Towards Developing a Hybrid Nonlinear Vibration Energy Harvester for Remote Sensing Applications: A Design and Optimization Study

A novel design of a hybrid piezoelectric-electromagnetic harvester for vortex-induced vibration applications inside a pipe-flow is proposed. The piezoelectric energy harvester is modeled with a macro-fiber composite with an electromagnetic oscillator. Analytical and numerical models were developed for the fluid-structure interaction. An optimization study was conducted using finite element modelling across different bluff body shapes and orientations where triangle and 2.5x ellipse were optimal choices for maximizing energy harvesting properties. An investigation into dual-mass energy harvesting was also performed for bandwidth enhancement. A secondary beam has improved the piezoelectric performance by 21% to 52%. Finally, an experimental study was conducted to verify the narrowband resonance models and validate the use of a magnetically coupled dual broadband harvester (58% enhancement). Optimization and design of the harvester has led to improvements in performance that can realize powering sensors and devices in wireless applications

Dynamic behavior modelling of a hybrid magnetorheological elastomer with encapsulated fluid for base vibration isolation

Magnetorheological elastomers (MRE) based semi-active isolators utilize MREs whose mechanical properties, such as stiffness and damping, change in response to an external magnetic field. MREs implementation in semi-active isolation remains challenging due to their slow response time caused by the suspension of the magnetic particles inside the elastomeric matrix and limited damping capabilities. Hybrid MREs, a combination of MREs and MRFs, have been developed to improve semi-active isolation's material properties and performance. However, modelling the nonlinear and hysteretic behavior of hybrid MRE-based isolators remains a challenge and needs to be adequately addressed. To bridge the gap, this study presents a parametric model for a hybrid semi-active isolator's nonlinear and hysteretic behavior that utilizes a hybrid MRE (H-MRE). The behavior of conventional and hybrid MRE-based isolators are experimentally tested under varying loading conditions of excitation frequency and input current. Simulation models are created using combinations of three different phenomenological models, Bouc-Wen, Modified-Dahl and LuGre friction. The experimental data are used to optimize and fit the simulated response of each model, and hence optimal values of the MRE and MRF hysteresis parameters are determined. The parameter estimation results indicate that a combination of LuGre friction for the MRE and Bouc-Wen for the MRF improves the accuracy of predicting the dynamic behaviour of the hybrid isolator. The relationship between the model parameters and loading conditions is also investigated and described through polynomial equations of the third order. These findings could provide valuable insights for the system identification and control of hybrid semi-active isolators and pave the way for developing smart base isolation systems utilizing hybrid MREs in future research.This research is supported by Qatar University Graduate Assistantship Grant .Scopu

Wideband Vibration Control in Multi Degree of Freedom System: Experimental Verification Using Labview

The attenuation of vibration in a multi degree of freedom system is presented in this paper. The objective is to employ the instrumentation capability of LabVIEW in the implementation of an Active Dynamic Vibration Absorber (ADVA). To reduce vibration, the ADVA and the multi degree of freedom systems used is taken to be an intelligent coupled system that determines the resonance frequency and subsequently tuned itself to reduce vibration amplitude at the resonance frequencies. The state machine platform in NI LabVIEW is used in achieving this objective. Each state is coded and a transition to the next state using interphase detection is used to run the control sequence. Each of the state action is well defined and the coupled system ensures a smart response to resonance frequencies. The knowledge of the system frequency response function and the ADVA is first studied. The performance of the ADVA is then incorporated into the design of the ADVA and implemented on an experimental setup. The result of the implementation reveals a robust adaptation of the ADVA to resonance frequencies and also reduction of vibration amplitude at all the resonance frequencies of the multi degree of freedom system

Vibration Energy Harvesting using Single and Comb-shaped Piezoelectric Beam Structures: Modeling and Simulation

AbstractOf late, many have shown great interests in the area of energy harvesting or energy scavenging. Researchers have been venturing into methods that can generate acceptable level of voltage since decades ago. In line with the spirit of green technology, energy harvesting will be a major contributor towards saving our environment in near future. Vibration energy harvesting, specifically, is getting more and more attention nowadays. With the abundant sources, this type of energy harvesting can generate desired voltage to power any low power devices and wireless sensor; and subsequently high power devices in the future. In this research, unimorph piezoelectric energy harvester is chosen to harvest wideband mechanical energy. The derivation of the mathematical modelling is based on the Euler-Bernoulli beam theory. MATLAB and COMSOL Multiphysics software are used to study the influence of the structure in generating output voltage due to base excitations. Finally, the results of the frequency response are displayed in the form of voltage within frequency range of 0 to 3500Hz, at which the comb-shaped piezoelectric beam structure shows better performance as there exist more natural frequencies in the specified range of frequency

Voltage Generation in Piezoelectric Energy Harvesting with Magnet: FEA Simulation and Experimental Analysis

Energy harvesting devices are needed as an alternative to batteries as it is costly to power up wireless sensor network. However, the power generated and operating bandwidth for the typical energy harvester are still compromised. Therefore, in this work, the use of permanent magnet in Piezoelectric Energy Harvester (PEH) is proposed to increase the operating bandwidth. A simulation study was conducted using COMSOL Multiphysics software to observe the effect of mechanical tuning using magnet on the voltage produced. It shows that PEH with oscillating magnetic field is capable of reaching generated peak power of 0.775 mW and increase the operating bandwidth by 10%. Experimental setup was also fabricated to further validate the observation at different polarities and varying distances with permanent magnets. It is observed that while the peak power achieved in the attractive mode is smaller as compared to its counterpart, however, its bandwidth is larger

Empirical modeling of micromechanical bending process of vertically aligned carbon nanotube forest using response surface methodology

Micromechanical bending (M2B) is a newly developed micro patterning technique applied for vertically aligned carbon nanotubes (VACNTs) array, commonly known as CNT forest. This process is required to realize the various use of CNT forest in Micro-Electromechanical Systems (MEMS). There are various parameters involved in M2B process that controls the surface roughness of the processed structure of the CNT forest. However, there is no mathematical model available, yet that could predict the influence of these parameters on the surface roughness of the patterned CNT forest. In this paper, an empirical approach has been used to predict the surface roughness for the micromechanical bending (M2B) processed CNT forest. At first, several experiments were conducted by varying different process parameters such as tool rotational speed, lateral speed and a step size of the bend. Best optimized process parameters were identified at 2,000 rpm tool rotational speed, 1 mm/min lateral speed and 1 μm step size that produced a minimum surface roughness of Ra = 15 nm. Finally, a response surface methodology (RSM) based mathematical model was developed and validated with reasonable accuracy to understand the impact of different parameters on the M2B process

DEVELOPMENT OF LOW POWER WIRELESS POWER TRANSFER SYSTEM USING RESONANCE PRINCIPLE WITH SECURITY FEATURES

This research describes a resonance principle-based low power Wireless Power Transfer (WPT) system. The reflective impedance model is derived to evaluate the resonance coupling between coils. Additionally, Cockroft Walton voltage boosting circuit is incorporated to boost up the received voltage to the appropriate level, instead of using traditional conditioning circuits. The prototype model, operating at 130 kHz, is demonstrated experimentally and analysed graphically to validate the performance of designed circuit. For an overall span of 100 mm coil separation distance, the maximum efficiency of 60% with no load and 36% loaded system, is observed at a distance of 55 mm with the approximate (e.g., manual) axial orientation of coils. It can be supported widely for the portable electronic products and biomedical devices. As an added contribution, the WPT circuit were enabled by a password security feature using an arduino nicrocontroller.

An efficient transition metal chalcogenide sensor for monitoring respiratory alkalosis

For many biomedical applications, high-precision CO2 detection with a rapid response is essential. Due to the superior surface-active characteristics, 2D materials are particularly crucial for electrochemical sensors. The liquid phase exfoliation method of 2D Co2Te3 production is used to achieve the electrochemical sensing of CO2. The Co2Te3 electrode performs better than other CO2 detectors in terms of linearity, low detection limit, and high sensitivity. The outstanding physical characteristics of the electrocatalyst, including its large specific surface area, quick electron transport, and presence of a surface charge, can be credited for its extraordinary electrocatalytic activity. More importantly, the suggested electrochemical sensor has great repeatability, strong stability, and outstanding selectivity. Additionally, the electrochemical sensor based on Co2Te3 could be used to monitor respiratory alkalosis.This publication was supported by the Qatar University Internal Grant No. QUCG-CAM-21/22-1