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Domain morphology and mechanics of the H/T′ transition metal dichalcogenide monolayers

Physical Review Materials 2018年第11期2卷 114002-114002页

作者： Joel Berry Songsong Zhou Jian Han David J. Srolovitz Mikko P. Haataja Department of Materials Science and Engineering University of Pennsylvania Philadelphia Pennsylvania 19104 USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania Philadelphia Pennsylvania 19104 USA Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR People's Republic of China Princeton Institute for the Science and Technology of Materials (PRISM) Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics (PACM) Princeton University Princeton New Jersey 08544 USA

The properties of two-dimensional (2D) transition metal dichalcogenide (TMD) monolayers can be dynamically controlled via strain-induced displacive structural transformations between semiconducting (H) and metallic or semimetallic (T′) crystal structures. The shapes, symmetries, and kinetics of crystalline domains generated during these transformations and the mechanical response of transforming monolayers are of fundamental and applied interest in, e.g., phase change memory devices and the study of topologically protected edge states in quantum spin Hall insulating T′ crystals. We quantitatively characterize T′ domain morphologies during H→T′ transformations in both flat and bendable TMD monolayers using a combination of first principles and continuum calculations. Wulff constructions for MoTe2 and MoS2 show that T′ domains within much larger T′ domains are either rhombi of fixed proportions (if nonmisfitting) or rectangles whose aspect ratio AR increases with domain size L0 (if misfitting). Isolated T′ domains within much larger H domains undergo a morphological crossover from compact to elongated shapes at L0≈100–200 nm if the sheet is constrained to be flat or L0≳2μm if the sheet is free to bend. This crossover is driven by a competition between anisotropic interfacial energy and elastic misfit energy, and its position can be tuned via the monolayer-substrate interaction strength. It is shown that the aspect ratio AR obeys a scaling law AR∼L02/3. Stress-strain response characterized as a function of strain orientation reveals extreme anisotropy in the effective elastic modulus through H/T′ coexistence. Ferroelastic multidomain T′−WTe2 monolayers are found to exhibit two to three regimes of reversible mechanical response, and localized buckling in freely suspended T′ monolayers is shown to qualitatively alter T′ domain symmetries.

关键词： Bending Domain walls Mechanical deformation Microstructure Structural phase transition 2-dimensional systems Transition metal dichalcogenides Density functional theory Phase-field modeling

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Quantifying Gerrymandering in North Carolina

arXiv

引用

arXiv 2018年

作者： Herschlag, Gregory Kang, Han Sung Luo, Justin Graves, Christy Vaughn Bangia, Sachet Ravier, Robert Mattingly, Jonathan C. Department of Mathematics Duke University DurhamNC27708 United States Department of Biomedical Engineering Duke University DurhamNC27708 United States Department of Computer Science Duke University DurhamNC27708 United States Department of Electrical and Computer Engineering Duke University DurhamNC27708 United States Department of Economics Duke University DurhamNC27708 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Department of Statistical Science Duke University DurhamNC27708 United States

Using an ensemble of redistricting plans, we evaluate whether a given political districting faithfully represents the geo-political landscape. Redistricting plans are sampled by a Monte Carlo algorithm from a probability distribution that adheres to realistic and non-partisan criteria. Using the sampled redistricting plans and historical voting data, we produce an ensemble of elections that reveal geo-political structure within the state. We showcase our methods on the two most recent districtings of NC for the U.S. House of Representatives, as well as a plan drawn by a bipartisan redistricting panel. We find the two state enacted plans are highly atypical outliers whereas the bipartisan plan accurately represents the ensemble both in partisan outcome and in the fine scale structure of district-level results. Copyright © 2018, The Authors. All rights reserved.

关键词： Probability distributions

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Gait transitions in a phase oscillator model of an insect central pattern generator

arXiv

引用

arXiv 2017年

作者： Aminzare, Zahra Srivastava, Vaibhav Holmes, Philip Program in Applied and Computational Mathematics Department of Mechanical and Aerospace Engineering Princeton University NJ United States Department of Electrical and Computer Engineering Michigan State University LansingMI United States Program in Applied and Computational Mathematics Department of Mechanical and Aerospace Engineering Princeton Neuroscience Institute Princeton University NJ United States

Legged locomotion involves various gaits. It has been observed that fast running insects (cockroaches) employ a tripod gait with three legs lifted off the ground simultaneously in swing, while slow walking insects (stick insects) use a tetrapod gait with two legs lifted off the ground simultaneously. Fruit flies use both gaits and exhibit a transition from tetrapod to tripod at intermediate speeds. Here we study the effect of stepping frequency on gait transition in an ion-channel bursting neuron model in which each cell represents a hemi-segmental thoracic circuit of the central pattern generator. Employing phase reduction, we collapse the network of bursting neurons represented by 24 ordinary differential equations to 6 coupled nonlinear phase oscillators, each corresponding to a sub-network of neurons controlling one leg. Assuming that the left and right legs maintain constant phase differences (contralateral symmetry), we reduce from 6 equations to 3, allowing analysis of a dynamical system with 2 phase differences defined on a torus. We show that bifurcations occur from multiple stable tetrapod gaits to a unique stable tripod gait as speed increases. Finally, we consider gait transitions in two sets of data fitted to freely walking fruit flies.34C16, 34C60, 37G10, 92B20, 92C2034C16, 34C60, 37G10, 92B20, 92C20 Copyright © 2017, The Authors. All rights reserved.

关键词： Bifurcation (mathematics)

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Optical and physical properties of MnO 2 doped soda-lime- barium-silicate glasses with industrial scales

引用

Materials Today: Proceedings 2018年第7期5卷 15040-15043页

作者： Rahmat Hidayat Narong Sangwaranatee Jakrapong Kaewkhao Nattapon Srisittipokakun Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung 40132 Indonesia Applied Physics Faculty of Science and Technology Suan Sunandha Rajabhat University Bangkok 10300 Thailand Center of Excellence in Glass Technology and Materials Science (CEGM) Faculty of Science and Technology Nakhon Pathom Rajabhat University Nakhon Pathom 73000 Thailand Physics Program Faculty of Science and Technology Nakhon Pathom Rajabhat University Nakhon Pathom 73000 Thailand

The aim of the present work is to study the optical and physical properties of MnO 2 doped soda-lime- Barium-silicate glasses with industrial scales. The density and refractive index of all glass samples which the same values are between 3.0250-3.0272 g/cm 3 and 1.5680-1.5688, respectively. From the results are indicate that every parts of glass samples are homogenous. The absorption peaks occurred at a wavelength of around 420 nm are assigned to the transitions of 6 A 1 (S) → 4 A 1 of Mn 2+ .

关键词： Optical properties Physical properties MnO 2 Industrial scales Soda lime silicate glasses

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THE ARCTIC

引用

Bulletin of the American Meteorological Society 2024年第8期105卷 S277-S330页

作者： Druckenmiller, M.L. Thoman, R.L. Moon, T.A. National Snow and Ice Data Center Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Boulder Colorado International Arctic Research Center University of Alaska Fairbanks Fairbanks Alaska National Snow and Ice Data Center Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Colorado Section for Glaciers Ice and Snow Norwegian Water Resources and Energy Directorate Oslo Norway School of Informatics Computing and Cyber Systems Northern Arizona University Flagstaff Arizona Biospherical Instruments Inc. San Diego California Geophysical Institute University of Alaska Fairbanks Fairbanks Alaska Plant Soils and Climate Department Utah State University Logan Utah Norwegian Institute for Nature Research Trondheim Norway FRAM – High North Research Centre for Climate and the Environment Tromsø Norway Geological Survey of Denmark and Greenland (GEUS) Copenhagen Denmark NOAA/NWS Alaska Region Anchorage Alaska Alaska Native Tribal Health Consortium Anchorage Alaska Geological Survey of Canada Natural Resources Canada Ottawa Canada NOAA Chemical Sciences Laboratory Boulder Colorado Arctic Geophysics Department University Centre in Svalbard Longyearbyen Norway Geology Department University Centre in Svalbard Longyearben Norway Centre National de Recherches Météorologiques Météo-France/CNRS Toulouse France Climate Research Division Environment and Climate Change Canada Toronto Canada Norwegian Polar Institute Fram Centre Tromsø Norway Danish Meteorological Institute Copenhagen Denmark Department of Physics University of Toronto Toronto Canada Department of Environmental Sciences University of Virginia Charlottesville Virginia Department of Geographical Sciences University of Maryland College Park Maryland University of Liège Liège Belgium Environment and Climate Change Canada Toronto Canada Northern Rocky Mountain Science Center U.S. Geological Survey Bozeman Montana Arctic C

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The SRG/eROSITA All-Sky Survey: Dark Energy Survey Year 3 Weak Gravitational Lensing by eRASS1 selected Galaxy Clusters

arXiv

引用

arXiv 2024年

作者： Grandis, S. Ghirardini, V. Bocquet, S. Garrel, C. Mohr, J.J. Liu, A. Kluge, M. Kimmig, L. Reiprich, T.H. Alarcon, A. Amon, A. Artis, E. Bahar, Y.E. Balzer, F. Bechtol, K. Becker, M.R. Bernstein, G. Bulbul, E. Campos, A. Carnero Rosell, A. Carrasco Kind, M. Cawthon, R. Chang, C. Chen, R. Chiu, I. Choi, A. Clerc, N. Comparat, J. Cordero, J. Davis, C. Derose, J. Diehl, H.T. Dodelson, S. Doux, C. Drlica-Wagner, A. Eckert, K. Elvin-Poole, J. Everett, S. Ferte, A. Gatti, M. Giannini, G. Giles, P. Gruen, D. Gruendl, R.A. Harrison, I. Hartley, W.G. Herner, K. Huff, E.M. Kleinebreil, F. Kuropatkin, N. Leget, P.F. Maccrann, N. McCullough, J. Merloni, A. Myles, J. Nandra, K. Navarro-Alsina, A. Okabe, N. Pacaud, F. Pandey, S. Prat, J. Predehl, P. Ramos, M. Raveri, M. Rollins, R.P. Roodman, A. Ross, A.J. Rykoff, E.S. Sanchez, C. Sanders, J. Schrabback, T. Secco, L.F. Seppi, R. Sevilla-Noarbe, I. Sheldon, E. Shin, T. Troxel, M. Tutusaus, I. Varga, T.N. Wu, H. Yanny, B. Yin, B. Zhang, X. Zhang, Y. Alves, O. Bhargava, S. Brooks, D. Burke, D.L. Carretero, J. Costanzi, M. da Costa, L.N. Pereira, M.E.S. De Vicente, J. Desai, S. Doel, P. Ferrero, I. Flaugher, B. Friedel, D. Frieman, J. García-Bellido, J. Gutierrez, G. Hinton, S.R. Hollowood, D.L. Honscheid, K. James, D.J. Jeffrey, N. Lahav, O. Lee, S. Marshall, J.L. Menanteau, F. Ogando, R.L.C. Pieres, A. Plazas Malagón, A.A. Romer, A.K. Sanchez, E. Schubnell, M. Smith, M. Suchyta, E. Swanson, M.E.C. Tarle, G. Weaverdyck, N. Weller, J. Universität Innsbruck Institut für Astro- und Teilchenphysik Technikerstr. 25/8 Innsbruck6020 Austria Max Planck Institute for Extraterrestrial Physics Giessenbachstrasse 1 Garching85748 Germany Faculty of Physics Ludwig-Maximilians-Universität München Scheinerstr. 1 Munich81679 Germany Universität Bonn Auf dem Hügel 71 Bonn53121 Germany Kavli Institute for Cosmology University of Cambridge Mading- ley Road CambridgeCB3 0HA United Kingdom Institute of Astronomy University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom Physics Department University of Wisconsin-Madison MadisonWI53706 United States Argonne National Laboratory 9700 South Cass Avenue LemontIL60439 United States Department of Physics and Astronomy University of Pennsylvania PhiladelphiaPA19104 United States Department of Physics Carnegie Mellon University PittsburghPA15312 United States Instituto de Astrofisica de Canarias Tenerife La LagunaE-38205 Spain Laboratório Interinstitucional de e-Astronomia - LIneA Rua Gal. José Cristino 77 RJ Rio de Janeiro20921-400 Brazil Universidad de La Laguna Dpto. Astrofísica Tenerife La LagunaE-38206 Spain Center for Astrophysical Surveys National Center for Supercom- puting Applications 1205 West Clark St. UrbanaIL61801 United States Department of Astronomy University of Illinois at Urbana-Champaign 1002 W. Green Street UrbanaIL61801 United States Physics Department William Jewell College LibertyMO64068 United States Department of Astronomy and Astrophysics University of Chicago ChicagoIL60637 United States Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Department of Physics Duke University DurhamNC27708 United States Department of Physics National Cheng Kung University Tainan70101 Taiwan NASA Goddard Space Flight Center 8800 Greenbelt Rd Green- belt MD20771 United States IRAP Université de Toulouse CNRS UPS CNES Toulouse France Jodrell Bank Center f

Context. Number counts of galaxy clusters across redshift are a powerful cosmological probe, if a precise and accurate reconstruction of the underlying mass distribution is performed - a challenge called mass calibration. With the advent of wide and deep photometric surveys, weak gravitational lensing by clusters has become the method of choice to perform this measurement. Aims. We measure and validate the weak gravitational lensing (WL) signature in the shape of galaxies observed in the first 3 years of the Dark Energy Survey (DES Y3) caused by galaxy clusters and groups selected in the first all-sky survey performed by SRG (Spectrum Roentgen Gamma)/eROSITA (eRASS1). These data are then used to determine the scaling between X-ray photon count rate of the clusters and their halo mass and redshift. Methods. We empirically determine the degree of cluster member contamination in our background source sample. The individual cluster shear profiles are then analysed with a Bayesian population model that self-consistently accounts for the lens sample selection and contamination, and includes marginalization over a host of instrumental and astrophysical systematics. To quantify the accuracy of the mass extraction of that model, we perform mass measurements on mock cluster catalogs with realistic synthetic shear profiles. This allows us to establish that hydro-dynamical modelling uncertainties at low lens redshifts (z © 2024, CC BY.

关键词： Calibration

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Comparative Study of Methods to Estimate Historical Peat Burnt Area in Gaung – Batang Tuaka River of Peat Hydrological Unit (KHG)

引用

IOP Conference Series: Earth and Environmental Science 2019年第1期363卷

作者： A Rossita R Boer L Hein DR Nurrochmat Applied Climatology Study Program Faculty of Mathematics and Natural Science Graduate School of Bogor Agricultural University (IPB) IPB Dramaga Campus Bogor West Java Indonesia 16680 Environmental System Analysis Group Wageningen University and Research Netherlands Forest Management Study Program Faculty of Forestry Graduate School of Bogor Agricultural University (IPB) IPB Dramaga Campus Bogor West Java Indonesia 16680

As a country with 14.9 ha of peatland, Indonesia is a major contributor of GHG emissions, especially from peat ecosystems. These emissions were caused by peat decomposition and peat fires. However, accurate estimation of peat burnt area was still a barrier that prevented the inclusion of peat fire emission in the document of Forest Reference Emission Level (FREL) as a followup document to REDD+ activities. This research has the objective to analyse two different approaches to estimate peat burnt area used in the FREL document and the most recent semi-automatic approach suggested by the Ministry of Environment and Forestry (MoEF). The study focused on the Gaung – Batang Tuaka River Peat Hydrological Unit (KHG), as one of the KHG priorities in Indonesia. The results showed that the average total annual burnt area from the FREL approach was 58% higher than that of the semi-automatic approach, which could lead to an overestimate of peat fire emissions from this approach. The burnt area identified in this study was found to occur within the production forest area. As stepwise approach is allowed for FREL submission, improvements to a higher precision method are necessary to increase the accuracy of burnt area estimation.

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A spectral-infinite-element solution of Poisson’s equation: An application to self gravity

arXiv

引用

arXiv 2017年

作者： Gharti, Hom Nath Tromp, Jeroen Department of Geosciences Princeton University PrincetonNJ08544 United States Program in Applied & Computational Mathematics Princeton University PrincetonNJ United States

We solve Poisson’s equation by combining a spectral-element method with a mapped infinite-element method. We focus on problems in geostatics and geodynamics, where Earth’s gravitational field is determined by Poisson’s equation inside the Earth and Laplace’s equation in the rest of space. Spectral elements are used to capture the internal field, and infinite elements are used to represent the external field. To solve the weak form of Poisson/Laplace equation, we use Gauss-Legendre-Lobatto quadrature in spectral elements inside the domain of interest. Outside the domain, we use Gauss-Radau quadrature in the infinite direction, and Gauss-Legendre-Lobatto quadrature in the other directions. We illustrate the efficiency and accuracy of the method by comparing the gravitational fields of a homogeneous sphere and the Preliminary Reference Earth Model (PREM) with (semi-)analytical solutions. Copyright © 2017, The Authors. All rights reserved.

关键词： Earth (planet)

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On signal reconstruction from frog measurements

arXiv

引用

arXiv 2017年

作者： Bendory, Tamir Edidin, Dan Eldar, Yonina C. Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Department of Mathematics University of Missouri ColumbiaMO United States The Andrew and Erna Viterbi Faculty of Electrical Engineering Technion – Israel Institute of Technology Haifa Israel

Phase retrieval refers to recovering a signal from its Fourier magnitude. This problem arises naturally in many scientific applications, such as ultra-short laser pulse characterization and diffraction imaging. Unfortunately, phase retrieval is ill-posed for almost all one-dimensional signals. In order to characterize a laser pulse and overcome the ill-posedness, it is common to use a technique called Frequency-Resolved Optical Gating (FROG). In FROG, the measured data, referred to as FROG trace, is the Fourier magnitude of the product of the underlying signal with several translated versions of itself. The FROG trace results in a system of phaseless quartic Fourier measurements. In this paper, we prove that it suffices to consider only three translations of the signal to determine almost all bandlimited signals, up to trivial ambiguities. In practice, one usually also has access to the signal’s Fourier magnitude. We show that in this case only two translations suffice. Our results significantly improve upon earlier work. Copyright © 2017, The Authors. All rights reserved.

关键词： Signal reconstruction

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Phase unwinding, or invariant subspace decompositions of hardy spaces

arXiv

引用

arXiv 2017年

作者： Coifman, Ronald R. Peyrie, Jacques Department of Mathematics Program in Applied Mathematics Yale University New HavenCT06510 United States Laboratoire de Mathématiques d'Orsay Univ. Paris-Sud CNRS Université Paris-Saclay Orsay91405 France

We consider orthogonal decompositions of invariant subspaces of Hardy spaces, these relate to the Blaschke based phase unwinding decompositions [1, 2, 7]. We prove convergence in Lp. In particular we build an explicit multiscale wavelet basis. We also obtain an explicit unwindinig decomposition for the singular inner function, exp 2iπ/*** Codes 30B50, 30A10, 42C40, 65T99 Copyright © 2017, The Authors. All rights reserved.

关键词： Functions

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