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Journal of Computational physics 2025年 532卷

作者： Zhang, Jinpeng Luo, Li Wang, Xiaoping Department of Mathematics University of Macau Macao SAR China School of Science and Engineering The Chinese University of Hong Kong Guangdong Shenzhen518172 China Shenzhen International Center for Industrial and Applied Mathematics Shenzhen Research Institute of Big Data Guangdong518172 China Department of Mathematics the Hong Kong University of Science and Technology Hong Kong

In this paper, we develop a second-order, fully decoupled, and energy-stable numerical scheme for the Cahn-Hilliard-Navier-Stokes model for two phase flow with variable density and viscosity. We propose a new decoupling Constant Scalar Auxiliary Variable (D-CSAV) method which is easy to generalize to schemes with high order accuracy in time. The method is designed using the "zero-energy-contribution" property while maintaining conservative time discretization for the "non-zero-energy-contribution" terms. A new set of scalar auxiliary variables is introduced to develop second-order-in-time, unconditionally energy stable, and decoupling-type numerical schemes. We also introduce a stabilization parameter α to improve the stability of the scheme by slowing down the dynamics of the scalar auxiliary variables. Our algorithm simplifies to solving three independent linear elliptic systems per time step, two of them with constant coefficients. The update of all scalar auxiliary variables is explicit and decoupled from solving the phase field variable and velocity field. We rigorously prove unconditional energy stability of the scheme and perform extensive benchmark simulations to demonstrate accuracy and efficiency of the method. © 2025 Elsevier Inc.

关键词： Navier Stokes equations

Probability of the share price going beyond the established corridor

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Probability of the share price going beyond the established ...

International Conference on Control, Decision and Information Technologies (CoDIT)

作者： Sergei L. Semakov Faculty of Control and Applied Mathematics Moscow Institute of Physics and Technology Department of Mathematics Moscow Automobile and Road Construction Institute Federal Research Center "Computer Science and Control" of the Russian Academy of Sciences the Russian Federation

ISBN: (数字)9798350373974

ISBN: (纸本)9798350373981

A technology is proposed for estimating the probability that the share price will leave the established corridor by a given point in time. The exact expression is obtained for the required probability under the assumption that the behavior of the share price is described by the well-known model of Samuelson, according to which the relative change in price is the sum of the non-random trend and the Wiener process.

关键词： Share prices Market research Information technology

Stable phases of freestanding monolayer TiO2: The emergence of out-of-plane ferroelectricity

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arXiv 2024年

作者： Bu, Xiangtian Liu, Haitao Li, Yuanchang Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing100081 China Institute of Applied Physics and Computational Mathematics Beijing100088 China National Key Laboratory of Computational Physics Beijing100088 China

Despite being successfully synthesized [Zhang et al., Nat. Mater. 20, 1073 (2021)], the monolayer structure of stable hexagonal TiO2 is unknown, and it is not even clear whether it can exist in a freestanding form. Through first-principles calculations, we have identified two previously uncharted stable structures, namely, distorted 1×√3 1T-TiO2 and √3×√3 1T-TiO2, both of which are energetically more favourable than commonly adopted 1H and 1T phases. Here structural distortions are characterized by the out-of-plane shifts of Ti atoms due to the pseudo-Jahn-Teller interactions, which break one and all two inversion symmetries of 1T configuration. As a consequence, the 1×√3 1T remains centrosymmetric while the √3×√3 1T exhibits out-of-plane ferroelectricity. Electronic structure calculations show that both two are wide-bandgap semiconductors with bandgaps larger than their bulk counterparts. Our study not only deepens the understanding of structural instability in wide-gap semiconductors but also adds a new member to the rare family of two-dimensional out-of-plane ferroelectrics. © 2024, CC BY.

关键词： Titanium dioxide

A way to identify whether a DFT gap is from right reasons or error cancellations: The case of copper chalcogenides

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arXiv 2024年

作者： Shen, Jiale Liu, Haitao Li, Yuanchang Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing100081 China Institute of Applied Physics and Computational Mathematics Beijing100088 China National Key Laboratory of Computational Physics Beijing100088 China

Gap opening remains elusive in copper chalcogenides (Cu2X, X = S, Se and Te), not least because Hubbard + U, hybrid functional and GW methods have also failed. In this work, we elucidate that their failure originates from a severe underestimation of the 4s-3d orbital splitting of the Cu atom, which leads to a band-order inversion in the presence of an anionic crystal field. As a result, the Fermi energy is pinned due to symmetry, yielding an invariant zero gap. Utilizing the hybrid pseudopotentials to correct the underestimation on the atomic side opens up gaps of experimental magnitude in Cu2X, suggesting their predominantly electronic nature. Our work not only clarifies the debate about the Cu2X gap, but also provides a way to identify which of the different methods really captures the physical essence and which is the result of error cancellation. © 2024, CC BY.

关键词： Copper

AN EFFICIENT UNSUPERVISED FRAMEWORK FOR CONVEX QUADRATIC PROGRAMS VIA DEEP UNROLLING

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arXiv 2024年

作者： Yang, Linxin Li, Bingheng Ding, Tian Wu, Jianghua Wang, Akang Wang, Yuyi Tang, Jiliang Sun, Ruoyu Luo, Xiaodong School of Data Science The Chinese University of Hong Kong Shenzhen China Shenzhen International Center for Industrial and Applied Mathematics Shenzhen Research Institute of Big Data China Michigan State University United States Tengen Intelligence Institute

Quadratic programs (QPs) arise in various domains such as machine learning, finance, and control. Recently, learning-enhanced primal-dual hybrid gradient (PDHG) methods have shown great potential in addressing large-scale linear programs;however, this approach has not been extended to QPs. In this work, we focus on unrolling "PDQP", a PDHG algorithm specialized for convex QPs. Specifically, we propose a neural network model called "PDQP-net" to learn optimal QP solutions. Theoretically, we demonstrate that a PDQP-net of polynomial size can align with the PDQP algorithm, returning optimal primal-dual solution pairs. We propose an unsupervised method that incorporates KKT conditions into the loss function. Unlike the standard learning-to-optimize framework that requires optimization solutions generated by solvers, our unsupervised method adjusts the network weights directly from the evaluation of the primal-dual gap. This method has two benefits over supervised learning: first, it helps generate better primal-dual gap since the primal-dual gap is in the objective function;second, it does not require solvers. We show that PDQP-net trained in this unsupervised manner can effectively approximate optimal QP solutions. Extensive numerical experiments confirm our findings, indicating that using PDQP-net predictions to warm-start PDQP can achieve up to 45% acceleration on QP instances. Moreover, it achieves 14% to 31% acceleration on out-of-distribution instances. © 2024, CC BY.

关键词： Unsupervised learning

Minimizing Age of Information in Multi-Class Systems Using an Elapsed-Time-Based Hybrid Service Discipline

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IEEE Open Journal of the Communications Society

IEEE Open Journal of the Communications Society 2025年 6卷 4366-4382页

作者： Fahim, Tamer E. Rabia, Sherif I. El-Malek, Ahmed H. Abd Zahra, Waheed K. Alexandria University Faculty of Engineering Department of Engineering Mathematics and Physics Alexandria Egypt Egypt-Japan University of Science and Technology Department of Electronics and Communications Engineering Alexandria Egypt Egypt-Japan University of Science and Technology Basic and Applied Sciences Institute Alexandria Egypt Tanta University Faculty of Engineering Department of Engineering Physics and Mathematics Tanta Egypt

Minimizing the age of information (AoI) has recently become a key objective in internet-of-things technology. However, research on prioritized sources with distinct AoI constraints remains limited, despite its significant relevance in real-world applications. In addition, the existing service disciplines —preemption (PR) and non-preemption (NP)— result in a biased satisfaction across priority classes. Therefore, this work proposes a hybrid PR/NP service discipline based on the elapsed service time for a multi-class status update system, considering Poisson arrival process and Erlang service time distribution. Class-specific thresholds on the elapsed service time are set to limit further service preemptions. By applying the stochastic hybrid system approach, we analyze the AoI moments for arbitrary number of classes and derive key insights that underscore the benefits of our model over classical ones. Numerical evaluations of average AoI and AoI dispersion demonstrate that adjusting threshold parameters can achieve a more balanced performance across classes. Additionally, we explore threshold optimization to either enhance the performance of the most AoI-sensitive class or maximize overall network satisfaction while meeting quality-of-service constraints. For the latter, a near-optimal approach is proposed to reduce the computational complexity of determining the optimal solution as the number of priority classes increases. © 2020 IEEE.

关键词： Queueing networks

Study of the atmospheric neutron radiation effects using compact laser-driven spallation neutron source

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Physical Review Research 2025年第1期7卷 013071-013071页

作者： Z. B. Wu Y. L. Yao X. F. Shen K. Li A. D. Liu X. T. He B. Qiao Center for Applied Physics and Technology HEDPS and SKLNPT School of Physics Peking University Beijing 100871 China Research Center of Laser Fusion China Academy of Engineering Physics (CAEP) Mianyang 621900 China Institute of System Engineering China Academy of Engineering Physics (CAEP) Mianyang 621900 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Frontiers Science Center for Nano-optoelectronic Peking University Beijing 100094 China

We propose a laboratory accelerated test method for study of the atmospheric neutron radiation effects by using a compact laser-driven spallation neutron source (LDSNS). The LDSNS is obtained by injecting a GeV quasimonoenergetic proton beam accelerated by light-sail (LS) radiation pressure of intense lasers into a lead target. According to the LS scaling law, proton energy spectra can be regulated by adjusting the laser and foil target parameters, so that the neutron spectra at various atmospheric altitudes are well reproduced. Integrated PIC and MC simulations have verified the scheme (for that at altitude 12 km, laser intensity of 1022W/cm2 is required) and shown that the neutron fluence per laser shot is as high as 1.73×108n/cm2, equivalent to 3.7 year flux accumulation in atmosphere. Using the G4SEE toolkit, we estimate that the HM628128 SRAM may undergo an average of ten single event upsets per shot for the proposed laboratory test.

关键词： Spalling

Structure function of helicity in compressible homogeneous isotropic turbulence

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Physical Review Fluids 2025年第3期10卷 034610-034610页

作者： Running Hu Zheng Yan Runyuan Gan Xinliang Li Changping Yu State Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China School of Engineering Science University of Chinese Academy of Sciences Beijing 100049 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China

Helicity plays an essential role in the interscale dynamics of turbulence. This paper focuses on the compressible effects on helicity cascades via structure functions. We first investigate the spatial-local dynamics of helicity, revealing that helicity is enhanced by pressure gradients along vorticity lines. Then, structure functions are used to describe the multiscale dynamics. The scaling law r2/3 for helicity remains valid in compressible turbulence, as helicity is independent of the compressive components. Additional pressure and divergence terms are introduced in the new third-order relation for helicity in compressible turbulence. The pressure term is related to the pressure gradients along the vorticity lines and plays a dominant role in the dissipative range. The divergence term is mainly induced by the mixed structure function of divergence and helicity, significantly contributing to inverse helicity cascades in the inertial range.

关键词： Vorticity

Computer-aided diagnosis of breast cancer from mammogram images using deep learning algorithms

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Journal of Electrical Systems and Information Technology 2024年第1期11卷 1-16页

作者： Dada, Emmanuel Gbenga Oyewola, David Opeoluwa Misra, Sanjay Department of Mathematical Sciences University of Maiduguri Maiduguri Nigeria Department of Mathematics and Computer Science Federal University Kashere Gombe Nigeria Department of Computer Science and Communication Østfold University College Halden Norway Department of Applied Data Science Institute for Energy Technology Halden Norway

Even though accurate detection of dangerous malignancies from mammogram images is mostly dependent on radiologists' experience, specialists occasionally differ in their assessments. Computer-aided diagnosis provides a better solution for image diagnosis that can help experts make more reliable decisions. In medical applications for diagnosing cancerous growths from mammogram images, computerized and accurate classification of breast cancer mammogram images is critical. The deep learning approach has been widely applied in medical image processing and has had considerable success in biological image classification. The Convolutional Neural Network (CNN), Inception, and EfficientNet are proposed in this paper. The proposed models attain better performance compared to the conventional CNN. The models are used to automatically classify breast cancer mammogram images from Kaggle into benign and malignant. Simulation results demonstrated that EfficientNet, with an accuracy between 97.13 and 99.27%, and overall accuracy of 98.29%, perform better than the other models in this paper.

关键词：

Imprints of dark matter-massive neutrino interaction in upcoming post-reionization and galaxy surveys

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arXiv 2023年

作者： Dey, Antara Paul, Arnab Pal, Supratik Physics and Applied Mathematics Unit Indian Statistical Institute Kolkata700108 India School of Physical Sciences Indian Association for the Cultivation of Science Kolkata700032 India Technology Innovation Hub on Data Science Big Data Analytics and Data Curation Indian Statistical Institute Kolkata700108 India

We explore possible signatures of the interaction between dark matter (DM) and massive neutrinos during the post-reionization epoch. Using both Fisher matrix forecast analysis and Markov Chain Monte-Carlo (MCMC) simulation, we conduct a thorough investigation of the constraints and imprints of the scenario on the upcoming post-reionization and galaxy surveys. Our investigation focuses on two key parameters: the strength of the DM-massive neutrino interaction (u) and the total neutrino mass (Mtot), on top of the usual 6 cosmological parameters. We utilize future 21-cm intensity mapping, galaxy clustering as well as cosmic shear observations in order to investigate the possible constraints of these parameters in the future observations: Square Kilometre Array (SKA1 and SKA2) and Euclid, taking both conservative and realistic approaches. All these missions show promise in constraining both the parameters u and Mtot by few orders compared to the current constraints from Planck18 (SKA2 performing the best among them). Although we do not find much improvement in H0 and σ8 tensions from our forecast analysis, SKA2 constrains them better in conservative approach. We further perform a brief investigation of the prospects of some of the next generation Cosmic Microwave Background (CMB) missions in combinations with LSS experiments in improving the constraints. Our analysis reveals that both SKA2 and CMB-S4 + Euclid + SKA1 IM2 combination will put the strongest bounds on the model parameters. Copyright © 2023, The Authors. All rights reserved.

关键词： Galaxies