查看更多>>摘要：Almost output regulation for switched linear systems with destabilizing behaviors, which means that the almost output regulation problems of all subsystems are unsolvable and some switching instants are unstable with finite increments of the Lyapunov function, is investigated based on the bumpless transfer control. Switching instants with decrements and increments of the Lyapunov function are described as stable and unstable switching instants respectively. Firstly, a hybrid average dwell time strategy is proposed to restrict the occurrence ratio of unstable/stable switching instants and reasonably arranges the number of stable switching instants to offset the increment of the Lyapunov function caused by unstable switching instants and insolvabilities of the involved problem for all subsystems. Then, by interpolating the gains of adjacent controllers within the minimum dwell time, a dynamic error feedback controller with bumpless transfer property is designed to suppress the control bumps induced by controller switchings. Finally, a numerical example is given to demonstrate the effectiveness of the proposed method. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：This paper will investigate the linear quadratic (LQ) control problem for a stochastic system with different intermittent observations. Different from traditional LQ control problems, two controllers with different information structures are considered to minimize a quadratic performance index. Specifically, the information sets available to two controllers are different and mutually exclusive (i.e., either of both is not the subset of the other one). The problem under consideration in this paper is an asymmetric information control problem. It is highlighted that previous literature on asymmetric information control mainly focused on the case when the information set is a subset of the other one. However, the case of the information sets being mutually exclusive remains less investigated to the best of our knowledge, which brings essential difficulties in finding the optimal control strategies: the structures and forms of two controllers are not clear; seeking for the solvability conditions of the optimal control problem is challenging. We summarize the contributions of this paper as follows: Firstly, by adopting the convex variational method, the necessary and sufficient solvability conditions are derived under some basic assumptions, which are relied on the forward and backward difference equations (FBSDEs); Secondly, by decoupling the FBSDEs, the control strategies are derived; Finally, the results are extended to investigate the general multiple controllers case. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：In classical ruin theory, the time of ruin is defined as the time when the surplus of an insurance portfolio falls below zero. This simplification of a single barrier, however, needs careful adaptations to imitate the real-world liquidation process. Inspired by [7] and [24], this paper adopts a three-barrier model to describe the financial stress leading to bankruptcy of an insurer. The financial status of the insurer is classified into three states, namely, the solvent, the insolvent, and the liquidated. The insurer's surplus processes at the states of solvent and insolvent are modeled by two spectrally negative Levy processes, which have been taken as good candidates to model insurance risks in the recent literature. Accordingly, the time of liquidation is defined in this three-barrier model. By adopting the techniques of excursions in fluctuation theory, we obtain the joint distribution of the time of liquidation, the surplus at liquidation, and the historical high of the surplus until liquidation, which generalizes the known results on the classical expected discounted penalty function from [16]. The results have semi-explicit expressions in terms of the scale functions and the Levy triplets associated with the two underlying Levy processes. The special case when the two underlying Levy processes coincide with each other or differ from each other by a constant drift term is also studied, and our results are expressed compactly via only the scale functions. The corresponding results are consistent with the classic works of literature on Parisian ruin with (or without) a lower barrier in [4,22], and [14]. Numerical examples are provided to illustrate the underlying features of liquidation ruin. (C) 2021 Elsevier Inc. All rights reserved.
Perez de Amezaga, Claudio SanchezGarcia-Suarez, Victor M.Fernandez-Martinez, Juan L.
20页
查看更多>>摘要：The electronic structure encapsulated in the density of states (DOS) is key to explain several physical properties of any material, i.e. from the knowledge of the DOS and its dependence on certain parameters it is possible to obtain a lot of information on the type of material and its behaviour. We outline in this article a series of methods that can be employed to classify and predict bulk DOS in an easy and efficient manner. These methods are based on machine learning techniques that are used to classify the elements and extract information from the DOS curves. We focus in particular in the bulk DOS of d-elements with different crystal lattices. We use a clusterization algorithm based on information obtained from the DOS, which is able to properly classify the elements in groups that are electronically similar. We find four groups clearly differentiated, whose more representative elements are scandium, iron, gold and mercury, and which tend to crystallize in similar lattice structures in their ground state. We further reduce the dimensionality of the data and find a new basis of DOS that, along with chemical properties of each type of element and basic information encapsulated in the DOS, is able to predict with a high degree of accuracy most of the original curves. We apply such basis and information to predict with reasonably accuracy the DOS curve of different elements. We also use that data to predict the chemical properties and the correlations between them. In particular, we apply the algoritm to calculate the Pauling electronegativity and find a rather good agreement between the predicted and real values. Finally, from intrinsic parameters, the DOS of other elements and additional information that is needed to properly describe the electronic structure, we predict the particular DOS of a particular element with a good degree of accuracy, including the width and general shape of the central part associated to the d states. These calculations prove that, by using pure electronic information encapsulated in the bulk DOS, it is possible to univocally classify materials and predict in a fast and accurate manner different physical and chemical properties. (C) 2021 Published by Elsevier Inc.
查看更多>>摘要：This paper focuses on the fault detection for networked systems with deception attacks. Firstly, a fault detection filter (FDF) is presented as a residual generator to detect the random occurring fault signal timely in networked systems with the consideration of network delay and deception attacks. Then, by using the Lyapunov stability theory and linear matrix inequality (LMI) techniques, sufficient conditions are presented to guarantee the stability with an H-infinity performance index gamma of our proposed fault detection system. Furthermore, the corresponding coefficient matrices of the FDF are also presented with the explicit expressions. Finally, two simulation examples demonstrate the effectiveness and practicability of the designed FDF. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：We consider wave propagation across an infinite waveguide of an arbitrary bounded cross-section, whose interior is blocked by two identical thick perforated barriers with holes. When the holes are small, the waves over a broad range of frequencies are almost fully reflected. However, we show the existence of a resonance frequency at which the wave is almost fully transmitted, even for very small holes. Counter-intuitively, this resonance effect occurs for barriers of arbitrary thickness. We also discuss another asymptotic limit, in which the thickness of barriers grows to infinity but the fixed diameter of the holes can be large and even arbitrarily close to the diameter of the waveguide. The resonance scattering, which is known as tunneling effect in quantum mechanics, is demonstrated in a constructive way by rather elementary tools such as separation of variables and matching of the resulting series, in contrast to commonly used abstract methods such as searching for complex-valued poles of the scattering matrix or non-stationary scattering theory. In particular, we derived an explicit equation that determines the resonance frequency. The employed basic tools make the paper accessible to non-experts and educationally appealing. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：A new approach is introduced for the oscillatory solutions of the second order non-linear delay dynamic equations on time scale with a super-linear neutral term. The result are obtained through various integral and differential relations. The Kamenev and Philos-type criteria for oscillation are also discussed. The results improve and extend the ones reported in the literature in the sense that the inequalities are easy to verify and results cover various kinds of equations by choosing different time scales. Examples for particular time scales are given for illustration. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：In this paper, a novel online mode-free integral reinforcement learning algorithm is proposed to solve the multiplayer non-zero sum games. We first collect and learn the subsystems information of states and inputs; then we use the online learning to compute the corresponding Ncoupled algebraic Riccati equations. The policy iterative algorithm proposed in this paper can solve the coupled algebraic Riccati equations corresponding to the multiplayer non-zero sum games. Finally, the effectiveness and feasibility of the design method of this paper is proved by simulation example with three players. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：Interactions in biology and social systems are not restricted to pairwise but can take arbitrary sizes. Extensive studies have revealed that the arbitrary-sized interactions significantly affect the spreading dynamics on networked systems. Competing spreading dynamics, i.e., several epidemics spread simultaneously and compete with each other, have been widely observed in the real world, yet the way arbitrary-sized interactions affect competing spreading dynamics still lacks systematic study. This study presents a model of two competing simplicial susceptible-infected-susceptible epidemics on a higher-order system represented by simplicial complex and analyzes the model's critical phenomena. In the proposed model, a susceptible node can only be infected by one of the two epidemics, and the transmission of infection to neighbors can occur through pairwise (i.e., an edge) and higher-order (e.g., 2-simplex) interactions simultaneously. Through a mean-field (MF) theory analysis and numerical simulations, we show that the model displays rich dynamical behavior depending on the 2-simplex infection strength. When the 2-simplex infection strength is weak, the model's phase diagram is consistent with the simple graph, consisting of three regions: the absolute dominant regions for each epidemic and the epidemic-free region. With the increase of the 2-simplex infection strength, a new phase region called the alternative dominant region emerges. In this region, the survival of one epidemic depends on the initial conditions. Our theoretical analysis can reasonably predict the time evolution and steady-state outbreak size in each region. In addition, we further explore the model's phase diagram both when the 2-simplex infection strength is symmetrical and asymmetrical. The results show that the 2-simplex infection strength has a significant impact on the system phase diagram. (C) 2021 Elsevier Inc. All rights reserved.
查看更多>>摘要：We consider an initial-boundary value problem for the n-dimensional wave equation, n >= 2, with the variable sound speed with the nonhomogeneous Dirichlet boundary conditions. We construct and study three-level in time and compact in space three-point in each spatial direction alternating direction implicit (ADI) schemes having the approximation orders O(h(t)(2) + vertical bar h vertical bar(4)) and O(h(t)(4) + vertical bar h vertical bar(4)) on the uniform rectangular mesh. The study includes stability bounds in the strong and weak energy norms, the discrete energy conservation law and the error bound of the order O(h(t)(2) + vertical bar h vertical bar(4)) for the first scheme as well as a short justification of the approximation order O(h(t)(4) + vertical bar h vertical bar(4)) for the second scheme. We also present results of numerical experiments. (C) 2021 Elsevier Inc. All rights reserved.
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