非稳态法计算油水相对渗透率的方法探讨

油水相对渗透率是评价油藏的一个重要指标,它在油藏工程计算中的应用十分广泛。通常油水相对渗透率可用稳态和非稳态两种方法求得。文中提出了几种非稳态法计算油水相对渗透率,既考虑了日常用恒速法,又提出了非恒速非恒压数学处理方法,非稳态法获取的数据较为可靠,但数学处理难度较大。笔者编制了相应的实用软件,其适用范围广,经多次应用实践,效果良好。

Design and optimization in multiphase homing trajectory of parafoil system

In order to realize safe and accurate homing of parafoil system,a multiphase homing trajectory planning scheme is proposed according to the maneuverability and basic flight characteristics of the vehicle.In this scenario,on the basis of geometric relationship of each phase trajectory,the problem of trajectory planning is transformed to parameter optimizing,and then auxiliary population-based quantum differential evolution algorithm(AP-QDEA)is applied as a tool to optimize the objective function,and the design parameters of the whole homing trajectory are obtained.The proposed AP-QDEA combines the strengths of differential evolution algorithm(DEA)and quantum evolution algorithm(QEA),and the notion of auxiliary population is introduced into the proposed algorithm to improve the searching precision and speed.The simulation results show that the proposed AP-QDEA is proven its superior in both effectiveness and efficiency by solving a set of benchmark problems,and the multiphase homing scheme can fulfill the requirement of fixed-points and upwind landing in the process of homing which is simple in control and facile in practice as well.

Some optimal dividend problems for a surplus process with interest

We derive some results on the dividend payments prior to ruin in the classical surplus process with interest.An integro-differential equation with a boundary conditions satisfied by the expected present value of dividend payments is derived and solved.Furthermore,we derive an integro-differential equation for the moment generating function,through which we analyze the higher moment of the present value of dividend payments.Finally,closed-form expressions for exponential claims are given.

Design and analysis of the reliability of on-board computer system based on Markov-model

An on-board computer system should have such advantages as light weight,small volume and low power to meet the demand of micro-satellites. This paper, based on specific characteristics of Stereo Mapping Micro-Satellite (SMMS), describes the on-board computer system with its advantage of having centralized and distributed control in the same system and analyzes its reliability based on a Markov model in order to provide a theoretical foundation for a reliable design. The on-board computer system has been put into use in principle prototype model of Stereo Mapping Micro-Satellite and has already been debugged. All indexes meet the requirements of the design.

Three Nonnegative Solutions of Three-Point Boundary Value Problem for Second-Order Impulsive Differential Equations

The paper studies the existence of three nonnegative solutions to a type of three- point boundary value problem for second-order impulsive differential equations,and obtains the sufficient conditions for existence of three nonnegative solutions by means of the Leggett- Williams's fixed point theorem.

Computational methods in super-resolution microscopy

The broad applicability of super-resolution microscopy has been widely demonstrated in various areas and disciplines. The optimization and improvement of algorithms used in super-resolution microscopy are of great importance for achieving optimal quality of super-resolution imaging. In this review, we comprehensively discuss the computational methods in different types of super-resolution microscopy, including deconvolution microscopy, polarization-based super-resolution microscopy, structured illumination microscopy, image scanning microscopy, super-resolution optical fluctuation imaging microscopy, single-molecule localization microscopy, Bayesian super-resolution microscopy, stimulated emission depletion microscopy, and translation microscopy. The development of novel computational methods would greatly benefit super-resolution microscopy and lead to better resolution, improved accuracy, and faster image processing.

Singular Nonlinear Boundary Value Problems Arising in the Boundary Layer Behind Expansion Wave

A class of singular nonlinear boundary value problems arising in the boundary layer behind expansion wave are studied.Sufficient conditions for the existence and uniqueness of positive solutions to the problems are established by utilizing the monotonic approaching tech- nique.And a theoretical estimate formula for skin friction coefficient is presented.The numerical solution is presented by using the shoot method.The reliability and efficiency of the theoretical prediction are verified by numerical results.

The New Criteria Robust Stability of Uncertain Neutral Systems with Discrete and Distributed Delays

The robust stability of uncertain linear neutral systems with discrete and distributed delays is investigated. The uncertainties under consideration are norm bounded, and possibly time varying. By means of the equivalent equation of zero in the derivative of the Lyapunov-Krasovskli function, the proposed stability criteria are formulated in the form of a linear matrix inequality and it is easy to check the robust stability of the considered systems. Numerical examples demonstrate that the proposed criteria are effective.

Stability of Stochastic Differential Delay Equations with Markovian Switching

The main aim of this paper is to investigate the pth moment exponential stability of stochastic differential delay equations with Markovian switching.A specific Lyapunov function is introduced to obtain the required stability,and the almost sure exponential stability for the delay equations is discussed subsequently.

A survey on artificial boundary method Dedicated to Professor Shi Zhong-Ci on the Occasion of his 80th Birthday

The artificial boundary method is one of the most popular and effective numerical methods tor solving partial differential equations on unbounded domains, with more than thirty years development. The artificiM boundary method has reached maturity in recent years. It has been applied to various problems in scientific and engineering computations, and the theoretical issues such as the convergence and error estimates of the artificial boundary method have been solved gradually. This paper reviews the development and discusses different forms of the artificial boundary method.

A convolution algorithm to calculate differential cross sections of the Ring effect in the Earth's atmosphere based on rotational Raman scattering

The Ring effect refers to the filling in of Fraunhofer lines, which is mainly attributed to the rotational Raman scattering of solar spectra by N2 and O2 molecules in the atmosphere. The Ring effect is one of the most significant factors affecting the accuracy of retrieving concentrations of atmospheric trace gases, such as NO2 and SO2, from satellite observations through differential optical absorption spectroscopy. First in this study, the solar spectrum measured by the Ozone Monitoring Instrument onboard NASA Aura is convolved with the rotational Raman cross section of the atmosphere, which is calculated from the rotational Raman cross sections of N2 and O2 molecules, and divided by the original solar spectrum. The slowly varying term is removed by fitting it with a cubic polynomial to obtain the differential Ring spectrum. The results agree well with the calculations using a radiative transfer model (R2=0.9663). Second, the differential Ring spectrum is computed using two fixed wavelengths of 410 nm and 488 nm, and the resulting differential Ring spectra are similar to that calculated with varying wavelengths and agree well with the calculation using the radiative transfer model (R2=0.9624 and 0.9639 respectively). The computation time using the fixed wavelength is about 0.128% of that using a varying wavelength. Finally, we found that the frequency spectrum of the Raman cross sections for the atmosphere, N2 molecules and O2 molecules are similar; thus, the Raman cross section of N2 or O2 molecules can be used to compute the approximate Ring effect for simplicity.

A Pinching Theorem for Riemannian Foliations with Parallel Mean Curvature in a Local-Symmetric Riemannian Manifold

We discuss the Riemannian foliations with parallel mean curvature in a local- symmetric Riemannian manifold,and obtain a pinching theorem about it.

The Hyperbolic Darboux Image and Rectifying Gaussian Surface of Nonlightlike Curve in Minkowski 3-Space

In this paper,we give the classification of the singularities of hyperbolic Darboux image and rectifying Gaussian surface of nonlightlike curve in Minkowski 3-space.We establish the relationship between the singularities and the geometric invariants of curves which are deeply related to its order of contact with helices.