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Full-Text Articles in Physical Sciences and Mathematics
Wave Profile For Current Bearing Lightning Strokes, Baylee Landers, M Hemmati, Ali Alzhrani
Wave Profile For Current Bearing Lightning Strokes, Baylee Landers, M Hemmati, Ali Alzhrani
Journal of the Arkansas Academy of Science
The propagation of breakdown waves in a gas, which is primarily driven by electron gas pressure, is described by a one-dimensional, steady-state, three-component (electrons, ions, and neutral particles) fluid model. This study will involve waves propagating in the opposite direction of the electric field force on electrons (anti-force waves—lightning return stroke) only. We consider the electron gas partial pressure to be much larger than that of the other species and the waves to have a shock front. Our set of equations consists of the equations of conservation of the flux of mass, momentum, and energy coupled with the Poisson’s equation. …
Generation Of Generalized-Gauss Laser Beams Via A Spatial Light Modulator, Jessica P. Conry Young, Samantha Dix
Generation Of Generalized-Gauss Laser Beams Via A Spatial Light Modulator, Jessica P. Conry Young, Samantha Dix
Journal of the Arkansas Academy of Science
Generalized-Gauss laser beams can be described as a continuous transition between the well-known Hermite-Gauss (HG) and Laguerre-Gauss (LG) laser beams. A spatial light modulator (SLM) was made by removing the liquid crystal display (LCD) from an overhead projector. The homemade SLM, encoded with a computer-generated hologram, was then used to convert a fundamental Gaussian beam from a small frame Helium-Neon (HeNe) laser into several different orders of Generalized-Gauss (GG) beams. The experimentally generated GG beam profiles matched the theoretically expected profiles.
Comparison Of Various Mean Field Formulations For Retrieving Refractive Indices Of Aerosol Particles Containing Inclusions, Kristin S. Dooley, Jessica Deyoung
Comparison Of Various Mean Field Formulations For Retrieving Refractive Indices Of Aerosol Particles Containing Inclusions, Kristin S. Dooley, Jessica Deyoung
Journal of the Arkansas Academy of Science
Application of effective medium approximation (EMA) methods to two-component systems are presented. Systems studied are composed of water, sulfate, soot, and dust as these are commonly encountered atmospheric aerosol components. Atmospheric models often employ EMAs to include internally mixed aerosols without the computational burden of exact theory. In the current work, several types of mixing rules (Maxwell-Garnet, Bruggeman, and coherent potential approximation) have been applied to various two-component internally mixed particles at 550 nm using volume fractions of the minor component below 0.1. As expected, results show that the formulations tested produce very similar effective refractive indices indicating that electric …
Electron Shock Waves With A Large Current Behind The Shock Front, H. D. Newberry, M. Hemmati, H. D. Moore, K. Ledbetter, M. W. Bowman
Electron Shock Waves With A Large Current Behind The Shock Front, H. D. Newberry, M. Hemmati, H. D. Moore, K. Ledbetter, M. W. Bowman
Journal of the Arkansas Academy of Science
The propagation of breakdown waves in a gas, which is primarily driven by electron gas pressure, is described by a one-dimensional, steady-state, three-component (electrons, ions, and neutral particles) fluid model. We consider the electron gas partial pressure to be much larger than that of the other species and the waves to have a shock front. Our set of equations consists of the equations of conservation of the flux of mass, momentum, and energy coupled with Poisson’s equation. This set of equations is referred to as the electron fluid dynamical equations. In this study we are considering breakdown waves propagating in …
Characterizing Nanoparticle Size By Dynamic Light Scattering, M. Zaman, S. Ang, S. Singh
Characterizing Nanoparticle Size By Dynamic Light Scattering, M. Zaman, S. Ang, S. Singh
Journal of the Arkansas Academy of Science
The Dynamic Light Scattering (DLS) Technique was used to determine the size, shape and diffusion coefficient of rod-like nanoparticles. The intensity auto-correlation functions of light scattered by particles in a solution were measured and analyzed to obtain the relaxation rates for decay of intensity correlations. These decay rates are related to the diffusion coefficients pertaining to the motion of the particle. In the case of nanorods, there are two types of motion - translational and rotational. By disentangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticles were characterized. These experiments, though limited …
Solid State Dye Sensitive Solar Cells Based On Zno Nanowire As The N-Type Semiconductor, S. Abdulalmohsin
Solid State Dye Sensitive Solar Cells Based On Zno Nanowire As The N-Type Semiconductor, S. Abdulalmohsin
Journal of the Arkansas Academy of Science
We fabricated solid state dye-sensitized solar cells with ZnO nanorods as the n-type material and polypyrrole as the p-type material. The ZnO nanorods were grown on indium-tin oxide (ITO) glass by electrochemical methods for one hour. Scanning electron micrographs of the ZnO nanowire (NW) indicated a length of about 1 micrometer and a diameter of approximately 100-200 nm for the nanorods. Polypyrrole deposited on ITO/ZnO NW/dye and the fabricated device of ITO glass/ZnO nanorods/dye/polypyrrole/Ag showed a power conversion efficiency of 1.29%.
Synthesis And Optical Properties Of Sprayed Zno And Zno:Ga Thin Films, N. F. Habubi, S. S. Chiad, S. Jabbar, W. Jabbar
Synthesis And Optical Properties Of Sprayed Zno And Zno:Ga Thin Films, N. F. Habubi, S. S. Chiad, S. Jabbar, W. Jabbar
Journal of the Arkansas Academy of Science
Characteristics and optical constants of pure and Ga-doped ZnO thin films have been studied. Pure and Ga-doped zinc oxide thin films were deposited onto glass substrates using the spray pyrolysis technique. Optical absorption studies in the wavelength range of 300–900 nm showed a peak near 450 nm for different doped films (in addition to the peak for un-doped ZnO). Increasing the doping concentration of Ga to 7% induced an increase in the optical constants of films. This increase is attributed to the formation of chargetransfer complexes. ZnO thin films doped with Ga have improved the optical transmittance in the visible …
Fabrication And Characterization Of Aluminum-Doped Zno/Pani Hybrid Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Fabrication And Characterization Of Aluminum-Doped Zno/Pani Hybrid Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Journal of the Arkansas Academy of Science
We report a facile method to fabricate an AZO/PANI heterostructure by a sandwiching technique. Aluminum-doped ZnO (AZO) films were deposited onto indium tin oxide (ITO) glass using the sputtering technique while PANI films were deposited onto ITO glass using electropolymerization. The optoelectric properties of the inorganic/organic device were characterized
Current Range In Lightning Return Strokes, M. Hemmati, W. P. Childs, D. C. Waters, J. R. Christensen, B. C. Richard
Current Range In Lightning Return Strokes, M. Hemmati, W. P. Childs, D. C. Waters, J. R. Christensen, B. C. Richard
Journal of the Arkansas Academy of Science
In our investigation of breakdown waves, we use a one-dimensional, steady-state, constant velocity fluid model. This investigation involves breakdown waves for which the electric field force on electrons is in the opposite direction of wave propagation. The waves are considered to be shock fronted and the electron gas partial pressure is large enough to sustain the wave propagation. Our basic set of electron fluid-dynamical equations is composed of the equations for conservation of mass, momentum and energy, coupled with Poisson’s equation. This investigation involves breakdown waves for which a large current exists behind the shock front. The current behind the …
Electrochemical Polymerization Of Ppy-Mwcnt Composite As A Counter Electrode For Dye-Sensitized Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Electrochemical Polymerization Of Ppy-Mwcnt Composite As A Counter Electrode For Dye-Sensitized Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Journal of the Arkansas Academy of Science
Polypyrrole (PPy) - multi wall carbon nanotube (MWCNT) nanocomposites were synthesized by using in situ electrochemical polymerization with different COOH-functionalized MWCNTs. The PPY-MWCNT composites were used as counter electrode in the fabrication of dye sensitized solar cells (DSCs). Compared to the DSC device with PPy counter electrode, the devices with PPY/MWCNT composite electrode offer much higher total photovoltaic conversion efficiency due to the reduced series resistance. These PPY/MWCNT nanocomposite materials proved to be a good alternate to the expensive Pt as counter electrode in DSC.
Al/Pani-Mwnt/Au-Plastic Schottky Diode Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Al/Pani-Mwnt/Au-Plastic Schottky Diode Solar Cells, S. Abdulalmohsin, S. M. Al-Mutoki, Z. Li
Journal of the Arkansas Academy of Science
Al/PANI-MWNT/Au-Plastic Schottky diode solar cells were fabricated by the electrochemical polymerization technique to make polyaniline films on the top of gold nanoparticles film. The aluminum contact was deposited by thermal evaporation. The electro-optical characteristics of these devices produced at the different polymerization time were compared. Here, we achieved the highest ever reported open-circuit voltage of 0.8 V with the electrochemical polymerization technique. The polymerization of polyaniline films was thought to be a major factor in the enhanced performance. The effects of varying the polyaniline thickness on the device performance were investigated
Effects Of Annealing On The Electronic Transitions Of Zns Thin Films, S. S. Chiad, W. A. Jabbar, N. F. Habubi
Effects Of Annealing On The Electronic Transitions Of Zns Thin Films, S. S. Chiad, W. A. Jabbar, N. F. Habubi
Journal of the Arkansas Academy of Science
Thin films of zinc sulphide were prepared using a flash evaporation technique. The obtained thin films were subjected to heat treatment to investigate the effect of annealing on the transmittance spectrum and the electronic transitions. It has been found that annealing affected the transmission spectrum and caused an increase in the direct optical band gap. The optical parameters, oscillator energy E0 and dispersion energy Ed were determined using the Wemple DiDomenico single oscillator model. The optical energy gap obtained from the Wemple and DiDomenico model was in good agreement with the optical energy gap proposed by the Tauc theory.
Boundary Condition On Electron Temperature For Antiforce Current Bearing Waves, M. Hemmati, W. P. Childs, D. C. Waters, J. D. Counts, J. K. Schmitt
Boundary Condition On Electron Temperature For Antiforce Current Bearing Waves, M. Hemmati, W. P. Childs, D. C. Waters, J. D. Counts, J. K. Schmitt
Journal of the Arkansas Academy of Science
In our investigation of breakdown waves, we apply a one-dimensional, three-component, steady-state fluid model. The wave is considered to be shock fronted and the electrons are assumed to be the main element in propagation of the wave. In our fluid model, the electron gas temperature is assumed to be large enough to sustain the wave motion. Our set of fluid equations is composed of the equations of conservation of mass, momentum and energy plus the Poisson’s equation. This investigation involves breakdown waves for which a large current exist in the vicinity of the wave front. Existence of current behind the …
Synthesis And Characterization Of Ruthenium Complexes Containing Chlorophenanthroline And Bipyridine, Anwar A. Bhuiyan, S. Kudo, J. Bartlett
Synthesis And Characterization Of Ruthenium Complexes Containing Chlorophenanthroline And Bipyridine, Anwar A. Bhuiyan, S. Kudo, J. Bartlett
Journal of the Arkansas Academy of Science
The divalent ruthenium polypyridine complexes hold promise as efficient photocatalysts for solar energy conversion schemes. This paper deals with the synthesis and spectroscopic investigation of ruthenium polypyridine complexes, which may be useful as photosensitizers. The homoleptic ruthenium(II) complex Ru(Cl-phen)3(PF6)2 (where Cl-phen = 5- chloro-1,10-phenanthroline), and heteroleptic ruthenium(II) complexes Ru(Cl-phen)2(bpy)(PF6)2, and Ru(Cl-phen)(bpy)2(PF6)2 (where bpy = 2,2′-bipyridine) have been prepared by following the standard synthetic procedure. Silica and alumina column chromatographies were used to purify the compounds. Mass spectroscopy, nuclear magnetic resonance (nmr) spectroscopy, and elemental analysis were used to confirm the identity and the integrity of the complexes. Absorption and emission …
Optical Characterization Of Silver Doped Poly (Vinyl Alcohol) Films, W. A. Jabbar, N. F. Habubi, S. S. Chiad
Optical Characterization Of Silver Doped Poly (Vinyl Alcohol) Films, W. A. Jabbar, N. F. Habubi, S. S. Chiad
Journal of the Arkansas Academy of Science
Silver-doped PVA films were prepared by casting method in order to study the effect of silver on the optical properties of poly(vinyl alcohol) using UV/VIS spectroscopy. It was found that these thin films have an indirect optical band gap (2.4-1.3) eV as the doping percentage increase. Extinction coefficient and refractive index increase as the doping percentage increase, while in general the optical dispersion parameters show an opposite behavior with doping
Analysis Of Gamma Rays And Cosmic Muons With A Single Detector, A. Bachri, P. C. Grant, A. Goldschmidt
Analysis Of Gamma Rays And Cosmic Muons With A Single Detector, A. Bachri, P. C. Grant, A. Goldschmidt
Journal of the Arkansas Academy of Science
In this paper, we report on the construction and upgrade of a 2002 Lawrence Berkeley National Laboratory (LBNL) Quanknet Cosmic Muons Detector. By adapting this model, we modify the electronics and mechanics to achieve a highly efficient gamma-ray and cosmic-ray detector. Each detector module uses a one-inch-thick scintillator, attached to a photomultiplier tube (PMT) and mounted on a solid aluminum frame. A mechanical support was designed to allow flexible positioning between the two modules. The detector uses scintillation to transform passing radiation into detectable photons that are guided toward a photocathode surface of the PMT, triggering the release of photoelectrons …
Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis
Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis
Journal of the Arkansas Academy of Science
The homoleptic ruthenium(II) complex Ru(C13H10N2)3(PF6)2, and heteroleptic ruthenium(II) complexes Ru(C13H10N2)2(C10H8N2)(PF6)2, and Ru(C13H10N2)(C10H8N2)2(PF6)2 have been prepared by following the standard synthetic procedure. These complexes were then purified by repeated column chromatography. The identity and the integrity of the complexes were confirmed by elemental analysis and mass spectroscopy. The calculated and the experimental values for the elemental analysis were in good agreement. The calculated and the experimental molar masses obtained were also identical. Ultravioletvisible absorption and emission spectroscopic methods were used to investigate the properties of these complexes. The absorption spectra of all complexes consist of a series of absorption bands in …
Ionization Rate, Temperature, And Number Density For Breakdown Waves With A Large Current Behind The Shock Front, S. Norman, Mostafa Hemmati, J. King
Ionization Rate, Temperature, And Number Density For Breakdown Waves With A Large Current Behind The Shock Front, S. Norman, Mostafa Hemmati, J. King
Journal of the Arkansas Academy of Science
A three component, one-dimensional, constant velocity, steady-state fluid model is employed to describe the breakdown waves with a current behind the wave front propagating into a neutral gas subjected to an external electric field. Electron gas partial pressure is much larger than that of the other species and therefore is considered to provide the driving force for the wave. The system of equations includes the equations of conservation of mass, momentum, and energy coupled with Poisson’s equation. Inclusion of current behind the wave front in the system of fluid equations also alters the initial boundary conditions and ionization rate. We …
Resonance Raman Spectroscopy For The Investigation Of Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhiuyan
Resonance Raman Spectroscopy For The Investigation Of Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhiuyan
Journal of the Arkansas Academy of Science
No abstract provided.
Quantifying Soil Chemical Properties Using Near Infrared Reflectance Spectroscopy, Robert L. Ficklin, Shane M. Foley, Robert E. Kissell Jr.
Quantifying Soil Chemical Properties Using Near Infrared Reflectance Spectroscopy, Robert L. Ficklin, Shane M. Foley, Robert E. Kissell Jr.
Journal of the Arkansas Academy of Science
Methodologies for determining soil chemical properties have evolved dramatically during the past century. Early geochemical analyses were conducted exclusively through the use of wet chemistry techniques that were relatively reliable but painstaking and subject to errors at various stages of analysis. Near infrared reflectance spectroscopy (NIRS) has emerged as a new approach for rapidly analyzing a variety of materials including soils. In this study soil samples were taken from eight study areas across the Ozark Highlands of Arkansas, and NIRS calibration models were developed to determine the accuracy of using NIRS to analyze soils compared with standard soil chemical analysis …
Measurement And Modeling Of Light Transmission Through Turbid Media, Alois (Al) J. Adams, Michael Fahrenwald, Long Do
Measurement And Modeling Of Light Transmission Through Turbid Media, Alois (Al) J. Adams, Michael Fahrenwald, Long Do
Journal of the Arkansas Academy of Science
No abstract provided.
Electron Shock Waves: Ionization Rate And Solutions To The Efd Equations, Mostafa Hemmati, Steven Summers, Michael Weller
Electron Shock Waves: Ionization Rate And Solutions To The Efd Equations, Mostafa Hemmati, Steven Summers, Michael Weller
Journal of the Arkansas Academy of Science
This paper describes our numerical investigation into ionizing breakdown waves, primarily antiforce waves. Antiforce waves are waves for which the electric field force on the electronsisin the opposite direction of the wave's propagation. This investigation required us to utilize one-dimensional electron fluid-dynamical equations, which were applied to a pulse wave that transmits into a region of neutral gas and is under the influence of an applied electric field. Two important assumptions were made in applying these equations: electrons were considered to be the main component in the propagation of the pulse wave, and the partial pressure of the electron gas …
Study Of Causal Component Placement In An Active Sound Cancellation System, Eileen Anderson, Andrew B. Wright
Study Of Causal Component Placement In An Active Sound Cancellation System, Eileen Anderson, Andrew B. Wright
Journal of the Arkansas Academy of Science
In a feedforward Active Sound Cancellation (ASC) system, the acoustic delay between a primary source and an error microphone must be greater than the delay between the measurement of that source by the reference microphone and the arrival of the secondary source's wave at the error microphone. Such a configuration is called a causal configuration. For periodic disturbances, cancellation can still be achieved in non-causal configuration. Since the waveform is periodic, each cycle of the waveform is identical, and the cycle being canceled is not the measured part of the waveform, but a subsequent cycle in the waveform. Non-periodic sources …
Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice
Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice
Journal of the Arkansas Academy of Science
The electron gas in electric discharge can be described by a set of one-dimensional fluid dynamical equations. The fundamental equations are those of a three-component (electrons, ions, and neutral particles) fluid, different from the treatment of the problem inplasma physics, a fully ionized two-component case. The leading edge of the wave is treated as a shock front driven mainly by the electron gas pressure. Integrating the one-dimensional global differential equations for mass balance, conservation of momentum and energy, and evaluating the constant of integration at the wave front permits derivation of boundary conditions on electron temperature and electron velocity. Using …
Antiforce Wave Profile For Quasi-Neutral Region, Mostafa Hemmati, Pashupati Adhikari, Jeremy Eckart, Marcus Ilbara
Antiforce Wave Profile For Quasi-Neutral Region, Mostafa Hemmati, Pashupati Adhikari, Jeremy Eckart, Marcus Ilbara
Journal of the Arkansas Academy of Science
This article will present a fluid dynamical theory for breakdown waves in which the direction of electric field force on electrons is in the opposite direction of wave propagation. We will refer to such waves as antiforce waves. The set of equations describing the model will include the equation of particle mass balance, equation of conservation of momentum, and equation of conservation of energy, coupled with Poisson's equation. This model treats the potential wave front as an electron shock wave propagating forward mainly due to the electron impact ionization. The shock front is succeeded by a thin dynamical transition region …
Synthesis Of A Ruthenium-Tetra(Tht)Dichloride Compound And The Molecular Structure Of The Partially Oxidized Compound Rucl2(Tht)2.2(Tht-O)1.8, L. A. Thornton, Mark Draganjac, Andres Meza, A. W. Cordes
Synthesis Of A Ruthenium-Tetra(Tht)Dichloride Compound And The Molecular Structure Of The Partially Oxidized Compound Rucl2(Tht)2.2(Tht-O)1.8, L. A. Thornton, Mark Draganjac, Andres Meza, A. W. Cordes
Journal of the Arkansas Academy of Science
No abstract provided.
Non-Commercial Software For The Analysis And Interpretation Of High Resolution Molecular Spectra, A. R. Ford, Scott W. Reeve
Non-Commercial Software For The Analysis And Interpretation Of High Resolution Molecular Spectra, A. R. Ford, Scott W. Reeve
Journal of the Arkansas Academy of Science
No abstract provided.
Synthesis And Characterization Of A Ruthenium-Thioxane Complex, Amanda Wroble, Scotty Sproles, Mark Draganjac, Paul M. Nave
Synthesis And Characterization Of A Ruthenium-Thioxane Complex, Amanda Wroble, Scotty Sproles, Mark Draganjac, Paul M. Nave
Journal of the Arkansas Academy of Science
No abstract provided.
Wave Profile For Antiforce Class Ii Waves, Rory Roberts, Mostafa Hemmati
Wave Profile For Antiforce Class Ii Waves, Rory Roberts, Mostafa Hemmati
Journal of the Arkansas Academy of Science
Breakdown waves propagating in the opposite direction of the applied electric field force are referred to as antiforce waves. Breakdown waves moving into a pre-ionized medium are referred to as Class II waves. Using a one-dimensional, steady state, three-fluid, hydrodynamical model and considering the electrons as the main element in propagation of ionizing waves, we have derived the proper boundary conditions for antiforce waves moving into a preionized medium. Using the new boundary conditions and for several current values ahead of the wave, the set of electron fluid dynamical equations (equations of conservation of mass, momentum, and energy coupled with …
Speed Range For Breakdown Waves, Mostafa Hemmati, Eric L. George, Frances Terry
Speed Range For Breakdown Waves, Mostafa Hemmati, Eric L. George, Frances Terry
Journal of the Arkansas Academy of Science
Considering the electrons as the main element in breakdown wave propagation and using a one-dimensional, steady-state, three-fluid, hydrodynamical model, previous investigations have resulted in the completion of a set of equations for conservation of mass, momentum, and energy. We will use the terms proforce and antiforce waves, depending on whether the applied electric field force on electrons is with or against the direction of wave propagation. In the case of antiforce waves, the electron gas temperature and therefore the electron fluid pressure is assumed to be large enough to sustain the wave propagation down the discharge tube. For strong discontinuity …