Publications

Improved known-plaintext attack to permutation-only multimedia ciphers

Permutation is a commonly used operation in many secure multimedia systems. However, it is fragile against cryptanalysis when used alone. For instance, it is well-known that permutation-only multimedia encryption is insecure against known-plaintext attack (KPA). There exist algorithms that are able to (partially) retrieve the secret permutation sequences in polynomial time with logarithmic amount of plaintexts in the number of elements to be permuted. But existing works fail to answer how many known plaintexts are needed to fully recover a underlying secret permutation sequence and how to balance the storage cost and computational complexity in implementing the KPA attack. This paper addresses these two problems. With a new concept of composite representation, the underlying theoretical rules governing the KPA attack on a permutation-only cipher are revealed, and some attractive algorithms outperforming the state-of-the-art methods in terms of computational complexity are developed. As a case study, experiments are performed on permutation-only image encryption to verify the theoretic analysis. The performance gap of the proposed KPA between artificial noise-like images, which perfectly fits the theoretical model, and the corresponding natural images is identified and analyzed. Finally, experimental results are shown to demonstrate the efficiency improvement of the new schemes over the existing ones.

Designing Protograph-Based LDPC Codes for Iterative Receivers on ${M}$ -ary DCSK Systems

In this brief, protograph-based low density parity check (P-LDPC) codes, which have simple structure and excellent error-correction capability, are designed for iterative receivers (IRs) on M-ary differential chaos shift keying (M-ary DCSK) systems. Due to the non-periodic and random characteristics of chaos carriers and their interaction with soft information, the conventional optimal P-LDPC codes over Bi-AWGN channels in the tandem mode may not perform well in M-ary DCSK systems with IR. With the help of a finite-length extrinsic information transfer (EXIT) algorithm, the convergence of IR is analyzed, by which a new design principle is proposed to construct new P-LDPC codes for the M-ary DCSK systems. Both EXIT analysis and simulated results demonstrate the superiority of the proposed P-LDPC codes.

Sampled-data chaos synchronization via fuzzy observer design

In this paper, a methodology for the synchronization of two chaotic systems by means of a sampled driving signal is presented. The method is based on the fuzzy Takagi-Sugeno representation of the chaotic system, from which a continuous-time fuzzy observer is designed as the solution of an LMI problem. Then, via the dual-system, the fuzzy observer is digitally redesigned such that the performance is maintained for the sampled system. Numerical simulations of Chua's circuit are used to illustrate the effectiveness of the proposed synchronization methodology.

A stochastic SEIHR model for COVID-19 data fluctuations

Although deterministic compartmental models are useful for predicting the general trend of a disease's spread, they are unable to describe the random daily fluctuations in the number of new infections and hospitalizations, which is crucial in determining the necessary healthcare capacity for a specified level of risk. In this paper, we propose a stochastic SEIHR (sSEIHR) model to describe such random fluctuations and provide sufficient conditions for stochastic stability of the disease-free equilibrium, based on the basic reproduction number that we estimated. Our extensive numerical results demonstrate strong threshold behavior near the estimated basic reproduction number, suggesting that the necessary conditions for stochastic stability are close to the sufficient conditions derived. Furthermore, we found that increasing the noise level slightly reduces the final proportion of infected individuals. In addition, we analyze COVID-19 data from various regions worldwide and demonstrate that by changing only a few parameter values, our sSEIHR model can accurately describe both the general trend and the random fluctuations in the number of daily new cases in each region, allowing governments and hospitals to make more accurate caseload predictions using fewer compartments and parameters than other comparable stochastic compartmental models.

CONTROLLING CHUA'S CIRCUIT

The unified canonical feedback control strategy developed recently by the present authors for controlling chaotic systems is refined and applied to the well-known Chua's circuit, driving its orbits from the chaotic attractor to its unstable limit cycle. Simple sufficient conditions for the controllability of this particular circuit are established. Simulation results are included to visualize the control process. A circuit implementation of the designed feedback control is realized by adding a linear resistor and an appropriate periodic-signal generator to the original circuit.

Nonlinear TiC nanosheets for MIR Q-switched laser in Er:GYAP cavity

Stochastic link activation for distributed filtering under sensor power constraint

We consider the problem of link activation for distributed estimation with power constraint. To satisfy the requirement of power consumption, we propose a stochastic link activation scheme, where each sensor equipped with a distributed estimator sends data to its neighboring sensors according to different probabilities. First, we design the optimal estimator gain of each sensor to minimize the state estimation error covariance. Then, we find an upper bound of the expected state estimation error covariance and provide a sufficient condition to guarantee the stability of the proposed estimator. Finally, we formulate the link activation problem as an optimization problem, and convert it to a convex optimization.

Controlling Complex Dynamical Networks

No abstract is provided for this article.

Synchronization of multi-agent systems with metric-topological interactions

A hybrid multi-agent systems model integrating the advantages of both metric interaction and topological interaction rules, called the metric-topological model, is developed. This model describes planar motions of mobile agents, where each agent can interact with all the agents within a circle of a constant radius, and can furthermore interact with some distant agents to reach a pre-assigned number of neighbors, if needed. Some sufficient conditions imposed only on system parameters and agent initial states are presented, which ensure achieving synchronization of the whole group of agents. It reveals the intrinsic relationships among the interaction range, the speed, the initial heading, and the density of the group. Moreover, robustness against variations of interaction range, density, and speed are investigated by comparing the motion patterns and performances of the hybrid metric-topological interaction model with the conventional metric-only and topological-only interaction models. Practically in all cases, the hybrid metric-topological interaction model has the best performance in the sense of achieving highest frequency of synchronization, fastest convergent rate, and smallest heading difference.

Simultaneous Source Localization and Formation via a Distributed Sign Gradient-Free Algorithm

This article develops a distributed sign gradient-free algorithm for simultaneous source localization and formation of a multirobot system. A distinguished feature of the algorithm is that it takes into account robots' measure noise as well as ternary communication, which significantly reduces the communication cost of the overall network. Considering the presence of noise, the algorithm is designed to be gradient-free. In addition, an inherent connection is established between the selection of control parameters and the convergence property of the sign gradient-free algorithm, as well as signal strength, noisy intensity, formation radius, and the number of informed robots.

Integrated Multiomics Reveals Silencing of has_circ_0006646 Promotes TRIM21‐Mediated NCL Ubiquitination to Inhibit Hepatocellular Carcinoma Metastasis

Recent studies suggest that circular RNA (circRNA)‐mediated post‐translational modification of RNA‐binding proteins (RBP) plays a pivotal role in metastasis of hepatocellular carcinoma (HCC). However, the specific mechanism and potential clinical therapeutic significance remain vague. This study attempts to profile the regulatory networks of circRNA and RBP using a multi‐omics approach. Has_circ_0006646 (circ0006646) is an unreported circRNA in HCC and is associated with a poor prognosis. Silencing of circ0006646 significantly hinders metastasis in vivo. Mechanistically, circ0006646 prevents the interaction between nucleolin (NCL) and the E3 ligase tripartite motif‐containing 21 to reduce the proteasome‐mediated degradation of NCL via K48‐linked polyubiquitylation. Furthermore, the change of NCL expression is proven to affect the phosphorylation levels of multiple proteins and inhibit p53 translation. Moreover, patient‐derived tumor xenograft and lentivirus injection, which is conducted to simulate clinical treatment confirmed the potential therapeutic value. Overall, this study describes the integrated multi‐omics landscape of circRNA‐mediated NCL ubiquitination degradation in HCC metastasis and provides a novel therapeutic target.

Simplicial networks: a powerful tool for characterizing higher-order interactions

No abstract is provided for this article.

Modeling, analysis and control of networked autonomous agents

No abstract is provided for this article.

Oscillations of nonlinear partial difference systems

This paper studies the following two-dimensional nonlinear partial difference systems T(∇1,∇2)(xmn)+bmng(ymn)=0, T(Δ1,Δ2)(ymn)+amnf(xmn)=0, where m,n∈N 0={0,1,2,…}, T(Δ 1,Δ 2)=Δ 1+Δ 2+I, T(∇1,∇2)=∇1+∇2+I, Δ 1 y mn =y m+1,n −y mn , Δ 2 y mn =y m,n+1−y mn , Iy mn =y mn , ∇1 y mn =y m−1,n −y mn , ∇2 y mn =y m,n−1−y mn , {a mn } and {b mn } are real sequences, m,n∈N 0, and f,g:R→R are continuous with uf(u)>0 and ug(u)>0 for all u≠0. A solution ({x mn },{y mn }) of the system is oscillatory if both components are oscillatory. Some sufficient conditions for all solutions of this system to be oscillatory are derived.

Second-Order Consensus for Multiagent Systems With Directed Topologies and Nonlinear Dynamics

This paper considers a second-order consensus problem for multiagent systems with nonlinear dynamics and directed topologies where each agent is governed by both position and velocity consensus terms with a time-varying asymptotic velocity. To describe the system's ability for reaching consensus, a new concept about the generalized algebraic connectivity is defined for strongly connected networks and then extended to the strongly connected components of the directed network containing a spanning tree. Some sufficient conditions are derived for reaching second-order consensus in multiagent systems with nonlinear dynamics based on algebraic graph theory, matrix theory, and Lyapunov control approach. Finally, simulation examples are given to verify the theoretical analysis.

Distributed Control and Estimation of Networked Agent Systems

1 Department of Mathematics, Southeast University, Nanjing 210096, China 2 Faculty of Mathematics and Natural Sciences, ITM, University of Groningen, 9747 AG Groningen, The Netherlands 3 Department of Electronic Engineering, City University of Hong Kong, Hong Kong 4 School of Engineering and Information Technology, The University of New South Wales at ADFA, Canberra, ACT 2600, Australia 5 School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC 3001, Australia

Controlling degenerate Hopf bifurcations

No abstract is provided for this article.

Network Centrality and Key Economic Indicators: A Case Study

No abstract is provided for this article.