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国内外河流(网)非线性动力系统防灾分形理论研究综述 被引量:7
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作者 田福昌 苑希民 +1 位作者 王秀杰 耿庆柱 《水利学报》 EI CSCD 北大核心 2018年第8期926-936,共11页
河流(网)非线性动力系统发展一般遵循"相对稳定—混沌—无序—分形自组织—恢复相对稳定"的变化规律,演变过程表现出一定的混沌分形特征。从长序列水文过程分形、洪水分期分形、河流形态演变分形、洪灾时序及频次分形、水文... 河流(网)非线性动力系统发展一般遵循"相对稳定—混沌—无序—分形自组织—恢复相对稳定"的变化规律,演变过程表现出一定的混沌分形特征。从长序列水文过程分形、洪水分期分形、河流形态演变分形、洪灾时序及频次分形、水文多尺度分形等5个方面,分析探讨了国内外河流(网)动力系统防灾分形理论研究动态及趋势展望。提出水利智能分形复合理论、流域多尺度洪灾分维动力机制、河型转化分维判别标准、河流演变复合参数分形特征与物理机制、堤防灾变系统演化分形混沌理论、水文多尺度智能分形与决策支持等方面是分形混沌学与水科学、灾害学及人工智能学交叉发展未来取得重要突破的关键方向。 展开更多
关键词 河流()动力系统 分形分维 水文序列 洪水分期 河型判别 智能分形 灾变系统 多尺度分形
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社会发展“动力丛林”问题辨析 被引量:5
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作者 龚培河 万丽华 《探索》 北大核心 2006年第4期162-166,共5页
社会发展动力理论中存在“动力丛林”问题———这些动力因素在同一个社会中有没有内在的逻辑一致性呢?它们是如何联动起来推动社会前进的?到底谁是核心的、关键的动力?本文通过梳理研究成果,探寻根本原因,来尝试解读这个问题。笔者把... 社会发展动力理论中存在“动力丛林”问题———这些动力因素在同一个社会中有没有内在的逻辑一致性呢?它们是如何联动起来推动社会前进的?到底谁是核心的、关键的动力?本文通过梳理研究成果,探寻根本原因,来尝试解读这个问题。笔者把动力丛林分成三个层面来理解:其一,从全局来看,社会发展动力是一个相互关联的系统,在总体上发挥作用;其二,在社会发展的不同阶段,起关键作用的主导动力是不同的,是变化的,它可能是生产力因素(经济关系),也可能是其他因素;其三,最终起基础作用的还是生产力因素(经济因素),尽管在很多情况下,它发挥的是间接的基本作用。 展开更多
关键词 历史唯物主义 社会发展动力 动力丛林”问题 动力系统网
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Distributed Power Control for Energy Conservation in Hybrid Cellular Network with Device-to-Device Communication 被引量:13
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作者 TANG Rui ZHAO Jihong QU Hua 《China Communications》 SCIE CSCD 2014年第3期27-39,共13页
Device-to-Device(D2D) communication has been proposed as a promising implementation of green communication to benefit the existed cellular network.In order to limit cross-tier interference while explore the gain of sh... Device-to-Device(D2D) communication has been proposed as a promising implementation of green communication to benefit the existed cellular network.In order to limit cross-tier interference while explore the gain of short-range communication,we devise a series of distributed power control(DPC) schemes for energy conservation(EC)and enhancement of radio resource utilization in the hybrid system.Firstly,a constrained opportunistic power control model is built up to take advantage of the interference avoidance methodology in the presence of service requirement and power constraint.Then,biasing scheme and admission control are added to evade ineffective power consumption and maintain the feasibility of the system.Upon feasibility,a non-cooperative game is further formulated to exploit the profit in EC with minor influence on spectral efficiency(SE).The convergence of the DPC schemes is validated and their performance is confirmed via simulation results. 展开更多
关键词 Device-to-Device communication distributed power control energy conservation interference avoidance biasing scheme admission control non-cooperative game
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The application of modeling and prediction with MRA wavelet network 被引量:2
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作者 LUShu-ping YANGXue-jing ZHAOXi-ren 《Journal of Marine Science and Application》 2004年第1期20-23,共4页
As there are lots of non-linear systems in the real engineering, it is very important to do more researches on the modeling and prediction of non-linear systems. Based on the multi-resolution analysis (MRA) of wavelet... As there are lots of non-linear systems in the real engineering, it is very important to do more researches on the modeling and prediction of non-linear systems. Based on the multi-resolution analysis (MRA) of wavelet theory, this paper combined the wavelet theory with neural network and established a MRA wavelet network with the scaling function and wavelet function as its neurons. From the analysis in the frequency domain, the results indicated that MRA wavelet network was better than other wavelet networks in the ability of approaching to the signals. An essential research was can:led out on modeling and prediction with MRA wavelet network in the non-linear system. Using the lengthwise sway data received from the experiment of ship model, a model of offline prediction was established and was applied to the short-time prediction of ship motion. The simulation results indicated that the forecasting model improved the prediction precision effectively, lengthened the forecasting time and had a better prediction results than that of AR linear model. The research indicates that it is feasible to use the MRA wavelet network in the short-time prediction of ship motion. 展开更多
关键词 MAR wavelet network non-linear system short-time prediction watercraft motion AR model
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Hybrid internal model control and proportional control of chaotic dynamical systems 被引量:1
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作者 齐冬莲 姚良宾 《Journal of Zhejiang University Science》 EI CSCD 2004年第1期62-67,共6页
A new chaos control method is proposed to take advantage of chaos or avoid it. The hybrid Internal Model Control and Proportional Control learning scheme are introduced. In order to gain the desired robust performance... A new chaos control method is proposed to take advantage of chaos or avoid it. The hybrid Internal Model Control and Proportional Control learning scheme are introduced. In order to gain the desired robust performance and ensure the system's stability, Adaptive Momentum Algorithms are also developed. Through properly designing the neural network plant model and neural network controller, the chaotic dynamical systems are controlled while the parameters of the BP neural network are modified. Taking the Lorenz chaotic system as example, the results show that chaotic dynamical systems can be stabilized at the desired orbits by this control strategy. 展开更多
关键词 CHAOS Neural network Internal model control Proportional control
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Modeling water and carbon fluxes above summer maize field in North China Plain with back-propagation neural networks 被引量:1
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作者 秦钟 苏高利 +2 位作者 于强 胡秉民 李俊 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE EI CAS CSCD 2005年第5期418-426,共9页
In this work, datasets of water and carbon fluxes measured with eddy covariance technique above a summer maize field in the North China Plain were simulated with artificial neural networks (ANNs) to explore the fluxes... In this work, datasets of water and carbon fluxes measured with eddy covariance technique above a summer maize field in the North China Plain were simulated with artificial neural networks (ANNs) to explore the fluxes responses to local environmental variables. The results showed that photosynthetically active radiation (PAR), vapor pressure deficit (VPD), air temperature (T) and leaf area index (LAI) were primary factors regulating both water vapor and carbon dioxide fluxes. Three-layer back-propagation neural networks (BP) could be applied to model fluxes exchange between cropland surface and atmosphere without using detailed physiological information or specific parameters of the plant. 展开更多
关键词 Carbon dioxide Water vapor and heat fluxes Three-layer back-propagation neural networks
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Control system design of hybrid fuel cell city bus 被引量:1
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作者 Li Jianqiu Xu Liangfei Hua Jianfeng Li Xiangjun Ouyang Minggao 《Engineering Sciences》 EI 2010年第1期84-91,共8页
This paper introduced the design of the hybrid powertrain of the Fuel Cell City Bus demonstrated in 2008 Beijing Olympic Games. The configuration of the hybrid fuel cell powertrain was introduced. The safety of hydrog... This paper introduced the design of the hybrid powertrain of the Fuel Cell City Bus demonstrated in 2008 Beijing Olympic Games. The configuration of the hybrid fuel cell powertrain was introduced. The safety of hydrogen storage and delivery system, the hydrogen leakage alarm system were developed. The real-time distributed control and diagnosis system based on the Time Trigger Controller Area Network (TTCAN) with 10 ms basic control period was developed. The concept and implementation of processor (or controller) monitor and process (or task) monitor technique based on the TYCAN were applied in this paper. The fault tolerant control algorithm of the fuel cell engine and the battery man- agement system were considered. The demonstration experience verified that the fault tolerant control was very important for the fuel cell city bus. 展开更多
关键词 hybrid fuel cell city bus time triggered controller area network control system design
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Hybrid Detection and Tracking of Fast-Flux Botnet on Domain Name System Traffic 被引量:2
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作者 邹福泰 章思宇 饶卫雄 《China Communications》 SCIE CSCD 2013年第11期81-94,共14页
Fast-flux is a Domain Name System(DNS)technique used by botnets to organise compromised hosts into a high-availability,loadbalancing network that is similar to Content Delivery Networks(CDNs).Fast-Flux Service Network... Fast-flux is a Domain Name System(DNS)technique used by botnets to organise compromised hosts into a high-availability,loadbalancing network that is similar to Content Delivery Networks(CDNs).Fast-Flux Service Networks(FFSNs)are usually used as proxies of phishing websites and malwares,and hide upstream servers that host actual content.In this paper,by analysing recursive DNS traffic,we develop a fast-flux domain detection method which combines both real-time detection and long-term monitoring.Experimental results demonstrate that our solution can achieve significantly higher detection accuracy values than previous flux-score based algorithms,and is light-weight in terms of resource consumption.We evaluate the performance of the proposed fast-flux detection and tracking solution during a 180-day period of deployment on our university’s DNS servers.Based on the tracking results,we successfully identify the changes in the distribution of FFSN and their roles in recent Internet attacks. 展开更多
关键词 domain name system BOTNET fast-flux
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Synchronization and Bifurcation Analysis in Coupled Networks of Discrete-Time Systems
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作者 SUN Wei-Gang CHEN Yan +1 位作者 LI Chang-Pin FANG Jin-Qing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第5X期871-876,共6页
Synchronization and bifurcation analysis in coupled networks of discrete-time systems are investigated in the present paper. We mainly focus on some special coupling matrix, i.e., the sum of each row equals a nonzero ... Synchronization and bifurcation analysis in coupled networks of discrete-time systems are investigated in the present paper. We mainly focus on some special coupling matrix, i.e., the sum of each row equals a nonzero constant u and the network connection is directed. A result that the network can reach a new synchronous state, which is not the asymptotic limit set determined by the node state equation, is derived. It is interesting that the network exhibits bifurcation if we regard the constant u as a bifurcation parameter at the synchronous state. Numerical simulations are given to show the efficiency of our derived conclusions. 展开更多
关键词 complex dynamical networks SYNCHRONIZATION BIFURCATION
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Influences on Generation of White Etching Crack Networks in Rolling Bearings 被引量:3
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作者 Joerg Loos Toni Blass +2 位作者 Joerg Franke Wolfram Kruhoeffer Iris Bergmann 《Journal of Mechanics Engineering and Automation》 2016年第2期85-94,共10页
In rare cases rolling bearings fail by WEC (white etching crack) damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stre... In rare cases rolling bearings fail by WEC (white etching crack) damage before reaching their calculated rating life, if so called additional loads are applied on the bearing in addition to the normal Hertzian stress (PHz). A number of additional loads have been identified by means of tests with rolling bearings. These can be small direct currents as a result of electrostatic charge or large alternating currents from inverter-fed drives that unintentionally flow through the bearing. WEC damages can also be initiated by a pure mechanical additional load which is dependent on factors including the bearing kinematics but also on the dynamics of the drive train. The current state of knowledge on this subject is presented and taken as the basis for developing a hypothesis on the WEC damage mechanism. If load situations critical for WEC cannot be avoided, the risk of WEC can be considerably reduced by the selection of suitable materials and coatings as well as, in some cases, of suitable lubricants. 展开更多
关键词 Rolling bearing WEC (white etching crack) WSF (white structure flaking) hydrogen fatigue.
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Research and practice of designing hydro/ photovoltaic hybrid power system in microgrid 被引量:2
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作者 Wang Yibo Xu Honghua 《Engineering Sciences》 EI 2013年第3期80-84,96,共6页
Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to com... Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation. 展开更多
关键词 photovoltaic system with battery hydro/PV hybrid power system isolated microgrid
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Integrated real-time roof monitoring 被引量:1
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作者 SHEN Bao-tang GUO Hua KING Andrew 《Journal of Coal Science & Engineering(China)》 2009年第3期313-317,共5页
CSIRO has recently developed a real-time roof monitoring system for under-groundcoal mines and successfully tried the system in gate roads at Ulan Mine.The systemintegrated displacement monitoring,stress monitoring an... CSIRO has recently developed a real-time roof monitoring system for under-groundcoal mines and successfully tried the system in gate roads at Ulan Mine.The systemintegrated displacement monitoring,stress monitoring and seismic monitoring in onepackage.It included GEL multianchor extensometers,vibrating wire uniaxial stress meters,ESG seismic monitoring system with microseismic sensors and high-frequency AE sensors.The monitoring system automated and the data can be automatically collected by acentral computer located in an underground nonhazardous area.The data are then transferredto the surface via an optical fiber cable.The real-time data were accessed at anylocation with an Internet connection.The trials of the system in two tailgates at Ulan Minedemonstrate that the system is effective for monitoring the behavior and stability of roadwaysduring Iongwall mining.The continuous roof displacement/stress data show clearprecursors of roof falls.The seismic data (event count and locations) provide insights intothe roof failure process during roof fall. 展开更多
关键词 roof fall real-time monitoring DISPLACEMENT STRESS SEISMICITY
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Modeling approaches to pressure balance dynamic system in shield tunneling 被引量:2
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作者 李守巨 于申 屈福政 《Journal of Central South University》 SCIE EI CAS 2014年第3期1206-1216,共11页
In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial n... In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests. 展开更多
关键词 intelligent modeling neural network pressure balance system excavation chamber analytically modeling approach
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Attack Vulnerability of Network with Duplication-Divergence Mechanism
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作者 WANG Li YAN Jia-Ren LIU Zi-Ran ZHANG Jian-Guo 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第4X期754-758,共5页
We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against targe... We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against target attack relatively. Furthermore, duplication-divergence network is broken down more quickly than its counterpart BA network under target attack. Such result is consistent with the fact of WWW and Internet networks under target attack. So duplication-divergence model is a more realistic one for us to investigate the characteristics of the world wide web in future. We also observe that the exponent γ of degree distribution and average degree are important parameters of networks, reflecting the performance of networks under target attack. Our results are helpful to the research on the security of network. 展开更多
关键词 complex network systems attack vulnerability statistical dynamics
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Development and Implementation of GSM-Based Distribution Automation System with Graphic User Interface in Nigeria Electric Power Distribution Network
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作者 Oyetunji Samson Adenle Edeko Fred Oba 《Journal of Energy and Power Engineering》 2013年第11期2181-2187,共7页
Lack of up-to-date information on efficient operation and maintenance of EPDS (electric power distribution systems), Nigeria is addressed by designing and implementing an indigenous real-time monitoring and diagnosi... Lack of up-to-date information on efficient operation and maintenance of EPDS (electric power distribution systems), Nigeria is addressed by designing and implementing an indigenous real-time monitoring and diagnosis system. The system encompasses the development of software driven hardware positioned at the remotely located sub-stations at the low voltage level to keep track of the network in real-time. The detection of faults exploits threshold passing algorithm through continuous monitoring of the network power quality. Communication between the RTU (remote terminal unit) and the DCC (distribution control center) which is based on GSM is initiated by disturbance. The DCC performs fault evaluation processing using the received data and predetermined faults signatures to determine the nature of disturbance and presents the result in graphic user interface environment. A fault reporting time of 2 s was achieved. The developed system exhibits a high degree of accuracy and manifests no spurious reports during testing. The resultant system limits the effects of interruption and increases power availability by reducing the down time. The system strengthens engineering and management capabilities required to enhance reliability by providing information about the network health status. 展开更多
关键词 AUTOMATION communication media current and electric power distribution.
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Geonets and Geotextiles as Leachate Containment Materials in Landfills: System Dynamics Modeling Perspective
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作者 Samson Olakunle Ojoawo lamiu Adetayo Dauda Olatunde Afeez Salami 《Journal of Civil Engineering and Architecture》 2012年第9期1252-1257,共6页
The effectiveness of geonet, geotextile and their composite as containment materials of landfill leachate has been examined in this paper through the use of system dynamics modeling method. The study area is Oriire Lo... The effectiveness of geonet, geotextile and their composite as containment materials of landfill leachate has been examined in this paper through the use of system dynamics modeling method. The study area is Oriire Local Government Area of Oyo State, Nigeria. Three materials were studied, which include: GN (geonet), GT (geotextile) and GC (geocomposite). The water absorption, hydraulic conductivity, porosity and thickness were the major properties studied in these liners. Governing equations coded in Visual Basic Computer Programming Language was employed in developing a model. Validation of the model was done with data on the study area. The interrelationship of the properties and the breakthrough times for each material was found through the STELLA 9.1.4 software application. This research showed that the effectiveness of the studied of the order GC 〈 GN 〈 GT. GT is, therefore, recommended for use as landfill liners in the study area. 展开更多
关键词 System dynamics GEONET GEOTEXTILE LINER Ogbomosoland.
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Design and Implementation of a Single-Phase Energy Meter with SMS Controlled and Monitored Recharge Capability
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作者 Anthony Uwakhonye Adoghe Victor Olugbenga Matthews +3 位作者 Peter Aigboviosa Amaize Joseph Oluwole Oloweni Timilehin Fiyinfoluwa Sanni Olayinka Ayo 《Journal of Energy and Power Engineering》 2016年第9期534-539,共6页
The Nigerian power sector is faced with poorly organized billing and consumer relations management. Tariff billing and collection has been a big problem in some community in Nigeria even with the introduction of prepa... The Nigerian power sector is faced with poorly organized billing and consumer relations management. Tariff billing and collection has been a big problem in some community in Nigeria even with the introduction of prepaid meters. The process of payment is cumbersome and stressful as consumers have to go and pay in banks and then take tellers to power utility office to confirm their power bills payment before they can recharge their cards. The major purpose of this work is to design and implement a convenient, cashless, automated and transparent electricity metering, billing and payment system. This project combines the power electronic meter with a communications network which in this case is a GSM (global system for mobile) network. Remote electricity billing is a unique concept, in which the electricity board can collect the consumed units' data from consumer on mobile phone using GSM network. A unique property of this system is that, the electricity board can disconnect or reconnect consumers from remote location through the mobile phone. As this project works on GSM network, the system can be controlled from any part of the country. 展开更多
关键词 METERING BILLING electricity board prepaid meter
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ON PERIODIC DYNAMICAL SYSTEMS 被引量:3
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作者 LUWENLIAN CHENTIANPING 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2004年第4期455-462,共8页
The authors investigate the existence and the global stability of periodic solution for dynamical systems with periodic interconnections, inputs and self-inhibitions. The model is very general, the conditions are quit... The authors investigate the existence and the global stability of periodic solution for dynamical systems with periodic interconnections, inputs and self-inhibitions. The model is very general, the conditions are quite weak and the results obtained are universal. 展开更多
关键词 Neural network Dynamical systems Periodic solution Global convergence
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COMPLEXITY ANALYSIS OF NETWORK-BASED DYNAMICAL SYSTEMS
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作者 Guofeng ZHANG Long WANG Tongwen CHEN 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2011年第3期413-432,共20页
This paper investigates the nonlinear dynamics of network-based dynamical systems where network communication channels of finite data rates are inserted into the closed loops of the control systems. The authors analyz... This paper investigates the nonlinear dynamics of network-based dynamical systems where network communication channels of finite data rates are inserted into the closed loops of the control systems. The authors analyze the bifurcation and chaotic behavior of the non-smooth dynamical systems. The authors first prove that for almost all system parameters there are no periodic orbits. This result distinguishes this type of non-smooth dynamical systems from many others exhibiting border-collision bifurcations. Next, the authors show analytically that the chaotic sets are separated from the region containing the line segment of all fixed points with a finite distance. Finally, the authors employ a simple model to highlight that both the number of clients sharing a common network channel and fluctuations in the available network bandwidth have significant influence on the performance of such dynamical systems. 展开更多
关键词 BIFURCATION FEEDBACK network-based dynamical system non-convexity periodicity.
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Counter-Rotating Type Pump-Turbine Unit Cooperating with Wind Power Unit 被引量:1
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作者 Tengen Murakami Toshiaki Kanemoto 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第1期7-12,共6页
This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/t... This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/turbulent wind.In this paper,the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode,and the performances and the flow conditions were investigated numerically and experimentally.The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model.While providing the pump unit for the turbine mode,the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclu-sively for the turbine mode.Besides,the runner/impeller of the unit works evidently so as to coincide the angularmomentum change through the front runners/impellers with that through the rear runners/impellers,namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.These results show that this type of unit is effective to work at not only the pumping but also the turbine modes. 展开更多
关键词 PUMP-TURBINE pumping mode turbine mode power supply counter-rotation
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