Hendrik Van Landeghem

The State of the Art of Nurse Rostering

Nurse rostering is a complex scheduling problem that affects hospital personnel on a daily basis all over the world. The need for quality software solutions is acute for a number of reasons. In particular, it is very important to efficiently utilise time and effort, to evenly balance the workload among people and to attempt to satisfy personnel preferences. A high quality roster can lead to a more contented and thus more effective workforce.In this review, we discuss nurse rostering within the global personnel scheduling problem in healthcare. We begin by briefly discussing the review and overview papers that have appeared in the literature and by noting the role that nurse rostering plays within the wider context of longer term hospital personnel planning. The main body of the paper describes and critically evaluates solution approaches which span the interdisciplinary spectrum from operations research techniques to artificial intelligence methods. We conclude by drawing on the strengths and weaknesses of the literature to outline the key issues that need addressing in future nurse rostering research.

Robust planning: a new paradigm for demand chain planning

Abstract This paper proposes a new paradigm for tactical demand chain planning (DCP), called robust planning, based on risk assessment of the supply and demand chain. The concepts of supply chain management (SCM), and its extension demand chain management (DCM), have been at the center of much recent research. One of the reasons for this is that, over the last years, a significant number of information systems have emerged, which claim to support the concept. The paper argues that these systems mostly adopt a myopic view of planning, based on pure deterministic planning methods. It demonstrates that such an approach fails to coop with the considerable uncertainty of the planning information. The proposed robust planning paradigm is then introduced and its impact explained, using the well-known example of the beer game. It holds the promise of reducing the number of re-planning cycles, through a better characterization of the expected service level performance over a medium planning horizon. Finally, a case study will show the value of robust planning in a European chemical enterprise.

Modeling inventory routing problems in supply chains of high consumption products

Given a distribution center and a set of sales-points with their demand rates, the objective of the inventory routing problem (IRP) is to determine a distribution plan that minimizes fleet operating and average total distribution and inventory holding costs without causing a stock-out at any of the sales-points during a given planning horizon. We propose a new model for the long-term IRP when demand rates are stable and economic order quantity-like policies are used to manage inventories of the sales-points. The proposed model extends the concept of vehicle routes (tours) to vehicle multi-tours. To solve the nonlinear mixed integer formulation of this problem, a column generation based approximation method is suggested. The resulting sub-problems are solved using a savings-based approximation method. The approach is tested on randomly generated problems with different settings of some critical factors to compare our model using multi-tours as basic constructs to the model using simple tours as basic constructs.

Optimising part feeding in the automotive assembly industry: deciding between kitting and line stocking

In a synchronous and fast-paced assembly line operation, it is crucial that the right parts are being supplied at the right time and at the right place. In automotive assembly, the need for efficient material handling part delivery is particularly great because of extensive product customisation and the lack of space to stock all the required parts at the assembly line. This paper introduces a mathematical cost model for evaluating the assignment of parts to one of two possible material supply systems: kitting or line stocking. Case data from an automotive company in Belgium is used to test the model. The results demonstrate that hybrid policies, where some parts will be kitted while others will be stocked in bulk at the line, are preferred to the exclusive use of either material delivery system. The factors influencing the preferred delivery method for individual parts are explored. Numerical results are presented.

A method to align a manufacturing execution system with Lean objectives

The application of information technology and Lean principles have long been seen as mutually exclusive, but both approaches are more and more claimed to be interdependent and complementary. Real-time production information is crucial to make important business decisions. A manufacturing execution system (MES) can provide the necessary support during the Lean journey. MES can trigger, feed or validate the Lean decision-making process by providing useful information. In addition, MES can maintain the process improvements by enforcing the standardised way of working. However, this is only possible when MES is aligned and is kept aligned to the Lean objectives. The MES processes must be included in the continuous improvement cycle to prevent them from becoming obsolete. In this work, a method is proposed to analyse this alignment between Lean and MES. The manufacturing operations management framework provided by ISA 95 is believed to deliver the necessary components to identify and structure this alignment. Mapping MES and Lean activities onto the same framework brings valuable insights about their dependency. The analysis is explored through a case example. Preventing the system from becoming obsolete, by proposing standard model changes, is an important direction for further research.

Rules for integrating fast changeover capabilities into new equipment design

Abstract The importance of short set-up times is becoming more and more important in every type of industry nowadays. How to address this problem is already known for about 20 years. The SMED method, originally developed by the Japanese Industrial Engineer Shigeo Shingo for reducing the time to exchange dies, gives a really straightforward approach to improve existing set-ups and to easily obtain a reduction of up to 90%, with mostly a moderate investment. In these past decade, several people have also realized that instead of improving an “a posteriori” situation, a lot of problems can be prevented during the design phase of the equipment. Only a few authors proposed design rules. These rules generally have a technical or engineering point of view. In several cases, the authors have noted that, even for a brand new equipment, the design can still be improved substantially. This paper extends the already published set of design rules considerably with the rules based on practical experiences from more than 60 set-up reduction projects in different industries over the last 10 years. In addition, the authors strongly believe that the responsibility of the equipment designer goes beyond these technical aspects. An efficient and effective set-up method also needs to be designed. Several basic industrial engineering tools can be used to this end.

An Evolutionary Algorithm and discrete event simulation for optimizing inspection strategies for multi-stage processes

The problem of determining the optimal inspection strategy for a given multi-stage production process, i.e. the inspection strategy that results in the lowest total inspection cost, while still assuring a required output quality, is modelled as a joint optimization of inspection location, type and inspection limits. A fusion between a discrete event simulation to model the multi-stage process subject to inspection and to calculate the resulting inspection costs, and an Evolutionary Algorithm (EA) to optimize the inspection strategies, is suggested.

Safety stock placement problem in capacitated supply chains

Todays highly competitive business environment forces supply chain managers to maintain high service levels while keeping inventory-related costs as low as possible. Therefore, placing the right amount of safety stock at the right places in the supply chain is an important aspect of effective inventory management. This safety stock placement problem, for which some solution strategies have been proposed in the case of uncapacitated supply chains, becomes much more complicated when, in addition to the variability of the demand, capacity constraints also come into play. In this paper we propose a model to locate safety stocks in a capacitated supply chain with the objective of maintaining the required service level. The underlying relationships linking excess capacity, demand variability, and service levels are analysed to gain deeper understanding of the safety stock placement problem in capacitated supply chains. Based on these relationships a solution approach for the problem is proposed and is tested with Monte Carlo simulation.

Rethinking IT governance for SMEs

Purpose – The purpose of this paper is to critically rethink the concepts and the theoretical foundations of IT governance in small‐ and medium‐sized enterprises (SMEs).Design/methodology/approach – The paper is based on multiple case studies. In total, eight cases of outsourced information system projects where failures occurred were selected. An outsourced information system failure (OISF) is suggested as a failure of governance of the IT in a SME environment. A structure for stating propositions derived from two competing theories is proposed (Agency Theory and Theory of Trust).Findings – The results reveal that trust is slightly more important than control issues such as output‐based contracts and structured controls in the governance of IT in SMEs.Practical implications – The world of SMEs is significantly different from that of large companies, and therefore, the concept of IT governance in SMEs needs reconsideration. For researchers and practitioners, it would be more meaningful to focus on actual,...

An integrated model for inventory and production planning in a two-stage hybrid production system

A two-stage hybrid flow-shop production system is considered. The first stage is a process production system and the second stage is a job-shop production system. The two stages are separated by an intermediate warehouse to introduce flexibility (some independence) in the planning of production at both stages. The inventory level at the warehouse should be optimized to provide a trade-off between the cost of carrying the inventory of the semi-finished products, the minimum batch size requirement in the first stage, and the required service level at the second stage. An integrated model for planning the production in these hybrid flow-shop production systems types is developed. The objectives of optimizing the production and inventory costs at the two stages of the system, including the warehouse, while satisfying customer demands, are considered. An algorithm to solve the suggested model is described in detail, and a solution is provided for a real world case, which has inspired the study. A computational study to measure the performance of the approach was also carried out and the results are reported.