Physical Sciences and Mathematics Commons^™

A Comprehensive Review Of Geometrical Thermodynamics: From Fluctuations To Black Holes, S. Mahmoudi, Kh. Jafarzade, Seyed Hossein Hendi

Turkish Journal of Physics

This paper presents a comprehensive review of geometrical thermodynamics, which employs geometric concepts to study the thermodynamic properties of physical systems. The review covers key topics such as thermodynamic fluctuation theory, proposed thermodynamic metrics in various coordinate systems, and thermodynamic curvature.Additionally, the paper discusses the geometrical approach to black hole thermodynamics and provides an overview of recent research in this field.

The Influence Of Allostery Governing The Changes In Protein Dynamics Upon Substitution, Joseph Hess

All Dissertations

The focus of this research is to investigate the effects of allostery on the function/activity of an enzyme, human immunodeficiency virus type 1 (HIV-1) protease, using well-defined statistical analyses of the dynamic changes of the protein and variants with unique single point substitutions ¹. The experimental data¹ evaluated here only characterized HIV-1 protease with one of its potential target substrates. Probing the dynamic interactions of the residues of an enzyme and its variants can offer insight of the developmental importance for allosteric signaling and their connection to a protein’s function. The realignment of the secondary structure elements can …

Perovskite Solar Cells, Liqiu Zheng Dr., Tyler Hurst, Zhongrui Li

Georgia Journal of Science

The semiconductor perovskite CsPbBr₂I was doped with Mn²⁺ to modulate its optical and photovoltaic performance. The Mn²⁺-doped CsPb_0.9Mn_0.1Br₂I exhibited improved crystalline quality. Ultraviolet and visible spectroscopy of Mn²⁺-doped CsPb_0.9Mn_0.1Br₂I revealed enhanced absorption capacity. Although the efficiency was not as good as desired, the enhanced light absorption of CsPb_0.9Mn_0.1Br₂I still boosted the photovoltaic performance when it was utilized as a light absorber in perovskite solar cells, along with a low-cost carbon electrode. Compared with its counterpart …

Stability Analysis Of Circular Robe’S R3bp With Finite Straight Segment And Viscosity, Bhavneet Kaur, Sumit Kumar, Shipra Chauhan, Dinesh Kumar

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, the effect of viscous force on the linear stability of equilibrium points of the circular Robe’s restricted three-body problem (CRR3BP) with smaller primary as a finite straight segment is studied. The present model comprises of a bigger primary m^*₁ which is a rigid spherical shell filled with a homogeneous incompressible fluid of density ρ₁ and the smaller primary m₂ lies outside the shell. The infinitesimal mass m₃ is a small solid sphere of density ρ₃ moving inside m^*₁. The pertinent equations of motion of m₃ are derived …

Efficient Time-Stepping Approaches For The Dispersive Shallow Water Equations, Linwan Feng

Dissertations

This dissertation focuses on developing efficient and stable (high order) time-stepping strategies for the dispersive shallow water equations (DSWE) with variable bathymetry. The DSWE extends the regular shallow water equations to include dispersive effects. Dispersion is physically important and can maintain the shape of a wave that would otherwise form a shock in the shallow water system.

In some cases, the DSWE may be simplified when the bathymetry length scales are small (or large) in relation to other length scales in the shallow water system. These simplified DSWE models, which are related to the full DSWEs, are also considered in …

Dynamics And Stability Of The Two Body Problem With Yukawa Correction, Eli Cavan, Ioannis Haranas, Ioannis Gkigkitzis

Physics and Computer Science Faculty Publications

We explore the dynamics and stability of the two body problem by modifying the Newtonian potential with the Yukawa potential. This model may be considered a theory of modified gravity; where the interaction is not simply the kepler solution for large distance. The stability is investigated by deriving the Jacobian of the linearized matrix equation and evaluating the eigenvalues of the various equilibrium points calculated during the analysis. The subcases of a purely Yukawa and purely Newtonian potential are also explored.

Electronic And Geometric Structure Of Alnom And Alnom +, Albert R. Armstrong

Theses and Dissertations

Generally, the electronic stability of aluminum clusters is associated with either closed electronic shells of delocalized electrons, or aluminum in the +3 state. To explore alternative routes for electronic stability in aluminum oxide clusters, theoretical methods were used to examine the geometric and electronic structure of Al_nO_m (2≤n≤7; 1≤m≤10) clusters. Two types of electronically stable clusters with large HOMO-LUMO gaps were identified the first being Al_2nO_3m clusters with a +3 oxidation state on the aluminum, and the second being planar clusters such as Al₄O₄, Al₅O₃, Al …

Restricted Three-Body Problem Under The Effect Of Albedo When Smaller Primary Is A Finite Straight Segment, Shipra Chauhan, Dinesh Kumar, Bhavneet Kaur

Applications and Applied Mathematics: An International Journal (AAM)

This paper addresses the dynamics of the infinitesimal body in the restricted three-body problem under the effect of Albedo when the smaller primary is a finite straight segment and bigger one is a source of radiation. The measure of diffusive reflection of solar radiation out of the total solar radiation received by a body is Albedo which is measured on a scale from 0 to 1. The equations of motion of the infinitesimal body are derived and it is found that there exist five libration points, out of which three are collinear and the rest are non-collinear with the primaries. …

Analysis Of Clusterization Of C70 Molecules In Benzene Solutions Prepared By Various Methods, U. Makhmanov, O. Ismailova, A. Kokhkharov, S. Bakhramov

Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences

Self-assembling features of molecules of C₇₀ in benzene solution prepared in two various ways – equilibrium and non-equilibrium – has been investigated experimentally by method of high-resolution transmission electron microscopy. It was demonstrated, that the formation of densely packed monomolecular fullerene aggregates with a diameter of not more than 30 nm in solutions prepared by the equilibrium method (without the use of external mechanical influences on solution). In the case of solutions C₇₀, which were prepared by the non-equilibrium method (stirring of solution of C₇₀ by a mechanical rotator), large quasispherical aggregates of nanoporous structure with …

Molecular Assembly Of Monolayer-Protected Gold Nanoparticles And Their Chemical, Thermal, And Ultrasonic Stabilities, Steven Ray Isaacs

Masters Theses & Specialist Projects

Gold monolayer-protected nanoclusters (MPCs) with average diameters of 1-5 nm protected by alkane- and arenethiolates were synthesized. Mixed-monolayer protected nanoparticles (MMPCs) were prepared by functionalizing hexanethiolate-protected MPCs with either 11-mercaptoundecanoic acid (MUA-MMPC), 11-mercaptoundecanol (MUO-MMPC), or 4-aminothiophenol (ATP-MMPC) using ligand place exchange. Presentation of various chemical reagents such as nucleophile, acid, or base and change in physical environment through ultrasonic and thermal irradiation resulted in changes to particles and their physical properties. Thermogravimetric analysis (TGA) was used to measure maximum temperature of the derivated thermogravimetric peaks (Tmax,DTG) as a means of comparing temperature dependence of mass loss. The absorption spectrum within …

Study Of The Restricted Three Body Problem When One Primary Is A Uniform Circular Disk, Mohd. Arif, Ravi K. Sagar

Applications and Applied Mathematics: An International Journal (AAM)

In this paper we have studied the location and stability of the equilibrium points in the restricted three body problem by taking into consideration the bigger primary as an uniform circular disc. We have observed that there exist six collinear (Li, i = 1::6) and two non-collinear (Li, i = 7; 8) equilibrium points.We have found that the points L1 and L3 move towards the center of mass while L2, L4, L5 and L6 go away from the center of mass as parameter of mass μ increases.We have also observed that the points L1, L2 and L3 move away from …

Is The Quilted Multiverse Consistent With A Thermodynamic Arrow Of Time?, Yakir Aharonov, Eliahu Cohen, Tomer Shushi

Mathematics, Physics, and Computer Science Faculty Articles and Research

Theoretical achievements, as well as much controversy, surround multiverse theory. Various types of multiverses, with an increasing amount of complexity, were suggested and thoroughly discussed in literature by now. While these types are very different, they all share the same basic idea: our physical reality consists of more than just one universe. Each universe within a possibly huge multiverse might be slightly or even very different from the others. The quilted multiverse is one of these types, whose uniqueness arises from the postulate that every possible event will occur infinitely many times in infinitely many universes. In this paper we …

Stability Of Triangular Libration Points In The Sun - Jupiter System Under Szebehely’S Criterion, M. R. Hassan, Md. A. Hassan, M. Z. Ali

Applications and Applied Mathematics: An International Journal (AAM)

In the present study, the classical fourth-order Runge-Kutta method with seventh-order automatic step-size control has been carried out to examine the stability of triangular libration points in the Sun-Jupiter system. The Sun is a highly luminous body and Jupiter is a highly spinning body, so radiation pressure of the Sun and oblateness of the Jupiter cannot be neglected. These factors must have some effects on the motion of the infinitesimal mass (spacecraft) and consequent effects on the stability of the triangular libration points. It is to be noted that in our problem, infinitesimal mass exerts no influence of attraction on …

Orbital Stability Results For Soliton Solutions To Nonlinear Schrödinger Equations With External Potentials, Joseph B. Lindgren

Theses and Dissertations--Mathematics

For certain nonlinear Schroedinger equations there exist solutions which are called solitary waves. Addition of a potential $V$ changes the dynamics, but for small enough $||V||_{L^\infty}$ we can still obtain stability (and approximately Newtonian motion of the solitary wave's center of mass) for soliton-like solutions up to a finite time that depends on the size and scale of the potential $V$. Our method is an adaptation of the well-known Lyapunov method.

For the sake of completeness, we also prove long-time stability of traveling solitons in the case $V=0$.

Structure And Stability Of Primordial Stars, Aysel İbrahi̇m Karafi̇stan

Turkish Journal of Physics

For decades large-scale cosmic structures have been modeled as the gravitational amplification of small-density perturbations of the cosmological recombination epoch of the Big Bang. In astrophysics, cosmological nucleosynthesis is considered responsible for the production of the pristine gas, which should be found in the first-generation stars in the form of hydrogen and helium as the main constituents. In the later type of second-generation stars, hydrogen is converted into helium by the CN-cycle reactions, in which heavier elements are produced. These elements are believed to enrich the intergalactic medium by possible star bursts at the last stages of evolution. Stability criteria …

Well, It's About Time, Daniel David Gagné

Senior Projects Spring 2016

A clock can be thought of as anything that oscillates with a known and stable frequency, and is able to count its oscillations. Multivibrators are examples of such a device. Multivibrators resonate with a calculable resonant frequency, and this frequency is stable enough to be a standard by which time is kept. Though we assume clocks to be perfect timekeepers, however, this is not the case. Clocks not only have hardware imperfections, they are also susceptible to environmental noises---the combined effects of which leads to variations in timekeeping. This project will aim to explore and characterize the impact of environmental …

Aqueous Foam Stabilized By Tricephalic Amphiphilic Surfactants, Seth A. Heerschap

Senior Honors Projects, 2010-2019

Aqueous foams can be described as a close packing of gas bubbles stabilized by surface active molecules. Their complex and diverse properties make them attractive for many chemical and physical applications where foaming, emulsifying or coating processes are needed. The recent synthesis of multi-cephalic and multi-tailed amphiphilic molecules have reportedly enhanced their antibacterial activity in connection with tail length and nature of the head group.

This report covers the foamability of two triple head, double tail cationic surfactants (M-1,14,14, M-P,14,14) and a triple head single tail cationic surfactant (M-1,1,14) and compares them with commercially available single headed, single tailed anionic …

Analysis And Simulation Of Semiconductor Laser Dynamics With Optoelectronic Delay Feedback, Varghese Bejoy, Sivasankaran Rajesh, Vadakkedath Madhom Nandakumaran

Turkish Journal of Physics

In this work we investigate semiconductor laser dynamics with optoelectronic delay feedback, both analytically and numerically. Stability criteria are derived from the delay differential equations of the system. Stability curves are obtained in the feedback strength-delay parameter space. We show that delay has a role in determining the stability only for a range of feedback strength and this range can vary depending on other parameters. Effects of bias current and nonlinear gain reduction on the stability curves are shown in the analysis and numerically verified.

Effects Of Crab Cavities Multipole Content In An Electron-Ion Collider, A. Castilla, V. S. Morozov, T. Satogata, J. R. Delayen

Physics Faculty Publications

The impact on the beam dynamics of the Medium Energy Electron-Ion Colider (MEIC) due to the multipole content of the 750 MHz crab cavity was studied using thin multipole elements for 6D phase space particle tracking in ELEGANT. Target values of the sextupole component for the cavity’s field expansion were used to perform preliminary studies on the proton beam stability when compared to the case of pure dipole content of the rf kicks. Finally, important effects on the beam sizes due to non-linear components of the crab cavities’ fields were identified and some criteria for their future study were proposed.

Observation Of Ground-State Two-Neutron Decay, M Thoennessen, Z Kholey, A Spyrou, E Lunderberg, Paul A. Deyoung, H Attanayake, T Baumann, D Bazin, B A. Brown, G Christian, D Divaratne, S M. Grimes, A Haagsma, J E. Finck, N Frank, B Luther, S Mosby, T Nagi, Graham F. Peaslee, W A. Peters, A Schiller, J K. Smith, J Snyder, M Strongman, A Volya

Faculty Publications

Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay products. The development of two-neutron detection capabilities of the Modular Neutron Array (MoNA) at NSCL has opened up the possibility to search for unbound nuclei which decay by the emission of two neutrons. Specifically, this exotic decay mode was observed in¹⁶Be and ²⁶O.

Numerical And Experimental Investigation Of The Stability Region For A Cylindrical Ion Trap, Bradley Steven Clarke

UNLV Theses, Dissertations, Professional Papers, and Capstones

The stability diagram provides a useful tool for determining the appropriate AC biased potential to confine ions in an ion trap. Since no analytic solution exists for the cylindrical ion trap's (CIT's) equations of motion, the CIT's stability region is not well known. The objective of this thesis is to determine the stability region for a CIT numerically and experimentally. The equations of motion for ions confined in a CIT are derived and found to be similar to the Mathieu equation, i.e. the equation that describes ion motion in a hyperbolic ion trap (HIT). Because of the similarities in the …

Transport And Spectroscopic Studies Of The Effects Of Fullerene Structure On The Efficiency And Lifetime Of Polythiophene-Based Solar Cells, Emilee L. Sena, Justin H. Peel, Devin Wesenberg, Shreya Nathan, Marianne Wallis, Maxwell J. Giammona, Thorsteinn Adalsteinsson, Brian J. Mcnelis, Richard P. Barber Jr.

Physics

Time-dependent measurements of both power conversion efficiency and ultraviolet-visible absorption spectroscopy have been observed for solar cell blends containing the polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) with two different functionalized C60 electron acceptor molecules: commercially available [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61 butyric acid octadecyl ester (PCBOD) produced in this laboratory. Efficiency was found to decay with an exponential time dependence, while spectroscopic features show saturating exponential behavior. Time constants extracted from both types of measurements showed reasonable agreement for samples produced from the same blend. In comparison to the PCBM samples, the stability of the PCBOD blends was …

On The Ph-Optimum Of Activity And Stability Of Proteins, Kemper Tally, Emil Alexov

Publications

Biological macromolecules evolved to perform their function in specific cellular environment (subcellular compartments or tissues); therefore, they should be adapted to the biophysical characteristics of the corresponding environment, one of them being the characteristic pH. Many macromolecular properties are pH dependent, such as activity and stability. However, only activity is biologically important, while stability may not be crucial for the corresponding reaction. Here, we show that the pH-optimum of activity (the pH of maximal activity) is correlated with the pH-optimum of stability (the pH of maximal stability) on a set of 310 proteins with available experimental data. We speculate that …

Modeling Bound States In The Continuum For Multiple Electrons In A Quantum Dot Pair, Thomas Ian Tuegel

Undergraduate Honors Thesis Collection

The bound eigenstates of an electron inside a pair of quantum dots embedded on an infinite quantum wire are examined using the method of particular solutions. The eigenstates of a two-electron system in the same structure are examined perturbatively using wavefunction expansions for the one-electron eigenstates. The stability of the two-electron eigenstates is evaluated and compared with other theoretical results. It is found that stable bound states in the continuum exist for two electrons confined to this geometry.

Influence Of Functionalized Fullerene Structure On Polymer Photovoltaic Degradation, Brian H. Johnson, Enaanake Allagoa, Robert L. Thomas, Gregory Stettler, Marianne Wallis, Justn H. Peel, Thorsteinn Adalsteinsson, Brian J. Mcnelis, Richard P. Barber Jr.

Physics

The time dependence of device performance has been measured for photocells using blends containing the conjugated polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with two different functionalized C60 electron acceptor molecules: commercially available [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61 butyric acid octadecyl ester (PCBOD) produced in this laboratory. Performance was characterized by the short-circuit current output of the devices, with the time dependence of PCBM samples typically degrading exponentially. Variations in the characteristic lifetime of the devices were observed to depend on the molar fraction of the electron acceptor molecules (calculated with respect to the MEH-PPV monomer fraction). In comparison …

Interaction Of Excited States In Two-Species Bose-Einstein Condensates: A Case Study, Todd Kapitula, Kody J.H. Law, Panayotis G. Kevrekidis

University Faculty Publications and Creative Works

In this paper we consider the existence and spectral stability of excited states in two-species Bose-Einstein condensates in the case of a pancake magnetic trap. Each new excited state found in this paper is to leading order a linear combination of two one-species dipoles, each of which is a spectrally stable excited state for one-species condensates. The analysis is done via a Lyapunov-Schmidt reduction and is valid in the limit of weak nonlinear interactions. Some conclusions, however, can be made at this limit which remain true even when the interactions are large. © 2010 Society for Industrial and Applied Mathematics.

Ergoregion Instability Of Black Hole Mimickers, Paolo Pani, Vitor Cardoso, Mariano Cadoni, Marco Cavaglia

Physics Faculty Research & Creative Works

Ultra-compact, horizonless objects such as gravastars, boson stars, wormholes and superspinars can mimick most of the properties of black holes. Here we show that these "black hole mimickers" will most likely develop a strong ergoregion instability when rapidly spinning. Instability timescales range between ∼ 10^-5s and ∼ weeks depending on the object, its mass and its angular momentum. For a wide range of parameters the instability is truly effective. This provides a strong indication that astrophysical ultra-compact objects with large rotation are black holes.

An Ultrahigh Stability, Low-Noise Laser Current Driver With Digital Control, Christopher J. Erickson, Marshall Van Zijll, Greg Doermann, Dallin S. Durfee

Faculty Publications

We present a low-noise, high modulation-bandwidth design for a laser current driver with excellent long-term stability. The driver improves upon the commonly used Hall–Libbrecht design. The current driver can be operated remotely by way of a microprocessing unit, which controls the current set point digitally. This allows precise repeatability and improved accuracy and stability. It also allows the driver to be placed near the laser for reduced noise and for lower phase lag when using the modulation input. We present the theory of operation for our driver in detail, and give a thorough characterization of its stability, noise, set-point accuracy …

The Asymptotics Of Neutral Curve Crossing In Taylor–Dean Flow, C. P. Hills, A. P. Bassom

Articles

The fluid flow between a pair of coaxial circular cylinders generated by the uniform rotation of the inner cylinder and an azimuthal pressure gradient is susceptible to both Taylor and Dean type instabilities. The flow can be characterised by two parameters: a measure of the relative magnitude of the rotation and pressure effects and a non-dimensional Taylor number. This work considers the small gap, large wavenumber limit for linear perturbations when the onset of the Taylor and Dean instabilities is concurrent. A consistent, matched asymptotic solution is found across the whole annular domain and identifies five regions of interest: two …

Simulations Of Resonant Alfvén Waves Generated By Artificial Hf Heating Of The Auroral Ionosphere, D Pokhotelov, W Lotko, A V. Streltsov

Dartmouth Scholarship

Numerical two-dimensional two-fluid MHD sim- ulations of dynamic magnetosphere-ionosphere (MI) cou- pling have been performed to model the effects imposed on the auroral ionosphere by a powerful HF radio wave trans- mitter. The simulations demonstrate that modifications of the ionospheric plasma temperature and recombination due to artificial heating may trigger the ionospheric feedback in- stability when the coupled MI system is close to the state of marginal stability. The linear dispersion analysis of MI coupling has been performed to find the favorable conditions for marginal stability of the system. The development of the ionospheric feedback instability leads to the generation …