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51.
介绍了一种用渐变镜像传输线阻抗变换器来实现螺旋天线与50Ω馈线之间的宽带匹配技术.实验结果表明,采用渐变镜像传输线阻抗变换器能在2:1的频带范围内实现 ρ<2. 相似文献
52.
本文针对 XS—ZY—125型塑料注射成型机,分析了现行通用的双联泵供油液压系统耗能大的原因。介绍了压力流量补偿负荷传感液压系统在注射机上应用的基本原理。通过应用上述两种液压系统分别驱动同一台注射机的生产运行对比试验和能耗测试分析,证明压力流量补偿负荷传感液压系统具有十分显著的节能效果。通过经济效益估算分析,指出进一步开发压力流量补偿负荷传感液压系统在注射机上的应用,不仅具有十分显著的经济效益,而且具有很大的社会效益。 相似文献
53.
Aycan Çelikaksoy Helena Skyt Nielsen Mette Verner 《Review of Economics of the Household》2006,4(3):253-275
It is a stylized fact that marriage formation involves positive assortative matching on education. We also find this in the
case of immigrants, even when they tend to “import” their spouses and potentially trade off education for other favorable
characteristics. For Pakistanis, we find positive compensating differentials in terms of high education to youth having adopted
host country norms, when marrying a marriage migrant. This indicates that Pakistani marriage migrants pay a premium to be
able to marry and live in Denmark. For Turks, individuals having source country norms pay a premium in order to import a partner,
indicating that unspoiled traditional norms are traded off for education.
相似文献
Mette Verner (Corresponding author)Email: |
54.
The academic performance of over 38,000 Texas students who failed the state’s 1994 reading test was examined through their sophomore year in high school. Propensity score matching resulted in strata with retained and promoted students of comparable observed characteristics. Reading scores were analyzed using a two-level hierarchical linear model. Same grade comparisons show that third graders failing the state-mandated reading test who repeated the grade consistently outperformed in later grades the socially promoted children who also failed the third grade test. Additional analyses indicate that alternative explanations for the findings such as omitted variables, regression to the mean, differential panel attrition and cohort effects are not supported. The results are consistent with findings from other recent studies which suggest that grade retention in third grade may help increase student achievement. 相似文献
55.
采用联立方程法和Acemoglu识别法分别对农民工工作匹配决策机制加以识别,联立方程法检验结果表明收入正向且显著性影响工作任期,而福利虽正向影响并通过收入渠道间接影响工作任期但效果并不显著。Acemoglu识别法检验结果进一步支持了联立方程法检验结论,即农民工工作匹配决策机制为生存导向型,还未上升到发展层面,同时福利待遇已成为农民工稳定就业的重要考量因素。 相似文献
56.
David R. Bickel 《统计学通讯:理论与方法》2013,42(8):1478-1496
By representing fair betting odds according to one or more pairs of confidence set estimators, dual parameter distributions called confidence posteriors secure the coherence of actions without any prior distribution. This theory reduces to the maximization of expected utility when the pair of posteriors is induced by an exact or approximate confidence set estimator or when a reduction rule is applied to the pair. Unlike the p-value, the confidence posterior probability of an interval hypothesis is suitable as an estimator of the indicator of hypothesis truth since it converges to 1 if the hypothesis is true or to 0 otherwise. 相似文献
57.
To approximate the joint distribution of the two-colony stepping-stone model, a finite mixture approach is proposed for constructing discrete multi-variate distributions. This approach generahzes the classic method of linear combinations of independent variables. The stepping-stone model is approximated through matching known moments. Numerical examples from entomology are given. Comparisons are made with the work by Wehrly et al (1993). 相似文献
58.
Daniel B. Radner 《商业与经济统计学杂志》2013,31(2):136-146
This article describes the effects on estimates of the size distribution of family-unit money income produced by adjusting CPS estimates for 1972 by adding several other data sources. Income estimates were adjusted on an individual-observation basis to make them consistent with independent control totals. As a result of these adjustments, mean income for all units rose 12 percent. The relative share of the top 5 percent increased substantially. Property income increased and wage income decreased in relative importance. The adjustment to mean income was largest for the oldest age group and smallest for the youngest age group. 相似文献
59.
Peter C. Austin 《统计学通讯:模拟与计算》2013,42(6):1228-1234
Researchers are increasingly using the standardized difference to compare the distribution of baseline covariates between treatment groups in observational studies. Standardized differences were initially developed in the context of comparing the mean of continuous variables between two groups. However, in medical research, many baseline covariates are dichotomous. In this article, we explore the utility and interpretation of the standardized difference for comparing the prevalence of dichotomous variables between two groups. We examined the relationship between the standardized difference, and the maximal difference in the prevalence of the binary variable between two groups, the relative risk relating the prevalence of the binary variable in one group compared to the prevalence in the other group, and the phi coefficient for measuring correlation between the treatment group and the binary variable. We found that a standardized difference of 10% (or 0.1) is equivalent to having a phi coefficient of 0.05 (indicating negligible correlation) for the correlation between treatment group and the binary variable. 相似文献
60.
基于CHARLS 2015数据,采用倾向得分匹配法实证分析参加医疗保险对农村居民健康的影响。研究发现:参加医疗保险对农村居民的日常活动能力和自评健康影响不显著,参加医疗保险对农村居民认知能力具有显著的正向影响。据此提出,应进一步提升社会医疗保险保障水平、扩大社会医疗保险保障范围、促进商业医疗保险有序发展、推进"三医"高效协同联动等,以充分发挥医疗保险的健康保障功能,从而进一步提升参加医疗保险对农村居民健康的正向影响。 相似文献