大口径光束波前采样器(孔栅)的研制

应用平面波角谱理论，分析了采样器对光波场采样和分光的基本原理以及对空间采样频率的选择规则，描述了实际研制的大口径采样器的结构设计，并通过数值方法和高能激光大气传输实验研究了高能激光经采样器前／后的远场光斑分布关系。结果表明：利用光束波前采样器能高保真地实现对高能激光束的分光。     

Design and Experimental Characterization of Low‐Volume PM10/2.5/1.0 Trichotomous Sampler Inlet

This paper presents the development and laboratory evaluation of a PM10/2.5/1.0 trichotomous sampling inlet that consists of two main parts: a previously designed PM10 size‐selective inlet part and a PM2.5/1.0 two‐stage virtual impactor, which was newly fabricated and attached serially to the PM10 size selective inlet part. Particles are collected in three locations through the trichotomous sampling inlet to provide for not only particle concentration measurements of PM10, PM2.5 and PM1.0, but also those of PM2.5–10 and PM1.0–2.5.     

A Generalized Markov Sampler

A recent development of the Markov chain Monte Carlo (MCMC) technique is the emergence of MCMC samplers that allow transitions between different models. Such samplers make possible a range of computational tasks involving models, including model selection, model evaluation, model averaging and hypothesis testing. An example of this type of sampler is the reversible jump MCMC sampler, which is a generalization of the Metropolis–Hastings algorithm. Here, we present a new MCMC sampler of this type. The new sampler is a generalization of the Gibbs sampler, but somewhat surprisingly, it also turns out to encompass as particular cases all of the well-known MCMC samplers, including those of Metropolis, Barker, and Hastings. Moreover, the new sampler generalizes the reversible jump MCMC. It therefore appears to be a very general framework for MCMC sampling. This paper describes the new sampler and illustrates its use in three applications in Computational Biology, specifically determination of consensus sequences, phylogenetic inference and delineation of isochores via multiple change-point analysis.     

Asymptotic behavior of eigenvalues and random updating schemes

For a stochastic matrix (Q _ij ^T ) _i,j=1 ^M withQ _ij ^T exp(–U(ij)/T) at the off-diagonal positions, we develop an algorithm to evaluate the asymptotic convergence rate of all eigenvalues ofQ _ij ^T asT 0 using Ventcel's optimal graphs. As an application we can compare the convergence rates of some random updating schemes used in image processing.This research was partially supported by the National Science Council, Taiwan and Air Force Office of Scientific Research Contract No. F49620 S5C 0144, and was completed while Tzuu-Shuh Chiang was visiting the Center for Stochastic Processes, Department of Statistics, University of North Carolina, Chapel Hill, NC 27599-3260, USA.     

新型二氧化硫被动采样器的研制

研究了一种新型二氧化硫被动采样器。考察了无纺布、定性滤纸和定量滤纸等吸收剂的载体在相同情况下对二氧化硫和二氧化氮的吸收效果 ,对吸收载体进行了优选。并针对低温地区和高温高湿的气候条件 ,确立了以三乙醇胺(TEA)为吸收主体 ,分别以乙二醇、丙三醇为添加剂的吸收体系。     

A Note on Convergence of the Equi-Energy Sampler

This paper studies maximum likelihood estimation for a parameterised elliptic diffusion in a manifold. The focus is on asymptotic properties of maximum likelihood estimates obtained from continuous time observation. These are well known when the underlying manifold is a Euclidean space. However, no systematic study exists in the case of a general manifold. The starting point is to write down the likelihood function and equation. This is achieved using the tools of stochastic differential geometry. Consistency, asymptotic normality and asymptotic optimality of maximum likelihood estimates are then proved, under regularity assumptions. Numerical computation of maximum likelihood estimates is briefly discussed.     

Mixing time of an unaligned Gibbs sampler on the square

The paper concerns a particular example of the Gibbs sampler and its mixing efficiency. Coordinates of a point are rerandomized in the unit square ${[0,1]}^2$ to approach a stationary distribution with density proportional to $exp(?A^2{(u?v)}^2)$ for $(u,v)\in {[0,1]}^2$ with some large parameter $A$.Diaconis conjectured the mixing time of this process to be $O\left(A^2\right)$ which we confirm in this paper. This improves on the currently known $O(exp\left(A^2\right))$ estimate.     

泊松逆高斯回归模型的贝叶斯统计推断

本文研究泊松逆高斯回归模型的贝叶斯统计推断.基于应用Gibbs抽样,Metropolis-Hastings算法以及Multiple-Try Metropolis算法等MCMC统计方法计算模型未知参数和潜变量的联合贝叶斯估计,并引入两个拟合优度统计量来评价提出的泊松逆高斯回归模型的合理性.若干模拟研究与一个实证分析说明方...     

取样管型流分相式气液两相流体流量计

提出了用取样管来组成一种分流分相式气液两相流体流量计,通过取样管从被测两相流中成比例地分流出一部分气液混合物,然后应用-小型分离器将其分离成单相气体和液体,并用单相流量计分别测量它们的流量,最后根据测量值计算被测两相流体的各相总流量.文中给出了这种两相流体流量计的组成原理,分流系数特性及实验结果.研究结果表明,取样管的端口形状对分流系数的特性影响较大,其中S型端口的效果较理想,能够在较宽的测量范围内保持分流系数的稳定.     

Dialysis membrane sampler for on-line flow injection analysis/chemiluminescence-detection of peroxynitrite in biological samples

Peroxynitrite, as a derivative of nitric oxide, is a potent oxidant. It reacts with several biological molecules, makes cellular and tissue damages, and is related with many diseases; therefore, it is of major concern in current medical research works. In this work, a special perm-selective cellulose acetate membrane sampler is used to implement flow injection analysis (FIA)/chemiluminscence (CL)-detection method for the detection of peroxynitrite with Luminol CL-reagent. Optimum detection conditions were established, and the permeability of peroxynitrite through cellulose acetate (CA) membrane, as well as the interference from matrix constituents were studied. The proposed method has the high sensitivity of the CL-detection and the selectivity of perm-selective membrane sampler. The obtained detection limit of 1×10⁻¹¹ M (without dialysis membrane) and 1×10⁻¹⁰ M (with dialysis membrane), makes it possible to monitor the elusive peroxynitrite in biological samples. The mechanism of luminol CL-emission generated during oxidation by peroxynitrite and the kinetics of peroxynitrite decomposition were also studied using FIA/CL-detection set-up.