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31.
整数模糊度参数的快速检索算法 总被引:1,自引:0,他引:1
GPS快速定位中,由于模糊度参数之间的强相关性,模糊度参数置信区间定义的检索区域比相应的置信椭球大得多。本文通过模糊度参数向量的正交变换,定义出包含模糊度参数置信椭球的最小正交多面体,借助在其中构造的均匀正交网格点,找出置信椭球中的所有整数模糊度参数向量。该方法显著地减少了整数模糊度参数的检索范围,提高了计算效率。 相似文献
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针对当前建筑群组相似模式检索中空间域和谱域相似度量方法的模型泛化能力较弱,且空间信息利用不足的问题,本文提出了一种基于变分图卷积自编码器的相似检索模型。首先,利用最小生成树构建建筑群组图数据,并将建筑物描述特征嵌入图节点中,实现建筑群组模式的定量化表达;其次,在变分图卷积自编码器重参数化模块中,加入四维超混沌系统与高斯分布融合生成的混合噪声,通过增加采样的随机性来提高模型的泛化能力;然后利用图卷积和池化代替全连接层以保留更多的空间信息,并对低维特征编码进行处理,获得建筑群组的模式特征编码;最后,利用余弦距离来获得待检索建筑群组与模式编码库中建筑群组之间的相似度,从而实现建筑群组模式的相似检索。实验结果表明,该模型能够有效提取建筑群组的模式特征,通过无监督学习实现端到端的建筑群组相似模式检索,为建筑群组模式的自动分类与相似检索提供了新的思路和方法。 相似文献
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汪玉琼 《物探化探计算技术》1998,20(4):373-375
本文是一份数据入库方法及检索应用的总结。文中主要介绍了利用计算机进行化探数据入库及检索应用。入库数据可进行标准图幅检索、任意区域检索等多条件数据检索,检索出的数据可作多种化探数据处理,并绘制等值线图、色块图等图形及图像。此项技术经济投入少,能及时检索数据、处理数据、显示及打印图形、图像,以指导找矿及勘探,具有一定的实用价值。 相似文献
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Wind plays an important role in hydrodynamic processes such as the expansion of Changjiang (Yangtze) River Diluted Water (CDW), and shelf circulation in the Changjiang estuary. Thus, it is essential to include wind in the numerical simulation of these phenomena. Synthetic aperture radar (SAR) with high resolution and wide spatial coverage is valuable for measuring spatially inhomogeneous ocean surface wind fields. We have collected 87 ERS-2 SAR images with wind-induced streaks that cover the Cbangjiang coastal area, to verify and improve the validity of wind direction retrieval using the 2D fast Fourier transform method. We then used these wind directions as inputs to derive SAR wind speeds using the C-band model. To demonstrate the applicability of the algorithms, we validated the SAR-retrieved wind fields using QuikSCAT measurements and the atmospheric Weather Research Forecasting model. In general, we found good agreement between the datasets, indicating the reliability and applicability of SAR- retrieved algorithms under different atmospheric conditions. We investigated the main error sources of this process, and conducted sensitivity analyses to estimate the wind speed errors caused by the effect of speckle, uncertainties in wind direction, and inaccuracies in the normalized radar cross section. Finally, we used the SAR-retrieved wind fields to simulate the salinity distribution off the Changjiang estuary. The findings of this study will be valuable for wind resource assessment and the development of future numerical ocean models based on SAR images. 相似文献
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ABSTRACT Satellite-based observations provide great opportunities for improving weather forecasting. Physical retrieval of atmo spheric profiles from satellite observations is sensitive to the uncertainty of the first guess and other factors. In order to improve the accuracy of the physical retrieval, an ensemble methodology was developed with an emphasis on perturbing the first guess. In the methodology, a normal probability density function (PDF) is used to select the optimal profile from the ensemble retrievals. The ensemble retrieval algorithm contains four steps: (1) regression retrieval for original first guess; (2) perturbation of the original first guess to generate new first guesses (ensemble first guesses); (3) using the ensemble first guesses and nonlinear iterative physical retrieval to generate ensemble physical results; and (4) the final optimal profile is selected from the ensemble physical results by using PDE Temperature eigenvectors (EVs) were used to generate the pertur- bation and generate the ensemble first guess. Compared with the regular temperature profile retrievals from the Atmospheric InfraRed Sounder (AIRS), the ensemble retrievals RMSE of temperature profiles selected by the PDF was reduced between 150 and 320 hPa and below 400 hPa, with a maximum improvement of 0.3 K at 400 hPa. The bias was also reduced in many layers, with a maximum improvement of 0.69 K at 460 hPa. The combined optimal (CombOpt) profile and a mean optimal (MeanOpt) profile of all ensemble physical results were improved below 150 hPa. The MeanOpt profile was better than the CombOpt profile, and was regarded as the final optimal (FinOpt) profile. This study lays the foundation for improving temperature retrievals from hyper-spectral infrared radiance measurements. 相似文献
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