高速公路项目进度管理信息系统设计研究

本文从项目管理软件发展现状及高速公路项目进度管理现实需求背景出发,利用生命周期法开发方法,对高速公路项目进度管理信息系统的设计进行研究并提出了系统的方案,具体内容涉及到系统功能模块、网络系统结构和数据库结构设计等几个方面。     

Linking performance drivers in production planning and inventory control to process choice

This study investigates how process choice relates to production planning and inventory control decisions. We empirically examine the validity of deductively derived patterns about these types of decisions. More importantly, we look for normative insights by exploring how production planning and inventory control decisions affect operations performance. Our findings show that production line and continuous flow plants use more of a level production strategy, and carry less raw material and work-in-process inventory. The performance drivers for these plants, through which the operations function excels, are effective utilization of equipment, reduced finished goods inventory, and reduced setup down time. To gain forward demand visibility and batching economies, job and batch shops rely much more on backlogs in their planning process. These plants use more of a production chase strategy and position inventory lower in the bills of materials. Four performance drivers for top-performing job and batch shops are to find ways that better anticipate customers' orders, have a more responsive chase strategy, carry less raw material or purchased inventory, and shorten production planning horizon, partly through less reliance on backlogs. It is intriguing that top-performing plants not only do the expected things, given their choice of process, but also excel in selected dimensions—some of which fit the profile normally associated with a different process choice. To monitor and continuously improve operations, evaluation ‘scorecards’ should pay particular attention to performance drivers, which change depending on the plant's process choice.     

The generalized lock scheduling problem: An exact approach

The present paper introduces an integrated approach to solving the generalized lock scheduling problem. Three interrelated sub problems can be discerned: ship placement, chamber assignment and lockage operation scheduling. In their turn, these are closely related to the 2D bin packing problem, the assignment problem and the (parallel) machine scheduling problem respectively. In previous research, the three sub problems mentioned were considered separately, often using (heuristic) interaction between them to obtain better solutions. A mixed integer linear programming model is presented and applied to instances from both inland locks and locks in a tide independent port. The experiments show that small instances incorporating a wide range of real-life constraints can be solved to optimality.     

Assessing the welfare effects of congestion charges in a real world setting

The standard textbook analysis shows that drivers as a group lose from congestion charges. However, it omits taste heterogeneity, shorter travel times far out in the larger network arising from less blocking back of upstream links and the possibility for drivers to reschedule. Taking account of these factors, using a dynamic scheduling model with heterogeneous users we find that all three add significantly to the benefit of the Stockholm congestion charges and that drivers as a group benefit from these charges even without recycling of revenues. This paper also provides an update on the consumer benefits of the Stockholm charges.     

基于云计算技术的铁路调度集中系统架构设计研究

为使铁路调度集中系统更好地满足运输组织需求,提升运输组织效率,阐述我国铁路调度集中系统运用现状,针对存在的系统功能区域化割裂、系统部署灵活性较低、系统建设和运用成本高等问题,结合铁路调度集中系统运用特点,提出基于云计算技术的铁路调度集中系统架构方案,将铁路调度集中系统部署在由云平台资源层、云平台服务层、云平台用户与接口层组成的云平台上,按需分配系统资源并动态扩充系统边界,提升系统资源利用率,提高业务协调性和计划编制的统一性,减轻运输人员的劳动强度,保障铁路运输生产的安全稳定。     

A note on “minimizing a weighted quadratic function of job lateness in the single machine system”

A set of jobs is to be scheduled on a single machine where an idle time is allowed to be inserted before the processing of the first job begins. The objective is to find an optimal sequence that minimizes the weighted sum of a quadratic function of job lateness. Sen et al. [Sen, T., Dileepan, P., Lind, M.R., 1995. Minimizing a weighted quadratic function of job lateness in the single machine system. International Journal of Production Economics 42(3), 237–243] presented a branch-and-bound algorithm for the problem; however, as shown in this note, their algorithm does not work because the branching rule for adjacent jobs is not applicable to non-adjacent jobs.     

An assessment of railway capacity

In this paper, we review the main concepts and methods to perform capacity analyses, and we present an automated tool that is able to perform several capacity analyses. Capacity is extremely dependent on infrastructure, traffic, and operating parameters. Therefore, an in-depth study of the main factors that influence railway capacity is performed on several Spanish railway infrastructures. The results show how the capacity varies according to factors such as train speed, commercial stops, train heterogeneity, distance between railway signals, and timetable robustness.     

Two-machine flow shop scheduling with deteriorating jobs and chain precedence constraints

In this paper we investigate two-machine flow shop scheduling problems with deteriorating jobs and chain precedence constraints. We consider two types of precedence constraints. Under the first type constraints, a successor cannot start on any machine before its predecessor has been completed on the same machine. Under the second one, a successor cannot start on any machine before its predecessor has been completed on all machines. We show that the problem with the first type precedence constraints is polynomially solvable, and the problem with the second type precedence constraints is NP-hard in the strong sense.     

Schedule evaluation in unstable manufacturing environments

This paper provides a new approach to validate the feasibility of schedules of multiple-step mixed-model unstable manufacturing environments with different changeover times. Traditionally, continuous lines in a manufacturing process run the same sequence in order to minimize WIP inventory and lead time. Nevertheless, multiple reasons such as different product mixes or setup times can lead managers to run different sequences in continuous lines. Unfortunately, lack of reliability of supply and demand in these environments makes it difficult to manage product inventories and often leads to starvation due to the discoordination between the schedules of both lines. This approach is based on a new type of visual representation of schedules and an estimate the probability of starvation. It assumes stochastic supply and demand and a predefined schedule sequence based on batches of different sizes.