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International Workshop on Advanced Motion Control (AMC)

作者： Daisuke Yanabe Suguru Kanoga Vincent Frémont Toshiyuki Murakami Graduate School of Science and Technology Keio University Kanagawa Japan Artificial Intelligence Research Center National Institute of Advanced Industrial Science and Technology (AIST) Tokyo Japan Ecole Centrale de Nantes Nantes Universite and CNRS LS2N Nantes France Department of System Design Engineering Keio University Kanagawa Japan

In nonlinear dynamical system identification, a flexible statistical model is commonly used for identification to compensate for non-linear elements. The flexibility in the statistical model induces a high sensitivity to the existence of external disturbances that could deteriorate the identification accuracy substantially. Most of the identification techniques assume a processing noise as a statistical variable and apply a maximum likelihood-based method to identify the dynamical system. Most of these methods do not take into account the effect of external disturbances. In this work, we also considered external disturbances as one of the statistical parameters to estimate. By estimating values for external disturbances and applying maximum a posteriori estimation, identification accuracy could be improved compared to models without considering external disturbances.

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Task-Space Riccati Feedback based Whole Body Control for Underactuated Legged Locomotion

Task-Space Riccati Feedback based Whole Body Control for Und...

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IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Shunpeng Yang Zejun Hong Sen Li Patrick Wensing Wei Zhang Hua Chen School of System Design and Intelligent Manufacturing Southern University of Science and Technology China Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology China Department of Aerospace and Mechanical Engineering University of Notre Dame USA LimX Dynamics Shenzhen China Zhejiang University-University of Illinois Urbana-Champaign Institute (ZJUI) Haining China

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

This manuscript primarily aims to enhance the performance of whole-body controllers(WBC) for underactuated legged locomotion. We introduce a systematic parameter design mechanism for the floating-base feedback control within the WBC. The proposed approach involves utilizing the linearized model of unactuated dynamics to formulate a Linear Quadratic Regulator(LQR) and solving a Riccati gain while accounting for potential physical constraints through a second-order approximation of the log-barrier function. And then the user-tuned feedback gain for the floating base task is replaced by a new one constructed from the solved Riccati gain. Extensive simulations conducted in MuJoCo with a point bipedal robot, as well as real-world experiments performed on a quadruped robot, demonstrate the effectiveness of the proposed method. In the different bipedal locomotion tasks, compared with the user-tuned method, the proposed approach is at least 12% better and up to 50% better at linear velocity tracking, and at least 7% better and up to 47% better at angular velocity tracking. In the quadruped experiment, linear velocity tracking is improved by at least 3% and angular velocity tracking is improved by at least 23% using the proposed method.

关键词： Legged locomotion systematics Angular velocity Feedback control Quadrupedal robots Intelligent robots

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Identification of the non-stationarity of extreme temperature events and teleconnections with solar activity and large-scale atmospheric circulation: A case study in the Yangtze River Economic Belt

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Journal of Earth science 2024年

作者： Lin Zhang Jingyun Ling Shengzhi Huang Hongbin Zhan Yi Wu Menggui Jin Qiang Huang State Key Laboratory of Eco-hydraulics in Northwest Arid Region， Xi'an University of Technology College of Design and Engineering， National University of Singapore Yinshanbeilu Grassland Eco-Hydrology National Observation and Research Station， China Institute of Water Resources and Hydropower Research Department of Geology and Geophysics， Texas A&M University， College Station School of Earth System Science， Tianjin University School of Environmental Studies， China University of Geosciences

In recent decades， extreme climate events have become a major problem worldwide. To understand the uncertainty in the response of extreme events to global warming， regional assessments are required for various climatic and geographic regions. The spatiotemporal distribution of extreme temperature events in the Yangtze River Economic Belt (YREB) from 1960 to 2019， including interannual changes and their teleconnections with solar activity and large-scale atmospheric circulation， were analyzed using eight indices of extreme temperature events. Over the past six decades， the climate in the YREB region has seen a warming trend， characterized by an increase in extreme warm events and a decrease in extreme cold events. The extreme temperature indices exhibit strong spatial variability. The warm extremes display a significant upward trend across the YREB， while cold extremes are primarily concentrated in the western part of the region. In recent decades， both warm and cold extremes have significant interannual variations， and these events predominantly oscillate over periods of less than four years. After 1985， the relationship between El Ni?o-Southern Oscillation (ENSO)， Arctic Oscillation (AO)， Pacific Decadal Oscillation (PDO) and extreme temperature events has changed significantly compared with pre-1985， and the direction of the phase angle can determine the positive and negative effects of the two time-series. ENSO， AO and PDO mainly have positive impacts on extreme temperature events， with ENSO and AO exerting greater impacts than PDO. In contrast， solar activity mainly has a negative impact on these events. Furthermore， the notable interdecadal changes in extreme temperature events， especially warm extremes， may be caused by the shift in the PDO phase. Therefore， the results of the study are important for the YREB region to take effective measures to mitigate the potential impacts of human activities on regional warming.

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Interspaces Between Nature and the City 22

Interspaces Between Nature and the City

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Proceedings of the Tenth International Symposium of Chinese CHI

作者： Ziqian Bai Yimin Wang Jiawei Guo Anqi Wang Hua Yue Ze Gao Zesheng Castiel Chen Xiaoyu Zhou Ziwei Pan Hao Li Yanming Sheng Jianwei Zheng Zaiwei Liu Kejia Zhang Yunhua Zhang Zerong Hong Liang Tan School of System Design and Intelligent Manufacturing Southern University of Science and Technology China Hong Kong University of Science and Technology Hong Kong University College London United Kingdom Hong Kong University of Science and Technology China University of Macau China Shandong University China Independent Artist China Future Lighting China Lighting Stories (Beijing) Cultural & Creative Co. Ltd. China Guangzhou Academy of Fine Arts China

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Preliminary development on thermal-hydraulic analysis code for the spent fuel rod under the condition of spray cooling

Preliminary development on thermal-hydraulic analysis code f...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Chao, Guo Jian, Deng Rong, Cai Yugao, Ma Lili, Liu Yuhao, Zhang Siyu, Lv Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Nuclear Science and Engineering School North China Electric Power University Changping District Beijing102206 China

ISBN: (纸本)9780791883785

According to spray cooling characteristics for failure of the cooling system in the spent fuel pool, we establish a model for analyzing spray cooling of a single spent fuel rod and develop a code named SFSC which is used to calculate the thermalhydraulic characteristics of film on the spent fuel rod under the condition of spray cooling. The results obtained from SFSC consist of film thickness, film temperature, film evaporation, fuel pellet temperature of spent fuel rod and cladding temperature of spent fuel rod at different height of spent fuel rod are shown in this paper. At the same time, we establish same model by RELAP and compare results calculated by RELAP with that calculated by SFSC. The good agreement of two results demonstrates that SFSC is effective. SFSC fills in the blanks of thermal-hydraulic calculation for the spent fuel rod under the condition of spray cooling. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Cooling

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A Novel Microwave Humidity Sensor Based on a Complementary Interdigital Capacitor Resonator

SSRN

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SSRN 2024年

作者： Wang, Litian Chen, Jie Li, Dan Qian, Lirong Xiong, Yang Miao, Lin Zhang, Rong Li, Cuiping Tianjin Key Laboratory of Film Electronic and Communication Devices School of Integrated Circuit Science and Engineering Tianjin University of Technology Tianjin300384 China School of Integrated Circuit Science and Engineering Tianjin University of Technology Tianjin300384 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Resonant for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China

This study presents a novel microwave humidity sensor that utilizes a complementary interdigital capacitor resonator (CIDCR), an advanced design derived from the traditional complementary split ring resonator (CSRR) structure. The CIDCR design enhances the sensor's performance by concentrating the electric field in a more compact region, leading to improved sensitivity and miniaturization. The sensor is coated with a composite film of chitosan (CS) and polyacrylamide-glycerol (PAMG), combining the high moisture sensitivity of PAMG with the stability of CS. The CIDCR-based sensor demonstrates superior performance, including high sensitivity, a broad detection range, rapid response/recovery times, and excellent long-term stability. Density functional theory (DFT) calculations further elucidate the moisture-sensitive mechanisms at the molecular level, highlighting the role of hydrogen bonding in the composite film. Application tests confirm the sensor's potential for use in respiratory monitoring, non-contact sensing, and health monitoring, showcasing the advantages of the CIDCR structure in achieving enhanced humidity sensing capabilities. © 2024, The Authors. All rights reserved.

关键词： Humidity sensors

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

SSRN

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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

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

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Small-Target Infrastructure Detection with Spatial Tracking and Multi-Level Feature Extraction of Railway Track Scenes

Small-Target Infrastructure Detection with Spatial Tracking ...

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Intelligent Communication, Sensing and Electromagnetics (ICSE), International Conference on

作者： Heng Du Huaiming Cang Yiwen Bai Xinyi Wang Beijing Elephant Technology Co. Ltd Beijing China School of Transportation Science and Engineering Beihang University Beijing China The State Key Lab of Intelligent Transportation System Beijing China Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China

ISBN: (数字)9798350354935

ISBN: (纸本)9798350354942

In the field of railway transportation, with the continuous improvement of train running speed and the continuous increase of operating mileage, it becomes particularly important to ensure the safety and integrity of small-target infrastructure along the railway train. Although many small-target detection methods have been proposed, the research on small-target infrastructure detection along rail trains is very rare. To solve this problem, this paper proposes a small-target infrastructure detection network with spatial tracking and multi-level feature extraction based on Yolov8n. The experimental results show that ST-YOLO has a 3.6% mAP improvement on the OSDaR23 dataset compared to the baseline Yolov8n, and shows significant advantages over other state-of-the-art methods.

关键词： Rails Transportation Railway safety Switches Feature extraction Rail transportation Real-time systems Sensors Safety Monitoring

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

SSRN

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SSRN 2024年

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

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Analysis of Age of Information in Non-terrestrial Networks

arXiv

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arXiv 2023年

作者： Lu, Yanwu Yang, Howard H. Pappas, Nikolaos Geraci, Giovanni Ma, Chuan Quek, Tony Q.S. ZJU-UIUC Institute Zhejiang University Haining China Department of Computer and Information Science Linköping University Linköping Sweden Telefonica Research Universitat Pompeu Fabra Barcelona Spain Zhejiang Lab Hangzhou China Information System and Technology Design Pillar Singapore University of Technology and Design Singapore

Non-terrestrial networks (NTN), particularly low Earth orbit (LEO) satellite networks, have emerged as a promising solution to overcome the limitations of traditional terrestrial networks in the context of next-generation (6G) wireless systems. In this paper, we focus on analyzing the timeliness of information delivery in NTN through the concept of Age of Information (AoI). We propose an on-off process to approximate the service process between LEO satellites and a source node located on the Earth’s surface. By utilizing stochastic geometry, we derive a closed-form expression for the time-average AoI in an NTN. This expression also applies to on-off processes with one component following an exponential distribution while the other has its probability density function supported on a bounded interval. Numerical results validate the accuracy of our analysis and demonstrate the impact of source status update rate and satellite constellation density on the time-average AoI. Our work fills a gap in the literature by providing a comprehensive analysis of AoI in NTN and offers new insights into the performance of LEO satellite networks. © 2023, CC BY.

关键词： Probability density function

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