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81.
本文导出了电阻率-孔隙度、电阻率-含油(气)饱和度关系的一般形式--两个对称的表达式,并给予了实验证明。同时,本文指出,Archie公式、Winsauer公式和双水公式都是一般形式在一定条件下的特例。在一般情况下,本文给出了14个能够逼近这两个表达式的函数类型,通过岩芯数据进行选优,可以得到适合不同地区或地层的最优方程。根据本文理论建立的解释方法和研制的软件已经在油田生产中推广应用并取得了良好效果。 由于涉及内容较多,全文分两部分撰写。以下是本文的第(Ⅰ)部分,即一般形式的导出及实验验证;而最佳函数类型的确定及其在生产中的应用将作为本文的第(Ⅱ)部分发表。 相似文献
82.
矿床中存在着岩浆离熔成因的磁黄铁矿-镍黄铁矿矿石和热液改造成因的黄铁矿-针镍矿-辉镍矿矿石。研究证明现在矿石中存在的硫化物均为较低温度条件下的变质产物,并且矿物组合的更替不仅同温度变化有关,同时还受体系中氧逸度和硫离子活度的控制。矿物组合的地球化学分析表明,现有Fe-Ni-S体系低温(<300℃)相平衡图解之间存在着矛盾的原因可能是忽略了氧化-还原条件的影响。 相似文献
83.
肖天贵 《南京气象学院学报》1995,18(3):444-449
时间标度计算表明,西北太平洋热带气旋路径是一个无标度性的系统,其关联方差谱遵从频率的-2 ̄-3次方幂律,不同背景下的路径系统均如此。由此得到的不同季节、不同地域的热带气旋路径可预报时间尺度基本上为3 ̄4d,但异常热带气旋路径的可预报时间尺度则为1 ̄2d。 相似文献
84.
Further Studies Of Atmospheric Turbulence In Layers Near The Surface: Scaling The Tke Budget Above The Roughness Sublayer 总被引:2,自引:0,他引:2
The second of two experimental studies of the TKE budget conducted on sites of different roughness is described, and results are compared. The first took place within a shallow layer above a small field of mostly bare, cultivated soil; the second was carried out above a roughness sublayer of significant depth on an extensive plain of tall dry grass. Budget terms observed in the second study were scaled with a modified u which compensated for effects of an unusually large stress gradient and ensured that the m functions would be collinear. By showing that the modification becomes negligible in smaller gradients, it is demonstrated that in normal conditions, budgets observed above significant roughness sublayers should be normalized by scaling in terms of the unreduced Reynolds stress at the sublayer's upper surface. This procedure is shown to be consistent with the expectation that TKE budgets in layers near the surface all scale in fundamentally the same way.Other findings include: (1) the fact that most m functions previously reported are not quite collinear is attributed to a type of overspeeding known to affect three-cup anemometers; (2) revised m functions, collinear and largely free of the effects of overspeeding, are determined from a well-established characteristic of the linear m relation for the stable case; (3) data that define collinear m functions can also be represented with single hyperbolic curves; (4) dissipation is found to be 10 to 15% too small to balance total TKE production in unstable and neutral conditions and to decrease with increasing z/L in thestable regime; and (5) new relations for based on the observed behaviour of the dissipation deficit provide an improved closure for the set of equations that express the budget terms as functions of m and z/L. 相似文献
85.
基于Voronoi图的空间方向关系形式化描述研究(一) 总被引:5,自引:0,他引:5
空间方向关系形式化描述模型是空间方向关系研究的难点和重点,目前尚无完善的模型出现。首先提出了影响空间方向关系的两个因素目标:一是两目标群凸壳的直径;二是目标的可视性。论述了运用平面目标Voronoi科作为两目标指向线的“替身”来描述方向关系在理论上的可行性。本文的结论是:Voronoi图是描述空间方向关系的良好工具。 相似文献
86.
This paper presents an overview and synthesis of an extensive research effort to characterize and quantify scale invariances in the morphology and evolution of braided rivers. Braided rivers were shown to exhibit anisotropic spatial scaling (self-affinity) in their morphology, implying a statistical scale invariance under appropriate rescaling of the axes along and perpendicular to the main direction of flow. The scaling exponents were found similar in rivers of diverse flow regimes, slopes, types of bed material and braid plain widths, indicating the presence of universal features in the underlying mechanisms responsible for the formation of their spatial structure. In regions where predominant geologic controls or predominant flow paths were present, no spatial scaling was found. Regarding their spatiotemporal evolution, braided rivers were found to exhibit dynamic scaling, implying that a smaller part of a braided river evolves identically to a larger one provided that space and time are appropriately normalized. Based on these findings, and some additional analysis of experimental rivers as they approach equilibrium, it was concluded that the mechanism bringing braided rivers to a state where they show spatial and temporal scaling is self-organized criticality and inferences about the physical mechanisms of self-organization were suggested. 相似文献
87.
Agricultural practices, hydrology, and water quality of the 267-km2 Big Spring groundwater drainage basin in Clayton County, Iowa, have been monitored since 1981. Land use is agricultural; nitrate-nitrogen
(-N) and herbicides are the resulting contaminants in groundwater and surface water. Ordovician Galena Group carbonate rocks
comprise the main aquifer in the basin. Recharge to this karstic aquifer is by infiltration, augmented by sinkhole-captured
runoff. Groundwater is discharged at Big Spring, where quantity and quality of the discharge are monitored.
Monitoring has shown a threefold increase in groundwater nitrate-N concentrations from the 1960s to the early 1980s. The nitrate-N
discharged from the basin typically is equivalent to over one-third of the nitrogen fertilizer applied, with larger losses
during wetter years. Atrazine is present in groundwater all year; however, contaminant concentrations in the groundwater respond
directly to recharge events, and unique chemical signatures of infiltration versus runoff recharge are detectable in the discharge
from Big Spring.
Education and demonstration efforts have reduced nitrogen fertilizer application rates by one-third since 1981. Relating declines
in nitrate and pesticide concentrations to inputs of nitrogen fertilizer and pesticides at Big Spring is problematic. Annual
recharge has varied five-fold during monitoring, overshadowing any water-quality improvements resulting from incrementally
decreased inputs.
Electronic Publication 相似文献
88.
Fractures: Finite-size scaling and multifractals 总被引:1,自引:0,他引:1
The distributions of contact area and void space in single fractures in granite rock have been determined experimentally by making metal casts of the void spaces between the fracture surfaces under normal loads. The resulting metal casts on 52 cm diameter core samples show a complex geometry for the flow paths through the fracture. This geometry is analyzed using finite-size scaling. The spanning probabilities and percolation probabilities of the metal casts are calculted as functions of observation scale. Under the highest stresses of 33 MPa and 85 MPa there is a significant size-dependence of the geometric flow properties for observation scales smaller than 2 mm. Based on this data, the macroscopic percolation properties of the extended fracture can be well represented by relatively small core samples, even under normal stresses larger than 33 MPa. The metal casts also have rich multifractal structure that changes with changing stress. 相似文献
89.
Excavation induced seismic events with moment magnitudesM<0 are examined in an attempt to determine the role geology, excavation geometry, and stress have on scaling relations. Correlations are established based on accurate measurements of excavation geometry and methodology, stress regime, rock mass structure, local tectonics, and seismic locations. Scaling relations incorporated seismic moments and source radii obtained by spectral analysis, accounting for source, propagation, and site effects, and using Madariaga's dynamic circular fault model. Observations suggest that the interaction of stresses with pre-existing fractures, fracture complexity and depth of events are the main factors influencing source characteristics and scaling behaviour. Self-similar relationships were found for events at similar depths or for weakly structured rock masses with reduced clamping stresses, whereas a non-similar behaviour was found for events with increasing depth or for heavily fractured zones under stress confinement. Additionally, the scaling behaviour for combined data sets tended to mask the non-similar trends. Overall, depth and fracture complexity, initially thought as second order effects, appear to significantly influence source characteristics of seismic events withM<0 and consequently favour a non-similar earthquake generation process. 相似文献
90.
Is the ocean floor a fractal? 总被引:1,自引:0,他引:1
The topographic structure of the ocean bottom is investigated at different scales of resolution to answer the question: Can the seafloor be described as a fractal process? Methods from geostatistics, the theory of regionalized variables, are used to analyze the spatial structure of the ocean floor at different scales of resolution. The key to the analysis is the variogram criterion: Self-similarity of a stochastic process implies self-similarity of its variogram. The criterion is derived and proved here: it also is valid for special cases of self-affinity (in a sense adequate for topography). It has been proposed that seafloor topography can be simulated as a fractal (an object of Hausdorff dimension strictly larger than its topological dimension), having scaling properties (self-similarity or self-affinity). The objective of this study is to compare the implications of these concepts with observations of the seafloor. The analyses are based on SEABEAM bathymetric data from the East Pacific Rise at 13°N/104°W and at 9°N/104°W and use tracks that run both across the ridge crest and along the ridge flank. In the geostatistical evaluation, the data are considered as a stochastic process. The spatial continuity of this process is described by variograms that are calculated for different scales and directions. Applications of the variogram criterion to scale-dependent variogram models yields the following results: Although the seafloor may be a fractal in the sense of the definition involving the Hausdorff dimension, it is not self-similar, nor self-affine (in the given sense). Mathematical models of scale-dependent spatial structures are presented, and their relationship to geologic processes such as ridge evolution, crust formation, and sedimentation is discussed. 相似文献