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陈俊明 《测绘与空间地理信息》2014,(5):123-126
空间关联规则是空间数据挖掘(SDM)中的重要内容之一。由于空间数据的复杂性,传统的空间关联规则挖掘方法主要是将空间数据库变换为非空间数据库,通过挖掘算法挖掘空间关联规则。目前,Apriori算法是关联规则挖掘中使用最为普遍的算法,但是,由于该算法在关联规则提取过程中需要多次扫描数据库,并且产生冗余的候选项集,因此,在执行大型数据库的关联规则挖掘时,具有效率低下的缺陷。本文基于Apriori算法提出了基于布尔矩阵的空间关联规则挖掘算法,并以挖掘福建省厦门市土地覆盖现状与地形特征因子的空间关联关系作为试验案例,对比Apriori算法的提取结果与提取效率,结果表明:该算法不仅减少了扫描数据库的次数,而且减少了冗余候选项集的产生,提高了空间关联规则的提取效率。 相似文献
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针对传统空间关联规则挖掘对数据硬化分导致的"尖锐边界"问题,提出了一种顾及模糊属性的空间关联规则挖掘方法。该方法引入模糊集理论,将模糊空间属性通过隶属函数转化为隶属度表示的模糊数值,从而将其划分为模糊集合。然后使用改进的模糊关联规则挖掘算法扫描数据库,根据相应的支持度得到频繁项集,最终提取出关联规则。实验结果表明,该方法能够对带有模糊属性的空间数据进行关联规则挖掘,且在一定程度上提高了挖掘结果的兴趣度。 相似文献
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空间关联规则挖掘是空间数据挖掘的重要内容,文中给出了时序空间关联规则挖掘的相关概念、原理及实现(算法),研究了时序空间关联规则挖掘数据集的构造方法,提出通过空间实体关联关系和时间项转置方法将处于不同时刻的、相互独立的空间数据集进行重构,生成隐含了时序空间关联特征的挖掘数据集,进而可应用关联规则挖掘算法获取时序空间关联知识,初步进行了时序空间关联规则挖掘的应用研究。 相似文献
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《武汉大学学报(信息科学版)》2010,(9)
提出了带确定性决策项的关联规则挖掘算法。理论和实验分析表明,该算法与传统的关联规则挖掘算法相比,具有高效率。在实际中应用该挖掘算法,可以得到有意义的知识模式,为生化企业优化生产环境提供理论基础。 相似文献
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《测绘科学技术学报》2013,(3)
关联规则挖掘会产生大量的项集和规则,其中只有少部分是用户感兴趣和有价值的,其他大部分是冗余的或已知的。在已有的空间关联规则挖掘研究中,用户对数据库中存在的强制约束缺少考虑。本文分析了空间数据库中的已知空间依赖,发现已有的Apriori算法和闭频繁项集挖掘难以消除该空间依赖,为此提出了基于概念格方法的已知空间依赖剔除策略,包括概念格中每个闭频繁节点的产生子获得方法和利用概念格产生子实现最优频繁地理模式挖掘的方法,最后通过实验验证了概念格产生子方法的有效性和优越性。 相似文献
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一种Apriori的改进算法 总被引:17,自引:0,他引:17
提出了一种Apriori算法的改进算法 ,讨论了通过使用概率的方法估算任意数据项集同时出现的概率来求候选频繁项集的方法 ,并给出了相关算法。将本算法与Apriori算法产生的候选项集大小和扫描数据库次数进行了比较 ,该算法将关联规则挖掘的运行速度提高了一个数量级 ,非常适合挖掘数据库、长模式的关联规则。 相似文献
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利用叠置分析和面积计算实现空间关联规则挖掘 总被引:1,自引:0,他引:1
提出利用叠置分析和面积计算实现空间关联规则挖掘的算法I-Apriori及其改进算法FI-Apriori,这两种算法不依赖于空间数据的事务化,可以直接从矢量多边形图层中提取所有强关联规则.采用实际数据对两种算法进行了检验,验证了它们的可用性与有效性,并对挖掘所得空间关联规则的筛选和可视化方法进行了探讨. 相似文献
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采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的
污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体
污染变化曲线,得出污染物浓度随着远离上游而增加。 相似文献
12.
Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data 总被引:5,自引:0,他引:5
C. Bhuiyan R.P. Singh F.N. Kogan 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):289-302
The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw. 相似文献
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Piyoosh Rautela Ramesh Chandra Lakhera 《International Journal of Applied Earth Observation and Geoinformation》2000,2(3-4)
The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies. 相似文献
14.
ZHAN F. Benjamin 《地球空间信息科学学报》2011,(1)
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200... 相似文献
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GNSS系统及其技术的发展研究 总被引:3,自引:1,他引:2
阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议. 相似文献
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“4D”技术及其应用 总被引:13,自引:0,他引:13
介绍“4D”(即数字地面模型、数字正射影像、数字栅格地图和数字线划地图)系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。 相似文献
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《International Journal of Digital Earth》2013,6(1):66-87
Abstract Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised. 相似文献
18.
Toward seamless indoor-outdoor applications: Developing stakeholder-oriented location-based services
Kohei OGAWA Edward VERBREE Sisi ZLATANOVA Naohiko KOHTAKE Yoshiaki OHKAMI 《地球空间信息科学学报》2011,14(2):109-118
Location-Based Services (LBS),an emerging new business based on smartphone and mobile networks,are becoming more and more popular.Most of these LBSs,however,only offer non-seamless indoor/outdoor applications and simple applications without giving stakeholders the chance to play an active role.Our specific aim is to solve these issues.This paper presents concepts to solve these issues by expanding the Open Location Services Interface Standard (OpenLS) to allow seamless indoor/outdoor positioning and to extend the content of the services to include information recommended by stakeholders. 相似文献
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地理数据库的关系模型及其实现 总被引:1,自引:0,他引:1
本文从以图论观点分析地理实体入手,系统阐述了地理数据库关系模型的设计法和过程。作者于1984年4~9月间在微型机上设计建立了关系型地理数据库的实方验系统(RGDB)。该系统采用了本文提出的关系模型,采用了可动态扩库的子库组合结构,这种结构具有灵活性和提高空间利用率的优点。RGDB含有多种功能的数据操作命令,除了具有一般检索功能外,还能进行“开窗”选取和十分“自由”的映象选取。本文对RGDB系统的主要性能和实现途径作了扼要介绍。 相似文献