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SSRN 2023年

作者： Wang, Quan Wang, Fei Li, Zhongheng Wang, Zheng Nie, Feiping Institute of Artificial Intelligence and Robotics Xi’an Jiaotong University Shaanxi Xi’an710049 China Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications Beijing Institute of Spacecraft System Engineering Beijing100094 China School of Software Engineering Xi’an Jiaotong University Xi’an710049 China Northwestern Polytechnical University Shaanxi Xi’an710072 China

Joint clustering and dimensionality reduction methods are a promising solution to clustering due to its scalability to high-dimensional data. Some methods leverage trace ratio criterion and attain clusters by borrowing the K-means algorithm. However, trace ratio criterion has no close-formed solution for the discriminative projection matrix and the K-means algorithm has a limited capacity to handle the many-cluster problem. In this paper, Coordinate Descent Clustering with Trace Difference criterion (CDCTD) is proposed for joint clustering and feature extraction. Formulating the objective function as a direct trace difference criterion containing a balance parameter, CDCTD harmonizes between-cluster scatter maximization and within-cluster scatter minimization by the balance parameter. Using the direct trace difference criterion, CDCTD can straightforward solve for the discriminative projection matrix and avoid obtaining a poor discriminative projection matrix in the iterative manner when a bad cluster start is given. CDCTD uses the coordinate descent method for clustering, improving the ability to address the many-cluster problem. Extensive experiments show that CDCTD has achieved significant performance improvements compared to previous trace ratio criterion related joint clustering and feature extraction methods, and also outperformed other clustering methods in most cases. © 2023, The Authors. All rights reserved.

关键词： Feature extraction

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Effects of TiO2 nanoparticles and electrode materials on impulse breakdown performance of propylene carbonate under uneven electric field

Effects of TiO2 nanoparticles and electrode materials on imp...

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22nd International Symposium on High Voltage Engineering (ISH 2021)

作者： S. Wu Q. Yang Z. Zhang W. He State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing 400044 China

Liquid dielectrics are widely used in power systems owing to their excellent insulation properties. Nanoparticles and electrode materials have demonstrated a great capability of enhanced dielectric of base insulation liquids. In this study, the impulse breakdown performance of TiO 2 nanoparticles doped propylene carbonate under an uneven electric field was investigated. We first proposed a measurement method for the uneven electric field under the blade electrode using an 8-channel array photodetector. The effects of nanoparticles and aluminum, copper, and stainless-steel electrodes on the breakdown voltage and electric field distribution characteristics of the liquid were studied. These results indicate that the breakdown voltage of the stainless steel electrode is the most significant polarity effect under an uneven electric field. The negative impulse breakdown voltage of the liquid under the stainless steel electrode is 24.6% higher than that of the positive polarity. The positive breakdown voltage of the TiO 2 nanoparticles doped propylene carbonate under aluminum and copper increased by 25% and 17.2%, however, it is no obvious increase under the stainless steel electrode. The TiO 2 nanoparticles capture electrons in the space charge zone which inhibits the development of streamers, and weakens the influence stage of electrode materials. For the negative polarity, the weakening of the polarity effect promotes the development of the streamer, resulting in a decrease in the breakdown voltage. This study enriches the discharge mechanism of liquids in uneven electric fields and provides a valuable reference for improving the liquid insulation performance and the discharge mechanism.

关键词： aluminium copper dielectric liquids discharges (electric) nanoparticles photodetectors polymers space charge stainless steel titanium compounds

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Quantification of Full-Field Stress in Continuously Loaded Fractured Rocks Using 3d Printing and Digital Photoelasticity

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SSRN 2023年

作者： Wan, Changbing Jin, Jidong Wang, Linjuan Wang, Jianxiang Ju, Yang State Key Laboratory of Turbulence and Complex System Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China School of Astronautics Beihang University Beijing100191 China State Key Labortaory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and Technology at Beijing D11 Xueyuan RD Beijing100083 China

Accurately characterizing stress fields in fractured rocks is crucial for understanding fracture propagation and rock failure mechanisms. However, existing methods struggle to quantify stress fields in continuously loaded fractured rocks with complex fracture networks. In this study, we propose a novel method that utilizes 3D printing and digital photoelasticity to quantify full-field stress in complex fractured rocks under continuous loading. Our method incorporates three key components: a modified global fringe thinning technique for automatic extraction of fringe skeletons, an optimized phase calculation process for efficient phase unwrapping, and a proposed algorithm for accurate determination of fringe orders through the identification of near-zero-order fringe regions. The effectiveness and accuracy of our method are validated through theoretical analysis and comparison with results obtained from the ten-step phase shifting method. Furthermore, our proposed method can also be applied to quantify stress fields in fractured rocks under static loading. © 2023, The Authors. All rights reserved.

关键词： Elasticity

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A New Reduced Reaction Mechanism of the Surrogate Fuel for RP-3 Kerosene

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SSRN 2022年

作者： Liu, Jing Hu, Erjiang Zheng, Weilin Zeng, Wen Chang, Yachao State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shangxi Xi’an710049 China Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University Liaoning Shenyang110136 China Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education Dalian University of Technology Dalian116024 China

By combining the reaction class-based global sensitivity analysis (RC-GSA) methodology, species sensitivity analysis (SSA) methodology, decoupling method and genetic algorithm (GA), a reduced reaction mechanism of the surrogate fuel (10% n-dodecane/14% n-decane/30% iso-hexadecane/36% methylcyclohexane/10% toluene, in mole fraction) for RP-3 kerosene was constructed. As an example, the detailed construction process of skeleton mechanism of methylcyclohexane (MCH) was presented, and the skeleton mechanism constructions of other components in the surrogate fuel were similar to that of MCH. First, the dominant reaction classes in the fuel-relevant mechanism of MCH were recognized by the RC-GSA, the representative species in each retained reaction classes were selected by the SSA, and the skeleton fuel-relevant mechanism of MCH was developed. Second, through combining the skeleton fuel-relevant mechanism of MCH with the reduced reaction mechanism of C 0 -C 3 by the decoupling method, the initial skeleton mechanism of MCH was obtained. Third, based on the GA, the rate constants of fuel-relevant reactions in the initial skeleton mechanism of MCH were optimized to enhance the prediction performance. Finally, by coupling the skeleton reaction mechanisms of n-dodecane, n-decane, toluene, iso-hexadecane, MCH, and the reduced reaction mechanism of C 0 -C 3 , a reduced mechanism (containing 121 species and 469 reactions) of the surrogate fuel for RP-3 kerosene was formed. The predicted main species concentrations during the oxidation process in the jet-stirred reactor, the ignition delay times in the shock tube and laminar flame speeds in the constant volume bomb by this reduced mechanism are in good agreement with the corresponding experimental data of RP-3 kerosene. © 2022, The Authors. All rights reserved.

关键词： Sensitivity analysis

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Study on the Lightning Strike Discharge Characteristics of Air Gap at Low Air Pressure Condition 3

Study on the Lightning Strike Discharge Characteristics of A...

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3rd International Conference on Electrical Materials and Power Equipment, ICEMPE 2021

作者： Jin, Li Xinhan, Zhu Qiang, Wang Zhijin, Zhang Xingliang, Jiang China Railway First Survey and Design Institute Group Co. Ltd. China Railway Construction Corporation Limited Xi'an China Chongqing University State Key Laboratory of Power Transmission Equipment System Security and New Technology Chongqing China

ISBN: (纸本)9781665418409

The average altitude of Qinghai Tibet railway is 4000m. The correct and reasonable design of air gap of electrical insulation is the technical bottleneck to determine the clearance height of Qinghai Tibet railway tunnel and the design of overhead contact system insulation structure. However, it costs a lot to carry out the typical air gap true type test in the actual site with an average altitude of 4000m and above. Therefore, it is necessary to establish tunnel model by using the large-scale multi-functional artificial climate chamber of Chongqing University, to test and study the insulation characteristics of typical air gap under different applied voltages. According to the actual parameters of the tunnel, the stainless steel ceiling is built. Since the Golmud - Lhasa section of Qinghai Tibet railway is in single line operation, the vertical plane where the highest line of ceiling is located is taken as the measurement datum of catenary. The constant voltage rise and fall method and uniform voltage rise method recommended by IEC60507, GB / t4585, DL / t859 and other standards are used to test the breakdown characteristics of air gap. The 50% breakdown voltage under lightning impulse voltage is obtained by constant voltage rise and fall method, and the breakdown voltage under AC power supply is obtained by uniform voltage rise method. The altitude parameters are classified according to 500m, and the atmospheric parameters of 3500∼5500m are simulated. The altitude correction methods based on (d, P, h) and (d, δ, h) are respectively used to fit the test data to obtain the lightning impulse discharge voltage correction formula of the air insulation gap. The test results show that the error between the calculation results and the test results is less than 5.0%, which means that the test and fitting meet the engineering requirements. The calculation results show that: (1) The lightning impulse voltage of the air gap at high altitude is a function of air pressure, tempe

关键词： Electric breakdown

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A disordered composite metamaterial beam optimized using NSGA-Ⅱ:a structure with an adjustable hybrid bandgap

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European Journal of Mechanics - A/Solids 2025年 114卷

作者： Wentao Wu Xiaobiao Shan Chenghui Sun Guangdong Sui Tianci Jiang Huan Zhang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China Institute of Ultra-precision Optoelectronic Instrument Engineering Harbin Institute of Technology Science Park No.2 Yikuang Street Nangang District Harbin 150080 China

To address the limitations of conventional periodic metamaterials in regulation and optimization, this study introduces a novel staggered supercell beam configuration designed to enhance low-frequency vibration isolation. The proposed supercell beam is composed of single cells with varying staggered degrees and inductances. Initially, the transmission matrix method was employed to model both symmetrical and staggered structures, enabling the determination of their attenuation constant and transmission coefficient. Subsequently, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was implemented for multi-objective optimization to identify Pareto frontiers. Theoretical analysis demonstrated that the staggered beam exhibits a lower attenuation constant than its symmetrical counterpart and, critically, introduces a new coupling bandgap at low frequencies. Experimental transmission coefficient measurements confirmed that the optimized staggered beam achieves superior low-frequency vibration isolation performance compared to the symmetrical beam. This improvement is attributed to the successful application of NSGA-II, which effectively balances bandgap width and attenuation constant—a challenge previously unresolved in the field, as evidenced by studies that have explored the maximum limits of attenuation constants and the influence of parameters such as resistance, piezoelectric sheet thickness, and lattice constant length on bandgap characteristics. The findings of this study demonstrate that the proposed disordered staggered supercell beam configuration, optimized with NSGA-II, achieves superior bandgap attenuation, offering significant potential for advancements in low-frequency vibration isolation research.

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A comprehensive channel and feature selection method for myoelectric pattern recognition 22

A comprehensive channel and feature selection method for myo...

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22nd IEEE International Conference on E-Health Networking, Application and Services, HEALTHCOM 2020

作者： Li, Mengyao Ma, Yue Zheng, Liangsheng Wang, Can Feng, Wei Wu, Xinyu Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Hong Kong Guangdong-Hong Kong-Macao Joint Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China

ISBN: (纸本)9781728162676

The advent of myoelectric control schemes provides promising chances for locomotion empowerment and restoration of those with disabilities. Despite substantial efforts have been made into advancing sEMG-based motion recognition, it may be a little tricky to determine appropriate muscles and features for people with muscle disorders or different muscle use preferences. To mitigate it, an advantageous sEMG channel and feature selection method based on ReliefF algorithm was proposed. Related experiments were conducted on a eight able-bodied subject database to showcase the feasibility and efficiency of the proposed approach, that is, considerably high classification performance was maintained with the original feature set reduced by more than half. Ulteriorly, we also investigated the influences of different number of neighbors or features on classification accuracy for ascertaining the optimal values. The strengths of our proposed method lie in not only customizing channel and feature selection for individual users, but also offering preliminary insight for a general mapping mechanism between human muscles and corresponding motions. © 2021 IEEE.

关键词： Feature Selection

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Foot Arch Stiffness-Based Dynamic Plantar Support Control of Human Walking Gait with Active Pneumatic Insoles

Foot Arch Stiffness-Based Dynamic Plantar Support Control of...

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

作者： Chenhao Liu Jingang Yi Long He Yijun Zhang Xiufeng Zhang Tao Liu State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical Engineering Zhejiang University Hangzhou China Department of Mechanical and Aerospace Engineering Rutgers University Piscataway NJ USA Zhiyuan Research Institute Hangzhou China Department of Orthopedics The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou China Key Laboratory of Rehabilitation Technical Aids Technology and System of the Ministry of Civil Affairs National Research Center for Rehabilitation Technical Aids Beijing China

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

The human foot arch plays a significant role in bearing weight, keeping balance, and walking efficiently. In this study, we present a pneumatic arch support insole (PASI) and a foot arch stiffness-based dynamic plantar support control to reduce the metabolic cost of walking. We first obtain the foot arch quasi-stiffness estimation over the gait phase by conducting multiple subject experiments. The design and modeling of the PASI and foot-insole interactions are then discussed. A model predictive control scheme is presented to dynamically regulate the foot arch stiffness over the gait phase by using the active PASI. We validate the system experimentally and conduct multi-subject walking tests. The results show that dynamic plantar support control of the foot arch stiffness reduces the metabolic cost by 7.99% compared to regular walking. In contrast, passive support without dynamic regulation increases the metabolic cost by 6.60%. The new pneumatic insoles and dynamic support method demonstrate promising potential for everyday and medical applications.

关键词： Legged locomotion Biomedical equipment Costs Estimation Medical services Regulation Intelligent robots Foot Predictive control

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Handwritten digit recognition based on corner detection and convolutional neural network 2

Handwritten digit recognition based on corner detection and ...

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2020 2nd International Conference on Artificial Intelligence Technologies and Application, ICAITA 2020

作者： Zhong, Chen Wang, Yuhang Zhang, Decheng Wang, Ke Shenyang Fire Science and Technology Research Institute MEM Shenyang Liaoning110034 China State Key Laboratory of Robotics and Systems Harbin Institute of Technology Harbin Heilongjiang150080 China

In the field of inspection and testing, it is necessary to manually fill a large number of test record forms, and the digital information accounts for a large proportion in the record forms. For the purpose of automatic and accurate recognition of handwritten form data, this paper proposes a handwritten digit recognition method based on Harris corner detection algorithm and convolutional neural network(CNN). The Harris corner detection algorithm is used to identify the positioning marks in the form image, which determine the possible fill-in positions of handwritten digits. Through a 14-layer CNN model, and using the ReLu function as the excitation function, the handwritten digit features of the target area in the image are recognized. The experimental results show that the average recognition accuracy rate of this method on the test set can reach 98.14%. So a technical solution for intelligent recognition of record forms is thus provided. © 2020 Published under licence by IOP Publishing Ltd.

关键词： Convolutional neural networks

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Bandgap Engineering of Resorcinol-Formaldehyde Resin for Efficient H2o2 Photosynthesis from Air and Water

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SSRN 2024年

作者： Wang, Wuming Tang, Yuyang Ran, Jiaqi Teng, Wei Peng, Cheng Xu, Zuxin Chu, Wenhai State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and Engineering Tongji University Shanghai200092 China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092 China International Joint Research Center for Sustainable Urban Water System Tongji University Shanghai200092 China Key Laboratory of Interfacial Physics and Technology Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201800 China Tongji University China

On-site photosynthesis of hydrogen peroxide (PHP) from water and oxygen presents a promising vision for decentralized production technology of H2O2 at low concentration. Bandgap structure is crucial to photocatalyst for efficient H2O2 photosynthesis. Here we presented a sulfur-doping strategy to modulate the bandgap structure of resorcinol-formaldehyde (RF) resin to enhance the photocatalytic activity and stability. Results revealed the optimized bandgap structure of sulfur-doped RF enables an outstanding performance, with the solar-to-chemical conversion efficiency exceeding 0.6% after 24 h. Over sulfur-doped RF, oxygen can not only undergo a one-step two-electron reduction to produce H2O2, but an additional pathway, a two-step single-electron indirect reduction pathway, also occurs. Besides, PHP solution exhibited adequate disinfection efficiency in E. coli suspend and natural water, while its disinfection by-product (DBP) formation was negligible. This study provides valuable insights into designing efficient photocatalyst for practical applications, offering a sustainable and low-energy consumption technology for decentralized water disinfection. © 2024, The Authors. All rights reserved.

关键词： Photosynthesis

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