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EN
The development of competitiveness on world markets caused the need to increase production flexibility. An essential tool in achieving this purpose could be production scheduling. Unfortunately, the production process is associated with presence of numerous random events that negatively affect its course. Therefore, it is necessary to apply appropriate prediction methods which help to reduce its affect. The paper presents the conception of robust production scheduling. The typical scheduling problems and robust scheduling idea are described. Moreover, the current solutions of production scheduling under uncertainty are outlined. Finally, the idea of creating robust schedules based on previous production processes are presented. In the final part of the paper the author presented problems related to proposed idea.
EN
In the paper, the proposition of application of two methodologies: the predictive scheduling and Total Productive Maintenance – TPM to increase efficiency of a production system is presented. To assess wastes due to unplanned events in the machine’s work the Overall Equipment Effectiveness (OEE) indicator is applied. Any failure of a bottle neck decreases value of the OEE. In this paper, the problem of predicting a time of the bottle neck failure is considered. In the paper, models of a production system and failures are presented. For the bottle neck various reliability characteristics are computed: the probability that, beginning with moment t0 , the first failure occurs after given time t, probability that in the interval [f ,g], there occurs at least one failure, failure intensity function, Mean Time To Failure (MTTF) and Mean Time of Repair (MTTR). Having the MTTF and MTTR of the bottle neck, a robust schedule is generated. At the time of predicted failure, preventive actions and technical survey of the machine are scheduled. In the second paper a numerical example is given.
EN
In the paper, the proposition of application of two methodologies: the predictive scheduling and Total Productive Maintenance - TPM to increase efficiency of a production system is presented. In this paper, an example of problem of predicting a time of a bottle neck failure is presented. Using the Statistica program, histograms that show the graphical relationship of a number of observations and failure-free times of the bottle neck for historical periods are created. The fitting of the histograms to the theoretical distributions: normal, exponential, gamma and Weibull using appropriate tests (for example the Kolmogorov-Smirnov test for normal distribution) is researched. After finding distribution and setting parameters for historical periods, for the next scheduling horizon values of parameters are extrapolated using the regression method in the Statistica program. For the bottle neck various reliability characteristics are computed. Having the Mean Time To Failure (MTTF) and Mean Time of Repair (MTTR) of the bottle neck, robust schedule is generated. At the time of the predicted failure, preventive actions and technical survey of the machine are scheduled. The production system is modeled in the simulation program - Enterprise Dynamics 8.1.
4
Content available Resource allocation for robust project scheduling
EN
The paper presents a formal description of the resource allocation problem for resource-constrained project scheduling. A schedule can be executed by various resource flow networks which may differ in terms of resistance to disruptions occurring during project execution. The authors define such criteria of evaluating a resource flow network which can be more useful than robustness metrics used so far in the research. The authors discuss the importance of robust scheduling for execution projects and propose metrics for resource allocation robustness which take into consideration the stability of the final schedule. Those metrics make it possible to carry out a more precise analysis concerning the properties of the resource flow network in terms of its robustness to disruptions in comparison with a well known flexibility indicator, flex.
PL
Artykuł prezentuje model harmonogramowania projektu z ograniczoną dostępnością zasobów (ang. RCPSP - Resource-Constrained Project Scheduling Problem) ze zdefiniowanymi terminami realizacji kamieni milowych projektu. Dla tego modelu proponowany jest priorytetowy algorytm alokacji buforów. Skuteczność opisanego algorytmu jest testowana przy użyciu zbioru instancji J30 i J90 z biblioteki PSPLIB (ang. Project Scheduling Problem LIBrary).
EN
This paper presents a model of the Resource-Constrained Project Scheduling Problem (RCPSP) with defined terms of milestones achievement. For this model is proposed priority algorithm of buffer allocation. Effectiveness of described algorithm is tested using a set of J30 and J90 problem instances from the Project Scheduling Problem LIBrary (PSPLIB).
PL
W artykule przedstawiono algorytmy odpornej alokacji zasobów dla problemu harmonogramowania projektu z ograniczoną dostępnością zasobów. Skuteczność algorytmów przydziału zasobów przetestowano przy użyciu zbioru zadań testowych J90 z biblioteki PSPLIB. Jako kryterium oceny stosowano zaproponowane przez autorów miary odporności alokacji zasobów.
EN
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.
7
Content available remote Harmonogramowanie odporne procesu technologicznego montażu
PL
Harmonogramowanie odporne jest nowym podejściem stosowanym w dynamicznych systemach produkcyjnych. W podejściu tym tworzy się uszeregowanie, które ze względu na swoje właściwości, jest odporne na zakłócenia występujace w trakcie produkcji. W artykule zaprezentowano podstawowe informacje dotyczące tworzenia odpornych harmonogramów realizacji procesu technologicznego montażu.
EN
Robust scheduling is a new approach used in dynamic manufacturing systems. The aim of this approach is to create a schedule which, due to its properties, is resistant to disruptions that may appear in the production process. In article are presented basic informations about developing robust sequences to technological assembly process.
8
Content available remote Predictive scheduling with determined terms of milestone achievement
EN
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.
PL
Harmonogramowanie predyktywne jest nowym podejściem wykorzystywanym podczas planowania produkcji. W podejściu tym tworzy się harmonogram odporny na możliwe zakłócenia występujące w trakcie realizacji tego uszeregowania. W artykule zaprezentowano algorytmy dla predyktywnego harmonogramowania produkcji z ograniczoną dostępnością zasobów RCPSP (ang. Resource-Constrained Project Scheduling Problem), z określonymi terminami realizacji części zadań.
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