| 题名 | 光学织针监测与气溶胶粒子形状识别技术研究 |
| 作者 | 刘鹭 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 赵永凯 |
| 关键词 | 织针 气溶胶 光散射 形状识别 |
| 其他题名 | Development of optical knitting needle monitoring and aerosol particle shape recognition technique |
| 中文摘要 | 光学检测技术通常具有快速、灵敏、无损的特点，针对纺织工业生产与环境保护而开展的相关技术研究具有实际意义。本文的工作主要包含两部分内容：织针实时监测装置的研制和气溶胶粒子形状识别技术研究。 纺织工业是我国国民经济的传统支柱产业。作为主流纺织机械，针织机被广泛应用于现代纺织生产中。针织机上织针针钩的断裂或过度偏弯会导致织物上连续的疵点或缝隙的产生，严重影响织品质量。因此，针织机上有必要安装一种织针的实时监测装置，用于检测织针的状态，在探测到织针异常以后立即报警并停止针织机的作业，以进行织针更换或复检。 经过了对国内外相关产品和检测技术的调研，我们研制了一种织针实时监测装置。该装置主要包括探测光源模块、光电探测器、Y字型光纤束、成像光学镜组和信号处理模块五部分。探测光源模块发出的光由Y字型光纤束传入成像光学镜组前方，经镜组会聚至织针针钩弯曲的外表面，从针钩外表面反射的光纤通过成像光学镜组返回，由Y字型光纤束传回至光电探测器，探测器将测得的光信号转为电信号送至信号处理模块进行分析。测试和初步实用结果表明，该装置能够完成对小型针织机的织针状态的实际监测。 气溶胶是悬浮于气体中的固体或液体粒子构成的胶状体系。其中，生物气溶胶对环境和人类健康有着重要的影响。不同气溶胶粒子通常具有不同形状，其弹性光散射图样与粒子尺寸和形状密切相关，因此可用于推断粒子的种类和来源。 我们首先通过对不同形状气溶胶粒子进行建模，基于时域有限差分法（FDTD）方法仿真其二维（2D）前向散射图样，分析了该方法对粒子尺寸与形状进行分辨的具体要求和可行性。基于麦克斯韦电磁场理论，FDTD方法可以处理复杂结构和非均匀介质粒子的电磁场散射问题。我们根据调研，以具有代表性的细菌和氯化钠晶体等粒子为参考建立了六种形态粒子模型进行仿真。 结合实际检测条件和对仿真结果的对比分析，我们得到以下结论：对球体粒子散射图样，利用散射光强第一极小值和第一极大值对应散射角度来估算粒径大小时，测量粒径下限受到实验能够采集到的最大散射角度的限制，当最大散射角为30°时，能够测量的粒径下限接近2μm；对于非球体粒子如椭球体、杆状体、螺旋体，可利用其极大值光条纹形状来分辨不同形态；对于非球体粒子如弧状体，粒子的弯曲程度可以由靠近中央亮斑的上下条纹光强度减弱部分来判断；对于正立方体粒子，其散射图样与其他模拟粒子有较大不同，与粒子空间取向有极大关系。 针对粒子散射光测量需求和国内外相关技术调研，依据气路、光学、机械、电子技术经验，设计了气溶胶粒子形状识别实验装置。装置包括五个单元：针对气溶胶粒子0~20°前向散射图样设计。实验结果表明，该装置可以检测到微小散射体的散射图样。 |
| 英文摘要 | Optical detection techniques usually have rapid, sensitive, non-destructive characteristics. Research associated with the textile industry production and environmental protection is of practical significance. The work of this paper mainly includes 2 parts studies: development of real-time knitting needle monitoring apparatus and aerosol particle shape recognition technique. Textile industry is a traditional pillar industry of the national economy of China. As a mainstream textile machinery, knitting machines are widely used in modern textile production. Broken or curving hook of needle on the knitting machine will result in a continuous defect or gap which could seriously affect the quality of fabric. Therefore, it is necessary to adopt a real-time knitting needle monitoring apparatus for hook status detection. When the needle becomes abnormal, this apparatus can stop the machine and raise the alarm immediately. Then needle will be replaced and re-examined. By study of the domestic and foreign products and testing technology, we developed a real-time knitting needle monitoring apparatus. The device consists of light source module, photoelectric detector, Y-shaped fiber bundle, imaging lens, signal processing module. The source light passes through the Y-shaped fiber bundle and converged by the imaging lens on outer surface of the needle hook. The reflected light collected by lens and fiber bundle and introduced into photoelectric detector. The electric signal converted from light will be analyzed by signal processing module. The test and trial results show that it has been able to meet the monitoring requirements of small knitting machine. An aerosol is defined as a colloidal system of solid or liquid particles in a gas. In particular, biological aerosols have an important effect on human health and environment. Different types of aerosol particles generally have different shapes. Their elastic light scattering pattern is closely related to particle size and shape, Hence, the type and source of aerosol particles could be deduced by their patterns. Aim to classify the different shapes of aerosol particles, we studied the simulation of two dimensional (2D) light scattering pattern of single particle based on finite-difference time-domain (FDTD) method. Based on the Maxwell''s theory, FDTD method is flexible in dealing with the electromagnetic scattering problem of complex structure and inhomogeneous media particle. We build six models to simulate according to representative aerosol particle shapes of bacteria and NaCl crystal particles. Combined with the actual test conditions and comparative analysis of simulation results, we get the following conclusions: For sphere particles, to estimate the particle size, resolvable limit is near to 2μm when experiment is based on the forward scattering angle of first minimum and maximum within the range of 0~30°. For ellipsoid, rhabdus and spiral particles, they could be sorted according to the ring patterns and the existence of truncation. For arc particles, it may be possible to distinguish their curvature by weak intensity part on horizontal stripes. For cube particle, the pattern is more different with other shape particles and has great relevance with orientation. According to light scattering measurement requirements, domestic and foreign related technology investigation, we design a preliminary experimental device of aerosol particle shape recognition based on gassy, optical, mechanical, electronic technical experience. Device includes five units and aim to aerosol particles forward scattering pattern with 0~20 degrees. Test results shows that the small scatterer light scattering pattern detection can be realized by optical system of this device. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16864]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 刘鹭. 光学织针监测与气溶胶粒子形状识别技术研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
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