Physics Commons^™

Hydro-Thermal Convective Solutions For An Aquifer System Heated From Below, Dambaru Bhatta

Applications and Applied Mathematics: An International Journal (AAM)

We investigate the effect of hydro-thermal convection in an aquifer system. It is assumed that the aquifer is bounded below and above by impermeable boundaries and it is heated from below. The solution of the governing system is expressed in terms of the basic steady state solution and perturbed solution. We obtain the critical Rayleigh number and critical wavenumber using Runge-Kutta method in combination of shooting method and present the marginal stability curve. The amplitude equation is derived by introducing the adjoint system. After amplitude is obtained, we compute the linear solutions for super-critical and sub-critical cases. Numerical results for …

Fluctuating Flow Of Thermomicropolar Fluid Past A Vertical Surface, Md. M. Hossain, M. A. Mandal, N. C. Roy, M. A. Hossain

Applications and Applied Mathematics: An International Journal (AAM)

The unsteady free convection boundary layer flow of a thermo-micropolar fluid along a vertical plate has been investigated in this paper. The temperature of the plate is assumed to be oscillating about a mean temperature, θ_w(x), with small amplitude ε. The governing boundary layer equations are analyzed using straight forward finite difference method. The effects of the material parameters such as micropolar heat conduction parameter, N*, the vortex viscosity parameter, K, on the shear stress,𝛕_w, surface heat transfer, q_w, and the couple-stress, m_w, have been investigated.

Generalised Separable Solution Of Double Phase Flow Through Homogeneous Porous Medium In Vertical Downward Direction Due To Difference In Viscosity, A. K. Parikh, M. N. Mehta, V. H. Pradhan

Applications and Applied Mathematics: An International Journal (AAM)

In this paper the instability (fingering) phenomenon in a double phase immiscible (oil and water) flow through the homogeneous porous medium with mean capillary pressure in the vertical downward direction is discussed. The mathematical formulation of this problem yields a nonlinear partial differential equation and the generalised separable solution is given in the exponential form. The numerical solution and graphical presentation is given using MAT LAB coding.

Winter Climatology Of Short-Period Mesospheric Gravity Waves Over Alaska, Michael Negale, Kim Nielsen, Michael J. Taylor, Dominique Pautet

Physics Student Research

Momentum deposition by short-period (<1 h) gravity waves is known to play a major role in the global circulation in the mesosphere and lower thermosphere (MLT) region ~80-100 km (e.g. Fritts and Alexander, 2003). Observations of these waves over the Arctic region are few and their impact on the Arctic MLT region is of high interest, but has yet to be determined. The Mesospheric Airglow Imaging and Dynamics (MAID) project was initiated in January 2011 to investigate short-period gravity wave dynamics over central Alaska.

In this poster, we focus on quantifying the climatology of short-period gravity waves during two winter seasons (2011-2012) over central Alaska

Thermal Convection In A Couple-Stress Fluid In The Presence Of Horizontal Magnetic Field With Hall Currents, Jaimala And Vikrant, Vivek Kumar

Applications and Applied Mathematics: An International Journal (AAM)

The thermal stability of a couple-stress fluid is considered to include the effects of uniform horizontal magnetic field and Hall currents. The analysis is carried out within the framework of linear stability theory and normal made technique. For the case of stationary convection, magnetic field has stabilizing effect whereas Hall currents are found to have destabilizing effect on the system. The couple stress, however, has dual character in contrast to its stabilizing effect in the absence of Hall currents. Oscillatory modes are not allowed in the system. Graphs in each case have been plotted by giving numerical values to the …

Bianchi Type I Magnetized Cosmological Model With Λ-Term In Bimetric Theory Of Gravitation, M. S. Borkar, S. S. Charjan

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, we investigated Bianchi Type I magnetized cosmological model with cosmological constant in Rosen’s bimetric theory of gravitation by using the techniques of Letelier and Stachel. The nature of the model is discussed in presence as well as in absence of the magnetic field and cosmological constant. Our model exists and it never goes to vacuum if cosmological constant is not equal to zero and for finite value of cosmic time. In the presence of magnetic field, our model goes to vacuum when the cosmic time tends to minus infinity. Further in the absence of magnetic field the …

The Onset Of Stationary And Oscillatory Convection In A Horizontal Porous Layer Saturated With Viscoelastic Liquid Heated And Soluted From Below: Effect Of Anisotropy, Vipin K. Tyagi, Jaimala ., S. C. Agrawal

Applications and Applied Mathematics: An International Journal (AAM)

The onset of double diffusive stationary and oscillatory convection in a viscoelastic Oldroyd type fluid saturated in an anisotropic porous layer heated and soluted from below is studied. The flow is governed by the extended Darcy model for Oldroyd fluid. Stability analysis based on the method of perturbations of infinitesimal amplitude is performed using the normal mode technique. The analysis examines the effect of the Darcy Rayleigh number, the solutal Darcy the Rayleigh number, the relaxation time, the retardation time and the Lewis number. Important conclusions include the destabilizing effect of the relaxation time, the Darcy Rayleigh number and the …

Chemical Reaction And Hall Effects On Mhd Convective Flow Along An Infinite Vertical Porous Plate With Variable Suction And Heat Absorption, S. Masthanrao, K. S. Balamurugan, S. V. K. Varma, V. C. C. Raju

Applications and Applied Mathematics: An International Journal (AAM)

In this paper an attempt is made to study the chemical reaction and combined buoyancy effects of thermal and mass diffusion on MHD convective flow along an infinite vertical porous plate in the presence of Hall current with variable suction and heat generation. A uniform magnetic field is applied in a direction normal to the porous plate. The equations governing the fluid flow are solved using the perturbation technique and the expressions for the velocity, the temperature and the concentration distributions have been obtained. Dimensionless velocity, temperature and concentration profiles are displayed graphically for different values of the parameters entering …

Simulation Of Electronic Processes Of Nanoenergetic Gas Generator Using Cabrera Mott Oxidation Model, Zamart Ramazanova

Theses and Dissertations - UTB/UTPA

This research study is a theoretical framework for understanding rapid thermal processes which occur during the performance of new Nanoenergetic Gas-Generators (NGG) systems that rapidly release a large amount of gaseous products and generate a fast-moving thermal wave during the explosion. The kinetics of rapid oxidation of metal nanoparticles acquires practical importance with the quickly developing nanoenergetic systems. The thin film oxidation theory of Cabrera-Mott model was examined for a spherically symmetric case and used to analyze the physical importance of the exothermic processes for prediction of the reaction time and front velocity. A rapid kinetic of oxide growth on …

Theoretical Modeling Of Near-Threshold Shape Resonance Behaviour In Photodetachment Experiments, Laurentiu Dan Dumitriu

Masters Theses

This thesis attempts to better understand the results obtained from photodetachment experiments of Fe-, made by the Western Michigan University experimental atomic physics group at the Advanced Light Source (ALS), Lawrence Berkeley National laboratory.

After a relevant description of the quantum mechanics and theoretical atomic physics concepts and formulas involved in this subject, a physically realistic model, based on the square well potential, is developed. Based on this model, the theoretical photodetachment cross section is computed in order to reproduce the qualitative behavior of the experimental photodetachment cross section measured at ALS.

This development, involving programming in Fortran and numerical …

Analysis Of An Unusual Liquid Crystal Phase Transition, Loni Ann Fuller

Physics

Liquid crystals are a unique phase of matter that resemble a state between a solid and liquid. Within these properties, liquid crystal molecules have the ability to align and create layers. From this phenomenon, many electro-optical effects can be investigated, such as measuring the tilt angle between molecules at different temperatures and applied electric fields and also measuring the birefringence, which is a unique property of liquid crystals in which the index of refraction of the sample behaves differently along different axes. In order to better understand these electro- optical effects, we designed a more precise protocol of measuring this …

Nbconvert Refactor, Jonathan Frederic

Physics

IPython is an interactive Python computing environment. It provides an enhanced interactive Python shell. The IPython Notebook is a browser based interface distributed with IPython. It enables the creation of richly formatted notebooks that contain embedded IPython code. With nbconvert, notebooks can be exported to various formats including, but not limited to, LaTeX, reveal.js, RST, and HTML. This is important for users that want to be able to share their work outside of IPython. This senior project is the addition of a Sphinx LaTeX output format and the refactor of nbconvert.

Organic Solar Cells Based On High Dielectric Constant Materials: An Approach To Increase Efficiency, Khalil Jumah Tawfiq Hamam

Dissertations

The efficiency of organic solar cells still lags behind inorganic solar cells due to their low dielectric constant which results in a weakly screened columbic attraction between the photogenerated electron-hole system, therefore the probability of charge separating is low. Having an organic material with a high dielectric constant could be the solution to get separated charges or at least weakly bounded electron-hole pairs. Therefore, high dielectric constant materials have been investigated and studied by measuring modified metal-phthalocyanine (MePc) and polyaniline in pellets and thin films. The dielectric constant was investigated as a function of temperature and frequency in the range …

A 3-D Model Of The Auroral Ionosphere, Yishi Lee

Doctoral Dissertations and Master's Theses

A new 3-D model of the high latitude ionosphere is developed to study the coupling of the ionosphere with the magnetosphere and neutral atmosphere. The model consists of equations describing conservations of mass, momentum and energy for the six ionospheric constituents (O+, NO+, N+2 , O+2 , N+ and e-) and an electrostatic potential equation. This 3-D model is used to examine interrelated processes of ion heating, plasma structuring due to perpendicular transport, ion upflow, molecular ion generation, and neutral wave forcing. It is first validated by comparisons with a 2-D model, which uses similar mathematical and numerical approaches, and …

System-Size Dependence Of Transverse Momentum Correlations At √ S N N = 62.4 And 200 Gev At The Bnl Relativistic Heavy Ion Collider, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, S. Bültmann, I. Koralt

Physics Faculty Publications

We present a study of the average transverse momentum (P_t) fluctuations and pt correlations for charged particles produced in Cu+Cu collisions at midrapidity for √sNN= 62.4 and 200 GeV. These results are compared with those published for Au+Au collisions at the same energies, to explore the system size dependence. In addition to the collision energy and system size dependence, the P_t correlation results have been studied as functions of the collision centralities, the ranges in P_t, the pseudorapidity η, and the azimuthal angle ϕ. The square root of the measured P_t correlations when scaled …

The Lick Agn Monitoring Project 2011: Fe Ii Reverberation From The Outer Broad-Line Region, Aaron J. Barth, Anna Pancoast, Vardha N. Bennert, Brendon J. Brewer, Gabriela Canalizo, Alexei V. Filippenko, Elinor L. Gates, Jenny E. Greene, Weidong Li, Matthew A. Malkan, David J. Sand, Daniel Stern, Tommaso Treu, Jong-Hak Woo, Roberto J. Assef, Hyun-Jin Bae, Tabitha Buehler, S. Bradley Cenko, Kelsey I. Clubb, Michael C. Cooper, Aleksander M. Diamond-Stanic, Sebastian F. Hönig, Michael D. Joner, C. David Laney, Mariana S. Lazarova, A. M. Nierenberg, Jeffrey M. Silverman, Erik J. Tollerud, Jonelle L. Walsh

Physics

The prominent broad Fe ii emission blends in the spectra of active galactic nuclei have been shown to vary in response to continuum variations, but past attempts to measure the reverberation lag time of the optical Fe ii lines have met with only limited success. Here we report the detection of Fe ii reverberation in two Seyfert 1 galaxies, NGC 4593 and Mrk 1511, based on data from a program carried out at Lick Observatory in Spring 2011. Light curves for emission lines including Hβ and Fe ii were measured by applying a fitting routine to decompose the spectra into …

Raman Spectroscopic Analysis Of Human Skin Tissue Sections Ex-Vivo: Evaluation Of The Effects Of Tissue Processing And Dewaxing, Syed Mehmood Ali, Franck Bonnier, Ali Tfayli, Helen Lambkin, Kathleen Flynn, Vincent Mcdonagh, Claragh Healy, Thomas Lee, Fiona Lyng, Hugh Byrne

Articles

Raman spectroscopy coupled with K-means clustering analysis (KMCA) is employed to elucidate the biochemical structure of human skin tissue sections, and the effects of tissue processing. Both hand and thigh sections of human cadavers were analysed in their unprocessed and formalin fixed paraffin processed (FFPP) and subsequently dewaxed forms. In unprocessed sections, KMCA reveals clear differentiation of the stratum corneum, intermediate underlying epithelium and dermal layers for sections from both anatomical sites. The stratum corneum is seen to be relatively rich in lipidic content; the spectrum of the subjacent layers is strongly influenced by the presence of melanin, while that …

Investigations Into B-O Defect Formation-Dissociation In Cz-Silicon And Their Effect On Solar Cell Performance, Prakash M. Basnyat

Dissertations

About 30% of the total market share of industrial manufacture of silicon solar cells is taken by single crystalline Czochralski (CZ) grown wafers. The efficiency of solar cells fabricated on boron-doped Czochralski silicon degrades due to the formation of metastable defects when excess electrons are created by illumination or minority carrier injection during forward bias. The recombination path can be removed by annealing the cell at about 200° C but recombination returns on exposure to light.

Several mono-crystalline and multi-crystalline solar cells have been characterized by methods such as laser beam induced current (LBIC), Four-Probe electrical resistivity etc. to better …

Mechanical, Electronic And Optical Properties Of Multi-Ternary Semiconductor Alloys, Dongguo Chen

Dissertations

The ability to obtain tunable properties with composition makes multi-ternary alloys extremely useful for a variety of applications in semiconductor devices and is of significant interest in experimental and theoretical research. This dissertation investigates the mechanical, electronic and optical properties of multi-ternary, i.e., binary, ternary and quaternary, semiconductor alloys using analytical methods and first-principles calculations.

For the calculations of mechanical properties, existing models on the average shear modulus of III-V & II-VI binary semiconductors are revised. New expressions are developed for the average Young’s modulus as well as the shear modulus and Young’s modulus on (111) plane for these compounds. …

Study Of Deep Level Defects Of N+-Cds/P-Cdte Solar Cells, Poonam Rani Kharangarh

Dissertations

Among various photovoltaic materials, polycrystalline cadmium telluride thin film is now the most promising material, due to its low production cost excellent stability and reliability. Current-voltage and capacitance-voltage measurements of CdTe photovoltaic devices at different temperatures can provide valuable information about non-idealities in the n-p semiconductor junction. There are certain limitations which limit the efficiency of CdTe solar cells. There is no real distinction between defects and impurities in CdTe solar cells as both act as beneficial dopants or detrimental traps unlike Si where intentional shallow dopants and traps are distinctly different. Therefore, the role of defect states on CdTe …

A Statistical Study Of Plasmawaves And Energetic Particles In The Outer Magnetosphere, Kyungguk Min

Dissertations

The Earth magnetosphere contains energetic particles undergoing specific motions around Earth’s magnetic field, and interacting with a variety of waves. The dynamics of energetic particles are often described in terms of three kinds of adiabatic invariants. Energetic electrons are often unstable to the whistler-mode chorus waves, and ions, to the electromagnetic ion cyclotron (EMIC) instability. These waves play an important role in the dynamics of the magnetosphere by energizing electrons to form a radiation belt, extracting energy from the hot, anisotropic ions and causing pitch angle scattering of energetic ions and relativistic electrons into the loss cone. EMIC waves correspond …

Validation Of Solar Flare Forecasting & Evolution Of Magnetic Helicity Of Two Active Regions, Qin Li

Theses

This thesis includes two components: (1) Validation of the NJIT flare-forecasting model that was established in recent years is carried out based on the statistical correlation between solar magnetic parameters and flare productivity of active regions (ARs). 378 ARs are examined, comparing observation with prediction. It is found that the accuracy rate to some extent decreases with the level of flares. (2) The temporal evolution of the relative magnetic helicity of two ARs, AR 11072 and 11158 is investigated. The former is flare-quiet while the latter is flare-productive over the 5-day observation period. It is found that for both regions, …

Testing The Well-Posedness Of Characteristic Evolution Of Scalar Waves, Maria Babiuc-Hamilton, Heinz Otto Kreiss, Jeffrey Winicour

Physics Faculty Research

Recent results have revealed a critical way in which lower order terms affect the well-posedness of the characteristic initial value problem for the scalar wave equation. The proper choice of such terms can make the Cauchy problem for scalar waves well posed even on a background spacetime with closed lightlike curves. These results provide new guidance for developing stable characteristic evolution algorithms. In this regard, we present here the finite difference version of these recent results and implement them in a stable evolution code. We describe test results which validate the code and exhibit some of the interesting features due …

Spectro-Astrometry Of Water In Dr Tauri, Logan Brown, Matthew Troutman, Erika Gibb

Physics Faculty Works

We present high-resolution, near-infrared spectro-astrometric (SA) data for the T Tauri star DR Tau using NIRSPEC at the Keck II telescope. Spectro-astrometry obtains sub-seeing spatial information from emission lines originating in a non-point source object, such as a circumstellar disk. We report the first detection of water SA signatures in a protoplanetary disk. Three water features near 3 μm were averaged together to produce the total signal analyzed. Using a disk model, we constrained the position angle of the disk (~140°), the inclination of the disk (~13°), and the emitting region of the emission lines (~0.056-0.38 AU).

Search For The Standard Model Higgs Boson Produced In Association With A Top-Quark Pair In Pp Collisions At The Lhc, The Cms Collaboration, M. M. Baarmand, B. Dorney, M. Hohlmann, H. Kalakhety, F. Yumiceva

Aerospace, Physics, and Space Science Faculty Publications

search for the standard model Higgs boson produced in association with a top-quark pair is presented using data samples corresponding to an integrated luminosity of 5.0 fb−1 (5.1 fb−1) collected in pp collisions at the center-of-mass energy of 7 TeV (8 TeV). Events are considered where the top-quark pair decays to either one lepton+jets (tt → .eνqqlbb) or dileptons (tt → .e+ν.e−νbb), .e being an electron or a muon. The search is optimized for the decay mode H → bb. The largest background to the ttH signal is top-quark pair production with additional jets. Artificial neural networks are used to …

Local Quantum Protocols For Separable Measurements With Many Parties, Scott M. Cohen

Physics Faculty Publications and Presentations

In a recent paper [ S. M. Cohen Phys. Rev. A 84 052322 (2011)], we showed how to construct a protocol for implementing a bipartite, separable quantum measurement using only local operations on subsystems and classical communication between parties (LOCC) within any fixed number of rounds of communication, whenever such a protocol exists. Here, we generalize that construction to one that applies for any number of parties. One important observation is that the construction automatically determines the ordering of the parties' measurements, overcoming a significant apparent difficulty in designing protocols for more than two parties. We also present various other …

Rotman Institute Speaker: Feminist Neo-Materialism And The Future Of Phenomenology, Dorothea Olkowski

Future Directions in Feminist Phenomenology

No abstract provided.

Discontinuities And Alfvenic Fluctuations In The Solar Wind, G. Paschmann, S. Haaland, B. Sonnerup, T. Knetter

Dartmouth Scholarship

We examine the Alfvenicity of a set of 188 solar wind directional discontinuities (DDs) identified in the Cluster data from 2003 by Knetter (2005), with the objective of separating rotational discontinuities (RDs) from tangential ones (TDs). The DDs occurred over the full range of solar wind velocities and magnetic shear angles. By performing the Walen test in the de Hoffmann–Teller (HT) frame, we show that 77 of the 127 crossings for which a good HT frame was found had plasma flow speeds exceeding 80 % of the Alfven speed at an average angular deviation of 7.7◦; 33 cases had speeds …

Effects Of Localized Trap-States And Corrugation On Charge Transport In Graphene Nanoribbons, Oleksiy Roslyak, Upali Aparajita, Godfrey Gumbs, Danhong Huang

Publications and Research

We investigate effects of the electron traps on adiabatic charge transport in graphene nanoribbons under a longitudinal surface acoustic wave (SAW) potential. Due to the weak SAW potential and strong transverse confinement of nanoribbons, minibands of sliding tunnel-coupled quantum dots are formed. Therefore, as the chemical potential passes through minigaps, quantized adiabatic charge transport is expected to occur. We analyze the condition for a closed minigap, thereby destroying the current quantization in a nanoribbon. We present numerical calculations showing the localized energy states within minigaps. Additionally, we compare the results with the minibands of corrugated nanoribbons.

Estimations Of The Magnetic Field Strength In The Torus Of Ic 5063 Using Near-Infrared Polarimetry, E. Lopez-Rodriguez, C. Packham, S. Young, Moshe Elitzur, N. A. Levenson, R. E. Mason, C. Ramos Almeida, A. Alonso-Herrero, T. J. Jones, E. Perlman

Physics and Astronomy Faculty Publications

An optically and geometrically thick torus obscures the central engine of active galactic nuclei (AGN) from some lines of sight. From a magnetohydrodynamical framework, the torus can be considered to be a particular region of clouds surrounding the central engine where the clouds are dusty and optically thick. In this framework, the magnetic field plays an important role in the creation, morphology and evolution of the torus. If the dust grains within the clouds are assumed to be aligned by paramagnetic alignment, then the ratio of the intrinsic polarization and visual extinction, P(per cent)/A_v, is a …