NTM方法在非线性贝叶斯动态模型中的应用

将NTM方法应用于非线性贝叶斯动态模型，给出了它的递推公式以及随机变量的数字特征的计算，与蒙特卡洛方法相比提高了效率和精度.     

Swarm intelligence for mixed-variable design optimization

Many engineering optimization problems frequently encounter continuous variables and discrete variables which adds considerably to the solution complexity.Very few of the existing methods can yield a globally optimal solution when the objective functions are non-convex and non-differentiable.This paper presents a hybrid swarm intelligence approach(HSIA)for solving these nonlinear optimization problems which contain integer,discrete,zero-one and continuous variables.HSIA provides an improvement in global search reliability in a mixed-variable space and converges steadily to a good solution.An approach to handle various kinds of variables and constraints is discussed.Comparison testing of several examples of mixed-variable optimization problems in the literature showed that the proposed approach is superior to current methods for finding the best solution,in terms of both solution quality and algorithm robustness.     

Does class-size reduction close the achievement gap? Evidence from TIMSS 2011

Policies about reducing class size have been implemented in the US and Europe in the past decades. Only a few studies have discussed the effects of class size at different levels of student achievement, and their findings have been mixed. We employ quantile regression analysis, coupled with instrumental variables, to examine the causal effects of class size on 4th-grade mathematics achievement at various quantiles. We use data from 14 European countries from the 2011 sample of the Trends in International Mathematics and Science Study (TIMSS). Overall, there are no systematic patterns of class-size effects across quantiles. Class-size effects are generally non-significant and uniform at different achievement levels, which suggests that in most European countries class-size reduction does not have an impact on student achievement and does not close the achievement gap. However, combined estimates across countries indicate that high achievers may benefit more from class-size reduction.     

求解多元函数极值的一种新方法

本文给出了三元函数极值的充分条件和必要条件,并把它推广到了多元函数,给出了求多元函数极值的一个新方法。     

我国沿海地区水产技术推广效率时空演变研究——基于面板三阶段DEA模型的分析

本文基于2006-2016年我国沿海地区水产技术推广的面板数据,运用三阶段DEA模型对沿海11省市剔除环境因素和随机误差项前后的水产技术推广效率进行测度与分析。分析结果表明,沿海地区水产技术推广效率受环境因素影响较大,水产技术推广网站数量、渔民手机数量、渔民人均纯收入和养殖受灾面积对水产技术推广机构、推广人员、推广经费和推广资料影响显著;在剔除环境因素和随机误差项后,大部分地区水产技术推广综合技术效率和规模效率呈现下降,各地普遍处于规模报酬递增状态,规模扩张是技术推广效率提升的关键;2006-2016年,沿海各地区水产技术推广效率变化显著,沿海“渔业大省”水产技术推广效率水平明显优于其他省市。各地区应结合渔业发展现实,挖掘资源优势,加大技术推广投入力度,提高各地区水产技术推广效率。     

College course scarcity and time to degree

College students are taking longer to earn baccalaureate degrees now than ever before, but little is known about institutional factors that may contribute to this trend. In this paper we investigate an important institutional constraint—course scarcity—that we hypothesize may be associated with increased time to degree. We employ a unique administrative dataset from a large, moderately selective, public institution and use an instrumental variables approach, identifying off the random registration times assigned to students. Results suggest that course scarcity does not delay students’ graduation. We explore alternative explanations for our findings and discuss a variety of other factors correlated with time to baccalaureate completion.     

Correlations Among Five Demographic Variables and the Performance of Selected Jamaican 11th-graders on Some Numerical Problems on Energy

This study was designed to assess whether the level of performance of selected Jamaican 11th-grade physics students on some numerical problems on the energy concept was satisfactory and if there were significant differences in their performance linked to their gender, socioeconomic background (SEB), school location, English language and mathematical abilities. The 331 sampled students consisted of 213 boys and 118 girls; 197 students were from a high SEB and 134 students from a low SEB; 296 students were from seven urban schools and 35 students from three rural schools; 112, 153 and 66 of the students had high, average and low English language abilities, respectively, while 144, 81 and 106 of the students had high, average and low mathematical abilities, respectively. An Energy Concept Test (ECT) consisting of six structured numerical questions was employed for data collection. The results indicated that although the students’ level of performance was regarded as fairly satisfactory, there was a lot of room for improvement. There were statistically significant differences in the students’ performance on the ECT linked to SEB, and mathematical abilities in favour of students from a high SEB, and high mathematical abilities, respectively. There was a positive, statistically significant but weak correlation between the students’ (a) mathematical abilities, and (b) English language abilities and their performance on the ECT, while there were no correlations among their gender, school location, and SEB and their performance on the ECT.     

Contribution of limbs’ actions to the four competitive swimming strokes: a nonlinear approach

The aim of our study was to assess the effect of the limbs’ actions on the nonlinear properties of the four competitive swimming strokes. Forty-nine swimmers performed all-out sprints at front-crawl, backstroke, breaststroke and butterfly, each one at full stroke (FS), only the arms’ stroke (AS), and only leg kicking (LK), in a total of 12 bouts, 6 per day. A speedo-meter cable was attached to the swimmer’s hip, to collect the speed-time raw data (f = 50Hz). Velocity, speed fluctuation, sample entropy and fractal dimension were derived from the speed-time series. Significant and moderate-strong effects were noted for both stroke and condition in all variables in the study (p ≤ 0.001; 0,560<η² < 0,952). The four competitive strokes and their three conditions exhibited nonlinear properties. The swimming pattern was less complex and more predictable for LK in comparison to AS and FS. Breaststroke and butterfly have more complex but more predictable patterns than backstroke and front-crawl.     

帕森斯的“结构——功能主义”之探析

帕森斯是现代结构功能主义学派的创始人,一生致力于构建一个包罗万象的、宏大社会学体系。帕森斯的研究取得了重大成果,但也遭到了许多批评。但是,即使是批评者也不得不承认,帕森斯的理论是现代社会学的主要参照点。帕森斯的＂结构—功能主义＂主要理论思想——社会系统理论、结构功能模型、社会变迁思想与＂分化＂理论、两分法理论与模式变量理论。     

Home advantage in Greek football

Abstract

Home advantage as it relates to team performance at football was examined in Superleague Greece using nine seasons of game-by-game performance data, a total of 2160 matches. After adjusting for team ability and annual fluctuations in home advantage, there were significant differences between teams. Previous findings regarding the role of territorial protection were strengthened by the fact that home advantage was above average for the team from Xanthi (P =0.015), while lower for teams from the capital city Athens (P =0.008). There were differences between home and away teams in the incidence of most of the 13 within-game match variables, but associated effect sizes were only moderate. In contrast, outcome ratios derived from these variables, and measuring shot success, had negligible effect sizes. This supported a previous finding that home and away teams differed in the incidence of on-the-ball behaviours, but not in their outcomes. By far the most important predictor of home advantage, as measured by goal difference, was the difference between home and away teams in terms of kicked shots from inside the penalty area. Other types of shots had little effect on the final score. The absence of a running track between spectators and the playing field was also a significant predictor of goal difference, worth an average of 0.102 goals per game to the home team. Travel distance did not affect home advantage.