化学热力学函数偏微商等式证明方法探讨

从基础热力学函数的相互关系出发，结合偏微商运算基本原理，归纳热力学函数偏微商变换的常用途径，并对化学热力学函数偏微商式的证明方法及技巧进行一些具体研讨。     

方向导数和偏导数

通过对方向导数和偏导数两者间区别与联系的论述，揭示了它们是同属于函数变化率问题的两个平行的不同的概念．     

Earnings and Consumption Dynamics: A Nonlinear Panel Data Framework

We develop a new quantile‐based panel data framework to study the nature of income persistence and the transmission of income shocks to consumption. Log‐earnings are the sum of a general Markovian persistent component and a transitory innovation. The persistence of past shocks to earnings is allowed to vary according to the size and sign of the current shock. Consumption is modeled as an age‐dependent nonlinear function of assets, unobservable tastes, and the two earnings components. We establish the nonparametric identification of the nonlinear earnings process and of the consumption policy rule. Exploiting the enhanced consumption and asset data in recent waves of the Panel Study of Income Dynamics, we find that the earnings process features nonlinear persistence and conditional skewness. We confirm these results using population register data from Norway. We then show that the impact of earnings shocks varies substantially across earnings histories, and that this nonlinearity drives heterogeneous consumption responses. The framework provides new empirical measures of partial insurance in which the transmission of income shocks to consumption varies systematically with assets, the level of the shock, and the history of past shocks.     

Structural Nested Models and Standard Software: A Mathematical Foundation through Partial Likelihood

Abstract.  In observational studies treatment may be adapted to the patient's state during the course of time. These covariates may in turn also react on the treatment under study, and so on. This makes it hard to distinguish between treatment effect and selection bias. Structural nested models aim at estimating treatment effect in such complicated situations, even when treatment may change at any time. We show that structural nested models can often be calculated with standard software, by using standard models to predict treatment as a tool to estimate treatment effect. Robins ( Survival analysis, Volume 6 of Encyclopedia of Biostatistics , John Wiley and Sons, Chichester, 1998) conjectured this, but so far it was unproven. We use a partial likelihood approach to choose the estimators and tests as a subclass of the estimators and tests in Lok (math. ST/0410271 at http://arXiv.org , 2004). We show that this is the class of estimators and tests that can be calculated with standard software. The estimators are consistent and asymptotically normal, and have interesting asymptotic properties.     

多棱镜像营造的跨文化景观 ——《英国情人》与《扶桑》之比较

爱默生的散文贯穿着一条清晰的主线:反对权威、束缚,追求独立、自由.然而,由于他的散文风格表现出以下一些基本特征:语言缺乏连贯性,充满似是而非和否定的句子,使得读者难以捉摸他的话语里的真实含义.研究发现,爱默生模糊的语言风格很接近中国老子似是而非的语言风格,而二人的语言风格代表着他们的真理观和语言观.爱默生刻意通过不连贯、似是而非和否定的修辞手法来表达其哲学主题,以启发读者通过文本寻找真理,而不是直接告诉读者真理是什么.     

Risk of Error and the Kappa Coefficient of a Binary Diagnostic Test in the Presence of Partial Verification

The accuracy of a binary diagnostic test is usually measured in terms of its sensitivity and its specificity, or through positive and negative predictive values. Another way to describe the validity of a binary diagnostic test is the risk of error and the kappa coefficient of the risk of error. The risk of error is the average loss that is caused when incorrectly classifying a non-diseased or a diseased patient, and the kappa coefficient of the risk of error is a measure of the agreement between the diagnostic test and the gold standard. In the presence of partial verification of the disease, the disease status of some patients is unknown, and therefore the evaluation of a diagnostic test cannot be carried out through the traditional method. In this paper, we have deduced the maximum likelihood estimators and variances of the risk of error and of the kappa coefficient of the risk of error in the presence of partial verification of the disease. Simulation experiments have been carried out to study the effect of the verification probabilities on the coverage of the confidence interval of the kappa coefficient.     

Some characterizations of discrete distributions based on weak records

Let X ₁, X ₂,... be iid random variables (rv's) with the support on nonnegative integers and let (W _n , n≥0) denote the corresponding sequence of weak record values. We obtain new characterization of geometric and some other discrete distributions based on different forms of partial independence of rv's W _n and W _n+r —W _n for some fixed n≥0 and r≥1. We also prove that rv's W ₀ and W _n+1 —W _n have identical distribution if and only if (iff) the underlying distribution is geometric.     

汉语否定处置句研究

否定是语言中普遍存在的一种现象,是语法中的重要范畴。就汉语处置句而言,根据否定词出现的位置,否定处置句可分为两种类型：否定前置处置句,否定后置处置句。这两种否定处置句的产生与处置介词语法化的句法环境有密切的关系。否定词前后位置的不同,其否定辖域及否定焦点也随之有所变化。否定词否定辖域及否定焦点和语用因素是两种否定处置句一直广泛存在于汉语方言的一个重要的内在动因,同时阿尔泰语否定词紧靠动词的语序对新疆、甘肃等地汉语方言处置句否定词的位置也有一定影响。     

基于非线性偏最小二乘的操作臂逆解算法

操作臂逆运动学问题是机器人控制中的一项重要内容。目前使用较多的神经网络法大多为多输入多输出或者 多输入单输出方式,需要大量运算。非线性偏最小二乘法( NLPLS)建立的模型分为内部和外部模型,样本数据经外部模 型处理后才用于训练若干个单输入单输出的神经网络。对PUMA560操作臂的仿真试验表明,在相同隐层神经元数的情 况下,该算法比普通神经网络法具有更好的预测精度。这也表明,NLPLS只需较少的隐层神经元数就可以达到普通方法 的精度,从而减少运算量。