道路网信息投影匹配方法研究     

郭黎  李宏伟  张泽建  张斌 《武汉大学学报(信息科学版)》2013,(9):1113-1117

针对道路网线要素特点,提出了基于投影的道路网信息几何匹配方法。根据线段斜率,对线段进行投影、分割,提取线要素特征点,将复杂的道路网匹配转化为特征点匹配,可解决复杂的多对多匹配。通过渐进式的匹配策略,逐步、快速缩小匹配范围,提高了匹配效率。通过实验合理地调整匹配阈值,减少漏匹配与误匹配,提高整体匹配准确率。结果表明,本算法效率高,可靠性好,符合应用需求。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987111000879     

Weihua Ao  Wenhui Huang  Chengmin Weng  Xiuling Xiao  Dameng Liu  Xiuyi Tang  Ping Chen  Zhigen Zhao  Huan Wan  Robert B. Finkelman 《地学前缘(英文版)》2012,3(1):85-95

Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin,northwestern China.The huge reserves of this high quality coal have a high commercial value.We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas.The results show that the Jurassic coals in the Ordos Basin have special penological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system.These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers.After burial,the peat continued to undergo oxidizing conditions,this process generated extensive higher inertinile contents in the coals and the vitrinite components were altered to semi-vitrinite.The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal,dull coal,semilustrous and lustrous coal.The proportions of semi-dull coal and dull coal are higher in the basin margins,especially in the area near the northern margin.The numbers of semilustrous and lustrous coals increase southwards and towards the central basin.This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components.Another observation is that in the Ordos" coal sequences,especially in the lower part,some sandstone beds are thick,up to 20 m with a coarse grain size.The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure.The fusinite structure is clear and well preserved.After burial,the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology.The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation,circulation and connection to the coal.So coal components remain in an oxidation environment for a long time.Conversely,in the basin center,lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment.As a result,abundant gelatification occurred and the vitrinite content increased.Exinite often accumulated in a specific position in the coal bed.Although the average exinite content is not high on the whole,it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated,especially the amorphous bituminous fluid and its importance is emphasized here.The reason is that the fluid flows easily into fusinite which has strong rigidity,or flows into some fissures,where it is commonly neglected.  相似文献   

Modeling bioavailable phosphorus via other phosphorus fractions in sediment cores from Jiulongkou Lake, China   总被引：1，自引：0，他引：1  

Ling Liu  Ying Zhang  Aris Efting  Tadd Barrow  Bao Qian  Zejian Fang 《Environmental Earth Sciences》2012,65(3):945-956

Bioavailable phosphorus (BAP) plays an important role in phosphorus (P) release from lake and river sediments, as well as serves as an indicator for the potential P-release risk in sediment. Developing a feasible model which could predict BAP via other P fractions is needed for the lakes and reservoirs without regular BAP monitoring. The algal available P (AAP), NaHCO₃ extractable P (Olsen-P), water soluble P (WSP) and readily desorption P (RDP) are four fractions of BAP. The vertical and spatial distributions of BAP fractions of three sediment cores from Jiulongkou Lake were analyzed. In addition, the P fractions, including total P (TP), organic P (OP), inorganic P (IP), non-apatite inorganic P (NAIP), and apatite P (AP) were measured to develop a model for predicting BAP. The model for each BAP fraction was developed based on datasets from Jiulongkou Lake and validated by the datasets collected from Wujin and Wugong Lake. The results showed that all of the four BAP fractions decreased with depth, along the direction of contaminant transport. Their rank order was AAP > Olsen-P > WSP > RDP in all samples. The concentration of BAP was affected by the anthropogenic input and aquatic macrophyte growth. Each of the four BAP fractions could be simulated by different P fractions: both AAP and Olsen-P were expressed by NAIP and OP, WSP had a significant relationship with OP, and RDP had significant relationship with IP. NAIP and OP were the major sources of the BAP fraction. The simulated results in two other lakes further illustrated that this model could be used to successfully predict the BAP concentrations in lakes in the study area, and holds promise for predicting the BAP levels in other lakes and reservoirs as well.  相似文献   

非线性地球化学矿化元素组合求异方法在西藏洞噶普矿区的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

柳炳利  郭科  王维  敖东  武菊 《地学前缘》2012,19(2):256-265

复杂的地质作用和控制因素常常使得地球化学元素的分布特征呈非线性,传统的线性模型在处理元素非线性分布具有一定的局限性和不适应性。文中以研究地球化学矿化元素组合为主线,应用aiNet网络模型(带权的不完全连接网络)对地球化学数据做预处理,应用FastICA算法(快速定点独立分量分析)求取矿化元素组合,应用分形含量面积法圈定元素异常下限,应用分形含量梯度法确定元素异常浓集分带,形成了一套地球化学矿化元素组合求异的非线性方法体系,并在西藏洞噶普矿区1∶1万土壤地球化学测量资料的应用中取得了良好的效果。  相似文献   

京承高速公路工程施工测量     

贾国香  敖学明 《现代测绘》2007,30(5):16-18

本工程为北京市京承高速公路（三环路至四环路段）工程，南起北京东北三环路太阳宫桥，向北经土城北路及规划中的曹慧路，止于北京市东北四环路望和桥，全长约为2km。本文详细介绍了该道路工程的施工测量放线过程，以及施工测量中一些常用的校核方法  相似文献   

中关村科技软件园市政道路工程施工测量     

敖学明  贾国香 《现代测绘》2007,30(4):24-25

中关村科技园区是北京市重点工程.软件园区是科技园建设总体规划中的重要组成部分.该工程中有4条外部市政道路工程,6条内部市政道路工程,其中有11条圆曲线,道路交叉比较繁杂,文中详细介绍了道路工程的施工测量放线过程,以及施工测量中一些常用的校核方法和一般圆曲线计算.  相似文献   

广州白云机场低能见度气候特征   总被引：4，自引：0，他引：4       下载免费PDF全文

张美平  敖淑珍 《气象科技》2003,31(3):163-166

利用广州白云机场1970～2000年逐时能见度观测资料，对白云机场低能见度的气候特征进行统计分析。结果表明：小于等于1km的低能见度有明显的8年周期变化，小于等于0．8kin和0．55km的低能见度主要振荡周期是6～10年；自20世纪70年代出现能见度小于等于1km的日数有逐年上升趋势，其中90年代出现的日数明显偏多，80年代相对偏少；低能见度有明显的季节变化和日变化特征；低能见度平均出现次数与持续时间明显成反比；造成低能见度障碍的天气现象仅有雾和雨。  相似文献   

广东石灰岩地区的任豆群落   总被引：4，自引：0，他引：4  

敖惠修  何道泉 《热带地理》1997,17(3):275-282

本文对任豆群落的分布及生境特点，主要种群的生物不特性，其种类组成，外貌，结构，动态进行了分析，将其分为三个群落类型加以介绍，并提出开发利用与保护意义。  相似文献   

用X射线荧光方法测定薄层、镀层和涂层厚度     

敖奇  曹利国  丁益民 《物探化探计算技术》1996,(S5)

本文提出用特征 X射线的发射和吸收来测定薄层或表面涂层的厚度。从理论上解决了最佳能量的选择问题 ,使薄层厚度测定的检出下限大幅度优化。并通过实践证明了方法的可靠性和实用性  相似文献   

香根草在土壤改良和水土保持中的作用   总被引：22，自引：0，他引：22  

夏汉平  敖惠修  何道泉  刘世忠  陈龙江 《热带地理》1996,(3)

香根草作为一种理想的水土保持植物具有许多优良特性，目前正在热带和亚热带地区广泛推广种植。本文通过盆栽和大田两方面试验观测了香根草在土壤改良和水土保持中的作用。结果表明，种植香根草后可使强酸性土壤的可交换性铝含量下降，并使土壤ｐＨ值、有机质、全氮、速效氮和钾以及总孔隙度等都有不同程度的增加。与对照区相比，香根草区的径流量和土壤侵蚀量分别下降了６０％和９３％，而土壤含水量上升４％～４２％不等。香根草还可较好地改善果园小气候，使果园生态系统内的士温、气温和空气湿度等都朝着有利于果树生长发育的方向变化。  相似文献