Search results for "Nonlinear system"
showing 10 items of 1446 documents
Fuzzy Non-fragile H∞ Tracking Control for Flexible Air-breathing Hypersonic Vehicles
2012
Abstract This paper proposed a fuzzy non-fragile tracking control design method for flexible air-breathing hypersonic vehicles (FAHVs). The T-S fuzzy set approach is applied to the modeling of the complex nonlinear dynamics of FAHVs, and a T-S fuzzy model is constructed, which can represent the nonlinear hypersonic vehicle system. Then, by considering the actuator controller coefficients uncertainties and disturbances, the fuzzy non-fragile H ∞ tracking problem for FAHVs is proposed. A state-feedback controller design method is proposed to guarantee the tracking performance in the presence of actuator controller coefficients uncertainties. By a Lyapunov approach, the existence conditions fo…
Improved Hölder regularity for strongly elliptic PDEs
2019
We establish surprising improved Schauder regularity properties for solutions to the Leray-Lions divergence type equation in the plane. The results are achieved by studying the nonlinear Beltrami equation and making use of special new relations between these two equations. In particular, we show that solutions to an autonomous Beltrami equation enjoy a quantitative improved degree of H\"older regularity, higher than what is given by the classical exponent $1/K$.
Simulation and Parameter-Identification of the Closed-Loop Cardiovascular System by the Use of a Nonlinear Mathematical Model
1981
Abstract A non-linear model of human cardio-vascular system, which includes the short-term pressure regulation mechanism was mathematically derived and implemented on a PDP-11/45 in a block-oriented, interactive programming language. In this way the behaviour of the arterial and venous pressures, cardiac output, stroke volume, total peripheral resistance and heart-rate under ergometric workload was studied by simulation, and experimentally proved, that the model matches the system with good accuracy. In a second phase the parameters of the model were identified by the use of the output-error method. For this purpose a non-linear system identification programming package was applied. The par…
Definition of a fiber macro-model for nonlinear analysis of infilled frames
2017
A common way to model infill-frame interaction is the use equivalent strut macromodels. In most cases these are compression only resistant truss elements defined with a multi-linear axial-force / axial-displacement law. The main difficulty in using this approach is to correctly calibrate such a force-displacement curve (slope of ascending and post-peak branches, critical yielding, peak and residual forces) because of the large number of variables (mechanical and elastic properties of materials) and the different possible damage mechanisms activated for the frame-infill system. Another possible way is using fiber-section elements as diagonal struts. In this case the force-displacement law is…
An ant colony optimization-based fuzzy predictive control approach for nonlinear processes
2015
In this paper, a new approach for designing an adaptive fuzzy model predictive control (AFMPC) based on the ant colony optimization (ACO) is proposed. On-line adaptive fuzzy identification is introduced to identify the system parameters. These parameters are used to calculate the objective function based on a predictive approach and structure of RST control. Then the optimization problem is solved based on an ACO algorithm, used at the optimization process in AFMPC to determine optimal controller parameters of RST control. The utility of the proposed controller is demonstrated by applying it to two nonlinear processes, where the proposed approach provides better performances compared with p…
Network-based H∞ output feedback control for uncertain stochastic systems
2013
This paper investigates the problem of network-based Floc, output feedback control for a class of stochastic nonlinear systems. A novel model is proposed to describe the systems taken into two sides of communication channels in the network environment, which is more general than one side of communication channel. The design procedure of observer-based controller is presented, which, guarantees the asymptotic stability in the mean square of the resulting closed-loop system with an H-infinity performance. Finally, a crane example is utilized to show the effectiveness and potential of the developed techniques. Refereed/Peer-reviewed
Compensating for instantaneous signal mixing in transfer entropy analysis of neurobiological time series
2013
The transfer entropy (TE) has recently emerged as a nonlinear model-free tool, framed in information theory, to detect directed interactions in coupled processes. Unfortunately, when applied to neurobiological time series TE is biased by signal cross-talk due to volume conduction. To compensate for this bias, in this study we introduce a modified TE measure which accounts for possible instantaneous effects between the analyzed time series. The new measure, denoted as compensated TE (cTE), is tested on simulated time series reproducing conditions typical of neuroscience applications, and on real magnetoencephalographic (MEG) multi-trial data measured during a visuo-tactile cognitive experime…
Approach to the analysis of nonlinear feedback oscillators under large-signal injection
1986
A method for the analysis of driven oscillators under high-level injection is presented. It applies to single-loop feedback systems with a memoryless nonlinear element and a second-order (high-Q) tank circuit. The analysis technique employed combines the classical block-diagram approach with an improved firstharmonic dynamic modelling to provide a couple of differential equations capable of accounting for the amplitude-dependence effects arising under large-signal operation. On this basis, first-and second-order approximate expressions are also derived, which allow a better understanding of the validity limits of previous theories on this subject. As an example of application, both the stea…
On the integrability of the extended nonlinear Schrödinger equation and the coupled extended nonlinear Schrödinger equations
2000
We consider the extended nonlinear Schr¨ (ENLS) equation which governs the propagation of nonlinear optical fields in a fibre with higher-order effects such as higher-order dispersion and self-steepening. We show that the ENLS equation does not pass the Painlev´ test. Similarly, we claim that the coupled ENLS equations and N -coupled ENLS equations which govern the simultaneous propagation of two and more nonlinear fields in optical fibres are also not integrable from the Painlev´ e analysis point of view.
Linear and Nonlinear Interest Rate Exposure of Spanish Firms
2006
This paper carries out a comprehensive analysis of the interest rate risk borne by the Spanish firms on a sector basis. The traditional linear interest rate exposure model has been extended to allow for the possibility of a nonlinear exposure component as well as the presence of asymmetric behaviour in the exposure pattern. The obtained results show a significant interest rate exposure for some sectors, especially with regard to changes in the long-term interest rates. Moreover, it is documented that the linear exposure profile prevails over the asymmetric and nonlinear exposure patterns. In particular, the Construction sector is the sector that shows the highest incidence of interest rate …