Mariusz Izdebski

Assessment of the Method Effectiveness for Choosing the Location of Warehouses in the Supply Network

This paper describes the problem of determining the location of warehouses in the logistics network supplying different type of entities with raw materials. Was presented a mathematical model, i.e. were defined decision variables, were specified constraints and objective function that minimizes the total cost of transporting raw materials from suppliers to the recipients. Were included costs of flow of raw materials between network facilities and costs associated with salaries for drivers engaged in the realization of this flow. Was developed a method of determining the location of storage facilities based on genetic algorithm. In order to check the efficiency of the method was proposed algorithm for evaluating its effectiveness.

USE OF COMPUTER ASSISTANCE IN ORDER TO DESIGNATE THE TASKS IN THE MUNICIPAL SERVICES COMPANIES

In this article, the method of designating the tasks in the municipal services companies was described. Presented method consists of three phase: the preparatory phase, the optimization phase and the generated tasks phase. Each phase was characterized. In this paper, the mathematical model of this problem was presented. The function of criterion and the condition on designating the tasks were defined. The minimum route described in the optimization phase was designated by the genetic algorithm. In this paper, the stages of constructing of the genetic algorithm were presented. A structure of the data processed by the algorithm, a function of adaptation, a selection of chromosomes, a crossover, a mutation and an inversion were characterized. A structure of the data was presented as string of natural numbers. In selection process, the roulette method was used and in the crossover, process the operator PMX was presented. The method was verified in programming language C #. The process of verification was divided into two stages. In the first stage, the best parameters of the genetics algorithm were designated. In the second stage, the algorithm was started with these parameters and the result was compared with the random search algorithm. The random search algorithm generates 2000 routes and the best result is compared with the genetic algorithm. The influence of the inversion, the mutation and the crossover on quality of the results was examined.

THE ANT ALGORITHM FOR SOLVING THE ASSIGNMENT OF VEHICLES TO TASKS IN THE MUNICIPAL SERVICES COMPANIES

In this article, the method of designating the assignment vehicles to tasks in the municipal services companies was described. This method consists of two stages, which were discussed. The first stage of the method of designating the assignment relies on determining the minimum route of the assignment, which consists of all the tasks. The second stage of the assignment is the stage of realization the route by the vehicles. In order to allocate the vehicles to tasks a concept of the elementary route was introduced. The problem of the assignment vehicles to tasks in the municipal services companies was characterized. The mathematical formulation of the assignment vehicles to the tasks was presented. The function of criterion determining the minimum route of the assignment was designated. The limit of driving time of a driver, the limit of the working time of a driver, the limit of realization all tasks, the limit of payload of the vehicle were described. The minimum route of the assignment was designated be means of the ant algorithm. The method was verified in programming language C #. The process of verification was divided into two stages. In the first stage, the best parameters of the ant algorithm were designated. In the second stage, the algorithm was started with these parameters and the result was compared with the random search algorithm. The random search algorithm generates 2000 routes and the best result is compared with the genetic algorithm. The influence of the parameters on quality of the results was examined.

The application of genetic algorithm for warehouse location in logistic network

The paper presents a certain approach to solving the problem of warehouse locations based on the application of a genetic algorithm. The main objective is to indicate a location of warehouses from among those that already exist, which are most likely to assure the best value of the adopted criterion function, concurrently meeting recipients’ needs. A formal notation was presented of the mathematical model, allowing for the indispensable data, decisionrelated variables of limitations and the criterion function. The problem is to determine the location of warehouses taking into account minimising costs of transport and storage of forwarded cargo between determined facilities within the network. To allow solving the problem related to warehouse location within the logistics network of a manufacturing enterprise the use of a genetic algorithm was proposed. The structure of the algorithm was adapted to the mathematical model. A genetic algorithm was used to determine the volume of cargo stream flows between particular facilities in the network. To form a genetic algorithm it is advisable to define the chromosome structure, the adaptation function, cross-linking process and mutation. The location problem is solved in such a way that if for any day within the analysed period flows take place from a given warehouse or to a given warehouse, such a logistics facility should constitute an element of the target logistics network. If there are no such flows, no warehouse is necessary in the given location.

Planning International Transport Using the Heuristic Algorithm

The article refers to the problem of planning international transport. The aim of this paper is to develop the algorithm which will be used to planning international transport. Planning international transport problems are the complex decision problems which refer to the vehicle routing problems and the problems of designating the minimal path in the graph. The approach to planning international transport presented in this paper takes into account the delay times in the intermediate points, e.g. cities and average waiting time at the border crossings. In order to determine the international transport routes the mathematical model was developed, i.e. decision variables, constraints and the criterion function. Decision variables take the binary form and determine the connections between the objects in the transportation network which are realized by the vehicles. Constraints take into account the weight limits on the routes and the time realization of the transportation task. The criterion function determines the minimal transportation route in the context the time of its realization. In order to designate the routes in international transport the heuristic algorithm, i.e. ant algorithm was developed. The steps of building this algorithm was presented. This algorithm was verified in the C# programming language. The results generating by the presented algorithm were compared with the results generating by the random algorithm.

The assessment of supply chain effectiveness

This paper presents the problem of the assessment of the supply chains in the context of their effectiveness. In this paper the concepts of a supply chain and effectiveness were characterized. The supply chain is a structure of entities which are connected with each other by the use of material and financial flows and functional, structural, technological, economic and information dependencies. Entities such as: suppliers, final recipients, entrepreneurs, warehouse facilities, supply centers, logistics operators, carriers, etc. perform material flows from suppliers to recipients. The concept of efficiency, in general terms, refers to economic rationality and means the relationship between the achieved or expected effects and the expenditures incurred. Additionally, indicators of measuring the effectiveness of the supply chain were described. In order to assess the effectiveness of the supply chain the decision model was developed. Optimization is crucial in decision support systems. The development of an appropriate model for mapping the behavior of a real object or system and formulating an optimization task is a necessary activity in effective management. This is even more important if we want to be competitive. Along with the development of decision support systems, as well as the development of systems for data acquisition on the system functioning, which feed optimization models in ever more detailed form, complex decision models are created that take into account many optimization criteria and require a large amount of data. It allows, however, to ensure the sustainable development of the system and simultaneous implementation of its basic tasks. The main aim of this paper is to present the stages and assumptions of the model for assessing the effectiveness of the supply chain. The main data input, constraints of the model, the criteria functions were determined.

The Warehouse Location Problem in the Context of Vehicle Routing Problem in the Production Companies

This paper presents warehouse location-routing problem in the logistics network. In order to solve this problem the location model was developed. The limitations and the optimization criterion of the model were determined. The optimization criterion refers to the distance between the facilities of the network. The final location of warehouse facilities was obtained using an ant algorithm. This paper describes the stages of the ant algorithm i.e. the stage of designating the probability of transition of ants to the other points of the route, update pheromone. In this paper the process of calibration of this algorithm was presented. The results of the ant algorithm were compared with the random results.