Stability analysis of systems with two additive time-varying delay components via an improved delay interconnection Lyapunov–Krasovskii functional

This paper is concerned with the stability analysis of systems with two additive time-varying delay components in an improved delay interconnection Lyapunov–Krasovskii framework. At first, an augmented vector and some integral terms considering the additive delays information in a new way are introduced to the Lyapunov–Krasovskii functional (LKF), in which the information of the two upper bounds and the relationship between the two upper bounds and the upper bound of the total delay are both fully considered. Then, the obtained stability criterion shows advantage over the existing ones since not only an improved delay interconnection LKF is constructed but also some advanced techniques such as the free-matrix-based integral inequality and extended reciprocally convex matrix inequality are used to estimate the upper bound of the derivative of the proposed LKF. Finally, a numerical example is given to demonstrate the effectiveness and to show the superiority of the proposed method over existing results.     

Distributed reconstruction of time-varying graph signals via a modified Newton’s method

This paper develops a distributed reconstruction algorithm, that can be implemented efficiently, for time-varying graph signals. The reconstruction problem is formulated as an unconstrained optimization problem that minimizes the weighted sum of the data fidelity term and the regularization term. The regularizer used is the nonsmoothness measure of the temporal difference signal. The classical Newton’s method can be used to solve the optimization problem. However, computation of the Hessian matrix inverse is required, and this does not scale well with the graph size. Furthermore, a distributed implementation is not possible. An approximation to the inverse Hessian, that exploits the graph topology, is developed here. The resulting iterative algorithm can be implemented in a distributed manner, and scales well with the graph size. Convergence analysis of the algorithm is presented, which shows convergence to the global optimum. Numerical results, using both synthetic and real world datasets, will demonstrate the superiority of the proposed reconstruction algorithm over existing methods.     

Quadratically convex combination approach to stability of T–S fuzzy systems with time-varying delay

This paper develops a novel stability analysis method for Takagi–Sugeno (T–S) fuzzy systems with time-varying delay. New delay-dependent stability criteria in terms of linear matrix inequalities for time-varying delayed T–S fuzzy systems are derived by the newly proposed augmented Lyapunov–Krasovski (L–K) functional. This functional contains the cross terms of variables and quadratic terms multiplied by a higher degree scalar function. Different from previous results, our derivation applies the idea of second-order convex combination, and the property of quadratic convex function without resorting to the Jensen's inequality. Two numerical examples are provided to verify the effectiveness of the presented results.     

Stability analysis of continuous-time systems with time-varying delay using new Lyapunov–Krasovskii functionals

This paper studies the stability of linear continuous-time systems with time-varying delay by employing new Lyapunov–Krasovskii functionals. Based on the new Lyapunov–Krasovskii functionals, more relaxed stability criteria are obtained. Firstly, in order to coordinate with the use of the third-order Bessel-Legendre inequality, a proper quadratic functional is constructed. Secondly, two couples of integral terms $\{{\int }_{t?h_t}^{s}x\left(s\right)ds,{\int }_s^{t}x\left(s\right)ds\}$ and $\{{\int }_{t?h_M}^{s}x\left(s\right)ds,{\int }_s^{t?h_t}x\left(s\right)ds\}$ are involved in the integral functionals ${\int }_{t?h_t}^t(·)ds$ and ${\int }_{t?h_M}^{t?h_t}(·)ds,$ respectively, so that the coupling information between them can be fully utilized. Finally, two commonly-used numerical examples are given to demonstrate the effectiveness of the proposed method.     

Novel delay-partitioning approaches to stability analysis for uncertain Lur’e systems with time-varying delays

This work deals with the problem of absolute stability analysis for a class of uncertain Lur’e systems with time-varying delays. Novel delay-partitioning approaches are presented, which are dividing the variation interval of the delay into three subintervals. Some new augment Lyapunov–Krasovskii functionals (LKFs) are defined on each of the obtained subintervals which can efficiently make use of the information of the delay and relate to the reciprocally convex combination technique and the Wirtinger-based integral inequality method. Several improved delay-dependent criteria are derived in terms of the linear matrix inequalities (LMIs). The merit of the proposed criteria lies in their less conservativeness and lower numerical complexity than relative literature. Two numerical examples are included to illustrate the effectiveness and the improvement of the proposed method.     

Master-slave synchronization for time-varying delay chaotic Lur’e systems based on the integral-term-related free-weighting-matrices technique

In this paper, the master-slave synchronization of the chaotic Lur’e system (MSSCLS) with time-varying delay is investigated. At first, a Lyapunov-Krasovskii functional (LKF) with nonlinear terms and time-varying delay is constructed. Secondly, when the derivative of LKF is estimated, the improved stability criterion is obtained by considering the relationship between the integral terms generated after using the Bessel-Legendre inequality (BLI) and introducing the integral-term-related free-weighting-matrices. Finally, case studies based on Chua’s circuit are carried out to test and verify the effectiveness of the proposed synchronization criterion, and the results are compared with the latest methods to show the advantages of the proposed synchronization criterion.     

Global mean square exponential stability and stabilization of uncertain switched delay systems with Lévy noise and flexible switching signals

This paper focuses on the stability analysis and stabilization problem for a class of uncertain switched delay systems with Lévy noise and flexible switching signals which unify the high-frequency switching and low-frequency switching. By employing the theory of switched systems, mathematical induction and stochastic analysis technique, some sufficient conditions in form of algebraic inequalities are derived to guarantee the stability and stabilization of such systems. Different from dwell time and average dwell time, the proposed switching rule constrained the partial dwell-time shows that the switching number in the same time interval can be more elastic. Finally, numerical examples are implemented to illustrate the effectiveness of the theoretical results.     

Hierarchical type stability and stabilization of networked control systems with event-triggered mechanism via canonical Bessel–Legendre inequalities

This paper is studied with the hierarchical type stability and stabilization of networked control systems (NCSs) with event-triggered mechanism (ETM). In the cause of reducing the amount of data transmission and saving the limited network bandwidth, ETM is introduced into NCSs, and the closed-loop time-delay NCSs model with ETM is presented. An improved Lyapunov–Krasovskii functional (LKF), containing delay-product-type terms and being appropriate for the canonical BesselLegendre inequality (BLI), is first constructed. Then, by utilizing the canonical BLI and the extended reciprocally convex matrix inequality (ERCMI) to deal with the single integral terms of the derivative of LKF, a sufficient condition on asymptotically stable is derived for NCSs. Based on above N-dependent stability criteria, a co-design method is developed, which can be capable of calculating the control gain of controller and the weighting matrix of the ETM. Finally, the feasibility and superiority of the results are verified by two examples.     

Customer’s role in knowledge management and in the innovation process: effects on innovation capacity and marketing results

Scholars have acknowledged customer knowledge management (CKM) as a key strategic resource for improving innovation and supporting long-term customer relationship management. This study provides a deeper understanding of the internal antecedents of business innovation capacity overcoming previous approaches. A model that had not previously been tested was used to analyse the role of customer collaboration and CKM – measured as a second-order construct – in innovation processes and marketing results. To test the model, structural equation modelling (partial least squares) was applied to a random sample of 210 Spanish companies. Results confirm that CKM and customer collaboration are antecedents of innovation capacity and marketing results. Furthermore, the effect of CKM is greater than the effect of customer collaboration. This paper provides a basis for managers to encourage innovation in their companies and explains how managers can improve marketing results.     

Stabilization of highly nonlinear hybrid systems driven by Lévy noise and delay feedback control based on discrete-time state observations

There are many hybrid stochastic differential equations (SDEs) in the real-world that don’t satisfy the linear growth condition (namely, SDEs are highly nonlinear), but they have highly nonlinear characteristics. Based on some existing results, the main difficulties here are to deal with those equations if they are driven by Lévy noise and delay terms, then to investigate their stability in this case. The present paper aims to show how to stabilize a given unstable nonlinear hybrid SDEs with Lévy noise by designing delay feedback controls in the both drift and diffusion parts of the given SDEs. The controllers are based on discrete-time state observations which are more realistic and make the cost less in practice. By using the Lyapunov functional method under a set of appropriate assumptions, stability results of the controlled hybrid SDEs are discussed in the sense of pth moment asymptotic stability and exponential stability. As an application, an illustrative example is provided to show the feasibility of our theorem. The results obtained in this paper can be considered as an extension of some conclusions in the stabilization theory.     

Understanding the impact of digital service failure on users: Integrating Tan’s failure and DeLone and McLean’s success model

Although information systems (IS) success has been given much attention in IS literature, failure has received lesser attention. This study empirically validates a model of digital service failure for consumers by integrating three dimensions from Tan’s failure model and one dimension from DeLone and Mclean’s Information Success model. The factors have been mapped to Expectation Disconfirmation Theory (EDT). Experiential survey approach has been used to collect primary data from information systems users who have experienced digital service failure. Structural equation modeling (SEM) has been used for model testing and validation to measure the impact of information, system, functional and service failure of digital service on end users. The findings suggests that information, functional, system and service failure has an impact on the consumers through the outcome, process, cost and user satisfaction of digital services.     

The interaction effects of online reviews and free samples on consumers’ downloads: An empirical analysis

Consumers’ software purchase decisions are influenced both by online reviews and by their experiences with free samples provided by firms. This paper empirically investigates the differential effects of online reviews (user and editor ratings) on consumers’ sample downloading behavior, using a dataset drawn from a large software free sampling website CNET.com. Our findings extend the previous research by suggesting that information disclosure levels of free samples (indicated by licenses) moderates the impacts of online reviews on consumers’ sample downloads. For samples that disclose a great level of information, higher user ratings can increase downloads; otherwise, higher user ratings fail to increase downloads. When both user and editor ratings are available to consumers, only user ratings can increase sample downloads. The findings can be explained by consumers’ two-stage information process whereby consumers first refer to online reviews and then determine whether to sample software. This study provides practical implications on the design of information disclosure channel and offers suggestions for firms regarding how to select and apply sample licenses.     

Political uncertainty and innovation: The relative effects of national leaders’ education levels and regime systems on firm-level patent applications

We explore the effect of political uncertainty on innovation. In particular, we examine the differential effects of two sources of uncertainty – leaders’ education levels and political regimes (i.e., presidential vs. parliamentary) – on patent applications. We posit that firms react to political uncertainty caused by the unexpected departure of a national leader by investing in patents as growth options. The empirical design analyzes a panel with information from over 62 million patent applications at the aggregated applicant level. Results show that leaders’ unexpected departures cause, on average, increases of approximately 9% in the aggregate growth of patent applications. We also find that the leader’s level of education and the country’s political regime system have significant effects on the relationship between political uncertainty and innovation. The difference between leaders with high and low levels of education accounts for 21% of the change in the growth of patent applications. Further, the effect of political uncertainty on innovation is amplified in presidential systems, which grant leaders more power and make electoral transitions less predictable. The differences between presidential and parliamentary systems account for approximately 16% of the change in the growth of patent applications. As a robustness check, we utilized a subsample of more than 170,000 firms with local and foreign patent applications, as well as a panel of over 5700 government non-profits, universities, and hospitals with local patent applications. Consistent with our theory, the former react to political uncertainty by investing in patents, while the latter remain unaffected. We contribute by showing the theoretical mechanisms linking leader and regime characteristics with patent applications.     

Game mechanics and technological mediation: an ethical perspective on the effects of MMORPG’s

In the past decades, video games have grown from a niche market to one of the major entertainment media, enticing millions of players worldwide. When ethical aspects of video games are being debated, the discussion oftentimes revolves around effects of their content, such as violence. This paper argues that effects of game mechanics, such as reward mechanisms, should be considered as well, as these are at the core of the appeal of games. We analyze the ethical dimension of behavioral game design present in Massively Multiplayer Online Role Playing Games (MMORPG’s). Using the framework of technological mediation, we show how opaque and seductive game mechanics can invite problematic usage patterns, such as excessive use with negative effects on well-being, and how designers can take responsibility for morally acceptable impact of their games. Having a practical focus, the paper concludes with several proposals for better design.     

Effects of members’ response styles in an online depression community based on text mining and empirical analysis

The online depression community (ODC) has become a popular resource for people with depression to manage their mental health during the COVID-19 pandemic. This study proposed a novel perspective based on response style theory to investigate whether depression individuals’ distractive and ruminative behaviors in ODC were related to social support received and co-rumination. Furthermore, we explored the influences of social support and co-rumination on suicidal behaviors using panel data set. We collected text data from 22,286 depressed users of a large ODC in China from March 2020 to July 2021, and conducted text mining and econometrics analyses to test our research questions. The results showed that depression users’ online ruminative behaviors had a positive relationship with the co-rumination and had a negative relationship with social support received. Besides, constructive distractive behaviors (i.e., providing social support to others) increased the support users received from others but had a negative relationship with co-rumination. Depression users' future suicidal behaviors are influenced by past received social support and co-rumination. The received social supports and co-rumination have a negative and positive influence on depression users' future suicidal behaviors, respectively. Our results enrich the application of response style theory in online medicine. They provide meaningful insights into behaviors that influence the acquisition of online social support and the incidence of online co-rumination in ODCs. This study helps relevant institutions to conduct more targeted online suicide interventions for depression patients.     

Synchronized stationary distribution of hybrid stochastic coupled systems with applications to coupled oscillators and a Chua’s circuits network

In this paper, the existence of synchronized stationary distribution for hybrid stochastic coupled systems (HSCSs) (here, also known as stochastic coupled systems with Markovian switching) is concerned. By the existence theory of stationary distribution as well as Lyapunov method and graph theory, two kinds of sufficient criteria are presented to promise the existence of synchronized stationary distribution for HSCSs. Our results exhibit that the existence region of synchronized stationary distribution has a close relationship with the intensity of stochastic perturbation. And when stochastic perturbation vanishes, synchronized stationary distribution will become complete synchronization. Then the proposed theoretical results are successfully applied to stochastic coupled oscillators and a Chua’s circuits network. Some existence criteria of synchronized stationary distribution are also obtained. The corresponding numerical simulations are carried out to verify the validity of the theoretical results.