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SSRN 2023年

作者： Ha, Hojin Ham, Sangwoo Ehsan, Adeeb Lee, Jeong Wan Interdisciplinary Program in Biohealth-Machinery Convergence Engineering Kangwon National University 1 Kangwondaehak-gil Gangwon-do Chuncheon-si24341 Korea Republic of Division of Mechanical & Biomedical Mechatronics and Materials Science and Engineering Kangwon National University 1 Kangwondaehak-gil Gangwon-do Chuncheon-si24341 Korea Republic of Kangwon Institute of Inclusive Technology Kangwon National University 1 Kangwondaehak-gil Gangwon-do Chuncheon-si24341 Korea Republic of

In this study, we aim to address the challenges of micro-hydropower generation in low-head environments. The authors reviewed and assessed various factors affecting the feasibility of micro-hydro systems, such as geographical constraints, construction costs, and grid connectivity. To overcome the limitations of conventional hydro turbines in such conditions, the authors proposed a novel cross-flow turbine. Initially, they designed and analyzed an inverted cross-flow turbine based on design rules established by previous researchers and performed numerical analyses. Four steps parametric studies were conducted to achieved optimum turbine values, such as runner diameter ratio and the number of blades, considering the maximum efficiency point from the previous step. The best efficiency point of the optimized design turbine was 72.92 % at a runner rotational speed of 170 RPM with a 0.75 runner diameter ratio and 35 blades. To validate the optimized design, the authors compared it with the initial design using hill charts and numerical values obtained from parametric studies. Overall, this research demonstrates the usefulness of computational fluid dynamics simulations and parametric studies in optimizing the design of an inverted cross-flow turbine under low head conditions. © 2023, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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H2O2-free catalytic dye degradation at dye/night circumstances using CuS@Au heterostructures decorating on MoS2 nanoflowers

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Journal of Alloys and Compounds 2024年 1002卷

作者： Hsiao, Po-Hsuan Lin, Kuan-Han Lee, Yu-Shen Liao, Pin-Chao Juan, Joon Ching Chen, Chia-Yun Department of Materials Science and Engineering National Cheng-Kung University Tainan701 Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan70101 Taiwan Nanotechnology & Catalysis Research Centre Institute for Advanced Studies University of Malaya Kuala Lumpur50603 Malaysia Research Center National Cheng Kung University No.1 University Road Tainan701 Taiwan

Catalytic remediation of industrial organic pollutants is considered effective mitigation of increasing risks from aqueous contaminations composed of hazardous substances. The need for in-situ environmental remediation is highly demanded to deal with organic contaminations from on-site, instant, and full-time treatment without the need to remove the contaminated sources for ex-situ remediation is highly demanded. In this work, by means of combining the strategies of daytime and dark degradation capabilities of organic dyes, the MoS2/Au@CuS hybrid catalysts resembling semiconductor/metal/semiconductor junction features underline the generation of hydroxyl radicals, and force to speed up the oxidative removal of organic dyes during light-on and light-off conditions in both scenarios. Decorations of CuS on hydrothermally synthesized MoS2/Au nanoflowers are prepared with the in-situ chemical reduction process. We reveal that such circumstance exists when programming the environment in the sequence of light-on/light-off conditions, which actively clicks the generation of H2O2 and strategically accelerates the degradation kinetics, offering an additional opportunity for promoting catalytic degradation of hazardous organic dyes with whole-day feasibility. © 2024 Elsevier B.V.

关键词： Degradation

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Assessment of HVAF thermally sprayed coatings: Unraveling microstructural, electrochemical, and tribological performance using glass former Fe-Cr-Mo-Nb-B feedstock powder

Journal of Alloys and Metallurgical Systems

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Journal of Alloys and Metallurgical Systems 2024年 6卷

作者： Mota, I.G.C. Koga, G.Y. Rodrigues, L.C.M. Nascimento, A.R.C. Ettouil, F.B. Ferreira, T. Coimbrão, D.D. Kiminami, C.S. Bolfarini, C. Moreau, C. Botta, W.J. Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luis km 235 SP São CarlosCEP 13565-905 Brazil Federal University of São Carlos Department of Materials Science and Engineering Rod. Washington Luis km 235 SP São CarlosCEP 13565-905 Brazil Federal University of Sao Carlos Rodovia Washington Luiz km 235 SP-310 São Paulo São Carlos13565-905 Brazil Thermal Spray and Multiphase Flow Laboratory Concordia University MontrealQCH3G 1M8 Canada Department of Mechanical Industrial and Aerospace Engineering Concordia University 1455 de Maisonneuve Blvd. W MontrealQCH3G 1M8 Canada

In this paper the microstructural features of the glass former Fe68Cr8Mo4Nb4B16 coatings are unveiled and related to their electrochemical and tribological responses. The coating was mostly glassy with some embedded borides (M3B2, M2B-tetragonal;M being the metallic elements of the alloy) and ferrite. The tribological behavior of the HVAF coated sample, characterized by a thickness of about 200 µm, ∼6% porosity and a Vickers hardness of 357 HV0.5, was assessed in a sphere-on-plate configuration, revealing a specific wear rate of approximately 5 ×10−4 mm3∙N−1m−1. The wear mechanism was dominated by delamination caused by fragile intersplats. The corrosion resistance of HVAF coatings was evaluated in 0.6 M NaCl solution and compared with the results obtained for the crystalline Fe68Cr8Mo4Nb4B16 ingot, produced by melting in an induction furnace, and for the AISI 1020 steel substrate. The HVAF coating showed satisfactory corrosion resistance compared to the carbon steel substrate and the crystalline ingot, with the highest corrosion potential, Ecorr, values (−533 mVSCE) and the lowest corrosion current density, icorr, (10−6 A∙cm−2) followed by a clear passivation window upon anodic polarization in 0.6 M NaCl solution. Evaluations of HVAF coating showed a higher glassy content compared to the gas-atomized feedstock powders. This suggests that during spraying, certain particles were molten and experienced cooling rates adequate to inhibit crystallization, resulting in the freezing of the supercooled liquid. This phenomenon contributes to the good corrosion resistance observed in the present work and offers an opportunity to enhance the electrochemical behavior of HVAF coatings. © 2024 The Authors

关键词： Wear of materials

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Machine learning moment tensor potential for modeling dislocation and fracture in L10−TiAl and D019−Ti3Al alloys

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Physical Review materials 2023年第10期7卷 103602-103602页

作者： Ji Qi Z. H. Aitken Qingxiang Pei Anne Marie Z. Tan Yunxing Zuo M. H. Jhon S. S. Quek T. Wen Zhaoxuan Wu Shyue Ping Ong Materials Science and Engineering Program University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla California 92093-0448 USA Institute of High Performance Computing (IHPC) Agency for Science Technology and Research (A*STAR) 1 Fusionopolis Way Connexis #16-16 Singapore 138632 Republic of Singapore Department of NanoEngineering University of California San Diego 9500 Gilman Dr Mail Code 0448 La Jolla California 92093-0448 USA Department of Mechanical Engineering The University of Hong Kong Hong Kong SAR China Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR China Hong Kong Institute for Advanced Study City University of Hong Kong Hong Kong SAR China

Dual-phase γ-TiAl and α2−Ti3Al alloys exhibit high strength and creep resistance at high temperatures. However, they suffer from low tensile ductility and fracture toughness at room temperature. Experimental studies show unusual plastic behavior associated with ordinary and superdislocations, making it necessary to gain a detailed understanding on their core properties in individual phases and at the two-phase interfaces. Unfortunately, extended superdislocation cores are widely dissociated beyond the length scales practical for routine first-principles density-functional theory (DFT) calculations, while extant interatomic potentials are not quantitatively accurate to reveal mechanistic origins of the unusual core-related behavior in either phases. Here, we develop a highly accurate moment tensor potential (MTP) for the binary Ti-Al alloy system using a DFT dataset covering a broad range of intermetallic and solid solution structures. The optimized MTP is rigorously benchmarked against both previous and new DFT calculations, and unlike existing potentials, is shown to possess outstanding accuracy in nearly all tested mechanical properties, including lattice parameters, elastic constants, surface energies, and generalized stacking fault energies (GSFE) in both phases. The utility of the MTP is further demonstrated by producing dislocation core structures largely consistent with expectations from DFT-GSFE and experimental observations. The new MTP opens the path to realistic modeling and simulations of bulk lattice and defect properties relevant to the plastic deformation and fracture processes in γ-TiAl and α2−Ti3Al dual-phase alloys.

关键词： Interatomic & molecular potentials Alloys Machine learning

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Crystal structure-controlled synthesis of NiMoO4/NiO hierarchical microspheres for high-performance supercapacitors and photocatalysts

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Journal of Energy Storage 2024年 97卷

作者： Lee, Kuen-Chan Huang, Jen-Hsien Wu, Yen-Ju Wang, Kuan-Syun Cho, Er-Chieh Hsu, Shih-Chieh Liu, Ting-Yu Department of Science Education National Taipei University of Education No. 134 Sec. 2 Heping E. Road Da-an District Taipei City106 Taiwan Ph.D. Program in Medical Neuroscience College of Medical Science and Technology Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Department of Green Material Technology Green Technology Research Institute CPC Corporation No.2 Zuonan Rd. Nanzi District Kaohsiung City81126 Taiwan 1-2-1 Sengen Tsukuba Ibaraki305-0047 Japan Department of Materials Engineering Ming Chi University of Technology New Taipei City243303 Taiwan School of Pharmacy College of Pharmacy Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Department of Chemical and Materials Engineering Tamkang University No. 151 Yingzhuan Road Tamsui District New Taipei City25137 Taiwan Department of Chemical Engineering and Materials Science Yuan Ze University Taoyuan City32003 Taiwan College of Engineering & Center for Sustainability and Energy Technologies Chang Gung University Taoyuan33302 Taiwan

Global environmental challenges and energy crises have driven researchers to develop multifunctional and highly efficient nanomaterials. This study presents dual-functional NiMoO4 (NMO)/NiO hierarchical microspheres that can serve as supercapacitors and photocatalysts prepared using a microwave-assisted hydrothermal method. The α- and β-phase contents of NMO can be regulated by controlling the post-annealing temperature and pH value of the precursor solution. The as-prepared NMO/NiO nanocomposites exhibited dual Faradaic redox reactions attributed to NMO and NiO, leading to remarkable supercapacitor performance. In addition, the constructed heterojunction between NMO and NiO also improved charge separation, leading to excellent photocatalytic capability. Based on the results, NMO with a higher β-phase content showed better supercapacitive and photocatalytic performance owing to its higher conductivity. The optimal NMO/NiO composite displayed a specific capacitance of 943 F g−1 at 1 A/g and excellent cycling stability, with 83.1 % retention at 5 A/g after 4000 cycles. Additionally, it demonstrated an outstanding photocatalytic capability for the degradation of methylene blue (MB), achieving a rate constant of (0.0113 min−1). © 2024 Elsevier Ltd

关键词： Supercapacitor

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Anomalous properties of spark plasma sintered boron nitride solids

arXiv

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arXiv 2024年

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King’s College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory United States

Hexagonal boron nitride (h-BN) is brittle, however, its atomic-scale structural engineering can lead to unprecedented physical properties. Here we report the bulk synthesis of high-density crystalline h-BN solids by using high-temperature spark plasma sintering (SPS) of micron size h-BN powders. In addition to the high mechanical strength and ductile response of such materials, we have obtained anomalous values of dielectric constant beyond theoretical limits, high thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and anomalous properties. Our findings highlight the importance of material design, via new approaches such as twisting and interconnections between atomically thin layers, to create novel ceramics with properties that could go beyond their intrinsic theoretical predictions. © 2024, CC BY.

关键词： Spark plasma sintering

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A temperature or FUV tracer? The HNC/HCN ratio in M83 on the GMC scale

arXiv

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arXiv 2024年

作者： Harada, Nanase Saito, Toshiki Nishimura, Yuri Watanabe, Yoshimasa Sakamoto, Kazushi National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-1855 Japan Department of Astronomy The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Materials Science and Engineering College of Engineering Shibaura Institute of Technology 3-7-5 Toyosu Koto-ku Tokyo135-8548 Japan Institute of Astronomy and Astrophysics Academia Sinica 11F of AS/NTU Astronomy-Mathematics Building No.1 Sec. 4 Roosevelt Rd Taipei10617 Taiwan

The HNC/HCN ratio is observationally known as a thermometer in Galactic interstellar molecular clouds. A recent study has alternatively suggested that the HNC/HCN ratio is affected by the ultraviolet (UV) field, not by the temperature. We aim to study this ratio on the scale of giant molecular clouds in the barred spiral galaxy M83 towards the southwestern bar end and the central region from ALMA observations, and if possible, distinguish the above scenarios. We compare the high (40-50 pc) resolution HNC/HCN ratios with the star formation rate from the 3-mm continuum intensity and the molecular mass inferred from the HCN intensities. Our results show that the HNC/HCN ratios do not vary with the star formation rates, star formation efficiencies, or column densities in the bar-end region. In the central region, the HNC/HCN ratios become higher with higher star formation rates, which tend to cause higher temperatures. This result is not consistent with the previously proposed scenario in which the HNC/HCN ratio decreases with increasing temperature. Spectral shapes suggest that this trend may be due to optically thick HCN and optically thin HNC. In addition, we compare the large-scale (∼ 200 pc) correlation between the dust temperature from the FIR ratio and the HNC/HCN ratio for the southwestern bar-end region. The HNC/HCN ratio is lower when the dust temperatures are higher. We suggest from the above results that the HNC/HCN ratio depends on the UV radiation field that affects the interstellar medium on the ∼ 100 pc scale where the column densities are low. © 2024, CC BY.

关键词： Dust

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Numerical Simulation of Thermo-Solutal Marangoni Convection in a Floating Half-Zone with Radiation Effects Under Zero Gravity

SSRN

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SSRN 2022年

作者： Jin, Chihao Okano, Yasunori Minakuchi, Hisashi Dost, Sadik Department of Materials Engineering Science Osaka University 1-3 Machikaneyama Osaka Toyonaka560-8531 Japan Mechanical Engineering Program School of Engineering University of the Ryukyus 1 Senbaru Nishihara Okinawa903-0213 Japan Crystal Growth Laboratory University of Victoria VictoriaBCV8W 3P6 Canada

Numerical simulations of thermo-solutal Marangoni convection in a floating half SiGe zone with radiation effects under zero gravity have been carried out. In this system, thermal and solutal Marangoni flows develop along the free surface either in the same direction or opposite directions depending on the directions of thermal and solutal gradients. In this simplified model of a liquid bridge, the ambient temperature is kept constant, and the radiation effects of heat loss and heat gain are considered as the dominant heat transfer from the ambience. By investigating the radiation effects at unequal or equal (MaC, MaT) values, the transition mode maps mainly based on the concentration distribution with respect to Marangoni number ratio (Rσ =MaT/MaT) and ambient temperature (Ta) have been proposed. The maps show the main concentration structures and potential transition tendencies at various Ta values. The opposite thermo-solutal Marangoni flows give rise to more complex structures than those of the same-direction flows. Both heat loss and heat gain have a significant effect on alteration or destabilizing of the concentration distribution. To some extent, the heat loss in the opposite-direction flow has a stabilizing effect on the azimuthal wave pattern at a lower or higher Rσ © 2022, The Authors. All rights reserved.

关键词： Radiation effects

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Improving the Performance of Asphalt Mixtures with Highly Acidic Aggregates in Central Vietnam Using Modifier Based on Styrene-Butadiene-Styrene and Rosin Resin

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Journal of materials in Civil engineering 2025年第7期37卷

作者： Nguyen, Lan Ngoc Lee, Hosin David Bui, Lam Tung Kim, Young-Ik Truong, Van Quyet Nguyen, May Huu Nguyen, Du Van Dept. of Construction Materials Faculty of Construction Engineering Univ. of Transport and Communications No. 03 Cau Giay Hanoi100000 Viet Nam Dept. of Civil and Environmental Engineering Iowa Technology Institute The Univ. of Iowa Iowa CityIA52242 United States Research Dept. Hansoo Natech Co. Ltd. 6-20 Yuseong-daero 1205beon-gil Yuseong-gu Daejeon34104 Korea Republic of Civil and Environmental Engineering Program Graduate School of Advanced Science and Engineering Hiroshima Univ. 1-4-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8527 Japan Faculty of Civil Engineering Univ. of Transport and Communications Campus in Ho Chi Minh City Ho Chi Minh City700000 Viet Nam

In Central Vietnam, the aggregate typically originates from highly acidic rocks containing a significant amount of silicon dioxide (SiO2), leading to poor adhesion quality with virgin asphalt binder. Hence, the asphalt mixture production usually needs to utilize adhesion promoters. Based on the chemical compositions of the sample aggregate (up to 72.3% SiO2), research has been conducted to introduce an adhesive agent called rubber modified compound (RMC-160), which is composed of styrene-butadiene-styrene (SBS) with petroleum hydrocarbon resin, treated clay and mineral oil. This article presents the research findings regarding the adhesion effectiveness of RMC-160-modified asphalt binder to high acid-based aggregate through laboratory and field tests, along with the mixture performance under both short-term oven aging (STOA) and long-term oven aging (LTOA). The test results exhibited remarkable effects, whereby the asphalt binder modified with RMC-160 additive significantly increased the adhesion level from Grade 2 to Grade 4, and the asphalt mixtures containing RMC-160 had lower rutting and higher cracking tolerance (CTIndex) under both the STOA and LTOA conditions. © 2025 American Society of Civil Engineers.

关键词： Silicon oxides

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Evidence for Two-Stage Hardening in an Al-Zn-Mg-Cu Alloy Processed by High-Pressure Torsion

SSRN

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SSRN 2022年

作者： dos Santos, Igor Cuzzuol Mazzer, Eric M. Figueiredo, Roberto B. Langdon, Terence G. Rodrigues Pereira, Pedro Henrique Graduate Program in Metallurgical Materials and Mining Engineering Universidade Federal de Minas Gerais MG Belo Horizonte31270-901 Brazil Department of Materials Science and Engineering Universidade Federal de São Carlos SP São Carlos13565-905 Brazil Department of Metallurgical and Materials Engineering Universidade Federal de Minas Gerais MG Belo Horizonte31270-901 Brazil Materials Research Group Department of Mechanical Engineering University of Southampton SouthamptonSO17 1BJ United Kingdom

Experiments were conducted to assess the effect of torsional straining on the microstructural evolution of an Al-5.7Zn-1.8Mg-2.1Cu alloy containing dispersed second phase particles prior to deformation. The results show that the material exhibits two distinct and consecutive hardening stages when processed through 1/8, 1, 5, 30, 50 and 100 turns in high-pressure torsion (HPT). There is an initial increase in the Vickers hardness from ~120 Hv in the unprocessed state to ~240 Hv after 1 turn. In this first stage, hardening occurs primarily through the accumulation and rearrangement of dislocations into fine cells/subgrains. A quasi-stationary condition is achieved with further straining where the microhardness remains nearly constant and the grain size is ~140 nm up to 30 revolutions. Thereafter, the microstructure consists of ultrafine and slightly elongated grains but the second phases are continuously fragmented. This fragmentation produces a new hardening stage and the development of a uniform array of highly elongated grains with an average size of ~93 nm after 100 HPT turns. It is shown that this two-stage hardening is consistent with conventional Hall-Petch strengthening and the development of the second stage is attributed to a reduction in grain boundary mobility due to the segregation of solutes. © 2022, The Authors. All rights reserved.

关键词： Aluminum alloys

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