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Dispersive optical solitons with parabolic law of self-phase modulation and multiplicative white noise

JOURNAL OF OPTICS-INDIA 2025年第2期54卷 353-361页

作者： Elsherbeny, Ahmed M. Ahmed, Manar S. Arnous, Ahmed H. Biswas, Anjan Gonzalez-Gaxiola, O. Yildirim, Yakup Alshomrani, Ali Saleh Ain Shams Univ Fac Engn Dept Phys & Math Engn Cairo 11517 Egypt El Shorouk Acad Higher Inst Engn Dept Phys & Engn Math Cairo Egypt Grambling State Univ Dept Math & Phys Grambling LA 71245 USA King Abdulaziz Univ Ctr Modern Math Sci & their Applicat CMMSA Dept Math Math Modeling & Appl Computat MMAC Res Grp Jeddah 21589 Saudi Arabia Sefako Makgatho Hlth Sci Univ Dept Math & Appl Math Pretoria South Africa Univ Autonoma Metropolitana Cuajimalpa Appl Math & Syst Dept Vasco Quiroga 4871 Mexico City 05348 Mexico Biruni Univ Dept Comp Engn TR-34010 Istanbul Turkiye Near East Univ Math Res Ctr CY-99010 Nicosia Cyprus Univ Kyrenia Fac Arts & Sci CY-99320 Kyrenia Cyprus

The current paper addresses dispersive optical solitons in presence of white noise with third and fourth-order dispersions in addition to the pre-existing chromatic dispersion. The self-phase modulation effect comes from parabolic law. Two integration approaches retrieved the soliton solutions. They are the enhanced Kuddryashov's approach and enhanced direct algebraic method.

关键词： Optical solitons Kudryashov Direct algebraic method Schr & ouml dinger Hirota 060.2310 060.4510 060.5530 190.3270 190.4370

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Accuracy of Reaction Coordinate Based Rate Theories for Modelling Chemical Reactions: Insights From the Thermal Isomerization in Retinal

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JOURNAL OF COMPUTATIONAL CHEMISTRY 2025年第1期46卷 e27529页

作者： Ghysbrecht, Simon Donati, Luca Keller, Bettina G. Free Univ Berlin Dept Biol Chem & Pharm Berlin Germany Free Univ Berlin Dept Math & Comp Sci Berlin Germany Zuse Inst Berlin Modeling & Simulat Complex Proc Berlin Germany

Modern potential energy surfaces have shifted attention to molecular simulations of chemical reactions. While various methods can estimate rate constants for conformational transitions in molecular dynamics simulations, their applicability to studying chemical reactions remains uncertain due to the high and sharp energy barriers and complex reaction coordinates involved. This study focuses on the thermal cis-trans isomerization in retinal, employing molecular simulations and comparing rate constant estimates based on one-dimensional rate theories with those based on sampling transitions and grid-based models for low-dimensional collective variable spaces. Even though each individual method to estimate the rate passes its quality tests, the rate constant estimates exhibit considerable disparities. Rate constant estimates based on one-dimensional reaction coordinates prove challenging to converge, even if the reaction coordinate is optimized. However, consistent estimates of the rate constant are achieved by sampling transitions and by multi-dimensional grid-based models.

关键词： diffusion kramers metadynamics path collective variable rate theory retinal square root approximation umbrella sampling

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A thermodynamically consistent and conservative diffuse-interface model for gas/liquid-liquid-solid flows

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JOURNAL OF COMPUTATIONAL PHYSICS 2025年 532卷

作者： Zhan, Chengjie Liu, Xi Chai, Zhenhua Shi, Baochang Huazhong Univ Sci & Technol Sch Math & Stat Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Inst Interdisciplinary Res Math & Appl Sci Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Hubei Key Lab Engn Modeling & Sci Comp Wuhan 430074 Peoples R China

In this work, a thermodynamically consistent and conservative diffuse-interface model for gas/ liquid-liquid-solid flows is proposed. In this model, a novel free energy for the gas/liquid-liquidsolid system is established according to a ternary phase-field model, and it not only contains the standard bulk and interface free energies for two-phase flows, but also includes some additional terms to reflect the penalty in the solid phase and the wettability on the solid surface. Furthermore, a smooth indicator function of the solid phase is also introduced in the consistent Navier-Stokes equations to achieve a high viscosity in the solid phase, and to preserve the velocity boundary conditions on the solid surface by the force caused by fluid-structure interaction. Based on the proposed diffuse-interface model, the fluid interface dynamics, the fluid-structure interaction, and the wetting property of the solid surface can be described simply and efficiently. Additionally, the total energy is also proved to be dissipative for the two-phase flows in the stationary geometries. To test the present diffuse-interface model, we develop a consistent and conservative lattice Boltzmann method and conduct some simulations. The numerical results also confirm the energy dissipation and good capability of the proposed diffuse-interface model in the study of two-phase flows in complex geometries and two-phase flows with moving particles.

关键词： Phase-field model Energy dissipation Two-phase flows in complex geometries Two-phase flows with moving particles

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A CONSISTENT AND CONSERVATIVE DIFFUSE-DOMAIN LATTICE BOLTZMANN METHOD FOR MULTIPHASE FLOWS IN COMPLEX GEOMETRIES

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2025年第2期47卷 B308-B332页

作者： Liu, Xi Zhan, Chengjie Chen, Ying Chai, Zhenhua Shi, Baochang Huazhong Univ Sci & Technol Sch Math & Stat Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Inst Interdisciplinary Res Math & Appl Sci Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Hubei Key Lab Engn Modeling & Sci Comp Wuhan 430074 Peoples R China

modeling and simulation of multiphase flows in complex geometries are challenging due to the complexity in describing the interface topology changes among different phases and the difficulty in implementing the boundary conditions on the irregular solid surface. In this work, we first developed a diffuse-domain based phase-field model for multiphase flows in complex geometries. In this model, the irregular fluid region is embedded into a larger and regular domain by introducing a smooth characteristic function. Then, the reduction-consistent and conservative phase-field equation for the multiphase field and the consistent and conservative Navier-Stokes equations for the flow field are reformulated as the diffuse-domain based consistent and conservative (DD-CC) equations where some additional source terms are added to reflect the effects of boundary conditions. In this case, there is no need to directly treat the complex boundary conditions on the irregular solid surface, and additionally, based on a matched asymptotic analysis, it is also shown that the DD-CC equations can converge to the original governing equations as the interface width parameter tends to zero. Furthermore, to solve the DD-CC equations, we proposed a novel and simple lattice Boltzmann (LB) method with a Hermite-moment-based collision matrix which can not only keep consistent and conservation properties, but also improve the numerical stability with a flexible parameter. With the help of the direct Taylor expansion, the macroscopic DD-CC equations can be recovered correctly from the present LB method. Finally, to test the capacity of the LB method, several benchmarks and complex problems are considered, and the numerical results show that the present LB method is accurate and efficient for the multiphase flows in complex geometries.

关键词： diffuse-domain method consistent and conservative phase-field method lattice Boltzmann method multiphase flows

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APPLIED mathEMATICS AND OPTIMIZATION 2025年第1期91卷 1-40页

作者： Campi, Luciano Cannerozzi, Federico Cartellier, Fanny Univ Milan Dept Math Federigo Enriques Via Saldini 50 I-20133 Milan Italy Inst Polytech Paris Ecole Polytech CNRS Ctr Res Econ & Stat CREST F-91120 Palaiseau France Univ Zurich Dept Math Modeling & Machine Learning Winterthurerstr 190 CH-8057 Zurich Switzerland Bielefeld Univ Ctr Math Econ IMW Univ Str 25 D-33615 Bielefeld Germany

Coarse correlated equilibria (CCE) are a good alternative to Nash equilibria (NE), as they arise more naturally as outcomes of learning algorithms and as they may exhibit higher payoffs than NE. CCEs include a device which allows players' strategies to be correlated without any cooperation, only through information sent by a mediator. We develop a methodology to concretely compute mean field CCEs in a linear-quadratic mean field game (MFG) framework. We compare their performance to mean field control solutions and mean field NE (usually named MFG solutions). Our approach is implemented in the mean field version of an emission abatement game between greenhouse gas emitters. In particular, we exhibit a simple and tractable class of mean field CCEs which allows to outperform very significantly the mean field NE payoff and abatement levels, bridging the gap between the mean field NE and the social optimum obtained by mean field control.

关键词： Mean field games Coarse correlated equilibrium Mean field Nash equilibrium Mean field control Emission abatement game

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Electrochemical reduction behavior of Si(IV) ions in LiF-SiO2 and KF-SiO2 melts at 1173 K

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JOURNAL OF FLUORINE CHEMISTRY 2025年 283卷

作者： Suzuki, Yuta Goto, Takuya Doshisha Univ Harris Sci Res Inst Kyotanabe Kyoto 6100394 Japan Doshisha Univ Grad Sch Sci & Engn Dept Sci Environm & Math Modeling Kyotanabe Kyoto 6100394 Japan

Metal electrodeposition from metal oxides is beneficial not only in the terrestrial metal smelting process but also in the process of recovering metals from minerals on the Moon and Mars. In the electrochemical process, a binary melt of metal oxide and metal fluoride can be a promising reaction media for constructing a practical electrolytic system that allows metal recovery directly from metal oxide at lower temperatures. In this study, the electrochemical reduction behavior of Si(IV) ions in LiF-SiO2 and KF-SiO2 melts at 1173 K, which included 10 mol% SiO2, was studied toward controlling the electrodeposition process of crystalline Si in high-temperature melts with higher SiO2 composition ratios. The dissolution behavior of SiO2 was investigated by high-temperature Raman spectroscopy and density functional theory calculation, revealing that Si(IV) complex ions such as Si3F7-2 K are formed in the KF-SiO2 system, whereas Si(IV) ion was not easily bonded to constituent ions of the LiF-SiO2 melt. It was demonstrated that polycrystalline Si could be obtained by potentiostatic electrolysis in both melts, and the reduction rate of Si(IV) ions was faster in the LiF-SiO2 system. The Raman spectroscopy and XRD analysis revealed that the electrodeposits were the polycrystalline Si and the alloys such as Li-Si and K-Si. The reported data on the interaction between fluoride ions and Si(IV) ions in the binary melt of metal fluoride and SiO2 will contribute to realizing an in-situ resource utilization process that enables one-step Si recovery from SiO2.

关键词： Silicon electrodeposition Molten fluoride In-situ resource utilization High-temperature Raman spectroscopy DFT calculation

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Application of multiple linear regression model and long short-term memory with compartmental model to forecast dengue cases in Selangor, Malaysia based on climate variables

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INFECTIOUS DISEASE MODELLING 2025年第1期10卷 240-256页

作者： Lu, Xinyi Teh, Su Yean Tay, Chai Jian Abu Kassim, Nur Faeza Fam, Pei Shan Soewono, Edy Univ Sains Malaysia Sch Math Sci George Town 11800 Pulau Pinang Malaysia Univ Malaysia Pahang Al Sultan Abdullah Ctr Math Sci Gambang 26300 Pahang Malaysia Univ Sains Malaysia Sch Biol Sci Usm Pulau Pinang 11800 Malaysia Inst Teknol Bandung Ctr Math Modeling & Simulat Bandung 40132 Indonesia Inst Teknol Sumatera Fac Math & Nat Sci Dept Math Lampung 35365 Indonesia

Despite the implementation of various initiatives, dengue remains a significant public health concern in Malaysia. Given that dengue has no specific treatment, dengue prediction remains a useful early warning mechanism for timely and effective deployment of public health preventative measures. This study aims to develop a comprehensive approach for forecasting dengue cases in Selangor, Malaysia by incorporating climate variables. An ensemble of Multiple Linear Regression (MLR) model, Long Short-Term Memory (LSTM), and Susceptible-Infected mosquito vectors, Susceptible-Infected- Recovered human hosts (SI-SIR) model were used to establish a relation between climate variables (temperature, humidity, precipitation) and mosquito biting rate. Dengue incidence subject to climate variability can then be projected by SI-SIR model using the forecasted mosquito biting rate. The proposed approach outperformed three alternative approaches and expanded the temporal horizon of dengue prediction for Selangor with the ability to forecast approximately 60 weeks ahead with a Mean Absolute Percentage Error (MAPE) of 13.97 for the chosen prediction window before the implementation of the Movement Control Order (MCO) in Malaysia. Extended validation across subsequent periods also indicates relatively satisfactory forecasting performance (with MAPE ranging from 13.12 to 17.09). This research contributed to the field by introducing a novel framework for the prediction of dengue cases over an extended temporal range. (c) 2024 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Dengue Climate SIR Regression Deep learning

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Detection of dynamic communities in temporal networks with sparse data

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APPLIED NETWORK SCIENCE 2025年第1期10卷 1-29页

作者： Djurdjevac Conrad, Natasa Tonello, Elisa Zonker, Johannes Siebert, Heike Zuse Inst Berlin Modeling & Simulat Complex Proc Takustr 7 D-14195 Berlin Germany Free Univ Berlin Dept Math & Comp Sci Arnimallee 7 D-14195 Berlin Germany Univ Kiel Dept Math Heinrich Hecht Pl 6 D-24118 Kiel Germany

Temporal networks are a powerful tool for studying the dynamic nature of a wide range of real-world complex systems, including social, biological and physical systems. In particular, detection of dynamic communities within these networks can help identify important cohesive structures and fundamental mechanisms driving systems behaviour. However, when working with real-world systems, available data is often limited and sparse, due to missing data on systems entities, their evolution and interactions, as well as uncertainty regarding temporal resolution. This can hinder accurate representation of the system over time and result in incomplete or biased community dynamics. In this paper, we consider established methods for community detection and, using synthetic data experiments and real-world case studies, we evaluate the impact of data sparsity on the quality of identified dynamic communities. Our results give valuable insights on the evolution of systems with sparse data, which are less studied in existing literature, but are frequently encountered in real-world applications.

关键词： Temporal networks Sparse data Dynamic communities Temporal resolution Temporal clustering

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A Fast Iterative Solver for Multidimensional Spatial Fractional Cahn-Hilliard Equations

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JOURNAL OF SCIENTIFIC COMPUTING 2025年第3期102卷 1-23页

作者： Huang, Xin Li, Dongfang Lin, Xuelei Sun, Hai-Wei Guangxi Normal Univ Sch Math & Stat Guilin 541006 Peoples R China Huazhong Univ Sci & Technol Sch Math & Stat Wuhan 430074 Peoples R China Huazhong Univ Sci & Technol Hubei Key Lab Engn Modeling & Sci Comp Wuhan 430074 Peoples R China Harbin Inst Technol Sch Sci Shenzhen 518055 Peoples R China Univ Macau Dept Math Macau Peoples R China

This paper is concerned with the fast algorithm for solving multidimensional spatial fractional Cahn-Hilliard equations. The equations are discretized by a linear and energy-stable finite difference scheme. It gives a system of linear equations with a 2x2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2\times 2$$\end{document} indefinite ill-conditioned block matrix. We construct a positive definite block preconditioner based on the sine transform for the minimal residual method to solve the indefinite system. Theoretically, we prove that all the eigenvalues of the preconditioned matrix are located in the intervals [-32,-122]boolean OR[122,32]\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$[-\frac{3}{2},-\frac{1}{2\sqrt{2}}]\cup [\frac{1}{2\sqrt{2}},\frac{3}{2}]$$\end{document} without outliers. Thus, the preconditioned MINRES method has a linear convergence rate within an iteration number independent of the matrix size. A fast implementation is presented for the preconditioned matrix-vector multiplication, which reduces the computation complexity significantly. The matrix-size independent convergence rate and the fast implementation guarantee a linearithmic (nearly optimal) complexity of the proposed solver. Numerical examples are given to demonstrate the effectiveness of the proposed method.

关键词： Fast solver Multidimensional cahn-hilliard equations Block toeplitz matrix Preconditioned krylov subspace solver Matrix-size independent convergence rate

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Studying Ballistic Aggregation Phenomena through Efficient Time Stepping Approaches

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SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS 2025年第1期24卷 710-743页

作者： Degond, Pierre Dimarco, Giacomo Ferreira, Marina A. Hecht, Sophie Univ Toulouse Inst Math Toulouse CNRS UMR5219UPS F-31062 Toulouse 9 France Univ Ferrara Dept Math & Comp Sci Ferrara Italy Univ Ferrara Ctr Modeling Comp & Stat CMCS Ferrara Italy Univ Coimbra Dept Math CMUC P-3000413 Coimbra Portugal Univ Paris Sorbonne Univ CNRS Lab Jacques Louis LionsUMR7598 F-75005 Paris France

This paper deals with the problem of simulating dense dispersed systems composed of large numbers of particles undergoing ballistic aggregation. The most classical approaches for dealing with such problems are represented by the so-called event-driven methods. Despite being more accurate, these methods become computationally very expensive as the number of particles increases. Typically, their computational cost is proportional to the square of the number of particles, and thus they become extremely demanding as soon as this number becomes sufficiently large. An alternative approach, called time stepping, consists in evolving the problem over small time intervals and handling all collisions occurring during each time interval simultaneously. In this work, we follow this second direction and introduce a new time stepping method which recasts the problem of the multiple collisions in a minimization framework. The objective of this work is twofold: The first goal is to show that the statistical description of the resulting aggregates obtained with this new time stepping method is sufficiently close to that of the event-driven methods. The second goal consists in showing that, in terms of computational performances, this new approach is competitive and may outperform standard methodologies, especially when the number of particles becomes sufficiently large. Numerical results obtained in the case of spherical particles moving in a two-dimensional box show that these two properties are indeed satisfied.

关键词： ballistic aggregation fractal aggregates time stepping methods event-driven methods optimization

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