考虑储存成本的集装箱公铁联运路径优化

联运企业的效益受运输路径和运输方式的影响。如何降低联运成本、提高联运企业的效益,已成为学术研究的重中之重。针对集装箱公铁联运路径优化问题,以运输成本、换装成本、储存成本、时间惩罚成本构成的运输总成本为目标函数,建立集装箱公铁联运路径优化模型,考虑运输时间限制、班期限制、节点储存成本,得出使运输总成本最低的运输路径及运输方式,并利用算例验证模型的有效性。     

Children’s narrative story stem responses: Contributions of executive functioning and language proficiency to relationship representations

Story stem narrative tasks provide insight into young children's inner experiences. Little research has investigated how developmental capacities impact narrative content and process. This study evaluates the influence of executive functioning (EF) and language ability on children's narratives. Data were gathered from 210 low‐income children. EF and language ability were assessed at age 4 and EF was assessed at age 6 via direct examination, cognitive‐motor tasks, and examiner ratings. Children's responses to eight story stems were gathered at age 6; three latent narrative variables were constructed (Prosocial, Aggressive/Conflict, and Avoidance/Danger), and Narrative Coherence was rated. Results of longitudinal path analyses in structural equation modeling demonstrated age 4 EF significantly predicted all narrative outcomes. Language ability independently predicted Prosocial and Narrative Coherence, and had an influence on Aggression/Conflict when modeled with EF. Age 6 EF mediated the relationship between age 4 EF and narrative outcomes. Findings provide insight into developmental abilities that influence on children's narrative responses to challenging interpersonal scenarios. Future research should study parent–child relations, EF, and language abilities simultaneously.     

Exact distributions of two non-central generalized Wilks's statistics

We derive the exact expressions of the probability density function (pdf) and the cumulative distribution function (cdf) of Wilks's likelihood ratio criterion Λ and Wilks-Lawley's statistic U in the non-central linear and the non-central planar cases. Those expressions are given in rapidly converging infinite series and can be used for numerical computation. For applications, we compute the exact power of these statistics in a multivariate analysis of variance exercise, and show by simulation the precision of our analytic formulae.     

Estimating ordered quantiles of two exponential populations with a common minimum guarantee time

The problem of estimating ordered quantiles of two exponential populations is considered, assuming equality of location parameters (minimum guarantee times), using the quadratic loss function. Under order restrictions, we propose new estimators which are the isotonized version of the MLEs, call it, restricted MLE. A sufficient condition for improving equivariant estimators is derived under order restrictions on the quantiles. Consequently, estimators improving upon the old estimators have been derived. A detailed numerical study has been done to evaluate the performance of proposed estimators using the Monte-Carlo simulation method and recommendations have been made for the use of the estimators.     

1981—2014年中国资本服务流量测算——基于截断正态退役分布和几何役龄效率剖面

通过梳理资本核算理论框架,结合中国实际情况测量了1981-2014年资本服务流量。资本分类、组合役龄效率-退役剖面计算、资本回报率确定和初始单位效率生产性资本存量估计等方面与既有研究有所不同。测量结果表明:按照1990年不变价格,各类资本服务流量呈增加趋势,其中无形资产服务流量前期较为波动;设备类服务流量增速最高;总资本服务增长率前期呈V型后期呈倒U型,与GDP增速变动不一致,整体来看前者高于后者;比较发现测量结果高于其它研究,差距先收敛后扩大。     

A note on the mean residual life of a coherent system with a cold standby component

In this paper, we investigate the effect of a cold standby component on the mean residual life (MRL) of a system. When the system fails, a cold standby component is immediately put in operation. We particularly focus on the coherent systems in which, after putting the standby component into operation, the failure of the system is due to the next component failure. For these systems, we define MRL functions and obtain their explicit expressions. Also some stochastic ordering results are provided. Such systems include k-out-of-n systems. Hence, our results extend some results in literature.     

Effect of tuberculosis on immune restoration among HIV-infected patients receiving antiretroviral therapy

In this article, time to immune recovery during antiretroviral therapy was estimated and compared between HIV-infected children with and without tuberculosis (TB). CD4?T-cell restoration was used as a criterion for determining immune recovery. The median residual lifetime function, which is more intuitive and robust compared to the frequently used measures of lifetime data, was used to estimate time to CD4?T-cell restoration. The median residual lifetime is not influenced by extreme observations and heavy-tailed distributions which are commonly encountered in clinical studies. Permutation-based methods were used to compare the CD4?T-cell restoration times between the two groups of patients. Our results indicate that children with TB had uniformly higher median residual lifetimes to immune recovery compared to those without TB. Although TB was associated with slower CD4?T-cell restoration, the differences between the restoration times of the two groups were not statistically significant.     

A robust automatic clustering algorithm for probability density functions with application to categorizing color images

This study develops a robust automatic algorithm for clustering probability density functions based on the previous research. Unlike other existing methods that often pre-determine the number of clusters, this method can self-organize data groups based on the original data structure. The proposed clustering method is also robust in regards to noise. Three examples of synthetic data and a real-world COREL dataset are utilized to illustrate the accurateness and effectiveness of the proposed approach.     

房价对企业技术创新产出的成本效应与投资效应研究——基于A股上市公司数据的实证分析

文章将房价对企业创新水平的影响归结为"成本效应"及"投资效应"两种影响机制，并分析了房地产价格、房产性投资行为、房产性投资的深化以及企业技术创新产出之间的关系。文章的创新之处在于，将创新要素投入和创新管理水平作为中介变量，从理论和实证两方面检验房价和创新产出的关系。基于提出的理论观点利用A股上市公司数据，对研究假设进行了实证研究，得到如下结论：房价对企业技术创新水平的影响机制至少是通过"成本效应"与"投资效应"两条渠道实现的；房价对企业技术创新水平的"成本效应"是通过技术创新投入作为中介对技术创新成果产生影响；房价对企业技术创新水平的"投资效应"是通过技术创新管理水平作为中介对技术创新成果产生影响；未能证实房产性投资会挤压上市公司技术创新投入。文章的研究结论具有以下重要政策启示意义：应当重视房地产价格对企业技术创新产出的"成本效应"。在新旧动能转换的背景下，创新人才的稀缺性提高了其在劳动力市场的议价能力，作为生活必需品的房屋价格上涨，会导致创新人才的劳动力价格随之上涨，这势必加大企业技术创新投入的负担，影响企业的转型升级和长期发展质量；A股企业的房地产投资并未挤压技术创新投入，但降低了企业创新的效率。在政策上，应当制定相关技术创新效率的考察指标，促进骨干型企业重视其创新效率的提升。