Consensus tracking control problems for single-integrator dynamics of multi-agent systems with switching topology are investigated. In order to design effective consensus tracking protocols for a more general class of...Consensus tracking control problems for single-integrator dynamics of multi-agent systems with switching topology are investigated. In order to design effective consensus tracking protocols for a more general class of networks, which are aimed at ensuring that the concerned states of agents converge to a constant or time-varying reference state, new consensus tracking protocols with a constant and time-varying reference state are proposed, respectively. Particularly, by contrast with spanning tree, an improved condition of switching interaction topology is presented. And then, convergence analysis of two consensus tracking protocols is provided by Lyapunov stability theory. Moreover, consensus tracking protocol with a time-varying reference state is extended to achieve the fbrmation control. By introducing formation structure set, each agent can gain its individual desired trajectory. Finally, several simulations are worked out to illustrate the effectiveness of theoretical results. The test results show that the states of agents can converge to a desired constant or time-varying reference state. In addition, by selecting appropriate structure set, agents can maintain the expected formation under random switching interaction topologies.展开更多
Based on strength reduction theory,the stability numbers of shallow tunnels were investigated within the framework of upper and lower bound theorems of limit analysis. Stability solutions taking into account of water ...Based on strength reduction theory,the stability numbers of shallow tunnels were investigated within the framework of upper and lower bound theorems of limit analysis. Stability solutions taking into account of water seepage were presented and compared with those without considering seepage. The comparisons indicate that the maximum difference does not exceed 3.7%,which proves the present method credible. The results show that stability numbers of shallow tunnels considering seepage are much less than those without considering seepage,and that the difference of stability numbers between considering seepage and without considering seepage increase with increasing the depth ratio. The stability numbers decrease with increasing permeability coefficient and groundwater depth. Seepage has significant effects on the stability numbers of shallow tunnels.展开更多
In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reducti...In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.展开更多
Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the "Dualistic" structure roek slope. The analysis presented here provides insight into the dynamic response of t...Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the "Dualistic" structure roek slope. The analysis presented here provides insight into the dynamic response of the "Dualistie" structure rock slope. By investigating the principle of energy distribution, it is shown that the effect of a joint plays a significant role in slope stability analysis. A dynamic reflection and transmission model (RTM) for the "Dualistic" structure rock slope and explicit dynamic equations are established to analyze the dynamic response of a slope, based on the theory of elastic mechanics and the principle of seismic wave propagation. The theoretical simulation solutions show that the dynamic response of the "Dualistic" structure rock slope (soft-hard) model is greater than that of the "Dualistic" strueture rock slope (hard-soft) model, especially in the slope crest. The magnifying effect of rigid foundation on the dynamic response is more obvious than that of soft foundation. With the amplitude increasing, the cracks could be found in the right slope (soft-hard) crest. The crest failure is firstly observed in the right slope (soft-hard) during the experimental process. The reliability of theoretical model is also investigated by experiment analysis. The conclusions derived in this paper could also be used in future evaluations of Multi-layer rock slopes.展开更多
In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula fo...In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula for calculating the thickness of the broken zone. The author points out that not only the ultimate strength of rockmass but its residual strength and strain-softening level all have a great influence on the stability of surrounding rock of a deep roadway. The paper’s results show that to reinforce surrounding rock, raise its residual strength and lower its strain-softening level should be taken as a basic requirement for supports of a deep roadway. In addition, the research also indicates that it is impossible for roadway supports to change surrounding rock states of a deep roadway, so it is certain for them to work in a broken state. For this reason, a sufficient yieldable quantity is necessary for roadway supports used in deep mining.展开更多
The material strength reserve method is practical in the study of the stability and failure mechanism of earth dam by analysing the development of failure zone of different shear strength parameters of the earth mass ...The material strength reserve method is practical in the study of the stability and failure mechanism of earth dam by analysing the development of failure zone of different shear strength parameters of the earth mass of the dam. The stability in the concrete dam and ensemble architecture has got general application while analysing. In combination with Feilaixia Multipurpose Project, application of this method to earth dam stability analysis was studied by plane Finite Element Method(FEM) for the first time. Through plane FEM, we can get the failure mechanism of earth dam and appraise to the security, for operating and managing put forward some reference suggestions.展开更多
It is imperative to evaluate factor of safety against basal heave failure in the design of braced deep excavation in soft clay.Based on previously published field monitoring data and finite element analyses of ground ...It is imperative to evaluate factor of safety against basal heave failure in the design of braced deep excavation in soft clay.Based on previously published field monitoring data and finite element analyses of ground settlements of deep excavation in soft clay,an assumed plastic deformation mechanism proposed here gives upper bound solutions for base stability of braced deep excavations.The proposed kinematic mechanism is optimized by the mobile depth(profile wavelength).The method takes into account the influence of strength anisotropy under plane strain conditions,the embedment of the retaining wall,and the locations of the struts.The current method is validated by comparison with published numerical study of braced excavations in Boston blue clay and two other cases of excavation failure in Taipei.The results show that the upper bound solutions obtained from this presented method is more accurate as compared with the conventional methods for basal heave failure analyses.展开更多
In this paper, a human immunodeficiency virus (HIV) infection model with both the types of immune responses, the antibody and the killer cell immune responses has been introduced. The model has been made more logica...In this paper, a human immunodeficiency virus (HIV) infection model with both the types of immune responses, the antibody and the killer cell immune responses has been introduced. The model has been made more logical by including two delays in the acti-vation of both the immune responses, along with the combination drug therapy. The inclusion of both the delayed immune responses provides a greater understanding of long-term dynamics of the disease. The dependence of the stability of the steady states of the model on the reproduction number R0 has been explored through stability theory. Moreover, the global stability analysis of the infection-free steady state and the infected steady state has been proved with respect to R0. The bifurcation analysis of the infected steady state with respect to both delays has been performed. Numerical simulations have been carried out to justify the results proved. This model is capable of explaining the long-term dynamics of HIV infection to a greater extent than that of the existing model as it captures some basic parameters involved in the system such as immunological delay and immune response. Similarly, the model also explains the basic understanding of the disease dynamics as a result of activation of the immune response toward the virus.展开更多
This paper is devoted to studying the uniqueness and existence of the system dynamic solution by using C0-semigroup theory and discussing its exponential stability by analyzing the spectrul distribution of system oper...This paper is devoted to studying the uniqueness and existence of the system dynamic solution by using C0-semigroup theory and discussing its exponential stability by analyzing the spectrul distribution of system operator and its quasi-compactness. Some primary reliability indices are discussed with the eigenfunction of system operator and the optimal vacation time to get the maximum system profit is analyzed at the end of paper.展开更多
Integrated pest management (IPM) is a long-term management strategy and has been proved to be more effective in pest control. To well-understand the mechanism and effect of the action of IPM, the geometric theory of...Integrated pest management (IPM) is a long-term management strategy and has been proved to be more effective in pest control. To well-understand the mechanism and effect of the action of IPM, the geometric theory of the involved semi-continuous dynamic systems is becoming more and more important. In this work, a geometric approach is applied to analyze the stability of the positive order-one periodic solution in semi-continuous dynamic systems. A stability criterion to test the stability of the order-one periodic solution is established. As an application, a stage-structure model involved chemical control is presented to show the efficiency of the proposed method. The sufficient conditions to insure the existence of the periodic solution are provided. In addition, the number and the stability of the periodic solutions are discussed accordingly. The simulations are carried out to verify the results.展开更多
In this paper, we analyze a nonlinear mathematical model of the HIV/AIDS and screening of unaware infectives on the transmission dynamics of the disease in a homoge- neous population with constant immigration of susce...In this paper, we analyze a nonlinear mathematical model of the HIV/AIDS and screening of unaware infectives on the transmission dynamics of the disease in a homoge- neous population with constant immigration of susceptibles incorporating use of condom, screening of unaware infectives and treatment of the infected. We consider constant con- trols and thereafter by incorporating the theory of Volterra-Lyapunov stable matrices into the classical method of Lyapunov functions, we present an approach for global stability analysis of HIV/AIDS. The analysis and results presented in this paper make building blocks toward a comprehensive study and deeper understanding of the funda- mental mechanism in HIV/AIDS. A numerical study of the model is also carried out to investigate the analytical results.展开更多
Dihedral fullerenes are thermodynamically stable molecules with Dnd or Dnh symmetry. Based on experimental findings, two series of dihedral fullerenes with five-fold (C5) and six-fold (C6) symmetry have been studi...Dihedral fullerenes are thermodynamically stable molecules with Dnd or Dnh symmetry. Based on experimental findings, two series of dihedral fullerenes with five-fold (C5) and six-fold (C6) symmetry have been studied using density functional theory (DFT). The DFT calculations showed that for both series the stabilities increased with increasing fullerene size. Structural analyses indicated that the stabilities are related to specific local geometries. In the case of the more abundant C5 series, the presence of approximately planar pentagons and hexagons on the top bowl favors their formation. That is to say, those fuller- enes with small dihedral angles within the polygons are readily formed, because planar hexagons lead to strengthened conjuga- tion which lowers average bonding energies (ABE) and increases thermodynamic stabilities. Non-planar hexagons at equatorial positions in tube-shaped fullerenes have an adverse effect on the conjugation and inhibit their formation. Calculations also demonstrated that fullerenes in the two series, including C50(D5h), C60(O6h), C80(O5d), C96(D6d), Cllo(D5h), and Cl20(D5d), have thermodynamically stable triplet structures with strong conjugation. The calculated IR and 13C NMR spectra of the fullerenes show some similarities and regular trends due to their homogenous structures. The electronic structures indicate that short dou- ble bonds in hexagons with high electron occupancies are readily attacked by electrophilic agents and can also be coordinated by transition metals. Mechanistic discussions suggested that C2 additions and C2 losses constitute reversible processes at high temperature and C2 additions in pentagonal fusions are crucial to the kinetics of the curvature of structures. C3 additions lead to the formation of large fullerenes of other types.展开更多
In this pape, almost periodic solution of a n-species Lotka-Volterra competition system with grazing rates and diffusions is investigated. By using the method of upper and lower solutions anti Schauder fixed point the...In this pape, almost periodic solution of a n-species Lotka-Volterra competition system with grazing rates and diffusions is investigated. By using the method of upper and lower solutions anti Schauder fixed point theorem as well as Lyapunov stability theory, we give sufficient conditions under which the strictly positive space homogeneous almost perilodic solution of the system is globally asymptotically stable. Moreover, some numerical simulations are given to validate our theoretical analysis.展开更多
Stability analysis is one of the key issues in car-following theory. The stability analysis with Lyapunov function for the two velocity difference car-following model(for short, TVDM) is conducted and the control meth...Stability analysis is one of the key issues in car-following theory. The stability analysis with Lyapunov function for the two velocity difference car-following model(for short, TVDM) is conducted and the control method to suppress traffic congestion is introduced. Numerical simulations are given and results are consistent with the theoretical analysis.展开更多
基金Projects(61075065,60774045) supported by the National Natural Science Foundation of ChinaProject supported by the Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘Consensus tracking control problems for single-integrator dynamics of multi-agent systems with switching topology are investigated. In order to design effective consensus tracking protocols for a more general class of networks, which are aimed at ensuring that the concerned states of agents converge to a constant or time-varying reference state, new consensus tracking protocols with a constant and time-varying reference state are proposed, respectively. Particularly, by contrast with spanning tree, an improved condition of switching interaction topology is presented. And then, convergence analysis of two consensus tracking protocols is provided by Lyapunov stability theory. Moreover, consensus tracking protocol with a time-varying reference state is extended to achieve the fbrmation control. By introducing formation structure set, each agent can gain its individual desired trajectory. Finally, several simulations are worked out to illustrate the effectiveness of theoretical results. The test results show that the states of agents can converge to a desired constant or time-varying reference state. In addition, by selecting appropriate structure set, agents can maintain the expected formation under random switching interaction topologies.
基金Project(200550) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of ChinaProject(09JJ1008) supported by Hunan Provincial Natural Science Foundation of ChinaProject(200631878557) supported by West Traffic of Science and Technology of China
文摘Based on strength reduction theory,the stability numbers of shallow tunnels were investigated within the framework of upper and lower bound theorems of limit analysis. Stability solutions taking into account of water seepage were presented and compared with those without considering seepage. The comparisons indicate that the maximum difference does not exceed 3.7%,which proves the present method credible. The results show that stability numbers of shallow tunnels considering seepage are much less than those without considering seepage,and that the difference of stability numbers between considering seepage and without considering seepage increase with increasing the depth ratio. The stability numbers decrease with increasing permeability coefficient and groundwater depth. Seepage has significant effects on the stability numbers of shallow tunnels.
基金Financial supports for this work, provided by the National Natural Science Foundation of China (No. 51274097)the Scientific Research Fund of Hunan Provincial Education Department of China (No. 13A020)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining, CUMT (No. 13KF03)
文摘In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.
基金financially supported by Project of the National Natural Science Foundation of China (Grant No. 41002126)Project of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Grant No. SKLGP2009Z010)
文摘Currently, scant attention has been paid to the theoretical analysis on dynamic response mechanism of the "Dualistic" structure roek slope. The analysis presented here provides insight into the dynamic response of the "Dualistie" structure rock slope. By investigating the principle of energy distribution, it is shown that the effect of a joint plays a significant role in slope stability analysis. A dynamic reflection and transmission model (RTM) for the "Dualistic" structure rock slope and explicit dynamic equations are established to analyze the dynamic response of a slope, based on the theory of elastic mechanics and the principle of seismic wave propagation. The theoretical simulation solutions show that the dynamic response of the "Dualistic" structure rock slope (soft-hard) model is greater than that of the "Dualistic" strueture rock slope (hard-soft) model, especially in the slope crest. The magnifying effect of rigid foundation on the dynamic response is more obvious than that of soft foundation. With the amplitude increasing, the cracks could be found in the right slope (soft-hard) crest. The crest failure is firstly observed in the right slope (soft-hard) during the experimental process. The reliability of theoretical model is also investigated by experiment analysis. The conclusions derived in this paper could also be used in future evaluations of Multi-layer rock slopes.
文摘In this paper the thickness of a broken zone, a state parameter of roadway surrounding rock, is used as the index to evaluate the stabi1ity of surrounding rock of a deep roadway. The paper gives a theoretic formula for calculating the thickness of the broken zone. The author points out that not only the ultimate strength of rockmass but its residual strength and strain-softening level all have a great influence on the stability of surrounding rock of a deep roadway. The paper’s results show that to reinforce surrounding rock, raise its residual strength and lower its strain-softening level should be taken as a basic requirement for supports of a deep roadway. In addition, the research also indicates that it is impossible for roadway supports to change surrounding rock states of a deep roadway, so it is certain for them to work in a broken state. For this reason, a sufficient yieldable quantity is necessary for roadway supports used in deep mining.
文摘The material strength reserve method is practical in the study of the stability and failure mechanism of earth dam by analysing the development of failure zone of different shear strength parameters of the earth mass of the dam. The stability in the concrete dam and ensemble architecture has got general application while analysing. In combination with Feilaixia Multipurpose Project, application of this method to earth dam stability analysis was studied by plane Finite Element Method(FEM) for the first time. Through plane FEM, we can get the failure mechanism of earth dam and appraise to the security, for operating and managing put forward some reference suggestions.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.51325901)the State Key Program of National Natural Science of China(Grant No.51338009)
文摘It is imperative to evaluate factor of safety against basal heave failure in the design of braced deep excavation in soft clay.Based on previously published field monitoring data and finite element analyses of ground settlements of deep excavation in soft clay,an assumed plastic deformation mechanism proposed here gives upper bound solutions for base stability of braced deep excavations.The proposed kinematic mechanism is optimized by the mobile depth(profile wavelength).The method takes into account the influence of strength anisotropy under plane strain conditions,the embedment of the retaining wall,and the locations of the struts.The current method is validated by comparison with published numerical study of braced excavations in Boston blue clay and two other cases of excavation failure in Taipei.The results show that the upper bound solutions obtained from this presented method is more accurate as compared with the conventional methods for basal heave failure analyses.
文摘In this paper, a human immunodeficiency virus (HIV) infection model with both the types of immune responses, the antibody and the killer cell immune responses has been introduced. The model has been made more logical by including two delays in the acti-vation of both the immune responses, along with the combination drug therapy. The inclusion of both the delayed immune responses provides a greater understanding of long-term dynamics of the disease. The dependence of the stability of the steady states of the model on the reproduction number R0 has been explored through stability theory. Moreover, the global stability analysis of the infection-free steady state and the infected steady state has been proved with respect to R0. The bifurcation analysis of the infected steady state with respect to both delays has been performed. Numerical simulations have been carried out to justify the results proved. This model is capable of explaining the long-term dynamics of HIV infection to a greater extent than that of the existing model as it captures some basic parameters involved in the system such as immunological delay and immune response. Similarly, the model also explains the basic understanding of the disease dynamics as a result of activation of the immune response toward the virus.
基金supported by the National Natural Science Foundation of China under Grant No.11001013
文摘This paper is devoted to studying the uniqueness and existence of the system dynamic solution by using C0-semigroup theory and discussing its exponential stability by analyzing the spectrul distribution of system operator and its quasi-compactness. Some primary reliability indices are discussed with the eigenfunction of system operator and the optimal vacation time to get the maximum system profit is analyzed at the end of paper.
文摘Integrated pest management (IPM) is a long-term management strategy and has been proved to be more effective in pest control. To well-understand the mechanism and effect of the action of IPM, the geometric theory of the involved semi-continuous dynamic systems is becoming more and more important. In this work, a geometric approach is applied to analyze the stability of the positive order-one periodic solution in semi-continuous dynamic systems. A stability criterion to test the stability of the order-one periodic solution is established. As an application, a stage-structure model involved chemical control is presented to show the efficiency of the proposed method. The sufficient conditions to insure the existence of the periodic solution are provided. In addition, the number and the stability of the periodic solutions are discussed accordingly. The simulations are carried out to verify the results.
文摘In this paper, we analyze a nonlinear mathematical model of the HIV/AIDS and screening of unaware infectives on the transmission dynamics of the disease in a homoge- neous population with constant immigration of susceptibles incorporating use of condom, screening of unaware infectives and treatment of the infected. We consider constant con- trols and thereafter by incorporating the theory of Volterra-Lyapunov stable matrices into the classical method of Lyapunov functions, we present an approach for global stability analysis of HIV/AIDS. The analysis and results presented in this paper make building blocks toward a comprehensive study and deeper understanding of the funda- mental mechanism in HIV/AIDS. A numerical study of the model is also carried out to investigate the analytical results.
文摘Dihedral fullerenes are thermodynamically stable molecules with Dnd or Dnh symmetry. Based on experimental findings, two series of dihedral fullerenes with five-fold (C5) and six-fold (C6) symmetry have been studied using density functional theory (DFT). The DFT calculations showed that for both series the stabilities increased with increasing fullerene size. Structural analyses indicated that the stabilities are related to specific local geometries. In the case of the more abundant C5 series, the presence of approximately planar pentagons and hexagons on the top bowl favors their formation. That is to say, those fuller- enes with small dihedral angles within the polygons are readily formed, because planar hexagons lead to strengthened conjuga- tion which lowers average bonding energies (ABE) and increases thermodynamic stabilities. Non-planar hexagons at equatorial positions in tube-shaped fullerenes have an adverse effect on the conjugation and inhibit their formation. Calculations also demonstrated that fullerenes in the two series, including C50(D5h), C60(O6h), C80(O5d), C96(D6d), Cllo(D5h), and Cl20(D5d), have thermodynamically stable triplet structures with strong conjugation. The calculated IR and 13C NMR spectra of the fullerenes show some similarities and regular trends due to their homogenous structures. The electronic structures indicate that short dou- ble bonds in hexagons with high electron occupancies are readily attacked by electrophilic agents and can also be coordinated by transition metals. Mechanistic discussions suggested that C2 additions and C2 losses constitute reversible processes at high temperature and C2 additions in pentagonal fusions are crucial to the kinetics of the curvature of structures. C3 additions lead to the formation of large fullerenes of other types.
基金This work is supported by Science and Technology Project of Chongqing Municipal Education Committee (Grant No. KJ 110501) of China, Natural Science Foundation Project of CQ CSTC (Grants No. CSTC2012jjA20016) of China and the NSFC (Grant Nos. 51005264, 11101298, 40801214) of China.
文摘In this pape, almost periodic solution of a n-species Lotka-Volterra competition system with grazing rates and diffusions is investigated. By using the method of upper and lower solutions anti Schauder fixed point theorem as well as Lyapunov stability theory, we give sufficient conditions under which the strictly positive space homogeneous almost perilodic solution of the system is globally asymptotically stable. Moreover, some numerical simulations are given to validate our theoretical analysis.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11372148,11372166the Natural Science Foundationof ZheJiang Province under Grant No.Y13A010029+1 种基金Disciplinary Project of Ningbo,China under Grant No.SZXL1067K.C.Wong Magna Fund in Ningbo University
文摘Stability analysis is one of the key issues in car-following theory. The stability analysis with Lyapunov function for the two velocity difference car-following model(for short, TVDM) is conducted and the control method to suppress traffic congestion is introduced. Numerical simulations are given and results are consistent with the theoretical analysis.