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The rule of four:anomalous distributions in the stoichiometries of inorganic compounds

npj computational Materials 2024年第1期10卷 2479-2486页

作者： Elena Gazzarrini Rose K.Cersonsky Marnik Bercx Carl S.Adorf Nicola Marzari Theory and Simulation of Materials(THEOS)and National Center for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland Department of Chemical and Biological Engineering University of Wisconsin-MadisonMadisonWIUSA

Why are materials with specific characteristics more abundant than others?This is a fundamental question in materials science and one that is traditionally difficult to tackle,given the vastness of compositional and configurational *** highlight here the anomalous abundance of inorganic compounds whose primitive unit cell contains a number of atoms that is a multiple of *** occurrence—named here the rule of four—has to our knowledge not previously been reported or ***,we first highlight the rule’s existence,especially notable when restricting oneself to experimentally known compounds,and explore its possible relationship with established descriptors of crystal structures,from symmetries to *** then investigate this relative abundance by looking at structural descriptors,both of global(packing configurations)and local(the smooth overlap of atomic positions)*** to intuition,the overabundance does not correlate with lowenergy or high-symmetry structures;in fact,structures which obey the rule of four are characterized by low symmetries and loosely packed arrangements maximizing the free *** are able to correlate this abundance with local structural symmetries,and visualize the results using a hybrid supervised-unsupervised machine learning method.

关键词： method inorganic rule

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A non-equilibrium wall model: application to the QinetiQ high-lift aircraft

A non-equilibrium wall model: application to the QinetiQ hig...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Agrawal, Rahul Bose, Sanjeeb T. Moin, Parviz Department of Mechanical Engineering Center for Turbulence Research Stanford University United States Cadence Design Systems Inc Institute for Computational and Mathematical Engineering Center for Turbulence Research Stanford University United States Dept. of Mechanical Engineering Center for Turbulence Research Stanford University United States

ISBN: (纸本)9781624107238

This work applies the non-equilibrium wall model of Agrawal et al., 2024 (arXiv preprint arXiv:2407.11390) to the flow over the QinetiQ High-Lift Common Research Model aircraft at low angles of attack. This choice is motivated by the previously reported misprediction of flow separation on the trailing edges of the flap in wall-modeled large-eddy simulations of this aircraft. It is shown that the proposed non-equilibrium model identifies conditions where the boundary layer significantly departs from equilibrium conditions around the trailing edges of the flap and the wing-body fairing. Further, the model provides improved predictions of the integrated loads, such as the lift, pitching moment, and drag in this regime for two grids containing 103 and 384 million control volumes, respectively, relative to the equilibrium wall model. The surface pressure data suggests the overprediction of lift from the equilibrium wall model is correlated with an overproduction of the suction peak and the reduced Cp flattening around the flaps. Finally, it is also shown that the refinement of the fuselage boundary layer and the uniformity of the grid distribution on the wing elements can further improve the predictions of flap separation. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Flow separation

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Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators

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National Science Review 2024年第2期11卷 15-23页

作者： Rui Chen Hai-Peng Sun Mingqiang Gu Chun-Bo Hua Qihang Liu Hai-Zhou Lu X.C.Xie Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) International Quantum Academy Institute for Theoretical Physics and Astrophysics University of Würzburg School of Electronic and Information Engineering Hubei University of Science and Technology Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering International Center for Quantum Materials School of PhysicsPeking University Collaborative Innovation Center of Quantum Matter CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences

The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.

关键词： layerHall effect hidden Berry curvature antiferromagnetic insulator axion insulator, quantum transport

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Variable stiffness design optimization of fiber-reinforced composite laminates with regular and irregular holes considering fiber continuity for additive manufacturing

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Chinese Journal of Aeronautics 2025年第3期38卷 334-354页

作者： Yi LIU Zunyi DUAN Chunping ZHOU Yuan SI Chenxi GUAN Yi XIONG Bin XU Jun YAN Jihong ZHU School of Mechanics Civil Engineering&ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Key Lab for Airborne Hi-performance Electro-magnetic Window RISACJinan 130012China School of System Design and Intelligent Manufacturing Southern University of Science and TechnologyShenzhen 518055China State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian 116024China State IJR Center of Aerospace Design and Additive Manufacturing MIIT Lab of Metal Additive Manufacturing and Innovative DesignNorthwestern Polytechnical UniversityXi’an 710072China

Fiber-reinforced composites are an ideal material for the lightweight design of aerospace structures. Especially in recent years, with the rapid development of composite additive manufacturing technology, the design optimization of variable stiffness of fiber-reinforced composite laminates has attracted widespread attention from scholars and industry. In these aerospace composite structures, numerous cutout panels and shells serve as access points for maintaining electrical, fuel, and hydraulic systems. The traditional fiber-reinforced composite laminate subtractive drilling manufacturing inevitably faces the problems of interlayer delamination, fiber fracture, and burr of the laminate. Continuous fiber additive manufacturing technology offers the potential for integrated design optimization and manufacturing with high structural performance. Considering the integration of design and manufacturability in continuous fiber additive manufacturing, the paper proposes linear and nonlinear filtering strategies based on the Normal Distribution Fiber Optimization (NDFO) material interpolation scheme to overcome the challenge of discrete fiber optimization results, which are difficult to apply directly to continuous fiber additive manufacturing. With minimizing structural compliance as the objective function, the proposed approach provides a strategy to achieve continuity of discrete fiber paths in the variable stiffness design optimization of composite laminates with regular and irregular holes. In the variable stiffness design optimization model, the number of candidate fiber laying angles in the NDFO material interpolation scheme is considered as design variable. The sensitivity information of structural compliance with respect to the number of candidate fiber laying angles is obtained using the analytical sensitivity analysis method. Based on the proposed variable stiffness design optimization method for complex perforated composite laminates, the numerical examples cons

关键词： Variable stiffness composite laminates Discrete material interpolation scheme Normal distribution fiber optimization Discrete fiber continuous filtering strategy Additive manufacturing of composite laminates

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Application of Sellars-Tagart constitutive law to modelling of stir-friction welding of CuCrZr plates 13

Application of Sellars-Tagart constitutive law to modelling ...

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13th International Symposium on Plasticity and Impact Mechanics, IMPLAST 2022

作者： Jha, Kaushal Mehra, Vishal Singh, R.N. Engineering Design and Development Division Bhabha Atomic Research Center Mumbai India Computational Analysis Division Bhabha Atomic Research Center Visakhapatnam India Materials Metallurgy Division Bhabha Atomic Research Center Mumbai India

Friction-stir welding (FSW) is a relatively new solid-state welding technique in which a non-consumable rotating tool is inserted between workpiece plates and travels along the line joining the workpieces. Thermal softening is induced in the workpieces by friction at workpiece-tool interface and leads to, along with the material dragging by tool, mixing of materials in the stirred zone. FSW avoids defects resulting from melting and recrystallization of the workpiece material. Numerical simulations are useful in understanding the FSW process. We report simulations, carried out using Smoothed Particle Hydrodynamics technique, of previously published FSW experiments of 15 cm by 6 cm CuCrZr plates. The CuCrZr alloy is represented as a viscoplastic material using Sellers-Tagert constitutive law which provides flow stress as a function of temperature, strain rate and a material-dependent deformation activation energy. Thermal effects are included via a heat generation model, a heat conduction model and heat loss model to the backing plate. Simulations are done in two dimensions with the tool modeled as a moving and rotating boundary with a specified velocity and are carried out for 10–15 s. Width of the stirred zone where the particles of two plates mix is inferred from the final configuration along with temperature distribution of the plates. For the tool at 1000 rpm and 80 mm/min travel velocity, the width of the stirred zone was 24 mm and maximum temperature 12 mm away from the weld centerline was 760 K from simulations compared with 20 mm and 960 K experimentally resp. © 2023 Elsevier Ltd. All rights reserved.

关键词： Friction

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Urban airflow prediction by pix2pix trained on FFD

Urban airflow prediction by pix2pix trained on FFD

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2023 International Conference on the Built Environment in Transition, CISBAT 2023

作者： Vecchiarelli, Rebekah Kraus, Michael Griego, Danielle Waibel, Christoph ETH Zürich Switzerland Center for Augmented Computational Design in Architecture Engineering and Construction ETH Zürich Switzerland Future Cities Lab Global ETH Zürich Switzerland

Existing computer-aided design tools render insufficient in their capacity to enable architects and engineers to efficiently evaluate alternative designs during early design phases due to their computationally expensive nature, which is especially the case for computational fluid dynamics (CFD) methods. One of the greatest bottleneck for integrating CFD analysis into early design phases is the limited potential for parametric analysis, where a number of design alternatives need to be quickly generated and evaluated. In this context, the present study investigates the use of the generative deep learning method "pix2pix", which leverages conditional generative adversarial networks (cGANs) for image-to-image translation, for prediction of airflow characteristics in different representations. The evaluation proposes statistical metrics to judge the fitness of the approach in performing urban airflow prediction. Our study demonstrates that the proposed method to be implemented, trained and validated successfully for different representations of the flow field prediction under parametric city shapes by incorporating building height and vectorial information (either components or magnitudes) into the pix2pix image inputs. The findings of the study reveal that the vortical flow fields can be predicted with a high accuracy in space and magnitude in all model variations tested. Adding building height information to the input images also significantly improves Kullback-Leibler (KL) divergence compared to using uniform building heights as inputs. Using vectorial information in the form of decomposed u, v, w-vector fields during training enabled pix2pix to additionally generate vectorial predictions instead of magnitudes only. © 2023 Institute of Physics Publishing. All rights reserved.

关键词： Forecasting

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Affinity-Engineered Flexible Scaffold toward Energy-Dense, Highly Reversible Na Metal Batteries

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Energy & Environmental Materials 2023年第2期6卷 344-352页

作者： Yujie Liu Miao Bai Dou Du Xiaoyu Tang Helin Wang Min Zhang Ting Zhao Fu Liu Zhiqiao Wang Yue Ma State Key Laboratory of Solidification Processing Center for Nano Energy MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene(NPU)Xi’an 710072China National Centre for Computational Design and Discovery of Novel Materials(MARVEL) École Polytechnique F´ed´erale de LausanneCH-1015Lausanne Switzerland

The practical deployment of metallic anodes in the energy-dense batteries is impeded by the thermodynamically unstable interphase in contact with the aprotic electrolyte,structural collapse of the substrates as well as their insufficient affinity toward the metallic ***,the mechanical flexible,lightweight(1.2 mg cm^(−2))carbon nanofiber scaffold with the monodispersed,ultrafine Sn_(4)P_(3) nanoparticles encapsulation(Sn_(4)P_(3)NPs@CNF)is proposed as the deposition substrate toward the high-areal-capacity sodium loadings up to 4 mAh cm^(−2).First-principles calculations manifest that the alloy intermediates,namely the Na_(15)Sn_(4) and Na_(3)P matrix,exhibit the intimate Na affinity as the“sodiophilic”***,the porous CNF regulates the heterogeneous alloying process and confines the deposit propagation along the nanofiber *** the precise control of pairing mode with the NaVPO4F cathode(8.7 mg cm^(−2)),the practical feasibility of the Sn_(4)P_(3) NPs@CNF anode(1^(*)Na excess)is demonstrated in 2 mAh single-layer pouch cell prototype,which achieves the 95.7%capacity retention for 150 cycles at various mechanical flexing states as well as balanced energy/power densities.

关键词： energy-dense prototype flexible sodium metal batteries heterogeneous alloying nanoconfinement effect Sn4P3 nanocrystalline

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Fe single atom trigger asymmetric In-In polarized site pairs boosting near-infrared N2 photoreduction

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Materials Today 2025年 86卷 96-103页

作者： Liang, Huimin Ye, Caichao Wu, Yao Li, Yezi Long, Ran Xiong, Jun Jiang, Wei Di, Jun School of Chemistry and Chemical Engineering National Special Superfine Powder Engineering Research Center Nanjing University of Science and Technology Nanjing210094 China Academy for Advanced Interdisciplinary Studies & Department of Materials Science and Engineering Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen518055 China School of Materials Science & Engineering Nanyang Technological University Singapore639798 Singapore National Synchrotron Radiation Laboratory CAS Center for Excellence in Nanoscience School of Chemistry and Materials Science University of Science and Technology of China Hefei230026 China Institute for Energy Research Jiangsu University Zhenjiang212013 China

Building differentiated charge distributed polarized atomic pairs may be an alternative for N2 activation. In this work, CuInS2 atomic layers with asymmetric In-In polarized site pairs are prepared by doping Fe single atoms, as proved by X-ray absorption fine structure spectroscopy, quasi in situ X-ray photoelectron spectra and calculated atomic charge distribution. The engineered Fe single atoms tuned the surface atomic charge distribution, building local polarization center to boost directional surface charge separation. The formed In-In polarized site pairs with asymmetric charge distribution creates distinct interaction with two N atoms in N2 molecule, contributing to the enhanced activation of N2. The alternating pathway is regarded as hydrogenation pathway over Fe-CuInS2 with *NNH formation as rate-determining step. The charge-redistributed surface atomic structure after engineered Fe single atoms strengthens intermediate interaction and lower the rate-determining step energy barrier. Benefiting from these features, Fe-CuInS2 exhibits excellent photocatalytic activity under near-infrared (NIR) irradiation with an ammonia synthesis rate of 94.1 μmol g−1 h−1. In comparison, the N2-NH3 conversion rate of Fe-CuInS2 under ultraviolet–visible (UV–Vis) irradiation could reach 137.4 μmol g−1 h−1, which is about 6.8 times higher than that of CuInS2. The apparent quantum efficiencies of Fe-CuInS2-2 at 380, 400, 450, 500, 550, 650, 700, 800, 850 and 1064 nm were 3.0 %, 3.3 %, 2.7 %, 2.1 %, 2.0 %, 1.5 %, 1.3 %, 0.4 %, 0.7 % and 0.6 %, respectively. © 2025 Elsevier Ltd

关键词： X ray absorption fine structure spectroscopy

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Inelastic neutron scattering of hydrogen in palladium studied by semiclassical dynamics

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Physical Review B 2024年第5期109卷 054303-054303页

作者： Motoyuki Shiga Bo Thomsen Hajime Kimizuka Center for Computational Science and e-Systems Japan Atomic Energy Agency Chiba 277-0871 Japan Department of Materials Design Innovation Engineering Nagoya University Aichi 464-8603 Japan

Inelastic neutron scattering (INS) spectra of hydrogen in face-centered cubic palladium have been calculated considering nuclear quantum effects (NQEs) at finite temperatures. The calculations were performed using semiclassical Brownian chain molecular dynamics (MD) [Shiga, J. Comput. Chem. 43, 1864 (2022)] and artificial neural network potentials with an accuracy of generalized gradient approximation of density functional theory. The calculated spectra are in good agreement with experimental spectra with respect to the peak positions and intensities corresponding to the fundamental tone and the first overtone of the vibrational excitation of hydrogen atoms. These results differ significantly from those of classical MD, indicating that NQE plays an essential role in the correct estimation of the INS spectrum. Importantly, the NQE acts as a blueshift of the INS spectrum for hydrogen in the octahedral site due to strong anharmonic vibrations of hydrogen on the potential surface with even symmetry. The calculated peak shifts associated with Pd lattice distortion were also in agreement with experimental results.

关键词： Hydrogen storage materials Ab initio molecular dynamics Inelastic neutron scattering Path-integral methods Semiclassical methods

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Fifth-Order A-WENO Path-Conservative Central-Upwind Scheme for Behavioral Non-Equilibrium Traffic Models

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Communications in computational Physics 2023年第3期33卷 692-732页

作者： Shaoshuai Chu Alexander Kurganov Saeed Mohammadian Zuduo Zheng Department of Mathematics Southern University of Science and TechnologyShenzhen518055P.R.China Shenzhen International Center for Mathematics and Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and TechnologyShenzhen518055P.R.China School of Civil Engineering the University of QueenslandBrisbane Qld4072Australia.

Non-equilibrium hyperbolic traffic models can be derived as continuum approximations of car-following models and in many cases the resulting continuum models are *** leads to numerical difficulties,which seem to have discouraged further development of complex behavioral continuum models,which is a significant research *** this paper,we develop a robust numerical scheme that solves hyperbolic traffic flow models based on their non-conservative *** develop a fifth-order alternative weighted essentially non-oscillatory(A-WENO)finite-difference scheme based on the path-conservative central-upwind(PCCU)method for several non-equilibrium traffic flow *** order to treat the non-conservative product terms,we use a path-conservative *** this end,we first apply the recently proposed secondorder finite-volume PCCU scheme to the traffic flow models,and then extend this scheme to the fifth-order of accuracy via the finite-difference A-WENO *** designed schemes are applied to three different traffic flow models and tested on a number of challenging numerical *** schemes produce quite accurate results though the resolution achieved by the fifth-order A-WENO scheme is *** proposed scheme in this paper sets the stage for developing more robust and complex continuum traffic flow models with respect to human psychological factors.

关键词： Finite-difference A-WENO schemes finite-volume central-upwind schemes pathconservative central-upwind schemes non-oscillatory schemes continuum traffic flow model driver behavior.

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