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26th Annual Conference on Recent Advances in Flame Retardancy of Polymeric materials, Flame 2015

作者： Yang, Kai Guo, Yichen Endoh, Maya Ramasamy, Radha P. Gentleman, Molly M. Butcher, Thomas A. Rafailovich, Miriam H. Charnoff, Russell Soni, Arun Choi, David Dept. of Materials Science and Engineering SUSB Stony BrookNY11795 United States Garcia High School Research Program SUSB Stony BrookNY11795 United States

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Shape optimization of an airfoil in ground effect for application to WIG craft 53

Shape optimization of an airfoil in ground effect for applic...

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53rd AIAA Aerospace sciences Meeting, 2015

作者： He, Yilei Qu, Qiulin Agarwal, Ramesh K. Dept. of Mechanical Engineering & Materials Science Washington University in St. Louis St. LouisMO63130 United States Institute of Fluid Mechanics Beijing Institute of Aeronautics and Astronautics Beijing China

ISBN: (数字)9781624103438

ISBN: (纸本)9781624103438

This paper employs a multi-objective genetic algorithm (MOGA) to optimize the shape of a widely used wing in ground (WIG) aircraft airfoil NACA 4412 to improve its lift and drag characteristics, in particular to achieve two objectives that is to increase its lift and its lift to drag ratio. The commercial software ANSYS FLUENT is employed to calculate the flow field on an adaptive structured mesh generated by ANSYS ICEM software using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one equation Spalart-Allmaras (SA) model. The results show significant improvement in both the lift coefficient and lift to drag ratio of the optimized airfoil compared to the original NACA 4412 airfoil. It is demonstrated that the performance of a wing in ground (WIG) aircraft can be improved by using the optimized airfoil. © 2015 by Yilei He, Qiulin Qu and Ramesh K. Agarwal.

关键词： Drag

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Optimal CMB lensing reconstruction and parameter estimation with SPTpol data

arXiv

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arXiv 2020年

作者： Millea, Marius Daley, C.M. Chou, T.-L. Anderes, E. Ade, P.A.R. Anderson, A.J. Austermann, J.E. Avva, J.S. Beall, J.A. Bender, A.N. Benson, B.A. Bianchini, F. Bleem, L.E. Carlstrom, J.E. Chang, C.L. Chaubal, P. Chiang, H.C. Citron, R. Corbett Moran, C. Crawford, T.M. Crites, A.T. de Haan, T. Dobbs, M.A. Everett, W. Gallicchio, J. George, E.M. Goeckner-Wald, N. Guns, S. Gupta, N. Halverson, N.W. Henning, J.W. Hilton, G.C. Holder, G.P. Holzapfel, W.L. Hrubes, J.D. Huang, N. Hubmayr, J. Irwin, K.D. Knox, L. Lee, A.T. Li, D. Lowitz, A. McMahon, J.J. Meyer, S.S. Mocanu, L.M. Montgomery, J. Natoli, T. Nibarger, J.P. Noble, G. Novosad, V. Omori, Y. Padin, S. Patil, S. Pryke, C. Reichardt, C.L. Ruhl, J.E. Saliwanchik, B.R. Schaffer, K.K. Sievers, C. Smecher, G. Stark, A.A. Thorne, B. Tucker, C. Veach, T. Vieira, J.D. Wang, G. Whitehorn, N. Wu, W.L.K. Yefremenko, V. Department of Physics University of California BerkeleyCA94720 United States Astronomy Department University of Illinois at Urbana-Champaign 1002 W. Green Street UrbanaIL61801 United States Kavli Institute for Cosmological Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Physics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Statistics University of California One Shields Avenue DavisCA95616 United States Cardiff University CardiffCF10 3XQ United Kingdom Fermi National Accelerator Laboratory MS209 P.O. Box 500 BataviaIL60510 United States NIST Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Department of Physics University of Colorado BoulderCO80309 United States High Energy Physics Division Argonne National Laboratory 9700 S. Cass Avenue ArgonneIL60439 United States Department of Astronomy and Astrophysics University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States School of Physics University of Melbourne ParkvilleVIC3010 Australia Enrico Fermi Institute University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Department of Physics McGill University 3600 Rue University MontrealQCH3A 2T8 Canada School of Mathematics Statistics & Computer Science University of KwaZulu-Natal Durban South Africa University of Chicago 5640 South Ellis Avenue ChicagoIL60637 United States Jet Propulsion Laboratory PasadenaCA91109 United States Dunlap Institute for Astronomy & Astrophysics University of Toronto 50 St George St TorontoONM5S 3H4 Canada Department of Astronomy & Astrophysics University of Toronto 50 St George St TorontoONM5S 3H4 Canada Physics Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Canadian Institute for Advanced Research CIFAR Program in Gravity Extreme Universe TorontoONM5G 1Z8 Canada Department of Astrophysical and Pla

We perform the first simultaneous Bayesian parameter inference and optimal reconstruction of the gravitational lensing of the cosmic microwave background (CMB), using 100 deg2 of polarization observations from the SPTpol receiver on the South Pole Telescope. These data reach noise levels as low as 5.8 µK-arcmin in polarization, which are low enough that the typically used quadratic estimator (QE) technique for analyzing CMB lensing is significantly sub-optimal. Conversely, the Bayesian procedure extracts all lensing information from the data and is optimal at any noise level. We infer the amplitude of the gravitational lensing potential to be Aφ = 0.949 ±0.122 using the Bayesian pipeline, consistent with our QE pipeline result, but with 17% smaller error bars. The Bayesian analysis also provides a simple way to account for systematic uncertainties, performing a similar job as frequentist "bias hardening," and reducing the systematic uncertainty on Aφ due to polarization calibration from almost half of the statistical error to effectively zero. Finally, we jointly constrain Aφ along with AL, the amplitude of lensing-like effects on the CMB power spectra, demonstrating that the Bayesian method can be used to easily infer parameters both from an optimal lensing reconstruction and from the delensed CMB, while exactly accounting for the correlation between the two. These results demonstrate the feasibility of the Bayesian approach on real data, and pave the way for future analysis of deep CMB polarization measurements with SPT-3G, Simons Observatory, and CMB-S4, where improvements relative to the QE can reach 1.5 times tighter constraints on Aφ and 7 times lower effective lensing reconstruction noise. Copyright © 2020, The Authors. All rights reserved.

关键词： Cosmology

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On the Convergence Rate of a Distributed Augmented Lagrangian Optimization Algorithm

On the Convergence Rate of a Distributed Augmented Lagrangia...

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American Control Conference

作者： Nikolaos Chatzipanagiotis Michael M. Zavlanos Dept. of Mechanical Engineering and Materials Science Duke University Durham NC 27708 USA

ISBN: (纸本)9781479917730

We consider the Accelerated Distributed Augmented Lagrangians (ADAL) algorithm, a distributed optimization algorithm that was recently developed by the authors to address problems that involve multiple agents optimizing a separable convex objective function subject to convex local constraints and linear coupling constraints. Optimization using augmented Lagrangians (AL) combines low computational complexity with fast convergence speeds due to the regularization terms included in the AL. However, decentralized methods that employ ALs are few, as decomposition of ALs is a particularly challenging task. ADAL is a primal-dual iterative scheme where at every iteration the agents locally optimize a novel separable approximation of the AL and then appropriately update their primal and dual variables, in a way that ensures convergence to their respective optimal sets. In this paper, we prove that ADAL has a worst-case O(1/k) convergence rate, where k denotes the number of iterations. The convergence rate is established in an ergodic sense, i.e., it refers to the ergodic average of the generated sequences of primal variables up to iteration k.

关键词： Optimization algorithms Converge iterative methods Distribute complexity classes

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Influence of zirconia shot peening treatment on high-cycle fatigue properties of Ti-6Al-4V

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Zairyo/Journal of the Society of materials science, Japan 2016年第9期65卷 679-686页

作者： Masaki, Kiyotaka Yonakuni, Yuki Hisamori, Noriyuki Suga, Yuichiro Kobayashi, Yuji Gowa, Daisuke Dept. of Mech. Eng. Systems Okinawa College National Institute of Technology Henoko Nago905-2192 Japan Nagaoka University of Technology Kamitomioka Nagaoka940-2188 Japan Dept. of Eng. and App. Sci. Sophia Univ. Chiyoda-ku Tokyo102-8554 Japan Master's Program in Science and Technology Mechanical Engineering. Sophia Univ. Chiyoda-ku Tokyo102-8554 Japan SINTOKOGIO Ltd Ohgi-cho Toyokawa441-1205 Japan

Rotating bending loading and axial loading fatigue tests were conducted to investigate the effect of zirconia shot peening on fatigue properties of Ti-6Al-4V ELI alloy. Specimen was treated in three different shot peening conditions. As a result of the rotating bending fatigue tests, the fatigue lives of shot peened specimen were longer life than non-peened specimen. Fish eyes were observed in the fracture surface of the most shot peened specimen. And there was the facet of α-Ti or the fine granular region near the crack initiation site of the fish eye. And then, fracture morphology of shot peened specimens is different by peening conditions. From the result of axial loading fatigue tests, it becomes obvious that the facet of α-Ti was formed by action of tensile stress over 500MPa without compressive stress and that the fine granular region was formed by action of compressive stress. These results suggested that low level tensile residual stress existed at subsurface near the surface of the SP treated specimen, and the residual stress distribution decided on internal crack origin type between the facet of α-Ti or the fine granular region. © 2016 The Society of materials science, Japan.

关键词： Aluminum alloys

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Corrigendum to “Biocorrosion behavior of biodegradable nanocomposite fibers coated layer-by-layer on AM50 magnesium implant” [Mater. Sci. Eng. C 58 (2016) 1232–1241]

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materials science and engineering: C 2016年 61卷 1029-1029页

作者： Abdalla Abdal-hay Anwarul Hasan Yu-Kyoung Kim Min-Ho Lee Abdel Salam Hamdy Khalil Abdelrazek Khalil Dept. of Engineering Materials and Mechanical Design Faculty of Engineering South Valley University Qena Egypt Dept. of Mechanical and Biomedical Engineering American University of Beirut Beirut Lebanon Dept of Mechanical and Industrial Engineering College of Engineering Qatar University P.O. Box 2713 Doha Qatar Dept of Dental Biomaterials and Institute of Biodegradable Materials Institute of Oral Bioscience and School of Dentistry (plus BK21 program) Chonbuk National University Jeon Ju 561-756 South Korea Dept. of Manufacturing and Industrial Engineering College of Engineering and Computer Science University of Texas Rio Grande Valley 1201West University Dr. Edinburg TX 78541-2999 USA Dept. of Mechanical Engineering College of Engineering King Saud University P.O. Box 800 Riyadh 11421 Saudi Arabia Dept. of Mechanical Engineering Faculty of Energy Engineering Aswan University Aswan Egypt

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Strontium vanadate: An ultra-low work function electron emission material

Strontium vanadate: An ultra-low work function electron emis...

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International Conference on Vacuum Electronics

作者： Ryan M. Jacobs Dane Morgan John H. Booske Materials Science Program Madison WI USA Materials Science and Engineering Madison WI USA Electrical and Computer Engineering Dept. University of Wisconsin-Madison Madison WI USA

Strontium vanadate, SrVO 3 , is a transition metal perovskite oxide with a low predicted work function of 1.79 eV using Density Functional Theory. Alloying SrVO 3 with Ba resulted in Ba segregation to the emitting surface, producing an ultra-low work function of only 1.07 eV. This Ba-enriched emitting surface is predicted to be very long-lived compared to Ba-impregnated W and scandate cathodes.

关键词： Barium Cathodes Electron emission Discrete Fourier transforms Surface contamination Slabs

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Experimental and Numerical Analysis of Microstructure Evolution during Linear Friction Welding of Ti6Al4V

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Procedia Manufacturing 2015年 1卷 429-441页

作者： Gianluca Buffa Davide Campanella Marco Cammalleri Antonino Ducato Antonello Astarita Antonino Squillace Sergio Esposito Livan Fratini Dept. of Chemical Management Computer Science and Mechanical Engineering University of Palermo Italy Dept. of Chemical Materials and Industrial Production Engineering University of Naples Italy Manufacturing and Assembly Research and Development Alenia Aermacchi S.p.A. Italy

Linear Friction Welding (LFW) is a solid state welding process used to joint bulk components. In the paper, an experimental and numerical study on LFW of Ti6Al4V titanium alloy is presented. A laboratory designed LFW machine has been used to weld the specimens with different contact pressure and oscillation frequency. The joint microstructure has been experimentally observed with SEM and EDS. A dedicated numerical model, able to predict temperature, strain and strain rate distribution as well as the phase volume fraction evolution, has been utilized to predict the final microstructure in the welded parts. It was found that complete transformation of the alpha phase into beta phase occurs during the process. After cool down, martensitic structure is obtained at the core of the weld due to high temperatures reached during the process and high cooling rates occurring at the end of the reciprocating motion. Microhardness measurements confirmed increased hardness in the Weld Zone with respect to the parent material

关键词： LFW Ti-6Al-4V Phase transformation FEM.

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Surface effects on martensitic phase transformation, a simultaneous in situ xrd and dilatometry study

Surface effects on martensitic phase transformation, a simul...

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International Conference on Solid-Solid Phase Transformations in Inorganic materials 2015, PTM 2015

作者： Faria, Guilherme Escobar, Julian Ramirez, Antonio J. Brazilian Nanotecnology National Laboratory Caixa Postal 6192 Campinas-SP Brazil Mechanical Engineering School State University of Campinas 200 Rua Mendeleyev Campinas-SP Brazil Dept. of Materials Science and Engineering Ohio State University 1248 Arthur E. Adams Drive ColumbusOH United States

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Developments of Bi-Sb-Cu alloys as a high-temperature Pb-free solder

Developments of Bi-Sb-Cu alloys as a high-temperature Pb-fre...

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Electronic Components and Technology Conference (ECTC)

作者： Junghyun Cho Sandeep Mallampati Harry Schoeller Liang Yin David Shaddock Dept. of Mechanical Engineering & Materials Science and Engineering Program Binghamton University (State University of New York) Binghamton NY Universal Instruments Corporation Conklin NY GE Global Research Niskayuna NY

Predominant high melting point solders for high temperature electronics (operating temperatures from 200 to 250°C) are Pb-based but these are hazardous to environment. In our previous study, we have shown the alloy design and characterization of the `new' bismuth (Bi) - based solder alloys; 78Bi-14Cu-8Sn, 70Bi-20Sb-10Cu. It was shown that these solders have strong reactivities with Ni (forming intermetallic phases containing Bi or Sb), and with Cu (forming Cu 2 Sb, Cu 4 Sb). Of the two alloys, 70Bi-20Sb-10Cu exhibited the potential for forming good bonding with both Ni and Cu surfaces. The aim of this study was to establish the microstructure - property relationship by exploring the microstructure features involving solid solution behavior between Bi and Sb and the interfacial intermetallic layers. For this, the sandwiched coupons were fabricated using high Bi solders to bond the silicon die having Ti/Ni/Au backside metallization to the Cu substrate. These sandwich samples were then tested for thermal conductivity, die shear testing and liquid thermal shock between -50°C and 150°C. The current alloy matched the performance of high Pb alloys in thermal and die shear testing. In particular, the role of interfacial intermetallic layer on the reliability of the solder joint was investigated. From the findings of this study, Bi solder alloys showed some potential as an alternative to high-temperature Pb-free solders.

关键词： Bismuth Thermal conductivity Conductivity Nickel Joints Microstructure

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