第十八届美国理论与应用力学大会总结

1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学

Study on Human Detection in a Static Image

静态图像中的人体检测技术在驾驶员辅助系统、人体运动捕捉、色情图片过滤以及虚拟视频等领域有重要的应用价值。人体形状的变化比较复杂，而且人体可能穿着各种颜色和各种风格的衣服，因此检测静态图像中的人体是一个非常困难的任务。本文针对该问题开展了研究工作，并取得了以下几个创新成果：尽管人体形状的变化非常复杂，但人体四肢的变化相对比较小。基于此，本文在第二章提出一种强调四肢组合结构的人体模型，并利用样本学习的方法获得这种人体模型对应的概率模型，以便定量地反映人体结构的变化。图像中包含的边缘信息是物体检测系统中一种重要的特征。本文在第三章提出一种基于图像的亮度变化以及颜色空间分布的彩色边缘检测算法。该算法以灰度边缘检测为基础，补充颜色变化导致的边缘，并消除那些位于纹理区域内部的点。该算法检测到的边缘可以反映物体的轮廓信息，因此可以通过边缘组织高效地检测图像中的人体目标。本文在第四章提出一种基于矩形拟合的人体检测算法。该方法以第二章定义的人体模型为基础，依据知觉组织原则将图像中的边缘信息组织为高层特征。算法首先由边缘点得到线段，继而拟合矩形。根据矩形集合搜索可能的肢体，并根据肢体搜索可能的侧影。最后寻找合理的侧影组合，以便检测人体。该算法可以有效地处理人体形状的变化。本文在第五章提出一种算法检测人脸和双臂所在的图像区域。该方法首先在YCbCr颜色空间检测可能为肤色的象素，利用连通性分析得到皮肤区域。依据皮肤区域的最小包围矩形的一长宽比，确定可能的人脸候选。利用图像的边缘信息定义皮肤区域之间的连通距离，并根据连通距离检测每个人脸矩形可能对应的左臂和右臂，如果它们满足一定的几何和拓扑关系，则检测到一个人体目标。该方法充分利用了肤色属性，因此检测结果更加符合人的视觉系统对图像的感知。本文在第六章介绍了另外一个工作，即多视点绘制的多边形模板法。为了充分利用透视投影的共性，该算法在预处理阶段为场景中的每个多边形建立多边形模板，每个多边形模板由一条轮廓路径和一组纹条组成，而纹条是用平行成像面的面切割多边形所得的直线段。成像时一，对多边形以纹条为单位进行绘制。通过利用模板中包含的可复用的信息，该算法有效地提高了成像速度。本文利用人体的几何、拓扑以及肤色属性，研究了静态图像中的人体检测问题，并在Windows 2000操作系统下，利用C++实现了一个人体检测系统，同时给出了一些实验结果。进一步改善后，本文的人体检测算法可以应用在驾驶员辅助系统、运动捕捉、图片过滤和虚拟视频等领域。The algorithm for human detection in a static image can be applied in many areas, such as driver assistance system, motion capture system, adult image filtering system and virtual video. However, as a human object may have various shapes and can be dressed in many different colors and styles, it is a challenging task to detect a human in a static image. In this paper, we outline some possible remedies in solving this problem, and the following contributions distinguish this dissertation from previous works: Although the shapes of humans can vary dramatically, the shape of limb is relatively simple. Based on the observation, we present a human model that emphasizes the shape of limbs, and we introduce a probability model for the human body to evaluate the variations of human shapes in chapter 2. Edge is an important image feature for object detection system, and we present a color edge detector based on the intensity variations and colors spatial distribution in chapter 3. Firstly, the algorithm detects gray edges and then further makes effort to find the color-texture edges. Finally, the detector removes the false edge pixels inside texture regions. The set of edge pixels detected by this algorithm is a useful cue for object's boundary, so it can be taken as an important feature for the human detection system. An algorithm of human detection is presented based on rectangle fitting in chapter 4. According to the principles of perceptual organization, the human detector takes edges as input, and then makes effort to obtain higher feature details step by step. The higher detail features include line segments, rectangles, limbs, OSBC (one-side body contour). Finally, we try to find the reasonable combinations among all the OSBCs to detect possible human objects. The algorithm can deal with the variations of human shapes effectively. An algorithm is presented to detect the combination of face and arms in chapter 5. The skin pixels are detected in the YCbCr space, and then the skin regions are determined according to the connectivity analysis. After that, face candidates are detected by the aspect ratio of the smallest bounding rectangles corresponding to the skin regions. The concept of connectivity distance is defined based on the edges of the original image. For each face candidate, its corresponding arms are detected in terms of the connectivity distance between the skin regions. If a combination of face and arms satisfies some geometric and topological constrains, it can be taken as a human object. As this algorithm makes use of skin colors, the detection results are more reliable. In chapter 6, we discuss another work that is an algorithm for rendering the same scene from multiple viewpoints, hi the pre-process, we define a splat for each polygon, and each splat is composed of a contour trace and a set of strips. After that, we can utilize the re-usable information contained in the splat to render each polygon. Compared with the traditional polygon scan-line algorithm, our new method can accelerate the rendering process effectively. hi this dissertation, we mainly study the algorithms for the human detection in a static image. A detection system is implemented in C++ under windows 2000 operating system, and some experiment results are presented. The algorithms may be applied in the driver assistance system, motion capture system, image filtering system and virtual video system in the future

基于图象的虚拟环境漫游技术中的一些图象处理问题的研究

虚拟现实是一种高度逼真地模拟人在自然环境中视、听、动等行为的人机交互技术。随着计算机交互手段和图形处理技术的不断提高，它已经在许多领域中得到了应用。但是随着场景复杂程度的不断提高，不仅使造型的工作量大为增加，同时也使得图形加速器难以实时地处理复杂的场景，造成系统的延迟，影响了虚拟现实技术的广泛应用。针对这个问题，人们提出了一种基于图象的绘制方法。与传统的基于图形的虚拟现实技术相比，该方法的优越性在于其生成图象的质量与场景的复杂性无关，因而不需要使用专门的硬件加速就能获得真实感很强的图象和实时的交互速度。本文的工作主要是围绕着基于图象的虚拟现实技术中的一些图象处理问题进行了研究。本文提出了两个算法：１）提出了一种基于塔形结构的颜色融合算法，并将该算法用于图象拼接，从而制作出了一些全景图。２）利用分块双三次Bezier插值C~1曲面的连续性和局部性，提出了一种基于Bezier曲面插值的图象放大方法。另外，本文在第一章给出的虚拟环境漫游时节点的组织与调度方法，并给出了所使用的数据结构。本文作者在WINDOWS NT的环境下开发了一套基于图象的虚拟环境漫游系统的制作工具，利用该工具完成了两个虚拟环境漫游系统：颐和园虚拟漫游系统和中科院软件所计算机科学实验室虚拟漫游系统。Virtual Reality(VR) is an advanced man-machine interface which allows the behaviors of the human being, such as viewing, listening and touching, to be conducted in a natural but virtual environment. With the development of man-machine interface and computer graphics techniques, VR has been applied in more and more fields. However most virtual reality systems still face some difficult problems. One problem is how to render very complex scenes in real time and another is how to generate photorealistic view of the scenes. They have limited the application of virtual reality. To solve these problems, a method of image-based rendering has been presented in recent years. In comparison with the customary graphics-based VR, the main advantage of image-based VR is, the rendering quality is independent of the scene complexity, so no special graphics engine is required in generating the realistic images for real time interaction. The main research work in this thesis focuses on solving some crucial problems on image processing related to the walkthrough of image-based virtual environment. Two algorithms are proposed in this aspect. Firstly, an improved algorithm is proposed and implemented for color blending, employed for image stitching in producing panoramic images. Secondly, by taking advantages of continuity and local property of piecewise bicubic Bezier interpolation surface, an efficient method of image zoom-in is designed and implemented. Besides, a mechanism in organizing and scheduling the panoramic nodes of a virtual environment has been also designed. A suite of toolkit in authoring image-based VR systems are also developed. By employment of the toolkit, two test examples of walkthrough systems are completed. One is for a part of the Summer Palace in Beijing, and another is for our research laboratory, the Lab. Of Computer Science of Institute of Software

Direct Production of Gasoline-Range Hydrocarbons from Carbon Dioxide over Iron-Based Multifunctional Catalysts

Direct Production of Gasoline-Range Hydrocarbons from Carbon Dioxide over Iron-Based Multifunctional Catalyst

polygon splatting for multiple viewpoint rendering

该文提出一种对场景进行多视点成像的方法.该方法首先为场景中的多边形生成多边形模板,一个多边形模板,包括一条轮廓路径和一组纹条,而一个纹条是平行成像面的一个平面与多边形相交的直线段.由于纹条相对于不同视点的透视投影的变化是线性的,因此,绘制多边形时可以基于模板逐个纹条地处理,而不必按照传统的扫描转换方法逐个点地处理,绘制速度可以提高很多.同时,与视点无关的光照和纹理可以预先计算并保存在模板中,以便在成像时利用基于图像绘制的技术来生成高质量的图像.该方法中,视点可以放置在三维空间的任意位置,并且在场景漫游时

芦笋叶绿素铜钠盐制备过程中提取工艺的研究

采用超声法对芦笋叶进行了叶绿素的提取并合成了叶绿素铜钠盐。结果表明,芦笋叶绿素的最佳提取工艺条件为：提取溶剂为80%丙酮与95%乙醇体积比1：4,提取时间60min,提取温度70℃,液固比10：1,超声功率160W。提取的叶绿素溶液,经过皂化、酸化、铜代、成盐等步骤制成叶绿素铜钠盐,得率（以鲜叶计）为0.18%,产品质量符合国家标准GB3262-1982

芦笋叶绿素铜钠盐制备过程中提取工艺的研究

采用超声法对芦笋叶进行了叶绿素的提取并合成了叶绿素铜钠盐。结果表明,芦笋叶绿素的最佳提取工艺条件为：提取溶剂为80%丙酮与95%乙醇体积比1：4,提取时间60min,提取温度70℃,液固比10：1,超声功率160W。提取的叶绿素溶液,经过皂化、酸化、铜代、成盐等步骤制成叶绿素铜钠盐,得率（以鲜叶计）为0.18%,产品质量符合国家标准GB3262-1982

信息科学部国际合作与交流项目实施情况调查综述

国际合作与交流是促进我国研发、提升技术创新能力的重要途径之一. 对国家自然科学基金委员会信息领域国际合作与交流项目从资助类别、实施情况、效果评价方式和存在的问题等方面进行综合分

芦笋叶绿素铜钠盐制备过程中提取工艺的研究

采用超声法对芦笋叶进行了叶绿素的提取并合成了叶绿素铜钠盐。结果表明,芦笋叶绿素的最佳提取工艺条件为:提取溶剂为80%丙酮与95%乙醇体积比1:4,提取时间60min,提取温度70℃,液固比10:1,超声功率160W。提取的叶绿素溶液,经过皂化、酸化、铜代、成盐等步骤制成叶绿素铜钠盐,得率(以鲜叶计)为0.18%,产品质量符合国家标准GB3262-1982

"半导体集成化芯片系统基础研究"重大研究计划结束综述

本文介绍了"半导体集成化芯片系统基础研究"重大研究计划立项背景、宗旨、总体科学目标、实施过程的基本情况以及取得的主要创新成果, 并分析了目前我国在该领域仍然存在的差距和问