Time-delay Interval Research Articles

On Extracting Subfemtosecond Data from Femtosecond Quantum Dynamics Calculations: The Methane Cation.

Motivated by recent measurements of the subfemtosecond structural rearrangement in the methane cation using high-harmonic generation technology, here, we attempt an ab initio quantum dynamics study to explore such an event by modeling the experiments. This is done by calculating the ratio of the squared autocorrelation functions of wave packets that evolve on the X T2 electronic manifold of the isotopes CD4 and CH4 , in full dimensionality including nonadiabatic coupling. We have found good agreement with the experimental data, and additionally predict an unexpected maximum in the above ratio at ∼1.85 fs, thence outside the experimentally covered time-delay window. We further predict the above structural rearrangements to occur in ∼1.85 fs, and we propose a mechanism for this via a five-dimensional hypersurface developed from the JT active bending vibrations of e and t2 symmetry. Recurrences of such a maximum are also found with an interval of time delays, and the average of such intervals suggested corroboration of the oscillation time between the Td and the C2v geometries of CH4 . Furthermore, we perform a dynamics study up to 200 fs, and we unravel the underlying details of the first photoelectron band of CD4.

Modular networks with delayed coupling: Synchronization and frequency control

We study the collective dynamics of modular networks consisting of map-based neurons which generate irregular spike sequences. Three types of intramodule topology are considered: a random Erdös-Rényi network, a small-world Watts-Strogatz network, and a scale-free Barabási-Albert network. The interaction between the neurons of different modules is organized by relatively sparse connections with time delay. For all the types of the network topology considered, we found that with increasing delay two regimes of module synchronization alternate with each other: inphase and antiphase. At the same time, the average rate of collective oscillations decreases within each of the time-delay intervals corresponding to a particular synchronization regime. A dual role of the time delay is thus established: controlling a synchronization mode and degree and controlling an average network frequency. Furthermore, we investigate the influence on the modular synchronization by other parameters: the strength of intermodule coupling and the individual firing rate.

Synchronization analysis for nonlinear bilateral teleoperator with interval time‐varying delay

SummaryIn this paper, we investigate synchronization problem of nonlinear teleoperator in the presence of variable time delay. Compared with previous works, we relax the restriction of the communication delay range. Although approaches to the interval time delay can be found in many literatures, they are not suitable for nonlinear teleoperator due to the properties of robotic systems. We first investigate the synchronization of teleoperation system with interval time delay and make full use of the information of both the lower and upper bounds of delay. All criteria are presented in the form of LMI, which can be easily calculated by MATLAB (MathWorks, USA). Finally, numerical example and simulation are given to show the effectiveness of the main results. Copyright © 2014 John Wiley & Sons, Ltd.

Frequency-tuning input-shaped manifold-based switching control for underactuated space robot equipped with flexible appendages

Underactuated control problems, such as the control of a space robot without actuators on the main body, have been widely investigated. However, few studies have examined attitude control problems of underactuated space robots equipped with a flexible appendage, such as solar panels. In order to suppress vibration in flexible appendages, a zero-vibration input-shaping technique was applied to the link motion of an underactuated planar space robot. However, because the vibrational frequency depends on the link angles, simple input-shaping control methods cannot sufficiently suppress the vibration. In this paper, the dependency of the vibrational frequency on the link angles is measured experimentally, and the time-delay interval of the input shaper is then tuned based on the frequency estimated from the link angles. The proposed control method is referred to as frequency-tuning input-shaped manifold-based switching control (frequency-tuning IS-MBSC). The experimental results reveal that frequency-tuning IS-MBSC is capable of controlling the link angles and the main body attitude to maintain the target angles and that the vibration suppression performance of the proposed frequency-tuning IS-MBSC is better than that of a non-tuning IS-MBSC, which does not take the frequency variation into consideration.

Organization of knowledge maps in the knowledge logistic system “Integration”

In the paper an approach for investigating asymptotic stability of nonlinear interval timedelay system is proposed on the base of Lyapunov’s direct method and interval analysis. A sufficient condition of asymptotic stability is obtained using the concept of Lyapunov-Krasovsky functional.

A New Approach to Robust and Non-Fragile Control of Uncertain T-S Fuzzy Systems with Interval Time-Delay

This paper describes the synthesis of robust and non-fragile state feedback controllers for T-S fuzzy system with time-varying delay in a range and parameter uncertainties. A new method is proposed by de¯ning new Lyapunov functionals and introducing some free-weighting matrices. Impr oved delay-dependent results are presented.

Robust and Passive Constrained Fuzzy Control for Discrete Fuzzy Systems with Multiplicative Noises and Interval Time Delay

The passive fuzzy control for discrete-time uncertain Takagi-Sugeno (T-S) fuzzy models with multiplicative noises and time delay is investigated subject to robust asymptotical stability. Applying Jensen’s inequality and free-weighting matrix technique, less conservative sufficient conditions are derived via choosing Lyapunov function to analyze and synthesize the robust asymptotical stability and passivity of closed-loop system. The derived conditions are not strictly linear matrix inequality (LMI) problems, thus the cone complementarity technique is employed to propose a suboptimal technique to solve the proposed nonstrictly LMI problems. An algorithm is developed in this paper to design the fuzzy controller which can be accomplished by state-feedback scheme or output-feedback scheme. Finally, numerical examples are provided to demonstrate the feasibility and applicability of the proposed fuzzy controller design technique.

Multi-controller approach to uncertain discrete-time-delay systems

In this paper, a switched robust control is designed for a class of discrete-time systems subject to linear fractional uncertainty and interval time-delays. The controller is based on state feedback and the LMIs-based stability conditions are derived using an improved Lyapunov-Krasovskii functional. Moreover, the switching rule as well as the state feedback gains are determined from the minimisation of a guaranteed cost function. The theoretical results are illustrated with numerical examples.

Novel Global Exponential Stability Criterion for Recurrent Neural Networks with Time-Varying Delay

The problem of global exponential stability for recurrent neural networks with time-varying delay is investigated. By dividing the time delay interval [0,τ(t)] intoK+1dynamical subintervals, a new Lyapunov-Krasovskii functional is introduced; then, a novel linear-matrix-inequality (LMI-) based delay-dependent exponential stability criterion is derived, which is less conservative than some previous literatures (Zhang et al., 2005; He et al., 2006; and Wu et al., 2008). An illustrate example is finally provided to show the effectiveness and the advantage of the proposed result.

Suppression of Repeat-Intensive False Targets Based on Temporal Pulse Diversity

This paper considers the problem of suppressing the repeat-intensive false targets produced by a deception electronic attack (EA) system equipped with a Digital Radio Frequency Memory (DRFM) device. Different from a conventional repeat jammer, this type of jamming intensively retransmits the intercepted signal stored in a DRFM to the victim radar in a very short time-delay interval relative to a radar pulse wide. A multipeak matched-filtering output is then produced other than the merely expected true target. An electronic protection (EP) algorithm based on the space time block code (STBC) is proposed to suppress the adverse effects of this jammer. By transmitting a pulse sequence generated from the STBC in succession and the following cancellation process applied upon the received signal, this algorithm performs successfully in a single antenna system provided that the target models are nonfluctuating or slow fluctuating and the pulse repetition frequency (PRF) is comparatively high. The performance in white and correlated Gaussian disturbance is evaluated by means of Monte Carlo simulations.

Robust Exponential Stability and Stabilization of a Class of Nonlinear Stochastic Time‐Delay Systems

AbstractThis paper presents new exponential stability and delayed‐state‐feedback stabilization criteria for a class of nonlinear uncertain stochastic time‐delay systems. By choosing the delay fraction number as two, applying the Jensen inequality to every sub‐interval of the time delay interval and avoiding using any free weighting matrix, the method proposed can reduce the computational complexity and conservativeness of results. Based on Lyapunov stability theory, exponential stability and delayed‐state‐feedback stabilization conditions of nonlinear uncertain stochastic systems with the state delay are obtained. In the sequence, the delayed‐state‐feedback stabilization problem for a nonlinear uncertain stochastic time‐delay system is investigated and some sufficient conditions are given in the form of nonlinear inequalities. In order to solve the nonlinear problem, a cone complementarity linearization algorithm is offered. Mathematical and/or numerical comparisons between the proposed method and existing ones are demonstrated, which show the effectiveness and less conservativeness of the proposed method.

Idle Speed Control for GDI Engines with Interval Time-Delay

The gasoline direct injection (GDI) engine is a highly non-linear and a delayed system. The engine modle with time-delays is derived. The delays consist of an intake to torque production state delay and a network -induced interval delay. Base on the Liapunov-Krasovskii function, the criterion of interval delay control system is proposed, which ensure the idle speed control system is stability as well as robust. The simulation results show that the H∞ control has good robustness,which improves the stability of the idle speed of the GDI engine.

Delay-segment-dependent robust stability for uncertain discrete stochastic Markovian jumping systems with interval time delay

This article deals with the problem of robust stochastic stability for a class of uncertain discrete stochastic Markovian jumping systems with time-varying interval delay. By constructing a parameter-dependent Lyapunov–Krasovskii functional and checking its difference in two subintervals, respectively, some novel delay-segment-dependent stability criteria for the addressed system are derived. Two simulation examples are given to show effectiveness of the proposed method.

Fuzzy robust H ∞ filter design for nonlinear discrete-time systems with interval time delays

This article deals with the problem of H ∞ filter design for nonlinear discrete-time systems with norm-bounded parameter uncertainties and time-varying delays. A new Lyapunov function and free-weighting matrix method are used for filtering design, consequently, a delay-dependent design method is first proposed in terms of linear matrix inequalities, which produces a less conservative result. Finally, numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method.

Robust control for a class of T-S fuzzy systems with interval time-varying delay

The problem of delay-dependent stability analysis and controller design for a class of T-S fuzzy systems with interval state time-varying delay is considered. Based on Lyapunov stability theory, defining a new Lyapunov-Krasovskii functional and introducing some free-weighting matrices, a new delay-dependent criterion is given to ensure the systems asymptotically stable. The merit of the proposed conditions lies in the less conservativeness than the existing ones, which is achieved by considering the mean of time-delay interval and the introduction of the free variables. By the concept of parallel distributed compensation (PDC), a delay-dependent condition for the existence of a fuzzy state feedback control law with memory is proposed. Another merit is the consideration of the memory of the controller. All conditions are shown in terms of linear matrix inequalities (LMIs), which can be solved efficiently by using the LMI optimization techniques. Two numerical examples are given to illustrate the feasibility and validity of the proposed approach.

Estimation of bitumen froth quality using Bayesian information synthesis: An application to froth transportation process

AbstractThis study presents the design of soft sensors for estimation of bitumen froth quality in an oil sands natural froth lubricated (NFL) transportation process. One of the most important quality indexes for bitumen froth is the water content. Due to the variation in oil sands composition and the nature of multi‐phase process conditions, existing hardware sensors are not reliable enough to provide on‐line accurate water content measurement. Laboratory analysis result is obtained off‐line with large sampling interval and irregular time delay. Therefore, it is not sufficient for real‐time monitoring and control. To overcome these limitations, Bayesian information synthesis approach is proposed to fuse all the existing information to produce more reliable and more accurate real‐time froth quality information. This technique has been applied in Syncrude Canada Extraction operations; both monitoring and control performance illustrate the promising perspectives of the proposed approach. © 2012 Canadian Society for Chemical Engineering

An improved robust delay-dependent stability criterion for genetic regulatory networks with interval time delays

This paper proposes an improved robust delay-dependent criterion for stability of genetic regulatory networks with delays which vary in an interval. A modified Lyapunov–Krasovskii functional is used to derive a sufficient condition in terms of linear matrix inequalities (LMIs) which can be easily solved by various convex optimization algorithms. The derived stability criterion is less conservative than ones in the literature. A numerical example and simulation results show the effectiveness of the proposed method.

Energy-to-peak control for a class of discrete stochastic fuzzy systems with time-delay

This paper considers the problem of stochastic stabilization and energy-to-peak control for a class of discrete stochastic fuzzy systems with interval time-delays. The objective is to design a state feedback controller such that the closed-loop system is stochastic stable and satisfies energy-to-peak performance. Based on the idea of interval partitioning, some new sufficient conditions are presented in LMI.

Research on Multi-Step Prediction of Wind Speed Time Series Based on Parallel Support Vector Regression

Aiming at the problem of traditional iterative way to achieve method of multi-step prediction, new method of multi-step prediction based on parallel Support Vector Regression (SVR) was proposed. To begin with the time delay of time series will be calculated in this method, resample the time series according to the interval of time delay. What’s more the time series will be classified into several sets of data, and it sets up SVR model for the sets of each. Finally, the parallel prediction of each set is composed to get multi-step prediction result. This method not only eliminates the accumulated error, improves the accuracy of prediction, but also saves the computation time.

Robust stability and performance of interval process plant with interval time delay

In this paper, a two-degree-of-freedom control for an interval process plant with interval time delay to guarantee both robust stability and performance has been considered. A simple necessary condition and a sufficient condition for robust Hurwitz stability of an interval polynomial has been used to design a robust controller for a chemical process plant with delay subjected to unknown but bounded parameter uncertainties referred to as an interval process plant with interval time delay. A pre-filter is constructed to ensure the desired system performance. Simulation results are presented to establish the efficacy of the proposed method for an interval process plant with interval time delay.