风云三号C卫星星载GPS/BDS实时定轨分析

随着北斗卫星导航系统(BeiDou navigation satellite system,BDS)的建设与运行,低轨卫星开始搭载GPS/BDS双系统接收机以实现卫星轨道确定.利用风云三号C(FengYun-3C,FY3C)卫星星载GPS/BDS双频伪距与载波相位观测数据,设置4种仿真试验方案,分别进行星载GPS/BDS在轨实时定轨数据处理,重点进行BDS观测数据对伪距实时定轨和载波相位实时定轨的精度影响分析和算法耗时分析.结果表明,采用伪距观测值,可获得1.0m的位置精度和1.0 mm/s的速度精度;采用载波相位观测值,可获得0.3 m的位置精度和0.3 mm/s的速度精度,且引入BDS观测值后,伪距实时定轨精度降低,相位实时定轨精度有所改善.     

中国煤层气勘探开发技术研究进展

我国煤层气勘探开发工作走过了十多年的探索历程,大致可以分为三个阶段：技术引进阶段、勘探评价阶段、开发试验及探索研究阶段。目前,制约煤层气商业开发的瓶颈技术问题在于寻找煤层气富集高渗区、提高煤层气产能的开发工艺技术。本文将着重介绍我国在煤层气勘探开发技术方面的研究进展,主要包括煤层气资源评价和区块优选评价技术、钻井技术、完井工艺技术、压裂工艺技术、注CO2增产技术、煤层气地球物理探测技术、煤层气井抽放技术、煤层气生产和评价技术等等。同时,提出了今后我国煤层气勘探开发技术存在的问题和发展趋势。     

鄂尔多斯盆地煤层气资源及开发潜力分析

鄂尔多斯盆地含石炭—二叠纪和侏罗纪两套含煤岩系,煤层发育,厚度大。石炭—二叠纪煤层煤级高,为气煤—无烟煤,含气量高,为2.46～23.25m3/t;侏罗纪煤层煤级低,以长焰煤为主,含气量低,为0.01～6.29m3/t。全盆地煤层气总资源量为107235.7×108m3,占全国煤层气总资源量的1/3,煤层气勘探开发潜力巨大。煤层气开发最有利区块包括鄂尔多斯东缘的河东煤田和陕北石炭—二叠纪煤田、鄂尔多斯南缘的渭北煤田,有利区块包括鄂尔多斯南部黄陇煤田、鄂尔多斯西部庆阳含煤区和灵武-盐池-韦州含煤区。可见煤层气最有利和有利区块主要沿盆缘分布。鄂尔多斯盆地东缘、渭北煤田、黄陇煤田是目前煤层气勘探的热点地区,勘探成果预示出良好的开发前景。     

Prediction of Reservoir Temperatures Using Hydrogeochemical Data,Western Anatolia Geothermal Systems (Turkey): A Machine Learning Approach

Natural Resources Research - Geothermal fluids can be used for purposes such as power production, district heating/cooling, agriculture, and industrial and thermal tourism. Although using...     

Monitoring Koyulhisar landslide using rapid static GPS: a strategy to remove biases from vertical velocities

GPS is frequently used in the monitoring of natural hazards and other geophysical phenomena. Landslide monitoring is one such area in which various GPS methods are tested and various systematic error sources are introduced. In previous studies, one error source introduced on rapid static GPS was the effect of large height differences in GPS positions. In this study, we further investigate how GPS velocities/slip rates are affected by large station height differences when rapid static surveying is used. In order to demonstrate the influences, we used static GPS measurements from the Koyulhisar landslide in central Turkey. Comparison of rapid static GPS solutions with static GPS solutions using BERNESE 5.0 indicates that systematic biases occur in the estimated rapid static GPS deformation rates when the station height difference is large between baseline points. The effect is more significant on the vertical component, whereas it is negligible on the horizontal components. When reducing the height difference between the reference station and the rover stations, rapid static solutions from 15-min sessions show high correlation and similar deformation rates with static positioning solutions.     

Evaluation of image fusion methods using PALSAR,RADARSAT-1 and SPOT images for land use/ land cover classification

This research aimed to explore the fusion of multispectral optical SPOT data with microwave L-band ALOS PALSAR and C-band RADARSAT-1 data for a detailed land use/cover mapping to find out the individual contributions of different wavelengths. Many fusion approaches have been implemented and analyzed for various applications using different remote sensing images. However, the fusion methods have conflict in the context of land use/cover (LULC) mapping using optical and synthetic aperture radar (SAR) images together. In this research two SAR images ALOS PALSAR and RADARSAT-1 were fused with SPOT data. Although, both SAR data were gathered in same polarization, and had same ground resolution, they differ in wavelengths. As different data fusion methods, intensity hue saturation (IHS), principal component analysis, discrete wavelet transformation, high pass frequency (HPF), and Ehlers, were performed and compared. For the quality analyses, visual interpretation was applied as a qualitative analysis, and spectral quality metrics of the fused images, such as correlation coefficient (CC) and universal image quality index (UIQI) were applied as a quantitative analysis. Furthermore, multispectral SPOT image and SAR fused images were classified with Maximum Likelihood Classification (MLC) method for the evaluation of their efficiencies. Ehlers gave the best score in the quality analysis and for the accuracy of LULC on LULC mapping of PALSAR and RADARSAT images. The results showed that the HPF method is in the second place with an increased thematic mapping accuracy. IHS had the worse results in all analyses. Overall, it is indicated that Ehlers method is a powerful technique to improve the LULC classification.     

Monitoring of coal mining subsidence in peri-urban area of Zonguldak city (NW Turkey) with persistent scatterer interferometry using ALOS-PALSAR

This paper presents the results of spatiotemporal monitoring of surface subsidence over a mining area in Zonguldak Province of Turkey using Synthetic Aperture Radar (SAR) data, providing maps of subsidence rates in the radar line of sight direction. A total of 18 SAR images, acquired between January 2007 and June 2010 by the Japanese Advanced Land Observing Satellite, have been used to map the surface displacements using the Persistent Scatterer Interferometry technique. The use of Phased Array Type L-band Synthetic Aperture Radar data has proved useful for avoiding signal decorrelation and estimating surface deformation in the heavily vegetated study region. The technique enables the monitoring of continuous small displacements over a large area. Our findings present that many Persistent Scatterers were located on the vegetation cover. The results reveal areas of ground surface subsidence up to 44 mm/year that are well correlated with the underground coal mining galleries particularly in the Gelik region where the Karadon mining galleries are present.