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Mechanical properties of cement-based rocks with arc-shaped cracks under uniaxial compression

Construction and Building Materials 2025年 484卷

作者： Wang, Pu Zhang, Mei Chen, Huidan Zhang, Chuanyang Ma, Fuwu Zheng, Pengqiang College of Resources Shandong University of Science and Technology Shandong Tai'an271000 China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and Technology Anhui Huainan232001 China Shandong Key Laboratory of Intelligent Prevention and Control of Dynamic Disaster in Deep Mines Shandong University of Science and Technology Qingdao266590 China Shandong Province Research Institute of Coalfield Geology Planning and Exploration Shandong jinan250000 China

This research uses cement-based rock as the subject, preparing cement-based rock-like samples with arc-shaped cracks with a 45° dip angle and different scales (similar in morphology but different in size). Combining uniaxial compression tests with FLAC3D numerical simulation, this study systematically investigates the effects of arc-shaped crack scale on the mechanical properties, energy evolution, and failure patterns of rock masses. The results show that: ① The bearing capacity of cement-based rock-like masses with arc-shaped cracks of different scales varies significantly. The peak strength is highest at λ-20 mm (crack chord length 28.28 mm, arch height 5.86 mm, corresponding to arc-shaped crack radius 20 mm) at 24.57 MPa, while λ-40 mm shows the minimum peak strength at 8.52 MPa. This indicates that larger arc-shaped crack scales result in lower overall bearing capacity of cement-based rock-like materials, making them more prone to instability failure. ② Energy evolution patterns differ across specimens with different crack scales, with larger λ values exhibiting more pronounced stress concentration and acoustic emission activity, as well as earlier yielding and instability. Among these, cement-based rock-like specimens with λ-50 mm have the shortest time to instability failure, while samples with λ-10 mm maintain stability for the longest duration. ③ Failure morphologies of cement-based rock-like materials with different scale arc-shaped cracks show considerable differences. Crack initiation occurs first at both tips of the arc-shaped crack, with secondary crack propagation and coalescence being the primary causes of instability. However, as λ increases, secondary cracks appear earlier, and the development, propagation, and coalescence speed of cracks progressively intensifies, resulting in increasingly severe damage. ④ Speckle characteristics during failure show significant similarities and differences across specimens with different crack scales. Strain conce

关键词： Compression testing

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Underdetermined direction of arrival estimation with nonuniform linear motion sampling based on a small unmanned aerial vehicle platform

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Defence technology（防务技术） 2024年第3期33卷 352-363页

作者： Xinwei Wang Xiaopeng Yan Tai An Qile Chen Dingkun Huang Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suffers from significant performance degradation owing to the limited number of physical *** improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform,we propose a nonuniform linear motion sampling underdetermined DOA estimation *** the motion of the UAV platform,the echo signal is sampled at different ***,according to the concept of difference co-array,a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom(DOFs).Through position analysis of the original and motion arrays,we propose a nonuniform linear motion sampling method based on ULA for determining the optimal *** the condition of no increase in the aperture of the physical array,the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of *** results of numerical simulations conducted herein verify the superior performance of the proposed method.

关键词： Unmanned aerial vehicle(UAV) Uniform linear array(ULA) Direction of arrival(DOA) Difference co-array Nonuniform linear motion sampling method

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Parameter estimation method for a linear frequency modulation signal with a Duffing oscillator based on frequency periodicity

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Chinese Physics B 2023年第8期32卷 237-246页

作者：张宁哲闫晓鹏吕明慧陈秀梅黄鼎琨 Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

In view of the complexity of existing linear frequency modulation(LFM)signal parameter estimation methods and the poor antinoise performance and estimation accuracy under a low signal-to-noise ratio(SNR),a parameter estimation method for LFM signals with a Duffing oscillator based on frequency periodicity is proposed in this *** method utilizes the characteristic that the output signal of the Duffing oscillator excited by the LFM signal changes periodically with frequency,and the modulation period of the LFM signal is estimated by autocorrelation processing of the output signal of the Duffing *** this basis,the corresponding relationship between the reference frequency of the frequencyaligned Duffing oscillator and the frequency range of the LFM signal is analyzed by the periodic power spectrum method,and the frequency information of the LFM signal is *** results show that this method can achieve high-accuracy parameter estimation for LFM signals at an SNR of-25 dB.

关键词： linear frequency modulation(LFM)signal Duffing oscillator frequency periodicity parameter estimation

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Adaptive target and jamming recognition for the pulse doppler radar fuze based on a time-frequency joint feature and an online-updated naive bayesian classifier with minimal risk

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Defence technology（防务技术） 2022年第3期18卷 457-466页

作者： Jian Dai Xin-hong Hao Ze Li Ping Li Xiao-peng Yan Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing100081China

This paper considers the problem of target and jamming recognition for the pulse Doppler radar fuze(PDRF).To solve the problem,the matched filter outputs of the PDRF under the action of target and jamming are ***,the frequency entropy and peak-to-peak ratio are extracted from the matched filter output of the PDRF,and the time-frequency joint feature is *** on the time-frequency joint feature,the naive Bayesian classifier(NBC)with minimal risk is established for target and jamming *** improve the adaptability of the proposed method in complex environments,an online update process that adaptively modifies the classifier in the duration of the work of the PDRF is *** experiments show that the PDRF can maintain high recognition accuracy when the signal-to-noise ratio(SNR)decreases and the jamming-to-signal ratio(JSR)***,the applicable analysis shows that he ONBCMR method has low computational complexity and can fully meet the real-time requirements of PDRF.

关键词： Pulse Doppler radar fuze(PDRF) Target and jamming recognition Time-frequency joint feature Online-update naive Bayesian classifier minimal risk(ONBCMR)

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Blind parameter estimation of pseudo-random binary code-linear frequency modulation signal based on Duffing oscillator at low SNR

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Chinese Physics B 2021年第5期30卷 312-319页

作者： Ke Wang Xiaopeng Yan† Ze Li Xinhong Hao Honghai Yu Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

Conventional parameter estimation methods for pseudo-random binary code-linear frequency modulation(PRBC-LFM)signals require prior knowledge,are computationally complex,and exhibit poor performance at low signal-to-noise ratios(SNRs).To overcome these problems,a blind parameter estimation method based on a Duffing oscillator array is proposed.A new relationship formula among the state of the Duffing oscillator,the pseudo-random sequence of the PRBC-LFM signal,and the frequency difference between the PRBC-LFM signal and the periodic driving force signal of the Duffing oscillator is derived,providing the theoretical basis for blind parameter *** based on amplitude method,short-time Fourier transform method,and power spectrum entropy method are used to binarize the output of the Duffing oscillator array,and their performance is *** pseudo-random sequence is estimated using Duffing oscillator array synchronization,and the carrier frequency parameters are obtained by the relational expressions and characteristics of the difference *** results show that this blind estimation method overcomes limitations in prior knowledge and maintains good parameter estimation performance up to an SNR of-35 dB.

关键词： Duffing oscillator pseudo-random binary code-linear frequency modulation(PRBC-LFM)signal blind parameter estimation low signal-to-noise ratio(SNR)

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Weak wide-band signal detection method based on small-scale periodic state of Duffing oscillator

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Chinese Physics B 2018年第3期27卷 205-215页

作者： Jian Hou Xiao-peng Yan Ping Li Xin-hong Hao Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical Engineering Beijing Institute of Technology Beijing 100081 China

The conventional Duffing oscillator weak signal detection method, which is based on a strong reference signal, has inherent deficiencies. To address these issues, the characteristics of the Duffing oscillator＇s phase trajectory in a small- scale periodic state are analyzed by introducing the theory of stopping oscillation system. Based on this approach, a novel Duffing oscillator weak wide-band signal detection method is proposed. In this novel method, the reference signal is discarded, and the to-be-detected signal is directly used as a driving force. By calculating the cosine function of a phase space angle, a single Duffing oscillator can be used for weak wide-band signal detection instead of an array of uncoupled Duffing oscillators. Simulation results indicate that, compared with the conventional Duffing oscillator detection method, this approach performs better in frequency detection intervals, and reduces the signal-to-noise ratio detection threshold, while improving the real-time performance of the system.

关键词： Duffing oscillator weak signal detection stopping oscillation system small-scale periodic state

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Cognitive interference decision method for air defense missile fuze based on reinforcement learning

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Defence technology（防务技术） 2024年第2期32卷 393-404页

作者： Dingkun Huang Xiaopeng Yan Jian Dai Xinwei Wang Yangtian Liu Science and Technology on Electromechanical Dynamic Control Laboratory School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing 100081China

To solve the problem of the low interference success rate of air defense missile radio fuzes due to the unified interference form of the traditional fuze interference system,an interference decision method based Q-learning algorithm is ***,dividing the distance between the missile and the target into multiple states to increase the quantity of state ***,a multidimensional motion space is utilized,and the search range of which changes with the distance of the projectile,to select parameters and minimize the amount of ineffective interference *** interference effect is determined by detecting whether the fuze signal ***,a weighted reward function is used to determine the reward value based on the range state,output power,and parameter quantity information of the interference *** effectiveness of the proposed method in selecting the range of motion space parameters and designing the discrimination degree of the reward function has been verified through offline experiments involving full-range missile *** optimal interference form for each distance state has been *** with the single-interference decision method,the proposed decision method can effectively improve the success rate of interference.

关键词： Cognitive radio Interference decision Radio fuze Reinforcement learning Interference strategy optimization

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Research on AI-driven complex network and management system of coal and gas outburst accident

Journal of Safety and Sustainability

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Journal of Safety and Sustainability 2025年第1期2卷 32-44页

作者： Cheng Lu Shuang Li Ningke Xu Yi Zhang Yanting Qin School of Economics and Management China University of Mining and Technology Xuzhou 221116 China Safety Science and Emergency Management Research Institute China University of Mining and Technology Xuzhou 221116 China Key Laboratory of Theory and Technology on Coal and Rock Dynamic Disaster Prevention and Control National Mine Safety Administration China University of Mining and Technology Xuzhou 221116 China

Coal and gas outburst accidents are the most dangerous and complex accidents in coal mines. There is an urgent need for a systematic, objective, intelligent, and full process coal and gas outburst accident control system. The study constructs artificial intelligence (AI) -driven complex network and control system for coal and gas outburst accident: a coal and gas outburst accident control method based on text mining, complex network, and knowledge graph is proposed to achieve systematic extraction of causal factors, accurate identification of control strategy, intelligent formulation of control measures for coal and gas outburst accidents. The research results indicate that: (1) 70 causal factors are extracted from 72 investigation reports on coal and gas outburst accidents, including 21 human factors, 16 mechanical equipment factors, 14 environmental factors, and 19 management factors. (2) The coal and gas outburst accident complex network has a more complex structure, stronger robustness, and more prominent multi factor coupling effect, requiring more intelligent control methods. (3) The attack strategy generated by the innovatively proposed comprehensive value (CV) topology indicator is the optimal control strategy for coal and gas outburst accidents, maintaining higher attack efficiency in multiple stages and better controlling accident complex network. It also performs well in controlling single accident. (4) The coal and gas outburst accident control technology which is based on knowledge graph can quickly match the control measures and relationships, perform intelligent search of entities, reduce the time and energy consumption of managers for knowledge analysis, and provide intelligent decision support for managers. This study validates the scientific and practical feasibility of AI in the control of coal and gas outburst accidents. Future research will focus on further expanding data sources, clarifying the mechanism of coal and gas outburst accidents, and

关键词： Coal and gas outburst accidents Complex network Knowledge graph AI

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Occurring Mechanism and Restraining Method Research of Numerical Noise Signal in Penetration Simulation

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 1037-1043页

作者： WANG Chen WANG Yabin National Key Laboratory on Electromechanical Dynamic Control Beijing Institute of Technology Beijing 100081 China

In hard target penetration simulation, the existing researches of the convergence of results are mainly concentrating in the corresponding relationship between penetration depth and mesh scales. However, the influence of the mesh difference on the penetration resistance and acceleration signals are seldom refer to. This paper presents the occurring mechanism and restraining method of numerical noise signal in penetration simulation. First, the concept of the noise signal izs proposed. By taking a 3D penetration simulation as example, the influence of the noise signal on the penetration resistance in different mesh scales and impact velocity is studied. To ensure the convergence of the computational results, the grid scale of the target is encrypted to 1：1：8. In addition, modem spectrum analysis method is introduced to further analyze the penetration resistance signal. The research results presented is useful to improve the computational accuracy of high speed projectile penetration simulation, and provide important reference for carrying out structural design and optimization of fuze system.

关键词： hard target penetration numerical simulation signal of numerical noise spectral analysis

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A Benchmark and Frequency Compression Method for Infrared Few-Shot Object Detection

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IEEE Transactions on Geoscience and Remote Sensing 2025年 63卷

作者： Zhang, Ruiheng Yang, Biwen Xu, Lixin Huang, Yan Xu, Xiaofeng Zhang, Qi Jiang, Zhizhuo Liu, Yu Beijing Institute of Technology State Key Laboratory of Electromechanical Dynamic Control Beijing100081 China University of Technology Sydney School of Electrical and Data Engineering UltimoNSW2007 Australia Anhui Polytechnic University School of Computer and Information Wuhan241000 China Technical University of Munich Data Science in Earth Observation Munich85521 Germany Tsinghua University Shenzhen International Graduate School Shenzhen518055 China Tsinghua University Department of Electronic Engineering Beijing100084 China

Infrared few-shot object detection (IFSOD) aims to detect infrared objects with limited labeled examples. Current infrared datasets, however, suffer from limited diversity in object types and classes, hindering robust evaluation of model generalization on novel classes. To systematically assess dataset quality, we propose metrics for class diversity, instance variability, and object density. By integrating three widely used infrared datasets, we construct the first dataset specifically tailored for IFSOD, increasing instance density to 4.8 (a 1.1 improvement) and expanding the number of classes to 18 (a 5-class increase) compared to the source datasets. Furthermore, frequency analysis of spatial features reveals that sparse annotations introduce spectral bias in the frequency domain. Directly transforming spatial features to the frequency domain, however, mixes background noise with object features, causing spectral leakage and impairing the learning of discriminative features for novel classes. To address these issues, we propose the frequency compression few-shot detection (FC-fsd) method, which incorporates a frequency compression (FC) module. The FC module leverages Discrete Cosine Transform (DCT) within localized windows to reduce spectral leakage and enhance feature clarity. With minimal additional computational overhead, FC-fsd significantly outperforms state-of-the-art methods, achieving nAP50 scores of 28.57 (+13.37) and 35.63 (+2.59) in 1-shot and 2-shot settings, respectively. Our dataset is published at https://***/RuihengZhang/IFSOD-dataset. © 2025 IEEE.

关键词： Zero-shot learning

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