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SSRN 2022年

作者： Jin, Chihao Okano, Yasunori Minakuchi, Hisashi Dost, Sadik Department of Materials Engineering Science Osaka University 1-3 Machikaneyama Osaka Toyonaka560-8531 Japan Mechanical Engineering Program School of Engineering University of the Ryukyus 1 Senbaru Nishihara Okinawa903-0213 Japan Crystal Growth Laboratory University of Victoria VictoriaBCV8W 3P6 Canada

Numerical simulations of thermo-solutal Marangoni convection in a floating half SiGe zone with radiation effects under zero gravity have been carried out. In this system, thermal and solutal Marangoni flows develop along the free surface either in the same direction or opposite directions depending on the directions of thermal and solutal gradients. In this simplified model of a liquid bridge, the ambient temperature is kept constant, and the radiation effects of heat loss and heat gain are considered as the dominant heat transfer from the ambience. By investigating the radiation effects at unequal or equal (MaC, MaT) values, the transition mode maps mainly based on the concentration distribution with respect to Marangoni number ratio (Rσ =MaT/MaT) and ambient temperature (Ta) have been proposed. The maps show the main concentration structures and potential transition tendencies at various Ta values. The opposite thermo-solutal Marangoni flows give rise to more complex structures than those of the same-direction flows. Both heat loss and heat gain have a significant effect on alteration or destabilizing of the concentration distribution. To some extent, the heat loss in the opposite-direction flow has a stabilizing effect on the azimuthal wave pattern at a lower or higher Rσ © 2022, The Authors. All rights reserved.

关键词： Radiation effects

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Experimental Investigation and Validation of Strength-Based Topology and Fiber Path Optimization in Continuous Fiber Reinforced Composites

SSRN

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SSRN 2024年

作者： Yap, Timothy He, Zhelong Wang, Zhichao Tamijani, Ali Tehrani, Mehran Department of Structural Engineering University of California San Diego La Jolla CA92093 United States Program in Materials Science and Engineering University of California San Diego La Jolla CA92093 United States State-Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China

Material Extrusion (ME) based Fused Filament Fabrication (FFF) excels with Continuous Carbon Fiber (CCF) reinforced filaments. This Additive Manufacturing (AM) technology allows for intricate parts to be made with topologies where fibers are aligned in directions that optimize strength and stiffness, albeit within certain manufacturing limitations. This study investigates the performance of strength-based optimization methods applied to two benchmark structural domains and loading scenarios. Two methods were used to concurrently design the topology and fiber paths: shape optimization using the level-set method, and topology optimization using both density-based Solid Orthotropic Material with Penalization (SOMP) and level-set methods. CCF filaments were printed to follow the post-processed fiber paths, and a discontinuous fiber reinforced filament was used to fill in the remaining gaps. The parts were then compression molded for full consolidation, followed by testing for their stiffness and strengths (failure loads). Finite Element Analysis (FEA) was used to simulate the stiffness and failures of the tested parts. FEA predicted stiffnesses, locations of failure, and failure loads with reasonable accuracy (less than 10% difference with experiment). A micro-computed tomography (µCT) examination of failed coupons showed that fiber flow (deviation from printed paths) during compression molding was a major source of error. In one case, a progressive damage failure model performed more accurately than a linear static simulation. Finally, comparing designs optimized for stiffness versus strength showed premature failures due to stress concentrations in stiffness-optimized designs. This study underscores the critical need for integrating proper optimization strategy with realistic AM constraints to enhance the performance and reliability of CFF reinforced AM parts. © 2024, The Authors. All rights reserved.

关键词： Finite element method

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Ultrafast laser cleaning of daguerreotypes

Ultrafast laser cleaning of daguerreotypes

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2010 MRS Fall Meeting

作者： Abere, Michael J. Murphy, Ryan D. Jackson, Bianca Mourou, Gerard Menu, Michel Mansfield, John Yalisove, Steven M. Applied Physics Program University of Michigan Ann Arbor MI United States Materials Science and Engineering University of Michigan Ann Arbor MI United States Institut de Lumière Extrême ENSTA Paris France Centre de Recherche et de Restauration des Musées du France Paris France Center for Solar and Thermal Energy Conversion University of Michigan Ann Arbor MI United States

ISBN: (纸本)9781605112961

An ultrafast laser irradiation method for the removal of corrosion from Daguerreotypes without detrimentally affecting image quality has been developed. Corrosion products such as silver oxide and silver sulfide may be removed by chemical cleaning but these reactions are hard to control and are often damaging to the underlying silver, ruining the image. The Ti:Sapphire 150 fs laser pulses used in this study are focused to a beam diameter of 60 μm and are normally incident to the Daguerreotype. It was found that the corrosion layer has a lower material removal threshold than silver allowing for removal of corrosion with minimal removal of vital information contained in the silver substrate. © 2011 materials Research Society.

关键词： Sulfur compounds

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Hypostatic jammed packings of frictionless nonspherical particles

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Physical Review E 2018年第1期97卷 012909-012909页

作者： Kyle VanderWerf Weiwei Jin Mark D. Shattuck Corey S. O'Hern Department of Physics Yale University New Haven Connecticut 06520 USA Department of Mechanics and Engineering Science Peking University Beijing 100871 China Department of Mechanical Engineering & Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA

We perform computational studies of static packings of a variety of nonspherical particles including circulo-lines, circulo-polygons, ellipses, asymmetric dimers, dumbbells, and others to determine which shapes form packings with fewer contacts than degrees of freedom (hypostatic packings) and which have equal numbers of contacts and degrees of freedom (isostatic packings), and to understand why hypostatic packings of nonspherical particles can be mechanically stable despite having fewer contacts than that predicted from naive constraint counting. To generate highly accurate force- and torque-balanced packings of circulo-lines and cir-polygons, we developed an interparticle potential that gives continuous forces and torques as a function of the particle coordinates. We show that the packing fraction and coordination number at jamming onset obey a masterlike form for all of the nonspherical particle packings we studied when plotted versus the particle asphericity A, which is proportional to the ratio of the squared perimeter to the area of the particle. Further, the eigenvalue spectra of the dynamical matrix for packings of different particle shapes collapse when plotted at the same A. For hypostatic packings of nonspherical particles, we verify that the number of “quartic” modes along which the potential energy increases as the fourth power of the perturbation amplitude matches the number of missing contacts relative to the isostatic value. We show that the fourth derivatives of the total potential energy in the directions of the quartic modes remain nonzero as the pressure of the packings is decreased to zero. In addition, we calculate the principal curvatures of the inequality constraints for each contact in circulo-line packings and identify specific types of contacts with inequality constraints that possess convex curvature. These contacts can constrain multiple degrees of freedom and allow hypostatic packings of nonspherical particles to be mechanically stable.

关键词： Granular materials Granular packing Jamming

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Ab initio phonon transport across grain boundaries in graphene using machine learning based on small dataset

arXiv

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arXiv 2019年

作者： Hashemi, Amirreza Guo, Ruiqiang Esfarjani, Keivan Lee, Sangyeop Computational Modeling and Simulation Program University of Pittsburgh PittsburghPA15261 United States Department of Mechanical Engineering and Materials Science University of Pittsburgh PittsburghPA15261 United States Department of Mechanical and Aerospace Engineering University of Virginia CharlottesvilleVA22904 United States Department of Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Department of Physics University of Virginia CharlottesvilleVA22904 United States Department of Physics and Astronomy University of Pittsburgh PittsburghPA15261 United States

Establishing the structure-property relationship for grain boundaries (GBs) is critical for developing next generation functional materials, but has been severely hampered due to its extremely large configurational space. Atomistic simulations with low computational cost and high predictive power are strongly desirable, but the conventional simulations using empirical interatomic potentials and density functional theory suffer from the lack of predictive power and high computational cost, respectively. A machine learning interatomic potential (MLIP) recently emerged but often requires an extensive size of the training dataset, making it a less feasible approach. Here we demonstrate that an MLIP trained with a rationally designed small training dataset can predict thermal transport across GBs in graphene with ab initio accuracy at an affordable computational cost. In particular, we employed a rational approach based on the structural unit model to find a small set of GBs that can represent the entire configurational space and thus can serve as a cost-effective training dataset for the MLIP. Only 5 GBs were found to be enough to represent the entire configurational space of graphene GBs. Using the atomistic Green's function approach and the MLIP, we revealed that the structure-thermal resistance relation in graphene does not follow the common understanding that large dislocation density causes larger thermal resistance. In fact, thermal resistance is nearly independent of dislocation density at room temperature and is higher when the dislocation density is small at sub-room temperature. We explain this intriguing behavior with the buckling near a GB causing a strong scattering of flexural phonon modes. Our work shows that a machine learning technique combined with conventional wisdom (e.g., structural unit model) can extend the recent success of ab initio thermal transport simulation, which has been mostly limited to single crystals, to complex yet practically importa

关键词： Grain boundaries

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Highly efficient Bi2O2CO3 coupled with interlayer expanded MoS2 photocatalyst with oxygen vacancy mediated direct Z-scheme charge transfer for photocatalytic degradation of organic pollutant

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Journal of Environmental Chemical engineering 2023年第6期11卷

作者： Lai, Magdeline Tze Leng Yang, Thomas Chung Kuang Lai, Chin Wei Chen, Chia-Yun Johan, Mohd Rafie Lee, Kian Mun Juan, Joon Ching Nanotechnology & Catalysis Research Centre Institute for Advanced Studies Universiti Malaya Kuala Lumpur50603 Malaysia Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan Research Center National Cheng Kung University Tainan70101 Taiwan Faculty of Engineering Technology and Built Environment UCSI University Cheras Kuala Lumpur56000 Malaysia Department of Chemistry Faculty of Science Universiti Malaya Kuala Lumpur50603 Malaysia

The development of photocatalysts to degrade organic pollutants from wastewater under visible light has attracted a lot of interest. Herein, a series of Bi2O2CO3 (BOC) coupled with interlayer expanded MoS2 (IEM) photocatalysts were synthesized via a facile two-pot hydrothermal technique. Among all the samples, 5 % of BOC with IEM (5 % BOC-IEM) nanocomposite exhibited the highest photodegradation with 94 % (4.97 × 10−2 min−1) for Methylene Blue (MB) dye removal under 1 W LED visible light. The performance by 5 % BOC-IEM is 1.5 times and 13.4 times higher than the parent IEM and BOC, respectively. Increased photocurrent density, lowest PL intensity, and smallest EIS arc further evidenced the lowered charge carrier's recombination rate in the optimized 5 % BOC-IEM heterostructure. Moreover, the outstanding photocatalytic performance of 5% BOC-IEM was due to the presence of oxygen vacancies, enhanced light absorption, and improved migration and separation of charge carriers. An Ohmic contact formed on the interfaces of BOC and IEM boosts the Z-scheme charge transfer mechanism, which greatly improves the photocatalytic activity of 5% BOC-IEM. © 2023 Elsevier Ltd

关键词： Molybdenum compounds

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Magnesium vapor reduction of structured silica for lithium ion battery applications

Magnesium vapor reduction of structured silica for lithium i...

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2013 MRS Fall Meeting

作者： Cook, Rob Schrandt, Matthew Kolla, Praveen Rhine, Wendell Koodali, Ranjit Smirnova, Alevtina Zyvex Technologies Rapid City SD 57701 United States Materials Engineering and Science Program South Dakota School of Mines and Technology Rapid City SD 57701 United States Aspen Aerogels Northborough MA 01532 United States University of South Dakota Vermillion SD 57069 United States Department of Chemistry and Applied Biological Sciences South Dakota School of Mines and Technology Rapid City SD 57701 United States

Three types of silica materials with different morphology, specifically SiO2 hollow microspheres, mesoporous silica, and silica aerogel were tested as potential precursors for synthesis of silicon nano- and meso-structures that resemble the original morphology of the precursors. In the optimized magnesium thermal reduction process, magnesium vapor was delivered to silica surface through a stainless steel mesh placed on top of a zirconia boat filled with silica precursor. This approach allowed for better control of silicon nanostructure formation by minimizing reaction by-products that can affect performance of lithium ion battery anode. Material morphological properties of the reduced silica precursors are discussed in terms of X-ray diffraction, BET, BJH pore size distribution, Raman spectroscopy, and TGA. Copyright © materials Research Society 2014.

关键词： Magnesium

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Subwavelength-engineered Antislot Photonic Crystals in a Silicon Photonics Foundry for On-chip Communications

Subwavelength-engineered Antislot Photonic Crystals in a Sil...

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2024 Conference on Lasers and Electro-Optics, CLEO 2024

作者： Arnold, Kellen P. Allen, Joshua A. Halimi, Sami I. Ryder, Landen D. Afzal, Francis O. Bian, Yusheng Aboketaf, Abdelsalam Hirokawa, Takako Dezfulian, Kevin Rakowski, Michal Augur, Rod Nummy, Karen Weiss, Sharon M. Interdisciplinary Materials Science Program Vanderbilt University 2201 West End Ave NashvilleTN37235 United States Department of Electrical and Computer Engineering Vanderbilt University 2201 West End Ave NashvilleTN37235 United States NASA Goddard Space Flight Center Code 561 GreenbeltMD20771 United States GlobalFoundries 400 Stone Break Rd. Ext. MaltaNY12020 United States

ISBN: (纸本)9781957171395

We report scalable foundry fabrication and characterization of photonic crystal nanobeam waveguides incorporating subwavelength-scale dielectric antislot unit cells. This work enables enhanced light-matter interaction and three-fold improvement in VπL when incorporated in Mach-Zehnder modulators. CLEO 2024 © Optica Publishing Group 2024 © 2024 The Author(s)

关键词： Mach-Zehnder interferometers

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Subwavelength-engineered Antislot Photonic Crystals in a Silicon Photonics Foundry for On-chip Communications

Subwavelength-engineered Antislot Photonic Crystals in a Sil...

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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

关键词： Silicon photonics

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Electron microscopy observations of the diversity of Ryugu organic matter and its relationship to minerals at the micro- to nano-scale

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Meteoritics and Planetary science 2024年第8期59卷 2023-2043页

作者： Stroud, Rhonda M. Barosch, Jens Bonal, Lydie Burgess, Katherine Cody, George D. De Gregorio, Bradley T. Daly, Luke Dartois, Emmanuel Dobrică, Elena Duprat, Jean Engrand, Cecile Harries, Dennis Hashiguchi, Minako Ishii, Hope Kebukawa, Yoko Kilcoyne, A. David Langenhorst, Falko Lee, Martin R. Nittler, Larry R. Quirico, Eric Okumura, Taiga Remusat, Laurent Sandford, Scott Yabuta, Hikaru Abe, Masanao Abreu, Neyda M. Bagot, Paul A. J. Beck, Pierre Bejach, Laure Bland, Phil A. Bridges, John C. Cymes, Brittany A. Dazzi, Alexandre de la Peña, Francisco Deniset-Besseau, Ariane Enju, Satomi Enokido, Yuma Frank, David R. Gray, Jennifer Haruta, Mitsutaka Hata, Satoshi Hicks, Leon Igami, Yohei Jacob, Damien Kamide, Kanami Komatsu, Mutsumi Laforet, Sylvain Leroux, Hugues Le Guillou, Corentin Martins, Zita Marinova, Maya Martinez, James Mathurin, Jérémie Matsumoto, Megumi Matsumoto, Toru Matsuno, Junya McFadzean, Samuel Michikami, Tatsuhiro Mitsukawa, Itaru Miyake, Akira Miyahara, Masaaki Miyazaki, Akiko Montagnac, Gilles Mostefaoui, Smail Nakamura, Tomoki Nakato, Aiko Naraoka, Hiroshi Nakauchi, Yusuke Nakazawa, Satoru Nishimura, Masahiro Noguchi, Takaaki Ohtaki, Kenta Ohigashi, Takuji Okada, Tatsuaki Okumura, Shota Okazaki, Ryuji Phan, Thi H. V. Rebois, Rolando Sakamoto, Kanako Saiki, Takanao Saito, Hikaru Seto, Yusuke Shigenaka, Miho Smith, William Suga, Hiroki Sun, Mingqi Tachibana, Shogo Takahashi, Yoshio Takeichi, Yasuo Takeuchi, Akihisa Takigawa, Aki Tamenori, Yusuke Tanaka, Satoshi Terui, Fuyuto Thompson, Michelle S. Tomioka, Naotaka Tsuchiyama, Akira Tsuda, Yuichi Uesugi, Kentaro Uesugi, Masayuki Usui, Tomohiro Verdier-Paoletti, Maximilien Wakabayashi, Daisuke Watanabe, Sei-ichiro Yada, Toru Yamashita, Shohei Yasutake, Masahiro Yogata, Kasumi Yoshikawa, Makoto Yurimoto, Hisayoshi Zanetta, Pierre-M. Zega, Thomas Zolensky, Michael E. School of Earth and Space Exploration Arizona State University Materials Science and Technology Division US Naval Research Laboratory Earth and Planets Laboratory Carnegie Institution for Science Institut de Planétologie et d'Astrophysique Université Grenoble Alpes School of Geographical and Earth Sciences University of Glasgow Australian Centre for Microscopy and Microanalysis University of Sydney Department of Materials University of Oxford Institut des Sciences Moléculaires d'Orsay Université Paris-Saclay Centre National de la Recherche Scientifique Hawai‘i Institute of Geophysics and Planetology the University of Hawai‘i at Mānoa Institut de Mineralogie Physique des Materiaux et Cosmochimie Museum National d'Histoire Naturelle Centre National de la Recherche Scientifique UMR 7590 Sorbonne Université Laboratoire de Physique des 2 Infinis Irène Joliot-Curie Centre National de la Recherche Scientifique Université Paris-Saclay Luxembourg Institute of Science and Technology European Space Resources Innovation Centre Graduate School of Environmental Studies Nagoya University Department of Chemistry and Life Science Yokohama National University Institute of Geoscience Friedrich Schiller University Jena Department of Earth and Planetary Science The University of Tokyo NASA Ames Research Center Department of Earth and Planetary Systems Science Hiroshima University Institute of Space and Astronautical Science Japan Aerospace Exploration Agency The Graduate University for Advanced Studies SOKENDAI Langley Research Center NASA School of Earth and Planetary Sciences Curtin University School of Physics and Astronomy University of Leicester Institut Chimie Physique Centre National de la Recherche Scientifique Université Paris-Saclay Université de Lille CNRS INRAE Centrale Lille Université Artois FR 2638-IMEC-Institut Michel-Eugène Chevreul Department of Mathematics Physics and Earth Science Ehime University Department of Earth Science Tohoku University Materials Characterization Lab Th

Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range of morphologies, elemental compositions, and carbon functional chemistries consistent with those of carbonaceous chondrites that have experienced low-temperature aqueous alteration. Both nanoglobules and diffuse organic matter are abundant. Non-globular organic particles are also present, and including some that contain nanodiamond clusters. Diffuse organic matter is finely distributed in and around phyllosilicates, forms coatings on other minerals, and is also preserved in vesicles in secondary minerals such as carbonate and pyrrhotite. The average elemental compositions determined by energy-dispersive spectroscopy of extracted, demineralized insoluble organic matter samples A0107 and C0106 are C₁₀₀N₃O₉S₁ and C₁₀₀N₃O₇S₁, respectively, with the difference in O/C slightly outside the difference in the standard error of the mean. The functional chemistry of the nanoglobules varies from mostly aromatic C=C to mixtures of aromatic C=C, ketone C=O, aliphatic (CH_n), and carboxyl (COOH) groups. Diffuse organic matter associated with phyllosilicates has variable aromatic C, ketone and carboxyl groups, and some localized aliphatics, but is dominated by molecular carbonate (CO₃) absorption, comparable to prior observations of clay-bound organic matter in CI meteorites. © 2024 The Authors. Meteoritics & Planetary science published by Wiley Periodicals LLC on behalf of The Meteoritical Society.

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