超高阶重力场模型EIGEN-6C2适应性分析

为了证明EIGEN-6C2是目前较优的超高阶重力场模型,该文将我国全部的共计13个沿海省市的陆地和岛礁上2 917个GNSS水准点的实测高程异常,分别与近几年国际上公布的比较优秀的EGM2008、EIGEN-6C、EIGEN-6C2、GO_CONS_GCF_2_DIR_R4和GOCO03S5个重力场模型的不同截断阶次模型高程异常之差进行外部精度检验,最后得出了到目前为止EIGEN-6C2重力场模型与我国沿海省市实测高程异常符合性最好的结论。     

The Impacts of Climate Change on the Autumn North Atlantic Wave Climate

Abstract

In this study, we investigate the impact of global warming induced by possible climate change on the autumn winds, the related storm climate, and the wave climate over the North Atlantic Ocean. These analyses are based on a third-generation wave model, WAVEWATCHIII? and dynamically downscaled winds, obtained from the Canadian Regional Climate Model driven by the third version of the Coupled Global Climate Model (T47) from the Canadian Centre for Climate Modelling and Analysis following the A1B climate change scenario of the Special Report on Emission Scenarios from the Intergovernmental Panel on Climate Change. Compared with the present wave climate, represented as 1970–1999, the significant wave heights in the northeast North Atlantic will increase, whereas in other areas, such as the mid-latitudes, they will decrease, with associated changes in winds in the future climate (2040–2069). An analysis of inverse wave ages is used to suggest that wind-driven wave regimes tend to occur more frequently in the northeast North Atlantic and decrease in the mid-latitudes in the climate change scenario. The dominant North Atlantic storm-track region is estimated to shift northward, especially over the northern Northeast Atlantic, where the frequency of occurrence of the most intense cyclones is estimated to increase. We suggest that changes in storm densities are related to changes in the upper level steering flow in the atmosphere, which are the precursor to changes in the winds and ocean waves.     

基于内力的卫星编队飞行动力学建模

基于内力的卫星编队飞行凭借良好的性能正日益受到重视,但由于该类编队的控制力对卫星间的相对位置和相对姿态均高度敏感,并且控制力和控制力矩之间存在耦合,给动力学建模带来了很大的挑战.首先,建立了六自由度的内力编队姿轨耦合动力学模型,该动力学模型利用了控制力和控制力矩的耦合效应,可以同时针对编队卫星的相对位置和相应姿态设计相应的控制律,从而实现编队的六自由度协同控制.最后,通过采用伪谱法求解编队构型的重构问题,对该动力学模型进行了验证.     

QZSS L6E增强服务改正数支持的PPP性能评估

准天顶卫星系统目前利用QZS-2~QZS-43颗卫星播发L6E信号,为东亚和大洋洲地区用户提供实时的增强服务。该文分析了L6E信号结构及轨道和钟差的计算模型,研究了目前L6E信号的覆盖范围和可用性,评估了L6E改正数恢复的卫星轨道和钟差及其用于动态PPP的精度水平。结果表明:我国用户在使用15°截止高度角时L6E信号仍有100%的可用性;L6E改正数恢复的GPS和GLONASS卫星轨道的3D RMS平均值分别为5.3和13.9 cm,卫星钟差的STD平均值分别为0.14和0.22 ns,利用GPS卫星的轨道和钟差进行的动态PPP可以获得水平优于10 cm、高程优于15 cm的精度,在加入GLONASS卫星后,东方向和高程方向定位误差和收敛时间均有明显改善。     

基于高分六号红边特征的面向对象桉树人工林信息提取

有效监测桉树林空间分布对区域生态环境保护及有关部门的统筹决策具有重要指导意义。本文在现有研究的基础上,以国内首个提供红边波段的多光谱高分六号（GF-6）卫星影像为数据源,选取广西鹿寨县为典型研究区域,结合光谱特征、植被指数特征和红边特征,设计不同特征组合分类方案,采用面向对象多尺度分割方法,对不同尺度层分别构建隶属度函数和CART决策树模型以进行分类提取桉树人工林信息。试验结果表明,红边特征在CART决策树模型构建中具有重要影响,融入GF-6红边特征能有效提高桉树人工林分类提取精度,总体精度达到91.75%,相比仅采用传统波段和植被指数的分类方案,精度提高了11.25%。本文研究结果在利用国产卫星红边波段识别提取桉树人工林方面具有重要的理论意义和实用价值。     

Marine Isotope Stage 7–6 transition age for beach sediments at Morston,north Norfolk,UK: implications for Pleistocene chronology,stratigraphy and tectonics

Optically stimulated luminescence age estimates for the Pleistocene beach at Morston, north Norfolk, UK, obtained by the single‐aliquot regenerative‐dose protocol, indicate a Marine Isotope Stage (MIS) 7–6 transition date. The view that the beach is of Ipswichian (MIS 5e) age, held virtually unanimously for the last 75 years, may now be discarded. The extant beach sequence lies up to ～5 m OD, yet global models suggest that MIS 7–6 sea levels were typically substantially below that of today. The explanation may lie with poorly understood regional tectonic movements. The MIS 7–6 date helps to constrain the ages of glacial deposits that bracket the beach sediments at Morston. The underlying Marly Drift till cannot be younger than MIS 8; this may also be true for the complex assemblage of glaciogenic landforms and sediments, including the Blakeney esker, in the adjacent lower Glaven valley. The well‐established Late Devensian (MIS 2) age of the Hunstanton Till is not compromised by the date of the Morston beach. There is no indication of a proposed Briton's Lane glaciation during MIS 6 times. Copyright © 2009 John Wiley & Sons, Ltd.     

断陷盆地中断裂作用与油气的关系

断陷盆地（以黄骅坳陷为例）中广泛的断裂作用不但控制了生油凹陷的形成，而且对油气的运移和富集具有重要影响．断层的三元结构和断裂带的多元结构模型，更能合理地解释断裂作用与油气的相互关系．岩石物性参数分析表明断裂带具有双重性，即对油气的横向封堵和侧向导流．在此基础上，本文探讨了不同时代断层的断裂带对油气的封堵能力．最后通过断层剖面特征和空间配置关系的归纳研究，尝试性地对断层控制的油气藏作了形态分类．     

莼菜( Brasenia schreberi )冬芽对 Cr6+污染的抗性反应

研究了Cr6 +污染对莼菜冬芽外部形态及过氧化物酶、硝酸还原酶活性、叶绿素、O-·2 、MDA的含量等生理指标的影响 .结果显示 :Cr6 +对莼菜毒害机制在于抑制酶活性和损害细胞膜系统 .在培养第三天时叶绿素的含量随着Cr6 +浓度的增加而降低 ;过氧化物酶的活性在 10mg/L中最高 ;硝酸还原酶活性除在 5mg/L中的略微升高外 ,在 10 - 4 0mg/L之间随着Cr6 +培养浓度的升高而降低 ;O-·2 的含量在 5mg/L中的最高 ,在 10mg/L中略高于对照 ,在随后培养中随浓度的升高而降低 ,MDA的含量变化趋势和O-·2 相似