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Temporal and spatial distribution of dissolved copper,lead,zinc and cadmium in the Changjiang Estuary and its adjacent waters

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Acta Oceanologica Sinica 2008年第4期27卷 73-82页

作者： wang changyou wang Xiulin wang Baodong ZHANG Chuansong SHI Xiaoyong ZHU Chenjian College of Chemistry ＆ Chemical Engineering Ocean University of China Qingdao 266100 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters. Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper, lead, zinc and cadmium in the study waters are 1.01 - 6.86, 0. 10 - 0.39,3.17 - 9.12 and 0.011 - 0. 049 μg/dm^3 , respectively. Similar to zinc, the behavior of dissolved copper was essentially conservative, but high scatter has been observed for high salinity samples, which can be attributed to the decomposition or mineralization of organic matter by bacteria. Dissolved lead may have active behavior with an addition at high salinity. Overall concentrations of dissolved cadmium increase with salinity. The mean values of these dissolved metals calculated for the surface waters were higher than those for the middle and bottom ones. External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values. The maximum seasonal average values of dissolved copper and zinc were found in summer, reflecting higher amounts of riverine input in this season. In contrast, the maximum seasonal average values of dissolved lead and copper were found in winter and the lowest ones in summer, respectively, which might be asso- ciated with a combination of low concentration with heterogeneous scavenging. Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers, except for cadmium. Compared with observations for the Changjiang Estuary in the last two decades, it is clear that the Changjiang estuarine waters has been contaminated with copper, lead, zinc and cadmium during China＇ s industrialization, but concentrations of them have decreased in the last few years.

关键词： heavy metals distribution biological activity East China Sea Changjiang Estuary

On a delay ratio-dependent predator-prey system with feedback controls and shelter for the prey

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International Journal of Biomathematics 2018年第7期11卷 287-316页

作者： changyou wang Linrui Lit Yuqian Zhou Rui Li College of Applied Mathematics Chengdu University of Information Technology Chengdu Sichuan 610225P.R.China Basic Courses Department Institute of Disaster Prevention SanheHebei 065201P.R.China College of Automation Chongqing University of Posts and Telecommunzcations Chongqing 400065 P.R.China

In this paper,a class of three-species multi-delay Lotka-Volterra ratio-dependent predator-prey model with feedback controls and shelter for the prey is considered.A set of easily verifiable sufficient conditions which guarantees the permanence of the system and the global attractivity of positive solution for the predator-prey system are established by developing some new analysis methods and using the theory of differentim inequalities as well as constructing a suitable Lyapunov ***,some conditions for the existence,uniqueness and stability of positive periodic solution for the corresponding periodic system are obtained by using the fixed point theory and some new analysis *** addition,some numerical solutions of the equations describing the system are given to show that the obtained criteria are new,general,and easily ***,we still solve numerically the corresponding stochastic predator-prey models with multiplicative noise sources,and obtain some new interesting dynamical behaviors of the *** the same time,the influence of the delays and shelters on the dynamics behavior of the system is also considered by solving numerically the predator-prey models.

关键词： Predator-prey model feedback control delay permanence attractive periodic solution

On the Uniqueness of Heat Flow of Harmonic Maps and Hydrodynamic Flow of Nematic Liquid Crystals

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Chinese Annals of Mathematics,Series B 2010年第6期31卷 921-938页

作者： Fanghua LIN changyou wang Courant Institute of Mathematical Sciences New York University New York NY 10012 USA Department of Mathematics University of Kentucky Lexington KY 40506 USA.

For any n-dimensional compact Riemannian manifold (M,g) without boundary and another compact Riemannian manifold (N,h), the authors establish the uniqueness of the heat flow of harmonic maps from M to N in the class C([0,T),W1,n). For the hydrodynamic flow (u,d) of nematic liquid crystals in dimensions n = 2 or 3, it is shown that the uniqueness holds for the class of weak solutions provided either (i) for n = 2, u ∈ Lt∞ L2x∩L2tHx1, ▽P∈ Lt4/3 Lx4/3 , and ▽d∈ L∞t Lx2∩Lt2Hx2; or (ii) for n = 3, u ∈ Lt∞ Lx2∩L2tHx1∩ C([0,T),Ln), P ∈ Ltn/2 Lxn/2 , and ▽d∈ L2tLx2 ∩ C([0,T),Ln). This answers affirmatively the uniqueness question posed by Lin-Lin-wang. The proofs are very elementary.

关键词： Hydrodynamic flow Harmonic maps Nematic liquid crystals Uniqueness

Role of Resuspended Sediments as Sources of Dissolved Inorganic Phosphorus Along Different Dimensions in the Subei Shoal, South Yellow Sea, China

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Journal of Ocean University of China 2023年第1期22卷 161-170页

作者： wang changyou ZHENG Ping SU Rongguo LUO Zhuhua ZHANG Yuanzhi MAO Longjiang School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationOcean University of ChinaQingdao 266100China Key Laboratory of Marine Biogenetic Resources Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

Several studies have documented that during‘green tide’events,comprising green macroalgae blooms in aquatic ecosystems,dissolved inorganic phosphorus(DIP)levels remain relatively steady despite the absorption of a large amount of *** this study,surface sediment samples and a sediment core were extracted using a modified sequential extraction scheme,and water and surface sediment samples were analyzed in April 2017 to better understand phosphorus(P)cycling and replenishment in Subei *** used a simple model on equilibrium of adsorption-desorption to present the buffering capacity of *** total P(TP)in the surface sediments ranged from 12.2 to 28.4μmol g^(-1)(average 15.5μmol g^(-1))and was dominated by inorganic ***,exchangeable P,reactive and reductive Fe/Al bound P,and authigenic apatite P significantly decreased northward and eastward from Subei shoal,contrary to the detrital P and organic P *** and particulate inorganic P in the water samples ranged from 0.01 to 0.54μmol L^(-1)(average 0.19μmol L^(-1))and 0.9 to 19.6μmol g^(-1)(average 4.9μmol g^(-1)),*** applied model showed that suspended particulate matter is an important regulator of DIP ***,modification of SPM can alter the DIP buffering *** calculated buffering capacity in the surface layer of the sea water was>60 within Subei shoal and always>10 along the path of floating Ulva prolifera,providing a reasonable explanation for the steady concentration of DIP and its replenishment during the blooming of this green macroalgae.

关键词： phosphorus speciation sediment buffering capacity South Yellow Sea

Predicting Ecological Distribution of the Toxic Dinoflagellate Alexandrium minutum in China Sea Using Ecological Niche Modeling

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Journal of Ocean University of China 2023年第4期22卷 1119-1128页

作者： wang changyou ZHENG Ping GU Haifeng LUO Zhaohe LUO Zhuhua MAO Longjiang ZHANG Yuanzhi School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China Key Laboratory of Marine Biogenetic Resources Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

Alexandrium minutum from the China Sea produces a range of toxins and causes damage to the local ecosystems and *** is essential to understand environmental factors affecting potential *** distributions of *** in the China Sea were predicted based on maximum entropy modeling,and dominant environmental variables were studied through analyses of variable contributions and response *** results showed that highly suitable areas were mainly located in the southwest of the Yellow Sea,the Laizhou Bay,and north of Haizhou *** coast of the South China Sea was predicted as a low-suitability area,and the coast of the East China Sea as an unsuitable *** temperature of the coldest month(T_min)had the largest drop in permutation importance but a low percent *** probability of presence of *** increased with increasing concentration of nitrate(NO3−)and annual mean temperature(T_ann)over a wide range of *** response curves decreased with increasing concentration of phosphate(PO43−)and ratio of NO_(3)^(−)to PO_(4)^(3−)(N_P_ratio)when PO_(4)^(3)−is above 0.049μmolL^(-1) and N_P_ratio above 4,indicating that low values of PO_(4)^(3−) concentration and N_P_ratio favour the occurrence of *** a predictor,the variance of annual temperature(T_Var)had the highest percent contribution and ***_(4)^(3−) was predicted to have much more information than the other variables,and exhibited the second largest drop in permutation importance and percent *** T_Var and PO_(4)^(3−) are the most important dominant predictor variables.

关键词： Alexandrium minutum MaxEnt,habitat suitability environmental variable potential distributions

ON A MULTI-DELAY LOTKA-VOLTERRA PREDATOR-PREY MODEL WITH FEEDBACK CONTROLS AND PREY DIFFUSION

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Acta Mathematica Scientia 2019年第2期39卷 429-448页

作者： changyou wang Nan LI Yuqian ZHOU Xingcheng PU Rui LI College of Applied Mathematics Chengdu University of Information Technology Department of Applied Mathematics Southwestern University of Finance and Economics College of Automation Chongqing University of Posts and Telecommunications

This article is focusing on a class of multi-delay predator-prey model with feedback controls and prey diffusion. By developing some new analysis methods and using the theory of differential inequalities as well as constructing a suitable Lyapunov function, we establish a set of easily verifiable sufficient conditions which guarantee the permanence of the system and the globally attractivity of positive solution for the predator-prey ***, some conditions for the existence, uniqueness and stability of positive periodic solution for the corresponding periodic system are obtained by using the fixed point theory and some new analysis techniques. In additional, some numerical solutions of the equations describing the system are given to verify the obtained criteria are new, general, and easily verifiable. Finally, we still solve numerically the corresponding stochastic predator-prey models with multiplicative noise sources, and obtain some new interesting dynamical behaviors of the system.

关键词： predator-prey model: delay diffusion: permanence attractivity periodic solution

Persistence of a Lotka-volterra Ratio-dependent Predator-prey Model with Delays and Feedback Controls

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Persistence of a Lotka-volterra Ratio-dependent Predator-pre...

作者： Lili Jia changyou wang Dianchi College of Yunnan University College of Applied Mathematics Chengdu University of Information Technology

The aim of this article is to study the dynamical behavior of a Lotka-volterra 3-species ratio-dependent predator-prey system with delays and feedback *** using the comparison theorem,the differential inequalities and developing new analysis method,some sufficient conditions are obtained to ensure the permanence of the solutions for the delayed predator-prey system,and some known results are generalized.

关键词： Delayed feedback control lotka-volterra ratio-dependent permanence

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航空静止变流器的输入纹波电流特性研究

中国电机工程学报 2012年第27期32卷 154-161,196页

作者：陈仲汪昌友陈淼江苏省新能源发电与电能变换重点实验室(南京航空航天大学) 江苏省南京市210016

航空静止变流器(aviation static inverter,ASI)作为飞机电源系统的典型负载,其脉动的输入电流严重影响着直流电网的电能质量。针对航空静止变流器的输入电流特性进行研究。基于双重傅里叶开关函数法给出逆变环节输入电流中直流分量、... 详细信息

航空静止变流器(aviation static inverter,ASI)作为飞机电源系统的典型负载,其脉动的输入电流严重影响着直流电网的电能质量。针对航空静止变流器的输入电流特性进行研究。基于双重傅里叶开关函数法给出逆变环节输入电流中直流分量、二次谐波分量、载波次谐波和载波的边频谐波等表达式,为定量计算各电流分量提供了精确依据。推导二次谐波电流向高压直流电网侧传播的等效电路模型,从而揭示航空静止变流器输入端低频纹波电流的产生、传导及其影响因素。最后,通过仿真和实验验证理论分析的正确性。

关键词：航空静止变流器二次谐波电流传播特性低频纹波电流

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一种模块化航空有源滤波器的研究

航空学报 2013年第4期34卷 919-927页

作者：陈仲陈淼汪昌友南京航空航天大学自动化学院江苏南京210016

航空有源滤波器(AAPF)是解决飞机供电系统中电能质量问题的一种先进方案,而模块化设计对航空有源滤波器灵活性、可维护性和可靠性的提升作用巨大。首先提出并研究了一种新型模块化航空有源滤波器,分析了主电路数学模型及其混合载波PWM(C... 详细信息

航空有源滤波器(AAPF)是解决飞机供电系统中电能质量问题的一种先进方案,而模块化设计对航空有源滤波器灵活性、可维护性和可靠性的提升作用巨大。首先提出并研究了一种新型模块化航空有源滤波器,分析了主电路数学模型及其混合载波PWM(CH-PWM)调制方式;其次基于损耗对比分析进行了主电路拓扑优化,推导了模块均压控制律并给出了系统控制策略;最后进行了仿真和实验验证。结果表明,模块化航空有源滤波器能够有效补偿航空电网中由典型非线性负载产生的谐波和无功电流分量,三相电网电流的总谐波畸变率(THD)均在5%以下,补偿效果显著。

关键词：有源滤波器飞机供电系统模块化数学模型混合载波PWM调制损耗