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Characterization and mechanical Behaviour of Nano-Al2O3 Reinforced Polymer Composites

Journal of The Institution of Engineers (India): Series D 2024年 1-12页

作者： Mahesh, K.S. Satheesh, J. Department of Robotics & amp Automation JSS Academy of Technical Education Bengaluru India Department of Mechanical Engineering SJB Institute of Technology Bengaluru India

This study presents an experimental investigation into the mechanical behaviour and characterisation of Nano-Al2O3 reinforced polymer composites, aiming to enhance the understanding of their structural performance. The incorporation of nanoscale Al2O3 particles into polymer matrices has gained attention for its potential to improve the mechanical properties of the resulting composites. In this research, 1 wt% Nano-Al2O3 was dispersed within a polymer matrix through a systematic fabrication process. The mechanical behaviour of the developed composites was evaluated through a comprehensive set of experiments, including compression testing, flexural testing, and impact testing. The results provided insights into the effects of Nano-Al2O3 content on the strength, stiffness, and impact resistance of the composites. Microstructural characterisation using techniques such as scanning electron microscopy and X-ray diffraction were employed to analyse the dispersion of nanoparticles and the resulting changes in the composite structure. The findings from this experimental investigation contribute to the current knowledge base on Nano-Al2O3 reinforced polymer composites and offer valuable information for optimising the fabrication process to achieve desired mechanical properties. © The Institution of Engineers (India) 2024.

关键词： Compression testing

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High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

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Defence Technology（防务技术） 2023年第11期29卷 153-163页

作者： R.Praveen S.R.Koteswara Rao G.Selvakumar R.Damodaram Department of Robotics and Automation Karpaga Vinayaga College of Engineering and TechnologyChengalpattu603308TamilNaduIndia Department of Mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringChennai603110TamilNaduIndia

In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). Base Material(BM) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from BM to WN, HAZ and TMAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TMAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the BM and WN. On the other hand, TMAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(ASB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关键词： Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration

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JADFER: Exploring Spatial-Contextual Interaction with Joint Attention Dropping for Facial Expression Recognition

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IEEE Transactions on Affective Computing 2024年第2期16卷 655-668页

作者： Gao, Yu Ren, Weihong Jiang, Weibo Dong, Qian Nie, Wei Wu, Wenhao Liu, Honghai Harbin Institute of Technology State Key Lab of Robotics and Systems School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China

Facial Expression Recognition (FER) aims to categorize emotional expressions depicted on a human face, and is a challenging task under unconstrained conditions, such as face occlusions and pose variations. Recent methods usually adopt self attention or cross attention to explore global or local relationships among different level features. However, these methods are inclined to focus on the redundant facial regions, causing model overfitting. To address this problem, we propose a new FER model named JADFER, which drops the joint attention in the weight matrix to adaptively enhance facial expression representations. Specifically, our JADFER model consists of three components: Spatial Branch (SB), Contextual Branch (CB), and Spatial-Contextual Interaction (SCI). Firstly, SB runs N paths in parallel, where a Variety loss is designed to guide the paths of SB to focus on different discriminative regions. Meanwhile, CB abstracts the contextual facial representations using self attention with Joint Attention Dropping (JAD). Then, the SCI adopts the spatial features from SB to query the contextual representations from CB through cross attention with JAD, which regulates the attention weights by dropping the similar activations to further enhance the facial embeddings. Experimental results demonstrate that the proposed model outperforms the state-of-the-art methods on several FER benchmarks. © 2010-2012 IEEE.

关键词： Face recognition

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DexTouch: Learning to Seek and Manipulate Objects with Tactile Dexterity

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IEEE robotics and Automation Letters 2024年第12期9卷 10772-10779页

作者： Lee, Kang-Won Qin, Yuzhe Wang, Xiaolong Lim, Soo-Chul Dongguk University Department of Mechanical Robotics and Energy Engineering Seoul04620 Korea Republic of University of California San Diego CA United States

The sense of touch is an essential ability for skillfully performing a variety of tasks, providing the capacity to search and manipulate objects without relying on visual information. In this paper, we introduce a multi-finger robot system designed to manipulate objects using the sense of touch, without relying on vision. For tasks that mimic daily life, the robot uses its sense of touch to manipulate randomly placed objects in dark. The objective of this study is to enable robots to perform blind manipulation by using tactile sensation to compensate for the information gap caused by the absence of vision, given the presence of prior information. Training the policy through reinforcement learning in simulation and transferring the trained policy to the real environment, we demonstrate that blind manipulation can be applied to robots without vision. In addition, the experiments showcase the importance of tactile sensing in the blind manipulation tasks. Our project page is available at https://***/dextouch/ © 2016 IEEE.

关键词： Reinforcement learning

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Tailoring the in-plane and out-of-plane stiffness of soft fingers by endoskeleton topology optimization for stable grasping

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Science China(Technological Sciences) 2023年第11期66卷 3080-3089页

作者： LI DeChen CHEN ShiTong SONG ZeNan LIANG JiaLong ZHU XiangYang CHEN FeiFei State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Meta Robotics Institute Shanghai Jiao Tong UniversityShanghai 200240China

The intrinsic compliance of soft materials endows soft robots with great advantages to achieve large deformation and adaptive interactions in grasping ***,current soft grippers usually focus on the in-plane large deformation and load capacity but ignore the effect of out-of-plane external loads,which may lead to instability in practical *** problem calls for stiffness design along multiple directions to withstand not only in-plane interacting forces with objects,but also unexpected outof-plane *** this paper,we design a new type of soft finger by embedding an endoskeleton inside the widely-used PneuNets actuator,and the endoskeleton layout is optimized to achieve a remarkable bending deflection and limited lateral deflection under combined external in-plane and out-of-plane *** on the multi-objective topology optimization approach,the key structural features of the optimized endoskeleton are extracted and *** multi-material soft fingers are fabricated by the silicone compound mold *** and dynamic experiment results validate that the soft gripper with endoskeleton embedded exhibits remarkably improved out-of-plane stiffness,without sacrificing the in-plane bending flexibility,and leads to more stable grasping.

关键词： soft robot soft gripper stable grasping topology optimization pneumatic actuator

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Orifice plate surface temperature measurement of a LaB6 hollow cathode using a near-infrared two-color radiation thermometer

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Journal of Electric Propulsion 2024年第1期3卷 1-19页

作者： Oshio, Yuya Hirai, Keito Watanabe, Hiroki Horisawa, Hideyuki Funaki, Ikkoh Mechanical Engineering and Robotics Course Ryukoku University Otsu-Shi520-2194 Japan Department of Mechanical Engineering Tokai University Hiratsuka259-1292 Japan Japan Aerospace Exploration Agency Kanagawa Sagamihara252–5210 Japan

This study measured the two-dimensional orifice plate surface temperature of a 20-A-class LaB6 hollow cathode using a near-infrared two-color radiation thermometer. The thermometer technique resolved the orifice plate temperature with an accuracy of approximately 166 ℃. With this technique, the surface temperature of the orifice plate was found nearly uniform, with no observed temperature gradient on the orifice plate. Consequently, the operational characteristics of the hollow cathode are discussed in relation to the average surface temperature. Data analysis revealed that the orifice plate temperature was not sensitive to the mass flow rate;conversely, it was highly sensitive to the discharge current. Moreover, for the same input power, the orifice plate temperature was higher in the high-current, low-voltage mode also known as the spot mode indicating efficient emitter heating. The measurement system developed in this study provides a more precise evaluation of the orifice plate temperature and allows for estimating the internal conditions of a hollow cathode, thus facilitating more appropriate design evaluations under various operating conditions. © The Author(s) 2024.

关键词： Infrared devices

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Identification of robot dynamic model and joint frictions using a baseplate force sensor

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Science China(Technological Sciences) 2022年第1期65卷 30-40页

作者： WU JianHua LI Wang XIONG ZhenHua Institute of Robotics School of Mechanical EngineeringShanghai Jiao Tong University.Shanghai 200240China

Dynamic models play an important role in robot control and *** accurate identification of dynamic models has become crucial to meeting increasing performance *** to the inertial forces and the joint frictions coupling,the identification first requires a parametrized friction ***,the joint frictions are strongly nonlinear and vary with many factors including posture,velocity and ***,all friction models have some deviation from the real values,which reduces the identification *** paper proposes an identification approach using a baseplate force *** identifies the inertial parameters first and then computes the joint friction values by subtracting the inertial torques from the joint *** method has the advantage that it does not require a priori friction *** can choose or construct a proper model to fit the real values and is thus expected to achieve high *** on a 6-DoF robot were conducted to verify the proposed method.

关键词： robot dynamic model model identification joint friction

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Energy-exergy and exergoeconomic analysis of a hydrogen-enriched spark-ignition engine fueled with premium gasoline-ethanol blends

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International Journal of Hydrogen Energy 2025年 137卷 689-709页

作者： Kumbhar, Sujit Khot, Sanjay Bhapkar, Udaysinh Patil, Vishal Singh, Paramvir Husainy, Avesahemad Department of Technology Shivaji University Kolhapur India Automation and Robotics Department Sharad Institute of Technology College of Engineering Yadrav Ichalkaranji India Mechanical Engineering Department Sharad Institute of Technology College of Engineering Yadrav Ichalkaranji India Kolhapur India Department of Mechanical Engineering National Institute of Technology Agartala India

Hydrogen is a promising alternative fuel for internal combustion engines due to its renewable nature, low emissions, and superior combustion performance. In the current research, the effects of hydrogen enrichment were studied on the thermodynamic analysis of spark ignition engines using premium gasoline-ethanol blends. The blends were prepared with a partial addition of ethanol (10 % and 20 % by volume) in premium gasoline and hydrogen was injected during combustion for 2, 3, 4, and 5 μs. The testing was done on the varying engine speeds at 1500, 2000, 2500, 3000, and 3500 rpm. Energy and exergy analyses, entropy generation, and sustainability index were assessed for different fuel blends and contrasted with premium gasoline. The brake thermal efficiency and exergy efficiency were found maximum at 2500 rpm engine speed for all tested fuel blends. The BTE of E10H5 fuel blend is 18 % higher than premium gasoline and the exhaust gas energy of the E10H5 fuel blend is 12 % higher than premium gasoline at 2500 rpm. Among all tested fuel blends, the E10H5 fuel blend showed prominent results. The present experimental investigation focuses on energy-exergy analyses of premium gasoline-ethanol blends with enriched hydrogen at different injection times to assess the potential fuel blends. These blends will help to reduce dependency on conventional fossil fuels by enriching hydrogen without modification of the engine. © 2025 Hydrogen Energy Publications LLC

关键词： Hydrogen engines

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Bifunctional nanoprobe for simultaneous detection of intracellular reactive oxygen species and temperature in single cells

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Microsystems & Nanoengineering 2024年第6期10卷 161-172页

作者： Yanmei Ma Weikang Hu Jian Hu Muyang Ruan Jie Hu Ming Yang Yi Zhang Hanhan Xie Chengzhi Hu Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Department of Mechanical and Energy EngineeringSouthern University of Science and TechnologyShenzhen 518000China Department of Electrical and Electronic Engineering Southern University of Science and TechnologyShenzhen 518000China

Living cells can rapidly adjust their metabolic activities in response to external stimuli,leading to fluctuations in intracellular temperature and reactive oxygen species(ROS)*** these parameters is essential for understanding cellular metabolism,particularly during dynamic biological *** this study,we present a bifunctional nanoprobe capable of simultaneous measurement of ROS levels and temperature within single *** nanoprobe features two individually addressable nanoelectrodes,with platinum(Pt)and nickel(Ni)coatings on both *** the tip,these two metal layers form a nano-thermocouple,enabling precise intracellular temperature measurements,while the Pt layer facilitates selective ROS *** dual functionality allows for real-time monitoring of cellular responses during synergistic chemo-photothermal therapy of cancer cells and zebrafish embryos subjected to mitochondrial toxic *** results demonstrate that the nanoprobe effectively measures increases in temperature and ROS levels in HeLa cells undergoing chemo-photothermal therapy,as well as in chemically stimulated zebrafish *** providing detailed analysis of submicrometer-scale temperature and ROS variations within living cells,this nanoprobe offers valuable insights into cellular processes and holds promise for early disease detection and drug development.

关键词： metabolism simultaneous holds

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Measurement of LaB6 hollow cathode emitter region temperature and plasma characteristics

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Journal of Electric Propulsion 2025年第1期4卷 1-19页

作者： Oshio, Yuya Masuyama, Shogo Watanabe, Hiroki Funaki, Ikkoh Mechanical Engineering and Robotics Course Ryukoku University Otsu-Shi520-2194 Japan Japan Aerospace Exploration Agency Kanagawa Sagamihara252–5210 Japan

Hollow cathodes are widely used as electron sources in electric propulsion systems owing to their high electron generation efficiency. Research findings allude to the significant impact of the temperature and plasma characteristics of the emitter region of a hollow cathode, which supplies thermionic electrons, on its operation. However, these characteristics are not yet fully understood. The objective of this study is to investigate these characteristics under different orifice diameters and operating conditions. The emitter temperature increased with the discharge current for both orifice diameters. The electron density was higher downstream for larger orifice diameters. The emitter temperature was compared with the orifice temperature and was found to be lower than the latter for smaller orifices. © The Author(s) 2025.

关键词： Plasma diagnostics

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