Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under nonhomogeneous solar irradiation using Series-Parallel (SP) topology. In the first part of the paper, the authors propose a method containing two key points: a switching matrix to change the connection of PV panels based on SP topology; the demonstration that the SP-based reconfiguration method can increase the efficiency of the photovoltaic system up to 50%. In the second part, the authors propose the extension of the method proposed in the first part to improve the efficiency of large solar generation systems by means of a two-levels architecture to minimize the cost of fabrication of the switching matrix.

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Objective: To develope a scale of the factors influencing the decision to purchase vitamin and mineral for children among mothers and assess the impact of them on the purchasing decision. Subjects and methods of research: The study was conducted randomly on the mothers having children under 6 years old at some pharmacies in Hue city. To evaluate results through measurement and analysis methods. Results: The new scale was constructed with 22 observed variables. Four independent factors that influence purchasing decisions are medical staff, product, knowledge and society in descending order; explained by 51.10% of the variation in purchasing decision among mothers. In addition, differences in the number of children every family, the mother’s education and the child’s anorexia are also related to the purchasing decision. Conclusion: A new scale of factors influencing purchasing decision has been developed. Medical staff was the most important factor of purchasing decision among mothers. Key words: purchasing decision, vitamin and mineral supplement (vitamin and mineral).