Design And Characterization On Piezoelectric Cantilever As A Self-Powered Accelerometer

Piezoelectric cantilever working on direct piezoelectric effect has shown promising applications as a sensor as well as a micro-power generator depending on the amount of stress that is applied on the piezoelectric material at different range of frequencies. In this research, a self-powered accelerometer that consists of a wide-band energy harvesting power generator, a low operating frequency device acceleration sensor, and a signal conditioning circuit is designed. Piezoelectric cantilevers are being used in this research as a sensor to measure the vibration acceleration level and at the same time as a generator to power up the amplifier circuit. This research includes characterize the frequency response of the piezoelectric cantilever by altering its effective mass and length, design the selfpowered accelerometer system, and lastly verify the output of the self-powered system with battery powered system. The result shows that increasing the effective mass of the cantilever can reduce the resonant frequency of the cantilever, while reducing the effective length of the cantilever would increase the resonant frequency. The designed self-powered accelerometer is able to operate at broadened operating frequency range of 180-310 Hz with acceleration level of not lower than 0.8-g and is able to produce linear output with a sensitivity of 231.28mV/g-level. The piezoelectric generator is able to produced constant voltage output of 1.8V and power output not less than 80μW at operating condition. While for the sensor, signal is successfully amplified at a factor of 3.2 with error deviation less than 15%. The overall result is verified and shows good agreement of 5% error with conventional battery powered accelerometer system and compatible with standard vibration source

Broadband Energy Harvesting using Multi-Cantilever based Piezoelectric

Wideband energy harvesting is essential particularly for extracting electrical energy from ambient vibration which is random. Researches show that the frequency bandwidth of the harvested energy can be effectively enhanced by using multiple cantilevers with different resonant frequencies connecting together. This paper investigates the effect of the different electrical configurations towards the output of the piezoelectric array. An array of four similar piezoelectric cantilevers was mounted side-by-side to operate as a system in generating electrical output across frequencies range up to 500 Hz. The resonant frequency of each of the cantilever was varied by introducing a proof mass of 0.15g, 0.50g and 1.00g at the tip of the cantilever. The result shows improvement in the frequency bandwidth of the piezoelectric array, where it is widened to 150 Hz with improved gap when connected in alternating polarities configurations. The piezoelectric array produces higher voltage when connecting in series configuration; but higher power when connecting in parallel configuration

Demonstration of Self-Powered Accelerometer Using Piezoelectric Micro-Power Generator

This paper demonstrates the operation of a self-power vibration measurement system. A piezoelectric material in the form of a cantilever is being used as a generator which harvest energy from ambient vibration source and transform into useful electrical output. The vibration sources is measured with a MEMS based accelerometer, which is powered up by the transformation of electrical energy derived from the mechanical vibration source itself. It has shown that at a resonant frequency of 78 Hz with an acceleration level of 1g (9.81 m/s2), the piezoelectric generator is able to produce rms output voltage of 5.20 V and successfully operating ADXL335 with the assistance of energy harvesting conditioning IC, LTC3588-1 equipped with rectifying as well as DC-to-DC step-down functions

Investigation On Phase Shifting Effect On The Voltage Output Of Piezoelectric Cantilever Array

This paper analyses the phase shifting of the output waveform produced by piezoelectric cantilevers under a range of vibration frequencies. The phase shift of four piezoelectric cantilevers with different resonant frequency are inspected while it is excited with the vibration from the electrodynamics shaker at a range of frequencies from 100 Hz to 500 Hz with the acceleration level (g-force) fixed at constant magnitude of 1g-level (9.81 m/s2). Time different and Lissajous pattern methods were used in this research to measure the phase shift of the output waveform. Both methods show similar result where the major phase shift happened at the resonant frequency of respective cantilevers. The phase difference remains low around 0 degrees or in other term in phase before the resonant frequency of the cantilever. When the frequency of the vibration source approaches the resonant frequency of respective cantilever, the phase different start to increase rapidly and reach 180 degree which is out of phase after the resonant frequency. This major phase shifting contributes to the significant rise of the gap in between the peaks formed when multiple piezoelectric cantilevers are connected together. As a result, it indirectly improves the output performance of the piezoelectric cantilevers array

Parametric Studies on Resonance Frequency Variation for Piezoelectric Energy Harvesting With Varying Proof Mass and Cantilever Length

This paper demonstrates the potential of the resonance frequency for a piezoelectric beam clamped on one of its end to be altered to a higher or lower range by introducing additional proof mass or by reducing the piezoelectric cantilever length. When the effective mass of the cantilever is increased, the resonance frequency of the cantilever is expected to shift to lower region, while when the stiffness of the cantilever is increased, the resonance frequency of the cantilever is expected to shift to higher region. These statements have been proven and validated in this paper. Overall, the experimental result showed good agreement with the theoretical result, however, there was still 20% and 35% error different for the proof mass experiment and length reduction experiment respectively

Power Optimization Configuration For Piezoelectric Cantilever Arrays

This paper investigates the changes in the output of the piezoelectric cantilever arrays when connected in different configurations. In this research matching load resistance determined and optimum output was measured by connecting the piezoelectric cantilever arrays to resistance ranging from 10 Ω to 1 MΩ while excited by constant vibration source at frequency of 300 Hz and acceleration of 1-g level. The result shows that matching load resistance for one single piezoelectric cantilever is 13 KΩ. When two, three and four cantilevers are connected in series, the matching load resistance is 26 kΩ, 39 kΩ and 52 kΩ respectively. While in parallel connection, matching load resistance reduced to 6.5 kΩ, 4.5 kΩ and 3.5 kΩ for two, three, and four connected cantilevers respectively. In series configuration, the voltage output produced is much higher as compared to the piezoelectric cantilever arrays that are connected in parallel connection. The voltage output of the piezoelectric cantilever increased from 3.41V to 6.09V when it is connected in series configuration with same polarity. Whereas in term of power output, piezoelectric cantilever arrays in parallel configuration produce higher power output as compared to piezoelectric cantilever arrays in series connection. The maximum power increased from 272μW to 521μW when two cantilevers are connected in parallel configuration with same polarity

The trans-ancestral genomic architecture of glycemic traits

Glycemic traits are used to diagnose and monitor type 2 diabetes and cardiometabolic health. To date, most genetic studies of glycemic traits have focused on individuals of European ancestry. Here we aggregated genome-wide association studies comprising up to 281,416 individuals without diabetes (30% non-European ancestry) for whom fasting glucose, 2-h glucose after an oral glucose challenge, glycated hemoglobin and fasting insulin data were available. Trans-ancestry and single-ancestry meta-analyses identified 242 loci (99 novel; P < 5 x 10(-8)), 80% of which had no significant evidence of between-ancestry heterogeneity. Analyses restricted to individuals of European ancestry with equivalent sample size would have led to 24 fewer new loci. Compared with single-ancestry analyses, equivalent-sized trans-ancestry fine-mapping reduced the number of estimated variants in 99% credible sets by a median of 37.5%. Genomic-feature, gene-expression and gene-set analyses revealed distinct biological signatures for each trait, highlighting different underlying biological pathways. Our results increase our understanding of diabetes pathophysiology by using trans-ancestry studies for improved power and resolution. A trans-ancestry meta-analysis of GWAS of glycemic traits in up to 281,416 individuals identifies 99 novel loci, of which one quarter was found due to the multi-ancestry approach, which also improves fine-mapping of credible variant sets.Peer reviewe

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis