Fabrication of Graphene Supercapacitors for Flexible Energy Storage

Habashi, M. Namdar,Asl, Shahab Khameneh Materials Research Society of Korea 2017 한국재료학회지 Vol.27 No.5

In the present work, graphene powder was synthesized by laser scribing method. The resultant flexible light-scribed graphene is very appropriate for use in micro-supercapacitors. The effect of the laser scribing process in reducing graphene oxide (GO) was investigated. GO was synthesized using a chemical mixture of GO solution; then, it was coated onto a LightScribe DVD disk and laser scribed to reduce GO and create laser-scribed graphene (LSG). The CV curves of pristine rGO at various scan rates showed that the ultimate product possesses the ability to store energy at the supercapacitor level. Charge-discharge curves of pristine rGO at two different current densities indicated that the specific capacitance ($C_m$) increases due to the reduction of the discharge current density. Finally, the long-term charge-discharge stability of the LSG was plotted and indicates that the specific capacitance decreases very slightly from its primary capacitance of ${\sim}10F\;cm^{-3}$ and that the cyclic stability is favorable over 1000 cycles.

A FRONTIER OF PARALLEL CFD

Wagdi G. Habashi 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5

CFD-FSI simulation of vortex-induced vibrations of a circular cylinder with low mass-damping

Borna, Amir,Habashi, Wagdi G.,McClure, Ghyslaine,Nadarajah, Siva K. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.16 No.5

A computational study of vortex-induced transverse vibrations of a cylinder with low mass-damping is presented. An Arbitrary Lagrangian-Eulerian (ALE) formulation of the Unsteady Reynolds-Averaged Navier-Stokes equations (URANS), along with the Spalart-Allmaras (SA) one-equation turbulence model, are coupled conservatively with rigid body motion equations of the cylinder mounted on elastic supports in order to study the amplitude and frequency response of a freely vibrating cylinder, its flow-induced motion, Vortex Street, near-wake flow structure, and unsteady loading in a moderate range of Reynolds numbers. The time accurate response of the cylinder from rest to its limit cycle is studied to explore the effects of Reynolds number on the start of large displacements, motion amplitude, and frequency. The computational results are compared with published physical experiments and numerical studies. The maximum amplitudes of displacements computed for various Reynolds numbers are smaller than the experimental values; however, the overall agreement of the results is quite satisfactory, and the upper branch of the limit-cycle displacement amplitude vs. reduced velocity response is captured, a feature that was missed by other studies. Vortex shedding modes, lock-in phenomena, frequency response, and phase angles are also in agreement with experiments.

Application of bioactive glasses in various dental fields

Nazanin Jafari,Mina Seyed Habashi,Alireza Hashemi,Reza Shirazi,Nader Tanideh,Amin Tamadon 한국생체재료학회 2022 생체재료학회지 Vol.26 No.3

Bioactive glasses are a group of bioceramic materials that have extensive clinical applications. Their properties such as high biocompatibility, antimicrobial features, and bioactivity in the internal environment of the body have made them useful biomaterials in various fields of medicine and dentistry. There is a great variation in the main composition of these glasses and some of them whose medical usage has been approved by the US Food and Drug Administration (FDA) are called Bioglass. Bioactive glasses have appropriate biocompatibility with the body and they are similar to bone hydroxyapatite in terms of calcium and phosphate contents. Bioactive glasses are applied in different branches of dentistry like periodontics, orthodontics, endodontics, oral and maxillofacial surgery, esthetic and restorative dentistry. Also, some dental and oral care products have bioactive glasses in their compositions. Bioactive glasses have been used as dental implants in the human body in order to repair and replace damaged bones. Other applications of bioactive glasses in dentistry include their usage in periodontal disease, root canal treatments, maxillofacial surgeries, dental restorations, air abrasions, dental adhesives, enamel remineralization, and dentin hypersensitivity. Since the use of bioactive glasses in dentistry is widespread, there is a need to find methods and extensive resources to supply the required bioactive glasses. Various techniques have been identified for the production of bioactive glasses, and marine sponges have recently been considered as a rich source of it. Marine sponges are widely available and many species have been identified around the world, including the Persian Gulf. Marine sponges, as the simplest group of animals, produce different bioactive compounds that are used in a wide range of medical sciences. Numerous studies have shown the anti-tumor, anti-viral, anti-inflammatory, and antibiotic effects of these compounds. Furthermore, some species of marine sponges due to the mineral contents of their structural skeletons, which are made of biosilica, have been used for extracting bioactive glasses.

Eight-Year Experience With Botulinum Toxin Type-A Injections for the Treatment of Nonneurogenic Overactive Bladder: Are Repeated Injections Worthwhile?

Shannon HK Kim,David Habashy,Sana Pathan,Vincent Tse,Ruth Collins,Lewis Chan 대한배뇨장애요실금학회 2016 International Neurourology Journal Vol.20 No.1

Purpose: To investigate the efficacy and safety of repeated botulinum toxin type-A (BTX-A) injections for patients with drugrefractory nonneurogenic overactive bladder (NNOAB) and explore factors predictive of outcome. Methods: Data were collected from all patients receiving repeated BTX-A injections for drug-refractory NNOAB between 2004 and 2012. Trigone-sparing injections were administered under sedation with antibiotic prophylaxis. Patient characteristics including age, sex, preoperative urodynamics, injection number, BTX-A dose, complications, and patient global impression of improvement (PGI-I) scores were collected. Correlations between patient factors and outcomes were assessed by using Pearson’s chi-square tests. Results: Fifty-two patients with a mean age of 67.4 years (range, 26–93 years) received 140 BTX-A injections in total; 33 (64%), 15 (29%), and 4 patients (7%) received 2, 3 to 4, and 5 to 8 injections, respectively. Mean follow-up time was 49 months (range, 9–101 months). Nine patients developed urinary tract infection; additionally, 3 patients experienced transient urinary retention. Median PGI-I score was 2 out of 7 (interquartile range [IQR], 2). For 46 patients, the PGI-I score remained stable with the administration of each injection. Pearson chi-square tests revealed that male patients or reduced bladder compliance was associated with a higher (worse) PGI-I score. Median PGI-I scores for men and women were 3 (IQR, 1) and 2 (IQR, 1), respectively; additionally, median PGI-I scores for those with normal bladder compliance and those with reduced bladder compliance were 2 (IQR, 2) and 4.5 (IQR, 1), respectively. Median PGI-I scores and complication rates were the same in the older patient (≥70 years) and younger (<70 years) patient cohorts. Conclusions: Efficacy is maintained with repeated BTX-A injections. Patients including the elderly show a good degree of tolerability with a low complication rate. Male patients or reduced bladder compliance is associated with poorer outcomes.

CFD-FSI simulation of vortex-induced vibrations of a circular cylinder with low mass-damping

Amir Borna,Wagdi G. Habashi,Ghyslaine McClure,Siva K. Nadarajah 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.5

A computational study of vortex-induced transverse vibrations of a cylinder with low mass-damping is presented. An Arbitrary Lagrangian-Eulerian (ALE) formulation of the Unsteady Reynolds-Averaged Navier-Stokes equations (URANS), along with the Spalart-Allmaras (SA) one-equation turbulence model, are coupled conservatively with rigid body motion equations of the cylinder mounted on elastic supports in order to study the amplitude and frequency response of a freely vibrating cylinder, its flow-induced motion, Vortex Street, near-wake flow structure, and unsteady loading in a moderate range of Reynolds numbers. The time accurate response of the cylinder from rest to its limit cycle is studied to explore the effects of Reynolds number on the start of large displacements, motion amplitude, and frequency. The computational results are compared with published physical experiments and numerical studies. The maximum amplitudes of displacements computed for various Reynolds numbers are smaller than the experimental values; however, the overall agreement of the results is quite satisfactory, and the upper branch of the limit-cycle displacement amplitude vs. reduced velocity response is captured, a feature that was missed by other studies. Vortex shedding modes, lock-in phenomena, frequency response, and phase angles are also in agreement with experiments.

Multiscale finite element method applied to detached-eddy simulation for computational wind engineering

Yue Zhang,Rooh A. Khurram,Wagdi G. Habashi 한국풍공학회 2013 한국풍공학회지 Vol.17 No.1

A multiscale finite element method is applied to the Spalart-Allmaras turbulence model based detached-eddy simulation (DES). The multiscale arises from a decomposition of the scalar field into coarse (resolved) and fine (unresolved) scales. It corrects the lack of stability of the standard Galerkin formulation by modeling the scales that cannot be resolved by a given spatial discretization. The stabilization terms appear naturally and the resulting formulation provides effective stabilization in turbulent computations, where reaction-dominated effects strongly influence near-wall predictions. The multiscale DES is applied in the context of high-Reynolds flow over the Commonwealth Advisory Aeronautical Council (CAARC) standard tall building model, for both uniform and turbulent inflows. Time-averaged pressure coefficients on the exterior walls are compared with experiments and it is demonstrated that DES is able to resolve the turbulent features of the flow and accurately predict the surface pressure distributions under atmospheric boundary layer flows.

Multiscale finite element method applied to detached-eddy simulation for computational wind engineering

Zhang, Yue,Khurram, Rooh A.,Habashi, Wagdi G. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.1

A multiscale finite element method is applied to the Spalart-Allmaras turbulence model based detached-eddy simulation (DES). The multiscale arises from a decomposition of the scalar field into coarse (resolved) and fine (unresolved) scales. It corrects the lack of stability of the standard Galerkin formulation by modeling the scales that cannot be resolved by a given spatial discretization. The stabilization terms appear naturally and the resulting formulation provides effective stabilization in turbulent computations, where reaction-dominated effects strongly influence near-wall predictions. The multiscale DES is applied in the context of high-Reynolds flow over the Commonwealth Advisory Aeronautical Council (CAARC) standard tall building model, for both uniform and turbulent inflows. Time-averaged pressure coefficients on the exterior walls are compared with experiments and it is demonstrated that DES is able to resolve the turbulent features of the flow and accurately predict the surface pressure distributions under atmospheric boundary layer flows.

Sensitivity studies in spent fuel pool criticality safety analysis for APR-1400 nuclear power plants

Abdulrahman S. Al Awad,Abdalla Habashy,Walid A. Metwally 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.5

A criticality safety analysis was performed for the APR-1400 spent fuel pool region-II to ensure the safestorage of spent fuel, with credit taken for depletion and in-rack neutron absorbers (Metamic panels). PLUS7 fuel assembly was modeled using TRITON-NEWT of SCALE-6.1. The burnup-dependent crosssectionlibrary was generated under limiting core-operating conditions with 5%-w U-235 initialenrichment. MCNP5 was used to evaluate the neutron multiplication factor in an infinite array of rackcells with the axially nonuniformly burnt PLUS7 assemblies under normal, abnormal, and accidentconditions; including all biases and uncertainties. The main purpose of this study is to investigatereactivity variations due to the critical depletion and reactor operation parameters. The approach, assumptions,and modeling methods were verified by analyzing the contents of the most important fissileand the associated reactivity effects. The Nuclear Regulatory Commission (NRC) guidance on k-eff beingless than 1.0 for spent fuel pools filled with unborated water was the main criterion used in this study. Itwas found that assemblies with 49.0 GWd/MTU and 5.0 w/o U-235 initial enrichment loaded in Region-IIsatisfy this criterion. Moreover, it was found that the end effect resulted in a positive bias, thus ensuringits consideration

Mathematical Modelling of Vickers Hardness of Sn-9Zn-Cu Solder Alloys Using an Artificial Neural Network

A. F. Abd El‑Rehim,D. M. Habashy,H. Y. Zahran,H. N. Soliman 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

An artificial neural network (ANN) model was used for the simulation and prediction of the mechanical properties ofSn-9Zn-Cu solder alloys. Sn-9Zn-Cu solder alloys containing different Cu contents (0, 1, 2, 3, 4 and 5 wt%) were successfullyprepared by permanent mold casting. The specimens were heated in a protective argon atmosphere at 433 K for 24 h,followed by water quenching at 298 K. Finally, the heat-treated samples were aged at 373 K for different time intervals (ta = 2,4, 8, 16 and 32 h), followed by water quenching at 298 K. The phases present in the current alloys were detected by X-raydiffraction analysis. For morphological characterization, a scanning electron microscope operated at 20 kV was tilized. Themechanical properties of the samples were studied using hardness measurements. The variations in the hardness data withincreasing aging time were determined based on the structural transformations that take place in the alloys. The ANN modelwas applied to the hardness measurements to simulate and predict the Vickers hardness of Sn-Zn-Cu alloys with mean squareerror values equal 9.55E-06 and 9.44E-06 for training and validation data respectively after 281 epochs. The simulated andpredicted results were consistent with the experimental results.