Wyniki wyszukiwania - BazTech

1

New ideas in Lagrangian relaxation for a scheduling problem with the weighted tardiness criterion

Rudy Jarosław, Idzikowski Radosław, Smutnicki Czesław, Banaszak Zbigniew, Bocewicz Grzegorz

International Journal of Applied Mathematics and Computer Science

|

2024

|

Vol. 34, no. 2

235--251

EN

We consider an extension of Lagrangian relaxation methods for solving the total weighted tardiness scheduling problem on a single machine. First, we investigate a straightforward relaxation method and decompose it into upper and lower subproblems. For the upper subproblem we propose an alternative solving method in the form of a local search metaheuristic. We also introduce a scaling technique by arbitrary numbers to reduce the complexity of the problem and confront it with greatest common divisor scaling. Next, we propose a novel alternative relaxation approach based on aggregating constraints. We discuss the properties and implementation of this new approach and a technique to further reduce its computational complexity. We perform a number of computer experiments on instances based on the OR-Library generation scheme to illustrate and ascertain the numerical properties of the proposed methods. The results indicate that for larger instances the proposed alternative relaxation and scaling approaches have a much better convergence rate with little to no decrease in solution quality. The results also show that the proposed local-search metaheuristic is a viable alternative to the existing solving methods.

2

Identifying the potential of unmanned aerial vehicle routing for emergency blood distribution

Dewmini Janani, Fernando W. Madushan, Nielsen Izabela Iwa, Bocewicz Grzegorz, Thibbotuwawa Amila, Banaszak Zbigniew

Applied Computer Science

|

2023

|

Vol. 19, no 4

68--87

EN

This study is focusing on identifying the potential of Unmanned Aerial Vehicle (UAV) routing for blood distribution in emergency requests in Sri Lanka compared to existing transportation modes. Capacitated Unmanned Aerial Vehicle Routing Problem was used as the methodology to find the optimal distribution plan between blood banks directing emergency requests. The developed UAV routing model was tested for different instances to compare the results. Finally, the proposed distribution process via UAVs was compared with the current distribution process for the objective function set up in the model and other Key Performance Indicators (KPIs) including energy consumption savings and operational cost savings. The average percentage reduction in distribution time, reduction in energy consumption costs and reduction in operating costs per day using UAVs was 58.57%, 96.35% and 61.20% respectively for the instances tested using the model, highlighting the potential of UAVs. Therefore, the deficiencies in Sri Lanka's present blood delivery system can be addressed using UAVs' potential for time, cost, and energy savings. The ability to save time through the deployment of UAVs to the fleet during emergency situations plays a crucial role in preventing the loss of human lives.

3

Wspomaganie modelowania i oceny efektywności ESP

Bocewicz Grzegorz, Wójcik Robert, Banaszak Zbigniew

Prace Naukowe Politechniki Warszawskiej. Elektronika

|

2022

|

z. 197, t. 1

81-92

PL

Prezentowana w pracy koncepcja metodyki zautomatyzowanego modelowania i oceny efektywności wykorzystania ESP zilustrowana została na przykładzie metody zautomatyzowanej syntezy modelu referencyjnego konfiguracji ESP i możliwych sposobów organizacji realizowanej w nim produkcji. Opracowany model referencyjny ogranicza przestrzeń możliwych przepływów produkcji tylko do wariantów wolnych od blokad i zagłodzeni. Proponowane rozwiązanie gwarantuje, że każdy wariant konfiguracji systemu i/lub scenariusz przepływu realizowanej w nim produkcji spełnia przyjęte założenia produkcyjne, aczkolwiek z różną efektywnością. Możliwości zastosowania metody implementującej ten model przedstawia przykład ilustrujący etap prototypowania elastycznego modułu obróbkowego, pozwalającego na zintegrowaną ocenę alternatywnych wariantów konfiguracji modułu z alternatywnymi przebiegami realizowanej w nim produkcji wieloasortymentowej.

EN

The paper presents a method of automated modelling and performance evaluation of concurrent production flows carried out in FMSs. The method allows for quick assessment of various variants of such systems, considering their structure and the organization of production flow of possible ways of their implementation in carried out. Its essences is the conditions imposed on the designed model, limiting the space of possible variants of the production flow only to deadlock-free variants. The practical usefulness of the model implemented in the proposed method illustrates the example describing the simultaneous assessment of alternative variants of the flexible machining module’s structures and the planned multi-assortment production. Finally, its capacity to focus on feasible solutions offers attractive perspective for guiding the Digital Twin like scenario in situations caused by the need to change the production flow.

4

Towards digital twin-driven performance evaluation methodology of FMS

Bocewicz Grzegorz, Wójcik Robert, Sitek Paweł, Banaszak Zbigniew

Applied Computer Science

|

2022

|

Vol. 18, no 3

5--18

EN

The paper presents a method of automated modelling and performance evaluation of concurrent production flows carried out in Flexible Manufacturing Systems. The method allows for quick assessment of various variants of such systems, considering their structure and the organization of production flow of possible ways of their implementation. Its essence is the conditions imposed on the designed model, limiting the space of possible variants of the production flow only to deadlock-free variants. The practical usefulness of the model implemented in the proposed method illustrates the example, which describes the simultaneous assessment of alternative variants of the flexible machining module's structure and the planned multi-assortment production. The ability of the method to focus on feasible solutions offers attractive perspectives for guiding the Digital Twin-like scenario in situations caused by the need to change the production flow.

5

A competency-driven staff assignment approach to improving employee scheduling robustness

Bocewicz Grzegorz, Szwarc Eryk, Wikarek Jaroslaw, Nielsen Peter, Banaszak Zbigniew

Eksploatacja i Niezawodność

|

2021

|

Vol. 23, no. 1

117--131

EN

Presented paper concerns the competency-driven staff assignment and scheduling approach to the management of project portfolios subject to perturbations caused by employee absences and/or unexpected arrival of high priority jobs. Proactive strategy is considered, which exploits the concept of employee substitutability to improve the robustness of personnel allocation in the case of occurrence of specific types of disruptions. Solutions obtained using the model of a constraint satisfaction problem developed in this study are validated in series quantitative and qualitative experiments. With a view to future implementation in a Decision Support Systems dedicated to prototyping of proactive personnel allocation, a methodology employing the concept of a competency framework-based robustness measure is proposed. Implemented in a declarative framework, the proposed approach allows one to find a redundant competency framework robust to a given set of disruptions.

6

Problem marszrutyzacji floty dronów

Radzki Grzegorz, Bocewicz Grzegorz, Budzisz Henryk

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

|

2019

|

Nr 15

5--22

PL

W artykule rozważany jest problem dostarczania towarów w sieci dystrybucyjnej, w której operacje transportu realizowane są przez flotę bezzałogowych statków powietrznych (BSP). Szczególny nacisk położony jest na możliwość uwzględniania warunków pogodowych, w których odbywa się transport. Rozważany problem sprowadza się do wyznaczenia marszruty gwarantującej bezkolizyjne dostarczenie towaru do węzła, przy uwzględnieniu warunków pogodowych oraz poziomu baterii dronów. Zaproponowany został deklaratywny model, którego implementacja w środowisku programowania IBM ILOG pozwala na rozwiązywanie tego typu problemów w trybie on-line. Przedstawione eksperymenty obliczeniowe, potwierdzają poprawność opracowanego modelu.

EN

A problem of delivering goods in a distribution network is considered in which, transport operations are carried out by a fleet of unmanned aerial vehicles (UAV). The weather conditions in which a transport operations take place and a UAV battery level are taken into account. The above-mentioned weather conditions and the battery level affect the determination of the route guaranteeing collision-free delivery. The goods must be delivered to a specific node in a given time window. Specifying the route is the focus of this study. Solutions maximizing the level of customer satisfaction are sought. Computational experiments which show impact of the weather conditions to on route determination are presented.

7

Milk-run routing and scheduling subject to a trade-off between vehicle fleet size and storage capacity

Bocewicz Grzegorz, Bożejko Wojciech, Wójcik Robert, Banaszak Zbigniew

Management and Production Engineering Review

|

2019

|

Vol. 10, No. 3

41--53

EN

The objective of the milk-run design problem considered in this paper is to minimize transportation and inventory costs by manipulating ﬂeet size and the capacity of vehicles and storage areas. Just as in the case of an inventory routing problem, the goal is to ﬁnd a periodic distribution policy with a plan on whom to serve, and how much to deliver by what ﬂeet of tugger trains travelling regularly on which routes. This problem boils down to determining the trade-oﬀ between ﬂeet size and storage capacity, i.e. the size of replenishment batches that can minimize ﬂeet size and storage capacity. A solution obtained in the declarative model of the milk-run system under discussion allows to determine the routes for each tugger train and the associated delivery times. In this context, the main contribution of the present study is the identiﬁcation of the relationship between takt time and the size of replenishment batches, which allows to determine the delivery time windows for milkrun delivery and, ultimately, the positioning of trade-oﬀ points. The results show that this relationship is non-linear.

8

Competence allocation planning robust to unexpected staff absenteeism

Szwarc Eryk, Bocewicz Grzegorz, Banaszak Zbigniew, Wikarek Jarosław

Eksploatacja i Niezawodność

|

2019

|

Vol. 21, no. 3

440--450

EN

In order to deal with unexpected events such as employee absenteeism and/or a demand for personnel that is higher or lower than expected, organizations need to adopt proactive and reactive scheduling strategies to protect the personnel roster and to respond to this operational variability, respectively. In this paper, we discuss a proactive approach that exploits the concept of employee substitutability to improve the flexibility of a personnel shift roster to respond to schedule disruptions. With a view to developing a DSS-driven method dedicated to competence allocation planning robust to unexpected staff absenteeism, we present the concept of the so-called robust employee competence structure. A declarative model of the concept allows to find an employee competence structure robust to a given set of disruptions while guaranteeing an admissible personnel allocation to the assumed set of tasks. Since the problem of designing such a robust structure is NP-hard, another goal of the present study is to propose a sufficient condition the fulfilment of which will guarantee the validity of calculations. Potential applications of the proposed solution are discussed using examples.

PL

Funkcjonowanie organizacji w warunkach występowania nieprzewidzianych absencji pracowników i/lub zmieniającego zapotrzebowania na pracowników o określonych kwalifikacjach wymusza działania mające na celu bądź to budowę, odpowiednio przygotowanego zespołu pracowników (dostosowanego do możliwości wystąpienia zidentyfikowanego zakłócenia), bądź też wprowadzania, w trybie online, zmian w przyjętym planie realizacji zadań niwelujących skutki wystąpienia zidentyfikowanego zakłócenia. W pracy rozważane jest pierwsze z ww. działań. Mając na celu opracowanie metody interakcyjnego planowania przydziału zadań przedstawiona została koncepcja struktury kompetencji odpornej na zakłócenia absencji pracowniczej. Wykorzystywany w niej model, umożliwia poszukiwanie struktur kompetencji gwarantujących dostosowanie kompetencji wykonawcy do wymagań danego zadania w sytuacjach występowania zakładanego rodzaju zakłóceń, np. powodowanych absencją pracowników. Z uwagi na fakt, że sprowadzający się do syntezy odpornych struktur kompetencji problem planowania odpornego przydziału kompetencji umożliwiającego substytucję redundantnych kompetencji należy do klasy problemów NP-trudnych, wyznaczane są również warunki wystarczające spełnienie których gwarantuje istnienie jakiejkolwiek poszukiwanej struktury dopuszczalnej. Możliwości praktycznego wykorzystania przedstawianego podejścia zilustrowane zostało na przykładach.

9

UAVS flight routes optimization in changing weather conditions – constraint programming approach

Radzki Grzegorz, Thibbotuwawa Amila, Bocewicz Grzegorz

Applied Computer Science

|

2019

|

Vol. 15, no 3

5--12

EN

The problem of delivering goods in a distribution network is considered in which a fleet of Unmanned Aerial Vehicles (UAV) carries out transport operations. The changing weather conditions in which the transport operations take place and the UAVs energy capacity levels influenced by the weather conditions are taken into account as factors that affect the determination of a collision-free route. The goods must be delivered to the customers in a given time window. Establishing the routes are the focus of this study. Solutions maximizing the level of customer satisfaction are focused and the computational experiments presented in the study show the impact of weather conditions on route determination.