检测前跟踪框架下利用蒙特卡洛算法的空间碎片跟踪策略研究（英文）

在轨卫星或者空间碎片数量的增多,是对空间目标地基自动观测的一个挑战。尽管北美防空司令部编目管理了绝大多数直径超过10 cm的空间物体,但由于轨道摄动,空间目标的位置信息(基于6个轨道根数)依然非常重要,并需要定期更新。在过去的几十年里,配备电子传感器的现代地基光电望远镜已广泛用于天体测量领域。然而,这种设备的跟踪性能主要取决于空间目标的大小和亮度。这些目标所在的天文图像会有不同的背景;而且,在基于凝视模式的短曝光实时观测过程中,运动目标和背景恒星在不同的信噪比下显示为类似的点扩散函数,难以辨认。本研究是为了实现对非高斯和动态背景的高灵敏度检测和跟踪能力的提高,并具有简单的系统机制和出色的计算效率。为突破该限制,将重点放在利用状态估计技术对微小卫星和暗弱目标进行跟踪上。提出一种基于神经网络的自适应运行高斯平均算法,用以从恒星背景及干扰下提取运动的空间目标。该方法随后被集成到了一个检测前跟踪框架中。该框架利用基于蒙特卡洛的粒子滤波跟踪空间目标。三段来自亚太地基光学空间目标观测系统(APOSOS)图像序列被用来对该跟踪策略进行评估。实验结果表明,该方法能够达到满意的跟踪性能。     

Exploring the database of a soil environmental survey using a geo-self-organizing map: A pilot study

A model integrating geo-information and self-organizing map (SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals (As, Cd, Cr, Hg, and Pb) was built by the regular grid sampling in Hechi, Guangxi Zhuang Autonomous Region in southern China. Auxiliary datasets were collected throughout the study area to help interpret the potential causes of pollution. The main findings are as follows: (1) Soil samples of 5 elements exhibited strong variation and high skewness. High pollution risk existed in the case study area, especially Hg and Cd. (2) As and Pb had a similar topo-logical distribution pattern, meaning they behaved similarly in the soil environment. Cr had behaviours in soil different from those of the other 4 elements. (3) From the U-matrix of SOM networks, 3 levels of SEQ were identified, and 11 high risk areas of soil heavy metal-contaminated were found throughout the study area, which were basically near rivers, factories, and ore zones. (4) The variations of contamination index (CI) followed the trend of construction land (1.353) > forestland (1.267) > cropland (1.175) > grassland (1.056), which suggest that decision makers should focus more on the problem of soil pollution surrounding industrial and mining enterprises and farmland.

     

Consumption of Ecosystem Services in Laos

The exponential increase of ecosystem utilization has instigated a serious conflict between ecosystem services and residents’ needs. The Belt and Road Initiative has greatly influenced Laotian production and living, and the scientific assessment of the consumption of ecosystem services in Laos is important for exploring residents’ influence on the ecosystem. Based on data for the Laotian consumption of agricultural products, fruits and livestock products during 1961-2013, normalized by either harvest index or feed conversion ratio, this study draws three main conclusions. 1) Ecosystem service consumption in Laos is centered on the consumption of farmland, forestry and grassland ecosystem services, which account for over 80%, over 10% and under 2%, showing downward, upward and constant trends, respectively. The consumption of these ecosystem services shows a trend of increasing first, then fluctuating, and finally increasing. 2) The consumption of ecosystem services in Laos was characterized by the mode of “dominance of consumption of the farmland ecosystem services” from 1961 to 2008, and the mode of “balanced development of consumption of farmland, forest and grassland ecosystem services” from 2008 to 2013, with a trend of transformation from the former into the latter. 3) The formation and change in the consumption mode of Laotian ecosystem services have been affected by both supply and trade. Laos developed agriculture mainly during the period from 1961 to 2008, forming the mode of “dominance of consumption of the farmland ecosystem services”. This development benefited from the enriched varieties of imports as well as the increased value of trade and import volume. However, the consumption of ecosystem services in Laos after 2008 changed from the mode of “dominance of consumption of the farmland ecosystem services” to one of “balanced development of consumption of farmland, forest and grassland ecosystem services”. This study provides an empirical reference for research on the consumption of ecosystem services.     

The Scientific Conceptual Framework for Ecological Quality of the Dryland Ecosystem: Concepts,Indicators, Monitoring and Assessment

The dryland ecosystem is the dominant component of the global terrestrial ecosystem since arid regions occupy 45% of the earth’s land area and feed 38% of the world's population. The stability and sustainable development of the dryland ecosystem are critical for achieving the millennium development goal (MDG) in the arid and semiarid areas. However, there is still no scientific guideline for measuring and conserving the health and productivity of dryland ecosystems. Therefore, the purpose of this study is to develop the scientific conceptual framework of defining, monitoring and evaluating the ecological quality of dryland ecosystems. The ecological quality of dryland ecosystems is represented by a system of comprehensive indicators that are each extracted from the ecological elements, and structural and functional indices of the ecosystem. These indicators can be monitored by integrating satellites and unmanned aerial vehicles with ground-based sensor networks at the scale of either observational sites or regional scales. Finally, the ecological quality can be evaluated by evaluation models based on the normalized index values and their thresholds. This paper presents a conceptual framework for monitoring and evaluating the ecological quality of drylands, which provides a way of advancing the monitoring, diagnosis, and evaluation of the ecological quality of the dryland ecosystems.     

Experimental,Numerical and Simplified Theoretical Model Study for Internal Solitary Wave Load on FPSO with Emphasis on Scale Effect

Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaveraged velocities induced by ISWs are used for the velocity-inlet boundary. Three scale ratio numerical models λ=1, 20 and 300 were selected, which the scale ratio is the size ratio of numerical models to the experimental model.The comparisons between the numerical and former experimental results are performed to verify the feasibility of numerical method. The comparisons between the numerical and simplified theoretical results are performed to discuss the applicability of the simplified theoretical model summarized from the load experiments. Firstly, the numerical results of λ=1 numerical model showed a good agreement with former experimental and simplified theoretical results. It is feasible to simulate the ISWs loads on FPSO by the numerical method. Secondly, the comparisons between the results of three scale ratio numerical models and experimental results indicated that the scale ratios have more significant influence on the experimental horizontal forces than the vertical forces. The scale effect of horizontal forces mainly results from the different viscosity effects associated with the model’s dimension.Finally, through the comparisons between the numerical and simplified theoretical results for three scale ratio models, the simplified theoretical model of the pressure difference and friction forces exerted by ISWs on FPSO is applied for large-scale or full-scale FPSO.     

南大西洋两岸盆地海相烃源岩特征与控制因素

南大西洋两岸盆地漂移期层系油气资源十分丰富,通过对两岸重点盆地漂移期主力烃源岩发育层位、生烃潜力、识别特征和分布范围对比分析,明确两岸发育早、晚两套主力海相烃源岩。其中,晚期的赛诺曼-土仑阶海相烃源岩分布范围较广。整体上,两岸北段和赤道段盆地漂移期主力烃源岩地化指标优于中段和南段盆地,西非一侧海域盆地烃源岩地化指标优于南美一侧盆地。在对重点钻井的矿物元素化验分析、沉积相和古地理分析基础之上,总结了局限海湾的古地理背景和沉积相带类型控制优质海相烃源岩发育程度和分布范围的规律,并进一步指出南大西洋两岸北段和赤道段盆地漂移期成熟生烃灶平面分布范围内的深水沉积砂体是主要有利勘探方向,以找油为主,中段含盐盆地内紧邻盐微盆的漂移期深水沉积砂体勘探潜力次之。     

长江三角洲蓝图重绘的基础科学问题:进展与未来研究

在全球气候变化和人类活动影响加剧的背景下,作为河口海岸重要子系统的三角洲正在发生快速变化。长江三角洲地处长江入东海交汇处,是中国最重要的经济核心区之一,对邻近区域乃至整个长江经济带经济社会发展都起着重要作用。由于全球变暖、海面上升和强烈人类活动引发了三角洲系统状态转换,因此以往基于恒定系统状态而获得的有关长江三角洲的认识已不能满足未来需求,迫切需要对未来海面变化、极端事件、流域与河口工程影响下的三角洲物质循环条件、物理过程、地貌冲淤演化、源-汇格局调整等科学问题进行深入研究。在三角洲系统行为、未来演化趋势的预测能力建设中,应重视从海面到海底的综合立体观测系统的发展,以获取关键数据;基于三角洲系统的时、空演化特征,建立三角洲本征态和衍生态的谱系理论。未来需针对系统状态转换而调整原先的经济社会发展模式,以便保护自然资源、重建生态系统,更好地支撑长江经济带发展,重绘长江三角洲发展蓝图。     

改进的最小曲率迭代法在重力剖面数据插值中的应用

基于将约束点也作为待解算结点的思想,对传统最小曲率迭代法进行改进。改进后的方法在待解算结点周围存在约束点时,避免了根据约束点与待解算结点之间的不同关系需要进行分类推导的复杂过程,同时也避免了因使用泰勒展开式进行分解造成的精度损失,提高了解算精度。     

北斗三号组网卫星数据质量分析及单系统定轨精度初步评估

选取2018-01-23起10 d内16个iGMAS测站观测数据,对北斗三号卫星的观测数据质量及BDS单系统精密定轨精度进行评估。初步结果表明,老信号B1I、B3I北斗三号卫星的信噪比略强于二号卫星,噪声与多路径基本相当,均在0.1 m量级,新卫星不存在星内多路径偏差。新信号B1C/L1/E1频点GPS信噪比最强,Galileo和BDS卫星相当,B2a/L5/E5a和B2b/E5b各系统基本相当;噪声及多路径方面,B1C/L1/E1频点GPS优于BDS、Galileo卫星0.1 m量级,B2a/L5/E5a和B2b/E5b各系统基本相当,均在0.1 m量级,新信号中北斗三号卫星星内多路径偏差基本消失。单系统精密定轨试验中,分别进行有/无GEO卫星策略、太阳光压模型ECOM 五/九参数策略的比较,并使用卫星激光测距数据进行独立检核。初步结果表明,有GEO卫星、ECOM五参数光压模型的定轨精度最好,C19号卫星7个重叠弧段的平均定轨精度在沿迹向、法向、径向的精度分别为32 cm、16 cm、8 cm,与试验卫星的定轨精度基本相当。     

贵州省市州域经济差异的时空演变

区域经济差异一直是国内外研究的热点,本文以贵州省9个市州为研究单位,选取10个经济发展指标,运用全局主成分分析,结合GIS技术,测度了贵州省9个市州域2006～2016年10年来经济差异的时空演变。结果表明:贵州省各市州区域经济内部差异明显,经济增长存在较强空间关联性,上升区与下降区均集中分布;各项指标数值相对比较大的地区,最终得分不一定高。