树形结构在关系数据库中的压缩存储研究

讨论在关系数据库中压缩存放树形数据结构的方法；数据一致性的保证；分析存储、检索算法的时空复杂度。     

Novel Local Search Method for the Traveling Salesman Problem

A new local search method for the traveling salesman problem based on an original greedy representation of solution space and neighborhood structure is proposed. First, a partial closed route that only consists of three cities is given; then other cities are added to this route by a greedy procedure successively. Implemented on a personal computer, this algorithm finds optimal solutions for 24 out of 27 standard benchmarks, and outperforms the Full Subpath Ejection Algorithm (F-SEC) proposed by Rego in 1998.     

供水管网多事故关阀方案分析

根据多事故点关阀分析的需求建立了基本网络模型,并建立阀门之间的控制关系,应用广度优先搜索遍历供水管网图,找出多事故点时的关阀集。根据阀门之间的控制关系剔除可不关的阀门,得出最优的关阀方案,并列出了受影响的管段。     

试论发达国家海上救助水平的几个要素及对策

文中通过分析发达国家海上搜救的四要素及我国的各要素现状,结合作者的搜救实践,指出我国海上搜救的不足之处,并提出相关对策。     

次任务下的驾驶员视觉搜索能力研究

从视觉搜索的角度研究次任务对驾驶绩效的影响,通过反应时长评价驾驶接管绩效,使用视野测试和眼动数据研究驾驶员视觉搜索能力.自变量为驾驶员所执行的次任务类型和次任务沉浸时长.共采集32名被试在不同沉浸程度下的反应时长和眼动数据,结果表明,经过一段时间的反应后,被试所需要的反应时长缩短且正确率升高.被试所执行的次任务类型对其...     

What drives the drivers? Predicting turnover intentions in the Belgian bus and coach industry

The bus industry is characterized by demanding jobs and high turnover rates. In this study we gather essential insights that can help companies and industry-level policy makers increase the attractiveness of the profession and design effective retention policies. We compare the factors that induce Belgian drivers to leave their current organization with those inducing them to leave the industry. Key factors increasing the likelihood to consider quitting the company are a negative work-life balance, a lack of social support and a temporary contract. Dominant factors to consider quitting the bus driver profession are a lack of fulfillment, a demanding job environment and a negative work-life balance.     

A model and optimization-based heuristic for the operational aircraft maintenance routing problem

This paper investigates the Operational Aircraft Maintenance Routing Problem (OAMRP). Given a set of flights for a specific homogeneous fleet type, this short-term planning problem requires building feasible aircraft routes that cover each flight exactly once and that satisfy maintenance requirements. Basically, these requirements enforce an aircraft to undergo a planned maintenance at a specified station before accumulating a maximum number of flying hours. This stage is significant to airline companies as it directly impacts the fleet availability, safety, and profitability. The contribution of this paper is twofold. First, we elucidate the complexity status of the OAMRP and we propose an exact mixed-integer programming model that includes a polynomial number of variables and constraints. Furthermore, we propose a graph reduction procedure and valid inequalities that aim at improving the model solvability. Second, we propose a very large-scale neighborhood search algorithm along with a procedure for computing tight lower bounds. We present the results of extensive computational experiments that were carried out on real-world flight networks and attest to the efficacy of the proposed exact and heuristic approaches. In particular, we provide evidence that the exact model delivers optimal solutions for instances with up to 354 flights and 8 aircraft, and that the heuristic approach consistently delivers high-quality solutions while requiring short CPU times.     

基于时间卷积自编码网络的实时交通事件自动检测方法

为了提高道路异常交通事件检测效率并降低误报率,提出了一种基于时间卷积自编码网络的实时交通事件自动检测方法。首先设计了基于波动相似性度量的交通模式搜索算法用来筛选具有相同交通规律的样本数据;并构造了交通流模式矩阵作为网络模型输入,以避免样本不均衡与单一样本数据随机性对交通模式学习的干扰;同时设计了新的时间卷积自编码网络对交通模式特征进行无监督提取并对未来交通参数进行合理预测;为了降低交通流参数随机波动性带来的事件判别的干扰,设计了异常状态评估方法,通过对模型预测误差分布的学习,结合当前检测数据给出最终的事件判定结果。采用美国西雅图I90公路与I405公路2015年全年的交通流检测数据与历史事故数据进行实证研究,并与6种典型交通事件检测算法进行性能对比。研究结果表明:基于时间卷积自编码网络的实时交通事件自动检测算法具有较高的检测率、较低的误报率以及更快的平均检测时间;综合各种交通运行情况下,可接受误检率分别为5%、10%时,平均检测率可分别达到93%、98%;同时算法能够自适应学习交通状态的动态变化,对不同交通运行环境具有较强适应性与稳定性。     

关于建立新型搜救系统的思考

通过对现代搜救行动的要求、特点的讨论,说明了建立新型搜救体系的必要性。