CD2000型深孔立轴式岩心钻机的研制          下载免费PDF全文

宋金亭姜光忍  唐宇恒高保娟 石清荣 《探矿工程》2006,33(12):40-41

介绍了CD2000型深孔立轴式岩心钻机的结构、特点、主要技术参数、试验概况及效果。  相似文献   

Improvement of SWAT2000 modelling to assess the impact of dams and sluices on streamflow in the Huai River basin of China     

Gangsheng Wang  Jun Xia 《水文研究》2010,24(11):1455-1471

Hydrological simulation and assessment in a dam–sluice regulated river basin are a complex and challenging issue. In this article, an improved SWAT2000 modelling system was developed that incorporated the Shuffled complex evolution (SCE‐UA) optimization algorithm and the multi‐site and multi‐objective calibration strategy. The implication of multi‐objective is different for different types of outlets, i.e. streamflow for an ordinary outlet, inflow for a sluice, and water storage for a reservoir. Model parameters were redefined to improve model simulations. The surface runoff lag time (SURLAG) was extended as a spatially distributed parameter, and a correction coefficient was introduced to modify the saturated hydraulic conductivity. The modelling system was then applied to the Huai River basin of China under various climatic conditions, including a very dry year (1999), a dry year (1981), an average year (1971), and wet year (1991). In all, 26 dams and 35 sluices were considered, among which about 20 dams/sluices were used for model calibration. The impact assessment primarily focused on the very dry year (1999). The results indicated that the released water from large reservoirs was blocked in the river channels by sluices located downstream. In the very dry year, the dam–sluice operations could result in an increase of the runoff volume during the non‐flood season and a decrease in runoff during the flood season, but the changing magnitude during the non‐flood season was much greater. An important conclusion of this case study is that the sluices in the Sha‐Yin branch located in the north region and the dams in the southern mountainous region above the Wangjiaba Hydrological Station have played the most significant role in regulating the streamflow of the entire river basin. The methods addressed in this article can simulate hydrological regime in the river basins regulated by dams and sluices under different climatic conditions at the whole‐watershed scale. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

江门市高精度GNSS控制网数据处理技术研究     

涂纯二  江翠云  陈国恒 《地理空间信息》2021,19(4):37-40

针对华南沿海城市的高精度的CGCS2000大地基准建设要求,分别从基线解算与网平差计算两方面的策略进行探讨分析,建立以江门市为例的高精度大地基准框架。结果表明采用高精度的GAMIT/GLOBK数据处理软件,设置较小的采样间隔和增加一定的观测时长,能为高精度的CGCS2000大地基准建设提供借鉴参考,也为后续的似大地水准面精化提供高精度的大地基准数据基础。  相似文献   

“多规合一”坐标系统选择探索     

雷勇  汪李辉  陈柱  任传建  王志红 《测绘与空间地理信息》2021,44(1):65-67,72

多规合一是城市建设发展的必然趋势。在边长投影变形较大的地区,通过边长投影变形的计算、处理,各自选择合适的坐标系统,依托自然资源部门的测绘技术力量,进行转换处理。消除自然资源部门同城乡建设部门之间由于坐标系统不同带来的差异,在满足工程建设精度要求、保证工程建设质量的前提下,满足自然资源部要求。  相似文献   

ITRS/J2000坐标转换误差及其对掩星反演的影响分析     

董启甲  程艳  周中华  许嵩  卿芸  汪文君 《大地测量与地球动力学》2021,41(5):530-534

分别对ITRS/J2000转换过程中的极移/潮汐章动、常数偏差矩阵等误差造成的影响进行分析,并分析季节变化、太阳活动、地磁活动等对坐标转换精度的影响。对2019年的IGS精密星历数据进行ITRS地固系转J2000惯性系坐标分析表明,潮汐章动造成的坐标转换误差为0.44 m,春季坐标转换误差(0.23 mm)是其他季节的约3倍;常数偏差矩阵对坐标转换误差可造成1.7 m的影响。对中性大气掩星反演的轨道转换加入误差改正项进行分析表明,潮汐章动和常数偏差矩阵对反演的温度产品分别造成0.09 K和0.19 K的误差影响。建议在进行GNSS无线电掩星反演中采用潮汐章动的高频改正,并且在ITRS/J2000转换过程中推荐将常数偏差矩阵进行旋转处理。  相似文献   

Terrain data compression using wavelet-tiled pyramids for online 3D terrain visualization     

Ricardo Olanda  Mariano Pérez  Juan Manuel Orduña  Silvia Rueda 《International journal of geographical information science》2014,28(2):407-425

Last years have witnessed the widespread use of online terrain visualization applications. However, the significant improvements achieved in sensing technologies have allowed an increasing size of the terrain databases. These increasing sizes represent a serious drawback when terrain data must be transmitted and rendered at interactive rates. In this paper, we propose a novel wavelet-tiled pyramid for compressing terrain data that replaces the traditional multiresolution pyramid usually used in wavelet compression schemes. The new wavelet-tiled pyramid modifies the wavelet analysis and synthesis processes, allowing an efficient transmission and reconstruction of terrain data in those applications based on multiresolution tiled pyramids. A comparative performance evaluation with the currently existing techniques shows that the proposed scheme obtains a better compression ratio of the terrain data, reducing the storage space and transmission bandwidth required, and achieving a better visual quality of the virtual terrain reconstructed after data decompression.  相似文献   

基于遥感的珠江口海岸线变迁分析          下载免费PDF全文

张怡  李晓敏  马毅  包玉海 《海洋测绘》2014,(3):52-55

利用1990年、2000年和2010年三个时相的遥感影像,进行2000年前后两个十年的海岸线变迁情况对比分析。结果表明:2000年前的十年间,珠江口海岸线向海推进,导致面积共增加了16486.63ha,主要受人为因素影响,围海养殖是本时段海岸线变迁的主要因素;2000年后的十年间,珠江口海岸线继续向海推进,但推进速度降低,导致面积增加了9280.15ha,填海造地是这一时段海岸线变迁的主要因素。又根据珠江口的区域特征,以珠江入海八大口门为界,将整个研究区划分为九个岸段进行了详细分析。  相似文献   

手持式GPS仪改正参数的内业确定方法     

朱向荣  孙肖 《地理空间信息》2014,(4):136-138

讨论了手持式GPS仪改正参数的内业确定方法 ,并给出了利用Excel表格进行计算的具体解决方案。与传统方法相比,本方法具有完全室内作业、省时省力、参数可靠性高的特点。  相似文献   

湖南省CGCS2000国家大地坐标系统转换方法   总被引：1，自引：0，他引：1  

魏卫红  汤仲安 《测绘工程》2011,20(3):21-24

基于湖南省大地控制点布设现状、各等级控制点成果以及信息扩散估计理论,分析现有CGCS2000坐标成果和北京54、西安80两类坐标系建模共点的数据质量,为后续模型优选和模型质量保障奠定基础.在此基础上,研究各类大地坐标系统转换算法,实例计算各类算法的坐标转换结果,进行精度比较与分析,提出适宜于湖南省CGCS2000坐标系...  相似文献   

参心坐标系向地心坐标系转换若干问题的分析     

张洪文  张明丽  张亚峰 《测绘与空间地理信息》2011,34(4):164-166

通过实例数据,对1980西安（参心）坐标系向2000（地心）坐标系转换过程中遇到的若干问题进行探讨,分析了参心坐标系大地高的粗差、公共点位于不同投影带、公共点位于不同高程抵偿面等因素对转换精度的影响。  相似文献