基于GPS的“雪龙”船冲击式破冰模式识别研究          下载免费PDF全文

桂大伟  庞小平沈权 汪大立张洁  艾松涛 《极地研究》2017,29(3):414-419

"雪龙"号破冰船是我国目前唯一的极地考察船,破冰航行是极地船舶的重要特征之一。以"雪龙"号破冰船的GPS数据为基础,通过建立模型算法识别冲击式破冰这一特殊的航行状态,在整个中国第28次南极考察航次的数据分析中,整体识别率超过86.1%,识别正确率达到98%以上。利用此算法,在中国第27次南极考察航次的破冰识别率也超过85%,识别正确率达到93.5%。雪龙船两个航次实测GPS数据验证了本文算法的可用性,而破冰识别统计结果表明,不同航次的破冰模式具有较大的差异。  相似文献   

基于ECMWF集合预报的极端天气预报产品应用和检验   总被引：7，自引：5，他引：2  

董全  代刊  陶亦为  周军 《气象》2017,43(9):1095-1109

通过个例总结和大样本分析的方法,本文分析和总结了ECMWF集合预报系统(EPS)中的极端温度和降水预报产品。以上产品主要为08—08时的平均气温、最高气温、最低气温和降水量四个要素的极端天气预报指数(extreme forecast index,EFI)和SOT("shift of tail"index)。研究显示,气温EFI和SOT预报效果接近,降水SOT优于EFI。运用过去3年的资料,以TS评分最大为标准,分别确定了不同时效、不同百分位的极端高低温和极端强降水事件在我国的预报阈值,及其对应的各检验参数。对于1%(99%)百分位的极端低温(高温)事件,平均气温EFI和SOT的阈值分别在-0.85(0.75)和0.38(0),最高和最低气温的阈值与平均气温的阈值接近。对于95%和99%的极端强降水事件,EFI的阈值分别在0.45和0.7左右,SOT的阈值分别在-0.6和0.4左右。整体上呈现时效越长阈值越小,预报效果越差;事件越极端,阈值越大的特点。且此时的bias接近或略大于1,表明预报的发生频率与实况比较接近,具有较好的应用价值。气温EFI和SOT的预报效果和阈值存在明显的季节差异,夏季预报较好,阈值较大,冬季预报较差,阈值较小。降水的季节差异不明显。EFI和SOT的预报效果和阈值在空间分布上也存在一定的差异,且不同的产品空间分布差异不同。  相似文献   

氯化钠浮选剂最佳合成条件研究          下载免费PDF全文

王爱丽  李海民  张全有  孟瑞英  杨海云 《盐湖研究》2003,11(2):51-55

讨论了二种N -烷基吗啉类氯化钠浮选剂最佳浮选性能的合成条件 ,给出了研究结果。  相似文献   

等值反磁通瞬变电磁成像技术及工程应用     

赵虎  王玲辉  程强  张泉 《地球物理学进展》2021,36(5):2244-2250

为了实现对可溶岩区公路路线范围内的隐伏岩溶发育规模及形态进行高精度勘察,为后期处治设计提供翔实可靠的地质依据,在公路塌陷区域岩溶勘察中引入了一种新技术——等值反磁通瞬变电磁成像技术.文中首先对等值反磁通瞬变电磁成像技术的基本原理进行简述;然后论述了该方法的4种主要技术特点;紧接着对该方法的质量控制原则及数据处理流程等关键技术进行分析;最后利用该方法在惠清高速公路岩溶塌陷区探测中进行实际应用,成像结果准确地反映出了岩土界面的位置及变化形态,精确探测出了岩溶发育区的形态及规模,为后期塌陷区域的处治设计提供了可靠的基础资料.通过理论分析及实际应用结果表明:等值反磁通瞬变电磁法可对公路穿过区域隐伏岩溶发育情况进行精确成像,可快速准确的为岩溶塌陷区的后期处治设计提供基础资料.  相似文献   

Geochemistry of soils derived from black shales in the Ganziping mine area, western Hunan, China     

Jingzhe Xu  Bo PENG  Changxun Yu  Guang Yang  Xiaoyan Tang  Changyin Tan  Shurong Xie  Xianglin Tu  Zhicheng Bao  Meijie Quan  Min Xiao 《Environmental Earth Sciences》2013,70(1):175-190

The geochemistry of major and trace elements (including heavy metals and rare earth elements) of the fresh and weathered black shales, and the soils derived from black shales in the Ganziping mine area in western Hunan province (China) were studied using the following techniques: X-ray fluorescence (XRF), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray diffraction (XRD). The results show that the black-shale soils are significantly enriched with Al₂O₃ and Fe₂O₃, and depleted of mobile elements CaO, Na₂O and K₂O. The soils are also highly enriched with heavy metals U, V, Ni, Ba, Cu, Zn and Pb, that may cause potential heavy-metal contamination of the soils. Composition of the soils is homogeneous compared to the weathered black shales, for which the concentrations of major elements except CaO and Na₂O, and trace elements except heavy metals (U, V, Ni, Ba, Cu, Zn and Pb) as well as the mobile Sr, show lower variations than in the weathered black shales. Ratios of Zr/Hf, Ta/Nb, Y/Ho, Nd/Sm, and Ti/(Ti + Zr), of the soils are also less variable, with values constantly similar to that of the fresh and weathered black shales correspondingly. Thus, components of the soils are believed to be contributed from the parent black shales through weathering and pedogenesis. It is concluded that the soils were formed by at least two stages of geochemical processes: the early stage of chemical differentiation and the later stage of chemical homogenization. The chemical differentiation that was taken during black-shale weathering might have caused the depletion of CaO and Na₂O, and the enrichment of Al₂O₃ and Fe₂O₃; while the chemical homogenization that was taken during pedogenesis led to the depletion of SiO₂ and K₂O, and to the further enrichment of Al₂O₃ and Fe₂O₃. The heavy-metal enrichment (contamination) of the soils was then genetically related to the enrichment of Al₂O₃ and Fe₂O₃ in the soils.  相似文献   

The giant Dexing porphyry Cu–Mo–Au deposit in east China: product of melting of juvenile lower crust in an intracontinental setting     

Zengqian Hou  Xiaofei Pan  Qiuyun Li  Zhiming Yang  Yucai Song 《Mineralium Deposita》2013,48(8):1019-1045

The Dexing porphyry Cu–Mo–Au deposit in east China (1,168 Mt at 0.45 % Cu) is located in the interior of the South China Craton (SCC), made up of two lithospheric blocks, the Yangtze and Cathaysia blocks. The Cu–Mo–Au mineralization is associated with mid-Jurassic granodioritic porphyries with three high-level intrusive centers, controlled by a series of lineaments at the southeastern edge of the Yangtze block. Available age data define a short duration (172–170 Ma) of the felsic magmatism and the mineralization (171?±?1 Ma). The deposit shows broad similarities with deposits in volcanoplutonic arcs, although it was formed in an intracontinental setting. Porphyries associated with mineralization are mainly granodiorites, which contain abundant phenocrysts (40–60 %) and carry contemporaneous microgranular mafic enclaves (MMEs). They are mainly high-K calc-alkaline and show geochemical affinities with adakite, characterized by relatively high MgO, Cr, Ni, Th, and Th/Ce ratios. The least-altered porphyries yielded relatively uniform ε _Nd(t) values from ?0.9 to +0.6, and wide (⁸⁷Sr/⁸⁶Sr)_i range between 0.7046 and 0.7058 partially overlapping with the Sr–Nd isotopic compositions of the MMEs and mid-Jurassic mafic rocks in the SCC. Zircons from the porphyries have positive ε _Hf(t) values (3.4 to 6.9), and low δ¹⁸O values (4.7 to 6.3?‰), generally close to those of depleted mantle. All data suggest an origin by partial melting of a thickened juvenile lower crust involving mantle components (e.g., Neoproterozoic mafic arc magmas), triggered by invasion of contemporaneous mafic melts at Dexing. The MMEs show textural, mineralogical, and chemical evidence for an origin as xenoliths formed by injection of mafic melts into the felsic magmas. These MMEs usually contain magmatic chalcopyrite, and have original, variable contents of Cu (up to 500 ppm). Their geochemical characteristics suggest that they were derived from an enriched mantle source, metasomatized by Proterozoic slab-derived fluids, and supplied a part of Cu, Au, and S for the Dexing porphyry system during their injection into the felsic magmas. The 171?±?1 Ma magmatic-hydrothermal event at Dexing is contemporaneous with the mid-Jurassic extension in the SCC, followed by 160–90 Ma arc-like magmatism in southeastern China. With respect to the tectono-magmatic evolution of the SCC, the emplacement of Cu-bearing porphyries and the associated Cu mineralization occurred in response to the transformation from a tensional regime, related to mid-Jurassic extension, to a transpressional regime, related to the subduction of the Paleo-Pacific oceanic lithosphere.  相似文献   

High-rate precise point positioning (PPP) to measure seismic wave motions: an experimental comparison of GPS PPP with inertial measurement units   总被引：2，自引：1，他引：1  

Peiliang Xu  Chuang Shi  Rongxin Fang  Jingnan Liu  Xiaoji Niu  Quan Zhang  Takashi Yanagidani 《Journal of Geodesy》2013,87(4):361-372

High-rate GPS has been widely used to construct displacement waveforms and to invert for source parameters of earthquakes. Almost all works on internal and external evaluation of high-rate GPS accuracy are based on GPS relative positioning. We build an experimental platform to externally evaluate the accuracy of 50-Hz PPP displacement waveforms. Since the shake table allows motion in any of six degrees of freedom, we install an inertial measurement unit (IMU) to measure the attitude of the platform and transform the IMU displacements into the GPS coordinate system. The experimental results have shown that high-rate PPP can produce absolute horizontal displacement waveforms at the accuracy of 2–4 mm and absolute vertical displacement waveforms at the sub-centimeter level of accuracy within a short period of time. The significance of the experiments indicates that high-rate PPP is capable of detecting absolute seismic displacement waveforms at the same high accuracy as GPS relative positioning techniques, but requires no fixed datum station. We have also found a small scaling error of IMU and a small time offset of misalignment between high-rate PPP and IMU displacement waveforms by comparing the amplitudes of and cross-correlating both the displacement waveforms.  相似文献   

基于MEMLS模型的积雪深度反演方法     

李震  邵雨阳  周建民  田邦森  陈权  张平 《遥感学报》2013,17(3):657-670

利用被动微波遥感反演积雪深度一直是积雪遥感领域中的研究热点。在现有的积雪深度反演算法中,NASA算法因其简洁、易于扩展的特点,成为应用最为广泛的算法。但NASA算法存在着一定不足:首先,由于NASA算法基于线性拟合得出,在应用到其他研究区域时需要对反演公式进行重新拟合,适用范围受到一定限制;其次,由于算法中引入的19GHz与37GHz的亮温差在雪深达到一定范围时会达到饱和,因此算法会低估积雪深度。本文针对现有反演算法的不足之处,结合蚁群智能算法的特点,发展了基于蚁群算法的积雪深度反演算法;此外,针对NASA算法中存在的雪深低估问题,引入了AMSR-E10.7GHz亮温数据,对算法进行了改进。利用MEMLS模型的模拟数据与AMSR-E辐射亮温数据对算法进行实验,并采用实测数据与AMSR-E雪水当量产品对算法的反演精度进行评价。结果表明,两种积雪深度反演算法均是可行的,反演精度与现有产品相比有较为明显的改进。  相似文献   

基于地表覆盖的TM影像波段选择定量分析算法应用研究     

周泉  杨爱玲  张晶 《测绘与空间地理信息》2013,36(6):96-97,101

地表覆盖变化信息提取更加依赖丰富、准确、可靠的多时相、多层次、多分辨率、多源的数据,因此,为了获取地表覆盖的信息,必须要对影像波段进行优化组合。不同的波段组合对不同的地图显示的效果不同,多光谱影像合成需要进行波段组合优化,本文重点针对地表覆盖研究中经常采用的TM的多光谱数据的波段选择问题,对地表覆盖研究具有借鉴意义。  相似文献   

STUDY OF SETTING UP THE FOREST RESOURCES MANAGEMENT INFORMATION SYSTEM BASED ON WEBGIS   总被引：1，自引：0，他引：1  

WUSu-li LOUQuan-sheng QUANZhi-jie LIXiao-jun 《中国地理科学(英文版)》2003,13(1):56-61

Based on an analysis of the characteristics of the Forest Resources Management Information System of each development phase,and consideration of the technical trend in Geographic Information System(GIS)in the Internet Age,this paper explores the importance and the feasibility of setting up Forest Resources Management Information System based on the WEBGIS ,At the same time,based on the experience of our study,the paper explores the function,structure and method of developing the Forest Resources Management Information System based on WEBGIS ,With the technology of WEBGIS,the Forest Resources Management Information System with data from Huoditang Fam was set up ,which makes a great impact on forest resources management ,So setting up the Forest Resources Management Information System based on WEBGIS is a trend of forest resources management,In the course of setting up this system ,we must pay attention to following questions:1)unify data standard and information encoding;2)change mind.  相似文献