As a consumer, you can use cards for payment more or less everywhere you go, however, it is not certain that the card can be used for all purchases. When a customer pays with card there arises a card transaction fee charged to the merchant. This is a big problem for businesses where transactions with small amounts are a large portion of sales. An observation at the beginning of this study showed that seemingly similar merchants have chosen to solve this problem in different ways. Some merchant’s refuses card purchases below a certain amount, while others accept card with any purchase. This study aims to create understanding why there is a difference between these merchants. Fifteen different merchants in kiosks, shops, cafes and convenience stores were interviewed. To analyze the collected data the investigator’s used “The Balanced Scorecard”. The model’s purpose is to illustrate a way of thinking of performance management and which factors are of importance. The responses from the interviews were categorized into “The Balanced Scorecards” four perspectives in order to see differences, similarities and patterns. The survey shows two distinct patterns. The six merchants who chosen not to have a threshold for card payments says that service towards the customers is the most important factor behind the decision. These merchants are aware that some purchases are unprofitable but they see a better financial result in future if their customers are satisfied. All of the other nine merchants who have a threshold indicate financial motives as a basis for their decisions. These merchants are more likely to see the effect to the individual transaction in which the nonprofitability of each purchase gives an inferior total result and therefore should be avoided.

This dissertation investigates in which conditions the optimal configuration of an electric power network is a minimum length spanning tree, and in which conditions it is shortest path tree configuration. For this purpose the dissertation, it applies computational optimization mathematical models of an optimal local access network design problem. The focus of the study is the 13.8 kV spacer cable primary radial networks. Applied models seek for the balance betweenfixedcostsandvariablecosts.Savedvaluesfromanoptimalnetworkcouldbeapplied to increase the range of the network and people reached as well. The bibliographic research is compound by three parts: graph theory, local access network optimization models, and distribution network costs. Research methodology includes the choice of the distribution system, determination of fixed and variable costs, choice and implementation of the local access network optimization models, tests in hypothetical and realistic systems by using the CPLEX solver, analysis of the resulting configuration, and construction of graphics to facilitate the results evaluation. It was found that the relationship between fixed costs and variable costs influences the optimal configuration of the distribution network in such a way that a low value of the quotient between fixed costs and variable costs contributes to a shortest path tree. On the other hand, a high quotient between fixed costs and variable costs contributes to a minimum length spanning tree configuration. However, others parameters must be considered to determine the network configuration such as extension, arches demand and quantity of arches. / O presente trabalho visa investigar sob quais condições a configuração ótima de uma rede de distribuição elétrica é uma árvore geradora mínima (AGM) e sob quais é uma árvore de caminhos mínimos (ACM). Utilizando, para isso, modelos matemáticos computacionais de otimização topológica de redes de utilidade pública. As redes de distribuição estudadas foram do tipo aérea radial primária protegida (ARPP) com nível de tensão em 13,8 kV. Os modelos utilizados prezam pelo equilíbrio entre o custo de investimento inicial (fixo) e os custos decorrentes da transferência de energia elétrica (variável). Os valores economizados através de uma configuração ótima da rede podem ser convertidos em investimentos para aumentar o número de pessoas com acesso aos recursos energéticos com eficiência e qualidade. A revisão bibliográfica foi dividida em três partes: teoria dos grafos, modelos de otimização de redes de acesso local e custos de redes de distribuição. A metodologia utilizada compreendeu as seguintes etapas: escolha do tipo de sistema de distribuição, determinação dos custos fixo e variável, escolha e implementação (GAMS) dos modelos, testes com exemplos de redes usando o solver CPLEX, análise das configurações resultantes e elaboração de gráficos para facilitar a avaliação dos resultados. Os resultados mostraram que a relação entre o custo fixo β e o custo variável γ exerce influência determinante na configuração ótima de uma rede de distribuição ARPP. Um valor baixo de β/γ, favorece a ACM. Já valores elevados de β/γ, conduzem a solução para uma AGM. No entanto, essa relação não é o único fator que determina a configuração da rede, outros parâmetros como extensão, demanda dos nós e quantidade de possíveis arcos influenciam de forma significativa na solução apresentada.

The aim of this thesis is to design the water-cooling system for a synchronous motor with an output of 10kW. The power loss was analytically determinated. For the initial water-cooling system and for two design proposals, thermal models were calculated in Ansys. The same boundary conditions were set for all three models. Then the analysis results of the temperature distribution on the machine surface and in the slots were compared. The comparison also includes the economical cost of the production and service of the machine. Then the production documentation was created, consisting of the assembly drawings and a simplified technological process.