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Sufficient variable selection of high dimensional nonparametric nonlinear systems based on Fourier spectrum of density-weighted derivative

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Applied Mathematics and Mechanics(English Edition) 2024年第11期45卷 2011-2022页

作者： Bing SUN Changming CHENG Qiaoyan CAI Zhike PENG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China China Academy of Launch Vehicle Technology Beijing100076China School of Mechanical Engineering Ningxia UniversityYinchuan750021China

The variable selection of high dimensional nonparametric nonlinear systems aims to select the contributing variables or to eliminate the redundant *** a high dimensional nonparametric nonlinear system,however,identifying whether a variable contributes or not is not ***,based on the Fourier spectrum of densityweighted derivative,one novel variable selection approach is developed,which does not suffer from the dimensionality curse and improves the identification ***,a necessary and sufficient condition for testing a variable whether it contributes or not is *** proposed approach does not require strong assumptions on the distribution,such as elliptical *** simulation study verifies the effectiveness of the novel variable selection algorithm.

关键词： nonlinear system identification variable selection Fourier spectrum non-parametric nonlinear system

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Fine-Grained Emotion Prediction for Movie and Television scene images

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The Journal of China Universities of Posts and Telecommunications 2024年第3期31卷 43-55页

作者： Su Zhibin Zhou Xuanye Liu Bing Ren Hui State Key Laboratory of Media Convergence and Communication Communication University of ChinaBeijing 100024China Key Laboratory of Acoustic Visual Technology and Intelligent Control System Communication University of ChinaBeijing 100024China School of Information and Communication Engineering Communication University of ChinaBeijing 100024China

For the task of content retrieval,analysis and generation of film and television scene images in the field of intelligent editing,fine-grained emotion recognition and prediction of images is of great *** this paper,the fusion of traditional perceptual features,art features and multi-channel deep learning features are used to reflect the emotion expression of different levels of the *** addition,the integrated learning model with stacking architecture based on linear regression coefficient and sentiment correlations,which is called the LS-stacking model,is proposed according to the factor association between multi-dimensional *** experimental results prove that the mixed feature and LS-stacking model can predict well on the 16 emotion categories of the self-built image *** study improves the fine-grained recognition ability of image emotion by computers,which helps to increase the intelligence and automation degree of visual retrieval and post-production system.

关键词： fine-grained emotion prediction movie and television scene images stacking model linear regression

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Snap-through behaviors and nonlinear vibrations of a bistable composite laminated cantilever shell:an experimental and numerical study

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 779-794页

作者： Lele REN Wei ZHANG Ting DONG Yufei ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanics Guangxi UniversityNanning 530004China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of TechnologyBeijing 100124China School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical *** improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric *** symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of *** motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement *** numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is *** numerical solutions are in good agreement with the experimental *** nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively *** to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.

关键词： bistable composite laminated cantilever shell snap-through behavior nonlinear vibration nonlinear stiffness characteristic chaos and bifurcation

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Ultrahigh Performance Triboelectric Nanogenerator Enabled by Charge Transmission in Interfacial Lubrication and Potential Decentralization Design

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Research 2022年第4期2022卷 519-529页

作者： Wencong He Wenlin Liu Shaoke Fu Huiyuan Wu Chuncai Shan Zhao Wang Yi Xi Xue Wang Hengyu Guo Hong Liu Chenguo Hu School of Physics State Key Laboratory of Power Transmission Equipment and System Security and New TechnologyChongqing UniversityChongqing 400044China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

Triboelectric nanogenerator (TENG) is a promising strategy for harvesting low frequency mechanical energy. However, the bottlenecks of limited electric output by air/dielectric breakdown and poor durability by material abrasion seriously restrict its further improvement. Herein, we propose a liquid lubrication promoted sliding mode TENG to address both issues. Liquid lubrication greatly reduces interface material abrasion, and its high breakdown strength and charge transmission effect further enhance device charge density. Besides, the potential decentralization design by the voltage balance bar effectively suppresses the dielectric breakdown. In this way, the average power density up to 87.26 W·m^(-2)·Hz^(-1), energy conversion efficiency of 48%, and retention output of 90% after 500,000 operation cycles are achieved, which is the highest average power density and durability currently. Finally, a cell phone is charged to turn on by a palm-sized TENG device at 2 Hz within 25 s. This work has a significance for the commercialization of TENG-based self-powered systems.

关键词： durability dielectric generator

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In situ X-ray imaging and numerical modeling of damage accumulation in C/SiC composites at temperatures up to 1200℃

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Journal of Materials Science & technology 2024年第30期197卷 65-77页

作者： Weijian Qian Wanen Zhang Shengchuan Wu Yue Hu Xiangyu Zhang Qiaodan Hu Shaoming Dong Shantung Tu State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and TechnologyShanghai 200237China

Carbon fiber reinforced silicon carbide matrix composites(C/SiC)have emerged as key materials for ther-mal protection systems owing to their high strength-to-weight ratio,high-temperature durability,resis-tance to oxidation,and outstanding ***,manufacturing defects deteriorate the mechani-cal response of these composites under extreme thermal-force coupling conditions,prompting significant research *** study demonstrates a customized in situ loading device compatible with syn-chrotron radiation facilities,enabling high spatial and temporal resolution recording of internal material damage evolution and failure behavior under thermal-force coupling *** thermal radia-tion units in a confocal configuration were used to create ultra-high-temperature environments,offering advantages of compactness,rapid heating,and *** situ tensile tests were conducted on C/SiC samples in a nitrogen atmosphere at both room temperature and 1200℃.The high-resolution image data demonstrate various failure phenomena,such as matrix cracking and pore ***-based fi-nite element simulations indicate that the temperature-dependent variation of the failure mechanism is attributable to thermal residual stresses and defect-induced stress *** work seamlessly integrates extreme mechanical testing methods with in situ observation techniques,providing a compre-hensive solution for accurately quantifying crack initiation,pore connection,and failure behavior of C/SiC composites.

关键词： Ceramic matrix composites Extreme environments X-ray computed tomography Internal damage evolution Image-based finite element method

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Development of a cable-driven redundant space manipulator with large bending angle by combining quaternion joints and segmented coupled linkages mechanism

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Chinese Journal of Aeronautics 2023年第11期36卷 483-499页

作者： Taiwei YANG Jian HUANG Wenfu XU Ke SHAO Bin LIANG School of Mechanical Engineering and Automation Harbin Institute of TechnologyShenzhen 518055China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China Department of Automation Tsinghua UniversityBeijing 100854China

A cable-driven redundant manipulator has significant potential in confined space applications, such as environmental exploration, equipment monitoring, or maintenance. A traditional design requires 3N driving motors/cables to supply 2N degrees of freedom(DOF) movement *** number of motors is 1.5 times that of the joints’ DOF, increasing the hardware cost and the complexity of the kinematics, dynamics, and control. This study develops a novel redundant space manipulator with decoupled cable-driven joints and segmented linkages. It is a 1680 mm continuum manipulator with eight DOF, consisting of four segmented linkages driven by eight motors/pairs of cables. Each segment has two equivalent DOF, which are realized by four quaternion joints synchronously driven by two linkage cables. The linkage cables of adjacent joints are symmetrically decoupled and offset at 180°. This design allows equal-angle movement of all the joints of each segment. Moreover, each decoupling driving mechanism is designed based on a pulley block composed of two fixed and movable pulleys. The two movable pulleys realize the opposite but equidistant motions of the two driving cables, i.e., pulling and loosening, assuring symmetrical movements of the two driving cables of each segment. Consequently, the equivalent 2N-DOF joints are driven only by 2N motors, significantly reducing the hardware cost and simplifying the mapping relationship between the motor angle/cable length and the joint angle. Furthermore, the bending range of each segment could reach 360°, which is three times that of a traditional design. Finally, a prototype has been developed and experimented with to verify the performance of the proposed mechanism and the corresponding algorithms.

关键词： Cable-driven Mechanism design Redundant manipulators Segmented linkages Kinematics

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Influence of different anodised nanoporous structures on the anti-icing and electrical properties of transmission Al lines

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High Voltage 2025年第1期10卷 167-177页

作者： Xu Dai Yuan Yuan Jie Xiao Chenghao Jiang Xujiang Hua Huiying Xiang Tao Zhu Guoyong Liu Jiang Zhou Ruijin Liao State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina College of Materials Science and Engineering Chongqing UniversityChongqingChina Dongfang Electric Machinery Co. LtdDeyangChina

Ice accumulation of overhead transmission lines can lead to serious damage to power *** nanostructured Al conductors are proposed to replace the de-icing or ice-melting equipment for economic advantages,good anti-icing properties and robust electrical *** under different direct current densities is adopted to fabricate two nanostructures on Al conductors,including the reticular and honeycomb-like nanoporous *** to pure Al conductors,the anodised surface of honeycomb-like nanoporous structures exhibits lower ice adhesion(3.82 kPa)and ice *** conductor steel reinforced treated in the proposed method has also been validated to exhibit a significant anti-glaze icing ***-tionally,corona performance and line loss are experimentally measured and calculated to prove good electrical *** 0.27 A Al strand shows the highest corona inception voltage(27.86 kV)and the lowest AC resistance(4.65Ω/km),which is attributed to the good dielectric property and heat ***,the proposed anti-icing transmission conductors show profound application potential for power systems.

关键词： electrical structures properties

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A hardware acceleration Framework of Reconfigurable Edge Modules for Convolutional Neural Networks 50

A hardware acceleration Framework of Reconfigurable Edge Mod...

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50th Annual Conference of the IEEE Industrial Electronics Society, IECON 2024

作者： Qiao, Yiming Jia, Zidi Li, Shixiang Ren, Lei Beihang University Beijing China Beihang University Zhongguancun Laboratory State Key Laboratory of Intelligent Manufacturing System Technology Beijing China

ISBN: (纸本)9781665464543

Edge computing exploits node devices situated in close proximity to terminals to deliver distributed computing services directly to users, with FPGAs serving as the predominant platform. With the amplification in volume and intricacy of deep learning models, effectively deploying these models on FPGA devices introduces substantial challenges. To counter this predicament, this paper introduces an FPGA-based hardware acceleration framework for reconfigurable edge devices tailored for Convolutional Neural Networks (CNNs). Initially, a method for dynamically quantizing network models is devised to markedly curtail model memory consumption. Subsequently, a meticulously engineered hardware acceleration unit is formulated to attain augmented computing parallelism via meticulous temporal redesign. Finally, model deployment on FPGA devices for inference verification is showcased utilizing fully connected and convolutional neural networks as exemplars. On the MNIST dataset, the FPGA inference unit attains remarkable accuracy and computational efficiency in comparison to CPUs and GPUs. © 2024 IEEE.

关键词： Convolutional neural networks

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25%-Efficiency flexible perovskite solar cells via controllable growth of SnO_(2)

iEnergy

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iEnergy 2024年第1期3卷 39-45页

作者： Ningyu Ren Liguo Tan Minghao Li Junjie Zhou Yiran Ye Boxin Jiao Liming Ding Chenyi Yi State Key Laboratory of Power System Operation and Control Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

High power conversion efficiency(PCE)flexible perovskite solar cells(FPSCs)are highly desired power sources for aerospace crafts and flexible ***,their PCEs still lag far behind their rigid ***,we report a high PCE FPSC by controllable growth of a SnO_(2)electron transport layer through constant pH chemical bath deposition(CBD).The application of SnSO_(4)as tin source enables us to perform CBD without strong acid,which in turn makes it applicable to acid-sensitive flexible indium tin ***,a mild and controllable growth environment leads to uniform particle growth and dense SnO_(2)deposition with full coverage and reproducibility,resulting in a record PCE of up to 25.09%(certified 24.90%)for FPSCs to *** as-fabricated FPSCs exhibited high durability,maintaining over 90% of their initial PCE after 10000 bending cycles.

关键词： Flexible perovskite solar cells chemical bath deposition SnO_(2) electron transport layer

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Performance analysis of multi-group three-tuple cross-eye jamming

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Journal of systems Engineering and Electronics 2022年第1期33卷 80-90页

作者： CHEN Jiabei SHI Qingzhan HUANG Zhaoyu WANG Qingping YUAN Naichang State Key Laboratory of Complex Electromagnetic Environmental Effects of Electronics and Information System National University of Defense TechnologyChangsha 410000China

Monopulse radar is widely used in *** monopulse radar has always been a research hotspot in electronic warfare(EW).Cross-eye jamming has always been considered as the most effective measures to jam with monopulse *** this paper, we propose a multi-group three-tuple crosseye jamming structure where each group contains three antenna elements with a definite phase and an amplitude ***, based on the principle of monopulse angle measurement, the error angle is deduced *** show that such a multi-group three-tuple cross-eye jamming structure performs better than the multi-element cross-eye jamming structure previously proposed, and the analysis of the centroid shows that the centroid of the structure proposed in this paper is more widely distributed in space.

关键词： electronic warfare(EW) angular deception jamming cross-eye jamming three-tuple antenna array near field

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