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11.
Remote sensing of the earth with satellites yields datasets that can be massive in size, nonstationary in space, and non‐Gaussian in distribution. To overcome computational challenges, we use the reduced‐rank spatial random effects (SRE) model in a statistical analysis of cloud‐mask data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board NASA's Terra satellite. Parameterisations of cloud processes are the biggest source of uncertainty and sensitivity in different climate models’ future projections of Earth's climate. An accurate quantification of the spatial distribution of clouds, as well as a rigorously estimated pixel‐scale clear‐sky‐probability process, is needed to establish reliable estimates of cloud‐distributional changes and trends caused by climate change. Here we give a hierarchical spatial‐statistical modelling approach for a very large spatial dataset of 2.75 million pixels, corresponding to a granule of MODIS cloud‐mask data, and we use spatial change‐of‐Support relationships to estimate cloud fraction at coarser resolutions. Our model is non‐Gaussian; it postulates a hidden process for the clear‐sky probability that makes use of the SRE model, EM‐estimation, and optimal (empirical Bayes) spatial prediction of the clear‐sky‐probability process. Measures of prediction uncertainty are also given.  相似文献   
12.
概念整合网络与新闻漫画的语义构建   总被引:3,自引:0,他引:3  
文章首先回顾了认知语言学中Fauconnier和Tunner等人提出的概念整合理论的主要概念和基本思想,然后运用这一理论探讨了新闻漫画的语义构建,并选取三副网络新闻漫画进行了个案分析,旨在说明概念整合理论的认知解释力.分析表明,概念整合理论具有解释在线构建非传统意义上的新颖意义的特性,能够为新闻漫画的语义构建、创新和理解提供一个新的理论视角.  相似文献   
13.
We propose an algorithmic framework for computing sparse components from rotated principal components. This methodology, called SIMPCA, is useful to replace the unreliable practice of ignoring small coefficients of rotated components when interpreting them. The algorithm computes genuinely sparse components by projecting rotated principal components onto subsets of variables. The so simplified components are highly correlated with the corresponding components. By choosing different simplification strategies different sparse solutions can be obtained which can be used to compare alternative interpretations of the principal components. We give some examples of how effective simplified solutions can be achieved with SIMPCA using some publicly available data sets.  相似文献   
14.
二维奇异问题的有限元方法是实际中经常会遇到的一类问题,对其解决有重要意义.本文讨论二维奇异非稳态问题的有限元方法,证明了弱解的存在唯一性,并给出有限元解的加权L2-模估计.  相似文献   
15.
16.
We explored the extent to which projections of future old-age mortality trends differ when different projection bases are used. For seven European countries, four alternative sets of annual rates of mortality change were estimated with age–period log-linear regression models, and subsequently applied to age-specific all-cause mortality rates (80+) in 1999 to predict mortality levels up to 2050. On average, up to 2050, e80 is predicted to increase further by 2.33 years among men and 4.03 years among women. Choosing a historical period of 25 instead of 50 years results in higher predicted gains in e80 for men but lower gains for women. Choosing non-smoking-related mortality instead of all-cause mortality leads to higher gains for women and mixed results for men. In all alternatives there is a strong divergence of predicted mortality levels between the countries. Future projections should be preceded by a thorough study of past trends and their determinants.  相似文献   
17.
Assuming that both birth and death rates are density and time dependent, a diffusion approximation of the generalized birth and death process has been considered in this paper to obtain a suitable stochastic population model describing the population size and its moments. A simple method of estimating the parameters of the model Is discussed. The predictions of the expected size of the population, and the variance are made and compared with the corresponding census figures as well as with another deterministic projection series made for the corresponding period.  相似文献   
18.
论述了一种成功运用于122cm背投式彩色投影电视机阴极射线管(CRT)中的磁聚焦电子枪。该枪采用了预聚焦发射系统和磁聚焦主透镜构成的双聚焦系统。经测试发现,当阴极电流为0.5~1.0mA时,其上屏束斑直径仅为0.065~0.080mm。  相似文献   
19.
傩面具有着独特的艺术魅力,通过追述傩文化的发展变化,梳理各个历史时期民众审美心态之变化与傩面具艺术特色变迁的关系,论述其功能由悦神到娱人的表现特征及原因,以加深对这一民间艺术瑰宝的认识.  相似文献   
20.
Following the release of the Intergenerational Report, the Australian Treasury identified the levers to address the economic effects of demographic ageing as ‘the three Ps’: population, participation and productivity. To date, the first ‘P’, population, has been treated as an exogenous factor, with the common view being that there is very little that the government can do to supplant demographic ageing. Focusing upon labour supply, this paper shows how variation in Australia’s underlying demography can significantly alter Australia’s future labour supply. Although governments cannot redirect the cohort flow component of population ageing, much can be achieved in promoting growth of the labour supply by maintaining or increasing fertility (in the longer term), or increasing targeted migration (in the short to medium term). This paper also decomposes the relative role of cohort flow, changing demography and changing labour force participation on the growth of the labour supply over the past 20 years. Over this period, the entry of the baby boom generation (cohort flow) and increased labour force participation of women accounted for almost all of the growth in the labour force. Changing demography had very little effect. However, Australias future labour supply will not include a large increase in cohort flow (as caused by the baby boomers) or a very large increase in female labour force participation. Regardless of the assumptions used, labour supply growth will be considerably lower in the next and subsequent 20 years, when compared to the previous 20.  相似文献   
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