Stochastic geometry in petroleum geology     

K. S. Deffeyes  B. D. Ripley  G. S. Watson 《Mathematical Geology》1982,14(5):419-432

Many aspects of the generation, migration, trapping, and discovery of petroleum, as well as its primary and enhanced recovery, depend upon geometry. The scale of the relevant geometric features varies all the way from that of continental margins and basins down to the pores and fissures in reservoir rocks. Because the spatial complexity is so great for each of these processes, it is reasonable to describe them statistically. The primary purpose of this paper is to survey possible ways in which statistical or stochastic geometry enters and might be used in petroleum geology and engineering. While it offers some new theory, this paper does not directly suggest any specific new methods for the estimation of hydrocarbon resources or reserves. This deficiency is mainly due to the current lack of relevant data. When data are available the point of view explained herein will be fruitful. The survey ties together many topics in a novel way.  相似文献   

Probabilistic seismic response and reliability assessment of isolated bridges     

GiuseppeCarloMarano 《地震工程与工程振动(英文版)》2005,4(1):95-106

Bridge seismic isolation strategy is based on the reduction of shear forces transmitted from the superstructure to the piers by two means: shifting natural period and earthquake input energy reduction by dissipation concentrated in protection devices. In this paper, a stochastic analysis of a simple isolated bridge model for different bridge and device parameters is conducted to assess the efficiency of this seismic protection strategy. To achieve this aim, a simple nonlinear softening constitutive law is adopted to model a wide range of isolation devices, characterized by only three essential mechanical parameters. As a consequence of the random nature of seismic motion, a probabilistic analysis is carried out and the time modulated Kanai-Tajimi stochastic process is adopted to represent the seismic action. The response covariance in the state space is obtained by solving the Lyapunov equation for a stochastic linearized system. After a sensitivity analysis, the failure probability referred to extreme displacement and the mean value of dissipated energy are assessed by using the introduced stochastic indices of seismic bridge protection efficiency. A parametric analysis for protective devices with different mechanical parameters is developed for a proper selection of parameters of isolation devices under different situations.  相似文献   

Detailed analysis for earthquake source spectrum represented by stochastic impulse train and its applications     

Hitoshi?MorikawaEmail author  Sumio?Sawada  Yusuke?Ono 《Journal of Seismology》2005,9(2):151-170

  相似文献   

Canonical Modelling of Relative Spacecraft Motion Via Epicyclic Orbital Elements     

N.?Jeremy?KasdinEmail author  Pini?Gurfil  Egemen?Kolemen 《Celestial Mechanics and Dynamical Astronomy》2005,92(4):337-370

This paper presents a Hamiltonian approach to modelling spacecraft motion relative to a circular reference orbit based on a derivation of canonical coordinates for the relative state-space dynamics. The Hamiltonian formulation facilitates the modelling of high-order terms and orbital perturbations within the context of the Clohessy–Wiltshire solution. First, the Hamiltonian is partitioned into a linear term and a high-order term. The Hamilton–Jacobi equations are solved for the linear part by separation, and new constants for the relative motions are obtained, called epicyclic elements. The influence of higher order terms and perturbations, such as Earth’s oblateness, are incorporated into the analysis by a variation of parameters procedure. As an example, closed-form solutions for J₂-invariant orbits are obtained.  相似文献   

Stochastic Hill's equations for the study of errant rocket burns in orbit     

Martin Ostoja-Starzewski  James M. Longuski 《Celestial Mechanics and Dynamical Astronomy》1992,54(4):295-303

The problem of errant rocket burns in low Earth orbit is of growing interest, especially in the area of safety analysis of nuclear powered spacecraft. The development of stochastic Hill's equations provides a rigorous mathematical tool for the study of such errant rocket maneuvers. These equations are analyzed within the context of a theory of linear dynamical systems driven by a random white noise. It is established that the trajectories of an errant rocket are realizations of a Gauss-Markov process, whose mean vector is given by the solution of a deterministic rocket problem. The time-dependent covariance matrix of the process is derived in an explicit form.  相似文献   

Improved relativistic transformations in GPS   总被引：1，自引：1，他引：0  

J.?KoubaEmail author 《GPS Solutions》2004,8(3):170-180

For GPS satellite clocks, a nominal (hardware) frequency offset and a conventional periodic relativistic correction derived as a dot product of the satellite position and velocity vectors, are used to compensate the relativistic effects. The conventional hardware clock rate offset of 38,575.008 ns/day corresponds to a nominal orbit semi-major axis of about 26,561,400 m. For some of the GPS satellites, the departures from the nominal semi-major axis can cause an apparent clock rate up to 10 ns/day. GPS orbit perturbations, together with the earth gravity field oblateness, which is largely responsible for the orbit perturbations, cause the standard GPS relativistic transformations to depart from the rigorous relativity transformation by up to 0.2 ns/day. In addition, the conventional periodic relativistic correction exhibits periodic errors with amplitudes of about 0.1 and 0.2 ns, with periods of about 6 h and 14 days, respectively. Using an analytical integration of the gravity oblateness term (J₂), a simple analytical approximation was derived for the apparent clock rate and the 6-h periodic errors of the standard GPS gravity correction. For daily linear representations of GPS satellite clocks, the improved relativistic formula was found to agree with the precise numerical integration of the GPS relativistic effects within about 0.015 ns. For most of the Block IIR satellites, the 6-h periodical errors of the GPS conventional relativistic correction are already detectable in the recent IGS final clock combinations.  相似文献   

A simplified method for simulation of strong ground motion using finite rupture model of the earthquake source     

A.?JoshiEmail author  S.?Midorikawa 《Journal of Seismology》2004,8(4):467-484

We present a simplified method to simulate strong ground motion for a realistic representation of a finite earthquake source burried in a layered earth. This method is based on the stochastic simulation method of Boore (Boore, D. M., 1983, Bull. Seism. Soc. Am. 73, 1865–1894) and the Empirical Greens Function (EFG) method of Irikura (Irikura, K., 1986, Proceedings of the 7th Japan Earthquake symposium, pp. 151–156). The rupture responsible for an earthquake is represented by several subfaults. The geometry of subfaults and their number is decided by the similarity relationships. For simulation of ground motion using the stochastic simulation technique we used the shapping window based on the kinetic source model of the rupture plane. The shaping window deepens on the geometry of the earthquake source and the propagation characteristics of the energy released by various subfaults. The division of large fault into small subfaults and the method for accounting their contribution at the surface is identical to the EGF. The shapping window has been modified to take into account the effect of the transmission of energy released form the finite fault at various boundaries of the layered earth model above the source. In the present method we have applied the correction factor to adjust slip time function of small and large earthquakes. The correction factor is used to simulate strong motion records having basic spectral shape of ² source model in broad frequency range. To test this method we have used the strong motion data of the Geiyo earthquake of 24th March 2001, Japan recorded by KiK network. The source of this earthquake is modelled by a simple rectangular rupture of size 24 × 15 km, burried at a depth of 31 km in a multilayered earth model. This rupture plane is divided into 16 rectangular subfaults of size 6.0 × 3.75 km each. Strong motion records at eight selected near-field stations were simulated and compared with the observed records in terms of the acceleration and velocity records and their response spectrum. The comparison confirms the suitability of proposed rupture model responsible for this earthquake and the efficacy of the approach in predicting the strong motion scenario of earthquakes in the subduction zone. Using the same rupture model of the Geiyo earthquake, we compared the simulated records from our and the EGF techniques at one near-field station. The comparison shows that this technique gives records which matches in a wide frequency range and that too from simple and easily accessible parameters of burried rupture.  相似文献   

Selection of environmental conditions for nearshore structure design     

DONGSheng GANBuhong HAOXiaoli 《中国海洋大学学报(英文版)》2004,3(1):111-114

1　Introduction　InChina ,coastalcitiesaremostlyregionaleconomicdevelopmentcenters.Becauseoftheirspecialgeogra phiclocations ,typhoonsandassociatedstormsurgescauseheavylossesoflivesandproperties.In 1 992 Qing daowasfloodedduetothecoincidenceoftheastrono m…  相似文献   

GPS／GLoNASS组合定位的抗差Helmert方差分量估计模型     

高晓  戴吾蛟 《全球定位系统》2012,37(6):17-20,25

GPS和GLONASS存在系统差异,组合定位时,采用Helmert方差分量估计可得到更加准确的结果。但GNSS观测值常受到衍射信号和多路径效应的影响,使观测值存有粗差,从而导致Helmert方差分量估计的失真。为此,将抗差Helmert方差分量估计应用于GPS／GLONASS组合单点定位,实验结果表明：抗差Helmert方差分量估计可以有效地抑制组合系统粗差观测值的影响。  相似文献   

辽宁沿海经济带工业环境效率分析   总被引：10，自引：3，他引：7  

佟连军  宋亚楠  韩瑞玲  李名升 《地理科学》2012,(3):294-300

环境效率是生态效率的重要组成部分。基于环境效率对于指导区域经济与环境协调发展的重要意义,以重工业基地辽宁沿海经济带为例作环境效率研究,应用数据包络分析(DEA)和随机前沿分析(SFA)测算辽宁沿海经济带2001~2009年工业环境效率和产出弹性。在此基础上利用Tobit模型构建多元线性回归,分析工业环境效率的关键影响因素。结果表明:2001~2009年辽宁沿海经济带工业环境效率有大幅提高,但与理想状况仍有一定差距。其中大连的工业经济增长主要依靠劳动力推动,对环境成本的依赖正在减小,丹东、营口和葫芦岛3市的工业增长需要牺牲更多的环境成本。重工业化、资本密集化和高新技术化不利于工业环境效率提高,经济发展水平的提高则极大地促进了工业环境效率的提高。所有制结构、生产规模、外商投资和环境管理力度等因素因其作用的两面性,对工业环境效率无有效影响。  相似文献