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Erratum: Glassy Chimeras could be blind to quantum speedup: Designing better benchmarks for quantum annealing machines [Phys. Rev. X 4, 021008 (2014)]

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Physical Review X 2015年第1期5卷 019901-019901页

作者： Martin Weigel Helmut G. Katzgraber Jonathan Machta Firas Hamze Ruben S. Andrist Applied Mathematics Research Centre Coventry University Coventry CV1 5FB United Kingdom Department of Physics and Astronomy Texas A&M University College Station Texas 77843-4242 USA Materials Science and Engineering Program Texas A&M University College Station Texas 77843 USA Santa Fe Institute 1399 Hyde Park Road Santa Fe New Mexico 87501 USA Physics Department University of Massachusetts Amherst Massachusetts 01003 USA D-Wave Systems Inc. 3033 Beta Avenue Burnaby British Columbia V5G 4M9 Canada

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Carbon fiber based custom orthoses for augmenting net ankle moment in gait

Carbon fiber based custom orthoses for augmenting net ankle ...

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SAMPE 2013 Conference and Exhibition: Education and Green Sky - materials Technology for a Better World

作者： Khattra, Narinder S. Tierney, John J. Yarlagadda, Shridhar Shevchenko, Nicholas Gillespie Jr., John W. Schrank, Elisa S. Stanhope, Steven J. Center for Composite Materials University of Delaware Newark DE 19716 United States Department of Mechanical Engineering University of Delaware Newark DE 19716 United States Department of Civil and Environmental Engineering University of Delaware Newark DE 19716 United States Department of Materials Science and Engineering University of Delaware Newark DE 19716 United States Department of Kinesiology and Applied Physiology University of Delaware Newark DE 19716 United States Department of Biomedical Engineering University of Delaware Newark DE 19716 United States Biomechanics and Movement Science Interdisciplinary Program University of Delaware Newark DE 19716 United States

ISBN: (纸本)9781934551158

Passive-dynamic ankle-foot orthoses (PD-AFOs) are a common form of assistive braces prescribed to improve gait of patients having impaired ankle joint function. The PD-AFO structural bending response is used to compensate for a patient's reduced ankle moment. This work focuses on the design and analysis of a carbon fiber based composite PD-AFO that provides a thin, lighter weight alternative to the more commonly used plastic based PD-AFOs. The purpose of this study was to demonstrate feasibility of designing composite PD-AFOs having desired bending stiffness. A custom, 3D surface model of the brace is used to create the overall geometry. The composite lay-up and associated stiffness of the composite PD-AFO is determined numerically, as a function of ankle angle for the foot-flat phase of the gait cycle. It is shown that the brace can be designed to augment the lost natural ankle stiffness of a patient to match that of a healthy person. The results indicate that the geometry of a PD-AFO, composite lay-up and the material properties are key factors in achieving the desired stiffness characteristics. Copyright 2013 by Aurora Flight sciences.

关键词： Carbon fibers

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Hybrid multiscale composite with electrospun carbon nanofibers

Hybrid multiscale composite with electrospun carbon nanofibe...

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International Symposium on Fibers Interfacing the World 2013

作者： Zhao, Yong Lai, Chuilin Xi, Min Fong, Hao Department of Chemistry and Applied Biological Sciences South Dakota School of Mines and Technology Rapid City South Dakota57701-3995 United States Program of Materials Engineering and Science South Dakota School of Mines and Technology Rapid City South Dakota57701-3995 United States

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Effect of strain on the stacking fault energy of copper: A first-principles study

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Physical Review B 2013年第6期88卷 064104-064104页

作者： P. S. Branicio J. Y. Zhang D. J. Srolovitz Institute of High Performance Computing Agency for Science Technology and Research 1 Fusionopolis Way 16-16 Connexis 138632 Singapore Department of Materials Science and Engineering and Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania 3231 Walnut Street Philadelphia Pennsylvania 19104 USA

The intrinsic stacking fault energy (SFE) of copper under volumetric, longitudinal, and shear strains is investigated using density functional theory (GGA-PBE). Calculations are performed using a copper slab model aligned perpendicular to the (111) intrinsic stacking fault plane. The calculated SFE for unstrained copper is γ = 41 mJ/m2. Results show a strong dependence of γ on strain and distinct behavior for different types of strain: (a) volumetric and longitudinal in the direction perpendicular to the stacking fault, (b) longitudinal parallel to the stacking fault, and (c) shear parallel to the stacking fault. In the first case (a), the SFE decreases monotonically with strain with a slope dγ/dε|ɛ=0 = −0.44 J/m2 and −0.87 J/m2 for volumetric and longitudinal, respectively, and with d2γ/dε2 > 0. In contrast, for longitudinal strain parallel to the stacking fault (b), the SFE dependence exhibits d2γ/dε2 < 0 with a maximum at ε ≈ −0.015. For the case of shear parallel to the stacking fault (c), the SFE is nearly constant at small and moderately large strain, but drops rapidly at very large strain (by a factor of 1/3 for 〈1¯10〉{111} shear at ε = ±0.1). For large 〈112¯〉{111} shear strains, the SFE can either increase or decrease at large strain depending on the sign of the strain. In volumetric or longitudinal (perpendicular to the stacking fault) tension and longitudinal strain in the boundary plane (and for some shear directions), the SFE can become negative, implying a limit on the stability of the fcc crystal structure. The strong dependence of the SFE on strain suggests deep implications for the mechanical properties, microstructural evolution, and dynamic plasticity of metals at high pressure, during severe plastic deformation, and in shock-loading conditions.

关键词： COPPER STACKING faults (Crystals) SHEAR (mechanics) STRAINS & stresses (mechanics) DENSITY functional theory

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Thermoeconomic design and optimization of frost-free refrigerators

Thermoeconomic design and optimization of frost-free refrige...

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作者： Mitishita, Rodrigo S. Barreira, Eduardo M. Negrão, Cezar O.R. Hermes, Christian J.L. Thermal Science Laboratory Postgraduate Program of Mechanical and Materials Engineering Federal University of Technology - Paraná Av. Sete de Setembro 3165 80230901 Curitiba PR Brazil Center for Applied Thermodynamics Department of Mechanical Engineering Federal University of Paraná P.O. Box 19011 81531990 Curitiba PR Brazil

An optimization methodology aiming at energy and cost savings in frost-free refrigerators is advanced. A steady-state simulation model was devised and its predictions for energy consumption were compared with experimental data obtained elsewhere, with differences not exceeding a +/- 9% error band. The model was used to find out the evaporator air flow rate, the number of evaporator and condenser fins, the compressor size and efficiency, and the insulation thicknesses of both fresh- and frozen-food compartments which yield the minimum energy consumption when the total cost is constrained. The optimization led to a refrigeration system with energy consumption 18% lower than that observed for the baseline system without any cost penalty. The system performance for four different compressors, including a high efficiency, a large capacity and a variable-speed one, was also analyzed. For the refrigerator under analysis, it was found that, to ensure an economically feasible design, the variable-speed compressor should not cost 26% more than a single-speed one with the same piston displacement. © 2012 Elsevier Ltd. All rights reserved.

关键词： Compressors

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Correlation and relativistic effects in U metal and U-Zr alloy: Validation of ab initio approaches

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Physical Review B 2013年第23期88卷 235128-235128页

作者： Wei Xie (谢玮) Wei Xiong Chris A. Marianetti Dane Morgan Materials Science Program University of Wisconsin-Madison Madison Wisconsin 53706 USA Department of Materials Science and Engineering University of Wisconsin-Madison Madison Wisconsin 53706 USA Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA Department of Engineering Physics University of Wisconsin-Madison Madison Wisconsin 53706 USA

Ab initio calculations have been performed on all solid phases of U metal and U-Zr alloy, the basis of a promising metallic fuel for fast nuclear reactors. Based on generalized gradient approximation, both density functional theory (DFT) in its standard form and the so-called DFT plus Hubbard U (DFT+U) modification are evaluated. The evolution of calculated energetics, volume, magnetic moments, electronic structure, and f-orbital occupation as functions of the effective Hubbard U parameter, Ueff, is carefully examined at Ueff from 0 to 4 eV. DFT is found to overestimate energetics, underestimate volume, downward shift some f bands near Fermi level and overestimate f-orbital occupation against existing experimental and/or computational data. The error is ∼0.07 eV/atom in terms of enthalpy, which affects phase stability modeling for δ(U,Zr) and γ(U,Zr). DFT+U at Ueff=1−1.5 eV offers clear improvement on these calculated properties (∼0.05 eV/atom in terms of enthalpy) and in general still neither promotes ordered magnetic moments nor opens unphysical band gaps, which occur at higher Ueff values. The empirical Ueff values of 1–1.5 eV are close to but smaller than the theoretical estimations of 1.9–2.3 eV that we obtain from the linear response approach. Ueff is found to vary only slightly (≤0.24 eV) between different phases and at different compositions of U and U-Zr; thus, a single Ueff=1.24 eV, which is the statistical optimal from energetic fitting, is suggested for both U and U-Zr. Besides correlation, the relativistic effect of spin-orbit coupling (SOC) is also systematically explored. SOC is found to lower energy, increase volume, and split the 5f shell above Fermi level and reduce f-orbital occupation. The effect predominates in the unoccupied states and is very small on all these calculated ground state properties (∼0.02 eV/atom in terms of enthalpy).

关键词： NUCLEAR reactors HUBBARD model ELECTRONIC structure FERMI level MAGNETIC moments

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Process simulation of ultrasonic additive manufacturing and the prediction of interface bonding

Process simulation of ultrasonic additive manufacturing and ...

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materials science and Technology Conference and Exhibition 2013, MS and T 2013

作者： Cheng, Jinquan Chaudhary, Anil Babu, Sudarsanam Norfolk, Mark Foster, Daniel Boone, Derek Applied Optimization Inc. 714 E. Monument Ave. Dayton OH 45402 United States Department of Materials Science and Engineering Welding Engineering Program Ohio State University Columbus OH 43210 United States Fabrisonic LLC 1250 Authur E Adam Dr. Columbus OH 43221 United States

ISBN: (纸本)9781629933092

In order to predict the quality of UAM bonding and to provide a framework for the optimization of UAM processing parameters, a multi-scale laminated plate model is presented in this paper. The model considers the interface deformations and stress distribution, which are represented using a spring boundary layer model. The spring stiffness is utilized to represent the extent of interfacial bonding. The evolution of the spring stiffness is determined by a micromechanical model. The simulation predicts how the character of dynamic response for the substrate, foil and the sonotrode changes as a function of the UAM bonding. These predictions are in agreement with UAM bonding experimental data. Copyright © 2013 MS&T'13®.

关键词： Forecasting

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Thermoeconomic analysis and optimization of residential split-type air conditioners

Thermoeconomic analysis and optimization of residential spli...

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作者： Barreira, Eduardo M. Negrão, Cezar O.R. Hermes, Christian J.L. Thermal Science Laboratory Postgraduate Program of Mechanical and Materials Engineering Federal University of Technology - Paraná Av. Sete de Setembro 3165 80230-901 Curitiba PR Brazil Center for Applied Thermodynamics Department of Mechanical Engineering Federal University of Paraná P.O. Box 19011 81531-990 Curitiba PR Brazil

A simulation-based optimization methodology for designing unitary residential air conditioners with focus on both energy performance enhancement and cost savings is presented. A steady-state system simulation model was put forward for a 2.5-ton nominal cooling capacity split-type air conditioning unit operating with R-410A as the working fluid. The model predictions for cooling capacity, sensible heat ratio (SHR) and coefficient of performance (COP) were compared with experimental data, when it was found that the model is able to predict the experimental trends within a ±6% error band. The model was then used to find out the condenser and evaporator geometries (face area, heat transfer area) that enhance the system COP for a fixed cost. On one hand, it was observed that the COP can be increased by 7% if the cost is held fixed. On the other hand, cost savings of 33% were achieved when the system COP was held constant. © 2012 Elsevier Ltd. All rights reserved.

关键词： Air conditioning

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High Efficiency Water Purification through Parallel Nano Desalinator under Electric Field

High Efficiency Water Purification through Parallel Nano Des...

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第八届全国微全分析系统学术会议、第三届全国微纳尺度生物分离分析学术会议暨第五届国际微化学与微系统学术会议

作者： Chin-Yu lin Yu-Sheng Huang Chia-Jung Chang Wen-Chih Chang Yu-Lun Chueh Fan-Gang Tseng Division of Mechanics Research Center for Applied SciencesAcademia SinicaTaiwan Department of Engineering and System Science National Tsing Hua UniversityTaiwan Industrial Technology Research InstituteITRI South/Microsystem Technology Center Department of Materials Science and EngineeringNational Tsing Hua UniversityTaiwan Department of Engineering and System ScienceNational Tsing Hua UniversityTaiwan

The *** Survey found that there is 96.5% water in the oceans and sea,1.7% in the ice caps,1% in brackish water,and only 0.8% fresh water [1].1.2 billion people lack access to safe drinking water,millions of people die annually from diseases transmitted through unsafe water [2].The best answer to solve the water shortage issue is transform sea water into fresh *** paper proposes to employ the stacking of two nano desalinators in parallel for water *** on the overlapping of electro-double-layer (EDL) inside the anodic aluminum oxide (AAO) nanochannels as virtual filter,each desalinator can select uni-ions for desalination [our previous paper].This study extends the previous result further,to apply electrical field throughout the stacking region of double desalinators from outside,thus both positive and negative ions can be separated at the same *** operation principle of the desalination system is shown in *** surface of the nano desolinator was coated with a conductive metal layer and an insulation *** enough voltages applied on the nano channel,the thickness of the EDL will increase to overlap owning to the increment of the charge density on the channel[3].When water passing through the channel,the co-ions are kept in the enter side due to electrostatic expelling while the counter-ions and water can go through the channel rapidly.A concept-testing model is designed as shown in Fig.2(a)un-ion separation testing,and it consists of two chambers stacking on a piece of nano desalinator.1M NaCl solution and pure water were loaded into the upper and lower chamber,*** stacked nano-desalinator is shown in Fig.2(b)consisting of two nano desalinators under electric field to filter out both positive and negative *** result of the concept-testing model for NaCl solution is shown *** the applications of +0.1V,+0.3V and +0.5V onto the desalinator membrane,the concentrations were reduced to 14.96 mM,12.12

关键词： desalinator AAO EDL electric field

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Simulating gasdynamic interaction and radiative heating within scramjets with hydrocarbon fuels

Simulating gasdynamic interaction and radiative heating with...

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44th AIAA Thermophysics Conference

作者： Surzhikov, S.T. Zheleznyakova, A.L. Shang, J.S. Rivir, R.B. Institute for Problem in Mechanics Russian Academy of Science-IPMech RAS Radiative Gasdynamic Laboratory Moscow 119526 Russia Center for Basic and Applied Research All-Russian Scientific Research Institute of Automatics Moscow Russia Russia Wright State University Mechanical and Materials Engineering Department Dayton OH 45435 United States Air Force Research Laboratory WPAFB OH United States

Convective and radiative heating of internal surfaces of two scramjets, dual-mode and Scholar models are studied by numerical simulation approach. The viscous-inviscid interacting flowfield and combustion of a hydrocarbon-air (C2H4-air) mixture in supersonic flow paths are modeled through thermo-physic and spectral optical properties. Fields of chemical species concentrations, pressure, and temperature are calculated by two-dimensional (axisymmetric) computational model based on unsteady governing equations including Navier-Stokes equations, energy conservation and diffusion equations together with system of chemical kinetic equations. Based on them, the fields of spectral optical properties and thermal radiation of the gas mixture within a scramjet combustor are computed. It has been revealed that some regimes of combustion can be unsteady, and the radiative heat flux contributes significantly to the total heating of the combustor wall. Comparison of radiation heat fluxes for different initial conditions are presented. Three dimensional numerical simulations of a dual-mode scramjet via an unstructured-grid approach are also performed for non-reacting perfect gas for the purposes of verifying a developed numerical simulation capability. It is shown that this model satisfactory repeats experimental data for "cold" flow.

关键词： Optical properties

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