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A nondestructive study of the identification of pigments on monuments by colorimetry

International Journal of Microstructure and Materials Properties 2009年第1期4卷 112-127页

作者： Cheilakou, Eleni Kartsonaki, Milka Koui, Maria Callet, Patrick Materials Science and Engineering Section School of Chemical Engineering National Technical University of Athens Iroon Polytechniou 9 15780 Zografou Athens Greece Arcelor Purchasing Energy Department Arcelor-Mittal Company 19 Avenue de la Liberte L-2390 Luxembourg Luxembourg Applied Mathematics and Systems Laboratory Ecole Centrale Paris Grande Voie des Vignes F-92295 Châtenay Malabry Paris France

The aim of this work was the identification of the pigments of the Philippe Dagobert monument (1222-1232) by spectrophotometry (Visible (VIS) region). Based on the bibliographic information about the pigments used in the Middle Ages, reference coloured samples were prepared in the laboratory. The study was based on the comparative analysis of VIS reflectance spectra, corresponding to laboratory measurements, with the in situ measurements. The obtained results allowed a primary identification of the pigments: the blue stimuli came from a mixture of azurite and malachite, the green from a mixture of equal concentrations of malachite and green earth, while the red and yellow were obtained from red and yellow ochre, respectively, presenting signs of ageing. Finally, it was concluded from these measurements that VIS reflectance spectroscopy could be considered an appropriate nondestructive method for the investigation and characterisation of the chromatic identity of monuments when no sampling is allowed. Copyright © 2009, Inderscience Publishers.

关键词： Mixtures

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Dense packings of polyhedra: Platonic and Archimedean solids

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Physical Review E 2009年第4期80卷 041104-041104页

作者： S. Torquato Y. Jiao Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA

Understanding the nature of dense particle packings is a subject of intense research in the physical, mathematical, and biological sciences. The preponderance of previous work has focused on spherical particles and very little is known about dense polyhedral packings. We formulate the problem of generating dense packings of nonoverlapping, nontiling polyhedra within an adaptive fundamental cell subject to periodic boundary conditions as an optimization problem, which we call the adaptive shrinking cell (ASC) scheme. This optimization problem is solved here (using a variety of multiparticle initial configurations) to find the dense packings of each of the Platonic solids in three-dimensional Euclidean space R3, except for the cube, which is the only Platonic solid that tiles space. We find the densest known packings of tetrahedra, icosahedra, dodecahedra, and octahedra with densities 0.823…, 0.836…, 0.904…, and 0.947…, respectively. It is noteworthy that the densest tetrahedral packing possesses no long-range order. Unlike the densest tetrahedral packing, which must not be a Bravais lattice packing, the densest packings of the other nontiling Platonic solids that we obtain are their previously known optimal (Bravais) lattice packings. We also derive a simple upper bound on the maximal density of packings of congruent nonspherical particles and apply it to Platonic solids, Archimedean solids, superballs, and ellipsoids. Provided that what we term the “asphericity” (ratio of the circumradius to inradius) is sufficiently small, the upper bounds are relatively tight and thus close to the corresponding densities of the optimal lattice packings of the centrally symmetric Platonic and Archimedean solids. Our simulation results, rigorous upper bounds, and other theoretical arguments lead us to the conjecture that the densest packings of Platonic and Archimedean solids with central symmetry are given by their corresponding densest lattice packings. This can be regarded to be

关键词： Optimization

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Low Fractal Dimension Cluster-Dilute Soot Aggregates from a Premixed Flame

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Physical Review Letters 2009年第23期102卷 235504-235504页

作者： Rajan K. Chakrabarty Hans Moosmüller W. Patrick Arnott Mark A. Garro Guoxun Tian Jay G. Slowik Eben S. Cross Jeong-Ho Han Paul Davidovits Timothy B. Onasch Douglas R. Worsnop Desert Research Institute Nevada System of Higher Education Reno Nevada 89512 USA Chemical Physics Program University of Nevada Reno Nevada 89557 USA Department of Physics University of Nevada Reno Nevada 89557 USA Division of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Chemistry University of Toronto Toronto Ontario M5S 3H6 Canada Department of Chemistry Boston College Chestnut Hill Massachusetts 02467 USA Aerodyne Research Inc. Billerica Massachusetts 01821 USA

Using a novel morphology segregation technique, we observed minority populations (≈3%) of submicron-sized, cluster-dilute fractal-like aggregates, formed in the soot-formation window (fuel-to-air equivalence ratio of 2.0–3.5) of a premixed flame, to have mass fractal dimensions between 1.2 and 1.51. Our observations disagree with previous observations of a universal mass fractal dimension of ≈1.8 for fractal-like aerosol aggregates formed in the dilute-limit via three-dimensional diffusion-limited cluster aggregation processes. A hypothesis is presented to explain this observation. Subject to verification of this hypothesis, it may be possible to control the fractal dimension and associated properties of aggregates in the cluster-dilute limit through application of a static electric field during the aggregation process.

关键词： Aggregates

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Diffusion maps - A probabilistic interpretation for spectral embedding and clustering algorithms

Diffusion maps - A probabilistic interpretation for spectral...

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作者： Nadler, Boaz Lafon, Stephane Coifman, Ronald Kevrekidis, Ioannis G. Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot 76100 Israel Google Inc. United States Department of Mathematics Yale University New Haven CT 06520-8283 United States Department of Chemical Engineering Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States

ISBN: (纸本)9783540737490

Spectral embedding and spectral clustering are common methods for non-linear dimensionality reduction and clustering of complex high dimensional datasets. In this paper we provide a diffusion based probabilistic analysis of algorithms that use the normalized graph Laplacian. Given the pairwise adjacency matrix of all points in a dataset, we define a random walk on the graph of points and a diffusion distance between any two points. We show that the diffusion distance is equal to the Euclidean distance in the embedded space with all eigenvectors of the normalized graph Laplacian. This identity shows that characteristic relaxation times and processes of the random walk on the graph are the key concept that governs the properties of these spectral clustering and spectral embedding algorithms. Specifically, for spectral clustering to succeed, a necessary condition is that the mean exit times from each cluster need to be significantly larger than the largest (slowest) of all relaxation times inside all of the individual clusters. For complex, multiscale data, this condition may not hold and multiscale methods need to be developed to handle such situations.

关键词： Relaxation time

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A fundamental analysis of continuous flow bioreactor and membrane reactor models with death and maintenance included

A fundamental analysis of continuous flow bioreactor and mem...

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作者： Nelson, Mark Ian Kerr, Tara Bridget Xiao, Dong Chen School of Mathematics and Applied Statistics University of Wollongong Wollongong NSW 2522 Australia Department of Chemical Engineering Clayton Campus Monash University VIC 3800 Australia

In this research we analyse the steady-state operation of a continuous flow bioreactor, with or without recycle, and an idealised, or non-idealised, continuous flow membrane reactor. The reaction is assumed to be governed by the well-known Monod growth kinetics. We show that a flow reactor with idealised recycle has the same performance as an idealised membrane reactor and that the performance of a non-idealised membrane reactor is identical to an appropriately defined continuous flow bioreactor with non-idealised recycle. The performance of all three reactor types can therefore be obtained by analysing a flow reactor with recycle. The steady-states of the recycle model are found and their stability determined as a function of the residence time. The performance of the reactor at large residence times is obtained. In the limit, as the residence time becomes very large, all three reactor configurations have identical performances. Thus the main advantage of using a membrane reactor, or a flow reactor with recycle, for the treatment of industrial wastewaters and slurries is to improve the performance at low residence times. This is quantified for the case of an ideal membrane reactor. © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

关键词： Bioreactors

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Pre-heated substrate effects on melt-mediated laser crystallization of NiTi thin films

Pre-heated substrate effects on melt-mediated laser crystall...

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ICALEO 2008 - 27th International Congress on Applications of Lasers and Electro-Optics

作者： Birnbaum, Andrew J. Chung, Ui-Jin Huang, Xu Ramirez, Ainissa G. Im, James S. Yao, Y. Lawrence Mechanical Engineering Department Columbia University New York NY 10027 United States Program in Materials Science Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States Mechanical Engineering Department Yale University New Haven CT 06511 United States

Amorphous sputter-deposited NiTi thin films were subjected to pulsed, melt-mediated laser crystallization techniques to engineer their microstructure. The effects of laser processing of pre-heated films are examined. Laser processing of films at an elevated temperature has a significant effect on the rate with which solidification occurs and therefore may be used as an added parameter to control the resulting microstructure. It is seen that the temperature at which processing is carried out has significant implications for the resulting phase and microstructure, and therefore mechanical properties. Furthermore, the microstructural effects of varying incident laser energy density are examined via atomic force microscopy (AFM), scanning electron microscopy (SEM) and x-ray diffraction (XRD), and mechanical/shape memory properties are characterized via nanoindentation.

关键词： Microstructure

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Differential and Integral Isoconversional Non-linear Methods and Their Application to Energetic ***-isothermal Decomposition Reaction Kinetics of Benzotrifuroxan

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中国化学（英文版） 2008年第11期26卷 1973-1978页

作者： GAO Hong-Xu ZHAO Feng-Qi HU Rong-Zu ZHANG Hai DONG Hai-Shan YAO Pu XU Zhou HU Gang Xi'an Modern Chemistry Research Institute Xi'anShaanxi 710065China Department of Mathematics Northwest UniversityXi'anShaanxi 710069China Institute of Chemical Materials China Academy of Engineering PhysicsMianyangSichuan 621900China Shaanxi Applied Physical Chemistry Research Institute Xi'anShaanxi 710061China

The thermal behaviour and decomposition reaction kinetics of benzotrifuroxan(BTF)were determined by TG and DSC *** kinetic parameters of the exothermic decomposition reaction in a temperature pro-grammed mode(the apparent activation energy Ea and pre-exponential factor A)were calculated by a single non-isothermal DSC *** E values calculated using the Kissinger and Flynn-Wall-Ozawa equations and inte-gral isoconversional non-linear equations were used to check the validity of activation energy by a single non-isothermal DSC *** results show that the kinetic model function in integral form and the values of Ea *** critical temperature of thermal explosion of BTF is 257.33 ℃.

关键词： benzotrifuroxan non-isothermal decomposition reaction TG DSC kinetic parameter

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Reply to the Comments by S. Alpert and G. Phillies on ’’Diffusion of spherical macromolecules at finite concentration’’

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The Journal of chemical Physics 2008年第10期65卷 4336-4337页

作者： John L. Anderson C. Christopher Reed Department of Chemical Engineering Cornell University Ithaca New York 14853 Center for Applied Mathematics and Department of Chemical Engineering Cornell University Ithaca New York 14853

John L. Anderson, C. Christopher Reed; Reply to the Comments by S. Alpert and G. Phillies on ’’Diffusion of spherical macromolecules at finite concentration’’,

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First-principles characterization of Ni diffusion kinetics in β-NiAl

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Physical Review B 2008年第18期78卷 184105-184105页

作者： Kristen A. Marino Emily A. Carter Department of Chemical Engineering Princeton University Princeton New Jersey 08544-5263 USA Department of Mechanical and Aerospace Engineering and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544-5263 USA

First-principles density functional theory calculations are performed to examine five postulated diffusion mechanisms for Ni in NiAl: next-nearest-neighbor (NNN) jumps, the triple defect mechanism, and three variants of the six-jump cycle. In contrast to most previous theoretical work, which employed empirical interatomic potentials, we provide a more accurate nonempirical description of the mechanisms. For each pathway, we calculate the activation energy and the pre-exponential factor for the diffusion constant. Although our quantum mechanics calculations are performed at 0 K, we show that it is critical to include the effect of temperature on the pre-exponential factor. We predict that the triple defect mechanism and [110] six-jump cycle both are likely contributors to Ni diffusion in NiAl since their activation energies and pre-exponential factors are in very good agreement with experimental data. Although the activation energy and pre-exponential factor of NNN jumps agree well with experiment, experimental evidence suggests that this is not a dominant contributor to Ni diffusion. Lastly, the activation energies of the [100] bent and straight six-jump cycles are 1 eV higher than the experimental value, allowing us to exclude both [100] cycle mechanisms.

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Fluorinated diamondlike carbon templates for high resolution nanoimprint lithography

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Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures 2008年第6期26卷 2394-2398页

作者： Schvartzman, M. Mathur, A. Kang, Y. Jahnes, C. Hone, J. Wind, S.J. Department of Chemical Engineering Columbia University New York NY 10027 United States Nanotechnology Center for Mechanics in Regenerative Medicine Columbia University New York NY 10027 United States IBM T. J. Watson Research Center Yorktown Heights NY 10598 United States Department of Mechanical Engineering Columbia University New York NY 10027 United States Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States

Nanoimprint templates were fabricated from diamondlike carbon (DLC) films grown on Si, using negative-tone e-beam lithography and oxygen plasma etching. An antiadhesion coating was provided through fluorocarbon-based plasma treatment, which was found to form a Teflon-like thin layer on the treated DLC surface. The fluorinated templates were used to imprint arrays of dots with diameters down to 10 nm in polymethyl-methacrylate. Application of the fluorocarbon plasma treatment was also demonstrated in the antiadhesion treatment of the nanoimprint resist and in elastomer molding. © 2008 American Vacuum Society.

关键词： Nanoimprint lithography

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