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arXiv 2023年

作者： Zhang, Shiyun Jin, Weiwei Wang, Dong Xu, Ding Zhang, Jerry Shattuck, Mark D. O’Hern, Corey S. Department of Physics University of Science and Technology of China Anhui Hefei230026 China Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Strain-controlled isotropic compression gives rise to jammed packings of repulsive, frictionless disks with either positive or negative global shear moduli. We carry out computational studies to understand the contributions of the negative shear moduli to the mechanical response of jammed disk packings. We first decompose the ensemble-averaged, global shear modulus as hGi = (1 − F−)hG+i + F−hG−i, where F− is the fraction of jammed packings with negative shear moduli and hG+i and hG−i are the average values from packings with positive and negative moduli, respectively. We show that hG+i and h|G−|i obey different power-law scaling relations above and below pN2 ∼ 1. For pN2 > 1, both hG+iN and h|G−|iN ∼ (pN2)β, where β ∼ 0.5 for repulsive linear spring interactions. Despite this, hGiN ∼ (pN2)β0 with β0 & 0.5 due to the contributions from packings with negative shear moduli. We show further that the probability distribution of global shear moduli P(G) collapses at fixed pN2 and different values of p and N. We calculate analytically that P(G) is a Gamma distribution in the pN2 1 limit. As pN2 increases, the skewness of P(G) decreases and P(G) becomes a skew-normal distribution with negative skewness in the pN2 1 limit. We also partition jammed disk packings into subsystems using Delanunay triangulation of the disk centers to calculate local shear moduli. We show that the local shear moduli defined from groups of adjacent triangles can be negative even when G > 0. The spatial correlation function of local shear moduli C(~r) displays weak correlations for pn2sub −2, where nsub is the number of particles within each subsystem. However, C(~r) begins to develop long-ranged spatial correlations with four-fold angular symmetry for pn2sub & 10−2 © 2023, CC BY-NC-ND.

关键词： Elastic moduli

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A Comparative Study of Human Activity Recognition: Motion, Tactile, and multi-modal Approaches

arXiv

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arXiv 2025年

作者： Belcamino, Valerio Le, Nhat Minh Dinh Luu, Quan Khanh Carfì, Alessandro Ho, Van Anh Mastrogiovanni, Fulvio TheEngineRoom Department of Informatics Bioengineering Robotics and System Engineering University of Genoa Genoa Italy Faculty of Mechanical Engineering The University of Danang University of Science and Technology Danang 54 Nguyen Luong Bang Da Nang550000 Viet Nam Soft Haptics Lab School of Materials Science Japan Advanced Institute of Science and Technology Nomi923-1292 Japan

Human activity recognition (HAR) is essential for effective Human-Robot Collaboration (HRC), enabling robots to interpret and respond to human actions. This study evaluates the ability of a vision-based tactile sensor to classify 15 activities, comparing its performance to an IMU-based data glove. Additionally, we propose a multi-modal framework combining tactile and motion data to leverage their complementary strengths. We examined three approaches: motion-based classification (MBC) using IMU data, tactile-based classification (TBC) with single or dual video streams, and multi-modal classification (MMC) integrating both. Offline validation on segmented datasets assessed each configuration’s accuracy under controlled conditions, while online validation on continuous action sequences tested online performance. Results showed the multi-modal approach consistently outperformed single-modality methods, highlighting the potential of integrating tactile and motion sensing to enhance HAR systems for collaborative robotics. © 2025, CC BY.

关键词： Collaborative robots

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Correction to: An Easy-to-Fabricate Cell Stretcher Reveals Density-Dependent mechanical Regulation of Collective Cell Movements in Epithelia

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Cellular and molecular bioengineering 2021年第6期14卷 661-662页

作者： Kevin C Hart Joo Yong Sim Matthew A Hopcroft Daniel J Cohen Jiongyi Tan W James Nelson Beth L Pruitt Department of Biology Stanford University Stanford CA 94305 USA. IGM Biosciences Mountain View CA 94043 USA. Department of Mechanical Engineering Stanford University Stanford CA 94305 USA. Sookmyung Women's University Seoul 04310 Republic of Korea. Red Dog Research Santa Barbara CA 93109 USA. Department of Mechanical Engineering University of California 494 UCEN Rd Santa BarbaraSanta Barbara CA USA. Department of Mechanical and Aerospace Engineering Princeton University Princeton NJ 08544 USA. Department of Biophysics Stanford University Stanford CA 94305 USA. Department of Cellular and Molecular Pharmacology University of California San Francisco San Francisco CA 94143 USA. Biomolecular Science and Engineering Program University of California Santa Barbara Santa Barbara CA 93106 USA.

[This corrects the article DOI: 10.1007/s12195-021-000689-6.].

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Development of wind turbines for urban environment using innovative design thinking methodology

Journal of Engineering Research

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Journal of engineering Research 2024年

作者： Claudia V. Campos Rubio Mohamed Kchaou Paulo Eustáquio de Faria Juan C. Campos Rubio Faris Alqurashi Environmental Engineering Master Program Universidade de Trás-os-Montes e Alto Douro Quinta de Prados Vila Real 5000-801 Portugal Department of Mechanical Engineering College of Engineering University of Bisha P.O. Box 551 Bisha 61922 Saudi Arabia Production Engineering Department Universidade Federal de Minas Gerais Campus Pampulha An-tônio Carlos 6627 Belo Horizonte MG CEP 31270-901 Brazil Mechanical Engineering Department Universidade Federal de Minas Gerais Campus Pampulha An-tônio Carlos 6627 Belo Horizonte MG CEP 31270-901 Brazil

This work focuses mainly on wind energy usage as a renewable source for energy generation in urban environments, where the variability of air current flow is a challenge. One of the main objectives to be achieved in this study is to develop small vertical wind turbines. Design thinking methodology was used to innovative ideas development using the application of concepts from rapid prototyping (additive manufacturing). As a target object to idealize an innovative product, was the providing of a mobile equipment recharging system, using the air current generated by the urban public transport vehicles. As a result, a modular system of small power generation was produced, tested, and validated. The mini-turbine with the best performance in power generation in wind flows lower than 4 m/s was the VAWT, which achieved the smallest difference, 18 % greater. Therefore, it was demonstrated that the installation of small wind turbines in an urbanized area requires a minimum of wind measurements at the exact location to validate the innovative design.

关键词： Wind generator Clean technology Innovation Urban environment Green energy

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Universal mechanical response of metallic glasses during strain-rate-dependent uniaxial compression

arXiv

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arXiv 2022年

作者： Jin, Weiwei Datye, Amit Schwarz, Udo D. Shattuck, Mark D. O'Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Department of Chemical and Environmental Engineering Yale University New HavenCT06520 United States Benjamin Levich Institute Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Experimental data on the compressive strength σmax versus strain rate Ε eng for metallic glasses undergoing uniaxial compression shows significantly different behavior for different alloys. For some metallic glasses, σmax decreases with increasing Ε eng, for others, σmax increases with increasing Ε eng, and for others σmax versus Ε eng is nonmonotonic. Using numerical simulations of metallic glasses undergoing uniaxial compression at nonzero strain rate and temperature, we show that they obey a universal relation for the compressive strength versus temperature, which determines their mechanical response. At low Ε eng, increasing strain rate leads to increases in temperature and decreases in σmax∗, whereas at high Ε eng, increasing strain rate leads to decreases in temperature and increases in σmax∗. This non-monotonic behavior of σmax∗ versus temperature causes the nonmonotonic behavior of σmax∗ versus Ε eng. Variations in the internal dissipation change the characteristic strain rate at which the nonmonotonic behavior occurs. These results are general for a wide range of metallic glasses with different atomic interactions, damping coefficients, and chemical compositions. © 2022, CC BY.

关键词： Strain rate

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Influence of cutting parameters on surface topography in high-speed milling of slots in titanium alloy TC4

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IOP Conference Series: Materials Science and engineering 2022年第1期1235卷

作者： S Kurpiel J Krupa K Zagórski J Cieślik Faculty of Mechanical Engineering and Robotics Department of Manufacturing Systems AGH University of Science and Technology al. Mickiewicza 30 30-059 Cracow Poland

This paper summarizes the experimental investigation of influence of process parameters on surface quality and dimensional accuracy of slots milled in titanium alloy TC4. Samples were milled using a 10 mm HXT coated monolith end mill for HSM milling of superalloys and titanium alloys. Process parameters, such as rotational speed, feed rate, and depth of cut were selected based on the Taguchi L9 method. After machining samples were measured, including surface quality parameters such as roughness, waviness and dimensional deviations. Measurement results indicate that within inspected parameter range rotational speed to feed ratio has a greater influence on surface quality than the depth of cut while having less influence on dimensional accuracy.

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Diopside-based bioactive glass-ceramic nanoparticles for osteoimmunomodulation

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Ceramics International 2025年

作者： Latt, Sun Sotoudehbagha, Pedram Cardenas, Valeria Larraza, Andres Razavi, Mehdi Cluster Department of Medicine University of Central Florida College of Medicine OrlandoFL32827 United States Burnett School of Biomedical Sciences University of Central Florida College of Medicine OrlandoFL32827 United States Department of Materials Science and Engineering University of Central Florida OrlandoFL32816 United States Biomedical Engineering Program Department of Mechanical and Aerospace Engineering University of Central Florida OrlandoFL32816 United States

The objective of this study was to develop and characterize an osteoimmunomodulatory diopside-based glass-ceramic nanoparticle synthesized using a sol-gel synthesis method. Hydroxyapatite nanoparticles were utilized as a gold standard control. X-ray diffraction, transmission electron microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, dynamic light scattering, and zeta-potential analysis were performed to characterize the crystalline phase, morphology, microstructure, composition, hydrodynamic size distribution, and surface charge, respectively. Weight loss, pH, and ion release were measured after immersion of glass-ceramic nanoparticles in simulated body fluid to evaluate the nanoparticle's biodegradation, showing ranges of Ca2+, Mg2+, and Si4+ ion release previously found to be osteogenic and angiogenic. Cytocompatibility with human bone-marrow-derived mesenchymal stem cells and murine RAW264.7 macrophages was studied using metabolic activity (MTT) and live/dead fluorescent assays, demonstrating dose-dependent cytotoxicity in RAW264.7 cells and excellent biocompatibility with mesenchymal stem cells. The effect of the nanoparticles on M1/M2 macrophage polarization potential was evaluated through ELISA and phase-contrast image analysis. Our glass-ceramic nanoparticle promoted greater M2-associated anti-inflammatory IL-1ra cytokine release than M1-associated pro-inflammatory TNF-α release compared to hydroxyapatite nanoparticles, though significant morphological changes were not observed. These results indicate that our glass-ceramic nanoparticle is a promising osteoimmunomodulatory biomaterial for bone regenerative applications. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Stem cells

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Robotic Cane as a soft superlimb for elderly sit-to-stand assistance

arXiv

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arXiv 2020年

作者： Wu, Xia Liu, Haiyuan Liu, Ziqi Chen, Mingdong Wan, Fang Fu, Chenglong Asada, Harry Wang, Zheng Song, Chaoyang Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen Guangdong518055 China SUSTech Institute of Robotics Southern University of Science and Technology Shenzhen Guangdong518055 China Department of Mechanical Engineering MIT CambridgeMA02138 United States

Many researchers have identified robotics as a potential solution to the aging population faced by many developed and developing countries. If so, how should we address the cognitive acceptance and ambient control of elderly assistive robots through design? In this paper, we proposed an explorative design of an ambient SuperLimb (Supernumerary Robotic Limb) system that involves a pneumatically-driven robotic cane for at-home motion assistance, an inflatable vest for compliant human-robot interaction, and a depth sensor for ambient intention detection. The proposed system aims at providing active assistance during the sit-to-stand transition for at-home usage by the elderly at the bedside, in the chair, and on the toilet. We proposed a modified biomechanical model with a linear cane robot for closed-loop control implementation. We validated the design feasibility of the proposed ambient SuperLimb system including the biomechanical model, our result showed the advantages in reducing lower limb efforts and elderly fall risks, yet the detection accuracy using depth sensing and adjustments on the model still require further research in the future. Nevertheless, we summarized empirical guidelines to support the ambient design of elderly-assistive SuperLimb systems for lower limb functional augmentation. Copyright © 2020, The Authors. All rights reserved.

关键词： Developing countries

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The structure of molten F 7 LiNaK with CeF 3 using neutron diffraction and EPSR

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Journal of Nuclear Materials 2025年

作者： G.S. Rakib Jörg C. Neuefeind Susan Michelle Everett Rebecca Mills Melissa A. Rose Shao-Chun Lee Y Z Brent J. Heuser Nuclear Plasma and Radiological Engineering University of Illinois Urbana-Champaign Urbana Illinois 61801 United States Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 United States Chemical & Fuel Cycle Technologies Division Argonne National Laboratory Lemont Illinois 60439 United States Department of Nuclear Engineering and Radiological Sciences Department of Materials Science and Engineering Department of Robotics and Applied Physics Program University of Michigan Ann Arbor Michigan 48105 United States

The local structure of eutectic F 7 LiNaK (Li-7 enriched, 0.465 7 LiF-0.115NaF-0.42KF) which has potential cooling applications in molten salt reactors (MSR), is studied using neutron diffraction. The nearest neighbor distances and the coordination numbers of constituent ion pairs are derived from the total neutron scattering data using empirical potential structure refinement (EPSR) software. A combination of Lennard-Jones and Coulomb 12-6-1 potential (without empirical adjustments) is used that captures the local structure of F 7 LiNaK from simulated 3D atomic configurations. The effect of adding the actinide surrogate cerium on the F 7 LiNaK local structure is also studied using neutron diffraction and EPSR with the same potential model. By comparing the results with previous experimental and computational findings, the effectiveness of EPSR in analyzing complex molten salt structures is demonstrated. The use of EPSR with simple potential models to describe the physical structures of molten salts can offer a computationally efficient approach, reducing both cost and time.

关键词： FLiNaK cerium EPSR molten salt neutron diffraction local structure

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Intuitive tasks planning using visuo-tactile perception for human robot cooperation

arXiv

引用

arXiv 2021年

作者： Katyara, Sunny Ficuciello, Fanny Teng, Tao Chen, Fei Siciliano, Bruno Caldwell, Darwin G. Department of Advanced Robotics Istituto Italiano di Tecnologia Via Morego 30 Genova16163 Italy Department of Information Technology and Electrical Engineering PRISMA Lab University of Naples Federico II Naples80125 Italy Universita Cattolica del Sacro Cuore Via E.Parmense 84 Piacenza29122 Italy Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Hong Kong

Designing robotic tasks for co-manipulation necessitates to exploit not only proprioceptive but also exteroceptive information for improved safety and autonomy. Following such instinct, this research proposes to formulate intuitive robotic tasks following human viewpoint by incorporating visuo-tactile perception. The visual data using depth cameras surveils and determines the object dimensions and human intentions while the tactile sensing ensures to maintain the desired contact to avoid slippage. Experiment performed on robot platform with human assistance under industrial settings validates the performance and applicability of proposed intuitive task formulation. © 2021, CC BY.

关键词： Robot programming

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