基于光场成像理论的弥散介质光热特性重构

发布时间：2018-01-04 05:13

  本文关键词：基于光场成像理论的弥散介质光热特性重构　出处：《哈尔滨工业大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 弥散介质 光场成像 多参数群重构 广义源项多流法 LSQR-SPSO混合优化算法

【摘要】：弥散介质广泛存在于自然界和工业生产过程中,发展弥散介质光热参数(主要包括辐射特性参数和温度场)非接触测量方法和理论,构建具有高置信度的光热参数基础数据库,对于推动航空航天、能源动力、国防科技、生物医学、冶金化工等领域的发展至关重要。本文基于先进的光场成像理论结合弥散介质内辐射传输正、反问题求解算法构建基于光场成像技术的弥散介质光热参数同时重构方法。首先系统地阐述了弥散介质内辐射传输机理和光场成像原理。考虑光场成像可同时获取多方向辐射信息的特点分别针对纯吸收介质和吸收、发射、散射性介质建立基于视在光线法(LOS)和广义源项多流法(GSMFM)的介质任意方向辐射强度的快速精确计算方法。并进一步结合光场成像原理构建了完整的基于光场成像技术的弥散介质辐射强度四维光场信息获取的辐射传输过程的数值模拟方法,并采用该方法成功模拟了火焰的光场信息获取过程,获得了相应的原始光场模拟图像。针对弥散介质辐射传输反问题的研究,归纳总结了目前常用的几种求解辐射传输反问题的正则化方法、梯度基方法和智能优化算法。在此基础上发展了几种改进型算法并将其应用于辐射传输逆问题的求解,证明了改进的算法具有更高的精度、效率和稳定性。在上述辐射传输正、反问题理论研究基础上建立了基于最小二乘QR分解算法(LSQR)的介质三维温度场重构方法,在介质辐射特性参数已知条件下根据介质边界出射辐射强度分布重构介质三维温度场,并且通过大量的计算证明该重构方法具有较高的计算精度和计算效率。同时研究了介质辐射特性参数、温度场重构分辨率以及辐射强度成像分辨率对介质温度场重构精度的影响。进一步提出了基于LSQR-SPSO混合优化算法的弥散介质光热参数同时重构方法,根据介质两组不同方向上的辐射强度分布同时重构出介质的三维温度场和均匀辐射特性参数(吸收系数、散射系数)。大量的数值模拟计算结果表明该方法是精确有效的。同时还分析了介质的辐射特性参数大小对于介质光热参数重构精度的影响。充分利用介质光场图像中的光谱信息,结合多光谱技术优化了基于LSQRSPSO混合优化算法的弥散介质光热参数同时重构方法,大幅度提高了介质温度场和均匀辐射特性参数的重构精度。并进一步考虑具有一定场参数优化能力的共轭梯度法提出了基于多光谱技术和LSQR-CG混合优化算法的弥散介质三维温度场和非均匀辐射特性参数同时重构方法。通过大量数值模拟计算证明该方法可有效地同时重构出介质的非均匀光热参数分布,并且与采用均匀辐射特性参数场的重建模式相比可有效提高温度场的重构精度,更适合于工程实际中弥散介质三维温度场的重构。最后,针对乙烯扩散火焰开展了基于光场成像的高温发光火焰光热参数重构试验研究。根据单光场图像分别重构得到了乙烯扩散火焰和掺杂Al2O3颗粒的乙烯扩散火焰的三维温度分布和非均匀辐射特性参数分布,并通过与热电偶测量结果和现有文献中结果的对比证明了本文提出的基于光场成像技术的弥散介质三维温度场和辐射特性参数分布重构方法是合理可行的。
[Abstract]:The dispersion medium widely exists in nature and in the process of industrial production, the development of dispersion medium photothermal parameters (including radiation parameters and temperature field) non contact measuring method and theory, build a database on the basis of photothermal parameters with high confidence, for the promotion of aerospace, energy power, national defense science and technology development, biomedicine, metallurgy and other fields. This paper advanced light field imaging theory combined with the dispersion medium radiation transmission is based on the construction of anti problem solving algorithm and reconstruction of light field imaging technology diffusion medium photothermal parameters method based on the first systematic exposition of the dispersion medium radiation transmission mechanism and light field imaging principle. Considering the characteristics of light field imaging can simultaneously obtain the multi direction radiation information for pure absorption medium and absorption, emission, and scattering light in the visual establishment method based on (LOS) and generalized sources Multi stream method (GSMFM) fast and accurate calculation method of the medium in any direction radiation intensity. And further combined with the light field imaging principle is constructed based on light field imaging dispersion medium radiation intensity of 4D light field numerical simulation method for radiative transfer process of information acquisition, and successfully simulated the field information acquisition process of the flame by this method, the image simulation of corresponding original light field. Research on the inverse problem of dispersion medium radiation transfer, summarizes the current commonly used to solve the radiative transfer inverse problem regularization method, gradient based method and intelligent optimization algorithm. On the basis of the development of several improved algorithm which is used to solve the inverse problem of radiative transfer, it is proved that the improved algorithm has higher precision, efficiency and stability. The radiative transfer is the inverse problem theory based on the study of building The QR decomposition algorithm based on least squares (LSQR) reconstruction method of medium 3D temperature field, radiation characteristic parameters in the medium under medium boundary radiation intensity distribution of 3D temperature field reconstruction of medium, and through a lot of calculation show that the reconstruction method has higher calculation accuracy and efficiency. At the same time on the radiation characteristics of the medium parameter, temperature field reconstruction resolution and radiation intensity imaging resolution on the reconstruction accuracy of medium temperature field is discussed. We propose an LSQR-SPSO hybrid dispersion medium photothermal parameters optimization algorithm and reconstruction method based on radiation intensity distribution at the same time, according to the media two groups in different directions to reconstruct the 3D temperature field of medium and uniform radiative properties (absorption coefficient, scattering coefficient). The simulation results show that this method is accurate and effective numerical analysis. At the same time Radiation parameters influence on the medium size medium. The reconstruction accuracy of photothermal parameters to make full use of the spectral information medium light field image, combined with multi spectral technology optimization of hybrid LSQRSPSO dispersion medium photothermal parameters optimization algorithm and the reconstruction method based on, greatly improve the reconstruction accuracy of medium temperature and uniform radiation characteristic parameters and further. Consider certain field parameters optimization ability of the conjugate gradient method proposed multi spectral technology and the dispersion medium of 3D temperature field of LSQR-CG hybrid optimization algorithm and non characteristic parameters at the same time the reconstruction method of uniform radiation based on numerical simulation. Through a large number of non uniform thermal parameter distribution calculation show that the method can effectively reconstruct the medium, and the uniform radiation characteristic parameter field reconstruction model can effectively improve the reconstruction accuracy compared to the temperature field, which is more suitable for engineering The actual dispersion medium of 3D temperature field reconstruction. Finally, the ethylene diffusion flame experiment was conducted to study the thermal parameter reconstruction of flame emission light field imaging based on high temperature. Based on the single light field reconstruction images were obtained of ethylene diffusion flame and doped Al2O3 particles of ethylene diffusion flame three-dimensional temperature distribution and non-uniform radiation parameters distribution. And through the comparison with the results of the thermocouple measurement results and the existing literature in this paper proves that the light field imaging technology diffusion medium three-dimensional temperature field and radiation characteristic parameter reconstruction based method is reasonable and feasible.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O439
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本文编号：1377193