EXPERIMENTS ON FLOW AROUND A CYLINDER IN A SCOURED CRANNEL BED     

I. ISTIARTO  W.H. GRAF Res. Asst.  Lab. de recherches hydrauliques  Ecole Polytechnique Federale  Lausanne  Switzerland. E-mail: adhy.kurniawan@epfl.ch or istiarto@tsipil.ugm.ac.id Prof  Lab. de recherches hydrauliques  Ecole Polytechnique Federal 《国际泥沙研究》2001,(4)

1 INTRODUCTION'LOcal scour around a pier is a result of the interatiOn amongst the pier, the aPproach flow and theerodible bed. The Presence of a pier results in a stagnation pressure build-up in front of the pier and athree-dimensional tUrbulent flow echaracterized by the downward flow ahead of the pier and the so-called horseshoe vortex along the base of the Pier forms itself The flow modifies the erothe bed inthe vicinity of the pier when local scour takes place (Graf and AJhnakar l…  相似文献   

LABORATORY PROFILE THE LABORATORY FOR ANALYTICAL CHEMISTRY,UNIVERSITY OF NIJMEGEN,NIJMEGEN,THE NETHERLANDS     

HEAD OF THE LABORATORY:GERRIT KATEMAN 《地理学报(英文版)》1993,(2)

The city of Nijmegen is situated in the East of the Netherlands,close to where the river Rhineenters the country from Germany.It was already known as a strategic point of interest duringthe days of the Roman Empire.Nijmegen has always belonged to the Dutch part of theNetherlands,meaning that it never was occupied by Spain (as the South was).The identity ofa strategically important,fortified and walled city has long dominated Nijmegen and thisreputation remained even up to the second world war.For about a century,Nijmegen has been  相似文献   

Structural pattern of eastern Himalayan syntaxis in Namjagbarwa and its formation process   总被引：20，自引：4，他引：16  

ZHANG Jinjiang  Jl Jianqing  ZHONG Dalai  DING Lin & HE Shundong. Department of Geology  Peking University  Beijing  China  . Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China Correspondence should be addressed to Zhang Jinjiang 《中国科学D辑(英文版)》2004,47(2):138-150

The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contrac-tional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62-60 Ma, -23 Ma and -13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma.  相似文献   

Typical basin-fill sequences and basin migration in Yanshan, North China ——Response to Mesozoic tectonic transition   总被引：6，自引：0，他引：6  

LI Zhong  LIU Shaofeng  ZHANG Jinfang & WANG Qingchen. Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China  . China University of Geosciences  Beijing  ChinaCorrespondence should be addressed to Li Zhong 《中国科学D辑(英文版)》2004,(2)

Basin-fill sequences of Mesozoic typical basins in the Yanshan area, North China may be divided into four phases, reflecting lithosphere tectonic evolution from flexure (T3), flexure with weak rifting (J1+2), tectonic transition (J3), and rifting (K). Except the first phase, the other three phases all start with lava and volcaniclastic rocks, and end with thick coarse clastic rocks and/or conglomerates, showing cyclic basin development rather than simple cyclic rift mechanism and disciplinary basin-stress change from extension to compression in each phase. Prototype basin analysis, based on basin-fill sequences, paleocurrent distribution and depositional systems, shows that single basin-strike and structural-line direction controlling basin development had evidently changed from east-west to northeast in Late Jurassic in the Yanshan area, although basin group still occurred in east-west zonal distribution. Till Early Cretaceous, main structural-line strike controlling basins just turned to northeast by  相似文献   

Detection of spheriodal free oscillation excited by Peru 8.2 M_s earthquake with five international superconducting gravimeter data     

LEI Xiang''''e  XU Houze & SUN Heping Key Laboratory of Dynamic Geodesy  Institute of Geodesy  Geophysics. Chinese Academy of Sciences  Wuhan  China Correspondence should be addressed to Lei Xiang''''e 《中国科学D辑(英文版)》2005,48(1)

In this paper, authors obtain the spectral peaks of the earth free oscillation and check all normal modes from 0S0 to 0S48 accurately, with the Fourier analysis and the maximum entropy spectrum method dealing jointly with six groups of the observational residual data from five international superconducting gravimeter stations. By comparing the observational results in this paper with three former groups of observations or models, authors notice an extra discrepancy between two observational 0S2 modes excited separately by Peru earthquake and Alaska earthquake, which probably mirrors the anisotropy of the Earth's inner core. The analysis on the splitting 1S2 mode shows that the asymmetric factor of rotationwise spectral splitting is possible to be different from that of anti-rotationwise spectral splitting.  相似文献   

LOCAL SCOUR ESTIMATION AT BRIDGE SITE: MODIFICATION AND APPLICATION OF LACEY FORMULA   总被引：1，自引：0，他引：1  

Md. Munsur RAHMAN  iwfm.buet.ac.bd  at present: Post Doctoral Research fellow  Ujigawa Open Laboratory  Disaster Prevention Research Institute  Kyoto University  Shimomisu  Yoko-Oji  Fushimi-Ku  Kyoto -  Japan  M. Anisul HAQUE 《国际泥沙研究》2003,18(4)

In the recent years, it has been established that b/h or h/b (b = length of the structure in the lateral direction and h = approach flow depth) is the dominant factor for the estimation of local scour depth around abutments and piers. One of the major limitations of the Lacey formula is that it predicts only one value of the scour depth for a specific river because of the absence of important parameters b and h. Therefore, its application is quite uncertain for variable b and h. Considering its limitations and experimental facts of flow concentration and shear stress amplification close to above structures, the original Lacey formula is modified introducing the parameters b and h. The applicability of the original as well as modified Lacey formula is tested to the data collected from major rivers in Bangladesh.  相似文献   

Kalligrammatid Lacewings from the Upper Jurassic Daohugou Formation in Inner Mongolia, China   总被引：3，自引：1，他引：3  

ZHANG JunfengNanjing Institute of Geology  Palaeontology  Chinese Academy of Sciences  Nanjing  Jiangsu  E-mail: jfzhang@nigpas.ac.cn 《《地质学报》英文版》2003,77(2):141-147

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.  相似文献   

Geochemistry of Mesoproterozoic Volcanic Rocks in the Western Kunlun Mountains: Evidence for Plate Tectonic Evolution   总被引：1，自引：0，他引：1  

ZHANG Chuanlin  DONG Yongguan  ZHAO Yu  WANG Aiguo  GUO Kunyi Guiyang Institute of Geochemistry  Chinese Academy of Sciences  Guiyang  Guizhou  E-mail: zchuanlin@sina.com Nanjing Institute of Geology  Mineral Resources  Nanjing  Jiangsu 《《地质学报》英文版》2003,77(2):237-245

Mesoproterozoic volcanic rocks occurring in the north of the western Kunlun Mountains can be divided into two groups. The first group (north belt) is an reversely-evolved bimodal series. Petrochemistry shows that the alkalinity of the rocks decreases from early to late: alkaline→calc-alkaline→tholeiite, and geochemistry proves that the volcanic rocks were formed in rifting tectonic systems. The sedimentary facies shows characteristics of back-arc basins. The second (south belt) group, which occurs to the south of Yutian-Minfeng-Cele, is composed of calc-alkaline island arc (basaltic) andesite and minor rhyolite. The space distribution, age and geochemistry of the two volcanite groups indicate that they were formed in a back-arc basin (the first group) and an island arc (the second group) respectively and indicate the plate evolution during the Mesoproterozoic. The orogeny took place at -1.05 Ga, which was coeval with the Grenville orogeny. This study has provided important geological data for explorin  相似文献   

Cenozoic Adakite-type Volcanic Rocks in Qiangtang, Tibet and Its Significance   总被引：6，自引：0，他引：6  

LIU Shen  HU Ruizhong  FENG Caixi  CHI Xiaoguo  LI Cai  YANG Rihong  WANG Tianwu  JIN WeiGuiyang Institute of Geochemistry  Chinese Academy of Sciences  Guiyang  Guizhou E-mail: lliushen@hotmail.comGraduate School of the Chinese Academy of Sciences  Beijing College of Earth Sciences  Jilin University  Changchun  Jilin Aero Geophysical & Remote Sensing Center  Beijing 《《地质学报》英文版》2003,77(2):187-193

Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau.  相似文献   

SIMULATION OF POLLUTANTS IN RIVER SYSTEMS USING FINITE DIFFERENCE METHOD     

ZAHEER Iqbal  CUI Guang Bai Ph D candidate  College of Water Resources  Environment  Hohai University  Nanjing  China E-mail: zaheeriqbal@hotmail.com Prof. College of Water Resources  Environment  Hohai University  Nanjing  China 《国际泥沙研究》2002,17(2)

1 INTRODUCTION Numerical computation provides an easily extended and user-friendly environment with computer aided programming for the simulation of pollutants in river systems. In the most of water quality assessment and monitoring problems during water pollution control and environmental impact assessment studies of river systems, mathematical modeling has been playing a key role for the last two decades. The majority of existing water quality models are the mechanistic and are based o…  相似文献