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arXiv 2019年

作者： Cinacchi, Giorgio Torquato, Salvatore Instituto de Ciencias de Materiales "Nicolás Cabrera" Universidad Autónoma de Madrid Ciudad Universitaria de Cantoblanco MadridE-28049 Spain Department of Chemistry Department of Physics Institute for the Science and Technology of Materials Program for Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Among the family of hard convex lens-shaped particles (lenses), the one with aspect ratio equal to 2/3 is ‘optimal’ in the sense that the maximally random jammed (MRJ) packings of such lenses achieve the highest packing fraction φMRJ ' 0.73. This value is only a few percent lower than φDKP = 0.76210 . . . , the packing fraction of the corresponding densest-known crystalline (degenerate) packings. By exploiting the appreciably reduced propensity that a system of such optimal lenses has to positionally and orientationally order, disordered packings of them are progressively generated by a Monte Carlo method-based procedure from the dilute equilibrium isotropic fluid phase to the dense nonequilibrium MRJ state. This allows one to closely monitor how the (micro)structure of these packings changes in the process of formation of the MRJ state. The gradual changes undergone by the many structural descriptors calculated can coherently and consistently be traced back to the gradual increase in contacts between the hard particles until the isostatic mean value of 10 contact neighbors per lens is reached at the effectively hyperuniform MRJ state. Compared to the MRJ state of hard spheres, the MRJ state of such optimal lenses is denser (less porous), more disordered, and rattler-free. This set of characteristics makes them good glass formers. It is possible that this conclusion may also hold for other hard convex uniaxial particles with a correspondingly similar aspect ratio, be they oblate or prolate, and that, by using suitable biaxial variants of them, that set of characteristics might further improve. Copyright © 2019, The Authors. All rights reserved.

关键词： Aspect ratio

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Snowmass2021 CMB-HD White Paper

arXiv

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arXiv 2022年

作者： Aiola, Simone Akrami, Yashar Basu, Kaustuv Boylan-Kolchin, Michael Brinckmann, Thejs Bryan, Sean Casey, Caitlin M. Chluba, Jens Clesse, Sébastien Cyr-Racine, Francis-Yan Di Mascolo, Luca Dicker, Simon Essinger-Hileman, Thomas Farren, Gerrit S. Fedderke, Michael A. Ferraro, Simone Fuller, George M. Galitzki, Nicholas Gluscevic, Vera Grin, Daniel Han, Dongwon Hasselfield, Matthew Hložek, Renée Holder, Gil Hotinli, Selim C. Jain, Bhuvnesh Johnson, Bradley Johnson, Matthew Klaassen, Pamela MacInnis, Amanda Madhavacheril, Mathew Mandal, Sayan Mauskopf, Philip Meerburg, Daan Meyers, Joel Miranda, Vivian Mroczkowski, Tony Mukherjee, Suvodip Münchmeyer, Moritz Munoz, Julian Naess, Sigurd Nagai, Daisuke Namikawa, Toshiya Newburgh, Laura Nguyên, Hô Nam Niemack, Michael Oppenheimer, Benjamin D. Pierpaoli, Elena Raghunathan, Srinivasan Schaan, Emmanuel Sehgal, Neelima Sherwin, Blake Simon, Sara M. Slosar, Anže Smith, Kendrick Spergel, David Switzer, Eric R. Trivedi, Pranjal Tsai, Yu-Dai van Engelen, Alexander Wandelt, Benjamin D. Wollack, Edward J. Wu, Kimmy Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States CERCA ISO Department of Physics Case Western Reserve University 10900 Euclid Avenue ClevelandOH44106 United States Department of Physics Imperial College London Blackett Laboratory Prince Consort Road LondonSW7 2AZ United Kingdom Laboratoire de Physique de l’École Normale Supérieure ENS Université PSL CNRS Sorbonne Université ParisF-75005 France Observatoire de Paris Université PSL Sorbonne Université LERMA Paris750 France Argelander Institute for Astronomy University of Bonn Auf dem Hügel 71 BonnD-53121 Germany Department of Astronomy The University of Texas at Austin 2515 Speedway Stop C1400 AustinTX78712 United States Dipartimento di Fisica e Scienze della Terra Universitá degli Studi di Ferrara via Giuseppe Saragat 1 Ferrara44122 Italy Sezione di Ferrara Via Giuseppe Saragat 1 Ferrara44122 Italy School of Earth and Space Exploration Arizona State University 781 Terrace Mall TempeAZ85287 United States Jodrell Bank Centre for Astrophysics Alan Turing Building University of Manchester ManchesterM13 9PL United Kingdom Université Libre de Bruxelles Boulevard du Triomphe Brussels1050 Belgium Department of Physics and Astronomy University of New Mexico 210 Yale Blvd NE AlbuquerqueNM87106 United States Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 Trieste34131 Italy INAF Osservatorio Astronomico di Trieste via Tiepolo 11 Trieste34131 Italy IFPU - Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste340 Italy Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street PhiladelphiaPA19104 United States NASA/Goddard Space Flight Center GreenbeltMD20771 United States Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom Department of Physics and Astronomy Haverford College 370 Lancaste

CMB-HD is a proposed millimeter-wave survey over half the sky that would be ultra-deep (0.5 µK-arcmin) and have unprecedented resolution (15 arcseconds at 150 GHz). Such a survey would answer many outstanding questions about the fundamental physics of the Universe. Major advances would be 1.) the use of gravitational lensing of the primordial microwave background to map the distribution of matter on small scales (k ∼ 10 hMpc-1), which probes dark matter particle properties. It will also allow 2.) measurements of the thermal and kinetic Sunyaev-Zel’dovich effects on small scales to map the gas density and velocity, another probe of cosmic structure. In addition, CMB-HD would allow us to cross critical thresholds: 3.) ruling out or detecting any new, light ( © 2022, CC BY.

关键词： Telescopes

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Global optical model potential for the weakly bound projectile Be9

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Physical Review C 2019年第3期99卷 034618-034618页

作者： Yongli Xu Yinlu Han Haiying Liang Zhendong Wu Hairui Guo Chonghai Cai College of Physics and Electronic Science Shanxi Datong University Datong 037009 China Key Laboratory of Nuclear Data China Institute of Atomic Energy P.O. Box (275-41) Beijing 102413 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Department of Physics Nankai University Tianjin 300071 China

The global optical model potential for the Be9 projectile is developed by systematically studying the experimental data of elastic-scattering angular distributions and reaction cross sections from Mg24 to Bi209 below 100 MeV. The analysis is performed in terms of comparing the theoretical results with the available experimental data. A satisfactory agreement is observed in the whole energy and target mass regions. Moreover, the elastic-scattering angular distributions and reaction cross sections of Be9 on some lighter targets are also predicted using the global optical model potential and a reasonable description of the experimental data is obtained.

关键词： Nuclear reactions Optical, coupled-channel & distorted wave models 6 ≤ A ≤ 19

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Constructing Impactful Machine Learning Research for Astronomy: Best Practices for Researchers and Reviewers

arXiv

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arXiv 2023年

作者： Huppenkothen, Daniela Ntampaka, Michelle Ho, Matthew Fouesneau, Morgan Nord, Brian Peek, J.E.G. Walmsley, Mike Wu, John F. Avestruz, C. Buck, Tobias Brescia, Massimo Finkbeiner, Douglas P. Goulding, Andy D. Kacprzak, T. Melchior, Peter Pasquato, Mario Ramachandra, Nesar Ting, Yuan-Sen van de Ven, Glenn Villar, Soledad Villar, V.A. Zinger, Elad SRON Netherlands Institute for Space Research Niels Bohrweg 4 Leiden2333CA Netherlands Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Space Telescope Science Institute BaltimoreMD21218 United States Department of Physics & Astronomy Johns Hopkins University BaltimoreMD21218 United States UMR 7095 98 bis bd Arago ParisF-75014 France Königstuhl 17 HeidelbergD-69117 Germany Fermi National Accelerator Laboratory P. O. Box 500 BataviaIL60510 United States Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL60637 United States Jodrell Bank Centre for Astrophysics Department of Physics & Astronomy University of Manchester ManchesterM13 9PL United Kingdom Dunlap Institute for Astronomy & Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Leinweber Center for Theoretical Physics University of Michigan Ann ArborMI48109 United States Department of Physics University of Michigan Ann ArborMI48109 United States Universität Heidelberg Interdisziplinäres Zentrum für Wissenschaftliches Rechnen Im Neuenheimer Feld 205 Heidelberg69120 Germany Universität Heidelberg Zentrum für Astronomie Institut für Theoretische Astrophysik Albert-Ueberle-Straße 2 Heidelberg69120 Germany Department of Physics "E. Pancini " University Federico II of Napoli Via Cinthia 21 NapoliI-80126 Italy INAF Astronomical Observatory of Capodimonte Salita Moiariello 16 NapoliI-80131 Italy Department of Physics Harvard University 17 Oxford St. CambridgeMA02138 United States Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States Department of Astrophysical Sciences Princeton University PrincetonNJ08544 United States Swiss Data Science Center Paul Scherrer Institute Villigen5303 Switzerland Center for Statistics & Machine Learn

Machine learning has rapidly become a tool of choice for the astronomical community. It is being applied across a wide range of wavelengths and problems, from the classification of transients to neural network emulators of cosmological simulations, and is shifting paradigms about how we generate and report scientific results. At the same time, this class of method comes with its own set of best practices, challenges, and drawbacks, which, at present, are often reported on incompletely in the astrophysical literature. With this paper, we aim to provide a primer to the astronomical community, including authors, reviewers, and editors, on how to implement machine learning models and report their results in a way that ensures the accuracy of the results, reproducibility of the findings, and usefulness of the method. Copyright © 2023, The Authors. All rights reserved.

关键词： Machine learning

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Active learning of uniformly accurate inter-atomic potentials for materials simulation

arXiv

引用

arXiv 2018年

作者： Zhang, Linfeng Lin, De-Ye Wang, Han Car, Roberto Weinan, E. Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Institute of Applied Physics and Computational Mathematics Huayuan Road 6 Beijing100088 China CAEP Software Center for High Performance Numerical Simulation Huayuan Road 6 Beijing100088 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Huayuan Road 6 Beijing100088 China Department of Chemistry Department of Physics Program in Applied and Computational Mathematics Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Department of Mathematics and Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Beijing Institute of Big Data Research Beijing100871 China

An active learning procedure called Deep Potential Generator (DP-GEN) is proposed for the construction of accurate and transferable machine learning-based models of the potential energy surface (PES) for the molecular modeling of materials. This procedure consists of three main components: exploration, generation of accurate reference data, and training. Application to the sample systems of Al, Mg and Al-Mg alloys demonstrates that DP-GEN can produce uniformly accurate PES models with a minimal number of reference data. Copyright © 2018, The Authors. All rights reserved.

关键词： Potential energy

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Multifunctional Composites for Elastic and Electromagnetic Wave Propagation

arXiv

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arXiv 2019年

作者： Kim, Jaeuk Torquato, Salvatore Department of Physics Princeton University PrincetonNJ08544 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Composites are ideally suited to achieve desirable multifunctional effective properties, since the best properties of different materials can be judiciously combined with designed microstructures. Here we establish the first cross-property relations for two-phase composite media that link effective elastic and electromagnetic wave characteristics to one another, including effective wave speeds and attenuation coefficients. This is achieved by deriving accurate formulas for the effective elastodynamic properties that depend on the microstructure via the spectral density and utilizing previous analogous results for effective electromagnetic properties. Our formulas enable us to explore the wave characteristics of a broad class of disordered microstructures, including exotic disordered "hyperuniform" varieties, that can have advantages over crystalline ones, such as nearly optimal, direction-independent properties and robustness against defects. We specifically show that disordered "stealthy" hyperuniform/nonhyperuniform microstructures exhibit novel elastic wave characteristics that have the potential for future applications, e.g., low-pass or narrow-band-pass (using negative Poisson ratio materials) filters that transmit or absorb elastic waves "isotropically" for a range of wavenumbers. We also demonstrate that two-phase media with engineered disorder and phase properties can exhibit "anomalous dispersion" with resonance-like attenuation. Our cross-property relations for effective wave characteristics can be applied to design multifunctional composites via inverse techniques, including exterior components of spacecraft or building materials that require both excellent stiffness and electromagnetic absorption, and heat-sinks for CPUs that have to efficiently emit thermal radiation and suppress mechanical vibrations, and nondestructive evaluation of the elastic moduli of materials from the effective dielectric response. DR Copyright © 2019, The Authors. All rights res

关键词： Microstructure

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New tessellation-based procedure to design perfectly hyperuniform disordered dispersions for materials discovery

arXiv

引用

arXiv 2019年

作者： Kim, J. Torquato, S. Department of Physics Princeton University PrincetonNJ08544 United States Department of Chemistry Princeton University PrincetonNJ08544 United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Disordered hyperuniform dispersions are exotic amorphous two-phase materials characterized by an anomalous suppression of long-wavelength volume-fraction fluctuations, which endows them with novel physical properties. While such unusual materials have received considerable attention, a stumbling block has been an inability to create large samples that are truly hyperuniform due to current computational and experimental limitations. To overcome such barriers, we introduce a new and simple construction procedure that guarantees perfect hyperuniformity for very large sample sizes. This methodology involves tessellating space into cells and then inserting a particle into each cell such that the local-cell particle packing fractions are identical to the global packing fraction. We analytically prove that such dispersions are perfectly hyperuniform in the infinite-sample-size limit. Our methodology enables a remarkable mapping that converts a very large nonhyperuniform disordered dispersion into a perfectly hyperuniform one, which we numerically demonstrate in two and three dimensions. A similar analysis also establishes the hyperuniformity of the famous Hashin-Shtrikman multiscale dispersions, which possess optimal transport and elastic properties. Our hyperuniform designs can be readily fabricated using modern photolithographic and 3D printing technologies. The exploration of the enormous class of hyperuniform dispersions that can be designed and tuned by our tessellation-based methodology paves the way for accelerating the discovery of novel hyperuniform materials. Copyright © 2019, The Authors. All rights reserved.

关键词： 3D printers

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Predictive modeling approaches in laser-based material processing

arXiv

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arXiv 2020年

作者： Velli, Maria-Christina Tsibidis, George D. Mimidis, Alexandros Skoulas, Evangelos Pantazis, Yannis Stratakis, Emmanuel Institute of Electronic Structure and Laser Foundation for Research and Technology - Hellas N. Plastira 100 Vassilika Vouton Heraklion70013 Greece Department of Physics University of Crete P.O. Box 2208 Heraklion71003 Greece Department of Material Science University of Crete P.O. Box 2208 Heraklion71003 Greece Institute of Applied and Computational Mathematics Foundation for Research and Technology - Hellas N. Plastira 100 Vassilika Vouton Heraklion70013 Greece

Predictive modelling represents an emerging field that combines existing and novel methodologies aimed to rapidly understand physical mechanisms and concurrently develop new materials, processes and structures. In the current study, previously-unexplored predictive modelling in a key-enabled technology, the laser-based manufacturing, aims to automate and forecast the effect of laser processing on material structures. The focus is centred on the performance of representative statistical and machine learning algorithms in predicting the outcome of laser processing on a range of materials. Results on experimental data showed that predictive models were able to satisfactorily learn the mapping between the laser’s input variables and the observed material structure. These results are further integrated with simulation data aiming to elucidate the multiscale physical processes upon laser-material interaction. As a consequence, we augmented the adjusted simulated data to the experimental and substantially improved the predictive performance, due to the availability of increased number of sampling points. In parallel, a metric to identify and quantify the regions with high predictive uncertainty, is presented, revealing that high uncertainty occurs around the transition boundaries. Our results can set the basis for a systematic methodology towards reducing material design, testing and production cost via the replacement of expensive trial-and-error based manufacturing procedure with a precise pre-fabrication predictive tool. Copyright © 2020, The Authors. All rights reserved.

关键词： Learning algorithms

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Methodology to construct large realizations of perfectly hyperuniform disordered packings

arXiv

引用

arXiv 2019年

Disordered hyperuniform packings (or dispersions) are unusual amorphous two-phase materials that are endowed with exotic physical properties. Such hyperuniform systems are characterized by an anomalous suppression of volume-fraction fluctuations at infinitely long-wavelengths, compared to ordinary disordered materials. While there has been growing interest in such singular states of amorphous matter, a major obstacle has been an inability to produce large samples that are perfectly hyperuniform due to practical limitations of conventional numerical and experimental methods. To overcome these limitations, we introduce a general theoretical methodology to construct perfectly hyperuniform packings in d-dimensional Euclidean space Rd. Specifically, beginning with an initial general tessellation of space by disjoint cells that meets a "bounded-cell" condition, hard particles are placed inside each cell such that the local-cell particle packing fractions are identical to the global packing fraction. We prove that the constructed packings with a polydispersity in size in Rd are perfectly hyperuniform in the infinite-sample-size limit and the hyperuniformity of such packings is independent of particle shapes, positions, and numbers per cell. We use this theoretical formulation to devise an efficient and tunable algorithm to generate extremely large realizations of such packings. We employ two distinct initial tessellations: Voronoi as well as sphere tessellations. Beginning with Voronoi tessellations, we show that our algorithm can remarkably convert extremely large nonhyperuniform packings into hyperuniform ones in R2 and R3. Implementing our theoretical methodology on sphere tessellations, we establish the hyperuniformity of the classical Hashin-Shtrikman multiscale coated-spheres structures, which are known to be two-phase media microstructures that possess optimal effective transport and elastic properties. A consequence of our work is a rigorous demonstration that pack

关键词： Cells

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Wavelength dependent tunneling delay time

arXiv

引用

arXiv 2019年

作者： Hao, Xiaolei Shu, Zheng Li, Weidong Chen, Jing Institute of Theoretical Physics Department of Physics State Key Laboratory of Quantum Optics and Quantum Optics Devices Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan030006 China Institute of Applied Physics and Computational Mathematics P. O. Box 8009 Beijing100088 China HEDPS Center for Applied Physics and Technology Peking University Beijing100084 China

A clear consensus on how long it takes a particle to tunnel through a potential barrier has never been so urgently required, since the electron dynamics in strong-field ionization can be resolved on attosecond time-scale in experiment and the exact nature of the tunneling process is the key to trigger subsequent attosecond techniques. Here a general picture of tunneling time is suggested by introducing a quantum travel time, which is defined as the ratio of the travel distance to the expected value of the velocity operator under the barrier. Specially, if applied to rectangular barrier tunneling, it can retrieve the Büttiker-Landauer time τBL in the case of an opaque barrier, and has a clear physical meaning in the case of a very thin barrier wherein τBL can not be well defined. In the case of strong-field tunneling process, with the help of the newly defined time, the tunneling delay time measured by attoclock experiment can be interpreted as a travel time spent by the electron to tunnel from a point under the barrier to the tunnel exit. In addition, a peculiar oscillation structure in the wavelength dependence of tunneling delay time in deep tunneling regime is observed, which is beyond the scope of adiabatic tunneling picture. This oscillation structure can be attributed to the interference between the ground state tunneling channel and the excited states tunneling channels. Copyright © 2019, The Authors. All rights reserved.

关键词： Travel time

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