network design to improve object detection performance in complex scenarios.

关键词： Object detection deep learning safety helmet wearing detection feature extraction attention mechanism

Asymptotic Weighted-Periodicity of the Impulsive Parabolic Equation with Time Delay

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Acta Mathematicae Applicatae Sinica 2007年第1期23卷 1-8页

作者： Jin-liang wang Hui-feng Li Ocean Current and Wave Lab Institute of Oceanology Chinese Academy of Science Qingdao 266071 China College of Science Qingdao Technological University Qingdao 266033 China

The main aim of this paper is to investigate the effects of the impulse and time delay on a type of parabolic equations. In view of the characteristics of the equation, a particular iteration scheme is adopted. The results show that Under certain conditions on the coefficients of the equation and the impulse, the solution oscillates in a particular manner--called ＂asymptotic weighted-periodicity＂.

关键词： Weighted-periodicity oscillation impulsive time delay parabolic

Selective Oxidation of Methane into Methanol Under Mild Conditions

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Chemical Research in Chinese Universities 2022年第3期38卷 671-676页

作者： LIU Yifeng wang liang XIAO Feng-Shou Key Lab of Applied Chemistry of Zhejiang Province Department of ChemistryZhejiang UniversityHangzhou310028P.R.China Key Lab of Biomass Chemical Engineering of Ministry of Education College of Chemical and Biological EngineeringZhejiang UniversityHangzhou310027P.R.China Zhejiang Tianlan Environmental Protection Technology Limited Company Hangzhou310012P.R.China

Selective oxidation of methane to methanol under mild conditions has been considered as a dream reaction but suffers from poor efficiency due to the strong C-H bond of methane and easy overoxidation of the methanol *** overcoming these problems,a series of strategies has been developed for improving methanol productivity with oxidants of hydrogen peroxide and even a mixture of oxygen and hydrogen at mild *** achievements in these strategies using effective catalysts,such as supported metal nanoparticles,colloidal metal nanoparticles,and metal@zeolites are briefly ***,the current challenges,future perspectives for preparing active,selective,and stable catalysts,have been *** zeolite fixed metal nanoparticle structure has been found to boost the reaction by benefiting the formation and enrichment of peroxide intermediates,which might guide the development of more efficient catalysts.

关键词： Methane oxidation Metal@zeolite Hydrogen peroxide Methanol

First-principles Study of NiAl Alloyed with Rare Earth Element Ce

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Journal of Materials Science & Technology 2011年第8期27卷 719-724页

作者： You wang Junqi He Mufu Yan Chonggui Li liang wang YeZhou Department of Materials Science School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

The structural, elastic, and electronic properties of NiAI alloyed with rare earth element （REE） Ce have been investigated by using density functional theory （DFT）. It is found that Ce has a strong AI site preference and causes lattice distortion of NiAI. The calculation of elastic constants shows that Ce increased both the hardness and the ductility of NiAI, which could be explained by the formation of new ionic bonds between AI （and Ni） and Ce and the enhancement of covalent bonds in NisAl7Ce. Our results are in good agreement with the available experimental data and other theoretical results.

关键词： Point defects Electronic states First-principles

Experimental research and numerical simulation of the multi-field performance of cemented paste backfill:Review and future perspectives

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International Journal of Minerals,Metallurgy and Materials 2023年第2期30卷 193-208页

作者： Yong wang Zhenqi wang Aixiang Wu liang wang Qing Na Chen Cao Gangfeng Yang School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining&Technology(Beijing)Beijing 100083China ZHONGGUANCUN Green Mine Industry Alliance Beijing 100083China

Cemented paste backfill(CPB)technology is a green mining method used to control underground goaves and tailings *** curing process of CPB in the stope is the product of a thermo-hydro-mechanical-chemical multi-field performance *** present,research on the multi-field performance of CPB mainly includes indoor similar simulation experiments,in-situ multi-field performance monitoring experiments,multi-field performance coupling model construction of CPB,and numerical simulation of the multi-field performance of *** it is hard to study the in-situ multi-field performance of CPB in the real stope,most current research on in-situ multi-field performance adopts the numerical simulation *** simulating the conditions of CPB in the real stope(e.g.,maintenance environment,stope geometry,drainage conditions,and barricade and backfilling rates),the multi-field performance of CPB is further *** paper summarizes the mathematical models employed in the numerical simulation and lists the engineering application cases of numerical simulation in the in-situ multi-field performance of ***,it proposes that the multi-field performance of CPB needs to strengthen the theoretical study of multi-field performance,form the strength design criterion based on the multi-field performance of CPB,perform a full-range numerical simulation of the multi-field performance of CPB,develop a pre-warning technology for the CPB safety of CPB,develop automatic and wireless sensors for the multi-field performance monitoring of CPB,and realize the application and popularization of CPB monitoring technology.

关键词： cemented paste backfill multi-field performance in situ mathematic model numerical simulation

Effect of wheel speed on phase formation and magnetic properties of (Nd_(0.4)La_(0.6))-Fe-B melt-spun ribbons

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Journal of Rare Earths 2018年第11期36卷 1179-1183页

作者： liang wang Jiang wang Maohua Rong Guanghui Rao Huaiying Zhou School of Material Science and Engineering & Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology Guilin 541004China

The effect of wheel speed on phase formation and magnetic properties of （Ndo.4La0.6）lsFeTzsBzs and （Ndo.4La0.6）13.4Fe79.9B6.7 ribbons prepared by melt-spinning method was investigated experimentally. Based on X-ray diffraction results, all melt-spun ribbons consist of the main phase with the tetragonal 2：14：1 type structure and the minor α-Fe phase. Magnetic measurements show the maximum magnetic energy product （（BH）max） and the remanence （Mr） increases firstly and then decreases with the increase of wheel speed, while the coercivity （Hci） increases, resulting from the variation of the average volume fraction of the ^-Fe phase and the average grain size in the melt-spun ribbons. Using Henkel plots, the interaction between the 2：14：1 phase and the ^-Fe phase in the melt-spun ribbons was analyzed and the intergranular exchange coupling is manifested. Optimal magnetic properties of Hci - 7.27 kOe, Mr - 90.94 emu/g and （BH）max -- 12.10 MGOe are achieved in the （Ndo.4La0.6）lsFeTzsBT.s ribbon with the wheel speed of 26 m/s. It indicates that magnetic properties of Nd-Fe-B melt-spun ribbons with highly abundant rare earth element La can be improved by optimizing alloy composition and preparation process.

关键词： Nd-La-Fe-B ribbons Phase formation Melt-spinning Magnetic properties Rare earths