LDPC编码的最优化HARQ方案研究

使用高斯近似和最优化理论的方法,对基于LDPC码度分布的混合自动重发请求(HARQ)方案的性能进行了研究。研究表明,根据LDPC编码的度分布和初始信道条件,能够确定一个编码码字中各个度数的比特所对应的最优的重发比例,如果按照该比例进行重发,重发功率的效率能够最大化。计算结果显示基于LDPC码度分布的混合自动重发请求方案具有最优的重发比例,是一种最优化方案。     

概率论在极限问题中的应用

通过建立概率模型、利用概率论相关定理解决了复杂的求极限问题。     

Non parametric mixture priors based on an exponential random scheme

We propose a general procedure for constructing nonparametric priors for Bayesian inference. Under very general assumptions, the proposed prior selects absolutely continuous distribution functions, hence it can be useful with continuous data. We use the notion ofFeller-type approximation, with a random scheme based on the natural exponential family, in order to construct a large class of distribution functions. We show how one can assign a probability to such a class and discuss the main properties of the proposed prior, namedFeller prior. Feller priors are related to mixture models with unknown number of components or, more generally, to mixtures with unknown weight distribution. Two illustrations relative to the estimation of a density and of a mixing distribution are carried out with respect to well known data-set in order to evaluate the performance of our procedure. Computations are performed using a modified version of an MCMC algorithm which is briefly described.     

Nonparametric density estimation from data with a mixture of Berkson and classical errors

The author considers density estimation from contaminated data where the measurement errors come from two very different sources. A first error, of Berkson type, is incurred before the experiment: the variable X of interest is unobservable and only a surrogate can be measured. A second error, of classical type, is incurred after the experiment: the surrogate can only be observed with measurement error. The author develops two nonparametric estimators of the density of X, valid whenever Berkson, classical or a mixture of both errors are present. Rates of convergence of the estimators are derived and a fully data‐driven procedure is proposed. Finite sample performance is investigated via simulations and on a real data example.     

氢化非晶硅膜的制备及其钝化机理

介绍了采用辉光放电(GD)法淀积用作钝化的氢化非晶硅(a-Si:H)膜,并将其应用于硅器件的表面钝化。结果表明,采用a-Si:H钝化,器件表面态密度显著下降,特性有较大改善。此外,对a-Si:H的钝化机理作了讨论。     

高肥条件下种植密度对小麦产量及其构成因素的影响

通过对不同种植密度小麦的籽粒灌浆特性及产量构成因素的研究表明，在土壤肥力和施肥水平较高的条件下，低密度群体（６０～１２０株／ｍ２）小麦的籽粒灌浆速率、穗粒数、千粒重较高密度群体（３００株／ｍ２）都有较大幅度提高，从而使其产量比后者高１０％～３０％．     

玉米种植密度与双棒率及空杆率的调查分析

玉米双棒率与空杆率是影响产量的两个因素，经调查研究表明：双棒率与种植密度有关，密度小，双棒率高，经测验差异显著；空杆率与密度无关，差异不显著。     

变离心力场中等截面冷却通道的流量计算和实验研究

本文用数值计算得到的数据集，回归出在变离心力场下，等截面管流由于热阻力引起的变密度流流量减少公式，并用热平衡法在旋转试验台上测量了加热条件下通道内的加热量和平均流速．由实验数据集回归出的流量减少公式与数值计算结果相符．     

燃烧诱发的炉墙结构振动

本文根据实测得到的国产300MW锅炉燃烧压力场功率谱密度函数,研究了用计算方法估计由燃烧诱发的结构振动,并与用实测方法获得的振动值作了对比,结果很接近。从而证明计算所用的数据与方法是可靠的。     

关于齐次马氏信源二元函数的一类偏差定理

利用任意信源相对熵密度偏差的概念,使用分析的方法研究了齐次马氏信源的一类强偏差定理,得出了一个二元函数的一类强偏差定理和几个极限性质.