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Articles 61 - 74 of 74
Full-Text Articles in Physical Sciences and Mathematics
Binary Black Hole Waveform Extraction At Null Infinity, Maria Babiuc-Hamilton, Jeffrey Winicour, Yosef Zlochower
Binary Black Hole Waveform Extraction At Null Infinity, Maria Babiuc-Hamilton, Jeffrey Winicour, Yosef Zlochower
Maria Babiuc-Hamilton
In this paper, we present a work in progress toward an efficient and economical computational module which interfaces between Cauchy and characteristic evolution codes. Our goal is to provide a standardized waveform extraction tool for the numerical relativity community which will allow CCE to be readily applied to a generic Cauchy code. The tool provides a means of unambiguous comparison between the waveforms generated by evolution codes based upon different formulations of the Einstein equations and different numerical approximation.
Gravitational Wave Extraction Based On Cauchy–Characteristic Extraction And Characteristic Evolution, Maria Babiuc-Hamilton, Yosef Zlochower, Béla Szilágyi, Ian Hawke
Gravitational Wave Extraction Based On Cauchy–Characteristic Extraction And Characteristic Evolution, Maria Babiuc-Hamilton, Yosef Zlochower, Béla Szilágyi, Ian Hawke
Maria Babiuc-Hamilton
We implement a code to find the gravitational news at future null infinity by using data from a Cauchy code as boundary data for a characteristic code. This technique of Cauchy–characteristic extraction (CCE) allows for the unambiguous extraction of gravitational waves from numerical simulations. We first test the technique on non-radiative spacetimes: Minkowski spacetime, perturbations of Minkowski spacetime and static black hole spacetimes in various gauges. We show the convergence and limitations of the algorithm and illustrate its success in cases where other wave extraction methods fail. We further apply our techniques to a standard radiative test case for wave …
Testing Numerical Evolution With The Shifted Gauge Wave, Maria Babiuc-Hamilton, Jeffrey Winicour, B´Ela Szilágyi
Testing Numerical Evolution With The Shifted Gauge Wave, Maria Babiuc-Hamilton, Jeffrey Winicour, B´Ela Szilágyi
Maria Babiuc-Hamilton
Computational methods are essential to provide waveforms from coalescing black holes, which are expected to produce strong signals for the gravitational wave observatories being developed. Although partial simulations of the coalescence have been reported, scientifically useful waveforms have so far not been delivered. The goal of the AppleswithApples (AwA) Alliance is to design, coordinate and document standardized code tests for comparing numerical relativity codes. The first round of AwA tests has now been completed and the results are being analyzed. These initial tests are based upon the periodic boundary conditions designed to isolate performance of the main evolution code. Here …
Synthesis Of Al2tio5 And Its Effect On The Properties Of Chitosan-Nh4scn Polymer Electrolytes, Siti Rohana Majid, Hassan F., Woo H. J., Aziz N. A., Kufian M. Z.
Synthesis Of Al2tio5 And Its Effect On The Properties Of Chitosan-Nh4scn Polymer Electrolytes, Siti Rohana Majid, Hassan F., Woo H. J., Aziz N. A., Kufian M. Z.
Siti Rohana Majid
In this paper, Al2TiO5 ceramic material has been synthesised and used as filler in polymer electrolyte system to enhance the conductivity. The precursor sintered at 1,050 A degrees C and contained 0.08 mole of aluminium nitrate gives the best and complete formation of Al2TiO5. Composite polymer electrolytes of chitosan-NH4SCN containing different amount of home-made Al2TiO5 were prepared by solution casting. The addition of filler has enhanced the conductivity of polymer electrolyte. The sample 57 wt% chitosan-38 wt% NH4SCN-5 wt% Al2TiO5 exhibited the highest electrical conductivity of 2.10 x 10(-4) S cm(-1) at room temperature. The presence of the Al2TiO5 creates …
The Effect Of Antimony Trioxide On Poly (Vinyl Alcohol)-Lithium Perchlorate Based Polymer Electrolytes, Siti Rohana Majid, Lim C. S., Ramesh S.
The Effect Of Antimony Trioxide On Poly (Vinyl Alcohol)-Lithium Perchlorate Based Polymer Electrolytes, Siti Rohana Majid, Lim C. S., Ramesh S.
Siti Rohana Majid
A new type of inorganic filler antimony trioxide (Sb2O3) is used to prepare composite polymer electrolytes based on poly (vinyl alcohol) (PVA) and lithium perchlorate (LiClO4) by solution casting technique. The incorporation of Sb2O3 enhances the ionic conductivity at ambient temperature and exhibits the highest ionic conductivity value of 9.51 x 10(-5) S cm(-1) upon the addition of 6 wt% Sb2O3. Thermogravimetric analyses (TGA) reveal that the second weight loss is reduced. This shows the improvement in thermal stability of electrolyte film upon addition of Sb2O3. Differential scanning calorimetry (DSC) analyses show that the glass transition temperature (T-g) value decreases …
A Long-Channel Model For The Asymmetric Double-Gate Mosfet Valid In All Regions Of Operation, Abhishek Kammula, Bradley Minch
A Long-Channel Model For The Asymmetric Double-Gate Mosfet Valid In All Regions Of Operation, Abhishek Kammula, Bradley Minch
Bradley Minch
We present a physically based, continuous analytical model for long-channel double-gate MOSFETs. The model is particularly well suited for implementation in circuit simulators due to the simple expressions for the current andthe continuous nature of the derivatives of the current which improves convergence behavior.
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonochemistry involves focusing acoustic energy through cavitation bubbles to increase chemical activity. The violent bubble collapses lead to temperatures of several thousand kelvin, which drive chemical reactions. In previous work, we gave a detailed computational model of a single bubble collapse, taking into account phase change, mass diffusion, heat diffusion and chemical reactions. All of these phenomena are important in determining the conditions at collapse. The present work involves development of a much simpler model that includes all the physics relevant to the determination of the reaction products. Comparisons with the more detailed computations are made; the reduced model is …
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonoluminescence is the production of light from acoustically forced bubbles; sonochemistry is a related chemical processing technique. The two phenomena share a sensitive dependence on the liquid phase. The present work is an investigation of the fate and consequences of water vapour in the interior of strongly forced argon micro–bubbles. Due to the extreme nonlinearity of the volume oscillations, excess water vapour is trapped in the bubble during a rapid inertial collapse. Water vapour is prevented from exiting by relatively slow diffusion and non–equilibrium condensation at the bubble wall. By reducing the compression heating of the mixture and through primarily …
Ftir Studies Of Pema/Pvdf-Hfp Blend Polymer Electrolyte System Incorporated With Licf3so3 Salt, Siti Rohana Majid, Sim L. N., Arof A. K.
Ftir Studies Of Pema/Pvdf-Hfp Blend Polymer Electrolyte System Incorporated With Licf3so3 Salt, Siti Rohana Majid, Sim L. N., Arof A. K.
Siti Rohana Majid
Poly(ethyl methacrylate), PEMA and poly(vinylidenefluoride-co-hexafluoropropylene). PVdF-HFP have been chosen as hosts for the development of a polymer blend electrolyte system. Lithium trifluoromethanesulfonate (triflate), LiCF3SO3 is the lithium ion, Li+ provider. The ratio of PEMA:PVdF-HFP in the blend is fixed at 70:30 in order to obtain transparent films with good mechanical stability. The polymers and LiCF3SO3 salt have been refluxed for 2 h at temperatures between 55 and 65 degrees C. The concentration of LiCF3SO3 salt has been varied from 0 to 40 wt.%. Fourier transform infrared (FTIR) spectroscopy has shown that blending between PEMA and PVdF-HFP has occurred from the …
Pmma-Libob Gel Electrolyte For Application In Lithium Ion Batteries, Siti Rohana Majid, Kufian M. Z., Aziz M. F., Shukur M. F., Rahim A. S., Ariffin N. E., Shuhaimi N. E. A., Yahya R., Arof A. K.
Pmma-Libob Gel Electrolyte For Application In Lithium Ion Batteries, Siti Rohana Majid, Kufian M. Z., Aziz M. F., Shukur M. F., Rahim A. S., Ariffin N. E., Shuhaimi N. E. A., Yahya R., Arof A. K.
Siti Rohana Majid
Different amounts of lithium bis(oxalato) borate (LiBOB) have been added into a mixture of equal weights of ethylene carbonate (EC) and propylene carbonate (PC). The variation of molar conductivity of the LiBOB based liquid electrolyte with square root of salt concentration obeys the weak electrolyte theory. The 0.6 M LiBOB in EC/PC liquid electrolyte with highest room temperature conductivity of 4.8 mS cm(-1) was chosen for further work. 10 to 50 wt.% PMMA was added to this composition and heated between 343 and 353 K for 20 min to obtain the gel polymer electrolytes (GPEs). Due to its dry state …
Graphene Oxide And Its Electrochemical Performance, Siti Rohana Majid, Ban F. Y., Huang N. M., Lim H. N.
Graphene Oxide And Its Electrochemical Performance, Siti Rohana Majid, Ban F. Y., Huang N. M., Lim H. N.
Siti Rohana Majid
In this study, graphene oxide (GO) was synthesized from graphite flakes using simplified Hummer's method. Field Emission Scanning Electron Microscopy (FESEM) image showed that the GO nanosheets had an average area 7000 mu m(2) with lateral dimension of up to 150 mu m. The X-Ray Diffraction (XRD) pattern revealed a (002) diffraction peak, signifying the successful synthesis of GO. GO solution was cast on an aluminum (Al) foil placed in a petri dish and left to dry to form an electrode made up of GO film on the Al foil (GO-Al). It was found that GO-Al exhibited equivalent series resistance …
Conduction And Thermal Properties Of A Proton Conducting Polymer Electrolyte Based On Poly (Epsilon-Caprolactone), Siti Rohana Majid, Woo H. J., Arof A. K.
Conduction And Thermal Properties Of A Proton Conducting Polymer Electrolyte Based On Poly (Epsilon-Caprolactone), Siti Rohana Majid, Woo H. J., Arof A. K.
Siti Rohana Majid
A proton conducting polymer electrolyte based on poly(epsilon-caprolactone) (PCL) complexed with different concentrations of ammonium thiocyanate (NH(4)SCN) salt has been investigated. The ionic conductivity of the solid polymer electrolyte (SPE) of pure PCL obtained at room temperature is 1.86 x 10(-11) S cm(-1). The maximum ionic conductivity achieved in the solution-cast films at room temperature is 1.01 x 10(-4) S cm(-1) for PCL incorporated with 26 wt.% NH(4)SCN. The calculated dielectric constant at selected frequencies follows the same trend as conductivity, concluding an increase in number density of ions with the salt content. DSC thermogram shows that the degree of …
Transport Studies Of Nh4no3 Doped Methyl Cellulose Electrolyte, Siti Rohana Majid, Shuhaimi N. E. A., Teo L. P., Arof A. K.
Transport Studies Of Nh4no3 Doped Methyl Cellulose Electrolyte, Siti Rohana Majid, Shuhaimi N. E. A., Teo L. P., Arof A. K.
Siti Rohana Majid
This work reports on the transport properties of NH4NO3 doped methyl cellulose (MC) polymer electrolyte. The polymer electrolyte films were prepared by the technique of solvent casting. The highest room temperature conductivity of MC doped with 25 wt.% NH4NO3 is 2.10 +/- 0.37 x 10(-6) S cm(-1). Conductivity-temperature relationship obeys the Vogel-Tamman-Fulcher (VTF) rule from which the glass transition temperature, T-g was evaluated. The mobility, p and number density of charge carrier, n were calculated using the Rice and Roth model. (C) 2010 Elsevier B.V. All rights reserved.
Characteristics Of Methyl Cellulose-Nh4no3-Peg Electrolyte And Application In Fuel Cells, Siti Rohana Majid, Shuhaimi N. E. A., Alias N. A., Kufian M. Z., Arof A. K.
Characteristics Of Methyl Cellulose-Nh4no3-Peg Electrolyte And Application In Fuel Cells, Siti Rohana Majid, Shuhaimi N. E. A., Alias N. A., Kufian M. Z., Arof A. K.
Siti Rohana Majid
We report the viability of methyl cellulose (MC) as a membrane in a polymer electrolyte membrane fuel cell (PEMFC). Methyl cellulose serves as the polymer host, ammonium nitrate (NH4NO3) as the doping salt and poly(ethylene glycol) (PEG) as plasticizer. Conductivity measurement was carried out using electrochemical impedance spectroscopy. The room temperature conductivity of pure MC film is is (3.08 +/- 0.63) x 10(-11)S cm(-1). The conductivity increased to (2.10 +/- 0.37) x 10(-6)S cm(-1) on addition of 25 wt.% NH4NO3. By adding 15 wt.% of PEG 200 to the highest conducting sample in the MC-NH4NO3 system, the conductivity was further …