On Delay-dependent and Delay-derivative-dependent Stability and Stabilization for Lur’e Systems with Slowvarying Delay

This note is concerned with the absolutestability for time-varying delay Lur’e system withsector-bounded nonlinearity. Improved delay-dependentand delay-derivative-dependent stability criteria areobtained in the form of linear matrix inequalities (LMIs)by constructing a modified augmented Lyapunov-Krasovskii (LK) functional without applying the modeltransformation or the bounding techniques for crossterms. Thus, the presented delay-dependent criteria areless conservative than those in the literature. Moreover,state feedback stabilizing controllers based on theproposed stability criteria are designed. Numericalexample demonstrates the effectiveness and superiorityof the proposed method.

Robust networked H_∞ synchronization of nonidentical chaotic Lur'e systems

We mainly investigate the robust networked H~ synchronization problem of nonidentical chaotic Lur＇e systems. In the design of the synchronization scheme, some network characteristics, such as nonuniform sampling, transmission- induced delays, and data packet dropouts, are considered. The parameters of master-slave chaotic Lur＇e systems often allow differences. The sufficient condition in terms of linear matrix inequality （LMI） is obtained to guarantee the dissipative synchronization of nonidentical chaotic Lur＇e systems in network environments. A numerical example is given to illustrate the validity of the proposed method.

Adaptive input-to-state stable synchronization for uncertain time-delay Lur’e systems

This paper is dedicated to the study of adaptive input-to-state stable synchronization of uncertain time-delay Lur’e systems with exterior interference. With the help of the Lyapunov function approach, a sufficient condition for the input-to-state stability of the synchronization-error system is derived, which is theoretically less conservative than a previously reported criterion in the absence of parameter uncertainties. On the basis of the present condition, a co-design of the feedback gain and estimates of the uncertain parameters is given to determine the desired adaptive synchronization controller. Finally, an example with simulations is provided to demonstrate the applicability and superiority of the analysis and design strategies.

Delay-Dependent Absolute Stability ofUncertain Lur′e Systems with Time-Delays^1）

This paper is concerned with delay dependent absolute stability for a class of uncertain Lur′e systems with multiple time-delays. By using a descriptor model transformation of the sys-tem and by applying a recent result on bounding of cross products of vectors, a new type of Lya-punov-Krasovskii functional is constructed. Based on the new functional, delay-dependent suffi-cient conditions for absolute stability are derived in terms of linear matrix inequalities. These con-ditions do not require any parameter tuning, and can be solved numerically using the software LMI Lab. A numerical example is presented which shows that the proposed method can substantiallyimprove the delay bound for absolute stability of Lur′e system with time-delays, compared to theexisting ones.

Exponential synchronization of chaotic Lur'e systems with time-varying delay via sampled-data control

In this paper, we study the exponential synchronization of chaotic Lur＇e systems with time-varying delays via sampled-data control by using sector nonlinearties. In order to make full use of information about sampling intervals and interval time-varying delays, new Lyapunov-Krasovskii functionals with triple integral terms are introduced. Based on the convex combination technique, two kinds of synchronization criteria are derived in terms of linear matrix inequal- ities, which can be efficiently solved via standard numerical software. Finally, three numerical examples are provided to demonstrate the less conservatism and effectiveness of the proposed results.

Some new criteria for lag synchronization of chaotic Lur'e systems by replacing variables control

Some new criteria for the chaotic lag synchronization are proposed. At first,lag synchronization scheme for identical master-slave Lur‘ e systems by replacing variables control and the relevant error system are given, and the relations between absolute stability of the error system and the chaotic lag synchronization are described. Then, based on a quadratic Lyapunov function, two new Lur‘ e criteria for the above chaotic lag synchronization are proved. Four corresponding frequency domain criteria are further derived by means of Meyer-Kalman-Yacubovia Lemma. These frequency domain criteria are applied to analyze the lag synchronization of general master-slave Chua's circuits so that some ranges of the parameters in which the master-slave Chua's circuits achieve chaotic lag synchronization by replacing single-variable control are attained. Finally, some examples are given to verify the theoretical results.

On absolute stability of Lur'e control systems with multiple non-linearities using linear matrix inequalities

Necessary and suffcient conditions for the existence of a Lyapunov function in the Lur ’ e form to guarantee the absolute stability of Lur’ e control systems with multiple non-linearities are discussed in this paper. It simplifies the existence problem to one of solving a set of linear matrix inequalities (LMIs). If those LMIs are feasible, free parameters in the Lyapunov function, such as the positive definite matrix and the coefficients of the integral terms, are given by the solution of the LMIs. Otherwise, this Lyapunov function does not exist. Some sufficient conditions are also obtained for the robust absolute stability of uncertain systems. A numerical example is provided to demonstrate the effectiveness of the proposed method.

Synchronization of chaotic Lur'e systems with delayed feedback control using deadzone nonlinearity

In this paper we present a synchronization method for chaotic Lur＇e systems by constructing a new piecewise Lyapunov function. Using a delayed feedback control scheme, a delay-dependent stability criterion is derived for the synchronization of chaotic systems that are represented by Lur＇e systems with deadzone nonlinearity. Based on the Lyapunov-Krasovskii functional and by using some properties of the nonlinearity, a new delay-dependent stabilization condition for synchronization is obtained via linear matrix inequality （LMI） formulation. The criterion is less conservative than existing ones, and it will be verified through a numerical example.

Exponential synchronization of stochastic impulsive perturbed chaotic Lur'e systems with time-varying delay and parametric uncertainty

This paper is devoted to investigating the scheme of exponential synchronization for uncertain stochastic impulsive perturbed chaotic Lur＇e systems. The parametric uncertainty is assumed to be norm bounded. Based on the Lyapunov function method, time-varying delay feedback control technique and a modified Halanay inequality for stochastic differential equations, several sufficient conditions are presented to guarantee the exponential synchronization in mean square between two identical uncertain chaotic Lur＇e systems with stochastic and impulsive perturbations. These conditions are expressed in terms of linear matrix inequalities （LMIs）, which can easily be checked by utilizing the numerically efficient Matlab LMI toolbox. It is worth pointing out that the approach developed in this paper can provide a more general framework for the synchronization of multi-perturbation chaotic Lur＇e systems, which reflects a more realistic dynamics. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed method.

Synchronization of general discrete Lur'e systems

This paper studies a master-slave type of synchronization systems for a general form of two discrete Lur＇e systems. Some simple necessary and/or sufficient conditions for synchronization are derived. They are basically algebraic conditions, and are convement to be applied in engineering applications.

一类具有变脉冲时滞的Lur’e网络的同步问题

研究了具有非线性耦合的脉冲时滞Lur’e网络的同步问题.借助于极限意义下的平均脉冲区间和平均脉冲时滞的技巧,得到了关于脉冲时滞Lur’e网络在平均脉冲区间T_(a)<∞和T_(a)=∞情形下全局指数同步的某些充分条件.

随机Lur’e时滞网络的指数同步与脉冲控制

本文研究了一类具有不对称耦合和时变时滞随机Lur’e动态网络的全局指数同步问题.为了使网络中的所有Lur’e系统达到同步,文章提出了一种实用的脉冲控制策略,利用平均脉冲间隔概念、Perron-Frobenius定理、比较原理、参数变分法和无参照系统策略,给出了保证网络实现全局指数同步的充分条件.基于脉冲信号既能促进网络群聚行为同时也可能阻碍网络同步这一事实,本文分别讨论了积极脉冲效应和消极脉冲效应作用下网络实现同步的判定方法,同时给出了不同脉冲效应作用下网络的收敛速度.提供了数值仿真证明主要结果和控制策略的有效性.

时滞Lur’e网络的事件触发脉冲自适应同步控制

本文研究了一类带有混合时变时滞Lur’e网络的全局同步及其脉冲自适应控制问题.首先,为实现网络的全局指数同步并有效避免控制器连续控制,设计了一类基于事件触发的脉冲反馈控制器.同时,为获得最优控制强度,针对反馈控制输入设计了一种自适应更新定律并实现脉冲控制与反馈控制的动态平衡.其次,基于推广的比较原理以及参数变分策略,提出了该控制策略下的Lur’e网络实现全局指数同步的充分判定条件,并精确给出了指数同步的收敛速度.最后,通过相应的仿真算例来验证本文提出的控制方案和理论分析的正确性和有效性.

基于采样控制的时滞Lur’e系统的渐近同步分析

本研究探讨了基于采样数据控制的时滞Lur’e系统的全局渐近同步问题。首先构建了时滞主从系统的模型,并设计了相应的采样控制器。接着,通过构造新的李雅普诺夫函数并结合稳定性理论,再利用不等式性质及时滞分解技术,推导出了时滞Lur’e系统渐近同步的新判据,并以矩阵不等式形式加以表述。最后,利用数值模拟来验证了所得结果的有效性与实用性。

Analysing chaos in fractional-order systems with the harmonic balance method

In this paper, the fractional-order Genesio-Tesi system showing chaotic behaviours is introduced, and the corresponding one in an integer-order form is studied intensively. Based on the harmonic balance principle, which is widely used in the frequency analysis of nonlinear control systems, a theoretical approach is used to investigate the conditions of system parameters under which this fractional-order system can give rise to a chaotic attractor. Finally, the numerical simulation is used to verify the validity of the theoretical results.

Does Smoking Weaken the Immune System: A Narrative Review

Smoking has a complex impact on the immune system, affecting both innate and adaptive immunity. It can exacerbate pathogenic immune responses and attenuate defensive immunity, leading to a higher susceptibility to infections and certain diseases. The chemicals in cigarette smoke, such as nicotine and carbon monoxide, can alter immune cell functions and inflammatory responses. Smoking can also have long-term effects on the immune system, with some changes persisting even after quitting [1]. According to a Penn Medicine Physician, the Medical Oncologist Dr. David Porter, “People who are smokers tend to get sicker from infections”, “It may be that smoking impacts the immune system’s ability to respond appropriately”. Thus, such individuals within smoking exposure history might be considered as immunocompromised due to the altered and weakened immune system. Cigarette smoking is a prevalent habit with far-reaching health implications. Among its many adverse effects, smoking significantly alters the immune system’s functionality [1].

Novel antigen delivery systems

Vaccines represent the most relevant contribution of immunology to human health. However, despite the remarkable success achieved in the past years, many vaccines are still missing in order to fight important human pathologies and to prevent emerging and re-emerging diseases. For these pathogens the known strategies formaking vaccines have been unsuccessful and thus, new avenues should be investigated to overcome the failure of clinical trials and other important issues including safety concerns related to live vaccines or viral vectors, the weak immunogenicity of subunit vaccines and side effects associated with the use of adjuvants. A major hurdle of developing successful and effective vaccines is to design antigen delivery systems in such a way that optimizes antigen presentation and induces broad protective immune responses. Recent advances in vector delivery technologies, immunology, vaccinology and system biology, have led to a deeper understanding of the molecular and cellular mechanisms by which vaccines should stimulate both arms of the adaptive immune responses, offering new strategies of vaccinations. This review is an update of current strategies with respect to live attenuated and inactivated vaccines, DNA vaccines, viral vectors, lipid-based carrier systems such as liposomes and virosomes as well as polymeric nanoparticle vaccines and virus-like particles. In addition, this article will describe our work on a versatile and immunogenic delivery system which we have studied in the past decade and which is derived from a nonpathogenic prokaryotic organism: the "E2 scaffold" of the pyruvate dehydrogenase complex from Geobacillus stearothermophilus.

Adaptation in Stochastic Dynamic Systems—Survey and New Results IV: Seeking Minimum of API in Parameters of Data

This paper investigates the problem of seeking minimum of API (Auxiliary Performance Index) in parameters of Data Model instead of parameters of Adaptive Filter in order to avoid the phenomenon of over parameterization. This problem was stated by Semushin in [2]. The solution to the problem can be considered as the development of API approach to parameter identification in stochastic dynamic systems.

System Assimilation of E-Skills in Tertiary Institutions to Empower Graduates in South Africa

The value of system assimilation is to improve working relationships between tutors and learners while increasing workflow efficiency among tertiary institutions with low operational costs. E-skills could be described as electronic education development, to assist ICT professionals to reach their future career goals and aim to help users boost their ICT skills. In a society that is expanding, it is also a crucial issue to take into account. Researchers have turned their attention to this topic because of its significance and contribution to the empowerment of graduates in digital education. Many scholars have proposed many methods for integrating e-skills into society with impressive results, but the rising rate of graduate unemployment in South Africa is gradually becoming a big worry in our society. A model based on Activity Theory (AT) and e-skills will be developed in our tertiary institution to equip graduates with skills that will increase their employability and provide more individualized work opportunities as part of this study’s effort to solve this issue. With the use of the Statistical Package for the Social Sciences (SPSS) and Cronbach’s Alpha for validity and reliability testing, the study will create an experimental performance to assess the approach taken to measure e-skills in tertiary institutions to empower graduates in South Africa. The study established that system development and e-skilled models for tertiary institutions are growing gradually, especially in South African institutions, that empower graduates with profitable employability with experiences to improve work operation in the industries. In conclusion, system development and e-skills are very demanding but important to empower graduate employability to determine competency in the professional workforce.

Security Vulnerability Analyses of Large Language Models (LLMs) through Extension of the Common Vulnerability Scoring System (CVSS) Framework

Large Language Models (LLMs) have revolutionized Generative Artificial Intelligence (GenAI) tasks, becoming an integral part of various applications in society, including text generation, translation, summarization, and more. However, their widespread usage emphasizes the critical need to enhance their security posture to ensure the integrity and reliability of their outputs and minimize harmful effects. Prompt injections and training data poisoning attacks are two of the most prominent vulnerabilities in LLMs, which could potentially lead to unpredictable and undesirable behaviors, such as biased outputs, misinformation propagation, and even malicious content generation. The Common Vulnerability Scoring System (CVSS) framework provides a standardized approach to capturing the principal characteristics of vulnerabilities, facilitating a deeper understanding of their severity within the security and AI communities. By extending the current CVSS framework, we generate scores for these vulnerabilities such that organizations can prioritize mitigation efforts, allocate resources effectively, and implement targeted security measures to defend against potential risks.