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SSRN 2025年

作者： Zhong, Boan Ni, Jiamiao Zhang, Qi Huang, Haoyu Liu, Yufei Song, Jian Liu, Yue Fan, Tongxiang State Key Lab of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Department of Mechanical & Materials Engineering University of Nebraska-Lincoln LincolnNE68588 United States National Engineering Research Center of Light Alloy Net Forming China

Enhancing interfacial binding and vibrational matching has been demonstrated to improve the thermal boundary conductance (TBC) of metal/non-metal interfaces. However, these two factors are not independent but are directly intercorrelated, which poses challenges in further improving the TBC. In this study, we focused on discerning this crucial correlation at classical immiscible carbon/copper (Cu) interfaces, with consideration of both interstitial doping (hydrogenated graphene) and substitutional doping (graphene-like boron nitride, BN). By employing density functional theory simulations, we observed a 32% decrease vibrational matching at H-Gr/Cu interface and a 73% increase at BN/Cu interface. Time-domain thermoreflectance measurements confirmed the changes in vibrational matching degree are congruent with the variations of TBC, while the binding energy exhibited an inverse trend. Further ph-DOS analysis revealed that the decrease in vibrational matching at H-Gr/Cu interface can be attributed to the suppression of out-of-plane vibrations that caused by the formation of strong bonds. This finding is further verified by non-equilibrium molecular dynamics simulations. The present study highlighted that the detrimental effect of binding strength on low-frequency vibrations, thereby facilitate a more profound understanding of the phonon state and heat transfer at such interfaces. © 2025, The Authors. All rights reserved.

关键词： Boron nitride

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Graphene-Diamond Heterostructures: Toward All-Carbon Devices with Enhanced Electrical Properties

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ACS Applied Electronic materials 2025年第11期7卷 5316-5321页

作者： Xiaolu Yuan Zichen Zhao Jinlong Liu Junjun Wei Liangxian Chen Chengming Li Wenrui Wang School of Mechanical Engineering University of Science and Technology Beijing No. 30 Xueyuan Road Haidian District Beijing 100083 China；Institute for Advanced Materials and Technology University of Science and Technology Beijing No. 30 Xueyuan Road Haidian District Beijing 100083 China Institute for Advanced Materials and Technology University of Science and Technology Beijing No. 30 Xueyuan Road Haidian District Beijing 100083 China School of Mechanical Engineering University of Science and Technology Beijing No. 30 Xueyuan Road Haidian District Beijing 100083 China

A variety of field effect transistors (FETs) with two types of graphene-diamond (G-D) heterostructures have been fabricated. The results indicate that the transferred G-D FETs exhibit bipolar output characteristics, characterized by a transfer curve resembling a classic V-shape. In contrast, the in situ catalyzed G-D FETs demonstrate a more complex output behavior. Notably, linear ohmic contact characteristics are established between Pd/Ti/Au contacts and the in situ G-D heterostructure without requiring additional postannealing treatment. An unprecedentedly low specific contact resistivity of 1.4 × 10–7Ω cm2has been achieved. For the in situ catalyzed G-D FETs, top-gated FETs display unipolar output characteristics with an impressive current density reaching 106A cm–2. Conversely, ring-gated FETs exhibit bipolar output characteristics, featuring a Dirac point at a voltage of 3 V. For certain FETs lacking gate modulation, approximately 18 nm-thick graphene layers situated beneath the gate oxide as the channel. This study paves new pathways for advancements in graphene-based devices or all-carbon electronics.

关键词： graphene-diamond heterostructures FETs ohmiccontact output characteristics all-carbon

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Synergistic effect of rhamnolipid and Bacillus mucilaginosus on detoxification and activation of municipal solid waste incineration fly ash

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Chemosphere 2024年 366卷 143461页

作者： Liu, Bin Sun, Shaoming Zhang, Xinyue Zhang, Shiquan Kong, Lijuan School of Materials Science and Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

In recent years, the substantial increase in municipal solid waste incineration fly ash (MSWIFA) production has made its treatment a critical issue. However, the high toxicity of MSWIFA makes its utilization still in the exploratory stage. In this study, the heavy metal leaching rate, particle size distribution and activity index of MSWIFA were tested to investigate the detoxification and activation effects of Bacillus mucilaginosus on MSWIFA by introducing rhamnolipid. The results show that the microbial treatment can greatly increase the leaching rate of heavy metals in MSWIFA and its 28-day and 90-day activity indexes, especially by the synergistic treatment. For the Bacillus mucilaginosus and rhamnolipid treated MSWIFA (BR-MSWIFA), the maximum leaching rates follow the order from high to low of 85.57% Cr, 78% Cu, 76.38% Zn, 62.78% Pb and 37.65% Mn, while having a low mass loss of less than 5%, which is important for its reuse. Moreover, compared with the untreated MSWIFA (U-MSWIFA), the average particle sizes of Bacillus mucilaginosus treated MSWIFA (B-MSWIFA) and BR-MSWIFA decrease from 8.39 μm to 7.80 μm and 4.31 μm, and the 28-day activity indexes increase from 80.19% to 101.59% and 110.61%. The effect mechanism is that rhamnolipid not only can promote the growth, reproduction, and metabolic acid production of Bacillus mucilaginosus, but also disperse the extracellular polymeric substance (EPS) and MSWIFA particles, thus increase their contact area and the bioleaching. This study provided a theoretical foundation for the harmless treatment and resource utilization of solid wastes containing heavy metals. © 2024 Elsevier Ltd

关键词： Fly ash

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Enhanced wear resistance of LDED 316L stainless steel fabricated by in-situ ultrasonic rolling

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China Foundry 2025年第3期 301-310页

作者： Yi-gui Su Guan Liu Xu-yu Pi Dong-xu Wen De-fu Liu Yong-cheng Lin School of Mechanical and Electrical Engineering Central South University State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology

Stainless steel parts with complex shape can be fabricated using additive manufacturing, which do not rely on molds and dies. However, coarse dendrites induced by repeated heating of additive manufacturing result in weak properties, which limits its application. In this study, an in-situ ultrasonic rolling(UR) device was developed to assist the laser directed energy deposition(LDED) process. The microstructural characteristics, as well as the microhardness and wear behavior, were studied for the 316L stainless steel manufactured by in-situ ultrasonic rolling assisted LDED. It is found that austenite, ferrite, and small Si oxides are the main constituents of both the LDED and LDED-UR alloy samples. Under the severe plastic deformation of ultrasonic rolling, the long-branched ferrites by LDED are transformed into the rod-like phases by LDED-UR. Meanwhile, the ferrite is more uniformly distributed in the LDED-UR alloy sample compared with that in LDED alloy sample. Columnar grains with the size of 97.85 μm appear in the LDED alloy sample, which is larger than the fully equiaxed grains(22.35 μm)of the LDED-UR alloy. The hardness of the LDED-UR alloy sample is about 266.13±13.62 HV0.2, which is larger than that of the LDED alloy sample(212.93±12.85 HV0.2). Meanwhile, the wear resistance is also greatly enhanced by applying the assisted in-situ ultrasonic rolling. The achieved high wear resistance can be ascribed to the uniformly distributed hard matter(ferrites) and the impedance of dislocations by high fraction of grain boundaries. Abrasive wear and adhesive wear are identified as the primary wear mechanisms of the studied alloy. Gaining an in-depth understanding of the relationship between wear mechanisms and microstructures offers an effective approach in manufacturing high wear resistant alloys suitable for use in harsh working environments.

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Tunable magneto-optical properties in MoS2 via defect-induced exciton transitions

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Physical Review B 2022年第16期106卷 L161407-L161407页

作者： Tomer Amit Daniel Hernangómez-Pérez Galit Cohen Diana Y. Qiu Sivan Refaely-Abramson Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovot 7610001 Israel Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06511 USA

The presence of chalcogen vacancies in monolayer transition metal dichalcogenides (TMDs) leads to excitons with mixed localized-delocalized character and to reduced valley selectivity. Recent experimental advances in defect design in TMDs allow for a close examination of such mixed exciton states as a function of their degree of circular polarization under external magnetic fields, revealing strongly varying defect-induced magnetic properties. A theoretical understanding of these observations and their physical origins demands a predictive, structure-sensitive theory. In this work, we study the effect of chalcogen vacancies on the exciton magnetic properties in monolayer MoS2. Using many-body perturbation theory, we show how the complex excitonic picture associated with the presence of defects—with reduced valley and spin selectivity due to hybridized electron-hole transitions—leads to a structurally controllable exciton magnetic response. We find a variety of g-factors with changing magnitudes and sign depending on the exciton energy and character. Our findings suggest a pathway to tune the nature of the excitons—and by that their magneto-optical properties—through defect architecture.

关键词： Defects Excitons Magneto-optics Transition metal dichalcogenides Ab initio calculations Many-body techniques

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3D Finite Thermal Modelling of SrSnO3 Field Effect Transistors

3D Finite Thermal Modelling of SrSnO3 Field Effect Transisto...

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Device Research Conference

作者： Bivek Bista Jiaxuan Wen Prafful Golani Fengdeng Liu Tristan Truttmann Bharat Jalan Steven Koester Georges Pavlidis School of Mechanical Aerospace and Manufacturing Engineering University of Connecticut Storrs CT USA Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN USA Department of Chemical Engineering and Materials Science University of Minnesota Minneapolis MN USA

ISBN: (数字)9798350373738

ISBN: (纸本)9798350373745

SrSnO 3 (SSO) is an ultra-wide bandgap (≈ 4.1 eV) semiconductor that has potential applications in high power electronics and DUV optoelectronics [1] . However, the thermal properties of doped SSO thin films have not been extensively studied. Due to its high bandgap, self-heating can severely limit the device’s performance and reliability. This study reports the thermal transport characteristics of SSO based metal-semiconductor field-effect transistors (MESFETs) through 3D finite modelling and compares them with experimental data obtained via Transient Thermoreflectance Imaging (TTI). TTI can be used to obtain surface temperature maps with high spatial (≈ 410 nm) and temporal (≈ 50 ns) resolution [2] , [3] . Therefore, the TTI technique was used to extract the gate and drain metal surface temperature under pulsed biasing (300 μs pulse width with 10% duty cycle), whereas the steady state temperature rise was numerically evaluated using a 3D Finite Element (FE) model in ANSYS Workbench.

关键词： Solid modeling Three-dimensional displays Temperature Photonic band gap Thermoreflectance imaging Numerical models Finite element analysis

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Dramatic reduction in thermal conductivity by high-density dislocations in SrTiO3

arXiv

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arXiv 2025年

作者： Ding, Jinxue Zhang, Jiawen Dong, Jinfeng Higuchi, Kimitaka Nakamura, Atsutomo Lu, Wenjun Sun, Bo Fang, Xufei Institute for Applied Materials Karlsruhe Institute of Technology Karlsruhe76131 Germany Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Materials Science and Engineering Nanyang Technological University Singapore639798 Singapore Institute of Materials and Systems for Sustainability Nagoya University Aichi Nagoya464-8601 Japan Graduate School of Engineering Science Osaka University Toyonaka Osaka560−8531 Japan Tsinghua SIGS and Guangdong Provincial Key Laboratory of Thermal Management Engineering & Materials Tsinghua University Shenzhen518055 China

Decreasing thermal conductivity is important for designing efficient thermoelectric devices. Traditional engineering strategies have focused on point defects and interface design. Recently, dislocations as line defects have emerged as a new tool for regulating thermal conductivity. In ceramics-based thermoelectric materials, the key challenge lies in achieving sufficiently high-density dislocations to effectively scatter phonons, as the typical dislocation density in ceramics after bulk deformation is constrained to ~1012 m−2. In this work, we adopted the mechanical imprinting method and achieved a dislocation density of ~1015 m−2 in single-crystal SrTiO3, which is known for its room-temperature plasticity and acts as a promising material for thermoelectric applications. Using the time-domain thermoreflectance (TDTR) method, we measured a ~50% reduction in the thermal conductivity over a broad temperature range (80−400 K) with the engineered high-density dislocations. These results suggest that tuning dislocations could offer a new path to minimizing thermal conductivity for engineering thermoelectric materials. © 2025, CC BY.

关键词： Single crystals

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Path Signatures and Graph Neural Networks for Slow Earthquake Analysis: Better Together?

arXiv

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arXiv 2024年

作者： Riess, Hans Veveakis, Manolis Zavlanos, Michael M. Department of Electrical & Computer Engineering Duke University DurhamNC United States Department of Civil & Environmental Engineering Duke University DurhamNC United States Department of Mechanical Engineering & Materials Science DurhamNC United States

The path signature, having enjoyed recent success in the machine learning community, is a theoretically-driven method for engineering features from irregular paths. On the other hand, graph neural networks (GNN), neural architectures for processing data on graphs, excel on tasks with irregular domains, such as sensor networks. In this paper, we introduce a novel approach, Path Signature Graph Convolutional Neural Networks (PS-GCNN), integrating path signatures into graph convolutional neural networks (GCNN), and leveraging the strengths of both path signatures, for feature extraction, and GCNNs, for handling spatial interactions. We apply our method to analyze slow earthquake sequences, also called slow slip events (SSE), utilizing data from GPS timeseries, with a case study on a GPS sensor network on the east coast of New Zealand’s north island. We also establish benchmarks for our method on simulated stochastic differential equations, which model similar reaction-diffusion phenomenon. Our methodology shows promise for future advancement in earthquake prediction and sensor network analysis. Copyright © 2024, The Authors. All rights reserved.

关键词： Stochastic systems

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Health-conscious optimal control of Li-ion cell using simplified full homogenized macro-scale model

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Journal of Energy Storage 2024年 91卷

作者： Qadir, Salman Li, Guang School of Engineering and Materials Science Queen Mary University of London LondonE1 4NS United Kingdom National University of Sciences and Technology Islamabad Pakistan Faculty of Mechanical and Electrical Engineering Kunming University of Science and Technology Kunming 650500 China

This article presents the optimal charging of a Li-ion cell based on a simplified full homogenized macro-scale (FHM) model. A solid electrolyte interface (SEI) layer model is included in the simplified FHM model to quantify cell degradation. With these models, a multi-objective optimal control problem subject to constraints from safety concerns is formulated to achieve health-conscious optimal charging. This constrained optimal control problem is converted to a nonlinear programming problem (NLP). A nonlinear model predictive control (NMPC) strategy is adopted by solving the NLP at each sampling time using the pseudo-spectral optimization method. The effect of the input current upper bound on the cell film resistance Rfilm and state of health (SoH) reveals that Rfilm and SoH are more sensitive to input current upper bound at lower values of input current upper bound. Simulation results show that the simplified model and pseudo-spectral method are crucial for reducing the computational load of the model. The proposed algorithm is more efficient in reducing health degradation than the conventional constant current constant voltage (CCCV) charging algorithm since it can explicitly handle the film resistance and capacity as health parameters. Multiple cycle charging simulations revealed that the health-conscious algorithm decreases health degradation and increases battery life. © 2024 The Author(s)

关键词： Model predictive control

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A FRAMEWORK FOR INVESTIGATING EDUCATIONAL THEORIES IN engineering EDUCATION RESEARCH 51

A FRAMEWORK FOR INVESTIGATING EDUCATIONAL THEORIES IN ENGINE...

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51st Annual Conference of the European Society for engineering Education, SEFI 2023

作者： van der Werf, V. van Helden, G. Schleiss, J. Saunders-Smits, G.N. LDE Centre for Education and Learning Delft University of Technology Delft Netherlands Leiden Institute of Advanced Computer Science Leiden University Leiden Netherlands Faculty of Aerospace Engineering Delft University of Technology Delft Netherlands 4TU Centre for Engineering Education Delft University of Technology Delft Netherlands Faculty of Computer Science Otto von Guericke University Magdeburg Magdeburg Germany Faculty of Mechanical Maritime and Materials Engineering Delft University of Technology Delft Netherlands

ISBN: (纸本)9782873520267

Grounding the design of educational interventions and their analysis in theory allows us to understand and interpret results of interventions and advance educational theories. Moreover, building an understanding of which educational theories are used and how they are used can build a consensus among researchers and mature the research in a field. In this paper, we investigate the extent to which educational theories are used to ground the design, analysis, and evaluation of learning activities in engineering education. For this purpose, we developed a coding instrument to determine: (1) which educational theories are expressed in studies investigating learning activities and interventions, and (2) the extent to which these theories inform (a) the design of an intervention and (b) the analysis of that intervention. The instrument was applied to a sample of 12 studies from an existing literature review on collaborative engineering design activities to demonstrate the relevance of the developed framework. Results reveal that most studies refer to educational theory, primarily pedagogical approaches such as project-based learning. Furthermore, half of the time, the design of learning interventions is grounded in theory, however, the evaluation of those interventions is often not connected to educational theories. © 2023 SEFI 2023 - 51st Annual Conference of the European Society for engineering Education: engineering Education for Sustainability, Proceedings. All Rights Reserved.

关键词： engineering education

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