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Enhancing the thermal conductivity of semiconductor thin films via phonon funneling

npj Computational materials 2024年第1期10卷 1414-1422页

作者： C.Jaymes Dionne Sandip Thakur Nick Scholz Patrick Hopkins Ashutosh Giri Department of Mechanical Industrialand Systems EngineeringUniversity of Rhode IslandKingston02881 RIUSA Department of Mechanical and Aerospace Engineering University of VirginiaCharlottesville22904 VAUSA Department of Materials Science and Engineering University of VirginiaCharlottesville22904 VAUSA Department of Physics University of VirginiaCharlottesville22904 VAUSA

The second law of thermodynamics asserts that energy diffuses from hot to *** resulting temperature gradients drive the efficiencies and failures in a plethora of ***,as the dimensionalities of materials shrink to the nanoscale regime,proper heat dissipation strategies becomemore challenging since the mean free paths of phonons become larger than the characteristic length *** leads to temperature gradients that are dependent on interfaces and boundaries,which ultimately can lead to severe thermal ***,we uncover a phenomenon which we refer to as‘phonon funneling’,that allows the control of phonon transport to preferentially direct phonon energy away from geometrically confined interfacial thermal bottlenecks and into localized colder *** phenomenon supersedes heat diffusion based on the macroscale temperature gradients,thus introducing a nanoscale regime in which boundary scattering increases the phonon thermal conductivity of thin films,an opposite effect than what is traditionally *** work advances the fundamental understanding of phonon transport at the nanoscale and the role of efficient scattering methods for enhancing thermal transport.

关键词： thermal conductivity films

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Effects of Interface Anisotropy on the Solidification Morphology of Zinc Alloys and Development of Data Assimilation for Their Estimation

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Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan 2025年第6期111卷 326-335页

作者： Yamamura, Ayano Yasuda, Hideyuki Takaki, Tomohiro Graduate School of Science and Technology Kyoto Institute of Technology Japan Department of Materials Science and Engineering Kyoto University Japan Faculty of Mechanical Engineering Kyoto Institute of Technology Japan

The solid–liquid interface energy anisotropy of Zn alloys remains poorly understood. Recently, characteristic 14-arm dendritic growth has been observed using time-resolved X-ray computed tomography at SPring-8 during the solidification of a Zn–4mass%Al alloy. This study investigates the dependence of the dendrite morphologies of Zn alloys on solid–liquid interface energy anisotropy through systematic phase-field simulations of the growth of an isolated equiaxed dendrite. We also develop a data assimilation system to estimate the anisotropy parameters of solid–liquid interface energy and crystal orientation in Zn alloys and validate the system through twin experiments. This study provides insights into the solidification of Zn alloys and a powerful tool for their investigation. © 2025 The Iron and Steel Institute of Japan.

关键词： data assimilation dendrite phase-field method solidification solid–liquid interface energy zinc alloy

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Sustainable materials and Decarbonization Prospects in Battery Technologies

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ACS APPLIED ENERGY materials 2024年第8期7卷 3018-3020页

作者： Ramasubramanian, Brindha Prasada Rao, Rayavarapu Dalapati, Goutam Kumar Adams, Stefan Ramakrishna, Seeram Center for Nanofibers & Nanotechnology Department of Mechanical Engineering College of Design and Engineering National University of Singapore Singapore 117574 Singapore Department of Materials Science and Engineering College of Design and Engineering National University of Singapore 117574 Singapore

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Prediction and optimisation of gasoline quality in petroleum refining: The use of machine learning model as a surrogate in optimisation framework

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CAAI Transactions on Intelligence Technology 2024年第5期9卷 1185-1198页

作者： Husnain Saghir Iftikhar Ahmad Manabu Kano Hakan Caliskan Hiki Hong School of Chemical and Materials Engineering National University of Sciences and TechnologyIslamabadPakistan Department of Systems Science Kyoto UniversityKyotoJapan Department of Mechanical Engineering Faculty of Engineering and Natural SciencesUsak UniversityUsakTurkey Department of Mechanical Engineering Kyung Hee UniversityYonginRepublic of Korea

Hardware-based sensing frameworks such as cooperative fuel research engines are conventionally used to monitor research octane number (RON) in the petroleum refining industry. Machine learning techniques are employed to predict the RON of integrated naphtha reforming and isomerisation processes. A dynamic Aspen HYSYS model was used to generate data by introducing artificial uncertainties in the range of ±5% in process conditions, such as temperature, flow rates, etc. The generated data was used to train support vector machines (SVM), Gaussian process regression (GPR), artificial neural networks (ANN), regression trees (RT), and ensemble trees (ET). Hyperparameter tuning was performed to enhance the prediction capabilities of GPR, ANN, SVM, ET and RT models. Performance analysis of the models indicates that GPR, ANN, and SVM with R2 values of 0.99, 0.978, and 0.979 and RMSE values of 0.108, 0.262, and 0.258, respectively performed better than the remaining models and had the prediction capability to capture the RON dependence on predictor variables. ET and RT had an R2 value of 0.94 and 0.89, respectively. The GPR model was used as a surrogate model for fitness function evaluations in two optimisation frameworks based on genetic algorithm and particle swarm method. Optimal parameter values found by the optimisation methodology increased the RON value by 3.52%. The proposed methodology of surrogate-based optimisation will provide a platform for plant-level implementation to realise the concept of industry 4.0 in the refinery.

关键词： genetic algorithms mach in ne learning multi-objective optimisation

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Evolution of nonmetallic inclusions in 80-t 9CrMoCoB large-scale ingots during electroslag remelting process

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International Journal of Minerals,Metallurgy and materials 2024年第7期31卷 1525-1539页

作者： Shengchao Duan Min Joo Lee Yao Su Wangzhong Mu Dong Soo Kim Joo Hyun Park School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China Department of Materials Science and Chemical Engineering Hanyang UniversityAnsan 15588Rep.of Korea Department of Materials Science and Engineering KTH Royal Institute of TechnologyBrinellvägen 23Stockholm 10044Sweden Department of Engineering Science and Mathematics Division of Materials ScienceLuleåUniversity of Technology97187 LuleåSweden Casting&Forging Business Unit Nuclear Business GroupDoosan EnerbilityChangwon 51711Rep.of Korea

In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR *** main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS *** Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification ***,inclusions can act as nucleation sites for carbide layer *** ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted *** M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy *** substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)***,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)*** Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid *** increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag.

关键词： nonmetallic inclusion heat-resistant steel electroslag remelting M_(23)C_(6) carbide MnS inclusion supersaturation degree

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Variable Admittance Control of High Compatibility Exoskeleton Based on Human-Robotic Interaction Force

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Chinese Journal of mechanical engineering 2024年第5期37卷 409-423页

作者： Jian Cao Jianhua Zhang Chang Wang Kexiang Li Jianjun Zhang Guihua Wang Hongliang Ren School of Mechanical Engineering Hebei University of TechnologyTianjin 300401China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China Department of Electronic Engineering The Chinese University of Hong KongHong Kong 999077NTChina

The wearable exoskeleton system is a typical strongly coupled human-robotic ***-robotic is the environment for each *** two support each other and compete with each *** high human-robotic compatibility is the most critical technology for wearable *** structural compatibility can improve the intrinsic safety of the exoskeleton,and precise intention understanding and motion control can improve the comfort of the *** paper first designs a physiologically functional bionic lower limb exoskeleton based on the study of bone and joint functional anatomy and analyzes the drive mapping model of the dual closedloop four-link knee ***,an exoskeleton dual closed-loop controller composed of a position inner loop and a force outer loop is *** inner loop of the controller adopts the PID control algorithm,and the outer loop adopts the adaptive admittance control algorithm based on human-robot interaction force(HRI).The controller can adaptively adjust the admittance parameters according to the HRI to respond to dynamic changes in the mechanical and physical parameters of the human-robot system,thereby improving control compliance and the wearing comfort of the exoskeleton ***,we built a joint simulation experiment platform based on SolidWorks/Simulink to conduct virtual prototype simulation experiments and recruited volunteers to wear rehabilitation exoskeletons to conduct related control *** results show that the designed physiologically functional bionic exoskeleton and adaptive admittance controller can significantly improve the accuracy of human-robotic joint motion tracking,effectively reducing human-machine interaction forces and improving the comfort and safety of the *** paper proposes a dual-closed loop four-link knee joint exoskeleton and a variable admittance control method based on HRI,which provides a new method for the design and control of exoskeletons with hi

关键词： Limb exoskeleton Strongly coupled system Human-robot interaction Admittance control

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Modeling and assessment of the techno-economic analysis of biogas and its potential for the generation of electricity from water hyacinth biomass

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Journal of engineering and Applied science 2024年第1期71卷 98页

作者： Asante, Enoch Asiedu, Nana Yaw Sarpong, Samuel Agyemang, Emmanuel Okoh Ajani, Ibrahim Ntiamoah, Augustine Adjaottor, Albert Amatey Addo, Ahmad Renewable Energy Systems Engineering Department Koforidua Technical University Eastern Region Koforidua Ghana Chemical Engineering Department Faculty of Mechanical and Chemical Engineering College of Engineering Kwame Nkrumah University of Science and Technology Kumasi Ghana Mechanical Engineering Department Faculty of Engineering Koforidua Technical University Eastern Region Koforidua Ghana Materials Engineering Department Faculty of Mechanical and Chemical Engineering College of Engineering Kwame Nkrumah University of Science and Technology Kumasi Ghana Department of Agricultural and Biosystems Engineering Faculty of Mechanical and Chemical Engineering College of Engineering Kwame Nkrumah University of Science and Technology Kumasi Ghana

The study presents the economic feasibility assessment of converting the produced biogas from water hyacinth biomass into electricity. Approximately, 0.3793 m3CH4/kgVS was generated from the water hyacinth biomass. The research indicated that the available water hyacinth population on the Lower Volta River in the year 2020 could potentially generate a methane yield of 53.676 × 106m3. The volume of methane gas generated had the potential to produce an annual electricity output of 110.792 × 106 kWh, which could be integrated into the national grid. The economic analysis indicated positive results with an initial total investment cost of $67,273,700. The project showed a positive net present value (NPV) of $8,923,769 and a levelized cost of 0.172 $/kWh. The simple payback and equity payback periods were determined to be 5.5 and 11.3 years, respectively. Furthermore, a sensitivity analysis conducted showed that the project’s NPV remained positive when variations in input parameters such as initial cost, operations, and maintenance cost were less than 15% sensitive range. However, a 30% reduction in the feed-in tariff cost resulted in a negative NPV. In conclusion, biogas production from water hyacinth biomass in Ghana can make a significant contribution to the country’s energy mix and help alleviate the energy shortfall in rural areas. © The Author(s) 2024.

关键词： Sensitivity analysis

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Multi-objective design optimization of polymer spur gears using a hybrid approach

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Journal of engineering and Applied science 2024年第1期71卷 105页

作者： Elsiedy, Marah A. Hegazi, Hesham A. El-Kassas, Ahmed M. Zayed, Abdelhameed A. Department of Production Engineering and Mechanical Design Faculty of Engineering Tanta University Tanta Egypt Mechanical Design and Production Engineering Department Faculty of Engineering Cairo University Giza12613 Egypt Design and Production Engineering Department Faculty of Engineering and Materials Science German University in Cairo Cairo11835 Egypt

Polymer gears are used in applications requiring small to moderate loads to effectively transmit power and use the limited place available as possible. Various commercial standards have been provided designers with the rating criteria and acquaintance of different polymer material properties for the process of design. However, the result was unsatisfactory in terms of economy, time, and the optimality of the product. Thus, classic and stochastic algorithms have been embraced to reach the best design of polymer gears. Taking advantage of the former and latter algorithm’ methods, optimal design of gears could be attained with an increased gear life span and decreased failure modes. In this study, polyoxymethylene (POM) spur gear set has been optimized combining the mathematical model from plastic standards and hybrid optimization approach of multi-objective genetic algorithm (MOGA) and sequential quadratic programming (SQP). Weight and power loss were the objective functions. Five design variables were optimized with the satisfaction of bending and contact stresses, temperature, wear, and deformation as constraints. Solutions of the problem were formulated as Pareto optimal set. The results of multi-objective were compared with previously published single-objective optimization. The results favored multi-objective optimization (82.67%, 31.39% reduction in weight and power loss respectively) as it gave the best applicable solution fitting in real life situations. The results also went hand in hand with literature confirming the efficiency of the proposed algorithm. With the variation of operating parameters, various optimal designs could be obtained where the designers can choose the design that is suitable for a particular application. © The Author(s) 2024.

关键词： Quadratic programming

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An efficient parameterized neural network enhanced multiscale finite element modeling for triply periodic minimal surface meta-structures and its applications for femur

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Journal of materials Research and Technology 2024年 30卷 6176-6194页

作者： Chen, Yan-Zhen Wang, Chu-Hao Hsieh, Tsung-Yeh Tung, Cheng-Che Chen, Po-Yu Huang, Tsung-Hui Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan Department of Power Mechanical Engineering National Tsing Hua University Hsinchu Taiwan

Triply periodic minimal surface (TPMS) multiscale structures are meta-structures known for their low-weight-high-strength property. Because of their delicate geometry and sheet-networks feature, a fine mesh is required for finite element analysis, which is computationally expensive for conventional direct numerical simulation. To resolve this issue, this study develops a neural network enhanced finite element method (NN-FEM) for parameterized TPMS multiscale meta-structures. The multiscale homogenization approach replaces the complicated representative volume elements (RVEs) with a surrogate homogenized material model. The surrogate process is accomplished by deep learning of artificial neural networks (NN) with an effective boundary displacement gradient and the Helmholtz free energy of RVEs. The NN-trained surrogate material model is deployed on the macroscale Galerkin finite element model for various field tests. The parameterized structural information of TPMS can also be embedded into the NN model to resolve the hidden constitutive relation of RVEs with unique geometries. Numerical examples are provided to benchmark the efficacy and efficiency of NN-FEM on the parameterized TPMS structure. The proposed model can be applied to femurs for rapid stress analysis and osteoporosis detection. © 2024 The Authors

关键词： Finite element method

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Enhanced helium ion irradiation tolerance in a Fe-Co-Ni-Cr-Al-Ti high-entropy alloy with L12 nanoparticles

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Journal of materials science & Technology 2023年第12期143卷 169-177页

作者： Y.L.Zhao F.L.Meng T.Yang J.H.Luan S.F.Liu G.M.Yeli W.T.Lin W.H.Liu X.J.Liu C.T.Liu J.J.Kai School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China School of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Materials Science and Engineering Mechanical Behavior Division of Shenyang National Laboratory for Materials ScienceCity University of Hong KongHong KongChina Department of Mechanical Engineering City University of Hong KongHong KongChina Institute of Nuclear&New Energy Technology Tsinghua UniversityBeijing 100084China

L12-strengthened high entropy alloys(HEAs)with excellent room and high-temperature mechanical prop-erties have been proposed as promising candidates as structural materials for advanced nuclear ***,knowledge about their radiation response is fairly *** the present work,a novel HEA with a high density of L12 nanoparticles was irradiated with He ion at 500°*** electron microscope(TEM)and atom probe tomography(APT)were employed to study the evolution of mi-crostructural stability and radiation-induced *** to the single-phase FeCoNiCr HEA,the main microstructural features were numerous large faulted dislocation loops and helium *** the irradiation resistance of the present L12-strengthened HEA is much improved in terms of reduced bubble size,which could be attributed to the considerable He trapping efficiency of the coherent pre-cipitate/matrix interface and the enhanced capability of the interface for damage elimination when the matrix channel width is *** analysis revealed that an inverse-Kirkendall-mechanism-dominated radiation-induced segregation(RIS)occurs around bubbles,where a significant Co enrichment and Ni de-pletion can be clearly *** addition,the competing dynamics of ballistic mixing and elemental clustering that raised from the irradiation-enhanced diffusion in a highly supersaturated matrix,along with the low precipitation nucleation barrier due to the small lattice misfit,lead to a dynamical pre-cipitation dissolution and re-precipitation appears under *** a promising phenomenon is expected to promote a potential self-healing effect and could in turn provide a sustainable irradiation tolerance over the operational lifetime of a reactor.

关键词： L12 nanoparticles High-entropy alloy Helium bubble Phase stability Radiation-induced segregation

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