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91.
本文在综述了目前稳定流涌水量经验方程建立方法的基础上,根据最小二乘法原理,提出了一种新的方法—最小残差法,并给出了计算实例。计算表明,最小残差法是建立稳定法涌水量经验方程的一种较好方法,计算过程在微机上易于实现。 相似文献
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A remote sensing model for monitoring soil evaporation based on differential thermal inertia and its validation 总被引:2,自引:0,他引:2
To develop geosciences quantification and multi-dimensional researches will be an inevitable trend in the 21st century. The interaction between the land surface and the atmosphere not only serves as an important component in geosciences quantification, bu… 相似文献
95.
Giovanni?BesioEmail author Paolo?Blondeaux Maurifio?Brocchini Giovanna?Vittori 《Ocean Dynamics》2003,53(3):232-238
A simple mathematical model is described, which reproduces the major features of sand waves' appearance and growth and in particular predicts their migration speed. The model is based on the linear stability analysis of the flat configuration of the sea bottom subject to tidal currents.
Attention is focused on the prediction of the complex growth rate that bottom perturbations undergo because of both oscillatory fluid motions and residual currents. While the real part r of controls the amplification or decay of the amplitude of the bedforms, the imaginary part i is related to their migration speed.
Previous works on the migration of the sand waves (Németh etal. 2002) consider a forcing tide made up by the M2 constituent (oscillatory period equal to 12 h) plus the residual current Z0 and predict always a downcurrent migration of the bedforms. However, field cases exist of upcurrent-migrating sand waves (downcurrent/upcurrent-migrating sand waves mean bedforms moving in the direction of the steady residual tidal current or in the opposite direction, respectively).
The inclusion of a tide constituent characterized by a period of 6 h (M4) is the main novelty of the present work, which allows for the prediction of the migration of sand waves against the residual current Z0. Indeed, the M4 tide constituent, as does also the residual current Z0, breaks the symmetry of the problem forced only by the M2 tide constituent, and induces sand-wave migration.
The model proposed by Besio etal. (2003a) forms the basis for the present analysis. Previous works on the subject (Gerkema 2000; Hulscher 1996a,b; Komarova and Hulscher 2000) are thus improved by using a new solution procedure (Besio etal. 2003a) which allows for a more accurate evaluation of the growth rate for arbitrary values of the parameter r, which is the ratio between the horizontal tidal excursion and the perturbation wavelength.
Responsible Editor: Jens Kappenberg 相似文献
96.
The Central Andean gravity high (CAGH) is a positive anomaly in isostatic residual gravity with its center located at the western flank of the Central Andes at about 24°S. The gravity was analyzed by various methods to draw quantitative conclusions about the sources of this anomaly and their process of formation. Methods include the analysis of the gravity gradients, power spectrum, wavelength filters, and Euler deconvolution.Numerical investigations of gravity field in the area of the CAGH indicate the presence of a dense body of nearly 400 km length and about 100–140 km width, that masses lie at varying depths between 10 and 38 km. A correlation between the location of the residual anomalies and the topographic lows in the area between the Salars de Atacama and Pipanaco is observed, which indicates the strong influence of the anomalous-causing rocks of the CAGH within the formation process of the Andean orogen. An influence of these causing bodies of rock on the trend of Holocene volcanic arc is likely. Genesis of the anomalous dense formations of rock could be traced back to Ordovician–Silurian time when a pre-Andean subduction zone is postulated in the region of northern Chile with its corresponding volcanic arc in the region of the CAGH.
Zusammenfassung
El campo de gravedad alto de los Andes Centrales (CAGH) consiste en una pronunciada anomalía positiva de la gravedad isostática, cuyo centro se encuentra en el borde oeste de los Andes Centrales a los 24°S. En este estudio se analizó el campo de gravedad mediante distintos métodos, de manera de poder establecer conclusiones cuantitativas sobre el causante de esta anomalía y el proceso de formación de este causante.La investigación numérica de las anomalías gravimétricas del CAGH indica la presencia de un cuerpo de alta densidad con aproximadamente 400 km de largo y 100–140 km de ancho, que se encuentra a profundidades variables entre 10 y 38 km. Se observa una correlación entre la posición de la anomalía residual y los bajos topográficos en los areas de Salares de Atacama, Arizaro, Antofalla y Pipanaco, la cual indica una fuerte influencia de rocas productoras de la anomalía en el CAGH, dentro del proceso de formación del orógeno andino. Es probable que estos cuerpos de rocas causantes de la anomalía tengan incluso influencia en el alineamiento del arco volcánico holocénico. La generación de cuerpos de rocas con una densidad anómala puede remontarse al Ordovícico–Silúrico, tiempo para el que postula una subducción pre-Andina en la región del norte de Chile y que corresponde con el arco volcánico en la región del CAGH. 相似文献97.
It has been shown in the past that the interval-NMO velocity and the non-ellipticity parameter largely control the P-wave reflection time moveout of VTI media. To invert for these two parameters, one needs either reasonably large offsets, or some structure in the subsurface in combination with relatively mild lateral velocity variation.This paper deals with a simulation of an inversion approach, building on the assumption that accurately measured V
NMO, as defined by small offset asymptotics for a particular reflector, were available. Instead of such measurements we take synthetically computed data. First, an isotropic model is constructed which explains these V
NMO. Subsequently, residual moveout in common image gathers is modelled by ray tracing (replacing real data), along with its sensitivity for changes in the interval-NMO velocity and the non-ellipticity parameter under the constraint that V
NMO is preserved. This enables iterative updating of the non-ellipticity parameter and the interval-NMO velocity in a layer that can be laterally inhomogeneous.This approach is successfully applied for a mildly dipping reflector at the bottom of a layer with laterally varying medium parameters. With the exact V
NMO assumed to be given, lateral inhomogeneity and anisotropy can be distinguished for such a situation. However, for another example with a homogeneous VTI layer overlying a curved reflector with dip up to 30°, there appears to be an ambiguity which can be understood by theoretical analysis. Consistently with existing theory using the NMO-ellipse, the presented approach is successfully applied to the latter example if V
NMO in the strike direction is combined with residual moveout in dip direction. 相似文献
98.
汕头市花岗岩残积土的工程特性及路堑边坡稳定分析 总被引:1,自引:0,他引:1
花岗岩残积土在汕头市分布广泛,具有不均匀性及各向异性、扰动性、软化特性和崩解性。在天然状态下它们具有较低的压缩性、较高的承载力和较大的抗剪强度,但遇水后力学性质显著降低。花岗岩残积土的扰动性通常导致室内试验指标失真,使压缩模量低于变形模量,因此,花岗岩残积土的变形模量和地基承载力应通过原位测试(主要是标准贯入试验)来确定,并为此建立了本区花岗岩残积土地基容许承载力与标准贯入击数的对应关系。同时对汕头市花岗岩残积土路堑边坡失稳的原因进行分析并提出切实可行的防护办法。 相似文献
99.
研究胀缩土的成因,为地表建筑物防灾减灾,有一定的现实意义。根据胀缩土的工程地质特征,平面和垂向分布规律,右江高阶地胀缩土为冲洪积成因。 相似文献
100.
中国地震速报台网走时残差分析与走时修正 总被引:4,自引:0,他引:4
使用了30个速报台站的观测数据,计算了100多个中国境内外的地震事件初至波走时残差。在此基础上分析各台所记录的所有地震事件的残差随方位角和震中距的分布,及产生这些残差的地球深部非流体静力平衡状态和地球表面构造等方面的原因,并给出了不同区域地震走时的平均校正值,从而提高了地震定位精度。 相似文献