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Determining lower bound on number of vehicle blocks in multi-depot vehicle scheduling problem with mixed fleet covering electric buses

Duda Jerzy, Fierek Szymon, Karkula Marek, Kisielewski Piotr, Puka Radosław, Redmer Adam, Skalna Iwona

Archives of Transport

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2023

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Vol. 65, iss. 1

27--38

EN

Scheduling buses in public transport systems consists in assigning trips to vehicle blocks. To minimize the cost of fuel and environmental impact of public transport, the number of vehicle blocks used should be as small as possible, but sufficient to cover all trips in a timetable. However, when solving real life transportation problems, it is difficult to decide whether the number of vehicle blocks obtained from an algorithm is minimal, unless the actual minimal number is already known, which is rare, or the theoretical lower bound on the number of vehicles has been determined. The lower bound on the number of vehicle blocks is even more important and useful since it can be used both as a parameter that controls the optimization process and as the minimum expected value of the respective optimization criterion. Therefore, methods for determining the lower bound in transportation optimization problems have been studied for decades. However, the existing methods for determining the lower bound on the number of vehicle blocks are very limited and do not take multiple depots or heterogeneous fleet of vehicles into account. In this research, we propose a new practical and effective method to assess the lower bound on the number of vehicle blocks in the Multi-Depot Vehicle Scheduling Problem (MDVSP) with a mixed fleet covering electric vehicles (MDVSP-EV). The considered MDVSP-EV reflects a problem of public transport planning encountered in medium-sized cities. The experimental results obtained for a real public transport system show the great potential of the proposed method in determining the fairly strong lower bound on the number of vehicle blocks. The method can generate an estimated distribution of the number of blocks during the day, which may be helpful, for example, in planning duties and crew scheduling. An important advantage of the proposed method is its low calculation time, which is very important when solving real life transportation problems.

2

Multi-objective optimization model for a multi-depot mixed fleet electric vehicle scheduling problem with real-world constraints

Duda Jerzy, Karkula Marek, Puka Radosław, Skalna Iwona, Fierek Szymon, Redmer Adam, Kisielewski Piotr

Transport Problems

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2022

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T. 17, z. 4

137--149

EN

This paper presents the problem of public transport planning in terms of the optimal use of the available fleet of vehicles and reductions in operational costs and environmental impact. The research takes into account the large fleet of vehicles of various types that are typically found in large cities, including the increasingly widely used electric buses, many depots, and numerous limitations of urban public transport. The mathematical multi-criteria mathematical model formulated in this work considers many important criteria, including technical, economic, and environmental criteria. The preliminary results of the Mixed Integer Linear Programming solver for the proposed model on both theoretical data and real data from urban public transport show the possibility of the practical application of this solver to the transport problems of medium-sized cities with up to two depots, a heterogeneous fleet of vehicles, and up to about 1500 daily timetable trips. Further research directions have been formulated with regard to larger transport systems and new dedicated heuristic algorithms.

3

Input Sequence of Jobs on NEH Algorithm for Permutation Flowshop Scheduling Problem

Puka Radosław, Duda Jerzy, Stawowy Adam

Management and Production Engineering Review

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2022

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Vol. 13, No. 1

32--43

EN

One of the most popular heuristics used to solve the permutation flowshop scheduling problem (PFSP) is the NEH algorithm. The reasons for the NEH popularity are its simplicity, short calculation time, and good-quality approximations of the optimal solution for a wide range of PFSP instances. Since its development, many works have been published analysing various aspects of its performance and proposing its improvements. The NEH algorithm includes, however, one unspecified and unexamined feature that is related to the order of jobs with equal values of total processing time in an initial sequence. We examined this NEH aspect using all instances from Taillard’s and VRF benchmark sets. As presented in this paper, the sorting operation has a significant impact on the results obtained by the NEH algorithm. The reason for this is primarily the input sequence of jobs, but also the sorting algorithm itself. Following this observation, we have proposed two modifications of the original NEH algorithm dealing with sequencing of jobs with equal total processing time. Unfortunately, the simple procedures used did not always give better results than the classical NEH algorithm, which means that the problem of sequencing jobs with equal total processing time needs a smart approach and this is one of the promising directions for further research.

4

Improving N-NEH+ algorithm by using Starting Point method

Puka Radosław, Łamasz Bartosz, Skalna Iwona

Annals of Computer Science and Information Systems

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2022

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Vol. 30

357--361

EN

The N-NEH+ algorithm is one of the most efficient construction algorithms for solving the permutation flow-shop problem with the makespan criterion. It extends the well-known NEH heuristic with the N-list technique. In this paper, we propose the Starting Point (SP) method that employs a new strategy for using the N-list technique. Extensive numerical experiments on the standard set of Taillard's and VRF benchmarks show that the SP method significantly improves the results of the N-NEH+ algorithm.

5

Effect of simultaneous and sequential use of keys on the correctness of entering command strings into devices

Puka Radosław, Łebkowski Piotr

Technologia i Automatyzacja Montażu

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2019

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nr 2

5--9

EN

Controlling the operation of many devices (e.g. machine tools or assembly lines) requires that proper communication is ensured between man and the machine for the purpose of entering appropriate instructions that will control the machine operation. To this end, control panels, among other things, are used to enable the operator to control the device. Such panel may have many various forms; very often they are computer keyboards. The problem of correct entering appropriate instructions at the right moment by the operator certainly has an impact on the quality of the final product. Should the operator make a mistake, the product will not meet the desired requirements. It becomes necessary to design keyboards used as control panels in which the arrangement of characters would facilitate correct entering of instructions. One of the main issues is to define the most effective way, simultaneous or sequential, of using key while entering instructions from the control panel. The study presented in the paper describes the effect of using a combination of keys (i.e. simultaneous use of more than one key in order to enter a signal) in controlling a machine on the correctness of the signals being entered. The results presented were compared with using only the sequential pressing of keys. The study presented in the paper was conducted using a computer keyboard.

PL

Sterowanie działaniem wielu urządzeń (np. obrabiarek, zespołów montażowych) wymaga zapewnienia komunikacji człowieka z maszyną, w celu wprowadzenia do urządzenia odpowiednich instrukcji, które sterować będą działaniem maszyny. W tym celu wykorzystywane są m.in. panele sterownicze, poprzez które operator ma możliwość sterowania urządzeniem. Panele te mogą przyjmować najróżniejsze formy, bardzo często są to klawiatury komputerowe. Problem poprawnego wprowadzania przez operatora odpowiednich instrukcji w odpowiednim momencie ma niewątpliwy wpływ na jakość wytworzonego produktu końcowego. W przypadku popełnienia przez operatora błędu produkt nie będzie spełniać żądanych wymagań. Konieczne staje się projektowanie klawiatur - paneli sterowniczych, w których rozmieszczenie znaków ułatwiałoby prawidłowe wprowadzanie instrukcji. Jednym z głównych zagadnień jest określenie najefektywniejszego sposobu - równoległego lub sekwencyjnego - wykorzystywania przycisków przy wprowadzaniu poleceń z panelu sterującego. Zaprezentowane w artykule badania przedstawiają wpływ wykorzystania w sterowaniu maszyną kombinacji klawiszy (jednoczesnym użyciu więcej niż jednego klawisza w celu wprowadzenia danego sygnału) na poprawność wprowadzanych sygnałów. Przedstawione wyniki zostały porównane z rezultatami przy wykorzystaniu jedynie sekwencyjnego wykorzystania klawiszy. Prezentowane w artykule badania zostały przeprowadzone z wykorzystaniem klawiatury komputerowej.