This paper focuses on the problem of dissipative filtering for nonlinear interconnected systems with interval time-varying delays. The considered nonlinear interconnected system is modeled by ...Takagi-Sugeno fuzzy rules. By constructing the delay-dependent Lyapunov-Krasovskii functional and using new integral inequality, the delay-dependent condition is established to ensure that the derived closed-loop system is asymptotically stable with strict <inline-formula><tex-math notation="LaTeX">(Q, S,R)-\alpha -</tex-math></inline-formula> dissipativity. In addition, a suitable filter is designed by solving a set of linear matrix inequalities. The presented method can provide better performance than the existing ones for the case of <inline-formula><tex-math notation="LaTeX">\mathcal {H}_\infty</tex-math></inline-formula> filtering. A simulation example is given to demonstrate the validity of the developed filter design technique.
We address stability of state feedback switched linear systems in which delays are present in both the feedback state and the switching signal of the switched controller. For switched systems with ...average dwell-time switching signals, we provide a condition, in terms of upper bounds on the delays and in terms of a lower bound on the average dwell-time, to guarantee asymptotic stability of the closed loop. The condition also implies that, in general, feedback switched linear systems are robust with respect to both small state delays and small switching delays. Our approach combines existing multiple Lyapunov function techniques with the merging switching signal technique, which gives relationships between the average dwell times of two mismatched switching signals and their mismatched times. A methodology for numerical solution based on linear matrix inequality is also included.
In the brief, delayed impulsive control is investigated for the synchronization of chaotic neural networks. In order to overcome the difficulty that the delays in impulsive control input can be ...flexible, we utilize the concept of average impulsive delay (AID). To be specific, we relax the restriction on the upper/lower bound of such delays, which is not well addressed in most existing results. Then, by using the methods of average impulsive interval (AII) and AID, we establish a Lyapunov-based relaxed condition for the synchronization of chaotic neural networks. It is shown that the time delay in impulsive control input may bring a synchronizing effect to the chaos synchronization. Furthermore, we use the method of linear matrix inequality (LMI) for designing average-delay impulsive control, in which the delays satisfy the AID condition. Finally, an illustrative example is given to show the validity of the derived results.
In this article, we investigate a new way of dealing with fault detection and isolation (FDI) for a class of delayed non-linear systems with an event-triggered mechanism (ETM). This article is based ...on 1) To estimate the dynamics of the nonlinear plant, Sliding Mode Observers (SMO's) is manipulated with Luenberger. 2) Under the ETM, sampled data is released only when the plant's measurement (sampled) violate the specific threshold of the event condition. 3) First, transform into two subsystems. In subsystem-A contains uncertainties without sensor fault and vice-versa in subsystem-B. To handle the uncertainties that appeared in subsystem-A, a new SMO's implemented while traditional Luenberger is employed to detect the sensor fault. Then, by using a new Lyapunov-Krasovskii function approach performance index is proposed. Based on stability criteria, sufficient conditions are provided in the account of Linear Matrix Inequalities (LMIs). The simulation example is given to demonstrate the effectiveness of our design method.
This article presents a compact 4-bit switched-line true-time delay (TTD) circuit over a wide frequency range extending from 3 to 30 GHz using novel delay elements. The delay elements, namely, the ...cascading coupled all-pass network (CAPN) and noncoupled all-pass network (NCAPN), were employed in the proposed TTD circuit to improve the delay-bandwidth product (DBW) while maintaining its compact size and low delay variation (DV). For comparison, a theoretical analysis for understanding the group delay feature of the APN with various coupling coefficients is presented along with low-pass network (LPN). To verify the proposed structure, the proposed delays are applied to construct the 4-bit switched-line TTD by utilizing two single-pole double-through (SPDT) and three double-pole double-through (DPDT) switches in a 28-nm CMOS process. The circuit has a compact size of 1.7 mm <inline-formula> <tex-math notation="LaTeX">\times0.2 </tex-math></inline-formula> mm, with a maximum delay of 68.5 ps and a minimum delay of 4.6 ps. The measured average insertion loss is 13.5 dB, and the in/out return loss is better than 10 dB across 3-30 GHz. The measured rms delay and gain errors are less than 2 ps and 3.2 dB, respectively, over the operating frequency range. To the best of our knowledge, the proposed TTD achieves the largest figure of merit (FoM) among the integrated TTD circuits.
<inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-path true time delay (TTD) circuits are highly attractive due to their high delay-bandwidth product, wideband response, ...scalability, and small size. However, in its standalone form, it cannot provide wideband input and output matching. To overcome these issues, we present a modified circuit of the <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-path TTD that includes an input low-noise amplifier (LNA) and an output buffer. The <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-path TTD response and its nonideal properties are analyzed further. A design guide is suggested, and an alternative isolated sampling switch is proposed. We present a 65-nm CMOS dedicated implementation, where the fine-tuning of the TTD is achieved by introducing two synchronized external local oscillator (LO) signals, with a relative shift between them. The core chip size is <inline-formula> <tex-math notation="LaTeX">0.32 \,\times \,0.575 </tex-math></inline-formula> mm 2 , and its power consumption is 30 mW for all delay states. In our implementation, we achieve a delay range of 1 ns for bandwidth (BW) of 0.2-3 GHz with a gain standard deviation (STD) of less than 0.14 dB between delay states and a relative delay STD of less than 10 ps (1%) over frequency.
With the ever increasing spectrum demand of broadband multimedia services, cognitive satellite terrestrial networks have emerged as a promising paradigm for future space information networks. To ...provide services with diverse delay quality-of-service (QoS) requirements in an energy-limited system, in this paper, we investigate energy efficient power allocation for cognitive satellite terrestrial networks. Employing statistical delay-QoS metric, power allocation schemes are formulated as optimization problems to maximize effective energy efficiency of secondary satellite communications while satisfying interference constraints imposed by primary terrestrial communications. Specifically, allowing for the availability of instantaneous channel state information (CSI) of the secondary transmitter-primary receiver link, optimal transmit powers are derived for both the cases of statistical and instantaneous interference constraints. Moreover, to provide a theoretical insight on the performance of the considered network, we derive closed-form expressions for the outage probability based on the obtained optimal transmit powers. The simulation results demonstrate the validity of the theoretical results and show the impacts of the delay exponent, interference constraint, and aggregate interference from terrestrial networks on the performance of satellite networks.
The technical note is concerned with the stabilization problem of networked control systems. A general framework is proposed firstly, where the zero-order hold has the logical capability of choosing ...the newest control input packet. The continuous-time process is discretized as a system with input delays. Then a sufficient condition for testing the stability of the discretized system and two sufficient conditions for designing a stabilizing controller are established based upon the Lyapunov theory. Finally numerical examples and simulations are used to illustrate the developed theory.
This paper studies the communication time-delay issue in islanded microgrids (MGs) with the distributed secondary control architecture. Firstly, a time-delayed MG small-signal model is developed. ...Then, a new weight-average-prediction (WAP) controller is proposed to compensate the delayed system states. By introducing a time-delayed differential term in the proposed control law, the traditional time-delayed small-signal model is transformed into a neutral time-delayed mathematic model. Based on the developed model, the stability analysis is conducted considering both fixed time delay and time-varying delay. For the fixed time delay, a novel graphic analytical method is proposed to evaluate the time delay margin, which eliminates the conservatism compared with existing time-domain methods. For the time-varying delay, stability condition is established by a Lyapunov-Krasovskii function and linear matrix inequalities. In addition, some non-linear WAP control methods are discussed to guide the parameter tuning with a higher resolution. Lastly, the proposed method and analytical result are verified in the OPAL-RT real-time test platform. The results demonstrate the effectiveness and high performance of the proposed controller.
In this study, mixed-delay-dependent robust stability problem is investigated for uncertain linear neutral systems with mixed delays. The existing stability conditions are obtained by employing the ...information of neutral delay and discrete delay independently, and are conservative to some extent. Different from most existing methods, this study attempts to introduce the interconnected information between neutral delay and discrete delay. Based on such an idea, the simple stability and robust stability conditions are firstly proposed by integral inequality method, then improved stability and robust stability conditions are obtained by incorporating delay-decomposition idea and augmented Lyapunov–Krasovskii functional. Theory analysis and examples show the benefits of the proposed techniques and conditions.
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