Performance of empirical Bayes estimators of random coefficients in multilevel analysis: Some results for the random intercept-only model

For a multilevel model with two levels and only a random intercept, the quality of different estimators of the random intercept is examined. Analytical results are given for the marginal model interpretation where negative estimates of the variance components are allowed for. Except for four or five level-2 units, the Empirical Bayes Estimator (EBE) has a lower average Bayes risk than the Ordinary Least Squares Estimator (OLSE). The EBEs based on restricted maximum likelihood (REML) estimators of the variance components have a lower Bayes risk than the EBEs based on maximum likelihood (ML) estimators. For the hierarchical model interpretation, where estimates of the variance components are restricted being positive, Monte Carlo simulations were done. In this case the EBE has a lower average Bayes risk than the OLSE, also for four or five level-2 units. For large numbers of level-1 (30) or level-2 units (100), the performances of REML-based and ML-based EBEs are comparable. For small numbers of level-1 (10) and level-2 units (25), the REML-based EBEs have a lower Bayes risk than ML-based EBEs only for high intraclass correlations (0.5).     

“捣衣砧上拂还来”释疑

《春江花月夜》中“捣衣砧上拂还来”写的是庭院内之景而非江边之景。捣衣非洗衣、捶衣,而是捣帛或捣 素;捣衣砧非洗衣、捶衣石,而是捣衣时的垫石,它不在水边而在庭院;以捣衣入诗表现的是闺怨闺思,对本诗相思离 别的主题起着一定的暗示作用。     

一种新型交织器的设计

在简单介绍两种常用交织器的基础上,给出了随机分组交织器的设计,并进行了计算机仿真。结果表明,此交织器设计简单,占用内存少,性能明显优于分组交织器,而仅次于随机交织器。     

Construction of D-optimal s 1 × s 2 × s 3 factorial designs using graph theory

In this paper, the maximum determinant of the associated 0-1 matrix in D-Optimal saturated main effect plans for 3× s_2 × s_3 factorials, is derived by the use of Graph theory and Combinatorics. The present work is related to a problem suggested by Chatterjee and Narasimhan (2002). Using the theoretical results, we also give the designs for s₃≥s₂ + 1. This research was supported by the State Scholarships Foundation of Greece.     

解析法化简控制系统传递函数方框图的研究

在经典控制理论中,传递函数方框图化简的常用方法有等效变换法和Mason增益公式法。对于复杂系统的传递函数方框图,等效变换法化简步骤繁琐,Mason增益公式法根据信号流图求传递函数不易理解。提出了一种传递函数方框图化简的解析办法,该方法用解析方程或方程组的形式表示系统输入、输出的关系,是等效变换法和Mason增益公式法的一个很好补充,具有较强的实用性。     

街区经济发展中土地集约利用评价研究——以西安市莲湖区为例

研究目的:以街区经济为平台,定量评价研究区内街区土地集约利用整体状况,以期为其他区域发展街区经济、合理利用土地提供参考。研究方法:地理信息系统(GIS)技术和方法,多因素综合评价法,聚类分析法。研究结果:选择的西安市莲湖区38个街区中,土地集约利用存在一定的差异,较好集约利用3个,一般集约利用24个,低度利用11个,因此在发展街区经济时,应采取提高区域整体经济水平、提高商业用地在整个街区中所占的比例和提高街区商业用地的容积率等措施来提高土地集约利用水平。研究结论:西安市莲湖区街区经济土地集约利用仍有较大潜力。     

高等教育学费问题探讨

对高等教育收费水平的现状进行了分析,预测了收费水平的基本增长趋势。并从影响学费的相关因素的角度对学费水平进行了系统分析,结合办学成本、政府拨款和农村居民可支配收入给出了可行性报告和建议。     

墙体参数模糊下穿墙雷达运动目标成像

针对墙参数模糊条件下运动目标成像速度慢、墙参数重建精度差等问题,提出了一种改进拟牛顿-粒子群优化(Limited Broyden Fletcher Goldfarb Shanno-Particle Swarm Optimization,LBFGS-PSO)算法,建立了LBFGS-PSO算法模型,解决了传统拟牛顿算法和粒子群算法计算速度慢、误差较大等问题。该算法与块正交匹配追踪（Block Orthogonal Matching Pursuit,BOMP）算法相结合不仅可以精确重建边墙位置,还能够准确地重建多径效应环境中的运动目标和静止目标,算法的计算速度和精度得到了一定程度的提高。仿真结果和数据分析验证了所提方法的性能。     

浅谈洛湛线微机计轴设备应用

本文介绍微机计轴自动闭塞在工程中的应用实例,介绍了系统性能、设备安装及调试。     

Shareholder Conflict as a Determinant of Corporate Social Responsibility Commitment for Shared Growth

In this study, we seek to explore shareholder conflicts as a determinant of large firms' corporate social responsibility (CSR) commitment for shared growth with subcontractors. Using a sample of 232 firms in the Korean chaebols during 2006'12, we find that CSR commitment is negatively related to controlling shareholders' cash flow rights but positively related to control-ownership disparity. We also find that foreign blockholders mitigate the positive relationship between CSR commitment and control-ownership disparity. This study offers a view of how controlling shareholders and blockholders protect their interests while enhancing their reputations as good citizens through CSR commitment.