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作者： McKenna, I.M. Gururajan, M.P. Voorhees, P.W. Department of Materials Science and Engineering Northwestern University Evanston IL 60208 United States Department of Applied Mechanics Indian Institute of Technology - Delhi Hauz Khas New Delhi 110016 India

Phase-field models based on multiple order parameters are used extensively to study grain growth in polycrystalline materials. However, if simulations are to be carried out using experimentally obtained microstructures as the initial condition, and the resultant microstructures are to be carefully compared with those obtained from experiments, then the parameters used in the numerical simulations need to be benchmarked with analytical solutions. Furthermore, the models themselves need to be modified to incorporate the dependence of grain boundary energy on misorientation across the boundary as well as the anisotropy in the boundary energy for any given misorientation that stems from the planes of different grains that make up the boundary. In this article, we address both these issues and present some preliminary results from our 2D and 3D simulations. © 2009 Springer science+Business Media, LLC.

关键词： Grain growth

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Electrodeposition of silicon thin films from ionic liquids

Electrodeposition of silicon thin films from ionic liquids

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作者： Martinez, A.M. Osen, K.S. Kongstein, O.E. Sheridan, E. Ulyashin, A. Haarberg, G.M. SINTEF Materials and Chemistry Department of Energy Conversion and Materials Sem Saelands vei 12 7465 Trondheim Norway SINTEF Materials and Chemistry Department of Applied Mechanics and Corrosion Richard Birkelands vei 2 B 7465 Trondheim Norway Department of Materials Science and Engineering Norwegian University of Science and Technology Sem Saelands vei 12 7491 Trondheim Norway

ISBN: (纸本)9781566778008

The possibility of obtaining Si thin films by electrodeposition from the oxygen and water stable N-butyl-N-methyl-pyrrolidinium bis(trifluoromethyl- sulfonyl)amide ionic liquid at room temperature was investigated. The results obtained using SiCl4and SiBr4 as precursors and aluminium and nickel as substrates were compared. Cyclic voltammetry, square wave voltammetry and chronoamperometry were used to characterize the electroreduction step of the silicon species. The results showed that the growth of the silicon layer is very slow, yielding only clusters of silicon at low cathodic potentials and short electrolysis times. At higher electrodeposition potentials and/or longer deposition times, the films became rougher and cracks appeared in the layers. This was mainly due to the accumulation of tensile strains during growth. The layers were very reactive to air and humidity, probably due to the high porosity of the film. In some cases, contamination of the layers by S and F was also observed. ©The Electrochemical Society.

关键词： Electrodeposition

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Quantitative microstructural analysis of a nylon 6,6/E-glass long fiber thermoplastic composite

Quantitative microstructural analysis of a nylon 6,6/E-glass...

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2009 SAMPE Fall Technical Conference and Exhibition - Global Material Technology: Soaring to New Horizons

作者： Chevali, Venkata S. Vaidya, Uday K. Janowski, Gregg M. Department of Materials Science and Engineering University of Alabama at Birmingham 1530 3rd Avenue South Birmingham AL 35205 United States Department of Mechanical Engineering and Applied Mechanics North Dakota State University 1301 12th Avenue North Fargo ND 58102 United States

ISBN: (纸本)9781934551066

Long fiber thermoplastic (LFT) composites are emerging as cost-effective alternatives to many metal and thermoset composite applications. The training-round tailcone is a subcomponent of a military application where LFT replaces machined aluminum alloy, with significant cost savings and comparable performance. Challenges remain in understanding how processing affects porosity fiber agglomeration, and fiber alignment, which is critical in predicting mechanical properties. The most common features of the LFT microstructure are centerline porosity, fiber alignment, matrix cracking, and low volume fraction of fibers in flow-constricted regions, and the formation of resin-rich and fiber-rich regions as an effect of processing. The present study quantifies the effect of microstructure on the three-stage firing performance and in tensile pullout of the tailcone.

关键词： Fibers

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A temperature-dependent study on the polarization-free straining of barium titanate single crystals

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Smart materials and Structures 2009年第10期18卷

作者： Shieh, J. Lin, J.A. Shu, Y.C. Department of Materials Science and Engineering National Taiwan University Taipei 106 Taiwan Institute of Applied Mechanics National Taiwan University Taipei 106 Taiwan

Previous studies by the authors have shown that, when subjected to combined uniaxial stress and electric field at room temperature, a (001)-oriented barium titanate (BaTiO3) single crystal may display incomplete switching characteristics and a severe disproportion of slope gradients at zero electric field for its polarization and strain hysteresis curves. It is proposed that the likely causes for the observed 'decoupling' of switching strain and switching polarization at room temperature are the cooperative operation of multiple 90 switching systems, by which 'polarization-free' strain changes could be induced, and the presence of depolarization fields generated from the unshielded boundaries and/or incompatible domains within the crystal. In the present study, the evolution of polarization and strain hystereses of BaTiO3 single crystals under various electromechanical loading combinations are investigated again at 55 °C. When compared to the hysteresis measurements at room temperature, the degree of discrepancy between the slope gradients at zero electric field for the polarization and strain hysteresis curves measured at 55 °C is significantly reduced. This is due to the increase in domain wall mobility at a higher temperature, lowering the extent of incomplete switching at maximum electric field. At 55 °C, domains with 180 relative orientation are less likely to exist at maximum electric field;hence, the critical prerequisite for polarization-free straining is no longer available. The experimental data obtained in the present study are expected to assist the development of reliable constitutive models for single-crystal ferroelectrics. © 2009 IOP Publishing Ltd.

关键词： Single crystals

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Computed tomography based finite element analysis of the thermal properties of cellular aluminium

Computed tomography based finite element analysis of the the...

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作者： Fiedler, T. Solórzano, E. Garcia-Moreno, F. Öchsner, A. Belova, I.V. Murch, G.E. Centre for Mass and Thermal Transport in Engineering Materials School of Engineering University of Newcastle Callaghan Australia Condensed Matter Physics Department University of Valladolid Valladolid Spain Department of Materials Science Hahn-Meitner-Institut Berlin Berlin Germany Technical University Berlin Berlin Germany Department of Applied Mechanics Faculty of Mechanical Engineering Technical University of Malaysia UTM Skudai Johor Malaysia Centre for Mass and Thermal Transport in Engineering Materials School of Engineering University of Newcastle Callaghan NSW 2308 Australia

This work addresses the thermal finite element analysis (FE) of cellular aluminium with irregular pore structures. The used finite element models are generated with computed tomography (CT) images as a basis. Three-dimensional brick elements of cubic shape are used. The material properties of each element are thereby defined based on corresponding pixels in computed tomography images. The proposed analysis with mapping of material properties on a regular finite element mesh is first validated on simple two dimensional models of regular geometries. The obtained results are compared to highly accurate reference solutions and analytical predictions. Subsequently, the FEM thermal analysis of closed cell Alporas aluminium foam and open cell M-Pore aluminium sponge is carried out determining the effective thermal conductivities of these materials in three perpendicular directions in order to investigate the anisotropic properties of both structures. The variability in the material volume (due to meso-inhomogeneities) has been inspected by computing different sub-volumes of the specimens. © 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

关键词： Aluminum

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Light control in organic electroluminescence devices by plasmonic grating coupled emission for biochemical applications

Light control in organic electroluminescence devices by plas...

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Plasmonics in Biology and Medicine VI

作者： Chiu, Nan-Fu Lee, Jiun-Haw Tsai, Feng-Yu Liu, Kuo-Chen Lee, Chun-Nan Lee, Chih-Kung Lin, Chii-Wann Institute of Biomedical Engineering Taiwan Department of Electrical Engineering Taiwan Graduate Institute of Electro-Optical Engineering Taiwan Department of Materials Science and Engineering Graduate Institute of Electro-Optical Engineering Chang Gung University 333 R.O.C Taiwan Department of Clinical Laboratory Sciences and Medical Biotechnology Institute of Applied Mechanics Taiwan Center for Nano Science and Technology National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei R.O.C Taiwan

ISBN: (纸本)9780819474384

We report the influence of organic electroluminescence (OEL) device on the color tunability and emission efficiency enhancement by surface plasmon grating coupled emission (SPGCE). The effect of coupling active surface plasmon polaritons (SPPs) on the metal nanostructure grating with organic material interface was studied. The dispersion relation was obtained from angle-resolved emission measurements. The combination of organic/metal interface SPPs mode allows specific directional emission rather than isotropic emission. Control of light emission angle in the SPGCE is dependent upon the index of refraction at the organic/metal/dielectric interface. Recent experimental results and potential applications of an active plasmonics biosensor with enhanced resonant energy emission due to interactions on the organic/metal nano-grating were presented and discussed. © 2009 SPIE.

关键词： Photons

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Critical dynamics in multicomponent lipid membranes

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Physical Review E 2009年第2期80卷 020902(R)-020902(R)页

作者： Mikko Haataja Department of Mechanical and Aerospace Engineering Princeton Institute for the Science and Technology of Materials (PRISM) and Program in Applied and Computational Mathematics (PACM) Princeton University Princeton New Jersey 08544 USA

The formation and dynamics of spatially extended compositional domains in multicomponent lipid membranes both in vivo and in vitro lie at the heart of many important biological and biophysical phenomena. While the thermodynamic basis for domain formation has been explored extensively in the past, the roles of membrane and exterior fluid hydrodynamics on domain formation kinetics have received less attention. A case in point is the impact of hydrodynamics on the dynamics of compositional heterogeneities in lipid membranes in the vicinity of a critical point. In this Rapid Communication it is argued that the asymptotic dynamic behavior of a lipid membrane system in the vicinity of a critical point is strongly influenced by hydrodynamic interactions. More specifically, a mode-coupling argument is developed which predicts a scaling behavior of lipid transport coefficients near the critical point for both symmetric and asymmetric bilayers immersed in a bulk fluid.

关键词： Hydrodynamics

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Connector faculty: A friendly face for early engineering students

Connector faculty: A friendly face for early engineering stu...

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2009 ASEE Annual Conference and Exposition

作者： Briedis, Daina Buch, Neeraj Collins-Eaglin, Jan Ehrlich, Nathaniel Fleming, Denise Hinds, Timothy Sticklen, Jon Urban-Lurain, Mark Wolff, Thomas Department of Chemical Engineering and Materials Science Michigan State University United States Department of Civil and Environmental Engineering Michigan State University United States Cornerstone Engineering and Residential Experience Program Michigan State University United States Michigan State University United States United States College of Engineering Michigan State University United States Michigan State University College of Engineering Undergraduate Studies Department of Mechanical Engineering United States Applied Engineering Sciences College of Engineering Michigan State University United States Computer Science and Engineering Department Michigan State University United States Division of Science and Mathematics Education College of Natural Science Michigan State University United States Engineering for Undergraduate Studies Michigan State University United States

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Dielectric constant at x -band microwave frequencies for multiferroic BiFeO3 thin films

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Journal of applied Physics 2009年第7期105卷

作者： Abdul Ahad, Faris B. Hung, D.S. Yao, Y.D. Lee, S.F. Tu, C.S. Wang, T.H. Chen, Y.Y. Fu, Y.P. Institute of Physics and Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei 115 Taiwan Department of Engineering and System Science NTHU Hsinchu 300 Taiwan Department of Information and Telecommunication Engineering Ming Chuan University Taipei 111 Taiwan Department of Materials Engineering Tatung University Taipei 104 Taiwan Department of Graduate Institute of Applied Science and Engineering Fu Jen University Taipei 242 Taiwan Department of Materials Science and Engineering National Dong Hwa University Hualien 974 Taiwan

The magnetic-induced dielectric responses of BiFeO3 (BFO) thin films were measured at the X -band microwave frequency ranged from 7 to 12.5 GHz. The measurement was given initially by a high-precision cavity microwave resonator without magnetic field. Both the real and imaginary parts of the permittivity showed its dielectric property as a function of the measuring frequency. The X -band dielectric responses of the BFO thin film were then measured by a controlled magnetic field at room temperature. The data demonstrated up to 2.2% dielectric tunability by using only 3.46 kOe magnetic field at TE107 mode (9.97705 GHz). © 2009 American Institute of Physics.

关键词： Magnetic fields

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Comparison of international learning outcomes and development of engineering curricula

Comparison of international learning outcomes and developmen...

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2009 ASEE Annual Conference and Exposition

作者： Alkhairy, Ashraf Blank, Leland Boning, Duane Cardwell, David Carter, W. Craig Collings, Nick Hayhurst, Allan Milne, William Robinson, Peter Seering, Warren Sheppard, Sallie Smith, Kenneth Stronge, Bill Alfaisal University Saudi Arabia Texas A and M University Qatar United States Department of Electrical Engineering and Computer Science MIT United States Department of Engineering University of Cambridge United Kingdom Department of Materials Science MIT United States Department of Chemical Engineering Cambridge University United Kingdom Department of Electrical Engineering Cambridge University United Kingdom Electronic Devices and Materials Group United Kingdom Department of Computer Technology Computer Laboratory University of Cambridge United Kingdom Department of Mechanical Engineering MIT United States Department of Engineering Systems MIT United States Design and Systems Division of Mechanical Engineering Nissan Cambridge Basic Research Laboratory MIT Center for Innovation in Product Development Department of Computer Science Texas A and M University United States Department of Chemical Engineering MIT United States Whitaker College of Health Sciences and Technology United States Department of Applied Mechanics Cambridge University United Kingdom University of California Davis United States

Various national and regional engineering accreditation bodies have developed sets of learning or program outcomes that serve as the foundation for the evaluation of curriculum quality. Some of the outcome structures are very broadly defined, leaving the details of curriculum design and the justification to the university and the accreditation evaluators. Other accreditation bodies define outcomes more thoroughly in topic and depth, with accreditation hinging on the general fit of the curriculum to these specifications. Most of these outcome structures have been developed and used as accreditation standards predominantly over the last decade. During this time, existing curricula are usually altered and upgraded (that is, 'retrofitted') to meet the outcomes requirements. However, new degree programs and new engineering colleges have the opportunity to use the relevant outcomes as design specifications. Such a design ensures quality, prepares the college for future accreditation evaluation, and can be tailored to meet the needs of students and prospective employers. This paper compares the outcomes structure and contents of several accreditation bodies, including the engineering Council of the UK (EC UK), EUR-ACE of the EU, and ABET of the USA. Similarities and differences between the outcomes of the bodies will be highlighted. The use of these accrediting standards as the basis of design specifications for engineering degrees at the Alfaisal University in Riyadh, Saudi Arabia will be presented. The designs for integrated BS, MS and PhD curricula were developed over a two-year period, based on the defined learning outcomes, by a committee comprised of the Founding Dean of engineering and faculty from the Massachusetts Institute of Technology (MIT), the University of Cambridge and independent reviewers. Example BS and MS curricula and their fit to the outcome specifications are described. © American Society for engineering Education, 2009.

关键词： Accreditation

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