测定小惯性热电偶时间常数新法

研究了用电加热法解决用于动态气流温度测量的小惯性热电偶时间常数的实验测定问题。提出采取在稳定气流场中用电加热热电偶然后迅速切断电源的方法 ,获取较为理想的负温度阶跃 ,进而由热电偶的阶跃响应曲线求得时间常数。设计了相应的设备 ,并进行了实验测定 ,获得了较好的结果。     

论创造性思维的时效性

创造性思维的时效是指创造性思维在一定的时间内所取得的思维成果。在追求创造性思维科学性的同时 ,力求其高效率是创造性思维的目的。我们要运用先进的思维工具 ,采用科学的思维方法 ,尽量减少创造性思维中的挫折和曲折 ,力戒不必要思维时间的浪费 ,以提高创造性思维的效率     

我国城镇养老保险存在的问题及对策探析

文章认为 ,我国城镇养老保险虽取得了很大的成绩 ,但还存在着诸多问题 ,作者对这些问题进行探讨和分析 ,并提出了切实可行的解决对策     

与时俱进 应势而变——浅议入世后我国高等职业教育发展的趋势

入世以后,必将对我国高等职业教育提出新的要求。高等职业教育必须顺应时代发展的趋势,与时俱进、应势而变,才能与时代同步。本文遵循以下思路展开:入世以后,对我国高等职业教育的发展趋势作一些前瞻性的探讨,在此基础上提出应对的措施。有利于我国高等职业教育主动地适应新形势发展的要求。     

论企业组织创新风险

企业组织创新伴随着巨大风险 ,导致创新行为的失败。风险蛰伏在以人为中心、以组织结构为中心和组织流程为中心的组织创新内容中 ,通过创新动机、战略、整合和速度等创新行为要素表现出来。造成创新风险的原因在于企业组织创新动因机理的复杂性、运行过程的动态不平衡性以及组织创新环境与条件的变动性诸方面。     

加强学习把握思路--新形势下高校学生思想工作者必须关注的两个重要方面

着重论述了新形势下高校思想教育工作者应该关注的两个重要方面。其一为加强学习提高自身素质 ,适应时代要求 ,其二为在具体学生工作中应当把握的几个重要方面 ,包括工作思路、道德教育、价值取向 ,以及实践教育、心理素质教育、创新教育等。学习与育人 ,构成了思想工作者提高工作成效的两个基本方面     

被消解了的英雄主义

2 0世纪 80年代以后 ,中国文学经历了先锋文学、新写实主义、新现实主义冲击波、民间化等历程 ,在这一历程中 ,英雄主义被有力地消解了 ,但正是这种消解 ,才有文学精神的愤激和呐喊 ,重塑英雄主义才有可能。     

Simple detection of outlying short time series

Sets of relatively short time series arise in many situations. One aspect of their analysis may be the detection of outlying series. We examine the performance of standard normal outlier tests applied to the means, or to simple functions of the means, of AR(1) series, not necessarily of equal lengths. Although unequal lengths of series implies that the means have unequal variances, that are only known approximately, it is shown that nominal significance levels hold good under most circumstances. Thus a standard outlier test can usefully be applied, avoiding the complication of estimating the time series' parameters. The test's power is affected by unequal lengths, being higher when the slippage occurs in one of the longer series     

Olive Oil Consumption in Greece: A Microeconometric Analysis

In this paper, the factors affecting at-home demand for three types of oils and fats in Greece, with emphasis on olive oil, are investigated using the linear approximation of the Almost Ideal Demand System and family budget survey data. To overcome the econometric problem created with the existence of zero expenditure, a generalization of the two-stage Heckman procedure is employed. In order to investigate the role of self-consumption, two different samples were used. The first includes all households; the second excludes those that acquire olive oil only from own production. According to the results, there are important differences in the first stage of the decision process between the two samples. Unlike the first stage, the second stage of the decision process found no important differences between the results for the two samples.     

Type I error rates from likelihood‐based repeated measures analyses of incomplete longitudinal data

The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SE_Δ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SE_Δ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SE_Δ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd.