Design and analysis of vibration energy harvesters based on peak response statistics

Energy harvesting using cantilever piezoelectric vibration energy harvesters excited by Gaussian broadband random base excitation is considered. The optimal design and analysis of energy harvesters under random excitation is normally performed using the mean and standard deviation of a response quantity of interest, such as the voltage. An alternative approach based on the statistics of the peak voltage is developed in this paper. Three extreme response characteristics, namely (a) level crossing, (b) response peaks above certain level, and (c) fractional time spend above a certain level, have been employed. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions have been derived for number of level crossings, statistics of response peaks and fractional time spend above a certain level for the output voltage. It is shown that these quantities can be related to the standard deviation of the voltage and its derivative with respect to time. Direct numerical simulation has been used to validate the analytical expressions. Based on the analytical results, closed-form expressions for optimal system parameters have been proposed. Numerical examples are given to illustrate the applicability of the analytical results

MEMS Technologies for Energy Harvesting

The objective of this chapter is to introduce the technology of Microelectromechanical Systems, MEMS, and their application to emerging energy harvesting devices. The chapter begins with a general introduction to the most common MEMS fabrication processes. This is followed with a survey of design mechanisms implemented in MEMS energy harvesters to provide nonlinear mechanical actuations. Mechanisms to produce bistable potential will be studied, such as introducing fixed magnets, buckling of beams or using slightly slanted clamped-clamped beams. Other nonlinear mechanisms are studied such as impact energy transfer, or the design of nonlinear springs. Finally, due to their importance in the field of MEMS and their application to energy harvesters, an introduction to actuation using piezoelectric materials is given. Examples of energy harvesters found in the literature using this actuation principle are also presented

Porous ferroelectrics for energy harvesting applications

This paper provides an overview of energy harvesting using ferroelectric materials, with a particular focus on the energy harvesting capabilities of porous ferroelectric ceramics for both piezo- and pyroelectric harvesting. The benefits of introducing porosity into ferro- electrics such as lead zirconate titanate (PZT) has been known for over 30 years, but the potential advantages for energy harvesting from both ambient vibrations and temperature fluctuations have not been studied in depth. The article briefly discusses piezoelectric and pyro- electric energy harvesting, before evaluating the potential benefits of porous materials for increasing energy harvesting figures of merits and electromechanical/electrothermal coupling factors. Established processing routes are evaluated in terms of the final porous structure and the resulting effects on the electrical, thermal and mechanical properties

Kincheloe, Joe L., Shirley R. Steinberg, Nelson M. Rodriquez, and Ronald E. Chennault, eds., White Reign: Deploying Whiteness in America. New York: St. Martin\u27s Press, 1998.

Gives theoretical, critical, and practical treatment to issues of white domination of U.S. identity, ideology, and institutions

Electrical insulation properties of RF-sputtered LiPON layers towards electrochemical stability of lithium batteries

Electrochemical stability, moderate ionic conductivity and low electronic conductivity make the lithium phosphorous oxynitride (LiPON) electrolyte suitable for micro and nanoscale lithium batteries. The electrical and electrochemical properties of thin-film electrolytes can seriously compromise full battery performance. Here, radio-frequency (RF)-sputtered LiPON thin films were fabricated in nitrogen plasma under different working pressure conditions. With a slight decrease in the deposition pressure from 6 to 1 × 10−3 mbar, the 600 nm thick LiPON film reveals an electric resistivity increase from 108 to 1010 Ω · cm, respectively. UV– micro-Raman spectroscopy confirms the nitrogen incorporation on the Li3PO4 material, while scanning electron microscopy, Rutherford backscattering spectrometry and nuclear reaction analysis show a well-defined compact structure with a composition of Li2.2PO2.2N0.6 for the higher electrical-resistivity film. An ionic conductivity close to 3 × 10−7 S cm−1 at room temperature (22 °C) was measured by AC impedance spectroscopy. Thermal properties were investigated through the differential scanning calorimetry technique. LiPON films reveal high optical transmission (>75%) in the UV–vis range, which could be interesting for transparent electronic devices.This work is supported by FCT with project reference UID/ EEA/04436/2013, by FEDER funds through the COMPETE 2020–Programa Operacional Competitividade e Internacionalização (POCI) with project reference POCI-01-0145- FEDER-006941, by the UID/FIS/50010/2013 project and by the strategic project PEST–C/QUI/UI0686/2013. EMFV is grateful for financial support through FCT grant SFRH/ BPD/95905/2013. NPB gratefully acknowledges FCT support through the UID/Multi/04349/2013 project. MRC acknowledges the funding provided by FEDER through the COMPETE 2020 Programme and National Funds through FCT–Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013 and RECI-II/ FIS-NAN/0183/2012 (FCOMP-01-0124-FEDER-027494).info:eu-repo/semantics/publishedVersio