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Thermoelectric chalcopyrite-type ZnSnAs 2 compound with high power factor for low-grade waste-heat recovery

Journal of Alloys and Compounds 2025年 1033卷

作者： Koki Nakashima Shoma Miura Hiroki Ienaga Keita Nomoto Kenji Yoshino Kensuke Nishioka Akira Nagaoka Graduate School of Engineering University of Miyazaki Miyazaki 889-2192 Japan School of Aerospace Mechanical and Mechatronic Engineering and Australian Centre for Microscopy and Microanalysis The University of Sydney Sydney 2006 Australia Faculty of Engineering Electrical and Electronic System Program University of Miyazaki Miyazaki 889-2192 Japan GX Research Center University of Miyazaki Miyazaki 889-2192 Japan

Chalcopyrite compounds are promising thermoelectric (TE) materials owing to their excellent performance. Adopting a pseudocubic structure is a key strategy to improve the TE performance as it increases the degeneracy at the valence band edge. Herein, the TE properties of a II-IV-V 2 group, p-type ZnSnAs 2 chalcopyrite with a pseudocubic structure are systematically investigated. Polycrystalline, single phase, stoichiometric ZnSnAs 2 was obtained at growth temperatures above 700 ºC. The TE properties of ZnSnAs 2 depended on its intrinsic defect concentration, which was influenced by its Zn/Sn ratios. A high power factor value of 2890 μW/mK 2 was obtained in Zn-poor Zn 0.9 Sn 1.1 As 2 at 373 K. The TE figure of merit for the off-stoichiometric ZnSnAs 2 reached 0.1 at 573 K. Consequently, a maximum TE conversion efficiency of ∼1 % at a temperature gradient of 300 K was demonstrated for a ZnSnAs 2 -based single-leg device. These results can accelerate the development of TE technologies for low-energy harvesting.

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Loss Balancing for Physics-Informed Neural Networks Considering Procedure for Solving Partial Differential Equations 13

Loss Balancing for Physics-Informed Neural Networks Consider...

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Joint 13th International Conference on Soft Computing and Intelligent systems and 25th International Symposium on Advanced Intelligent systems, SCIS and ISIS 2024

作者： Kojima, Manabu Otsuki, Kazuma Suzuki, Masato Abe, Masajiro Baba, Masaaki Yokota, Kazuya Master's Program in Mechanical Engineering Nagaoka University of Technology Nagaoka Japan Nagaoka University of Technology Department of System Safety Engineering Nagaoka Japan Nagaoka University of Technology Department of Mechanical Engineering Nagaoka Japan

ISBN: (纸本)9798350373332

With the development of machine learning, numerical analysis using neural networks has been devised. Remarkably, physics-informed neural networks (PINNs) enable physically consistent numerical analysis by introducing a loss function that conforms to relevant governing equations. Moreover, research is rapidly advancing for the application of PINNs to inverse analysis in areas such as physical property identification. For a PINN to learn governing equations, the weights of the loss functions should be properly determined because they have different roles in components such as boundary conditions, initial conditions, and governing equations. However, weight setting is generally challenging. We propose a loss balancing method considering the procedure for solving partial differential equations. The proposed method is validated through comparisons with conventional solvers. © 2024 IEEE.

关键词： Partial differential equations

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The Integration of True Lean and Industry 4.0 to Sustain a Culture of Continuous Improvement 16th

The Integration of True Lean and Industry 4.0 to Sustain a C...

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16th IFIP WG 5.1 International Conference on Product Lifecycle Management, PLM 2019

作者： Maginnis, M. Abbot Hapuwatte, Buddhika M. Keown, David Lean System Program Department of Mechanical Engineering University of Kentucky Lexington KY United States Department of Mechanical Engineering University of Kentucky Lexington KY United States Plano TX United States

ISBN: (纸本)9783030422493

Recent advances in information and communication technology and the Internet of Things (IoT) are driving the development of Industry 4.0. Its objective is to enable real-time information exchange between people, machines, products and resources, providing new opportunities for improved safety, quality, productivity and cost factors which can be applied in all stages of Product Lifecycle Management (PLM). The application of lean principles and practices where Industry 4.0 is deployed can leverage real-time processing visibility into even greater productivity improvements if implemented correctly. To do this, companies need to go beyond the implementation of the familiar lean tools and practices such as 5S, visual management and management directed kaizen activities etc. to consider the thinking behind the tools, especially the role of the team members. An over-reliance on technology risks undervaluing the importance of human innovative capacity which can significantly impact the ability to conduct systematic problem solving, adversely effecting daily operational performance and significantly reducing continuous improvement (CI) capacity. This conceptual paper introduces the major elements and thinking of the Toyota Production system (TPS), also referred to as ‘True Lean’, which are often hidden or underdeveloped within the popular understanding of lean. This paper illustrates how TPS-thinking can be operationalized to support and sustain a CI environment while leveraging the improved visibility possible with Industry 4.0 to integrate all stages of PLM. © 2019, IFIP International Federation for Information Processing.

关键词： Industry 4.0

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Generation of the anti-Twist crowned helical gear by modifying the gear rotation angle in the hobbing process 2nd

Generation of the anti-Twist crowned helical gear by modifyi...

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2nd International Conference on Machining, Materials and mechanical Technologies, IC3MT 2016

作者： Hsu, Ruei-Hung Wu, Yu-Ren Chen, Shih-Sheng Bachelor's Program in Precision System Design Feng Chia University Taiwan Department of Mechanical Engineering National Central University Taiwan

ISBN: (纸本)9783035711011

In the gear-hobbing process, the work gear tooth flank is usually longitudinally crowned by varying the center distance between the hob and the work gear. Without crossed angle compensation, however, this center distance variation produces a twisted tooth flank on the work gear. This paper therefore proposes a methodology to reduce this tooth flank twist and achieve anti-Twist in longitudinal crowning by modifying the gear rotation angle in the hobbing process which is practiced using a CNC hobbing machine with three synchronous axes. © 2017 Trans Tech Publications, Switzerland.

关键词： Helical gears

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Comparison of load calculation between IEC and GL offshore wind turbine design guideline using NREL 5 MW reference wind turbine 25

Comparison of load calculation between IEC and GL offshore w...

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25th International Ocean and Polar engineering Conference, ISOPE 2015

作者： Su, Wei-Nian Huang, Chin-Cheng Lin, Huei-Jeng Mechanical and System Engineering Program Institute of Nuclear Energy Research Taoyuan City Taiwan Department of Engineering Science and Ocean Engineering National Taiwan University Taipei City Taiwan

ISBN: (纸本)9781880653890

IEC 61400-3 (2009) and GL Offshore guideline (2012) are two commonly adopted guidelines for certification of offshore wind turbines worldwide. Comparison of load calculation during normal and idling situations between these two guidelines is performed in this paper. The NREL 5 MW wind turbine with monopile support structure is selected as the reference wind turbine system. Study of the impact on the loading conditions is conducted in this paper. Design load case (DLC) 1, 6, and 7 are considered in this work and the focus is on the Class I system with different turbulence characteristics (category A, B, and C). Both of extreme and fatigue loads are derived at critical components such as blade, shaft, tower, and foundation. The major impact is investigated and identified in this paper. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Offshore wind turbines

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Improve the through-thickness electrical conductivity of cfrp laminate using flow-aligned carbon nanofiber Z-threads

Improve the through-thickness electrical conductivity of cfr...

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SAMPE Long Beach 2018 Conference and Exhibition

作者： Ranabhat, Bikash Hsiao, Kuang-Ting University of South Alabama Department of Mechanical Engineering Shelby Hall 150 Jaguar Drive MobileAL36608 United States System Engineering Program United States

ISBN: (纸本)9781934551271

Traditional Carbon Fiber Reinforced Plastics (CFRPs), carry high in-plane strength and electrical conductivity but exhibit intrinsic weaknesses in strength, toughness and conductivity in the through-thickness direction (i.e. z-direction). This paper presents a novel approach to align and thread Carbon Nanofibers (CNFs) through the porous medium (Carbon fiber fabric) using an interesting radial-flow alignment method and manufacture a novel CNFs z-threaded CFRP prepreg. This new radial-flow alignment approach is unique and has been found highly effective to z-thread the array of carbon fibers (diameter ~ 7 microns) with numerous long CNFs (length ~ 50-200 microns) under a Scanning Electronic Microscope (SEM) analysis. Experimental tests performed on a cured laminate sample prepared by this novel technique with 1 wt% aligned CNF concentration showed a significant improvement on the z-directional electrical conductivity for direct current (DC). The 1 wt% CNFs z-threaded CFRP was found about 100 times as conductive as the control CFRP;whereas the unaligned 1 wt% CNFs modified CFRP was only about 16 times as conductive as the control sample. © 2017 by Bikash Ranabhat and Kuang-Ting Hsiao. Published by Society for the Advancement of Material and Process engineering with permission.

关键词： Carbon nanofibers

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On the importance of species selection for the formulation of fuel surrogates 38th

On the importance of species selection for the formulation o...

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38th International Symposium on Combustion, 2021

作者： Kim, Doohyun Violi, Angela Department of Mechanical and System Design Engineering Hongik University 94 Wausan-ro Mapo-gu Seoul Korea Republic of Departments of Mechanical Engineering Chemical Engineering Biophysics Program University of Michigan Ann Arbor MI United States

Fuel surrogates are mixtures of simple compounds that emulate the combustion characteristics of more complex fuels, with the primary objective to enable detailed combustion modeling of very complex real fuels. Current efforts in surrogate development aim to optimize the compositions of pure hydrocarbons to emulate multiple combustion related properties. In doing so, weights are assigned when defining optimization problem to reflect the importance of each property. In this study, the impact of surrogate component selection and weight assignment on surrogate formulations was quantitatively investigated by analyzing their sensitivities during the surrogate optimization. Using experimental data of a reference jet fuel as target, a study was designed using a surrogate optimizer that imposes orthogonal perturbations on the surrogate components and weights, and their effect on the optimized surrogate mixtures was analyzed. Results from 3600 cases revealed that perturbations of surrogate components, rather than weights, induce far greater variability in the optimized composition and target property agreement. While the derived cetane number (DCN) agreement showed a greater variability from the weight perturbation, the main reason for such high sensitivity was due to the wide range of values for pure component DCN of the individual components, which was also a result of the surrogate component selection. The results also demonstrated that the selection of surrogate components nearly predefines the overall shape of the distillation curves regardless of the weight values. This study quantitatively supports the idea that appropriate selection of surrogate components that capture the physical and chemical characteristics of actual constituents of target fuel will increase the possibility of successful surrogate formulation and will mitigate the impact from arbitrary weight assignment.

关键词： Fuel additives

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EXPERIMENTAL EVALUATION ON THE LONGITUDINAL COMPRESSIVE STRENGTH OF CARBON NANOFIBERS Z-THREADED CFRP LAMINATE MANUFACTURED BY THE MAGNETIC COMPACTION FORCE ASSISTED ADDITIVE MANUFACTURING METHOD 9

EXPERIMENTAL EVALUATION ON THE LONGITUDINAL COMPRESSIVE STRE...

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9th Annual Composites and Advanced Materials Expo, CAMX 2023

作者： Islam, Mohammad Rakibul Taylor, Wyatt Warren, Ryan Hsiao, Kuang-Ting Department of Mechanical Engineering University of South Alabama MobileAL36688 United States System Engineering Program University of South Alabama MobileAL36688 United States

ISBN: (纸本)9781934551448

The matrix sensitive weaknesses of Carbon Fiber Reinforced Polymer (CFRP) laminates are usually magnified by mainstream additive manufacturing (AM) methods due to the AM-process-induced voids and defects. In this paper, a novel Magnetic Compaction Force Assisted-Additive Manufacturing (MCFA-AM) method is used to print Carbon Nanofibers (CNF) Z-threaded CFRP (i.e., ZT-CFRP) composite laminates. The MCFA-AM method utilizes a magnetic force to simultaneously support, deposit, and compact Continuous Carbon Fiber Reinforced Polymer (C-CFRP) composites in free space and quickly solidifies the CFRP part without any mold;it effectively reduces the voids. Past research proved that the zig-zag threading pattern of the CNF z-threads reinforces the interlaminar and intralaminar regions in the ZT-CFRP laminates manufactured by the traditional Out of Autoclave-Vacuum Bag Only (OOA-VBO) method, and enhances the matrix sensitive mechanical, thermal, and electrical properties. In this study, the longitudinal compressive test (ASTM D695, i.e., SACMA SRM 1R-94) was performed on the MCFA-AM printed ZT-CFRP laminate. The results were compared with unaligned CNF-modified CFRP (UA-CFRP), control CFRP, and no-pressure CFRP samples' data to investigate the impact of the CNF z-threads and MCFA-AM process on the CFRP's performance. The 0.5-bar MCFA-AM printed ZT-CFRP showed comparable longitudinal compressive strength with the 1-bar OOA-VBO cured CFRP. Copyright © 2023. Used by CAMX - The Composites and Advanced Materials Expo. CAMX Conference Proceedings.

关键词： Carbon nanofibers

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On reference node deployment for precise clock synchronization in smart power grid

On reference node deployment for precise clock synchronizati...

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9th IEEE Int. Conf. on Dependable, Autonomic and Secure Comput., DASC 2011, incl. 9th Int. Conf. on Pervasive Intelligence and Computing, PICom 2011, 9th Int. Symp. on Embedded Computing, EmbeddedCom 2011, 1st Int. Conf. on Cloud and Green Comput.CGC

作者： Chang, Chiu-Ping King, Chung-Ta Chan, Chen-Min Department of Computer Science National Tsing Hua University Hsinchu Taiwan Mechanical and System Engineering Program Institute of Nuclear Energy Research Taoyuan Taiwan

ISBN: (纸本)9780769546124

Cloud computing will play an essential role in smart power grid by providing a cost-efficient, scalable IT platform for the delivery and management of electricity. A key component in the cloud-based smart power grid is the intelligent electronic devices (IEDs), which monitor, control, and protect the power system, and collect data back into the cloud for analysis and management. To maintain proper and robust operations of the power system, the collected data must be time-stamped under a common time reference. This in turn demands that the clocks of the distributed IEDs be synchronized to the required precision. A viable approach is to equip some of the IEDs with the Global Positioning system (GPS) as the time references and use the communication links already existing between the IEDs to synchronize the clocks of those without GPS. The question is, given a set of such references nodes, how to decide whether the clocks of all the IEDs can be synchronized to the required precision. If not, how can one add fewest reference nodes to meet the requirements? This paper addresses these issues and proposes efficient algorithms to solve the problems. © 2011 IEEE.

关键词： Smart power grids

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Resistance of double-glove hole puncture indication systems to surgical needle puncture

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Journal of Long-Term Effects of Medical Implants 2003年第2期13卷 85-90页

作者： Edlich, Richard F. Wind, Tyler C. Hill, Lisa G. Thacker, John G. Plastic Surgical Research Program University of Virginia Health System Charlottesville VA United States Department of Mechanical Engineering Charlottesville VA United States 16155 NW Jenne Lake Ct. Beaverton OR 97006 United States

Double-gloving has been shown to reduce conclusively the risk of operating room personnel's exposure to blood. Limiting risk of exposure to blood by double-gloving provides protection against the transmission of bloodborne diseases. Realizing the importance of double-gloving, a double-glove hole puncture indication system exists that accurately detects the presence of glove hole puncture in the presence of fluid. Once a glove puncture is recognized by this double-glove hole puncture indication system, it provides a warning to the surgeon to remove the punctured gloves, wash hands, and don a new, sterile double-glove hole puncture indication system. While accurately identifying the presence of glove hole puncture in the presence of fluid, this double-glove hole puncture indication system also has resistance to needle puncture superior to that of single gloves. It is the purpose of this study to document the resistance to needle puncture of latex and non-latex double-glove hole puncture indication systems using a reproducible experimental model. The resistance to needle puncture of the double-glove systems was significantly greater than that of the undergloves or outer gloves alone. The resistance to glove puncture of the non-latex and latex single and double-glove systems was significantly greater than those encountered by the latex single and double-glove systems, respectively. On the basis of their accuracy in detecting glove hole puncture, combined with their demonstrated superior resistance to surgical needle puncture as compared to single gloves, these latex and non-latex double-glove hole puncture indication systems are recommended for all surgical procedures.

关键词： Implants (surgical)

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