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Existence and nonexistence of radial solutions for semilinear equations with bounded nonlinearities on exterior domains

Description: Article studies radial solutions of ∆u + K(r)f(u) = 0 on the exterior of the ball of radius R > 0 centered at the origin in ℝᶰ where f is odd with f < 0 on (0, β), f > 0 on (β, δ), f ≡ 0 for u > δ, and where the function K(r) is assumed to be positive and K(r) → 0 as r → ∞.
Date: December 1, 2020
Creator: Iaia, Joseph A.
Partner: UNT College of Science
open access

Electrostatic equilibria of non-neutral plasmas confined in a Penning trap with axially varying magnetic field

Description: This article describes a procedure for computing the electrostatic equilibria of non-neutral plasmas in a Penning trap with a nonuniform magnetic field by solving Poisson's equation using an iterative method. Plasma equilibria in a model Penning trap with high and low field regions are computed. The plasma is assumed to follow the Boltzmann density distribution along magnetic field lines.
Date: May 21, 2019
Creator: Lane, Ryan A. & Ordonez, Carlos A.
Partner: UNT College of Science
open access

Infinitely Many Solutions of Semilinear Equations on Exterior Domains

Description: We prove the existence and nonexistence of solutions for the semilinear problem ∆u + K(r)f(u) = 0 with various boundary conditions on the exterior of the ball in R^N such that lim r→∞u(r) = 0. Here f : R → R is an odd locally lipschitz non-linear function such that there exists a β > 0 with f < 0 on (0, β), f > 0 on (β, ∞), and K(r) \equiv r^−α for some α > 0.
Date: August 2018
Creator: Joshi, Janak R
Partner: UNT Libraries

Commentary on "Effect of β-alanine and the solvent composition on the solubility of solvate of calcium D-pantothenate containing four molecules of methanol and one molecule of water (D-PC·4MeOH·1H₂O)"

Description: This article points out problems associated with two of the mathematical treatments used by authors Han et al. (2017) for the solubility behavior of calcium D-panthenate solvate as the mole fraction concentration β-alanine approaches zero.
Date: February 7, 2017
Creator: Acree, William E. (William Eugene)
Partner: UNT College of Arts and Sciences

[Byrd notebook that has construction measurements]

Description: Photograph of a notebook with a message and measurements from the Byrd Williams Family Photography Collection, held by UNT Special Collections. The message reads "P.S. If you think this is a special case just remember that a little circle just has a smaller radius than a big circle and that old Dioginese was more than half cracked." On the next page are measurements and math for building a cantilever retaining wall.
Date: July 20, 2016
Creator: Sylve, Joshua
Partner: UNT Libraries Special Collections

[Byrd notebook with construction information]

Description: Photograph of a notebook with measurements and formula information from the Byrd Williams Family Photography Collection, held by UNT Special Collections. It includes notes on materials, equations, and cheat-sheets for what certain letters mean.
Date: July 20, 2016
Creator: Sylve, Joshua
Partner: UNT Libraries Special Collections

[Byrd notebook with construction measurements]

Description: Photograph of a notebook with a message and measurements from the Byrd Williams Family Photography Collection, held by UNT Special Collections. The message reads "P.S. If you think this is a special case just remember that a little circle just has a smaller radius than a big circle and that old Dioginese was more than half cracked." On the next page are measurements and math for building a cantilever retaining wall.
Date: July 20, 2016
Creator: Sylve, Joshua
Partner: UNT Libraries Special Collections
open access

Loading Mode Dependent Effective Properties of Octet-truss Lattice Structures Using 3D-Printing

Description: Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, … more
Date: May 2015
Creator: Challapalli, Adithya
Partner: UNT Libraries
open access

Condition-dependent Hilbert Spaces for Steepest Descent and Application to the Tricomi Equation

Description: A steepest descent method is constructed for the general setting of a linear differential equation paired with uniqueness-inducing conditions which might yield a generally overdetermined system. The method differs from traditional steepest descent methods by considering the conditions when defining the corresponding Sobolev space. The descent method converges to the unique solution to the differential equation so that change in condition values is minimal. The system has a solution if and only … more
Date: August 2014
Creator: Montgomery, Jason W.
Partner: UNT Libraries
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Stress-Softening and Residual Strain Effects in Suture Materials

Description: This article focuses on the formulation of a constitutive equation to predict Mullins and residual strain effects of buna-N, silicone, and neoprene rubber strings subjected to small transverse vibrations.
Date: September 4, 2013
Creator: Elías-Zúñiga, Alex; Baylón, Karen; Martínez-Romero, Oscar; Rodríguez, Ciro A. & Siller Carrillo, Héctor Rafael
Partner: UNT College of Engineering
open access

Rotation Angle for the Optimum Tracking of One-Axis Trackers

Description: An equation for the rotation angle for optimum tracking of one-axis trackers is derived along with equations giving the relationships between the rotation angle and the surface tilt and azimuth angles. These equations are useful for improved modeling of the solar radiation available to a collector with tracking constraints and for determining the appropriate motor revolutions for optimum tracking.
Date: July 1, 2013
Creator: Marion, W. F. & Dobos, A. P.
Partner: UNT Libraries Government Documents Department
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Space-charge-based electrostatic plasma confinement involving relaxed plasma species

Description: In this article, a numerical study is reported on the equilibrium properties of a surface-emitted or edge-confined non-drifting plasma. A self-consistent finite-differences evaluation of the electrostatic potential is carried out for a non-neutral plasma that follows a Boltzmann density distribution.
Date: October 23, 2012
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences
open access

The Hamiltonian Structure and Euler-Poincare Formulation of the Valsov-Maxwell and Gyrokinetic System

Description: We present a new variational principle for the gyrokinetic system, similar to the Maxwell-Vlasov action presented in Ref. 1. The variational principle is in the Eulerian frame and based on constrained variations of the phase space fluid velocity and particle distribution function. Using a Legendre transform, we explicitly derive the field theoretic Hamiltonian structure of the system. This is carried out with the Dirac theory of constraints, which is used to construct meaningful brackets from t… more
Date: September 25, 2012
Creator: Squire, J.; Qin, H. & Tang, W. M.
Partner: UNT Libraries Government Documents Department
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Response to Comment on &quot;Geometric Phase of the Gyromotion for Charged Particles in a Time-dependent Magnetic Field

Description: The reformulation of our analysis on the geometric phase of the gyromotion [J. Liu and H. Qin, Phys. Plasmas 18, 072505 (2011)] in terms of spatial angles presented in the comment by Brizard and Guillebon is interesting and correct. The subtlety of whether the adiabatic term associated with the long term average of the variation of pitch angle completely disappears after the gyrophase average is related to where valid approximations are applied. But it has no impact on the main conclusions.
Date: August 22, 2012
Creator: Qin, Jian Liu and Hong
Partner: UNT Libraries Government Documents Department
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High Temperature, high pressure equation of state density correlations and viscosity correlations

Description: Global increase in oil demand and depleting reserves has derived a need to find new oil resources. To find these untapped reservoirs, oil companies are exploring various remote and harsh locations such as deep waters in Gulf of Mexico, remote arctic regions, unexplored deep deserts, etc. Further, the depth of new oil/gas wells being drilled has increased considerably to tap these new resources. With the increase in the well depth, the bottomhole temperature and pressure are also increasing to e… more
Date: July 31, 2012
Creator: Tapriyal, D.; Enick, R.; McHugh, M.; Gamwo, I. & Morreale, B.
Partner: UNT Libraries Government Documents Department
open access

Large-Eddy Simulation Study of Wake Propagation and Power Production in an Array of Tidal-Current Turbines: Preprint

Description: This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally-periodic precursor simulation is performed to create turbulent flow data. Then that data is used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modeled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical … more
Date: July 1, 2012
Creator: Churchfield, M. J.; Li, Y. & Moriarty, P. J.
Partner: UNT Libraries Government Documents Department
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Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section

Description: In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.
Date: July 1, 2012
Creator: Li, Rui
Partner: UNT Libraries Government Documents Department
open access

Non-perturbative String Theory from Water Waves

Description: We use a combination of a 't Hooft limit and numerical methods to find non-perturbative solutions of exactly solvable string theories, showing that perturbative solutions in different asymptotic regimes are connected by smooth interpolating functions. Our earlier perturbative work showed that a large class of minimal string theories arise as special limits of a Painleve IV hierarchy of string equations that can be derived by a similarity reduction of the dispersive water wave hierarchy of diffe… more
Date: June 14, 2012
Creator: Iyer, Ramakrishnan; Johnson, Clifford V. & Pennington, Jeffrey S.
Partner: UNT Libraries Government Documents Department
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Comparing new models of transverse instability with simulations

Description: Recently, Balbekov and Burov have produced an ordinary integro-differential equation that approximates the Vlasov equation for beams with wakefields and large space charge tune shift. The present work compares this model with simulations. In particular, the claim that certain types of transverse wakes cannot lead to mode coupling instabilities is explored.
Date: May 20, 2012
Creator: M., Blaskiewicz
Partner: UNT Libraries Government Documents Department
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Numerical Simulations of Transverse Beam Diffusion Enhancement by the Use of Electron Lens in the Tevatron Collider

Description: Transverse beam diffusion for the Tevatron machine has been calculated using the Lifetrac code. The following effects were included: random noise (representing residual gas scattering, voltage noise in the accelerating cavities) lattice nonlinearities and beam-beam interactions. The time evolution of particle distributions with different initial amplitudes in Hamiltonian action has been simulated for 6 million turns, corresponding to a time of about 2 minutes. For each particle distribution, se… more
Date: May 1, 2012
Creator: Previtali, V.; Stancari, G.; Valishev, A. & Shatilov, D. N.
Partner: UNT Libraries Government Documents Department
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RELAP-7 Level 2 Milestone Report: Demonstration of a Steady State Single Phase PWR Simulation with RELAP-7

Description: The document contains the simulation results of a steady state model PWR problem with the RELAP-7 code. The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at Idaho National Laboratory (INL). The code is based on INL's modern scientific software development framework - MOOSE (Multi-Physics Object-Oriented Simulation Environment). This report summarizes the initial results of simulating a model steady-state single phase PWR problem using the curren… more
Date: May 1, 2012
Creator: Andrs, David; Berry, Ray; Gaston, Derek; Martineau, Richard; Peterson, John; Zhang, Hongbin et al.
Partner: UNT Libraries Government Documents Department
open access

Synthesis of Numerical Methods for Modeling Wave Energy Converter-Point Absorbers: Preprint

Description: During the past few decades, wave energy has received significant attention among all ocean energy formats. Industry has proposed hundreds of prototypes such as an oscillating water column, a point absorber, an overtopping system, and a bottom-hinged system. In particular, many researchers have focused on modeling the floating-point absorber as the technology to extract wave energy. Several modeling methods have been used such as the analytical method, the boundary-integral equation method, the… more
Date: May 1, 2012
Creator: Li, Y. & Yu, Y. H.
Partner: UNT Libraries Government Documents Department
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