Operations Research/Management

Research topics

The OM/OR research team focuses on problems that concern how to conduct and coordinate the operations within an organization. More specifically, the operations refer to the production, services and information provided by a company. Whereas previously the principles of operations management were only applied to a single unit in a static environment, the decisions within a company should nowadays be taken in the perspective of a bigger entity in a competitive and dynamic environment. As a result of this increasing complexity, operations research is applied as the primary research methodology to structure, model, analyze and support decisions that concern operations management. Using operations research our research team aims to develop new models, processes and algorithms that are able to optimize the often conflicting goals of the stakeholders in a company. By developing new analytical solution methods and associated decision support systems, the research team OM/OR aims to obtain innovative insights in the organizational policies and external factors of problems.

In addition to operations research, our research team approaches problems in a multidisciplinary way by making use of other methods such as empirical and theoretical research methods, qualitative and quantitative data analysis techniques, artificial intelligence, business intelligence, combinatorial optimization and simulation in function of the purpose of the research.

The research topics of the OM/OR team are organized around five clusters of research:

    1. Project Management: The management of a group of related activities in order to generate a unique product, service or result effectively and efficiently.
    2. Personnel Management: The management of personnel resources within an organization in order to have suitably qualified staff on duty at the right time.
    3. Production Management: The management, planning and control of industrial processes to produce goods and services of the right quality, right quantity, at the right time and at minimum cost.
    4. Sport Management: The management and alignment of the operations within an organization together with the operations of other related companies in order to improve the efficiency and responsiveness of the individual companies and the supply chain as a whole.

    Sport Management: Sport management involves the planning, organization and control within the context of a department whose primary product or service is related to sport or physical activity.

      1. Project Management

        The research on Project Management has initially focused on the scheduling of project activities within the presence of resource constraints. The research team under the guidance of Mario Vanhoucke has a long history that dates back to the end of the 90s. Since 2007, this research has expanded from purely scheduling to the so-called Dynamic Scheduling methodology, which is a Project Management methodology to plan, monitor and control projects in progress in order to deliver them on time and within budget to your client. Its main focus lies in the integration of three crucial aspects, as follows:

        • Baseline Scheduling: Plan your project activities to create a project timetable with time and budget restrictions
        • Schedule Risk Analysis: Analyze the risk of your schedule and its impact on your time and budget
        • Project Control: Measure and analyze your project performance data and take actions to bring your project on track

        Project scheduling: Baseline scheduling is the act of determining start and finish times of each project activity within the activity network and resource constraints and results in an expected timing of the work to be done as well as an expected impact on the project’s time and budget implications.
        The research on baseline scheduling has taken a central place in the research team, and will continue to do so in the future. The main reason is that constructing a baseline schedule is a crucial step in the dynamic scheduling methodology since the project baseline schedule will act as a point-of-reference for your schedule risk and project control steps, as discussed hereunder.
        Project risk
        : Schedule Risk Analysis is a Project Management methodology to assess the risk of the baseline schedule and to forecast the impact to time and budget deviations on the project objectives. The importance of analyzing the risk of the baseline schedule comes from the need of any project manager to restrict his/her attention to the most influential activities of the project that might have the biggest impact on the initial time and cost constraints. It enables them to take better management focus and it supports a more accurate response during project progress that positively contributes to the overall project performance.
        Project control: Project control is the act of monitoring deviations from the expected project progress and controlling its performance in order to facilitate the decision making process in case corrective actions are needed to bring projects back on track. Both traditional Earned Value Management (EVM) and the novel Earned Schedule (ES) methods are used.

        (OM/OR members: Mario Vanhoucke)

      2. Personnel Management

        The personnel management research that is conducted at the OM/OR research team embodies three main categories along with the traditional three phases of the workforce management process, i.e. the strategic phase, the tactical phase and the operational phase.

        Personnel staffing: In the strategic phase long-term decisions are made regarding to the planning of personnel such as determining the organisational structure and the personnel budget in terms of the workforce size and the required competences.
        Personnel scheduling
        : In the tactical phase, a duty roster is composed for the personnel for the next planning period that assigns persons to particular duties on particular days.
        In the operational phase of a schedule decisions need to be taken during the execution of a roster as uncertainty arises leading to schedule disruptions and imbalances between the supply of personnel resources and the demand for its services.
        Integration: Not like the traditional division of the workforce management process in three different distinct phases, the research of the OM/OR team tries to integrate different phases. Feedback between different phases is required to manage the personnel resources properly.
        Integration is also stimulated in terms of problem definition as the OM/OR team recognizes that personnel resources are often employed as ancillary resources. In this perspective our research team studies the integration of personnel resources with other operations management domains.

        (OM/OR members: Mario Vanhoucke, Broos Maenhout, Veronique Limère)

      3. Production Management

        The OM/OR team conducts research to different areas in production management, i.e. production strategy, production scheduling, production control and logistics design of an organization. On a strategic level, the operations within an organization have to be aligned to the production strategy. Manufacturing strategy research tries to provide a structured decision making approach to improve the economics of manufacturing and to make companies more competitive. In the management of production systems, one of the major items is to schedule production systems and to sequence jobs in order to optimize one or multiple objectives. Moreover, a complete logistics organization is necessary to meet the organization’s objectives. If the material handling process is not integrated, production delays may be possible with a negative impact on the company’s objectives.

        International manufacturing strategy: Ann Vereecke studies the way in which the (inter-)national context has an impact on how manufacturing strategies are set, the ways in which companies and countries continually improve their manufacturing capability and the resulting improvement in performance. Ann Vereecke developed a benchmarking tool to study the strategy of plants within global manufacturing networks. Based on empirical research, understanding is gained in the dynamics of a company’s manufacturing architecture and how knowledge sharing can be optimized in a factory network.
        Production scheduling and planning
        : The research on the scheduling of production systems refers especially to the machine scheduling problem. Machine scheduling refers to the processing of jobs on a number of machines to optimize one or more objectives. There exists a wide variety of machine scheduling problems in the literature and this is also reflected in the research at the OM/OR team as various deterministic machine scheduling problems have been investigated. The objective of production planning is to plan the release of work into production units over time in order to match output (supply) to demand in some optimal way. Queuing models of production systems show that cycle times increase nonlinearly with resource utilization, which, in turn, is determined by the release plan produced by the planning system. This dependence is increasingly important as organizations move from creating production plans for individual production lines to entire supply chains that require coordination. In addition to this nonlinear behavior, uncertain demand is a fact of life in most production systems, requiring special operating tactics to minimize costs and ensure desired customer service levels. Tarik Aouam investigates the dependency between utilization, production lead times, and demand uncertainty. His research focuses on incorporating workload-dependent lead times and safety stocks in production planning models and developing effective solution methods to solve the emerging problems.
        Logistics design of an organization: Veronique Limère studies the logistics organization within a company and in particular material handling and supply feeding policies. Material handling is important for production systems to have the right materials, at the right time, at the right place and in the exact amount at the line. Veronique aims to develop a new assembly line feeding model that comprehends new line feeding methods, location and organizational elements. In the near future she plans to integrate the parts supply problem with the assembly line balancing problem by rearranging the production tasks over the workstations such that the storage of parts at the border of the line is optimized. Birger Raa studies the sequencing and routing problem of order pickers in conventional multiparallel- aisle warehouse systems. He developed heuristic optimization methods by reformulating the problem as a classical travelling salesman problem (TSP) and combining this with dedicated local search heuristics.

        (OM/OR members: Ann Vereecke, Mario Vanhoucke, Tarik Aouam, Veronique Limère)

      4. Supply Chain Management

        Our research team OM/OR performs intensive research on supply chain integration, which embodies a close alignment and coordination between all parties of a supply chain starting from purchasing raw materials, manufacturing the product, distributing products and supporting services.

    Supply chain integration: Tarik Aouam develops models and efficient solution methods for problems where two or more functional decisions within supply chain systems are integrated, including production planning decisions, procurement decisions, risk management decisions, distribution decisions and finance decisions. In this perspective, Tarik already performed some research on risk management and delegation in procurement within a project funded by the Indiana Utility Regulatory Commission (IURC). Exploring other risk measures and new contract forms will expand the research on this topic to better regulate the pricing of natural gas to consumers.
    Ann Vereecke investigates different strategy concepts in supply chain management such as supplier integration, supplier collaboration and purchasing management. Ann Vereecke pursued interest in variables such as behavioral characteristics, contextual variables and the development of alliances that might impact the supply chain performance. Different from the other researchers in the team, Ann Vereecke uses both qualitative and quantitative studies.
    Logistics design in the supply chain: Veronique Limère intends to integrate the logistics design within a plant in the complete supply chain. Material handling activities may take place at different points in the supply chain. Research will be performed on the impact of this outsourcing decision on the trade-offs between different part supply methods and the current decision model will be extended to include the entire supply chain and in-plant inventory costs.
    Modeling and optimization at a distribution center: Veronique Limère is co-advisor of a PhD research study that deals with the modeling and optimization of processes, planning methods and man-machine interactions at a distribution center under changing market demand. The industrial partner in this project is facing changing market needs, being changes in requested volumes, product types and lead-time of orders. To deal with an unseen volatile environment, the distributor’s processes and infrastructure must be able to quickly react.
    Vendor managed inventory problems
    : Birger Raa studies vendor managed inventory problems (VMI), which are an example of effective cooperation and partnering practices between up and downstream stages in a supply chain. In VMI, the supplier takes the responsibility for replenishing his customers’ inventories based on their consumption data, with the aim of optimizing the overall distribution and inventory costs throughout the supply chain, known as the inventory routing problem. Birger Raa performed different studies on the cyclic inventory routing problem with single and multiple vehicles where customer demand rates are deterministic and constant. The developed solution procedures combine fleet sizing, vehicle routing and inventory management.
    Combinatorial auctions
    : Combinatorial auctions are auctions where bidders are allowed to express package bids, i.e. bids on subsets of the assets that are for sale. Dries Goossens examines combinatorial auctions where constraints influence the allocation. These constraints are motivated by practical considerations; they could be bidder specific, but could just as well concern a group of bidders. Dries Goossens investigates the effect of allocation constraints on bidder behavior: indeed, allocation constraints may result in a lower bid winning over a higher bid, and in general can make the allocation process less transparent. With respect to applications, the focus is on the supply chain: procurement, transportation, pricing, and supply chain formation. For instance, in procurement, a common allocation constraint is to limit the number of suppliers and/or to impose bounds on the procurement dependency of one single supplier. He also aims to further popularize the combinatorial auction for non-professional bidders, and fully exploit its potential in practice. Auction designs that offer flexibility in the allocation constraints used by the auctioneer and the bidders should result in a much broader applicability of combinatorial auctions.

    (OM/OR members: Tarik Aouam, Veronique Limère, Ann Vereecke, Dries Goossens)

    1. Sport Management

      Dries Goossens performs research on sport management and in particular on sport scheduling where a timetable is constructed that states who will play whom, when, and where satisfying the objectives of the sport competition, the public attendance, commercial interests, and even the health of the players. Dries his main goal is to construct models for problems in sport scheduling, to develop efficient methods for solving these models, and to evaluate their performance. More in particular, Dries focuses on two different types of sport scheduling problems that we intend to focus on: competitions where successions of home matches (away matches) is not the primary concern, and amateur competitions (where teams have to share their home ground with other sports). Another research goal is the study of sport scheduling under uncertainty, ranging from robust scheduling with pro-active and re-active approaches, to dynamic sport scheduling, where the sport schedule is finalized sequentially, as more information becomes available. His research is not limited to academic research as he implemented his algorithm for scheduling the first division of the Belgian football competition and others.

      (OM/OR members: Dries Goossens)


    • Mario Vanhoucke
      The research interest of Mario Vanhoucke lies in the integration of project scheduling, risk management and project control using “combinatorial optimization models”. He has written +60 papers and 5 books on this topic, and is a regular speaker at conferences for academics and professionals. He also has an interest in integrating project resource scheduling with personnel scheduling.
    • Broos Maenhout
      The research of Broos Maenhout focuses on the management of personnel resources. In this perspective, he develops new analytical methods that support the planning and scheduling of personnel and new insights are acquired in personnel management. His current research focuses on the integration of personnel planning with other domains in operations management such as project management.
    • Ann Vereecke
      Her main interests are Supply Chain Management and manufacturing strategy, in particular international manufacturing strategy.
    • Dries Goossens
      The research interests of Dries Goossens are divided over several areas, each of which on the crossroad between operations research (OR) and operations management (OM): combinatorial auctions (with applications in procurement and transportation), sports scheduling (including scheduling the first division of the Belgian football competition), and personnel planning.
    • Tarik Aouam
      The research of Tarik Aouam is focused on three main directions as follows, (i) Production planning under uncertainty with load-dependent lead-times in manufacturing systems, (ii) Integrating the production (manufacturing) function with other functions, including: Sales (acceptance of orders with risk inherent in orders), Distribution (Inventory and routing), Network Design (Facility location), Procurement (with the existence of spot markets and financial contracts for hedging), Finance (cash management with risk in customer payments), (iii) Risk management and delegation in Procurement.
    • Veronique Limère
      Veronique Limère’s research interests lie in facility logistics, material handling, operations research applications in production and logistics systems, and industrial engineering applications in health care. IWT project funding was obtained in the past, and projects were carried out in collaboration with some major Belgian manufacturing firms.