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测绘工作是国民经济和社会发展的一项前期性、基础性工作。测绘业是国家重要的信息产业。测绘向社会提供测绘产品和测绘技术服务。我国改革开放二十多年来,测绘产品逐步商品化,测绘单位逐步走向市场, 相似文献
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一、前言
随着市场经济不断发展与完善,各个行业与部门对管理水平要求也越来越高,培养高素质的各级管理干部队伍已成为社会主义现代化建设事业迫切要求。提高干部素质,要牢固树立正确的世界观、人生观与价值观,全面提高干部政治素质、理论素质和专业技术水平。 相似文献
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随着改革开放的深入发展,经济结构的调整,变计划经济为市场经济,基本上所有的测绘单位也由指令性生产、稳拿工资、津贴等,变为到社会上找任务、找饭吃的局面。因此整个测绘行业中许多单位感到任务不足,经济困难,千方百计找活干,形成测绘市场竞争激烈, 相似文献
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R. P. Singh V. K. Dadhwal K. P. Singh R. R. Navalgund R. Sharma G. D. Bairagi S. A. Raza N. K. Sharma 《Journal of the Indian Society of Remote Sensing》2005,33(2):307-313
This paper reports estimation of the Leaf Area Index (LAI) of wheat crop from IRS-LISS-III data using Price (1993) approach.
Empirical approach for LAI estimation with different NDVI estimation procedures viz. radiance, apparent reflectance and dark
object subtraction (DOS) based atmospheric correction were also evaluated. Validation of LAI retrieval and NDVI normalizations
were carried out using field level measurements of crop LAI and spectral property using canopy analyzer and spectro-radiometer,
respectively over selected fields in Bhopal District, Madhya Pradesh. It was observed that empirical relations are sensitive
to the NDVI estimation approach and DOS method performed better as compared to other two approaches. It was also observed
that LAI estimation from Price algorithm is sensitive to the crop attenuation coefficients. Crop specific attenuation coefficients
reported in literature for Indian cultivars gave higher accuracy. The root mean square (RMS) error of 0.77 for LAI estimation
was achieved using above described approach. 相似文献
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House prices fluctuate spatiotemporally and when influential changes from a region happen, the effects spread out in space over time. Although many studies have introduced various models to explain the spatiotemporal dynamics in housing markets, it is always challenging to consider both dimensions in a model. Some recent studies have identified spatiotemporal interactions of house prices by combining spatial and temporal models via spatial vector autoregression. The approach, however, assumes spatial homogeneity of the variables due to insufficient degrees of freedom. Since the housing market is generally conceived as heterogeneous, we suggest an alternative model of the spatial vector autoregressive Lasso without the homogeneity assumption. As an empirical example, we examine the spatiotemporal interaction between house sales price and rent in Seoul, Korea. The results show that rent for apartments in Gangnam‐gu, a socioeconomic core of Seoul, has positive impacts on rent for apartments in surrounding suburbs rather than their sales price. Moreover, the suggested model outperforms the classical method in terms of explanation, prediction, and autocorrelation of residuals. This research is expected to provide a methodological guide to explore the interaction between house sales price and rent, and insights into the spatiotemporal dynamics of the housing market in Seoul. 相似文献
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Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements,
such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach
can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even
when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the lever
arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined lever arm by direct measurement
is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose
a new hybrid derivative-free extended Kalman filter for the estimation of the unknown lever arm in tightly coupled GPS/INS
integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement
propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years
is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new
Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new lever
arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate
the unknown lever arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test
results confirm the effectiveness of the new method. 相似文献
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土地利用监测,是根据实时更新的土地利用信息,全面地检测全市内的土地利用状况,便于人们更快的了解信息;土地利用预测,是根据近十年来的土地利用数据,使用科学的方法,预测土地行业的发展趋势,帮助政府及个人决策。本文利用ArcIMS技术构建了一套土地市场监测的WebGIS系统。从工程人员在服务器端的具体实施方法和客户端的最终成果两方面着重介绍了WebGIS在北京市国土资源局土地市场监测预测中的应用。本系统具有操作简单快捷、可视化、多时态、多模式显示、多用户同时使用等特点,较好的解决了用户在土地监测中出现的问题。 相似文献
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我国卫星导航应用市场分析 总被引:2,自引:0,他引:2
分析了中国卫星导航定位产业特征,并用波特五力分析模型对卫星导航定位产业吸引力进行了分析,得出该产业是颇具吸引力的朝阳产业,该产业中的利益各方正处于从无序到有序的发展过程中的结论;指出了制约产业发展的三大问题和两大发展方向. 相似文献
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Gravity-field improvement in the Mediterranean Sea by estimating the bottom topography using collocation 总被引:4,自引:0,他引:4
The contribution of bathymetry to the prediction of quantities related to the gravity field (e.g., gravity anomalies, geoid
heights) is discussed in an extended test area of the central Mediterranean Sea. Sea gravity anomalies and a priori statistical
characteristics of depths are used in a least-squares collocation procedure in order to produce new depths, giving a better
smoothing of the gravity field when using a remove-restore procedure. The effect of the bottom topography on gravity-field
modeling is studied using both the original and the new depths through a residual terrain modeling reduction. The numerical
tests show a considerable smoothing of the sea gravity anomalies and the available altimeter heights when the new depth information
is taken into account according to the covariance analysis performed. Moreover, geoid heights are computed by combining the
sea gravity anomalies either with the original depths or with the new ones, using as a reference surface the OSU91A geopotential
model. Comparing the computed geoid heights with adjusted altimeter sea-surface heights (SSHs), better results are obtained
when subtracting the attraction of the new depth information. Similar results are obtained when predicting gravity anomalies
from altimeter SSHs where the terrain effect on altimetry is based on the new bottom topography.
Received: 10 September 1996 / Accepted: 4 August 1997 相似文献
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兰州市商品住宅价格的空间分异规律 总被引:1,自引:0,他引:1
针对住宅价格在城市空间中的分布规律问题,该文以兰州市主城区2015年在售的187个商品住宅样本均价为基本数据,运用空间自相关法对兰州市住宅价格的空间异质性和集聚性进行分析,并利用趋势面分析和空间反距离权重插值法对住宅价格的空间分布格局进行研究。结果表明:兰州市住宅价格总体上呈显著的空间正自相关性,少数地区存在差异性;住宅价格发展不平衡,价格"东高西低";住宅价格由各区行政中心向四周逐级递减,呈多极核分布特征;价格等值线"东密西疏",住宅价格变化幅度空间差异较大。分析发现,区位条件、交通条件及居住环境是影响兰州市商品住宅价格的主要因素。 相似文献