科创中国

针对当前基于自然特征的增强现实效率低,提出一种新的基于ORB自然特征的实时注册方法.提取视频帧与基准图像中的ORB特征点,使用汉明距离匹配,利用RANSAC算法筛选得到最佳匹配点对,确定摄像机的位姿.将三维虚拟物体叠加到真实场景中,达到虚实结合的效果.实验表明,在不同尺度角度、一定环境光变化、复杂背景和基准图像部分遮挡的情况下,该AR系统都具有良好的性能,跟踪定位准确度高,速度基本达到实时要求

As one of the most wear monitoring indicator, dimensional feature of individual particles has been studied mostly focusing on off-line analytical ferrograph. Recent development in on-line wear monitoring with wear debris images shows that merely wear debris concentration has been extracted from on-line ferrograph images. It remains a bottleneck of obtaining the dimension of on-line particles due to the low resolution, high contamination and particle's chain pattern of an on-line image sample. In this work, statistical dimension of wear debris in on-line ferrograph images is investigated. A two-step procedure is proposed as follows. First, an on-line ferrograph image is decomposed into four component images with different frequencies. By doing this, the size of each component image is reduced by one fourth, which will increase the efficiency of subsequent processing. The low-frequency image is used for extracting the area of wear debris, and the high-frequency image is adopted for extracting contour. Second, a statistical equivalent circle dimension is constructed by equaling the overall wear debris in the image into equivalent circles referring to the extracted total area and premeter of overall wear debris. The equivalent circle dimension, reflecting the statistical dimension of larger wear debris in an on-line image, is verified by manual measurement. Consequently, two preliminary applications are carried out in gasoline engine bench tests of durability and running-in. Evidently, the equivalent circle dimension, together with the previously developed concentration index, index of particle coverage area(IPCA), show good performances in characterizing engine wear conditions. The proposed dimensional indicator provides a new statistical feature of on-line wear particles for on-line wear monitoring. The new dimensional feature conveys profound information about wear severity.

The classical natural coordinate modeling method which removes the Euler angles and Euler parameters from the governing equations is particularly suitable for the sensitivity analysis and optimization of multibody systems. However, the formulation has so many principles in choosing the generalized coordinates that it hinders the implementation of modeling automation. A first order direct sensitivity analysis approach to multibody systems formulated with novel natural coordinates is presented. Firstly, a new selection method for natural coordinate is developed. The method introduces 12 coordinates to describe the position and orientation of a spatial object. On the basis of the proposed natural coordinates, rigid constraint conditions, the basic constraint elements as well as the initial conditions for the governing equations are derived. Considering the characteristics of the governing equations, the newly proposed generalized-α integration method is used and the corresponding algorithm flowchart is discussed. The objective function, the detailed analysis process of first order direct sensitivity analysis and related solving strategy are provided based on the previous modeling system. Finally, in order to verify the validity and accuracy of the method presented, the sensitivity analysis of a planar spinner-slider mechanism and a spatial crank-slider mechanism are conducted. The test results agree well with that of the finite difference method, and the maximum absolute deviation of the results is less than 3%. The proposed approach is not only convenient for automatic modeling, but also helpful for the reduction of the complexity of sensitivity analysis, which provides a practical and effective way to obtain sensitivity for the optimization problems of multibody systems.

衡水市水功能区一级功能区共涉及25个,二级功能区共涉及23个.为加强水功能区保护和管理,结合当地实际情况,共在10处重点水功能区常设12处水质监测断面.通过对多年监测数据分析,功能区受点源、面源污染以及上游下泄污水等因素影响,水质污染较重,达标率较低,2010年仅为20%.针对境内自产入河污染物,对照河流纳污能力,消减任务最重的是滏阳河衡水景观娱乐用水区段.降低污染,恢复水体功能任务艰巨,依据现有条件,可积极寻求开发污水再生利用、消减面源污染等途径,以实现水生态良性循环.

《东方之旅》是黑塞最重要的作品之一.它蕴含了作者大半生的对人的内在精神世界以及人类文化所作的思考和总结.黑塞将中国老子哲学思想与西方宗教文化融于作品之中,运用比喻、暗喻等手法表述深刻的思想内涵,使人物和情节都给人以神秘、魔幻的感觉.主人公雷欧兼具东西方文化的特征,这种多文化互补的形式才是人类心灵的寓所."双体人像"的情节则暗示了人类各民族文化是一个整体,与自然、宇宙和谐共生.《东方之旅》展现了黑塞的多文化和谐共存思想.

为了降低药物开发后期的失败率,指导侯筛化合物库的设计,药物化学家提出了许多基于化学信息学或计算化学的"成药性"理论指标,这些预测方法日益成熟,取得了广泛应用.本文综述了现有的化合物成药性预测方法的研究进展,包括类药性、类先导性、类天然产物、类代谢物以及生物相关性等,对比了各种成药性预测方法的特征,分析了各种预测方法的优点及其在组合化合物库的设计和优化中的作用,指出了这些方法的不足和局限性.最后,对化合物的成药性预测的应用前景和发展趋势进行了展望.