Mathematical modeling of the multi‐run process of crystal pulling from the melt by EFG (Stepanov) technique in dependence on the angle of inclination of the working edges of the dies

A mathematical model for the determination of melt hydrodynamics, impurity concentrations and thermal stresses in the multi‐run process of the growth of sapphire ribbons by EFG (Stepanov) technique with inclinated working surfaces of the dies is considered. The mathematical model deals with thermal conductivity equation, Navier‐Stokes equation, diffusion equation, capillary Laplace equation. This problem has been solved by the finite‐element method. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

有偏总体的EWMA均值控制图

基于总体分布有偏并假定总体分布未知情况下均值-极差控制图的控制限的研究结果,将其推广到EWMA均值控制图,给出总体分布有偏并假定总体分布未知情况下EWMA均值控制图的控制界限,并以质量特性值服从对数正态分布为例,给出EWMA均值控制图的控制效果的模拟分析.     

碱金属原子和类氢离子束缚态能级的解析解

对于碱金属原子和类氢离子的原子实模型,从物理实质图像和极化与贯穿作用的量化及实验资料入手深入地进行了分析,引入了半经验碱金属和类氢原子内部相互作用势,建立了定态薛定谔方程.运用微扰理论获得能级Enl,并进一步导出了有效主量子数、有效核电荷数等重要参数.这对物质化学特性和原子特性研究是有益的.     

全二维气相色谱分析直馏柴油中含硫化合物

采用全二维气相色谱-硫化学发光检测器,以直馏柴油为研究对象,考察了一维色谱柱初始温度、升温速率及两维柱温温差等条件对含硫化合物分离的影响,建立了直馏柴油中含硫化合物的分析方法。本方法对基质复杂的直馏柴油中含硫化合物的分离,并定性分析或归类了直馏柴油中的主要含硫化合物。以苯并噻吩为测试样,以峰面积对浓度作图,硫的浓度在1～100mg/kg范围内,峰面积与硫的浓度呈线性关系,相关系数大于0.999。与传统一维气相色谱相比,全二维气相色谱技术除可检测到苯并噻吩类、二苯并噻吩类等含硫化合物外,还可检测到直馏柴油中的硫醚类化合物;苯并噻吩类和二苯并噻吩类化合物也可得到较好分离。     

一种以TATB/HMX为基炸药的到爆轰距离

利用光纤探针/光电转换器/示波器技术和楔形炸药块方法,采取电炮驱动薄飞片冲击加载产生高压短脉冲激励的装置,测量了一种以TATB/HMX为基炸药的到爆轰距离,研究了到爆轰距离与初始冲击波压力幅值和脉宽的关系,给出了该炸药的POP曲线和表达式。实验结果有助于了解压力脉宽对钝感炸药的冲击起爆和爆轰成长的影响。对于短脉冲冲击加载,入射压力脉宽对炸药的到爆轰距离影响明显,相同实验条件下,压力脉宽越长,炸药的到爆轰距离越短;相同压力脉宽下,加载压力越高,炸药的到爆轰距离越短。     

Deep hydrodesulfurization of FCC gasoline and gas oil cuts: Comparison of CO effect,a by-product from biomass

Regarding the composition of the various feedstocks which should be hydrotreated in order to obtain fuels with amount of sulfur less than 10 wt ppm, we have shown that the presence of traces of CO, a by-product from lignocellulosic biomass feedstock conversion, inhibited the transformation of model compounds representative of FCC gasolines and gas oils over CoMo-based sulfide catalysts. Thus, this effect is more significant in the presence of 2-methylthiophene and 2,3-dimethylbut-2-ene representative of a FCC gasoline than in the presence of dibenzothiophene and 4,6-dimethyldibenzothiophene representative of a straight run gas oil, even if the operating conditions are not the same. This effect is attributed to phenomena of competitive adsorption between sulfur compounds, alkenes and CO on the catalyst surface.     

Liquid chromatography quadrupole time‐of‐flight mass spectrometry identification and determination of tri‐ and hexaaryl chloro imidazoles in sewage sludge

The identification and further quantification of 2‐chloro‐triarylimidazole (o‐Cl‐TAI) and its dimer (o‐DCl‐HABI) in sludge from a sewage treatment plant (STP) is reported for the first time. Liquid chromatography (LC) quadrupole time‐of‐flight (QTOF) mass spectrometry (MS) was used as analytical technique during screening and determination steps. Pollutants were identified following a post‐run search strategy, applying the chlorine mass filter, and characterized by their accurate MS and product ion scan spectra. Finally, their identities were confirmed with authentic standards. The species (o‐Cl‐TAI) has been rated as potentially genotoxic and carcinogenic for mice and rats. Effects of sample preparation in the stability and the extraction efficiency of both compounds are discussed. Under final conditions, they were extracted from freeze‐dried samples (0.5 g of sludge or biosolids dispersed with 2 g of C₁₈ and packed into a polypropylene syringe) with 20 ml of methanol, which also flowed through a clean‐up layer of Florisil and PSA sorbents (0.5 g each). This method attained quantitative extraction yields and limits of quantification between 4 and 10 ng/g. The pollutants o‐Cl‐TAI and o‐DCl‐HABI were ubiquitous in sludge and biosolids obtained in consecutive years from the investigated STP. Their concentrations varied from 0.02 to more than 13 μg/g (freeze‐dried sample). Copyright © 2016 John Wiley & Sons, Ltd.     

基于收支一体化理念我国政府财政变量在经济长期增长中解释能力分析

利用向量自回归(VAR)技术,从收支一体化的角度对1978年以来我国政府公共支出和税收政策变化对经济增长的冲击以及这些冲击在GDP长期走向中的解释能力作了系统的实证研究.实证分析结果表明,我国改革开放以来的财政政策队经济运行的宏观调控方面冲击效应明显,政府的收支行为对经济的长期走向有一定的解释能力.     

On the distribution of the total number of run lengths

In the present paper, we study the distribution of a statistic utilizing the runs length of “reasonably long” series of alike elements (success runs) in a sequence of binary trials. More specifically, we are looking at the sum of exact lengths of subsequences (strings) consisting ofk or more consecutive successes (k is a given positive integer). The investigation of the statistic of interest is accomplished by exploiting an appropriate generalization of the Markov chain embedding technique introduced by Fu and Koutras (1994,J. Amer. Statist. Assoc.,89, 1050–1058) and Koutras and Alexandrou (1995,Ann. Inst. Statist. Math.,47, 743–766). In addition, we explore the conditional distribution of the same statistic, given the number of successes and establish statistical tests for the detection of the null hypothesis of randomness versus the alternative hypothesis of systematic clustering of successes in a sequence of binary outcomes. Research supported by General Secretary of Research and Technology of Greece under grand PENED 2001.     

Comparison of the cuscore, GLRT and cusum control charts for detecting a dynamic mean change

Although statistical process control (SPC) techniques have been focused mostly on detecting constant mean shifts, dynamic and time-varying process changes frequently occur in the monitoring of feedback-controlled and autocorrelated processes. In this research, the performances of cumulative score (Cuscore), generalized likelihood ratio test (GLRT), and cumulative sum (CUSUM) charts in detecting a dynamic mean change that finally approaches a steady-state value are compared. Theoretical results in average run length (ARL) comparison are provided. From the theretical study we find that, when the steady-state value is greater or less than a critical value,Rδ/2+δ/2, the Cuscore and CUSUM charts have a different performance in detecting the mean change. We prove also that the GLRT has the best performance among the three charts in detecting any mean change for which the steady-state value is not equal to δ or δR, when the in-control ARL is large.