检索结果-南通市图书馆

Exponential synchronization of general chaotic delayed neural networks via hybrid feedback

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2期9卷 262-270页

作者： mei-qin LIU Jian-hai ZHANG School of Electrical Engineering Zhejiang University Hangzhou 3 10027 China

This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model,which is the interconnection of a linear delayed dynamic system and a bounded static nonlinear operator,and covers several well-known neural networks,such as Hopfield neural networks,cellular neural networks(CNNs),bidirectional associative memory(BAM)networks,recurrent multilayer perceptrons(RMLPs).By virtue of Lyapunov-Krasovskii stability theory and linear matrix inequality(LMI)technique,some exponential synchronization criteria are *** the drive-response concept,hybrid feedback controllers are designed to synchronize two identical chaotic neural networks based on those synchronization ***,detailed comparisons with existing results are made and numerical simulations are carried out to demonstrate the effectiveness of the established synchronization laws.

关键词： Exponential synchronization Hybrid feedback Drive-response conception Linear matrix inequality (LMI) Chaotic neural network model

Response to temperature stress of reactive oxygen species scavenging enzymes in the cross-tolerance of barley seed germination

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第12期11卷 965-972页

作者： Yu-qin mei Song-quan SONG Institute of Botany Chinese Academy of Sciences Beijing 100093 China

A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood. In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment to high-temperature stress and the possible involvement of reactive oxygen species （ROS） scavenging enzymes in the cross-tolerance. After pretreatment at 0 ℃ for different periods of time, barley seeds were germinated at 35 ℃, and the content of malondialdehyde （MDA） and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that barley seed germinated very poorly at 35 ℃, and this inhibitive effect could be overcome by pretreatment at 0 ℃. The MDA content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 ℃ did not change the MDA content. Compared with seeds germinated directly at 35 ℃, the seeds pretreated first at 0 ℃ and then germinated at 35 ℃ had markedly increased activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, catalase （CAT）, and glutathione reductase （GR）. The SOD and APX activities of seeds germinated at 35 ℃ after 0 ℃-pretreatment were even substantially higher than those at 25 ℃, and GR activity was similar to that at 25 ℃, at which the highest germination performance of barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity. This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system for the study of cross-tolerance.

关键词： Barley seed Cross-tolerance Germination/growth Reactive oxygen species (ROS) scavenging enzyme,Pretreatment at low temperature Temperature stress

Mg doping and native N vacancy effect on electronic and transport properties of AlN nanowires

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2015年第5期58卷 832-841页

作者： qin mei SHANG Yan WANG Xiao ZHANG GuiLing Innovative Research Team of Green Chemical Technology in University of Heilongjiang Province College of Chemical and Environmental Engineering Harbin University of Science and Technology

The effects of Mg doping(MgAl) and native N vacancy(VN) on the electronic structures and transport properties of Al N nanowire(Al NNW) were theoretically investigated by using density functional theory. Either the MgAl defect or the VN defect prefers to be formed on the Al NNW surfaces. Both MgAl and VN defects could increase the conductivity owing to introducing a defect band inside the band gap of Al N and split the Al N band gap into two subgaps. The defect concentration has little influence on the magnitude of the subgaps. The MgAl serves as a shallow acceptor rendering the nanowire a p-type conductor. The VN introduces a deep donor state enabling the nanowire an n-type conductor. The MgAl systems exhibit higher conductivity than the VN ones owing to the narrow subgaps of MgAl systems. The conductivity is roughly proportional to the defect concentration in the MgAl and VN defect systems. When the MgAl and VN coexist, the hole state of the MgAl defect and the electron state of the VN defect will compensate each other and their coupling state appears just above the valence-band maximum leading to a little decrease of the band gap compared with the pure Al NNW, which is unfavorable for the enhancing of the conductivity.

关键词： doping enabling rendering compensate introducing valence magnitude defects narrow nanotubes

Robust exponential stability analysis of a larger class of discrete-time recurrent neural networks

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) 2007年第12期8卷 1912-1920页

作者： ZHANG Jian-hai ZHANG Sen-lin LIU mei-qin Department of System Science ＆ Engineering School of Electrical Engineering Zhejiang University Hangzhou 310027 China

The robust exponential stability of a larger class of discrete-time recurrent neural networks (RNNs) is explored in this paper. A novel neural network model, named standard neural network model (SNNM), is introduced to provide a general framework for stability analysis of RNNs. Most of the existing RNNs can be transformed into SNNMs to be analyzed in a unified way. Applying Lyapunov stability theory method and S-Procedure technique, two useful criteria of robust exponential stability for the discrete-time SNNMs are derived. The conditions presented are formulated as linear matrix inequalities (LMIs) to be easily solved using existing efficient convex optimization techniques. An example is presented to demonstrate the transformation procedure and the effectiveness of the results.

关键词： Standard neural network model (SNNM) Robust exponential stability Recurrent neural networks (RNNs) Discrete-time Time-delay system Linear matrix inequality (LMI)

Energy-efficient localization and target tracking via underwater mobile sensor networks

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2018年第8期19卷 999-1012页

作者： Hua-yan CHEN mei-qin LIU Sen-lin ZHANG State Key Laboratory of Industrial Control Technology Zhejiang University College of Electrical Engineering Zhejiang University

Underwater mobile sensor networks(UMSNs) with free-floating sensors are more suitable for understanding the immense underwater environment. Target tracking, whose performance depends on sensor localization accuracy, is one of the broad applications of UMSNs. However, in UMSNs, sensors move with environmental forces,so their positions change continuously, which poses a challenge on the accuracy of sensor localization and target tracking. We propose a high-accuracy localization with mobility prediction(HLMP) algorithm to acquire relatively accurate sensor location estimates. The HLMP algorithm exploits sensor mobility characteristics and the multistep Levinson-Durbin algorithm to predict future positions. Furthermore, we present a simultaneous localization and target tracking(SLAT) algorithm to update sensor locations based on measurements during the process of target tracking. Simulation results demonstrate that the HLMP algorithm can improve localization accuracy significantly with low energy consumption and that the SLAT algorithm can further decrease the sensor localization error. In addition, results prove that a better localization accuracy will synchronously improve the target tracking performance.

关键词： Underwater mobile sensor networks Energy-efficient Sensor localization Target tracking

A new neural network model for the feedback stabilization of nonlinear systems

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8期9卷 1015-1023页

作者： mei-qin LIU Sen-lin ZHANG Gang-feng YAN School of Electrical Engineering Zhejiang University Hangzhou 310027 China

A new neural network model termed ‘standard neural network model’ (SNNM) is presented, and a state-feedback control law is then designed for the SNNM to stabilize the closed-loop system. The control design constraints are shown to be a set of linear matrix inequalities (LMIs), which can be easily solved by the MATLAB LMI Control Toolbox to determine the control law. Most recurrent neural networks (including the chaotic neural network) and nonlinear systems modeled by neural networks or Takagi and Sugeno (T-S) fuzzy models can be transformed into the SNNMs to be stabilization controllers synthesized in the framework of a unified SNNM. Finally, three numerical examples are provided to illustrate the design developed in this paper.

关键词： Standard neural network model (SNNM) Linear matrix inequality (LMI) Nonlinear control Asymptotic stability Chaotic cellular neural network Takagi and Sugeno (T-S) fuzzy model

H_∞ reference tracking control design for a class of nonlinear systems with time-varying delays

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2015年第9期16卷 759-768页

作者： mei-qin LIU Hai-yang CHEN Sen-lin ZHANG State Key Laboratory of Industrial Control Technology Zhejiang University College of Electrical Engineering Zhejiang University

This paper investigates the H∞ trajectory tracking control for a class of nonlinear systems with time- varying delays by virtue of Lyapunov-Krasovskii stability theory and the linear matrix inequality （LMI） technique. A unified model consisting of a linear delayed dynamic system and a bounded static nonlinear operator is introduced, which covers most of the nonlinear systems with bounded nonlinear terms, such as the one-link robotic manipulator, chaotic systems, complex networks, the continuous stirred tank reactor （CSTR）, and the standard genetic regulatory network （SCRN）. First, the definition of the tracking control is given. Second, the H∞ performance analysis of the closed-loop system including this unified model, reference model, and state feedback controller is presented. Then criteria on the tracking controller design are derived in terms of LMIs such that the output of the closed-loop system tracks the given reference signal in the H∞ sense. The reference model adopted here is modified to be more flexible. A scaling factor is introduced to deal with the disturbance such that the control precision is improved. Finally, a CSTR system is provided to demonstrate the effectiveness of the established control laws.

关键词： H∞ reference tracking Nonlinear system State feedback control Time-varying delays Unified model

Prime Mover Capacity Optimization and Thermodynamic Performance Analysis of Internal Combustion Engine Based CCHP System

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 Thermal Science 2023年第4期32卷 1583-1594页

作者： WANG Shucheng MUHAMMAD Imran LI Hongwei CHEN Xiaoxu qin mei School of Energy and Power Engineering Northeast Electric Power UniversityJilin132012China College of Engineering and Physical Sciences MechanicalBiomedical and Design EngineeringAston UniversityBirminghamB47ETUK Northeast Electric Power Design Institute Co. Ltd.of China Power Engineering Consulting GroupChangchun130021China

In this research,a solar hybrid combined cooling heating and power(CCHP)system is proposed considering the different scenarios of Prime Movers(PMs)and the part-load performance of PMs is validated by the designed values from the manufacturer of ***,a multi-optimization model based on a genetic algorithm is developed in order to select both the most promising performance PM and the most cost-effectiveness,environmentally friendly number of collectors for the proposed CCHP system,*** the hourly performance of this solar hybrid CCHP is determined through a case study of a hotel in *** show that the highest efficiency of the PM with larger capacity has the most promising performance and the collector number of 90 turns out to be a superior value for the hotel building based on the primary energy saving ratio of 61.61%.Moreover,on a typical summer day,the recovered waste heat and the solar energy can provide all the thermal energy demands,while,an auxiliary boiler should be started to fulfill the energy gap in both typical transition and winter *** the simulation result,the CO_(2) emissions can be reduced by 856.2 t/a due to the solar energy introduced into the ***,the dynamic investment payback period will change from 3.01 years to 3.56 years when the fuel price(P_(fuel))ranges from 0.8P_(fuel) to1.2P_(fuel).

关键词： combined cooling heating and power(CCHP)system distributed energy system optimization waste heat recovery ICE

Microstructure Regulation and Combustion Performance Optimization of PVDF/Al Composite Powder by Non-covalent Functionalized Graphenes

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 904-911页

作者：易卓然 DENG Haoyuan qin mei 孙一 LUO Guoqiang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Graphene prepared by non-covalent modification of sulfonated poly(ether-ether-ketone)(SPG)was combined with polyvinylidene fluoride(PVDF)/Al to improve the PVDF/Al thermal conductivity while reducing the effect of the thermal resistance at the graphene-polymer *** regulation rule of SPG with different contents on the energy release of fluorine-containing system was *** the content of SPG is 4%,the peak pressure and rise rate of SPG/PVDF/Al composite powder during ignition reach the maximum of 4845.28 kPa and 8683.58 kPa/*** the content of SPG is 5%,the PVDF/Al composite powder is completely coated by SPG,and the calorific value of the material reachs the maximum of 29.094 kJ/*** the design and micro-control of the composite powder,the calorific value of the material can be effectively improved,but the improvement of the mass release rate still depends on the graphene content and surface modification state.

关键词： energetic materials PVDF/Al composites graphene modification energy release combustion