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| 1 | PERSISTENCE AND GLOBAL STABILITY FOR A THREE-SPECIES RATIO-DEPENDENT PREDATOR-PREY SYSTEM WITH TIME DELAYS IN TWO-PATCH ENVIRONMENTS显示文摘A three-species ratio-dependent predator-prey diffusion model with time de-lays is investigated. It is shown that the system is uniformly persistent under some ap-propriate conditions, and sufficient conditions are obtained for the global stability of the positive equilibrium of the system. | 徐瑞 陈兰荪 | 2002 | Acta Mathematica Scientia2002，22，4： | 12 |
| 2 | H_∞ Consensus Control of Discrete-Time Multi-Agent Systems Under Network Imperfections and External Disturbance显示文摘This paper presents a distributed control protocol for consensus control of multi-agent systems(MASs) under external disturbances and network imperfections, including communication delay and random packet dropout. To comply with the discrete nature of networked systems, in contrast to most of the existing work for MASs under network imperfections,the agents are modeled by discrete-time dynamics. The communication network is considered to be undirected, its delay is considered to be time-varying but bounded, and its packet dropout is modeled by a Bernoulli distributed white sequence.Sufficient conditions in terms of linear matrix inequalities(LMIs)for asymptotic mean-square consensus stability are derived under network imperfections without considering external disturbances.A desired disturbance attenuation level in the presence of both external disturbances and network imperfections is also provided.A simulation example is given to verify the effectiveness of the proposed approach in coping with network imperfection and disturbances. | Arezou Elahi Alireza Alfi Hamidreza Modares | 2019 | IEEE/CAA Journal of Automatica Sinica2019，6，3： | 12 |
| 3 | THE DYNAMIC BEHAVIORS OF VISCOELASTIC PIPE CONVEYING FLUID WITH THE KELVIN MODEL显示文摘Based on the differential constitutive relationship of linear viscoelastic material,a solid-liquidcoupling vibration equation for viscoelastic pipe conveying fluid is derived by the D’Alembert’s principle.Thecritical flow velocities and natural frequencies of the cantilever pipe conveying fluid with the Kelvin model(flutter instability)are calculated with the modified finite difference method in the form of the recurrence for-mula.The curves between the complex frequencies of the first,second and third mode and flow velocity ofthe pipe are plotted.On the basis of the numerical calculation results,the dynamic behaviors and stability ofthe pipe are discussed.It should be pointed out that the delay time of viscoelastic material with the Kelvinmodel has a remarkable effect on the dynamic characteristics and stability behaviors of the cantilevered pipeconveying fluid,which is a gyroscopic non-conservative system. | Wang Zhongmin Zhao Fengqun Feng Zhenyu Liu Hongzhao | 2000 | Acta Mechanica Solida Sinica2000，13，3： | 12 |
| 4 | 四旋翼飞行器时延积分反演容错控制显示文摘针对四旋翼飞行器在飞行过程中会出现执行机构故障,提出了一种简单有效的容错控制方法,该方法是将积分反演控制技术与时延控制(time delay control,TDC)技术相结合得到的。采用积分反演控制方法设计基本控制器,在此基础上利用TDC技术的逼近能力来补偿执行机构可能出现的故障,该方法省去了在线的故障检测和估计,仅需要一步状态迭代即可,仿真结果表明该控制器对执行机构故障具有较强的鲁棒性。 | 贺有智 刘同其 | 2015 | 系统工程与电子技术2015，37，10： | 10 |
| 5 | Delayed Hopf bifurcation in time-delayed slow-fast systems显示文摘This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems.Here the two delayed's have different meanings.The delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious distance.In a time-delayed system,the evolution of the system depends not only on the present state but also on past states.In this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's theory.It shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples. | ZHENG YuanGuang1 & WANG ZaiHua1,2 1 Institute of Vibration Engineering Research,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China 2 Institute of Science,PLA University of Science and Technology,Nanjing 211101,China | 2010 | Science China(Technological Sciences)2010，53，3： | 9 |
| 6 | GLOBAL STABILITY AND HOPF BIFURCATION OF AN SIS EPIDEMIC MODEL WITH TIME DELAYS显示文摘An SIS epidemic model with a discrete delay has been investigated in this article. By means of Liapunov functional, some sufficient conditions of global stability to endemic equilibrium and disease free equilibrium have been obtained. The influence of time delay on the stability of equilibria is displayed. The switch of stability and the Hopf bifurcation from the endemic equilibrium have been discussed. | YUAN Sanling MA Zhien (Department of Applied Mathematics, Xi’an Jiaotong University, Xi’an 710049, China) | 2001 | Journal of Systems Science & Complexity2001，14，3： | 7 |
| 7 | STABILITY OF LINEAR TIME VARIANT DYNAMIC SYSTEMS WITH MULTIPLE TIME DELAYS显示文摘By means of the frozen time approach and the Kronecker product,two criteria of asymptotic stability are derived for the linear,time variant dynamicsystems with either short time delays or with weak feedback involving arbitrary timedelays,respectively.It is found that the asymptotic stability of these retarded dy-nainic systems is governed by the maximal and minimal singular values of the coeffi-cient matrices and their time derivatives. | 王在华 胡海岩 | 1998 | Acta Mechanica Sinica1998，14，3： | 7 |
| 8 | New Results on Discrete-time Delay Systems Identification显示文摘A new approach for simultaneous online identification of unknown time delay and dynamic parameters of discrete-time delay systems is proposed in this paper.The proposed algorithm involves constructing a new generalized regression vector and defining the time delay and the rational dynamic parameters in the same vector.The gradient algorithm is used to deal with the identification problem.The effectiveness of this method is illustrated through simulation. | Sada Bedoui Majda Ltaief Kamel Abderrahim | 2012 | International Journal of Automation and computing2012，9，6： | 7 |
| 9 | GLOBAL ASYMPTOTIC STABILITY IN N-SPECIES COOPERATIVE SYSTEM WITH TIME DELAYS显示文摘GLOBALASYMPTOTICSTABILITYINN-SPECIESCOOPERATIVESYSTEMWITHTIMEDELAYS￥CUIJing'an(DepartmentofMathematics,XinjingUniversity,Urum... | CUI Jing’an(Department of Mathematics, Xinjing University, Urumqi 830046, China) | 1994 | Systems Science and Mathematical Sciences1994，7，1： | 5 |
| 10 | Stochastic averaging technique for SDOF strongly nonlinear systems with delayed feedback fractional-order PD controller显示文摘A stochastic averaging technique is proposed to study the randomly excited single-degree-of-freedom(SDOF) strongly nonlinear systems with delayed feedback fractional-order proportional-derivative(PD) controller. The delayed feedback fractional-order PD control force is approximated by an equivalent non-delay feedback control force combining with a quasi-linear elastic force and a quasi-linear damping force. The averaged It? stochastic differential equation for amplitude of the equivalent nonlinear system is derived by the generalized harmonic functions. The analytical stationary probability density function(PDF) is obtained with solving the reduced Fokker-Planck-Kolmogorov(FPK) equation. Two examples of van der Pol oscillator and RayleighDuffing oscillator are studied to illustrate the application and effectiveness of the proposed method. Numerical results display that the proposed method can yield to the high precision, and the time delay could ruin the control effectiveness, but also even amplifies the response of the system more than that of uncontrolled system. Furthermore, the study finds that the parameters of fractional-order α and time delay may cause the stochastic P-bifurcation. It is indicated that the delayed feedback fractional-order PD controller can offer a potentially effective tool for anti-control of stochastic | CHEN LinCong LIANG Xiao ZHU WeiQiu ZHAO YaoBing | 2019 | Science China(Technological Sciences)2019，62，2： | 5 |
| 11 | Stochastic stability of quasi-integrable Hamiltonian systems with time delay by using Lyapunov function method显示文摘The asymptotic Lyapunov stability of one quasi-integrable Hamiltonian system with time-delayed feedback control is studied by using Lyapunov functions and stochastic averaging method.First,a quasi-integrable Hamiltonian system with time-delayed feedback control subjected to Gaussian white noise excitation is approximated by a quasi-integrable Hamiltonian system without time delay.Then,stochastic averaging method for quasi-integrable Hamiltonian system is used to reduce the dimension of the original system,and after that the Lyapunov function of the averaged It equation is taken as the optimal linear combination of the corresponding independent first integrals in involution.Finally,the stability of the system is determined by using the largest eigenvalue of the linearized system.Two examples are used to illustrate the proposed procedure and the effects of delayed time on the Lyapunov stability are discussed as well. | LING Quan 1,JIN XiaoLing 1 &HUANG ZhiLong 2 1 Department of Mechanics,Zhejiang University,Hangzhou 310027,China 2 State Key Laboratory of Fluid Power Transmission and Control,Zhejiang University,Hangzhou 310027,China | 2010 | Science China(Technological Sciences)2010，53，3： | 5 |
| 12 | A new impedance and robust adaptive inverse control approach for a teleoperation system with varying time delay显示文摘This paper presents a new robust adaptive inverse control approach for a force-reflecting teleoperation system with varying time delay. First,an impedance control is designed for the master robot. Second,an adaptive inverse control is proposed for the slave robot. Finally,the slave side controller is modified such that the robust stability and performance are achieved. In addition,robust stability analysis has been performed and optimal behavior is ensured by using standard characteristic polynomials. It is shown that despite of presence of randomly-varying time delay,the proposed control algorithm compensates the position drifts efficiently. Demonstrable simulation studies confirm the effectiveness of the proposed control system and its advantages over the existing sliding mode control strategies. | Mokhtar SHA SADEGHI Hamid Reza MOMENI | 2009 | Science China(Technological Sciences)2009，52，9： | 5 |
| 13 | A threshold effect of coupling delays on intra-layer synchronization in duplex networks显示文摘This paper investigates the impact of inter-layer coupling functions and intra-layer coupling delays on intra-layer synchronization regions and sychronizability. It is found that the inter-layer coupling functions have great influence on intra-layer synchronization regions, as well as on the intra-layer synchronizability. In particular, there exists an inter-layer coupling function such that the inter-layer coupling strength neither improves nor weakens the intra-layer synchronizability. Furthermore, no matter which one of three inter-layer coupling functions is chosen, a small intra-layer delay always keeps the intra-layer synchronized regions almost unchanged, implying that the small delay neither enhances nor suppresses the intra-layer synchronizability. At the same time the delay greatly frustrates the synchronizability in each layer when it is greater than some threshold. Our results may have potential applications for interconnected technological networks where communication delays are inevitably present. | TANG LongKun LU JunAn Lü JinHu | 2018 | Science China(Technological Sciences)2018，61，12： | 4 |
| 14 | PSO-based Parameter Tuning for a TwoDegree-of-Freedom IMC Scheme and Its Application to Paper Basis Weight Control显示文摘Basis weight is an important indicator for evaluating paper quality and a major factor directly affecting the economic benefits of enterprises.Focusing on the large time-delay,time-varying,and nonlinear characteristics of a basis weight control system,a two-degree-of-freedom(TDF)internal model control(IMC)method based on a particle swarm optimization(PSO)algorithm was proposed.The method took the integral of time multiplied by the absolute error(ITAE)as the objective function,and the PSO algorithm was used to optimize the time constant of the tuning IMC filter.The simulation results for the control system under the proposed TDF-IMC method based on the PSO algorithm demonstrate good set-point tracking performance,strong anti-interference capabilities,and good robustness properties.The application results revealed that the basis weight fluctuation range of the paper was±2 g/m2,which significantly improved both the control quality and the product quality. | Wei Tang Zhimin Yuan Wenjuan Shan MdMuhie Menul Haque | 2019 | Paper And Biomaterials2019，4，4： | 4 |
| 15 | Sensor Fault Diagnosis for a Class of Time Delay Uncertain Nonlinear Systems Using Neural Network显示文摘In this paper, a sliding mode observer scheme of sensor fault diagnosis is proposed for a class of time delay nonlinear systems with input uncertainty based on neural network. The sensor fault and the system input uncertainty are assumed to be unknown but bounded. The radial basis function (RBF) neural network is used to approximate the sensor fault. Based on the output of the RBF neural network, the sliding mode observer is presented. Using the Lyapunov method, a criterion for stability is given in terms of matrix inequality. Finally, an example is given for illustrating the availability of the fault diagnosis based on the proposed sliding mode observer. | Mou Chen~* Chang-Sheng Jiang Qing-Xian Wu College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PRC | 2008 | International Journal of Automation and computing2008，5，4： | 4 |
| 16 | High order single step time delay compensation algorithm for structural active control显示文摘The optimal instantaneous high order single step algorithm for active control is first discussed and then, the n+1 time step controlling force vector of the instantaneous optimal algorithm is derived from way of n time state vector. An estimating algorithm, is developed from this to solve the problem of active control with time delay compensation. The estimating algorithm based on this high order single step β method (HSM) foundation, is proven by simulation and experiment analysis, to be a valid solution to problem of active control with time delay compensation. | 王焕定 耿淑伟 王伟 | 2002 | Journal of Harbin Institute of Technology(New Series)2002，9，4： | 4 |
| 17 | Optimal feedback gains of a delayed proportional-derivative(PD) control for balancing an inverted pendulum显示文摘In the dynamics analysis and synthesis of a controlled system, it is important to know for what feedback gains can the controlled system decay to the demanded steady state as fast as possible. This article presents a systematic method for finding the optimal feedback gains by taking the stability of an inverted pendulum system with a delayed proportional-derivative controller as an example.First, the condition for the existence and uniqueness of the stable region in the gain plane is obtained by using the Dsubdivision method and the method of stability switch. Then the same procedure is used repeatedly to shrink the stable region by decreasing the real part of the rightmost characteristic root. Finally, the optimal feedback gains within the stable region that minimizes the real part of the rightmost root are expressed by an explicit formula. With the optimal feedback gains, the controlled inverted pendulum decays to its trivial equilibrium at the fastest speed when the initial values around the origin are fixed. The main results are checked by numerical simulation. | Qiang Wang Zaihua Wang | 2017 | Acta Mechanica Sinica2017，33，3： | 4 |
| 18 | Optimization of hepatobiliary phase delay time of Gd-EOB-DTPA-enhanced magnetic resonance imaging for identification of hepatocellular carcinoma in patients with cirrhosis of different degrees of severity显示文摘AIM To optimize the hepatobiliary phase delay time(HBPDT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging(GED-MRI) for more efficient identification of hepatocellular carcinoma(HCC) occurring in different degrees of cirrhosis assessed by Child-Pugh(CP) score.METHODS The liver parenchyma signal intensity(LPSI), the liver parenchyma(LP)/HCC signal ratios, and the visibility of HCC at HBP-DT of 5, 10, 15, 20, and 25 min(i.e., DT-5, DT-10, DT-15, DT-20, and DT-25) after injection of GdEOB-DTPA were collected and analyzed in 73 patients with cirrhosis of different degrees of severity(including 42 patients suffering from HCC) and 18 healthy adult controls.RESULTS The LPSI increased with HBP-DT more significantly in the healthy group than in the cirrhosis group(F = 17.361, P < 0.001). The LP/HCC signal ratios had a significant difference(F = 12.453, P < 0.001) among various HBP-DT points, as well as between CP-A and CP-B/C subgroups(F = 9.761, P < 0.001). The constituent ratios of HCC foci identified as obvious hypointensity(+++), moderate hypointensity(++), and mild hypointensity or isointensity(+/-) kept stable from DT-10 to DT-25: 90.6%, 9.4%, and 0.0% in the CP-A subgroup; 50.0%, 50.0%, and 0.0% in the CP-B subgroup; and 0.0%, 0.0%, and 100.0% in the CP-C subgroup, respectively.CONCLUSION The severity of liver cirrhosis has significant negative influence on the HCC visualization by GED-MRI. DT-10 is more efficient and practical than other HBP-DT points to identify most of HCC foci emerging in CP-A cirrhosis, as well as in CP-B cirrhosis; but an HBP-DT of 15 min or longer seems more appropriate than DT-10 for visualization of HCC in patients with CP-C cirrhosis. | Jian-Wei Wu Yue-Cheng Yu Xian-Li Qu Yan Zhang Hong Gao | 2018 | World Journal of Gastroenterology2018，24，3： | 4 |
| 19 | Effect of 2,5-dimethylfuran addition on ignition delay times of n-heptane at high temperatures显示文摘The shock tube autoignition of 2,5-dimethylfuran (DMF)/n-heptane blends (DMF)/n-100%, by mole fraction) with equivalence ratios of 0.5, 1.0, and 2.0 over the temperature range of 1200-1800 K and pressures of 2.0 atm and 10.0 atm were investigated. A detailed blend chemical kinetic model resulting from the merging of validated kinetic models for the components of the fuel blends was developed. The experimental observations indicate that the ignition delay times nonlinearly increase with an increase in the DMF addition level. Chemical kinetic analysis including radical pool analysis and flux analysis were conducted to explain the DMF addition effects. The kinetic analysis shows that at lower DMF blending levels, the two fuels have negligible impacts on the consumption pathways of each other.As the DMF addition increases to relatively higher levels, the consumption path of n-heptane is significantly changed due to the competition of small radicals, which primarily leads to the nonlinear increase in the ignition delay times of DMF/n-heptane blends. | Zhenhua GAO Erjiang HU Zhaohua XU Geyuan YIN Zuohua HUANG | 2019 | Frontiers in Energy2019，13，3： | 4 |
| 20 | A leader-follower stochastic linear quadratic differential game with time delay显示文摘In this paper, we are concerned with the leader-follower stochastic differential game of It?o type with time delay appearing in the leader's control. The open-loop solution is explicitly given in the form of the conditional expectation with respect to several symmetric Riccati equations. The key technique is to establish the nonhomogeneous relationship between the forward variables and the backward ones obtained in the optimization problems of both the follower and the leader. | Juanjuan XU Jingtao SHI Huanshui ZHANG | 2018 | Science China(Information Sciences)2018，61，11： | 3 |
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