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Applied mathematics and computation
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Applied mathematics and computation

Elsevier [etc.]

0096-3003

Applied mathematics and computation/Journal Applied mathematics and computationSCIISTPEIAHCI
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    Observer-Based fuzzy containment control for nonlinear networked mass under dos attacks

    Ma, Yong-ShengChe, Wei-WeiDeng, Chao
    14页
    查看更多>>摘要：The observer-based fuzzy containment control problem of nonlinear networked multi agent systems (MASs) suffered from denial-of-service (DoS) attacks is studied in this paper. The studied nonlinear networked MASs are expressed by the Takagi-Sugeno (T-S) fuzzy model. For each agent, the sensor sends measurements to the controller through a non ideal wireless network that may be attacked. Due to the fact that system states are unmeasurable, a fuzzy observer design method is proposed to resist DoS attacks. Based on observer states, a novel resilient containment controller is designed to compensate for DoS attacks and achieve the states containment objective. The proposed controller design method can convert the nonconvex design condition into a convex one by using the rank decomposition method combined with DoS attacks effect. Finally, simulation is shown to testify the effectiveness of the designed fuzzy observer and containment controller.(c) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    The multiscale perturbation method for two-phase reservoir flow problems

    Rocha, Franciane F.Mankad, HetSousa, Fabricio S.Pereira, Felipe...
    20页
    查看更多>>摘要：In this work we formulate and test a new procedure, the Multiscale Perturbation Method for Two-Phase Flows (MPM-2P), for the fast, accurate and naturally parallelizable numerical solution of two-phase, incompressible, immiscible displacement in porous media approximated by an operator splitting method. The proposed procedure is based on domain decomposition and combines the Multiscale Perturbation Method (MPM) [Ali, et al., Appl. Math. and Comput., 387 (2020) pp. 125023] with the Multiscale Robin Coupled Method (MRCM) [Guiraldello, et al., J. Comput. Phys., 355 (2018) pp. 1-21]. When an update of the velocity field is called for by the operator splitting algorithm, the MPM-2P may provide, depending on the magnitude of a dimensionless algorithmic parameter, an accurate and computationally inexpensive approximation for the velocity field by reusing previously computed multiscale basis functions. Thus, a full update of all multiscale basis functions required by the MRCM for the construction of a new velocity field is avoided. There are two main steps in the formulation of the MPM-2P. Initially, for each subdomain one local boundary value problem with trivial Robin boundary conditions is solved (instead of a full set of multiscale basis functions, that would be required by the MRCM). Then, the solution of an inexpensive interface problem provides the velocity field on the skeleton of the decomposition of the domain. The resulting approximation for the velocity field is obtained by downscaling. We consider challenging two-phase flow problems, with high-contrast permeability fields and water-oil finger growth in homogeneous media. Our numerical experiments show that the use of the MPM-2P gives exceptional speed-up -almost 90% of reduction in computational cost -of two-phase flow simulations. Hundreds of MRCM solutions can be replaced by inexpensive MPM-2P solutions, and water breakthrough can be simulated with very few updates of the MRCM set of multiscale basis functions.(c) 2021 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    An analytical theory for the forced convection condensation of shear-thinning fluids onto isothermal horizontal surfaces

    Chakraborty, SoumikKar, Uttam KumarSengupta, SayantanPramanik, Shantanu...
    15页
    查看更多>>摘要：We present an analytical theory for laminar forced convection condensation of saturated vapor on horizontal surfaces. The condensation produces shear-thinning film moving downstream due to the viscous-drag occurring at the vapor-liquid interface. The mathematical model is built based on a few input parameters, viz. power-law index (n), nondimensional film-thickness (eta(delta,l)), Prandtl number (Pr), and inertia number (Mc). A set of output parameters is used to analyze the distinct characteristics of the fluid-flow and condensation, viz. the condensate's nondimensional mass flow rate ((m) over cap), Nusselt number, specific enthalpy ratio (R-h), thermal retention coefficient (circle dot), and nondimensional wall-shear stress ((tau) over cap (w)). We have identified the subtlety of shear-thinning film flow when liquid's thermophysical properties vary according to the changes in wall-shear and the interfacial drag. Contextually, we illustrate that a rise in shear-thinning effect (obtained by decreasing n), keeping Mc and eta(delta,l) fixed, results in a decrease of (m) over cap, R-h, (tau) over cap (w), and (1/(sic)). We have demonstrated that for a fixed R h, a shear-thinning film, compared to the Newtonian film, would exhibit a greater.d, l but a smaller interfacial velocity (f'(i)). Furthermore, a greater film thickness is required for low Prliquids to attain the same degree of subcooling compared to high Prliquids. We perform systematic investigation over a wide range of eta(delta,l) We observe that for small.d, l values, the vapor boundary-layer moving onto the liquid-film exhibits similar flow-features as found in the well-known Blasius boundary-layer. Conversely, at large eta(delta,l), the present solution would remarkably differ from the Blasius solution. Finally, we establish an approximate theory for small.d, l motivated by the linearity in the cross-stream variations of velocity and temperature within the thin-film. This approximate theory gives rise to analytical correlations for R-h, (tau) over cap (w), and (m) over cap, which would be useful for engineers. (C) 2021 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    An improvement of methods for solving the CUPL-Toeplitz linear system

    Zhang, XingJiang, XiaoyuJiang, ZhaolinByun, Heejung...
    7页
    查看更多>>摘要：In this paper, matrix order-reduction algorithms are realized to solve the CUPL-Toeplitz linear system. Firstly, we describe order-reduction algorithms for the multiplication of real skew-circulant matrix or complex circulant matrix and vector. Secondly, based on the two fast approaches [1] through splitting the CUPL-Toeplitz matrix into a Toeplitz matrix subtract a low-rank matrix, we propose new fast Toeplitz solvers to reduce the amount of calculation. Finally, numerical experiments are given to show the performance of the proposed algorithms. (c) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Refinements of bounds for tails of compound distributions and ruin probabilities

    Chadjiconstantinidis, StathisXenos, Panos
    27页
    查看更多>>摘要：In this paper we derive lower bounds for right-tails of compound geometric distributions and ruin probabilities in the classical compound Poisson risk model in the heavy-tailed cases using the truncated Lundberg condition, which improve all the corresponding known lower bounds. Some upper bounds are also derived. Examples are given and numerical comparison for ruin probabilities when the adjustment coefficient does not exist are also considered, illustrating the effectiveness of the proposed new bounds. In addition, several bounds for tails of negative binomial distributions are obtained in terms of the tail of compound geometric distributions as well as bounds in the heavy-tailed cases. Also, some bounds for the stop-loss premium associated with compound negative binomial distributions are given. Using Chernoff's upper bounds we derive two-sided bounds for tails of compound Poisson distributions. Finally, two-sided bounds are given for tails of compound logarithmic distributions in the heavy-tailed cases. (C) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Stability of stochastic nonlinear delay systems with delayed impulses

    Cao, WenpingZhu, Quanxin
    9页
    查看更多>>摘要：In this paper, we study the input-to-state stability of a class of stochastic delay differential equations with delay impulses. We consider the two cases where the continuous stochastic delay system is stable and unstable, and establish different types of stability conditions by using the average dwell time and the vector Lyapunov function method. Finally, two examples are used to verify the validity of our results.(c) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Relaxed stabilization synthesis of discrete-time nonlinear systems with uplink data loss based on a novel online evaluation mechanism

    Xie, XiangpengShen, XichengPeng, Chen
    11页
    查看更多>>摘要：The problem of promoting the adaptability to uplink data loss for nonlinear plant is addressed via developing the fuzzy gain-scheduling stabilization law based on a novel online evaluation mechanism. Different from those previous methods, the proposed online evaluation mechanism is dependent not only the current-time but also the past-time normalized fuzzy weighting functions, and thus much more information can be absorbed and utilized in the process of stabilization synthesis by introducing extra free matrices than before. More importantly, an additional constraint is for the first time proposed for updating the plant status instantly so that critical replacement operations can be implemented for reducing the conservativeness of the designing conditions. Therefore, the adaptability to uplink data loss is improved evidently and thus the worse communication quality of uplink channel is bearable in this study. Finally, the advantages relative to those reported ones are tested and validated through benchmark numerical comparisons.(c) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Epidemic dynamics on higher-dimensional small world networks

    Wang, HaiyingMoore, Jack MurdochSmall, MichaelWang, Jun...
    20页
    查看更多>>摘要：Dimension governs dynamical processes on networks. The social and technological networks which we encounter in everyday life span a wide range of dimensions, but studies of spreading on finite-dimensional networks are usually restricted to one or two dimensions. To facilitate investigation of the impact of dimension on spreading processes, we define a flexible higher-dimensional small world network model and characterize the dependence of its structural properties on dimension. Subsequently, we derive mean field, pair approximation, intertwined continuous Markov chain and probabilistic discrete Markov chain models of a COVID-19-inspired susceptible-exposed-infected-removed (SEIR) epidemic process with quarantine and isolation strategies, and for each model identify the basic reproduction number R-0, which determines whether an introduced infinitesimal level of infection in an initially susceptible population will shrink or grow. We apply these four continuous state models, together with discrete state Monte Carlo simulations, to analyse how spreading varies with model parameters. Both network properties and the outcome of Monte Carlo simulations vary substantially with dimension or rewiring rate, but predictions of continuous state models change only slightly. A different trend appears for epidemic model parameters: as these vary, the outcomes of Monte Carlo change less than those of continuous state methods. Furthermore, under a wide range of conditions, the four continuous state approximations present similar deviations from the outcome of Monte Carlo simulations. This bias is usually least when using the pair approximation model, varies only slightly with network size, and decreases with dimension or rewiring rate. Finally, we characterize the discrepancies between Monte Carlo and continuous state models by simultaneously considering network efficiency and network size. (C) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Three-dimensional pattern dynamics of a fractional predator-prey model with cross-diffusion and herd behavior

    Bi, ZhiminLiu, ShutangOuyang, Miao
    18页
    查看更多>>摘要：In this paper, we study the pattern dynamics in a spatial fractional predator-prey model with cross fractional diffusion, herd behavior and prey refuge. In this model, herd behavior exists in the population of predators and the prey. The spatial dynamics of the system are obtained through appropriate threshold parameters, and a series of three-dimensional patterns are observed, such as tubes, planar lamellae and spherical droplets. Specifically, linear stability analysis is applied to obtain the conditions of Hopf bifurcation and Turing instability. Then, by utilizing the central manifold reduction theory analysis, the amplitude equation near the critical point of Turing bifurcation is deduced to study the selection and stability of pattern formation. The theoretical results are verified by numerical simulation.(c) 2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    A collocation method to solve the parabolic-type partial integro-differential equations via Pell-Lucas polynomials

    Yuzbasi, SuayipYildirim, Gamze
    19页
    查看更多>>摘要：In this paper, a new collocation method based on the Pell-Lucas polynomials is presented to solve the parabolic-type partial Volterra integro-differential equations. According to the method, it is assumed that the solution of this equation is in the form & nbsp;u(2N) (x, t)& nbsp; expressionpproximexpressiontely equexpressionl to & nbsp;sigma(N & nbsp;)(n=0)sigma(N & nbsp;)(s=0)a(n,s)Q(n,s), Q(n,s) (x, t) = Q(n) (x)Q(s) (t)& nbsp;which depends on the Pell-Lucas polynomials. Next, the matrix representation of the solution is written. Using this matrix form, the matrix representations of the partial derivatives, the matrix representations of the Volterra integral part and the matrix forms of the conditions are also constituted. All obtained matrix forms are substituted in the equation and its conditions. Using equally spaced collocation points in matrix forms of this equation and initial conditions, the equation is reduced to a system of algebraic equations. The solution of this system gives the coefficients of the assumed solution. Additionally, the error analysis for the method is presented. According to this, an upper bound of the errors is determined. Also, the error estimation is made with the help of the residual function. Moreover, the residual improvement technique is also applied. Then, all these procedures are then supported with the examples. The results obtained from these examples are clearly tabulated and graphed. An important aspect of this study is to compare the obtained results with the present method with other results in the literature. (C)& nbsp;2022 Elsevier Inc. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier