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arXiv 2025年

作者： Chu, Shaoshuai Kurganov, Alexander Mohammadian, Saeed Zheng, Zuduo Department of Mathematics RWTH Aachen University Aachen52056 Germany Department of Mathematics Shenzhen International Center for Mathematics Southern University of Science and Technology Shenzhen518055 China Department of Mathematics Shenzhen International Center for Mathematics Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China School of Civil Engineering University of Queensland BrisbaneQLD4072 Australia

Phase-transition models are an important family of non-equilibrium continuum traffic flow models, offering properties like replicating complex traffic phenomena, maintaining anisotropy, and promising potentials for accommodating automated vehicles. However, their complex mathematical characteristics such as discontinuous solution domains, pose numerical challenges and limit their exploration in traffic flow theory. This paper focuses on developing a robust and accurate numerical method for phase-transition traffic flow models: We propose a second-order semi-discrete central-upwind scheme specifically designed for discontinuous phase-transition models. This novel scheme incorporates the projection onto appropriate flow domains, ensuring enhanced handling of discontinuities and maintaining physical consistency and accuracy. We demonstrate the efficacy of the proposed scheme through extensive and challenging numerical tests, showcasing their potential to facilitate further research and application in phase-transition traffic flow modeling. The ability of phase-transition models to embed the "time-gap"—a crucial element in automated traffic control—as a conserved variable aligns seamlessly with the control logic of automated vehicles, presenting significant potential for future applications, and the proposed numerical scheme now substantially facilitates exploring such potentials. © 2025, CC BY.

关键词： Finite volume method

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A New Locally Divergence-Free Path-Conservative Central-Upwind Scheme for Ideal and Shallow Water Magnetohydrodynamics

arXiv

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arXiv 2022年

作者： Chertock, Alina Kurganov, Alexander Redle, Michael Wu, Kailiang Department of Mathematics Center for Research in Scientific Computing North Carolina State University RaleighNC27695 United States Department of Mathematics SUSTech International Center for Mathematics Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China Department of Mathematics North Carolina State University RaleighNC27695 United States Shenzhen518055 China

We develop a new second-order unstaggered path-conservative central-upwind (PCCU) scheme for ideal and shallow water magnetohydrodynamics (MHD) equations. The new scheme possesses several important properties: it locally preserves the divergence-free constraint, it does not rely on any (approximate) Riemann problem solver, and it robustly produces high-resolution and non-oscillatory results. The derivation of the scheme is based on the Godunov-Powell nonconservative modifications of the studied MHD systems. The local divergence-free property is enforced by augmenting the modified systems with the evolution equations for the corresponding derivatives of the magnetic field components. These derivatives are then used to design a special piecewise linear reconstruction of the magnetic field, which guarantees a non-oscillatory nature of the resulting scheme. In addition, the proposed PCCU discretization accounts for the jump of the nonconservative product terms across cell interfaces, thereby ensuring stability. We test the proposed PCCU scheme on several benchmarks for both ideal and shallow water MHD systems. The obtained numerical results illustrate the performance of the new scheme, its robustness, and its ability not only to achieve high resolution, but also preserve the positivity of computed quantities such as density, pressure, and water depth. © 2022, CC BY.

关键词： Magnetohydrodynamics

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The Power Control Method of Data Center Based on Cloud- Edge Collaboration

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Journal of Physics: Conference Series 2021年第1期1754卷

作者： Junjie Zhao Yucheng Hou Liu Liu Feng Xie Xiang Mao Pan Luo Jinxin Wang Zhiqiang Zhang Jiang Deng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China Key Laboratory of the Ministry of Education on Smart Power Grids (Tianjin University) Tianjin 300072 China

Data centers have the characteristics of huge energy consumption and strong power fluctuations. To solve the problem of unstable supply and demand such as frequent power fluctuations in the micro-grid of the data center using renewable energies, this paper establishes a controllable load model of server clusters based on the task migration mechanism by analyzing the various tasks and characteristics of large cloud data centers, as well as edge computing nodes. Through the collaborative optimization control of edge and cloud computing tasks, and dynamically adjusting and migrating the server cluster load, a new data center tie-line power control method is proposed. The results of calculation examples show that the method can achieve power smoothing of large-scale cloud data center tie lines through cloud-edge collaborative control.

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Reduced-order modelling and quantifying local entropy production with triple decomposition in a low-pressure turbine

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Thermal science and Engineering Progress 2025年 63卷

作者： He, Bihai Hu, Chenxing Liu, Hao Wu, Shufan School of Aeronautics and Astronautics Shanghai Jiao Tong University Shanghai200240 China National Key Laboratory of Science and Technology on Multi-perch Vehicle Driving Systems Beijing Institute of Technology Beijing100081 China Tangshan Research Institute Beijing Institute of Technology Hebei Tangshan063000 China Shanghai Aircraft Design & Research Institute Commercial Aircraft Corporation of China Shanghai201210 China

The precise quantification of energy losses induced by multiscale flow structures in turbomachinery remains challenging, particularly under periodic wake disturbances. One of the bottleneck problems, which is frequently encountered in critical conditions for turbomachinery, lies at recognizing the losses associated with the large-scale perturbations or coherent structures in turbulent flows. This study addresses the critical need to distinguish irreversible losses from large-scale coherent structures versus random turbulence in a low-pressure turbine. A framework integrating triple decomposition of entropy production with quadruple Proper Orthogonal Decomposition was developed, enabling spatiotemporal separation of mean flow, wake-driven coherent motions, and small-scale turbulence. In order to validate the ability of the method in quantifying the irreversibility of wake flows, a low-pressure turbine cascade with incoming periodic wakes was numerically analyzed with simulations. For what concerns the quantitative estimation of the entropy production by mean flow, coherent flow and random turbulent flow are obtained. The entropy production by mean flow accounts for almost 99% of the total energy. The main energy loss induced by the coherent structure are found near 90% axial length and suction side of blade, driven by the tip leakage vortex and passage vortex. The energy loss induced by small-scale turbulent flow is similar with that of coherent structure, except from a more significant impact by the incoming wakes at 30% axial length of blade downstream leading edge. The methodology advances conventional Reynolds-averaged entropy analysis by resolving scale-specific loss mechanisms, and establishes a paradigm for optimizing turbine designs against multiscale flow irreversibility. © 2025 Elsevier Ltd

关键词： Turbine components

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Emergence of nodal-knot transitions by disorder

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science Bulletin 2025年

作者： Gong, Ming Zhao, Peng-Lu Lu, Hai-Zhou Niu, Qian Xie, X.C. International Center for Quantum Materials School of Physics Peking University Beijing100871 China Department of Physics University of Science and Technology of China Hefei230026 China Shenzhen518055 China Shenzhen518045 China CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics University of Science and Technology of China Hefei230026 China International Center for Quantum Design of Functional Materials University of Science and Technology of China Hefei230026 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Hefei National Laboratory Hefei230088 China

Under certain symmetries, degenerate points in three-dimensional metals form one-dimensional nodal lines. These nodal lines sometimes exhibit intricate knotted structures and have been studied in various contexts. As one of the most common physical perturbations, disorder effects often trigger novel quantum phase transitions. For nodal-knot phases, whether disorder can drive knot transitions remains an open and intriguing question. Employing renormalization-group calculations, we demonstrate that nodal-knot transitions emerge in the presence of weak disorder. Specifically, both chemical-potential-type and magnetic-type disorders can induce knot transitions, resulting in the emergence of distinct knot topologies. The transition can be quantitatively characterized by changes in topological invariants such as the knot Wilson loop integrals. Our findings open up a new avenue for manipulating the topology of nodal-knot phases through disorder effects. © 2025 science China Press

关键词： Disorder Nodal-knot Renormalization group Topological phase transition

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Electronic, adsorption, and hydration structures of water-contained Na-montmorillonite and Na-beidellite through the first-principles method combined with the classical solution theory

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Physical Review Materials 2022年第2期6卷 025001-025001页

作者： Satoshi Hagiwara Yasunobu Ando Yuta Goto Susumu Shinoki Minoru Otani Center for Computational Sciences University of Tsukuba 1-1-1 Tenno-dai Tsukuba Ibaraki 305-8577 Japan Research Center for Computational Design of Advanced Functional Materials (CD-FMat) National Institute of Advanced Industrial Science and Technology (AIST) 1-1-1 Umezono Tsukuba Ibaraki 305-8568 Japan Iwaki Laboratory Kunimine Industries Co. Ltd. 23-5 Kuidesaku Jobanshimofunao-machi Iwakishi Fukushima 972-8312 Japan

We investigated the electronic and hydration structures of montmorillonite (MMT) and beidellite (BEI) using a first-principles method combined with classical solution theory. Both MMT and BEI belong to a family of clay minerals with a layered structure containing water molecules and cations in the interlayer. First, we optimized the number of accumulated water molecules in the interlayer space and found the present results to be in reasonable agreement with previous experiments. Next, we refined the positions of the cations to determine the most stable structure based on the adsorption energy of the clay layers. We found that the cations in the interlayer stably adsorb to the clay layers and the most stable adsorption site is the center of the six-membered ring. The hydration structure strongly depends on the cation adsorption structure based on the charge density distribution of the water. In contrast, the electronic state is weakly dependent on the adsorption structure because of its insulating electronic structure. Therefore, our results strongly suggest that the physical properties of MMT and BEI arise from changes in the hydration structure induced by cation adsorption/desorption.

关键词： Charge Electronic structure Electrostatic interactions Van der Waals interaction Clay gels Liquid-solid interfaces Density functional theory

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Coexistence of Robust Edge States and Superconductivity in Few-Layer Stanene

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Physical Review Letters 2022年第20期128卷 206802-206802页

作者： Chenxiao Zhao Leiqiang Li Liying Zhang Jin Qin Hongyuan Chen Bing Xia Bo Yang Hao Zheng Shiyong Wang Canhua Liu Yaoyi Li Dandan Guan Ping Cui Zhenyu Zhang Jinfeng Jia Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education) Shenyang National Laboratory for Materials Science School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China International Center for Quantum Design of Functional Materials (ICQD) Hefei National Laboratory for Physical Sciences at Microscale (HFNL) and CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Key Laboratory for Special Functional Materials of Ministry of Education Collaborative Innovation Center of Nano Functional Materials and Applications School of Materials Science and Engineering Henan University Kaifeng 475004 China International Laboratory for Quantum Functional Materials of Henan and School of Physics and Microelectronics Zhengzhou University Zhengzhou 450001 China Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai 200240 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

High-quality stanene films have been actively pursued for realizing not only quantum spin Hall edge states without backscattering, but also intrinsic superconductivity, two central ingredients that may further endow the systems to host topological superconductivity. Yet to date, convincing evidence of topological edge states in stanene remains to be seen, let alone the coexistence of these two ingredients, owing to the bottleneck of growing high-quality stanene films. Here we fabricate one- to five-layer stanene films on the Bi(111) substrate and observe the robust edge states using scanning tunneling microscopy/spectroscopy. We also measure distinct superconducting gaps on different-layered stanene films. Our first-principles calculations further show that hydrogen passivation plays a decisive role as a surfactant in improving the quality of the stanene films, while the Bi substrate endows the films with nontrivial topology. The coexistence of nontrivial topology and intrinsic superconductivity renders the system a promising candidate to become the simplest topological superconductor based on a single-element system.

关键词： Growth Topological insulators Elemental superconductors Stanene Topological superconductors First-principles calculations Molecular beam epitaxy Scanning tunneling microscopy Scanning tunneling spectroscopy

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Development Research of the Double “L” Shaped Steel Plate-Concrete Composite Shear Wall

Development Research of the Double “L” Shaped Steel Plate-...

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作者： Wenhui He Yikun Wan Yuyu Li Lin Chen State Key Laboratory of Subtropical Building Science South China University of Technology College of Water Conservancy and Civil Engineering South China Agricultural University Guangdong Jianke Architectural Design Institute of Guangdong Province Co. Ltd

A double steel plates composite shear wall member composed of "L" elements(D-L-SCW) was proposed in this paper and its seismic behavior was preliminarily studied. With the shear-span ratio as test parameter, two specimens with actual ratio of 0.5 were constructed and tested in horizontal low-cycle reverse loading test. The failure modes, hysteretic behavior, skeleton curve, ductility and energy dissipation of the specimens were studied. Results showed that the suggested composite shear wall has significant seismic performance and can make more full use of the properties of both materials. The shear-span ratio mainly affected the peak load of the specimens, whilst it didn't affect the overall deformation trend.

关键词： Double "L" shaped steel plate development research composite shear wall horizontal low cycle reverse test

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Efficient purification of impurities from depleted uranium chips by hydrogen plasma arc melting

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Vacuum 2025年 240卷

作者： Yanhu Li Cun Hu Yuanfen Cheng Zhen Lei Hongya Li The 404 Company Limited China National Nuclear Corporation Jiayuguan 735100 China Chengdu Nuclear Engineering Design & Research Institute Co. Ltd. 404. CNNC Chengdu 610000 China State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology Wuhan 430074 China

Recycling and utilization of depleted uranium (DU) chips is highly significant for the development of nuclear energy and environmental safety. In this paper, the removal of non-metallic and metallic impurities from DU chips by plasma arc melting with pure Ar (PAM) and H 2 -Ar mixture (HPAM) was examined, respectively. Experimental results demonstrate that HPAM exhibits a significantly superior impurity removal effect compared to PAM. Notably, the average removal degree of non-metallic impurities in DU chips using HPAM with a 20 % H 2 -Ar mixture gas for 30 min can reach 82.8 %, which is much higher than 10.9 % achieved by PAM. Meanwhile, average removal degree of metallic impurities increased from 37.9 % for PAM to 67.5 % for HPAM. Therefore, HPAM can rapidly and efficiently remove non-metallic and metallic impurities from DU chips, thereby promoting the recycling and reuse of DU materials, and providing a reliable guarantee for the development of nuclear energy and environmental safety.

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Scheme for automatic differentiation of complex loss functions with applications in quantum physics

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Physical Review E 2021年第1期103卷 013309-013309页

作者： Chu Guo Dario Poletti Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha 410081 China Science and Math Cluster and Engineering Product Development Singapore University of Technology and Design 8 Somapah Road 487372 Singapore

The past few years have seen a significant transfer of tools from machine learning to solve quantum physics problems. Automatic differentiation is one standard algorithm used to efficiently compute gradients of loss functions for generic neural networks. In this work we show how to extend automatic differentiation to the case of complex loss function in a way that can be readily implemented in existing frameworks and which is compatible with the common case of real loss functions. We then combine this tool with matrix product states and apply it to compute the ground state and the steady state of a close and an open quantum system. Compared to the traditional density matrix renormalization group algorithm, complex automatic differentiation allows both straightforward GPU accelerations as well as generalizations to different types of tensor and neural networks.

关键词： Density matrix methods Machine learning

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