等距抽样总体指标估计值的优良判定

等距抽样是实践中常用的一种抽样方法，它是事先将全区及总体各单位按某一标志排列，然后依固定顺序和间隔来抽选调查单位，以样本来推断总体．在实践中常用“随机确定起点，对称等距抽样”、“半距起点，顺序等距抽样”的方法．近几年，学术界对样本指标的推断研究的较多，但对这一抽样方法总体指标的估计却很少问究，致使实践中的估计方法较单一，抽样效果难以提高。本文想就标志等距抽样总体指标值的估计进行分析．为实际中的抽样技术提供理论上的数学依据。     

分组数据的Bayes分析—Gibbs抽样方法

分组数据是可靠性试验中常见的一类不完全数据，由于似然函数比较复杂使Bayes分析很困难。本文利用Gibbs抽样方法，对分组数据的Bayes分析就容易实现，在寿命分布是威布尔分布情形，本文还给出了Gibbs抽样和Metropolis算法杂合的抽样方法，最后还讨论了Gibbs抽样方法的一些特点，并通过一些模拟结果对现有的几种处理分组数据的方法进行了比较。     

为PPS抽样而进行双重抽样的方法

本文把双重抽样技术用于ＰＰＳ抽样，给出了该方法下总体总值的无偏估计量，估计量的方差及方差的无偏估计公式。     

基于二相抽样的PPS二阶抽样

研究初级单元大小未知时基于二相抽样的PPS二阶抽样，给出总体总值的估计量，估计量的方差及方差的估计量。     

变异系数的抽样分布

本文在抽样分布定理的基础上，推导了变异系数的抽样分布     

Stein两阶段抽样问题中第一阶段最优抽样量研究

当精度和可靠度给定时，Stein（1945）提出了两阶段抽样方法，构造了同时满足一定可靠度与精度的区间估计．本文则利用数值计算方法，进一步给出了此两阶段抽样中最优的第一阶段抽样量．     

PPS抽样回归估计量及其在两相抽样中的应用

本文针对交通运输量抽样调查中存在的波动系数问题，讨论在ＰＰＳ的抽样条件下，回归估计量的构造及其在两相抽样中的应用     

谈不放回抽样与放回抽样的区别

高中数学新教材中增加了概率论的内容 ,在有关的课外资料中经常出现 (或隐含 )“不放回”与“放回”这类问题 ,本文就此谈一下它们的区别 .不放回抽样与放回抽样的区别主要体现在以下四个方面 :(1)不放回抽样是指每次抽出样品不放回 ,下次再抽样时 ,样品结构发生变化 ,总数比前次少一 ;而放回抽样是指每次抽出的样品放回 ,下次再抽样时 ,样品结构和总数保持不变 .(2 )不放回抽样各次抽取不是相互独立的 ;而放回抽样各次抽取是相互独立的 .(3)对不放回抽样来说 :事件A =“不放回地逐个取k个样品”与事件B =“一次任取k个样品“的概率相等 ,…     

辅助信息下的逆抽样设计算法

通过将逆抽样设计视为一种特殊的二重抽样,建立了二重抽样和为回归估计的二重抽样的一般形式,得到了逆抽样设计算法下的回归估计.模拟分析的结果表明,以回归估计的形式引入较为合适的辅助信息,能够在估计精度上对逆抽样设计算法做出改进.     

过抽样信号的恢复

本文根据傅立叶分析和重抽样理论讨论了关于过抽样信号恢复的处理方法 ,所提出的重抽样信号恢复平均法对于强噪音背景下弱信号的提取 ,其效果是比较明显的     

事后分层方法及其在交通运输抽样调查中的应用

本文介绍事后分层技术，说明了它不仅可用于简单随机抽样，而且可以用于放回ＰＰＳ抽样。给出了事后分层估计量的形式，证明了它的无编性，并给出了它在交通运输抽样调查中的应用。     

吸烟者调查抽样设计案例研究

本文通过对南宁市烟草公司拟进行的吸烟者调查抽样设计案例的研究,讨论了有限总体概率抽样原理和技术方面某些问题的具体应用。其中包括:抽样单位的选择;总体总值的单位均值估计量和比估计量;总体比率的比估计量;直接写出比估计量方差的法则,等等。在此基础上,进行了案例实证分析。     

我国水路货运量短期预测模型

本文对我国逐月水路货运量进行了趋势、季节分析，并利用时间序列分析方法建立了简单、实用的短期预测模型。     

Two-dimensional numerical modelling of shallow water flows over multilayer movable beds

The two-dimensional modelling of shallow water flows over multi-sediment erodible beds is presented. A novel approach is developed for the treatment of multiple sediment types in morphodynamics. The governing equations include the two-dimensional shallow water equations for hydrodynamics, an Exner-type equation for morphodynamics, a two-dimensional transport equation for the suspended sediments, and a set of empirical equations for entrainment and deposition. Multilayer sedimentary beds are formed of different erodible soils with sediment properties and new exchange conditions between the bed layers are developed for the model. The coupled equations yield a hyperbolic system of balance laws with source terms. As a numerical solver for the system, we implement a fast finite volume characteristics method. The numerical fluxes are reconstructed using the method of characteristics which employs projection techniques. The proposed finite volume solver is simple to implement, satisfies the conservation property and can be used for two-dimensional sediment transport problems in non-homogeneous isotropic beds without need of complicated three-dimensional equations. To assess the performance of the proposed models, we present numerical results for a wide variety of shallow water flows over sedimentary layers. Comparisons to experimental data for dam-break problems over movable beds are also included in this study.     

Simulation of mass transport in series arrays of membranes with “active” solute flow

The behaviour of the volume and solute flows across a series array of several membranes is investigated by simulation, using a model based on the linear thermodynamics of irreversible processes. Locally linear phenomenological equations are integrated along the direction of the flows, giving non-linear flow-force relationships whose shape is in good agreement with the observations. The simulation also shows that an asymmetry of the array is required, in order to obtain both the non-linearity of the flows and the coupling between the water and solute transport, when the former is coupled to a chemical reaction (metabolism coupled ‘active transport).     

On the dependable level of the negative survey

The negative survey is a new way to collect information, which could protect sensitive data and individual privacy. Generally, the results of negative survey need to be converted to positive survey results to acquire positive information. However, the traditional method to estimate positive surveys does not point out the dependable level of the negative survey. In this paper, the dependable level of the negative survey is analyzed by studying the confidence coefficient of the negative survey. And a greedy algorithm to calculate the shortest confidence intervals is proposed. Furthermore, the dependable level of multiple-choice negative survey is also analyzed.     

A Survey of High Order Schemes for the Shallow Water Equations

In this paper, we survey our recent work on designing high order positivity-preserving well-balanced finite difference and finite volume WENO (weighted essentially non-oscillatory) schemes, and discontinuous Galerkin finite element schemes for solving the shallow water equations with a non-flat bottom topography. These schemes are genuinely high order accurate in smooth regions for general solutions, are essentially non-oscillatory for general solutions with discontinuities, and at the same time they preserve exactly the water at rest or the more general moving water steady state solutions. A simple positivity-preserving limiter, valid under suitable CFL condition, has been introduced in one dimension and reformulated to two dimensions with triangular meshes, and we prove that the resulting schemes guarantee the positivity of the water depth.     

Efficient Numerical Methods for an Anisotropic,Nonisothermal, Two-Phase Transport Model of Proton Exchange Membrane Fuel Cell

We carry out model and numerical studies for a three-dimensional, anisotropic, nonisothermal, two-phase steady state transport model of proton exchange membrane fuel cell (PEMFC) in this paper. Besides fully addressing the conservation equations of mass, momentum, species, charge and energy equations arising in the PEMFC, we present some efficient numerical methods for this model to achieve a fast and convergent nonlinear iteration, comparing to the oscillatory and nonconvergent iteration conducted by commercial flow solvers or in-house codes with standard finite element/volume method. In a framework of a combined finite element-upwind finite volume method, Kirchhoff transformation plays an important role in dealing with the discontinuous and degenerate water diffusivity in its transport equation. Preconditioned GMRES solver together with Newton’s linearization scheme make the entire numerical simulation more efficient. Three-dimensional numerical simulations demonstrate that the convergent physical solutions can be attained within 30 steps. Numerical convergence tests are also performed to verify the efficiency and accuracy of the presented numerical algorithms and techniques.     

Steady state numerical simulation of the particle collection efficiency of a new urban sustainable gravity settler using design of experiments by FVM

The aim of this work is to analyze the efficiency of a new sustainable urban gravity settler to avoid the solid particle transport, to improve the water waste quality and to prevent pollution problems due to rain water harvesting in areas with no drainage pavement. In order to get this objective, it is necessary to solve particle transport equations along with the turbulent fluid flow equations since there are two phases: solid phase (sand particles) and fluid phase (water). In the first place, the turbulent flow is modelled by solving the Reynolds-averaged Navier-Stokes (RANS) equations for incompressible viscous flows through the finite volume method (FVM) and then, once the flow velocity field has been determined, representative particles are tracked using the Lagrangian approach. Within the particle transport models, a particle transport model termed as Lagrangian particle tracking model is used, where particulates are tracked through the flow in a Lagrangian way. The full particulate phase is modelled by just a sample of about 2,000 individual particles. The tracking is carried out by forming a set of ordinary differential equations in time for each particle, consisting of equations for position and velocity. These equations are then integrated using a simple integration method to calculate the behaviour of the particles as they traverse the flow domain. The entire FVM model is built and the design of experiments (DOE) method was used to limit the number of simulations required, saving on the computational time significantly needed to arrive at the optimum configuration of the settler. Finally, conclusions of this work are exposed.