Kalligrammatid Lacewings from the Upper Jurassic Daohugou Formation in Inner Mongolia, China

A new species, referable to a new genus, is erected, and named the Sinokalligramma jurassicum gen. et sp. nov. It is the second finding of kalligrammatids in the Daohugou Formation. The origin and migration of the family Kalligrammatidae are discussed. The geological age and stratigraphic correlation of the Daohugou and Karabastau Formations are briefly reviewed and reassessed.     

Measurements of ^222Rn and ^220Rn with a Large Size Collector of Radon Progeny

Radon concentrations in high background radiation areas in the south are higher than those of others in China, especially ^220Rn concentration is significantly high. Therefore, measurements of ^222Rn and ^220Rn concentrations should be carried out there. This paper introduces a large size collector of radon progeny and its applications. The collector is a sheet of polyvinyl chloride fiber with electrostatics of (-500 V)-(-700 V). Its size (60 mm in diameter) is larger than those of others (26 mm in diameter) that work with the same principle. The collector is more effective to adsorb radon progeny than most of others. The equipment of ZnS(Ag) Scintillation Counting System is available for large size collectors to detect radon progeny. Therefore, its sensitivity of measurement is higher than that of others. According to the different half lives of radon progeny, and based on both theory and experiments, a formula for discrimination and calculation of ^222Rn and ^220Rn concentrations is deduced. The ^222Rn and ^220Rn concentrations were surveyed with electrostatic collectors of radon progeny on the campus of commercial school and some other areas in Hainan, southern China. Neither ^222Rn nor ^220Rn concentration was found significantly high. However, several faults underground were delineated. The collector is also used to study radon transportation. Results indicate that radon changes regularly with date when it has transported for a certain distance. Velocities of radon migration in the four media are quite different. Radon migrates more quickly in vertical tube than in the horizontal tube.     

弹性波逆时偏移及其成像条件

从弹性波动方程出发,推导了二维各向同性介质情况下弹性波逆时传播的高阶差分格式,实现了弹性波在数值空间中的逆时延拓。从程函方程出发,采用逆时差分格式求取网格空间中各点的直达波旅行时,以此作为弹性波逆时偏移的成像条件(激发时间成像条件),实现多波多分量资料的逆时偏移。文中给出了几个典型模型的理论记录的偏移结果,数值试验表明,逆时偏移能够使地表接收到的波场准确归位,提高资料处理的精度。     

Estimating the windward slope profile of a barchan dune

A new theoretical scheme is presented to model the shape of a sand dune at equilibrium that does not require iterative calculations of the interaction between the wind flow and topography. The model is constructed by incorporating theory based on aerodynamics into a grain‐scale model that estimates the shear velocity at the dune crest through the calculation of the sand trapping efficiency of the slipface in the lee of the dune. Published field data, collected in southern Peru, California and southern Morocco, show that as a dune becomes higher the windward slope becomes steeper. For the model proposed, the wind flow over a dune was first assumed to be similar to that over a Gaussian hill. By further assuming a fixed shear velocity on the level surface, the windward slope angle and migration speed of dunes in southern Peru can be explained. To comply with all available data, some aspects are still open to further investigation. However the theoretical insight presented herein implies that the upper limit of dune height may be greater in windier environments.     

伊利石测年在焉耆盆地油气成藏时期研究中的应用

油气藏成藏时期的确定是进行油气藏勘探与评价的重要工作内容之一。也是揭示成藏过程的有效途径，利用伊利石测年确定油气成藏期，能够得出其绝对年龄，因而受到人们重视，运用自生伊利石同位素年龄测定的原理和方法及自生伊利石同位素年龄资料对焉耆盆地博湖坳陷油气藏成藏时期及油气运移时期进行了分析，最后对自生伊利石同位素测年存在的问题和措施进行了有益的探讨并克服了以往只能根据地质综合研究定性确定油气藏成藏时期及油气运移时期问题，为定量确定油气藏成藏时期以及油气运移时期提供了科学的方法。     

Seismic response of adjacent dense and loose saturated sand columns

Compaction or densification of loose saturated soils has been the most popular method of reducing earthquake related liquefaction potential. Such compaction of a foundation soil is only economical when limited in extent, leading to a case of an ‘island’ of improved ground (surrounded by unimproved ground). The behavior of the densified sand surrounded by liquefied loose sand during and following earthquakes is of great importance in order to design the compacted area rationally and optimize both safety and economy. This problem is studied herein by means of dynamic centrifuge model tests. The results of three heavily-instrumented dynamic centrifuge tests on saturated models of side-by-side loose and dense sand profiles are discussed. The test results suggest the following concerns as relates to ‘islands’ of densified soil: (1) there is a potential strength degradation in the densified zone as a result of pore pressure increase due to migration of pore fluid into the island from the adjacent loose liquefied ground; (2) there is a potential for lateral deformation (sliding) within the densified island as the surrounding loose soil liquefies.     

Effects of wet meadow riparian vegetation on streambank erosion. 1. Remote sensing measurements of streambank migration and erodibility

We quantified how rates of stream channel migration in a montane meadow vary as a function of the riparian vegetation community. The South Fork of the Kern River at Monache Meadow, located in California's southern Sierra Nevada range, supports two distinct types of vegetation: a dry meadow community dominated by sagebrush and non‐native grasses (xeric scrub and meadow), and a wet meadow community dominated by rushes and sedges (hydric graminoids). We measured rates of lateral stream migration for dry versus wet meadow reaches from aerial photographs spanning a 40‐year period (1955–1995). While stream migration rates averaged only 0·24 ± 0·02 m a^?1 in the wet meadow, the dry meadow channel migrated an average of 1·4 ± 0·3 m a^?1. We used a linear model of meander migration to calculate coefficients that characterize bank migration potential, or bank erodibility, independent of channel curvature. These calculations demonstrate that, at Monache Meadow, banks without wet meadow vegetation are roughly ten times more susceptible to erosion than banks with wet meadow vegetation. Where stream bank heights consistently exceed 1 m, low water availability creates riparian habitats dominated by dry meadow vegetation. Thus, channel incision may reduce bank stability not only by increasing bank height, but also by converting banks from wet meadow to dry meadow vegetation. Copyright © 2002 John Wiley & Sons, Ltd.     

石油二次运移物理模拟及运移特征分析

石油二次运移是一个复杂的地质过程,本文通过利用饱和地层水的低孔低渗储层砂岩来进行石油二次运移模拟实验,初步研究了此过程的变化特征。研究表明 :在静水条件下,石油水平运移带的平均含油饱和度达 15 %~2 5 %。运移过程中饱和烃、芳烃及非烃与含油饱和度呈正相关性。在运载层物性相差较小的情况下,运移驱动力是运移效率的主导因素。在孔渗性好的运载层,含油饱和度容易达到稳定。     

焉耆盆地三工河组储层流体包裹体形成期次分析

焉耆盆地三工河组流体包裹体具有丰度低、个体小的特征,并以液态烃相包裹体为主,主要分布在石英颗粒的溶孔或溶缝当中。结合盆地成岩作用和有机质演化历史分析,认为它们形成于侏罗纪晚期的以压溶和溶蚀作用为特征的晚成岩作用阶段。包裹体均一温度呈双峰型分布,具有 10 1~ 110℃和 12 1~ 130℃两个区间,结合焉耆盆地的埋藏史和盆地的热史,这两个温度区间分别对应于晚侏罗世和侏罗纪末期。包裹体组份特征分析也证实该地区存在两期包裹体,并且包裹体组分主要是在烃源岩低成熟阶段形成的。可以认为,焉耆盆地三工河组储层的流体包裹体主要是在晚侏罗世烃源岩的低成熟阶段和侏罗纪末期烃源岩的成熟阶段形成。     

集群系统进程迁移机制研究

进程迁移是提高集群系统整体性的基础机制之一。作者在本文中首先详细地论述了进程迁移机制的关键技术，然后描述了在集群系统中PVM迁移原理，接着重点分析了在Linux集群中进程迁移算法的设计，最后对集群系统中与进程迁移机制相关的技术做了讨论。