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Three-Dimensional Object Detection Network Based on Coordinate Attention and Overlapping Region Penalty Mechanisms 1

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7th Asian Conference on Pattern Recognition, ACPR 2023

作者： Li, Wenxin Zhu, Shiyu Liu, Hongzhi Zhang, Pinzheng Zhang, Xiaoqin Zhejiang Gongshang University Hangzhou310018 China National Key Laboratory of Transient of Physics Nanjing University of Science and Technology Nanjing210094 China School of Computer Science and Engineering Southeast University Nanjing210096 China

ISBN: (数字)9783031476655

ISBN: (纸本)9783031476648

Three-dimensional target detection is a key technology in the fields of autonomous driving and robot control for applications such as self-driving cars and unmanned aircraft systems. In order to achieve high detection accuracy, this paper proposes a 3D target detection network with a coordinate attention training mechanism that generates voting feature points for better detection ability and an overlap region penalty mechanism that reduces false detection. In comparative experiments on public large-scale 3D datasets including the Scannet dataset and SUN-RGB-D dataset, the proposed method obtained an average detection accuracy mAP of 60.1% and 58.0% with an intersection ratio of 0.25, which demonstrates its superior effectiveness over the current main algorithms such as F-PointNet, VoxelNet and MV3D. The improved method is expected to achieve higher accuracy for 3D object detection relying only on point cloud information. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

关键词： Object detection

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Standing window of oblique detonation with pathological behaviour

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Chinese Journal of Aeronautics 2021年第5期34卷 496-503页

作者： Zhuo XU Gang DONG Zhenhua PAN Mingyue GUI Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China School of Energy Resources and Power Engineering Jiangsu UniversityZhenjiang 212013China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Standing of an Oblique Detonation Wave(ODW)on a wedge within combustor is the prerequisite of thrust generation for ODW engine which is regarded as a novel and conceptual propulsion device with hypersonic flight Mach *** a standing window of ODW is defined as the wedge angle ranged from the ODW detached angle from wedge(upper limit)to the angle that a Chapman-Jouguet(CJ)detonation occurs(lower limit).For pathological detonation cases,however,the CJ detonation cannot be achieved,and thus the lower limit of the standing window of ODW should be *** present study,two types of reactions in hypersonic incoming flow that include the behavior of pathological detonation,that is,the single-step irreversible reaction with mole variation and the two-step irreversible reactions with exothermic process followed by endothermic process,have been used for studying standing behavior of *** steady detonation polar analysis of ODW is carried out for both reaction *** results reveal that the reaction with more mole decrement and the reactions with stronger endothermic process show the pathological detonation feature and therefore modify the lower limit of standing window of *** equivalent parameters are proposed to quantitatively measure the standing window range of ODW from points of view of thermodynamics,Mach number of incoming flow and heat effect of *** is found that the standing window of ODW is determined by the specific heat ratio,the overdrive degree of detonation and the endothermic level of the hypersonic incoming flow,regardless of whether the detonation is pathological or not.

关键词： Chemical reaction Equivalent parameter Hypersonic flow Oblique detonation Pathological detonation Standing window

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Super-cavitation contour extraction method based on multi-scale space

Super-cavitation contour extraction method based on multi-sc...

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2022 International Conference on Optical and Photonic Engineering, icOPEN 2022

作者： Kong, Xiaofang Yang, Wenguang Chen, Xueqi Wan, Minjie Li, Baoming National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing210094 China Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense Nanjing University of Science and Technology Nanjing210094 China China Academy of Ordnance Science Beijing100089 China

ISBN: (纸本)9781510661905

Super-cavitation morphological parameter information of the cross-media projectile reflects high-speed projectiles motion characteristics. Accurate measurement of super-cavitation morphological parameters is the basis for high-speed projectile structural design and optimization, becoming a research hotspot of the underwater ballistic testing field. With the development of the high-speed photography technology, recording the evolution process of projectile cavitation morphologies by high-speed cameras and acquiring super-cavitation morphological information through image processing methods have become one of the main research directions. Aiming at reducing the large workload of manual interpretation from super-cavitation images, a multi-scale space-based automatic contour extraction algorithm for supercavitation images captured by the array cross-media high-speed imaging system is introduced in this paper. The Canny edge detection method is applied to obtain the binary edge image with coarse extraction super-cavitation edge after image pre-processing. The super-cavitation contour point set is searched in the binary edge image and small gaps between adjacent endpoints are filled at the same time. The contour extraction algorithm based on the multi-space curvature characteristics is presented to calculate the curvature value of each contour point in the high-scale space, and the curvature feature points are determined by the threshold judgment approach. The contour feature points extracted in the high-scale space are located in the low-scale space precisely, and the super-cavitation contour is extracted. Experimental results show that, the proposed method can reduce the workload from manual interpretation while improve the accuracy of contour positioning, which can provide basic data support for the cross-media high-speed projectile super-cavitation morphological parameter measurement. © 2022 SPIE.

关键词： High speed cameras

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Supercavitating Projectile Tail-Slaps Based on a Normal Distribution

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哈尔滨工程大学学报(英文版) 2025年第2期24卷 398-414页

作者： Kangjian Wang Youran Xia Qizhuang Kang Youli Wu Aviation Engineering College Air Force Engineering UniversityXi’an 710038China National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing 210094China

The present study focuses on simulating supercavitating projectile tail-slaps with an analytical method.A model of 3σ-normal distribution tail-slaps for a supercavitating projectile is ***,theσ-κequation is derived,which is included in this ***,the supercavitating projectile tail-slaps are simulated by combining the proposed model and the Logvinovich supercavity section expansion *** results show that the number of tail-slaps depends on where the initial several tail-slaps are under the same initial *** the distances between the initial several tail-slap positions are large,the number of tail-slaps will considerably decrease,and vice ***,a series of simulations is employed to analyze the influence of the initial angular velocity and the *** of variance is used to evaluate simulation *** evaluation results suggest that the projectile’s initial angular velocity and centroid have a major impact on the tail-slap *** larger the value of initial angular velocity,the higher the probability of an increase in tail-slap ***,the closer the centroid is to the projectile head,the less likely a tail-slap number *** study offers important insights into supercavitating projectile tail-slap research.

关键词： Tail-slaps Normal distribution Supercavity Stability Supercavitating projectile

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Study, development and related application of a miniature compact pulsed power supply with high repetition frequency

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Defence technology 2025年第5期 304-318页

作者： Zhangfei Wang Jian Liu Chunxia Yang Baoming Li National Key Laboratory of Transient Physics Nanjing University of Science and Technology

Capacitor-based pulsed power supply(PPS) is widely used in fields related to electromagnetic launch,plasma, and materials' synthesis, modification and processing. As industrial applications place higher requirements on compact and portable pulsed power supplies, the National Key laboratory of transient physics(NKLTP) recently developed a pulsed power supply consisting of a set of compact pulse-forming units(PFU), each with a capacitor energy storage of 220 k J. This integrated PPS comes with a complete system configuration, a miniature compact structure, a high rate of repetition, and high power, with energy storage density exceeding 1.2 MJ/m3. This paper describes the device-level design of the unit, the system layout, the control system, the thermal management system, and the experimental results of the pulsed power supply. The experimental results verified the good reliability of the PPS at high repetition rates with each unit module delivering an output current of more than 100 k A. Additionally, flexible current pulse shapes can be formed by setting the charging voltage and the trigger sequence of the *** pulse forming network(PFN) developed from these PFUs was successfully applied to electromagnetic launch.

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Rapid and Nanometric-Precision Distance Measurement with Hybrid Comb Lasers

Rapid and Nanometric-Precision Distance Measurement with Hyb...

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2024 Conference on Lasers and Electro-Optics/Pacific Rim, CLEO-PR 2024

作者： Zhi, Jiawen Wang, Zhichuang Wu, Hanzhong Little, Brent E. Chu, Sai T. Wang, Panpan Shao, Chenggang Wang, Weiqiang Zhang, Wenfu MOE Key Laboratory of Fundamental Physical Quantities Measurements Hubei Key Laboratory of Gravitation and Quantum Physics PGMF and School of Physics Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an710119 China University of Chinese Academy of Sciences Beijing100049 China Department of Physics and Materials Science City University of Hong Kong Hong Kong

We demonstrate a dual-hybrid-comb distance meter with a fully-stabilized microcomb, enabling ultra-rapid and nanometric-precision distance measurement. The precision can reach 3.572 μm at 4.136 μs and 432 nm at 827... 详细信息

关键词： Distance measurement

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When optical vortex array meets cycloid

When optical vortex array meets cycloid

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作者： Ma, Xin Hu, Huajie Tai, Yuping Li, Xinzhong School of Physics and Engineering Henan University of Science and Technology Luoyang471023 China State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an710119 China

Optical vortex arrays (OVAs) have drawn widespread attention owing to their multiple optical vortices and higher dimensions. However, existing OVAs have not yet been utilized to exploit the synergy effect as an entire system, particularly for manipulating multiple particles. Thus, the functionality of OVA should be explored to respond to application requirements. Hence, this study proposes a functional OVA, called cycloid OVA (COVA), based on a combination of cycloid and phase-shift techniques. By modifying the cycloid equation, multiple structural parameters are designed to modulate the structure of the COVAs. Subsequently, versatile and functional COVAs are experimentally generated and modulated. In particular, COVA executes local dynamic modulation, whereas the entire structure remains unchanged. Further, the optical gears are first designed using two COVAs, which exhibit potential for transferring multiple particles. Essentially, OVA is endowed the characteristics and capacity of the cycloid when they meet. This work provides an alternative scheme to generate OVAs, which will open up advanced applications for the complex manipulation, arrangement and transfer of multiple particles. © 2023 Optica Publishing Group.

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Experimental research on the instability propagation characteristics of liquid kerosene rotating detonation wave

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Defence technology（防务技术） 2020年第6期16卷 1106-1115页

作者： Quan Zheng Hao-long Meng Chun-sheng Weng Yu-wen Wu Wen-kang Feng Ming-liang Wu National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with *** fuel and oxidizer are room-temperature liquid kerosene and preheated oxygenenriched air,*** experimental tests keep the equivalence ratio of 0.81 and the oxygen mass fraction of 35%unchanged,and the total mass flow rate is maintained at about 1000 g/s,changing the total temperature of the oxygen-enriched air from 620 K to 860 *** different types of instability were observed in the experiments:temporal and spatial instability,mode transition and *** interaction between RDW and supply plenum may be the main reason for the fluctuations of detonation wave velocity and pressure peaks with ***,the inconsistent mixing of fuel and oxidizer at different circumferential positions is related to RDW oscillate *** phenomenon of single-double-single wave transition is *** the transition,the initial RDW weakens until disappears,and the compression wave strengthens until it becomes a new RDWand propagates *** increased deflagration between the detonation products and the fresh gas layer caused by excessively high temperature is one of the reasons for the RDC quenching and re-initiation.

关键词： Rotating detonation wave Liquid kerosene Oxygen-enriched air Instability propagation characteristics Compression wave

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Research on TMR-FCN-based underwater projectile localization method 3

Research on TMR-FCN-based underwater projectile localization...

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3rd International Conference on Defence technology, ICDT 2022

作者： Hu, Xi Gu, Jin-Liang Liu, Jun-Min Wu, Ming-Yu National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China Nanjing Research and Development Center Northern Heavy Industries Group Co. Ltd. Nanjing210014 China

A machine learning localization method for underwater projectile using Tunnel magnetoresistance (TMR) sensors is proposed in this paper. Firstly, the relation between the magnetic field intensity and the position of the projectile was built based on the magnetic dipole model. Then, the measurement model of TMR sensors was constructed to offer the voltage signal linearly correlated to the magnetic field intensity, and the network model based on the fully connected neural network (FCN) was established to approximate and regress the highly nonlinear mapping function between the magnetic field intensity (B) and the square of the distance from the projectile to the sensor (d2). Inspired by the Received Signal Strength (RSS) localization method, the least-square method was adopted to solve the actual coordinate of the projectile. Finally, to verify the localization accuracy of the proposed TMR-FCN-based method, the ballistic simulation was performed for providing the actual position of the projectile and the output of the TMR sensors, then the positioning operation was carried out by coupling the FCN model and the least-square method. The results demonstrate that the B-d2 model can fast compute the d2 within 8ms for the single given B and the overall mean accuracy is up to 99.15%. The localization distance error via the least-square method is lower than 0.5mm. These results indicate that the TMR-FCN-based localization method can achieve accurate localization for the underwater projectile and effectively overcome the tough problem of solving the high-dimensional nonlinear equations for B and d2. © Published under licence by IOP Publishing Ltd.

关键词： Projectiles

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Physical characteristics of detonation noise from multi-tube pulse detonation engine

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Chinese Journal of Acoustics 2021年第3期40卷 378-388页

作者： HUANG Xiaolong LI Ning WENG Chunsheng National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094

An experimental system of multi-tube pulse detonation engine with single tube to four tubes is set up to study the formation of detonation noise and acoustic characteristics of multi-tube pulse detonation *** physical parameters of multi-tube detonation noise,including waveform,attenuation of sound pressure,radiation characteristics,duration and acoustic spectrum characteristics are *** results show that the peak sound pressure of detonation noise attenuates faster in the area near the tube exit,and the attenuation speed in the area far away from the tube exit is inversely proportional to the radius *** the increase of the number of detonation tubes,the peak sound pressure level of detonation noise at each directivity angle increases *** the far-fiekl region,the directivity of the detonation noise is *** the number of detonation tubes increases,the A and B durations of detonation noise *** acoustic spectrum of detonation noise is a broadband signal,and the acoustic energy mainly concentrates in the range of middle and low *** dominant spectrum peak and sound pressure level of the acoustic spectrum vary with the increase of the number of detonation *** results are of great significance for studying the propagation of acoustic wave in detonation process and will be useful for application of pulse detonation engine in aircraft power systems.

关键词： characteristics pulse tube

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