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GLOBAL EXISTENCE,EXPONENTIAL DECAY AND BLOW-UP IN FINITE TIME FOR A CLASS OF FINITELY DEGENERATE SEMILINEAR PARABOLIC EQUATIONS

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Acta Mathematica Scientia 2019年第5期39卷 1290-1308页

作者： hua chen Huiyang XU School of Mathematics and Statistics Wuhan University Wuhan 430072 China Computational Science Hubei Key Laboratory Wuhan University Wuhan 430072 China

In this paper,we study the initial-boundary value problem for the semilinear parabolic equations ut-△Xu=|u|p-1u,where X=（X1,X2,…,Xm） is a system of real smooth vector fields which satisfy the H?rmander’s condition,and △X=∑j=1m Xj2 is a finitely degenerate elliptic *** potential well method,we first prove the invariance of some sets and vacuum isolating of ***,by the Galerkin method and the concavity method we show the global existence and blow-up in finite time of solutions with low initial energy or critical initial energy,and also we discuss the asymptotic behavior of the global solutions.

关键词： finitely degenerate parabolic equation global existence blow-up decay estimate

Deep learning-based multi-source precipitation merging for the Tibetan Plateau

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Science China Earth Sciences 2023年第4期66卷 852-870页

作者： Tianyi NAN Jie chen Zhiwei DING Wei LI hua chen State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Hubei Provincial Key Lab of Water System Science for Sponge City Construction Wuhan UniversityWuhan 430072China

Due to its complex and diverse terrain, precipitation gauges in the Tibetan Plateau(TP) are sparse, making it difficult to obtain reliable precipitation data for environmental studies. Data merging is a method that can integrate precipitation data from multiple sources to generate high-precision precipitation data. However, the more commonly used methods, such as regression and machine learning, do not usually consider the local correlation of precipitation, so that the spatial pattern of precipitation cannot be reproduced, while deep learning methods do incorporate spatial correlation. To explore the ability of using deep learning methods in merging precipitation data for the TP, this study compared three methods: a deep learning method—a convolutional neural network(CNN) algorithm, a machine learning method—an artificial neural network(ANN) algorithm, and a statistical method based on Extended Triple Collocation(ETC) in merging precipitation from multiple sources(gauged, grid,satellite and dynamic downscaling) over the TP, as well as their performance for hydrological simulations. Dynamic downscaling data driven by global reanalysis data centered on the TP were introduced in the merging process to better reflect the spatial variability of precipitation. The results show that:(1) in terms of the meteorological metrics, the merged data perform better than the gauge interpolation data. By using data merging, the error between the raw multi-source and gauged precipitation can be reduced, and the precipitation detection capability can be greatly improved;(2) The merged precipitation data also perform well in the hydrological evaluation. The Xin’anjiang(XAJ) model parameter calibration experiments at the source of the Yangtze River(SYR) and the source of the Yellow River(SHR) were repeated 300 times to remove uncertainty in the model parameter results. The median Kling-Gupta Efficiency Coefficients(KGE) of simulated runoff from the merged data of the ANN, CNN and ETC me

关键词： Tibetan Plateau Precipitation data merging Deep learning Dynamic downscaling

Characterization of Phenol Biodegradation by Comamonas testosteroni ZD4-1 and Pseudomonas aeruginosa ZD4-3

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Biomedical and Environmental Sciences 2003年第2期16卷 163-172页

作者： YING-XU chen HE LIU hua-LIN chen Department of Environmental Engineering Zhejiang UniversityHangzhou 310029China

To investigate the characteristic and biochemical mechanism about the phenol biodegradation by bacterial strains ZD 4-1 and ZD 4-3. Methods Bacterial strains ZD 4-1 and ZD 4-3 were isolated by using phenol as the sole source of carbon and energy, and identified by 16S rDNA sequence analysis. The concentrations of phenol and total organic carbon (TOC) were monitored to explore the degradation mechanism. The biodegradation intermediates were scanned at 375 nm by using a uv-vis spectrophotometer. The enzyme assays were performed to detect the activities of dioxygenases. Results Bacterial strains ZD 4-1 and ZD 4-3 were identified as Comamonas testosteroni and Pseudomonas aeruginosa by 16S rDNA sequence analysis, respectively. The growth of the two strains was observed on a variety of aromatic hydrocarbons. The strains ZD 4-1 and ZD 4-3 metabolized phenol via ortho-pathways and meta-pathways, respectively. In addition, the results of enzyme assays showed that the biodegradation efficiency of phenol by meta-pathways was higher than that by ortho-pathways. Finally, the results of induction experiment indicated that the catechol dioxygenases, both catechol 1,2-dioxygenase (C12O) and catechol 2,3-dioxygenase (C23O), were all inducible. Conclusion The strains ZD 4-1 and ZD 4-3 metabolize phenol through ortho-pathways and meta-pathway, respectively. Furthermore, the biodegradation efficiency of phenol by meta-pathways is higher than that by ortho-pathways.

关键词： Aromatic compounds Phenol Biodegradation Ortho-pathways Meta-pathways C12O C23O

Progress in pancreas transplantation and combined pancreas-kidney transplantation

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Hepatobiliary & Pancreatic Diseases International 2007年第1期6卷 17-23页

作者： Zhong-hua Klaus chen Institute of Organ Transplantation Affiliated Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China

BACKGROUND: Pancreas transplantation (PT) has proved effective but it is associated with a high risk of surgical complications and technical failure. Duct management and venous drainage are identified as major issues. Improvements in immunosuppression and prophylaxis greatly have contributed to surgical progress. DATA SOURCES: A literature search of the PubMed database (1996-2005) was conducted and research articles on PT reviewed. RESULTS: More than 23 000 PTs have been performed throughout the world. The majority (83%) were performed in combination with kidney transplantation [simultaneous pancreas-kidney transplantation (SPK)]. Pancreas graft survival rates at one year were 85% for 2001-2003 SPK cases, 79% for pancreas after kidney transplantation (PAK) cases, and 76% for pancreas transplantation alone (PTA) cases. For the 1999-2003 cases, enteric drainage was done in 79% of the SPK cases and bladder drainage in 21%. Patient survival rates, pancreas and kidney graft survival rates, and pancreas graft immunological failure rates did not differ significantly in enteric versus bladder drainage cases. All the available data fail to demonstrate a definitive advantage of portal drainage over systemic drainage. From 1993 to 2002, the use of rabbit antithymocyte globulin increased from 0 to 37%; the use of daclizumab increased from 0 to 16%; and the use of basiliximab increased from 0 to 25%. In 1993, 98% of SPK recipients received cyclosporine; but this was decreased to 9% in 2002. Tacrolimus (FK506) usage has increased from 0 (1993) to 87% (2002) of SPK recipients. Sirolimus (SIR) usage has increased from 0 (1993) to 18% (2002) of SPK recipients. CONCLUSIONS: PT remains an effective therapy for treatment of type I diabetes mellitus. Enteric drainage is currently predominant in SPK, but bladder drainage is still largely used. Portal drainage is as safe as systemic drainage, but there is still no convincing evidence about whether it is immunologically or metabolically co

关键词： diabetes mellitus pancreas transplantation enteric drainage bladder drainage portal drainage immunosuppression

Impact of Information Security Policies on Email-Virus Propagation

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Tsinghua Science and Technology 2005年第z1期10卷 803-810页

作者： YUAN hua chen Guoqing School of Economics and Management Tsinghua University Beijing 100084 China School of Economics and Management Tsinghua University Beijing 100084 China

Aimed at tracing out the email-virus propagation rules in communication network, this paper extends the traditional epidemiological model (i. e., SEIR) by taking into account the behavior of email users, such as email checking frequency and anti-virus information security policies, and discusses the factors that affect the email-virus propagation in an organization. With the extended SEIR model, namely E-SEIR, three aspects of information security policies (i. e., immunization, information security training,and user recovery support) are investigated in terms of their impacts on the email virus propagation. The results show that the E-SEIR model is suitable to reflect the propagation pattern of email virus, and may also be used in anti-virus policies simulation and evaluation.

关键词： email virus propagation simulation E-SEIR model information security policy epidemiological

Event-triggered model-free adaptive control for a class of surface vessels with time-delay and external disturbance via state observer

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Journal of Systems Engineering and Electronics 2023年第3期34卷 783-797页

作者： chen hua SHEN Chao huaNG Jiahui CAO Yuhan College of Science Hohai UniversityNanjing 210098China College of Mechanical and Electrical Engineering Hohai UniversityChangzhou 213022China Hohai-Lille College Hohai UniversityNanjing 211100China

This paper provides an improved model-free adaptive control(IMFAC)strategy for solving the surface vessel trajectory tracking issue with time delay and restricted ***,the original nonlinear time-delay system is transformed into a structure consisting of an unknown residual term and a parameter term with control inputs using a local compact form dynamic linearization(local-CFDL).To take advantage of the resulting structure,use a discrete-time extended state observer(DESO)to estimate the unknown residual ***,according to the study,the inclusion of a time delay has no effect on the linearization structure,and an improved control approach is provided,in which DESO is used to adjust for ***,a DESO-based event-triggered model-free adaptive control(ET-DESO-MFAC)is established by designing event-triggered conditions to assure Lyapunov *** when the system’s indicator fulfills the provided event-triggered condition will the control input signal be updated;otherwise,the control input will stay the same as it is at the last trigger moment.A coordinate compensation approach is developed to reduce the steady-state inaccuracy of trajectory ***,simulation experiments are used to assess the effectiveness of the proposed technique for trajectory tracking.

关键词： surface vessels event-triggered condition(ETC) discrete-time extended state observer(DESO) model-free adaptive control(MFAC) coordinate compensation

Wavelet network solution for the inverse kinematics problem in robotic manipulator

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第4期7卷 525-529页

作者： chen hua chen Wei-shan XIE Tao School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China

Wavelet network, a class of neural network consisting of wavelets, is proposed to solve the inverse kinematics problem in robotic manipulator. A wavelet network suitable for dealing with multi-input and multi-output system is constructed. The network is optimized by reducing the number of wavelets handling large dimension problem according to the sample data. The algorithms for sparseness analysis of input data and fitting wavelets to the output data with orthogonal method are introduced. Then Levenberg-Marquardt algorithm is used to train the network. Simulation results showed that this method is capable of solving the inverse kinematics problem for PUMA560.

关键词： Inverse kinematics problem Robotic manipulator Wavelet network

A novel heterogeneous Co(Ⅱ)-Fenton-like catalyst for efficient photodegradation by visible light over extended pH

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Science China Chemistry 2020年第12期63卷 1825-1836页

作者： Wu-hua chen Jin-hua Xiong Xue Teng Jin-Xiao Mi Zhi-Biao Hu Haifeng Wang Zuofeng chen Fujian Provincial Colleges and University Engineering Research Center of Solid Waste Resource Utilization(Longyan University) College of Chemistry and Material ScienceLongyan UniversityLongyan 364012China Shanghai Key Laboratory of Chemical Assessment and Sustainability School of Chemical Science and EngineeringTongji UniversityShanghai 200092China Key Laboratory for Advanced Materials Centre for Computational Chemistry and Research Institute of Industrial CatalysisEast China University of Science and TechnologyShanghai 200237China Department of Materials Science and Engineering College of MaterialsXiamen UniversityXiamen 361005China

A novel Co^Ⅱ-Fenton-like heterogeneous catalyst,(H3O)2[Co^Ⅱ(phen)(H2O)2]2[Mo^Ⅵ5O15(PO4)2]·4H2O (phen=1,10-phenanthroline,C12N2H8)(1),is synthesized and utilized for photocatalytic degradation of organic dyes and antibiotic in a wide range of *** experimental results show that 1 acting as the Fenton-like catalyst with H2O2 exhibits remarkable activity at pH 3–9 under vis-light irradiation and is merited with excellent recyclability and reusability.A variety of analytical methods,including in-situ electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations,are applied to study the mechanism on generation of·OH and O2^·-radicals for photocatalytic *** suggests that,unlike the classical Fenton process involving the redox transformation of the central cations,the generation of·OH and O2^·-radicals is associated with the substitution of the coordinating water molecules at Co(Ⅱ) by H2O2 and/or OOH^-,followed by the light-driven O–O bond cleavage and *** outcomes of this study are striking which overcome the obstacles in the classical Fe^Ⅱ-Fenton process,including the slow redox transformation between Fe(Ⅱ) and Fe(Ⅲ) and the production of massive iron precipitates especially at elevated *** opens up new avenues for the development of the high-performance Fenton(-like) catalysts for photocatalytic degradation over extended pH and provides new insight into the related process.

关键词： Co^Ⅱ-Fenton-like reagent polyoxometalate photocatalytic degradation density functional theory(DFT)calculations in-situ EPR spectroscopic analysis

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CWP皮革防水加脂剂的研制及应用性能

皮革与化工 2025年第1期42卷 7-10,16页

作者：陈华祝林峰闵峰巴克曼实验室化工(上海)有限公司上海201707

本文以丙烯酸、丙烯酸高碳醇酯及有机硅反应单体为原料,在溶剂介质中及引发剂作用下进行共聚反应生成聚合物加脂剂,当该聚合物反应单体的配比为:甲基丙烯酸十七酯(HMA)∶甲基丙烯酸十三酯(TA)∶丙烯酸(AA)=1.0∶0.2∶1.2,有机硅反应单... 详细信息

本文以丙烯酸、丙烯酸高碳醇酯及有机硅反应单体为原料,在溶剂介质中及引发剂作用下进行共聚反应生成聚合物加脂剂,当该聚合物反应单体的配比为:甲基丙烯酸十七酯(HMA)∶甲基丙烯酸十三酯(TA)∶丙烯酸(AA)=1.0∶0.2∶1.2,有机硅反应单体用量4%(单体质量比),引发剂V601用量为5%时,其具有很好的防水效果。在牛蓝湿皮鞋面革上,对该防水加脂剂与市场上防水加脂剂进行对比应用测试,达到了较高的动态防水效果,满足客户需求。

关键词：牛皮鞋面革防水加脂剂丙烯酸酯聚合物有机硅

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