Wyniki wyszukiwania - Biblioteka Nauki

1

Wybrane aspekty modelu dystrybucji ładunków na obszarach aglomeracji miejskiej z uwzględnieniem danych losowych

100%

Szczepański E.

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tom z. 97

509--518

PL

W artykule przedstawiono koncepcję wielokryterialnego modelu matematycznego systemu dystrybucji na obszarach miejskich, w ujęciu wielokryterialnej optymalizacji z uwzględnieniem danych losowych. Prezentowana koncepcja modelu dotyczy systemów dystrybucji wielostopniowych wykorzystujący Centra Konsolidacji Ładunków i punkty przeładunkowe (HUB). Zdefiniowano elementy systemu istotne z punktu widzenia definiowanego modelu matematycznego. Przedstawiono formalny zapis składowych funkcji kryterium.

EN

Paper presents the construction of a mathematical model of the distribution system in urban areas, including multi-criteria optimization with random data. This model refers to systems based on an multi-stage distribution systems with Cargo Consolidation Centers and transshipment points (HUB). Individual elements of transport network in urban areas were analyzed, which were used to formulate a mathematical model. The article contains the concept of a model urban transport system, including the formal record. Vector criteria function was also presented.

2

Decision support system in freight transport based on vehicle routing problem with quality criterion

100%

Szczepański E. , Jachimowski R. , Żak J.

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tom Vol. 11, iss. 3

49--56

EN

Deliveries planning in transport systems is a complicated task and require taking into account a wide range of factors. Enterprises wanting to propose solutions that meet the clients’ needs and be competitive on the market must prepare their offer based on decision support systems including factors characteristic for the real process. The aim of the article is to present a concept of a decision support system based on a multi-criteria vehicle routing problem in real conditions (Real-World VRP). Taking into account the latest trends in the optimization of the delivery plan, the model includes three criteria - the cost, time and success rate of the delivery plan as a criterion relating to the quality of the delivery plan. Among other assumptions, it should be pointed out that the heterogeneous structure of the rolling stock has been taken into account, the number of which is not limited, the vehicles return to the place of origin. The travel time of the connection and the time of loading operations are random variables. The limited driver’s work time and driving time were also applied. The effect of the work presented in the article is the concept of the decision support system in the freight transport, taking into account the quality criterion of the delivery plan.

3

An attribute based similarity function for VRP decision support

99%

Lokketangen A. , Oppen J. , Oyola J. , Woodruff D. L.

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tom Vol. 6, no. 1-2

65--83

EN

When solving problems in the real world using optimization tools, the model solved by the tools is often only an approximation of the underlying, real, problem. In these circumstances, a decision maker (DM) should consider a diverse set of good solutions, not just an optimal solution as produced using the model. On the other hand, the same DM will only be interested in seeing a few of the alternative solutions, and not the plethora of solutions often produced by modern search techniques. There is thus a need to distinguish between good solutions using the attributes of solutions. We develop a distance function of the type proposed in the Psychology literature by Tversky (1977) for the class of VRP problems. We base our difference on the underlying structure of solutions. A DM is often interested in focusing on a set of solutions fulfilling certain conditions that are of specific importance that day, or in general, like avoiding a certain road due to construction that day. This distance measure can also be used to generate solutions containing these specific classes of attributes, as the normal search process might not supply enough of these interesting solutions. We illustrate the use of the functions in a Multiobjective Decision Support System (DSS) setting, where the DM might want to see the presence (or absence) of certain attributes, and show the importance of identifying solutions not on the Pareto front. Our distance measure can use any attributes of the solutions, not just those defined in the optimization model.

4

Simulation Methods Application for LPG Deliveries Planning and Scheduling to the Network of Stations Under Demand Uncertainty

99%

Karkuła M. , Kaleta J.

Logistics and Transport

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2017

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tom Vol. 34, No. 2

63--78

EN

In our paper we considered the problem of demand uncertainty and its influence on planning and scheduling of LPG deliveries. The experience of specialized transportation company in charge of LPG deliveries for the domestic supplier network under VMI approach was analyzed. High variability of distribution parameters and frequent orders modifications were observed while small stations tanks capacities comparing to high daily LPG sales volumes were considered. The combined use of simulation and optimization methods was proposed for the case of LPG distribution to the petrol stations network. The demand uncertainty at customers' stations was considered. Simulation models were assumed to be efficient for dynamic and robust delivery plans of LPG distribution. The results of computational experiments were presented for different values of coefficient of variation.

5

CLP solution for new variant of VRP

80%

Szklarczyk R.

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tom nr 2(38)

11-15

EN

In the paper a mathematical model of MDMGVRP is presented. The two CLP programs solving above are described and discussed. The new variant of VRP consider certain number of commodities (goods) transported. In classic VRP there is only one commodity. The second main difference to classic problem is limited stock in depots. This two aspects cause the problem more complicated and prevent from direct applying of common known algorithms for solving the MDMGVRP. Two CLP solver tools were used to formulate CLP programs. The first was Cosytec CHIP the other was GNU-Prolog. Finally a demonstration problem is presented and solution is discussed.

PL

W artykule przedstawiono nowy wariant problemu marszrutyzacji pojazdów - MDMGVRP, czyli problem marszrutyzacji pojazdów z wieloma magazynami i wieloma asortymentami. Zagadnienie zostało opisane modelem matematycznym a następnie rozwiązane metodą CLP. Opisano dwa programy wykonane przy użyciu narzędzi CLP: Cosytec CHIP i GNU-Prolog. Na koniec przedstawiono przykładowe dane oraz rozwiązanie uzyskane przy pomocy opisanych programów.

6

Zarządzanie samochodowym taborem ciężarowym – przykłady

57%

Redmer A. , Kiciński M. , Rybak R.

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tom nr 12

23--32

PL

Niniejszy artykuł jest trzecim z cyklu artykułów, jakie autorzy analizują tematykę zarządzania samochodowym taborem ciężarowym. Artykuł ten prezentuje pięć przykładów zastosowania ilościowych (optymalizacyjnych) metod rozwiązywania wybranych problemów zarządzania taborem. W artykule zaprezentowano przykłady rozwiązania następujących problemów: Make or Buy (MOB), liczebność/kompozycja taboru, wymiana taboru, przydział pojazdów do zadań przewozowych oraz marszrutyzacja (ang. vehicle routing problem - VRP). W przypadku każdego z problemów dokonano jego definicji oraz zaprezentowano dane wejściowe i uzyskane rezultaty, w tym rozwiązanie optymalne na tle rozwiązania losowego.

EN

The paper is the third one from the series of three papers that the Authors dedicate to the freight fleet management topic. The paper presents five examples of the application of quantitative (optimization) methods to selected fleet management problems. The following fleet management problems are considered: Make or Buy problem, fleet sizing/composition problem, vehicle replacement problem, assignment of vehicles to transportation tusks, and the VRP. All the selected problems are carefully defined. Moreover, input and output data (obtained solutions) are presented, including optimal solutions compared to random ones.