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AN ADAPTIVE NONMONOTONIC TRUST REGION METHOD WITH CURVILINEAR SEARCHES

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Journal of Computational Mathematics 2006年第6期24卷 761-770页

作者： qun-yan Zhou Wen-yu Sun School of Mathematics and Computer Science Nanjing Normal University Nanjing 210097 China Department of Mathematics Jiangsu Teacher University of Technology Changzhou 213001 China

In this paper, an algorithm for unconstrained optimization that employs both trust region techniques and curvilinear searches is proposed. At every iteration, we solve the trust region subproblem whose radius is generated adaptively only once. Nonmonotonic backtracking curvilinear searches are performed when the solution of the subproblem is unacceptable. The global convergence and fast local convergence rate of the proposed algorithms are established under some reasonable conditions. The results of numerical ＇experiments are reported to show the effectiveness of the proposed algorithms.

关键词： Unconstrained optimization Preconditioned gradient path Trust region method,Curvilinear search.

Analytical and Numerical Studies for Chaotic Dynamics of a Duffing Oscillator with a Parametric Force

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Communications in Theoretical Physics 2007年第3X期48卷 477-480页

作者： WANG yan-qun WU Qin Department of Mathematics Hengyang Normal University Hengyang 421008 China School of Basic Medical Science Guangdong Medical College Dongguan 523808 China

The chaotic dynamics of a Duffing oscillator with a parametric force is investigated. By using the direct perturbation technique, we analytically obtain the general solution of the lst-order equation. Through the boundedness condition of the general solution we get the famous Melnikov function predicting the onset of chaos. When the parametric and external forces are strong, numerical simulations show that increasing the amplitude of the parametric or external force can lead the system into chaos via period doubling.

关键词： general solution Melnikov function period doubling chaos

Numerical simulation of pedestrian flow past a circular obstruction

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Acta Mechanica Sinica 2011年第2期27卷 215-221页

作者： yan-qun Jiang Ru-Xun Liu Ya-Li Duan Department of Mathematics Southwest University of Science and Technology 621010 Mianyang China Department of Mathematics University of Science and Technology of China 230026 Hefei China

In this paper, a revisiting Hughes’ dynamic continuum model is used to investigate and predict the essential macroscopic characteristics of pedestrian flow, such as flow, density and average speed, in a two dimensional continuous walking facility scattered with a circular obstruction. It is assumed that pedestrians prefer to walk a path with the lowest instantaneous travel cost from origin to destination, under the consideration of the current traffic conditions and the tendency to avoid a high-density region and an obstruction. An algorithm for the pedestrian flow model is based on a cellcentered finite volume method for a scalar conservation law equation, a fast sweeping method for an Eikonal-type equation and a second-order TVD Runge-Kutta method for the time integration on unstructured meshes. Numerical results demonstrate the effectiveness of the algorithm. It is verified that density distribution of pedestrian flow is influenced by the position of the obstruction and the path-choice behavior of pedestrians.

关键词： Pedestrian flow · Continuum model ·Finite volume method · Unstructured meshes · Obstruction

Study on Dynamic Characteristics of Hydraulic Pumping Unit on Offshore Platform

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China Ocean Engineering 2017年第6期31卷 693-699页

作者： CHANG Zong-yu YU yan-qun QI Yao-guang College of Engineering Ocean University of ChinaQingdao 266100China College of Mechanical and Electronic Engineering China University of PetroleumQingdao 266580China

A new technology of offshore oil rod pumping production is developed for offshore heavy oil recovery. A new type of miniature hydraulic pumping unit with long-stroke, low pumping speed and compact structure is designed based on the spatial characteristics of offshore platforms. By combining the strengths of sinusoidal velocity curve and trapezoidal velocity curve, a kinematical model of the acceleration, the velocity and displacement of the pumping unit＇s hanging point is established. The results show that the pumping unit has good kinematic characteristics of smooth motion and small dynamic load. The multi-degree-of-freedom dynamic model of the single-well pumping unit is established. The first and second order natural frequencies of the sucker rod string subsystem and the pumping unit subsystem are studied. The results show that the first and the second order natural frequencies among the pumping rod string, pumping unit-platform subsystem and the dynamic excitation have differences over 5 times from each other, indicating that resonance phenomenon will not appear during the operation and the dynamic requirements for field use are met in the system.

关键词： offshore platform platform pumping unit kinematic model dynamic model multiple degrees of freedom

Radiological diagnosis of duodenocaval fistula:A case report and literature review

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World Journal of Gastroenterology 2010年第18期16卷 2314-2316页

作者： Guo, Yong Zhang, yan-qun Lin, Wei Gen Navy Hosp Dept Radiol Beijing 100048 Peoples R China

Duodenocaval fistula(DCF) is an uncommon but lethal clinical *** high mortality has been attributed to the difficulty of diagnosis before attempts at definitive *** this case report,we describe a patient with a series of computed tomography(CT) examinations over a 2-mo period in hospital.A low-density air bubble appeared in the inferior vena cava(IVC) on the second day in hospital and became clear on day 19,and gradually *** resonance imaging(MRI) also clearly demonstrated a high-signal enteric contrast medium or thrombus and signal-void air bubbles in the ***,cavography did not show the filling *** suggest that noninvasive CT and MRI should be chosen as a first-line investigation,and IVC,including the surrounding structures,should be carefully reviewed on images if DCF is clinically considered.

关键词： Duodenocaval fi stula Computed tomography Magnetic resonance imaging

Application of artificial neural network for switching loss modeling in power IGBTs

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第6期11卷 435-443页

作者： yan DENG Xiang-ning HE Jing ZHAO yan XIONG yan-qun SHEN Jian JIANG School of Electrical Engineering Zhejiang University Hangzhou 310027 China

The modeling of switching loss in semiconductor power devices is important in practice for the prediction and evaluation of thermal safety and system *** simulation-based behavioral models and data processing-based empirical models are difficult and have limited *** the artificial neural network(ANN) algorithm has often been used for modeling, it has never been used for modeling insulated gate bipolar transistor(IGBT) transient *** this paper, we attempt to use the ANN method for this purpose, using a customized switching loss test *** compare its performance with two conventional curve-fitting models and verify the results by *** model is generally superior in calculation speed, accuracy, and data requirement, and is also able to be extended to loss modeling for all kinds of semiconductor power devices.

关键词： Insulated gate bipolar transistor(IGBT) Switching loss Modeling Artificial neural network(ANN)

Arsenite oxidation by three types of manganese oxides

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Journal of Environmental Sciences 2006年第2期18卷 292-298页

作者： FENG Xiong-han ZU yan-qun TAN Wen-feng LIU Fan College of Resources and Environment Huazhong Agricultural University Wuhan 430070 China College of Resources and Environment Yunnan Agricultural University Kunming 650201 China

Oxidation of As（Ⅲ） by three types of manganese oxides and the effects ofpH, ion strength and tartaric acid on the oxidation were investigated by means of chemical analysis, equilibrium redox, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Three synthesized Mn oxide minerals, bimessite, cryptomelane, and hausmannite, which widely occur in soil and sediments, could actively oxidize As（Ⅲ） to As（Ⅴ）. However, their ability in As（Ⅲ）-oxidation varied greatly depending on their structure, composition and surface properties. Tunnel structured cryptomelane exhibited the highest ability of As （Ⅲ） oxidation, followed by the layer structured birnessite and the lower oxide hausmannite. The maximum amount of As （Ⅴ） produced by the oxidation was in the order （mmol/kg） of cryptomelane （824.2）〉 bimessite （480.4）〉 hausmannite （117.9）, As pH increased from the very low value（pH 2.5）, the amount of As（Ⅲ） oxidized by the tested Mn oxides was firstly decreased, then negatively peaked in pH 3.0 6.5, and eventually increased remarkably. Oxidation of As（Ⅲ） by the Mn oxides had a buffering effects on the pH variation in the solution. It is proposed that the oxidative reaction processes between As （Ⅲ） and biruessite（or cryptomelane） are as follows：（1） at lower pH condition：（MnO2）x＋ H3AsO3 ＋ 0.5H^＋=0.5H2AsO4^- ＋ 0.5HAsO4^2- ＋Mn〉^2＋（MnO2）x-1 ＋ H2O; （2） at higher pH condition：（MnO2）x ＋ H3AsO3 = 0.5H2AsO4^- ＋ 0.5HAsO4^2- ＋ 1.5H^＋＋（MnO2）x-1. MnO. With increase of ion strength, the As（Ⅲ） oxidized by bimessite and cryptomelane decreased and was negatively correlated with ion strength. However, ion strength had little influence on As （Ⅲ） oxidation by the hausmarmite. The presence of tartaric acid promoted oxidation of As（Ⅲ） by birnessite. As for cryptomelane and hansmannite, the same effect was observed when the concentration of tartaric acid was below 4 mmol/L, otherwise the oxidized As（Ⅲ） decreased. These findings are of great significance in improving our understanding

关键词： oxidation of As(Ⅲ) As(Ⅴ) Mn oxides pH ion strength tartaric acid

National Natural Science Foundation of China leads the comprehensive development of basic research in the field of male reproductive health in China

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Asian Journal of Andrology 2020年第6期22卷 547-548页

作者： Shu-Jie Liao yan-Ying Xu Rui-Juan Sun qun-yan Lyu Department of Health Science National Natural Science Foundation of ChinaBeijing 100085China Department of Obstetrics and Gynecology Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

"Reproductive health"was officially defined as humans and their individual activities related to reproduction throughout their lives,which should be in good health in physical,psychological,and social aspects.1 The basic research on male reproductive health in China can be traced back to the 1960s.2 Since the National Natural Science Foundation of China(NSFC)began systematic support for basic research on male reproductive health in 1988,the field has been systematically developed in *** this regard,we analyze the role of the NSFC on the development of basic research in the field of male reproductive health in China.

关键词： NSFC China. field

Graphdiyne as a novel nonactive anode for wastewater treatment:A theoretical study

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Chinese Chemical Letters 2021年第9期32卷 2819-2822页

作者： Guoshuai Liu yanan Zhou qun yan Yasmina Doekhi-Bennani School of Environmental and Civil Engineering Jiangnan UniversityWuxi 214122China School of Chemical Engineering Sichuan UniversityChengdu 610065China Department of Water Management Section Sanitary EngineeringDelft University of TechnologyPO Box 50482600 GADelftthe Netherlands

Electrochemical oxidation of water to produce highly reactive hydroxyl radicals(·OH)is the dominant factor that accounts for the organic compounds removal efficiency in water *** an emerging carbon-based material,the investigation of electrocatalytic of water to produce·OH on Graphdiyne(GDY)anode is firstly evaluated by using first-principles *** theoretical calculation results demonstrated that the GDY anode owns a large oxygen evolution reaction(OER)overpotential(η^(OER)=1.95 V)and a weak sorptive ability towards oxygen evolution intermediates(HO^(*),not·OH).The high Gibbs energy change of HO^(*)(3.18 e V)on GDY anode makes the selective production of·OH(△G=2.4 eV)thermodynamically *** investigation comprises the understanding of the relationship between OER to electrochemical advanced oxidation process(EAOP),and give a proof-of-concept of finding the novel and robust environmental EAOP anode at quantum chemistry level.

关键词： First-principle Graphdiyne Hydroxyl radical Nonactive