查看更多>>摘要：Mathematical modeling is an important tool to study the role of delay in neural systems and to evaluate its effects on the signaling activity of coupled neurons. Models for delayed neurons are often used to represent the dynamics of real neurons, but rarely to assess the energy required to maintain these dynamics. In this work, we address these questions from an energy perspective by considering a pair of Hindmarsh-Rose burst neurons coupled by reciprocal time-delayed coupling with electrical and chemical synapses. We examine the average energy consumption required to maintain cooperative behavior and quantify the contribution of synapses to total energy consumption. We show that unlike electrical coupling, where the time delay appears to reduce the instantaneous average relative weight of the synaptic contribution, in chemical coupling this average synaptic contribution appears to be much higher in delayed coupling than in instantaneous coupling, except at certain values of coupling strength where the instantaneous synaptic contribution is more important. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We derive a closed-form solution for pricing geometric Asian rainbow options under the mixed geometric fractional Brownian motion (FBM). In particular, the number of underlying assets is allowed to be arbitrary, and fully correlated fractional Brownian motions are taken into account. The analytical solution obtained is used as a control variate for Monte Carlo based computations of the price of arithmetic Asian rainbow options. Numerical experiments are presented in which options on two, three, four and ten underlying assets are considered. Results reveal that the proposed control variate technique is very effective to reduce the variance of theMonte Carlo estimator and yields a reliable approximation of the Asian rainbow option price. (C) 2022 Published by Elsevier Ltd.
查看更多>>摘要：A hybrid of Muntz-Legendre polynomials (MLPs) and block-pulse functions (BPFs) is defined and carried out to analyze nonlinear fractional optimal control problems consisting of multiple delays. Instead of using the Caputo fractional derivative, an alternative fractional derivative operator is utilized. The primary optimization problem reduces to an alternative optimization one involving unknown parameters. For this purpose, the fractional Legendre-Gauss quadrature formula is utilized for approximating the associated cost functional and the fractional Legendre-Gaussian nodes are taken as the collocation points. Some new aspects of the proposed basis are demonstrated to verify the effectiveness of the proposed approach based on theMuntz-Legendre basis (MLB) against the classical orthogonal bases. The simulation results certify the feasibility and reliability of the proposedmethod. Numerous fractional control problems, e.g., bang-bang controls and control systemswith any irregularities in the structure of control input can be handled successfully by employing the new fractional basis. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Based on the special structure of cyclic symmetric systems and the characteristics of conservative systems, a new method for constructing cyclic symmetric conservative chaotic systems(CSCCSs) is proposed, which can be used to construct three-dimensional(3D) system and above. Taking 3D system, four-dimensional(4D) system and five-dimensional(5D) systemas examples, the construction method is introduced, and the conservation and chaotic features are verified by the determination of divergence, equilibrium points, and Lyapunov exponents(LEs), which proves the feasibility of the new method. Then, we carry out the improvement of the offset boosting control for the three constructed CSCCSs. The results show that this new control method can change the average value of the corresponding state variables, offset the variables and realize the polarity conversion of the signal. Finally, the new system is implemented by using the digital signal processor(DSP) hardware platform. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A necessary-sufficient condition for the existence and non-existence of global solutions to the following semilinear parabolic equations u(t) = delta u + psi(t)u(p), in omega x (0, t*), has remained as an open problem for a few decades. This paper discuss the necessary-sufficient condition for the existence and non-existence of global solutions of the above equations on networks for more general source term psi(t)f(u) under various boundary conditions. The purpose of this paper is to prove that there is no global solution for any initial data if and only if the function f satisfies integral(infinity)(0)psi(t)f epsilon?S(t)u0?(infinity/)?S(t)u(0)?(infinity )dt = infinity for every epsilon > 0, where (S(t))(t >= 0) is the heat semigroup on networks with the corresponding boundary condition. (C) 2022 Elsevier Ltd. All rights reserved.
Paul, Peng WenSadiq, Muhammad TariqAkbari, HesamSiuly, Siuly...
12页
查看更多>>摘要：Alcoholism is a severe disorder that leads to brain problems and associated cognitive, emotional and behavioral impairments. This disorder is typically diagnosed by a questionnaire technique known as CAGE that measures the severity of a drinking problem. This isa time-consuming, onerous, error-prone, and biased method. Hence, this article aims to establish a novel framework for automatic detecting alcoholism using electroencephalogram (EEG) signals, which can mitigate these issues and help clinicians and researchers. In the proposed framework, firstly, we explore the phase space dynamic of EEG signals for visualizing the chaotic nature and complexity of EEG signals. Secondly, we discover thirty-four graphical features for decoding the chaotic behavior of normal and alcoholic EEG signals. After that, we investigate thirteen feature selection in combination with eleven machine learning and neural network classifiers to select the best combination for the development of an efficient framework. The experimental results reveal that the proposed method achieves the highest classification performance involving 99.16% accuracy, 100% sensitivity and 98.36% specificity for the twenty-three features selected by Henry gas solubility optimization with feedforward neural network (FFNN). The proposed system provides a new visual biomarker for alcoholic detection. In addition, we developed two new indexes using clinically relevant features to distinguish normal and alcoholic classes with a single number. These indexes can help medical teams, commercial users as well as product developers to develop a real-time system. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：In recent years, the division of labor game has received widespread attention, however, the time delay in payoffs has been ignored. Hence, in this paper, we consider that there is a time delay for the player to gain the payoffs in the game, and the delay in payoffs leads to a Hopf bifurcation. When the time delay is greater than the critical time delay, the replicator dynamics oscillates near the equilibrium point, the critical time delay is determined by the cost difference between the two tasks and the cooperation benefits between the two players. We obtain the expression of the critical time delay by applying the characteristic equation analysis method, and clearly analyze various cases through observation and numerical simulation. With the increase of time delays, the dynamic system shows a transition from asymptotic stability to oscillation near equilibrium.
查看更多>>摘要：The exponential growth of space exploration, and of nuclear energy applications, leads to optimize the material distribution in a shield to protect against hypervelocity impacts and radiation. In order to find the optimal distribution, we study multilayer and porous structures, regular and random, by simulating straight particle trajectories crossing a rectangle filled with a constant mass according to the different structures. These trajectories are analyzed theoretically in multilayer structures and following a Monte Carlo method in porous structures. In this second case, distribution and probability estimators are used to ensure results with almost sure convergence, which indicates that the amount of matter crossed by particles is independent of the underlying structure. However, in regular porous structures, there are singularities given by fractal sets of measure zero that allow a theoretical construction. These fractal sets reveal protection gaps in regular porous structures that make them extremely dangerous for shielding purposes. Furthermore, this result allows to explain X-ray fractal patterns of certain semi-crystalline materials.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We study behavioral change in the context of a stochastic, non-linear consumption model with preference adjusting, interdependent agents. Changes in long-run consumption behavior are modelled as noise induced transitions between coexisting attractors. A particular case of multistability is considered: two fixed points, whose immediate basins have smooth boundaries, coexist with a periodic attractor, with a fractal immediate basin boundary. If a trajectory leaves an immediate basin, it enters a set of complexly intertwined basins for which final state uncertainty prevails. The standard approach to predicting transition events rooted in the stochastic sensitivity function technique due to Mil'shtein and Ryashko (1995) does not apply since the required exponentially stable attractor, for which a confidence region could be constructed, does not exist. To solve the prediction problem we propose a heuristic based on the idea that a vague manifestation of a non-attracting chaotic set (chaotic repellor) -could serve as a surrogate for an attractor. A representation of the surrogate is generated via an algorithm for generating the boundary of an absorbing area due to Mira et al. (1996). Then a confidence domain for the surrogate is generated using the approach due to Bashkirtseva and Ryashko (2019). The intersections between this confidence region and the immediate basins of the coexisting attractors can then be used to make predictions about transition events. Preliminary assessments show that the heuristic indeed explains the transition probabilities observed in numerical experiments. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
查看更多>>摘要：In the wake of COVID-19, mask-wearing practice and self-quarantine is thought to be the most effective means of controlling disease spread. The current study develops an epidemiological model based on the SEIR process that takes into account dynamic human behavior toward those two preventive measures. In terms of quantifying the effect of wearing a mask, our model distinguishes itself by accounting for the effect of self-protection as well as the effect of reducing a potential risk to other individuals in different formulations. Each of the two measures de-rived from the so-called behavior model has a dynamical equation that takes into account the delicate balance between the cost of wearing a mask/self-quarantine and the risk of infection. The dynamical system as a whole contains a social dilemma structure because of whether to commit to preventing measures or seek the possibility of infection-free without paying anything. The numerical result was delivered along the social efficiency deficit, quantifying the extent to which Nash equilibrium has been improved to a social optimal state. PACS numbers Theory and modeling; computer simulation, 87.15.Aa; Dynamics of evolution, 87.23.Kg (c) 2022 Elsevier Ltd. All rights reserved.
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