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The absorption coefficient measurement of underwater materials in a water tube by using the wide-band pulse method

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Chinese Journal of Acoustics 2017年第2期36卷 180-194页

作者： DAI Yang YANG Jianhua HOU Hong CHEN Jianping SUN Liang SHI Jing Northwestern Polytechnical University cssc Systems Engineering Research institute

The existing absorption coefficient measurement in a water tube is limited in low frequency due to the limitation of the pulse tube length.A wide-band pulse tube method based on the post-processing inverse filter is *** obtaining the response of the entire system,the transducer is excited with wide-band,short-duration ***,the received signals are processed with inverse filters and the ＂blurred＂ reflective signals of standard reflector and test sample are recovered respectively,finally,the reflection coefficient and absorption coefficient are *** work is implemented to verify the advantage of postprocessing inverse filter over pre-processing inverse filter in terms of low frequency *** verify the proposed method,two different wide-band pulses in the separate frequency ranges are adopted to measure the same rubber *** experimental results indicate that the wide-band pulse method and CW（Continuous Wave） pulse method have good agreement in both low frequency range and high frequency ***-band pulse method is of high efficiency,and the low frequency reaches 350 Hz,which is able to extend the low frequency range.

关键词： inverse reflective underwater transducer verify reflector rubber processed excited truncation

Compared discharge characteristics and film modifications of atmospheric pressure plasma jets with two different electrode geometries

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Chinese Physics B 2023年第11期32卷 537-544页

作者：陈雄王兴权张彬祥袁明杨思泽 institute of Low Temperature Plasma Technology School of Physics and Electronic InformationGannan Normal UniversityGanzhou 341000China The 722 Research institute of cssc Wuhan 430205China institute of Physics Chinese Academy of SciencesBeijing 100190China

Atmospheric pressure plasma jet shows great potential for polymer film processing. The electrode geometry is the key factor to determine discharge characteristics and film modification of jets. In this paper, we compared the discharge characteristics and the film modifications of atmospheric pressure plasma jets with needle-ring electrode(NRE) and doublering electrode(DRE). The results show that jet with NRE has stronger electric field intensity and higher discharge power,making it present more reactive oxygen particles and higher electron temperature, but its discharge stability is *** contrast, the jet with DRE has uniform electric field distribution of lower field intensity, which allows it to maintain stable discharge over a wide range of applied voltages. Besides, the modification results show that the treatment efficiency of PET film by NRE is higher than that by DRE. These results provide a suitable atmospheric pressure plasma jets device selection scheme for polymer film processing process.

关键词： atmospheric pressure plasma jet electrode structure jet characteristics modification

Dynamic Spectrum Anti-Jamming with Distributed Learning and Transfer Learning

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China Communications 2023年第12期20卷 52-65页

作者： Xinyu Zhu Yang Huang Delong Liu Qihui Wu Xiaohu Ge Yuan Liu Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China the 723 institute of cssc Yangzhou 225001China School of Electronic Information and Communications Huazhong University of Science and TechnologyWuhan 430074China School of Electronic and Information Engineering South China University of TechnologyGuangzhou 510641China

Physical-layer security issues in wireless systems have attracted great *** this paper,we investigate the spectrum anti-jamming(AJ)problem for data transmissions between *** fast-changing physical-layer jamming attacks in the time/frequency domain,frequency resources have to be configured for devices in advance with unknown jamming patterns(*** time-frequency distribution of the jamming signals)to avoid jamming signals emitted by malicious *** process can be formulated as a Markov decision process and solved by reinforcement learning(RL).Unfortunately,stateof-the-art RL methods may put pressure on the system which has limited computing *** a result,we propose a novel RL,by integrating the asynchronous advantage actor-critic(A3C)approach with the kernel method to learn a flexible frequency pre-configuration ***,in the presence of time-varying jamming patterns,the traditional AJ strategy can not adapt to the dynamic interference *** handle this issue,we design a kernelbased feature transfer learning method to adjust the structure of the policy function *** results reveal that our proposed approach can significantly outperform various baselines,in terms of the average normalized throughput and the convergence speed of policy learning.

关键词： A3C anti-jamming reinforcement learning spectrum transfer learning wireless system

High-resolution deconvolved beamforming for three-dimensional imaging sonars

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Chinese Journal of Acoustics 2021年第1期40卷 95-110页

作者： WANG Peng CHI Cheng JI Yongqiang HUANG Yong LIU Jiyuan HUANG Haining institute of Acoustics Chinese Academy of SciencesBeijing 100190 System Engineering Research institute of cssc Beijing 100094

Three-dimensional(3D) imaging sonars based on the conventional beamforming(CBF) suffers from relatively wide main-lobes and high sidelobe *** improve the spatial resolution of 3D imaging sonars,a deconvolved beamforming method is proposed with the iterative Richardson-Lucy algorithm in this *** first,each distance slice can be processed to obtain images by the *** the near field,the Fresnel approximation is ***,the deconvolution technique is applied to the CBF outputs to obtain high-resolution images and suppress the sidelobe *** simulations demonstrate that the proposed algorithm is able to improve the spatial resolution significantly and suppress the sidelobes for 3D imaging ***,the algorithm shows similar robustness with the CBF in the case of wideband and sparse *** priority of the proposed algorithm is also validated by the tank experiment *** presented results indicate that the spatial resolution is increased by one time and the average sidelobe level is reduced by 20 dB.

关键词： resolution algorithm beamforming

ANALYTICAL SOLUTION OF RADIATION SOUND PRESSURE OF DOUBLE CYLINDRICAL SHELLS IN FLUID MEDIUM

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Applied Mathematics and Mechanics(English Edition) 2002年第4期23卷 463-470页

作者：陈美霞骆东平陈小宁沈瑞喜 Faculty of Traffic Science and Engineering Huazhong University of Science and Technology Wuhan 430074 P R China System Engineering Research institute CSSC Beijing 100036 P R China

The Donnell theory of shell was applied to describe shell motion. The inner and outer shells were stiffened by transverse components. Using deformation harmonious conditions of the interface, the effects of stiffeners were treated as reverse forces and moments on the double cylindrical shell. In the acoustic field produced by vibration and sound radiation of the double shell, the structure dynamic equation, Helmholtz equation in the fluid field and the continuity conditions of the surface of fluid-structure compose the vibration equation coupled by the sound-fluid-structure. The extract of acoustic pressure comes down to the extract of coupling vibration equation. The near field acoustic pressure can be solved directly by complicated calculational methods.

关键词： double cylindrical shell coupling vibration equation acoustic pressure

Influence of warm eddies on sound propagation in the Gulf of Mexico

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Chinese Physics B 2019年第5期28卷 134-144页

作者： Yao Xiao Zhenglin Li Jun Li Jiaqi Liu State Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences University of Chinese Academy of Sciences China State Shipbuilding Corporation (cssc) Systems Engineering Research institute College of Underwater Acoustic Engineering Harbin Engineering University Woodruff School Mechanical Engineering Georgia Institute of Technology

An automatic detection method is employed to identify and track eddies in the Gulf of Mexico. The physical parameters of the eddies, such as lifespan, radius, and distribution position are first examined and used to determine the spatio–temporal evolution of a strong warm eddy separated from the Mexico current. Then, the influence of this strong warm eddy on sound propagation during its lifespan are comprehensively analyzed with the parabolic equation and explained by using the normal mode and ray theories. Additionally, the influence of mesoscale eddies on the redistribution of total depth-integrated energy among the normal modes in the deep water is also discussed. The variation of arrival angle is investigated to explain the spreading acoustic energy caused by eddies. Overall, the results show that warm eddies can change the propagation paths and cause the convergence zone to broaden and approach the sound source. Moreover,the warm eddy can disperse sound energy and cause the total depth-integrated energy to incline to a lower normal *** the whole of these three periods(eddy generating, eddy maturing, and eddy terminating), the fluctuation in the transmission loss is up to 30 dB(depending on the relative location of eddy center to the source).

关键词： mesoscale eddies sound propagation mode coupling acoustic energy disturbance

THE SOLUTION OF INTEGRAL EQUATIONS WITH STRONGLY SINGULAR KERNELS APPLIED TO THE TORSION OF CRACKED CIRCULAR CYLINDER

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Applied Mathematics and Mechanics(English Edition) 1993年第10期14卷 899-906页

作者：李玉兰马稚青汤任基 Lanzhou University Lanzhou The 9th Design and Research institute CSSC Shanghai Shanghai Jiaotong University Shanghai

In this paper, the functions of warping displacement interruption defined on the crack lines are taken for the fundamental unknown functions. The torsion problem of cracked circular cylinder is reduced to solving a system of integral equations with strongly singular kernels. Using the numerical method of these equations, the torsional rigidities and the stress intensity factors are calculated to solve the torsion problem of circular cylinder with star-type and other different types of cracks. The numerical results are satisfactory.

关键词： torsion of cracked cylinder strongly singular integral equation,star-type crack torsional rigidity stress intensity factor

Dynamic Timeslot MAC Protocol for AUV Underwater Communication

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Dynamic Timeslot MAC Protocol for AUV Underwater Communicati...

An Indoor Localization Approach Based on Fingerprint and Time-Difference of Arrival Fusion

第三十九届中国控制会议

作者： Jun Zhou Xiaokang Wang Baogui Zhang No.710 institute cssc

It is difficult to achieve satisfactory results in underwater acoustic communication because of the characteristics of large time delay and multi-path. MAC protocol is the key to the quality of underwater communication. Some protocols, such as S-Aloha, solve the problems of collision and hidden nodes, and use RTS/CTS to compete for access. The change of network structure brings new problems because of the movement of AUV. Based on the fact that the time delay is the main factor affecting the slot length, AUV underwater position prediction model is established. The timeslo is changed when the interval distance of AUV *** dynamic timeslot MAC protocol is designed. Compared with the fixed time slot MAC protocol, the simulation results show that the dynamic timeslot MAC protocol improves the network throughput.

关键词： MAC protocol underwater communication position prediction Dynamic Timeslot

来源： cnki会议评论

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Journal of Beijing institute of Technology 2022年第6期31卷 570-583页

作者： Haoyu Yang Yuanshuo Wang Dongchen Li Tiancheng Li the Key Laboratory of Information Fusion Technology(Ministry of Education) School of AutomationNorthwest-ern Polytechnical UniversityXi’an 710072China cssc Systems Engineering Research institute Beijing 100094China

In this paper,an effective target locating approach based on the fingerprint fusion posi-tioning(FFP)method is proposed which integrates the time-difference of arrival(TDOA)and the received signal strength according to the statistical variance of target position in the stationary 3D *** FFP method fuses the pedestrian dead reckoning(PDR)estimation to solve the moving target localization *** also introduce auxiliary parameters to estimate the target motion ***,we can locate the static pedestrians and track the the moving *** the case study,eight access stationary points are placed on a bookshelf and hypermarket;one target node is moving inside hypermarkets in 2D and 3D scenarios or stationary on the *** compare the performance of our proposed method with existing localization algorithms such as k-nearest neighbor,weighted k-nearest neighbor,pure TDOA and fingerprinting combining Bayesian frameworks including the extended Kalman filter,unscented Kalman filter and particle fil-ter(PF).The proposed approach outperforms obviously the counterpart methodologies in terms of the root mean square error and the cumulative distribution function of localization errors,espe-cially in the 3D *** results corroborate the effectiveness of our proposed approach.

关键词： 3D indoor localization fingerprint fusion positioning time-difference of arrival pedestrian dead reckoning received signal strength