一种基于OpenMP的高效GPS卫星钟差实时估计方法

提出基于单观测值的Kalman滤波快速计算方法,并引入共享存储并行编程（OpenMP）技术实现协方差快速更新,从而实现非差GPS卫星钟差的快速实时计算。均匀选取55个IGS参考站,计算2017-03-20~03-30采样率为60 s的卫星钟差。与IGS事后30 s钟差相比,两者具有很好的一致性,RMS互差优于0.5 ns。选取未参与钟差解算的10个IGS参考站进行精密单点定位,结果表明,实时静态PPP水平方向精度优于2 cm,高程方向精度为2~4 cm;实时动态PPP水平方向精度为2～4 cm,高程方向精度为4～6 cm,能够满足实时PPP的精度要求。该方法在主频1.2 GHz服务器上8线程并行模式下单历元耗时4 s,相比串行模式效率提升1/3。     

利用超快速精密星历约束的北斗卫星实时精密定轨

以广播星历为起算轨道的北斗卫星实时滤波精密定轨往往需要较长收敛时间,针对此,提出利用超快速精密星历约束的实时精密定轨方法。通过MGEX跟踪网全球分布的51个测站连续7 d的实测数据,利用平方根信息滤波对北斗卫星实时精密轨道进行确定,并以3 d解事后轨道作为参考,评估北斗卫星实时滤波轨道精度。结果表明,利用广播星历作起算轨道时,北斗实时滤波轨道平均需要经过15 h收敛才能达到稳定,而新方法在这段时间内轨道变化较为平稳,未出现明显的收敛现象,并且7 d时间内GEO卫星在切向、法向和径向上RMS分别优于2.5 m、20 cm和30 cm,IGSO和MEO卫星在3个方向上分别优于30 cm、15 cm和10 cm。
     

锦州9-3油田海域环境现状及其评价

1 引言 石油,作为现代社会的主要能源,在全球经济迅速发展和人口激增的情况下,世界范围内的供求在不断增长,海洋石油勘探开发规模也在不断扩大.海洋油气开发已成为我国油气战略资源的主要来源之一.     

全过程联合校正方法在饶河流域洪水预报中的应用研究

为提高饶河流域洪水预报精度,将全过程联合校正(EPJC)方法与三水源新安江(XAJ)模型结合,按一定比例划分洪水预报总误差为各过程误差,基于系统响应理论反演得到面雨量计算误差和模型参数误差,重新输入流域水文模型正演得出校正后的洪水过程.选取洪峰流量相对误差、峰现时间绝对误差、径流深相对误差和确定性系数作为模型评价指标,...     

乌鲁木齐市建设生态城市现状的比较分析及发展对策研究

乌鲁木齐是绿洲城市,自然环境比较脆弱,由于城市建设缺乏生态环境规划,能源消费结构不合理以及特殊的自然地理等原因,致使城市的生态环境问题十分突出,建设生态城市是乌鲁木齐市未来发展的必然选择。从城市生态系统的结构、功能和协调度三个方面构建了生态城市的评价指标体系,采用层次分析法对乌鲁木齐市生态城市建设现状进行了定量分析,同时选择北京、上海、成都、西安、兰州等5个城市的生态化程度进行对比,结果表明:乌鲁木齐市的结构指数为0.241,低于对比的5个城市;功能指数乌鲁木齐为0.271,远低于上海(0.615)、北京(0.466)和兰州(0.343),与西安(0.272)接近,略高于成都(0.222);从城市协调度来看,乌鲁木齐市的指数值为0.306,为6个城市的最小值,生态综合指数由高到低分别为北京(0.580)>上海(0.579)>成都(0.382)>西安(0.380)>兰州(0.360)>乌鲁木齐(0.270),乌鲁木齐市生态化程度为第Ⅳ级,即生态化程度较低,为6个城市中的最低值。总体上为较发达地区城市的生态化程度较高,中西部地区城市的生态化程度较低。乌鲁木齐市建设生态城市应采取的关键对策包括以下几个方面:1、编制城市综合生态区划,做好城市生态规划;2、优化能源结构,大力发展清洁能源;3、建立排污权交易制度,控制大气污染;4、采用边际成本定价方法、制定科学的水价、优化配置水资源;5、合理布局城市景观生态,搞好城市绿化及荒山绿化。     

Advanced use into rainfall prediction of three-dimensionally scanning radar

A computational method for the determination of rainfall distribution for applications in short term rainfall prediction is presented here. The method is strongly influenced by the experience gained from the observation and analysis of data gathered on a heavy rainfall event in 1986 that occurred during the Baiu Season in Japan. The method is based on the concept that rainfall occurs as an interaction between an instability field, appropriately modeled, and a field of water vapor under the influence of topography. The results from this computational method showed good agreement with the temporal variation in the rainband that moved across the observation field in 1986. Towards determination of the parameters in the computational model, another method for the determination of the rainfield is also developed. This second method determines the rainfall distribution from estimation of the conversion rate of water vapor to liquid water through use of data from a three dimensional scanning radar. The results are consistent with those obtained from the first method.     

FD-125测氡仪观测中值得注意的几个问题

论述了FD-125测氡仪在水氡观测中值得注意的几个问题：①仪器的供电系统中不应有线路接触不良；②仪器接地线应避免接触不良；③其他用电器内部线路也不应有接触不良；④引起电场和磁场变化的大功率用电设备不应在测量时间内使用；⑤供电电路中电压尽可能避免大幅度波动等。上述因素对氡测值都有影响，影响幅度可达10％以上。     

Holocene development and anthropogenic disturbance of a shallow lake system in Central Ireland recorded by diatoms

Three cores from two connected lakes in Central Ireland (Lough Kinale and Derragh Lough) were investigated using diatom analysis to establish the Holocene development of the lacustrine system, any local variations within the lakes and any anthropogenic influences. The study area was situated in a lowland location and the lakes were shallow, unstratified and interconnected. Litho-and bio-stratigraphical analyses of the lake cores and deposits beneath a mire separating the two lakes showed the changing spatial configuration of the lake system in the early Holocene and the separation of the initial lake into three basins (cf. lacustrine cells) and finally into two interlinked lakes. The evolution of the lake system is conceptualised as the development of distinct lacustrine cells, and its sediments have recorded changes in the physical (geography, depth and sedimentation) and chemical (water chemistry) properties of the lakes inferred through diatom analyses. The longest sequence, from the early Holocene, records fluctuating lake levels and these are correlated with geomorphological mapping and surveying of palaeoshorelines. The diatom assemblages of the upper 2 m of the three cores, covering approximately the last 2000–3000 radiocarbon years show considerable difference in trophic status and life-form categories. This is related to the location of the cores in the lake and also the distance from human settlement with particular reference to proximity to crannog (artificial island) construction and use. The most central core from the deepest part of Lough Kinale has the least representation of the human settlement and agricultural activity in the catchment and on the fringes of the lake, whereas the core taken from the edge of a crannog is able to identify when construction and use of the crannog occurred. The local nature of the palaeoecological response to human activity due to incomplete water mixing has the advantage of allowing the lake sediment cores to be used to determine spatially discrete settlement patterns.     

国内氢氧化镁阻燃剂的研究现状

综述了国内氢氧化镁阻燃剂的合成、表面改性及其应用,主要论述了近20年来国内在氢氧化镁阻燃剂研发方面取得的成果及发展方向,简单概述氢氧化镁阻燃剂的发展前景。     

Continuous,Direct Gas-Geochemical Monitoring in Hydrothermal Vents: Installation and Long-Term Operation on Nisyros Island (Greece)

In this paper the installation and long-term operation of a system for continuous monitoring of fumarolic gases is described. Several physicochemical and gas-geochemical parameters such as the concentration of CO₂, H₂S and CO in the fumarolic emissions, as well as the temperatures of the hydrothermal steam and soil in close vicinity of the fumarole and steam pressure are measured in short-time intervals (typically 15 seconds). Data are logged on-site and in parallel transferred to a remote station by digital telemetry. Specially developed software enables the real-time observation of the local conditions in the crater and full bidirectional control of the monitoring system. Fluctuations in the monitored parameters are also reported. From the data presented it can be concluded that environmental conditions (direction and strength of wind, precipitation) will interact with some of the parameters monitored. These influences can only be revealed by continuously operated monitoring systems.