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Trajectory parameter identification and impact point prediction for canard dual-spin projectile considering nonlinear effects 认领 引用
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作者 Xinxin Zhao Jinguang Shi Zhongyuan Wang 《Theoretical & Applied Mechanics Letters》 EI CAS CSCD 2026年第1期95-107,共13页
Canard dual-spin projectiles typically adjust the forebody roll angle for trajectory correction by analyzing devia-tions between predicted impact points and target positions.An accurate method for trajectory parameter... Canard dual-spin projectiles typically adjust the forebody roll angle for trajectory correction by analyzing devia-tions between predicted impact points and target positions.An accurate method for trajectory parameter identi-fication and impact point prediction is crucial for this process.This paper introduces nonlinear factors to couple geometric and aerodynamic nonlinear effects at large angles of attack,analyzes angular motion dynamics before and after control initiation,as well as their influence on center-of-mass motion,thereby establishing an improved modified point-mass trajectory equation for such projectiles.Moreover,by mapping the effects of random distur-bances and canard-body interactions to a finite set of primary characteristic parameters and employing periodic averaging to suppress fluctuations caused by rapid period changes of the complex angle of attack after control initiation,a nonlinear trajectory filtering model for both uncontrolled and controlled flights is proposed using the unscented Kalman filter algorithm,with its performance in parameter identification and impact point prediction systematically evaluated.Numerical results indicate that the improved modified point-mass trajectory equation accurately characterizes the nonlinear effects of canard control disturbances on aerodynamics and trajectory compared to traditional methods,closely matching rigid body trajectories for both uncontrolled and controlled flight,while improving computational efficiency by three orders of magnitude to meet real-time requirements.Furthermore,the filtering model effectively predicts uncontrolled trajectories and significantly reduces the influ-ence of canard control initiation and orientation changes on prediction accuracy during controlled flight,thereby providing a theoretical foundation for studying correction strategies and guidance control methods,particularly for multiple control initiations. 展开更多
关键词 Canard dual-spin projectile Improved modified point-mass trajectory equation Online real-time rapid trajectory computation Nonlinear trajectory parameter identification Impact point prediction for multiple control flights
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Global Singularity-Free Prescribed Performance Control for Faulty Nonlinear Systems via Parameterized Nonmonotonic Constraints 认领 引用
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作者 Yu Xia Jun He +2 位作者 Zsófia Lendek Imre J.Rudas Ramesh K.Agarwal 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2026年第5期1176-1183,共8页
In this paper,we investigate potential singularity issues in prescribed performance control induced by actuator faults and propose a global nonmonotonic prescribed performance scheme for strict-feedback nonlinear syst... In this paper,we investigate potential singularity issues in prescribed performance control induced by actuator faults and propose a global nonmonotonic prescribed performance scheme for strict-feedback nonlinear systems.This scheme allows for parameterized relaxation of constraint boundaries in the presence of actuator faults.Unlike existing prescribed performance control schemes that rely on redesigning nonmonotonic rate functions to modify boundary relaxation properties,the proposed method introduces a novel adjustment module into the prescribed performance function,enabling the parametric design of nonmonotonic boundaries.Moreover,the proposed method simultaneously addresses the removal of the initial feasibility condition and the imposition of asymmetric constraints by introducing a global asymmetric design with an error correction module.This module enables flexible conversion from asymmetric to symmetric boundaries at a predetermined time instant,thereby reducing transient overshoot while maintaining steady-state tracking precision.Simulation results validate the effectiveness and superiority of the proposed scheme. 展开更多
关键词 Actuator fault error correction global asymmetric design nonmonotonic prescribed performance control strict-feedback nonlinear system
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Adaptive identification of distributed parameters in nonlinear PDE setting:Sine-Gordon case study 认领 引用
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作者 Yury Orlov Boris Andrievsky 《Journal of Automation and Intelligence》 EI CSCD 2026年第2期147-154,共8页
The primary concern of the work is to develop adaptive identification approach to uncertain dynamic systems governed by nonlinear partial differential equations.The well-known nonlinear sine-Gordon PDE model,which des... The primary concern of the work is to develop adaptive identification approach to uncertain dynamic systems governed by nonlinear partial differential equations.The well-known nonlinear sine-Gordon PDE model,which describes distributed wave dynamics(e.g.,of continuum of interacting oscillators),serves as a testbed.It is shown that the sine-Gordon model with uncertain external force and viscous friction,which are distributed in space,is identifiable over the entire state measurement provided that it is excited by a specific nonzero input.Numerical simulations support the theory in the case where unknown plant parameters are spatially invariant. 展开更多
关键词 Nonlinear PDE systems Adaptive identification Lyapunov functional
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Nonlocal Boundary Value Problems for Nonlinear Fractional Differential Equations with a Disturbance Parameter on the Infinite Interval 认领 引用
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作者 ZHENG Yanping YANG Hui WANG Wenxia 《应用数学》 北大核心 2026年第2期360-372,共13页
This paper is concerned with a class of nonlinear fractional differential equations with a disturbance parameter in the integral boundary conditions on the infinite interval.By using Guo-Krasnoselskii fixed point theo... This paper is concerned with a class of nonlinear fractional differential equations with a disturbance parameter in the integral boundary conditions on the infinite interval.By using Guo-Krasnoselskii fixed point theorem,fixed point index theory and the analytic technique,we give the bifurcation point of the parameter which divides the range of parameter for the existence of at least two,one and no positive solutions for the problem.And,by using a fixed point theorem of generalized concave operator and cone theory,we establish the maximum parameter interval for the existence of the unique positive solution for the problem and show that such a positive solution continuously depends on the parameter.In the end,some examples are given to illustrate our main results. 展开更多
关键词 Boundary value problem Disturbance parameter Infinite interval Bifurcation point Cone
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Self-heating tendency evaluation of sulfide ores based on nonlinear multi-parameters fusion 认领 引用 被引量：4
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作者 潘伟 吴超 +1 位作者 李孜军 杨月平 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期582-589,共8页
In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials ... In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples （ore samples 1, 2, 6 and 9） are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is： sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results. 展开更多
关键词 sulfide ores self-heating process nonlinear characteristic parameter nonlinearity self-heating tendency
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Simultaneous identification of unknown time delays and model parameters in uncertain dynamical systems with linear or nonlinear parameterization by autosynchronization 认领 引用 被引量：4
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作者 顾卫东 孙志勇 +1 位作者 吴晓明 于长斌 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第9期190-196,共7页
In this paper, we propose a general method to simultaneously identify both unknown time delays and unknown model parameters in delayed dynamical systems based on the autosynchronization technique. The design procedure... In this paper, we propose a general method to simultaneously identify both unknown time delays and unknown model parameters in delayed dynamical systems based on the autosynchronization technique. The design procedure is presented in detail by constructing a specific Lyapunov function and linearizing the model function with nonlinear parameterization. The obtained result can be directly extended to the identification problem of linearly parameterized dynamical systems. Two Wpical numerical examples confirming the effectiveness of the identification method are given. 展开更多
关键词 autosynchronization parameter identification delay identification nonlinear parameterization
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Nonsingular terminal sliding mode approach applied to synchronize chaotic systems with unknown parameters and nonlinear inputs 认领 引用 被引量：3
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作者 Mohammad Pourmahmood Aghababa Hassan Feizi 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期107-116,共10页
This paper deals with the design of a novel nonsingular terminal sliding mode controller for finite-time synchro-nization of two different chaotic systems with fully unknown parameters and nonlinear inputs. We propose... This paper deals with the design of a novel nonsingular terminal sliding mode controller for finite-time synchro-nization of two different chaotic systems with fully unknown parameters and nonlinear inputs. We propose a novel nonsingular terminal sliding surface and prove its finite-time convergence to zero. We assume that both the master＇s and the slave＇s system parameters are unknown in advance. Proper adaptation laws are derived to tackle the unknown parameters. An adaptive sliding mode control law is designed to ensure the existence of the sliding mode in finite time. We prove that both reaching and sliding mode phases are stable in finite time. An estimation of convergence time is given. Two illustrative examples show the effectiveness and usefulness of the proposed technique. It is worthwhile noticing that the introduced nonsingular terminal sliding mode can be applied to a wide variety of nonlinear control problems. 展开更多
关键词 nonsingular terminal sliding mode finite-time synchronization uncertain parameter,nonlinear input
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Evaluation of spontaneous combustion tendency of sulfide ore heap based on nonlinear parameters 认领 引用 被引量：5
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作者 PAN Wei WU Chao +2 位作者 LI Zi-jun WU Zhi-wei YANG Yue-ping 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第10期2431-2437,共7页
To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variatio... To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variations of the measuring points of simulated ore heap were measured. Combined with wavelet transform and nonlinear parameters extraction, a new method for spontaneous combustion tendency of different areas in sulfide ore heap based on nonlinear parameters was proposed and its reliability was verified by field test. The results indicate that temperature field evolution of the simulated ore heap presents significant spatial difference during self-heating process. Area with the maximum increasing extent of temperature in sulfide ore heap changes notably with the proceeding of self-heating reaction. Self-heating of sulfide ore heap is a chaotic evolution process, which means that it is feasible to evaluate spontaneous combustion tendency of different areas by nonlinear analysis method. There is a relatively strong correlation between the maximum Lyapunov exponent and spontaneous combustion tendency with the correlation coefficient of 0.9792. Furthermore, the sort of the maximum Lyapunov exponent is consistent with that of spontaneous combustion tendency. Therefore, spontaneous combustion tendency of different areas in sulfide ore heap can be evaluated by means of the maximum Lyapunov exponent method. 展开更多
关键词 sulfide ore heap spontaneous combustion tendency self-heating process nonlinear parameters maximum Lyapunov exponent
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Novel Approach to Nonlinear PID Parameter Optimization Using Ant Colony Optimization Algorithm 认领 引用 被引量：12
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作者 Duan Hai-bin Wang Dao-bo Yu Xiu-fen 《Journal of Bionic Engineering》 EI 2006年第2期73-78,共6页
This paper presents an application of an Ant Colony Optimization （ACO） algorithm to optimize the parameters in the design of a type of nonlinear PID controller. The ACO algorithm is a novel heuristic bionic algorith... This paper presents an application of an Ant Colony Optimization （ACO） algorithm to optimize the parameters in the design of a type of nonlinear PID controller. The ACO algorithm is a novel heuristic bionic algorithm, which is based on the behaviour of real ants in nature searching for food. In order to optimize the parameters of the nonlinear PID controller using ACO algorithm, an objective function based on position tracing error was constructed, and elitist strategy was adopted in the improved ACO algorithm. Detailed simulation steps are presented. This nonlinear PID controller using the ACO algorithm has high precision of control and quick response. 展开更多
关键词 Ant Colony Optimization algorithm pheromone nonlinear PID parameter optimization
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Parameter identification of hysteretic model of rubber-bearing based on sequential nonlinear least-square estimation 认领 引用 被引量：11
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作者 Yin Qiang Zhou Li Wang Xinming 《Earthquake Engineering and Engineering Vibration》 SCIE EI 2010年第3期375-383,共9页
In order to evaluate the nonlinear performance and the possible damage to rubber-bearings(RBs)during their normal operation or under strong earthquakes,a simplified Bouc-Wen model is used to describe the nonlinear hys... In order to evaluate the nonlinear performance and the possible damage to rubber-bearings(RBs)during their normal operation or under strong earthquakes,a simplified Bouc-Wen model is used to describe the nonlinear hysteretic behavior of RBs in this paper,which has the advantages of being smooth-varying and physically motivated.Further,based on the results from experimental tests performed by using a particular type of RB(GZN 110)under different excitation scenarios,including white noise and several earthquakes,a new system identification method,referred to as the sequential nonlinear least-square estimation(SNLSE),is introduced to identify the model parameters.It is shown that the proposed simplified Bouc-Wen model is capable of describing the nonlinear hysteretic behavior of RBs,and that the SNLSE approach is very effective in identifying the model parameters of RBs. 展开更多
关键词 parameter identification rubber-bearing hysteretic behavior Bouc-Wen model sequential nonlinear least-square estimation
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Parameters optimization and nonlinearity analysis of grating eddy current displacement sensor using neural network and genetic algorithm 认领 引用 被引量：18
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作者 Hong-li QI Hui ZHAO +1 位作者 Wei-wen LIU Hai-bo ZHANG 《Journal of Zhejiang University-SCIENCE A》 SCIE EI CAS 2009年第8期1205-1212,共8页
A grating eddy current displacement sensor(GECDS) can be used in a watertight electronic transducer to realize long range displacement or position measurement with high accuracy in difficult industry conditions.The pa... A grating eddy current displacement sensor(GECDS) can be used in a watertight electronic transducer to realize long range displacement or position measurement with high accuracy in difficult industry conditions.The parameters optimization of the sensor is essential for economic and efficient production.This paper proposes a method to combine an artificial neural network(ANN) and a genetic algorithm(GA) for the sensor parameters optimization.A neural network model is developed to map the complex relationship between design parameters and the nonlinearity error of the GECDS,and then a GA is used in the optimization process to determine the design parameter values,resulting in a desired minimal nonlinearity error of about 0.11%.The calculated nonlinearity error is 0.25%.These results show that the proposed method performs well for the parameters optimization of the GECDS. 展开更多
关键词 Grating eddy current displacement sensor （GECDS） Artificial neural network （ANN） Genetic algorithm （GA） Parameters optimization Nonlinearity error
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A singularly perturbed reaction diffusion problem for the nonlinear boundary condition with two parameters 认领 引用 被引量：68
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作者 莫嘉琪 《Chinese Physics B》 SCIE EI CAS 2010年第1期13-16,共4页
A class of singularly perturbed initial boundary value problems of reaction diffusion equations for the nonlinear boundary condition with two parameters is considered. Under suitable conditions, by using the theory of... A class of singularly perturbed initial boundary value problems of reaction diffusion equations for the nonlinear boundary condition with two parameters is considered. Under suitable conditions, by using the theory of differential inequalities, the existence and the asymptotic behaviour of the solution for the initial boundary value problem are studied. The obtained solution indicates that there are initial and boundary layers and the thickness of the boundary layer is less than the thickness of the initial layer. 展开更多
关键词 nonlinear two parameters singular perturbation
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Singularly Perturbed Solution for Nonlinear Equations of Fourth Order with Two Parameters 认领 引用 被引量：3
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作者 陈丽华 莫嘉琪 刘树德 《Journal of Shanghai Jiaotong university(Science)》 EI 2008年第4期495-498,共4页
A class of singularly perturbed boundary value problem for nonlinear equation of fourth order with two parameters is considered. Under suitable conditions, the existence and asymptotic behavior of solution for boundar... A class of singularly perturbed boundary value problem for nonlinear equation of fourth order with two parameters is considered. Under suitable conditions, the existence and asymptotic behavior of solution for boundary value problem are studied using theory of differential inequalities. 展开更多
关键词 nonlinear two parameters singular perturbation
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Singularly perturbed solution for weakly nonlinear equations with two parameters 认领 引用 被引量：3
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作者 陈丽华 莫嘉琪 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第10期1343-1348,共6页
A class of singularly perturbed boundary value problems of weakly non linear equation for fourth order on the interval [a, b] with two parameters is considered. Under suitable conditions, firstly, the reduced solution... A class of singularly perturbed boundary value problems of weakly non linear equation for fourth order on the interval [a, b] with two parameters is considered. Under suitable conditions, firstly, the reduced solution and formal outer solution are constructed using the expansion method of power series. Secondly, using the transformation of stretched variable, the first boundary layer corrective term near x = a is constructed which possesses exponential attenuation behavior. Then, using the stronger transformation of stretched variable, the second boundary layer corrective term near x = a is constructed, wtfich also possesses exponential attenuation behavior. The thickness of second boundary layer is smaller than the first one and forms a cover layer near x = a. Finally, using the theory of differential inequalities, the existence, uniform validity in the whole interval [a, b] and asymptotic behavior of solution for the original boundary value problem are proved. Satisfying results are obtained. 展开更多
关键词 nonlinear two parameters singular perturbation
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Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes 认领 引用 被引量：3
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作者 许锋 汪晔晔 罗雄麟 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第9期1038-1047,共10页
Chemical processes are usually nonlinear singular systems.In this study,a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes,whic... Chemical processes are usually nonlinear singular systems.In this study,a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes,which are augmented as state variables.Based on the observability of the singular system,this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters.When the observability is satisfied,the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer.The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation.With the catalyst circulation rate as the only unknown input without model error,one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst circulation rate.However,when uncertain model parameters also exist,additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes. 展开更多
关键词 soft sensor state observer ＂nonlinear singular system unknown inputs uncertain model parameters riser reactor of fluid catalytic cracking unit
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Cauchy prior distribution-based AVO elastic parameter estimation via weakly nonlinear waveform inversion 认领 引用 被引量：3
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作者 麻纪强 耿建华 《Applied Geophysics》 SCIE CSCD 2013年第4期442-452,511,512,共11页
Cauchy priori distribution-based Bayesian AVO reflectivity inversion may lead to sparse estimates that are sensitive to large reflectivities. For the inversion, the computation of the covariance matrix and regularized... Cauchy priori distribution-based Bayesian AVO reflectivity inversion may lead to sparse estimates that are sensitive to large reflectivities. For the inversion, the computation of the covariance matrix and regularized terms requires prior estimation of model parameters, which makes the iterative inversion weakly nonlinear. At the same time, the relations among the model parameters are assumed linear. Furthermore, the reflectivities, the results of the inversion, or the elastic parameters with cumulative error recovered by integrating reflectivities are not well suited for detecting hydrocarbons and fuids. In contrast, in Bayesian linear AVO inversion, the elastic parameters can be directly extracted from prestack seismic data without linear assumptions for the model parameters. Considering the advantages of the abovementioned methods, the Bayesian AVO reflectivity inversion process is modified and Cauchy distribution is explored as a prior probability distribution and the time-variant covariance is also considered. Finally, we propose a new method for the weakly nonlinear AVO waveform inversion. Furthermore, the linear assumptions are abandoned and elastic parameters, such as P-wave velocity, S-wave velocity, and density, can be directly recovered from seismic data especially for interfaces with large reflectivities. Numerical analysis demonstrates that all the elastic parameters can be estimated from prestack seismic data even when the signal-to-noise ratio of the seismic data is low. 展开更多
关键词 Cauchy priori distribution AVO elastic parameters inversion weakly nonlinear waveform inversion
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Unknown parameter’s variance-covariance propagation and calculation in generalized nonlinear least squares problem 认领 引用 被引量：9
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作者 陶华学 郭金运 《Journal of Coal Science & Engineering(China)》 2005年第1期52-55,共4页
The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. Th... The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. The unknown parameter’s vari- ance-covariance propagation formula, considering the two-power terms, was concluded used to evaluate the accuracy of unknown parameter estimators in the generalized nonlinear least squares problem. It is a new variance-covariance formula and opens up a new way to evaluate the accuracy when processing data which have the multi-source, multi-dimensional, multi-type, multi-time-state, different accuracy and nonlinearity. 展开更多
关键词 generalized nonlinear least squares problem unknown parameter vari- ance-covariance propagation
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Inducing Unstable Grassland Equilibrium States Due to Nonlinear Optimal Patterns of Initial and Parameter Perturbations:Theoretical Models 认领 引用 被引量：2
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作者 SUN Guodong MU Mu 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第1期79-90,共12页
Due to uncertainties in initial conditions and parameters, the stability and uncertainty of grassland ecosystem simulations using ecosystem models are issues of concern. Our objective is to determine the types and pat... Due to uncertainties in initial conditions and parameters, the stability and uncertainty of grassland ecosystem simulations using ecosystem models are issues of concern. Our objective is to determine the types and patterns of initial and parameter perturbations that yield the greatest instability and uncertainty in simulated grassland ecosystems using theoretical models. We used a nonlinear optimization approach, i.e., a conditional nonlinear optimal perturbation related to initial and parameter perturbations （CNOP） approach, in our work. Numerical results indicated that the CNOP showed a special and nonlinear optimal pattern when the initial state variables and multiple parameters were considered simultaneously. A visibly different complex optimal pattern characterizing the CNOPs was obtained by choosing different combinations of initial state variables and multiple parameters in different physical processes. We propose that the grassland modeled ecosystem caused by the CNOP-type perturbation is unstable and exhibits two aspects： abrupt change and the time needed for the abrupt change from a grassland equilibrium state to a desert equilibrium state when the initial state variables and multiple parameters are considered simultaneously. We compared these findings with results affected by the CNOPs obtained by considering only uncertainties in initial state variables and in a single parameter. The numerical results imply that the nonlinear optimal pattern of initial perturbations and parameter perturbations, especially for more parameters or when special parameters are involved, plays a key role in determining stabilities and uncertainties associated with a simulated or predicted grassland ecosystem. 展开更多
关键词 conditional nonlinear optimal perturbation initial perturbation parameter perturbation grass-land ecosystem
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TECHNICAL STABILITY OF NONLINEAR TIME-VARYING SYSTEMS WITH SMALL PARAMETERS 认领 引用 被引量：1
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作者 楚天广 王照林 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2000年第11期1264-1271,共8页
Technical stability:allowing quantitative estimation of trajectory behavior of a dynamical system over a given time interval was considered. Based on a differential comparison principle and a basic monotonicity condit... Technical stability:allowing quantitative estimation of trajectory behavior of a dynamical system over a given time interval was considered. Based on a differential comparison principle and a basic monotonicity condition, technical stability relative to certain prescribed state constraint sets of a class of nonlinear time-varying systems with small parameters was analyzed by means of vector Liapunov function method. Explicit criteria of technical stability are established in terms of coefficients of the system under consideration. Conditions under which the technical stability of the system can be derived from its reduced linear time-varying (LTV) system were further examined, as well as a condition for linearization approach to technical stability of general nonlinear systems. Also, a simple algebraic condition of exponential asymptotic stability of LTV systems is presented. Two illustrative examples are given to demonstrate the availability of the presently proposed method. 展开更多
关键词 nonlinear time-varying system small parameter technical stability vector comparison principle reduced system linearization technique exponential asymptotic stability
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Molecular structure dependence of acoustic nonlinearity parameter B/A for silicone oils 认领 引用 被引量：1
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作者 张喆 陈功 章东 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第5期333-338,共6页
Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samp... Exploring new acoustic parameters is essential to develop a noninvasive imaging technique for the surgery of silicone oil tamponades. In this study, the acoustic nonlinearity parameters B/A of varied silicone oil samples （e.g., linear or hyper-branched） are experimentally measured by using a modified thermodynamic method. The results show that： （i） when the concentration of the silicone oil with a molecular weight of 5 × 10^4 increases from 0.5 g/100 ml to 8 g/100 ml, the corresponding B/A value increases by about 18%, but the acoustic velocity only increases by about 0.1%; （ii） when the molecular weight of the hyper-branched silicone oil is enhanced from 2 × 10^5 to 1 × 10^6, the B/A value increases by about 22%, while the acoustic velocity is only raised by about 0.2%. This study suggests that the B/A parameter of the silicone oil is more sensitive to the change in its molecular structure than that of the acoustic velocity. Thus, the B/A parameter might be utilized as an effective index for the development and optimization of the noninvasive imaging of the surgery of silicone oil tamponades. 展开更多
关键词 acoustic nonlinearity parameter molecular structure modified thermodynamic method siliconeoil
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