In recent years, researchers have been developing solutions to reduce our energy consumption by optimizing existing systems in different ways. Indeed, it is not enough just to create or use renewable energies but we must also not waste the available energy. This and systems are developed to recover unused energy of human body movement, which will be used to power either the equipment itself or another.
This paper proposes a pressure-type generator that collects human mechanical energy by stepping, a prototype is already designed and manufactured. The average output voltage can reach to 20.9 V by step for F = 100N,and finally, we did a series of tests to prove that the device can have great power output performance in the low frequency environment of the human foot movement.
Marine energies are a strategic channel for renewable energies to diversify and complement the global energy mix. From this perspective, several researches have seen the light in order to allow the maximum exploitation possible of the energy estimated at 80,000 TWh/year, presenting multiple vacant possibilities concerning energy not yet exploited on a large scale. The purpose of this paper is the use of ocean vibratory energy coupling with a smart composite material in order to harvest the maximum power. This study will be devoted to the design, modeling, and simulation of a floating harvester energy system that combines the mechanical strength and flexibility of polymer with the high piezo and pyroelectric activities of ceramic. The harvester system is composed of a mass-spring system used to transfer wave movements to mechanical vibrations, and two piezoelectric lever devices will be used to amplify and convert the harvested mechanical vibration into electrical power. With this flexible device, the maximum power harvested is 56.45 μW/mm², using PU/PZT composite with the optimal resistance of 108 MΩ. Considering these results, this system can be used in very different ways in marine applications.
We study the existence of solutions for random system of fractional differential equations with boundary nonlocal initial conditions. Our approach is based on random fixed point principles of Schaefer and Perov, combined with a vector approach that uses matrices that converge to zero. We prove existence and uniqueness results for these systems. Some examples are presented to illustrate the theory.
Lead zirconate titanate (PZT) is the most common piezoelectric ceramic and exhibits excellent electromechanical conversion properties. But in order to make it more adaptable for energy harvesting applications, we resort to ceramic/polymer composites because of their excellent and tailorable properties. The advantages of this type of composite are high coupling factors due to PZT, mechanical flexibility (PU) and wide bandwidth. In this work, we studied the mechanical and electrical characteristics of this composite, as well as their behavior as a function of the percentage of PZT (by volume). Forth more, we followed the impact of this parameter on the collected energies, as well as others like frequency and resistance. The harvested power significantly increases with increasing PZT, achieving a power value up to 13.4 and 420 nW for PU/PZT 60% and PU/PZT 70%, respectively. In conclusion, composite piezoelectric films have great potential from an energy density viewpoint and could represent interesting candidates for energy harvesting applications.
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