GPS/Doppler导航随机模型的移动窗口实时估计算法

引进时间遗忘因子和观测冗余度因子,有效地平衡移动窗口内不同时刻的观测数据及其冗余情况对单位权方差估值的贡献,改进单位权方差的移动开窗实时估计算法.采用载噪比模型确定观测权阵,等价权抗差估计方法处理粗差.实测车载GPS/Doppler数据的处理结果表明:采用本文算法显著提高GPS/Doppler的导航精度与可靠性.     

Bromide as a conservative tracer for soil-water studies

The assumption that potassium bromide is a conservative tracer for soil-water studies was tested in a series of batch sorption experiments. Sorption experiments were conducted on soil samples collected from the O, E, and A horizons of the Albemarle soil series near Charlottesville, VA. The experiments were conducted under conditions of differing bromide concentration and filter treatments. Bromide concentrations in soil-solution mixtures were measured through time using an Orion bromide-specific electrode. An analysis of variance of results showed no significant sorption of bromide through time under any concentration level or filter treatment (α = 0·01). No sorption of bromide between different soil horizons could be determined. This work clearly indicates that bromide is conservative under the conditions examined.     

An investigation of analysis of variance as a tool for exploring regional differences in strong ground motions

The statistical technique known as analysis of variance is applied to a large set of European strong-motion data to investigate whether strong ground motions show a regional dependence. This question is important when selecting strong-motion records for the derivation of ground motion prediction equations and also when choosing strong-motion records from one geographical region for design purposes in another. Five regions with much strong-motion data (the Caucasus region, central Italy, Friuli, Greece and south Iceland) are investigated here. For the magnitude and distance range where there are overlapping data from the five areas (2.50 M_s 5.50, 0 d 35 km) and consequently analysis of variance can be performed, there is little evidence for a regional dependence of ground motions. There is a lack of data from moderate and large magnitude earthquakes (M_s > 5.5) so analysis of variance cannot be performed there. Since there is uncertainty regarding scaling ground motions from small to large magnitudes whether ground motions from large earthquakes are significantly different in different parts of Europe is not known. Analysis of variance has the ability to complement other techniques for the assessment of regional dependence of ground motions.     

Helmert方差分量估计严密公式与简化公式等价性的证明

在分析了Helmert方差分量估计严密公式与简化公式迭代收敛结果一些统计性质的基础上,导出了关于收敛结果共同的求解方程,从理论上证明了两种结果的等价性,为使用简化公式提供了依据。     

GPS在轨卫星原子钟的稳定性分析

导航卫星星载原子钟的相位或频率数据,作为导航系统应用研究的基础,将直接影响导航系统时间尺度建立以及定位的精度和准确性。本文针对由IGS官网提供的四种GPS卫星钟的钟差数据,采用修正阿伦方差进行了稳定性分析,得到了一些有益的结论。     

1951—2010年长沙市极端气温事件的变化特征

利用1951-2010年长沙最高和最低气温资料,运用国际上通用的百分位阈值法确定暖日、暖夜和冷日、冷夜数,采用线性倾向估计法和M-K突变检测等方法,研究长沙市60 a来极端气温事件的时空变化特征。结果表明,暖日和暖夜数分别以3.48个.（10a）-1和3.06个.（10a）-1的速率显著增加,冷日和冷夜数分别以-2.13个.（10a）-1和-1.78个.（10a）-1的速率显著减少,白天增暖幅度大于夜间增暖幅度。研究还表明,阶段性特征明显,近60 a来暖日和冷日、冷夜数发生了明显的突变。暖日数增加秋季最显著,春季次之;暖夜数增加夏季最显著,冬季次之。冷日（夜）数减少的季节主要是春季和冬季;四季都在变暖,但以春季、冬季变暖最明显。7月暖日（暖夜）数增加最显著,4月和2月冷日（冷夜）数减少最显著。     

A Comparison Study of the Contributions of Additional Observations in the Sensitive Regions Identified by CNOP and FSV to Reducing Forecast Error Variance for the Typhoon Morakot

The sensitive regions of conditional nonlinear optimal perturbations (CNOPs) and the first singular vector (FSV) for a northwest Pacific typhoon case are reported in this paper. A large number of probes have been designed in the above regions and the ensemble transform Kalman filter (ETKF) techniques are utilized to examine which approach can locate more appropriate regions for typhoon adaptive observations. The results show that, in general, the majority of the probes in the sensitive regions of CNOPs can reduce more forecast error variance than the probes in the sensitive regions of FSV. This implies that adaptive observations in the sensitive regions of CNOPs are more effective than in the sensitive regions of FSV. Furthermore, the reduction of the forecast error variance obtained by the best probe identified by CNOPs is twice the reduction of the forecast error variance obtained by FSV. This implies that dropping sondes, which is the best probe identified by CNOPs, can improve the forecast more than the best probe identified by FSV. These results indicate that the sensitive regions identified by CNOPs are more appropriate for adaptive observations than those identified by FSV.     

Spatial distribution and influencing factors of interprovincial terrestrial physical geographical names in China

The interprovincial terrestrial physical geographical entities are the key areas of regional integrated management. In this paper, we analyzed the spatial patterns of the interprovincial terrestrial physical geographical names (ITPGN) from three aspects: numerical features, spatial variance and spatial agglomeration. The influencing factors of the distribution of ITPGN and the implications for the regional management were further discussed. GIS technology was used to visualize the distribution of ITPGN, analyze the spatial agglomeration and the influencing factors of ITPGN. A total of 11,325 ITPGN, including 4243 water ITPGN and 7082 terrain ITPGN, were extracted from the database of “China’s Second National Survey of Geographical Names (2014-2018)”, and the mountain geographical names were the largest type in ITPGN. Hunan Province had the largest number of the names in China, and Shanghai had the smallest number of the names. The spatial variance of the terrain ITPGN was larger than that of the water ITPGN, and the ITPGN showed a significant agglomeration phenomenon in the southern part of China. In addition, the relative elevation and the population had an impact on the distribution of the ITPGN. The largest number of the geographical names occurred in the regions where the relative elevation was between 1000-2000 meters, and where the population was between 40-50 million. Based on the analysis, it was suggested that the government should take the ITPGN as management units, optimize management strategies based on the characteristics of different types of ITPGN, strengthen the naming of unnamed interprovincial terrestrial physical geographical entities and balance the interests in the controversial ITPGN. This study demonstrated that GIS and spatial analysis techniques were useful for the research of ITPGN and the results could provide targeted management suggestions to realize coordinated development in the interprovincial regions.     

自动与人工雨量计观测降水量的差异分析

通过对东胜国家基准气候站自动与人工两年观测数据资料的实时对比,分析判断出自动观测雨量计相对人工观测雨量计来说,误差率比较稳定。     

测流不确定度的插值方差估计法

目前,测流不确定度通过误差试验或通过经验数值来确定,但这些方式存在着工作量大或不确定估计不足等局限性。为解决此问题,对基于实测数据和统计理论的插值方差估计法在不同测流条件下进行了验证,选取白河、襄阳和沙洋3个流量站进行了实测数据的不确定度分析,同时对白河站进行了Monte Carlo试验,比较插值方差估计法得到的不确定度与真实误差的差异。结果表明,插值方差估计法能较好地反映水位变化的影响,插值方差估计法所得到的不确定度与真实测流误差的相关系数达0.64,与断面水位变化的Spearman相关系数达0.79,高、中水位情况下插值方差估计法的不确定度估计结果较为合理,低水位情况下偏高。