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SAMPE 2019 Conference and Exhibition

作者： Kirmse, Sebastian Kim, Keonhyeong Ranabhat, Bikash Hsiao, Kuang-Ting College of Engineering University of South Alabama MobileAL36688 United States Systems Engineering Program University of South Alabama MobileAL36688 United States Department of Mechanical Engineering University of South Alabama MobileAL36688 United States

ISBN: (纸本)9781934551301

In this study, unidirectional carbon fiber prepregs that contain long carbon nanofiber (CNF) z-threads as a through-thickness (z-directional) reinforcement were manufactured. The CNF z-threads are long enough to thread through multiple carbon fiber (CF) arrays, which creates a multi-scale CNF/CF/resin-composite. The CNF z-threaded prepregs were manufactured using an electric-field aligned flow-transferring process. It was hypothesized that the CNF z-threads with the zig-zag threading pattern reinforces the interlaminar and intralaminar regions of the CFRP laminate thus improve the compressive strength by reducing the chance of carbon fiber buckling. Compressive testing was performed per modified version of ASTM D695 (i.e., SACMA SRM 1R-94) to evaluate the compressive strength of the CNF z-threaded CFRP (ZT-CFRP) laminates. The samples were manufactured using AS4 carbon fibers, EPON 862/Epikure-W resin and a 1wt% CNF content. ZT-CFRP testing results were compared with unaligned CNF-modified CFRP (UA-CFRP) and unmodified CFRP samples to investigate the impact of the CNF z-threads on the compressive strength. Results showed an increase of ~15% for the compressive strength of ZT-CFRPs, whereas the UA-CFRPs experienced a decrease of ~8% when compared to unmodified CFRPs. It was concluded that CNF/carbon fiber interlocking stops and delays crack growth, and helps to stabilize carbon fibers from further buckling. Copyright 2019 by Sebastian Kirmse et al. Published by Society for the Advancement of Material and Process engineering with permission.

关键词： Carbon nanofibers

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Unifying femtosecond and picosecond single-pulse magnetic switching in Gd-Fe-Co

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Physical Review B 2021年第10期103卷 104422-104422页

作者： F. Jakobs T. A. Ostler C.-H. Lambert Y. Yang S. Salahuddin R. B. Wilson J. Gorchon J. Bokor U. Atxitia Dahlem Center for Complex Quantum Systems and Fachbereich Physik Freie Universität Berlin 14195 Berlin Germany Département de Physique Universitè de Liége (B5) B-4000 Liége Belgium College of Business Technology and Engineering Sheffield Hallam University Howard Street Sheffield S1 1WB United Kingdom Department of Electrical Engineering and Computer Sciences University of California Berkeley California 94720 USA Department of Materials Science and Engineering University of California Berkeley California 94720 USA Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside California 92521 USA

Many questions are still open regarding the physical mechanisms behind the magnetic switching in Gd-Fe-Co alloys by single optical pulses. Phenomenological models suggest a femtosecond scale exchange relaxation between sublattice magnetization as the driving mechanism for switching. The recent observation of thermally induced switching in Gd-Fe-Co by using both several picosecond optical laser pulse as well as electric current pulses has questioned this previous understanding. This has raised the question of whether or not the same switching mechanics are acting at the femtosecond and picosecond scales. In this work, we aim at filling this gap in the understanding of the switching mechanisms behind thermal single-pulse switching. To that end, we have studied experimentally thermal single-pulse switching in Gd-Fe-Co alloys, for a wide range of system parameters, such as composition, laser power, and pulse duration. We provide a quantitative description of the switching dynamics using atomistic spin dynamics methods with excellent agreement between the model and our experiments across a wide range of parameters and timescales, ranging from femtoseconds to picoseconds. Furthermore, we find distinct element-specific damping parameters as a key ingredient for switching with long picosecond pulses and argue that switching with pulse durations as long as 15 ps is possible due to a low damping constant of Gd. Our findings can be easily extended to speed up dynamics in other contexts where ferrimagnetic Gd-Fe-Co alloys have been already demonstrated to show fast and energy-efficient processes, e.g., domain-wall motion in a track and spin-orbit torque switching in spintronics devices.

关键词： Demagnetization Magnetic interactions Magnetic order Magnetism Spin dynamics Ultrafast magnetic effects

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Radar Occupancy Prediction with Lidar Supervision while Preserving Long-Range Sensing and Penetrating Capabilities

arXiv

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arXiv 2021年

作者： Kung, Pou-Chun Wang, Chieh-Chih Lin, Wen-Chieh The Graduate Degree Program of Robotics National Yang Ming Chiao Tung University Hsinchu Taiwan The Department of Electrical and Computer Engineering National Yang Ming Chiao Tung University Taiwan The Mechanical and Mechatronics Systems Research Laboratories Industrial Technology Research Institute Hsinchu Taiwan The Department of Computer Science National Yang Ming Chiao Tung University Hsinchu Taiwan

Radar shows great potential for autonomous driving by accomplishing long-range sensing under diverse weather conditions. But radar is also a particularly challenging sensing modality due to the radar noises. Recent works have made enormous progress in classifying free and occupied spaces in radar images by leveraging lidar label supervision. However, there are still several unsolved issues. Firstly, the sensing distance of the results is limited by the sensing range of lidar. Secondly, the performance of the results is degenerated by lidar due to the physical sensing discrepancies between the two sensors. For example, some objects visible to lidar are invisible to radar, and some objects occluded in lidar scans are visible in radar images because of the radar's penetrating capability. These sensing differences cause false positive and penetrating capability degeneration, respectively. In this paper, we propose training data preprocessing and polar sliding window inference to solve the issues. The data preprocessing aims to reduce the effect caused by radar-invisible measurements in lidar scans. The polar sliding window inference aims to solve the limited sensing range issue by applying a near-range trained network to the long-range region. Instead of using common Cartesian representation, we propose to use polar representation to reduce the shape dissimilarity between long-range and near-range data. We find that extending a near-range trained network to long-range region inference in the polar space has 4.2 times better IoU than in Cartesian space. Besides, the polar sliding window inference can preserve the radar penetrating capability by changing the viewpoint of the inference region, which makes some occluded measurements seem non-occluded for a pretrained network. Copyright © 2021, The Authors. All rights reserved.

关键词： Optical radar

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An efficient two-dimensional heat transfer model for building envelopes

arXiv

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arXiv 2021年

作者： Berger, Julien Gasparin, Suelen Mazuroski, Walter Mendes, Nathan UMR 7356 CNRS La Rochelle Université CNRS La Rochelle17000 France Univ. Savoie Mont Blanc LOCIE Chambéry73000 France Thermal Systems Laboratory Mechanical Engineering Graduate Program Pontifícia Universidade Católica do Paraná Rua Imaculada Conceição 1155 CuritibaCEP: 80215-901 Brazil

A two-dimensional model is proposed for energy efficiency assessment through the simulation of heat transfer in building envelopes, considering the influence of the surrounding environment. The model is based on the Du Fort–Frankel approach that provides an explicit scheme with a relaxed stability condition. The model is first validated using an analytical solution and then compared to three other standard schemes. Results show that the proposed model offers a good compromise in terms of high accuracy and reduced computational efforts. Then, a more complex case study is investigated, considering non-uniform shading effects due to the neighboring buildings. In addition, the surface heat transfer coefficient varies with wind velocity and height, which imposes an addition non-uniform boundary condition. After showing the reliability of the model prediction, a comparison over almost 120 cities in France is carried out between the two- and the one-dimensional approaches of the current building simulation programs. Important discrepancies are observed for regions with high magnitudes of solar radiation and wind velocity. Last, a sensitivity analysis is carried out using a derivative-based approach. It enables to assess the variability of the solution according to the modeling of the two-dimensional boundary conditions. Moreover, the proposed model computes efficiently the solution and its sensitivity to the modeling of the urban environment. © 2021, CC BY-NC-SA.

关键词： Wind

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Examination of appearance conditions of singular stress fields at the vertex and along the side of interface in prismatic butt joint

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Journal of Japan Institute of Electronics Packaging 2020年第2期23卷 155-165页

作者： Miyazaki, Tatsujiro Sato, Keisuke Fujiwara, Takahiro Noda, Nao-Aki Sano, Yoshikazu Energy and Environment Program School of Engineering Faculty of Engineering University of the Ryukyus 1 Senbaru Nishihara-cho Nakagami-gun Okinawa903-0213 Japan Department of Mechanical Systems Engineering Graduate School of Engineering and Science University of the Ryukyus 1 Senbaru Nishihara-cho Nakagami-gun Okinawa903-0213 Japan Department of Mechanical Engineering Graduate School of Engineering Kyushu Institute of Technology 1-1 Sensui-cho Tobata-ku Kitakyushu-shi Fukuoka804-8550 Japan

In this paper, we discuss the bad pair condition causing a singular stress at a vertex of the interface in three dimensional (3D) prismatic butt joints in comparison with the bad pair condition along the side. 3D finite element (FE) eigenanalysis is applied to obtain the singular index. We found that the bad pair condition at a vertex is slightly different from the well-known 2D bad pair condition α(α- 2β) > 0 , which can be expressed using Dundurs' parameter (α, β). It should be noted that in most cases the bad pair can be judged by (α, β) except for some cases where the bad pair depends on the material combination even under the same (α, β). To clarify the difference, the bad pair conditions are compared on the (α, β) diagram. For convenience, a simple expression for a bad pair is proposed on the basis of the theoretical consideration, and the validity is confirmed numerically. We also confirm that the bad pair condition along the side of the interface can be expressed using Dundurs' parameter as α(α- 2β) > 0 . © 2020 Japan Institute of Electronics Packaging. All rights reserved.

关键词： Stresses

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Bridging particle deformability and collective response in soft solids

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Physical Review Materials 2021年第5期5卷 055605-055605页

作者： John D. Treado Dong Wang Arman Boromand Michael P. Murrell Mark D. Shattuck Corey S. O'Hern Department of Mechanical Engineering & Materials Science Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA Department of Biomedical Engineering Yale University New Haven Connecticut 06520 USA Department of Physics Yale University New Haven Connecticut 06520 USA Systems Biology Institute Yale University West Haven Connecticut 06516 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

Soft, amorphous solids such as tissues, foams, and emulsions are composed of deformable particles. However, the effect of single-particle deformability on the collective behavior of soft solids is still poorly understood. We perform numerical simulations of two-dimensional jammed packings of explicitly deformable particles to study the mechanical response of model soft solids. We find that jammed packings of deformable particles with excess shape degrees of freedom possess low-frequency quartic vibrational modes that stabilize the packings even though they possess fewer interparticle contacts than the nominal isostatic value. Adding intraparticle constraints can rigidify the particles, but these particles undergo a buckling transition and gain an effective shape degree of freedom when their preferred perimeter is above a threshold value. We find that the mechanical response of jammed packings of deformable particles with shape degrees of freedom differs significantly from that of jammed packings of rigid-shape particles, which emphasizes the importance of particle deformability in modeling soft solids.

关键词： Collective behavior Jamming Emulsions Foams Tissues Molecular dynamics

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LOW-carbon hydrogen production via bioenergetic systems: A bibliometric and systematic review

Next Research

引用

Next Research 2025年第2期2卷

作者： Victor C.L. Arruda Taynara G.S. Lago Glauber Cruz Sayonara A. Eliziário Marta C. Dantas Raphael Abrahão Postgraduate Program in Renewable Energy (PPGER) Center of Renewable and Alternative Energy (CEAR) Federal University of Paraiba (UFPB) João Pessoa Brazil Department of Renewable Energy Engineering Center of Renewable and Alternative Energy (CEAR) Federal University of Paraiba (UFPB) João Pessoa Brazil Processes and Thermal Systems Laboratory (LPSisTer) Department of Mechanical Engineering Federal University of Maranhão (UFMA) São Luís Maranhão Brazil

Biomass, the feedstock for conversion into bioenergy, can come from forestry, agricultural, urban, industrial, or animal environments. Energy from biomass can be produced by direct combustion or, converted into biofuels through bioconversion or thermoconversion processes, such as biogases (methane, hydrogen), bioethanol, biodiesel, and others. This study aimed to provide a bibliometric and systematic literature analysis of low-carbon hydrogen and bioenergy systems. A combination of the keywords "biomass," "renewable," "anaerobic digestion" or "biodigestion," and "H2" or "hydrogen" were used. The study covered the period from 2002 to 2022. After applying filters and considering the topic's relevance in current discussions, 49 works were selected and analyzed in detail. The scientific community has shown increasing interest in this field in recent years, with efforts focused on bioenergy, energy sources renewables, and climate change. Several studies, from theoretical models to experimental, were conducted at both laboratory and industrial scales, and agricultural or urban settings. In addition to anaerobic digestion, other conversion processes were explored, such as coupled or isolated dark fermentation and photo-fermentation, particularly when using algal biomass as feedstock. Co-digestion with animals, vegetable, or algae substrates was also discussed. In terms of bibliometrics, the growth trend of research has been since 2017. The increase in articles featuring practical, methodological, and technological innovations led to diverse technological and biomass arrangements. The integration of cascade bioprocesses represents a significant step toward optimizing bioenergy production. This work highlights the trends in low-carbon hydrogen production, particularly through the techniques, technologies, and substrates in various production setup combinations. However, there is still a need for research on the financial and economic aspects of investments and operations in

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Sers Spectroscopy with Machine Learning to Analyze Human Plasma Derived Sevs for Coronary Artery Disease Diagnosis and Prognosis

SSRN

引用

SSRN 2022年

作者： Huang, Xi Liu, Bo Guo, Shenghan Guo, Weihong Liao, Ke Hu, Guoku Shi, Wen Kuss, Mitchell Duryee, Michael J. Anderson, Daniel R. Lu, Yongfeng Duan, Bin Department of Electrical and Computer Engineering University of Nebraska Lincoln LincolnNE United States Mary & Dick Holland Regenerative Medicine Program University of Nebraska Medical Center OmahaNE United States Division of Cardiovascular Medicine Department of Internal Medicine University of Nebraska Medical Center OmahaNE United States Department of Industrial and Systems Engineering Rutgers The State University of New Jersey PiscatawayNJ United States Department of Pharmacology and Experimental Neuroscience University of Nebraska Medical Center OmahaNE United States Division of Rheumatology Department of Internal Medicine University of Nebraska Medical Center OmahaNE United States Department of Surgery College of Medicine University of Nebraska Medical Center OmahaNE United States Department of Mechanical and Materials Engineering University of Nebraska-Lincoln LincolnNE United States School of Manufacturing Systems and Networks Arizona State University MesaAZ United States

Coronary artery disease (CAD) is one of the major cardiovascular diseases and represents the leading causes of global mortality. Developing new diagnostic and therapeutic approaches for CAD treatment are critically needed, especially for an early accurate CAD detection and further timely intervention. In this study, we successfully isolated human plasma small extracellular vesicles (sEVs) from four stages of CAD patients, i.e., healthy control, stable plaque, non-ST-elevation myocardial infarction, and ST-elevation myocardial infarction. Surface-enhanced Raman scattering (SERS) measurement in conjunction with five machine learning approaches, including Quadratic Discriminant Analysis, Support Vector Machine (SVM), K-Nearest Neighbor, Artificial Neural network, were then applied for the classification and prediction of the sEV samples. Among these five approaches, the overall accuracy of SVM shows the best predication results on both early CAD detection (86.4%) and overall prediction (92.3%). SVM also possesses the highest sensitivity (97.69%) and specificity (95.7%). Thus, our study demonstrates a promising strategy for noninvasive, safe, and high accurate diagnosis for CAD early detection. © 2022, The Authors. All rights reserved.

关键词： Diseases

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Short-term forecasting of Amazon rainforest fires based on ensemble decomposition model

arXiv

引用

arXiv 2020年

作者： da Silva, Ramon Gomes Ribeiro, Matheus Henrique Dal Molin Mariani, Viviana Cocco dos Santos Coelho, Leandro Pontifical Catholic University of Parana Industrial & Systems Engineering Graduate Program Curitiba Brazil Federal Technological University of Parana Department of Mathematics Pato Branco Brazil Federal University of Parana Dept. of Electrical Eng. Curitiba Brazil Pontifical Catholic University of Parana Mechanical Engineering Graduate Program Curitiba Brazil

Accurate forecasting is important for decision-makers. Recently, the Amazon rainforest is reaching record levels of the number of fires, a situation that concerns both climate and public health problems. Obtaining the desired forecasting accuracy becomes difficult and challenging. In this paper were developed a novel heterogeneous decomposition-ensemble model by using Seasonal and Trend decomposition based on Loess in combination with algorithms for short-term load forecasting multimonth-ahead, to explore temporal patterns of Amazon rainforest fires in Brazil. The results demonstrate the proposed decomposition-ensemble models can provide more accurate forecasting evaluated by performance measures. Diebold-Mariano statistical test showed the proposed models are better than other compared models, but it is statistically equal to one of them. Copyright © 2020, The Authors. All rights reserved.

关键词： Decision making

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Autonomously deployable tower infrastructure for exploration and communication in lunar permanently shadowed regions

Autonomously deployable tower infrastructure for exploration...

引用

Accelerating Space Commerce, Exploration, and New Discovery Conference, ASCEND 2020

作者： Amy, Caleb Bégin, Marc-André Browder, Becca Chan, Manwei Dawson, Charles Pereira, Paula Do Vale Hank, Travis J. Hinterman, Eric Lordos, George Martell, Benjamin Miller, Alex O’neill, Cormac Padia, Vineet J. Stamler, Natasha Todd, Jessica Wang, Nieky Newman, Dava J. de Weck, Olivier L. Hoffman, Jeffrey A. Dept of Mechanical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Dept of Aeronautics and Astronautics and Technology & Policy Program Massachusetts Institute of Technology CambridgeMA02139 United States Dept of Aeronautics and Astronautics Massachusetts Institute of Technology CambridgeMA02139 United States Physics and EECS Massachusetts Institute of Technology CambridgeMA02139 United States Dept of Mechanical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Mechanical Engineering and Urban Planning Massachusetts Institute of Technology CambridgeMA02139 United States Dept of Aeronautics and Astronautics Woods Hole Oceanographic Institute Massachusetts Institute of Technology CambridgeMA02139 United States Massachusetts Institute of Technology CambridgeMA02139 United States Aeronautics and Astronautics and Engineering Systems Dept of Aeronautics and Astronautics Massachusetts Institute of Technology CambridgeMA02139 United States

ISBN: (纸本)9781624106088

NASA is interested in characterising and robotically exploring the lunar permanently shadowed regions (PSRs) in advance of Artemis crewed landings. The challenging terrain of these regions means a lander would only be able to access the rim of a PSR, limiting line-of-sight communication and sensing into the PSR. Autonomously deployed lunar tower infrastructures could provide valuable lines of sight into and around these PSRs. NASA has developed deployable composite booms for use in microgravity, and we propose an extension of those capabilities by deploying a composite boom vertically in the lunar gravity field. Services hosted by the elevated platform at the top of the boom, such as power beaming, radio repeaters, or imagers, could support the near-term operations of multiple distributed, mobile, robotic assets as well as long-term regional operations of exploration crews. The Multifunctional Expandable Lunar Lightweight, Tall Tower (MELLTT) design, created by our interdisciplinary team of MIT graduate and undergraduate students in October 2019, has been selected and funded by NASA STMD and Space Grant as a finalist in the National Institute of Aerospace’s NASA BIG Idea 2020 Challenge and will be demonstrated at the virtual BIG Idea Forum in January 2021. The expected result of this work is a proof-of-concept of a TRL 4 prototype of a deployable, tall lunar tower by January 2021, setting the stage for future development along a path to flight targeting an early 2020’s lunar tower technology demonstration mission in support of the Artemis program. © 2020 The MITRE Corporation. All Rights Reserved.

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