铝合金材料LY12CZ临界空穴扩张比的适用性探讨

对光滑试样和 3种不同曲率半径的切口试样 ,采用拉伸试验和电镜观测相结合的方法 ,研究了铝合金材料LY12CZ的VGC 参数的适用性。证实VGC 参数对材料的断裂形式较为敏感 ,适用于以拉伸型断裂为主的切口试样 ,对以剪切断裂为主的光滑拉伸试样不适用。     

Costs and distortion of U.S. regulation policy in intercoastal lumber shipping

This article quantitatively analyzes the various impacts of current U.S. coastal restrictions on the Northwest lumber industry. The history of U.S. maritime regulation is briefly reviewed and a simulation model is developed to measure its affect on lumber shipments and transport costs. The results of the model indicate that aggregate cost redutions obtained through deregulation are likely to be small. The pattern of intercoastal shipments could change a great deal, however, with U.S. producers picking up a large share of the Northeast market.     

煤抽出物中含硫化合物的分离

采用硅胶柱色谱与配位体交换薄层色谱（ＰｄＣｌ２／ＳｉＯ２）两步分离，从煤的索氏抽出物芳烃馏分中分离出含硫多环芳香化合物（ＰＡＳＨ）和其他芳香组分，并用毛细管气相色谱（ＦＩＤ和ＦＰＤ）与色质联用仪分析了它门的组成结构。     

顶空气相色谱法测定食品中的蛋白质

本文探讨并优化了顶空气相色谱法测定NH_3 的各项条件,并应用此法来测定食品中的蛋白质含量,测定结果与凯氏定氮法无显著性差异。     

Marshall–Olkin gamma–Weibull distribution with applications

Abstract

A Marshall–Olkin variant of the Provost type gamma–Weibull probability distribution is being introduced in this paper. Some of its statistical functions and numerical characteristics among others characteristics function, moment generalizing function, central moments of real order are derived in the computational series expansion form and various illustrative special cases are discussed. This density function is utilized to model two real data sets. The new distribution provides a better fit than related distributions as measured by the Anderson–Darling and Cramér–von Mises statistics. The proposed distribution could find applications for instance in the physical and biological sciences, hydrology, medicine, meteorology, engineering, etc.     

Use of the Correlation Coefficient with Normal Probability Plots

The use of the correlation coefficient is suggested as a technique for summarizing and objectively evaluating the information contained in probability plots. Goodness-of-fit tests are constructed using this technique for several commonly used plotting positions for the normal distribution. Empirical sampling methods are used to construct the null distribution for these tests, which are then compared on the basis of power against certain nonnormal alternatives. Commonly used regression tests of fit are also included in the comparisons. The results indicate that use of the plotting position p_i = (i - .375)/(n + .25) yields a competitive regression test of fit for normality.     

Multiple Comparison Procedures: The Practical Solution

A practicing statistician looks at the multiple comparison controversy and related issues through the eyes of the users. The concept of consistency is introduced and discussed in relation to five of the more common multiple comparison procedures. All of the procedures are found to be inconsistent except the simplest procedure, the unrestricted least significant difference (LSD) procedure (or multiple t test). For this and other reasons the unrestricted LSD procedure is recommended for general use, with the proviso that it should be viewed as a hypothesis generator rather than as a method for simultaneous hypothesis generation and testing. The implications for Scheffé's test for general contrasts are also discussed, and a new recommendation is made.     

On testes for threshold–type nonlinearity in irregulaly spaced time series

Formulating the model first in continuous time, we have developed a state space approach to the problem of testing for threshold-type nonlinearity when the data are irregularly spaced.     

为优质教育正名 替素质教育解困

文章针对《国家中长期教育改革和发展规划纲要（2010-2020年）》中一些值得商榷的概念和观点,指出：第一,《纲要》提优质教育很好,但只关注＂优质教育资源＂不行,因为优质教育的逻辑起点是＂教育权利与教育公平＂,优质教育质量目标是＂人人享受教育权利与保证教育全过程公平＂和人人成为＂负责公民＂;优质教育的目标人口应为全部受教育者尤其是受高等教育者;第二,＂素质教育＂的原有概念及其实施没有与时俱进;将教育的均衡发展＂剥离于＂推进素质教育之外是＂推进素质教育＂困难的主要原因。