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21.
三叠纪末的印支运动使鄂尔多斯盆地整体抬升,上三叠统延长组顶部遭受到强烈风化及河流侵蚀等地质作用,形成水系广布、沟壑纵横、丘陵起伏的古地貌景观。通过对下侏罗统延安组延10油层组和富县组地层等厚图及延长组顶面起伏图的编绘,基本恢复了前侏罗纪古地貌形态,并将其划分为河谷、斜坡、阶地、高地、平原和潜丘6种古地貌单元。该种古地貌景观严格控制了下侏罗统富县组及延安组下部的沉积相类型、相带展布及压实披盖构造的形成。古河谷的下切作用不仅使延安组下部与油源层的接触距离缩短,又为油气运移提供了良好的通道,如遇到有利的储集体与背斜、鼻隆等构造,即可有机配置、富集成藏;同时地层水特征表明斜坡带保存条件最好。指出前侏罗纪古地貌斜坡带上的坡嘴、阶地及潜丘是勘探延安组下部油藏的有利地带。 相似文献
22.
Experimental data are presented in this paper to study the strain-softening behaviour of sand under plane-strain conditions. K 0 consolidated strain path tests were conducted using a new plane-strain apparatus. The stress–strain behaviour of medium dense sand under plane-strain conditions was characterized. The test results show that the occurrence of pre-failure strain softening under plane-strain conditions is affected by the void ratio, the strain increment ratio and the initial effective confining stress. This is consistent with previous findings established under axisymmetric conditions. However, a pre-failure strain-softening behaviour in plane-strain tests conducted under high-confining stresses may consist of three stages, namely, material softening, banding softening, and ultimate state. This observation is different from that in triaxial tests where banding softening does not normally occur. 相似文献
23.
Experimental results are presented in this paper to study the strain softening behaviour of a marine dredged sand under plane-strain conditions. K0 consolidated drained and undrained tests were conducted using a new plane-strain apparatus to characterize the strain softening behaviour of the sand under plane-strain conditions. For medium dense specimens, strain softening and shear bands were observed to occur under both drained and undrained conditions. For very loose specimens, no shear bands were observed and critical states were reached within the homogeneous deformation region in both drained and undrained tests. Strain softening was observed to occur at small strain for very loose specimens under undrained conditions. Two types of strain softening, the homogenous softening and banding softening, were identified and the conditions for strain softening were established. The results obtained from this study were compared with the studies by Han and Vardoulakis (Géotechnique 41(1):49–78, 1991), Finno et al. (J Geotech Eng ASCE 122(6):462–473, 1996, Géotechnique 47(1):149–165, 1997) and Mokni and Desrues (Mech Cohes-Frict Mat 4:419–441, 1998). 相似文献
24.
25.
The FORMOSAT-3/COSMIC mission is a microsatellite mission for weather forecast, climate monitoring, and atmospheric, ionospheric and geodesy research. This mission is a collaborative Taiwan-USA science experiment to deploy a constellation of six microsatellites in low Earth orbits. The mission life is 2 years with a goal of 5 years. The final mission orbit has an altitude of 750–800 km. Each satellite consists of three science payloads: global positioning system (GPS) occultation experiment (GOX) payload, tiny ionospheric photometer (TIP) and tri-band beacon (TBB). The GOX will collect the GPS signals for the study on atmosphere, ionosphere, and geodesy. The TIP and TBB can provide the electron distribution information for ionospheric research. The deployment of the FORMOSAT-3 constellation and the resulting influence on the occultation sounding distributions are reported. Details are also given on GOX, TIP, and TBB payload operations and the contributions of the Taiwan Science Team. 相似文献
26.
Public health authorities generally recommend annual water-quality monitoring of rural water wells and shock chlorination if coliforms are detected. It is implicitly assumed that shock chlorination is effective in ridding most wells of bacteriological pathogens for months to years. Neither annual monitoring nor shock chlorination was effective in addressing coliform contamination of selected water wells in a small town developed on an alluvial aquifer where septic system effluents are impacting well water quality. Considerable temporal variation in total and fecal coliforms was observed in water wells monitored for a six-month period. Individual wells intermittently met and exceeded the drinking water criteria, indicating annual sampling was insufficient. Shock chlorination of three contaminated wells and their associated distribution systems proved ineffective because colonies apparently originated from outside the wells and reappeared over relatively short time periods (ranging from less than one week up to 21 weeks). The relatively fast and similar rate of recovery of total heterotrophic bacteria suggested they are related to biofilm formation in the wells and not to ground water contamination. 相似文献
27.
应用 1 951- 2 0 0 2年NINO特征指数 (NINO1 +2 ,NINO3 ,NINO4 ,NINO3 .4)和 1 973-1 998年南极海冰北界范围以及 1 950- 2 0 0 1年SODA海洋温度资料。首先分析探讨了在ElNi no期间 ,堆积于赤道东太平洋的异常暖水在南半球的传播途径 ,进而研究了ENSO以及东南太平洋异常海温场与南极海冰之间的关系。结果表明 ,在ElNino期间 ,堆积于赤道东太平洋的异常暖水 ,是沿秘鲁和智利沿岸向极传播。其传播过程持续大约 1年的时间 ,但未发现沿南赤道流的西传现象。ENSO循环过程与南极海冰变化存在一定联系 ,特别是Amundsen Belling shausen海和南极半岛海冰的变化与ENSO暖事件 (ElNino)较为密切。当ElNino事件发生后 ,时滞 2年左右的时间 ,Amundsen Bellingshausen海和南极半岛的海冰将出现明显的减少现象 ,特别是南极半岛的海冰减少最为明显。ElNino事件对南极海冰的影响过程是 ,堆积于赤道东太平洋的大量异常暖水 ,沿南美 (秘鲁和智利 )沿岸近海向极地传播 ,异常暖水的这种向极传播过程将引起近极的海温场出现异常升高 ,最终导致Amundsen Bellingshausen海和南极半岛地区的海冰减少。自 2 0世纪 80年代以来 ,Amundsen Bellingshausen海和南极半岛的海冰出现明显减少的趋势 ,与这一时期的ElNino事件的频繁发生 相似文献
28.
分析了房地产市场发展的状况,提出了对测绘学科教学的要求,对测绘人才的需求,并对高校培养房产测绘人才综合能力提出了具体建议。 相似文献
29.
South China Sea Warm Pool in Boreal Spring 总被引:36,自引:1,他引:36
During the boreal spring of 1966, a warm-core eddy is identified in the upper South China Sea (SCS) west of the Philippines through an analysis of the U.S. Navy’s Master Oceanographic Observation Data Set. This eddy occurred before the development of the northern summer monsoon and disappeared afterward. We propose that this eddy is a result of the radiative warming during spring and the downwelling due to the anticyclonic forcing at the surface. Our hypothesis suggests an air-sea feedback scenario that may explain the development and withdrawal of the summer monsoon over the SCS. The development phase of the warm-core eddy in this hypothesis is tested by using the Princeton Ocean model 相似文献
30.
鲁中碳酸岩中磷灰石同位素地球化学研究 总被引:6,自引:0,他引:6
鲁中地区分布着100多个碳酸岩体,微量元素含量及稀土配分等均与世界典型碳酸岩相近。而碳酸岩的碳氧及斑晶磷灰石的锶、钛同位素组成与典型地幔物质有差异,与富集地幔颇为近似,从而证实在山东地区陆壳下存在富集地幔源区。 相似文献