检索结果-内蒙古大学图书馆

作者： Li, Jiang-Yu Lei, Chi-Hou Li, Liang-Jun Shu, Yi-Chung Liu, Yun-Ya Department of Mechanical Engineering University of Washington Seattle WA 98195-2600 United States Institute of Applied Mechanics National Taiwan University Taipei Taiwan Faculty of Materials Optoelectronics and Physics Xiangtan University 411105 Hunan China

Transforming materials with evolving microstructures is one of the most important classes of smart materials that have many potential technological applications, and an unconventional phase field approach based on the characteristic functions of transforming variants has been developed to simulate the formation and evolution of their microstructures. This approach is advantageous in its explicit material symmetry and energy well structure, minimal number of material coefficients, and easiness in coupling multiple physical processes and order parameters, and has been applied successfully to study the microstructures and macroscopic properties of shape memory alloys, ferroelectrics, ferromagnetic shape memory alloys, and multiferroic magnetoelectric crystals and films with increased complexity. In this topical review, the formulation of this unconventional phase field approach will be introduced in details, and its applications to various transforming materials will be discussed. Some examples of specific microstructures will also be presented. © The Chinese Society of Theoretical and applied Mechanics and Springer-Verlag Berlin Heidelberg 2012.

关键词： Shape memory effect

来源：评论

学校读者我要写书评

暂无评论

Modification of Outer Layer of Al-Si Alloys by doped Fe atoms

Modification of Outer Layer of Al-Si Alloys by doped Fe atom...

引用

2012 International Conference on Nanotechnology Technology and Advanced Materials(ICNTAM 2012)

作者： D.Chasoglou E.M Pechlivani F.Stergioudi Applied Physics Laboratory Department of Physics Aristotle University of Thessaloniki Physical Metallurgy Laboratory Department of Mechanical Engineering Aristotle University of Thessaloniki

The modification of the outer layer of Al-Si alloys doped with iron atoms was examined. The samples both were taken from automotive pistons and they also were prepared in the laboratory. In any case, they were used as basic raw materials for examination. It was found that the structure and properties of these alloys are very much dependent on the cooling rate, composition and heat treatment. The iron atoms are usually doped, in order to diminish and stabilize the thermal expansion coefficient of the alloys. However, this process makes the alloys to become harder and harder;thus leading the alloys to a degradation of their mechanical behavior at elevated temperatures. Optical Microscope observations, SEM analysis of the interactive surface layers and XRD measurements were performed on tested samples. At elevated temperatures a large homogenized zone extended to about 500(μm) without an apparent distribution of the silicon dendrites or faceted crystals was formed. Moreover at the surface of the so called homogenized zone a layer of about 35(μm) was formed inside of which iron atoms were migrated. This layer is mainly responsible for scuffing phenomena.

关键词： modification alloys x-ray techniques elevated temperatures scuffing

来源：评论

学校读者我要写书评

暂无评论

Photoresponse Characteristics of Archetypal Metal-Organic Frameworks (vol 116, pg 3112, 2012)

引用

JOURNAL OF PHYSICAL CHEMISTRY C 2012年第15期116卷 8858-8858页

作者： Feldblyum, Jeremy I. Keenan, Elizabeth A. Matzger, Adam J. Maldonado, Stephen Macromolecular Science and Engineering University of Michigan Ann Arbor MI 48109-2136 2300 Hayward Avenue United States Department of Chemistry University of Michigan Ann Arbor MI 48109-1055 930 North University United States Program in Applied Physics University of Michigan Ann Arbor MI 48109-1040 450 Church Street United States

The photoelectrochemical responses of two archetypal metal–organic frameworks (MOFs), MOF-5 and MOF-177, have been assessed. Films of MOF-5 and MOF-177 were grown on carboxylic-acid-terminated conductive fluorine-doped tin oxide substrates. Separate analyses by powder X-ray diffraction, Raman spectroscopy, and fluorescence spectroscopy collectively indicated these films prepared via a solvothermal method in diethylformamide were free of residual impurities such as ZnO clusters and residual organics. Exposure of these films to white light illumination while immersed in acetonitrile electrolytes elicited measurable photocurrents. Wavelength-dependent analysis of the photoresponses showed that the measured photocurrents were induced by ultraviolet light and that the spectral response profiles followed closely the light absorption profiles of each respective material. Attenuation of the induced photocurrents was noted after prolonged ultraviolet light illumination and/or exposure of the films to H2O(l), indicating that the observed photoresponse properties are directly related to the structural integrity of these MOFs. The cumulative data illustrate that such MOFs have innately light-sensitive properties that are atypical in high surface area materials.

关键词： Photonics Photoresponse Metal organic frameworks Quantum mechanics Materials

来源：评论

学校读者我要写书评

暂无评论

Ultrafast-laser Modification of Thermoelectric Sb2Te3 Thin Films

引用

MRS Online Proceedings Library 2012年第1期1456卷 1-6页

作者： Li, Yuwei Stoica, Vladimir A. Endicott, Lynn Wang, Guoyu Sun, Huarui Pipe, Kevin P. Uher, Ctirad Clarke, Roy Department of Physics University of Michigan Ann Arbor USA Center for Solar and Thermal Energy Conversion University of Michigan Ann Arbor USA Department of Mechanical Engineering University of Michigan Ann Arbor USA Applied Physics Program University of Michigan Ann Arbor USA

We have modified Sb2Te3 thin film thermoelectric materials by scanning a femtosecond laser across the film surface to create track-like nanostructures. These nanotracks have widths of 50-80 nm and a periodicity of ~ 130 nm. We show that the nanotrack morphology is highly dependent on laser fluence and scan speed. Moreover, we performed transient thermoreflectance measurements on a laser-irradiated film and found a thermal conductivity reduction of 4.5% in the nanostructured regions compared to that of the unmodified regions. These results suggest the potential use of femtosecond pulsed lasers to create nanostructured thermoelectric materials with improved performance.

关键词： laser nanostructure thermoelectric

来源：评论

学校读者我要写书评

暂无评论

Hydrodynamic Fluctuations in Confined Particle-Laden Fluids

引用

Physical Review Letters 2013年第11期111卷 118301-118301页

作者： Nicolas Desreumaux Jean-Baptiste Caussin Raphael Jeanneret Eric Lauga Denis Bartolo Laboratoire de Physique et Mécanique des Milieux Hétérogènes PMMH ESPCI ParisTech CNRS UMR 7636 Université Paris 6 and Université Paris 7 10 Rue Vauquelin 75005 Paris France Laboratoire de Physique de l’Ecole Normale Supérieure de Lyon Université de Lyon and CNRS 46 Allée d’Italie F-69007 Lyon France Department of Mechanical and Aerospace Engineering University of California San Diego 9500 Gilman Drive La Jolla California 92093-0411 USA Department of Applied Mathematics and Theoretical Physics Centre for Mathematical Sciences University of Cambridge Wilberforce Road Cambridge CB3 0WA United Kingdom

We address the collective dynamics of non-Brownian particles cruising in a confined microfluidic geometry and provide a comprehensive characterization of their spatiotemporal density fluctuations. We show that density excitations freely propagate at all scales, and in all directions even though the particles are neither affected by potential forces nor by inertia. We introduce a kinetic theory which quantitatively accounts for our experimental findings, demonstrating that the fluctuation spectrum of this nonequilibrium system is shaped by the combination of truly long-range hydrodynamic interactions and local collisions. We also demonstrate that the free propagation of density waves is a generic phenomenon which should be observed in a much broader range of hydrodynamic systems.

关键词： ANALYTICAL mechanics PARTICLES MICROFLUIDIC analytical techniques SPATIOTEMPORAL processes KINETIC theory of matter

来源：评论

学校读者我要写书评

暂无评论

Terahertz study of reduced graphene oxide

Terahertz study of reduced graphene oxide

引用

International Conference on Infrared and Millimeter Waves

作者： Kyujin Choi Juhwan Lim Taeyoon Hong Taewoo Ha Byung Cheol Park Kyung Ik Sim Jin-Seon Kim Changgu Lee Seong Chan Jun Jae Hoon Kim Department of Physics and Institute of Physics and Applied Physics Yonsei University Seoul South Korea Department of Mechanical Engineering Yonsei University Seoul South Korea School of Mechanical Engineering Sungkyunkwan University Gyeonggi-do South Korea

We report on our terahertz study of the reduction effect on graphene oxide films grown on fused silica substrates by spin-coating. The optical characteristics before and after thermal reduction were studied by teraher... 详细信息

关键词： Silicon compounds Substrates Optical films Optical pulses Electric fields

来源：评论

学校读者我要写书评

暂无评论

Thermal and athermal three-dimensional swarms of self-propelled particles

引用

Physical Review E 2012年第1期86卷 011136-011136页

作者： Nguyen H. P. Nguyen Eric Jankowski Sharon C. Glotzer Department of Mechanical Engineering University of Michigan Ann Arbor Michigan 48109 USA Department of Chemical Engineering University of Michigan Ann Arbor Michigan 48109 USA Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA

Swarms of self-propelled particles exhibit complex behavior that can arise from simple models, with large changes in swarm behavior resulting from small changes in model parameters. We investigate the steady-state swarms formed by self-propelled Morse particles in three dimensions using molecular dynamics simulations optimized for graphics processing units. We find a variety of swarms of different overall shape assemble spontaneously and that for certain Morse potential parameters at most two competing structures are observed. We report a rich “phase diagram” of athermal swarm structures observed across a broad range of interaction parameters. Unlike the structures formed in equilibrium self-assembly, we find that the probability of forming a self-propelled swarm can be biased by the choice of initial conditions. We investigate how thermal noise influences swarm formation and demonstrate ways it can be exploited to reconfigure one swarm into another. Our findings validate and extend previous observations of self-propelled Morse swarms and highlight open questions for predictive theories of nonequilibrium self-assembly.

关键词： MORSE theory MOLECULAR dynamics PHASE diagrams LANGEVIN equations COMPUTER simulation

来源：评论

学校读者我要写书评

暂无评论

Effect of Film Thickness Variation on (100)-Surface Texturing of MPS Processed Polycrystalline Si Films

引用

MRS Online Proceedings Library 2012年第1期1426卷 257-262页

作者： Monica Chahal P. C. van der Wilt D. Van Gestel A. B. Limanov A. M. Chitu James S. Im Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New York USA IMEC Solar Cell Tech. Group Leuven Belgium WCU Program Department of Materials Science and Engineering College of Engineering Korea Advanced Institute of Science and technology (KAIST) Korea

We have investigated the effect of varying the film thickness on the surface orientation texturing in polycrystalline Si films obtained via mixed-phase solidification (MPS) of initially a-Si precursor films on SiO2. It is found that, for a given number of MPS exposure cycles, the degree of (100)-surface texturing is reduced as the film thickness is increased. We discuss how this trend can be accounted for by the previously proposed thermodynamic model of MPS, wherein a decreasing local solid/liquid interface curvature with increasing film thickness is identified as the primary cause for decreasing the influence which anisotropic solid-Si/SiO2 interfacial energies have on the survivability of the grains. This, in turn, leads to other factors becoming more significant in determining the grains that survive the MPS cycle, thereby reducing the degree of (100)-surface texturing in the resulting films.

关键词： Si microstructure texture

来源：评论

学校读者我要写书评

暂无评论

Automated indirect transport of biological cells with optical tweezers using planar gripper formations

Automated indirect transport of biological cells with optica...

引用

2012 IEEE International Conference on Automation Science and engineering: Green Automation Toward a Sustainable Society, CASE 2012

作者： Chowdhury, Sagar Thakur, Atul Wang, Chenlu Svec, Petr Losert, Wolfgang Gupta, Satyandra K. Department of Mechanical Engineering Institute for Systems Research University of Maryland College Park MD 20742 United States Department of Mechanical Engineering University of Maryland College Park MD 20742 United States Biophysics Program University of Maryland College Park MD 20742 United States Department of Physics Institute for Physical Science and Technology University of Maryland College Park MD 20742 United States

ISBN: (纸本)9781467304283

Optical tweezers are used for manipulation of micron-sized dielectric beads and cells. Some biological cells are vulnerable to photo damage if subjected to laser-based direct manipulation. In such cases, precise manipulation of these cells can be accomplished by using gripper formations made up of silica beads, which are actuated by optical tweezers. Manual indirect manipulation of cells using grippers made of optically trapped beads is a time consuming process or sometimes just impossible. This paper presents an approach for automated micromanipulation using gripper formations and heuristic based path planning for collision-free transport of biological cells. The objective of the developed planner is to transport target cells to their respective goal positions in the minimum time. we evaluated the performance of different gripper formations in terms of gripper stability, speed of transport, and required laser power using experiments. © 2012 IEEE.

关键词： Grippers

来源：评论

学校读者我要写书评

暂无评论

Reconstructing 3D x-ray CT images of polymer gel dosimeters using the zero-scan method

引用

Journal of physics: Conference Series 2013年第1期444卷

作者： M B Kakakhel T Kairn J Kenny J V Trapp School of Chemistry Physics & Mechanical Engineering Queensland University of Technology GPO Box2434 Brisbane Qld 4001 Australia Department of Physics and Applied Mathematics DPAM Pakistan Institute of Engineering and Applied Sciences PO Nilore Islamabad 45650 Pakistan Premion Cancer Care The Wesley Medical Centre Suite 1 40 Chasely St Auchenflower Qld 4066 Australia

In this study x-ray CT has been used to produce a 3D image of an irradiated PAGAT gel sample, with noise-reduction achieved using the 'zero-scan' method. The gel was repeatedly CT scanned and a linear fit to the varying Hounsfield unit of each pixel in the 3D volume was evaluated across the repeated scans, allowing a zero-scan extrapolation of the image to be obtained. To minimise heating of the CT scanner's x-ray tube, this study used a large slice thickness (1 cm), to provide image slices across the irradiated region of the gel, and a relatively small number of CT scans (63), to extrapolate the zero-scan image. The resulting set of transverse images shows reduced noise compared to images from the initial CT scan of the gel, without being degraded by the additional radiation dose delivered to the gel during the repeated scanning. The full, 3D image of the gel has a low spatial resolution in the longitudinal direction, due to the selected scan parameters. Nonetheless, important features of the dose distribution are apparent in the 3D x-ray CT scan of the gel. The results of this study demonstrate that the zero-scan extrapolation method can be applied to the reconstruction of multiple x-ray CT slices, to provide useful 2D and 3D images of irradiated dosimetry gels.

关键词：

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：