生育政策的地区差异与儿童营养过剩关系研究

近年来,中国的肥胖儿童不断增多。由于该现象发生在“独生子女”政策开始实施以后,后者被认为是前者之因。然而,实证研究的缺乏使生育政策与儿童营养过剩之间的关系尚不明确。使用“中国健康和营养调查”数据,探讨政策与儿童(0-12岁)营养过剩之间的关系。多层模型和纵向分析结果显示,其一,儿童营养过剩的比例在90年代持续攀升,但增长速度较慢。其二,虽然生活在一孩生育政策地区的儿童营养过剩的比例高于其它地区儿童,独生子女营养过剩的比例超过非独生子女,但在其它条件同等的情况下,生育政策的地区差异和姊妹结构与儿童营养过剩概率无显著关联。分析结果并不支持“独生子女政策造成了儿童肥胖”的公共观点。影响儿童营养过剩的主要因素包括父母的体重、母亲的教育、社区发展水平和省份。     

高校排课算法的设计

该文主要介绍了高校排课系统中排课算法的设计,通过在排课之前对要排课的数据进行优化处理,从而使得排课的冲突减少,提高了排课的效率。     

用神经网络对开式冷挤压极限变形程度的预测

给出了基于 BP网络的极限变形程度预测的分析方法 ,得到了开式冷挤压εmax神经网络计算结果 ,与实验结果比较 ,其精度较高 ,证明了神经网络模型在开式冷挤压工艺中应用的可行性。     

Inclusion climate: A multilevel investigation of its antecedents and consequences

This study investigates the antecedents and consequences of organization‐level inclusion climate. A national sample of human resource decision‐makers from 100 organizations described their firms' formal diversity management programs; 3,229 employees reported their perceptions of, and reactions to, their employers' diversity management. Multilevel analyses demonstrate that identity‐conscious programs (programs that target specific identity groups) generate an inclusion climate. Moreover, the analyses provide evidence of multilevel mediation: In organizations with an inclusion climate, individual employees perceive the organization as fulfilling its diversity management obligations and respond with higher levels of affective commitment. This study represents an important step toward understanding how a shared perception of organizational inclusiveness develops and how inclusion climate facilitates the achievement of diversity management objectives. The findings also shed light on the important role of identity‐conscious programs in promoting organizational commitment within a diverse workforce.     

不确定环境下的地震应急救援路径优化研究

针对地震应急救援的特点,引入不确定理论,在地震灾害的背景下,研究震后动态网络环境下的应急救援路径选择问题。用不确定变量表示网络中各路段的破坏程度,综合考虑路径破坏程度及车辆路径连续性等约束条件,以救援时间最短为目标,基于不确定理论建立了动态优化模型,并用改进的遗传算法求解,最后设计算例验证了模型和算法的有效性。     

Searching for empirical linkages between demographic structure and economic growth

Demographic structure could affect economic growth through many channels. However, little is known about how demographic structure affects economic growth since no study has examined an extensive collection of channels through which demographic structure could affect economic growth in a single context. This paper overcomes this limitation by examining 45 potential mediating variables between demographic structure and economic growth. A causal search algorithm is used to identify channels through which demographic structure affects economic growth. Our results suggest that demographic structure affects economic growth differently between developed and developing countries. For developed countries, we find that an increase in the share of middle-aged workers has a positive effect on economic growth through institutions, investment and education channels. On the other hand, an increase in the share of the senior population has a negative effect on economic growth through institutions and investment channels. For developing countries, we find (but with weak evidence) that an increase in the share of young workers has a negative effect on economic growth through investment, financial market development and trade channels.     

基于成本优化的制造业生产物流装配线排序问题分析

为了降低制造业的生产成本，提高收益，在分析生产物流配线闲置和超载成本的基础上，采用粒子群算法对其进行优化，并利用模糊自适应改进惯性权值，通过实证研究表明该方法实用，可操作性强，可以有效降低制造业生产物流成本，具有广泛的应用价值。     

Numerical Maximisation of Likelihood: A Neglected Alternative to EM?

There is by now a long tradition of using the EM algorithm to find maximum‐likelihood estimates (MLEs) when the data are incomplete in any of a wide range of ways, even when the observed‐data likelihood can easily be evaluated and numerical maximisation of that likelihood is available as a conceptually simple route to the MLEs. It is rare in the literature to see numerical maximisation employed if EM is possible. But with excellent general‐purpose numerical optimisers now available free, there is no longer any reason, as a matter of course, to avoid direct numerical maximisation of likelihood. In this tutorial, I present seven examples of models in which numerical maximisation of likelihood appears to have some advantages over the use of EM as a route to MLEs. The mathematical and coding effort is minimal, as there is no need to derive and code the E and M steps, only a likelihood evaluator. In all the examples, the unconstrained optimiser nlm available in R is used, and transformations are used to impose constraints on parameters. I suggest therefore that the following question be asked of proposed new applications of EM: Can the MLEs be found more simply and directly by using a general‐purpose numerical optimiser?     

The trade-off between fixed vehicle costs and time-dependent arrival penalties in a routing problem

This paper introduces the vehicle routing problem with soft time windows (VRPSTW) in which problem definition differs from ones previously defined in literature. Branch-and-price approach is employed, resulting in a set partitioning master problem and its new subproblem. Novel techniques are consequently developed to solve this new subproblem. Experimental results report the comparisons of these solution techniques under the branch-and-price framework. The VRPSTW solutions have further been compared to the state-of-the-art literature, signifying the superiority of the VRPSTW on this issue.     

基于遗传算法的锅炉水位控制器设计

文章分析了锅炉水位控制系统的基本原理及结构,针对传统PID控制器的不足之处设计了基于遗传算法的新型锅炉水位控制器,在此基础上搭建了锅炉水位控制系统。最后,通过仿真验证了该水位控制器在改善水位系统稳态误差及动态超调方面均具有较好的作用。