基于最优规划的汽车租赁调度分析

针对汽车租赁公司不同目标下的效益最大化,运用分步分析、最优规划、直线折旧等方法,建立转运费最低的、短缺损失费和转运费最低的调度规划模型,使用Matlab7和Lingo软件,得到两个不同目标下的汽车调度方案以及各代理点的最低转运费.其次,使用会计学中的直线折旧法构建基于年度获利最大的购买规划模型,得出年度最大利润并给出了新车购置计划.最后,还对年度利润函数做了进一步讨论.     

农村空心化区域差异因素研究——基于安徽黄山村与江苏尧南社区的个案分析

随着我国工业化和城市化的推进,以及阻碍城乡之间要素自由流动的因素逐渐减少,造成了农村人口向城市的过多流动,出现了农村空心化问题。如何解决农村空心化问题关系到我国新农村建设以及城镇化进程。本文选取安徽省黄山村与江苏省尧南社区作为样本村。在实地进行调研后,获得了空心化有关数据,以此为基础计算空心化率,并利用线性逐步回归模型,计算经济、资源、区位等区域差异因素对样本村空心化率的影响。结果表明,影响黄山村空心化的区域差异因素个数较少,但影响系数较大;影响尧南社区空心化的区域差异因素较多,但影响系数较小。     

温室最低气温与气象因素相关分析

利用山东省气候中心提供的莱芜市某大棚内外2007年12月18日~2008年2月29日气象数据,对温室内最低温度与气象因素数据进行多元回归分析,建立了不同天气条件下温室内最低气温预测模型.     

Assessment of different genetic distances in constructing cotton core subset by genotypic values

One hundred and sixty-eight genotypes of cotton from the same growing region were used as a germplasm group to study the validity of different genetic distances in constructing cotton core subset.Mixed linear model approach was employed to unbiasedly predict genotypic values of 20 traits for eliminating the environmental effect.Six commonly used genetic distances (Euclidean,standardized Euclidean,Mahalanobis,city block,cosine and correlation distances) combining four commonly used hierarchical cluster methods (single distance,complete distance,unweighted pair-group average and Ward's methods) were used in the least distance stepwise sampling (LDSS) method for constructing different core subsets.The analyses of variance (ANOVA) of different evaluating parameters showed that the validities of cosine and correlation distances were inferior to those of Euclidean,standardized Euclidean,Mahalanobis and city block distances.Standardized Euclidean distance was slightly more effective than Euclidean,Mahalanobis and city block distances.The principal analysis validated standardized Euclidean distance in the course of constructing practical core subsets.The covariance matrix of accessions might be ill-conditioned when Mahalanobis distance was used to calculate genetic distance at low sampling percentages,which led to bias in small-sized core subset construction.The standardized Euclidean distance is recommended in core subset construction with LDSS method.     

新型城镇化对房地产价格影响程度的实证研究

新型城镇化的核心是以人为本,重点是解决农民进城后的市民化问题。城镇化给房地产市场带来了广阔的发展空间,导致房地产价格一路飙升。文章主要从人均GDP、当年房地产销售额、城镇居民家庭人均可支配收入、城镇化率等影响城镇化发展的四个因素出发,选取2001--2011年的数据进行实证分析,研究得出城镇化对房地产价格影响的原因及程度。具体为：当年房地产销售额和城镇化率和房地产价格有正相关关系,人均GDP和城镇居民家庭人均可支配收入对房地产价格的影响不具有显著性。     

Citations and RefWorks

ABSTRACT

A practicable approach to meta-assessment is reported involving the use of online research guides as an outreach tool at Western Kentucky University. A series of such guides has been produced that cover each department on campus; this approach lends its way to assessment efforts by identifying discrete and quantifiable target populations across campus. A multiple-regression model is used to predict usage rates on the basis of surrogates for size of potential usership, and variations in quality and size of the guides themselves. The “badness of fit” of the regression model can be used to suggest ways of improving the outreach effort, as the residuals left from the analysis arguably identify related lapses in coverage or promotion. If carried out on an annual basis, the approach provides an almost ideal services assessment tool, since various measures can be taken to improve those guides that during each period are identified as “underachievers.”     

几种均三嗪型活性染料构性关系的研究

本文利用B3LYP/6-311G*方法对几种均三嗪型活性染料化合物进行构型优化,得到了它们的构型参数和轨道参数,然后用逐步回归法对这些参数进行筛选,找出对lnk(水解反应速率常数的对数值)影响较显著的参数.最后用偏最小二乘法建立了此类染料水解反应活性的定量构性关系方程.将所得方程用于同系列染料化合物水解反应速率常数的预测,结果与实测值较为吻合.这些对此类活性染料染色性能的深入研究和新型优良染料的开发有一定的指导意义.     

老年游客旅游决策影响因素之多元逐步回归分析

作者历时2个多月,在大量走访以及问卷调查的基础之上,着重研究分析了影响国内老年游客旅游消费行为的众多因素,并运用多元逐步回归分析方法研究了各因素对老年人旅游消费行为的影响程度。结论显示,影响老年人旅游行为的主要有13个因素,其中老年人的收入水平、旅游地景点的吸引力是影响老年人旅游行为——旅游次数、旅游停留时间和旅游日消费额的共同因素,而收入水平最为关键。     

聚类分析和逐步回归法在车道流量预测中的综合应用

针对目前国内外大中城市中普遍存在的无检测器信号交叉口车道交通流信息难于获取的情况,基于信号控制交叉口车道之间的相关性,综合应用聚类分析和逐步回归法预测单点无检测器信号控制交叉口车道流量.首先应用聚类分析将单点无检测器信号控制交叉口的车道与有检测器信号控制交叉口的车道交通流量进行聚类,然后在聚类分析结果的基础上随机选取车道交通流量样本运用逐步回归法预测单点无检测器信号控制交叉口的车道流量,此方法经过南京市的具体车道流量数据验证.此类问题的解决,可广泛应用于城市交通流诱导系统以及交通控制系统.     

Mostly Harmless Direct Effects: A Comparison of Different Latent Markov Modeling Approaches

We evaluate the performance of the most common estimators of latent Markov (LM) models with covariates in the presence of direct effects of the covariates on the indicators of the LM model. In LM modeling it is common practice not to model such direct effects, ignoring the consequences that might have on the overall model fit and the parameters of interest. However, in the general literature about latent variable modeling it is well known that unmodeled direct effects can severely bias the parameter estimates of the model at hand. We evaluate how the presence of direct effects in?uences the bias and efficiency of the 3 most common estimators of LM models, the 1-step, 2-step, and 3-step approaches. Furthermore, we propose amendments (that were thus far not used in the context of LM modeling) to the 2- and 3-step approaches that make it possible to account for direct effects and eliminate bias as a consequence. This is done by modeling the (possible) direct effects in the first step of the stepwise estimation procedures. We evaluate the proposed estimators through an extensive simulation study, and illustrate them via a real data application. Our results show, first, that the augmented 2-step and 3-step approaches are unbiased and efficient estimators of LM models with direct effects. Second, ignoring the direct effects leads to biased estimates with all existing estimators, the 1-step approach being the most sensitive.