Łebkowski, Piotr
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nauki o zarządzaniu i jakości
inżynieria mechaniczna
inżynieria mechaniczna
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Item type:Article, Access status: Open Access , Concept of industry 4.0-related Manufacturing Technology Maturity Model (ManuTech Maturity Model - MTMM)(AGH University of Science and Technology Press, 2018) Gracel, Jarosław; Łebkowski, PiotrThe main objective of this article is to describe Industry 4.0 and the key manufacturing-technology-related technological and business challenges for manufacturing companies. The groups especially interested in the implementation of Industry 4.0 are the operations, technical, and production directors responsible for operational excellence of manufacturing plants, strategic development, and business continuity. Based on the latest Industry 4.0 and manufacturing technology market research, factories located in Poland are less technologically advanced than their counterparts in Western European plants. Accordingly, development of the model for assessing the current level of maturity for manufacturing technology related to the Industry 4.0 initiative becomes a relevant research task. In the article, key Industry 4.0-related technological areas will be described. Based on extensive research into international references and industrial consulting experiences in the industrial business consulting conducted in Polish manufacturing companies, the manufacturing technology ManuTech Maturity Model (MTMM) concept related to Industry 4.0 will be developed and presented. A substantial and innovative part of the article will be devoted to the adjustment of a proposed maturity model to specific features of the Polish industrial and manufacturing sector. This will be relevant due to the noticeable differences in the levels of technological advancement between the Western and Eastern Europe sectors.Item type:Article, Access status: Open Access , A two-phase algorithm for a Resource Constrained Project Scheduling Problem with Discounted Cash Flows(2013) Klimek, Marcin; Łebkowski, PiotrThis paper presents a Resource-Constrained Project Scheduling Problem (RCPSP) settled by contractual milestones. The criterion analysed here is the maximisation of aggregate discounted cash flows from the contractor's perspective, known as an RCPSP problem with Discounted Cash Flows (RCPSPDCF). The cash flows analysed here cover the contractor´s cash outflows (negative cash flows), related to the commencement of individual activities, and cash inflows (positive cash flows) after the fulfilment of individual milestones. The authors propose a two-phase algorithm for solving the problem defined. In the first phase, the simulated annealing metaheuristics is used, designed to identify a forward schedule with as high total DCF as possible. In the second phase, the best first-phase schedule is improved by right shifts of activities. To this end, the procedure which iteratively shifts tasks by one unit is applied, with a view to maximising the objective function. Activity shifts take into consideration precedence and resource constraints, and they are performed for a specified resource allocation to activities. This paper also includes an analysis of the problem for a sample project. The results of computational experiments are then analysed. The experiments were run with the use of standard test problems from the Project Scheduling Problem LIBrary (PSPLIB), with additionally defined cash flows and contractual milestones.Item type:Article, Access status: Open Access , Sequential simulated annealing for the vehicle routing problem with time windows(Wydawnictwa AGH, 2009) Woch, Marcin; Łebkowski, PiotrThis article presents a new simulated annealing algorithm that provides very high quality solutions to the vehicle routing problem. The aim of described algorithm is to solve the vehicle routing problem with time windows. The tests were carried out with use of some well known instances of the problem defined by M. Solomon. The empirical evidence indicates that simulated annealing can be successfully applied to bi-criterion optimization problems.Item type:Article, Access status: Open Access , Insertion algorithms with justification for solving the Resource-Constrained Project Scheduling(AGH University of Science and Technology Press, 2016) Klimek, Marcin; Łebkowski, PiotrThe paper presents the resource-constrained project scheduling problem with the makespan minimization criterion. To solve the problem, the authors propose insertion algorithms that generate schedules with the use of forward serial and parallel decoding procedures. Schedules are improved with the use of the double justification by the extremes technique (first right and then left justification). The efficiency of the procedures proposed is tested on standard test problems from the PSPLIB library.Item type:Article, Access status: Open Access , Robust buffer allocation for scheduling of a project with predefined milestones(Wydawnictwa AGH, 2009) Klimek, Marcin; Łebkowski, PiotrThe paper discusses the problem of robust buffer allocation for Resource-Constrained Project Scheduling Problem (RCPSP) with predefined milestones1 , for which execution deadlines have been established. To solve the problem, an algorithm is proposed supporting insertion of unit time buffers, with the simultaneous maximisation of new metrics of arrangement robustness. The presented results of experimental research speak for usability of the solutions proposed. The effectiveness is studied with use of test tasks2 included in the Project Scheduling Problem Library (PSPLIB) with additionally specified project milestones.Item type:Article, Access status: Open Access , Algorytmy odpornej alokacji zasobów dla problemu harmonogramowania projektu z ograniczoną dostępnością zasobów(Wydawnictwa AGH, 2009) Klimek, Marcin; Łebkowski, PiotrIn article are presented algorithms of robust resource allocation for resource-constrained project scheduling problem. Effectiveness of algorithms have been tested on the J90 instance set of PSPLIB. As the evaluation criterion proposed by authors measures of robustness of resource allocations were applied.Item type:Article, Access status: Open Access , Alokacja zasobów dla problemu harmonogramowania projektu z ważonymi kosztami niestabilności(Wydawnictwa AGH, 2011) Klimek, Marcin; Łebkowski, PiotrArticle presents resource allocation problem for resource-constrained project scheduling problem with weighted instability costs of tasks. Rules of allocations which may have an influence on increase robustness of schedule were denoted. Measures of robustness of resource allocations which take into consideration the effect of the duration lengthening for individual activities on the stability of the schedule completed were proposed.Item type:Article, Access status: Open Access , Petri nets of the materials flow at the steel plant(Wydawnictwa AGH, 2007) Łebkowski, PiotrA Petri deterministic time net applied to the modelling of the material flow at the steel plant is a very effective research tool. This paper presents a Petri net expanded with the attribute vectors of places and transitions, as well as the logical rules of transition launching and the procedures that update the attribute values. Owing to such an expansion, we can observe the properties of the streams that flow through the system, e.g. the costs and the project completion time, simulate the effects of the changes introduced into the system and analyse the results of unexpected disturbances and the breaks in the supply chain.