Study on Modeling of Shallow Water Acoustic Channel and Its Applications

浅海是水声对抗发生的重要区域,因此对其声信道的研究具有重要意义。采用射线声学理论,建立了一个多途浅海声信道仿真模型。在水声对抗仿真系统中,选用基于AdSP21160的HAMMErHEAd PCI予以实现,取得了预期的实时效果;海试验证结果表明,该模型同样适用于实际情况下浅海海域的声传播损失等参数的折算,可作为水声对抗器材性能预报及战术使用的参考。Underwater acoustic warfare will happen mainly in shallow water region.So study on its acoustic channel is an important task.Based on the Ray Acoustics theory,a simulation model of multi-path shallow water acoustic channel was established.Used in underwater acoustic warfare simulation system with ADSP21160-based Hammerhead PCI,the prospected real-time results were achieved.When it was used in shallow sea trial for parameters calculation such as transmission loss,reasonable results were gotten.The facts imply that the proposed model can be used in performance prediction and tactical reference of acoustic countermeasures

Simulation Study on Wire-guided Torpedo and Countermeasures

在各种鱼雷导引方式中,线导由于不受鱼雷自噪声的影响而具有极佳的寻的性能.研究了其作为鱼雷寻的重要阶段(或者单独导引到底)的导引规律以及常见的弹道形式.研究指出,随着水声对抗系统和技术的发展,对鱼雷线导阶段的对抗也必须得到重视.结合“网络化水声对抗“的研究,提出了利用“水声对抗网络“与线导鱼雷进行对抗的思路和方法.通过仿真,就现有的对抗方法和基于水声对抗网络的对抗效果进行了对比,结果显示了所提方法的优越性,给出了可供水声对抗系统发展参考的相关结论.Among various torpedo guiding styles,wire-guidance suffers least influence of self-noise so that the better seeking performance is achieved.Regarded as an important stage(or an individual stage),its guidance law and the well known ballistic trajectories were investigated.It is pointed out that the counterworking against the wire-guided torpedo must be noticed as the development of underwater acoustic system and technologies.With the development of the concept "Networked Underwater Acoustic Warfare",a new means of counterworking to wire-guided torpedo is presented.Simulation comparison between current measures and the presented measure showed that the latter was much more efficient.Suggestions of the development of underwater acoustic warfare system are put forward as well.“十一五”国防预研项目(4010503010201)资

Detection of Underwater Target Motion State Based on the Dopplerlet Transform

为解决水下目标运动状态的检测问题,提出了一种基于多普勒变换的检测方法.因受被测目标的不同运动状态影响,线性调频信号回波的参数会产生相应变化.利用; 多普勒变换在时频域中良好的能量积聚性,将回波信号稀疏化,然后基于压缩感知重构回波信号的特征参数,同时消除水声信道背景噪声的干扰,从而根据线性调频; 信号回波的物理特征判定水下目标的运动状态.仿真结果表明,该方法提高了非线性信号瞬时性能的时频域分辨率,能够有效检测水下目标的运动状态,并且在低信; 噪比下具有较高的检测概率.This paper proposes a method based on dopplerlet transform for the; detection of underwater target motion state. Influenced by different; motion states of the target under test,linear frequency modulation; signal's echo parameters will encounter corresponding changes.This; method uses the characteristics of dopplerlet transform matrix' which; associated good energy-accumulation characteristics in the; time-frequency domain, to sparse the echo signal.Based on compression; sensing, characteristic parameters of echo signal have been; reconstructed, and at the same time the interference of background; noises in underwater acoustic channel will be eliminated.Consequently,; we can determine the motion state of underwater object according to; physical characteristics of linear frequency modulation signal echo.; Simulation results show thatthe performance of the nonlinear signal; instantaneous time and frequency domain resolution can be improved.This; technique can measure physical parameters of underwater moving target; effectively,and has high detection probability under the low SNR; condition.国家自然科学基

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies