次天气尺度与中尺度正、斜压模演变揭示的武汉暴雨过程

利用滤波原理提取出大气流场中的次天气尺度和中尺度信息，再把大尺度和中尺度水平风场分别分解为正压分量（垂直平均）和斜压分量（扰动）流场。对1998年7月21～22日发生在武汉附近的强暴雨过程进行了次天气尺度与中尺度流场正、斜压分量演变特征的分析。结果表明：次天气尺度与中尺度流场正压分量的演变与此次强暴雨的酝酿、发展和消亡具有内在的联系；次天气尺度与中尺度流场高层200hPa斜压分量很强，低层850hPa正压分量很强；次天气尺度与中尺度流场斜压性占主导地位，随着暴雨的发展，中尺度流场的正压性减弱而斜压性进一步增强，而次天气尺度流场的正压性增强而斜压性减弱。以上结论对于揭示中尺度暴雨过程发生发展的本质有一定的意义。     

Bench–shelf system dynamic characteristics and their effects on equipment and contents

Economic losses during past earthquakes are strongly associated with damage and failure to nonstructural equipment and contents. Among the vast types of nonstructural elements, one important category, is scientific equipment in biological or chemical laboratories. These equipment are often mounted on heavy ceramic bench‐tops of bench–shelf systems, which in turn may amplify the dynamic motions imposed. To investigate the seismic response of these types of systems, a series of shake table and field experiments were conducted considering different representative bench and shelf‐mounted equipment and contents. Results from shake table experiments indicate that these equipment are generally sliding‐dominated. In addition, the bench–shelf system is observed to be very stiff and when lightly loaded, has a fundamental frequency between 10 and 16 Hz. An approximate 50% reduction in the first and second fundamental frequencies is observed considering practical loading conditions. Insight into a broader range of system response is provided by conducting eigenvalue and time history analyses. Non‐linear regression through the numerical data indicate acceleration amplification ratios Ω range from 2.6 to 1.4 and from 4.3 to 1.6, for fixed–fixed and pinned–pinned conditions, respectively. Both the experimental and numerical results support the importance of determining the potential dynamic amplification of motion in the context of accurately determining the maximum sliding displacement of support equipment and contents. Copyright © 2006 John Wiley & Sons, Ltd.     

基于主成分分析的遥感图像模拟真彩色融合法

对不同空间分辨率、时间分辨率和波谱分辨率的遥感图像进行综合、高效的利用,是遥感应用的关键问题之一.基于主分量变换法,提出了基于主成分分析的模拟真彩色融合法.该方法不仅具有主成分分析融合法的光谱波段选择灵活和光谱信息损失小等优点,同时该方法还可获得逼真的自然色彩的融合图像,提高了图像的融合效果.利用QuickBird全色和多光谱数据进行了试验,并与色彩空间变换法(HIS)、比值变换融合法和乘积变换法等传统方法,在定性和定量两个方面进行了比较分析.结果表明,新方法很好的保留了多光谱影像的光谱信息,提高了空间细节的表现能力,是一种有效实用的遥感图像融合方法.     

The simulation of heat and water exchange in the boreal spruce forest by the land-surface model SWAP

All previous versions of a physically based land-surface model SWAP have assumed for simplicity that vegetation is fully covered by snow during the cold season. Such assumption is reasonable only for the regions dominated by short vegetation or for warm climates where snow processes are absent. The major goals of this paper are (i) modification of the latest version of SWAP by incorporation of tall vegetation into the cold-season parameterizations to make the model applicable for simulating heat and water transfer within a boreal forest biome and (ii) validation of the modified version using the data from a forested catchment located in the boreal zone. Modification of SWAP required to parameterize radiative and turbulent exchange between the forest crown and forest floor, partitioning snowfall between interception by the canopy (in doing so, snow interception differs from rain interception) and falling to the ground, formation of snow cover on the forest crown and forest floor including snow accumulation (both in solid and liquid fractions), snow evaporation, and snowmelt. The advanced model was validated using a set of hydrometeorological data measured during 18 years (1966–1983) at the Tayozhniy catchment (covered by boreal spruce forest), Valdai, Russia. Simulations of annual and monthly snow/rain interception, daily runoff at the catchment outlet, snow density, snow depth, snow water equivalent, soil water storage in three layers (0–20, 0–50 and 0–100 cm), and monthly evapotranspiration from the catchment were compared with observations. Analysis of the results of validation shows that the new version of the model SWAP reproduces the heat and water exchange processes occurring in mid-latitude boreal forest quite reasonable.     

On the Components of Indigenous Population Change

The 2001 census count of Indigenous Australians produced an intercensal change in numbers that cannot be explained by demographic processes alone. Using census and vital registration data, this paper unravels the components of such change and provides new insight into Indigenous population dynamics. In particular, it establishes the first estimates of proximate determinants of fertility, and extends mortality analysis by examining the components of low Indigenous life expectancy. Results show that demographic factors account for only 69 per cent of population change. Of these components, national Indigenous fertility is found to be below replacement level, while lack of convergence between Indigenous and non-Indigenous mortality remains. As Indigenous socio-economic circumstances are spatially diverse, the paper also explores the geography of demographic processes using data for 36 ATSIC regions and capital city/balance of State classifications. This reveals continued high fertility across parts of north Australia and an indication that mortality levels are associated with degree of urban residence.     

起算数据误差影响下的方差分量估计

探讨了起算数据误差影响下的方差分量估计方法,给出了顾及起算数据误差影响时求解方差分量估值的方程组及单位权中误差估值的计算公式,并通过实例说明了当起算数据误差较大时,它们对方差分量估计的影响是不应忽略的。     

热泉热液金矿化中嗜热微生物——有机质的地球化学作用

本文主要通过对热泉热液金成矿过程中的热泉水化学成分和组分的分析,得出泉水中金与氮磷硫、氟硅碳两组组分有很好的相关性。嗜热硫酸盐还原菌能使［Ａｕ（ＨＳ）２］－和［Ａｕ（Ｓ２Ｏ３）２］３－都氧化还原成硫化物,从而使金由热水溶液中沉淀。热泉沉积软泥的有机质中的含硫氨基酸、含硫芳烃也起到了一定的聚金作用。     

合成孔径雷达遥感新技术--InSAR介绍

InSAR是正在发展中的极具潜力的微波遥感新技术。为使广大测绘工作者对它有一个全面了解，本系列讲座将分六部分对InSAR作较为详细的介绍与讨论。作为第一部分，本文将对InSAR的发展历史、技术背景、系统构成与应用情况等方面作总体介绍。     

Response to orthogonal components of ground motion and assessment of percentage combination rules

The effects of horizontal components of ground motion on the linear response of torsionally stiff and torsionally flexible systems, on soft and firm soil conditions, are examined. A one‐story, two‐way asymmetric structural system is used, subjected to uncorrelated ground motion components along their principal directions. Spectral densities for ground accelerations in firm and soft soils are modeled based on recorded data from large intensity Mexican earthquakes. It is shown that for firm soils, in general, these effects are important in the case of torsionally flexible systems that are stiff under translation, or for torsionally stiff systems that are flexible in translation. The percentage combination rules usually specified in seismic design codes are assessed against the dynamic response. Such combination rules can result in overly conservative design forces or underestimated design forces, particularly for torsionally flexible structures. Given the relative magnitude of the response to each ground motion component, it was found that using different percentage values in the combination rules has no significant effect on improving the estimation of the total response. Copyright © 2003 John Wiley & Sons, Ltd.