大巴山地区铂矿地质特征及成因初探   总被引：6，自引：1，他引：5  

唐将  邓富银 《矿产与地质》2000,14(2):86-90

大巴山铂矿产于秦岭地槽与扬子准地台的接合部位——城巴深断裂两侧的断块或岩体蚀变破碎带中 ,含矿层为上震旦统至下寒武统黑色岩系 ,含矿围岩具黄铁矿化、硅化、碳化现象。成矿物质来源、矿源初始富集与聚积成矿均与城巴深断裂的多期活动及早期火山喷发、多期岩浆侵入关系密切  相似文献   

Large Eddy Simulation of Open Ocean Deep Convection with Application to the Deep Water Formation in the East Sea (Japan Sea)     

Y. Noh  C. J. Jang  J-.W. Kim 《Journal of Oceanography》1999,55(2):347-367

Various important features could be found on the open ocean deep convection and the subsequent deep water formation from large eddy simulation (LES), and the results were applied to the East Sea (Japan Sea). It was found that under a strong cold wind outburst with the heat flux of 1000 Wm⁻² for 5 days generates a deep convection which can penetrate to the depth 1500 m, but under the continuous cooling with the heat flux of 250 Wm⁻² the growth of a mixed layer is suppressed at 700 m. The effects of the spatial and temporal variations of the surface forcing were investigated with regard to the penetrative depth of convection, the generation of baroclinic eddies, the volume of the water mass formation, and the intensity of the rim current. The deep water formations in the intermediate and deep layer of the East Sea were explained in terms of the simulation results, and the intensity of the consequent circulation and the volume of water mass formation were compared with the observation data. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Photometric Survey of Galactic Open Clusters     

M.G. Lee  H.B. Ann  M.Y. Chun  S. L. Kim  Y. B. Jeon  B. G. Park  I. S. Yuk  H.Sung 《天文研究与技术》1999,(Z1)

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Gradual downslope change in high-resolution acoustic characters and geometry of large-scale submarine debris lobes in Ulleung Basin, East Sea (Sea of Japan), Korea   总被引：1，自引：1，他引：0  

S. H. Lee  S. K. Chough  G. G. Back  Y. B. Kim  B. S. Sung 《Geo-Marine Letters》1999,19(4):254-261

A detailed analysis of high-resolution seismic data (Chirp, 2–7 kHz) in the Ulleung Basin reveals spatial variation in echo characteristics and geometry of large-scale debris lobes. In the proximal part, the debris lobes are dominated by hummocky surface echoes and gradually transitional downslope to seafloor-tangent hyperbolic and smooth prolonged bottom echoes, reflecting progressive decrease in size, spacing, and relief of surface forms. The strongly convex-upward upper surface with steep blunt margins in the proximal part is gradually transitional downslope to slightly convex- upward or nearly flat form with less blunt margins. The gradual downslope decrease in both scale and spacing of surface forms and convexity of upper surface within each debris lobe is suggestive of progressive dilution in flow concentration within a debris flow, probably due to mixing of ambient water and removal of suspended sediment by deposition during downslope movement. Received: 3 February 1999 / Revision received: 27 April 1999  相似文献   

Influence of frequency‐dependent soil–structure interaction on the fragility of R/C bridges          下载免费PDF全文

Nikolaos Lesgidis  Anastasios Sextos  Oh‐Sung Kwon 《地震工程与结构动力学》2017,46(1):139-158

Bridge performance under earthquake loading can be significantly influenced by the interaction between the structure and the supporting soil. Even though the frequency dependence of the interaction mentioned in this study has long been documented, the simplifying assumption that the dynamic stiffness is dominated by the mean or predominant excitation frequency is still commonly made, primarily as a result of the associated numerical difficulties when the analysis has to be performed in the time domain. This study makes use of the advanced lumped parameter models recently developed 1 in order to quantify the impact of the assumption on the predicted fragility of bridges mentioned in this study. This is achieved by comparing the predicted vulnerability for the case of a reference, well studied, actual bridge using both conventional, frequency‐independent, Kelvin–Voigt models and the aforementioned lumped parameter formulation. Analysis results demonstrate that the more refined consideration of frequency dependence of soil–structure interaction at the piers and the abutments of a bridge not only leads to different probabilities of failure for given intensity measures but also leads to different hierarchy and distribution of damage within the structure for the same set of earthquake ground motions even if the overall probability of exceeding a given damage state is the same. The paper concludes with the comparative assessment of the effect for different soil conditions, foundation configurations, and ground motion characteristics mentioned in this study along with the relevant analysis and design recommendations. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Development of benthic macroinvertebrates sediment index(BSI) for bioassessment of freshwater sediment     

Pil Jae Kim  Jong Hyeon Lee  In Ae Huh  DongSoo Kong 《国际泥沙研究》2019,34(4):368-378

Sediment quality has been evaluated in a variety of ways since the early 1990s in studies from Europe. In South Korea, most studies have used an indicator value for benthic macroinvertebrates based on water quality, not sediment quality. To date, few studies have examined the biological integrity of benthic macroinvertebrate communities in South Korea. In the current study, the tolerance valency and value in samples and the indicator weight values were measured for 43 benthic macroinvertebrate taxa from 73 sampling units in South Korea from 2014 to 2016. Total organic carbon, the amount of heavy metals, and total ammonia nitrogen were analyzed. The average grade for each pollutant was used as the sediment quality index. A benthic macroinvertebrates sediment index was developed for bioassessment of freshwater sediment. The benthic macroinvertebrates sediment index, which is based on the relative frequency of occurrence of macroinvertebrates, was highly correlated with pollution levels in the sediment. This index can be used in the field to assess the contamination of freshwater sediment. As the sample size was small in the current study and there were taxonomic limitations of Chironomidae larvae, further research is needed to improve the reliability of the benthic macroinvertebrates sediment index.  相似文献   

A simple model to predict the effect of volume fraction,diameter, and length of fibres on strength of fibre reinforced brittle matrix composites     

T. Kundu  H.S. Jang  Y. H. Cha  C. S. Desai 《国际地质力学数值与分析法杂志》2000,24(7):655-673

A simplified model is presented to predict the strength variations of brittle matrix composites, reinforced by steel fibres, with the variations of fibre parameters—length, diameter and volume fraction. This model predicts that its tensile and flexural strength increase non‐linearly with the fibre volume fraction. It also predicts that similar non‐linear behaviour should be observed with the reduction of the fibre diameter when other parameters are kept constant. The experimental results support both these theoretical predictions. It is also explained why an increase in the fibre length does not always significantly increase the fracture toughness. The objective of this paper is not to explain and understand in great detail the science of all phenomena responsible for the strength increase of fibre reinforced brittle matrix composites, but to provide a simple engineering explanation as to why its strength increases with the fibre addition, and how this increase can be quantitatively related to the variations in fibre parameters—fibre volume fraction, fibre length and diameter. These simplifying steps are needed to provide a tool that the practicing engineers can use to predict the brittle matrix strength variation with the fibre parameters. In the area of geomechanics, the results presented here can be used to assess and predict the behaviour of fibre‐reinforced earth. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Creating Spatial Information Infrastructures: Towards the Spatial Semantic Web – Edited by Peter van Oosterom and Sisi Zlatanova     

Zorica Nedovi&#;-Budi&#;  Sung-Gheel Jang 《Transactions in GIS》2010,14(1):89-91

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A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)     

Sangheon Yi  Chang-Gyun Han  Keun-Chang Oh  In Sun Seo  Dongwook Kim  Jaeyoung Lee  Min Han  Hanwoo Choi  Jaesoo Lim  Sujeong Park  Chang-Pyo Jun  Taesop Cho 《第四纪科学杂志》2022,37(1):100-113

We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ¹⁸O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.  相似文献