查看更多>>摘要：This paper employs fractional calculus (FC) for modeling three-dimensional prey-predator populations model. This study uses an eco-epidemiological system in which the prey disease is constructed as a susceptible-infected (SI) disease. The Caputo and Caputo-Fabrizio (CF) operators are consolidated into this model and the existence of a solution is explored. The model is evaluated for uniqueness under what conditions it provides a unique solution. Based on the singular kernel of the Caputo operator, we investigate the properties of the proposed model and show it can be stable locally. We developed maximum bifurcation diagrams to analyze the dynamics of the epidemiological model as varying transmission rates beta and attack rates b(1) . To simulate the dynamics of proposed fractional systems, we employed the ToufikAt angana (TA) numerical technique with the Caputo operator. Moreover, we present another numerical approach based on Adams-Bashforth (AB) technique with CF operators. Results of the numerical analysis show that diverse non-integer operator alternatives to the eco-epidemiological predator-prey model result in a range of dynamical behaviors. (c) 2021 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Numerous social problems can be directly related to poverty, and its elimination is thus often declared a grand challenge in modern human societies. Nevertheless, it is difficult to shake the belief that certain fractions of the population would like to see it maintained to ensure the availability of cheap workforce and its readiness to do the hardest jobs, as well as to keep the prices of natural resources in the afflicted countries as low as possible. Here we show, however, that by allowing low-income individuals to escape poverty, either by means of mobility to pursue potential opportunities in remote areas or by ending dilemmas through social learning in local areas, greatly increases cooperation and thus has the potential to raise the social capital. In particular, we find that mobility of low-income individuals can promote cooperation when the per capita mobility rate is as low as 10(-3) in the order of magnitude as long as network reciprocity is still active. This synergy between network reciprocity and mobility is due to the emergence of large cooperative clusters that are in this size impossible without mobility. Moreover, we find that the mobility of defectors undermines cooperation, but only a few defectors actually move as they are typically well off when surrounded by cooperators. On the contrary, the higher the cooperation level, the greater the proportion of low-income cooperator that move. Our research thus shows that by providing ways out of poverty for individuals can raise whole societies out of economic gridlocks by elevating cooperation levels. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.& nbsp;
查看更多>>摘要：The study of multifractal properties is one of the current scopes in the analysis of complex networks. Last decade, several multifractal algorithms have been proposed, both adding new approaches and improving their accuracy or time consumption. One of the methods that provide more advantages is the sandbox method, which does not require to solve the NP-hard problem of covering the whole networks in non-overlapping boxes by means of an approximation. Unlike the box-covering methods, the sandbox method allows the complete reconstruction of the multifractal dimension functions D(q). However, sandbox algorithms for complex networks have been developed exclusively from a Fixed-Size approach. Hence, the applicability of the Fixed-Mass approach with a sandbox procedure (FM-SB) in this framework is explored for the first time. The accuracy of the FM-SB is evaluated in deterministic networks, and subsequently applied for determining multifractal properties in synthetic networks generated by the Barabasi-Albert model (scale-free) and the Watts-Strogatz model (small-world and random), as well as in real ones. The FM-SB algorithm is capable to completely characterize multifractal properties in these networks, like the mass exponent function and generalized fractal dimensions. This work completes the algorithms proposed in the literature for the multifractal analysis of unweighted complex networks, using a Fixed-Mass procedure. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：The use of non-ideal features of semiconductor devices is an interesting option for implementations of nonlinear electronic systems. This paper analyzes the Chua circuit with nonlinearity based on the exponential hyperbolic characteristics of semiconductor devices. The stability analysis using describing functions predicts the dynamics of this nonlinear system, which is corroborated by numerical investigations and experimental results. The dynamic behaviors and bifurcations of this nonlinear system are mapped in parameter space in order to create a base for studies, analyses, and designs. The dynamic behavior of the experimental high speed implementation of this version of Chua circuit differs from the expected dynamics for a conventional Chua circuit due to effects of unmodelled non-idealities of the real semiconductor devices, displaying that new and different dynamics for the Chua circuit can be obtained exploring different nonlinearities. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We study gap solitons and nonlinear Bloch waves in the nonlinear fractional order quantum coupler modulated by periodic potential. The results show that the gap solitons match almost perfectly with nonlinear Bloch waves. The stability of the solitons is carefully investigated by the linear stability analysis and the real-time evolution method. We find that the variations of Levy index and chemical potential have a profound impact on the existence, profile and stability of solitons. The stability enhances with the increase of the Levy index alpha or potential in the corresponding parameter interval. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：This paper is concerned with the Ulam-Hyers stability (UHs) of Caputo type fuzzy fractional differential equations (FFDEs) with time-delays. By applying Schauder's fixed point theorem and a hypothetical condition, we explore the existence of the solutions. In addition, by using Banach contraction principle, we show the uniqueness of the solution of the system. What is more, we consider the UHs with aid of generalized Gr o spacing diaeresis nwall inequality. Finally, an example with numerical simulation is provided to visualize the theoretical results.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A B S T R A C T Hybridization of individual models emerged as a predominant alternative for increasing accuracy in time series forecasting. The literature is abundant on providing hybrid methods aiming at improving forecasting accuracy and comprehensive pattern recognition. The principle behind all hybrid models' success is improving forecasting accuracy. One of the most widely used combination methods in line with the common objective of the hybridization concept is a parallel approach in which the forecasting model applied on the original time series and the weighted forecasts generate the final hybrid result. In parallel hybridization, the key is how to select the weights of each model. The weighting algorithm plays a significant role and the degree of accuracy in such models directly depends on it. However, the traditional parallel hybrid models developed to enhance forecasting accuracy employing multiple individual models simultaneously, faced some limitations, e.g., missing considering the reliability and generalization criteria of developed hybrid models. From the literature, it is observed that none of the parallel hybrid modes proposed in the literature focused on the improving reliability of the hybrid model to obtain better model generalization for unseen data. Thus, the main objective of this study is to propose a novel class of hybrid models named reliability-based parallel hybridization (RPH). The main goal of RPH methodology is to improve hybrid models' reliability rather than accuracy using a new reliable-based weighting algorithm (RWA). The RWA instead of traditional accuracy-based weighting algorithms in which error measurements are minimized, the reliability of hybrid models is maximized to determine the exact optimum weights of individual models. The RWA computed the optimum weights of forecasts regarding minimizing performance changing of the hybrid model in the validation data set. The RPH model proposed two crucial concepts for the first time: (1) Bringing up reliability in hybridization procedure (2) Proposing a novel reliable-based weighting algorithm to maximize the generalization power of the hybrid model. The bi-component version of the RPH model is proposed in this paper using ARIMA and MLP models. The forecasting power of the proposed PRH constructed based on ARIMA and MLP models is verified using the benchmark data sets e.g. the closing of Standard and Poor's 500 indexes (S&P500), the closing of the Shenzhen Integrated Index (SZII), and the opening of the Dow Jones Industrial Average Index (DJIAI). The experimental results indicate that the forecasting performance of the RPH model is much better than traditional accuracy-based parallel hybrid models.(c) 2022 Elsevier Ltd. All rights reserved.
Asamoah, Joshua Kiddy K.Okyere, EricYankson, ErnestOpoku, Alex Akwasi...
38页
查看更多>>摘要：The purpose of analysing the transmission dynamism of Q fever (Coxiellosis) in livestock and incorpo-rating ticks is to outline some management practices to minimise the spread of the disease in livestock. Ticks pass coxiellosis from an infected to a susceptible animal through a bite. The faecal matter can also contain coxiellosis, thus contaminating the environment and spreading the disease. First, a nonlinear integer order mathematical model is developed to represent the spread of this infectious disease in live -stock. The proposed integer model investigates the positivity and boundedness, disease equilibria, basic reproduction number, bifurcation, and sensitivity analysis. Through mathematical analysis and numerical simulations, it shows that if the environmental transmission and the effective shedding rate of coxiella burnetii into the environment by both asymptomatic and symptomatic livestock are zero, then the usual threshold hold and it produces forward bifurcation. It is noticed that an increase in the recruitment rate of ticks produces backward bifurcation. And also, it is seen that an increase in the natural decay rate of the bacterial in the environment reduces the backward bifurcation point. Furthermore, to take care of the memory aspect of ticks on their host, we modified the initially proposed integer order model by introducing Caputo, Caputo-Fabrizio, Atangana-Baleanu fractional differential operators. The existence and uniqueness of these three newly developed fractional-order differential models are shown using the Banach fixed point theorem. Numerical trajectories are obtained for each of the fractional-order math-ematical models. The trajectory of some fractional orders converges to the same endemic equilibrium point as the integer order. Finally, it is seen that the Atangana-Baleanu fractional differential operator captures more susceptibilities and fewer infections than the other operators.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Microfluidic technology has great advantages in the precise manipulation of micro and nanoparticles, and the separation method based on deterministic lateral displacement separation technology has attracted much attention due to its high resolution, high throughput, and strong size dependence. In this paper, starting from the principle of deterministic lateral displacement sorting and taking control of the flow velocity distribution and pressure difference in the gap as the key points, a new shape of inverted heart-shaped micro-columns with a smaller critical size was designed to separate white blood cells and red blood cells. Under the premise of considering the two-way coupling, the trajectory of the particles was simulated, the critical size of the array was determined, and the influence of the flow velocity particle sorting was discussed. Finally, the separation process of the two kinds of cells was simulated, and the separation of the two kinds of cells was successfully realized. This work has laid a certain theoretical foundation for the rapid diagnosis of diseases in practical applications.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Optical fiber communication system is one of the supporting systems in the modern internet age. We investigate an M-coupled variable-coefficient nonlinear Schrodinger system, which describes the simultaneous pulse propagation of the M-field components in an inhomogeneous optical fiber, where M is a positive integer. With respect to the complex amplitude of the jth-field (j = 1, ..., M) component in the optical fiber, we construct an n-fold Darboux transformation, where n is a positive integer. Based on the n-fold Darboux transformation, we obtain some one- and two-fold localized wave solutions for the above system with the mixed defocusing-focusing-type nonlinearity and M = 2. We acquire the infinitely-many conservation laws. Via such solutions, we obtain some vector gray solitons, interactions between the two vector parabolic/cubic gray solitons, and interactions between the vector parabolic/cubic breathers and gray solitons with different beta(z), gamma(z) and delta(z), the coefficients of the group velocity dispersion, nonlinearity and amplification/absorption. It can be found that delta(z) affects the backgrounds of the breathers and gray solitons. (C) 2021 Elsevier Ltd. All rights reserved.
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