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arXiv 2017年

作者： Santra, Biswajit Shneider, Mikhail N. Car, Roberto Department of Chemistry Princeton University PrincetonNJ08544 United States Mechanical and Aerospace Engineering Department 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

We report a theoretical analysis showing that Rayleigh scattering could be used to monitor the growth of nanoparticles under arc discharge conditions. We compute the Rayleigh scattering cross sections of the nanoparticles by combining light scattering theory for gas-particle mixtures with calculations of the dynamic electronic polarizability of the nanoparticles. We find that the resolution of the Rayleigh scattering probe is adequate to detect nanoparticles as small as C60 at the expected concentrations of synthesis conditions in the arc periphery. Larger asymmetric nanoparticles would yield brighter signals, making possible to follow the evolution of the growing nanoparticle population from the evolution of the scattered intensity. Observable spectral features include characteristic resonant behaviour, shape-dependent depolarization ratio, and mass-dependent line shape. Direct observation of nanoparticles in the early stages of growth with unobtrusive laser probes should give insight on the particle formation mechanisms and may lead to better-controlled synthesis protocols. Copyright © 2017, The Authors. All rights reserved.

关键词： Rayleigh scattering

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Enterobacteria and Vibrio from Macrobrachium amazonicum prawn farming in Fortaleza,Ceará,Brazil

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Asian Pacific Journal of Tropical Medicine 2016年第1期9卷 24-28页

作者： Débora de Souza Collares Maia Castelo-Branco Jamille Alencar Sales Raimunda Samia Nogueira Brilhante Glaucia Morgana de Melo Guedes Yago Brito de Ponte Celia Maria de Souza Sampaio Tereza de Jesus Pinheiro Gomes Bandeira José Luciano Bezerra Moreira Lucas Pereira de Alencar Manoel de Araújo Neto Paiva Rossana de Aguiar Cordeiro André Jalles Monteiro Waldemiro de Aquino Pereira-Neto José Júlio Costa Sidrim Marcos Fábio Gadelha Rocha Department of Pathology and Legal Medicine Postgraduate Program in Medical MicrobiologySpecialized Medical Mycology CenterFederal University of Ceará School of Veterinary Medicine Postgraduate Program in Veterinary SciencesState University of Ceará Department of Statistics and Applied Mathematics Federal University of Ceará

Objective:To investigate the isolation of enterobacteria associated with Macrobrachium amazonicum(***) farming and evaluate the in vitro antimicrobial susceptibility of Vibrio ***:Strains were isolated from female *** prawns and environmental and hatchery *** assays were used to identify bacterial genera and those belonging to the genus Vibrio were submitted to further analyses for species identification,through Vitek 2 automated system and *** test was performed according to Clinical Laboratory Standards ***:The following genera of enlerobacteria were recovered:Enterobacter(n=11),Citrobacter(n=10),Proteus(n=2),Serratia(n=2),Kluyvera(n=2),Providencia(n=2),Cedecea(n=1),Escherichia(n=1).Edwardsiella(n=1) and BulliauxeUa(n=1).As for Vibrio,three species were identified:Vibrio cholerae non-O1/non-O139(n=4).Vibrio vulnificus(***)(n=1) and Vibrio mimicus(n=1).Vibrio *** minimum inhibitory concentrations values within the susceptibility range established by Clinical Laboratory Standards Institute for almost all antibiotics,except for ***,which presented intermediate profile to ***:Enterobacteria do not seem to be the most important pathogens associated with *** farming,whereas the recovery of Vibrio *** larviculture,with emphasis on Vibrio cholerae and ***,deserves special attention due to their role as potentially zoonotic aquaculture-associated ***,the intermediate susceptibility of *** to ampicillin reflects the importance of monitoring drug use in prawn farming.

关键词： Prawn Water Enterobacteria Vibrio Antibiotics

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A FEniCS-HPC framework for multi-compartment Bloch-Torrey models 7

A FEniCS-HPC framework for multi-compartment Bloch-Torrey mo...

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7th European Congress on computational Methods in applied Sciences and Engineering, ECCOMAS Congress 2016

作者： Nguyen, D.V. Jansson, J. Hoffman, J. Computational Technology Laboratory Department of Computational Science and Technology School of Computer Science and Communication KTH Royal Institute of Technology Sweden BCAM - Basque Center for Applied Mathematics Bilbao Basque Country Spain

ISBN: (纸本)9786188284401

In diffusion nuclear magnetic resonance (NMR) and diffusion magnetic resonance imaging (MRI), the multi-compartment Bloch-Torrey equation plays an important role in probing the diffusion characteristics from a nanometer scale to a macroscopic scale. The signal attenuation can be computed by solving the equation. If the volume of interest is composed by multiple compartments, interface conditions with permeability are imposed. Depending on applications, different gradient strengths can be used to capture the signal attenuation. In probing porous media, for instance, high gradient strengths are used. In diffusion MRI, since water molecules enter and exit the computational domain in realistic cases, pseudo-periodic boundary conditions are used. These conditions cause difficulties in solving the equation efficiently and many efforts have been made to develop an efficient numerical method. However, large-scale problems for supercomputers with realistic applications have not been considered yet. We propose a framework for the multi-compartment Bloch-Torrey models based on the FEniCS-HPC platform, a part of the FEniCS project that allows for automated discretization, automated error control with mesh adaptivity and high performance computing. The framework runs on supercomputers with near optimal weak and strong scaling. Our work includes two parts. First, we simplify the multi-compartment Bloch-Torrey model used in diffusion MRI by proposing an approximation to the pseudo-periodic boundary conditions to derive a general form for the interface and boundary conditions. The second part includes implementation and numerical validation of our method on the FEniCS-HPC platform. This simplified model is straightforward to implement and to parallelize and shows promise in validation against more realistic models.

关键词： Diffusion

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Peripheral fishes in the Estuary of Simeulue Island, Indonesia

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IOP Conference Series: Earth and Environmental Science 2018年第1期216卷

作者： A S Batubara M Abdan Z Muhammad N F Putra Z A Muchlisin Department of Aquaculture Faculty of Marine and Fisheries Syiah Kuala University Banda Aceh 23111 Indonesia. Doctorate Program of Mathematics and Applied Sciences Syiah Kuala University Banda Aceh 23111 Indonesia

The objective of the present study was to inventory of peripheral water fishes were conducted in several estuaries of Simeulue Island, Aceh Province, Indonesia. The sampling was done at seven river mouths in August 2017 and May 2018. The fish samples were collected using fishhooks, casting net and gill net. The sampled fishes were taxonomic identified based on several references at the Laboratory of Ichthyology, Faculty of Marine and Fisheries, Syiah Kuala University. The results showed that there were 356 individual of fishes were recorded during the survey, its belong to 10 orders, 25 families, 41 genera and 52 species. The Perciformes was a predominant with a total of 15 families, 27 genera and 35 species. Furthermore, Gobiidae was predominant with the highest number of genera and species (7 genera and 10 species), followed by Eleotridae (4 genera and 4 species), Mugilidae (3 genera and 4 species), and Carangidae (3 genera and 4 species).

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Preface of the symposium: “V-International Symposium of computational and Mathematical Modeling of Biologic and Medicine Targets”

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AIP Conference Proceedings 2018年第1期2040卷

作者： Dilson Silva Celia M. Cortez 1Applied Mathematics Department Post-graduation Program in Computational Sciences and Post-graduation Program in Medical Sciences University of the State of Rio de Janeiro. Rua São Francisco Xavier 524 sala 6020 D 20550-900 - Rio de Janeiro / Brazil. Phone +55(21)34960298 Fax +55(21)34960298

Dilson Silva, Celia M. Cortez; Preface of the symposium: “V-International Symposium of computational and Mathematical Modeling of Biologic and Medicine Targets”

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Characterization of maximally random jammed sphere packings. II. Correlation functions and density fluctuations

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Physical Review E 2016年第2期94卷 022152-022152页

作者： Michael A. Klatt Salvatore Torquato Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

In the first paper of this series, we introduced Voronoi correlation functions to characterize the structure of maximally random jammed (MRJ) sphere packings across length scales. In the present paper, we determine a variety of different correlation functions that arise in rigorous expressions for the effective physical properties of MRJ sphere packings and compare them to the corresponding statistical descriptors for overlapping spheres and equilibrium hard-sphere systems. Such structural descriptors arise in rigorous bounds and formulas for effective transport properties, diffusion and reactions constants, elastic moduli, and electromagnetic characteristics. First, we calculate the two-point, surface-void, and surface-surface correlation functions, for which we derive explicit analytical formulas for finite hard-sphere packings. We show analytically how the contact Dirac delta function contribution to the pair correlation function g2(r) for MRJ packings translates into distinct functional behaviors of these two-point correlation functions that do not arise in the other two models examined here. Then we show how the spectral density distinguishes the MRJ packings from the other disordered systems in that the spectral density vanishes in the limit of infinite wavelengths; i.e., these packings are hyperuniform, which means that density fluctuations on large length scales are anomalously suppressed. Moreover, for all model systems, we study and compute exclusion probabilities and pore size distributions, as well as local density fluctuations. We conjecture that for general disordered hard-sphere packings, a central limit theorem holds for the number of points within an spherical observation window. Our analysis links problems of interest in material science, chemistry, physics, and mathematics. In the third paper of this series, we will evaluate bounds and estimates of a host of different physical properties of the MRJ sphere packings that are based on the structural

关键词： Jamming

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Dynamic thermo-mechanical coupled simulation of statistically inhomogeneous materials by statistical second-order two-scale method

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Acta Mechanica Sinica 2015年第5期31卷 762-776页

作者： Zihao Yang Junzhi Cui Yufeng Nie Zhiqiang Huang Meizhen Xiang Department of Applied Mathematics Northwestern Polytechnical University LSEC ICMSECAcademy of Mathematics and Systems ScienceChinese Academy of Sciences Institution of Applied Physics and Computational Mathematics

In this paper,a statistical second-order twoscale（SSOTS） method is developed to simulate the dynamic thcrmo-mechanical performances of the statistically inhomogeneous *** this kind of composite material,the random distribution characteristics of particles,including the shape,size,orientation,spatial location,and volume fractions,are all ***,the *** for the microscopic configuration of the statistically inhomogeneous materials is ***,the SSOTS formulation for the dynamic thermo-mechanical coupled problem is proposed in a constructive way,including the cell problems,effective thermal and mechanical parameters,homogenized problems,and the SSOTS formulas of the temperatures,displacements,heat flux densities and *** then the algorithm procedure corresponding to the SSOTS method is brought *** numerical results obtained by using the SSOTS algorithm are compared with those by classical *** addition,the thermo-mechanical coupling effect is studied by comparing the results of coupled case with those of uncoupled *** demonstrates that the coupling effect on the temperatures,heat flux densities,displacements,and stresses is very *** results show that the SSOTS method is valid to predict the dynamic thermo-mechanical coupled performances of statistically inhomogeneous materials.

关键词： Statistically inhomogeneous materials Dynamic thermo-mechanical coupled performances The SSOTS method The thermo-mechanical coupling effect

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An extended hybrid numerical simulation of isotropic compressible turbulence

arXiv

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arXiv 2017年

作者： Liu, Luoqin Wang, J.C. Shi, Y.P. Chen, S.Y. He, X.T. State Key Laboratory for Turbulence and Complex Systems Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China Department of Mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen518055 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

This paper presents an extension of the hybrid scheme proposed by Wang et al. (J. Comput. Phys. 229 (2010) 169-180) for numerical simulation of compressible isotropic turbulence to flows with higher turbulent Mach numbers. The scheme still utilizes an 8th-order compact scheme with built-in hyperviscosity for smooth regions and a 7th-order WENO scheme for highly compressive regions, but now both in their conservation formulations and for the latter with the Roe type characteristic-wise reconstruction. To enhance the robustness of the WENO scheme without compromising its high-resolution and accuracy, the recursive-order-reduction procedure is adopted, where a new type of reconstruction-failure-detection criterion is constructed. To capture the upwind direction properly in extreme conditions, the global Lax-Friedrichs numerical flux is used. In addition, a new form of cooling function is proposed, which is proved to be positivity-preserving. With these techniques, the new scheme not only inherits the good properties of the original one but also extends largely the computable range of turbulent Mach number, which has been further confirmed by numerical results. Copyright © 2017, The Authors. All rights reserved.

关键词： Turbulence

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Deep convolutional neural networks for estimating porous material parameters with ultrasound tomography

arXiv

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arXiv 2017年

作者： Lähivaara, Timo Kärkkäinen, Leo Huttunen, Janne M.J. Hesthaven, Jan S. Department of Applied Physics University of Eastern Finland Kuopio Finland Nokia Technologies Espoo Finland Nokia Bell Labs Espoo Finland Computational Mathematics and Simulation Science Ecole Polytechnique Fédérale de Lausanne Lausanne Switzerland

We study the feasibility of data based machine learning applied to ultrasound tomography to estimate water-saturated porous material parameters. In this work, the data to train the neural networks is simulated by solving wave propagation in coupled poroviscoelastic-viscoelastic-acoustic media. As the forward model, we consider a high-order discontinuous Galerkin method while deep convolutional neural networks are used to solve the parameter estimation problem. In the numerical experiment, we estimate the material porosity and tortuosity while the remaining parameters which are of less interest are successfully marginalized in the neural networks-based inversion. computational examples confirms the feasibility and accuracy of this approach. Copyright © 2017, The Authors. All rights reserved.

关键词： Deep neural networks

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First Lasing of the CAEP THz FEL facility Driven by a Superconducting Accelerator

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Journal of Physics: Conference Series 2018年第3期1067卷

作者： Dai Wu Ming Li Xinfan Yang Hanbin Wang Xing Luo Xuming Shen Dexin Xiao Jianxin Wang Peng Li Xiangkun Li Kui Zhou Chenglong Lao Yong Xu Peng Zhang Longgang Yan Sifen Lin Qing Pan Lijun Shan Tianhui He Wei Bai Linde Yang Derong Deng Hao Zhang Jie Liu Yanan Chen Dichao Feng Xiaojian Shu Yuhuan Dou Xiangyang Lu Wenhui Huang Institute of Applied Electronics China Academy of Engineering Physics Mianyang 621900 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Institute of Heavy Ion Physics Peking University Beijing 100871 China Department of Engineering Physics Tsinghua University Beijing 10084 China

China Academy of Engineering Physics terahertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. CTFEL consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz lasers frequency is continuously adjustable from 2 THz to 3 THz. The average power is about 20W and the micro-pulse power is more than 0.3 MW.

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