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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

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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

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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

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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...

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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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Haptic display for virtual reality: progress and challenges

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Virtual Reality & Intelligent Hardware 2019年第2期1卷 136-162页

作者： Dangxiao WANG Yuan GUO Shiyi LIU Yuru ZHANG Weiliang XU Jing XIAO State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100083China Beijing Advanced Innovation Center for Biomedical Engineering Beihang UniversityBeijing 100083China Peng Cheng Laboratory Shenzhen 518055China Department of Mechanical Engineering University of AucklandAuckland 1142New Zealand School of Computer Science and the Robotics Engineering Program Worcester Polytechnic InstituteWorcesterMA 01609-2280USA

Immersion, interaction, and imagination are three features of virtual reality (VR). Existing VR systems possess fairly realistic visual and auditory feedbacks, and however, are poor with haptic feedback, by means of which human can perceive the physical world via abundant haptic properties. Haptic display is an interface aiming to enable bilateral signal communications between human and computer, and thus to greatly enhance the immersion and interaction of VR systems. This paper surveys the paradigm shift of haptic display occurred in the past 30 years, which is classified into three stages, including desktop haptics, surface haptics, and wearable haptics. The driving forces, key technologies and typical applications in each stage are critically reviewed. Toward the future high-fidelity VR interaction, research challenges are highlighted concerning handheld haptic device, multimodal haptic device, and high fidelity haptic rendering. In the end, the importance of understanding human haptic perception for designing effective haptic devices is addressed.

关键词： Haptic display Virtual reality Desktop haptics Surface haptics Wearable haptics Multimodal haptics

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Numerical Investigation Against Laboratory Experiment: An Overview of Damage and Wind Loads on Structural Design

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Procedia Structural Integrity 2020年 27卷 6-13页

作者： Aldias Bahatmaka Dong-Joon Kim Aditya Rio Prabowo Daewoo Shipbuilding and Marine Engineering (DSME).Co.Ltd Okpo 53305 South Korea Interdisciplinary Program of Marine Design Convergence Pukyong National University Busan 48513 South Korea Department of Naval Architecture and Marine Systems Engineering Pukyong National University Busan 48513 South Korea Department of Mechanical Engineering Universitas Sebelas Maret Surakarta 57126 Indonesia

The numerical approach is being used against experimental and solves engineering problems. In the engineering design, the structural and load analysis are a part of an important thing to show the effect of geometrical or the structure design. The main purpose is to review the influence of deckhouse height on the flow around the funnel and aft ship structure. In this review study, the fluid-structure and 3D steady RANS CFD are used to validate the result of simulations. Several aspects of the numerical approach, such as turbulence modeling, boundary conditions, inlet velocity, and pressure outlet to simulate wind load in CFD, ground surface roughness, and quantification of wind loads by computational fluid-structure and computational fluid dynamics (CFD) are summarized. A benchmarking study of the numerical approach against the experiment is emphasized. A comparative study among the numerical prediction on the wind tunnel demonstrated good agreement and satisfaction. Moreover, by numerical approach could handle the accurate results and show how the response to the ship structure that makes the dynamic interaction during wind loads events.

关键词： Fluid Structure Wind Loads Numerical Approach CFD Experimental

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First and second law analyses of wastewater cooled condenser for a refrigeration system

First and second law analyses of wastewater cooled condenser...

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作者： Karacayli, Ibrahim Altay, Lutfiye Hepbasli, Arif Air Conditioning and Refrigeration Technology Program Ege High Vocational School Ege University Bornova Izmir35100 Turkey Department of Mechanical Engineering Faculty of Engineering Ege University Bornova Izmir35100 Turkey Department of Energy Systems Engineering Faculty of Engineering Yaşar University Bornova Izmir35100 Turkey

In this study, a vapour compression refrigeration (VCR) system with a wastewater (WW) cooled condenser at a temperature range of 27-29°C was designed. The cooling capacity of the system using R134a as the refrigerant was 1.09 kW. The condenser consisted of a coaxial heat exchanger with a capacity of 1 kW. This paper dealt with energy and exergy analyses of the VCR system using WW, as a heat sink. Experiments were performed in order to evaluate the energetic and exergetic performances of the wastewater-cooled condenser (WWC) and the overall system. The convective heat transfer coefficient of WW and refrigerant in the condenser, overall heat transfer coefficient of the WWC, total amount of heat removed by WW, amount of cooling effect, coefficient of performance (COP), exergy destruction rate, and second law efficiencies of the WWC and VCR system were calculated under different WW temperatures and flowrates. Increasing volumetric flowrate of WW from 200 L/h to 400 L/h caused 4.4% improvement in COP, 12.0% reduction in exergy destruction, and 10.3% increase in exergy efficiency. © 2019 Inderscience Enterprises Ltd.

关键词： Exergy

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Vehicle scrappage policies for transportation decarbonization

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Environmental Research: Energy 2024年第3期1卷 033002-033002页

作者： Maxwell Woody Samuel Stolper Parth Vaishnav Gregory A Keoleian Center for Sustainable Systems School for Environment and Sustainability University of Michigan Ann Arbor MI United States of America Department of Mechanical Engineering College of Engineering University of Michigan Ann Arbor MI United States of America Science Technology and Public Policy Program Ford School of Public Policy University of Michigan Ann Arbor MI United States of America School for Environment and Sustainability University of Michigan Ann Arbor MI United States of America

Vehicle electrification is one of the primary strategies being pursued for the decarbonization of the transportation sector. But to meet emissions reduction goals for that sector, the current vehicle replacement rate is insufficient. Vehicle scrappage policies can accelerate fleet turnover by providing an incentive to retire a vehicle before its natural end of life and simultaneously replace it with a more efficient or less polluting alternative. Previous scrappage programs, like the United States' Cash for Clunkers, have had limited success as decarbonization policies; however, most of these programs ended before the widespread availability of electric vehicles and did not have decarbonization as a primary policy goal. Here we explain why scrappage policies may be necessary to meet climate goals, review historic vehicle scrappage policies from a variety of countries, highlight the successes and failures of those policies, and establish policy design considerations that could help ensure that future scrappage programs are more successful than previous efforts.

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