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摘要:
针对固体发动机电子计算机断层扫描(CT)图像数据具有伪影噪声的问题,和实际成型药柱燃面粗糙度大、退移计算难度大的问题,提出一种CT数据的快速最小距离函数(CT-FMDF)法。固体火箭发动机CT图像中存在伪影噪声,采用非均值滤波(NLM)算法对CT图像进行去噪处理,采用Scharr算子对去伪影后的图像进行Canny边缘检测,提取装药燃面。最大类间方差(OTSU)算法将装药分离,并建立三维装药体数据模型,对燃面数据建立多个并行K-d树,快速检索出装药到燃面的最小距离。实验结果证明:对于不同的装药结构,可以完成任意燃去厚度时的燃面位置,且CT-FMDF法运行时间更短。基于CT实测数据,对于带有初始燃面缺陷的装药,可计算出燃烧时缺陷对燃面的影响。
Abstract:A fast minimum distance function method for CT data (CT-FMDF) is proposed to address the artifact noise in CT image data of solid rocket motors, the large combustion surface roughness of actually formed grains, and the difficulty in transition calculation. The non-local means (NLM) filtering algorithm is used to denoise the CT images. Then, the Canny edge detection improved by the Scharr operator is used to extract the initial burning surface of the grains from the de-artifacted image. The maximum between-class variance algorithm (OTSU) separates the grains, establishing a three-dimensional volume data model of grains, and multiple parallel K-dimension trees for the combustion surface data. The minimum distance from the grains to the combustion surface is quickly retrieved. The experimental results show that for different grains structures, the position of a burning surface at any thickness can be achieved and that the algorithm has a shorter running time. For the grains with initial burning surface defects, the effect of the defects on the burning surface during combustion can be calculated based on the actual CT data.
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Key words:
- solid motor /
- minimum distance function /
- CT image /
- grain burnback /
- K-d tree
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表 1 K-d树的数据结构
Table 1. K-d tree data structure
域名 数据类型 描述 Node-data 数据矢量 数据集中某个数据点,
是n维矢量(本文就是k维)Range 空间矢量 该节点所代表的空间范围 split 整数 垂直于分割超平面的方向轴序号 Left K-d树 由位于该节点分割超平面左子空间内
所有数据点所构成的K-d树Right K-d树 由位于该节点分割超平面右子空间内
所有数据点所构成的K-d树Parent K-d树 父节点 表 2 去噪声图像质量分析
Table 2. Quality analysis of denoising image
去噪算法 MSE PSNR SSIM NLM(星形) 1.62984 46.0094 0.999048 NLM(圆柱) 6.33753 40.1116 0.997223 BM3D(星形) 2.16834 44.7695 0.998738 BM3D(圆柱) 3.74647 42.3946 0.998386 双边滤波(星形) 5.76638 40.5218 0.996544 双边滤波(圆柱) 10.8642 37.7708 0.995227 高斯滤波(星形) 8.27121 38.9551 0.995228 高斯滤波(圆柱) 7.36916 39.4566 0.996813 表 3 星形装药特征参数
Table 3. Characteristic parameters of star grain
肉厚
w/mm星角
数n星边
夹角θ/(°)星尖角
分数ε星尖导圆
半径f/mm特征
长度l/mm星根尖倒圆
半径r/mm220 6 45 0.7 20 230 20 -
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