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3rd International Conference on Defence technology, ICDT 2022

作者： Zhang, Huayi Tang, Yilin National Key Laboratory of Transient Physics Nanjing University of Science and Technology Jiangsu Nanjing210094 China Chongqing High-tech Zone Pegasus Innovation Institute Chongqing400050 China

For the electromagnetic launch system, how to realize the wide pulse, fast rise, and small fluctuation of pulse forming network output current is a core problem. A trigger time sequence control method based on fuzzy theory for the pulse forming network is proposed in this paper. First, circuit models of pulse forming unit, pulse forming network, and electromagnetic rail launcher is established. Second, a fuzzy trigger time sequence controller model for pulse forming network is designed by using Simulink. Third, fixed time sequence discharge tests consisting of 20 pulsed forming units on the linear simulation load are carried out to verify the accuracy of the simulation model. Finally, discharge tests on the linear simulation load and launch tests on the electromagnetic railgun are carried out to verify the precision of the fuzzy controller output respectively. The results show that the designed fuzzy trigger time sequence controller can obtain the ideal trigger time sequence, which demonstrates the pragmatic and reliability of fuzzy control algorithm. © Published under licence by IOP Publishing Ltd.

关键词： Simulink

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Investigation on H2/O2 Rocket Rotating Detonation Engine with Annular and Hollow Combustors

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SSRN 2024年

作者： Xu, Hongfei Wang, Fang Weng, Chunsheng National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing210094 China

In this paper, a three-dimensional numerical investigation is conducted to reveal the propagation characteristics and operation performance of the H2/O2 rocket rotating detonation engine (RDE) with annular and hollow combustors. A detailed chemical mechanism is adopted and a complex slit-hole non-premixed injection configuration is simulated. The effects of engine configurations and sizes on flow field structure, internal flow properties, mixing effect, and propulsive performance are analyzed and compared. The results indicate that the engine configurations significantly affect the flow field and properties. The rotating detonation waves (RDWs) in the hollow RDE have a larger detonation height, faster propagation velocity, and fewer numbers. The average peak pressure of the detonation wave in the annular RDE is 0.92 MPa, while in the hollow RDE, it is only 0.42 MPa. The annular RDE has a thick deflagration surface with significant heat release and slow speed, contributing to the generation of new RDW. The lack of an inner wall decreases the mixing efficiency of reactants in the hollow RDE. Furthermore, larger RDE sizes typically lead to more RDWs. The K (=l/h) value in the hollow RDE is lower than that of the annular one, while the ratio h/λ is higher for the same engine size. As the RDE size increases, the engine thrust increases while the specific impulse decreases. In hollow RDE, the axial kinetic energy ratio can reach 66.2%, significantly lower than that of the annular RDE (95.7%). This study presents an in-depth analysis of H2/O2 RDE operating in both annular and hollow configurations, providing valuable insights for the design of high-reactivity rocket RDE systems. © 2024, The Authors. All rights reserved.

关键词： Kinetic energy

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Scalable parallel ultrafast optical random bit generation based on a single chaotic microcomb

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Light(science & Applications) 2024年第4期13卷 637-644页

作者： Pu Li Qizhi Li Wenye Tang Weiqiang Wang Wenfu Zhang Brent ELittle Sai Tek Chu KAlan Shore Yuwen Qin Yuncai Wang Institute of Advanced Photonics Technology School of Information EngineeringGuangdong University of TechnologyGuangzhou 51006China. Key Laboratory of Photonic Technology for Integrated Sensing and Communication Ministry of Education of ChinaGuangdong University of TechnologyGuangzhou 51006China. Guangdong Provincial Key Laboratory of Information Photonics Technology Guangdong University of TechnologyGuangzhou 51006China. Key Laboratory of Advanced Transducers andIntelligent Control System Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China. State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi’an 710119China. Department of Physics and Materials Science City University of Hong KongHong KongChina. School of Electronic Engineering Bangor UniversityBangorWales LL571UTUK

Random bit generators are critical for information security,cryptography,stochastic modeling,and *** and scalability are key challenges faced by current physical random bit ***,we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator.A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams.A proof-of-concept experiment demonstrates that using our method,random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb *** bit rate can be easily enhanced by further increasing the number of comb lines *** approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation,and offers superhigh speed and large scalability.

关键词： resonator random chaotic

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STUDY ON THE DISPERSAL DYNAMICS OF TERMINAL SENSITIVE BULLET WITHOUT PARACHUTES AND WINGS 1

STUDY ON THE DISPERSAL DYNAMICS OF TERMINAL SENSITIVE BULLET...

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1st International Conference on Mechanical System Dynamics, ICMSD 2022

作者： Yang, Yongliang Qu, Yue Jiang, Lin Guo, Rui School of Mechanical Engineering Nanjing University of Science and Technology Nanjing China National Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing China

ISBN: (数字)9781839537837

ISBN: (纸本)9781839537837

A high initial velocity, high rotation velocity, orientational and instantaneous dispersal is the prerequisite for realizing the steady-state scanning motion of the Terminal Sensitive Bullet without parachutes and wings (called TSB in present work). In order to meet this special dispersal requirement of the TSBs (who are carried by airborne dispensers), we firstly designed the inertial kinetic energy dispersal scheme and connection-unfold mechanism between the TSB and the carrier, and theoretically proved the feasibility of the scheme from the perspective of kinematics. Further through the analysis of multi-body dynamics, the relationship between the offset angle of the TSB after unfolded and the initial rotational velocity is obtained. Then, on this basis, a centrifugal unlocking separation mechanism was designed, and a dynamic model of the centrifugal unlocking mechanism was established considering the non-linear factors of friction. By numerically solving the dynamic equations, the effects of stiffness/mass ratio, contact pressure of a sleeve, angular acceleration of the cluster munition system and control parameters of the friction model on the performance of separation mechanism are analysed. And compared with the high-fidelity simulation results obtained by multi-body dynamics solver ADAMS, the reliability of the centrifugal unlocking separation mechanism was verified. The research results can provide some technical supports for the dispersal and separation designs of terminal sensitive cluster munitions. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Kinetic energy

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Detecting and Tracking Moving Objects in Defocus Blur Scenes

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SSRN 2024年

作者： Hu, Fen Yang, Peng Dou, Jie Dou, Lei National Key Laboratory of Transient Physics Nanjing University of Science and Technology Jiangsu Nanjing210094 China

Object tracking stands as a cornerstone challenge within the domain of computer vision, with blurriness analysis representing a burgeoning field of interest. Among the various forms of blur encountered in natural scenes, defocus blur remains significantly underexplored, despite its prevalence and distinct characteristics. To bridge this gap, this article introduces the DBVOT dataset, specifically crafted to facilitate research in visual object tracking under defocus blur conditions. We conduct a comprehensive performance analysis of 18 state-of-the-art object tracking methods on this unique dataset. Additionally, we propose a selective deblurring framework based on DID-ANet, innovatively designed to tackle the complexities of defocus blur. This framework integrates a novel defocus blurriness metric for the smart deblurring of video frames, thereby enhancing the efficacy of tracking methods in defocus blur scenarios. Our extensive experimental evaluations underscore the significant advancements in tracking accuracy achieved by incorporating our proposed framework with leading tracking technologies. © 2024, The Authors. All rights reserved.

关键词： Object detection

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Manipulating Nonsequential Double Ionization of Argon Atoms via Orthogonal Two-Color Field

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Chinese physics Letters 2022年第9期39卷 10-16页

作者： Yingbin Li Lingling Qin Aihua Liu Ke Zhang Qingbin Tang Chunyang Zhai Jingkun Xu Shi Chen Benhai Yu Jing Chen College of Physics and Electronic Engineering Xinyang Normal UniversityXinyang 464000China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China School of Physics and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Center for Applied Physics and Technology HEDPSand School of PhysicsPeking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100088China Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Advanced Material Diagnostic Technologyand College of Engineering PhysicsShenzhen Technology UniversityShenzhen 518118China State Key Laboratory of Transient Optics and Photonics Chinese Academy of SciencesXi’an 710119China

Using a three-dimensional classical ensemble model,we investigate the dependence of relative frequency and relative initial phase for nonsequential double ionization(NSDI)of atoms driven by orthogonal two-color(OTC)*** findings reveal that the NSDI probability is clearly dependent on the relative initial phase of OTC fields at different relative *** inversion analysis results indicate that adjusting the relative frequency of OTC fields helps control returning probability and flight time of the first ***,manipulating the relative frequency at the same relative initial phases can vary the revisit time of the recolliding electron,leading that the emission direction of Ar^(2+)ions is explicitly dependent on the relative frequency.

关键词： initial ensemble finding

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Signal Characteristics and Energy Transmittance During Detonation Tube Excitation in a Gas–Water–Soil Environment

SSRN

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SSRN 2024年

作者： Lv, Haicheng Li, Ning Huang, Xiaolong Li, Cheng Weng, Chunsheng National Key Laboratory of Transient Physics Nanjing University of Science and Technology Jiangsu Nanjing210094 China

To investigate signal characteristics and energy transmittance during the excitation process of detonation tubes in a gas–water–soil environment, an experimental system that utilizes shock waves and gases produced by detonation tubes to generate vibration waves in soil through coupling with a small pond is constructed. The transmission process of detonation tube signals in multiphase flow fields is studied through experiments. The characteristics of signals in water and soil and the energy transmittance during the process are analyzed using the fast Fourier transform and wavelet transform methods. The results indicate that the signal in water comprises low-frequency signals generated by bubble expansion and rupture and high-frequency signals generated by shock wave oscillation. The frequency of the soil vibration signal in the near field is concentrated between 10 and 240 Hz. As the diameter of the detonation tube increases, the peak frequency of the signal decreases relatively, and the energy transmittance develops from being concentrated near the highest frequency position to being uniformly distributed throughout the entire frequency range. The highest energy transmittance is located in the frequency range of 60–80 Hz, which is not related to the diameter of the detonation tube. © 2024, The Authors. All rights reserved.

关键词： Flow fields

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Analysis of sliding electric contact characteristics in augmented railgun based on the combination of contact resistance and sliding friction coefficient

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Defence technology（防务技术） 2020年第4期16卷 747-752页

作者： Chun-yan Zhu Bao-ming Li National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyChina

The contact resistance between the armature and rails is an important indicator of the contact characteristics in electromagnetic *** the contact resistance depends not only on the contact state but also on the contact stress and temperature,there are some limitations in analyzing the contact characteristics using only the contact *** this paper,the contact characteristics of the augmented railgun are analyzed by the combination of contact resistance and sliding friction ***,the theoretical calculation model of the contact resistance and friction coefficient of the augmented electromagnetic railgun is *** the contact resistance and friction coefficient are calculated by the measured values of the muzzle voltage,rail current and armature ***,the contact characteristics are analyzed according to the features of the waveforms of the contact resistance and the friction coefficient,and the analysis conclusions are verified by experimental rail *** results showed that:the aluminum melt film gradually formed on the contact surface reduces the contact resistance and the friction coefficient;the wear and erosion of the armature cause deterioration of the contact state;after the transition,the reliability of the sliding contact between the armature and rails decreases,resulting in an increase in contact resistance.

关键词： Augmented railgun Contact resistance Friction coefficient Contact characteristics

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VIBRATION AND HYPERVELOCITY GOUGING OF SLIDING PAIRS IN ELECTROMAGNETIC RAILGUNS 1

VIBRATION AND HYPERVELOCITY GOUGING OF SLIDING PAIRS IN ELEC...

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1st International Conference on Mechanical System Dynamics, ICMSD 2022

作者： Wu, Jinguo Li, Sihan Yang, Bin Chen, Ruwen Lin, Qinhua School of Automotive & Rail Transit Nanjing Institute of Technology Nanjing China Key Laboratory of Transient Physics Nanjing University of Science and Technology Nanjing China

ISBN: (数字)9781839537837

ISBN: (纸本)9781839537837

Hypervelocity gouging has been observed over several decades in engineering applications involving rocket sled, electromagnetic railgun and light-gas gun. In this paper, numerical simulations using explicit finite element method were carried out to investigate the gouging mechanism in railguns. Two models were constructed and discussed: one is the non-uniform contact model under magnetic pressure, and the other is the transverse swing impact model. The former shows that, the non-uniform contact under the action of magnetic pressure will not cause gouging, but will form grooves, although the armature slides parallel to the rail at a high speed. The latter shows that, the lateral swing of the armature at a high speed can lead to oblique impacts on the interface, forming pressure cores, and eventually gouging. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Rail guns

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Graphene-empowered dynamic metasurfaces and metadevices

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Opto-Electronic Advances 2022年第4期5卷 1-47页

作者： Chao Zeng Hua Lu Dong Mao Yueqing Du He Hua Wei Zhao Jianlin Zhao MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions and Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an 710129China State Key Laboratory of Transient Optics and Photonics Xi’an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi’an 710119China

Metasurfaces,with extremely exotic capabilities to manipulate electromagnetic(EM)waves,have derived a plethora of advanced metadevices with intriguing *** endeavors have been mainly devoted to the static metasurfaces and metadevices,where the functionalities cannot be actively tuned in situ *** to the in-trinsic advantage of active tunability by external stimulus,graphene has been successively demonstrated as a favorable candidate to empower metasurfaces with remarkably dynamic tunability,and their recent advances are propelling the EM wave manipulations to a new height:from static to ***,we review the recent progress on dynamic metasur-faces and metadevices enabled by graphene with the focus on electrically-controlled dynamic manipulation of the EM waves covering the mid-infrared,terahertz,and microwave *** fundamentals of graphene,including basic ma-terial properties and plasmons,are first ***,graphene-empowered dynamic metasurfaces and met-adevices are divided into two categories,i.e.,metasurfaces with building blocks of structured graphene and hybrid metasurfaces integrated with graphene,and their recent advances in dynamic spectrum manipulation,wavefront shap-ing,polarization control,and frequency conversion in near/far fields and global/local ways are *** the end,we summarize the progress,outline the remaining challenges,and prospect the potential future developments.

关键词： metasurface dynamic metasurface graphene graphene plasmons light field manipulation electromagnetic wave manipulation

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