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Strong Broadband Terahertz Optical Activity through Control of the Blaschke Phase with Chiral Metasurfaces

Physical Review Applied 2017年第1期8卷 014019-014019页

作者： Michael A. Cole Wen-chen Chen Mingkai Liu Sergey S. Kruk Willie J. Padilla Ilya V. Shadrivov David A. Powell Nonlinear Physics Centre and Centre for Ultrahigh Bandwidth Devices for Optical Systems Research School of Physics and Engineering The Australian National University Canberra Australian Capital Territory 2601 Australia Computer Simulation Technology (CST) San Mateo California 94404 USA Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA

We demonstrate terahertz chiral metamaterials that achieve resonant transmission and strong optical activity. This response is realized in a metasurface coupled to its Babinet complement, with additional twist. Uniquely, the optical activity achieved in this type of metamaterial is weakly dispersive around the resonant transmission maxima, but it can be highly dispersive around the transmission minima. It has recently been shown that this unique optical activity response is closely related to zeros in the transmission spectra of circular polarizations through the Kramers-Kronig relations and strong resonant features in the optical activity spectrum corresponding to the Blaschke phase terms. Here we demonstrate how modifying the meta-atom geometry greatly affects the location and magnitude of these Blaschke phase terms. We study three different meta-atoms, which are variations on the simple cross structure. Their responses are measured using terahertz time-domain spectroscopy and analyzed via numerical simulations.

关键词： Chirality Metamaterials Polarization of light Microwave techniques Optical techniques

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A hybrid machine learning model to study UV-Vis spectra of gold nano spheres

arXiv

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arXiv 2018年

作者： Yilmaz, M.F. Ozdemir, M. Danisman, Y. Karlik, B. Yavuz, C.T. Basic Sciences College of Engineering Imam Abdulrahman Bin Faisal university P.O. Box 1982 Dammam31451 Saudi Arabia Department of Mathematics and Computer Sciences Queensborough Community College CUNY BaysideNY United States Neurosurgical Simulation and Artificial Intelligence Learning Centre Montreal Neurological Institute McGill University H3A2B4 MontrealQC Canada Environmental Engineering College of Engineering Imam Abdulrahman Bin Faisal university P.O. Box 1982 Dammam31451 Saudi Arabia

Here, we have employed Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) to analyze a database consisting of Mie calculated UV-Vis spectra of gold nanospheres (GNS). PCA and LDA extract the hidden structures of the database by the corresponding vectors and coordinates. 3D representation of coordinates of PCA of spectral database results in a beam of surface plasmon polaritons (SPP) following a parabolic trajectory. The eigen spectra of PCA exhibit the Fano type resonances of SPP, and quantum confinement effects are observed by 3d representation of LDA coordinates obtained from the database. In addition, standing wave patterns resulting from oscillations of ions and electrons are illustrated through the eigen spectra of LDA. Such results confirm that GNPs have high potential for high energy density physics applications. Furthermore, the coordinates of PCA of spectral database are used for the training of Machine Learning (ML) algorithms for the estimation of the diameters of GNS. As a result, experimental spectra of diameters of GNS are tested, and the outputs of ML algorithms and Dynamic Light Scattering (DLS) measurements are compared for reliability of calculations. PCA based artificial neural network (ANN) were found to estimate the diameters with a high accuracy. Moreover, our results show that application of PCA and LDA on spectra could efficiently investigate the light-nanoparticles interactions for applications like rapid size determination. Copyright © 2018, The Authors. All rights reserved.

关键词： Principal component analysis

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High-performance flow visualization for effective data analysis

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Journal of Flow Visualization and Image Processing 2016年第1-2期23卷 41-57页

作者： Liu, Zhanping Moorhead, Robert J. Department of Modeling Simulation and Visualization Engineering Old Dominion University ODU-MSVE 1300 ECSB 4700 Elkhorn Avenue NorfolkVA23529 United States Department of Electrical and Computer Engineering Mississippi State University United States

As data grows at exponential rates toward exa-scale (1018) computing, it is necessary to exploit scientific visualization in the form of a visual, informative, and interactive methodology to help resolve daunting problems arising from a wide variety of disciplines that involve big data analysis. While novel visualization algorithms are investigated for effective as well as efficient exploration of surface and volume flows, there are signs of revisiting sparse geometry-based methods with further improvement, back from dense texture-based approaches, and resorting to parallel visualization. This paper presents our innovative research along this path in high-performance visualization of flow data for exploration, recognition, representation, and analysis of overall patt erns and salient features, with techniques from texture-based to geometry-based, flows from 2D to 3D, complexity from steady to unsteady, and computing from serial to parallel. Specifically, a high-level description is primarily focused on four algorithms, i.e., accelerated unsteady flow line integral convolution, its extension to time-varying volume flows, advanced evenly spaced streamline placement, and interactive view-driven evenly spaced streamline placement. Also introduced are four systems, i.e., ActiveLIC, ActiveIBFV, ActiveFLOVE, and DOXIV, which we developed for high-performance flow visualization coupled with applications to demonstrate the practical applicability. © 2016 by Begell House, Inc.

关键词： Data visualization

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Synthesizing and visualizing symmetric flows

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Journal of Flow Visualization and Image Processing 2016年第3-4期23卷 253-273页

There are frequent user studies in flow visualization for comparing different algorithms in the effectiveness. While much work is focused on statistical analysis of the collected results, considerable bias arising from both flow data and task design is seldom addressed, compromising and even invalidating the subsequent conclusion. This paper presents topology-based synthesis of symmetric flows for explicit data generation, which then facilitates implicit task design, so as to enable convincing user studies. This method can produce a large number of (x-/y-/center-)symmetric flows with different structures but with nearly the same degree of topological complexity, and geometrically symmetric yet topologically asymmetric flows. The wide variety of topological constitution requires local + global visual perception, comprehensive feature recognition, and discreet pattern classification to gain a proper understanding of such symmetric and asymmetric flows. To visualize these flows, we propose to use a set of representative techniques including sparse geometry-based methods (i.e., arrow plots and evenly spaced streamlines) and dense texture-based approaches (i.e., three variants of line integral convolution) coupled with two color map schemes (i.e., rainbow band and color wheel). This selection, out of a broad range of candidate techniques, is based on thorough investigation of the working mechanisms, in-depth analysis of perceptual factors, and extensive observation of the advances in flow visualization. Thus, the rationale helps identify strengths and weaknesses of the existing flow visualization methods and provides hints for designing new effective algorithms. © 2016 by Begell House, Inc.

关键词： Flow visualization

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Snakes and ghosts in a parity-Time-symmetric chain of dimers

arXiv

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arXiv 2018年

作者： Susanto, H. Kusdiantara, R. Li, N. Kirikchi, O.B. Adzkiya, D. Putri, E.R.M. Asfihani, T. Department of Mathematical Sciences University of Essex Wivenhoe Park ColchesterCO4 3SQ United Kingdom Centre of Mathematical Modelling and Simulation Institut Teknologi Bandung 1st Floor Bandung40132 India School of Computer Science and Electronic Engineering University of Essex Wivenhoe Park ColchesterCO4 3SQ United Kingdom Department of Mathematics Faculty of Mathematics and Natural Sciences Institut Teknologi Sepuluh Nopember Surabaya60111 India

We consider linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms and with a cubic-quintic nonlinearity. The system models a parity-Time (PT )-symmetric coupler composed by a chain of dimers. Particularly we study site-centered and bond-centered spatiallylocalized solutions and present that each solution has a symmetric and antisymmetric configuration between the arms. When a parameter is varied, the resulting bifurcation diagrams for the existence of standing localized solutions have a snaking behaviour. The critical gain/loss coefficient above which the PT symmetry is broken corresponds to the condition when bifurcation diagrams of symmetric and antisymmetric states merge. Past the symmetry breaking, the system no longer has timeindependent states. Nevertheless, equilibrium solutions can be analytically continued by defining a dual equation that leads to so-called ghost states associated with growth or decay, that are also identified and examined here. We show that ghost localized states also exhibit snaking bifurcation diagrams. We analyse the width of the snaking region and provide asymptotic approximations in the limit of strong and weak coupling where good agreement is obtained. Copyright © 2018, The Authors. All rights reserved.

关键词： Nonlinear equations

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Superstrengthening Bi2Te3 through Nanotwinning

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Physical Review Letters 2017年第8期119卷 085501-085501页

作者： Guodong Li Umut Aydemir Sergey I. Morozov Max Wood Qi An Pengcheng Zhai Qingjie Zhang William A. Goddard, III G. Jeffrey Snyder State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Chemistry Koc University Sariyer Istanbul 34450 Turkey Department of Computer Simulation and Nanotechnology South Ural State University Chelyabinsk 454080 Russia Department of Chemical and Materials Engineering University of Nevada Reno Reno Nevada 89557 USA Materials and Process Simulation Center California Institute of Technology Pasadena California 91125 USA

Bismuth telluride (Bi2Te3) based thermoelectric (TE) materials have been commercialized successfully as solid-state power generators, but their low mechanical strength suggests that these materials may not be reliable for long-term use in TE devices. Here we use density functional theory to show that the ideal shear strength of Bi2Te3 can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi2Te3 is the weak van der Waals interaction between the Te1 coupling two Te1─Bi─Te2─Bi─Te1 five-layer quint substructures. However, we demonstrate here a surprising result that forming twin boundaries between the Te1 atoms of adjacent quints greatly strengthens the interaction between them, leading to a tripling of the ideal shear strength in nanotwinned Bi2Te3 (0.6 GPa) compared to that in the single crystalline material (0.19 GPa). This grain boundary engineering strategy opens a new pathway for designing robust Bi2Te3 TE semiconductors for high-performance TE devices.

关键词： First-principles calculations Material failure Mechanical deformation Semiconductors Stress

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WHEN HOLLYWOOD INSPIRES MEDICINE: NEW CONCEPTS IN THE DESIGN AND ARCHITECTURE OF MEDICAL simulation FACILITIES TO SUPPORT INTER-PROFESSIONAL HEALTHCARE EDUCATION AND TRAINING

WHEN HOLLYWOOD INSPIRES MEDICINE: NEW CONCEPTS IN THE DESIGN...

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Modeling and simulation in Medicine Symposium

作者： Allan Hamilton Marissa Lovett David Biffar Jonathan Kanda Jerzy Rozenblit Ronald Weinstein Arizona Simulation Technology Education Center University of Arizona 1501 N. Campbell Avenue Tucson AZ USA Co Architects Inc. 5055 Wilshire Boulevard 9th Floor Los Angeles California Department of Electrical & Computer Engineering University of Arizona 1230 E. Speedway Blvd. Suite 506 Tucson AZ USA Arizona Telemedicine Program University of Arizona Health Sciences P.O. Box 235105 Tucson AZ USA

The changing landscape of healthcare education, delivery, and technology is placing new demands for significant inter-disciplinary and inter-professional training in medical simulation. New architectural concepts and building designs must ensure that large-scale healthcare simulation facilities offer customized training opportunities for nursing, medicine, public health, and pharmacy while allowing for maximal flexibility and adaptation across nearly fifty different user groups and stake holders. A novel concept of a larger, configurable "stage" design, more akin to a Hollywood production studio, with in-patient and outpatient suites seen as temporary or "standing" sets was created. The stage, called a "Sim Deck," can be easily dismantled while providing ample square footage for mass casualty scenarios. The facility required significant technological support to provide remote simulation training via existing and future telemedical technologies as well as remaining nimble enough to incorporate technologies in augmented and virtual reality, artificial intelligence, and large-scale learner management systems.

关键词： Architecture Healthcare Informational technologies Inter-professional Medical simulation

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Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

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Physical Review Letters 2017年第21期119卷 215503-215503页

作者： Guodong Li Sergey I. Morozov Qingjie Zhang Qi An Pengcheng Zhai G. Jeffrey Snyder State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Computer Simulation and Nanotechnology South Ural State University Chelyabinsk 454080 Russia Department of Chemical and Materials Engineering University of Nevada Reno Reno Nevada 89557 USA

The conversion efficiency (zT) of thermoelectric (TE) materials has been enhanced over the last two decades, but their engineering applications are hindered by the poor mechanical properties, especially the low strength at working conditions. Here we used density functional theory (DFT) to show a strength enhancement in the TE semiconductor InSb arising from the twin boundaries (TBs). This strengthening effect leads to an 11% enhancement of the ideal shear strength in flawless crystalline InSb where this theoretical strength is considered as an upper bound on the attainable strength for a realistic material. DFT calculations reveal that the directional covalent bond rearrangements at the TB accommodating the structural mismatch lead to the anisotropic resistance against the deformation combined with the enhanced TB rigidity. This produces a strong stress response in the nanotwinned InSb. This work provides a fundamental insight for understanding the deformation mechanism of nanotwinned TE semiconductors, which is beneficial for developing reliable TE devices.

关键词： Material failure Mechanical deformation Semiconductors Stress Density functional theory

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An environment for sustainable research software in Germany and beyond: Current state, open challenges, and call for action

arXiv

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arXiv 2020年

作者： Anzt, Hartwig Bach, Felix Druskat, Stephan Löffler, Frank Loewe, Axel Renard, Bernhard Y. Seemann, Gunnar Struck, Alexander Achhammer, Elke Aggarwal, Piush Appel, Franziska Bader, Michael Brusch, Lutz Busse, Christian Chourdakis, Gerasimos Dabrowski, Piotr W. Ebert, Peter Flemisch, Bernd Friedl, Sven Fritzsch, Bernadette Funk, Maximilian D. Gast, Volker Goth, Florian Grad, Jean-Noël Hermann, Sibylle Hohmann, Florian Janosch, Stephan Kutra, Dominik Linxweiler, Jan Muth, Thilo Peters-Kottig, Wolfgang Rack, Fabian Raters, Fabian H.C. Rave, Stephan Reina, Guido Reißig, Malte Ropinski, Timo Schaarschmidt, Joerg Seibold, Heidi Thiele, Jan P. Uekerman, Benjamin Unger, Stefan Weeber, Rudolf Germany Innovative Computing Lab University of Tennessee KnoxvilleTN United States Department of English Studies Friedrich Schiller University Jena Germany Germany Department of Computer Science Humboldt-Universität zu Berlin Germany Heinz Nixdorf Chair for Distributed Information Systems Friedrich Schiller University Jena Germany Michael Stifel Center Jena Germany Center for Computation and Technology Louisiana State University Baton Rouge United States Germany Robert Koch Institute Berlin Germany Hasso Plattner Institute Faculty of Digital Engineering University of Potsdam Germany Institute for Experimental Cardiovascular Medicine University Heart Centre Freiburg Bad Krozingen Germany Faculty of Medicine University of Freiburg Freiburg Germany Matters of Activity. Image Space Material. Cluster of Excellence at Humboldt-Universität zu Berlin Germany Technische Universität München Germany Language Technology Lab Universität Duisburg-Essen Germany Germany Department of Informatics Technical University of Munich Germany Technische Universität Dresden Germany Deutsches Krebsforschungszentrum Heidelberg Germany Scientific Computing in Computer Science Technical University Munich Germany School of Computing Communication and Business Hochschule für Technik und Wirtschaft Berlin Germany Center for Bioinformatics Saar Saarland Informatics Campus Germany Institute for Modelling Hydraulic and Environmental Systems University of Stuttgart Germany Berlin Institute of Health Germany Scientific Computing Alfred Wegener Institute Helmholtz Center for Polar and Marine Research Bremerhaven Germany Max-Planck-Gesellschaft e.V. Institut für Theoretische Physik und Astrophysik Universität Würzburg Germany Institut für Computerphysik University of Stuttgart Germany University Library University of Stuttgart Germany Universität Bremen Germany Max Planck Institute of Molecular Cell Biology and Genetics Dresden Germany European Molecular Biology Laboratory Heidelb

Research software has become a central asset in academic research. It optimizes existing and enables new research methods, implements and embeds research knowledge, and constitutes an essential research product in itself. Research software must be sustainable in order to understand, replicate, reproduce, and build upon existing research or conduct new research effectively. In other words, software must be available, discoverable, usable, and adaptable to new needs, both now and in the future. Research software therefore requires an environment that supports sustainability. Hence, a change is needed in the way research software development and maintenance are currently motivated, incentivized, funded, structurally and infrastructurally supported, and legally treated. Failing to do so will threaten the quality and validity of research. In this paper, we identify challenges for research software sustainability in Germany and beyond, in terms of motivation, selection, research software engineering personnel, funding, infrastructure, and legal aspects. Besides researchers, we specifically address political and academic decision-makers to increase awareness of the importance and needs of sustainable research software practices. In particular, we recommend strategies and measures to create an environment for sustainable research software, with the ultimate goal to ensure that software-driven research is valid, reproducible and sustainable, and that software is recognized as a first class citizen in research. This paper is the outcome of two workshops run in Germany in 2019, at deRSE19 - the first International Conference of Research Software Engineers in Germany - and a dedicated DFG-supported follow-up workshop in Berlin. Copyright © 2020, The Authors. All rights reserved.

关键词： Software design

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Fault diagnosis for multi-energy flows of energy internet: Framework and prospects

Fault diagnosis for multi-energy flows of energy internet: F...

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2017 IEEE Conference on Energy Internet and Energy System Integration, EI2 2017

作者： Wang, Tao Wang, Jun Fan, Zhennan Wei, Xiaoguang Zang, Tianlei Pérez-Jiménez, Mario J. Huang, Tao School of Electrical Engineering and Electronic Information Sichuan Province Key Laboratory of Power Electronics Energy-saving Technologies and Equipment Key Laboratory of Fluid and Power Machinery Ministry of Education Xihua University Chengdu China School of Electrical Engineering Southwest Jiaotong University Chengdu China State Key Laboratory of Security Control and Simulation of Power Systems and Large Scale Generation Department of Electrical Engineering Tsinghua University Beijing China Research Groupon Natural Computing Department of Computer Science and Artificial Intelligence University of Sevilla Sevilla Spain Department of Energy Politecnico di Torino Torino Italy

ISBN: (纸本)9781538614273

Energy Internet (EI) is an inevitable development trend of energy systems under the background of technology development, environmental pressure and energy transition. Multi-energy flow coupling is one of the key characteristics of the EI, which enhances the interoperability of different types of energy flows while consequently increases the probability of cascading failures. Therefore it is of great significance to study the multi-energy flow fault diagnosis of the EI to ensure its safe and stable operation as well as the continuous energy supply. This paper introduces the concept of multi-energy flow cascading fault of the EI for the first time. The energy internet framework for multi-energy flow cascading fault diagnosis is firstly proposed, and then characteristics of various energy networks in the EI are analyzed from the perspective of fault diagnosis. Finally, future research prospects are discussed. © 2017 IEEE.

关键词： Failure analysis

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