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951.
952.
Abir Gupta 《Gondwana Research》2000,3(4):529-544
The Permian Gondwana sediments in the Damodar-Koel Valley, Rajmahal and Deoghar basins were deposited on a northwest palaeoslope in broad valleys within uplands (e.g. Aravalli-Vindhyan, Chattisgarh, Chotanagpur and Santhal Parganas upland). The main winds during Permian Period were mostly the westerly winds coming from the northwest low pressure belt in the Tethys, which found no barrier between the Vindhyan and Santhal Parganas uplands and then changing its direction, moving towards east. Frequent storm activity also took place from the northwest Tethyan low pressure belt and followed the same path of wind. Possibly there was a barrier in the form of a dense rain forest or elevated land at the place of East Bokaro coalfield and its adjoining southern part, which acted as a deterrent and minimized the effect of storm towards further east of the Damodar Valley. Intense tropical hurricanes for the generation of storm generated bedforms, cannot be ruled out, which probably, in some cases, causes marine inundation/flooding deep into the landmass and also mass (?) uprooting of trees. 相似文献
953.
【目的】研究提高船舶主机燃料的综合利用率。【方法】结合MAN 6S50ME型船舶柴油机的余热能量特性和循环热力过程特点,分别建立基本循环、缸套水预热循环和回热循环等三种船舶余热利用有机朗肯循环系统模型,对三种余热利用系统的热力性能与经济性能进行计算和分析。【结果与结论】在三种循环系统中,缸套水预热循环的综合性能更具优势,在循环压力为2000 kPa时,系统的综合性能达到最优,循环净功为555.35 kW,热效率可达18.27%,循环发电净收益提高39.64%。研究结果可为船舶柴油机余热利用系统的设计和优化提供一定的理论指导。 相似文献
954.
风浪要素是海洋环境信息中影响舰船航行安全与人员作业的首要因素.基于GIS技术对海洋风浪信息服务系统进行了设计,实现了台风信息与海浪信息的可视化表达.该系统可为舰船航行中的海洋水文气象保障提供必要的辅助决策,也可为同类GIS系统的设计与开发提供一些参考. 相似文献
955.
Marine waters from seven sites around Hong Kong with varying levels of sewage pollution were analyzed for Hepatitis A virus (HAV) by PCR cloning and DNA sequencing of the highly variable VP1/2A junction of the HAV genome. Phylogenetic analysis of 10 PCR clones from each of the HAV-positive marine sites indicated that human HAV genotype IB is the most widely distributed type in Hong Kong waters. A sensitive and quantitative TaqMan-based PCR method targeting the 5′-noncoding region (5′-NCR) of HAV was used to quantify HAV particles in marine water samples along with the total Escherichiacoli counts being enumerated on TBX medium for comparison. Our results showed that no correlation of any significance between HAV and E. coli counts was observed which underscores the inadequacy in using E. coli as a sanitary standard to predict the levels of HAV in marine waters. 相似文献
956.
天津市建设项目"海上地震观测试验系统",是"十五"期间天津数字地震观测网络项目中的重点实验任务,该项目的建设将有效提高渤海海域地震监测能力,为天津经济社会发展建设、为滨海新区开发开放提供服务.通过建设海洋地震台,提高了天津市测震台网在渤海地区的监控能力,对于海啸预警能力也大有提高. 相似文献
957.
Progress in some areas of process‐based aeolian sediment transport research is hampered by limited opportunities for data comparison, synthesis, and integration. This is partially due to a lack of reliable comparison methods. Many comparison methods are forms of calibration that are either restrictive (e.g., time‐averages only) or non‐existent (e.g., for field‐based sediment transport thresholds or vertical mass flux profiles). It is believed that the adoption of standard methods for common measurements may improve inter‐study comparison, add value and longevity to data, and advance integrative modeling efforts. Examples of approaches in allied disciplines where standards are used routinely are reviewed and we discuss how the mutual benefits of standardized data could outweigh perceived disadvantages. Overall, the goal of this commentary is to encourage discussion, self‐assessment, and forethought with regard to measurement methods used in process‐based aeolian geomorphology. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
958.
959.
River mouths along the Israeli Mediterranean coast are characterized by a dynamic morphology as their channels migrate hundreds of meters along the coast. This study examines the dynamic morphology of seven such river mouths. It offers a conceptual model aimed at generalizing and describing their spatial and temporal morphological patterns, and the environmental factors influencing them. The study methodology comprised a detailed monitoring and mapping by GIS techniques, with quantitative data derived from historic aerial photographs, river discharge records, wave measurements, and a digital elevation model. These data were incorporated into a homogenous database and subsequently applied in the investigation of the morphological patterns of these mouths, and the analysis of their influencing factors. River mouths in this study occur in two distinctive topographic settings. In one setting (here termed barrier topography) the river mouth is deflected alongshore by a sandy barrier. In the second setting (termed funnel topography) the river mouth is confined to a funnel‐shaped topographic depression perpendicular to the coast. The behavior of river mouths in these two settings is quite distinctive. Barrier mouths usually migrate over larger distances, as they tend to deflect along a sand barrier and establish semi‐permanent channels along the dune toe. This enables the wide range migration of semi‐permanent channels over decades. Funnel topography mouths deflect over shorter distances and they rapidly migrate within the funnel boundaries. This study concludes that the topographic setting of the beach, a constant element in the temporal scale of this study, is the primary influencing factor on the morphology of the mouths studied. The influence of other factors on the morphology of these mouths differs in space and time and depends on the topographic settings. 相似文献
960.
ZHAO Wenjin WANG Nianzhong ZHU Min Ulrich MANN Ulrich HERTEN Andreas LüCKE 《《地质学报》英文版》2011,85(2):340-353
Carbon isotope (δ13Corg) analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as ?25.2‰ (Xishancun) and ?19.9‰ (Putonggou) in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti (only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna). These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary (SDB) at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point (GSSP) in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation (between sample QX-20 and sample QX-21) in the Xishancun Section and the lower part of the Xiaputonggou Formation (between sample ZP-09 and sample ZP-10) in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine deposits. 相似文献