Browsing by Author "Klimek, Marcin"

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Access status: Open Access ,
A two-phase algorithm for a Resource Constrained Project Scheduling Problem with Discounted Cash Flows
(2013) Klimek, Marcin; Łebkowski, Piotr
This 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.
Access status: Open Access ,
Algorytmy odpornej alokacji zasobów dla problemu harmonogramowania projektu z ograniczoną dostępnością zasobów
(Wydawnictwa AGH, 2009) Klimek, Marcin; Łebkowski, Piotr
In 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.
Access status: Open Access ,
Alokacja zasobów dla problemu harmonogramowania projektu z ważonymi kosztami niestabilności
(Wydawnictwa AGH, 2011) Klimek, Marcin; Łebkowski, Piotr
Article 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.
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, Piotr
The 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.
Access status: Open Access ,
Predictive scheduling with determined terms of milestone achievement
(AGH University of Science and Technology Press, 2008) Klimek, Marcin; Łebkowski, Piotr
Predictive scheduling is a new approach used in production planning. The aim of this approach is to develop robust schedules and solutions that are able to absorb disruptions during the schedule execution. In this paper, we present algorithms of predictive scheduling for the Resource-Constrained Project Scheduling Problem (RCPSP), with defined dates of selected activities.
Access status: Open Access ,
Robust buffer allocation for scheduling of a project with predefined milestones
(Wydawnictwa AGH, 2009) Klimek, Marcin; Łebkowski, Piotr
The 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.
Access status: Open Access ,
Sieci Hopfielda dla problemu komiwojażera
(Wydawnictwa AGH, 2005) Klimek, Marcin
In article is described an idea Hopfield neural network for solving combinatorial optimization problems, specifically for the Traveling Salesman Problem (TSP). It was implemented three algorithms for solving TSP with Hopfield nets. The performance of these algorithms was examined in simulation study. Results of experiments are described in this work. According to these results, the conclusion is that the Hopfield nets are not applicable for solving TSP.