本文關鍵詞：內波對水下聲信號時間相關性影響的數值和實驗研究　出處：《中國海洋大學》2015年博士論文　論文類型：學位論文

  更多相關文章： 線性內波 時間相關半徑 匹配場 絕熱近似 耦合簡正波

【摘要】：海洋中內波的存在會使聲信號的時間相關半徑變小。受物理介質影響的信號時間相關半徑表明了信號由完全相關變?yōu)椴幌嚓P時經過的時間尺度,它是聲納目標的檢測與識別、匹配場聲源定位以及水下通訊的重要技術指標。本文通過數值仿真和海上實驗數據處理,分析了內波對聲場時間相關性的影響,得到了典型聲傳播條件下信號的匹配場時間相關半徑以及時間相關半徑在距離-深度空間上的分布�；趻佄锓匠�(PE)理論,Monte-Carlo數值仿真了線性內波存在時聲場的時間相關函數,得到時間相關性的空間分布。在前人PE仿真所采用的凍結聲學環(huán)境模型的基礎上提出了一種非凍結的環(huán)境模擬方法,時間相關性的數值結果表明,在一定的頻率和接收距離范圍內,凍結模型依然可靠,但頻率越高,接收距離越遠,可靠性越低。對距離-深度空間各個位置處聲場時間相關性的理論和數值研究發(fā)現(xiàn),時間相關性在空間上的分布具有與聲場干涉條紋類似的結構,聲場會聚區(qū)的時間相關性優(yōu)于影區(qū),隨機噪聲的存在使這個結論更加明顯。此外,聲源頻率f、接收距離R和聲速擾動的統(tǒng)計標準差|δc|等參數的改變引起聲場干涉結構的變化,導致時間相關半徑對其不再是對數坐標下的線性依賴。在Monte-Carlo研究的同時,提出了基于絕熱近似和耦合簡正波理論的統(tǒng)計方法。研究結果表明：深遠海聲傳播條件下,絕熱近似得到的匹配場時間相關半徑隨R、f和|δc|的冪指數關系與Monte-Carlo仿真和單向耦合方法的結果近似相同,但它高估了信號的時間相關半徑,且不能正確描述時間相關半徑的空間分布；淺海近距離聲傳播條件下,絕熱近似的計算結果具有一定的可靠性。本文發(fā)展的二維統(tǒng)計模型得到的匹配場時間相關半徑大于前人的三維模型,在本文參數范圍內,數值計算中一般考慮前5號內波模態(tài)和幾十號簡正波就可以保證數值結果的可靠性,但要得到時間相關半徑的空間分布需要考慮更多的簡正波。對ASIAEX2001實驗的聲學數據處理后得到,當聲傳播路徑上出現(xiàn)強孤立子內波時,聲場的時間相關半徑明顯降低,某些時刻300Hz信號的時間相關半徑低于20s,500Hz信號的時間相關半徑甚至降到l 0s內；信號頻率越高,時間相關半徑越短：且聲場的時間相關半徑在深度上有明顯起伏。由兩個位置不同的聲源S1和S2發(fā)射的400Hz信號在接收位置R處的時間相關半徑不同,S2-R路徑的時間相關半徑比S1-R路徑長。這可能是由于內波在S2-R路徑上的相位傳播速度小于S1-R路徑,聲源深度和地形的不同也可能對上述結果有所影響。PE仿真采用的凍結聲學環(huán)境忽略了內波在傳播過程中波形和強度的變化,導致計算得到的時間相關半徑比實驗數據處理的結果要長。因此,建立更加完善的非凍結環(huán)境模型需要在發(fā)射與接收間布放足夠多的溫度鏈以監(jiān)測內波傳播過程中的演變。
[Abstract]:The existence of internal waves in the ocean will make the time correlation radius of acoustic signal smaller. The time correlation radius of the signal affected by physical medium indicates the time scale of signal from complete correlation to irrelevant. It is an important technical index of sonar target detection and recognition, matching field source location and underwater communication. In this paper, the influence of internal wave on the time dependence of sound field is analyzed by numerical simulation and offshore experimental data processing. The time correlation radius of the matching field and the distribution of the time correlation radius in the distance-depth space are obtained under the typical sound propagation condition. The theory of the parabolic equation (PE) is used to obtain the distribution of the time-dependent radius of the signal in the range-depth space. The time correlation function of sound field in the presence of linear internal wave is simulated numerically by Monte-Carlo. Based on the frozen acoustic environment model used in previous PE simulation, a non-frozen environmental simulation method is proposed, and the numerical results of time correlation show that. In a certain range of frequency and receiving distance, the freezing model is still reliable, but the higher the frequency, the longer the receiving distance. The lower the reliability is, the more the theoretical and numerical study on the temporal correlation of sound field at each position in the range-depth space shows that the spatial distribution of temporal correlation has a structure similar to that of the interference fringes of sound field. The temporal correlation of the acoustic field convergence region is better than that of the shadow area, and the existence of random noise makes this conclusion more obvious. In addition, the sound source frequency f. The change of receiving distance R and the statistical standard deviation 未 c of the acoustic velocity disturbance leads to the change of the sound field interference structure. Therefore, the time-dependent radius is no longer a linear dependency in logarithmic coordinates. A statistical method based on adiabatic approximation and coupled normal wave theory is proposed. The results show that the time-dependent radius of the matching field obtained by adiabatic approximation depends on R. The power exponent relation of f and 未 c is approximately the same as that of Monte-Carlo simulation and unidirectional coupling method, but it overestimates the time-dependent radius of the signal. And the spatial distribution of time-dependent radius can not be correctly described. The calculated results of adiabatic approximation are reliable under the condition of near distance acoustic propagation in shallow water. The time correlation radius of the matching field obtained by the two-dimensional statistical model developed in this paper is larger than that of the previous three dimensional model. In the parameter range of this paper, the reliability of the numerical results can be guaranteed by considering the first 5 internal wave mode and the dozens of normal waves in the numerical calculation. But in order to obtain the spatial distribution of time-dependent radius, we need to consider more normal waves. After processing the acoustic data of ASIAEX2001 experiment, we can get that, when the strong soliton internal waves appear on the sound propagation path. The time correlation radius of sound field decreases obviously, and the time correlation radius of 300 Hz signal at some times is lower than that of 20 s ~ 500 Hz signal, even within 10 s. The higher the signal frequency. The shorter the time-dependent radius:. The time correlation radii of sound field fluctuate obviously in depth. The time correlation radii of 400 Hz signals transmitted by two different sound sources S1 and S2 are different at the receiving position R. The time-dependent radius of the S2-R path is longer than that of the S1-R path, which may be due to the fact that the phase propagation velocity of the internal wave in the S2-R path is lower than that in the S1-R path. The difference of sound source depth and topography may also affect the above results. The frozen acoustic environment used in PE simulation ignores the variation of the waveform and intensity of the internal wave in the process of propagation. The calculated time correlation radius is longer than that of experimental data processing. To establish a more perfect non-freezing environment model, enough temperature chains should be placed between the transmitter and receiver to monitor the evolution of internal wave propagation.
【學位授予單位】：中國海洋大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：P733.2;TB56

【相似文獻】

相關期刊論文 前10條

1 易學華;陳泗凱;賴鵬華;卜壽亮;鐘慶湖;;量子絕熱近似條件與量子幾何勢[J];量子電子學報;2014年02期

2 黃昆;多聲子復合理論中絕熱近似是否失效的問題[J];半導體學報;1980年01期

3 朱公先;過阻尼振子系統(tǒng)中役使原理與絕熱近似的關系及適用條件的探討——線性情況(Ⅰ)[J];北京師范學院學報(自然科學版);1988年02期

4 朱公先;過阻尼振子系統(tǒng)中役使原理與絕熱近似的關系及適用條件的探討——非線性情況(Ⅱ)[J];北京師范學院學報(自然科學版);1988年03期

5 曹力,吳大進;確定論系統(tǒng)快弛豫變量的精確消去和絕熱近似[J];華中理工大學學報;1992年02期

6 孫昌璞，趙樹人;時間軌道勢的理論分析[J];東北師大學報(自然科學版);1996年03期

7 劉倩,吳兆顏;高級量子絕熱近似理論在經典物理中的應用[J];萊陽農學院學報;2004年04期

8 張新琴;夏秀文;羅小兵;;含時磁共振系統(tǒng)的精確解和絕熱近似解[J];大學物理;2011年07期

9 黃英華;;納機電系統(tǒng)的兩種解法比較——嚴格數值解和絕熱近似解[J];華北科技學院學報;2012年02期

10 朱公先;一維阻尼型弱非線性的運動系統(tǒng)中延遲響應時間的計算法[J];杭州師范學院學報;1993年06期

相關博士學位論文 前2條

1 于小濤;內波對水下聲信號時間相關性影響的數值和實驗研究[D];中國海洋大學;2015年

2 趙梅生;量子信息理論中若干問題的研究[D];中國科學技術大學;2007年

相關碩士學位論文 前3條

1 俞春明;量子絕熱近似中Berry相因子的幾何結構[D];吉林大學;2006年

2 秦江濤;量子系統(tǒng)Berry相位、A-A相位和PM相位的研究[D];魯東大學;2015年

3 王英霞;強磁場中氫分子離子能級研究[D];中國石油大學;2007年

，

本文編號：1408471