北京地区一次小雪天气过程造成路面交通严重受阻的成因分析

通过对2001年12月7日降雪天气过程与历史同期降雪过程的比较以及对降雪过程中不同物理介质路面温度变化的观测研究表明,"12·7"北京地区路面交通严重受阻是由于特殊的时间、特殊的城市和特定的路面状况等多种非气象因素与"落雪成冰"的气象环境条件共同作用造成的.这种气象环境条件的形成是由于降雪过程中,雪面、路面与近地面大气之间复杂的热量交换和相互影响的结果:降雪开始时,由于雪片的吸热作用,造成路面和紧贴地面的大气温度下降,而近地面层气温的下降,反过来造成路面温度进一步降低,在两者的共同作用下,地表落雪迅速形成冰面.冰面的反射作用又进一步加速了气温、尤其是近地面层气温的下降,不断降低的气温使得冰层硬度加强、厚度迅速增加.作者还通过天气诊断和数值模拟分析,对这次降雪天气过程的物理机制进行了简单的讨论,认为这次降雪天气很可能是由对流层中层快速移动的高空槽、地面弱倒槽和近地面层弱的偏东气流共同影响而产生的.     

山东栖霞庄子金矿床地质特征

山东栖霞庄子金矿床产于郭家岭花岗岩和磁山花岗岩与胶东群的接触带，矿石以石英脉型为主，金品位高且发育明金。庄子金矿矿床地质研究表明，矿区存在两组控矿构造，一组为NNE向，另一组为近EW向。金矿床与郭家岭花岗岩期后热液有成因联系。成矿作用划分为5个阶段，最主要的金矿化阶段为多金属硫化物阶段和细粒黄铁矿—石英阶段。     

海洋沉积物中吸附态轻烃的气相色谱分析

改进了可用于少量样品的酸解烃脱气装置，建立了毛细管柱气相色谱测定海洋沉积物中吸附态轻烃(酸解烃、顶空间轻烃)的方法，并用于大批量实际样品分析，结果良好。讨论了分析柱的优化以及定量分析等问题。方法的检测限(释放气)为0．048～0．78μL／L，精密度(RSD，n=10)为0．52％～0．98％。     

The inhibitory effect of Negev Desert loess soil on the fast germinating caryopses of Schismus arabicus (Poaceae)

This study examined dispersal units, caryopsis size groups, the inhibitory effect of loess soil on germination and the rate of germination of Schismus arabicus caryopses. Germination of small batches of the seeds from the large, long-lasting soil seed bank of S. arabicus contributes to its success as a very common annual plant in large areas of the Negev, under the unpredictable small amounts and distribution of rain. The lower the percentage of germinating caryopses on local loess soil, and the faster the speed of germination (from 4 h) of caryopses that do germinate, the higher is the chance of plants survival to reproduce.     

Statistical analysis of two 3-D registration and modeling strategies

The paper deals with the registration and modeling of multiple 3-D profile maps acquired from different viewpoints by light striping. We analyze the propagation of measurement and calibration errors to the registration parameters and further to the reconstructed model of the scene consisting of planar patches. The analysis is performed for two strategies. In the first strategy, the maps are registered simultaneously using the Levenberg–Marquardt method to update the registration parameters and the model computed afterwards while in the second one, the maps are registered sequentially against the model reconstructed up till then using the method of unit quaternions to update the registration parameters. Our statistical analysis thus combines the registration and modeling steps, and in registration, we determine the corresponding points either on the parametric domains of the maps or as closest points in 3-D using the information from the parametric domain to restrict the search for the closest points. We also point out the precise estimation of the covariance matrix of the solution given by the Levenberg–Marquardt method. We illustrate the results of our analysis with real data from a scale model of an urban area.     

Application of light hydrocarbons (C4–C13) to oil/source rock correlations:: a study of the light hydrocarbon compositions of source rocks and test fluids from offshore Mid-Norway

Relatively little work has been published on the correlation between the light hydrocarbon distributions in reservoir fluids and their proposed source rocks [Philippi, G. T. (1981)]. The aim of our work was to study this relationship in detail for samples from Mid-Norway. The main source rocks offshore Mid-Norway are the marine shales of the Late Jurassic Spekk Formation and the coals and paralic shales of the Early Jurassic Åre Formation. Reliable light hydrocarbon (C₄–C₁₃) data for source rock samples were acquired by thermal extraction-GC of the source rocks. Of these, notably the hydrocarbons in the C₆–C₈ range (routinely measured in test fluids) were used to discriminate between the Spekk and Åre Formation samples. A total of twenty-six samples from the Spekk Formation and twenty-four samples from the Åre Formation at different maturity levels and facies were analyzed. In general, the two source rock types differ in their light hydrocarbon composition by the presence of relatively more aromatics and cyclohexanes in the Åre samples, while the Spekk samples are richer in cyclopentanes and acyclic hydrocarbons. We show that source rock facies is a more important indicator of light hydrocarbon composition than maturity variation. Differences in the chemical composition, which can be used to discriminate between the two source rocks, were supported by differences in the carbon isotope composition of individual components of the same fraction, as determined by GHM-IR-MS analysis of eleven samples. Further, the light hydrocarbon compositions of reservoir fluids (oils and condensates) were compared with those for the source rock(s). Sixty-six gas chromatograms of oils and condensates, representing most of the known petroleum accumulations in Mid-Norway, were collected. Of these, five oil samples were selected for detailed isotopic analysis of individual components (GC-IR-MS). When using a classification scheme based on data from sediment samples, data for the light hydrocarbon fraction of oils and condensates indicate that the Spekk Formation is the dominant source for most of the fields from Mid-Norway, with a significant contribution from the Åre Formation being detected principally in one field. Differences in the chemical composition of the C₆–C₈ fractions were supported by differences in the carbon isotope composition of individual components, which also discriminate between the oils. Although the classification diagrams used in this study are based on source rock data from Mid-Norway, the method can be applied to other areas, providing that the diagrams are calibrated with source rock data from the area of interest.     

悬浮物浓度对水下光照和初级生产力的影响

采用太湖湖泊生态系统研究站生态实验室的模拟生态槽进行水动力模拟实验研究(1999年5月8日～6月24日),探讨了水动力的扰动引起悬浮物的增加、改变水下光强的分布,并由此造成了初级生产力的变化.结果表明,无论是静止还是小水流、大水流状态,水下光强随深度都是按指数规律衰减;在静止状态下,槽水清澈见底,光衰减系数为1m-1左右,到小水流和大水流时,由于动力的扰动、悬浮物浓度的增加,光学衰减系数增加到2m-1和4m-1左右,真光层深度也由最初的4m降到2m、1m;对光学衰减系数、真光层深度与悬浮物浓度进行线性和幂函数回归,发现他们之间的相关性很好,反映了风浪扰动引起水中悬浮物增加是改变水下光照分布的主要原因;在静止状态下,由于槽水清澈,强光作用下表面存在光抑制现象,最大初级生产力出现在04～06m,其他情形光抑制很弱或基本上不存在,最大初级生产力出现在0～02m.     

轻非水相液体在地下环境中的运移特征与模拟预测研究

通过自行设计制备的二维砂箱模拟轻非水相液体(LNAPL)在湿润多孔介质中的渗漏,得出LNAPL在地下环境中的入渗、迁移及分布规律,并利用多相流体理论对其污染机理进行分析.在实验基础上建立模型来预测渗漏的基本特征,即渗流带中污染锋面扩展速度和透镜体的最终形状,预测结果与实测结果较为接近.这种预测模型对控制和治理地下水中LNAPL污染是至关重要的.     

由多频射电爆发探讨太阳白光耀斑的起源问题

从射电运动Ⅳ型爆发的特征和多频射电爆发开始时序的分析可以看出这个伴生的白光耀斑（ Ｗ Ｌ Ｆ） 和射电爆发同是由低日冕的加速电子激活,可能通过非热电子沉降能量于色球层, 产生了色球层压缩波, 又经二步能量传输过程在上光球层导致 Ｗ Ｌ Ｆ。通过对共生事件的分析, 并与已知的二类 Ｗ Ｌ Ｆ的观测特征作了比较, 提出该 Ｗ Ｌ Ｆ 可能属于二类的混合型, 并提出 Ｗ Ｌ Ｆ 可能存在射电辐射的必要条件     

Diatom-based transfer functions for western Quebec lakes (Abitibiand Haute Mauricie): the possible role of epilimnetic CO2 concentration in influencing diatom assemblages

Surficial sediments from 76 lakes from two western Quebec regions(Abitibi and Haute Mauricie) were sampled to identify the relationships betweendiatoms and environmental variables. Because the two regions containedradically different diatom communities, we then investigated which factors maybe responsible for the large community discrepancies in the two nearbygeographical areas. Standard lake chemistry variables showed little differencesbetween the regions, although epilimnetic light regimes were slightly lower inAbitibi. Nevertheless, lakes of the two regions with similar light regimes andchemistry still showed a clear separation in their diatoms, implying that otherimportant factors are influencing assemblages. We found that the calculatedconcentration of CO₂ in the open water can explain some of thediscrepancy in diatom assemblages. A pCCA constrained to the concentration ofCO₂ with alkalinity and pH as covariables explained 12.5% of speciesvariance and was significant. Given the lack of a relationship between DOC andCO₂, and because the lakes are heavily supersaturated withCO₂ in the calibration set, lake-to-lake variations inCO₂ concentrations are likely due to groundwater inputs; thepossibility that this environmental variable may be influencing diatomcommunities might allow, in some cases, the reconstruction of historicalchanges in groundwater inputs to lakes. Finally, new calibration models werebuilt in Quebec by using weighted averaging partial least square(WA-PLS) techniques in order to infer pH, CO₂, TP, TN, and, DOC fromdiatom assemblages preserved in the surface sediments.