Journal papers by Renzo Akkerman
Bryndis Stefansdottir, , Martin Grunow , Renzo Akkerman (2017). Classifying and modeling setups a... more Bryndis Stefansdottir, , Martin Grunow , Renzo Akkerman (2017). Classifying and modeling setups and cleanings in lot sizing and scheduling. European Journal of Operational Research.
Marlies de Keizer, Renzo Akkerman, Martin Grunow, Jacqueline M. Bloemhof, Rene Haijema, Jack G.A.... more Marlies de Keizer, Renzo Akkerman, Martin Grunow, Jacqueline M. Bloemhof, Rene Haijema, Jack G.A.J. van der Vorst (2017). Logistics network design for perishable products with heterogeneous quality decay. European Journal of Operational Research
High demand uncertainties, long production lead times, and short product life cycles cause high r... more High demand uncertainties, long production lead times, and short product life cycles cause high risks for supply chain planning in the semiconductor industry. These affect all industries producing goods containing semiconductors. We present a robust supply chain planning framework for revenue management that consists of stable and flexible solutions for demand steering and dynamic pricing, extending current industry practice in several aspects. We introduce the concept of availabilities and capabilities, as well as various planning processes and process enablers. Based on our framework, we also highlight directions for future research.
An increasing share of the daily meals served in Europe are prepared out-of-home by professionals... more An increasing share of the daily meals served in Europe are prepared out-of-home by professionals in foodservice. The quality of such meals is highly debated. This paper presents and discusses obstacles to improving quality in a cost-effective way and suggests solutions: 1) Modularisation of the meal production in order to transfer labour-intensive operations from the kitchens to the industry; 2) Systemic use of a new concept: thawing during distribution, which improves shelf-life and reduces waste; 3) Supply chain modelling to improve delivery schedules and reduce environmental impact. Existing food legislation complies with the suggested approaches.
Trends in Food Science & Technology, 2013
An increasing share of the daily meals served in Europe is prepared out-of-home by professionals ... more An increasing share of the daily meals served in Europe is prepared out-of-home by professionals in foodservice. The quality of such meals is highly debated. This paper presents and discusses obstacles to improving quality in a cost-effective way and suggests solutions: 1) Modularisation of the meal production in order to transfer labour-intensive operations from the kitchens to the industry; 2) Systemic use of a new concept: thawing during distribution, which improves shelf-life and reduces waste; 3) Supply chain modelling to improve delivery schedules and reduce environmental impact. Existing food legislation complies with the suggested approaches.
Health Care Management Science, Jan 1, 2004
Waiting times for cardiac surgery is a significant problem in the medical world. The fact that pa... more Waiting times for cardiac surgery is a significant problem in the medical world. The fact that patients' length of stay varies considerably makes effective hospital operation a difficult job. This paper analyzes patients' length of stay in hospital wards following cardiac surgery. Three scenarios for hospital management are presented and evaluated using Markov chain theory and simulation experiments. The aim of our analyses is to examine unused bed capacity in hospital wards. This makes it possible to attain a more efficient allocation of hospital beds. The results presented in this paper provide useful insight into relationships between patients' length of stay, bed availability, and hospital waiting lists.
International Journal of Production Economics, Jan 1, 2007
In the food-processing industry, usually a limited number of storage tanks for intermediate stora... more In the food-processing industry, usually a limited number of storage tanks for intermediate storage is available, which are used for different products. The market sometimes requires extremely short lead times for some products, leading to prioritization of these products, partly through the dedication of a storage tank. This type of situation has hardly been investigated, although planners struggle with it in practice. This paper aims at investigating the fundamental effect of prioritization and dedicated storage in a two-stage production system, for various product mixes. We show the performance improvements for the prioritized product, as well as the negative effects for the other products. We also show how the effect decreases with more storage tanks, and increases with more products.
International Journal of …, Jan 1, 2007
In food processing, two-stage production systems with a batch processor in the first stage and pa... more In food processing, two-stage production systems with a batch processor in the first stage and packaging lines in the second stage are common and mostly separated by capacity- and time-constrained intermediate storage. This combination of constraints is common in practice, but the literature hardly pays any attention to this. In this paper, we show how various capacity and time constraints influence the performance of a specific two-stage system. We study the effects of several basic scheduling and sequencing rules in the presence of these constraints in order to learn the characteristics of systems like this. Contrary to the common sense in operations management, the LPT rule is able to maximize the total production volume per day. Furthermore, we show that adding one tank has considerable effects. Finally, we conclude that the optimal setup frequency for batches in the first stage is dictated by the storage time constraint.
Journal of Cleaner Production, Jan 1, 2008
In food-processing industries, reduction of product losses is important for improving profitabili... more In food-processing industries, reduction of product losses is important for improving profitability and sustainability. This paper presents a decision support tool for analyzing the effects of planning decisions on the amount of product losses in the food-processing industry. We created a research framework to collect and analyze data, supporting the development of an Excel-based decision support tool that helps to evaluate different scenarios for the planning decisions and production parameters. The tool was developed in co-operation with and implemented in a real-life dairy plant, where the tool was able to reduce the planning-related losses by nearly 20%. But an equally important result is the insight gained on the interactions between processing, packaging, and intermediate storage. The framework and tool can easily be implemented in other situations.
British Food Journal, Jan 1, 2008
Purpose – The purpose of the paper is to investigate the limitations and barriers for supply chai... more Purpose – The purpose of the paper is to investigate the limitations and barriers for supply chain integration that food manufacturers experience and to highlight their planning and scheduling problems. Possible ways to cope with these are offered.
Design/methodology/approach – The paper is theoretical/conceptual in nature: the findings are illustrated in an explorative case study.
Findings – It is often suggested that food supply chains are typical for what can be achieved in supply chain management. This paper challenges this belief by investigating the possibilities and limitations for supply chain integration for food manufacturers. The authors argue that a combination of typical food characteristics and the use of shared resources limit the possibility for integration, while uncertainties and complex business conditions increase the need for integration. In a case study, the paper explores alternatives to cope with that situation.
Research limitations/implications – The paper is based on previous empirical work, which is applied and further developed in a case-study setting of a consumer product food manufacturer. The authors argue that the case has several generic characteristics, but further research is needed to test the main ideas in a wider context.
Practical implications – Production managers and planners in food manufacturing are often aware of the described situation, but general managers, marketing managers, and supply chain managers can learn that there are limits to aligning operations to customers. The paper offers a number of solutions that might assist production managers in better understanding their situation and thinking about improvements.
Originality/value – The paper introduces buyer focus, shared resources and the limitations of supply chain integration into the field of food supply chains.
International Journal of Production Economics, Jan 1, 2009
In food processing, market demands are increasingly important, resulting in regular introductions... more In food processing, market demands are increasingly important, resulting in regular introductions of new products, or special offers. Often, such an introduction or promotional effort affects demand of other products or packaging types. Here we study the effect of such correlated demand. More specifically, the aim of this paper is to study the effect of product mix variability and correlated demand in a two-stage food production system. Results from a simulation study show that increasing correlation on the product level results in an increase in average lead times. A slightly smaller effect is seen for correlation on the package level. Similar results are found for average waste. Increased variability amplifies these effects.
Cognition, Technology & Work, Jan 1, 2009
Production scheduling has been widely studied in several research areas, resulting in a large num... more Production scheduling has been widely studied in several research areas, resulting in a large number of methods, prescriptions, and approaches. However, the impact on scheduling practice seems relatively low. This is also the case in the food-processing industry, where industry-specific characteristics induce specific and complex scheduling problems. Based on ideas about decomposition of the scheduling task and the production process, we develop an analysis methodology for scheduling problems in food processing. This combines an analysis of structural (technological) elements of the production process with an analysis of the tasks of the scheduler. This helps to understand, describe, and structure scheduling problems in food processing, and forms a basis for improving scheduling and applying methods developed in literature. It also helps in evaluating the organisational structures and information flows related to scheduling.
International Journal of …, Jan 1, 2010
Changing customer requirements, unpredictable disturbances combined with expensive production fac... more Changing customer requirements, unpredictable disturbances combined with expensive production facilities, are major problems for food processing companies to achieve synergy between the economic and environmental performance. There is notably a lack of tools to support decisions to explore effects on performance related to new product introductions, changes in production equipment, changes in planning concepts and their cross sections. We argue that interdisciplinary research that uses operations research techniques, operations management insights, food process technology and product design helps in exploring the effect of uncertainty in demand and production. As a result, process design can be more robust: both economic and environmental. This position paper explores the problem and the main elements of the proposed scenario-based simulation approach.
International Journal of …, Jan 1, 2010
In contrast to discrete manufacturers, food-processing companies can sometimes produce the same e... more In contrast to discrete manufacturers, food-processing companies can sometimes produce the same end products in different ways: either mix first and then process, or process first and mix later. Moreover, a final product can be mixed from different raw materials or intermediates. That adds a new dimension to postponement and decoupling point theory as choices need to be made not only with regard to where to locate inventory, but also which products to store. That aspect has not been covered so far. This paper explores this problem for a typical two-stage food production situation in a flour mill. The number and composition of intermediate products in the decoupling point is determined using a stepwise solution approach supported by mathematical programming models. The procedure facilitates decision-making for the management of the mill regarding how many and what intermediates to store. Extensions of the models presented might be helpful to solve related problems such as determining the number of intermediate storage tanks required.
OR spectrum, Jan 1, 2010
The management of food distribution networks is receiving more and more attention, both in practi... more The management of food distribution networks is receiving more and more attention, both in practice and in the scientific literature. In this paper, we review quantitative operations management approaches to food distribution management, and relate this to challenges faced by the industry. Here, our main focus is on three aspects: food quality, food safety, and sustainability. We discuss the literature on three decision levels: strategic network design, tactical network planning, and operational transportation planning. For each of these, we survey the research contributions, discuss the state of the art, and identify challenges for future research.
International Journal of Production …, Jan 1, 2009
One of the most challenging tasks in today's food industry is controlling the product quality thr... more One of the most challenging tasks in today's food industry is controlling the product quality throughout the food supply chain. In this paper, we integrate food quality in decision-making on production and distribution in a food supply chain. We provide a methodology to model food quality degradation in such a way that it can be integrated in a mixed-integer linear programming model used for production and distribution planning. The resulting model is applied in an illustrative case study, and can be used to design and operate food distribution systems, using both food quality and cost criteria.
The primary aim of food traceability is to increase food safety, but traceability systems can als... more The primary aim of food traceability is to increase food safety, but traceability systems can also bring other benefits to production systems and supply chains. In the literature these benefits are extensively discussed, but studies that quantify them are scarce. In this paper we propose two hypothetical improvements of the traceability system within the chocolate production system and supply chain and we illustrate the resulting benefits by using a case study. Based on the case study, we quantify the influence of these improvements on production efficiency and recall size in case of a safety crisis by developing a simulation tool. These results are aimed to illustrate and quantify the additional benefits of traceability information, and could help food industries in deciding whether and how to improve their traceability systems.
This study addresses a capacitated intermediate product selection and blending problem typical fo... more This study addresses a capacitated intermediate product selection and blending problem typical for two-stage production systems in the food processing industry. The problem involves the selection of a set of intermediates and end product recipes characterizing how those selected intermediates are blended into end products to minimise the total operational costs under production and storage capacity limitations. A comprehensive mixed integer linear model is developed for the problem. The model is applied on a data set collected from a real-life case. The trade-off s between capacity limitations and operational costs are analysed, and the eff ects of di erent types of cost parameters and capacity limitations on the selection of intermediates and end product recipes are investigated.
Due to recent developments in traceability systems, it is now possible to exchange significant am... more Due to recent developments in traceability systems, it is now possible to exchange significant amounts of data through food supply chains. Farming practices applied by cocoa farmers at the beginning of the chocolate supply chain strongly influence several quality parameters of the finished chocolate. However, information regarding these practices does not normally reach the chocolate manufacturer. As a consequence, many specifications of the raw material cannot be taken into consideration in the operational decision making processes related to chocolate production. In recent years many studies have been investigating the influence of certain farming practices on cocoa beans and the subsequent chocolate quality parameters. However, no comprehensive analysis of the process variables in the chain and their effects on the quality can be found. In this paper we review and classify the available literature on the topic in terms of process variables throughout the chain, and their effects on quality and flavour aspects of cocoa beans and the eventual chocolate product. After analysing the literature, we are able to identify potential benefits of using data regarding the farming practices into the chocolate production process. These potential benefits especially concern product quality and production yield, giving directions for the future of chocolate production.
Purpose – Stock keeping unit (SKU) classifications are widely used in the field of production and... more Purpose – Stock keeping unit (SKU) classifications are widely used in the field of production and operations management. Although many theoretical and practical examples of classifications exist, there are no overviews of the current literature, and general guidelines are lacking with respect to method selection for classifying SKUs. The purpose of this paper is to systematically synthesise the earlier work in this area, and to conceptualise and discuss the factors that influence the choice of a specific SKU classification.
Design/methodology/approach – The paper structurally reviews existing contributions and synthesises these into a conceptual framework for SKU classification.
Findings – How SKUs are classified depends on the classification aim, the context and the method that is chosen. In total, three main production and operations management aims were found: inventory management, forecasting and production strategy. Within the method three decisions are identified to come to a classification: the characteristics, the classification technique and the operationalisation of the classes.
Research limitations/implications – Drawing on the literature survey, the authors conclude with a conceptual framework describing the factors that influence SKU classification. Further research could use this framework to develop guidelines for real-life applications.
Practical implications – Examples from a variety of industries and general directions are provided which managers could use to develop their own SKU classification.
Originality/value – The paper aims to advance the literature on SKU classification from the level of individual examples to a conceptual level and provides directions on how to develop a SKU classification.
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Journal papers by Renzo Akkerman
Design/methodology/approach – The paper is theoretical/conceptual in nature: the findings are illustrated in an explorative case study.
Findings – It is often suggested that food supply chains are typical for what can be achieved in supply chain management. This paper challenges this belief by investigating the possibilities and limitations for supply chain integration for food manufacturers. The authors argue that a combination of typical food characteristics and the use of shared resources limit the possibility for integration, while uncertainties and complex business conditions increase the need for integration. In a case study, the paper explores alternatives to cope with that situation.
Research limitations/implications – The paper is based on previous empirical work, which is applied and further developed in a case-study setting of a consumer product food manufacturer. The authors argue that the case has several generic characteristics, but further research is needed to test the main ideas in a wider context.
Practical implications – Production managers and planners in food manufacturing are often aware of the described situation, but general managers, marketing managers, and supply chain managers can learn that there are limits to aligning operations to customers. The paper offers a number of solutions that might assist production managers in better understanding their situation and thinking about improvements.
Originality/value – The paper introduces buyer focus, shared resources and the limitations of supply chain integration into the field of food supply chains.
Design/methodology/approach – The paper structurally reviews existing contributions and synthesises these into a conceptual framework for SKU classification.
Findings – How SKUs are classified depends on the classification aim, the context and the method that is chosen. In total, three main production and operations management aims were found: inventory management, forecasting and production strategy. Within the method three decisions are identified to come to a classification: the characteristics, the classification technique and the operationalisation of the classes.
Research limitations/implications – Drawing on the literature survey, the authors conclude with a conceptual framework describing the factors that influence SKU classification. Further research could use this framework to develop guidelines for real-life applications.
Practical implications – Examples from a variety of industries and general directions are provided which managers could use to develop their own SKU classification.
Originality/value – The paper aims to advance the literature on SKU classification from the level of individual examples to a conceptual level and provides directions on how to develop a SKU classification.
Design/methodology/approach – The paper is theoretical/conceptual in nature: the findings are illustrated in an explorative case study.
Findings – It is often suggested that food supply chains are typical for what can be achieved in supply chain management. This paper challenges this belief by investigating the possibilities and limitations for supply chain integration for food manufacturers. The authors argue that a combination of typical food characteristics and the use of shared resources limit the possibility for integration, while uncertainties and complex business conditions increase the need for integration. In a case study, the paper explores alternatives to cope with that situation.
Research limitations/implications – The paper is based on previous empirical work, which is applied and further developed in a case-study setting of a consumer product food manufacturer. The authors argue that the case has several generic characteristics, but further research is needed to test the main ideas in a wider context.
Practical implications – Production managers and planners in food manufacturing are often aware of the described situation, but general managers, marketing managers, and supply chain managers can learn that there are limits to aligning operations to customers. The paper offers a number of solutions that might assist production managers in better understanding their situation and thinking about improvements.
Originality/value – The paper introduces buyer focus, shared resources and the limitations of supply chain integration into the field of food supply chains.
Design/methodology/approach – The paper structurally reviews existing contributions and synthesises these into a conceptual framework for SKU classification.
Findings – How SKUs are classified depends on the classification aim, the context and the method that is chosen. In total, three main production and operations management aims were found: inventory management, forecasting and production strategy. Within the method three decisions are identified to come to a classification: the characteristics, the classification technique and the operationalisation of the classes.
Research limitations/implications – Drawing on the literature survey, the authors conclude with a conceptual framework describing the factors that influence SKU classification. Further research could use this framework to develop guidelines for real-life applications.
Practical implications – Examples from a variety of industries and general directions are provided which managers could use to develop their own SKU classification.
Originality/value – The paper aims to advance the literature on SKU classification from the level of individual examples to a conceptual level and provides directions on how to develop a SKU classification.
In this thesis, several aspects of these developments are studied from an Operations Management perspective. Specific questions that are addressed are:
- What are the implications of capacity- and time-constrained intermediate storage on production performance?
- What are the performance implications of demand characteristics like high product mix variability and lead time reductions?
- How do planning decisions and process configurations influence the realization of product losses
The results provide insight in the operational performance of two-stage food production systems with intermediate storage. This performance not only entails competitiveness (through the insights on lead time performance), but also sustainability (through the insight in realization of product losses).