Group-based educational inequalities in India: Have major education policy interventions been effective?     

《International Journal of Educational Development》2020

Despite seven decades of policy thrust, group-based educational inequalities persist in India. The tenacious social group-based stratification often proves to be a hurdle for educational participation policies to be effectively rolled out. Given these realities, this study reviews all major national education policy interventions since t 1950s. Using four rounds of National Sample Survey (NSS) data, we analysed the pattern of educational attainments in terms of Average Years of Schooling (AYS) and educational inequalities in India for the period 1994-2012. Three indices of inequality - Gini, Theil’s enttropy and Atkinson - have been constructed to study inequality by gender, place of residence and social groups. . We also empirically estimated the determinants of educational attainments in India by using OLS and Tobit Models. Further using the Oaxaca-Blinder Decomposition technique, we analysed the educational attainment gaps between groups. The study concludes that policy interventions have done little to reduce the group-based educational attainment gap and it’s time to place improved focus on secondary and higher education while continuing the efforts in primary education.  相似文献   

基于无人机激光点云的树障检测与砍伐树木数量估算     

张苏  齐立忠  韩文军  朱笑笑  习晓环  王成  王濮  聂胜 《中国科学院大学学报》2020,37(6):760-766

电力走廊的树木生长会对输电线路的安全运营造成巨大影响，精确检测出影响线路安全的树木并将其砍伐至关重要。因此，提出一种基于无人机激光点云的树障检测与砍伐树木数量估算方法。首先，对激光点云进行快速自动化处理，先后精确提取地面点、电力线点与植被点；其次，基于电力线点进行分段，并分析电力线与植被点的安全距离，进而确定树障区域的位置和范围；最后，对树障区域植被点云进行单木分割，并统计单木数量，最终实现砍伐树木数量的精准估算。研究结果表明，无人机激光点云可以实现输电通道树障的有效检测与砍伐树木数量的精确估算，总体树木砍伐数量估算精度可达92.3%，可为输电线路安全运营提供遥感技术支撑，也可为电网运维单位制订树木砍伐计划提供可靠依据。  相似文献   

多旋翼无人机微多普勒特性分析与特征提取     

马娇  董勇伟  李原  李凌霄  杨杰芳 《中国科学院大学学报》2019,36(2):235-243

针对多旋翼无人机目标的识别问题，提出一种基于伽柏（Gabor）变换的瞬时频率估计与快速傅里叶变换（FFT）相结合的微多普勒特征提取算法。首先建立多旋翼无人机旋翼回波模型，并通过仿真分析叶片数目、旋翼转速和初始相位等参数对微多普勒特征的影响，利用Gabor变换得到时频特征。在此基础上通过瞬时频率极大值法提取微多普勒频率，并对瞬时频率采用FFT提取旋翼数和转动频率，从而获得叶片长度估计值。实测数据验证了该算法较为准确地提取无人机的微多普勒参数。  相似文献   

Contribution of uncertainty in estimation of active drag using assisted towing method in front crawl swimming     

Pendar Hazrati  Peter James Sinclair  Wayne Spratford  René Edouard Ferdinands  Bruce Robert Mason 《Journal of sports sciences》2018,36(1):7-13

Active drag force in swimming can be calculated from a function of five different variables: swim velocity, tow velocity, belt force, power output and exponent of velocity. The accuracy of the drag force value is dependent on the accuracy of each variable, and on the contribution of each variable to drag estimation. To calculate uncertainty in drag value, first the derivatives of the active drag equation with respect to each variable were obtained. Second, these were multiplied by the uncertainty of that variable. Twelve national age and open level swimmers were recruited to complete four free swimming and five active drag trials. The uncertainties for the free and the tow swim velocities, and for the belt force, contributed approximately 5–6% and 2–3% error, respectively, in calculation of drag. The result of the uncertainty of the velocity exponent (1.8–2.6) indicated a contribution of about 6% error in active drag. The contribution of unequal power output showed that if a power changed 7.5% between conditions, it would lead to about 30% error in calculated drag. Consequently, if a swimmer did not maintain constant power output between conditions, there would be substantial errors in the calculation of active drag.  相似文献   

海洋产业结构升级、海洋科技创新与海洋经济增长——基于省际面板数据PVAR模型的实证研究     

杜军  寇佳丽  赵培阳 《科技管理研究》2019,(21)

为促进我国海洋经济实现高质量发展，基于2006-2015年的省际面板数据，运用PVAR模型对海洋产业结构升级、海洋科技创新与海洋经济增长之间的动态关系进行实证分析，研究结果表明:海洋产业结构升级对海洋经济增长具有显著的影响，海洋经济增长对海洋科技创新具有显著的影响；从短期来看，海洋经济增长对海洋产业结构升级的正向效应不明显，从长期来看，海洋经济增长能够促进海洋产业结构的优化；海洋科技创新对海洋经济增长的正效应逐渐减弱；海洋产业结构升级对海洋经济增长的贡献率高于海洋科技创新对海洋经济增长的贡献率；海洋产业结构升级是海洋经济增长的格兰杰原因，海洋经济增长是海洋科技创新的格兰杰原因。  相似文献   

Mutual point-winning probabilities (MPW): a new performance measure for table tennis     

Christophe Ley  Yves Dominicy  Wim Bruneel 《Journal of sports sciences》2018,36(23):2684-2690

ABSTRACT

We propose a new performance measure for table tennis players: the mutual point-winning probabilities (MPW) as server and receiver. The MPWs quantify a player’s chances to win a point against a given opponent, and hence nicely complement the classical match statistics history between two players. These new quantities are based on a Bradley-Terry-type statistical model taking into account the importance of individual points, since a rally at 8–2 in the first set is less crucial than a rally at the score of 9–9 in the final set. The MPWs hence reveal a player’s strength on his/her service against a given opponent as well as his/her capacity of scoring crucial points. We estimate the MPWs by means of maximum likelihood estimation and show via a Monte Carlo simulation study that our estimation procedure works well. In order to illustrate the MPWs’ versatile use, we have organized two round-robin tournaments of ten respectively eleven table tennis players from the Belgian table tennis federation. We compare the classical final ranking to the ranking based on MPWs, and we highlight how the MPWs shed new light on strengths and weaknesses of the players.  相似文献   

Enhancing young children's arithmetic skills through non-intensive,computerised kindergarten interventions: A randomised controlled study     

《Teaching and Teacher Education》2014

Children in kindergarten were randomly assigned to adaptive computerised counting or comparison interventions, or to a business-as-usual control group. Children in both intervention groups, including children with poor calculation skills at the start of the intervention, performed better than controls in the posttest. However the effects of training held in grade 1, playing serious counting games improving number knowledge and mental arithmetic performances, and playing serious comparison games, only enhanced the number knowledge proficiency in grade 1. The value of these short periods of intensive gaming in kindergarten are discussed as a look-ahead approach to enhance arithmetic proficiency.  相似文献   

约束条件下的广义最小二乘估计     

朱永娜 《重庆职业技术学院学报》2011,20(4):166-167

本文仿造约束最小二乘估计和广义最小二乘估计的推导方法．给出约束条件下的广义最小二乘估计。  相似文献   

Parameter Estimation Accuracy of the Effort-Moderated Item Response Theory Model Under Multiple Assumption Violations     

Joseph A. Rios  James Soland 《Educational and psychological measurement》2021,81(3):569

As low-stakes testing contexts increase, low test-taking effort may serve as a serious validity threat. One common solution to this problem is to identify noneffortful responses and treat them as missing during parameter estimation via the effort-moderated item response theory (EM-IRT) model. Although this model has been shown to outperform traditional IRT models (e.g., two-parameter logistic [2PL]) in parameter estimation under simulated conditions, prior research has failed to examine its performance under violations to the model’s assumptions. Therefore, the objective of this simulation study was to examine item and mean ability parameter recovery when violating the assumptions that noneffortful responding occurs randomly (Assumption 1) and is unrelated to the underlying ability of examinees (Assumption 2). Results demonstrated that, across conditions, the EM-IRT model provided robust item parameter estimates to violations of Assumption 1. However, bias values greater than 0.20 SDs were observed for the EM-IRT model when violating Assumption 2; nonetheless, these values were still lower than the 2PL model. In terms of mean ability estimates, model results indicated equal performance between the EM-IRT and 2PL models across conditions. Across both models, mean ability estimates were found to be biased by more than 0.25 SDs when violating Assumption 2. However, our accompanying empirical study suggested that this biasing occurred under extreme conditions that may not be present in some operational settings. Overall, these results suggest that the EM-IRT model provides superior item and equal mean ability parameter estimates in the presence of model violations under realistic conditions when compared with the 2PL model.  相似文献   

Parameter estimation of an unstable system with a PID controller in a closed loop configuration     

E. Cheres 《Journal of The Franklin Institute》2006,343(2):204-209

An essential part of the auto-tuning control involves parameter estimation of a suitable low order model. Since a common way to control an unstable system is via a PID controller, there is a growing interest in the application of new PID-based algorithms for the identification task. In this light the relative advantages of two recently published methods are investigated. The first method is based on typical data of the reaction curve and the time delay is measured directly from the initial portion of the curve. The second method utilizes a least-squares algorithm to get an equivalent time delay together with the values of the other parameters. Thus, the obtained time delay approximates not only the true delay but also part of the nonlinear and the higher order dynamics. This is an advantage when a PID auto-tuning is sought. Two examples are provided to demonstrate and compare between the results of the methods.  相似文献