检索结果-内蒙古大学图书馆

9th Symposium on Novel Photoelectronic Detection technology and Applications

作者： Lu, Zhang Yunying, Wang Yuanyuan, Guo Fangyuan, Jin Hui, Lin Science and Technology on Underwater Test and Control Laboratory Dalian116013 China

ISBN: (纸本)9781510664432

For the study of the environmental characteristic parameters of typical ocean weak turbulence field, such as temperature and salinity concentration, the intensity distribution of the Gaussian beam propagation in ocean weak turbulence has been obtained by using the temperature-salinity coupling refractive power spectrum model and the theory of random phase screen, and the intensity characteristic has been analyzed by the two-dimensional gray histogram. The simulation results show that the turbulence intensity is an influence on the image characteristic, which contain the brightness and the non-uniformity degree of the image, and the effects of the variable average temperature on the image characteristics are stronger with the increase of the turbulence intensity, and then the effects of the variable average salinity concentration on the image characteristics are small under the typical weak turbulence conditions. © 2023 SPIE.

关键词： Statistical optics

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Pressure Sensitivity Kernel and Travel-Time Gradient for Geoacoustic Parameters Perturbations of Sediment in Shallow Water

Pressure Sensitivity Kernel and Travel-Time Gradient for Geo...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Zheng, J. Zhang, X. Ma, Z. Science and Technology on Underwater Test and Control Laboratory Dalian116013 China

In shallow sea, the effect of geoacoustic characteristics of seabed sediments on acoustic propagation cannot be neglected, which is closely related to acoustic detection and seabed inversion. Aiming at the problem of low-frequency acoustic propagation, the sound pressure sensitivity kernel (PSK) and travel-time gradient (TTG) of the shallow low-frequency acoustic field for the geoacoustic parameters of sediment were presented by using normal mode model and perturbation approximation. Combined with the benchmark shallow sea model, the numerical simulation was carried out. The simulation results show that the PSK for the sound velocity of sediment are showing some interference pattern in velocity-range plane and velocity-frequency plane, and its strength is attenuated with the increase of range. TTGs have different sensitivity to the sound velocity of sediment at different range, which is more sensitive at mid-range. The PSK and TTG show some frequency selectivity. © Published under licence by IOP Publishing Ltd.

关键词： Travel time

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Scintillation Characteristics of Gaussian Vortex Beam Propagation in Turbulent Flume

Scintillation Characteristics of Gaussian Vortex Beam Propag...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Zhang, L. Wang, Y. Lin, H. Guo, Y. Jin, F. Science and Technology on Underwater Test and Control Laboratory Dalian116013 China

Aiming at the low sensitivity of weak turbulent wake detection of underwater vehicles, studied the laser propagation characteristics in underwater weak turbulence, and then proposed a method based on the statistical characteristics of the scintillation peak of Gaussian vortex beam for detecting the weak turbulence fluctuation. According to the refractive index power spectrum of turbulent flume, the intensity distribution images of Gaussian vortex beam propagating through turbulent flume are simulated by using the random phase screen method, and the scintillation characteristics of Gaussian vortex beam under different conditions are studied. For the simulation results, under the weak turbulence conditions with low refractive index structure coefficient, the average scintillation indexes near the peak value of spot scintillation indexes are obviously higher than those of the whole image. Under the condition that the temperature difference between hot plate and cold plate, between hot plate and water are about 6.4°C and 5.8°C, respectively, the scintillation indexes of the laser propagation intensity image under different temperature gradient (turbulence intensity) are calculated in the experiment. The results show that, the mean values of the scintillation indexes near the spot scintillation peak fluctuate around 1.02 and 1.07, and the mean values in whole image fluctuate around 0.58 and 0.68, respectively, when the temperature gradient is small, which verify the effectiveness of the statistical characteristics of the scintillation peak in detecting weak turbulence. © Published under licence by IOP Publishing Ltd.

关键词： Scintillation

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Estimation of target depth using deep-sea echo multipath structure matching

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Chinese Journal of Acoustics 2023年第3期42卷 251-269页

作者： ZHANG Fengzhen LI Guijuan HU Wenshuai HU Chen Key Laboratory of Science and Technology on Underwater Test and Control Dalian 116013 Dalian Scientific Test and Control Technology Institute Dalian 116013

This paper presents a method to estimate the depth of deep-sea target by matching the time delay and amplitude structure of echo multipath highlight *** echo structure is the convolution of two-way channel transfer function as well as the acoustic scattering function of the target,which shows the characteristics of deep-sea highlight clusters when the target is close to the sea surface or near the sea *** time delay and amplitude structure of highlight clusters are related to the target depth,which can be used to estimate the target depth.A method of matching estimation of target depth on range-depth grid using nonlinear programming cost function is *** mismatch effects of inter-cluster time delay interval deviation and sea water sound velocity profile deviation on matching estimation are simulated and *** results of a winter experiment in the South China Sea illustrate that when the water depth is 1 km and distance is 5–8 km,the echo of target is 40 m underwater,there are three highlight clusters with a time interval of about 0.3 s,with the error range of target depth matching estimation being 0–65 m.

关键词： matching structure estimation

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Design and Verification of Low Frequency Alternating Magnetic Field Detection Device Based on Unstable Platform

Design and Verification of Low Frequency Alternating Magneti...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Zhao, Zhe Jiao, Dawen Hu, Ping Zhang, Jing Cui, Pei Lv, Junjun Science and Technology on Underwater Test and Control Laboratory 16 Binhai Street Dalian China

Low frequency alternating magnetic field is one of the important features for marine magnetic field detection. In order to realize the effective detection of low-frequency alternating magnetic field signal in the marine environment, a low-frequency alternating magnetic field detection device based on unstable platform was designed based on the low-power optical pump magnetometer and signal control processing circuit in this paper. The magnetic field signal can be stored. The power spectrum analysis, line spectrum purification, line spectrum extraction and so on can be processed online, and the processing results are saved and transmitted to the upper computer through serial communication. The test results of laboratory and offshore signal source show that the device has good ability of low frequency alternating magnetic field measurement, analysis and line spectrum extraction. © Published under licence by IOP Publishing Ltd.

关键词： Magnetic fields

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Vertical array signal recovery method based on normalized virtual time reversal mirror

Vertical array signal recovery method based on normalized vi...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Li, P. Zhang, X.G. Zhang, X.Y. Liu, Y. Science and Technology on Underwater Test and Control Laboratory Dalian116013 China Dalian Scientific Test and Control Technology Institute Dalian116013 China

Focusing on the vertical array source signal recovery method, aiming at the estimation deviation caused by environment mismatch in the engineering application of virtual time reversal mirror technology, this paper proposes the normalized virtual time reversal technology through theoretical derivation and analyzes the performance of the virtual time reversal technology under the change of environment and signal-to-noise ratio through simulation. Finally, the practicability of the normalized virtual time reversal method and the effectiveness of model correction are verified through experimental data. The data processing results show that the source level estimation error of vertical array based on normalized virtual time reversal algorithm is less than 5.2dB. In the experimental environment of this paper, the correlation of signal spectral structure recovered by this method is about 5% higher than that by the traditional method. © Published under licence by IOP Publishing Ltd.

关键词： Signal to noise ratio

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Target recognition method based on image simulation technology of underwater target in harsh environment 6

Target recognition method based on image simulation technolo...

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6th Conference on Frontiers in Optical Imaging and technology: Imaging Detection and Target Recognition

作者： Hui, Lin Yunying, Wang Yuanyuan, Guo Fangyuan, Jin Lu, Zhang Meiyu, Sun Science and Technology on Underwater Test and Control Laboratory Dalian116013 China Dalian Maritime University Dalian116026 China

ISBN: (数字)9781510679733

ISBN: (纸本)9781510679726

In order to study the recognition methods of underwater targets in harsh environments and improve the accuracy of image based underwater target recognition, a deep learning based underwater target recognition method in harsh environments was carried out. Propose a simulation method for underwater target harsh environment images based on clearer image samples. The simulation processing mainly includes adding random scale and spatial position obstructions, adding random noise, and obtaining simulated image data. Establish an integrated image dataset, which includes clearer original image data and simulated image data. The recognition results of target recognition models trained on the integrated image dataset have significantly improved compared to the original image dataset. © 2024 SPIE. All rights reserved.

关键词： Deep learning

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Influence and remedial measures of missing test data on magnetic field source location of underwater vehicle

Influence and remedial measures of missing test data on magn...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Hu, Ping Jiao, Dawen Qi, Jiahui Chen, Sidi Science and Technology on Underwater Test and Control Laborary Dalian China

Due to the incomplete data collected, it will increase the difficulty of inversion location in the field source inversion of the static magnetic field data of underwater vehicles. Therefore, it is very necessary to study the influence of data loss on the static magnetic source location of underwater vehicles and the field source location for timely remedy of missing data. In this paper, the static magnetic equivalent source model of underwater vehicle was established. Then the inversion positioning algorithm was used to locate the magnetic field source of the underwater vehicle obtained from the test, and the influence of the location result under the incomplete data information was analyzed. We used deleting method, linear interpolation method and sliding filling method to populate the data to fill the remedy of missing data. Using the localization algorithm to carried out the inversion location of source, then we took the location of source inversion and the size of the magnetic dipole moment to the ellipsoid model to get fitting curve of magnetic field. The simulation curve of contrast verification test data with experimental data and the lack of remedial method was feasible. The results show that the missing data can not be ignored for the location of the underwater vehicle's magnetic field source, and the data pairs filled with missing data can be effectively located for the equivalent static magnetic field source of the underwater vehicle through using deletion method, linear interpolation method and sliding filling method. © Published under licence by IOP Publishing Ltd.

关键词： Location

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Magnetic Field Feature Fusion of underwater Vehicle Model Based on Principal Component Analysis

Magnetic Field Feature Fusion of Underwater Vehicle Model Ba...

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2022 International Conference on Information Processing in Ocean science and technology, ICIPOST 2022

作者： Hu, Ping Chen, Sidi Jiao, Dawen Qi, Jiahui Science and Technology on Underwater Test and Control Laborary Dalian China

Aiming at the model of underwater vehicle, a magnetic field feature fusion method based on principal component analysis (PCA) is proposed, focusing on: Non-stationary, nonlinear and non-Gaussian magnetic field time domain of underwater vehicle model based on genetic algorithm optimization neural network Feature extraction technology, underwater vehicle model fusion technology based on principal component analysis of magnetic field time-domain features, constructs effective PCA fusion features with low dimension, and finally uses the model sample recording data to conduct experiments on the main methods of this paper Verification and experimental simulation results show that PCA fusion features can reduce the feature dimension on the basis of maintaining a sufficient amount of effective information, and improve the target recognition efficiency. The results confirm the effectiveness of the related algorithms. © Published under licence by IOP Publishing Ltd.

关键词： Principal component analysis

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Influence of Physical Parameters on Echo Spectrum of underwater Target

Influence of Physical Parameters on Echo Spectrum of Underwa...

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2024 OES China Ocean Acoustics, COA 2024

作者： Chen, Yunfei Yu, Dapeng Jia, Bing Wang, Zhenshan Yong, Jintao Wang, Yanjie School of Information and Communication Engineering Dalian University of Technology Dalian China Science and Technology on Underwater Test and Control Laboratory Dalian China

ISBN: (纸本)9798350340297

The elastic scattering features of the underwater target scattering wave depend on the physical parameters of the target, such as the material and structure. Intuitively evaluating the influence of the elastic scattering wave on the characteristics of the whole scattering wave signal is difficult due to the coupling and superposition of the elastic scattering wave and the geometric scattering wave of the target. Based on the different modulation characteristics of broadband echo spectrum produced by target geometry scattering and elastic scattering wave, this paper characterizes and studies the modulation features of echo spectrum and tests the influence of physical parameters on the echo spectrum of underwater target using several simple cylindrical targets with different physical parameters. Moreover, the geometric scattering wave and the elastic scattering wave of the simple target echo are extracted using the fractional Fourier transform (FrFT) domain filtering method, and the influence of physical parameters on the echo spectrum is quantitatively analyzed. © 2024 IEEE.

关键词： Elastic scattering

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