發(fā)布時(shí)間：2018-07-25 15:39

【摘要】：隨著軍用核武器、核材料及核技術(shù)擴(kuò)散日益嚴(yán)重,以及核輻射事故和核恐怖事件特有的突發(fā)性,對社會安全和國家政治經(jīng)濟(jì)有極大威脅,具有核探測設(shè)備的多旋翼飛行器在核環(huán)境中的應(yīng)用已經(jīng)逐漸凸顯出它的優(yōu)勢與不可估量的效果。本文圍繞放射性物質(zhì)探測、識別和處置問題,開展了理論與實(shí)際緊密結(jié)合的多旋翼飛行器γ譜儀關(guān)鍵技術(shù)研究工作。主要內(nèi)容包括以下幾方面:在研究數(shù)字譜儀原理和結(jié)果的基礎(chǔ)上,分析得出多旋翼飛行器影響γ譜儀性能的主要因素及需要解決的關(guān)鍵技術(shù)問題。針對多旋翼飛行器平臺,對傳統(tǒng)核能譜儀數(shù)字處理方法進(jìn)行分析、比較,并確定合成成形法、時(shí)間比較法、平均法為該平臺的γ譜儀數(shù)字處理方法,為能譜分析奠定基礎(chǔ)。針對傳統(tǒng)譜線平滑方法在濾波器參數(shù)選擇不當(dāng)或平滑次數(shù)過多時(shí)引起譜線畸變的缺點(diǎn),提出一種遞歸最小二乘法的能譜平滑方法。利用自適應(yīng)濾波器原理,采用快速卡爾曼實(shí)現(xiàn)遞歸最小二乘法,并通過前向、后向預(yù)測器更新濾波器系數(shù),實(shí)現(xiàn)能譜數(shù)據(jù)的平滑處理。通過實(shí)驗(yàn)將該方法與多項(xiàng)式最小二乘法、最小均方算法進(jìn)行定性分析與比較,結(jié)果表明該方法能較好地降低能譜中的噪聲,并能保持能譜的特征。針對傳統(tǒng)神經(jīng)網(wǎng)絡(luò)在核素識別中訓(xùn)練效果弱,易陷入局部極小、收斂速度慢等問題,提出了基于概率神經(jīng)網(wǎng)絡(luò)的核素識別方法。平滑后的能譜數(shù)據(jù)通過希爾伯特-黃變換進(jìn)行特征提取,將譜峰寬度、特征能量射線強(qiáng)度、峰面積等特征信息作為概率神經(jīng)網(wǎng)絡(luò)的輸入,建立訓(xùn)練與測試樣本從而進(jìn)行核素識別。實(shí)驗(yàn)結(jié)果表明,此算法可以處理單一核素、混合核素以及未知核素的情況,可應(yīng)用于安全監(jiān)控、失控放射物探測等快速核素識別領(lǐng)域。最后,搭建了一套多旋翼飛行器γ譜儀關(guān)鍵技術(shù)測試平臺,該平臺具有前置放大、增益可調(diào)放大及數(shù)據(jù)采集等功能,對理論得出的最優(yōu)化數(shù)字核信號處理方案的可行性與合理性進(jìn)行了驗(yàn)證。為核事故突發(fā)情況下,使用具有核探測的多旋翼飛行器為核事故現(xiàn)場勘察和障礙排除奠定堅(jiān)實(shí)的基礎(chǔ)。
[Abstract]:With the increasing proliferation of military nuclear weapons, nuclear materials and nuclear technology, as well as the sudden occurrence of nuclear radiation accidents and nuclear terrorist incidents, they pose a great threat to social security and national political and economic development. The application of multi-rotor aircraft with nuclear detection equipment in nuclear environment has gradually highlighted its advantages and inestimable effects. This paper focuses on the problem of detection, identification and disposal of radioactive materials, and studies the key techniques of 緯 spectrometer of multi-rotary-wing aircraft, which are closely combined with theory and practice. The main contents are as follows: on the basis of studying the principle and results of the digital spectrometer, the main factors affecting the performance of the 緯 spectrometer and the key technical problems to be solved are obtained. This paper analyzes and compares the traditional digital processing methods of nuclear energy spectrometer for multi-rotor aircraft platform, and determines the synthetic shaping method, time comparison method and average method as the digital processing methods of 緯 -spectrometer of the platform, and lays a foundation for energy spectrum analysis. Aiming at the disadvantage of the traditional spectral line smoothing method which causes spectral line distortion when the filter parameters are not chosen properly or when the number of smoothing is too many a recursive least square method is proposed for spectral smoothing. Based on the principle of adaptive filter, the recursive least square method is implemented by using fast Kalman method, and the filter coefficients are updated by the forward and backward predictors to smooth the energy spectrum data. The method is qualitatively analyzed and compared with the polynomial least square method and the least mean square algorithm. The results show that the proposed method can reduce the noise in the energy spectrum and preserve the characteristics of the energy spectrum. In order to solve the problems of weak training effect, easy to fall into local minima and slow convergence rate of traditional neural network in nuclide recognition, a method of nuclide recognition based on probabilistic neural network is proposed. The smooth energy spectrum data are extracted by Hilbert-Huang transform, and the spectral peak width, characteristic energy ray intensity and peak area are used as the input of the probabilistic neural network. Establish training and test samples to identify nuclides. The experimental results show that the algorithm can deal with single nuclides, mixed nuclides and unknown nuclides, and can be used in the field of rapid nuclide recognition such as security monitoring, uncontrolled radionuclide detection and so on. Finally, a set of key technology test platform for multi-rotor aircraft gamma-ray spectrometer is built. The platform has the functions of preamplifier, gain adjustable amplification and data acquisition, etc. The feasibility and rationality of the optimized digital nuclear signal processing scheme are verified. It lays a solid foundation for nuclear accident site investigation and obstacle removal by using multi-rotor aircraft with nuclear detection.
【學(xué)位授予單位】：西南科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：V241;TL817.2

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本文編號：2144274