(Vapour + liquid) equilibrium in (N,N-dimethylacetamide + methanol + water) at the temperature 313.15 K

Total vapour pressures, measured at the temperature 313.15 K, are reported for the ternary mixture (N,N-dimethylacetamide + methanol + water), and for binary constituents (N,N-dimethylacetamide + methanol) and (N,N-dimethylacetamide + water). The present results are compared with previously obtained data for binary mixtures (amide + water) and (amide + methanol), where amide=N-methylformamide, N,N-dimethylformamide, N-methyl-acetamide, 2-pyrrolidinone and N-methylpyrrolidinone. Moreover, it was found that excess Gibbs free energy of mixing for binary mixtures varies roughly linearly with the molar volume of amide.     

MO theoretical studies of electron pair decorrelation processes. I. Pair correlation energy and single bond dissociation

The homolytic dissociation of a single bond involves the decorrelation of one electron pair. Thus, the contribution of electron correlation to dissociation energies is large. In the present paper a new procedure is presented which allows the computation of the (within the given basis) complete correlation energy of one optimized electron pair. The method which requires only modest computational effort has been applied to the calculation of dissociation energies of a number of bonds of different types. The results show that the correlation of the electron pair of the bond which is broken contributes about 50–80% to the change of the total correlation energy occuring during the dissociation process which amounts to 20–70 kcal/mol. The fraction of correlation contributed by the bond electron pair as well as the relative importance of the left-right correlation within the bond depend very much on the type of the bond. In the case of CC and CH single bonds our method yields dissociation energies which are low by only about 5 kcal/mol. Thus, the method seems to be well suited for the calculation of potential surfaces of non-concerted organic chemical reactions which involve diradicals as intermediates.     

Coupled Hamiltonians and three-dimensional short-range wetting transitions

We address three problems faced by effective interfacial Hamiltonian models of wetting based on a single collective coordinate

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(y) representing the position of the unbinding fluid interface. Problems (P1) and (P2) refer to the predictions of non-universality at the upper critical dimension d = 3 at critical and complete wetting, respectively, which are not borne out by Ising model simulation studies. (P3) relates to mean-field correlation function structure in the underlying continuum Landau model. Building on earlier work by Parry and Boulter we investigate the hypothesis that these concerns arise due to the coupling of order parameter fluctuations near the unbinding interface and wall. For quite general choices of collective coordinates X_i(y) we show that arbitrary two-field models H[X₁,X₂] can recover the required anomalous structure of mean-field correlation functions (P3). To go beyond mean-field theory we introduce a set

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of Hamiltonians based on proper collective coordinates s(y) near the wall which have both interfacial and spin-like components. We argue that an optimum model H[s,

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]

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, in which the degree of coupling is controlled by an angle like variable δ^*, best describes the non-universality of the Ising model and investigate its critical behaviour. For critical wetting the appropriate Ginzburg criterion shows that the true asymptotic critical regime for the local susceptibility χ₁ is dramatically reduced consistent with observations of mean-field behaviour in simulations (P1). For complete wetting the model yields a precise expression for the temperature dependence of the renormalised critical amplitude θ in good agreement with simulations (P2). We highlight the importance of a new wetting parameter which describes the physics that emerges due to the coupling effects.     

居民消费的计量经济模型实证分析

本文在凯恩斯的绝对收入假说的基础上，分析影响居民消费的其他原因，以及这些因素与消费的相关程度，建立计量经济学模型，并采用中国城镇居民的收入消费等统计资料，对消费函数进行实证分析。文中提出用线性二次指数平滑法估算居民对通货膨胀的预期，并指出不应将居民储蓄视为消费的单一方程计量经济学模型中的解释变量，进而有针对性地提出调节总需求的应对策略。     

Roughness of pigment coatings and its influence on gloss

A robust method is used for analyzing roughness at a wide range of lateral length scales. The method is based on two-point correlation where both the amplitude and lateral spacing of surface heights are considered when determining the roughness. Atomic force microcopy and confocal optical microscopy images were captured for a set of pigment-coated samples. The effects of sampling interval, image size and filtering on surface roughness were studied. Isotropy and periodicity of roughness were determined by analyzing the angular distribution of the correlation length (T) and the autocorrelation function (ACF). A clear dependence of root mean square (RMS) roughness (σ) on T was established for randomly distributed surfaces. By taking into account the σ-T dependence it was possible to obtain σ for various length scales for each sample and thus attaining the most relevant σ for a certain surface function, which in this study was specular reflection of light (gloss). The roughness analysis showed that a small amount of DPP coating was sufficient to completely cover and change the surface of the substrate, while kaolin coatings gave a different response.     

On path correlation and PERT bias

Most studies of project time estimation assume that (a) activity times are mutually independent random variables; many also assume that (b) path completion times are mutually independent. In this paper, we subject the impact of both these assumptions to close scrutiny. Using tools from multivariate analysis, we make a theoretical study of the direction of the error in the classical PERT method of estimating mean project completion time when correlation is ignored. We also investigate the effect of activity dependence on the normality of path length via simulation.     

红黄鹅膏菌原亚种及其黄褐变种的傅里叶变换红外光谱鉴别

为了检验傅里叶变换红外光谱技术在变种的水平上鉴别大型真菌的能力,利用该技术对红黄鹅膏菌原亚种样品和红黄鹅膏菌黄褐变种样品作了光谱研究.结果显示它们的傅里叶变换红外光谱在整体上十分相似,仅在相对吸收强度上有微小差异.为了提高光谱灵敏度、放大差异,对它们的光谱做一阶和二阶导数处理并进行相关分析,发现红黄鹅膏菌黄褐变种和两个红黄鹅膏菌原亚种的二阶导数光谱差异十分明显,相关系数仅分别为0.254和0.356,而两个红黄鹅膏菌原亚种的二阶导数光谱较相似,相关系数为0.865.研究表明利用傅里叶变换红外光谱技术结合相关分析可以容易的把红黄鹅膏菌原亚种和红黄鹅膏菌黄褐变种区分开.     

Impact of correlation crises in risk theory: Asymptotics of finite-time ruin probabilities for heavy-tailed claim amounts when some independence and stationarity assumptions are relaxed

In the renewal risk model, several strong hypotheses may be found too restrictive to model accurately the complex evolution of the reserves of an insurance company. In the case where claim sizes are heavy-tailed, we relax the independence and stationarity assumptions and extend some asymptotic results on finite-time ruin probabilities, to take into account possible correlation crises like the one recently bred by the sub-prime crisis: claim amounts, in general assumed to be independent, may suddenly become strongly positively dependent. The impact of dependence and non-stationarity is analyzed and several concrete examples are given.     

一种基于先验模板的图像面积特征测量方法

针对显微视觉中需要反复自动聚焦与自动照明调节以获取高质量图像,降低了微操作效率,提出一种图像特征测量方法.该方法建立在二值图像标准互相关计算模型的基础上.首先,通过设计特殊模板图像,简化该计算模型;通过反推该计算模型,可以在不作预处理基础上,得到目标图像的面积特征参量.利用误差补偿原理,设计两种模板求解两次面积参量,而后求平均值,提高了算法对比度及鲁棒性.强噪音仿真图像实验结果表明:改进方法的测量正确度比常规方法高约20倍;强离焦退化仿真实验表明:改进方法的测量正确度可提高一个数量级.实际图像实验中,改进方法可以在严重离焦以及弱照明条件下有效对图像面积特征进行测量,测量精密度比常规方法高3～5倍.结果表明,该方法在低质量图像面积特征测量中具有实用价值.