查看更多>>摘要：Given a connected graph G , the toughness tau G is defined as the minimum value of the ratio |S|/omega(G-S), where S ranges over all vertex cut sets of G , and omega(G-S) is the number of connected components in the subgraph G - S obtained by deleting all vertices of S from G . In this paper, we provide a lower bound for the toughness tau(G) in terms of the maximum degree, minimum degree and normalized Laplacian eigenvalues of G . This can be viewed as a slight generalization of Brouwer's toughness conjecture, which was confirmed by Gu (2021). Furthermore, we give a characterization of those graphs attaining the two lower bounds regarding toughness and Laplacian eigenvalues provided by Gu and Haemers (2022). (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：For an edge subset S of connected graph G, if G - S has only one perfect matching M, then S is called an anti-forcing set of M. The number of edges in a smallest anti-forcing set of M is the anti-forcing number of M, generally indicated by the symbol a f (G, M) . For a graph G, its anti-forcing spectrum is defined as the integer set Spec af (G ) := { af(G, M) : M is a perfect matching of G } . In this paper, we show that for a (4,6)-fullerene graph T n with cyclic edge-connectivity 3, Spec af (T n ) = [ n + 3 , 2 n + 4] . Moreover, we show that for any perfect matching M of a (4 , 6) -fullerene graph G, a minimum anti-forcing set S of M and each M-alternating facial boundary share exactly one edge. Applying this conclusion, we prove that the minimum anti-forcing number of a lantern structure (4,6)-fullerene of order n is L n 8 j + 2 , and Spec a f (B n ) = [ L n 8 j + 2 , L n (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：A novel dynamic event-triggered distributed fault tolerant control (FTC) scheme with guaranteed cost is proposed for uncertain nonlinear interconnected systems suffering from time-varying actuator faults. The event-triggered FTC problem of uncertain interconnected system is first converted to a series of equivalent event-triggered optimal control designs of isolated fault-free auxiliary subsystems by defining a modified cost function for each auxiliary subsystem. The equivalence of problem transformation is demonstrated meanwhile the upper bound of cost function of overall interconnected system is analyzed. Subsequently, for the isolated auxiliary subsystem, a dynamic event-triggered adaptive dynamic programming (DET-ADP) algorithm is proposed to obtain the optimal control policy, which can remove the restriction of initial admissible control, eliminate the actor network, and save more communication resources. Furthermore, we prove that the closed-loop auxiliary subsystems are ensured to be uniform ultimate bounded based on Lyapunov approach. Finally, simulation results are presented to validate the developed dynamic eventtriggered distributed guaranteed cost FTC scheme.
查看更多>>摘要：The control of heat transfer in the hydromagnetic semiconductor crystal involves Marangoni convection with buoyancy forces. In this study, the conventional thermo-solutal Marangoni mixed flow model is modified by incorporating the solutal buoyancy effects that are significant in the flow phenomenon. The heat and mass transfer (HMT) characteristics of the Marangoni convective flow of a Cu - H2O nanofluid subjected to the assisting/resisting buoyancy forces and cross-diffusion are numerically studied. The homogeneous single-phase nanoliquid model is used in conjunction with experimental data of dynamic viscosity and thermal conductivity. The Dufour and Soret effects are considered. Governing equations are solved using the finite difference-based algorithm. The problem is analyzed in a unified way considering the cases of buoyancy-assisted flow and buoyancy opposed flow. The response surface methodology (RSM) based on the face-centered composite design (CCD) is used to optimize the heat and mass transfer rates. A multivariate regression model is proposed and authenticated prior to optimization. Additionally, sensitivity analysis is performed using the full quadratic regression model. The increase in the temperature profile is more significant due to the radiative heat flux than the inclined magnetic field. Heat transfer has a high sensitivity to the appearance of thermal radiation, while mass transfer has a high sensitivity to the Soret effect. Simultaneous optimization of HMT rates is achieved with the high level of thermal radiation and low levels of the cross-diffusion aspects. (c) 2022 Elsevier Inc. All rights reserved.
Moghadam, Amin AbrishamiSoheili, Ali R.Bagherzadeh, Amir Saboor
14页
查看更多>>摘要：In this paper, a new method for solving fourth-order BVPs is presented. The method is based on the first type Lidstone interpolating function. One of the greatest features of the Lidstone interpolating function is that, it can be extended to a piecewise function. Therefore, this extension led us construct piecewise Lidstone interpolating functions on the subintervals and subsequently on the collocation points to have better accuracy. We have fully discussed the method and the whole process in full details to obtain a large system of algebraic equations. The system includes numerical approximation of the problems at the collocation points. From the aspect of error estimation, we have obtained the local truncation errors of the equations and finally presented the comparisons of our approach with the other methods.(c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Let H be a digraph possibly with loops and D a digraph without loops with a coloring of its arcs c : A(D)& nbsp;-> V (H) ( D is said to be an H-colored digraph). A directed path W in D is said to be an H-path if and only if the consecutive colors encountered on W form a directed walk in H. A subset N of vertices of D is said to be an H-kernel if (1) for every pair of different vertices in N there is no H-path between them and (2) for every vertex u in V (D ) \ N there exists an H-path in D from u to N. Under this definition an H-kernel is a kernel whenever A(H) = empty set . The color-class digraph C-C (D ) of D is the digraph whose vertices are the colors represented in the arcs of D and (i, j) is an element of & nbsp;A (C-C (D )) if and only if there exist two arcs, namely (u, v ) and (v , w ) in D , such that (u, v ) has color i and (v , w ) has color j. Since not every H-colored digraph has an H-kernel and V (C-C(D)) = V (H) , the natural question is: what structural properties of C-C(D), with respect to the H-coloring, imply that D has an H-kernel?& nbsp;In this paper we investigate the problem of the existence of an H-kernel by means of a partition xi of V(H) and a partition {xi(1), xi(2)} of xi. We establish conditions on the directed cycles and the directed paths of the digraph D , with respect to the partition {xi(1), xi(2)}. In particular we pay attention to some substructures produced by the partitions xi and {xi(1), xi(2}), namely (xi(1),xi, xi(2)) -H-subdivisions of (C)over right arrow(3) and (xi(1), xi, xi(2)) -H-subdivisions of (P)over right arrow(3) .& nbsp;We give some examples which show that each hypothesis in the main result is tight. (C)& nbsp;2022 Elsevier Inc. All rights reserved.
Ugarte, Juan P.Tenreiro Machado, J. A.Tobon, Catalina
15页
查看更多>>摘要：Atrial fibrillation (AF) underlies disordered spatiotemporal electrical activity, that increases in complexity with the persistence of the arrhythmia. It has been hypothesized that a specific arrhythmogenic mechanism, known as rotor, is the main driver sustaining the AF. Thus, the ablation of rotors has been suggested as a therapeutic strategy to terminate the arrhythmia. Nonetheless, such strategy poses a problem related with the characterization of the rotor propagating activity. This work addresses the rotor characterization by means of a fractional generalization of the entropy concept. By adopting complex order derivative operators, we endorse the definition of information content. The derived metric is used to study the AF propagation dynamics in computational models. The results evince that the fractional entropy approach yields a better spatio-temporal characterization of rotor dynamics than the conventional entropy analysis, under a wide range of simulated fibrillation conditions.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
查看更多>>摘要：The view that altruistic punishment plays an important role in supporting public cooperation among human beings and other species has been widely accepted by the public. However, the positive role of altruistic punishment in enhancing cooperation will be undermined if corruption is considered. Recently, behavioral experiments have confirmed this finding and further investigated the effects of the leader's punitive power and the economic potential. Nevertheless, there are relatively few studies focusing on how these factors affect the evolution of cooperation from a theoretical perspective. Here, we combine institutional punishment public goods games with bribery games to investigate the effects of the above factors on the evolution of cooperation. Theoretical and numerical results reveal that the existence of corruption will reduce the level of cooperation when cooperators are more inclined to provide bribes. In addition, we demonstrate that stronger leader and richer economic potential are both important to enhance cooperation. In particular, when defectors are more inclined to provide bribes, stronger leaders can sustain the contributions of public goods from cooperators if the economic potential is weak.(c) 2022 Elsevier Inc. All rights reserved.
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