基于Benders分解算法的跨区互联电力系统协调规划模型

研究跨区互联电力系统的协调规划,对于提高投资效率实现更大范围的资源配置具有较强现实意义。本文首先描述多区域电力系统扩张规划问题,并建立多区域扩张规划模型,旨在寻求最优的扩容方案,以最小投入来满足多区域电力系统负荷增长需求;其次,采用Benders分解算法将多区域扩张规划问题分解为一个规划主问题和一个运行子问题,通过主子问题之间的迭代求解,获得最终的最优解;最后,对某个典型的包含7个区域的多区域电力系统进行模拟仿真,验证了本文所构建模型及算法的有效性。     

Likelihood estimation for longitudinal zero-inflated power series regression models

In this paper, a zero-inflated power series regression model for longitudinal count data with excess zeros is presented. We demonstrate how to calculate the likelihood for such data when it is assumed that the increment in the cumulative total follows a discrete distribution with a location parameter that depends on a linear function of explanatory variables. Simulation studies indicate that this method can provide improvements in obtaining standard errors of the estimates. We also calculate the dispersion index for this model. The influence of a small perturbation of the dispersion index of the zero-inflated model on likelihood displacement is also studied. The zero-inflated negative binomial regression model is illustrated on data regarding joint damage in psoriatic arthritis.     

Estimating the prevalence of low-lumbar spine bone mineral density in older men with or at risk for HIV infection using normal mixture models

Bone mineral density decreases naturally as we age because existing bone tissue is reabsorbed by the body faster than new bone tissue is synthesized. When this occurs, bones lose calcium and other minerals. What is normal bone mineral density for men 50 years and older? Suitable diagnostic cutoff values for men are less well defined than for women. In this paper, we propose using normal mixture models to estimate the prevalence of low-lumbar spine bone mineral density in men 50 years and older with or at risk for human immunodeficiency virus infection when normal values of bone mineral density are not generally known. The Box–Cox power transformation is used to determine which transformation best suits normal mixture distributions. Parametric bootstrap tests are used to determine the number of mixture components and to determine whether the mixture components are homoscedastic or heteroscedastic.     

Local power properties of some asymptotic tests in symmetric linear regression models

In this paper we obtain asymptotic expansions, up to order n^−1/2 and under a sequence of Pitman alternatives, for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in the class of symmetric linear regression models. This is a wide class of models which encompasses the t model and several other symmetric distributions with longer-than normal tails. The asymptotic distributions of all four statistics are obtained for testing a subset of regression parameters. Furthermore, in order to compare the finite-sample performance of these tests in this class of models, Monte Carlo simulations are presented. An empirical application to a real data set is considered for illustrative purposes.     

Testing bioequivalence for multiple formulations with power and sample size calculations

Bioequivalence (BE) trials play an important role in drug development for demonstrating the BE between test and reference formulations. The key statistical analysis for BE trials is the use of two one‐sided tests (TOST), which is equivalent to showing that the 90% confidence interval of the relative bioavailability is within a given range. Power and sample size calculations for the comparison between one test formulation and the reference formulation has been intensively investigated, and tables and software are available for practical use. From a statistical and logistical perspective, it might be more efficient to test more than one formulation in a single trial. However, approaches for controlling the overall type I error may be required. We propose a method called multiplicity‐adjusted TOST (MATOST) combining multiple comparison adjustment approaches, such as Hochberg's or Dunnett's method, with TOST. Because power and sample size calculations become more complex and are difficult to solve analytically, efficient simulation‐based procedures for this purpose have been developed and implemented in an R package. Some numerical results for a range of scenarios are presented in the paper. We show that given the same overall type I error and power, a BE crossover trial designed to test multiple formulations simultaneously only requires a small increase in the total sample size compared with a simple 2 × 2 crossover design evaluating only one test formulation. Hence, we conclude that testing multiple formulations in a single study is generally an efficient approach. The R package MATOST is available at https://sites.google.com/site/matostbe/ . Copyright © 2012 John Wiley & Sons, Ltd.     

成员企业权力结构对联盟中控制权不对称分布影响的研究

以我国电器制造企业间联盟为样本,考察了成员企业权力结构对联盟控制权不对称分布的影响.结果表明,成员企业的权力结构各因素显著影响着联盟控制权的不对称分布:内部联合权力水平会弱化这种不对称,而其冲突水平则会强化这一不对称;外部联合权力水平会显著强化这种不对称,内外部联合权力间的冲突水平也会强化这种不对称.同时,成员企业的权力结构相似性与联盟中控制权分布的不对称之间存在负相关关系,但这种关系并非线性关系,仅在成员权力结构具有高度相似性时,才会倾向于降低联盟控制权分布的不对称.     

基于中国公司情境的和谐管理领导力研究

在回顾有关领导理论研究的基础上,提出了和谐管理领导力应具备3种特征:组织影响力、内在控制点的个性特征和管理技能.同时,发展了相应的测度和研究量表,通过对中国公司样本的研究,对比了环境、组织、战略与领导4个要素对组织绩效的影响效果,用实证结论支持了和谐管理领导力的观点,即在中国公司情境下,与环境、组织和战略因素相比,领导扮演着更为重要的角色并发挥关键作用.     

多标度条件下资本市场波动的级串方向和结构

对上证综指多标度条件下波动级串方向和结构的实证研究发现,在4days临界标度范围内,大小波动间互为因果;超出临界标度,大小波动间表现出单方向性特征.运用交叉相关系数和功率谱方法从相关性和能量耗散2个角度对多标度波动级串传递方向的分析同样显示,在101～103min的3个数量级广泛标度范围内,大波动对于小波动具有较强预测能力,波动级串结构表现出大波动影响小波动变化的单方向特征.在此基础上,提出了4类"递进"的资本市场波动级串模型及其运用于风险管理的基本思路.     

供电行业用户满意度模型构建及实证研究

在相关理论研究基础上,构建了供电行业用户满意度模型,模型数据采集于江苏省电力公司的800位客户,并采用SAS8．1统计软件包的CALIS功能模块对模型进行了验证分析。研究结果表明：用户期望对用户感知质量、感知价值和用户满意的影响不显著,故在模型中予以删除;企业形象对用户满意和用户忠诚的影响以间接为主,直接影响不显著;修正模型中5个内生隐变量R2的平均值为0．69,经综合考虑,修正后的模型有效可靠。最后,为供电行业提升客户满意度和忠诚度提出建议。