P507萃取色谱法分离稀土元素的数学模型研究

本文根据大量的实验数据和色谱理论，提出了P507-RECL3-HCL体系萃取色谱法分离稀土元素时峰宽W的数学模型。研究发现，影响峰宽的因素有树脂床高度H、柱截面积S、洗脱酸酸度C、进料量Q及树脂中P507百分含量P。本文综合影响峰宽的各种因素，提出峰宽的模型，利用参数设计法原理，对三种稀土元素Gd、Tb、Dy模型进行参数识别，检验结果表明，本文所建立的数学模型基本揭示各种因素对峰宽影响的规律。本文建立的峰宽W的数学模型（温度为50℃，线速度为1cm／min）为：当Q＜0．04％时，W＝KaHKhSKsPKp／CKc；当0．04＜Q＜1．5％时，W＝KaHKhSKsPKp／CKc＋K1Q-K2Q2。其中Kh＝0．04％、Ks＝0．9125、Kp＝0．65，Ka、K1、K2为随元素种类变化的常数。如要建立某元素的W模型，只需根据该元素的实验数据，对参数Ka、Kc、K1、K2进行估值，即可求得该元素准确性较高的W模型，用该模型能直接计算此元素在不同条件下的峰宽值。利用本文建立的W数学模型，结合已报道的保留作积Vr数学模型，可通过计算判断稀土元素的分离效果。     

遗传算法在指数投资组合中的应用

将遗传算法运用于证券指数投资分析，具体解释了染色体、适应值函数在股票投资分析中的实际意义，设计了选择、杂交、变异算子的使用方案，并选用上海证券交易所上证180指数为目标指数进行实证研究。实验结果表明，该算法能够有效地跟踪和模拟180指数。     

4n-2阶发展方程的算子半群

针对高价发展方程的形式解,将二阶发展方程扩展为时滞分布参数系统标准型中的4n?2阶发展方程,同时构造内积形成4n?2维Hilbert空间。将4n?2阶发展方程转化为一阶发展方程组,求得4n?2阶发展方程的生成算子和在一定的条件下生成半群。构造出半群的结构式并证明其具有的基本特征。当n=1时为二阶发展方程型的Golstein算子半群。     

Empirical Likelihood for Non-Smooth Criterion Functions

Abstract.  Suppose that X ₁ ,…,  X _n is a sequence of independent random vectors, identically distributed as a d -dimensional random vector X . Let     be a parameter of interest and     be some nuisance parameter. The unknown, true parameters ( μ ₀ , ν ₀ ) are uniquely determined by the system of equations E { g ( X , μ ₀ , ν ₀ )} =   0 , where g  =  ( g ₁ ,…, g _{p + q} ) is a vector of p + q functions. In this paper we develop an empirical likelihood (EL) method to do inference for the parameter μ ₀ . The results in this paper are valid under very mild conditions on the vector of criterion functions g . In particular, we do not require that g ₁ ,…, g _{p + q} are smooth in μ or ν . This offers the advantage that the criterion function may involve indicators, which are encountered when considering, e.g. differences of quantiles, copulas, ROC curves, to mention just a few examples. We prove the asymptotic limit of the empirical log-likelihood ratio, and carry out a small simulation study to test the performance of the proposed EL method for small samples.     

基于核方法的贝叶斯邮件分类网络研究

提出一种包含核函数的Bayesian参数估计方法,提高了Bayesian参数估计的实用性。结合邮件内容和报文格式两个方面分析和提取邮件的重要特征,建立了对应的Bayesian邮件分类网络。将包含核函数的Bayesian参数估计方法应用到邮件分类网络,在对不同邮件测试集的在线学习试验结果证明,这种新的分类模型能够有效地实现垃圾邮件的分类过滤。     

Option pricing under model and parameter uncertainty using predictive densities

The theoretical price of a financial option is given by the expectation of its discounted expiry time payoff. The computation of this expectation depends on the density of the value of the underlying instrument at expiry time. This density depends on both the parametric model assumed for the behaviour of the underlying, and the values of parameters within the model, such as volatility. However neither the model, nor the parameter values are known. Common practice when pricing options is to assume a specific model, such as geometric Brownian Motion, and to use point estimates of the model parameters, thereby precisely defining a density function.We explicitly acknowledge the uncertainty of model and parameters by constructing the predictive density of the underlying as an average of model predictive densities, weighted by each model's posterior probability. A model's predictive density is constructed by integrating its transition density function by the posterior distribution of its parameters. This is an extension to Bayesian model averaging. Sampling importance-resampling and Monte Carlo algorithms implement the computation. The advantage of this method is that rather than falsely assuming the model and parameter values are known, inherent ignorance is acknowledged and dealt with in a mathematically logical manner, which utilises all information from past and current observations to generate and update option prices. Moreover point estimates for parameters are unnecessary. We use this method to price a European Call option on a share index.     

对混凝土弹性模量影响因素的探讨

本文探讨了影响混凝土弹性模量的各种因素,并对混凝土的抗压强度与弹性模量之间的关系进行了说明.     

Cryptosporidium Dose Response Studies: Variation Between Isolates

The infectivity of three different isolates of the waterborne protozoan parasite Cryptosporidium parvum has been tested in human feeding studies. These three isolates (Iowa, TAMU, and UCP) have different ID50s, indicating substantial variation in their infectivity for humans. This finding is of great importance for quantitative risk assessment as it provides strong evidence for heterogeneity in infectivity among isolates of the same species.     

电容近炸引信的综合参数测试系统

测试电容近炸引信的信号处理电路的动态性能参数,是产品研制、调试、生产的重要环节.利用计算机、信号调理板、数据采集板和在LabView平台上开发的软件,构成一套完整的电容近炸引信综合参数测试系统.该系统针对电容近炸引信的检波放大信号、积分信号、微分信号和启动信号等技术指标进行测试和分析,判断电路工作情况,分析有故障电路的故障原因.该系统具有测试精度高、开发成本低、检测效率高、操作简单等优点.     

含孔洞材料细观韧性损伤的体胞模型分析

本文对六面体含球形微孔洞体胞在不同的三轴应力状态参数和Lode参数条件下进行了三维大应变数值模拟分析。着重讨论了Lode参数的不同对微孔洞在不同方向长大的影响．分析结果表明：（1）Lode参数不同可导致微孔洞在不同方向长大呈现不同的规律，从而使得做孔洞在变形后形状上呈现很大的差异；（2）且Lode参数不同可使微孔洞体胞对应的微孔洞失稳扩张应变有很大的不同．