查看更多>>摘要：For a simple graph G , its Q -graph Q (G ) is derived from G by adding one new point in every edge of G and linking two new vertices by edge if they are between two edges that having a common endpoint. In our work, we demonstrate that for a regular graph G , if all the signless Laplacian eigenvalues are integers, then the Q (G ) exists no signless Laplacian perfect state transfer. We also present a sufficient restriction that the Q (G ) admits signless Laplacian pretty good state transfer when G exhibits signless Laplacian perfect state transfer between two specific vertices for a regular graph G . In addition, in view of these results, we also present some new families of Q -graphs, which have no signless Laplacian perfect state transfer, but admit signless Laplacian pretty good state transfer. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Thomassen proved that all planar graphs are 5-choosable. Skrekovski strengthened the result by showing that all K 5-minor-free graphs are 5-choosable. Dvorak and Postle pointed out that all planar graphs are DP-5-colorable. In this note, we first improve these results by showing that every K 5-minor-free or K-3,K- 3-minor-free graph is DP-5-colorable. In the final section, we further improve these results under the term strictly f-degenerate transversal. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Currently, the catch of fishery resources in South Korea has fallen more than 40%, from 1.73 million tons in 1986 to 1.01 million tons in 2018. In particular, the amount of chub mack-erel, one of the most favored fish species by South Koreans, caught in 2017 was 103,870 tons, which was only 25% of the total catch, compared with 415,003 tons in 1996. The total allowable catch system and the closed season are currently in place as a countermeasure to the continued decline in fishery resources; however, their effectiveness is questionable. Our study aims to maximize fishing profits by controlling the monthly fishing effort while maintaining the amount of chub mackerel. Discrete age-structured mathematical model was established with an optimal harvest control system. Density-dependent mortality was applied at the juvenile stage to reflect fish mortality because it is highly dependent on population density in the underage phase. The conditions of the parameters guaranteeing the existence of optimal harvest strategies were demonstrated and obtained using Pon-tryagin's maximum principle. We compared an optimal harvest strategies and the actual harvest strategies of fishing effort from July 2010 to June 2020. In addition, we compared the profit and biomass of the optimal harvest strategies when designating one month in a year as closed season. We also conducted sensitivity analysis by varying the price of chub mackerel and cost of fishing effort. As a result, the optimal harvest strategies are to have the highest amount of fishing effort from August to September and gradually re-duce the amount of effort. The optimal harvest strategies could improve the maximum economic yield and the maximum sustainable yield by 11.9% and 10.9%, respectively, over the observed strategy. To the best of our knowledge, forecasting analysis of the maximum economic yield and closed season conducted based on optimal harvest control system for Chub mackerel in South Korea. The appropriate allocation of monthly fishing effort can in-crease sustainable catch and profit. In addition, it is better to implement a closed season in July to maximize the profit of fishing and in June to the resource recovery.(c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Investigation of the asymptotic properties of solutions to systems of discrete equations is a topic of permanent interest. Numerous papers analyze the so-called prescribed behaviour of solutions giving sufficient conditions for the existence of at least one solution having a given asymptotic behaviour. To a smaller extent the problem is considered of determining the initial data generating such solutions. The present paper finds its niche being concerned with the case of a triangular system of linear discrete equations. The existence of solutions with a prescribed asymptotic behaviour is proved and algorithms suggested for computing stepwise the initial data defining such solutions and eventually suggesting these. Illustrative examples (supported with a MATLAB program) are considered and some open problems are formulated as well. (C) 2021 Elsevier Inc. All rights reserved.
An, ShujuanTian, KaiDing, ZhaodongJian, Yongjun...
9页
查看更多>>摘要：This study investigates the unsteady electroosmotic slip flow of viscoelastic fluid through a parallel plate microchannel under the combined effect of electroosmotic and pressure gradient forcings. Analytical solutions for velocity and potential distributions are derived using the Debye-Hackel linearization, Laplace transform, and residue theorem. Numerical solutions are also provided based on the finite difference method. The process through which the velocity and flow rate attain a steady state is related to the governing groups, including the fractional calculus parameter alpha, slip coefficient L , Deborah number De , normalized electrokinetic width K and ratio 17 of the pressure to electroosmotic driving forces. Results show that an increase in alpha, De , L or 17 increases the time required to reach a steady state. The steady flow rate depends on L and K but is independent of alpha and De . For the same slip coefficient, increases in alpha, De or K increase the slip velocity at the wall. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Fredholm integral equation of the first kind is a typical ill-posed problem, and it is usually difficult to obtain a stable numerical solution. In this paper, a new method is proposed to solve Fredholm integral equation using Gaussian process regression (GPR). The key to this method is that the right-hand term of the original integral equation is reconstructed by the GPR model to obtain a new integral equation in a reproducing kernel Hilbert spaces (RKHS). We present an analytical approximate solution of the new equation and prove that it converges to the exact minimal-norm solution of the original equation under the L2 -norm. Especially, for the degenerate kernel equation, we obtain an explicit formula of the exact minimal-norm solution. Finally, the proposed method is verified to be very effective in solution accuracy by multiple examples. (c) 2022 Elsevier Inc.
查看更多>>摘要：In this paper, we develop a computational multiscale method to solve the parabolic wave approximation with heterogeneous and variable media. Parabolic wave approximation is a technique to approximate the full wave equation. One benefit of the method is that one wave propagation direction can be taken as an evolution direction, and one then can discretize it using a classical scheme like backward Euler method. Consequently, one obtains a set of quasi-gas-dynamic (QGD) models with possibly different heterogeneous permeability fields. For coarse discretization, we employ constraint energy minimization generalized multiscale finite element method (CEM-GMsFEM) to perform spatial model reduction. The resulting system can be solved by combining the central difference in time evolution. Due to the variable media, we apply the technique of proper orthogonal decomposition (POD) to further the dimension of the problem and solve the corresponding model problem in the POD space instead of in the whole multiscale space spanned by all possible multi scale basis functions. We prove the stability of the full discretization scheme and give the convergence analysis of the proposed approximation scheme. Numerical results verify the effectiveness of the proposed method. (c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：A network is always viewed as a simple connected graph. The connectivity of a network can evaluate its fault tolerance and reliability. Since the faulty elements of a graph may have special structures, the (strong) structure connectivity and (strong) substructure connectivity were proposed as generalizations of connectivity. We give the (strong) structure connectivity and (strong) substructure connectivity of the (n, k )-bubble-sort network B-n,B-k in this paper, where the special structures are complete graphs. (C)& nbsp;2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：Conformity behavior is crucial in human social learning and we consider this effect on spatial public goods game (SPGG). Two types of agents and two corresponding social learning rules are introduced in SPGG. One is link-type agents based on the rational conformity learning rule, whose strategies are independent in different groups. The other is node-type agents based on the Fermi learning rule, whose strategies are the same in different groups. Rational conformity behavior signifies that conformity only occurs when individuals are unsatisfied with their payoffs. Through simulation experiments, we find that cooperation can be induced constantly with a large proportion of link-type agents, in which situation rational conformity behavior in social learning is conducive to the emergence of cooperation. We further find that the independent strategies of link-type agents favor reciprocity to be enhanced among cooperative groups and the extended imitation range is beneficial to distinguish cooperative groups which also improves cooperation. Moreover, an appropriate payoff threshold is favorable to induce a positive correlation between payoffs and contributions, and thus a more reasonable distribution of payoffs and strategies. Meanwhile, the payoff threshold in the rational conformity learning rule is also contributed to diminishing the spread of defective behavior for those defectors with outstandingly high payoffs. These results expand our comprehension of individuals' conformity behavior in social learning and its effect on cooperation in social dilemmas.(c) 2022 Elsevier Inc. All rights reserved.
查看更多>>摘要：In this paper, we develop and study a fully implicit positive finite volume scheme that allows an accurate approximation of the nonlinear highly anisotropic convection-diffusion equations on almost arbitrary girds. The key idea is to relate the oscillatory fluxes, including the convective ones, to the normal monotonic diffusive flux thanks to a technique used in the Scharfetter-Gummel discretizations. Then, we obtain a nonlinear two-point-like scheme with positive coefficients on primal and dual meshes. We check that the structure of the scheme naturally ensures the nonnegativity of the approximate solutions. We also establish energy estimates, which leads to a proof of existence of the numerical solutions. This analytical study is accompanied with a series of numerical results and simulations. They highlight the fulfillment of the discrete maximum principle, the optimal accuracy of our scheme, and its robustness with respect to the mesh and to high ratios of anisotropy. (C) 2022 Elsevier Inc. All rights reserved.
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