Other Physics Commons^™

Response Of The Isothermal Mode Grüneisen Tensor Across Phase Boundaries, Jasmine K. Hinton

UNLV Theses, Dissertations, Professional Papers, and Capstones

The assumptions for the 1912 Grüneisen parameter are reviewed, particularly in the cases of anisotropy, high temperatures, and across phase boundaries. Two main case studies are shown: β-Sn, and Cd. The main techniques of this work involve resistively heated diamond anvil cells with both optical Raman spectroscopy and x-ray diffraction. It is found in Sn that the isothermal mode Grüneisen tensor along increasing isotherms diverges from the single-valued temperature aggregate at the onset of melt, and this is proposed to use as a method of exploring melt phase boundaries in other systems. This method is examined once again on another …

Studies Of The Ionosphere-Thermosphere Responses To Multi-Scale Energy Deposition Processes, Haonan Wu

All Dissertations

The Ionosphere-Thermosphere (I-T) system is greatly affected by the magnetospheric energy deposition from above and subjected to forcing from the lower atmosphere simultaneously. A central problem in studying the coupled I-T system is to analyze the multi-scale processes naturally embedded in both ways. Magnetospheric energy input such as auroral precipitation and electric field demonstrates multi-scale structures during magnetic storms, resulting in multi-scale I-T responses when deposited into the I-T system. To better quantify the multi-scale aurora and electric field, we developed a new data assimilation model based on a multi-resolution Gaussian process model to synthesize empirical models and observational data …

An Investigation Into The Physical Properties Governing The​ Coupled Harmonic Oscillator​, Ethan Taylor, Jj Rivera

ATU Scholars Symposium

The coupled harmonic oscillator is an extremely important model in physics - especially in the field of solid state physics where the forces that tie atoms to their equilibrium positions are much stronger than their inter-atomic coupling forces. Given a coupled spring-mass system, we want to theoretically determine and then experimentally verify the normal frequencies involved in coupled harmonic oscillation. To do so, a coupled spring-mass system was built using an air track, carts, and PASCO motion detectors, the normal frequencies were theoretically calculated, and then we experimentally verified these normal frequencies with 4 trials: Symmetric, Antisymmetric, and two Mixed …

One-Dimensional And Two-Dimensional Simulations Of Helical Homopolymers: A Comparative Analysis Of Energy Stabilization And Efficiency​, Nathan Roberts, Matthew Hooks

Scholars Week

The purpose of our work is to analyze the results of a two-dimensional parallel tempering Monte Carlo simulation of a coarse-grained helical homopolymer. The two-dimensional simulation allows Hamiltonian exchanges across both temperature and torsion values, while the one-dimensional simulation exclusively exchanges across temperature values. The genesis of each simulation is defined by a randomly configured polymer; as time progresses, randomly generated movements of monomers decrease the structure’s energy until equilibrium is reached. Equilibrium is determined by finding the absolute minimum of the data series, computing the mean of all remaining data, and finding the intersection between the rolling average and …

An Analysis Of Energy Production And Efficiency In Various Longbow Archery Models, Hannah Mcpherson

Honors Projects

An analysis of the energy production and efficiency of three lab-tested longbow models is undertaken. The first model, which is constructed to not allow flexing of limbs and which uses a frictionless cart and track in place of an arrow, demonstrated an efficiency of 50% +/- 40%. The second model, which is constructed similarly to the first with the exception of a wooden dowel now being used as an arrow-like object, demonstrated an efficiency of 13% +/- 3%. The last model, a 3D printed longbow with flexible limbs using the wooden dowel as an arrow-like object, demonstrated an efficiency of …

Carbon Dioxide-Induced Corrosion Of Aisi 4140 Steel In Acidified Artificial Geothermal Brine, Anawati Anawati, Rayhan Izzat, Riene Kaelamanda Pragitta, Rafli Ihsan Hernandi

Makara Journal of Science

Carbon dioxide (CO₂)-induced corrosion often occurs in the structural materials of geothermal industry. The presence of CO₂ influences the formation of various corrosion products. This research investigates the effect of dissolved CO₂ in acidic brines on the corrosion behavior of AISI 4140 steel at atmospheric pressure. The brines were the standard brine, Ca-free brine, and high-salinity brine. The corrosion behavior was studied using electrochemical and immersion tests. A cyclic polarization test showed that the corrosion rate was higher in dissolved CO₂ brine than in non-CO₂ brine, and an immersion test demonstrated a similar result. …

Effective Connectivity Of Functional Mri Via Deep Learning Methods, Kai-Cheng Chuang

LSU Doctoral Dissertations

Effective connectivity, based on functional magnetic resonance imaging (fMRI) time series signals, is the quantification of how strongly brain activity in a certain source brain region contributes to brain activity in a target brain region, independent of the contributions of other source regions. Current methods to solve this problem have several limitations. They are either unable to model nonlinear relationships between source and target signals, unable to efficiently quantify time lags in source-target relationships, unable to identify time-varying relationships, or fail to account for variability in the hemodynamic response function that converts neuron activity to a measurable signal. In this …

Designing Polar Textures With Ultrafast Neuromorphic Features From Atomistic Simulations, Sergey Prosandeev, Sergei Prokhorenko, Yousra Nahas, Yali Yang, Changsong Xu, Julie Grollier, Diyar Talbayev, Brahim Dkhil, L. Bellaiche

Physics Faculty Publications and Presentations

This review summarizes recent works, all using a specific atomistic approach, that predict and explain the occurrence of key features for neuromorphic computing in three archetypical dipolar materials, when they are subject to THz excitations. The main ideas behind such atomistic approach are provided, and illustration of model relaxor ferroelectrics, antiferroelectrics, and normal ferroelectrics are given, highlighting the important potential of polar materials as candidates for neuromorphic computing. Some peculiar emphases are made in this Review, such as the connection between neuromorphic features and percolation theory, local minima in energy path, topological transitions and/or anharmonic oscillator model, depending on the …

High-Frequency Diode Effect In Superconducting Nb3Sn Microbridges, Sara Chahid, Serafim Teknowijoyo, Iris Mowgood, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

The superconducting diode effect has recently been reported in a variety of systems and different symmetry-breaking mechanisms have been examined. However, the frequency range of these potentially important devices still remains obscure. We investigated superconducting microbridges of Nb3Sn in out-of-plane magnetic fields; optimum magnetic fields of ∼10 mT generate ∼10% diode efficiency, while higher fields of ∼15–20 mT quench the effect. The diode changes its polarity with magnetic field reversal. We documented superconductive diode rectification at frequencies up to 100 kHz, the highest reported as of today. Interestingly, the bridge resistance during diode operation reaches a value that is a …

Have Underground Radiation Measurements Refuted The Orch Or Theory?: Comment On “At The Crossroad Of The Search For Spontaneous Radiation And The Orch Or Consciousness Theory”, Kelvin J. Mcqueen

Philosophy Faculty Articles and Research

"In [1] it is claimed that, based on radiation emission measurements described in [2], a certain 'variant' of the Orch OR theory has been refuted. I agree with this claim. However, the significance of this result for Orch OR per se is unclear. After all, the refuted 'variant' was never advocated by anyone, and it contradicts the views of Hameroff and Penrose (hereafter: HP) who invented Orch OR [3].

My aim is to get clear on this situation. I argue that it is indeed reasonable to speak of 'variants' here. Orch OR is not a complete model of reality but …

A Quantum Approach To Language Modeling, Constantijn Van Der Poel

Dissertations, Theses, and Capstone Projects

This dissertation consists of six chapters. . . Chapter 1: We introduce language modeling, outline the software used for this thesis, and discuss related work. Chapter 2: We will unpack the transition from classical to quantum probabilities, as well as motivate their use in building a model to understand language-like datasets. Chapter 3: We motivate the Motzkin dataset, the models we will be investigating, as well as the necessary algorithms to do calculations with them. Chapter 4: We investigate our models’ sensitivity to various hyperparameters. Chapter 5: We compare the performance and robustness of the models. Chapter 6: We conclude …

Beam-Based Target Alignment For Mu2e, Helenka Casler

Dissertations, Theses, and Capstone Projects

The Mu2e Experiment is a precision experiment at Fermi National Accelerator Laboratory, searching for charged lepton flavor violation (CLFV) in the conversion of a muon to an electron in the presence of an atomic nucleus. In order to achieve the expected single-event sensitivity of 3 × 10^-17 , Mu2e will require an intense muon beam, generated via pion decay. These pions are the product of a proton beam striking a radiatively-cooled tungsten target. In order to maximize pion production and prevent target failure, the beam will have to be aligned with the target center to within 0.5 mm. The …

Gamelan Gong Directivity Dataset, Samuel D. Bellows, Dallin T. Harwood, Kent L. Gee, Micah R. Shepherd

Directivity

No abstract provided.

A Theoretical Framework For 3+1d Dynamics Of Relativistic Heavy-Ion Collisions, Sahr Alzhrani

Wayne State University Dissertations

The primary goal is to enhance a theoretical tool for studying 3D dynamics in relativistic heavy-ion collisions. We aim to explore the effects of stochastic fluctuations within these systems as part of the Beam Energy Scan program at the Relativistic Heavy-Ion Collider. Our approach involves constructing 3D initial conditions using minimal model parameters based on Glauber collision geometry, energy, and momentum conservation principles. We validate the model by comparing its predictions on particle rapidity distributions and anisotropic flow coefficients in specific collision scenarios. Model parameters are calibrated by comparing predictions to observed data from central Au+Au collisions. Additionally, we extend …

Entropy-Driven Structural Transition From Tetragonal To Cubic Phase: High Thermoelectric Performance Of Cucdinse3 Compound, Tingting Luo, Yihao Hu, Shi Liu, Fanjie Xia, Junhao Qiu, Haoyang Peng, Keke Liu, Quansheng Guo, Xingzhong Li, Dongwang Yang, Xianli Su, Jinsong Wu, Xinfeng Tang

Nebraska Center for Materials and Nanoscience: Faculty Publications

Cu based chalcopyrite is an important class of thermoelectric materials with excellent electronic properties, however, the thermal conductivity is relatively high due to the simple tetragonal structure with highly ordered configuration on cation sites, limiting the thermoelectric performance. Herein, we realize that the modulation of entropy via alloying CdSe achieves the structural transition from tetragonal structure with ordered configuration on cations sites in CuInSe₂ compound to cubic CuCdInSe₃. CuCdInSe₃ crystallizes in a zinc blende (ZnS) structure where Cu, Cd and In cations randomly occupy the Zn site with the occupancy fraction 1/3. This entropy driven order-disorder …

"Density" Of Light And Pi, John Adam

Mathematics & Statistics Faculty Publications

Question 1: What is the linear “density” of the spectral range on the ceiling? The crown molding is common for an older (circa 1925) house.

Question 2: The glass shown is a standard 16-oz. water glass engraved with many digits of pi. (The dimensions appear somewhat distorted because of the camera angle chosen to enhance the contrast of the numerals against the dark background.)

New Features In Landyne 5 - A Software Suite For Materials Characterization And Crystallography By Transmission Electron Microscopy, Xing-Zhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

Landyne software suite (version 5) includes fifteen standalone computer programs for materials characterization and crystallography by transmission electron microscopy [1]. A launcher interface is provided for users to access all components conveniently. The purpose of this software suite is twofold: i) as research tools to analyze experimental results, ii) as teaching tools to explore the varieties of electron diffraction methods and crystallographic image processing principles.

The Landyne suite previously included: PTable, an interactive periodic table of elements; SVAT, a structural visual and analytical tool; SAED and PCED, simulation and analysis of electron diffraction (spot and ring) patterns; QSAED and QPCED, …

Structural, Electronic, And Magnetic Properties Of Cofevge-Based Compounds: Experiment And Theory, Parashu Kharel, Zachary Lehmann, Gavin Baker, Lukas Stuelke, Shah R. Valloppilly, Paul M. Shand, Pavel V. Lukashev

Nebraska Center for Materials and Nanoscience: Faculty Publications

We have carried out a combined theoretical and experimental investigation of both stoichiometric and nonstoichiometric CoFeVGe alloys. In particular, we have investigated CoFeVGe, Co_1.25Fe_0.75VGe, Co_0.75Fe_1.25VGe, and CoFe_0.75VGe bulk alloys. Our first principles calculations suggest that all four alloys show ferromagnetic order, where CoFeVGe, Co_1.25Fe_0.75VGe, and Co_0.75Fe_1.25VGe are highly spin polarized with spin polarization values of over 80%. However, the spin polarization value of CoFe_0.75VGe is only about 60%. We have synthesized all four samples using arc melting and high-vacuum annealing …

Tem Studies Of A New Modulated Structure In Mn2Rusn Alloy And Intermetallic Phases In Fe3+XCo3–XTi2 (X = 0, 1, 2, 3) Alloys, Xing-Zhong Li, Shah R. Valloppilly

Nebraska Center for Materials and Nanoscience: Faculty Publications

Heusler compounds are a remarkable class of intermetallic materials with wide-ranging and tunable properties. The Mn₂RuSn Heusler compound was reported as an L2₁B-type cubic phase, a = 0.62195 nm, distinguishing from the original L2₁ structure (or L2₁A-type). The L2₁B-type structure is a disordered variant of the inverse Heusler structure, XA-type (Prototype-CuHg₂Ti, space group No. 216, F4–3m).

In our recent work [1], we observed a new modulated structure derived from the XA-type structure and its orthogonal domains in the Mn₂RuSn Heusler alloy. The structural characterization was carried out …

More On The Demons Of Thermodynamics, Daniel P. Sheehan, Garret Moddel, James W. Lee

Chemistry & Biochemistry Faculty Publications

No abstract provided.