A quantitative field study of the decision behaviour of four shopfloor schedulers

In this article the decision behaviour of four production schedulers in a truck manufacturing company is investigated by means of a quantitative model. The model consists of there parts: performance variables, action variables and disturbance variables. The outcomes show that there is a large difference between schedulers that apparently have the same type of decision problem. Another interesting finding is that some scheduling actions work positively in the short term, but negatively over a longer term. Other results, along with methodological issues of quantitative research, are discussed.     

论航空公司运营中的服务接触及关键事件管理

一般地,顾客根据服务接触形成对航空公司运输服务质量的感知.而从服务过程的角度看,服务接触中的关键事件对顾客服务质量感知有显著影响.根据近年来民航运输消费者的有效投诉情况进行综合分析,航空公司须加强以下几类关键事件的管理:航班延误、排队等待、服务角色、第三方生产者和顾客互动等.只有加强服务接触的各类关键事件的管理,强化服务人员的服务意识,并积极做好修复工作.才能提高航空公司服务接触的质量和产品竞争力.     

基于有限优先级的动态调度算法

实时任务调度是实时系统中的关键问题,实时动态调度是实时调度的主要方面。当实时调度应用于实际的任务系统时,仅能使用有限的优先级数量。实时调度在理论分析时,都假设系统能够识别任意多的优先级。该文提出了在优先级数量有限的条件下的动态调度算法,给出了一个任务系统动态调度所需的最小优先级的数量的算法,并对算法的复杂性进行了分析。     

分布式实时嵌入式系统端到端性能确保

针对具有端到端截非周期任务模型的分布式实时系统,提出了一种ICA算法,构造了一个兼顾非周期实时任务个体性能和总体性能的分布式控制环。该算法能动态调整任务的QoS,从概率上确保了任务的端到端截止时间,并能通过确保CPU利用率来提高系统吞吐量。实验结果证明ICA能为具有端到端非周期任务模型的分布式实时嵌入式系统提供更好的性能确保。     

The bike sharing rebalancing problem: Mathematical formulations and benchmark instances

Bike sharing systems offer a mobility service whereby public bicycles, located at different stations across an urban area, are available for shared use. These systems contribute towards obtaining a more sustainable mobility and decreasing traffic and pollution caused by car transportation. Since the first bike sharing system was installed in Amsterdam in 1965, the number of such applications has increased remarkably so that hundreds of systems are now operating all over the world.In a bike sharing system, users can take a bicycle from a station, use it to perform a journey and then leave it at a station, not necessarily the same one of departure. This behavior typically leads to a situation in which some stations become full and others are empty. Hence, a balanced system requires the redistribution of bicycles among stations.In this paper, we address the Bike sharing Rebalancing Problem (BRP), in which a fleet of capacitated vehicles is employed in order to re-distribute the bikes with the objective of minimizing total cost. This can be viewed as a special one-commodity pickup-and-delivery capacitated vehicle routing problem. We present four mixed integer linear programming formulations of this problem. It is worth noting that the proposed formulations include an exponential number of constraints, hence, tailor-made branch-and-cut algorithms are developed in order to solve them.The mathematical formulations of the BRP were first computationally tested using data obtained for the city of Reggio Emilia, Italy. Our computational study was then extended to include bike sharing systems from other parts of the world. The information derived from the study was used to build a set of benchmark instances for the BRP which we made publicly available on the web. Extensive experimentation of the branch-and-cut algorithms presented in this paper was carried out and an interesting computational comparison of the proposed mathematical formulations is reported. Finally, several insights on the computational difficulty of the problem are highlighted.     

Shift scheduling for tank trucks

In this paper we deal with shift scheduling of tank trucks for a small oil company. Given are a set of tank trucks with different characteristics and a set of drivers with different skills. The objective is to assign a feasible driver to every shift of the tank trucks such that legal and safety restrictions are satisfied, the total working times of the drivers are within desired intervals, requested vacation of the drivers is respected and the trucks are assigned to more favored drivers. We propose a two-phase solution algorithm which is based on a mixed integer linear programming formulation and an improvement procedure. Computational results are reported showing that the algorithm is able to generate feasible schedules in a small amount of time.     

The Fabricare system: a multi-agent-based scheduling prototype

Several trends in society in general, and manufacturing in particular, have changed the way business was made in the last decades of the 20th century, setting new requirements for companies and individuals. The research question being addressed in this paper is concerned with the ability to build computer-supported manufacturing systems able to cope with current and future requirements. For this matter, a hypothesis based on the holonic and multi-agent paradigms is proposed. The paper describes a holonic architecture for manufacturing enterprises and a prototype system (named Fabricare) for manufacturing orders scheduling based on that architecture. A negotiation mechanism called ‘contract net with constraint propagation protocol’ was developed for regulating the interaction between holons in the system. This protocol also implements a negotiation-driven scheduling procedure.     

Scheduling material handling vehicles in a container terminal

Increasing global trade has created the need for efficient container ports. The goal of the port is to move containers as quickly as possible and at the least possible cost. Goods that are delayed at the port are inevitably tardy when delivered to the customer, and thus sanctioned by late charges. Two key activities in the port are (i) unloading of containers from truck and then storage in the export area, and (ii) removal of containers from import storage and then loading onto the trucks. Since containers are large and heavy, specialized material handling vehicles are required for transporting them within the terminal. The focus of this paper is on port terminals where straddle carriers are primarily used to move containers. Container terminals typically have well developed computer and communication networks. Through these networks a terminal scheduler will control and schedule the movement of the straddle carrier fleet in real time. The objective of the terminal scheduler is to minimize the empty travel of straddle carriers, while at the same time minimizing any delays in servicing customers. This paper presents a straddle scheduling procedure that can be used by a terminal scheduler to control the movement of straddle carriers. At its core, the procedure is driven by an assignment algorithm that dynamically matches straddle carriers and trucks, as each becomes available. The procedures were developed and tested in collaboration with the largest container terminal operator in the Port of New York and New Jersey. Using a simulation model of the real system, the superiority of the proposed procedure over two alternative scheduling strategies is illustrated.     

城市物流配送仿真调度系统设计及实证分析

结合仿真调度的特点，提出城市物流配送仿真调度系统总体设计方案，根据准时配送和成本最低的要求，建立城市物流配送仿真调度系统运行机制模型，并对城市共同配送问题进行模拟仿真实例分析，证明该方法的有效性。