Forecasting front displacements with a satellite based ocean forecasting (SOFT) system

Relatively long term time series of satellite data are nowadays available. These spatio–temporal time series of satellite observations can be employed to build empirical models, called satellite based ocean forecasting (SOFT) systems, to forecast certain aspects of future ocean states. The forecast skill of SOFT systems predicting the sea surface temperature (SST) at sub-basin spatial scale (from hundreds to thousand kilometres), has been extensively explored in previous works. Thus, these works were mostly focussed on predicting large scale patterns spatially stationary. At spatial scales smaller than sub-basin (from tens to hundred kilometres), spatio–temporal variability is more complex and propagating structures are frequently present. In this case, traditional SOFT systems based on Empirical Orthogonal Function (EOF) decompositions could not be optimal prediction systems. Instead, SOFT systems based on Complex Empirical Orthogonal Functions (CEOFs) are, a priori, better candidates to resolve these cases.In this work we study and compare the performance of an EOF and CEOF based SOFT systems forecasting the SST at weekly time scales of a propagating mesoscale structure. The SOFT system was implemented in an area of the Northern Balearic Sea (Western Mediterranean Sea) where a moving frontal structure is recurrently observed. Predictions from both SOFT systems are compared with observations and with the predictions obtained from persistence models. Results indicate that the implemented SOFT systems are superior in terms of predictability to persistence. No substantial differences have been found between the EOF and CEOF-SOFT systems.     

Topological Expression Model of Satellite Gear Mechanism

By investigation of the topological characteristics of the kinematic structure of Satellite Gear Mechanism (SGM) with graph theory, the graph model of SGM is analyzed, and a topological expression model between input and output of SGM is established based on systematic design point. Meanwhile, the mathematical expression for SGM is deduced by integrating matrix theory and graph theory; thus, the topological characteristics of the kinematic structure of SGM can be converted into a matrix model, and the topological design problem of SGM into a matrix operation problem. In addition, a brief discussion about the measures for identification of isomorphism of the graph mode is made.     

水上溢油应急装备跟踪定位浮标关键技术研究

文中介绍了近年来国内外溢油事故危害及应急技术现状,针对当前海上溢油难以跟踪定位的难题,提出了溢油跟踪定位浮标技术解决方案,采用北斗卫星定位通信为平台,实现海上溢油的全过程、全天候的实时跟踪、监测功能,通过海上试验验证,溢油跟踪定位浮标为海上溢油事故应急快速反应提供了一种有力工具．     

Particle fluxes in the Almeria-Oran Front: control by coastal upwelling and sea surface circulation

Particle flux data were obtained from one instrumented array moored under the direct influence of the Almeria-Oran Front (AOF) in the Eastern Alboran Sea, Western Mediterranean Sea, within the frame of the “Mediterranean Targeted Project II-MAss Transfer and Ecosystem Response” (MTPII-MATER) EU-funded research project. The mooring line was deployed from July 1997 to May 1998, and was equipped with three sequential sampling sediment trap-current meter pairs at 645, 1170 and 2210 m (30 m above the seafloor). The settling material was analysed to obtain total mass, organic carbon, opal, calcium carbonate and lithogenic fluxes. Qualitative analyses of SST and SeaWiFS images allowed monitoring the location and development of the Western and Eastern Alboran Sea gyres and associated frontal systems to determine their influence on particle fluxes.Particle flux time series obtained at the three depths showed a downward decrease of the time-weighed total mass flux annual means, thus illustrating the role of pelagic particle settling. The total mass flux was dominated by the lithogenic fraction followed by calcium carbonate, opal and organic carbon. The time series at the various depths were rather similar, with two strong synchronous biogenic peaks (up to 98 mg m⁻² day⁻¹ of organic carbon and 156 mg m⁻² day⁻¹ of opal) recorded in July 1997 and May 1998. Through comparing the fluctuations of the lithogenic and calcium carbonate-rich fluxes with the biogenic flux, we observed that the non-biogenic fluxes remained roughly constant, while the biogenic flux responded strongly to seasonal variations throughout the water column.Overall, the temporal variability of particle fluxes appeared to be linked to the evolution of several tens of kilometres in length sea surface hydrological structures and circulation of the Alboran Sea. Periodic southeastward advective displacements of waters from upwelling events off the southern Spanish coast were observed on SST and SeaWiFS images. In between these periods, widespread phytoplankton blooms were observed. The influence of the varying surface structures resulted in changes in the biogenic particle flux. For example, we observed an opal pulse in April 1998 that resulted from a diatom-rich highly productive frontal surface situation above the mooring line.Estimation of the annual organic carbon export and calculation of a seasonality index indicate that the overall dynamics of the carbon reservoir within the Eastern Alboran Sea appears to be strongly influenced by the sea surface hydrological structures.     

基于轨道约束H∞滤波的 北斗辅助列车定位算法研究

针对列车定位的高安全性和稳定性要求,结合列车行驶的特殊性,提出采用铁路轨道信息对北斗定位数据进行约束的H_∞滤波算法。以模糊自适应"当前"统计模型为基础建立列车运动模型,通过将轨道近似为直线段,建立轨道约束模型。将轨道约束与H_∞滤波器结合实现轨道约束H_∞滤波算法。通过仿真对比分析H_∞滤波与卡尔曼滤波、约束与无约束估计的误差。仿真结果表明:轨道约束在提高算法定位精度方面效果明显,H_∞滤波在列车位置估计上具有鲁棒性优势。验证了轨道约束H_∞滤波算法的有效性,对北斗辅助列车定位的工程应用具有理论指导意义。     

铁路应急通信系统应用

按照铁道部应急技术体制,结合我国铁路实际的现场情况,分析铁路应急通信系统的组成方式和应用模式,以及如何通过各种通信手段构建高效的多媒体指挥平台。     

卫星AIS系统分析与研究

文章介绍了卫星AIS的工作原理,分析了其核心结构功能及性能特点,并针对卫星AIS系统的探测概率、卫星平台及报文类型进行了研究。     

利用卫星微波遥感资料推算波浪极值

应用已取得的Ｔ／Ｐ卫星高度计资料和ＥＲＳ－１卫星散射记资料,计算和推算结果表明,推算的极值与实测的极值非常接近,差值小于０．４ｍ。利用卫星微波遥感资料推算多年一遇的波高极值,方案是可行的,方法是可靠的,精度是可信的。     

利用卫星影像进行新线勘测设计的可行性研究

主要从铁路设计阶段、卫星影像的特点、制作地形图等方面分析利用卫星影像进行新线勘测设计的可行性     

GPS多普勒定位法的研究

本文提出了ＧＰＳ信号多普勒频移的测量方法，给出了定位解算的数学方法，并与子午仪系统的多普勒定位法和ＧＰＳ的伪距定位法进行了比较。