埃文斯目视日晕光度计测量原理研究

埃文斯目视日晕光度计（Evans Visual Sky Photometer,EVSP）是应用于日冕仪选址的重要仪器,从20世纪40年代一直使用至今,它为现代日晕光度计的定标提供了参考标准。通过使用云南天文台现存的一架EVSP研究了它的工作原理,并重点介绍了所利用的简易定标方法。给出了国际现有的多台EVSP日晕亮度定标曲线。由于EVSP内部光学元件反射率和透过率,以及中性渐变光楔的光学密度等存在未知的时间缓变特点,因此利用这种新定标手段可以高效经济地获得各自的定标曲线。     

Late Quaternary landscapes in Central Australia: sedimentary history and palaeoecology of Puritjarra rock shelter

Puritjarra rock shelter provides a long record of late Quaternary vegetation in the Australian arid zone. Analysis of the sedimentary history of this rock shelter is combined with reanalysis of charcoal and phytolith records to provide a first‐order picture of changing landscapes in western Central Australia. These show a landscape responding to increasing aridity from 45 ka with deflation of clay‐rich red palaeosols (<45 ka) and sharp declines in grassland and other vegetation at 40–36 ka, and at the beginning of the Last Glacial Maximum (LGM) (24 ka). Vegetation in the catchment of the rock shelter recovered after 15 ka with expansion of both acacia woodland and spinifex grasslands, registering stronger summer rainfall in the interior of the continent. By 8.3 ka re‐vegetation of local palaeosols and dunes had choked off sediment supply to the rock shelter and the character of the sediments changed abruptly. Poaceae values peaked at 5.8 ka, suggesting the early–mid Holocene climatic optimum in Central Australia is bracketed between 8.3 and 5.8 ka. Local vegetation was disrupted in the late Holocene with a sharp decline in Poaceae at 3.8 ka, coinciding with an abrupt intensification of ENSO. Local grasslands recovered over the next two millennia and by 1.5 ka the modern vegetation appears to have become established. Copyright © 2009 John Wiley & Sons, Ltd.     

青藏高原多年冻土区地温监测结果分析

Ground temperatures monitored at four observation sites in permafrost regions on the Tibetan Plateau was analyzed. It was found that the ground temperature at the depth of 12～20 m increased 0.2～0.4 K and the permafrost thickness decreased 4～5 m from the base in Xidatan Site from 1975 to 1989; and the ground temperature at the depth of 6～15 m increased 0.2～0.4 K in Kunlun Pass Site from 1982 to 1997. Contrast observations show that a sand cover, 15～20 cm in depth, can result in a ground temperature decrease of 0.1～ 0.2 K in MS66 Site; and a removal of vegetation can result in a ground temperature decrease of some 0.2 K in Hoh Xil Site. The monitor demonstrates that many factors that control permafrost developing have duality, e.g., sand and vegetation are able to increase or decrease the ground temperature. These factors, in conjunction with permafrost behaviour, play different roles under different conditions. Therefore, it is necessary to study, understand and evaluate permafrost and its engineering geological properties taking the viewpoint of dynamic variation.     

一种用于突发性场地污染模拟的解析模型

为了及时有效地应对各种突发性环境污染事故,有必要开发一种简单实用、适于各类型污染物的场地污染数学模型。通过污染事故发生后污染物在包气带、饱和带迁移转化的概化,建立了污染物运移的自由入渗模型以及降雨入渗模型并给出各自相应的解析解。无降雨时,考虑污染物在重力作用下随包气带向下渗透的作用,建立一维垂直入渗模型。有降雨时,考虑污染场地(包气带)中污染物迁移和转化的对流作用、扩散作用及挥发、生物降解、吸附、根系吸收等作用,建立包气带剖面二维溶质运移模型和饱和带平面二维溶质运移数学模型。建模过程中,假定降雨量的平均分布及土壤质地、水力参数以及有机物成分、种类均相同,同时假定污染物与多孔介质间的作用为线性吸附,植物根系对污染物的吸附遵循一级动力学。基于模型的解析解,实现案例的模拟计算。模拟结果表明:该模型具有适用范围广、模拟高效快捷等优点,能够较准确预测污染发生后污染物在土壤中的动向、到达饱和带的时间以及饱和带中污染物的迁移情况。     

滇西地震预报实验场场区水平形变分析

利用场区各种类型水平形变网数据，求得红河断裂中、北段的区域应力场基本特征是：（１）北区为张性左旋型，（２）中区为压性右旋型，（３）南区为张性右旋型。场区区域应力场基本以张性为主，中区的压性右旋型恰好反映转换区应力场的局部特征。北区主应变积累和速率比南区大，最大处在剑川，而高敏感区在后山定两岭。基于水平形变和应变分析，获得了场区现今主要活动构造参数。利用地震前兆形变信息和震后效应进行了地震震例分析。并对３～５年内的潜在震源区进行了预估。     

Site Effects Study in the Serravalle Village (NE Italy) by Means of Spectral Ratios Analyses Relatively to Multiple Reference Sites

The area of Serravalle, sited in the northern part of the town of Vittorio Veneto (TV), NE Italy, has been the target of a seismic microzonation campaign. 10 seismic stations have been deployed for a 7 months period to record in continuous mode. Three stations were installed on bedrock outcrops and seven on sedimentary sites with variable cover thickness. Spectral analyses have been performed on the collected data-set using the Generalized Inversion Technique (GIT, e.g. Andrews, 1986). In particular, spectral ratios have been calculated for each station relatively to the average of the three reference, bedrock sites. The spectral ratios provide quantitative estimates of the seismic motion amplifications which occur in each of the monitored sites. Two sites show high values of amplification, 5 times larger than signal amplitude at the reference sites, in correspondence of well discernible peak frequencies of 5 Hz. Results for the other stations show smaller amounts of site amplification spreading over a broad range of frequencies. Sites where the highest amplifications were recorded all lie on the left bank of the Meschio River and in areas farther away from its outlet into the plain correlating with the presence of thick layers of Quaternary deposits.     

Richter magnitudes and site corrections using vertical component seismograms

The definition of the Richter Ml magnitude scale is in terms of seismic wave horizontal components recorded on Wood‐Anderson seismographs. However, at many seismograph sites only the vertical component is available, and at sedimentary sites horizontal components are usually significantly amplified, causing complications in the assignment of a magnitude to an earthquake. Because each earthquake can be recorded at a different subset of sites, each subset having a different combination of site amplifications, the assignment of a magnitude is dependent upon the seismograph site combination that records a particular earthquake. Although there is some amplification of the vertical component at sedimentary foundation sites, it is shown that a reduced spread of values of Ml magnitude, consistent with low amplification (bedrock) site magnitudes, can be achieved using the vertical component to compute the magnitude and adding 0.2 to adjust to the Ml magnitude scale (defined in terms of the horizontal components). This presupposes that the sites used by Richter were on bedrock; however, even if this is incorrect, it appears to be a necessary precondition for the world‐wide unification of the Richter scale along with defining the true gain of Wood‐Anderson seismographs rather than accepting the design gain of 2800. Site corrections would be smaller than those established using the horizontal components. Taking into account the use of only the vertical component in the calculation of Ml and including the 0.2 adjustment to the equivalent horizontal component derived magnitude, the expression for the calculation of magnitudes in the Victoria region becomes:

Ml = logA_z ‐ logS_z + 0.9 + logR + 0.0056Re^‐0.0013R

where A_z is the equivalent Wood‐Anderson seismograph displacement amplitude, S_z is the site amplification (vertical component) and R is the hypocentral distance.     

交河故城瞭望台保护加固技术

交河故城遗址是第一批全国重点文物保护单位,瞭望台是交河故城内重要建筑遗址,它的主要病害是表面风化、裂隙密布、洞顶失稳。在分析病害形成机理的基础上,重点研究了生土遗址保护加固的几个关键技术,对掏蚀深度相对于悬挑土体厚度较小的土遗址,当基础掏蚀深度小于块体宽度的30 %时,可不采用砌补技术,只进行表面防风化处理;可选择竹木锚杆、PS-C浆液灌浆加固生土遗址,锚杆的单位锚固力可采用5 kN/m;采用新奥法加固洞顶可较好地保持文物原貌;西部干旱地区采用PS材料对土遗址进行防风化加固时应采用低浓度（小于5 %）、多次渗透的方式,迎风面渗透次数应不少于3遍,背风面应达4～5遍,并应合理选择施工时间。工程实践检验表明,这些保护技术取得了理想的加固效果。