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Anisotropic high-Tc superconductivity above 90 K in hole-doped boron-nitrogen clathrates at ambient pressure

Physical Review B 2025年第9期111卷 094520-094520页

作者： Yu-Lin Han Kai-Yue Jiang Bao-Tian Wang Ping Zhang Hong-Yan Lu School of Physics and Physical Engineering Qufu Normal University Qufu 273165 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Spallation Neutron Source Science Center Dongguan 523803 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

Breakthroughs in near-room-temperature superconductivity within clathrate hydrides underscore the effectiveness of theory-driven approaches to designing high-Tc superconductors. However, superconductivity in these clathrate hydrides has not been realized at low or ambient pressures. To explore phonon-mediated superconductors with Tc exceeding the liquid-nitrogen temperature under ambient pressure, this study investigates the crystal structure, metallization, electron-phonon coupling, and anisotropic superconducting behavior in hole-doped (BN)6 and (BN)5 clathrates, with configurations akin to CaH6 and LaH10, utilizing first-principles calculations in junction with Wannier interpolation technique. By solving the fully anisotropic Migdal-Eliashberg equations, this work reveals a positive correlation between Tc and hole-doping levels, with the highest Tc approximately 32 K and 96 K in hole-doped (BN)6 and (BN)5, respectively, and both with single anisotropic energy gap nature. The high-Tc superconductivity in B-N clathrates arises from two primary factors: the enhanced density of states at the Fermi level and the presence of strong B-N sp3-hybridized covalent σ-bonding bands. These insights provide a new perspective for revealing the superconductivity of B-N clathrates from an anisotropic perspective and offer valuable avenues for inducing high-Tc superconductors at ambient conditions.

关键词： Energy gap

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On the conservation of helicity by weak solutions of the 3D Euler and inviscid MHD equations

arXiv

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arXiv 2024年

作者： Boutros, Daniel W. Titi, Edriss S. Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom Department of Mathematics Texas A&M University College StationTX77843-3368 United States Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot76100 Israel

Classical solutions of the three-dimensional Euler equations of an ideal incompressible fluid conserve the helicity. We introduce a new weak formulation of the vorticity formulation of the Euler equations in which (by implementing the Bony paradifferential calculus) the advection terms are interpreted as paraproducts for weak solutions with low regularity. Using this approach we establish an equation of local helicity balance, which gives a rigorous foundation to the concept of local helicity density and flux at low regularity. We provide a sufficient criterion for helicity conservation which is weaker than many of the existing sufficient criteria for helicity conservation in the literature. Subsequently, we prove a sufficient condition for the helicity to be conserved in the zero viscosity limit of the Navier-Stokes equations. Moreover, under additional assumptions we establish a relation between the defect measure (which is part of the local helicity balance) and a third-order structure function for solutions of the Euler equations. As a byproduct of the approach introduced in this paper, we also obtain a new sufficient condition for the conservation of magnetic helicity in the inviscid MHD equations, as well as for the kinematic dynamo model. Finally, it is known that classical solutions of the ideal (inviscid) MHD equations which have divergence-free initial data will remain divergence-free, but this need not hold for weak solutions. We show that weak solutions of the ideal MHD equations arising as weak-∗ limits of Leray-Hopf weak solutions of the viscous and resistive MHD equations remain divergence-free in *** Codes 35Q35 (primary), 35Q31, 76F02, 76B99, 76W05, 35D30 (secondary) © 2024, CC BY.

关键词： Euler equations

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Massively Winning Configurations in the Convex Grabbing Game on the Plane 33

Massively Winning Configurations in the Convex Grabbing Game...

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33rd Canadian Conference on Computational Geometry, CCCG 2021

作者： Dvorak, Martin Nicholson, Sara Department of Theoretical Computer Science and Mathematical Logic Faculty of Mathematics and Physics Charles University Institute of Science and Technology Austria Department of Applied Mathematics Faculty of Mathematics and Physics Charles University Czech Republic

The convex grabbing game is a game where two players, Alice and Bob, alternate taking extremal points from the convex hull of a point set on the plane. Rational weights are given to the points. The goal of each player is to maximize the total weight over all points that they obtain. We restrict the setting to the case of binary weights. We show a construction of an arbitrarily large odd-sized point set that allows Bob to obtain almost 3/4 of the total weight. This construction answers a question asked by Matsumoto, Nakamigawa, and Sakuma in [Graphs and Combinatorics, 36/1 (2020)]. We also present an arbitrarily large even-sized point set where Bob can obtain the entirety of the total weight. Finally, we discuss conjectures about optimum moves in the convex grabbing game for both players in general. © 2021 Meng He and Don Sheehy.

关键词： Combinatorial mathematics

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High-Flux Neutron Generator Based on Laser-Driven Collisionless Shock Acceleration

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Physical Review Letters 2023年第2期131卷 025101-025101页

作者： Y. L. Yao S. K. He Z. Lei T. Ye Y. Xie Z. G. Deng B. Cui W. Qi L. Yang S. P. Zhu X. T. He W. M. Zhou B. Qiao Center for Applied Physics and Technology HEDPS and State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China Science and Technology on Plasma Physics Laboratory Research Center of Laser Fusion 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

A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield 6.6×107 n/sr from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is 1019 W/cm2. Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to 5×1010 n/sr can be obtained when laser intensity increases to 1021 W/cm2 under the same laser energy.

关键词： High-energy-density plasmas Laser driven ion acceleration Laser-plasma interactions Neutron physics Nuclear reactions Neutrons Multiscale modeling Nuclear data analysis & compilation

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Efficient Diabetes Detection using Hybrid Machine Learning Model

Efficient Diabetes Detection using Hybrid Machine Learning M...

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2024 International Conference on Distributed Systems, Computer Networks and Cybersecurity, ICDSCNC 2024

作者： Gowri, A.S. Jose, P. Karthik, S.M. Shaheema, S Berlin Karuppasway, K.M. Balamurugan, R. School of Computing Srm Institute of Science and Technology Department of Networking and Communications Kattankulathur India Vel Tech Rangarajan Dr. Sagunthala R&d Institute of Science and Technology Department of Computer Science and Engineering Chennai India Department for Applied Research Gandhigram India Stella Mary's College of Engineering Department of Artificial Intelligence and Data Science Azhikal India Bharath Institute of Higher Education and Research Department of Mathematics and Statistics Chennai India Dmi College of Engineering Department of Information Technology Chennai India

ISBN: (纸本)9798350375442

Diabetes is a metabolic disease that affects a large number of the global population and is incurable. The primary causes of death symptoms are kidney failure, heart attacks, strokes, and blindness. In this paper Principal component analysis used for pre-processing the data to extract features and The Efficient Hybrid Machine Learning Model Convolution Neural Network-Support Vector Machine is used to categorize the Pima Indian dataset. CNN and non-linear SVM used in a hybrid model to classify the diabetes data from the Pima Indians. To identify positive classes of pima Indians diabetes, the HCNN-SVM extract the features from the original data expression and learns diabetes data through a novel convolution network environment to the SVM classifier with RBF function and achieve the accuracy as 98,04%. © 2024 IEEE.

关键词： Adversarial machine learning

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Mixture of Experts Soften the Curse of Dimensionality in Operator Learning

arXiv

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arXiv 2024年

作者： Kratsios, Anastasis Furuya, Takashi Lara, Antonio Lassas, Matti de Hoop, Maarten Department of Mathematics McMaster University Vector Institute Canada Education and Research Center for Mathematical and Data Science Shimane University Japan Computational Applied Mathematics Rice University United States Department of Mathematics and Statistics University of Helsinki Finland

In this paper, we construct a mixture of neural operators (MoNOs) between function spaces whose complexity is distributed over a network of expert neural operators (NOs), with each NO satisfying parameter scaling restrictions. Our main result is a distributed universal approximation theorem guaranteeing that any Lipschitz non-linear operator between L2([0,1]d) spaces can be approximated uniformly over the Sobolev unit ball therein, to any given Ε > 0 accuracy, by an MoNO while satisfying the constraint that: each expert NO has a depth, width, and rank of O(Ε−1). Naturally, our result implies that the required number of experts must be large, however, each NO is guaranteed to be small enough to be loadable into the active memory of most computers for reasonable accuracies Ε. During our analysis, we also obtain new quantitative expression rates for classical NOs approximating uniformly continuous non-linear operators uniformly on compact subsets of L2([0,1]d). Copyright © 2024, The Authors. All rights reserved.

关键词： Mathematical operators

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Secrecy Performance of Joint Antenna and User Selection in Cognitive Ambient Backscattering Communications 100

Secrecy Performance of Joint Antenna and User Selection in C...

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100th IEEE Vehicular Technology Conference, VTC 2024-Fall

作者： Elbattrawy, Ahmed N. El-Malek, Ahmed H. Abd Rabia, Sherif I. Zahra, Waheed K. Basic and Applied Sciences Institute New Borg El-Arab City Alexandria21934 Egypt Egypt-Japan University of Science and Technology School of Electronics Communications and Computer Engineering New Borg El-Arab City Alexandria21934 Egypt Alexandria University Faculty of Engineering Department of Engineering Mathematics and Physics Alexandria21544 Egypt

ISBN: (纸本)9798331517786

In this work, we investigate the security performance of an underlay cognitive radio network (CRN) with ambient backscatter communication (AmBC), where a backscattering device (BD) shares the spectrum and the receivers with the secondary user. Different from the related work, we consider a secondary user transmitter (ST) with multiple antenna in an AmBC-CRN with multiple receivers and multiple passive eavesdroppers. The ST performs joint antenna-user selection to enhance its security performance and overcome the performance degradation caused by BD interference. Considering the Nakagami-m fading model, closed-form expressions are derived for the secrecy outage probability for both the ST and the BD transmissions. Monte Carlo simulations are performed to validate the derived closed-form expressions. Numerical results show that employing joint antenna-user selection enhances the ST security performance by exploiting antenna and user diversity. © 2024 IEEE.

关键词： Radio communication

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A Space-time Nonlocal Traffic Flow Model: Relaxation Representation and Local Limit

arXiv

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arXiv 2022年

作者： Du, Qiang Huang, Kuang Scott, James Shen, Wen Department of Applied Physics and Applied Mathematics Data Science Institute Columbia University New YorkNY10027 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States Department of Mathematics Pennsylvania State University University ParkPA16802 United States

We propose and study a nonlocal conservation law modelling traffic flow in the existence of inter-vehicle communication. It is assumed that the nonlocal information travels at a finite speed and the model involves a space-time nonlocal integral of weighted traffic density. The well-posedness of the model is established under suitable conditions on the model parameters and by a suitably-defined initial condition. In a special case where the weight kernel in the nonlocal integral is an exponential function, the nonlocal model can be reformulated as a 2 × 2 hyperbolic system with relaxation. With the help of this relaxation representation, we show that the Lighthill-Whitham-Richards model is recovered in the equilibrium approximation limit. Copyright © 2022, The Authors. All rights reserved.

关键词： Exponential functions

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SymILO: a symmetry-aware learning framework for integer linear optimization 24

SymILO: a symmetry-aware learning framework for integer line...

引用

Proceedings of the 38th International Conference on Neural Information Processing Systems

作者： Qian Chen Tianjian Zhang Linxin Yang Qingyu Han Akang Wang Ruoyu Sun Xiaodong Luo Tsung-Hui Chang School of Science and Engineering The Chinese University of Hong Kong Shenzhen China and Shenzhen Research Institute of Big Data China Shenzhen Research Institute of Big Data China and School of Data Science The Chinese University of Hong Kong Shenzhen China Shenzhen Research Institute of Big Data China School of Data Science The Chinese University of Hong Kong Shenzhen China and Shenzhen International Center For Industrial And Applied Mathematics Shenzhen Research Institute of Big Data China

ISBN: (纸本)9798331314385

Integer linear programs (ILPs) are commonly employed to model diverse practical problems such as scheduling and planning. Recently, machine learning techniques have been utilized to solve ILPs. A straightforward idea is to train a model via supervised learning, with an ILP as the input and an optimal solution as the label. An ILP is symmetric if its variables can be permuted without changing the problem structure, resulting in numerous equivalent and optimal solutions. Randomly selecting an optimal solution as the label can introduce variability in the training data, which may hinder the model from learning stable patterns. In this work, we incorporate the intrinsic symmetry of ILPs and propose a novel training framework called SymILO. Specifically, we modify the learning task by introducing solution permutation along with neural network weights as learnable parameters and then design an alternating algorithm to jointly optimize the loss function. We conduct extensive experiments on ILPs involving different symmetries and the computational results demonstrate that our symmetry-aware approach significantly outperforms three existing methods—achieving 50.3%, 66.5%, and 45.4% average improvements, respectively.

关键词：

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Enhanced prairie dog optimization with Levy flight and dynamic opposition-based learning for global optimization and engineering design problems

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Neural Computing and Applications 2024年第19期36卷 11137-11170页

作者： Biswas, Saptadeep Shaikh, Azharuddin Ezugwu, Absalom El-Shamir Greeff, Japie Mirjalili, Seyedali Bera, Uttam Kumar Abualigah, Laith Department of Mathematics National Institute of Technology Agartala Tripura Agartala India Unit for Data Science and Computing North-West University 11 Hoffman Street Potchefstroom2520 South Africa Faculty of Natural and Agricultural Sciences School of Computer Science and Information Systems North-West University Vanderbijlpark South Africa Centre for Artificial Intelligence Research and Optimization Torrens University Australia Fortitude Valley BrisbaneQLD4006 Australia Research Center University of Tabuk Tabuk71491 Saudi Arabia Computer Science Department Al al-Bayt University Mafraq25113 Jordan Hourani Center for Applied Scientific Research Al-Ahliyya Amman University Amman19328 Jordan Applied Science Research Center Applied Science Private University Amman11931 Jordan Department of Electrical and Computer Engineering Lebanese American University Byblos13-5053 Lebanon School of Engineering and Technology Sunway University Malaysia Petaling Jaya27500 Malaysia College of Engineering Yuan Ze University Taoyuan32003 Taiwan MEU Research Unit Middle East University Amman11831 Jordan

This study proposes a new prairie dog optimization algorithm version called EPDO. This new version aims to address the issues of premature convergence and slow convergence that were observed in the original PDO algorithm. To improve performance, several modifications are introduced in EPDO. First, a dynamic opposite learning strategy is employed to increase the diversity of the population and prevent premature convergence. This strategy helps the algorithm avoid falling into local optima and promotes global optimization. Additionally, the Lévy dynamic random walk technique is utilized in EPDO. This modified Lévy flight with random walk reduces the algorithm’s running time for the test function’s ideal value, accelerating its convergence. The proposed approach is evaluated using 33 benchmark problems from CEC 2017 and compared against seven other comparative techniques: GWO, MFO, ALO, WOA, DA, SCA, and RSA. Numerical results demonstrate that EPDO produces good outcomes and performs well in solving benchmark problems. To further validate the results and assess reliability, the authors employ average rank tests, the measurement of alternatives, and ranking according to the compromise solution (MARCOS) method, as well as a convergence report of EPDO and other algorithms. Furthermore, the effectiveness of the EPDO algorithm is demonstrated by applying it to five design problems. The results indicate that EPDO achieves impressive outcomes and proves its capability to address practical issues. The algorithm performs well in solving benchmark and practical design problems, as supported by the numerical results and validation methods used in the study. © The Author(s) 2024.

关键词： Global optimization

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