Caesarean delivery before 39 weeks associated with selecting an auspicious time for birth in Taiwan

BackgroundCaesarean delivery before 39 weeks of gestation increases the risk of morbidity among infants. Taiwan has one of the highest caesarean rates in the world, but little attention has been paid to this issue. This study aimed to describe the rate of caesarean delivery before 39 weeks gestation among women who did not have labour signs and had a non-emergency caesarean delivery in Taiwan and to examine whether the phenomenon was associated with the Chinese cultural practice of selecting an auspicious time for birth.MethodsWe recruited women at 15–28 weeks of pregnancy at 5 hospitals in northern Taiwan and followed them at 4 or 5 weeks after delivery using structured questionnaires. This analysis included 150 primiparous mothers with a singleton pregnancy who had a non-emergency caesarean delivery without the presence of labour signs.ResultsNinety-three of these women (62.0%) had caesarean deliveries before 39 weeks of gestation. Logistic regression analysis showed that women who had selected an auspicious time for delivery (OR = 2.82, 95% CI: 1.15–6.95) and delivered in medical centres (OR = 5.26, 95% CI: 2.25–12.26) were more likely to deliver before 39 weeks of gestation.ConclusionNon-emergency caesarean delivery before 39 weeks of gestation was common among the study women, and was related to the Chinese cultural practice of selecting an auspicious time for birth. Further studies are needed to examine the risks and benefits associated with timing of caesarean delivery in Taiwan in order to generate a consensus among obstetricians and give pregnant women appropriate information.     

A reactive tabu search algorithm for the vehicle routing problem with simultaneous pickups and deliveries

The vehicle routing problem with pickups and deliveries (VRPPD) extends the vehicle routing problem (VRP) by allowing customers to both send and receive goods. The main difficulty of the problem is that the load of vehicles is fluctuating rather than decreasing as in the VRP. We design a reactive tabu search metaheuristic that can check feasibility of proposed moves quickly and reacts to repetitions to guide the search. Several new best solutions are found for benchmark problems.     

回载可分的闭环供应链多配送中心多车辆运输策略

本文从车辆路径的角度研究了具有多个配送中心、多台车辆结合前向物流配送和逆向物流回载的闭环供应链运输策略,考虑回收产品的不同形态和可分批运输的特点,引入库存限制和成本惩罚,建立并分析了问题的数学模型.运用sweep算法把多配送中心转化为单配送中心,引入2σ原则构造了分组的启发式求解方法.算例分析表明该策略的合理有效性.     

直接配送下随机需求库存-路径问题最优平稳策略及其算法

直接配送策略下随机需求库存-路径问题（Stochastic Demand Inventory Routing Problem with Direct Deliveries, SDIRPDD）由于其需求的不确定性、决策的长期性以及其最优策略形式对求解其他库存-路径问题（IRP）的参考价值,使得对SDIPRDD问题的研究成为物流、供应链优化领域研究的一个热点。文章首先证明了无约束SDIRPDD的最优平稳策略为（s,S）形式,并通过分析车辆数约束对客户单阶段期望成本函数的影响,给出了存在车辆数和客户库存容量约束时SDIRPDD问题的最优平稳策略形式,进而提出了一种求解有约束SDIRPDD问题最优平稳策略的近似算法。最后,通过数值算例验证了算法的有效性并分析了结果的现实意义。     

Using Public Feedback and Competitive Rewards to Increase the Safe Driving of Pizza Deliverers

Abstract

This study investigated the effects of a safe driving competition facilitated by publicly-posted individual feedback. The turn-signal use, safety-belt use, and complete intersection stopping of 82 pizza deliverers were observed at two experimental and three control stores, as well as among the civilian population. After baseline observations, pizza deliverers received posted weekly individual feedback on their turn-signal use (at Store A) or complete intersection stops (at Store B). The deliverers' safe driving scores were posted individually on a vertical scale along with their names. Each week the deliverer with the highest average performance was rewarded with a free vehicle-maintenance coupon. Turn-signal use among drivers at Store A (n= 24) increased 22 percentage points from baseline to the intervention phase which was maintained into the withdrawal phase. Complete intersection stopping among drivers at Store B (n= 21) increased 17 percentage points from baseline to the intervention phase and was maintained into the withdrawal phase. Although the winners of the weekly competitions had the greatest increase in performance, non-winners also increased their instances of safe driving during the competition.     

求解带时间窗的客户需求可分条件下的车辆路径问题

物流运输中的车辆路径问题历来是一个重要的理论和实际问题,在同时考虑客户需求可分以及客户方和配送中心时间窗限制的前提下,重新构造了问题模型,并结合蚂蚁算法中转移概率的改进和最大-最小蚂蚁系统,设计了问题求解过程和分割点选取规则,计算结果显示出算法的可行性。另外还与客户需求不可分的情况进行了对比,从而说明在大规模物流运输需求下,可分能带来更好的效果。     

同时集散货物的开放式车辆路径问题研究

本文研究了车辆工作时间限制下同时集散货物的多配送中心开放式车辆路径问题,以车辆数和运输里程最小为目标,建立了多目标规划模型,提出了基于拉格朗日松弛技术和禁忌搜索算法的混合求解算法。 该算法首先求出最优解的最大下界,然后采用客户点的分配和调整策略实现解的可行化,其中禁忌搜索引入了4种领域搜索方法,采用了随机变领域搜索方法和重起策略。算例分析表明,该算法能有效地找到满意解,且采用开放式安排路线比闭合式安排路线更加经济合理。