旋转流场中的格子波耳兹曼模型

在大尺度的旋转流场中,由于存在哥氏力,使流体的流动出现了一系列复杂的动力学现象.在原格子Boltzmann模型研究的基础上,引入了哥氏力效应,发展了一个旋转流场中的格子Boltzmann模型.从该模型出发可导出地球流体力学方程,用这一模型对理想边界条件下的北半球大气环流进行了数值计算.数值结果很好地再现了大尺度地转流的流动特征.从理论和数值实验上验证了该模型的适用性.     

Study on the feature selection and classifica－tion effect of precursory data of ground tilt

Ｓｔｕｄｙｏｎｔｈｅｆｅａｔｕｒｅｓｅｌｅｃｔｉｏｎａｎｄｃｌａｓｓｉｆｉｃａ┐ｔｉｏｎｅｆｅｃｔｏｆｐｒｅｃｕｒｓｏｒｙｄａｔａｏｆｇｒｏｕｎｄｔｉｌｔＺＨＥＮＧ－ＹＵＡＮＬＩ（李正媛），ＤＥ－ＦＵＣＨＥＮ（陈德福），ＹＩ－ＬＩＮＷＵ（吴奕麟）ａ...     

SEDIMENT TRANSPORT EXPERIMENTSIN UNSTEADY FLOWS

l INTRODUCTIONThe theories and formulas of sediment dynamics were established based on steady and uniform flows.These theories and formulas often fail to aPply in engineering projects because, in nthee, sediment istransported often by unsteady and non-uniform fiows (Wang et al., l997).TWo cases ofnon-stationarity can be distinguished f long-tertn and short-term (Plate, l994). Long-termnon-stationarity tfansport can be defined as a sediment process which can be treated by sequences ofstat…     

ELECTROMAGNETIC PROSPECTING FOR GROUNDWATER IN PRECAMBRIAN TERRAINS IN THE REPUBLIC OF UPPER VOLTA*

The “Autorité des amenegements des valées des Voltas (AVV)” is establishing new rural settlements in the Volta valleys. First, a survey of available water supplies is performed. Economic aquifers in Precambrian terrains are deep (15–50 m) and usually occur in fractured zones accompanying faults. Such zones can be identified on aerial photographs, but their precise location on the ground is virtually impossible by visual means. Because of the small size of the aquifers, a location error of 5 m can make the difference between a productive well and a dry hole. Traditionally, resistivity profiling has been used as the means of locating the fractured zones in the field. Our studies suggest that the task can be performed faster, cheaper and more accurately by VLF and EM methods. Because of the limited choice of transmitting stations reccivable in Upper Volta, the VLF method is not sufficiently sensitive to detect conductors with a strike between 45° and 105°. The results obtained with a multifrequency, horizontal-loop EM (HLEM) system were satisfactory in all investigated areas. During the 1980 field season, 35 target areas were surveyed. Of the 24 holes drilled so far, 23 are productive. The weathered layer is a source of distinctive HLEM anomalies, which are characteristic of the underlying rocks. Therefore, different interpretational procedures had to be developed for granitic and volcano-sedimentary areas. Despite the high background level of in-phase and quadrature components, which varied with thickness and conductivity of the weathered layer, aquifers could be detected at a depth greater than 30 m. Attempts were made to interpret the HLEM results quantitatively using two models: a three-layer medium and a valley discontinuity. The latter model is more realistic, but more scale modelling will have to be performed to permit development of viable interpretational procedures. Meanwhile, phasor diagrams based on drilling and resistivity sounding data can be used to estimate the aquifer depth.     

INFLUENCE OF VELOCITY ERRORS ON THE FOCUSING ASPECTS OF MIGRATION*

In migration procedures, the velocity profile of the subsurface is the most important input information. Since, in general, this information is only approximately known, errors in the migration output due to errors in the velocity input occur in all practical applications. In migration, velocity errors and depth errors can be interchanged. This interchange property is perfect in the paraxial approximation. From this result it follows that migration with incorrect velocities may still yield correctly migrated data if the imaging principle is modified. This attractive property can be used in the stripping version of migration (recursive migration).     

Characteristics of fault rocks and paleo-earthquake source along the Koktokay-Ertai fault zone,Xinjiang,China

ＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｆａｕｌｔｒｏｃｋｓａｎｄｐａｌｅｏｅａｒｔｈｑｕａｋｅｓｏｕｒｃｅａｌｏｎｇｔｈｅＫｏｋｔｏｋａｙＥｒｔａｉｆａｕｌｔｚｏｎｅ，Ｘｉｎｊｉａｎｇ，ＣｈｉｎａＬＡＮＢＩＮＳＨＩ１）（史兰斌）ＣＨＵＡＮＹＯＮ...     

TRACING FLOOD FLOWS USING SEDIMENTARY INDICATORS

LinTRODUCTIONANDAIMSTheaimsofthisStUdyaretointroducenewtechniquesforanalysingfloodflowsfromsedimentarrangementmsapproachincorporatestheeffectsofflotvonthedevelopmentofrouglmessontheriverbed,andnot,asismostlythecase,theeffectsofbedroughnessonflow.Differentacsofflows,includingthemaalmumfloodflowarereconsmictedfromfloworientahonsofparticlesoveranentiregravCIbar.DuetOtheddricultiesinvolvedinobtaininglargeparticlesamples,studiesonpAncleOrientationsintheliteratUrearerare.WhilstmoStanalyse…     

Etablissement de la relation hauteur-débit de l'Amazone à Óbidos: méthode de la dénivelée normale à “géométrie variable”

Résumé

Cet article décrit la façon dont ont été calculés les débits journaliers de l'Amazone à Óbidos. La relation hauteur-débit est univoque en basses et moyennes eaux. En période de hautes eaux la dispersion des jaugeages par rapport à la courbe de tarage univoque amène à corriger les débits en fonction des niveaux à Santarém puis à Parintins. La méthode de la “dénivelée normale” n'étant pas bien adaptée pour Óbidos: elle a été remplacée par une “dénivelée à géométrie variable” fonction de la hauteur d'eau à Óbidos. En utilisant seulement la station de Santarém, l'application de cette nouvelle méthode ramène la dispersion à 3.0% sur la totalité de la courbe de tarage.     

Estevâo Cabral's pioneering contribution to open channel hydrometry

Résumé

Le portugais Estevão Cabral (1734–1811) a construit, en 1786, un moulinet lui permettant de mesurer la vitesse de l'eau à différentes profondeurs et de calculer ainsi le débit des rivières. Cabrai a été le premier chercheur qui ait utilisé un moulinet pour mesurer la vitesse de l'eau au-dessous de la surface libre, les moulinets à roue à ailettes planes utilisés auparavant ne pouvant que mesurer la vitesse à la surface. Il a aussi été le premier chercheur à soutenir que la vitesse dans les écoulements a surface libre croît depuis la surface jusqu'à un maximum à partir duquel elle décroît vers le fond.     

A kind of informationon short-term and imminent earthquake precursors-research on atmospheric electric field anomalies before earthquakes

Ａｋｉｎｄｏｆｉｎｆｏｒｍａｔｉｏｎｏｎｓｈｏｒｔｔｅｒｍａｎｄｉｍｍｉｎｅｎｔｅａｒｔｈｑｕａｋｅｐｒｅｃｕｒｓｏｒｓ—ｒｅｓｅａｒｃｈｏｎａｔｍｏｓｐｈｅｒｉｃｅｌｅｃｔｒｉｃｆｉｅｌｄａｎｏｍａｌｉｅｓｂｅｆｏｒｅｅａｒｔｈｑｕａｋｅｓＪＩ...