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时变参数PGM(1, 1)变形预测模型及其应用 总被引：7，自引：1，他引：7
汪孔政 《武汉大学学报(信息科学版)》2005,30(5):456-459
在GM(1，1)模型的基础上，考虑参数随时间的变化，用多项式逼近模型参数，同时针对GM(1，1)模型背景值取值方法的不足，引入背景值最佳生成系数，建立了时变参数PGM(1，1)变形预测模型。多项式中的待定系数采用最小二乘法确定，背景值最佳生成系数采用搜索法确定。实例计算表明，时变参数PGM(1，1)变形预测模型具有较高的模拟精度和预测精度，适合用于变形体的变形预测。 相似文献
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针对大坝变形预测中非平稳性且含噪声的数据处理问题,该文提出一种基于剔除含噪声信号的大坝变形傅里叶(Fourier)预测新算法。首先利用经验模态分解(EMD)法将变形时间序列分解成具有不同尺度特征的固有模态函数(IMF)分量,并计算出各分量与原始信号的相关系数;然后根据相关系数剔除含噪声的IMF分量,并采用游程判定法对剩余的波动程度相似或相同的分量进行信号重构;最后利用傅里叶函数对重构后的分量进行曲线拟合,并据此构建大坝变形预测模型,对出现的模型系数采用最小二乘算法求解。经算例验证,并与GM(1,1)、BP神经网络和傅里叶模型对比分析,结果表明该文算法预测精度较高,可用于大坝的变形预测。 相似文献
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为了克服建筑物变形预测中单一模型预测精度差、不稳定的问题,本文融合了适应性强、互补性好的自回归滑动模型、灰色模型和三次指数平滑法三种模型,基于误差平方和最小准则,采用滚动时间域的方式构建了非负变权组合预测模型。工程应用表明:非负变权组合预测模型的预测精度、可靠性优于三种单一预测模型、方差倒数组合预测模型以及等权组合预测模型。研究成果对建筑物沉降预测具有较好的参考价值。 相似文献
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文章讨论了灰色预测模型和半参数模型,针对经典最小二乘在解算GM(1,1)模型待识别向量时存在的模型误差,采用将模型误差当作非参数信号的补偿最小二乘法进行数据处理.根据矿区变形观测特点,简要说明了正规矩阵R和平滑因子α的选取,并结合淮南市朱集矿地表移动观测站的实测数据对改正模型进行检验分析,结果表明:该方法可有效地削弱模型系统误差影响,提高预测模型精度. 相似文献
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从挖掘边坡变形特性出发,提出一种基于经验模态分解(EMD)和遗传小波神经网络(GA-WNN)法的新型边坡变形预测模型。该模型首先对边坡变形序列进行EMD分解,有效分离出不同尺度特征的子序列;其次基于相空间重构挖掘各子序列的特性,以避免预测模型输入维数选取的随意性;然后采用遗传算法优化小波神经网络的权值和阈值,进而对各子序列建立预测模型;最后叠加各子序列预测值得到边坡预测结果。经过了算例计算,并与SVM和GA-WNN对比分析。结果表明:该模型具有较强的非线性拟合和自适应能力;在一定程度上保证较优的局部预测值和较好的全局预测精度,均方根误差为0.68 mm;在边坡变形预测中具有一定的实用意义。 相似文献
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为了确保建筑物在建设过程中的安全,需要准确掌握建筑物基坑及周边的变形情况。针对建筑物基坑沉降变形预测问题,本文对单一的GM(1.1)模型与BP神经网络模型进行优化并构建组合预测模型。优化组合模型一方面解决了单一预测模型稳定性差、预测精度低的问题,另一方面提高了预测模型的适用性。将本文提出的组合预测模型应用于某在建建筑物基坑沉降变形预测中,结果表明,相较于单一的GM(1.1)模型与BP神经网络模型,本文提出的优化组合预测模型的预测精度与稳定性更高,证明了组合预测模型在建筑物基坑类沉降预测中的可靠性。 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
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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
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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
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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