常用坐标系统转换方法探讨   总被引：3，自引：0，他引：3  

雷新堂 《地理空间信息》2008,6(4):121-124

分析了三种不同坐标转换方法的优缺点,通过广州市花都区测绘生产中使用的各种坐标系统成果进行验算比较,提出了平面坐标三种近似转换方法,从中选择出适合本地区大面积图形数据转换的坐标系统转换方法。  相似文献   

拓扑变换法在平面直角坐标近似变换中的应用     

陈群国  陈永立  赵根庄 《地理空间信息》2008,6(3):107-109

简要介绍了对平面直角坐标进行近似变换的几种方法,重点讨论了拓扑变换法对平面直角坐标进行近似变换的原理。并对其变换的精度情况进行了实践分析。提出了提高其变换精度的处理方法及在建立变换模型时应注意的问题。  相似文献   

30-year response to damming of a Mediterranean river in California,USA     

Fernando Magdaleno  Carlo Donadio  G. Mathias Kondolf 《自然地理学》2018,39(3):197-215

Dry Creek is a major tributary of the Russian River in Northern California (USA) that has experienced hydrologic and morphologic alterations after the closure of Warm Springs Dam in 1983. Our objective is to present a detailed diagnosis of the modification of the creek’s flow and sediment regimes, and interpret the alterations regarding the ecomorphologic evolution previously observed in the creek. Statistical analysis of the river’s flow and sediment series indicates that dam operation has had significant impacts on the magnitude and frequency of occurrence of the highest floods, and the magnitude, variability, and duration of low and very low flows. Similarly, sediment concentration and discharge have also experienced major alterations. Loss of habitat complexity for native flora and fauna (especially endangered salmonids), channel incision, and vegetation encroachment are some of the negative trends found for the creek over the last 30 years, since river regulation began. We discuss the present dynamics of the river and propose, on that basis, the improvement of its hydromorphic functioning as part of future large-scale restoration initiatives.  相似文献   

传承与嬗变：广州市小洲村的空间转换   总被引：2，自引：1，他引：1  

方远平  易颖  毕斗斗 《地理研究》2018,37(11):2318-2330

在快速城市化进程影响下,广州市小洲村因从典型的岭南水乡古村逐步演化为创意艺术与旅游空间而成为关注热点。空间生产理论为揭示小洲村的空间转换与重构提供了理论工具。运用实地考察法、访谈法、文本分析法等质性研究方法,围绕“空间转换的过程”“空间生产主体及作用”“空间生产的结果及机制”等问题,探讨不同发展阶段各空间主体对小洲村的建构过程以及结果,构建“时间—空间主体—空间”的分析框架。研究发现：① 小洲村经历了岭南水乡古村落的自然发育阶段、艺术精英自发集聚阶段、乡村旅游与文化创意产业融合发展阶段三个空间转换阶段,并分别形成了对应水乡古寨的生产生活空间、艺术创意空间、创意旅游商业空间三种空间形态。② 创意阶层、政府、资本、游客等空间主体的加入,使小洲村由单一空间主体（村民）转变为多元主体。③ 在资本城乡不平衡发展机制下,创意阶层、政府、资本、村民、游客等空间主体为实现各自的利益诉求,在小洲村的空间转换中产生了不同的影响,其中当地村民、创意阶层和游客发挥着自下而上的能动作用;政府起到自上而下的管治作用,但在村民的空间抵抗下效果甚微。  相似文献   

青海共和盆地风况及风沙地貌   总被引：1，自引：1，他引：0  

陈宗颜  董治宝  汪青春 《中国沙漠》2018,38(3):492-499

利用共和盆地茶卡、共和、贵南站2012-2015年的风资料,分析盆地风向、风速和输沙势的变化特征,并结合Google Earth高清影像,对盆地风能环境与风沙地貌进行探讨。结果表明：（1）盆地年平均风速1.6～2.7 m·s^-1,西北部、中部和东南部年起沙风出现的频率分别为7.7%、3.5%、0.9%,起沙风主要发生在冬、春季,风向以WNW和W为主。（2）盆地属于低风能环境,风沙活动自西北部向东南部减弱,方向变率指数0.7～0.96,风况为窄单峰或宽单峰风况,西北部和中部风向变率属于低变率,东南部属于中等变率,合成输沙方向较一致,为281.0°～286.7°。（3）盆地沙丘类型有新月形沙丘（链）、格状沙丘、复合型链状沙丘、沙山、沙垄、抛物线沙丘等,沙丘类型和风况较吻合。  相似文献   

RTK技术在高速公路像片控制测量中的应用     

李宏伟  潘宝玉  崔国钧 《山东国土资源》2006,(Z1)

通过RTK技术在诸永高速公路1∶2000像片控制测量中的应用,介绍了RTK测量在带状测区基准转换参数的求解方法及RTK测量成果的精度检验等情况。结果表明,RTK测量不仅能够满足1∶2000像片控制测量精度要求,而且可以大幅度提高作业效率,尤其在交通和通视困难地区更具明显优势。即使在山区和高山区,只要采取有效措施,RTK测量同样能取得比较高的精度。  相似文献   

Cokriging of regionalized compositions     

V. Pawlowsky 《Mathematical Geology》1989,21(5):513-521

To avoid spurious spatial correlation when analyzing the spatial covariance structure of regionalized compositions, additive-log-ratio transformation can be used. Here, the additive-log-ratio cokriging estimator, derived in a natural way from this transformation, is shown to be invariant under permutation of components of the untransformed regionalized composition. It leads, as expected, to an exact interpolation. As original data, predicted values of the regionalized composition at unknown points add up to the same constant c and lie between 0 and c.  相似文献   

Regime-dependent streamflow sensitivities to Pacific climate modes cross the Georgia–Puget transboundary ecoregion     

Sean W. Fleming  Paul H. Whitfield  R. D. Moore  Edward J. Quilty 《水文研究》2007,21(24):3264-3287

The Georgia Basin–Puget Sound Lowland region of British Columbia (Canada) and Washington State (USA) presents a crucial test in environmental management due to its combination of abundant salmonid habitat, rapid population growth and urbanization, and multiple national jurisdictions. It is also hydrologically complex and heterogeneous, containing at least three streamflow regimes: pluvial (rainfall-driven winter freshet), nival (melt-driven summer freshet), and hybrid (both winter and summer freshets), reflecting differing elevation ranges within various watersheds. We performed bootstrapped composite analyses of river discharge, air temperature, and precipitation data to assess El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) impacts upon annual hydrometeorological cycles across the study area. Canadian and American data were employed from a total of 21 hydrometric and four meteorological stations. The surface meteorological anomalies showed strong regional coherence. In contrast, the seasonal impacts of coherent modes of Pacific circulation variability were found to be fundamentally different between streamflow regimes. Thus, ENSO and PDO effects can vary from one stream to the next within this region, albeit in a systematic way. Furthermore, watershed glacial cover appeared to complicate such relationships locally; and an additional annual streamflow regime was identified that exhibits climatically driven non-linear phase transitions. The spatial heterogeneity of seasonal flow responses to climatic variability may have substantial implications to catchment-specific management and planning of water resources and hydroelectric power generation, and it may also have ecological consequences due to the matching or phase-locking of lotic and riparian biological activity and life cycles to the seasonal cycle. The results add to a growing body of literature suggesting that assessments of the streamflow impacts of ocean–atmosphere circulation modes must accommodate local hydrological characteristics and dynamics. Copyright © 2007 John Wiley & Sons, Ltd. The copyright in Paul H. Whitfield's contribution belongs to the Crown in right of Canada and such copyright material is reproduced with the permission of Environment Canada.  相似文献   

GPS控制网约束平差精度探讨     

祝乃龙 《地理空间信息》2009,7(5):16-18

简要介绍了GPS生产过程中局域范围的坐标转换常用模型、重合点选择以及对约束平差精度进行分析，根据约束平差精度要求选择重合点、转换模型和方法，对GPS相对定位测量数据处理中的约束平差、坐标转换模型及重舍点选择对约束平差精度的影响进行系统分析，以统计图表方式进行系统研究，从GPS应用中探讨约束平差的方法。  相似文献   

新疆兵团坐标转换参数的确定   总被引：1，自引：0，他引：1  

高永甲 《测绘与空间地理信息》2009,32(3):202-204,207,210

在新疆兵团高精度GPS首级网建成的基础上,实时地确定出新疆兵团坐标转换参数,并提供给用户使用,取得了良好的社会效益和经济效益.论述了新疆兵团坐标转换参数确定的教学模型、参数确定的方法、回代粗差探测技术、参数区域划分原则、参数精度及参数的使用等问题,是新疆兵团最新一项GPS应用研究成果,已在新疆兵团各项基础测量生产中全面推广应用.文中的观点和方法可供从事GPS定位和坐标转换技术人员参考.  相似文献