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Exponential, quadratic, and trigonometric 2D thermal analysis in inhomogeneous functionally graded materials (FGMs) are solved through an efficient hybrid boundary-type weak-form meshfree algorithm, which is the virtual boundary meshfree Galerkin method with fundamental solutions (FS-VBMGM). Three types of temperature fundamental solutions for FGMs are introduced. The corresponding thermal flow fundamental solutions are derived in detail. Temperature and thermal flux are obtained by utilizing the virtual boundary element method (VBEM) based on the continuous virtual loads. The continuous virtual loads are constructed through the radial basis function interpolation (RBFI) of meshfree algorithm. Using the Galerkin method, calculating formula of FS-VBMGM for thermal analysis in inhomogeneous FGMs is deducted. The benefits of VBEM, Galerkin method, and meshfree algorithm are thus presented in FS-VBMGM. Exponential, quadratic, and trigonometric inhomogeneous numerical examples of FGMs are calculated and contrasted to the exact solutions as well as other numerical methods. The reliability and exactness are proved. The specific discrete formula of FS-VBMGM for thermal analysis in inhomogeneous FGMs is simple to program and extended to calculate other particularly composite FGMs examples. [ABSTRACT FROM AUTHOR]

It is established that the new boundary element-free Galerkin method, namely the virtual boundary element-free Galerkin method (VBEFGM), using dual compactly supported radial basis function interpolation (CSRBFI) for 2D inhomogeneous heat conduction problems with variable heat sources, whose solutions are divided into homogeneous and particular solutions. The virtual loads of the homogeneous solutions and undetermined coefficients of particular solutions are interpolated by CSRBFI. Its formula is established by the Galerkin method. The homogeneous solutions are obtained by the virtual boundary element-free method (VBEFM). The recommended method for 2D inhomogeneous heat conduction problems is real meshfree without background integration elements and exhibits the merits of the meshfree method, Galerkin method, and boundary element method. Its calculation scheme is deduced in detail and easily programmed. The coefficient matrix has symmetrical characteristics. The implementation steps and implementation flow-chart are also shown in detail. Seven numerical examples, such as exponential functionally graded material, are calculated and contrasted with other numerical methods. The precision and stableness of the proposed method for 2D inhomogeneous heat conduction problems are verified. [ABSTRACT FROM AUTHOR]

• The Markovian switching LPV system is introduced to model a nonlinear plant. Every submodel of Markovian switching LPV system is LPV, which better describe the actual system. • A novel bumpless transfer controller is designed for Markovian switching LPV system, which satisfies with a bumpless transfer constraint at the switching points. • A more general condition for transition rates is established since the completely known condition is no longer assumed; which provides an additional degree of freedom for the design of H1 bumpless transfer reliable control. • An application example of the turbofan-engine is introduced to demonstrate the effiectiveness of the main results. In this paper, the H ∞ bumpless transfer reliable control problem of Markovian switching linear parameter-varying (LPV) systems subject to actuator failures is addressed. A bumpless transfer reliable control constraint is introduced to describe the transient performance for such systems. By the use of the parameter-dependent Lyapunov function approach to reduce control bumps generated by the Markovian switching, a reliable switching controller which is also parameter-dependent is constructed to attenuate external disturbances. A criterion checking the solvability of the H ∞ bumpless transfer reliable control problem is provided. As an application, a turbofan-engine model is used to verify the validity of the proposed design method. [ABSTRACT FROM AUTHOR]

• A state-dependent switching strategy is introduced to solve the H ∞ globally asymptotic synchronization issue of the switched complex networks. • A more general condition for ensuring the H ∞ globally asymptotic synchronization is provided, since the H ∞ globally asymptotic synchronization of every subnetwork is unnecessary. • The switching impulsive controller is designed, which includes two parts. The impulsive control part is distributed, which provide a solid foundation in synchronizing process. The state-feedback part ensures synchronization and L 2 gain of the switched complex networks. In this paper, the H ∞ global asymptotic synchronization problem is addressed for switched complex networks. A switching impulsive controller and a state-dependent switching signal are co-designed, which is underpinned by the multiple Lyapunov functions method. A sufficient condition guaranteeing the performance of H ∞ global asymptotic synchronization is established, and does not require the H ∞ global asymptotic synchronization issue of each subsystem solvable. The switching impulsive controller and the state-dependent switching controller are simple in structure and ease of implementation; which includes state-feedback part and impulsive control part. The effectiveness of the presented control method is attested by an example. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the problem of the composite anti-disturbance model reference adaptive control for switched systems with parametric uncertainties and multiple types of disturbances. It is worth emphasizing that the measurability of the system state and the disturbance generated by an exosystem is unnecessary. A key point is to design a composite anti-disturbance model reference adaptive control strategy to achieve the state tracking and the anti-disturbance performance. First, a switched adaptive state-disturbance observer is designed to estimate the system state and the disturbance generated by the exosystem simultaneously. Secondly, based on the switched adaptive state-disturbance observer, a composite switched adaptive controller and a state-dependent switching law are designed to solve the composite anti-disturbance model reference adaptive control problem for switched systems. Thirdly, a sufficient condition ensuring the solvability of the composite anti-disturbance model reference adaptive control problem for switched systems is given, even if the problem is unsolvable for individual subsystems. Finally, an example of the electrohydraulic system is used to verify the availability of the acquired approach. [ABSTRACT FROM AUTHOR]

For switched systems, the time-and state-dependent multiple Lyapunov function method is set up to investigate the bumpless transfer control problem. The key point of the proposed study is to relax the decreasing assumption of traditional Lyapunov functions at switching points and the global limitation of the bumpless transfer constraint, which provides more freedom for solving the bumpless transfer control problem. First, the description of the bumpless transfer performance is proposed by using switching points directly, which makes the controller only constrain in the subinterval of the active interval rather than the whole active interval. Second, a switching controller with time-varying gain matrices and a mixed dwell time-and state-dependent switching signal are designed to reduce control bumps and avoid frequent switching. Third, based on the developed multiple Lyapunov function method, a solvability condition of the bumpless transfer control problem is developed. Finally, an example is given to show the availability of the bumpless transfer control strategy. [ABSTRACT FROM AUTHOR]

This work presents an efficient Procedure for fault measurement of the single-input-single-output (SISO) system by driving the system directly with the output of a chaotic oscillator. Firstly, we propose a method to adjust the Lyapunov exponents (LEs) of the chaotic excitation by multiplying each equation with a different acceleration factor. These acceleration factors constitute an acceleration factor field (AFF). Secondly, in order to evaluate the degree of activation to the SISO system, which is excited by the chaotic signal with different acceleration factors, we partition the AFF into fully matched, partially matched and non-matched areas by using the criteria derived from Kaplan–Yorke conjecture. It is proved that chaotic excitation with acceleration factors chosen from the fully matched AFF can sufficiently excite the system, i.e. every change in the eigen-structure of the system will be reflected in the output. Thirdly, attractor based fault feature “prediction error (PE)” and evolutionary algorithm “Backtracking Search Optimization Algorithm (BSA)” is used to find the optimal acceleration factor׳s location in the matched area, then the fault feature is signified by using the chaotic excitation with optimized acceleration factors. Finally, two linear analog circuits with different chaotic excitations are tested to validate the power of the approach. Experiment results show that fully matched chaotic excitation can be used to detect faults in a SISO system, while, non-matched chaotic excitation may be capable of detecting some faults in the system, but there is a risk to make the wrong decision. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the virtual boundary meshless least squares collocation method of two dimensional steady-state heat conduction problems in multi-domain. In the proposed method, each region with different heat transfer properties is considered as a piecewise homogeneous in a heterogeneous system. Being different from the conventional virtual boundary element method (VBEM), this method incorporates the point interpolation method (PIM) with the compactly supported radial basis function (CSRBF) to approximately construct the virtual source function of the VBEM. Consequently, this method has the advantages of boundary-type meshless methods. In addition, it does not have to deal with singular integral and has the symmetric coefficient matrix, and the pre-processing operation is also very simple. Since the mathematical model for steady-state heat conduction can be represented by a generalized Poisson equation, this problem is solved by finding an approximate particular solution to the Poisson equation and making use of the virtual boundary meshless least squares collocation method to solve the resulting Laplace equation. This method can be used to analyze multi-domain composite structures with each subdomain having different heat transfer properties or materials or geometries. Since the configuration of virtual boundary has a certain preparability, the integration along the virtual boundary can be carried out over the smooth simple curve that can be structured beforehand (for 2D problems) to reduce the complicity and difficulty of calculus without loss of accuracy, while “Vertex Question” existing in BEM can be avoided. In the end, several numerical examples are analyzed using the proposed method and some other commonly used methods for verification and comparison purposes. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the problem of robust finite-time control for Markovian jump systems with partially known transition probabilities. Sufficient conditions ensuring the finite-time boundedness, finite-time boundedness and finite-time state feedback stabilization are, respectively, developed for the given system for the first time. A robust finite-time state feedback controller is also designed, which guarantees the finite-time boundedness of the closed-loop system. Seeking computational convenience, all the conditions are cast in the format of linear matrix inequalities. Finally a numerical example is provided to demonstrate the effectiveness of the main results. [Copyright &y& Elsevier]

Abstract: Moving least squares approximation (MLSA) has been widely used in the meshless method. The singularity should appear in some special arrangements of nodes, such as the data nodes lie along straight lines and the distances between several nodes and calculation point are almost equal. The local weighted orthogonal basis functions (LWOBF) obtained by the orthogonalization of Gramm–Schmidt are employed to take the place of the general polynomial basis functions in MLSA. In this paper, MLSA with LWOBF is introduced into the virtual boundary meshless least square integral method to construct the shape function of the virtual source functions. The calculation format of virtual boundary meshless least square integral method with MLSA is deduced. The Gauss integration is adopted both on the virtual and real boundary elements. Some numerical examples are calculated by the proposed method. The non-singularity of MLSA with LWOBF is verified. The number of nodes constructing the shape function can be less than the number of LWOBF and the accuracy of numerical result varies little. [Copyright &y& Elsevier]

Abstract: We propose a model to address the problem how the evolution of cooperation in a social system depends on the spatial motion and the payoff expectation. In the model, if the actual payoff of an individual is smaller than its payoff expectation, the individual will either move to a new site or simply reverse its current strategy. It turns out that migration of dissatisfied individuals with relatively low expectation level leads to the aggregation of cooperators and promotion of cooperation. Moreover, under appropriate parameters migration leads to some interesting spatiotemporal patterns which seems not to have been reported in previously studied spatial games. Furthermore, it also found that a population with constant expectation can better favor cooperative behavior than a population with adaptive aspiration. [Copyright &y& Elsevier]

For a class of switched nonlinear systems with unmatched external disturbances and unknown backlash-like hysteresis, an adaptive fuzzy-based control strategy is proposed to handle the anti-disturbance issue. The unmatched external disturbances come from a switched exosystem. Our aim is to achieve the output tracking performance and the disturbance attenuation by using the adaptive fuzzy-based composite anti-disturbance control technique. First, based on the fuzzy logics, we design a switching adaptive fuzzy disturbance observer to estimate unmatched external disturbances. Second, a composite switching adaptive anti-disturbance controller is constructed. By means of the backstepping technique, disturbance estimations are added in each virtual control to offset the unmatched disturbances, which results in the different coordinate transformations. At last, the availability of the proposed approach is illustrated by a mass-spring-damper system. [ABSTRACT FROM AUTHOR]

• The finite-time stability concept is extended to the input–output finite-time stability for the Markovian jump systems with incomplete transition probabilities. • An observer-based output feedback controller is constructed to solve the input–output finite-time stability problem. • Since the transition probabilities are incompletely known, we discuss the input–output finite-time stabilization problem under two different cases. • By constructing efficient Lyapunov–Krasovskii functionals, no nonlinear crossing terms appear. A set of observer gains and controller gains can be given in explicit form by solving a set of strict linear matrix inequalities. • A mass-spring system is modelled as a MJS with delay, for which we have demonstrated the superiority of the proposed algorithms. This paper deals with the input–output finite-time stabilization problem for Markovian jump systems (MJSs) with incompletely known transition rates. An observer-based output feedback controller is constructed to study the input–output finite-time stability (IO-FTS) problem. By using the mode-dependent Lyapunov–krasovskii functional method, a sufficient criterion checking the IO-FTS problem is provided. Then, an observer and a corresponding state feedback controller for the individual subsystem are respectively designed to solve the input–output finite-time stabilization problem for the systems. Finally, a numerical example on the mass-spring system model is investigated to bring out the advantages of the control scheme proposed in this paper. [ABSTRACT FROM AUTHOR]

The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has unique epidemiological characteristics that include presymptomatic and asymptomatic infections, resulting in a large proportion of infected cases being unconfirmed, including patients with clinical symptoms who have not been identified by screening. These unconfirmed infected individuals move and spread the virus freely, presenting difficult challenges to the control of the pandemic. To reveal the actual pandemic situation in a given region, a simple dynamic susceptible-unconfirmed-confirmed-removed (D-SUCR) model is developed taking into account the influence of unconfirmed cases, the testing capacity, the multiple waves of the pandemic, and the use of non-pharmaceutical interventions. Using this model, the total numbers of infected cases in 51 regions of the USA and 116 countries worldwide are estimated, and the results indicate that only about 40% of the true number of infections have been confirmed. In addition, it is found that if local authorities could enhance their testing capacities and implement a timely strict quarantine strategy after identifying the first infection case, the total number of infected cases could be reduced by more than 90%. Delay in implementing quarantine measures would drastically reduce their effectiveness. [ABSTRACT FROM AUTHOR]

This paper investigates the finite-time adaptive neural control and almost disturbance decoupling problems for multi-input/multi-output (MIMO) nonlinear systems with disturbances and non-strict-feedback structure. In the design procedure of the adaptive controller, neural networks are employed to estimate the unknown nonlinearities and Young's inequality is utilized to cope with the disturbance terms derived from all subsystems. In order to characterize the disturbance attenuation performance of finite-time adaptive control, a criterion named finite-time almost disturbance decoupling is first developed. Under this criterion, an adaptive neural controller is designed via the backstepping method and the appropriate selection of Lyapunov function. It is revealed that the proposed controller can guarantee all variables of the closed-loop system are bounded, and the performance of finite-time almost disturbance decoupling is realized. Finally, a practical example is employed to validate the effectiveness of the designed controller. [ABSTRACT FROM AUTHOR]

This paper dedicates to dealing with the adaptive neural design problem for uncertain stochastic nonlinear systems with non-lower triangular pure-feedback form and input constraint. On the basis of the mean-value theorem, the pure-feedback structure is first transformed into the desired affine structure, and then the well-known backstepping technology is applied to construct the actual input signal of the controller. Although the considered system has a fairly complex structure, a new adaptive neural tracking controller design frame is established via the flexible application of radial basis function (RBF) neural networks' (NNs') structural characteristics. The proposed design frame guarantees the control objective of this paper can be achieved. Finally, a simulation example is given to further illustrate the availability of the proposed control scheme. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the multiple model strategy is applied to the adaptive control of switched linear systems to improve the transient performance. The solvability of the adaptive stabilization problem of each subsystem is not required. Firstly, the two-layer switching mechanism is designed. The state-dependent switching law with dwell time constraint is designed in the outer-layer switching to guarantee the stability of the switched systems. During the interval of dwell time constraint, the parameter resetting adaptive laws are designed in the inner-layer switching to improve the transient performance. Secondly, the minimum dwell time constraint providing enough time for multiple model adaptive control strategy to work fully and maintaining the stability of the switched systems is found. Finally, the proposed switched multiple model adaptive control strategy guarantees that all the closed-loop system signals remain bounded and the state tracking error converges to zero. [ABSTRACT FROM AUTHOR]