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arXiv 2021年

作者： Hao, Xiaolei Bai, Yuxing Li, Chan Zhang, Jingyu Li, Weidong Yang, Weifeng Liu, MingQing 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 Department of Physics College of Science Shantou University Shantou Guangdong515063 China Institute of Applied Physics and Computational Mathematics P. O. Box 8009 Beijing100088 China Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Advanced Material Diagnostic Technology College of Engineering Physics Shenzhen Technology University Shenzhen518118 China

Consensus has been reached that recollision, as the most important post-tunneling process, is responsible for nonsequential double ionization process in intense infrared laser field, however, its effect has been restricted to interaction between the first ionized electron and the residual univalent ion so far. Here we identify the key role of recollision between the second ionized electron and the divalent ion in the below-threshold nonsequential double ionization process by introducing a Coulomb-corrected quantum-trajectories method, which enables us to well reproduce the experimentally observed cross-shaped and anti-correlated patterns in correlated two-electron momentum distributions, and also the transition between these two patterns. Being significantly enhanced relatively by the recapture process, recolliding trajectories of the second electron excited by the first- or third-return recolliding trajectories of the first electron produce the cross-shaped or anti-correlated distributions, respectively. And the transition is induced by the increasing contribution of the third return with increasing pulse duration. Our work provides new insight into atomic ionization dynamics and paves the new way to imaging of ultrafast dynamics of atoms and molecules in intense laser field. Copyright © 2021, The Authors. All rights reserved.

关键词： Ionization of gases

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Color screening in (2+1)-flavor QCD

arXiv

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arXiv 2018年

作者： Bazavov, A. Brambilla, N. Petreczky, P. Vairo, A. Weber, J.H. Department of Computational Mathematics Science and Engineering Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Physik Department Technische Universität München GarchingD-85748 Germany Institute of Advanced Studies Technische Universität München GarchingD-85748 Germany Physics Department Brookhaven National Laboratory UptonNY11973 United States Exzellenzcluster Universe Technische Universität München GarchingD-85748 Germany

We study correlation functions of spatially separated static quark-antiquark pairs in (2+1)-flavor QCD in order to investigate onset and nature of color screening at high temperatures. We perform lattice calculations in a wide temperature range, 140 ≤ T ≤ 5814 MeV, using the highly improved staggered quark action and several lattice spacings to control discretization effects. By comparing at high temperatures our lattice results to weak-coupling calculations as well as to the zero temperature result for the energy of a static quark-antiquark pair, we observe that color screening sets in at rT ≈ 0.3. Furthermore, we also observe that in the range 0.3 . rT . 0.6 weak-coupling calculations in the framework of suitable effective field theories provide an adequate picture of color *** Codes 81T25, 81T28 Copyright © 2018, The Authors. All rights reserved.

关键词： Color

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Probability-turbulence divergence: A tunable allotaxonometric instrument for comparing heavy-tailed categorical distributions

arXiv

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arXiv 2020年

作者： Dodds, Peter Sheridan Minot, Joshua R. Arnold, Michael V. Alshaabi, Thayer Adams, Jane Lydia Reagan, Andrew J. Danforth, Christopher M. Computational Story Lab Vermont Complex Systems Center MassMutual Center of Excellence for Complex Systems and Data Science University of Vermont BurlingtonVT05401 United States Vermont Advanced Computing Center University of Vermont BurlingtonVT05401 United States Department of Computer Science University of Vermont BurlingtonVT05401 United States Santa Fe Institute 1399 Hyde Park Rd Santa FeNM87501 United States MassMutual Data Science AmherstMA01002 United States Howard Hughes Medical Institute University of California Berkeley BerkeleyCA94720 United States Data Visualization Lab Khoury College of Computer Sciences Northeastern University BostonMA United States Department of Mathematics & Statistics University of Vermont BurlingtonVT05401 United States

Real-world complex systems often comprise many distinct types of elements as well as many more types of networked interactions between elements. When the relative abundances of types can be measured well, we further observe heavy-tailed categorical distributions for type frequencies. For the comparison of type frequency distributions of two systems or a system with itself at different time points in time—a facet of allotaxonometry—a great range of probability divergences are available. Here, we introduce and explore ‘probability-turbulence divergence’, a tunable, straightforward, and interpretable instrument for comparing normalizable categorical frequency distributions. We model probability-turbulence divergence (PTD) after rank-turbulence divergence (RTD). While probability-turbulence divergence is more limited in application than rank-turbulence divergence, it is more sensitive to changes in type frequency. We build allotaxonographs to display probability turbulence, incorporating a way to visually accommodate zero probabilities for ‘exclusive types’ which are types that appear in only one system. We explore comparisons of example distributions taken from literature, social media, and ecology. We show how probability-turbulence divergence either explicitly or functionally generalizes many existing kinds of distances and measures, including, as special cases, L(p) norms, the Sørensen-Dice coefficient (the F1 statistic), and the Hellinger distance. We discuss similarities with the generalized entropies of Rényi and Tsallis, and the diversity indices (or Hill numbers) from ecology. We close with thoughts on open problems concerning the optimization of the tuning of rank- and probability-turbulence divergence. Copyright © 2020, The Authors. All rights reserved.

关键词： Normal distribution

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Physics-driven Explosions of Stripped High-Mass Stars: Synthetic Light Curves and Spectra of Stripped-Envelope Supernovae with Broad Lightcurves

arXiv

引用

arXiv 2024年

作者： Lu, Jing Barker, Brandon L. Goldberg, Jared Kerzendorf, Wolfgang E. Modjaz, Maryam Couch, Sean M. Shields, Joshua V. Fullard, Andrew G. Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Computational Physics and Methods Los Alamos National Laboratory Los AlamosNM87545 United States Center for Theoretical Astrophysics Los Alamos National Laboratory Los AlamosNM87545 United States Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States Department of Astronomy University of Virginia CharlottesvilleVA22904 United States Joint Institute for Nuclear Astrophysics Center for the Evolution of the Elements Michigan State University East LansingMI48824 United States National Superconducting Cyclotron Laboratory Michigan State University East LansingMI48824 United States

Stripped-envelope supernovae (SESNe) represent a significant fraction of core-collapse supernovae, arising from massive stars that have shed their hydrogen and, in some cases, helium envelopes. The origins and explosion mechanisms of SESNe remain a topic of active investigation. In this work, we employ radiative-transfer simulations to model the light curves and spectra of a set of explosions of single, solar-metallicity, massive Wolf-Rayet (WR) stars with ejecta masses ranging from 4 to 11 M☉, that were computed from a turbulence-aided and neutrino-driven explosion mechanism. We analyze these synthetic observables to explore the impact of varying ejecta mass and helium content on observable features. We find that the light curve shape of these progenitors with high ejecta masses is consistent with observed SESNe with broad light curves but not the peak luminosities. The commonly used analytic formula based on rising bolometric light curves overestimates the ejecta mass of these high-initial-mass progenitor explosions by a factor up to 2.6. In contrast, the calibrated method by Haynie et al., which relies on late-time decay tails, reduces uncertainties to an average of 20% within the calibrated ejecta mass range. Spectroscopically, the He I 1.083 µm line remains prominent even in models with as little as 0.02 M☉ of helium. However, the strength of the optical He I lines is not directly proportional to the helium mass but instead depends on a complex interplay of factors such as 56Ni distribution, composition, and radiation field. Thus, producing realistic helium features requires detailed radiative transfer simulations for each new hydrodynamic model. © 2024, CC BY.

关键词： Giant stars

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Real-Time Data Collection of Wsn Based on Trajectory Optimization of Laser-Charged Uav

SSRN

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SSRN 2023年

作者： Luo, Chuanwen Hong, Yi Hou, Yunan Zhu, Yuqing Li, Deying Yu, Dongxiao Wu, Weili School of Information Science and Technology Beijing Forestry University Beijing100083 China Engineering Research Center for Forestry-oriented Intelligent Information Processing of National Forestry and Grassland Administration Beijing100083 China Research Center of Applied Mathematics and Machine Intelligence Zhejiang Lab Zhejiang Hangzhou311121 China Department of Computer Science California State University Los AngelesCA90032 United States School of Information Renmin University of China Beijing100872 China School of Computer Science and Technology Institute of Intelligent Computing Shandong University Qingdao266510 China Department of Computer Science The University of Texas at Dallas RichardsonTX75080 United States

Unmanned Aerial Vehicle (UAV) can be used as wireless aerial mobile base station for collecting data from sensors in UAV-based Wireless Sensor Networks (WSNs), which is crucial for providing seamless services and improving the performance in the next generation wireless networks. However, since the UAV are powered by batteries with limited energy capacity, the UAV can not complete data collection tasks of all sensors without energy replenishment when a large number of sensors are deployed over large monitoring areas. To overcome this problem, this paper study the Real-time Data Collection with Laser-charging UAV (RDCL) problem, where the UAV is used to collect data from a given WSN and replenished energy by Laser Beam Directors (LBDs). The problem aims at optimizing the flight trajectory of UAV for ensuring the real-time performance of data, which is to design the detailed hovering and traveling plans of UAV for collecting data from sensors and charged by LBDs such that all sensory data of WSN are collected by UAV and transported to the base *** prove that the RDCL problem is NP-hard. To solve the problem, we first study two sub-problems, the Trajectory Optimization of UAV for Data Collection (TODC) problem and the Charging Trajectory Optimization of UAV (CTO) problem, whose objectives are to find the optimal flight plans of UAV in the data collection areas and charging areas, respectively. Then we propose an approximation algorithm to solve each of them with the constant factor. Afterwards, we propose an approximation algorithm to solve the RDCL problem based on TODC and CTO problems. Finally, the proposed algorithm is verified by extensive simulations. © 2023, The Authors. All rights reserved.

关键词： Wireless sensor networks

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Equation of state dependent dynamics and multimessenger signals from stellar-mass black hole formation

arXiv

引用

arXiv 2017年

作者： Pan, Kuo-Chuan Liebendörfer, Matthias Couch, Sean M. Thielemann, Friedrich-Karl Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Joint Institute for Nuclear Astrophysics Michigan State University East LansingMI48824 United States Departement Physik Universität Basel Klingelbergstrasse 82 BaselCH-4056 Switzerland Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States National Superconducting Cyclotron Laboratory Michigan State University East LansingMI48824 United States

We investigate axisymmetric black hole (BH) formation and its gravitational wave (GW) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 M☉ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects. We consider four different neutron star (NS) equations of state (EoS): LS220, SFHo, BHBΛφ and DD2, and study the impact of the EoS on BH formation dynamics and GW emission. We find that the BH formation time is sensitive to the EoS from 460 to > 1300 ms and is delayed in multiple dimensions for ∼ 100 − 250 ms due to the finite entropy effects. Depending on the EoS, our simulations show the possibility that shock revival can occur along with the collapse of the proto-neutron star (PNS) to a BH. The gravitational waveforms contain four major features that are similar to previous studies but show extreme values: (1) a low frequency signal (∼ 300 − 500 Hz) from core-bounce and prompt convection, (2) a strong signal from the PNS g-mode oscillation among other features, (3) a high frequency signal from the PNS inner-core convection, and (4) signals from the standing accretion shock instability and convection. The peak frequency at the onset of BH formation reaches to ∼ 2.3 kHz. The characteristic amplitude of a 10 kpc object at peak frequency is detectable but close to the noise threshold of the Advanced LIGO and KAGRA, suggesting that the next generation gravitational wave detector will need to improve the sensitivity at the kHz domain to better observe stellar-mass BH formation from core-collapse supernovae or failed supernovae. Copyright © 2017, The Authors. All rights reserved.

关键词： Gravity waves

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Ab initio calculated dynamic structure factors and optical properties of beryllium along the Hugoniot

arXiv

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arXiv 2023年

作者： Li, Wei-Jie Zhou, Jie Li, Zi Zhu, Yunliang Hu, Han-Dong Ma, Hao Ma, Zhe Wang, Cong Zhang, Ping Intelligent Science & Technology Academy Limited of CASIC Beijing100141 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Scientific Research Key Laboratory of Aerospace Defence Intelligent Systems and Technology Beijing100141 China School of Mechanical and Electric Engineering Sanming University Fujian Province Sanming365004 China Tianfu Innovation Energy Establishment Chengdu610213 China Center for Applied Physics and Technology Peking University Beijing100871 China Shanghai Jiao Tong University 200240 China

Beryllium is an ablator material in the inertial-confinement fusion and hypervelocity impact studies. The thermoelastic properties, structure factors, and optical properties of beryllium are important in these studies. In this paper, the static structure factors, ion-ion dynamic structure factors, adiabatic velocity, and optical properties of beryllium along the Hugoniot were calculated by ab initio simulations. The static structure factors show that beryllium atoms were randomly distributed. The dynamic structure factors via the scattering function have extracted the dispersion relation for the collective excitations. By collecting the peak position of dynamic structure factors, the dispersion relation and adiabatic sound velocity were derived by definitions. By the calculated equation of state, the thermoelastic properties and adiabatic sound velocity have been derived. The two calculated methods about adiabatic sound velocity were verified to be equivalent. © 2023, CC BY.

关键词： Optical properties

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On the development of multidimensional progenitor models for core-collapse supernovae

arXiv

引用

arXiv 2020年

作者： Fields, Carl E. Couch, Sean M. Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Center for Theoretical Astrophysics Los Alamos National Lab Los AlamosNM87545 United States Joint Institute for Nuclear Astrophysics - Center for the Evolution of the Elements United States Department of Computational Mathematics Science and Engineering Michigan State University East LansingMI48824 United States National Superconducting Cyclotron Laboratory Michigan State University East LansingMI48824 United States

Multidimensional hydrodynamic simulations of shell convection in massive stars suggest the development of aspherical perturbations that may be amplified during iron core-collapse. These perturbations have a crucial and qualitative impact on the delayed neutrino-driven core-collapse supernova explosion mechanism by increasing the total stress behind the stalled shock. In this paper, we investigate the properties of a 15 M* model evolved in 1-,2-, and 3-dimensions (3D) for the final ∼424 seconds before gravitational instability and iron core-collapse using MESA and the FLASH simulation framework. We find that just before collapse, our initially perturbed fully 3D model reaches angle-averaged convective velocity magnitudes of ≈ 240-260 km s−1 in the Si- and O-shell regions with a Mach number ≈ 0.06. We find the bulk of the power in the O-shell resides at large scales, characterized by spherical harmonic orders (`) of 2-4, while the Si-shell shows broad spectra on smaller scales of ` ≈ 30 − 40. Both convective regions show an increase in power at ` = 5 near collapse. We show that the 1D MESA model agrees with the convective velocity profile and speeds of the Si-shell when compared to our highest resolution 3D model. However, in the O-shell region, we find that MESA predicts speeds approximately four times slower than all of our 3D models suggest. All eight of the multi-dimensional stellar models considered in this work are publicly available. Copyright © 2020, The Authors. All rights reserved.

关键词： Hydrodynamics

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Artificial Intelligence for Climate Smart Forestry: A Forward Looking Vision

Artificial Intelligence for Climate Smart Forestry: A Forwar...

引用

IEEE International Conference on Cognitive Machine Intelligence (CogMI)

作者： Feng Luo Ling Liu G. Geoff Wang Vijay Kumar Mark S. Ashton Jacob Abernethy Fatemeh Afghah Matthew H. E. M Browning David Coyle Philip Dames Tom O'Halloran James Hays Patrick Heisl Chenfanfu Jiang Puskar Khanal Venkat Narayan Krovi Sara Kuebbing Nianyi Li JingJing Liang Ninghao Liu Steve McNulty Christopher M. Oswalt Neil Pederson Demetri Terzopoulos Christopher W. Woodall Yongkai Wu Jian Yang Yin Yang Liang Zhao School of Computing Clemson University Clemson SC USA College of Computing Georgia Institute of Technology Atlanta GA USA Department of Forestry and Environmental Conservation Clemson University Clemson SC USA School of Engineering and Applied Science University of Pennsylvania Philadelphia PA USA The Forest School Yale University New Haven CT USA Department of Electrical and Computer Engineering Clemson University Clemson SC USA Department of Parks Recreation and Tourism Management Clemson University Clemson SC USA Department of Mechanical Engineering Temple University Philadelphia PA USA Department of Mathematics University of California Los Angeles Los Angeles CA USA Department of Automotive Engineering Clemson University Clemson SC USA Department of Forestry and Natural Resources Purdue University West Lafayette IN USA School of Computing University of Georgia Athens GA USA Northern Research Station USDA Forestry Service Durham NH USA South Research Station USDA Forestry Service Knoxville TN USA The Harvard Forest Harvard University Petersham MA USA Computer Science Department University of California Los Angeles Los Angeles CA USA Department of Forestry and Natural Resources University of Kentucky Lexington KY USA School of Computing University of Utah Salt Lake City UT USA Department of Computer Science Emory University Atlanta GA USA

Forests and forest ecosystems are vital to our social, economic, and environmental well-being. However, climate change and climate-driven disturbances (CDDs) are undermining the health and resilience of forests worldwide and pose significant uncertainty to sustainable forest management. Climate-smart forestry (CSF) remains a grand challenge in practice due to our limited knowledge of how forests respond to climate change and our abilities to collect related information to empower decision making. Rapid advances in artificial intelligence (AI) can offer a timely opportunity to address the challenges in CSF. We argue that the AI-enabled, next-generation CSF can be achievable through synergistically coordinated and transdisciplinary efforts that develop and advance foundational and use-inspired AI technologies that can lead to building next-generation forest decision support systems.

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Exclusion Volumes of Convex Bodies in High Space Dimensions: Applications to Virial Coefficients and Continuum Percolation

arXiv

引用

arXiv 2022年

作者： Torquato, Salvatore Jiao, Yang Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Princeton Institute of Materials Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Materials Science and Engineering Arizona State University TempeAZ85287 United States Department of Physics Arizona State University TempeAZ85287 United States

Using the concepts of mixed volumes and quermassintegrals of convex geometry, we derive an exact formula for the exclusion volume vex(K) for a general convex body K that applies in any space dimension. While our main interests concern the rotationally-averaged exclusion volume of a convex body with respect to another convex body, we also describe some results for the exclusion volumes for convex bodies with the same orientation. We show that the sphere minimizes the dimensionless exclusion volume vex(K)/v(K) among all convex bodies, whether randomly oriented or uniformly oriented, for any d, where v(K) is the volume of K. When the bodies have the same orientation, the simplex maximizes the dimensionless exclusion volume for any d with a large-d asymptotic scaling behavior of 22d/d3/2, which is to be contrasted with the corresponding scaling of 2d for the sphere. We present explicit formulas for quermassintegrals W0(K), . . ., Wd(K) for many different nonspherical convex bodies, including cubes, parallelepipeds, regular simplices, cross-polytopes, cylinders, spherocylinders, ellipsoids as well as lower-dimensional bodies, such as hyperplates and line segments. These results are utilized to determine the rotationally-averaged exclusion volume vex(K) for these convex-body shapes for dimensions 2 through 12. While the sphere is the shape possessing the minimal dimensionless exclusion volume, we show that, among the convex bodies considered that are sufficiently compact, the simplex possesses the maximal vex(K)/v(K) with a scaling behavior of 21.6618...d. Subsequently, we apply these results to determine the corresponding second virial coefficient B2(K) of the aforementioned hard hyperparticles. Our results are also applied to compute estimates of the continuum percolation threshold ηc derived previously by the authors for systems of identical overlapping convex bodies. We conjecture that overlapping spheres possess the maximal value of ηc among all identical nonzero-vol

关键词： Spheres

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