Hi, I have to make a report on an energy harvesting system using piezolectric materials by comparing two methods each other which are: the standard technique (rectifier bridge+filtering capacitance) and the nonlinear technique, by adding to the standard device a switch and an inductor in parallel of the piezoelectric element (SSHI technique) to optimize the electromechanical conversion. According to the different articles, the nonlinear technique is very efficient in weak coupling (constant displacement amplitude) but not for larger electromechanical coupling factors due to a damping effect caused by the SSHI technique. What is concretly the damping effect ? why it doesn't occur using the standard technique ? I know that the electromechanical coupling factor is low for weakly coupled structure and high for strongly coupled strucutre but i don't understand what it physically means. How can we obtain these two types of structures in laboratory ? Thanks.