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2nd Spring International Conference on Defence technology, ICDT 2020

作者： Nie, Weirong Liu, Guowei Zhang, Runduo School of Mechanical Engineering Nanjing University of Science and Technology Nanjing China Science and Technology on Electromechanical Dynamic Control Laboratory Xi'an China

This paper proposes an innovation microfluidic inertial switch structure with precise time delay response characteristic, which can be used in the fuze safety and arming system. The switch works on the principle of fluidic inertial force and capillary valve, which makes it sensitive to the unidirection acceleration load and has the ability to recognize the acceleration amplitude. The microfluidic inertial switch has a structure of a J-shaped reservoir, capillary valves, a serpentine delay microchannel and a U-shaped latching microchannel. The acceleration threshold is analyzed theoretically considering the surface tension coefficient of the gas-liquid interface. The delay response time of the switch is studied by finite element simulation based on the Gambit 2.4 and Fluent 6.3 software. The prototype is fabricated by wet etching technology and magnetron sputtering metal technology. Many tests have been done to verify the functions of the switch. The experimental results are matched well to the results of calculation and simulation. When the capillary valve throat widths are 80μm, 120μm, 160μm, the thresholds of the switch are 75.1g, 46.6g, 36.5g. When the switch is loaded with a 75g acceleration load, the delay response is 146.7ms. Finite element simulation and experimental results show that the switch can effectively identify the acceleration threshold, and can achieve a precise delay response under a certain load. © Published under licence by IOP Publishing Ltd.

关键词： Microchannels

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Strong Electromagnetic Protection Circuit for RF Front End of Autodyne Radio Fuze

Strong Electromagnetic Protection Circuit for RF Front End o...

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

作者： Cheng Wang Wei Chen Rui-Hu Wen Science and Technology on Electromechanical Dynamic Control Laboratory China Xi'an Electromechanical Information Technology Research Institute

ISBN: (纸本)9781665418133

In order to solve the problem that the RF front end of autodyne radio fuze is weak in resisting high-power and energy-based jamming, a design method of electromagnetic protection circuit for RF front end is proposed. The method is to add an electromagnetic protection circuit composed of microwave limiter, RF band-pass filter, and single pole double throw switch, which between RF front-end circuit and transceiver antenna of the autodyne radio fuze. The electromagnetic protection of RF front-end core high-frequency devices is carried out by means of excess energy attenuation, selection of passing frequency, and transmission channel locking. Experimental verification shows that the electromagnetic protection circuit can protect the RF front end of the Autodyne radio fuze in both the frequency domain and the time domain, and improve the survivability of the fuze in the high EM environment.

关键词： Radio frequency Microwave antennas Design methodology Microwave theory and techniques Microwave circuits Transceivers Electromagnetics

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Pedestrian Dead Reckoning Assisted by Motion Pattern Recognition

SSRN

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SSRN 2022年

作者： Yang, Wanpeng Li, Qing Beijing Information Science & Technology University Beijing100192 China Beijing Key Laboratory of High Dynamic Navigation Technology Beijing100192 China Ministry of Education Key Laboratory of Modern Measurement & Control Technology Beijing100192 China

The pedestrian dead reckoning (PDR) system based on inertial measurement units (IMU) has become the preferred indoor positioning device because it adapts to the environment without beacons. Aiming at the problem of PDR positioning error accumulation and heading divergence over time in complex motion mode, this paper proposes a dead reckoning algorithm assisted by adaptive human motion pattern recognition. Firstly, a feature-level LSTM-CNN network is designed to recognize human motion. Secondly, the step frequency detection threshold and step length parameters are adaptively determined according to the recognized motion mode. The UKF fusion filter combined with IMU and magnetometer is used to solve the problem of heading divergence. In addition, the barometer is introduced to calculate the 3D position information. The experimental results show that the average accuracy of motion recognition can reach 96.83%. In multi-storey buildings, the horizontal positioning error is 0.8925m, and the elevation positioning error is 0.9010m © 2022, The Authors. All rights reserved.

关键词： Pattern recognition

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Water absorptivity and frost resistance performance of self-ignition coal gangue autoclaved aerated concrete

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Journal of Infrastructure Preservation and Resilience 2021年第1期2卷 1-10页

作者： Cong, Xinyu Tan, Yiqiu Lu, Shuang Wang, Zhaojia Huang, Tianyong School of Transportation Science and Engineering Harbin Institute of Technology Huanghe Road 73 Harbin150090 China School of Civil Engineering Harbin Institute of technology Harbin150090 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education 9 Harbin Institute of Technology Harbin150090 China State Key Laboratory of Solid Waste Reuse for Building Materials Beijing Building 11 Materials Academy of Science Research Beijing100041 China

Self-ignition coal gangue (SCG) used as one of precursors to fabricate autoclaved aerated concrete (AAC). Aiming at studying water absorptivity and frost resistance performance of SCG-based AAC (SCGAAC), three-period water absorption tests and freeze-thaw tests were carried out and the corresponding results were recorded and analyzed. In order to modify the water absorptivity of SCGAAC, foam stabilizer was applied to adjust pore structure while calcium stearate was expected to change hydrophilic feature of SCG. It was demonstrated that the compressive strength of SCGAAC containing foam stabilizer or calcium stearate declined at different levels. For water absorption, foam stabilizer failed to decrease the water content and even increased water absorption rates. Calcium stearate controlled water absorption rate successfully although the ultimate water content hardly reduced. All of the SCGAAC samples exhibited intact appearance after 50 freeze-thaw cycles and showed excellent frost resistance performance. Three models were proposed to predict water absorptivity and frost resistance performance of SCGAAC and the corresponding prediction results matched test resulted well. © The Author(s) 2021.

关键词： Coal

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A mechanical model for polyhedral oligomeric silsesquioxane (Poss) reinforced amorphous polyethylene 6th

A mechanical model for polyhedral oligomeric silsesquioxane ...

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6th International Conference on Mechanical Structures and Smart Materials, ICMSSM 2020

作者： Li, Yufeng Xiong, Yanyi Fan, Chenyang Wang, Zhijun Xiao, Youcai The 713 Research Institute of China State Shipbuilding Corporation Limited Zhengzhou China College of Mechatronic Engineering North University of China Taiyuan030051 China Science and Technology on Electromechanical Dynamic Control Laboratory Xian710000 China

ISBN: (纸本)9783035736861

The mechanical behavior of polyethylene (PE) co-polymerized with polyhedral oligomeric silsesquioxane (POSS) was studied by using molecular simulations. Simulation configurations consisted of aligned PE chains with POSS were attached to the central chain and amorphous PE chains with different content POSS. From the simulations with aligned PE chains with POSS, it was found that the method for reinforcement was due to dislocation pile-up at POSS, and above a critical stress the dislocations traverse the POSS causing a sawtooth variation in the load-displacement curve. The stress-strain curves for amorphous PE-POSS bulk showed distinct elastic and plastic straining stages. Plastic straining consisted of hardening and slipping segments attributed to dislocation pile-up and chain sliding. Computational results were used to develop a reinforcement model to describe the mechanical response of PE-POSS bulk under uniaxial tension. © 2021 Trans Tech Publications Ltd, Switzerland Online: 2021-02-01.

关键词： Polyethylenes

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Mapping-based drift fault repair method for array inertial devices

Mapping-based drift fault repair method for array inertial d...

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9th International Symposium on Test Automation & Instrumentation (ISTAI 2022)

作者： H. Chen Z. Su Z. Xu Q. Li Beijing Key Laboratory of High Dynamic Navigation Technology Beijing Information Science & Technology University Beijing People's Republic of China Key Laboratory of Modern Measurement and Control Technology Ministry of Education Beijing Information Science & Technology University Beijing People's Republic of China

The array inertial device can significantly improve the positioning accuracy of the wearable autonomous positioning system, but it is difficult to avoid faults in the working process of the array inertial device, even if the fault is detected, the positioning system will fail. Aiming at the fault that the acceleration drift of array inertial device increases in the process of motion in the wearable autonomous positioning system of emergency rescue personnel, a fault repair method of acceleration array based on BP neural network was proposed. Through data fusion of accelerometer and gyroscope, a fault repair method based on mapping contrast elimination is implemented. The experimental results of twelve IMU array data fusion and fault repair show that the proposed method can be used to repair the typical faults with the increase of accelerometer drift in the array inertial device.

关键词： accelerometers backpropagation fault diagnosis gyroscopes inertial systems sensor fusion

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Unsupervised Feature Enrichment and Fidelity Preservation Learning Framework for Skeleton-based Action Recognition

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IEEE Transactions on Circuits and Systems for Video technology 2025年

作者： Li, Chuankun Li, Shuai Gao, Yanbo Gao, Xingyu Chen, Ping Li, Jian Li, Wanqing North University of China State Key Laboratory of Dynamic Testing Technology School of Information and Communication Engineering Taiyuan030051 China Shandong University School of Control Science and Engineering School of Software Jinan250100 China Chinese Academy of Sciences Institute of Microelectronics Beijing100029 China University of Wollongong Advanced Multimedia Research Lab WollongongNSW2522 Australia

Unsupervised skeleton-based action recognition has achieved remarkable progress recently. Existing unsupervised learning methods suffer from severe overfitting problem, and thus small networks are used, significantly reducing the representation capability. To address this problem, the overfitting mechanism behind the unsupervised learning for skeleton-based action recognition is first investigated. It is observed that skeleton is already a relatively high-level and low-dimension feature, but not in the same manifold as the features for action recognition. Simply applying the existing unsupervised learning method tends to produce features that discriminate the different samples rather than action classes, resulting in the overfitting problem. To address this problem, this paper proposes an Unsupervised spatial-temporal Feature Enrichment and Fidelity Preservation (U-FEFP) learning framework to generate rich distributed features that contain all the information of a skeleton sample. A spatial-temporal feature transformation subnetwork is developed using channel-wise topology refinement graph convolutional block and graph convolutional gated recurrent unit block as the basic feature extraction network. The unsupervised Bootstrap Your Own Latent-based learning is utilized to generate rich distributed features, and the unsupervised pretext task-based learning is employed to preserve the information contained in the skeleton. The two unsupervised learning ways are collaborated as U-FEFP to produce robust and discriminative representations. Experimental results on four widely used benchmarks, namely NTU-RGB+D-60, PKU-MMD, NTU-RGB+D-120 and UAV-Human dataset, demonstrate that the proposed U-FEFP obtains the best result compared with the state-of-the-art unsupervised learning methods. © 1991-2012 IEEE.

关键词： Convolution

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Modeling and Analysis of a Non-linear Electret Electrostatic Energy Harvester 3

Modeling and Analysis of a Non-linear Electret Electrostatic...

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3rd IEEE International Conference on Automation, Electronics and Electrical Engineering, AUTEEE 2020

作者： Niu, Shaohua Gao, Chunhui Chen, Jian Beijing Institute of Technology Science and Technology on Electromechanical Dynamic Control Laboratory Beijing China Beijing Power Machinery Institute Beijing China

ISBN: (纸本)9781728198279

With the rapid development of MEMS and CMOS sensors and improvement of data processing capabilities we have entered the era of the internet of everything (IoE), and the ensuing problem of sensor power supply has attracted more and more people's attention. Vibration energy harvester that can directly convert vibration energy into electrical energy from the environment have become hot topics in recent years because of the short life, large size, long-term storage and other shortcomings of traditional chemical batteries. The electrostatic vibration energy harvester is a typical harvester, which always uses beam structure to capture the environmental energy. However the working bandwidth of traditional beam is always relatively narrow, while the vibration frequency range of environment is relatively wide. Thus the capture energy efficiency of traditional beam structure is relatively low. In this paper, a nonlinear method is introduced into electret electrostatic energy harvester, which employed magnetic body structure to introduce nonlinear force. In the paper, the model of this nonlinear harvest is built, and its characteristics are analyzed. According the analysis result, magnetic force introduced can improve capture energy bandwidth, moreover, repulsive force expands the bandwidth larger than attractive force. © 2020 IEEE.

关键词： Bandwidth

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Structural Optimization Design of H-type Piezoelectric Actuator Based on APDL 8

Structural Optimization Design of H-type Piezoelectric Actua...

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8th Annual International Conference on Material science and Engineering, ICMSE 2020

作者： Rui, Suyuan Wang, Xinjie School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Science and Technology on Electromechanical Dynamic Control Laboratory Xi'an710065 China

Aiming at the problem of low efficiency in optimizing the H-type piezoelectric actuator with the "trial method", this article uses a program written in the APDL (ANSYS Parametric Design Language) to optimize the structure of the piezoelectric actuator. First, a parametric finite element model is established based on the initial data values of the mover structure. Modal analysis and sensitivity analysis are performed to determine the design variables. Then, the objective function is determined based on the frequency consistency of the two-phase working modes. Finally, based on the optimization tool proposed in this paper, the structure of the H-type piezoelectric actuator is optimized. The optimization results show that the optimization program based on APDL can achieve the optimal design requirements of the H-type piezoelectric actuator and shorten the time required for structural optimization design. © Published under licence by IOP Publishing Ltd.

关键词： Piezoelectric actuators

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Terminal Impact-angle-constrained Guidance Law of Miniature Munition Based on High-order Fully Actuated System Approach

Terminal Impact-angle-constrained Guidance Law of Miniature ...

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Chinese Automation Congress (CAC)

作者： Shiwei Chen Junfang Fan Wei Wang Yi Ji Ning Liu School of Aerospace Engineering Beijing Institute of Technology Beijing China Beijing Key Laboratory of UAV Autonomous Control Beijing Institute of Technology Beijing China Beijing Key Laboratory of High Dynamic Navigation Technology Beijing Information Science & Technology University Beijing China

Aiming at the terminal impact-angle constraint in the interception of large maneuvering targets by munition, this paper proposes a three-dimensional(3D) maneuvering target interception guidance law combined with the high-order fully-actuated (HOFA) system theory based on biased proportional navigation guidance (BPNG). First, a complete second-order nonlinear model with fully-actuation is built for munition-target relative motion without the small-angle assumption. Second, the nonlinear system of the munition-target relative motion is transformed into a quasi-feedback system, and a HOFA model is developed for the system. A BPNG law with the linear relationship of the line-of-sight angle is introduced to transform the closed-loop system into a linear time-invariant closed-loop system with the expected characteristic structure. Finally, target maneuver information is taken as the model compensation and adopted as the external input of the closed-loop system together with the remainder of the guidance law; thus, the channel coupling of the nonlinear three-dimensional system is eliminated. The effectiveness of the proposed method is verified by simulation results.

关键词： Couplings Solid modeling Three-dimensional displays Navigation Weapons Simulation Line-of-sight propagation

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