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Nonconvex Unified Prior Fused Low-Rankness and Smoothness for Tensor Recovery

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SSRN

SSRN 2023年

作者： Yin, Junping Sun, Jianing Wu, Yumo School of Mathematics and Statistics Northeast Normal University Changchun China Northeast Normal University Changchun China Institute of Applied Physics and Computational Mathematics Beijing100094 China Shanghai Zhangjiang Institute of Mathematics Shanghai201203 China

Tensor data such as hyperspectral images and multi-frame videos have gained increasing attention in practical applications. However, degradation phenomena, including noise and missing pixels, are inevitable during data acquisition and transmission and they generate a series of tensor data recovery tasks, i.e. ill-posed inverse problems. Currently, it is known that the prior knowledge for tensor recovery includes global low-rankness and local smoothness, etc. How to reasonablly unify these two typical priors has become a common concern. In this paper, we propose a novel nonconvex unified prior term for jointly characterizing the low-rankness and smoothness of tensor in the gradient domain. Specifically, the weighted tensor Schatten p-norm is introduced to be a tighter nonconvex rank surrogate function. We apply the proposed prior term as a regularizer into the tensor completion model and tensor robust principal component analysis model, respectively. Furthermore, an efficient algorithm is developed based on the alternating direction method of multipliers to solve the problems. Extensive experimental results on inpainting and denoising tasks demonstrate the superiority of the proposed method compared with the existing state-of-the-art methods, particularly in cases of high missing rates and strong noise levels. © 2023, The Authors. All rights reserved.

关键词： Tensors

Mathematical modelling of transport phenomena in compressible multicomponent flows

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arXiv 2022年

作者： Zhang, Chao Wang, Lifeng Ye, Wenhua Wu, Junfeng Shen, Zhijun Menshov, Igor Institute of Applied Physics and Computational Mathematics Beijing China Keldysh Institute for Applied Mathematics RAS Moscow Russia SRISA RAS Moscow Russia Center for Applied Physics and Technology HEDPS Peking University Beijing China

The present article proposes a diffuse interface model for compressible multicomponent flows with transport phenomena of mass, momentum and energy (i.e., mass diffusion, viscous dissipation and heat conduction). The model is reduced from the seven-equation Baer-Nuziato type model with asymptotic analysis in the limit of instantaneous mechanical relaxations. The main difference between the present model and the Kapila’s five-equation model consists in that different time scales for pressure and velocity relaxations are assumed, the former being much smaller than the latter. Thanks to this assumption, the velocity disequilibrium is retained to model the mass diffusion process. Aided by the diffusion laws, the final model still formally consists of five equations. The proposed model satisfy two desirable properties: (1) it respects the laws of thermodynamics, (2) it is free of the spurious oscillation problem in the vicinity of the diffused interface zone. For solution of the model governing equations, we implement the fractional step method to split the model into five physical steps: the hydrodynamic step, the viscous step, the heat transfer step, the heat conduction step and the mass diffusion step. The split governing equations for the hydrodynamic step formally coincide with the Kapila’s five equation model and are solved with the Godunov finite volume method. The mass diffusion, viscous dissipation and heat conduction processes contribute parabolic partial differential equations that are solved with the Chebyshev method of local iterations. Numerical results show that the proposed model maintains pressure, velocity and temperature equilibrium near the diffused interface. Convergence tests demonstrate that the numerical methods achieve second order in space and time. The proposed model and numerical methods are applied to simulate the laser-driven RM instability problem in inertial confinement fusion, good agreement with experimental results are observed. © 2022,

关键词： Heat conduction

Droplet coalescence kinetics: Coalescence mechanisms and thermodynamic non-equilibrium effects under isothermal and non-isothermal conditions

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arXiv 2025年

作者： Sun, Guanglan Gan, Yanbiao Yang, Bin Xu, Aiguo Liu, Zhipeng Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle School of Liberal Arts and Sciences North China Institute of Aerospace Engineering Langfang065000 China School of Energy and Safety Engineering Tianjin Chengjian University Tianjin300384 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing100088 China National Key Laboratory of Shock Wave and Detonation Physics Mianyang621999 China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China School of Science Tianjin Chengjian University Tianjin300384 China

Droplet coalescence is a multiscale phenomenon driven by multiple thermodynamic non-equilibrium (TNE) effects. This study investigates the droplet coalescence mechanisms and the interplay between various TNE effects under isothermal and non-isothermal conditions kinetically. The main findings include: (1) Coalescence initiation and cut-through mechanisms: In non-isothermal conditions, the temperature rise caused by the release of latent heat during phase transition slightly increases the surface tension gradient (driving force) near the contact point of the two droplets, while significantly enhancing the pressure gradient (resistance). This results in a significantly prolonged coalescence initiation time compared to the isothermal case. The additional temperature field effect increases the spatial complexity of both the flow field and droplet morphology. Regarding the cut-through mechanism, in both cases, pressure extends the liquid-vapor interface in opposite directions, promoting the growth of the liquid bridge. (2) TNE effects: Latent heat-induced temperature rise significantly refrains the TNE intensity in thermal case. Before and after droplet contact, non-equilibrium quantities driven by the temperature gradient (∆∗3,1 and ∆∗3) and those driven by the velocity gradient (∆∗2 and ∆∗4,2), alternate in dominating the coalescence process. This competition and interplay result in a more complex spatial and spatiotemporal evolution of TNE effects compared to the isothermal case, where the TNE intensity is primarily dominated by ∆∗2 and ∆∗4,2. (3) Entropy production mechanisms: In the non-isothermal case, entropy production is contributed not only by ∆∗2 but also by ∆∗3,1, with the former being the dominant contributor. The temperature field reduces the entropy production rate, while extends its duration, and increases the total entropy production. Before and after droplet cut-through, the entropy production rates from ∆∗2 and ∆∗3,1 alternate in dominating the total e

关键词： Latent heat

Crossed Nonlinear Dynamical Hall Effect in Twisted Bilayers

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arXiv 2023年

作者： Chen, Cong Zhai, Dawei Xiao, Cong Yao, Wang New Cornerstone Science Laboratory Department of Physics University of Hong Kong Hong Kong HKU-UCAS Joint Institute of Theoretical and Computational Physics at Hong Kong Hong Kong Institute of Applied Physics and Materials Engineering University of Macau Taipa China

We propose a novel nonlinear dynamical Hall effect characteristic of layered materials with chiral symmetry, which is driven by the joint action of in-plane and time variation of out-of-plane ac fields jH ∼ E⊥ × E. A new band geometric quantity – interlayer Berry connection polarizability, which probes a mixed quantum metric characteristic of layer hybridized electrons by twisted interlayer coupling, underlies this effect. When the two orthogonal fields have common frequency, their phase difference controls the on/off, direction and magnitude of the rectified Hall current. We show sizable effects in twisted homobilayer transition metal dichalcogenides and twisted bilayer graphene over broad range of twist angles. Our work opens the door to discovering mixed quantum metric responses unique to van der Waals stacking and concomitant applications under the nonlinear spotlight. Copyright © 2023, The Authors. All rights reserved.

关键词： Transition metals

THE MANY-BODY GROUND STATE MANIFOLD OF FLAT BAND INTERACTING HAMILTONIAN FOR MAGIC ANGLE TWISTED BILAYER GRAPHENE

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arXiv 2025年

作者： Stubbs, Kevin D. Ragone, Michael Macdonald, Allan H. Lin, Lin Department of Mathematics University of California BerkeleyCA94720 United States Department of Physics University of Texas at Austin AustinTX78712 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

At a magic relative twist angle, magic angle twisted bilayer graphene (MATBG) has an octet of flat bands that can host strong correlation physics when partially filled. A key theoretical discovery in MATBG is the existence of ferromagnetic Slater determinants as exact ground states of the corresponding flat band interacting (FBI) Hamiltonian. The FBI Hamiltonian describes the behavior of electrons that interact with each other in a high-dimensional space, and is constructed from the band structure of the non-interacting Bistritzer–MacDonald model at the chiral limit. A key property of the FBI Hamiltonian for MATBG is that it is frustration free and can be written as a sum of non-commuting terms. In this work, we provide a complete characterization of the ground state manifold of the FBI Hamiltonian, proving that it is precisely the linear span of such ferromagnetic Slater determinants. © 2025, CC BY.

关键词： Ferromagnetism

Petal-Graphyne: A Novel 2D Carbon Allotrope for High-Performance Li and Na Ion Storage

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arXiv 2025年

作者： Lima, Kleuton A.L. Laranjeira, José A.S. Martins, Nicolas F. Dias, Alexandre C. Sambrano, Julio R. Galvão, Douglas S. Ribeiro Junior, Luiz A. Department of Applied Physics Center for Computational Engineering and Sciences State University of Campinas SP Campinas13083-859 Brazil School of Sciences SP Bauru17033-360 Brazil Institute of Physics University of Brasília DF Brasília70910-900 Brazil International Center of Physics University of Brasília DF Brasília70910-900 Brazil Computational Materials Laboratory LCCMat Institute of Physics University of Brasília DF Brasília70910-900 Brazil

Using density functional theory simulations, this study introduces Petal-Graphyne (PLG), a novel multi-ring metallic structure composed of 4-, 8-, 10-, and 16-membered rings. Its structural, electronic, and lithium/sodium storage properties were comprehensively investigated. PLG exhibits a high theoretical capacity of 1004 mAh∕g for Li, Na, and mixed-Li/Na-ions, surpassing conventional graphite anodes. The material remains metallic, with multiple band crossings at the Fermi level. The optimal energy barriers for Li (0.28 eV) and Na (0.25 eV) on PLG and favorable diffusion coefficients in both monolayer and multilayer configurations are unveiled. The open circuit voltages are 0.47 V for Li, 0.51 V for Na, and 0.54 V for mixed-ion storage, suggesting stable electrochemical performance. These results highlight PLG as a promising candidate for next-generation lithium and sodium-ion batteries, combining high storage capacity and efficient ion *** Codes 00-XX Copyright © 2025, The Authors. All rights reserved.

关键词： Sodium-ion batteries

Phonon-mediated Migdal effect in semiconductor detectors

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Physical Review D 2022年第4期106卷 043004-043004页

作者： Zheng-Liang Liang Chongjie Mo Fawei Zheng Ping Zhang College of Mathematics and Physics Beijing University of Chemical Technology Beijing 100029 China Beijing Computational Science Research Center Beijing 100193 China Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) School of Physics Beijing Institute of Technology Beijing 100081 China School of Physics and Physical Engineering Qufu Normal University Qufu 273165 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China

The Migdal effect inside detectors provides a new possibility of probing the sub-GeV dark matter (DM) particles. While there has been well-established methods treating the Migdal effect in isolated atoms, a coherent and complete description of the valence electrons in a semiconductor is still absent. The bremstrahlunglike approach is a promising attempt, but it turns invalid for DM masses below a few tens of MeV. In this paper, we lay out a framework where phonon is chosen as an effective degree of freedom to describe the Migdal effect in semiconductors. In this picture, a valence electron is excited to the conduction state via exchange of a virtual phonon, accompanied by a multiphonon process triggered by an incident DM particle. Under the incoherent approximation, it turns out that this approach can effectively push the sensitivities of the semiconductor targets further down to the MeV DM mass region.

关键词： Particle dark matter Ab initio calculations Dark matter detectors Solid-state detectors

How does Goldene Stack?

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arXiv 2024年

作者： Pereira, Marcelo Lopes dos Santos, Emanuel J.A. Ribeiro, Luiz Antonio Galvão, Douglas Soares University of Brasília College of Technology Department of Electrical Engineering Federal District Brasília Brazil Institute of Physics University of Brasília Brasília70910-900 Brazil Computational Materials Laboratory LCCMat Institute of Physics University of Brasília Brasília70910-900 Brazil Department of Applied Physics Center for Computational Engineering and Sciences State University of Campinas Campinas São Paulo Brazil

MSC Codes 00-XXThe recent synthesis of Goldene, a 2D atomic monolayer of gold, has opened new avenues in exploring novel materials. However, the question of when multilayer Goldene transitions into bulk gold remains unresolved. This study used density functional theory calculations to address this fundamental question. Our findings reveal that multilayer Goldene retains an AA-like stacking configuration of up to six layers, with no observation of Bernal-like stacking as seen in graphene. Goldene spontaneously transitions to a bulk-like gold structure at seven layers, adopting a rhombohedral (ABC-like) stacking characteristic of bulk face-centered cubic (FCC) gold. The atomic arrangement converges entirely to the bulk gold lattice for more than ten layers. Quantum confinement significantly impacts the electronic properties, with monolayer and bulk Goldene exhibiting a single Dirac cone at the X-point of the Brillouin zone. In contrast, multilayer Goldene shows two Dirac cones at the X- and Y-points. Additionally, monolayer Goldene exhibits anisotropic optical absorption, which is absent in bulk gold. This study provides a deeper understanding of multilayer Goldene’s structural and electronic properties and stacked 2D materials in general. Copyright © 2024, The Authors. All rights reserved.

关键词： Multilayers

Equivalence analysis between Quasi-coarse-grained and Atomistic Simulations

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arXiv 2024年

作者： Jiang, Dong-Dong Wang, Pei Shao, Jian-Li National Key Laboratory of Explosive Science and Safety Protection Beijing Institute of Technology Beijing100081 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Explosion Protection and Emergency Disposal Technology Engineering Research Center of the Ministry of Education Beijing100039 China

In recent years, some mesoscale simulation methods based on the scaling of atomic potential functions, such as quasi-coarse-grained dynamics and coarse-grained dynamics, have shown promising results for modeling crystalline systems. However, this study presents evidence suggesting that the spatiotemporal trajectories of coarse-grained systems generated by such simulation methods exhibit a complete correspondence with those of specific molecular dynamics systems. In essence, current coarse-grained simulation methods involve a direct amplification of the results obtained from molecular dynamics simulations across spatial and temporal scales, yet they may lack the capability to adequately capture authentic scale effects. Consequently, the findings of related studies warrant careful re-evaluation. Furthermore, this study underscores the importance of not only verifying the consistency of mesoscale simulation methods with microscopic simulations but also meticulously assessing their capability to accurately forecast mesoscale physical phenomena. Copyright © 2024, The Authors. All rights reserved.

关键词： Coarse-grained modeling