共查询到20条相似文献,搜索用时 46 毫秒
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在静止卫星红外云图上,用实际大气廓线的响应权重取代标准大气的响应权重,对利用时间序列差分法反演出的晴空区风矢,进行高度重新指定。然后对台风个例高度重新指定前、后的晴空区风矢进行了误差统计检验和分析,最后利用三维中尺度同化系统WRF\|3DVAR进行了敏感性试验。结果表明:利用实际大气廓线的权重响应进行高度指定优于标准热带大气廓线,晴空风矢高度主要分布在600~900 hPa之间;经高度重新指定后各高度层上的晴空区风矢的均方根差和标准差明显减小,风速偏差集中。同化经过高度重新指定的晴空区风矢能够减小台风路径预报误差。因此,对晴空区风矢进行高度重新指定能够改善晴空风矢产品的质量。 相似文献
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虚拟现实中的三维卫星云图技术研究 总被引:2,自引:0,他引:2
使用卫星云图对云仿真是虚拟现实视景仿真中的一项新技术.以卫星云图原始数据为数据源,从中提取定位和定标信息,文章从坐标和投影变换、云图数字高程模型(DEM)生成和三维仿真实现三个主要方面详细介绍了虚拟现实中三维卫星云图的实现方法.生成云图DEM是三维化的关键,这里用墨卡托投影生成规则云图网格,用大地主题解算计算距离,用火箭外弹道学的方法来计算高程. 相似文献
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首先介绍了云模型这种新兴的处理不确定性问题的工具,提出了一种基于云模型的层次聚类方法.该方法将原始数据集划分为许多小簇,然后分别用云模型来表示这些簇,再通过云综合的方法对这些小簇进行逐层合并,实现对数据集的聚类.将该方法应用于2006-2007年中国及周边亚太地区FY-2C卫星云图的聚类分析,得出不同降水类型的云图特征.最后以2006年7月6日FY-2C中国分区图所示地区对应的FY-2C卫星云图进行降水类型分类为实例,得到不同降水天气对应的云图辐射亮度值特征,并利用分类结果对实况云图进行降水天气的判别,结果表明该方法对大暴雨天气的判别效果良好. 相似文献
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本文针对台风卫星云图的具体特点,采用一种利用迭代模型并结合台风云系面积特征的分割方法,对台风卫星云图进行分割,取得了满意的效果。 相似文献
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空间电磁场三维可视化技术研究 总被引:1,自引:0,他引:1
为研究战场中典型电磁环境及其对低空巡航导弹的影响,将虚拟现实技术和三维场数据可视化方法结合在一起,通过在战场场景中重构三维等值曲面,把战场中典型电磁场计算模型得到的大量点数据转变成形象直观的,实时交互的三维图像信息,全面表现了战场的地理环境、电磁场的分布等情况,为战场决策和控制提供了依据和帮助. 相似文献
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本文针对台风卫星云图的具体特点,采用一种利用迭代模型并结合台风云系面积特征的分割方法,对台风卫星云图进行分割,取得了满意的效果。 相似文献
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云层背景是红外仿真成像中重要的一部分,论文通过分析云层的基本特性、红外特性,结合云层自身辐射、反射辐射、散射辐射,然后基于卫星云图,对图像的像素点进行处理,根据白天、夜晚等不同情况仿真得到红外云层图像.仿真结果显示,仿真图像整体上达到了红外云图的效果. 相似文献
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European Community policy and the market 总被引:1,自引:0,他引:1
C. Lloyd 《Journal of Computer Assisted Learning》1993,9(2):86-91
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven. 相似文献
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融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。 相似文献
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David Poole 《Computational Intelligence》1989,5(2):97-110
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given. 相似文献
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Watts S. Humphrey 《Annals of Software Engineering》2002,14(1-4):39-72
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical. 相似文献
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基于复小波噪声方差显著修正的SAR图像去噪 总被引:4,自引:1,他引:3
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。 相似文献
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R. NOSS 《Journal of Computer Assisted Learning》1987,3(1):2-12
Abstract This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development. 相似文献
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C. Xiang 《控制理论与应用(英文版)》2014,12(3):217-217
正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where 相似文献
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《浙江大学学报:C卷英文版》2014,(7)
正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere. 相似文献
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Alan V. Di Vittorio 《Remote sensing of environment》2009,113(9):1948-2750
The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm2, BIAS = 0.143 µg/cm2, RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm2, BIAS = − 0.992 µg/cm2, RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm2, BIAS = − 2.12 µg/cm2, RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data. 相似文献
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Philip Marks 《Cryptologia》2018,42(1):1-80
This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G). 相似文献