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Papers by Jörn Schönberger

Research paper thumbnail of On the Value of Objective Function Adaptation in Online Optimisation

We analyse a dynamic variant of the vehicle routing problem with soft time windows in which an av... more We analyse a dynamic variant of the vehicle routing problem with soft time windows in which an average punctuality must be guaranteed (e.g. lateness is allowed at some customer sites). The existing objective function does not support both the aspiration for punctuality and least cost so that additional efforts are necessary to achieve an acceptable punctuality level at least possible costs. Within numerical experiments it is shown that static penalties are not adequate in such a situation but that an adaptation of the objective function before its application to the next problem instance supports the search for high quality solutions of the problem.

Research paper thumbnail of Planning the Incorporation of Logistics Service Providers to Fulfill Precedence and Time Window-Constrained Transport Requests in a Most Profitable Way

We investigate an extension of the Pickup and Delivery Problem with Time Windows (PDPTW) in which... more We investigate an extension of the Pickup and Delivery Problem with Time Windows (PDPTW) in which only a part of the available request portfolio can be fulfilled by own equipment and the remaining requests are served by subcontracted carriers (Logistic Service Providers). The costs for the fulfillment of the request portfolio result in the sum of travel costs for the self-served requests and the charges paid to the Logistic Service Providers. A Memetic Algorithm (MA) is configured to determine solutions of this combined selection, assignment and sequencing problem. Special genetic operators are proposed to identify those requests that should be served by Logistics Service Providers in order to minimize the overall fulfillment costs. By means of suitable benchmark instances, the capability of the algorithmic approach is assessed and the impacts of the selection feature are analyzed.

Research paper thumbnail of Rules for the Identification Portfolio-incompatible Requests in Dynamic Vehicle Routing

In this article, we propose and evaluate simple rules for selecting transport requests that do no... more In this article, we propose and evaluate simple rules for selecting transport requests that do not fit into a request portfolio because their temporal or spatial requirements are incompatible with the requirements of other request so that the compilation of profitable routes is compromised. We integrate these rules into an adaptive online vehicle operations planning system and analyze in numerical simulation experiments how their application impacts on the flexibility, the stability and the profitability of the controlled transportation system and the integration of consecutively arriving request.

Research paper thumbnail of On Decision Model Adaptation in Online Optimization of a Transport System

This article is about the enhancement of myopic online decision approaches for considering longer... more This article is about the enhancement of myopic online decision approaches for considering longer term planning goals in the management of logistic processes in a dynamically varying environment. By means of a demand peak we simulate a severe disruption of the environment of a transport system and show that a pure myopic scheduling strategy is not able to ensure an acceptable service level in such a situation. As a remedy, we propose to adapt automatically the short term decision behaviour of the used decision making algorithm. We anticipate the instantiation of a reasonable number of decision variables in a model pre-processing step in order to break the rule of selecting the least cost but also low quality decision alternatives. Within several numerical experiments we prove the applicability and suitability of our approach.

Research paper thumbnail of Interactive Solving of Vehicle Routing and Scheduling Problems: Basic Concepts and Qualification of Tabu Search Approaches

This paper introduces a framework for the interactive solving of optimization problems and presen... more This paper introduces a framework for the interactive solving of optimization problems and presents an interactive tabu search algorithm for the pick-up-and-delivery problem with time windows (PDPTW). The framework for the development of interactive algorithms is based on the idea of activating and deactivating constraints in the model of the problem under consideration. We start with an introduction to interactive problem solving and suggest an algorithmic framework. Next we focus to vehicle routing and scheduling applications. There we discuss the demand for interactive approaches, since established local search methods fail to produce reasonable solutions. Our idea is to support them by interactive manipulations. Therefore, we present a recent tabu search algorithm for the PDPTW. We demonstrate several possibilities for human interactions by means of an additional tabu list.

Research paper thumbnail of Autonomously Controlled Adaptation of Formal Decision Models - Comparison of Generic Approaches

Research paper thumbnail of 1 Autonomous Decision Model Adaptation and the Vehicle Routing Problem with Time Windows and Uncertain Demand

Research paper thumbnail of Memetic Algorithm timetabling for non-commercial sport leagues

European Journal of Operational Research, 2004

We address the automatic generation of timetables for non-commercial sport leagues. By example of... more We address the automatic generation of timetables for non-commercial sport leagues. By example of table-tennis we stress the particularity of non-commercial leagues, namely the limited access to sport facilities and temporary non-availability of sportsmen. For this problem class we propose a Memetic Algorithm backed by a constraint propagation based heuristic. The order of variable instantiation for this heuristic is evolved adaptively by means of a co-evolutionary approach.

Research paper thumbnail of Online decision making and automatic decision model adaptation

Computers & Operations Research, 2009

The paper investigates an online version of the vehicle routing problem with time windows, in whi... more The paper investigates an online version of the vehicle routing problem with time windows, in which additionally arriving requests cause the revision of so far followed routes and schedules. An extended online optimization framework is proposed, which automatically adapts to problem variations and enables the explicit consideration of up-to-date knowledge about the current performance of the controlled system. Actually, we use the mean punctuality observed in the transportation system to adjust the objective function utilized for solving the next decision problem instance. The search is guided toward least cost solutions coming along with high punctuality. We prove the applicability of this approach within comprehensive numerical experiments.

Research paper thumbnail of Integration von Software-Agenten und Soft-Computing-Methoden für die Transportplanung

Zusammenfassung: Anwendungen in der Transportlogistik zeichnen sich durch eine besonders hohe Kom... more Zusammenfassung: Anwendungen in der Transportlogistik zeichnen sich durch eine besonders hohe Komplexität und Dynamik aus. In diesem Rahmen haben sich Soft-Computing-Ansätze für die Disposition etabliert, da sie eine effiziente Planung ermöglichen. Daneben werden in der Forschung Ansätze zur Transportplanung mit Hilfe von Multiagentensystemen untersucht, die eine natürliche Repräsentation bieten und hierbei autonomes und robustes Verhalten ermöglichen. Die Integration von Multiagentensystemen und Soft-Computing-Methoden wird in diesem Beitrag als Lösungsansatz beschrieben, um robuste und flexibel reagierende selbststeuernde logistische Prozesse in dieser Domäne zu realisieren.

Research paper thumbnail of Automated timetable generation for rounds of a table-tennis league

In this research we consider the problem of scheduling rounds of a non-professional table-tennis ... more In this research we consider the problem of scheduling rounds of a non-professional table-tennis league.

Research paper thumbnail of Decision support systems and the coordination of supply consortium partners

Computers in Industry, 2011

Research paper thumbnail of Integration zentraler Prozess-Optimierung und lokaler agentenbasierter Prozess-Anpassung für das Management von Transportprozessen in dynamischen Umgebungen

Research paper thumbnail of Supporting Cooperative Demand Fulfillment in Supply Networks Using Autonomous Control and Multi-Agent-Systems

Today, economic value creation is typically carried out in supply networks, which are temporal co... more Today, economic value creation is typically carried out in supply networks, which are temporal coalitions of independent partners. Each partner has its own decision competencies but the common objective of value creation requires a coordinated planning of the value creating processes. We show that the common decision making process can be understood as a combination of a Multi Agent System (MAS) and decision making according to the paradigm of autonomous control. This combination is an appropriate approach to coordinate the agents in the demand fulfilment process. We extract the advantages and deficiencies of autonomously controlled MAS. Our example of transport process planning combines the advantages of autonomous decision making by the agents and of a central coordination instance. This coordination instance may intervene only if the achievement of the common objective is severely endangered.

Research paper thumbnail of Operations Research Proceedings 2005, Selected Papers of the Annual International Conference of the German Operations Research Society (GOR), Bremen, September 7-9, 2005

... 137 A Group Setup Strategy for PCB Assembly on a Single Automated Placement Machine Ihsan Onu... more ... 137 A Group Setup Strategy for PCB Assembly on a Single Automated Placement Machine Ihsan Onur Yilmaz, Hans-Otto Gunther ... 229 Effizienzanalyse deutscher Banken mit Data Envelopment Analysis und Stabilitatsanalysen Armin Varmaz..... ...

Research paper thumbnail of Transport system responsiveness improvement

International Journal of Physical Distribution & Logistics Management, 2009

Purpose -The coping of demand oscillation is an important challenge in dynamic transport planning... more Purpose -The coping of demand oscillation is an important challenge in dynamic transport planning. A reliable request fulfillment must be provided even if the number of incoming requests temporarily climbs over the expected demand and resource scarceness appears. The aim of this paper is to propose an innovative planning approach that enables a transportation fleet to maintain a sufficiently high percentage of timely-fulfilled customer requests even in demand peak situations. Design/methodology/approach -The effectiveness of the new approach is verified in computational simulation experiments. Quantifications for the system's responsiveness are proposed. Then, the quantified knowledge about the intermediate responsiveness is exploited to adjust the decision model representing the next schedule update task in a rolling horizon re-planning. Findings -The observed simulation results suggest the suitability of the proposed approach. An adjustment of the plan update model supports the maintenance of a high percentage of timely completed requests during and after the demand peak.

Research paper thumbnail of Autonomy and decentralized decision making in logistics: new ideas, technological innovations, enhanced decision support, and initial applications

Research paper thumbnail of Flexible Transport Process Planning in Volatile Environments and the Adaptation of a Cost-Based Objective Function

Research paper thumbnail of A General Approach to Robustness in Logistics – Basic Concepts, Quantification Approaches and Experimental Evaluations

We direct our attention to robustness issues of dynamic decision problems. After having structure... more We direct our attention to robustness issues of dynamic decision problems. After having structured the discussion of robustness in the scientific literature, we develop a generic, domain-independent definition of the term “robust” by strictly distinguishing “acceptable” and “unacceptable” schedule updates. The main innovation is the development of a general approach to robustness that does not rely on domain-specific assumptions and the proposal of a quantification scheme to measure robustness-related properties. We prove the general applicability of our robustness concept in experiments with a transport system.

Research paper thumbnail of Freight Flow Consolidation in Presence of Time Windows

This contribution addresses the consideration of time windows in the optimization of multi-commod... more This contribution addresses the consideration of time windows in the optimization of multi-commodity network flows. For each node, one interval is specified in which the visitation is allowed. Applications in freight flow consolidation let this problem become interesting. An optimization model is proposed and a construction heuristic is presented. For improving the generated solutions, a genetic algorithm framework including several hill climbing procedures for local optimization, is configured.

Research paper thumbnail of On the Value of Objective Function Adaptation in Online Optimisation

We analyse a dynamic variant of the vehicle routing problem with soft time windows in which an av... more We analyse a dynamic variant of the vehicle routing problem with soft time windows in which an average punctuality must be guaranteed (e.g. lateness is allowed at some customer sites). The existing objective function does not support both the aspiration for punctuality and least cost so that additional efforts are necessary to achieve an acceptable punctuality level at least possible costs. Within numerical experiments it is shown that static penalties are not adequate in such a situation but that an adaptation of the objective function before its application to the next problem instance supports the search for high quality solutions of the problem.

Research paper thumbnail of Planning the Incorporation of Logistics Service Providers to Fulfill Precedence and Time Window-Constrained Transport Requests in a Most Profitable Way

We investigate an extension of the Pickup and Delivery Problem with Time Windows (PDPTW) in which... more We investigate an extension of the Pickup and Delivery Problem with Time Windows (PDPTW) in which only a part of the available request portfolio can be fulfilled by own equipment and the remaining requests are served by subcontracted carriers (Logistic Service Providers). The costs for the fulfillment of the request portfolio result in the sum of travel costs for the self-served requests and the charges paid to the Logistic Service Providers. A Memetic Algorithm (MA) is configured to determine solutions of this combined selection, assignment and sequencing problem. Special genetic operators are proposed to identify those requests that should be served by Logistics Service Providers in order to minimize the overall fulfillment costs. By means of suitable benchmark instances, the capability of the algorithmic approach is assessed and the impacts of the selection feature are analyzed.

Research paper thumbnail of Rules for the Identification Portfolio-incompatible Requests in Dynamic Vehicle Routing

In this article, we propose and evaluate simple rules for selecting transport requests that do no... more In this article, we propose and evaluate simple rules for selecting transport requests that do not fit into a request portfolio because their temporal or spatial requirements are incompatible with the requirements of other request so that the compilation of profitable routes is compromised. We integrate these rules into an adaptive online vehicle operations planning system and analyze in numerical simulation experiments how their application impacts on the flexibility, the stability and the profitability of the controlled transportation system and the integration of consecutively arriving request.

Research paper thumbnail of On Decision Model Adaptation in Online Optimization of a Transport System

This article is about the enhancement of myopic online decision approaches for considering longer... more This article is about the enhancement of myopic online decision approaches for considering longer term planning goals in the management of logistic processes in a dynamically varying environment. By means of a demand peak we simulate a severe disruption of the environment of a transport system and show that a pure myopic scheduling strategy is not able to ensure an acceptable service level in such a situation. As a remedy, we propose to adapt automatically the short term decision behaviour of the used decision making algorithm. We anticipate the instantiation of a reasonable number of decision variables in a model pre-processing step in order to break the rule of selecting the least cost but also low quality decision alternatives. Within several numerical experiments we prove the applicability and suitability of our approach.

Research paper thumbnail of Interactive Solving of Vehicle Routing and Scheduling Problems: Basic Concepts and Qualification of Tabu Search Approaches

This paper introduces a framework for the interactive solving of optimization problems and presen... more This paper introduces a framework for the interactive solving of optimization problems and presents an interactive tabu search algorithm for the pick-up-and-delivery problem with time windows (PDPTW). The framework for the development of interactive algorithms is based on the idea of activating and deactivating constraints in the model of the problem under consideration. We start with an introduction to interactive problem solving and suggest an algorithmic framework. Next we focus to vehicle routing and scheduling applications. There we discuss the demand for interactive approaches, since established local search methods fail to produce reasonable solutions. Our idea is to support them by interactive manipulations. Therefore, we present a recent tabu search algorithm for the PDPTW. We demonstrate several possibilities for human interactions by means of an additional tabu list.

Research paper thumbnail of Autonomously Controlled Adaptation of Formal Decision Models - Comparison of Generic Approaches

Research paper thumbnail of 1 Autonomous Decision Model Adaptation and the Vehicle Routing Problem with Time Windows and Uncertain Demand

Research paper thumbnail of Memetic Algorithm timetabling for non-commercial sport leagues

European Journal of Operational Research, 2004

We address the automatic generation of timetables for non-commercial sport leagues. By example of... more We address the automatic generation of timetables for non-commercial sport leagues. By example of table-tennis we stress the particularity of non-commercial leagues, namely the limited access to sport facilities and temporary non-availability of sportsmen. For this problem class we propose a Memetic Algorithm backed by a constraint propagation based heuristic. The order of variable instantiation for this heuristic is evolved adaptively by means of a co-evolutionary approach.

Research paper thumbnail of Online decision making and automatic decision model adaptation

Computers & Operations Research, 2009

The paper investigates an online version of the vehicle routing problem with time windows, in whi... more The paper investigates an online version of the vehicle routing problem with time windows, in which additionally arriving requests cause the revision of so far followed routes and schedules. An extended online optimization framework is proposed, which automatically adapts to problem variations and enables the explicit consideration of up-to-date knowledge about the current performance of the controlled system. Actually, we use the mean punctuality observed in the transportation system to adjust the objective function utilized for solving the next decision problem instance. The search is guided toward least cost solutions coming along with high punctuality. We prove the applicability of this approach within comprehensive numerical experiments.

Research paper thumbnail of Integration von Software-Agenten und Soft-Computing-Methoden für die Transportplanung

Zusammenfassung: Anwendungen in der Transportlogistik zeichnen sich durch eine besonders hohe Kom... more Zusammenfassung: Anwendungen in der Transportlogistik zeichnen sich durch eine besonders hohe Komplexität und Dynamik aus. In diesem Rahmen haben sich Soft-Computing-Ansätze für die Disposition etabliert, da sie eine effiziente Planung ermöglichen. Daneben werden in der Forschung Ansätze zur Transportplanung mit Hilfe von Multiagentensystemen untersucht, die eine natürliche Repräsentation bieten und hierbei autonomes und robustes Verhalten ermöglichen. Die Integration von Multiagentensystemen und Soft-Computing-Methoden wird in diesem Beitrag als Lösungsansatz beschrieben, um robuste und flexibel reagierende selbststeuernde logistische Prozesse in dieser Domäne zu realisieren.

Research paper thumbnail of Automated timetable generation for rounds of a table-tennis league

In this research we consider the problem of scheduling rounds of a non-professional table-tennis ... more In this research we consider the problem of scheduling rounds of a non-professional table-tennis league.

Research paper thumbnail of Decision support systems and the coordination of supply consortium partners

Computers in Industry, 2011

Research paper thumbnail of Integration zentraler Prozess-Optimierung und lokaler agentenbasierter Prozess-Anpassung für das Management von Transportprozessen in dynamischen Umgebungen

Research paper thumbnail of Supporting Cooperative Demand Fulfillment in Supply Networks Using Autonomous Control and Multi-Agent-Systems

Today, economic value creation is typically carried out in supply networks, which are temporal co... more Today, economic value creation is typically carried out in supply networks, which are temporal coalitions of independent partners. Each partner has its own decision competencies but the common objective of value creation requires a coordinated planning of the value creating processes. We show that the common decision making process can be understood as a combination of a Multi Agent System (MAS) and decision making according to the paradigm of autonomous control. This combination is an appropriate approach to coordinate the agents in the demand fulfilment process. We extract the advantages and deficiencies of autonomously controlled MAS. Our example of transport process planning combines the advantages of autonomous decision making by the agents and of a central coordination instance. This coordination instance may intervene only if the achievement of the common objective is severely endangered.

Research paper thumbnail of Operations Research Proceedings 2005, Selected Papers of the Annual International Conference of the German Operations Research Society (GOR), Bremen, September 7-9, 2005

... 137 A Group Setup Strategy for PCB Assembly on a Single Automated Placement Machine Ihsan Onu... more ... 137 A Group Setup Strategy for PCB Assembly on a Single Automated Placement Machine Ihsan Onur Yilmaz, Hans-Otto Gunther ... 229 Effizienzanalyse deutscher Banken mit Data Envelopment Analysis und Stabilitatsanalysen Armin Varmaz..... ...

Research paper thumbnail of Transport system responsiveness improvement

International Journal of Physical Distribution & Logistics Management, 2009

Purpose -The coping of demand oscillation is an important challenge in dynamic transport planning... more Purpose -The coping of demand oscillation is an important challenge in dynamic transport planning. A reliable request fulfillment must be provided even if the number of incoming requests temporarily climbs over the expected demand and resource scarceness appears. The aim of this paper is to propose an innovative planning approach that enables a transportation fleet to maintain a sufficiently high percentage of timely-fulfilled customer requests even in demand peak situations. Design/methodology/approach -The effectiveness of the new approach is verified in computational simulation experiments. Quantifications for the system's responsiveness are proposed. Then, the quantified knowledge about the intermediate responsiveness is exploited to adjust the decision model representing the next schedule update task in a rolling horizon re-planning. Findings -The observed simulation results suggest the suitability of the proposed approach. An adjustment of the plan update model supports the maintenance of a high percentage of timely completed requests during and after the demand peak.

Research paper thumbnail of Autonomy and decentralized decision making in logistics: new ideas, technological innovations, enhanced decision support, and initial applications

Research paper thumbnail of Flexible Transport Process Planning in Volatile Environments and the Adaptation of a Cost-Based Objective Function

Research paper thumbnail of A General Approach to Robustness in Logistics – Basic Concepts, Quantification Approaches and Experimental Evaluations

We direct our attention to robustness issues of dynamic decision problems. After having structure... more We direct our attention to robustness issues of dynamic decision problems. After having structured the discussion of robustness in the scientific literature, we develop a generic, domain-independent definition of the term “robust” by strictly distinguishing “acceptable” and “unacceptable” schedule updates. The main innovation is the development of a general approach to robustness that does not rely on domain-specific assumptions and the proposal of a quantification scheme to measure robustness-related properties. We prove the general applicability of our robustness concept in experiments with a transport system.

Research paper thumbnail of Freight Flow Consolidation in Presence of Time Windows

This contribution addresses the consideration of time windows in the optimization of multi-commod... more This contribution addresses the consideration of time windows in the optimization of multi-commodity network flows. For each node, one interval is specified in which the visitation is allowed. Applications in freight flow consolidation let this problem become interesting. An optimization model is proposed and a construction heuristic is presented. For improving the generated solutions, a genetic algorithm framework including several hill climbing procedures for local optimization, is configured.