遥感技术在核监测活动中的应用

近几年来，世界上一些国家尤其是空间应用技术较发达的国家，充分利用地球观测卫星等遥感技术，对核设施及其运行状况和周围相应辅助设备进行了大量的研究，在核安全防护监测中取得了良好的成果，本文简要介绍了一些国家用于监测核设施的观测卫星的发展，以及在核安全监测活动中的应用。     

龙陵县勐糯铅锌矿深部巷道稳定性数值模拟研究

根据勐糯铅锌矿巷道工程条件,采用phase2有限元软件构建巷道数值计算模型,对比分析200m中段结晶灰岩、千枚岩巷道无支护情况下应力场、位移场、塑性变形区等情况,为巷道支护方法优化提供参考。计算结果表明,该矿山沿脉巷道走向普遍为南北方向,与原岩应力场中最大主应力σ₁为近似垂直关系,对巷道稳定性较为不利。巷道开挖后,应力重新分布,硐壁围岩应力降低,应力向围岩深部转移,出现巷道围岩深处局部区域应力集中。200m中段结晶灰岩围岩巷道无支护时不会发生大面积垮塌或严重的巷道变形,围岩为千枚岩时,将发生大面积垮塌和较严重的巷道收敛变形,若及时采取支护措施可在一定程度上暂时控制巷道变形,但后期要多次对断面进行修整并重新支护来减少围岩变形的影响。     

Public housing and migration: a multi-level modelling approach

"This paper...[analyzes] the distance moved by one-year migrants using a multi-level modelling approach. Controlling for a range of socio-economic variables, derived from the 1991 British Census Sample of Anonymised Records (SAR), at both the individual and area level, the distance moved by household heads in public, privately rented and owner-occupied housing within Britain is assessed.... It is confirmed that migrants in public housing are less likely to migrate long distances than owner-occupiers and that the proportion of public housing in a SAR area, and the absolute reduction in public housing in a SAR area between 1981 and 1991, does not have a significant effect on the distance that in-migrants have moved."     

Inter-provincial migration in Spain: temporal trends and age-specific patterns

"This paper provides interpretation of the changing patterns of internal migration in Spain at the inter-provincial scale, and new analysis of age-specific migration during the 1980s using a 10% sample of anonymised records from the 1991 census. Schedules of age-specific gross migration rates are constructed and classified according to their shape and level relative to the national schedule, and the relationships between in-migration and out-migration rates are examined for four selected age groups to demonstrate how aggregate patterns of inter-provincial migration conceal a wide diversity of age specific experience."     

Hydrocarbon contamination of coastal sediments from the Sfax area (Tunisia), Mediterranean Sea

The coastal area off the city of Sfax (730,000 inhabitants), well-known for fisheries and industrial activities, receives high inputs of organic matter mostly anthropogenic. Eighteen stations were selected in the vicinity of the direct discharge of industrial sewage effluents in the sea in order to study the spatial distribution of the organic contamination. Surface sediments sampled in the shallow shelf were analysed for hydrocarbons by Fourier transform infrared spectroscopy, gas chromatography and gas chromatography/mass spectrometry. Total hydrocarbon distributions revealed high contamination as compared to other coastal Mediterranean sites, with an average concentration of 1865 ppm/dry weight sediment. Gas chromatographic distribution patterns, values of unresolved mixture/n-alkane ratio and distributions of steranes and hopanes confirmed a petroleum contamination of the Arabian light crude oil type. Biogenic compounds were also identified with a series of short-chain carbon-numbered n-alkenes in the carbon range 16-24.