Ahmed Atrah | Universiti Kebangsaan Malaysia (original) (raw)

Papers by Ahmed Atrah

Energies

In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabric... more In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabricated and tested. The design can enhance output power by frequency up-conversion and provide the desired output power range from a fixed input rotational speed by increasing the interchangeable planet cover numbers which is the novelty of this work. The prototype ability to harvest energy has been evaluated with four experiments, which determine the effect of rotational speed, interchangeable planet cover numbers, the distance between PZTs, and PZTs numbers. Increasing rotational speed shows that it can increase output power. However, increasing planet cover numbers can increase the output power without the need to increase speed or any excitation element. With the usage of one, two, and four planet cover numbers, the prototype is able to harvest output power of 0.414 mW, 0.672 mW, and 1.566 mW, respectively, at 50 kΩ with 1500 rpm, and 6.25 Hz bending frequency of the PZT. Moreover, when...

Micromachines, Jul 21, 2017

This study presents the creation of a Karman vortex for a fluttering electromagnetic energy harve... more This study presents the creation of a Karman vortex for a fluttering electromagnetic energy harvester device using a cylinder. The effects of two parameters, which are the diameter and the position of the cylinder, were investigated on the Karman vortex profile and the amplitude of the fluttering belt, respectively. A simulation was conducted to determine the effect of the creation of the Karman vortex, and an experiment was performed to identify influence of the position of the cylinder on the fluttering belt amplitude. The results demonstrated that vortex-induced vibration occurred at the frequency of the first natural mode for the belt at 3 cm and 10 cm for the diameter and position of the cylinder, respectively. Under such configuration, an electromagnetic energy harvester was attached and vibrated via the fluttering belt inside the turbulent boundary layers. This vibration provides a measured output voltage and can be used in wireless sensors.

Energies

Energies, Jan 2, 2020

In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabric... more In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabricated and tested. The design can enhance output power by frequency up-conversion and provide the desired output power range from a fixed input rotational speed by increasing the interchangeable planet cover numbers which is the novelty of this work. The prototype ability to harvest energy has been evaluated with four experiments, which determine the effect of rotational speed, interchangeable planet cover numbers, the distance between PZTs, and PZTs numbers. Increasing rotational speed shows that it can increase output power. However, increasing planet cover numbers can increase the output power without the need to increase speed or any excitation element. With the usage of one, two, and four planet cover numbers, the prototype is able to harvest output power of 0.414 mW, 0.672 mW, and 1.566 mW, respectively, at 50 kΩ with 1500 rpm, and 6.25 Hz bending frequency of the PZT. Moreover, when three cantilevers are used with 35 kΩ loads, the output power is 6.007 mW, and the power density of piezoelectric material is 9.59 mW/cm 3. It was concluded that the model could work for frequency up-conversion and provide the desired output power range from a fixed input rotational speed and may result in a longer lifetime of the PZT.

An acoustic energy harvester using piezoelectric backplate has been studied numerically using COM... more An acoustic energy harvester using piezoelectric backplate has been studied numerically using COMSOL Multiphysics 4.3. There are many research activities focusing on harvesting various environmental energies. However, acoustic energy harvesting has seldom been studied. In this study, a Helmholtz Resonator is used to collect travelling acoustic waves at frequencies of 3500 to 4500Hz. Piezoelectric ring made of Lead Zirconate Titanate (PZT) is connected with silicone membrane. At the resonance of the Helmholtz Resonator, amplified resonant acoustic standing waves are developed inside the cavity. The pressure difference between the walls drive the vibration motion of the membrane backplate and that leads to generate an electrical power via the direct piezoelectric effect. In COMSOL, the 2D Acoustic-Piezoelectric physics has been used for a frequency domain analysis. Background acoustic pressure is used to simulate an incident plane wave which acoustically excites the membrane. The material properties are also included in simulations to consider sound leakage through resonator walls. The resonance behaviour of the Helmholtz Resonator with the piezoelectric backplate has been studied. The neck radius has been swept with 1 µm interval to investigate the output voltage. When using a parameter sweep for neck length from 50 µm to 150 µm, it was found that at 3.5 kHz maximum output voltage was 1.3 mV. In conclusion, the numerical studies of acoustic resonance behaviour of the Helmholtz Resonator with piezoelectric backplate are performed using COMSOL Multiphysics. The harvested voltage and power have been calculated and compared to previous works.

This paper presents designs and developments of Acoustic Energy Harvester (AEH). AEH consists of ... more This paper presents designs and developments of Acoustic Energy Harvester (AEH). AEH consists of 3 main components which are a sound resonator (Helmholtz Resonator), energy capturing membrane, and an energy storage unit. Helmholtz Resonator can be optimized by playing around with its geometry to get the resonance frequency that will match with the resonance frequency of membrane. Researchers used two power converter topologies for the energy reclamation process. The first one was a rectifier, the second one was a rectifier connected to a flyback convertor. Although the available acoustic energy may be small in many situations, the energy requirements for certain applications such as microsensing are also correspondingly small. The ability to reclaim acoustic energy and store are sufficient to power a variety of low power electronic devices.

Energies

Micromachines, Jul 21, 2017

Energies

Energies, Jan 2, 2020

In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabric... more In the present study, a rotational piezoelectric (PZT) energy harvester has been designed, fabricated and tested. The design can enhance output power by frequency up-conversion and provide the desired output power range from a fixed input rotational speed by increasing the interchangeable planet cover numbers which is the novelty of this work. The prototype ability to harvest energy has been evaluated with four experiments, which determine the effect of rotational speed, interchangeable planet cover numbers, the distance between PZTs, and PZTs numbers. Increasing rotational speed shows that it can increase output power. However, increasing planet cover numbers can increase the output power without the need to increase speed or any excitation element. With the usage of one, two, and four planet cover numbers, the prototype is able to harvest output power of 0.414 mW, 0.672 mW, and 1.566 mW, respectively, at 50 kΩ with 1500 rpm, and 6.25 Hz bending frequency of the PZT. Moreover, when three cantilevers are used with 35 kΩ loads, the output power is 6.007 mW, and the power density of piezoelectric material is 9.59 mW/cm 3. It was concluded that the model could work for frequency up-conversion and provide the desired output power range from a fixed input rotational speed and may result in a longer lifetime of the PZT.