The work deals with the issue of assigning vehicles to tasks in transport companies, taking into account the minimization of the risk of dangerous events on the route of vehicles performing the assigned transport tasks. The proposed risk management procedure based on a heuristic algorithm reduces the risk to a minimum. The ant algorithm reduces it in the event of exceeding the limit, which differs from the classic methods of risk management, which are dedicated only to risk assessment. A decision model has been developed for risk management. The decision model considers the limitations typical of the classic model of assigning vehicles to tasks, e.g. window limits and additionally contains limitations on the acceptable risk on the route of vehicles' travel. The criterion function minimizes the probability of an accident occurring along the entire assignment route. The probability of the occurrence of dangerous events on the routes of vehicles was determined based on known theoretical distributions. The random variable of the distributions was defined as the moment of the vehicle's appearance at a given route point. Theoretical probability distributions were determined based on empirical data using the STATISTICA 13 package. The decision model takes into account such constraints as the time of task completion and limiting the acceptable risk. The criterion function minimizes the probability of dangerous events occurring in the routes of vehicles. The ant algorithm has been validated on accurate input data. The proposed ant algorithm was 95% effective in assessing the risk of adverse events in assigning vehicles to tasks. The algorithm was run 100 times. The designated routes were compared with the actual hours of the accident at the bottom of the measurement points. The graphical interpretation of the results is shown in the PTV Visum software. Verification of the algorithm confirmed its effectiveness. The work presents the process of building the algorithm along with its calibration.
In the article, traffic safety management on the apron comes down to determining appropriate routes for ground handling vehicles to avoid collision situations with aircraft. The route search problem is a decision problem, so different optimization algorithms are used to solve it. Bearing in mind the growing importance of heuristic algorithms in the effectiveness of solving complex decision problems, the authors of this study analyzed the possibility of using the ant algorithm to determine the driving routes of ground service vehicles. As part of the research, the decision model of traffic safety management on the apron was presented.
PL
W artykule zarządzanie bezpieczeństwem ruchu na płycie lotniska sprowadza się do wyznaczenia odpowiednich tras jazdy pojazdów obsługi naziemnej w celu uniknięcia sytuacji kolizyjnych ze statkami powietrznymi. Problem wyszukiwania tras jest problemem decyzyjnym, więc w celu jego rozwiązania stosowane są różne algorytmy optymalizacyjne. Mając na uwadze rosnące znaczenie algorytmów heurystycznych w efektywności rozwiązywania złożonych problemów decyzyjnych, autorzy niniejszego opracowania przeanalizowali możliwość zastosowania do wyznaczenia tras jazdy pojazdów obsługi naziemnej algorytmu mrówkowego. W ramach realizacji badań przedstawiono model decyzyjny zarządzania bezpieczeństwem ruchu na płycie lotniska.
The article presents a method of selecting a fleet of vehicles with a homogeneous structure for tasks based on the statistical characteristics of their operational parameters. The selection of a vehicle fleet for tasks is one of the stages of vehicle fleet management in transport companies. The selection of a vehicle fleet for tasks has been defined as the allocation of a vehicle model to a given company, which is associated with the unification of the vehicle fleet to one specific type. The problem of selecting a fleet of vehicles has been presented in a multi-criteria approach. The operational parameters assessing the selection of vehicles for the tasks are mileage and the number of days to the first and subsequent failure, and vehicle maintenance costs. The developed method of selecting a fleet of vehicles for the tasks consists of two stages. In the first stage, the average operating parameter values are determined using statistical inference. In the second stage, using the MAJA method, a unified model of the fleet of vehicles operating in the enterprise is established.
The aim of the article is to develop a model for assessing the safety of children’s travel. Safety is the most important indicator describing the mobility system of children, even more important than the costs of operating it. Due to the dynamic development of intelligent solutions, it is possible to undertake additional activities supporting the improvement of children’s safety when traveling to and from school. However, their implementation requires an adequate assessment of a children’s mobility system. Currently, there are no solutions that could comprehensively support the decision-making process in this sphere. The article presents the issues of children’s mobility, a literature review in this area, mathematical model for assessing school bus travel, and a computational example. The presented approach is an original solution allowing for evaluation of the existing systems and their development scenarios. In addition, it enables the comparison of children mobility systems of different complexity and scale.
The aim of this article is to assess the risk of performance of rail freight transport on the basis of an analysis of identified risk areas based on statistical data on the causes of accidents that occurred on the lines of railway transport in Poland. A critical review of selected scientific studies relating to the risk assessment process for identified areas of the railway system has been undertaken. Based on statistical data, the authors analysed the causes of accidents on railway lines in 2019 in Poland and determined the probability of occurrence of a given cause. In addition, the article calculates the probability of vehicle delays for different emergency situations occurring in the performance of rail freight transport operations. This enabled the authors of the article to carry out a risk assessment of freight train delays on railway lines.
The aim of the article was to develop a tool to support the process of planning and managing aircraft (ac) maintenance. Aircraft maintenance management has been presented for scheduled technical inspections resulting from manufacturers’ technical documentation for ac. The authors defined the problem under investigation in the form of a four-phase decisionmaking process taking into account assignment of aircraft to airports and maintenance stations, assignment of crew to maintenance points, setting the schedules, i.e. working days on which aircraft are directed to maintenance facilities. This approach to the planning and management of aircraft maintenance is a new approach, unprecedented in the literature. The authors have developed a mathematical model for aircraft maintenance planning and management in a multi-criteria approach and an optimisation tool based on the operation of a genetic algorithm. To solve the problem, a genetic algorithm was proposed. The individual steps of the algorithm construction were discussed and its effectiveness was verified using real data.
The purpose of this paper is to evaluate the efficiency of airport processes using simulation tools. A critical review of selected scientific studies relating to the performance of airport processes with respect to reliability, particularly within the apron, has been undertaken. The developed decision-making model evaluates the efficiency of airport processes in terms of minimizing penalties associated with aircraft landing before or after the scheduled landing time. The model takes into account, among other things, aircraft take-offs and landings and separation times between successive aircraft. In order to be able to verify the correctness of the decision-making model, a simulation tool was developed to support decision making in the implementation of airport operations based on a genetic algorithm. A novel development of the structure of a genetic algorithm as well as crossover and mutation operators adapted to the determination of aircraft movement routes on the apron is presented. The developed simulation tool was verified on real input data.
This paper presents decision problems which occur in designing database architecture for the assessment of logistics services. In the work, it was emphasized that the key stages in database design is to define a database model comprising a set of rules that characterize the structure of data in the database and a list of operations that can be performed on the data entered into the database. Research presented in the article is conducted as part of the project on the European Portal of Logistics Services (EPLOS) implemented on the basis of an agreement with the National Center for Research and Development under the EUREKA program. As part of the research carried out as part of the project, the principles of functioning of distributed architecture were developed and evaluated for the services offered by carriers or logistics operators operating on the international market. These include operators providing air services, international road, intermodal, sea transports, etc. The article indicates that the purpose of the database responsible for processing information in cargo intermodal connections is not only to collect input data on aviation and road infrastructure, but also to save the results generated by computational modules. At work, the modular database structure for assessing logistics services consisting of among others from dynamic data module, archive module, data entry module, optimization algorithm calibration module was proposed. Catalog structure and rules for supplying the database with data on the example of a railway operator were presented in detail.
W artykule opisano zastosowanie algorytmu mrówkowego w wyznaczaniu przydziału pojazdów do zadań w transporcie zbiorowym. Analizowany problem przydziału jest złożonym zagadnieniem optymalizacyjnym, klasyfikującym go do problemów NP-trudnych. W obszarze dotyczącym zagadnień miejskiego transportu zbiorowego jest podstawowym problemem, który należy rozwiązać w procesie konstruowania rozkładów jazdy oraz planów pracy pojazdów i kierowców. Celem niniejszej publikacji było opracowanie nowego narzędzia optymalizacyjnego adekwatnego do analizowanego zagadnienia przydziału pojazdów do zadań w komunikacji miejskiej. Przedstawiony algorytm mrówkowy jest nowym podejściem zastosowanym do rozwiązywania zagadnień przydziału w transporcie zbiorowym i stanowi podstawę do dalszych badań nad tematyką opracowywania nowych metod optymalizacyjnych w badanym problemie. Opracowany algorytm minimalizuje liczbę pojazdów przy jednoczesnej minimalizacji czasu pracy oraz przebytej drogi przez wykorzystane pojazdy. Opracowano model matematyczny zagadnienia przydziału pojazdów do zadań w transporcie publicznym, tj. zdefiniowano zmienne decyzyjne, ograniczenia oraz funkcje kryterium. Ograniczenia przydziału wynikają z czasu realizacji kursów w danym dniu roboczym, ograniczeń prawnych w zakresie czasu pracy i jazdy kierowcy, a także dostępnej liczy pojazdów. Problem został przedstawiony w aspekcie wielokryterialnym, gdzie decydujące znaczenie w ocenie efektywnego przydziału mają czas i dystans pokonany przez wszystkie pojazdy realizujące zlecone zadania. W artykule przedstawiono ogólną koncepcję algorytmu mrówkowego, która jest w trakcie procesu weryfikacji na danych teoretycznych i rzeczywistych bazach danych przedsiębiorstw komunikacji miejskiej.
EN
The article describes the application of the ant algorithm in the problem of vehicle allocation to tasks in public transport. The analyzed allocation problem is a complex optimization problem that classifies it as NP-difficult. In the area of public transport issues it is a basic problem that should be solved in the process of constructing timetables and work plans for vehicles and drivers. The purpose of this publication was to develop a new optimization tool adequate to the analyzed issue of the allocation of vehicles to tasks in public transport. The presented ant algorithm is a new approach used to solve allocation issues in public transport and is the basis for further research on the development of new optimization methods in the studied problem. The developed algorithm minimizes the number of vehicles while minimizing working time and the distance traveled by the operating vehicles. A mathematical model has been developed on the issue of allocation of vehicles in public transport, i.e. decision variables, constraints and criterion functions were defined. The restrictions on the allocation result from the duration of the courses on a given business day, legal restrictions on the driver’s working time and driving time, as well as the available number of vehicles. The problem was presented in a multi-criteria aspect, where the decisive factor in assessing the effective allocation is the time and distance covered by all vehicles carrying out the assigned tasks. The article presents the general concept of the ant algorithm, which is in the process of verification on theoretical data and real databases of public transport companies.
The article presents an approach to assessing the reliability of logistics processes implemented in supply chains in terms of time losses resulting from the selection of a variant of material flows in the supply chain. In order to define this indicator, a mathematical model of the supply chain has been developed, i.e. the parameters of the research problem, the decision variables, the constraints and the evaluation criteria. The method of evaluating the reliability of the system is presented in diagram form. The algorithm was verified based on experimental data. In order to evaluate the reliability of the logistic processes for the sample supply chain, a simulation model was developed that determines the time losses in the points and linear elements of the examined chain. Time losses are dictated by traffic delays resulting from traffic congestion on particular sections of the route and road junctions and delays in point elements in the supply chain.
PL
W artykule przedstawiono podejście do oceny niezawodności procesów logistycznych realizowanych w łańcuchach dostaw w aspekcie strat czasu wynikających z wyboru wariantu realizacji przepływów materiałowych w łańcuchu dostaw. Na potrzeby tych badań opracowano model matematyczny łańcucha dostaw, tj. określono parametry problemu badawczego, zmienne decyzyjne, ograniczenia oraz kryteria oceny. Sposób oceny niezawodności systemu został przedstawiony w postaci schematu. Algorytm został zweryfikowany na podstawie danych eksperymentalnych. W celu oceny niezawodności procesów logistycznych dla przykładowego łańcucha dostaw opracowano model symulacyjny wyznaczający straty czasu w elementach punktowych i liniowych badanego łańcucha. Straty czasu podyktowane są opóźnieniami w ruchu drogowym wynikającymi z kongestii ruchu na poszczególnych odcinkach trasy i węzłach drogowych oraz opóźnieniami w elementach punktowych łańcucha dostaw.
The facility location problem is a popular issue in the literature. The current development of world economies and globalization of the market requires continuous improvement of methods and research in this field. The location of the object determines the time of transport, affects the operational costs of the supply chain, and determines the possible amount of inventory or minimum inventory levels. These are critical issues from the point of view of designing an effective logistics system. The degree of complexity of current decision-making problems requires the construction of mathematical models and support for the decision-maker by optimization and simulation methods. A comprehensive and systemic approach to the problem allows the effective planning of supply chains. The purpose of this article was to study the sensitivity of the warehouse location problem in the supply chain. The solution was obtained based on the methodology developed under the SIMMAG3D project. The article presents the characteristics of the issue of the location of warehouse objects, the mathematical formulation of the solved problem of location and the method of its solution based on the heuristic algorithm using the modification of the Busacker-Gowen method. Then, a supply chain simulation model was developed in the FLEXSIM environment and scenario studies were performed for various input data and model parameters. The analysis and assessment of the solution based on parameters such as utilization of the potential of warehouse objects object were presented. Random change in demand described by Erlang distribution and normal distribution was considered. The analysis showed how the selection of a statistical distribution to describe the input data can affect the shape of the logistics system. The article ends with a summary of considerations and a plan for further research in the use of the simulation environment to support the decision-making process of the location of storage facilities and the functioning of supply chains.
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