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761.
廖华 《大地测量与地球动力学》1996,(1)
讨论了多个粗差的定位方法──“向前、向后”探测法,并编制了相应的平差计算程序,对鲜水河断裂带上具有代表意义的虾拉沱小测边网和老乾宁小测边网进行了粗差探测与自动剔除,结果表明效果显著,方法简单、有效。 相似文献
762.
对2012—2013年GRAPES_TYM模式热带气旋路径预报结果进行检验,结果表明:模式对所有类型路径预报在24h、48h和72h预报时效的平均距离误差分别为94.3km,143.7km和260.8km,并且存在偏北的系统性偏差;对于南海TC,模式对TC移向预报较实况偏右,移速误差较小,移向偏差是路径偏差的主要原因;另外统计得到模式对TC移向的预报偏差与对其环境引导气流预报偏差有密切的关系,以1213号台风"启德"为例进一步通过移向误差诊断方程探讨了环境引导气流预报偏差(包括环境风场预报偏差、环境引导气流半径偏差及环境引导气流厚度偏差)对TC移向偏差的影响,而环境引导气流预报误差来源与模式对大尺度天气系统、TC大小及强度的预报偏差有关。 相似文献
763.
为了解和掌握上级指导产品对石家庄市空气质量预报的适用性,进一步提高石家庄市空气质量预报的准确性,利用国家气象中心(NMC)、北京区域气象中心(BJ)和河北省气象局(HB)空气质量预报产品,对石家庄市夏季4种主要污染物PM_(2.5)、PM_(10)、O_3和SO_2的预报进行了对比检验,结果表明:1)NMC对4种污染物的预报效果均逊于HB和BJ的,对PM_(10)、PM_(2.5)和SO_2的预报值明显较实况偏大,尤其在发生重污染天气时,对PM_(10)和PM_(2.5)的空报率高达90%以上;2)HB对PM_(10)和SO_2的预报效果好于BJ的,对SO_2的预报值与实况值均在一个等级范围内,发生重污染天气时,对PM_(10)的预报效果好于BJ的,预报值更接近于实况,但对重污染向优、良转折天气的预报值偏高;3)BJ预报PM_(2.5)和O_3的效果好于HB的,对O_3的0级误差级别预报准确率高达90.5%,对PM_(2.5)优到轻度污染等级的预报效果较好,但对重污染天气的预报值低于实况。 相似文献
764.
765.
以日本宇宙航空研究开发机构(JAXA)提供的精密星历为参考,对QZSS MICHIBIKI卫星发布的实时轨道和钟差数据进行了评估。数值结果表明,QZSS MICHIBIKI卫星的实时轨道精度优于11 cm,实时钟差优于0.56 ns;GPS卫星的实时轨道精度优于5 cm,实时钟差优于0.4 ns。通过比较得知,QZSS MICHIBIKI卫星的实时轨道和钟差精度明显低于GPS卫星。 相似文献
766.
Model errors offset by constant and time-variant optimal forcing vector approaches(termed COF and OFV, respectively)are analyzed within the framework of El Nio simulations. Applying the COF and OFV approaches to the well-known Zebiak–Cane model, we re-simulate the 1997 and 2004 El Nio events, both of which were poorly degraded by a certain amount of model error when the initial anomalies were generated by coupling the observed wind forcing to an ocean component. It is found that the Zebiak–Cane model with the COF approach roughly reproduced the 1997 El Nio, but the 2004 El Nio simulated by this approach defied an ENSO classification, i.e., it was hardly distinguishable as CP-El Nio or EP-El Nio. In both El Nio simulations, substituting the COF with the OFV improved the fit between the simulations and observations because the OFV better manages the time-variant errors in the model. Furthermore, the OFV approach effectively corrected the modeled El Nio events even when the observational data(and hence the computational time) were reduced.Such a cost-effective offset of model errors suggests a role for the OFV approach in complicated CGCMs. 相似文献
767.
Digital elevation model (DEM) source data are subject to both horizontal and vertical errors owing to improper instrument operation, physical limitations of sensors, and bad weather conditions. These factors may bring a negative effect on some DEM-based applications requiring low levels of positional errors. Although classical smoothing interpolation methods have the ability to handle vertical errors, they are prone to omit horizontal errors. Based on the statistical concept of the total least squares method, a total error-based multiquadric (MQ-T) method is proposed in this paper to reduce the effects of both horizontal and vertical errors in the context of DEM construction. In nature, the classical multiquadric (MQ) method is a vertical error regression procedure, whereas MQ-T is an orthogonal error regression model. Two examples, including a numerical test and a real-world example, are employed in a comparative performance analysis of MQ-T for surface modeling of DEMs. The numerical test indicates that MQ-T performs better than the classical MQ in terms of root mean square error. The real-world example of DEM construction with sample points derived from a total station instrument demonstrates that regardless of the sample interval and DEM resolution, MQ-T is more accurate than classical interpolation methods including inverse distance weighting, ordinary kriging, and Australian National University DEM. Therefore, MQ-T can be considered as an alternative interpolator for surface modeling with sample points subject to both horizontal and vertical errors. 相似文献
768.
769.
针对当前大多UAV搭载单个数码相机进行摄影测量时存在的实际问题,详细分析了多面阵组合相机的结构设计。以飞思IQ180相机为例,通过比较双拼组合相机与三拼组合相机的组合方式及各自成像特点,对其相机的组合参数以及相应关系进行探讨;并通过对拼接误差与高程精度的影响分析,得出组合相机对高程精度的提高、增大像幅、提高作业效率等方面有明显的优越性,对多面阵数码相机的设计具有一定的指导意义。 相似文献
770.
Adrian C. Prelipcean Gyözö Gidofalvi Yusak O. Susilo 《International journal of geographical information science》2016,30(9):1763-1784
ABSTRACTRooted in the philosophy of point- and segment-based approaches for transportation mode segmentation of trajectories, the measures that researchers have adopted to evaluate the quality of the results (1) are incomparable across approaches, hence slowing the progress in the field and (2) do not provide insight about the quality of the continuous transportation mode segmentation. To address these problems, this paper proposes new error measures that can be applied to measure how well a continuous transportation mode segmentation model performs. The error measures introduced are based on aligning multiple inferred continuous intervals to ground truth intervals, and measure the cardinality of the alignment and the spatial and temporal discrepancy between the corresponding aligned segments. The utility of this new way of computing errors is shown by evaluating the segmentation of three generic transportation mode segmentation approaches (implicit, explicit–holistic, and explicit–consensus-based transport mode segmentation), which can be implemented in a thick client architecture. Empirical evaluations on a large real-word data set reveal the superiority of explicit–consensus-based transport mode segmentation, which can be attributed to the explicit modeling of segments and transitions, which allows for a meaningful decomposition of the complex learning task. 相似文献