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Sufficient and necessary conditions for Lyapunov stability of Lorenz system and their application

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Science china(Information Sciences) 2010年第8期53卷 1574-1583页

作者： LUO Qi 1 , LIAO XiaoXin 2.& ZENG ZhiGang 2.1 college of Information and Control, nanjing {2. of Information Science and technology, nanjing 2.0044, china 2.Department of Control Science and engineering, Huazhong {2. of Science and technology, Image Processing and Intelligent Control Key Laboratory of Education Ministry of china, Wuhan 430074, china college of Information and Control Nanjing University of Information Science and Technology Nanjing China Department of Control Science and engineering Huazhong University of Science and Technology Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Wuhan China

The sufficient and necessary conditions for Lyapunov stability of the zero equilibrium point of Lorenz system are discussed, and some brief criteria are presented for globally exponential stability, globally asymptotical stability and instability. Furthermore, the behavior of the non-zero equilibrium point of Lorenz system is also investigated, and several sufficient and necessary conditions are provided for locally exponential stability and instability. The established theorems in this paper develop and extend the existing achievements on Lyapunov stability of Lorenz system. In conclusion, by applying the obtained results, some less conservative feedback-control laws are derived to guarantee the globally exponential stability of the chaos control of Chen system, Lu¨ system, Yang-Chen system and Yu-Xia Li system.

关键词： Lorenz system Lyapunov stability sufficient and necessary condition bifurcation values globally exponential synchronization

Coupling analysis of unsteady seepage and stress fields in discrete fractures network of rock mass in dam foundation

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Science china(Technological Sciences) 2011年第S1期54卷 133-139页

作者： CHAI JunRui 1,2.& XU WeiSheng 2.1 college of Hydraulic and Environmental engineering,{2. Three Gorges university,Yichang 443002.{2. 2.college of Hydropower engineering,Xi’an university of technology,Xi’an 710048,{2. college of Hydraulic and Environmental engineering China Three Gorges University Yichang China college of Hydropower engineering Xi’an University of Technology Xi’an China

The drag force of water flow through single fracture and the coupling characteristics of seepage and stress in single fracture surface are analyzed,and a three dimensional model of coupled unsteady seepage and stress fields is *** model is used to the analysis of foundation rock mass of a high *** the coupling effects are considered,the changes of boundary heads have less influence on the inner head of rock mass,and the strong permeability of main fractures *** the coupling effects are not considered,the fractures distribution affects the inner head more *** the upstream water head declines,the inner head of dam foundation slightly declines and the hydraulic gradient distribution becomes smoother.A bigger upstream water level declining velocity has a stronger lag effect,meanwhile the values of stress components change more *** the upstream water level declining velocity directly affects the stability of rock mass in dam foundation and we should take into account the above factors to make sure the safety of the dam during reservoir level fluctuation period.

关键词： hydraulic engineering unsteady seepage stress coupling fractures network rock mass

On power allocation for a cognitive radio network with hybrid spectrum sharing

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Science china(Information Sciences) 2011年第11期54卷 2425-2434页

作者： ZHANG Jing 1,2.3 & ZHU HongBo 1 1 Key Laboratory of Wireless Communications of Jiangsu Province,nanjing university of Posts & Telecommunications,nanjing 2.0003,china 2.college of Electronic Science & engineering,nanjing university of Posts & Telecommunications,nanjing 2.0003,china 3 State Key Laboratory of Millimeter Waves,nanjing 2.0096,china Key Laboratory of Wireless Communications of Jiangsu Province Nanjing University of Posts & Telecommunications Nanjing China college of Electronic Science & engineering Nanjing University of Posts & Telecommunications Nanjing China State Key Laboratory of Millimeter Waves Nanjing China

In this study we propose a hybrid spectrum sharing scheme based on power control by combining Overlay with Underlay schemes,to improve radio spectrum *** the scheme,the secondary users dynamically switch their operational states between Overlay and Underlay according to the spectrum *** the dynamics of the primary network is first modeled with a discrete-state Markov process to find the time fraction of secondary users in the Overlay state and that in the Underlay state,which leads to the capacity model of the hybrid spectrum sharing *** the criterion of maximizing capacity,the power allocation of the cognitive network is researched and the optimum power allocation for secondary users is *** a result,the maximum achievable capacity of the cognitive network is *** are given to prove the analysis *** and simulated results indicate that hybrid spectrum sharing based on power control provides a higher capacity than single Overlay and Underlay systems for the cognitive network,i.e.,hybrid spectrum sharing can further improve radio spectrum efficiency.

关键词： cognitive radio network hybrid spectrum sharing primary network dynamics power allocation achievable capacity

Research on stability of the accumulated rock-soil body of reservoir bank under rainfall condition

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Science china(Technological Sciences) 2009年第9期52卷 2528-2535页

作者： GU ChongShi1,2.WU HaiZhen1,2.& SU HuaiZhi1,2.1 college of Water Resources and Hydropower engineering,Hohai {2.,nanjing 2.0098,china 2.National engineering Research Center of Water Resources Efficient Utilization and engineering Safety,Hohai {2.,nanjing 2.0098,china 3 Jiangxi Water Conservancy Research Institute,Nanchang 33002.,china college of Water Resources and Hydropower engineering Hohai University Nanjing China National engineering Research Center of Water Resources Efficient Utilization and engineering Safety Hohai University Nanjing China Jiangxi Water Conservancy Research Institute Nanchang China

The shear strength parameters property of rock-soil aggregates in embankment slope of reservoir,that is,the relationship between cohesion and gravel content,between friction angle and gravel content,and the relationship between cohesion and water content,between friction angle and water content,is studied based on the direct shear test results,the shear strength change law of the rock-soil aggregates is given,and the unsaturated shear strength formulation of rock-soil aggregates that could consider suction and saturation degree influence is put forward in this paper,through which the sliding or failure physical mechanism of this type of slope under the condition of rainfall infiltration is studied. Also the 3D unsteady saturated-unsaturated seepage field and its FEM resolving mode are established based on the analysis of the slope rainfall infiltration process. Case study with this method indicates that the minimum safety factor of the accumulated rock-soil aggregates dose not arrive at the moment of rainfall cessation,but appears several hours after the rainfall cessation,this phenomenon is in accordance with the practical slope engineering's failure process and could explain appropriately the slope failure caused by rainfall infiltration. Research results in this paper have an important reference value for the research on stability of the accumulated rock-soil aggregates in embankment slope of reservoir,and can enrich the stability analysis method and relevant theory of reservoir embankment slope.

关键词： reservoir bank slope rock-soil aggregates rainfall infiltration saturated/unsaturated seepage

The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

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Science china(Technological Sciences) 2006年第2期49卷 238-247页

作者： ZHANG Hai’ou1, QIAN Yingping1,3, WANG Guilan1 & ZHENG Qiguang2.1. School of material Science and technology, Huazhong {2. of Science and technology, Wuhan 430074, china 2. Institute of Laser technology and engineering, Huazhong {2. of Science and technology, Wuhan 430074, china 3. Mechanical engineering college, Hubei {2. of technology, Wuhan 430068, china School of material Science and technology Huazhong University of Science and Technology Wuhan China Mechanical engineering college Hubei University of Technology Wuhan China Institute of Laser technology and engineering Huazhong University of Science and Technology Wuhan China

As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

关键词： plasma hybrid laser, direct deposition, plasma arc beam, molding character, high-temperature alloy.

Back analysis of mechanical parameters of roller compacted concrete dam

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Science china(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1,2.3,LI Bo 1,XU GuangLei 4 &YU Hong 1,2.3 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering,Hohai university,{2. 2.0098,china 2.4} of Water Conservancy Hydropower,Hohai university,{2. 2.0098,china 3National engineering Research Center of Water Resources engineering Safety,Efficient Utilization and {2. 2.0098,china 4 {2. Hydraulic Research Institute,{2. 2.002.,china State Key Laboratory of Hydrology-Water Resources and Hydraulic engineering Hohai University Nanjing China college of Water Conservancy Hydropower Hohai University Nanjing China National engineering Research Center of Water Resources engineering Safety Efficient Utilization and Nanjing Nanjing China nanjing Hydraulic Research Institute Nanjing China

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

Review on hidden trouble detection and health diagnosis of hydraulic concrete structures

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Science china(Technological Sciences) 2007年第Z1期50卷 34-50页

作者： WU ZhongRu1,2., LI Ji1, GU ChongShi1,2.& SU HuaiZhi1,2.1 college of Water Conservancy and Hydropower engineering, Hohai {2., nanjing 2.0098, china 2.National engineering Research Center of Water Resources Efficient Utilization and engineering Safety, nanjing 2.0098, china college of Water Conservancy and Hydropower engineering Hohai University Nanjing China National engineering Research Center of Water Resources Efficient Utilization and engineering Safety Nanjing China

A large number of hydraulic concrete structures have hidden defects such as cracks, erosion, freeze and thaw, thermal fatigue, carbonization. These hidden defects seriously affect the strength, stability and durability of structures. These problems are studied mainly by single monitoring or diagnosis methods at present. The integration of multiple monitoring and diagnosis methods is not applied widely. Besides, the analysis theory on these problems is not developed very well. The systemic study on the aging mechanism of hydraulic concrete structures, time- variation model and health diagnosis is still not enough. The support for engineering practice is limited. Aimed at these major scientific and technological problems and combined with specific projects, study on detection of hidden defects and health diagnosis of hydraulic concrete structure has been carried out. This study includes the following content: field non-destructive examination of hidden defects of hydraulic concrete structures, seepage detection, the construction of in-situ sensing system, the combination of field detection and in-situ monitoring, the mechanism of crack, freeze and thaw, erosion and carbonization of hydraulic concrete structure, mechanism of combination aging; time-variation model of hydraulic concrete structure, theories and methods for health diagnosis of hydraulic concrete structures.

关键词： hydraulic concrete structure hidden trouble detection health diagnosis

Two-and Three-Dimensional Chloride Ingress into Fly Ash Concrete

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Journal of Wuhan university of technology({2.s Science) 2011年第5期26卷 978-982页

作者：张云升 Jiangsu Key Laboratory for Construction materials Southeast University college of materials Science and {2. Southeast University

2.,3D chloride ion concentration at the edge and corner zones were systematically investigated for fly ash concretes made with different cement replacement percentage by fly ash （0%,10%,2.%,40%,60%）,water to binder ratios （0.3,0.35,0.4）,and curing ages （2. d,90 d）.An interaction effect caused by 2. and 3D diffusion could obviously be observed through the comparison with 1D testing *** order to quantify the interaction effect,2. and 3D diffusion interaction coefficients was proposed in this ***,the changes of 2. and 3D interaction coefficients with the change in the free chloride ion concentration were *** above research provide an insight into chloride ion attack on the edge and corner reinforcing bars of concrete structures in the field of civil engineering.

关键词： fly ash concrete chlorides two and three dimension ingress

Simulation study of real-time monitor for BEPC-Ⅱ luminosity

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Science china(Technological Sciences) 2010年第5期53卷 1215-1219页

作者： SHAN Qing1,2.WU Jian2.XUE Zhen2.XU ZiZong2.HU Tao3,WANG YiFang3 & WANG XiaoLian2.1 college of material Science and {2.,nanjing university of Aeronautics and Astronautics,nanjing 2.0016,china 2.Department of Modern Physics,university of Science and {2. of china,Hefei 2.002.,china 3 Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,china college of material Science and {2. Nanjing University of Aeronautics and Astronautics Nanjing China Department of Modern Physics University of Science and Technology of China Hefei China Institute of High Energy Physics Chinese Academy of Sciences Beijing China

A fast and real time luminosity monitor system will be used in the BEPC-Ⅱ(Beijing Electron Positron Collider,china).Photons generated in radiative Bhabha scattering at the interaction point are transformed into charged particles,and then the luminosity of each bunch pair is measured through collecting the Cherenkov light produced by charged particles in fused *** whole process happening in the detector is *** physics acceptance and detection threshold with the monitor accu-racy of 1% are set based on the simulation spectra of photoelectron yield calibrated by e-beam data.

关键词： luminosity BEPC-Ⅱ Cherenkov detector radiative Bhabha