Publications

A unified control method for consensus with various quantizers

This paper studies the distributed consensus problem for networked general linear systems in the presence of different quantizers. The distinct features of this work are three-fold. First, both uniform and logarithmic quantization effects are analyzed. A unified control method (involving a distributed controller, a distributed event-detector, time-varying gains and constant parameters) is developed based on the relative quantized state information, which is applicable to practical scenarios where uniform and logarithmic quantization phenomena appear separately or alternately. Second, the updates of the relative information involved in the controller and the communication between adjacent agents are executed only at certain discrete event instants, significantly reducing the information update burden and data transmission load. Moreover, an internal variable, which is adjustable in accordance with the update law, is introduced in the event-detector to enhance the dynamic characteristics of the triggering performance with a lower triggering frequency. Simultaneously, the undesired Zeno behavior can be ruled out. Third, time-varying coupling gain (regulated by an adaptive rule) and triggering gain (relevant to the coupling gain) instead of constant ones are designed for the controller and the event-detector, respectively. Besides, other constant parameters can be easily tuned. These settings enable the developed control method to feature more flexibility and to be implemented in a fully distributed manner, requiring no global information. Finally, simulation examples are presented to illustrate the applicability of the theoretical results.

Kalman Filtering for Interval Systems

No abstract is provided for this article.

A Distributed Algorithm for Tracking General Functions of Multiple Signals Not-Necessarily Having Steady States

This brief exploits the possibility of devising an algorithm for tracking a general function pertaining to multiple signals from a multi-agent system in a distributed sense, where each agent has access to one single signal. Each agent's input relies solely on local neighboring information, from which some conditions on the gain parameters, the reference signals, along with the general function, are derived such that the tracking objective is attainable. The algorithm is well-defined as long as the gradient of the general function with respect to agents' states has a uniform lower bound. Under mild conditions, it is shown that the devised system is able to track a general consensus function of multiple dynamic signals, including arithmetic mean, geometric mean, and root-mean square as special examples. The effectiveness of the proposed algorithm is demonstrated via numerical examples.

Looking More Closely at the Rabinovich–Fabrikant System

Recently, we looked more closely into the Rabinovich–Fabrikant system, after a decade of study [Danca & Chen, 2004], discovering some new characteristics such as cycling chaos, transient chaos, chaotic hidden attractors and a new kind of saddle-like attractor. In addition to extensive and accurate numerical analysis, on the assumptive existence of heteroclinic orbits, we provide a few of their approximations.

On the Construction of Coprime Factorization of Nonlinear Feedback Control Systems

In this paper, we present a new approach for constructing left and right coprime factorizations for a large class of (stable and unstable) nonlinear feedback control systems developed recently by the authors [7], under relatively weak conditions. The coprime factorization under investigation here was formulated by Hammer mer [14]. We will describe the proposed constructive scheme for obtaining explicit and closed-form solutions. The same technique presented in this paper works also for the left coprime factorization for a class of nonlinear control systems described by standard vector-valued nonlinear ordinary differential equations formulated by Verma [20], which has been demonstrated in the authors' [6].

ADAPTIVE AND ROBUST AUTOMATIC TRAIN CONTROL SYSTEMS WITH INPUT SATURATION1

No abstract is provided for this article.

Cryptanalyzing a chaos-based image encryption algorithm using alternate structure

Recently, a chaos-based image encryption algorithm using alternate structure (IEAS) was proposed. This paper focuses on differential cryptanalysis of the algorithm and finds that some properties of IEAS can support a differential attack to recover equivalent secret key with a little small number of known plain-images. Detailed approaches of the cryptanalysis for cryptanalyzing IEAS of the lower round number are presented and the breaking method can be extended to the case of higher round number. Both theoretical analysis and experiment results are provided to support vulnerability of IEAS against differential attack. In addition, some other security defects of IEAS, including insensitivity with respect to changes of plain-images and insufficient size of key space, are also reported.

Complex Dynamics in a Memcapacitor-Based Circuit

In this paper, a new memcapacitor model and its corresponding circuit emulator are proposed, based on which, a chaotic oscillator is designed and the system dynamic characteristics are investigated, both analytically and experimentally. Extreme multistability and coexisting attractors are observed in this complex system. The basins of attraction, multistability, bifurcations, Lyapunov exponents, and initial-condition-triggered similar bifurcation are analyzed. Finally, the memcapacitor-based chaotic oscillator is realized via circuit implementation with experimental results presented.

ADAPTIVE CONTROL OF CHAOTIC n-SCROLL CHUA'S CIRCUIT

In this paper, stabilization of fixed points of n-scroll Chua's circuit is investigated. Two adaptive control methods are proposed. One is based on an unstable low pass filter; the other is based on a stable and an unstable low pass filter. The simulation results verify the effectiveness of the two proposed control methods and performance comparisons show that the second control method is superior to the first one with regard to control speed and attraction basins.

Neuroadaptive robust control of automatic train operation subject to actuator saturation

In this paper, neuroadaptive robust control problem for the automatic train operation (ATO) system under actuator saturation is considered. The saturation is caused by constraints from serving motors. A neuroadaptive robust control scheme is proposed. To cope with the actuator saturation, another neuroad-aptive robust control scheme is proposed for the ATO system, by explicitly considering the actuator saturation nonlinearity other than unknown system parameters, which is proved capable of stabilizing the closed-loop system. The effectiveness of the proposed control schemes are verified via numerical simulations.

Synchronization of Intermittently Coupled Dynamical Networks

This paper investigates the synchronization phenomenon of an intermittently coupled dynamical network in which the coupling among nodes can occur only at discrete instants and the coupling configuration of the network is time varying. A model of intermittently coupled dynamical network consisting of identical nodes is introduced. Based on the stability theory for impulsive differential equations, some synchronization criteria for intermittently coupled dynamical networks are derived. The network synchronizability is shown to be related to the second largest and the smallest eigenvalues of the coupling matrix, the coupling strength, and the impulsive intervals. Using the chaotic Chua system and Lorenz system as nodes of a dynamical network for simulation, respectively, the theoretical results are verified and illustrated.

Cryptanalysis of an Image Scrambling Scheme Without Bandwidth Expansion

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Recently, a new image scrambling (i.e., encryption) scheme without bandwidth expansion was proposed based on two-dimensional discrete prolate spheroidal sequences. A comprehensive cryptanalysis is given here on this image scrambling scheme, showing that it is not sufficiently secure against various cryptographical attacks including ciphertext-only attack, known/chosen-plaintext attack, and chosen-ciphertext attack. Detailed cryptanalytic results suggest that the image scrambling scheme can only be used to realize perceptual encryption but not to provide content protection for digital images. </para>

Joint Space Decomposition-and-Synthesis Approach and Achievable DoF Regions for $K$-User MIMO Interference Channels

The paper proposes a new approach of joint space decomposition-and-synthesis (JSDS) for deriving achievable degree-of-freedom (DoF) region by interference alignment without symbol extension for K-user MIMO interference channel. Solving the interference alignment problem is to find the precoders that align desired signal and interference with disjoint subspaces at receivers. A related property of these precoders is that the solution range for each one of them is a union of linear spaces, termed transmit spaces. Based on this property, the JSDS approach is developed to derive transmit spaces that fulfill alignment conditions. From this approach, achievable DoF regions for 2 and 3-user interference channels are obtained. The region for the 2-user channel is shown to coincide with the existing result of the DoF capacity of the channel. For the K-user (K > 3) case, inner as well as outer bounds are given.

Topological and Algebraic Structures of Atanassov's Intuitionistic Fuzzy-Values Space

We prove that the space of intuitionistic fuzzy values (IFVs) with a linear order based on a score function and an accuracy function has the same algebraic structure as the one induced by a linear order based on a similarity function and an accuracy function. By introducing a new operator for IFVs via the linear order based on a score function and an accuracy function, we show that such an operator is a strong negation on IFVs. Moreover, we observe that the space of IFVs is a complete lattice and a Kleene algebra with the new operator. We also demonstrate that the topological space of IFVs with the order topology induced by the above two linear orders is not separable and metrizable but compact and connected. From some new perspectives,our results partially answer three open problems posed by Atanassov [Intuitionistic Fuzzy Sets: Theory and Applications, Springer, 1999] and [On Intuitionistic Fuzzy Sets Theory, Springer, 2012]. Furthermore, we construct an isomorphism between the spaces of IFVs and q-rung orthopedic fuzzy values (q-ROFVs) under the corresponding linear orders. To this end, we introduce the concept of admissible similarity measures with particular orders for IFSs, extending the existing definition of the similarity measure for IFSs, and construct an admissible similarity measure with a linear order based on a score function and an accuracy function, which is effectively applied to a pattern recognition problem about the classification of building materials.

Bifurcations and Exact Traveling Wave Solutions in the Generalized Sasa–Satsuma Equation

This paper studies traveling wave solutions of a generalized Sasa–Satsuma equation introduced in [Adem et al., 2020]. For the cases of [Formula: see text], under given parameter conditions, the bifurcations of traveling wave solutions in the parameter space are investigated for the corresponding traveling systems. All possible explicit exact parametric representations of various solutions are obtained.

Fusion of video encoding and image stabilization

Digital image stabilization (DIS) is an elementary function of hand-held video-capturing devices. In conventional combination, video encoding is performed after DIS. However, both DIS and video encoding have the same time-consuming unit: motion estimation (ME). Thus, a novel methodology for fusion of DIS and video encoding is proposed in this paper to reduce the computation of ME and produce coding-compliant motion vectors (MVs). That is accomplished by re-using the MVs of DIS and the variable block sizes defined in H.264; thus, macro blocks (MBs) with MVs need not to compute MVs again. In addition to the MBs used in DIS, the rest area f a stabilized P frame is partitioned into many blocks by means of the variable block size as defined in H.264. By using the proposed method, the saving in chip area will result in great reduction of power and cost. According to experiments, it is approximated that 25% of the ME can be eliminated.

POSTER: MDS-1488 Allogeneic Stem Cell Transplant with Myeloablative Fractionated Busulfan- Fludarabine- and Thiotepa-Conditioning Regimen in Older Patients With High-Risk MDS

Power Systems as Dynamic Networks

The theory of power systems dynamics has been developed largely from detailed studies of the dynamics of simple system structures with emphasis on the effects of modeling details of the dynamics. In contrast, the recent study in the science of complex networks, motivated by numerous real-world examples in various areas including power systems, employs rather simple dynamics and yet places much more emphasis on network structures. It appears that the two approaches can usefully inform each other for further progress into an integrated study of very large (or massive) systems as well as very complex dynamics. This paper reviews recent progress in these areas and suggests fruitful lines of future research.