ORCID Profile
0000-0001-5445-8883
Current Organisations
Macquarie University
,
UNSW Sydney
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Publisher: The Royal Society
Date: 12-2021
Abstract: Monitoring human respiratory patterns is of great importance as it gives essential information for various medical conditions, e.g. sleep apnoea syndrome and chronic obstructive pulmonary disease and asthma, etc. Herein, we have developed a polymeric airflow sensor based on nanocomposites of vertically grown graphene nanosheets (VGNs) with polydimethylsiloxane (PDMS) and explored their applications in monitoring human respiration. The sensing performance of the VGNs/PDMS nanocomposite was characterized by exposing to a range of airflow rates (20–130 l min −1 ), and a linear performance with high sensitivity and low response time (mostly below 1 s) was observed. To evaluate the experimental results, finite-element simulation models were developed in the COMSOL Multiphysics package. The piezoresistive properties of VGNs/PDMS thin film and fluid–solid interaction were thoroughly studied. Laser Doppler vibrometry measures of sensor tip displacement closely approximated simulated deflection results and validated the dynamic response of the sensor. By comparing the proposed sensor and some other airflow sensors in the literature, it is concluded that the VGNs/PDMS airflow sensor has excellent features in terms of sensor height, detection range and sensitivity. The potential application of the VGNs/PDMS airflow sensor in detecting the respiration pattern of human exercises like walking, jogging and running has been demonstrated.
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 09-2017
Publisher: SAGE Publications
Date: 06-06-2018
Abstract: This study is dedicated to drawing a comparison between two- and three-dimensional approach capabilities for the simulation of two similar rotors placed in three inline (or tandem) arrangements. This arrangement is generally recognized as the worst-case scenario for the downwind rotor considering the vortices and disorders produced by the upwind rotor. The rotor in question with the diameter of 2.5 m is made up of three NACA0015 blades with the chord length and span size equal to 0.4 and 3 m, respectively. Based on the authors’ previous works, the [Formula: see text] shear stress transport model was selected for this comparative study. According to the results, there is an appreciable deviation in the aerodynamic performance of the upwind rotor predicted by the two-dimensional and three-dimensional simulation techniques. There is no tangible difference between the two-dimensional and three-dimensional results in terms of the averaged power output for the downwind rotor. However, the study of flow field employing different means like vortex structures, axial velocity, and even torque variation indicates that the two-dimensional approach is unable to achieve realistic and reliable output data. The introduced “pillar effect” regarding the dimensional limitations of the two-dimensional approach, which affects the vorticity shape and its dissipation, is plausible evidence for this discrepancy.
Publisher: Elsevier BV
Date: 05-2014
Publisher: Springer Science and Business Media LLC
Date: 31-05-2016
Publisher: Elsevier BV
Date: 06-2014
Publisher: Elsevier BV
Date: 09-2016
Publisher: Emerald
Date: 02-11-2015
Abstract: – The purpose of this paper is to focus on convective heat and mass transfer characteristics of Cu-water nanofluid inside a porous microchannel in the presence of a uniform magnetic field. The walls of the microchannel are subjected to constant asymmetric heat fluxes and also the first order catalytic reaction. To represent the non-equilibrium region near the surfaces, the Navier’s slip condition is considered at the surfaces because of the non-adherence of the fluid-solid interface and the microscopic roughness in microchannels. – Employing the Brinkman model for the flow in the porous medium and the “clear fluid compatible” model as a viscous dissipation model, the conservative partial differential equations have been transformed into a system of ordinary ones via the similarity variables. Closed form exact solutions are obtained analytically based on dimensionless parameters of velocity, temperature and species concentration. – Results show that the addition of Cu-nanoparticles to the fluid has a significant influence on decreasing concentration, temperature distribution at the both walls and velocity profile along the microchannel. In addition, total heat transfer in microchannel increases as nanoparticles add to the fluid. Slip parameter and Hartmann number have the decreasing effects on concentration and temperature distributions. Slip parameter leads to increase velocity profiles, while Hartmann number has an opposite trend in velocity profiles. These two parameters increase the total heat transfer rate significantly. – In the present study, a comprehensive analytical solution has been obtained for convective heat and mass transfer characteristics of Cu-water nanofluid inside a porous microchannel in the presence of a uniform magnetic field. Finally, the effects of several parameters such as Darcy number, nanoparticle volume fraction, slip parameter, Hartmann number, Brinkman number, asymmetric heat flux parameter, Soret and Damkohler numbers on total heat transfer rate and fluid flow profiles are studied in more detail. To the best of author’s knowledge, no study has been conducted to this subject and the results are original.
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 2014
Publisher: IEEE
Date: 12-2019
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 2016
DOI: 10.2514/1.T4562
Publisher: Wiley
Date: 06-09-2020
Publisher: Oxford University Press (OUP)
Date: 13-03-2014
Abstract: In the present work, a recently developed in-house 2D CFD code is used to study the effect of gas turbine stator blade roughness on various performance parameters of a two-dimensional blade cascade. The 2D CFD model is based on a high resolution flux difference splitting scheme of Roe (1981). The Reynolds Averaged Navier-Stokes (RANS) equations are closed using the zero-equation turbulence model of Baldwin-Lomax (1978) and two-equation Shear Stress Transport (SST) turbulence model. For the smooth blade, results are compared with experimental data to validate the model. Finally, a correlation between roughness Reynolds number and loss coefficient for both turbulence models is presented and tested for three other roughness heights. The results of 2D turbine blade cascades can be used for one-dimensional models such as mean line analysis or quasi-three-dimensional models e.g. streamline curvature method.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2019
Publisher: Springer Science and Business Media LLC
Date: 21-06-2016
Publisher: Elsevier BV
Date: 12-2016
Publisher: Springer Science and Business Media LLC
Date: 06-03-2018
Publisher: Elsevier BV
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 21-05-2023
DOI: 10.1007/S13369-023-07895-6
Abstract: The current research deals with the fully developed forced convection through metallic foam partly filled annulus. A metallic foam was adhered to inner and outer walls of the annulus in such a way that two foam regions and one open region were formed against the fluid flow. The inner and outer surfaces were exposed to an asymmetric heat flux ratio. To couple heat transfer and flow of the foam and open regions, no-slip coupling conditions were considered at the fluid–solid interface. Based on the fully developed fluid flow assumption, momentum, continuity, and energy equations for foam and open regions were simplified to ordinary differential equations and solved numerically as the governing equations. The impact of porosity, pore density, ratio of fluid–solid conductivity, Re number, heat flux ratio on velocity profiles, temperature distributions, flow heterogeneity, friction factor, Nu, and system performance in an annulus partly included with metallic foam were obtained. The obtained results indicated that flow heterogeneity, friction factor, and Nu depend crucially on thickness of the foam, porosity, and pore density. The study found that partially filled cases had lower performance than the empty annulus across various porosity, pore density, and Re number for a fixed conductivity ratio of 0.01, but the performance depended on the conductivity ratio. When k r values were below 0.002, the partially filled annulus outperformed the empty one, but for a fully filled annulus, this critical k r increased to 0.006.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Wiley
Date: 14-09-2022
Abstract: Flow sensors play a critical role in monitoring flow parameters, including rate, velocity, direction, and rotation frequency. In this paper, inspired by biological hair cells in the human vestibular system, an innovative flow sensor is developed based on polyvinyl alcohol (PVA) hydrogel nanocomposites with a maze‐like network of vertically grown graphene nanosheets (VGNs). The VGNs/PVA hydrogel absorbs a copious amount of water when immersed in water, making the sensor highly sensitive to tiny stimuli underwater. The sensor demonstrates a high sensitivity (5.755 mV (mm s −1 ) −1 ) and extremely low velocity detection (0.022 mm s −1 ). It also reveals outstanding performance in detecting low‐frequency oscillatory flows down to 0.1 Hz, which make it suitable for many biomedical applications. As one of the potential applications of the sensor, it exhibits excellent performance in mimicking various physiological conditions of vestibular hair cells. To explain the experimental results, a complete finite element simulation is developed to model the piezoresistive effect of VGNs/PVA thin film structure. This is the first attempt to develop hydrogel–graphene nanosheet‐based flow sensors, which creates the closest artificial sensor to vestibular hair cells. This miniaturized hair cell sensor paves the way for utilizing hydrogels to develop next‐generation of ultrasensitive flow sensors for biomedical applications.
Publisher: Oxford University Press (OUP)
Date: 18-09-2016
Abstract: In this paper, the dynamic stall of S809 airfoil that widely used in horizontal axis wind turbine, in different reduced frequencies is investigated. The simulation was carried out numerically handling Navier-Stokes equations. For this purpose, the segregated solver with SIMPLE algorithm was chosen to solve the momentum equations. The effect of turbulence on the flow field is taken into account using Shear Stress Transport (SST) K-ω turbulence model. The obtained numerical results are compared with experimental and a few numerical results. The results indicate that the K-ω SST model is in good agreement with experimental results for both steady and unsteady conditions. Furthermore, a non-dimensional parameter, relating the acceleration of unsteady free stream velocity and acceleration of pitch motion (known as reduced frequency), is also investigated. In addition, the results show that any increase in the reduced frequency increases the instantaneous aerodynamic characteristics of oscillating airfoil.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.BIOS.2022.114521
Abstract: Balance disorders affect approximately 30% of the population throughout their lives and result in debilitating symptoms, such as spontaneous vertigo, nystagmus, and oscillopsia. The main cause of balance disorders is peripheral vestibular dysfunction, which may occur as a result of hair cell loss, neural dysfunction, or mechanical (and morphological) abnormality. The most common cause of vestibular dysfunction is arguably vestibular hair cell damage, which can result from an array of factors, such as ototoxicity, trauma, genetics, and ageing. One promising therapy is the vestibular prosthesis, which leverages the success of the cochlear implant, and endeavours to electrically integrate the primary vestibular afferents with the vestibular scene. Other translational approaches of interest include stem cell regeneration and gene therapies, which aim to restore or modify inner ear receptor function. However, both of these techniques are in their infancy and are currently undergoing further characterization and development in the laboratory, using animal models. Another promising translational avenue to treating vestibular hair cell dysfunction is the potential development of artificial biocompatible hair cell sensors, aiming to replicate functional hair cells and generate synthetic 'receptor potentials' for sensory coding of vestibular stimuli to the brain. Recently, artificial hair cell sensors have demonstrated significant promise, with improvements in their output, such as sensitivity and frequency selectivity. This article reviews the history and current state of bioelectronic devices to interface with the labyrinth, spanning the vestibular implant and artificial hair cell sensors.
Publisher: Frontiers Media SA
Date: 19-10-2020
Publisher: Springer Science and Business Media LLC
Date: 11-05-2020
DOI: 10.1007/S40820-020-00446-W
Abstract: This paper suggests development of a flexible, lightweight, and ultra-sensitive piezoresistive flow sensor based on vertical graphene nanosheets (VGNs) with a mazelike structure. The sensor was thoroughly characterized for steady-state and oscillatory water flow monitoring applications. The results demonstrated a high sensitivity (103.91 mV (mm/s) −1 ) and a very low-velocity detection threshold (1.127 mm s −1 ) in steady-state flow monitoring. As one of many potential applications, we demonstrated that the proposed VGNs/PDMS flow sensor can closely mimic the vestibular hair cell sensors housed inside the semicircular canals (SCCs). As a proof of concept, magnetic resonance imaging of the human inner ear was conducted to measure the dimensions of the SCCs and to develop a 3D printed lateral semicircular canal (LSCC). The sensor was embedded into the artificial LSCC and tested for various physiological movements. The obtained results indicate that the flow sensor is able to distinguish minute changes in the rotational axis physical geometry, frequency, and litude. The success of this study paves the way for extending this technology not only to vestibular organ prosthesis but also to other applications such as blood/urine flow monitoring, intravenous therapy (IV), water leakage monitoring, and unmanned underwater robots through incorporation of the appropriate packaging of devices.
Publisher: IEEE
Date: 20-06-2021
Publisher: American Chemical Society (ACS)
Date: 13-09-2021
Abstract: With an ageing population, hearing disorders are predicted to rise considerably in the following decades. Thus, developing a new class of artificial auditory system has been highlighted as one of the most exciting research topics for biomedical applications. Herein, a design of a biocompatible piezoresistive-based artificial hair cell sensor is presented consisting of a highly flexible and conductive polyvinyl alcohol (PVA) nanocomposite with vertical graphene nanosheets (VGNs). The bilayer hydrogel sensor demonstrates excellent performance to mimic biological hair cells, responding to acoustic stimuli in the audible range between 60 Hz to 20 kHz. The sensor output demonstrates stable mid-frequency regions (∼4-9 kHz), with the greatest sensitivity as high frequencies (∼13-20 kHz). This is somewhat akin to the mammalian auditory system, which has remarkable sensitivity and sharp tuning at high frequencies due to the "active process". This work validates the PVA/VGN sensor as a potential candidate to play a similar functional role to that of the cochlear hair cells, which also operate over a wide frequency domain in a viscous environment. Further characterizations of the sensor show that increasing the sound litude results in higher responses from the sensor while taking it to the depth drops the sensor outputs due to attenuation of sound in water. Meanwhile, the acoustic pressure distribution of sound waves is predicted through finite element analysis, whereby the numerical results are in perfect agreement with experimental data. This proof-of-concept work creates a platform for the future design of susceptible, flexible biomimetic sensors to closely mimic the biological cochlea.
No related grants have been discovered for Sajad Abolpour Moshizi.