A piezoelectric energy harvester generator is a device capable of transforming environmental mechanical energy into electrical energy. The piezoelectric electromechanical parameters determine the maximum electrical power which is able to be transferred to an electric load. In this research work, an exhaustive study of the electromechanical parameters related to the piezoelectric material is carried out, modeling them as components of an electrical circuit, in order to analyze their influence on the transmitted power. On the other hand, some electrical loads are simulated to determine different matrix scenarios for a model developed by state-space equations in the Laplace transform domain. The results obtained have allowed to know how the piezoelectric material properties and mechanical characteristics influence the electrical power output of the energy harvester generator and the energy transmission behavior for different electric loads. The conclusions show how the different electromechanical parameters are related to each other, and how their combination transforms the mechanical environmental energy into the required electrical energy. The novelty of this research is the presentation of a model capable of obtaining the optimized working point of the harvester, taking into account not only the electric loads and current demands but also the piezoelectric material parameters.

Nowadays, the energy consumption of machines is becoming increasingly important in production areas. This is mainly due to rising energy costs, but sustainability and energy savings also play an important role. This article aims to carry out a study on the energy efficiency of machine tools through the acquisition of energy data in real time. The proposed methodology is based on Patterson's definition of energy efficiency to analyse the energy consumption of the tools and evaluate its possible improvement through the development of productive, economic and environmental indicators. As a result of this study, the methodology developed is implemented in a machine tool for which the visualisation of these indicators is obtained in real time so that they can be used to help in decision-making to improve the energy efficiency of the tool. In short, this research seeks to provide a solution to one of the great challenges facing industry today due to the increase in energy costs, which is directly reflected in the cost of manufacturing.