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SSRN 2024年

作者： Jo, Seohyeon Raj, Rishi Materials Science Engineering Program Department of Mechanical Engineering University of Colorado Boulder BoulderCO80309 United States

We report memristor behavior in bar shaped single crystals of titania that have been "formed" into electronic conductors. The cycling experiments are carried out with forward and reverse current, rather than voltage;the current experiments are more reproducible. The single crystals permit in-situ measurements of interface as well as the end-to-end resistivities by the four-point method. The total specimen resistance is shown to be nearly equal to the sum of the interface resistances at the positive and negative electrodes referenced at the forming step. The memristor effect arises predominantly from the change in the interfacial resistance at the positive electrode which shows local ratio of high/low resistance of x103. The resistance at the opposite interface remains unchanged. The effect at the positive electrode is attributed to a change in the state of exciton-like electron-hole configurations under the local field induced by the current. The memristor effect is sensitive to crystal-orientation. © 2024, The Authors. All rights reserved.

关键词： Memristors

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Towards Scalable Automated Grading: Leveraging Large Language Models for Conceptual Question Evaluation in engineering 1

Towards Scalable Automated Grading: Leveraging Large Languag...

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1st Workshop on Large Foundation Models for Educational Assessment

作者： Gao, Rujun Guo, Xiaosu Li, Xiaodi Narayanan, Arun Balajiee Lekshmi Thomas, Naveen Srinivasa, Arun R. J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University United States Computer Science Department University of Texas Dallas United States Intelligent Systems Program University of Pittsburgh United States Department of Artificial Intelligence and Informatics Mayo Clinic United States

This study explores the feasibility of using large language models (LLMs), specifically GPT-4o (ChatGPT), for automated grading of conceptual questions in an undergraduate mechanical engineering course. We compared the grading performance of GPT-4o with that of human teaching assistants (TAs) on ten quiz problems from the MEEN 361 course at Texas A&M University, each answered by approximately 225 students. Both the LLM and TAs followed the same instructor-provided rubric to ensure grading consistency. We evaluated performance using Spearman’s rank correlation coefficient and Root Mean Square Error (RMSE) to assess the alignment between rankings and the accuracy of scores assigned by GPT-4o and TAs under zero- and few-shot grading settings. In the zero-shot setting, GPT-4o demonstrated a strong correlation with TA grading, with Spearman’s rank correlation coefficient exceeding 0.6 in seven out of ten datasets and reaching a high of 0.9387. Our analysis reveals that GPT-4o performs well when grading criteria are straightforward but struggles with nuanced answers, particularly those involving synonyms not present in the rubric. The model also tends to grade more stringently in ambiguous cases compared to human TAs. Overall, ChatGPT shows promise as a tool for grading conceptual questions, offering scalability and consistency. © 2024 R. Gao1, X. Guo2, X. Li4, A.B.L. Narayanan3, N. Thomas1 & A.R. Srinivasa1.

关键词： Mean square error

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Optothermal Manipulation at Fluid Interfaces

Optothermal Manipulation at Fluid Interfaces

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Conference on Lasers and Electro-Optics (CLEO)

作者： Youngsun Kim Carolina Ponce Zhihan Chen Yuebing Zheng Materials Science & Engineering Program Texas Materials Institute The University of Texas at Austin Austin TX USA Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA

Optothermal manipulation of particles at fluid interfaces was studied with a film of gold nanoparticles assembled at aqueous/oil interfaces. The unique optothermal behaviors of particles and fluid interfaces under opt... 详细信息

ISBN: (纸本)9781957171258

关键词： Gold Laser beams Laser irradiation Light scattering Optical force Optical tweezers

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Moderate-Refractive-Index Mie Resonators for Versatile Modulation of Two-Dimensional Excitons

Moderate-Refractive-Index Mie Resonators for Versatile Modul...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Jie Fang Yuebing Zheng Materials Science & Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX USA Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA

By coupling well-designed moderate-refractive-index Mie resonators to monolayer semiconductors, we have demonstrated efficient modulation of two-dimensional excitons in multiple dimensions: far-field excitonic radiati... 详细信息

ISBN: (纸本)9781957171258

关键词： Excitons Mie resonances Mie theory Optical resonators Refractive index Semiconductors

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Optothermal multimodal manipulation of micro/nanoparticles

Optothermal multimodal manipulation of micro/nanoparticles

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Conference on Lasers and Electro-Optics (CLEO)

作者： Hongru Ding Pavana Siddhartha Kollipara Kan Yao Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA Materials Science & Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX USA

We report a new optical platform to achieve on-demand multimodal manipulation of micro/nanoparticles by a synergy of optical and thermal forces.

ISBN: (纸本)9781957171258

We report a new optical platform to achieve on-demand multimodal manipulation of micro/nanoparticles by a synergy of optical and thermal forces.

关键词： Laser beams Nanoparticles Optical force Optical manipulation Optical tweezers Spatial resolution

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Processing-dependent stabilization of a dissimilar rare-earth boride in high-entropy (Ti0.2Zr0.2Hf0.2Ta0.2Er0.2)B2 with enhanced hardness and grain boundary segregation

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Journal of the European Ceramic Society 2022年第12期42卷 5164-5171页

作者： Qin, Mingde Shivakumar, Sashank Lei, Tianjiao Gild, Joshua Hessong, Esther C. Wang, Haoren Vecchio, Kenneth S. Rupert, Timothy J. Luo, Jian Program of Materials Science and Engineering University of California San Diego La JollaCA92093 United States Department of NanoEngineering University of California San Diego La JollaCA92093 United States Department of Mechanical and Aerospace Engineering University of California Irvine IrvineCA92697 United States Department of Materials Science and Engineering University of California Irvine IrvineCA92697 United States

This study demonstrates that 20% of a rare-earth (RE) diboride (ErB2) can be stabilized in a high-entropy transition metal (TM) diboride, despite the dissimilar chemical properties of RE and TM elements and large differences in lattice parameters of ErB2 and typical TMB2. However, the phase formation depends on the fabrication route, which is a noteworthy observation. Specifically, single-phase (Ti0.2Zr0.2Hf0.2Ta0.2Er0.2)B2 is synthesized via reactive spark plasma sintering (SPS) using elemental boron and metal elements. In contract, a specimen made by borocarbothermal reduction of binary oxides and SPS possess significant amounts of two Er-rich secondary phases. Notably, the RE addition in high-entropy TM diboride leads to improved hardness. Aberration-corrected scanning transmission electron microscopy (AC STEM) and energy-dispersive X-ray spectroscopy (EDS) elemental analyses further reveal significant Er segregation at grain boundaries. This work suggests that high-entropy ceramics can have significant solubilities of dissimilar components that may enable new, tunable, and improved properties. © 2022 The Authors

关键词： Rare earths

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Erosion-corrosion resistance of Mo-Ti- and Ni-Cr-Mo-alloyed medium-carbon martensitic steels: a critical analysis of synergistic effect of erosion and corrosion

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Journal of Iron and Steel Research International 2022年第8期29卷 1299-1311页

作者： De-fa Li Hang-yu Dong Cheng-yang Hu Kai-ming Wu Serhii Yershov Oleg Isayev School of Mechanical and Vehicle Engineering West Anhui UniversityLuan 237012AnhuiChina The State Key Laboratory of Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science on Metallurgical ProcessingInternational Research Institute for Steel TechnologyWuhan University of Science and TechnologyWuhan 430081HubeiChina Laboratory for Excellence in Advanced Steel Research Materials Science and Engineering ProgramDepartment of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79968USA

Grain refinement renders Mo-Ti-alloyed medium-carbon martensitic steel to exhibit high hardness,high strength,and good toughness,but the erosion-corrosion resistance of steel in a corrosive slurry environment is not ***-Ti-alloyed medium-carbon martensitic steel is compared with Ni-Cr-Mo-alloyed medium-carbon martensitic steel,and the erosion-corrosion resistance of those two steels under impingement by NaCl solution with gravels has been *** components,pure-corrosion rate,pure-erosion rate,and synergistic effect of erosion and corrosion(SEEC)of erosion-corrosion rate,were *** pure-corrosion and pure-erosion rates of Mo-Ti-alloyed steel were higher than those of Ni-Cr-Mo-alloyed one;however,its erosion-corrosion rate was relatively lower because of a weak *** plastic deformation and work hardening due to gravel impingement were the essential reason for SEEC,which could be reduced by grain refinement,and consequently,Mo-Ti-alloyed steel with finer grains had better erosion-corrosion *** refinement could be an effective way to improve the erosion-corrosion resistance of martensitic steels.

关键词： Grain refinement Mo-Ti alloying Ni-Cr-Mo alloying Martensite Erosion-corrosion

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Vortex Formation of Active Particles within a Confined Geometry by Velocity Alignment

Vortex Formation of Active Particles within a Confined Geome...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Zhihan Chen Hongru Ding Yuebing Zheng Materials Science & Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX USA Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA

we have developed an optical feedback control system with synchronous control of active particles to study collective motion in nature. Fish-like vortex is observed within a circular confined geometry based on the par... 详细信息

ISBN: (纸本)9781957171258

关键词： Coherence Light fields Optical feedback Polarization Rubidium Spatial light modulators

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Molecular simulation-guided and physics-informed mechanistic modeling of multifunctional polymers

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Acta Mechanica Sinica 2021年第5期37卷 725-745,I0002页

作者： Guang Chen Weikang Xian Qiming Wang Ying Li Department of Mechanical Engineering University of ConnecticutStorrsCT 06269USA Sonny Astani Department of Civil and Environmental Engineering University of Southern CaliforniaLos AngelesCA 90089USA Department of Mechanical Engineering and Polymer Program Institute of Materials ScienceUniversity of ConnecticutStorrsCT 06269USA

Polymeric materials have a broad range of mechanical and physical *** have been widely used in material science,biomedical engineering,chemical engineering,and mechanical *** introduction of active elements into the soft matrix of polymers has enabled much more diversified functionalities of polymeric materials,such as self-healing,electroactive,magnetosensitive,pH-responsive,and many *** further enable applications of these multifunctional polymers,a mechanistic modeling method is required and of great significance,as it can provide links between materials’micro/nano-structures and their macroscopic mechanical *** this goal,molecular simulation plays an important role in understanding the deformation and evolution of polymer networks under external loads and *** molecular insights provide physical guidance in the formulation of mechanistic-based continuum models for multifunctional *** this perspective,we present a molecular simulation-guided and physics-informed modeling framework for polymeric ***,the physical theory for polymer chains and their networks is briefly *** serves as the foundation for mechanistic-models of polymers,linking their chemistry,physics,and mechanics ***,the deformation of the polymer network is used to derive the strain energy density ***,the corresponding continuum models can capture the intrinsic deformation mechanisms of polymer *** then highlight several representative examples across multiphysics coupling problems to describe in detail for this proposed *** but not least,we discuss potential challenges and opportunities in the modeling of multifunctional polymers for future research directions.

关键词： Molecular simulation Multiphysics modeling Multiscale modeling Multifunctional polymers Soft Matter

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Optically-generated focused ultrasound for noninvasive brain stimulation with ultrahigh precision

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Light(science & Applications) 2022年第11期11卷 2817-2831页

作者： Yueming Li Ying Jiang Lu Lan Xiaowei Ge Ran Cheng Yuewei Zhan Guo Chen Linli Shi Runyu Wang Nan Zheng Chen Yang Ji-Xin Cheng Department of Mechanical Engineering Boston UniversityBostonMA 02215USA Graduate Program for Neuroscience Boston UniversityBostonMA 02215USA Department of Electrical and Computer Engineering Boston UniversityBostonMA 02215USA Department of Chemistry Boston UniversitBostonMA 02215USA Department of Biomedical Engineering Boston UniversityBostonMA 02215USA Division of Materials Science and Engineering Boston UniversityBostonMA 02215USA Department of Biological Engineering Massachusetts Institute of TechnologyCambridgeMA 02142USA

High precision neuromodulation is a powerful tool to decipher neurocircuits and treat neurological *** non-invasive neuromodulation methods offer limited precision at the milimeter ***,we report opticallygenerated focused ultrasound(OFUS)for non-invasive brain stimulation with ultrahigh *** is generated by a soft optoacoustic pad(SOAP)fabricated through embedding candle soot nanoparticles in a curved polydimethylsiloxane *** generates a transcranial ultrasound focus at 15 MHz with an ultrahigh lateral resolution of 83μm,which is two orders of magnitude smaller than that of conventional transcranial-focused ultrasound(tFUS).Here,we show effective OFUS neurostimulation in vitro with a single ultrasound *** demonstrate submillimeter transcranial stimulation of the mouse motor cortex in *** acoustic energy of 0.6 mJ/cm?,four orders of magnitude less than that of tFUS,is suffcient for successful OFUS *** offers new capabilities for neuroscience studies and disease treatments by delivering a focus with ultrahigh precision noninvasively.

关键词： SOAP stimulation precision

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