Rommert Dekker | Erasmus University Rotterdam (original) (raw)

Papers by Rommert Dekker

IISE transactions, Jan 26, 2018

Report / Econometric Institute, Erasmus University Rotterdam, Mar 31, 2010

Ports provide a number of logistical choices concerning storage, onward transport, and postponeme... more Ports provide a number of logistical choices concerning storage, onward transport, and postponement. We investigate the routing flexibility offered by ports with a central location with respect to the hinterland. This flexibility is investigated using an illustrative case in which a number of alternative strategies are evaluated by means of simulation. Detailed cost data was used for the illustrative case. The combination of a simulation model and detailed cost data allows us to quantify the value of the rerouting flexibility. A combination of using regional distribution centers and a European Distribution Center results in the lowest cost per container.

Transportation Research Part E: Logistics and Transportation Review, 2018

We propose an analytical modeling methodology for quantifying the impact of slow steaming on the ... more We propose an analytical modeling methodology for quantifying the impact of slow steaming on the carrier's voyage cost and on the shipper's total landed logistics costs. The developed methodology can be employed by a carrier and a shipper in their contract negotiations, in order for the two parties to determine how they could divide between them the savings resulted from slow steaming. We demonstrate that the impact of slow steaming and speed adjustment policies on the shippers' total landed logistics costs tend to increase as the vessel travels towards the end of its voyage.

Transportation Science, 2019

Transport companies often have a published timetable. To maintain timetable reliability despite d... more Transport companies often have a published timetable. To maintain timetable reliability despite delays, companies include buffer times during timetable development and adjust the traveling speed during timetable execution. We develop an approach that integrates timetable development and execution. We model execution of the timetable as a stochastic dynamic program (SDP). An SDP is a natural framework to model random events causing (additional) delay, propagation of delays, and real-time optimal speed adjustments. However, SDPs alone cannot incorporate the buffer allocation during timetable development, as buffer allocation requires choosing the same action in different states of the SDP. Motivated by the practical need for timetables that operate well during timetable execution, our model seeks the buffer allocation that yields the SDP that has minimal long-run average costs. We derive several analytical insights into the model. We prove that costs are joint convex in the buffer tim...

SSRN Electronic Journal, 2016

We consider a long-term capacity investment problem in a competitive market under demand uncertai... more We consider a long-term capacity investment problem in a competitive market under demand uncertainty. Two firms move sequentially in the competition and a firm's capacity decision interacts with the other firm's current and future capacity. Throughout the investment race, a firm can either choose to plan its investments proactively, taking into account possible responses from the other firm, or decide to respond reactively to the competition. In both cases, the optimal decision at each period is determined according to an ISD (Invest, Stayput, Disinvest) policy. We develop two algorithms to efficiently derive proactive ISD policies for the leader and follower firms. Using data from the container shipping market (2000-2015), we show that the optimal capacity determined by our competitive strategy is consistent with the realized investments in practice. By revealing strategical flexibility of proactive strategies, our results demonstrate that firms in the competition can gain more capacity and profit through such a strategy. Using Monte Carlo simulations, we explore the impact of different market conditions and investment irreversibility levels on capacity strategies. In particular, by comparing the results of competitive strategies and strategies that separate firms into different markets, we show that both firms can benefit from the competition and that market downturns likely lead to investment cascades.

Operations Research Proceedings, 1994

Journal of Engineering and Technological Sciences, 2016

A block replacement schedule can be optimized simultaneously with a spare parts ordering schedule... more A block replacement schedule can be optimized simultaneously with a spare parts ordering schedule, since all items are replaced at a constant interval. The solution of joint optimization for spare parts ordering time and block replacement gives lower costs compared to separate optimization of ordering time and replacement time. The spare parts for replacement can be classified as stochastic demand for failure replacement and deterministic demand for block replacement. In this paper, we propose a simulation model for a separate spare parts ordering schedule. The solution was compared to the solution for a model with common spare parts for both failure and block replacement. The system has N identical components, each with a Weibull lifetime distribution. The costs of failure and block replacements, and also the costs of ordering, holding and shortage of spare parts are given. The proposed model was shown to perform better than the common order model. Also, compared to the age replacement model, the solution of the proposed model is relatively similar, yet the economies of scale would be an advantage for the block replacement over age replacement.

Reliability Engineering & System Safety, 2021

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

European Journal of Operational Research, 2018

Timing is of crucial importance for successful vaccination. To avoid a large outbreak, vaccines a... more Timing is of crucial importance for successful vaccination. To avoid a large outbreak, vaccines are administered preferably as quickly as possible. However, in the early stages of an outbreak the information on the disease is limited and waiting with the intervention allows to design a more tailored vaccination strategy. In this paper we study the resulting tradeoff between timing of vaccination and the effectiveness of the response. We model disease progression using the seminal SIR model, and consider a decision maker who allocates her budget over two vaccine types: an early aspecific vaccine and a later specific vaccine. We analytically characterize the switching curve separating the parameter space region where the late specific vaccine is preferred from the region where the early aspecific type is preferred. More importantly, we show that the decision maker should not only consider pure strategies, i.e., strategies which spend the entire budget on one of the types. Instead, she should suitably invest in both vaccine types to benefit both from the early response and from the good vaccine. We prove that at the switching curve, such a hybrid strategy is strictly better than either of the pure strategies due to the non-linear dynamics of epidemics. Numerical experiments show that the associated benefit of hybrid strategies over pure strategies in terms of reduction of the number of infections may be more than 50%. Such experiments also substantiate our restriction to two vaccine types.

European Journal of Operational Research, 2017

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

European Journal of Operational Research, 2018

Vaccination is one of the most effective ways to prevent the outbreak of an infectious disease. T... more Vaccination is one of the most effective ways to prevent the outbreak of an infectious disease. This medical intervention also brings about many logistical questions. In recent years, in the Operations Research/Operations Management community there is growing interest in the logistical aspects of vaccination. However, publications on this topic are somewhat scattered: most papers focus on particular logistical aspects only and a broad overview is missing. This potentially leads to contributions being overlooked and makes it difficult to identify open research questions. In this literature review we use a supply chain perspective and propose a classification for the literature on vaccine logistics in order to structure this relatively new field and highlight promising research directions. Thereto we distinguish between the following four components: (1) composition, (2) production, (3) allocation and (4) distribution. We use this classification to derive the unique characteristics of the vaccine supply chain. We find that the vaccine supply chain can amongst others be characterized by high uncertainty in both supply and demand; asymmetry between supplier, public health organization and end customer; complex political decisions concerning allocation and the crucial importance of deciding and acting in time. Our review yields a framework for Operations Research/Operations Management research in vaccine logistics. Based on this framework we discuss for each component in the vaccine supply chain the related decision problems, the current status and future research possibilities.

This paper gives an overview of scientific literature that describes and discusses cases of rever... more This paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addition we compare practice with theoretical models and point out research opportunities in the field

Omega, 2000

Recovery of used products is receiving much attention recently due to growing environmental conce... more Recovery of used products is receiving much attention recently due to growing environmental concern. Ecient implementation requires appropriate logistics structures to be set up for the arising goods¯ow from users to producers. We investigate the design of such logistics networks. As a basis for our analysis we review recent case studies on logistics network design for product recovery in dierent industries. We identify general characteristics of product recovery networks and compare them with traditional logistics structures. Moreover, we derive a classi®cation scheme for dierent types of recovery networks.

Naval Research Logistics, 2002

In this paper an inventory model with several demand classes, prioritised according to importance... more In this paper an inventory model with several demand classes, prioritised according to importance, is analysed. We consider a lot-for-lot or S , 1; S i n v entory model with lost sales. For each demand class there is a critical stock level at and below which demand from that class is not satis ed from stock on hand. In this way stock is retained to meet demand from higher priority demand classes. A set of such critical levels determines the stocking policy. F or Poisson demand and a generally distributed lead time we derive expressions for the service levels for each demand class and the average total cost per unit time. E cient solution methods for obtaining optimal policies, with and without service level constraints, are presented. Numerical experiments in which the solution methods are tested demonstrate that signi cant cost reductions can be achieved by distinguishing between demand classes.

International Journal of Production Economics, 1996

In this paper we consider a single-product, single-echelon production and inventory system with p... more In this paper we consider a single-product, single-echelon production and inventory system with product returns, product remanufacturing, and product disposal. For this system we consider three different procurement and inventory control strategies, i.e., the (sp,Qp,sd,N) strategy, the (sp,Qp,sd) strategy, and the (sp, Q,,AJ) strategy. The control parameters in these strategies relate to the inventory position at which an outside procurement order is placed (sp), the inventory position at which returned products are disposed of (sd), the outside procurement order quantity (Q,), and the capacity of the remanufacturing facility (N). For each of the strategies we derive exact expressions of the total expected costs as functions of the control parameters. Main objective of this paper is to compare the performance of each of the alternative strategies with respect to costs, under different system conditions.

International Journal of Production Economics, 1996

In this paper we analyse an (s, Q) inventory model in which used products can be remanufactured t... more In this paper we analyse an (s, Q) inventory model in which used products can be remanufactured to new ones. Wc develop two approximations for the average costs and compare their performance with that of an approximation suggested by Muckstadt and Isaac. Next we extend the model with the option to dispose returned products and present a heuristic optimisation procedure which is checked with full enumeration.

Lecture Notes in Economics and Mathematical Systems, 2005

Products, components, materials and other equipment stream forward and back wards and back in the... more Products, components, materials and other equipment stream forward and back wards and back in their supply chains. Reverse Logistics deals with the processes associated with the reverse stream from users/owners to re-users. This paper provides a review and content analysis of scientific literature on reverse logistics case studies. Over sixty case studies are included. In addition, we give an overview of particular issues, which we link with propositions, unanswered questions and thus directions for future research.

This paper gives an overview of scientific literature that describes and discusses cases of rever... more This paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addition we compare practice with theoretical models and point out research opportunities in the field.

In this report we discuss a model that can be used to determine stocking levels using the data th... more In this report we discuss a model that can be used to determine stocking levels using the data that comes forward from a Shell RCM analysis and the data available in E-SPIR. The model is appropriate to determine stock quantities for parts that are used in redundancy situations, and for parts that are used in different pieces of equipment with different downtime costs. Estimating the annual production loss using the model consists of a number of steps. First, we need to determine which spares are used for the repairs of which failure modes. In the second step, we estimate the average waiting time for spares as a function of the number of spares stocked. In the third step, the annual downtime costs are determined. We combine the downtime costs with the holding costs to determine the optimal number of parts to stock.

IISE transactions, Jan 26, 2018

Report / Econometric Institute, Erasmus University Rotterdam, Mar 31, 2010

Ports provide a number of logistical choices concerning storage, onward transport, and postponeme... more Ports provide a number of logistical choices concerning storage, onward transport, and postponement. We investigate the routing flexibility offered by ports with a central location with respect to the hinterland. This flexibility is investigated using an illustrative case in which a number of alternative strategies are evaluated by means of simulation. Detailed cost data was used for the illustrative case. The combination of a simulation model and detailed cost data allows us to quantify the value of the rerouting flexibility. A combination of using regional distribution centers and a European Distribution Center results in the lowest cost per container.

Transportation Research Part E: Logistics and Transportation Review, 2018

We propose an analytical modeling methodology for quantifying the impact of slow steaming on the ... more We propose an analytical modeling methodology for quantifying the impact of slow steaming on the carrier's voyage cost and on the shipper's total landed logistics costs. The developed methodology can be employed by a carrier and a shipper in their contract negotiations, in order for the two parties to determine how they could divide between them the savings resulted from slow steaming. We demonstrate that the impact of slow steaming and speed adjustment policies on the shippers' total landed logistics costs tend to increase as the vessel travels towards the end of its voyage.

Transportation Science, 2019

Transport companies often have a published timetable. To maintain timetable reliability despite d... more Transport companies often have a published timetable. To maintain timetable reliability despite delays, companies include buffer times during timetable development and adjust the traveling speed during timetable execution. We develop an approach that integrates timetable development and execution. We model execution of the timetable as a stochastic dynamic program (SDP). An SDP is a natural framework to model random events causing (additional) delay, propagation of delays, and real-time optimal speed adjustments. However, SDPs alone cannot incorporate the buffer allocation during timetable development, as buffer allocation requires choosing the same action in different states of the SDP. Motivated by the practical need for timetables that operate well during timetable execution, our model seeks the buffer allocation that yields the SDP that has minimal long-run average costs. We derive several analytical insights into the model. We prove that costs are joint convex in the buffer tim...

SSRN Electronic Journal, 2016

We consider a long-term capacity investment problem in a competitive market under demand uncertai... more We consider a long-term capacity investment problem in a competitive market under demand uncertainty. Two firms move sequentially in the competition and a firm's capacity decision interacts with the other firm's current and future capacity. Throughout the investment race, a firm can either choose to plan its investments proactively, taking into account possible responses from the other firm, or decide to respond reactively to the competition. In both cases, the optimal decision at each period is determined according to an ISD (Invest, Stayput, Disinvest) policy. We develop two algorithms to efficiently derive proactive ISD policies for the leader and follower firms. Using data from the container shipping market (2000-2015), we show that the optimal capacity determined by our competitive strategy is consistent with the realized investments in practice. By revealing strategical flexibility of proactive strategies, our results demonstrate that firms in the competition can gain more capacity and profit through such a strategy. Using Monte Carlo simulations, we explore the impact of different market conditions and investment irreversibility levels on capacity strategies. In particular, by comparing the results of competitive strategies and strategies that separate firms into different markets, we show that both firms can benefit from the competition and that market downturns likely lead to investment cascades.

Operations Research Proceedings, 1994

Journal of Engineering and Technological Sciences, 2016

A block replacement schedule can be optimized simultaneously with a spare parts ordering schedule... more A block replacement schedule can be optimized simultaneously with a spare parts ordering schedule, since all items are replaced at a constant interval. The solution of joint optimization for spare parts ordering time and block replacement gives lower costs compared to separate optimization of ordering time and replacement time. The spare parts for replacement can be classified as stochastic demand for failure replacement and deterministic demand for block replacement. In this paper, we propose a simulation model for a separate spare parts ordering schedule. The solution was compared to the solution for a model with common spare parts for both failure and block replacement. The system has N identical components, each with a Weibull lifetime distribution. The costs of failure and block replacements, and also the costs of ordering, holding and shortage of spare parts are given. The proposed model was shown to perform better than the common order model. Also, compared to the age replacement model, the solution of the proposed model is relatively similar, yet the economies of scale would be an advantage for the block replacement over age replacement.

Reliability Engineering & System Safety, 2021

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

European Journal of Operational Research, 2018

Timing is of crucial importance for successful vaccination. To avoid a large outbreak, vaccines a... more Timing is of crucial importance for successful vaccination. To avoid a large outbreak, vaccines are administered preferably as quickly as possible. However, in the early stages of an outbreak the information on the disease is limited and waiting with the intervention allows to design a more tailored vaccination strategy. In this paper we study the resulting tradeoff between timing of vaccination and the effectiveness of the response. We model disease progression using the seminal SIR model, and consider a decision maker who allocates her budget over two vaccine types: an early aspecific vaccine and a later specific vaccine. We analytically characterize the switching curve separating the parameter space region where the late specific vaccine is preferred from the region where the early aspecific type is preferred. More importantly, we show that the decision maker should not only consider pure strategies, i.e., strategies which spend the entire budget on one of the types. Instead, she should suitably invest in both vaccine types to benefit both from the early response and from the good vaccine. We prove that at the switching curve, such a hybrid strategy is strictly better than either of the pure strategies due to the non-linear dynamics of epidemics. Numerical experiments show that the associated benefit of hybrid strategies over pure strategies in terms of reduction of the number of infections may be more than 50%. Such experiments also substantiate our restriction to two vaccine types.

European Journal of Operational Research, 2017

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

European Journal of Operational Research, 2018

Vaccination is one of the most effective ways to prevent the outbreak of an infectious disease. T... more Vaccination is one of the most effective ways to prevent the outbreak of an infectious disease. This medical intervention also brings about many logistical questions. In recent years, in the Operations Research/Operations Management community there is growing interest in the logistical aspects of vaccination. However, publications on this topic are somewhat scattered: most papers focus on particular logistical aspects only and a broad overview is missing. This potentially leads to contributions being overlooked and makes it difficult to identify open research questions. In this literature review we use a supply chain perspective and propose a classification for the literature on vaccine logistics in order to structure this relatively new field and highlight promising research directions. Thereto we distinguish between the following four components: (1) composition, (2) production, (3) allocation and (4) distribution. We use this classification to derive the unique characteristics of the vaccine supply chain. We find that the vaccine supply chain can amongst others be characterized by high uncertainty in both supply and demand; asymmetry between supplier, public health organization and end customer; complex political decisions concerning allocation and the crucial importance of deciding and acting in time. Our review yields a framework for Operations Research/Operations Management research in vaccine logistics. Based on this framework we discuss for each component in the vaccine supply chain the related decision problems, the current status and future research possibilities.

This paper gives an overview of scientific literature that describes and discusses cases of rever... more This paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addition we compare practice with theoretical models and point out research opportunities in the field

Omega, 2000

Recovery of used products is receiving much attention recently due to growing environmental conce... more Recovery of used products is receiving much attention recently due to growing environmental concern. Ecient implementation requires appropriate logistics structures to be set up for the arising goods¯ow from users to producers. We investigate the design of such logistics networks. As a basis for our analysis we review recent case studies on logistics network design for product recovery in dierent industries. We identify general characteristics of product recovery networks and compare them with traditional logistics structures. Moreover, we derive a classi®cation scheme for dierent types of recovery networks.

Naval Research Logistics, 2002

In this paper an inventory model with several demand classes, prioritised according to importance... more In this paper an inventory model with several demand classes, prioritised according to importance, is analysed. We consider a lot-for-lot or S , 1; S i n v entory model with lost sales. For each demand class there is a critical stock level at and below which demand from that class is not satis ed from stock on hand. In this way stock is retained to meet demand from higher priority demand classes. A set of such critical levels determines the stocking policy. F or Poisson demand and a generally distributed lead time we derive expressions for the service levels for each demand class and the average total cost per unit time. E cient solution methods for obtaining optimal policies, with and without service level constraints, are presented. Numerical experiments in which the solution methods are tested demonstrate that signi cant cost reductions can be achieved by distinguishing between demand classes.

International Journal of Production Economics, 1996

In this paper we consider a single-product, single-echelon production and inventory system with p... more In this paper we consider a single-product, single-echelon production and inventory system with product returns, product remanufacturing, and product disposal. For this system we consider three different procurement and inventory control strategies, i.e., the (sp,Qp,sd,N) strategy, the (sp,Qp,sd) strategy, and the (sp, Q,,AJ) strategy. The control parameters in these strategies relate to the inventory position at which an outside procurement order is placed (sp), the inventory position at which returned products are disposed of (sd), the outside procurement order quantity (Q,), and the capacity of the remanufacturing facility (N). For each of the strategies we derive exact expressions of the total expected costs as functions of the control parameters. Main objective of this paper is to compare the performance of each of the alternative strategies with respect to costs, under different system conditions.

International Journal of Production Economics, 1996

In this paper we analyse an (s, Q) inventory model in which used products can be remanufactured t... more In this paper we analyse an (s, Q) inventory model in which used products can be remanufactured to new ones. Wc develop two approximations for the average costs and compare their performance with that of an approximation suggested by Muckstadt and Isaac. Next we extend the model with the option to dispose returned products and present a heuristic optimisation procedure which is checked with full enumeration.

Lecture Notes in Economics and Mathematical Systems, 2005

Products, components, materials and other equipment stream forward and back wards and back in the... more Products, components, materials and other equipment stream forward and back wards and back in their supply chains. Reverse Logistics deals with the processes associated with the reverse stream from users/owners to re-users. This paper provides a review and content analysis of scientific literature on reverse logistics case studies. Over sixty case studies are included. In addition, we give an overview of particular issues, which we link with propositions, unanswered questions and thus directions for future research.

This paper gives an overview of scientific literature that describes and discusses cases of rever... more This paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addition we compare practice with theoretical models and point out research opportunities in the field.

In this report we discuss a model that can be used to determine stocking levels using the data th... more In this report we discuss a model that can be used to determine stocking levels using the data that comes forward from a Shell RCM analysis and the data available in E-SPIR. The model is appropriate to determine stock quantities for parts that are used in redundancy situations, and for parts that are used in different pieces of equipment with different downtime costs. Estimating the annual production loss using the model consists of a number of steps. First, we need to determine which spares are used for the repairs of which failure modes. In the second step, we estimate the average waiting time for spares as a function of the number of spares stocked. In the third step, the annual downtime costs are determined. We combine the downtime costs with the holding costs to determine the optimal number of parts to stock.