关于《模式识别之重心法则及其在地图制图中运用一例》一文的一点注记     

冯可君  徐扬  欧百鸣 《武汉大学学报(信息科学版)》1990,(4)

本文对重心法则给出了一个扩展,使该法则的运用由综合指标到了全部指标,并证明了 I_G~((1))=I_G~((2))。  相似文献   

On the echo interference in sound backscattering by densely aggregated targets     

Gorska  Natalia; Chu  Dezhang 《ICES Journal of Marine Science》2005,62(4):771-778

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球形标靶的固定式扫描大点云自动定向方法   总被引：1，自引：0，他引：1  

姚吉利  马宁  贾象阳  徐广鹏  谢建春 《测绘学报》2015,44(4):431-437

根据目前地面激光扫描数据获取速度快、数据量大、测量距离远、专用特殊材料制作的标靶识别距离近、点云定向数据处理相对滞后、自动化程度低、不能适应远距离地形测量的现状,提出了从大点云中(每站1亿点以上)自动探测远距离标靶的点云定向方法。该方法首先根据标靶控制点的工程测量坐标信息,搜索到标靶所在点云环,然后对各点云环进行扇形分区,快速探测标靶,获取标靶中心扫描坐标,最后平差计算扫描仪位置参数和姿态参数,实现点云坐标到工程测量坐标的转换。该方法在普通配置的计算机上得到实现,并成功用于远距离山区地形测量,其中定向标靶半径0.162m,标靶到扫描站距离在180~700m之间。  相似文献   

压缩感知窄带自旋目标雷达成像     

王保平  方阳  孙超  谭歆 《遥感学报》2015,19(2):254-262

对于高速自旋目标而言,为了获得聚焦效果良好的图像,通常要求雷达系统具有较高的脉冲重复频率(PRF)。当PRF不满足采样要求时,雷达接收到的通常是方位欠采样的回波数据,从而影响目标识别。本文根据压缩感知理论,结合自旋目标回波信号稀疏性的特点,建立方位欠采样的成像模型,并提出了基于压缩采样匹配追踪的窄带雷达高速自旋目标成像算法。该算法在对信号进行重构迭代中,采用回退策略,并结合回波信号稀疏性的具体参数,选取最优的支撑集,提高了算法的重构质量。仿真实验表明新算法在回波欠采样的情况下能很好地重构图像,尤其是在低信噪比的情况下。采用"误选数"和"均方误差"两个指标对CoSaMP算法重建信号的性能进行评价,结果表明该算法受雷达PRF和信噪比SNR的影响较小,算法稳定性好。  相似文献   

The Digital Versatile Disc as a Learning Support Medium in the Teaching and Learning of Map Work     

《The Journal of geography》2012,111(4-5):131-141

Abstract

This article describes the results of a study where the digital versatile disc (DVD) was used as a variant of Information and Communication Technology (ICT) in order to aid in the teaching and learning of map work in geography at secondary school level. A group of grade 10 learners of a previously disadvantaged school in South Africa comprised the target group for the project. A case study was conducted and data was gathered on the implementation of the DVD and the learners' perceptions thereof. Qualitative analysis techniques such as field notes, observation, interviews with the learners, and questionnaires were used to analyze the effectiveness of the implementation of the DVD as well as the learners' perceptions regarding the use of the DVD in geography education. The results of the study indicated that the geography learners demonstrated positive attitudes towards the implementation of the DVD as a learning support medium. To determine the contribution of the DVD project towards the achieved results of the learners in map work, both the experimental and control groups participated in a pre- and post-test at the beginning and conclusion of the project. Effect size was used to determine the significance of the differences between the two groups and indicates a strong practical significance regarding the contribution of the DVD project towards the achieved test results of the learners.  相似文献   

The feasibility and utility of a paleolimnology/paleoclimate data cooperative for North America   总被引：1，自引：0，他引：1  

T. J. Sullivan  D. F. Charles 《Journal of Paleolimnology》1994,10(3):265-273

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建设一流山地研究所的战略构想——写在成都山地所成立40周年之际     

邓伟  程根伟 《山地学报》2006,24(5):513-517

成都山地所走过了40年的发展历程，现在已经成为在山地灾害防治和山地环境保护方面的国家级研究机构。进入21世纪以来，山地所面临新的发展机遇和挑战，即如何更好地满足国家重大战略需求，更准确地把握世界科技前沿，不断地推动一流山地研究所的建设。其核心与关键就是要造就一支高水平的科研队伍，持续提升全所的创新能力，不断为山区可持续发展做出基础性、战略性和前瞻性科技贡献。本文是基于知识创新工程三期学科发展规划主要框架而成，提出了研究所学科发展的目标及基本举措。  相似文献   

Practical Influences of Geometric and Radiometric Image Quality Provided By Different Digital Camera Systems   总被引：1，自引：0，他引：1  

S. Robson  & M. R. Shortis 《The Photogrammetric Record》1998,16(92):225-248

Imaging systems founded on current digital camera technology are finding widespread use in high precision measurement applications. A single digital CCD camera, or an array of such cameras, equipped with ring lighting equipment is commonly used to acquire imagery of high contrast retroreflective targets placed on the object at discrete locations to signalize points of interest. The precise and accurate measurement of each imaged target location is a fundamental requirement if suitable measurement tolerances are to be obtained. Whilst such systems are undoubtedly capable of producing excellent results, the practical effects of target image quality on the photogrammetric measurement process is in need of careful consideration. This paper revisits some fundamentals of the optical imaging of retrotargets and investigates some abilities of a range of digital camera systems to provide images of retrotargets that are appropriate to the measurement process. Some experimental results are presented including the imaging of planar arrays of differing sized retrotargets at differing angles and exposures and a series of network analyses in which the level of target image intensity has been varied systematically.  相似文献   

协作空间推演探讨     

刘纪平  范荣双  王亮  张福浩  朱翊  石丽红 《测绘科学》2003,28(3):20-22

介绍了协作空间推演的基本概念和任务,对其体系结构进行了分析,提出了基于Client/Server结构的协作空间推演关键技术,如多用户方案生成与修改、在线用户状态管理、数据通讯模式及其实现和方案演播等,对未来需要开展的工作进行的展望。  相似文献   

“一带一路”建设背景下中国区域空间响应差异及形成机制     

车冰清  孙东琪  朱传耿 《世界地理研究》2021,30(5):903-912

运用媒体报道的国家间合作事件大数据,构建国内区域参与“一带一路”建设的响应指数模型、合作流量模型和影响因素回归模型,分析中国国内区域主动与沿线国家开展合作的空间异质性,定量刻画合作流量（空间交互）的格局特征,并剖析响应差异形成的影响因素。研究发现：①2010—2019年响应指数变化呈现出普遍较快增长的态势。省域单元响应指数的空间差异较小,而市域单元响应指数的空间差异大,反映出明显的大尺度均衡化、小尺度集聚化的尺度效应。②国内区域与沿线国家的首位合作流量呈现地理临近性特征,东部沿海省份与东南亚、西亚及中东合作联系密切,而边境省份则具有较明显的边境贸易特征。合作流量网络的区位依赖特性突出,流量网络结构不断复杂,小流量流线始终占据多数,大流量、长距离流线数量逐年增加,辐射范围显著扩大。③经济规模、对外投资水平、开放程度以及陆路交通可达性,对国内区域响应“一带一路”建设具有明显的积极推动作用,国家政策的区域效应逐渐体现。  相似文献