检索结果-内蒙古大学图书馆

What are tutors’ perceptions of an online tutoring project—Digital Learning Companion—During the COVID-19 pandemic? A case study in Taiwan

学校读者我要写书评

暂无评论

Universal Access in the Information Society 2024年第3期23卷 1409-1425页

作者： Tran, Khanh Nguyen Phuong Weng, Cathy Tran-Nguyen, Phuong Lan Astatke, Melese Tran, Nguyen-Phuong-Dung Graduate Institute of Digital Learning and Education National Taiwan University of Science and Technology No. 43 Section 4 Keelung Rd Da’an District Taipei106 Taiwan Department of Mechanical Engineering Can Tho University Campus II 3/2 StreetNinh Kieu District Can Tho City Viet Nam Department of Materials Science and Technology National Taiwan University of Science and Technology No. 43 Section 4 Keelung Rd Da’an District Taipei106 Taiwan

The COVID-19 outbreak has had serious impact on remote education and service-learning implementation in Taiwan. To alleviate these impacts, the Digital Learning Companion, an online tutoring project, was proposed to bridge the digital divide and learning gap among remote children, while offering university students an online service-learning environment. This project recruited international students as tutors for local children. To explore tutors' perceptions of this project during the COVID-19 pandemic, qualitative research, particularly a case study, was conducted. Adopting purposive sampling, 15 participants were chosen for interviews at the end of the project, and 10 reflective videos were used to reveal further information to supplement the interview results. Content analysis was employed to analyse the data. The findings implied that using JoinNet and tutoring journals significantly facilitated the tutoring process, which led to tutors’ remarkable development in skills, social relationships, multicultural experience, altruism, social responsibility, self-efficacy, and affective values. However, they encountered some challenges, such as technical problems, communication barrier, lack of tutee information, and short tutoring duration. The solutions to these challenges and insightful suggestions for the project development are pointed out. The results of this study contribute to tutors’ cognitive, social, and motivational development, and support the online service-learning-integrated curriculum, which can become a reference for further studies regarding online service-learning implementation to bridge the research gap. Graphical abstract: (Figure presented.). © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.

关键词： COVID-19

Encapsulating Spherical Feni Particles in N-Doped Carbon Fibers to Construct a Free-Standing and Flexibleelectrode with Superior Lithium Storage Performance

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Li, Xiaoqiang Xiang, Jun Guan, Guangguang Zhang, Xueke Zhang, Kaiyin School of Science Jiangsu University of Science and Technology Zhenjiang212100 China Institute of Materials Science and Engineering Beijing University of Technology Beijing100124 China Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang110016 China College of Mechanical and Electrical Engineering Wuyi University Wuyishan354300 China

Constructing free-standing electrode with superior lithium storage capacity and good mechanical performance is fascinating for next-generation lithium-ion batteries (LIBs). Nevertheless, their practical application is hindered by complicated synthesis procedures and high cost. Herein, a highly stable, self-supporting and flexible electrode material for LIBs is created by encapsulating spherical FeNi particles into one-dimensional N-doped carbon nanofiber film (FeNi/N-CFM) using the electrospinning technique and heat treatment. The carbon nanofiber-supported three-dimensional (3D) conductive skeleton can significantly buffer FeNi nanoparticle agglomeration and comminution for improving constructional stability, and meanwhile accelerate the movement and jumping of electrons, thus further promoting the electrochemical conversion reaction. Benefiting from the unique structure characteristics and flexibility, the FeNi/N-CFM nanocomposites employed as binder-free electrodes for LIBs exhibit good lithium storage performance (an initial discharge capacity of 1031.5 mA h g−1 and a reversible capacity of 481.3 mA h g−1 at 100 mA g−1 after 100 cycles), rate capacity (305.1 mA h g−1 at 1000 mA g−1) and outstanding reversibility (coulombic efficiency of around 100% after 100 cycles). In addition, this facile and effective strategy may provide a pathway for fabricating free-standing electrodes. © 2024, The Authors. All rights reserved.

关键词： Carbon nanofibers

The Advent of Wide Bandgap Green-Synthesized Copper Zinc Tin Sulfide Nanoparticles for Applications in Optical and Electronic Devices

学校读者我要写书评

暂无评论

Journal of materials science and Chemical engineering 2023年第3期11卷 22-33页

作者： Opeyemi S. Akanbi Haruna A. Usman Gbemi F. Abass Kehinde E. Oni Akinsanmi S. Ige Bola P. Odunaro Idowu J. Ojo Julius A. Oladejo Halimat O. Ajani Adnan Musa Joshua Ajao Department of Pure and Applied Physics Ladoke Akintola University of Technology Ogbomosho Nigeria Department of Mechanical Engineering Jigawa State Polytechnic Dutse Nigeria Department of Materials Science and Engineering Hohai University Nanjing China Department of Mechanical Engineering Ekiti State University Ado Ekiti Nigeria Department of Materials Science and Engineering University of Colorado Boulder Boulder USA Department of Chemical Engineering Ladoke Akintola University of Technology Ogbomoso Nigeria Department of Mechanical Engineering Federal University of Technology Akure Nigeria Department of Biotechnology and Genetics Russian State Agrarian University Moscow Russia

Power-electronic devices are widely used in various applications, such as voltage and frequency control for transmitting and converting electric power. As these devices are becoming increasingly important, there is a need to reduce their losses and improve their performance to reduce electric power consumption. Current power semiconductor devices, such as inverters, are made of silicon (Si), but the performance of these Si power devices is reaching its limit due to physical properties and energy bandgap. To address this issue, recent developments in wide bandgap (WBG) semiconductor materials, such as silicon carbide (SiC) and gallium nitride (GaN), offer the potential for a new generation of power semiconductor devices that can perform significantly better than silicon-based devices. In this research, a green synthesized copper-zinc-tin-sulfide (CZTS) nanoparticle is proposed as a new WBG semiconductor material that could be used for optical and electronic devices. Its synthesis, consisting of the production methods and materials used, is discussed. The characterization is also discussed, and further research is recommended in the later sections to enable the continual advancement of this technology.

关键词： Wide Bandgap Semiconductor Semiconductor Electronic Device Power Device Optical Device CZTS

Microstructure, mechanical Properties and Wear Resistance of Tinbcrmox Refractory Multi-Principal Element Alloys

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Shi, Shaoqi Zou, Yang Yang, Zefeng Sun, Aihua Xu, Gaojie Long, Fei Li, Zhixiang Zhejiang Key Laboratory of Additive Manufacturing Materials Ningbo Institute of Materials Technology & Engineering Chinese Academy of Sciences Ningbo315201 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Ningbo China Ningbo315100 China

The advancement of refractory multi-principal element alloys, exhibiting superior mechanical properties and wear resistance, is of paramount importance in materials engineering. This study introduces a novel series of refractory multi-principal element alloys, designated as TiNbCrMox(x=0, 0.2, 0.4, 0.6, 0.8, 1.0), and methodically explores the impact of varying molybdenum (Mo) content on their microstructural characteristics, phase composition, mechanical performance, and wear resistance. Empirical analyses reveal that these alloys are primarily composed of body-centered cubic (BCC) and Laves phases. The yield strength at ambient temperature is observed to span a range from 1572.8 MPa to 1902.5 MPa. Notably, the strategic addition of Mo in controlled proportions has been found to significantly enhance the hardness and ductility of the TiNbCrMox alloys. This improvement is attributed to the modification in the Laves phase concentration and the degree of lattice distortion. Moreover, the study identifies a marked increase in the hardness of the alloys, which, in conjunction with the formation of a lubricative oxide film, substantially reduces their wear rate. Specifically, the TiNbCrMo0.6 variant demonstrates a notably low wear rate, measured at 9.05×10−5mm3/(N·m). This investigation offers invaluable insights into the design and development of high-strength, wear-resistant metallic materials, highlighting their potential for diverse industrial applications. © 2024, The Authors. All rights reserved.

关键词： Wear resistance

Novel Enclosed Delamination Injection Repair Process for Strength Restoration 37

学校读者我要写书评

暂无评论

Novel Enclosed Delamination Injection Repair Process for Str...

37th Technical Conference of the American Society for Composites, ASC 2022

作者： Massey, Justin Romasko, Barrett Kim, Hyonny Materials Science and Engineering Program University of California La Jolla San DiegoCA92093 United States Department of Structural Engineering University of California La Jolla San DiegoCA92093 United States

ISBN: (纸本)9781605956909

Delaminations are a common damage mechanism that occurs on composite structures due to in-service impacts. Enclosed damages less than 50 mm in diameter are of particular interest for repair. Current practices for repair of delaminations include: cut out of the damage and applying a patch or doubler to the cutout site, or injection using a repair resin. The use of a bonded doubler repair is more invasive and requires a cutout that acts as a stress concentration in the area of the repair. Injection repairs have traditionally been a faster, less expensive way to repair composite delaminations. However, the aerospace industry has not accepted injection repair as a strength restorative process. Questions about quantifying delamination internal contamination and ensuring percentage of repair resin fill within a delamination have been primary reasons why injection repairs have not been credited with strength restoration. Development of a new quantitative internal surface cleaning, preparation and repair process for delaminated composite materials is required to provide justification for strength restoration using injection repair. Fabricating representative local delaminations was performed with a modified end-notch flexure (ENF) test. A unidirectional 24-ply panel was fabricated to simulate damage to laminates. Intentional contamination was introduced into the induced delamination of each panel type. Contamination removal and surface preparation using solvent and atmospheric plasma cleaning were completed on the modified ENF coupon and verified utilizing in-line monitoring with Quantitative Gas Analysis (QGA) and post processing inspection with Fourier Transform Infrared Spectroscopy (FTIR). A modified low-viscosity injection resin was developed and utilized to repair the post-tested ENF coupons. The modified epoxy exhibited comparable shear strength characteristics to un-modified neat resin while achieving a >97% reduction in viscosity. Each ENF panel type was assessed f

关键词： Resins

Are we going towards "no-brainer" risk management? A case study on climate hazards 16

学校读者我要写书评

暂无评论

Are we going towards "no-brainer" risk management? A case st...

16th International Conference on Probabilistic Safety Assessment and Management, PSAM 2022

作者： Tamascelli, Nicola Akel, Antonio Javier Nakhal Patriarca, Riccardo Paltrinieri, Nicola Cruz, Ana Maria Department of Mechanical and Industrial Engineering Norwegian University of Science and Technology NTNU Trondheim Norway Department of Civil Chemical Environmental and Materials Engineering Alma Mater Studiorum University of Bologna Bologna Italy Department of Mechanical and Aerospace Engineering Sapienza University of Rome Rome Italy Disaster Prevention Research Institute Kyoto University Kyoto Japan

The overall risk management domain is stepping into its 4.0 phase by implementing and increasingly relaying on cyber-technological systems. Enhanced computational power provides the capability of processing collected databases for prediction and preparation purposes. In fact, early warnings can lead to suggestion for proactive strategies, or directly initiate the action of autonomous actuators ensuring the required level of system safety. But have we reached the promises of digital risk management yet, or will we ever reach them? A traditional view on safety defines it as the absence of accidents and incidents. A forward-looking perspective on safety affirms that it involves ensuring that "as many things as possible go right". However, in both the views there is an element of uncertainty associated to the prediction of future risks and, more subtle, to the capability of possessing all the necessary information for such prediction. This uncertainty does not simply disappear once we apply advanced Machine Learning (ML) techniques to the infinite series of possible accident scenarios, but it can be found behind modelling choices and parameters setting. In a nutshell, "there ain't no such thing as a free lunch", i.e., any model claiming superior flexibility usually introduces extra assumptions. This contribution will illustrate a case on climate-driven disaster data extracted from the Emergency Events Database (EM-DAT) where ML techniques are used to understand natural disaster mortality and unravel underlying causes and influential factors that can inform decision-making and be relevant for risk reduction efforts. This manuscript may allow to affirm with certain confidence that present risk management systems are not even close to a "no-brainer" condition in which the responsibility for human and system safety is entirely moved to the machine. However, this shows that such advanced techniques are progressively providing a reliable support for critical decision making a

关键词： Risk management

Long Term and in situ Measurements of Nanostructure Evolution of Al-3.9Cu-1.5Mg Alloys by Laboratory High Energy Small-Angle X-Ray Scattering

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Fukuda, Shin Ohnuma, Masato Itoh, Goroh Kuramoto, Shigeru Kobayashi, Junya Kobayashi, Equo Division of Quantum Science and Engineering Graduate School of Engineering Hokkaido University Sapporo060-8628 Japan Division of Quantum Science and Engineering Faculty of Engineering Hokkaido Univeristy Sapporo060-8628 Japan Department of Mechanical Systems Engineering Graduate School of Science and Engineering Ibaraki University Hitachi316-8511 Japan Department of Materials Science and Engineering Tokyo Institute of Technology Tokyo152–8552 Japan

The effect of nanostructures on the hardness of Al-3.9Cu-1.5Mg alloys with and without cold rolling (CR) during natural and isothermal aging at 190 °C for up to 48 h has been investigated by in situ high energy laboratory small-angle X-ray scattering combined with micro-Vickers and calorimetry measurements. In the naturally aged samples, the formation of Cu-Mg co-clusters of 1 nm in diameter was observed. In the specimens with CR, the formation of clusters due to CR was observed at the beginning, while little change were observed during aging. Consequently, the total amount of clusters was less than in the specimens without CR in the latter stage of natural aging. The change in the amount of age hardening corresponded to the change in the amount of Cu-Mg co-cluster formation, indicating that the Cu-Mg co-cluster was responsible for the precipitation strengthening at room temperature. At 190 °C for the artificial aging process, precipitate scattering of three different sizes and shapes was observed, i.e., the intermediate and S phases were precipitated in addition to the Cu-Mg co-cluster. The continuous change in volume fraction and size with time suggests that the Cu-Mg co-cluster has grown into an intermediate phase. The time evolution of hardness at 190 °C artificial aging without CR was simply explained by Orowan's equation. These results show that the dispersion state of precipitates mainly affects the hardness in Al-Cu-Mg alloys with low Cu/Mg ratios rather than the phases themselves. © 2024, The Authors. All rights reserved.

关键词： Age hardening

Morphable 3d Architectures Enabled by Shear-Guided Approach

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Li, Kan Liu, Zhi Hu, Xiaonan Xu, Zijian Zhou, Yunlei Chen, Lin Huang, Yonggang Bo, Renheng Zhang, Yihui AML Department of Engineering Mechanics Laboratory of Flexible Electronics Technology Tsinghua University Beijing100084 China State Key Laboratory of Digital Manufacture Equipment and Technology Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi’an Jiaotong University Shaanxi Xi’an710000 China Departments of Mechanical Engineering Civil and Environmental Engineering and Materials Science and Engineering Center for Bio-Integrated Electronics Northwestern University EvanstonIL60208 United States

3D structures and electronic devices assembled through mechanically guided approaches have found important applications in a wide spectrum of emerging fields, including healthcare, biomedical engineering, wearable devices, robotics, among others. To broaden the obtainable functional 3D architectures via mechanical pathways, in this work, a shear-guided assembly approach is demonstrated. A series of structures in forms of ribbon, membrane and hybrid configurations with previously inaccessible geometrical features, such as reversible local flips and centrosymmetric charity are showcased. Finite element analysis (FEA) is performed, suggesting that such shear-induced structures are capable of reversible post-assembly shape transformation among different modes. Given the above, a facile design, consisting of two ribbon-like 3D units (dual-3D-unit design), is introduced and carefully calibrated for shear sensing. Notably, such design is capable of translating the hard-to-measure shear deformation into easily-accessed vertical displacements while insensitive to finite tensile loadings. A multifunctional arrayed electronic interface is fabricated using such dual-3D-unit design, suggesting promising potentials in human-machine interactions. © 2024, The Authors. All rights reserved.

关键词： Shear deformation

Nitrate additives for lithium batteries:Mechanisms,applications,and prospects

学校读者我要写书评

暂无评论

escience 2021年第2期1卷 108-123页

作者： Xiang Li Ruxin Zhao Yongzhu Fu Arumugam Manthiram College of Chemistry Zhengzhou UniversityZhengzhou450001PR China Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX78712United States

Lithium-metal batteries(LMBs)are considered as one of the most promising energy storage devices due to the high energy density and low reduction potential of the Li-metal ***,the growth of lithium dendrites results in accumulated dead Li and safety issues,limiting the practical application of ***_(3)is a well-known additive in lithium-sulfur batteries to regulate the solid-electrolyte interphase(SEI),effectively suppressing the redox shuttle of ***,other nitrates have been investigated in various electrolyte and battery systems,yielding improved SEI stability and cycling *** this review,we provide an overview of various nitrates,including LiNO_(3)for lithium batteries,focusing on their mechanisms and *** first discuss the effect of nitrate anions on SEI formation,as well as the cathode-electrolyte interphase(CEI).The solvation behavior regulated by nitrates is also extensively *** strategies to improve the solubility of LiNO_(3)in ester-based electrolytes are then summarized,followed by a discussion of recent progress in the application of nitrates in different ***,further research directions are presented,along with *** review provides a comprehensive understanding of nitrates and affords new and interesting ideas for the design of better electrolytes and battery systems.

关键词： Nitrate additive Lithium battery Mechanism Application