基于误差分布的震源区波速比反演及其应用:乳山震群源区介质性质变化研究

本文利用误差分布和概率统计分析改进了波速比计算方法.对于震源位置相对集中的震群活动,对台站震相到时进行两次差分,通过对差分后的震相数据对进行二维高斯分布拟合,可以稳健地估计震群活动震源区波速比.该方法充分利用了不同台站Pg、Sg到时差的所有信息,其优势是不需要地震事件的震源位置,并且不依赖震源区以外的速度变化,有效消除了震源区到台站的传播路径效应的影响;相对于传统的平均波速比,本文方法得到的震源区波速比,更能真实地反映震源区介质的性质.我们将该方法应用到2013—2016年的乳山震群,结果显示:震源区波速比的变化与震群活动过程密切相关,波速比的变化反映了序列活动的阶段性特征.     

TOVS水汽及演的误差分析及其订正

该文利用同步物理反演法以６小时数值预报场为背景场对１９９２年１月份ＮＯＡＡ－１２卫星垂直探测（ＴＯＶＳ）资料进行了大气参数反演，并对水汽反演误差进行了检验和分析．以常规观测作为检验的标准，检验结果按３条轨道统计，发现反演的相对湿度平均误差与背景场的误差密切相关，均为负值；在高层和高纬度，误差绝对值随高度的增加而增加，随纬度的升高而增加；误差的日际变化在高层比较稳定，低层振动较大．对反演误差进行订正后的结果表明，在５００ｈＰａ以上反演均比背景质量要好，尤其轨道Ａ所有层次上订正后的反演比背景场好．     

How can the uncertainty in the natural inflow regime propagate into the assessment of water resource systems?

The Canadian Rocky Mountain headwaters support the water resource systems of the Canadian Prairies. Significant variations in natural headwater contributions have been observed due to warming climate. Projecting future natural headwater flows under climate change effects, however, has large uncertainty. First, there are difficulties in climate modeling and downscaling in alpine regions. Second, streamflow modeling in mountainous areas is extremely challenging. There is therefore a need to understand the effects of uncertainty in the natural inflow regime, and in particular how this translates into uncertainty in representing the state and the outflow of water resource systems. Considering the Oldman River basin in Alberta, Canada, we synthesized different inflow regimes based on site/inter-site properties of the historical inflow regime. The water resources system was then conditioned on the synthesized inflow regimes to identify the mechanisms of error propagation from the headwater streamflows to the water allocations. The results show that the response of the water resource system to the uncertainty in the generated inflow regime depends on the system state, flow condition and the component of interest. Generally, the response of the reservoirs to the uncertainty in the estimated inflow regime is more significant in dry years, in particular during low flow conditions. The response at the system outlet is rather different, as the propagation of the headwater uncertainty is more significant during high flow conditions. Also, similar inflow estimates in terms of error and uncertainty may result in different error and uncertainty estimates in the simulated outflows; therefore, lower bias and uncertainty in estimating the regional inflow regime does not necessarily mean lower bias and uncertainty in simulating the streamflow at the outlet of the system. Our results provide improved understanding of uncertainty propagation through complex water resource systems, but also portray the need for better climate and hydrological modeling in the Rocky Mountains for improved water management in the Canadian Prairies, particularly in the face of uncertain climate futures. This will be crucial if the natural headwater inflows decline and/or the system faces drought conditions.     

EGNOS数据处理模型与实例

主要分析研究了EGNOS系统测试采用的误差修正模型和定位保护精度算法,并通过比较一次实测静态数据单点解算和差分解算的不同效果来说明误差模型的修正效果和保护精度算法的有效性。事实证明EGNOS系统数据处理采用的误差修正模型效果是明显的,采用的定位保护精度算法是有效的。     

河北省月平均气温分布式模型应用研究

利用1971-2000年河北省及周边126个气象台站的常规观测资料,应用月平均气温分布式模型,实现了起伏地形下河北省月平均气温的分布式模拟,制作出100 m×100 m分辨率的气温空间制图。结果表明：坝上高原和河北省平原地区地势平坦,气温分布比较均匀;燕山山脉和太行山山脉地形复杂,气温受局地地形影响显著。在角度相同的坡地上,偏南坡与偏北坡的气温差异1月>10月>4月>7月。在同一时段,偏南坡与偏北坡的气温差异随坡度的增加而增加;张家口地区多盆地河谷,气温分布均匀且较周围地区高;月平均气温分布式模型在河北省具有良好的模拟精度、时间维和空间维模拟性能及山地扩展性能。     

基于Gauss-Markov卡尔曼滤波的电离层数值同化现报预报系统的构建-以中国及周边地区为例的观测系统模拟试验

本文给出了一个基于Gauss-Markov卡尔曼滤波的电离层数据同化系统的初步构建和试验结果.我们选择中国及周边地区部分涉及电离层观测的台站(包括子午工程台站、中国地壳形变网和部分IGS台站)作为观测系统进行模拟试验,背景场利用IRI模式,观测值则由NeQuick模式计算得到.我们的同化结果表明,采用Kalman滤波算法,把部分斜TEC同化到背景模式当中,能够获得较好的同化结果,说明我们设计的算法可行、所选择的各种参数比较合理,采用Gauss-Markov假设进行短期预报也取得了较合理的结果.本项研究经过进一步的改进和完善,可以用来对中国地区的电离层进行现报和短期预报,一方面满足相关空间工程应用,另一方面可以提升现有观测系统的科学意义.     

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Error analysis of satellite attitude determination using a vision-based approach

Improvements in communication and processing technologies have opened the doors to exploit on-board cameras to compute objects’ spatial attitude using only the visual information from sequences of remote sensed images. The strategies and the algorithmic approach used to extract such information affect the estimation accuracy of the three-axis orientation of the object.This work presents a method for analyzing the most relevant error sources, including numerical ones, possible drift effects and their influence on the overall accuracy, referring to vision-based approaches. The method in particular focuses on the analysis of the image registration algorithm, carried out through on-purpose simulations. The overall accuracy has been assessed on a challenging case study, for which accuracy represents the fundamental requirement. In particular, attitude determination has been analyzed for small satellites, by comparing theoretical findings to metric results from simulations on realistic ground-truth data. Significant laboratory experiments, using a numerical control unit, have further confirmed the outcome.We believe that our analysis approach, as well as our findings in terms of error characterization, can be useful at proof-of-concept design and planning levels, since they emphasize the main sources of error for visual based approaches employed for satellite attitude estimation. Nevertheless, the approach we present is also of general interest for all the affine applicative domains which require an accurate estimation of three-dimensional orientation parameters (i.e., robotics, airborne stabilization).     

误差限的病态总体最小二乘解算

大地测量和地球物理数据解算中时常会涉及病态问题的处理。基于客观的观测精度,利用设计矩阵与观测向量的误差限制,一方面降低了病态性对求解造成的波动;另一方面避免引入正常数,从而提高整个解算过程的客观性与可靠性。计算表明,本文提出的方法可以有效地处理病态总体最小二乘问题,并且具有较高的稳定性。     

粗大误差在船坞围堰安全施工监测中的运用与分析

船坞监测数据对船坞围堰的正常施工起着非常重要的作用,但是由于各种不正确的因素导致监测数据与实际情况不符,而这些异常测值不能通过直观的方法进行剔除,从而对船坞围堰的安全施工监控产生较大的影响,必须进行判断和处理。分别介绍了3σ（拉伊达）、Grubbs（格罗布斯）、Dixon（狄克逊）3种常用排除粗大误差的准则,并应用于具体的船坞围堰安全施工监测。结果表明,这些准则能快速、方便、有效地排除异常测值,为船坞围堰安全施工提供帮助。