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Collaborative Fall Detection and Response using Wi-Fi Sensing and Mobile Companion Robot

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arXiv

arXiv 2024年

作者： Chen, Yunwang Kang, Yaozhong Zhao, Ziqi Hong, Yue Meng, Lingxiao Meng, Max Q.-H. The Shenzhen Key Laboratory of Robotics Perception and Intelligence Southern University of Science and Technology Shenzhen518055 China The Department of Electrical and Electronic Engineering SUSTech Shenzhen China The School of System Design and Intelligent Manufacturing SUSTech Shenzhen China

This paper presents a collaborative fall detection and response system integrating Wi-Fi sensing with robotic assistance. The proposed system leverages channel state information (CSI) disruptions caused by movements to detect falls in non-line-of-sight (NLOS) scenarios, offering non-intrusive monitoring. Besides, a companion robot is utilized to provide assistance capabilities to navigate and respond to incidents autonomously, improving efficiency in providing assistance in various environments. The experimental results demonstrate the effectiveness of the proposed system in detecting falls and responding effectively. Copyright © 2024, The Authors. All rights reserved.

关键词： Fall detection

Predicting Vibration Fatigue Strength and Three-Dimensional Fatigue Crack Growth in Simulated Compressor Blade by Phase-Field Model

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SSRN 2024年

作者： Sun, Shen Liu, Shijie He, Weiwei Zhang, Xuan Tang, Wei Zhou, Liucheng Yi, Min Nanjing210016 China Beijing Aerospace Propulsion Institute Laboratory of Science and Technology on Cryogenic Liquid Propulsion Beijing100076 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Xi’an710038 China

Vibration fatigue is a major concern for aeroengine compressor blades under complex cyclic mechanical and aero-dynamic loads, but predicting vibration fatigue behavior of blades remains challenging. Herein, a phase-field fatigue fracture model is applied to simulate the vibration fatigue behavior of the simulated compressor blade. In the phase-field model, a logarithmic degradation function is adopted to describe the fracture toughness decreasing with fatigue cycles. Vibration induced cyclic loads are mimicked by the pressure applied on the blade surface. The three-dimensional (3D) fatigue crack propagation of the simulated blade is simulated. It is found that the fatigue crack initiates at the variable cross-section and propagates horizontally. Laser shock peening (LSP) is further shown to improve the fatigue properties, i.e., LSP induced compressive residual stress results in a 95% increase of fatigue life and notably retards the 3D fatigue crack growth. For the vibration fatigue strength of both the original and LSPed blades, the predictions are within the ±5% error band. The phase-field model here provides a predictive approach for the evaluation of vibration fatigue behavior and shows a great potential in the optimal design of durable and reliable compressor blades. © 2024, The Authors. All rights reserved.

关键词： Fatigue crack propagation

GeoReF: Geometric Alignment Across Shape Variation for Category-level Object Pose Refinement

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GeoReF: Geometric Alignment Across Shape Variation for Categ...

Conference on Computer Vision and Pattern Recognition (CVPR)

作者： Linfang Zheng Tze Ho Elden Tse Chen Wang Yinghan Sun Hua Chen Ales Leonardis Wei Zhang Hyung Jin Chang Shenzhen Key Laboratory of Control Theory and Intelligent Systems School of System Design and Intelligent Manufacturing Southern University of Science and Technology China School of Computer Science. University of Birmigsham UK Department of Computer Science the University of Hong Kong China

ISBN: (数字)9798350353006

ISBN: (纸本)9798350353013

Object pose refinement is essential for robust object pose estimation. Previous work has made significant progress to-wards instance-level object pose refinement. Yet, category-level pose refinement is a more challenging problem due to large shape variations within a category and the discrep-ancies between the target object and the shape prior. To address these challenges, we introduce a novel architecture for category-level object pose refinement. Our approach in-tegrates an HS-Iayer and learnable affine transformations, which aims to enhance the extraction and alignment of Geometric information. Additionally, we introduce a cross-cloud transformation mechanism that efficiently merges di-verse data sources. Finally, we push the limits of our model by incorporating the shape prior information for translation and size error prediction. We conducted extensive ex-periments to demonstrate the effectiveness of the proposed framework. Through extensive quantitative experiments, we demonstrate significant improvement over the baseline method by a large margin across all metrics. 1 1 Project page: https://***/***

关键词： Point cloud compression Computer vision Shape Soft sensors Pose estimation Computer architecture Predictive models

Hierarchical Micro/Nano Structures with Anti-Reflection and Superhydrophobicity on the Silicon Surface Fabricated by Femtosecond Laser

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SSRN 2024年

作者： Duan, Junyu Long, Gui Xu, Xu Liu, Weiming Li, Chuankun Zhang, Jianguo Xu, Jianfeng Xiao, Junfeng State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Hubei Jiuzhiyang Infrared System Co. Ltd. Wuhan430223 China Huazhong Institute of Electro-Optics Wuhan National Laboratory for Optoelectronics Wuhan430223 China China Ship Development and Design Center Wuhan43006 China Hunan University China

In this paper, hierarchical micro/nano structures composed of periodic microstructures, LIPSS, and nanoparticles were fabricated by femtosecond laser processing. A layer of hydrophobic species was formed on the micro/nano structures through perfluorosilane modification. The reflectivity and hydrophobicity’s influence mechanisms of structural height, duty cycle, and size are experimentally elucidated. The average reflectivity of the silicon surface in the visible light band is reduced to 3.0% under the optimal parameters, and the surface exhibits a large contact angle of 172.3 ± 0.8 ° and a low sliding angle of 4.2 ± 1.4 °. Finally, the durability of anti-reflection and superhydrophobicity is also confirmed. This study deepens the understanding of the principles of anti-reflection and superhydrophobicity and expands the design and preparation methods for self-cleaning and anti-reflective surfaces. © 2024, The Authors. All rights reserved.

关键词： Femtosecond lasers

Microstructure and impact toughness of 16MND5 reactor pressure vessel steel manufactured by electrical additive manufacturing

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Journal of Iron and Steel Research International 2020年第8期27卷 992-1004页

作者： Xi-kou He Chang-sheng Xie Li-jun Xiao Ying Luo Di Lu Zheng-dong Liu Xi-tao Wang Institute for Special Steels China Iron and Steel Research InstituteBeijing 100081China Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610041SichuanChina Southern Additive Science and Technology Co. Ltd.Foshan 528225GuangdongChina

Electrical additive manufacturing can improve manufacturing efficiency and reduce the cost of 16MND5 reactor pres-sure vessel steel. Impact tests were conducted to compare the impact toughness of 16MND5 steels manufactured by the electrical additive manufacturing and conventional forging, respectively. It is found that the impact toughness of electrical additive manufacturing specimen was slightly higher than that of conventional forging specimen. The characterizations of microstructure show that there were large ferrites and carbides in electrical additive manufacturing specimen. The fracture mechanisms of electrical additive manufacturing specimen were that microvoids or microcracks were prone to nucleate at the large ferrite/bainite interface and large carbide/bainitic ferrite interface, where the stress concentration was high. In addi-tion, the block size and high-angle grain boundaries played a vital role in hindering crack propagation of electrical additive manufacturing specimen, helping to improve the impact energy and leading to a low ductile–brittle transition temperature. The results suggest that the electrical additive manufacturing technology was an effective method to enhance the impact toughness of 16MND5 steel.

关键词： Electrical additive manufacturing 16MND5 steel Impact toughness Fracture High-angle grain boundary

Unidirectional Transmission Waveguide with Polarization Locking Based on Metasurface

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Unidirectional Transmission Waveguide with Polarization Lock...

International Symposium on Antennas, Propagation and EM Theory (ISAPE)

作者： Li-jie. Chen Rui Zhou Hai Lin National Key Laboratory of Electromagnetic Effect and Security on Marine Equipment China Ship Development and Design Centre. China and School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan China College of Physical Science and Technology Central China Normal University Wuhan Hubei China

ISBN: (数字)9798350353129

ISBN: (纸本)9798350353136

When the polarization state of a system is linearly locked to momentum and its scatterers do not induce spin flips, the resulting edge state with polarization locking can demonstrate unidirectional reflectionless transmission. In classical systems, the creation of polarization-locked edge states relies on two key symmetry transformations: electromagnetic duality (EM-duality) symmetry and parity time-reversal duality (PT-duality) symmetry. While EM-duality supports infinitesimal line-surface wave modes, PT-duality facilitates line-guided wave modes. However, the transmission power capacity of these modes is typically limited by the size of the model. To overcome this limitation, our work integrates both transformation physics mechanisms to develop a chiral waveguide with miniaturization, high power, and increased capacity through the design of a tailored metasurface structure. This innovative design approach opens up new avenues in the realms of photonics and electronics, particularly in the domains of information transmission and processing.

关键词： Wireless communication Antenna theory Transmitting antennas Electromagnetic scattering Waveguide theory Information processing Metasurfaces Electromagnetics Physics Photonics

Effect of the Graphene Oxide Incorporation on the Morphology, Corrosion Resistance and Fatigue Performance of Micro-Arc Oxidation Coating on Magnesium Alloy

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SSRN 2024年

作者： Tan, Yansong Liu, Xin Sun, Xiaohao Gao, Lilan Liu, Debao Zhang, Chunqiu Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Cont rol School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineerin g Education Tianjin University of Technology Tianjin300384 China School of Materials Science and Engineering Tianjin University of Technology Tianjin300384 China

Magnesium (Mg) alloy has great potential in biomedical applications, but the rapid corrosion rate which mismatches with bone reconstruction rate limits its clinical use. In this study, the graphene oxides (GO) were added into alkaline electrolyte solution during micro-arc oxidation (MAO) process, aiming to form a corrosion resistant surface coating on Mg alloy. By changing the concentration of GO, the coatings' morphology, composition, corrosion resistance, and fatigue property were compared to reveal the strengthening mechanism and find out the optimal graphene concentration. The results show that the MAO coating is composed of MgO, Mg2SiO4, Mg3(PO4)2 and GO. The added GO exhibits excellent adsorption property in the MAO process, reducing the intermolecular gap, thereby improving densification and obturation of the MAO coating. The surface morphology of MAO coating initially improves with increasing GO content, but then deteriorates, reaching its best quality at 0.4 g/L. Compared to MAO samples without GO, the samples with 0.4g/L GO not only have lower corrosion current density of 5.226 μA/cm2, but also show higher fatigue lives both before and after pre-corrosion. This study offers a promising approach to enhance the corrosion resistance and fatigue performance of Mg alloy by applying a GO-strengthened MAO coating onto its surface. © 2024, The Authors. All rights reserved.

关键词： Magnesium alloys

Effect of the Graphene Oxide Incorporation on the Morphology, Corrosion Resistance And Fatigue Performance Of Micro-Arc Oxidation Coating on Mg Alloy

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SSRN 2024年

Mg alloy has great potential in biomedical applications, but the rapid corrosion rate which mismatches with bone reconstruction rate limits its clinical use. A protective oxide coating layer can be generated on the surface of Mg alloy by micro-arc oxidation (MAO) technique, aiming to improve the corrosion performance and long-term structural integrity of Mg alloy. In this study, the MAO coating layer of Mg alloy was improved by adding appropriate content of graphene oxide (GO) into electrolyte solution. GO has excellent adsorption property and plays a role in the MAO process, reducing the intermolecular gap, thereby improving the densification and obturation of the coating surface. With the increase of GO content, the surface morphology of the MAO coating initially has improved, then later deteriorated, and the best surface morphology has achieved at a GO content of 0.4 g/L. When the GO content increases from 0 g/L to 0.4 g/L, the corrosion current density reduces to 5.226 μA/cm2, with a reduction two orders in magnitude;in addition, at a stress amplitude of 140 MPa and a frequency of 4 Hz, the fatigue life increases from 9261 cycles to 13887 cycles without corrosion, and from 2042 cycles to 2759 cycles after pre-corrosion. This study provided a promising approach to ameliorate the morphology, corrosion resistance and fatigue performance of MAO coating on Mg alloy by elaborately configuring the electrolyte solution and customizing the process parameters. © 2024, The Authors. All rights reserved.

关键词： Corrosion resistance

Interdiffusion Behaviors and Mechanical Properties of Zr−Hf system

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SSRN 2024年

作者： Jia, Jie Liu, Ying Wang, Renquan Chen, Yuhang Sun, Yongduo He, Yong College of Materials Science and Engineering Sichuan University No.24 South Section 1 Yihuan Road Chengdu610065 China National Key Laboratory of Nuclear Reactor Technology Nuclear Power Institute of China Chengdu610213 China

In this work, Zr-Hf diffusion couples were firstly prepared by Spark Plasma Sintering (SPS) method and the diffusion behavior and mechanical properties of the Zr-Hf system in temperatures range from 1300 to 1600°C were investigated in detail. The microstructure characterization by SEM and TEM reveals that Zr-Hf diffusion zone form some amorphous and nanocrystalline grains in local area. Then the hardness and Young's modulus of the Zr-Hf system in the diffusion zone were tested and the results show that the hardness and Young’s modulus of the alloy system was enhanced by solid solution Hf element, and the maximum hardness and Young's modulus in the diffusion zone reached to 10.74GPa and 203.5GPa, respectively. Finally, based on the profiles of Electron probe microanalysis (EPMA), the interdiffusion coefficient is composition-dependent. The value calculated by Sauer-Freise method is between 10-13 m2/s and 10-11 m2/s, which indicating that SPS diffusion annealing significantly enhances the diffusion rate of the Zr-Hf system. Meanwhile, the interdiffusion coefficient decreases slowly with increasing Hf concentration. The diffusion activation energy Q and the frequency factor D0 of the Zr-Hf binary alloy in this experiment ranges from 182 to 226 kJ/mol and 8.0×10-6 to 4.1×10-5 m2/s, respectively. © 2024, The Authors. All rights reserved.

关键词： Hardness