3D model retrieval using principal plane analysis and dynamic programming

Three dimensional models play an important role in many applications; the problem is how to select the appropriate models from a 3D database rapidly and accurately. In recent years, a variety of shape representations, statistical methods, and geometric algorithms have been proposed for matching 3D shapes or models. In this paper, we propose a 3D shape representation scheme based on a combination of principal plane analysis and dynamic programming. The proposed 3D shape representation scheme consists of three steps. First, a 3D model is transformed into a 2D image by projecting the vertices of the model onto its principal plane. Second, the convex hall of the 2D shape of the model is further segmented into multiple disjoint triangles using dynamic programming. Finally, for each triangle, a projection score histogram and moments are extracted as the feature vectors for similarity searching. Experimental results showed the robustness of the proposed scheme, which resists translation, rotation, scaling, noise, and destructive attacks. The proposed 3D model retrieval method performs fairly well in retrieving models having similar characteristics from a database of 3D models.     

Proposed modification to the CIECAM02 colour appearance model to include the simultaneous contrast effects

A modified CIECAM02 colour appearance model, named CIECAM02‐m2, is proposed to enable CIECAM02 to predict the simultaneous contrast effect. The structure of the CIECAM02‐m2 is a development from CIECAM02, and contains two different procedures for modifying the reference white; one is for lightness and the other is for hue. The model was tested using a data set accumulated in this study and the LUTCHI data. The CV values for three colour attributes between predictions and experimental data were used to evaluate the accuracy of the model. The low CV values obtained show the performance of the CIECAM02‐m2 model to predict the simultaneous contrast effect satisfactorily. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 121 – 129, 2007     

巡航导弹机动地形相关系统

研究了一种适用于巡航导弹辅助导航的机动地形相关系统(MTCS)。介绍了 MTCS的工作原理、相关定位算法以及提高定位概率的技术途径,指出了系统设计中的关键技术。另外还讨论了 MTCS 的计算机运算,研究结论对地形辅助系统的设计有参考价值。     

Finding approximate matches in large lexicons

Approximate string matching is used for spelling correction and personal name matching. In this paper we show how to use string matching techniques in conjunction with lexicon indexes to find approximate matches in a large lexicon. We test several lexicon indexing techniques, including n-grams and permuted lexicons, and several string matching techniques, including string similarity measures and phonetic coding. We propose methods for combining these techniques, and show experimentally that these combinations yield good retrieval effectiveness while keeping index size and retrieval time low. Our experiments also suggest that, in contrast to previous claims, phonetic codings are markedly inferior to string distance measures, which are demonstrated to be suitable for both spelling correction and personal name matching.     

原子力显微术

本文首先介绍了原子力显微术的基本理论，其次讨论了原子力显微镜的结构原理，主要报导了一台我们研制的使用光学偏转法检测的原子力显微镜及仪器性能，仪器测试的结果表明我们这台原子力显微镜获得了原子分辨率，最后给出使用这台显微镜的首批实验结果。     

增力式夹具的设计与应用

增力式夹具结构紧凑，夹紧迅速可靠。它可以用较少的原动力获得较大的夹紧力，其增力倍数据实际须要同设计者调整。而且，若按机构自锁条件设计，该夹具夹紧之后，实现自锁。本文对该夹具结构做了介绍，并通过理论分析，指出增力系数和夹具自锁的设计条件。     

波谱匹配支持的遥感专题地物自适应提取

为贴合地物表现的多样性和复杂性,提出一种波谱匹配支持下的遥感影像专题地物自适应提取方法,经过专题地物端元选取、波谱匹配、影像自动分割、"整体-局部"的空间转换,以及局部针对性、精细化地迭代逼近等一系列相互衔接的算法,全面、准确地提取遥感影像上的专题地物。通过在ETM+影像上水体和裸地的提取实验,并与最大似然法和SVM分类结果比较,证明了该方法对多样性专题地物提取的有效性和普适性。     

基于梯度值的自适应窗口立体图像匹配算法

针对基于区域的立体图像匹配算法支持窗口难以选择,容易出现窗口过大或过小的问题,提出一种新的自适应窗口立体图像匹配算法。该算法利用Sobel梯度算子计算像素梯度值,并根据其梯度值动态地获取具有自适应的支持窗口,然后分别选择相似性测度函数SAD或NCC搜索最佳匹配点,获得视差图。此外,算法在窗口选择过程中进行优化,减少了计算量。实验结果表明,改进后的算法提高了匹配正确率且计算时间缩短了近5%。     

基于损失自注意力机制的立体匹配算法研究

针对现有的立体匹配算法在阴影、物体边缘和光照反射等区域匹配困难且存在大量错误结果的问题,设计了一种可拆卸的损失自注意力网络（loss self-attention net,LSAnet）查找图像中的匹配困难区域。LSAnet的网络各层相互稠密连接,应用了空洞卷积来扩大感受野,并以立体匹配算法生成的损失分布为标签,能够动态地进行有监督训练,最终生成匹配困难区域掩膜辅助立体匹配网络进行更好的优化;同时,改进了立体匹配网络中经典的特征匹配代价卷结构,降低了后续3D卷积的计算负荷,提高了匹配效率。实验结果表明,该算法相比于基准算法精度更高,并且可以提高算法对于匹配困难区域的鲁棒性。     

全面建设小康社会进程中黄河流域水资源利用效率时空演变分析

提升水资源利用效率,减轻水资源短缺对经济社会发展产生的约束,是实现水资源与经济社会和谐发展的有力支撑。尝试将DEA视窗分析方法应用于水资源利用效率研究,结合超效率DEA模型,探究黄河流域九省区在全面小康社会建设进程中水资源利用效率时空演变特征,在此基础上,通过Malmquist指数分解效率变动的内在原因,并引用空间匹配度计算方法,研究水资源利用效率与全面小康相对水平匹配程度。研究发现:九省区2012—2018年水资源利用效率总体呈增加趋势,水资源利用水平具有显著空间差异性;九省区水资源利用效率的提升主要得益于技术进步TC,制约水资源利用效率提升的主要因素是综合技术效率EC;水资源利用效率与全面小康相对水平的匹配程度呈现出较强的地区差异,部分省区两者动态协同性较差,其中,宁夏需要同时提升水资源利用水平和经济社会发展水平,陕西需要提升水资源利用水平,内蒙古需要提升经济社会发展水平。