Real-time pixel based early apple bruise detection using short wave infrared hyperspectral imaging in combination with calibration and glare correction techniques

High speed data processing for online food quality inspection using hyperspectral imaging (HSI) is challenging as over hundred spectral images have to be analyzed simultaneously. In this study, a real-time pixel based early apple bruise detection system based on HSI in the shortwave infrared (SWIR) range has been developed. This systems consists of a novel, homogeneous SWIR illumination unit and a line scan camera. The system performance was tested on Jonagold apples bruised less than two hours before scanning. Partial least squares-discriminant analysis was used to discriminate bruised pixel spectra from sound pixel spectra. As the glossiness of many fruit and vegetables limits the accuracy in the detection of defects, several reflectance calibrations and pre-processing techniques were compared for glare correction and maximizing the signal to noise ratio. With the best combination of first derivative and mean centering, followed by image post-processing, this system was able to detect fresh bruises in thirty apples with 98% accuracy at the pixel level with a processing time per apple below 200 ms.     

横移车前端钢管的自动对中设计

介绍焊管生产线前辊道上的钢管中心与横移车中心线的自动对中方法。     

曲轴加工中的车床配重计算

本文以偏心曲轴为例,介绍一种车床配重的计算方法,并对计算配重的一些注意事项进行了说明。     

工业缝纫机自动更换底线装置的研究与应用

提出了一种新的自动更换工业缝纫机底线的工艺方法,设计出了相应的自动更换底线装置;对装置中的关键部件抓取机械手的结构进行了分析;通过仿真分析确定了机械手气缸输入压力的合理范围;最后加工出机械手样机,并进行梭芯套抓取试验。试验结果表明：抓取机械手的原理正确,结构合理,但需要对机械手与梭芯套的接触面进行一定的处理,以提高抓取和定位的可靠性。     

Fine grinding of silicon wafers: a mathematical model for the chuck shape

Fine grinding of silicon wafers is a patented technology to manufacture super flat semiconductor wafers cost-effectively. Two papers on fine grinding were previously published in this journal, one discussed its uniqueness and special requirements, and the other presented the results of a designed experimental investigation. As a follow up, this paper presents a study aiming at overcoming one of the technical barriers that have hindered the widespread application of this technology, namely, the difficulty and uncertainty in chuck preparation. Although the chuck shape is critically important in fine grinding, there are no standard procedures for its preparation. Furthermore, the information on the relation between the set-up parameters and the resulting chuck shape is not readily available. In this paper, a mathematical model for the chuck shape is first developed. Then the model is used to predict the relations between the chuck shape and the set-up parameters. Finally, the results of the pilot experiments to verify the model are discussed.     

大跨度石拱桥的全桥结构仿真分析研究

阐述了全桥结构仿真分析的基本思路。结合丹河新桥这一世界最大跨度石拱桥的实例 ,详细介绍了如何建立由多种单元组合而成 ,包括上部结构、下部结构和地基在内的全桥结构仿真分析模型 ,并借助上述模型 ,进行了结构分析计算。计算结果表明 :全桥结构仿真分析技术在大跨度石拱桥的分析计算中 ,能得到较传统计算理论更加详尽和精确的结果 ,有着良好的应用前景     

压电式四向无定心钻削测力仪的研制

根据“力偶矩在平面内移动,其值不变”原理研制出新型压电式四向无定心钻削测力仪.轴向力和切向力分别采用两片X0°和Y0°晶片对装;扭矩采用4对Y0°晶片均布在同一分布圆上,各晶片电荷灵敏度方向与分布圆相切,即可实现无定心扭矩测量.标定结果表明,该测力仪轴向力、径向力和扭矩的线性度和重复性均小于1％,横向干扰小于5％,完全达到了石英力传感器的使用要求.     

激光对中仪的工作原理及其应用

介绍了设备对中的必要性和传统的千分表对中法,分析了激光对中仪的工作原理及其在供水行业的应用实例。通过技术比较,证明激光对中仪用于设备的安装调试具有传统对中方法难以比拟的优势。     

最小二乘圆法及其在原木定心中的应用

利用模态分析中的拟合圆法求圆度误差的最小二乘圆,给出二乘圆的圆心坐标C(a,b)及二乘圆的半径R,并与国际统一文件CIRP法作比较,找出两种方法的异同点,同时比较它们在实际应用中的精确程度,为其在制材中的合理应用提供一定的科学依据。     

高速、低滚动阻力子午线轮胎一次法成型机的开发

从结构、性能、技术特征、主要参数等方面较详细的介绍了自主开发的高速、低滚动阻力子午线轮胎一次法成型机,证明该成型机具有广泛的推广应用前景.