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Euro Powder Metallurgy 2023 Congress and Exhibition, PM 2023

作者： Gomes, Uilame Umbelino de Araújo, Kívia Fabiana Galvão José, Maria Lima, Santos De Souza, Vitor Manoel Silva Fernandes da Silva Lourenço, Cléber Raimundo, Rafael Alexandre Materials Science and Engineering Postgraduate Program Federal University of Rio Grande do Norte Natal59078-970 Brazil Department of Physics Federal University of Paraíba João Pessoa58051-900 Brazil

Copper niobate (CuNb2O6) has been studied for technological and environmental applications, such as in solar cells and photocatalysts, for example. And to make the application of CuNb2O6 even more feasible, in this study, therefore, high-energy milling was applied in its synthesis process with variation in the milling time, from the precursor powders Nb2O5 and CuO. The calcination occurred in a muffle with temperatures in the range of 500 °C to 1000 °C, for 3 h and heating rate of 5 °/min. Then, the powders were characterized by XRD, SEM, EDS and Raman. The powders showed crystallite sizes smaller than 80 nm, good homogeneity and high purity. The particle morphologies and the Raman spectrum are coherent with the literature. It was also verified that the increase in milling time reduced the initial formation temperature of the monoclinic phase and the calcination time for the complete formation of the orthorhombic phase. © European Powder Metallurgy Association (EPMA)

关键词： mechanical alloying

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A review of solar chimney for natural ventilation of residential and non-residential buildings

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SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS 2022年第PartB期52卷

作者： Maghrabie, Hussein M. Abdelkareem, Mohammad Ali Elsaid, Khaled Sayed, Enas Taha Radwan, Ali Rezk, Hegazy Wilberforce, Tabbi Abo-Khalil, Ahmed G. Olab, A. G. [a]Department of Mechanical Engineering Faculty of Engineering South Valley University Qena 83521 Egypt [b]Dept. of Sustainable and Renewable Energy Engineering University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates [c]Center for Advanced Materials Research University of Sharjah PO Box 27272 Sharjah United Arab Emirates [d]Faculty of Engineering Minia University Elminia Egypt [e]Chemical Engineering Department Texas A&M University College Station TX 77843-3122 USA [f]Mechanical Power Engineering Department Mansoura University El-Mansoura 35516 Egypt [g]College of Engineering at Wadi Addawaser Prince Sattam Bin Abdulaziz University Saudi Arabia [h]Mechanical Engineering and Design Aston University School of Engineering and Applied Science Aston Triangle Birmingham B4 7ET United Kingdom [i]Sustainable Energy & Power Systems Research Centre RISE University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates

The requirement for passive cooling strategies in buildings has great attention in almost all countries, where hot temperatures are predominant throughout the year. The ventilation process is a crucial necessity for a healthy lifestyle and its significance is additionally highlighted through the contemporary universal outbreak of Covid19. One of the promising applications for cooling residential buildings is the solar chimney (SC) that is particularly convenient for hot and humid climates. The solar chimney is a natural draught passive method that utilizes available solar energy to build up the stack pressure. The solar chimney participates in elevating the cooling and heating efficiency of residential/non-residential spaces. The present article introduces an overview of the operation and performance of the SC. Studying the potential design and operating parameters influencing the SC performance for natural ventilation (NV) compared to the electrical high-energy technologies to sustain the acceptable indoor climatic conditions is important. As well, the natural ventilation for harsh climate conditions using SC only is not applicable so the enhanced solar ventilation systems are studied. Combined enhanced cooling/heating energy systems based on the solar chimney are considered as an effective strategy towards low energy consuming buildings.

关键词： Solar chimney Natural ventilation Thermal comfort Residential non-residential buildings ACH

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Experimental Study on the Microstructure and mechanical Properties of the Mg-Y-Zn Alloys with Lpso Phases Tailored by Calphad Method

SSRN

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SSRN 2023年

作者： Li, Changrong Ruan, Yongxin Xia, Shibing Guo, Cuiping Du, Zhenmin School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China School of Mechanical Engineering Xinjiang University Urumqi830046 China

Long-Period Stacking Ordered (LPSO) phases in the Mg-Y-Zn alloys can significantly improve comprehensive mechanical properties of the Mg-based alloys. The nominal compositions of the Mg95Y3Zn2 and Mg86Y8Zn6 (at%) alloys with different contents of LPSO phases were tailored by CALPHAD method, and the tested compositions of these two alloys were Mg95.2Y2.6Zn2.2 and Mg86.2Y7.7Zn6.1, respectively. The microstructure evolutions of the studied alloys in the states of as-cast and isothermal treatments at different times were observed, and the mechanical properties of the as-extruded alloys after homogenization (short term, 12 h) and the isothermal treatment (long term, 240 h) at 500 °C were measured. After the isothermal treatment at 500 °C for 240 h, the phase constituent of the Mg95.2Y2.6Zn2.2 alloy changed from the as-cast three phases (18R + α-Mg + W-Mg3Y2Zn3) into the equilibrium three phases (18R + α-Mg + 14H), while that of the Mg86.2Y7.7Zn6.1 alloy completely changed from the as-cast four phases (18R + α-Mg + W-Mg3Y2Zn3 + 14H) into the equilibrium two LPSO phases (18R + 14H), where the 14H-type LPSO phase is formed by the solid transition of "18R + α-Mg + W-Mg3Y2Zn3 → 14H". The results of mechanical properties show that the strength of the Mg86.2Y7.7Zn6.1 alloy composed entirely of LPSO phases is better than that of the Mg95.2Y2.6Zn2.2 alloy composed of LPSO phases and some α-Mg matrix, while the plasticity of the Mg86.2Y7.7Zn6.1 alloy is not as good as that of the Mg95.2Y2.6Zn2.2 alloy. Therefore, the amount of LPSO phases can be increased for pursuing high strength of Mg alloys, but a certain amount of α-Mg phase needs to be kept for retaining good plasticity. © 2023, The Authors. All rights reserved.

关键词： Magnesium alloys

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Mass transport in a highly immiscible alloy on extended shear deformation

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Journal of materials science & Technology 2023年第3期134卷 197-208页

作者： Miao Song Jia Liu Xiaolong Ma Qin Pang Matthew J.Olszta Joshua Silverstein Madhusudhan R.Pallaka Peter V.Sushko Suveen N.Mathaudhu Cynthia Powell Arun Devaraj Bharat Gwalani Physical and Computational Sciences Directorate Pacific Northwest National Laboratory902 Battelle BoulevardRichlandWA 99354USA Energy and Environmental Directorate Pacific Northwest National Laboratory902 Battelle BoulevardRichlandWA 99354USA Material Science and Engineering Program University of CaliforniaRiversideCA92521USA Colorado School of Mines 1500 Illinois St.GoldenCO 8040USA Department of Materials Science and Engineering North Carolina State UniversityRaleighNC27695-7907USA State Key Laboratory of Powder Metallurgy Central South Uni-versityChangsha 410083China

Forced mixing to a single-phase or supersaturated solid solution(SSS)and its prerequisite microstructure evolution in immiscible systems has been a focus of research for fundamental science and practical *** the formation of SSS by shear deformation could enable a material design beyond conventional equilibrium microstructure in immiscible ***,a highly immiscible Cu-50 at.%Cr binary alloy(mixing enthalpy of∼20 kJ mol^(−1))was employed to investigate the microstructure evolution and localized tendencies of SSS during severe shear *** results demonstrate the dislocation mediated microstructural refinement process in each phase of the binary alloy and the mechanisms associated with localized solute supersaturation as a function of shear *** grain refinement in the softer Cu phase occurs owing to the strain localization driving the preferential dynamic *** grain refinement of the Cr phase,however,is enabled by the progressive evolution of grain lamination,splitting,and fragmentation as a function of shear *** solute supersaturation is found to be strongly dependent on the local environments that affect the dislocation activity,including the level of microstructure refinement,the interfacial orientation relationship,the mechanical incompatibility,and the localized preferential phase *** initio simulations confirm that it is more favorable to oxidize Cr than Cu at incoherent Cu/Cr interfaces,limiting the mass transport on an incoherent *** results unveil the mechanism underpinning the non-equilibrium mass transport in immiscible systems upon severe deformation that can be applied to produce immiscible alloys with superior mechanical properties.

关键词： Tribology Immiscible alloys Nanostructures Shear deformation Forced mixing Atom probe

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ENHANCED mechanical PROPERTIES OF HIERARCHICAL MXENE/CF COMPOSITES VIA LOW CONTENT ELECTROPHORETIC DEPOSITION 20

ENHANCED MECHANICAL PROPERTIES OF HIERARCHICAL MXENE/CF COMP...

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20th European Conference on Composite materials: Composites Meet Sustainability, ECCM 2022

作者： Hu, Yi Pang, Shaojie Li, Jialiang Jiang, Jianjun Papageorgiou, Dimitrios G. School of Engineering and Materials Science Queen Mary University of London LondonE1 4NS United Kingdom School of Mechanical Engineering Northwestern Polytechnical University Xi'an710072 China

ISBN: (纸本)9782970161400

The weak fiber-matrix interface is a bottleneck hindering the development of carbon fiber composites. In this work, an optimized electrophoretic deposition (EPD) approach was explored to improve the interface by depositing uniformly two-dimensional MXene (Ti3C2Tx) nanoparticles onto the surface of carbon fibers (CF). The MXene-CF hybrids were then used to fabricate continuous carbon fiber reinforced polymer (CFRP) composites. The results manifested that the presence of MXene nanoparticles on the CF surfaces could significantly increase the fiber surface energy and wettability, as well as their surface roughness. As a result, a remarkable increase of the interfacial strength and flexural properties of CFRP has been observed. The functionalized MXene-CF-epoxy composites witnessed a prominent enhancement of interlaminar shear strength (ILSS), flexural strength and monofilament tensile strength compared to their unfunctionalized counterparts (i.e., 75%, 50.4%, and 32.7%). The versatile EPD strategy proposed herein, constitutes a promising approach for CFRP modification that can lead to significantly improved performance. © 2022 Papageorgiou et al.

关键词： Tensile strength

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Low-leakage-current and improved thermal stability of normally-OFF hydrogen-terminated diamond FET via boron nitride passivation

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Diamond and Related materials 2025年 157卷

作者： Yang, Mingyang Hu, Youwang Duan, Yongxin Shen, Yi Sun, Xiaoyan Nishimura, Kazuhito Xu, Yuehang Chee, Kuan W.A. Guo, Liangchao Jiang, Nan Yuan, Qilong State Key Laboratory of Precision Manufacturing for Extreme Service Performance College of Mechanical and Electrical Engineering Central South University Changsha410083 China Key Laboratory of Advanced Marine Materials Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu611731 China National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei230026 China College of Mechanical Engineering Yangzhou University Yangzhou225127 China

Normally-OFF hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with low leakage current is highly desirable for energy-saving switching applications. Metal/H-diamond FET with Schottky gate exhibits potential application advantages, owing to its excellent switching speed and small subthreshold swing. However, a lower interface barrier height (Schottky junction) typically results in high leakage current and poor thermal stability. In this work, a normally-OFF H-diamond metal/insulator/semiconductor-metal/semiconductor hybrid gate FET (MIS-MES HGFET) was achieved by nano‑boron nitride (nano-BN) passivation at the Al/H-diamond interface to reduce leakage currents. The results achieved a low OFF-state drain-source current density of ∼10−9 mA/mm. And the gate leakage current was suppressed by up to 6 orders of magnitude compared to FETs without nano-BN passivation. An ON/OFF ratio of 3.3 × 109 was also obtained for devices with a gate length of 4 μm, the subthreshold swing is 102 mV/dec, and the maximum drain current density is −8.6 mA/mm. Encouragingly, this FET still exhibited improved thermal stability at high temperatures. At 450 K, the device maintained an ON/OFF ratio of ∼1 × 109 and low leakage currents of ∼10−9 mA/mm for both gate and OFF-state drain-source. In contrast, the counterpart device without nano-BN passivation failed at only 425 K. Such improvements can be attributed to the excellent passivation and insulating properties of BN, which not only enhance the Schottky barrier height at the Al/H-diamond interface but also serve as a gate insulator to effectively suppress tunneling-induced leakage current. Results of this work can promote the development of diamond FETs for energy-saving and high-temperature applications. © 2025 Elsevier B.V.

关键词： MISFET devices

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Numerical simulation of surface topography evolution during pulsed CO2 laser ablation of fiber 6

Numerical simulation of surface topography evolution during ...

引用

6th International Symposium on Laser Interaction with Matter

作者： Hu, Chang Wu, Han Ma, Xiuquan School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China The State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Guangdong Intelligent Robotics Institute 523808 China

ISBN: (纸本)9781510660236

D-shaped fiber manufacturing by mechanical grinding or chemical acid will inevitably introduce subsurface damages or impurity during processing. Laser ablation has been proven to be a high-efficiency non-contact technique that can achieve a low-defect surface. However, the process of laser processing fiber involves the phase change of the material, which leads to a very complicated evolution process of the surface topography of the fiber. In order to predict the surface topography of fiber during irradiation by pulse laser. Herein, a 3D model has been established to assist the understanding of the thermal mechanism of pulsed CO2 laser ablation and phase change of evaporation during ablation. Furthermore, the temperature characteristics of the fiber surface during the laser irradiation are also analyzed. The simulation results show that from the second pulse, the ablation depth is basically stable, and the texture formed on the fiber surface is related to the processing parameters. © 2022 SPIE.

关键词： Laser ablation

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Characterization of Anisotropic Lattice Structured Phantoms Using 3D-Rotational Shear Wave Elasticity Imaging (3D-RSWEI)

Characterization of Anisotropic Lattice Structured Phantoms ...

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IEEE International Symposium on Applications of Ferroelectrics (ISAF)

作者： Shruthi Srinivasan Daniel Yoon Margrethe Ruding Kevin Eckstein Ned C. Rouze Wren E. Wightman Mark L. Palmeri David P. Bradway Derek Y. Chan Kaden D. Bock Philip V. Bayly Kathryn R. Nightingale Department of Biomedical Engineering Duke University Durham NC United States Mechanical Engineering and Materials Science Washington University St. Louis MO United States

ISBN: (数字)9798350371901

ISBN: (纸本)9798350371918

We present a 3D-RSWEI characterization of anisotropic lattice phantoms. Shear wave speeds versus rotational angle were measured while the lattices were submerged in water and after embedding in a softer, isotropic polyvinyl alcohol cryogel. In both cases, shear wave propagation was anisotropic and fit to an ellipse, with faster wave speeds observed along the material symmetry direction. Measured shear wave speeds and shear anisotropy decreased between lattices in water versus embedded in PVA. Linear wave dispersion slopes were higher along versus across the material symmetry direction. Measured speed of sound was higher and acoustic attenuation was lower than that of biological tissue. These results showcase applicability of 3D-RSWEI to characterize novel anisotropic lattice phantoms.

关键词： Fabrication Protocols Anisotropic magnetoresistance Lattices Phantoms Anisotropic NIST Imaging phantoms Acoustics Dispersion

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Microscale photoacoustic spectroscopy using integrated photonics for lab-on-chip applications

Microscale photoacoustic spectroscopy using integrated photo...

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Photons Plus Ultrasound: Imaging and Sensing 2021

作者： Singh, Robin Agarwal, Anu Anthony, Brian W. Department of Mechanical Engineering Institute for Medical Engineering and Science Mit Nano Department of Materials Science and Engineering Microphotonics Center Materials Research Laboratory Massachusetts Institute of Technology CambridgeMA United States

ISBN: (数字)9781510641204

ISBN: (纸本)9781510641198

We propose a microscale photoacoustic hardware architecture using silicon photonics. The system builds on a platform that monolithically integrates on-chip light excitation and ultrasound detection of photoacoustic signal. The device uses a waveguide terminating with a meta grating structure to engineer an excitation beam profile. The ultrasound receiver is based on a photonic ring resonator that sits on top of mechanical membrane. The pressure wave impinging on the membrane deflects the ring resonator resulting in change in optical readout. We believe the method is scalable to develop low-cost ultra-highly sensitive photoacoustic sensors for applications such as PA imaging, spectroscopy, and microscopy. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Silicon photonics

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Generalizability of Graph Neural Network Force Fields for Predicting Solid-State Properties

arXiv

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arXiv 2024年

作者： Mohanty, Shaswat Wang, Yifan Cai, Wei Department of Mechanical Engineering Stanford University CA94305-4040 United States Department of Materials Science and Engineering Stanford University CA94305-4040 United States

Machine-learned force fields (MLFFs) promise to offer a computationally efficient alternative to ab initio simulations for complex molecular systems. However, ensuring their generalizability beyond training data is crucial for their wide application in studying solid materials. This work investigates the ability of a graph neural network (GNN)based MLFF, trained on Lennard-Jones Argon, to describe solid-state phenomena not explicitly included during training. We assess the MLFF’s performance in predicting phonon density of states (PDOS) for a perfect face-centered cubic (FCC) crystal structure at both zero and finite temperatures. Additionally, we evaluate vacancy migration rates and energy barriers in an imperfect crystal using direct molecular dynamics (MD) simulations and the string method. Notably, vacancy configurations were absent from the training data. Our results demonstrate the MLFF’s capability to capture essential solid-state properties with good agreement to reference data, even for unseen configurations. We further discuss data engineering strategies to enhance the generalizability of MLFFs. The proposed set of benchmark tests and workflow for evaluating MLFF performance in describing perfect and imperfect crystals pave the way for reliable application of MLFFs in studying complex solid-state materials. © 2024, CC BY.

关键词： Phonons

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