Stabilizing region of PDμ controller for fractional order system with general interval uncertainties and an interval delay

This paper concentrates on computing the stabilizing region of PD^μ controller for fractional order system with general interval uncertainties and an interval delay. The stabilizing region means the complete/approximate set of PD^μ controllers that stabilize the given closed-loop control system. General interval uncertainties refer to both coefficients and orders of the fractional system suffer from interval uncertainties. Interval delay indicates that the delay also vary in a specified interval.Firstly, a method is presented to calculate the stabilizing region for general interval fractional system with an interval time-constant delay. Based on a novel mapping function and the concept of critical controller parameters, the stabilizing region can be determined numerically. Secondly, the stabilizing region computation problem for general interval fractional system with an interval time-varyingdelay is considered. By applying a revised small-gain theorem, the stabilizing region can be calculated like the time-constant delay case. Thirdly, two alternative methods are proposed to improve the computational efficiency of stabilizing region calculation. Both methods can reduce the number of polynomials which are used to determine the stabilizing region. Examples are followed to illustrate the proposed results.     

On stability and stabilization of singular uncertain Takagi–Sugeno fuzzy systems

This paper deals with the problem of robust stability and robust stabilization for a class of continuous-time singular Takagi–Sugeno fuzzy systems. Sufficient conditions on stability and stabilization are proposed in terms of strict LMI (Linear Matrix Inequality) for uncertain T–S fuzzy models. In order to reduce the conservatism of results developed using quadratic method, an approach based on non-quadratic Lyapunov functions and S-procedure is proposed. Illustrative examples are given to show the effectiveness of the given 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.     

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.     

Finite-horizon H∞-consensus control for multi-agent systems with random parameters: The local condition case

This paper is concerned with the distributed H_∞-consensus control problem over the finite horizon for a class of discrete time-varying multi-agent systems with random parameters. First, by utilizing the proposed information matrix, a new formula is established to calculate the weighted covariance matrix of random matrix. Next, by allowing every agent to track the average of the neighbor agents, a novel local H_∞-consensus performance constraint is presented to cater to the local performance analysis. Then, by means of the proposed definition of the stochastic vector dissipativity-like over the finite horizon, a set of sufficient conditions for every agent is obtained such that the controlled outputs of the closed-loop multi-agent systems satisfy the proposed H_∞-consensus performance constraint. As a result, the proposed consensus control algorithm can be executed on each agent in an indeed distributed manner. Finally, a simulation example is employed to verify the effectiveness of the proposed algorithm.     

Sampled-data H∞ filtering of Takagi–Sugeno fuzzy systems with interval time-varying delays

The sampled-data _H∞$H_{\infty }$ filtering for a continuous-time Takagi–Sugeno fuzzy system with an interval time-varying state delay is investigated, where the measurement outputs from the plant to the filter are assumed to be sampled at discrete instants with a variable period. Firstly, by means of a newly proposed inequality bounding technique and a new Lyapunov–Krasovskii functional, the fuzzy sampled-data _H∞$H_{\infty }$ filtering performance analysis is carried out such that the resultant filter error system is asymptotically stable with a prescribed _H∞$H_{\infty }$ attenuation performance index. Secondly, sufficient conditions on the existence of fuzzy sampled-data _H∞$H_{\infty }$ filters are derived in the simultaneous presence of the time-varying state delay and the variable sampling period. The proposed bounding inequality lies in its more tightness and alleviates the enlargement of some inverse “coefficients” resulting from the utilization of the well-known Jensen integral inequality  . Compared with some existing Lyapunov–Krasovskii functionals, more information about the relationship among the current state and its delayed state is considered. The upper bound of the derivative of the time-varying state delay is not required to be less than one. Different from some existing results in the literature, by applying the proposed results, each different value of such an upper bound (greater than one) leads to a different _H∞$H_{\infty }$ disturbance attenuation level. Finally, a numerical example and a modified continuous stirred tank reactor system are given to show the effectiveness of the proposed results.     

The politics of research and innovation: Understanding instrument choices in complex governance environments – the case of France and Italy

What governments desire to achieve, and how they want to accomplish their goals, represent the core of any policy design process. However, it is still unclear how partisan politics, in its combined effect with path-dependency forces, influence policy makers’ choices over alternative instrument mixes. Through a comparative analysis of Research and Innovation (R&I) instrument choices in countries characterized by different paradigmatic models of policy (Italy and France), the paper investigates how the politics of different cabinets influence the formulation of national R&I strategies and the extent to which these decisions are constrained by the legacy of previous choices. By capitalizing on a new proposed treatment of policy instruments, the paper contributes to the definition of the types of tools found in policy mixes, investigating how national R&I instrument mix variations develop. The results of the analysis indicate how the selection of R&I policy instruments does not closely follow traditional left versus right-wing political cleavages, and their evolution is generally influenced by a combination of different context-dependent dynamics. However, when partisan acceptance of consolidated R&I instrument mixes across cabinets is present, this triggers a consolidating effect on path-dependency forces.     

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.     

Nb12+—niobespherene: a full-metal hollow-cage cluster with superatomic stability and resistance to CO attack

Why one chemical is more stable than another is not always easy to understand.A unified answer for metal clusters has led to the establishment of the superatom concept,which rationalizes the delocalization of electrons;however,cluster stability based on superatom theory has not been confirmed unambiguously for any metal other than the s-and p-blo cks of the periodic table of elements.Here,we have prepared pure niobium clusters and observed their reactions with CO under sufficient gas collision c...     

The destabilisation of existing regimes: Confronting a multi-dimensional framework with a case study of the British coal industry (1913–1967)

Because innovation studies are oriented towards novelty, scholars in this field have paid less attention to the destabilisation of existing regimes. This paper discusses four views on industry destabilisation and presents an encompassing conceptual framework, which addresses interactions between the build-up of external pressures, industry response strategies, and the gradual weakening of commitment to existing regime elements. We confront the framework with an in-depth longitudinal case study of the British coal industry (1913–1967). Specific conclusions are developed about different degrees of regime inertia, the ebb and flow of external pressures, the relative importance of economic and socio-political pressures, and interactions between them.     

The C:N:P stoichiometry in bryophytes: relationships with habitat,climate and growth formOA

<正>The elemental composition and stoichiometry of organisms provide a useful lens for explaining and predicting ecological paterns and processes. However, few studies have focused on stoichiometry in bryophytes, even though they are abundant in many pristine ecosystems. Several case studies found variable paterns in bryophyte stoichiometry(e.g. [1,2]).     

Mixed H∞ and passive control for a class of nonlinear switched systems with average dwell time via hybrid control approach

This paper investigates the mixed H_∞ and passive control problem for a class of nonlinear switched systems based on a hybrid control strategy. To solve this problem, firstly, using the Takagi–Sugeno (T–S) fuzzy model to approximate every nonlinear subsystem, the nonlinear switched systems are modeled as the switched T–S fuzzy systems. Secondly, the hybrid controllers are used to stabilize the switched T–S fuzzy systems. The hybrid controllers consist of dynamic output-feedback controllers for every subsystem and state updating controllers at the switching instant. Thirdly, a new performance index is proposed for switched systems. This new performance index can be viewed as the mixed weighted H_∞ and passivity performance. Based on this new performance index, the weighted H_∞ control problem and the passive control problem for switched T–S fuzzy systems via the hybrid control strategy are solved in a unified framework. Together the multiple Lyapunov functions (MLFs) approach with the average dwell time (ADT) technique, new design conditions for the hybrid controllers are obtained. Under these conditions, the closed-loop switched T–S fuzzy systems are globally uniformly asymptotically stable with a prescribed mixed H_∞ and passivity performance index. Moreover, the desired hybrid controllers can be constructed by solving a set of linear matrix inequalities (LMIs). Finally, the effectiveness of the obtained results is illustrated by a numerical example.     

“All for One and One for All?” - Knowledge broker roles in managing tensions of internal coopetition: The Ubisoft case

Coopetition, i.e., cooperation between competing actors, has become a pervasive strategy for innovative firms. The primary focus of studies investigating coopetition centers on inter-firm relationships, highlighting the benefits, limits and configurational patterns of cooperative relationships between competing firms. Only a small, emerging group of studies seeks to extend the concept to the intra-firm level, stressing the existence and effects of competition and cooperation between units that are part of the same organization. This paper contributes to this latter group by investigating the effects of internal coopetition on knowledge and innovation sharing and highlighting the fundamental role of knowledge brokers in managing the resulting tensions. Based on a qualitative case study of the video game publisher Ubisoft, we stress how the tensions raised by internal coopetitive settings limit knowledge sharing between units, and we analyze the mechanisms through which the knowledge broker helps to overcome these limits. We identify three main functions of this knowledge broker that allow the promotion of knowledge and innovation transfer to occur between coopeting units: (1) protecting the unit’s competitive advantage by introducing a lagging principle in the transfer process, (2) reducing sharing costs by standardizing innovative solutions, and (3) enhancing awareness of and trust in innovative solutions by centralizing knowledge diffusion.