Mathematics and Computers in Simulation最新文献_第2页

Impact of COVID-19 lockdown in short-term load forecasting COVID-19封锁对短期负荷预测的影响

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-05-01 DOI: 10.1016/j.matcom.2025.04.035

Miguel López, Sergio Valero, Carolina Senabre

{"title":"Impact of COVID-19 lockdown in short-term load forecasting","authors":"Miguel López, Sergio Valero, Carolina Senabre","doi":"10.1016/j.matcom.2025.04.035","DOIUrl":"10.1016/j.matcom.2025.04.035","url":null,"abstract":"<div><div>Accurate prediction of electrical demand is crucial for the efficient operation of power systems. However, the unprecedented activity restrictions imposed during the pandemic led to unforeseen disruptions in electrical consumption, challenging the predictive capabilities of existing systems. This phenomenon was widespread, affecting power systems globally, as evidenced by analyses of the Spanish electricity grid presented in this paper. The precision of prediction systems significantly diminished upon the implementation of activity restrictions. This article offers an in-depth analysis of the impact on prediction accuracy in the Spanish context. Moreover, it proposes a method to identify situations where the prediction system is out of control, necessitating corrective measures. The paper introduces a straightforward corrective measure that reduces errors during out-of-control periods. It is designed as an addition to the existing forecast model, modifying its output when an out-of-control situation is reached. The results suggest that further investigation could substantially mitigate the impact of such events and enhance prediction system resilience.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 344-354"},"PeriodicalIF":4.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143949031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Phase field-lattice Boltzmann model for axisymmetric two-phase ferrofluid flows 轴对称两相铁磁流体流动的相场晶格玻尔兹曼模型

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-30 DOI: 10.1016/j.matcom.2025.04.034

Yuqi Zhu , Shiting Zhang , Yang Hu , Xiaoqiang Yue , Shi Shu , Qiang He , Decai Li

{"title":"Phase field-lattice Boltzmann model for axisymmetric two-phase ferrofluid flows","authors":"Yuqi Zhu , Shiting Zhang , Yang Hu , Xiaoqiang Yue , Shi Shu , Qiang He , Decai Li","doi":"10.1016/j.matcom.2025.04.034","DOIUrl":"10.1016/j.matcom.2025.04.034","url":null,"abstract":"<div><div>In this paper, a phase field-based lattice Boltzmann model is developed to simulate axisymmetric two-phase ferrofluid flows. The three-population multi-relaxation time lattice Boltzmann models are constructed to solve the conservative Allen-Cahn phase field equation, the velocity-based Navier-Stokes equations, and the magnetic scalar potential equation. To deal with axisymmetric effects, some appropriate equilibrium distribution functions and discrete source/forcing terms are given. The Chapman-Enskog analysis is used to show the consistencies between the present newly proposed multi-relaxation time flow field lattice Boltzmann model and macroscopic governing equations. In the numerical validation section, the Laplace law and a sphere in a uniform magnetic field were simulated, which the simulation results show good agreement with the analytical solutions. Then several typical problems such as ferrofluid droplet deformation, Rayleigh–Plateau instability, two bubbles merging and bubble rising in ferrofluids are numerically studied to explore the mechanism of phase field interface dynamics in two-phase ferrofluid flows. As the density ratio between the two phases ranges from 1.975 to 1000, and the dynamic viscosity ratio ranges from 1 to 200, the numerical simulation results are satisfactory. This indicates that the proposed model can effectively deal with complex two-phase ferrofluid flows with large density and viscosity ratios.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 281-315"},"PeriodicalIF":4.4,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

News of IMACS IMACS新闻

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-28 DOI: 10.1016/S0378-4754(25)00162-4

引用次数: 0

IMACS Calendar of Events IMACS事件日历

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-28 DOI: 10.1016/S0378-4754(25)00163-6

引用次数: 0

Hopf bifurcation in a generalized Goodwin model with delay 一类时滞广义Goodwin模型的Hopf分岔

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-28 DOI: 10.1016/j.matcom.2025.04.012

Eysan Sans , Melisa Akdemir , Ayse Tiryakioglu , Ayse Peker-Dobie , Cihangir Ozemir

{"title":"Hopf bifurcation in a generalized Goodwin model with delay","authors":"Eysan Sans , Melisa Akdemir , Ayse Tiryakioglu , Ayse Peker-Dobie , Cihangir Ozemir","doi":"10.1016/j.matcom.2025.04.012","DOIUrl":"10.1016/j.matcom.2025.04.012","url":null,"abstract":"<div><div>Goodwin’s model is a cornerstone in the study of dynamical systems within macroeconomics, explaining the interaction between employment ratio and wage share in a closed economy. Analogous to predator–prey dynamics in mathematical economics, the Goodwin model, despite its simplicity, effectively captures the periodic behavior of state variables over specific time intervals. By relaxing the initial assumptions, the model can be adapted to account for more complex economic scenarios. In this article, we study a higher-dimensional extension of the Goodwin model that incorporates variable capacity utilization and capital coefficient alongside employment ratio and wage share. In particular instances, the wage share and employment rate equations decouple from the overall system. For these cases, by incorporating a delay effect in the Phillips curve, we demonstrate that while the equilibrium of the generalized system remains stable within certain parameter domains in the absence of delay, the introduction of delay can induce a Hopf bifurcation, leading to periodic oscillations. We analytically derive the critical delay parameter value that destabilizes the equilibrium point via a Hopf bifurcation.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 86-106"},"PeriodicalIF":4.4,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

N-policy for redundant machining system with double retrial orbits using soft computing techniques 基于软计算技术的双重审轨道冗余加工系统n策略

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-27 DOI: 10.1016/j.matcom.2025.04.025

Vijay Pratap Singh , Madhu Jain , Richa Sharma

{"title":"N-policy for redundant machining system with double retrial orbits using soft computing techniques","authors":"Vijay Pratap Singh , Madhu Jain , Richa Sharma","doi":"10.1016/j.matcom.2025.04.025","DOIUrl":"10.1016/j.matcom.2025.04.025","url":null,"abstract":"<div><div>The present study is concerned with the performance prediction of a double retrial orbit redundant repairable machining system. Both primary and secondary orbits are available as waiting/buffer space for the failed units. In these orbits, the failed units can reside and make re-attempts for the repair. As per N-policy, if there are no units in the orbits for the repairing job, the repairman goes on vacation and further starts the repair job when N-failed units are accumulated. The objective of this investigation is to evaluate the transient and steady-state distributions of the queue length of failed units under N-policy. The matrix analytic and matrix recursive methods are utilized for solution purpose while an adaptive neuro-fuzzy inference system (ANFIS) is employed for validating the feasibility of designing the AI-based controller. The harmonic search (HS) and particle swarm optimization (PSO) methods have been implemented for the cost optimization purpose so as to evaluate the optimal design parameters. The outputs of study provides critical insights into optimal system performance and improving the repair policy. Furthermore, a practical application of this investigation is demonstrated in a telecommunications network traffic system, where the proposed methods can be utilized to manage the maintenance issues of routers in the network traffic.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 42-69"},"PeriodicalIF":4.4,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Composite likelihood expectation–maximization algorithm for the first-order multivariate integer-valued autoregressive model with multivariate mixture distributions 多元混合分布一阶多元整值自回归模型的复合似然期望最大化算法

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-26 DOI: 10.1016/j.matcom.2025.04.017

Weiyang Yu, Haitao Zheng

引用次数: 0

Local convergence analysis of L1/finite element scheme for a constant delay reaction-subdiffusion equation with uniform time mesh 等时间网格常延迟反应-次扩散方程L1/有限元格式的局部收敛性分析

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-26 DOI: 10.1016/j.matcom.2025.04.014

Weiping Bu, Xin Zheng

{"title":"Local convergence analysis of L1/finite element scheme for a constant delay reaction-subdiffusion equation with uniform time mesh","authors":"Weiping Bu, Xin Zheng","doi":"10.1016/j.matcom.2025.04.014","DOIUrl":"10.1016/j.matcom.2025.04.014","url":null,"abstract":"<div><div>The aim of this paper is to develop a refined error estimate of L1/finite element scheme for a reaction-subdiffusion equation with constant delay <span><math><mi>τ</mi></math></span> based on the uniform time mesh. Under the non-uniform multi-singularity assumption of exact solution in time, the local truncation error of L1 scheme is investigated. Then we introduce a fully discrete finite element scheme of the considered problem. In order to investigate the error estimate, a novel discrete fractional Grönwall inequality with delay term is proposed, which does not include the increasing Mittag-Leffler function. By applying this Grönwall inequality, we obtain a local error estimate of the above fully discrete scheme without including the Mittag-Leffler function. In particular, the convergence result implies that, for the considered time interval <span><math><mrow><mo>(</mo><mrow><mo>(</mo><mi>i</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow><mi>τ</mi><mo>,</mo><mi>i</mi><mi>τ</mi><mo>]</mo></mrow></math></span>, although the convergence rate in the sense of maximum time error is low for the first interval, i.e. <span><math><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow></math></span>, it will be improved as the increasing <span><math><mi>i</mi></math></span>, which is consistent with the factual assumption that the smoothness of the solution will be improved as the increasing <span><math><mi>i</mi></math></span>. Finally, we present some numerical tests to verify the developed theory.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 70-85"},"PeriodicalIF":4.4,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dynamical system modelling for picture fuzzy multi-criteria public opinion on transportation infrastructure 交通基础设施舆情的图象模糊多准则动态系统建模

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-26 DOI: 10.1016/j.matcom.2025.04.024

Lanndon Ocampo , Dharyll Prince Abellana , Julius Selle , Rhoda Namoco , Fatima Maturan , John Kevin Padro , Samantha Shane Evangelista

{"title":"Dynamical system modelling for picture fuzzy multi-criteria public opinion on transportation infrastructure","authors":"Lanndon Ocampo , Dharyll Prince Abellana , Julius Selle , Rhoda Namoco , Fatima Maturan , John Kevin Padro , Samantha Shane Evangelista","doi":"10.1016/j.matcom.2025.04.024","DOIUrl":"10.1016/j.matcom.2025.04.024","url":null,"abstract":"<div><div>This work presents a novel approach for modelling dynamic fuzzy multi-criteria decision-making problems. We consider a problem where members of a population evaluate alternatives under a given criterion by taking either of three options: agree, neutral, or disagree. The physical partitioning of the population gives rise to the notion of describing the performance of alternatives under multiple criteria as Picture fuzzy sets, with operations that can aggregate multi-criteria performance into real numbers. Then, the dynamic performance of the alternatives is described by considering the interactions of the partitions of the populations, modelled as a system of differential equations constructed for each criterion. We provided proof of the basic properties of each system, including nonnegativity and boundedness of solutions, and presented the points of convergence. Parameter values were estimated by performing time-series clustering. The proposed approach was applied numerically in modelling multi-criteria public opinion of a bus rapid transit project—a single alternative, where nine criteria were evaluated. Initial performance values under multiple criteria were obtained using a survey, and four scenarios representing possible government interventions were evaluated. The time-dependent performance profiles of the public about the project were obtained, with insights indicating the efficacy of the proposed model.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"236 ","pages":"Pages 455-474"},"PeriodicalIF":4.4,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143899208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hierarchical Newton iterative identification methods for a class of input multi-piecewise Hammerstein models with autoregressive noise 一类具有自回归噪声的输入多分段Hammerstein模型的层次牛顿迭代辨识方法

IF 4.4 2区数学

Mathematics and Computers in Simulation Pub Date : 2025-04-25 DOI: 10.1016/j.matcom.2025.04.019

Yamin Fan , Ximei Liu , Meihang Li

{"title":"Hierarchical Newton iterative identification methods for a class of input multi-piecewise Hammerstein models with autoregressive noise","authors":"Yamin Fan , Ximei Liu , Meihang Li","doi":"10.1016/j.matcom.2025.04.019","DOIUrl":"10.1016/j.matcom.2025.04.019","url":null,"abstract":"<div><div>Advancements in mathematical theories and applied technologies have driven research on modeling and identification of complex nonlinear systems, yet existing models still face challenges in terms of model structures, accuracy of parameter estimation, and efficiency. In this study, we present a class of input multi-piecewise Hammerstein models that utilize piecewise-linear function to capture arbitrary nonlinear characteristics. By employing the key term separation technique and the Newton iterative algorithm for parameter estimation, a generalized Newton iterative algorithm is proposed, which overcomes the limitations of conventional identification methods in handling complex nonlinearities. Additionally, considering the computational load caused by the numerous parameters in multi-piecewise linear function and the inversion of the Hessian matrix in the Newton iterative algorithm, the hierarchical identification principle is introduced and a three-stage generalized Newton iterative algorithm is derived for enhancing the computational efficiency. The feasibility of the presented methods are demonstrated through a simulation example.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"237 ","pages":"Pages 247-262"},"PeriodicalIF":4.4,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0