检索结果-南通市图书馆

Consensus of Single Integrator Multi-Agent Systems with Unbounded Transmission Delays

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2019年第3期32卷 778-788页

作者： xu xiang LIU Lu FENG Gang Department of Biomedical Engineering City University of Hong Kong

This paper investigates the consensus problem of single integrator multi-agent systems with unbounded time-varying transmission delays and fixed di rec ted topology. A dist ributed cont roller is proposed taking into consideration the unbounded transmission delays. It is shown that the consensus problem can be solved via the proposed controller under the spanning tree assumption and the nocycle assumption. The authors characterize the no-cycle assumption and prove the consensus of the concerned multi-agent systern with an induction procedure. Two simulation examples are provided, one to illustrate the effectiveness of our result and the other to show the necessity of the no-cycle assumption.

关键词： Consensus multi-agent systems unbounded transmission delays

Two Novel Methods to Enhance Network Synchronizability

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第4期49卷 1064-1068页

作者： dai Kun WANG Xiao-Fan LI xiang Department of Automation Shanghai Jiao Tong University Shanghai 200240 China

In this paper, we propose two methods to enhance the synchronizability of a class of complex networks which do not hold the positive correlation between betweenness centrality （BC） and degree of a node, and observe other topology characteristics of the network affected by the methods. Numerical simulations show that both methods can effectively enhance the synchronizability of this kind of networks. Furthermore, we show that the maximal BC of all edges is an important factor to affect the network synchronizability, although it is not the unique factor.

关键词： synchronizability betweenness centrality clustering coefficient

ON SPECTRAL METHODS FOR VOLTERRA INTEGRAL EQUATIONS AND THE CONVERGENCE ANALYSIS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2008年第6期26卷 825-837页

作者： Tao Tang xiang xu Jin Cheng Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong China School of Mathematics Fudan University Shanghai 200433 China

The main purpose of this work is to provide a novel numerical approach for the Volterra integral equations based on a spectral approach. A Legendre-collocation method is proposed to solve the Volterra integral equations of the second kind. We provide a rigorous error analysis for the proposed method, which indicates that the numerical errors decay exponentially provided that the kernel function and the source function are sufficiently smooth. Numerical results confirm the theoretical prediction of the exponential rate of convergence. The result in this work seems to be the first successful spectral approach （with theoretical justification） for the Volterra type equations.

关键词： Legendre-spectral method Second kind Volterra integral equations Convergence analysis.

Analysis of structural response under blast loads using the coupled SPH-FEM approach

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1184-1192页

作者： Jun-xiang xu Xi-la LIU Department of Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China

A numerical model using the coupled smoothed panicle hydrodynamics-finite element method （SPH-FEM） approach is presented for analysis of structures under blast loads. The analyses on two numerical cases, one for free field explosive and the other for structural response under blast loads, are performed to model the whole processes from the propagation of the pressure wave to the response of structures. Based on the simulation, it is concluded that this model can be used for reasonably accurate explosive analysis of structures. The resulting information would be valuable for protecting structures under blast loads.

关键词： Smoothed particle hydrodynamics (SPH) Finite element method (FEM) Reinforced concrete structure Explosion

Efficient projected gradient methods for cardinality constrained optimization

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2019年第2期62卷 245-268页

作者： Fengmin xu Yuhong dai Zhihu Zhao Zongben xu School of Economics and Finance Xi'an Jiaotong University LSEC ICMSEC Academy of Mathematics and Systems ScienceChinese Academy of Sciences School of Mathematics and Statistics Xi'an Jiaotong University

Sparse optimization has attracted increasing attention in numerous areas such as compressed sensing, financial optimization and image processing. In this paper, we first consider a special class of cardinality constrained optimization problems, which involves box constraints and a singly linear constraint. An efficient approach is provided for calculating the projection over the feasibility set after a careful analysis on the projection subproblem. Then we present several types of projected gradient methods for a general class of cardinality constrained optimization problems. Global convergence of the methods is established under suitable assumptions. Finally, we illustrate some applications of the proposed methods for signal recovery and index *** for index tracking, we propose a new model subject to an adaptive upper bound on the sparse portfolio weights. The computational results demonstrate that the proposed projected gradient methods are efficient in terms of solution quality.

关键词： sparse approximation projected gradient method global convergence signal recovery index tracking

Structural, magnetic and electronic properties of the iron-chalcogenide AxFe2-ySe2 （A=K, Cs, Rb, and TI, etc.） superconductors

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2011年第4期6卷 410-428页

作者： dai-xiang Mou Lin Zhao Xing-jiang Zhou National Laboratory for Superconductivity Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China

The latest discovery of a new iron-chalcogenide superconductor AXFe2-ySe2 （A =K, Cs, Rb, and Tl, etc.） has attracted much attention due to a number of its unique characteristics, such as the possible insulating state of the parent compound, the existence of Fe-vacancy and its ordering, a new form of magnetic structure and its interplay with superconductivity, and the peculiar electronic structures that are distinct from other Fe-based superconductors. In this paper, we present a brief review on the structural, magnetic and electronic properties of this new superconductor, with an emphasis on the electronic structure and superconducting gap. Issues and future perspectives are discussed at the end of the paper.

关键词： superconductor iron-chalcogenides electronic structure photoemission Fermi science superconducting gap crystal structure magnetic structure

Enhancing short-term ethanol-type fermentation of waste activated sludge by adding saccharomycetes and the implications for bioenergy and resource recovery

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2022年第3期34卷 179-189页

作者： Linke Zheng Ying xu Hui Geng Xiaohu dai State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Science and EngineeringTongji UniversityShanghai 200092China East China Architecture Design&Research Institute Shanghai 200002China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

Ethanol-type sludge fermentation has recently attracted much attention because it can enhance direct interspecies electron transfer and thus improve the anaerobic digestion of waste activated sludge(WAS). In this paper, the enhancement of short-term ethanol-type fermentation of WAS via adding Saccharomyces was investigated. The experimental results show that the maximum ethanol production of 1030.8 ± 20.6 mg/L was achieved, with the optimum fermentation conditions of a p H of 5.1, temperature of 26.0 ℃ and time of 8.0 hr. Although the content of volatile fatty acid(VFA) increased within 10 hr, it is one order of magnitude lower than the content of ethanol, indicating that the VFA generation did not affect the efficient production of ethanol. The analyses of changes in the microbial community during the fermentation process demonstrate that the greatest Saccharomyces activity occurred in the first 8 hr and it can play an important role in ethanol production even at a very low relative abundance. Meanwhile, most typical acid-producing bacteria were inhibited, but the hydrogenotrophic methanogens(i.e., Methanobacterium) were enriched to a certain extent. Further statistical analyses reveal that the Rhodobacter, Thermomonas, Terrimonas and Saccharomyces are responsible for ethanol production during the fermentation. However, these findings not only provide a reference for the development of enhancing ethanol-type fermentation of sludge, but also are expected to provide a new way of thinking for the efficient bioenergy and resource recovery from sludge.

关键词： Anaerobic digestion Sewage sludge Methane production Ethanol production Biodegradability

Decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes:Statistical molecular fragmentation model and DFT calculations

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第1期135卷 433-448页

作者： xiang Meng Pierre Désesquelles Lejin xu Department of Nuclear Engineering and Technology School of Energy and Power EngineeringHuazhong University of Science&TechnologyWuhan 430074China CNRS Laboratoire de Physique des Gaz et des PlasmasUniversitéParis-SaclayOrsay 91405France State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The treatment and disposal of radioactive waste are presently facing great *** ion exchange resins have become a focus of attention due to their high production and serious environmental *** this paper,a simplified model of cationic exchange resin is proposed,and the degradation processes of cationic resin monomer initiated by hydroxyl radicals(·OH)are clarified by combining statistical molecular fragmentation(SMF)model and density functional theory(DFT)*** prediction of active sites indicates that the S-O bonds and the C-S bond of the sulfonic group are more likely to react during the *** meta-position of the sulfonic group on the benzene ring is the most active site,and the benzene ring without the sulfonic group has a certain *** C11-C14 and C17-C20 bonds,on the carbon skeleton,are the most easily *** is also found that dihydroxy addition and elimination reactions play a major role in the process of desulfonation,carbon skeleton cleavage and benzene ring *** decomposition mechanisms found through the combination of physical models and chemical calculations,provide theoretical guidance for the treatment of complex polycyclic aromatic hydrocarbons.

关键词： Cationic exchange resin Statistical molecular fragmentation model Density functional theory Hydroxyl radical Decomposition mechanism

Study on a conical bearing for acceleration-sensitive equipment

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui xu Wen dai Junwu Jiang Tao Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China School of Civil Engineering and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during ***,isolation strategies give less attention to acceleration-sensitive systems or ***,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance *** a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system ***,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various *** to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement ***,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model