Balazs David

55877174300

Publications - 4

Comparison of discrete- and continuous-time models for scheduling waste wood processing facilities

Máté Hegyháti Balazs David O. Ooz

Publication Name: Central European Journal of Operations Research

Publication Date: 2023-09-01

Volume: 31

Issue: 3

Page Range: 853-871

Description:

With the growing significance of environmental awareness, the role of renewable materials and their reuse and recycling possibilities have become increasingly important. Wood is one of the best examples for this, as it is a material that has a variety of primary uses, while also being a prime candidate for reuse and recycling. An important phase in most waste wood value chains is the processing of bulk waste from various sources, usually by means of shredding. This paper presents methods for scheduling the machines in such a waste wood processing facility, where incoming deliveries of different types of wood are processed by a series of treatment and transformation steps to produce shredded wood. Two mathematical models are developed for the problem that both allow overlaps between consecutive steps to optimize resource flow through the system. One of these is a more traditional discrete-time model, while the other is precedence-based and uses continuous-time variables for the timing of the various tasks. Both modeling techniques have their advantages and shortcomings with regard to the ease of integration of further problem-specific parameters and requirements. Next to providing a sound approach for the identified problem class, another aim is to evaluate, which technique suits better for this problem class, and should be used as a basis for extended and integrated cases in the future. Thus, the performance of these models is compared on instances that were randomly generated based on real-world distributions from the literature.

Open Access: Yes

DOI: 10.1007/s10100-023-00852-6

Robust scheduling of waste wood processing plants with uncertain delivery sources and quality

Máté Hegyháti Balazs David O. Ooz

Publication Name: Sustainability Switzerland

Publication Date: 2021-05-01

Volume: 13

Issue: 9

Page Range: Unknown

Description:

While the study of reverse wood value chains has become an important topic recently, optimization-focused studies usually consider network-level problems and decisions, and do not address the individual processes in the network. In the case of waste wood, one such important process is the scheduling of the various machines in a waste wood processing facility to treat incoming wood deliveries with multiple sources and varying quality. This paper proposes a robust multi-objective mixed-integer linear programming model for the optimization of this process that considers the uncertain origins and compositions of the incoming deliveries, while aiming to minimize both lateness and energy consumption. An exhaustive study is performed on instance sets of different sizes and structures to show the efficiency and the limits of the proposed model both in single-and multi-objective cases.

Open Access: Yes

DOI: 10.3390/su13095007

SCHEDULING OF WASTE WOOD PROCESSING FACILITIES WITH OVERLAPPING JOBS

Máté Hegyháti Balazs David O. Ooz

Publication Name: Proceedings of the 16th International Symposium on Operational Research in Slovenia Sor 2021

Publication Date: 2021-01-01

Volume: Unknown

Issue: Unknown

Page Range: 321-326

Description:

An important phase in most waste wood value chains is the processing of bulk waste from various sources, usually by means of shredding. This paper presents a method for scheduling the machines in such a waste wood processing facility, where incoming deliveries of different types of wood are processed by a series of treatment and transformation steps to produce shredded wood. A mathematical model is presented for the problem, that allows overlaps between consecutive steps to optimize resource flow through the system. The efficiency of the model is presented on randomly generated instances.

Open Access: Yes

DOI: DOI not available

Linearly priced timed automata for the bus schedule assignment problem

Máté Hegyháti Balazs David Miklos Kresz

Publication Name: Proceedings Gol 2018 4th IEEE International Conference on Logistics Operations Management

Publication Date: 2018-06-08

Volume: Unknown

Issue: Unknown

Page Range: 1-7

Description:

Papers dealing with optimization problems in public transportation usually follow the same methodology. The problem is modeled in a classical mathematical way, and then either solved directly using mathematical programming methods, or by the application of combinatorial heuristics. Even if this process yields an optimal solution, it might prove complicated to apply the achieved results directly in practice. In a transportation system, solutions for individual problems are only part of a more complex process, and they are often used only to aid experts in making decisions. However, the structure of the problem and the steps taken to achieve the solution are often lost in the solution process, while they might prove extremely useful to a human planner. This paper introduces a linearly priced timed automata model for the bus schedule assignment problem. With its help, the steps taken to achieve any feasible solution of the problem can be easily reconstructed, providing another tool for human experts to use in their decision planning process.

Open Access: Yes

DOI: 10.1109/GOL.2018.8378104