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In Situ Atomic-Scale Visualization of Oxygen Vacancy Assisted Reaction Dynamics on TiO2Surfaces

Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Chen, Xiaobo Li, Meng Hwang, Sooyeon Zakharov, Dmitri N Yang, Judith Zhou, Guangwen Materials Science and Engineering Program & Department of Mechanical Engineering State University of New York at Binghamton Binghamton New York United States Center for Functional Nanomaterials Brookhaven National Laboratory Upton New York United States

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Numerical and experimental investigation of laser-assisted fused filament fabrication of carbon fibre reinforced polyether-ether-ketone composites: Temperature field evolution and crystallisation behaviours

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Additive Manufacturing 2025年 109卷

作者： Wenhan Qiu Yingdan Zhu Pengcheng Shi Xiaocheng Yu Kok hoong Wong Dongxi Lv Gang Chen Jian Yang Zhejiang Key Laboratory of Precision Actuation and Intelligent Robotics Ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Ningbo China Ningbo 315100 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China

This study presents a parameterised finite element modelling approach to predict the temperature field evolution and crystallisation behaviour of short carbon fibre reinforced polyether-ether-ketone (SCF/PEEK) during laser-assisted fused filament fabrication (LAFFF). The model innovatively integrates dynamic laser-nozzle heat sources with the melting-crystallisation kinetics of materials, which effectively addresses the longstanding issues of thermal imbalance and non-uniform crystal distribution in composites additive manufacturing. Validated through thermocouple measurements, infrared monitoring, and differential scanning calorimetry, the framework achieves predictive accuracy within ± 5 % for average relative crystallinity and ± 20 % for crystal variance. This research uncovers the crucial role of laser induced through-thickness heat transfer, a characteristic that has not been previously evident in conventional FFF. The results show that optimised auxiliary heating parameters, with ambient temperatures ranging from 75–110 °C and laser power between 2–3 W, create a process window that balances crystallinity enhancement with defect mitigation. Laser preheating generates transient temperature cycles, prolonging the exposure of the material near the crystallisation peak temperature of 235 °C. Meanwhile, elevated ambient temperatures decrease thermal gradients, together expanding the crystallisation window. This synergistic effect boosts the average relative crystallinity by 60 %–82 % compared to conventional rapid - cooling FFF, reaching values similar to those of industrial - grade 3D printing systems. These insights pave the way for the optimisation of thermal conditions in LAFFF, reducing dependence on high-temperature equipment and expanding the applicability of SCF/PEEK 3D printing technology.

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Single-Level Differentiable Contact Simulation

arXiv

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arXiv 2022年

作者： Le Cleac’h, Simon Schwager, Mac Manchester, Zachary Sindhwani, Vikas Florence, Pete Singh, Sumeet The Department of Mechanical Engineering Stanford University StanfordCA94305 United States The Aeronautics and Astronautics Department Stanford University StanfordCA94305 United States The Robotics Institute Carnegie Mellon University PittsburghPA15213 United States Google New York CityNY10011 United States Google Mountain ViewCA94043 United States

We present a differentiable formulation of rigid-body contact dynamics for objects and robots represented as compositions of convex primitives. Existing optimization-based approaches simulating contact between convex primitives rely on a bilevel formulation that separates collision detection and contact simulation. These approaches are unreliable in realistic contact simulation scenarios because isolating the collision detection problem introduces contact location non-uniqueness. Our approach combines contact simulation and collision detection into a unified single-level optimization problem. This disambiguates the collision detection problem in a physics-informed manner. Compared to previous differentiable simulation approaches, our formulation features improved simulation robustness and a reduction in computational complexity by more than an order of magnitude. We illustrate the contact and collision differentiability on a robotic manipulation task requiring optimization-through-contact. We provide a numerically efficient implementation of our formulation in the Julia language called ***. Copyright © 2022, The Authors. All rights reserved.

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Beyond Constant Curvature: A New Mechanics Model for Unidirectional Notched-Tube Continuum Wrists

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Journal of Medical robotics Research 2021年第1-2期6卷 2140004页

作者： Pacheco, Nicholas E. Gafford, Joshua B. Atalla, Mostafa A. Webster, Robert J. Fichera, Loris Department of Robotics Engineering Worcester Polytechnic Institute Worcester 01609 MA United States EndoTheia Inc. Nashville 37203 TN United States Department of BioMechanical Engineering Delft University of Technology CD Delft 2628 Netherlands Department of Mechanical Engineering Vanderbilt University Nashville 37212 TN United States

This paper presents a new mechanics model for unidirectional notched-tube continuum wrists, a class of mechanisms frequently used to implement distal steering in needle-sized surgical robotic instruments. Existing kinematic models available for these devices are based on the simplifying assumption that, during actuation, all the notches undergo the same amount of deflection, so that the shape of a wrist can be approximated by an arc of constant curvature. This approach is analytically attractive, but, as we show in this paper, it can sometimes fail to provide good tracking accuracy. In this paper, we provide a new model that relaxes the assumption above, and we report experimental evidence showing its superior accuracy. We model wrist deflection using Castigliano's Second Theorem, with the addition of a capstan friction term that accounts for frictional losses on the actuation tendon. Because notched-tube wrists are typically made of Nickel-Titanium (Nitinol), which has nonlinear stress-strain characteristics, we use a technique to obtain a local linearized approximation of the material modulus, suitable for use in the deflection model. The result of our modeling is a system of nonlinear equations that can be solved numerically to predict the wrist configuration based on the applied actuation force. Experimental results on physical specimens show that this improved model provides a more accurate estimate of wrist kinematics than prior models assuming constant curvature bending. © 2021 World Scientific Publishing Company.

关键词： notched-tube joints steerable needles Surgical robotics

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SegKAN: High-Resolution Medical Image Segmentation with Long-Distance Dependencies

arXiv

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arXiv 2024年

作者： Tan, Shengbo Xue, Rundong Luo, Shipeng Zhang, Zeyu Wang, Xinran Zhang, Lei Ergu, Daji Yi, Zhang Zhao, Yang Cai, Ying College of Computer Science and Artificial Intelligence Southwest Minzu University Chengdu610225 China Institute of Artificial Intelligence and Robotics Xi’an Jiaotong University Xi’an710049 China College of Mechanical and Electrical Engineering Northeast Forestry University Harbin150040 China The Australian National University CanberraACT2601 Australia University of Chinese Academy of Sciences Beijing101408 China Sichuan University Chengdu610225 China Department of Computer Science and Information Technology La Trobe University BundooraVIC3086 Australia

Hepatic vessels in computed tomography scans often suffer from image fragmentation and noise interference, making it difficult to maintain vessel integrity and posing significant challenges for vessel segmentation. To address this issue, we propose an innovative model: SegKAN. First, we improve the conventional embedding module by adopting a novel convolutional network structure for image embedding, which smooths out image noise and prevents issues such as gradient explosion in subsequent stages. Next, we transform the spatial relationships between Patch blocks into temporal relationships to solve the problem of capturing positional relationships between Patch blocks in traditional Vision Transformer models. We conducted experiments on a Hepatic vessel dataset, and compared to the existing state-of-the-art model, the Dice score improved by 1.78%. These results demonstrate that the proposed new structure effectively enhances the segmentation performance of high-resolution extended objects. Code will be available at https://***/goblin327/SegKAN. © 2024, CC BY-NC-SA.

关键词： Image segmentation

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Insights into Oxide Growth: In Situ Atomic-Scale Visualization of Mass Transport during Copper Oxidation

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Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Qiao, Linna Wang, Jianyu Ye, Shuonan Chen, Xiaobo Li, Meng Zakharov, Dmitri N Kisslinger, Kim Yang, Judith C Zhou, Guangwen Materials Science and Engineering Program & Department of Mechanical Engineering State University of New York at Binghamton Binghamton New York United States Center for Functional Nanomaterials Brookhaven National Laboratory Upton New York United States

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Toward magneto-electroactive endoluminal soft (MEESo) robots

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ASME 2019 Dynamic Systems and Control Conference, DSCC 2019

作者： Steiner, Jake A. Hussain, Omar A. Pham, Lan N. Abbott, Jake J. Leang, Kam K. Lab Department of Mechanical Engineering Robotics Center University of Utah Salt Lake CityUT84112 United States Telerobotics Lab Department of Mechanical Engineering Robotics Center University of Utah Salt Lake CityUT84112 United States

ISBN: (纸本)9780791859162

This paper introduces a magneto-electroactive endoluminal soft (MEESo) robot concept, which could enable new classes of catheters, tethered capsule endoscopes, and other mesoscale soft robots designed to navigate the natural lumens of the human body for a variety of medical applications. The MEESo locomotion mechanism combines magnetic propulsion with body deformation created by an ionic polymer-metal composite (IPMC) electroactive polymer. A detailed explanation of the MEESo concept is provided, including experimentally validated models and simulated magneto-electroactive actuation results demonstrating the locomotive benefits of incorporating an IPMC compared to magnetic actuation alone. © 2019 ASME.

关键词： Magnetos

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Corrigendum to “A critical review on mechanical micro-drilling of glass and carbon fibre reinforced polymer (GFRP and CFRP) composites” [Compos B: Eng 254 (2023) 110589]

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Composites Part B: engineering 2023年 262卷

作者： Norbert Geier Karali Patra Ravi Shankar Anand Sam Ashworth Barnabás Zoltán Balázs Tamás Lukács Gergely Magyar Péter Tamás-Bényei Jinyang Xu J Paulo Davim Budapest University of Technology and Economics Faculty of Mechanical Engineering Department of Manufacturing Science and Engineering Budapest 1111 Hungary Indian Institute of Technology Patna Department of Mechanical Engineering Patna 801103 India Birla Institute of Technology Department of Mechanical Engineering Patna Campus Patna 800014 India North of England Robotics Innovation Centre The University of Salford Salford Greater Manchester UK Budapest University of Technology and Economics Faculty of Mechanical Engineering Department of Polymer Engineering Műegyetem rkp. 3 Budapest 1111 Hungary ELKH–BME Research Group for Composite Science and Technology Műegyetem rkp. 3 Budapest 1111 Hungary Shanghai Jiao Tong University School of Mechanical Engineering State Key Laboratory of Mechanical System and Vibration Shanghai 200240 PR China University of Aveiro Department of Mechanical Engineering Centre for Mechanical Engineering and Automation (TEMA) Campus Santiago Aveiro 3810-193 Portugal

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Learning an Action-Conditional Model for Haptic Texture Generation

Learning an Action-Conditional Model for Haptic Texture Gene...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Negin Heravi Wenzhen Yuan Allison M. Okamura Jeannette Bohg Department of Mechanical Engineering Stanford University Robotics Institute Carnegie Mellon University Department of Computer Science Stanford University

ISBN: (数字)9781728173955

ISBN: (纸本)9781728173962

Rich haptic sensory feedback in response to user interactions is desirable for an effective, immersive virtual reality or teleoperation system. However, this feedback depends on material properties and user interactions in a complex, non-linear manner. Therefore, it is challenging to model the mapping from material and user interactions to haptic feedback in a way that generalizes over many variations of the user's input. Current methodologies are typically conditioned on user interactions, but require a separate model for each material. In this paper, we present a learned action-conditional model that uses data from a vision-based tactile sensor (GelSight) and user's action as input. This model predicts an induced acceleration that could be used to provide haptic vibration feedback to a user. We trained our proposed model on a publicly available dataset (Penn Haptic Texture Toolkit) that we augmented with GelSight measurements of the different materials. We show that a unified model over all materials outperforms previous methods and generalizes to new actions and new instances of the material categories in the dataset.

关键词： Haptic interfaces Autoregressive processes Force Acceleration Predictive models Solid modeling Discrete Fourier transforms

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Kinematic calibration of a 3RRPS metamorphic parallel mechanism

Kinematic calibration of a 3RRPS metamorphic parallel mechan...

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ASME 2020 International Design engineering Technical Conferences and Computers and Information in engineering Conference, IDETC-CIE 2020

作者： Chai, Xuheng Nurahmi, Latifah Dai, Jian S. Gan, Dongming MOE Key Laboratory for Mechanism Theory and Equipment Design International Centre for Advanced Mechanisms and Robotics Tianjin University Tianjin China Department of Mechanical Engineering Institut Teknologi Sepuluh Nopember Kampus ITS Sukolilo Surabaya60111 Indonesia Kinematics and Robotics Lab Centre for Robotics Research King’s College London Strand LondonWC2R 2LS United Kingdom School of Engineering Technology Purdue University West LafayetteIN47907 United States

ISBN: (纸本)9780791883990

In this paper, a kinematic calibration method is developed for a 3rRPS metamorphic parallel mechanism with respect to all unknown parameters. Each limb of the 3rRPS mechanism is composed of (rR), P, and S joints. Two joints are actuated, namely P and r joints, hence the mechanism is able to switch between the 3RPS parallel mechanism and 3US parallel mechanism. The geometric constraint equations of the 3rRPS mechanism are initially established. Then, the optimization problems for the base, platform and actuated prismatic lengths during given trajectory are formulated by using the global search optimization algorithm. A physical model of the 3rRPS metamorphic parallel mechanism is built and an experiment is setup to validate the proposed calibration and optimization models. The external device, i.e., the OptiTrack is used during the experiment for motion capture system. All unknown parameters are identified and optimized by dint of the geometric properties of this mechanism and nonlinear optimization algorithms. The experimental results demonstrate that the proposed calibration method is valid and effective. Copyright © 2020 ASME

关键词： Mechanisms

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