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Articles 1 - 30 of 45
Full-Text Articles in Physics
A Novel Technique To Solve Fractional Differential Equations Using Fractional-Order B-Polynomial Basis Set, Md Habibur Rahman
A Novel Technique To Solve Fractional Differential Equations Using Fractional-Order B-Polynomial Basis Set, Md Habibur Rahman
Theses and Dissertations
This thesis uses B-Polynomial bases to solve both one-dimensional and multi-dimensional linear and nonlinear partial differential equations and linear and nonlinear fractional differential equations. The approach involves constructing an operational matrix from the terms of these equations using Caputo's fractional derivative of fractional B-polynomials. This leads to a semi-analytical solution derived from a matrix equation, and the results obtained using this method are compared to analytical and numerical solutions presented by other authors. The method is shown to be effective in calculating approximate solutions for various differential equations and provides a higher accuracy level than finite difference methods. This technique …
A Convolutional Neural Network Based Approach To Study The Gravitational Waves From Core-Collapse Supernovae In Ligo's Third Observation Run: Detection Efficiency And Parameter Estimation, Bhawana Sedhai
Theses and Dissertations
Core-Collapse Supernova (CCSN) is one of the most anticipated sources of Gravitational Waves (GW) arriving at the advanced LIGO detectors during the fourth observation run (O4). CCSN are rare, weak and unmodeled having a very low rate of occurrence in our galaxy (estimated 2 per century). Thus, detection of GW from CCSN is a challenging problem. An analysis pipeline used in this study is Multi-Layer Signal Enhancement with cWB and CNN or MuLaSEcC that combines Machine Learning methods with a network of Gravitational Wave detectors to identify and reconstruct signals from core collapse supernovae, while minimizing false alarms through the …
Analyzing The On Source Window Of Supernova Sn2019ejj With A Multi Layered Signal Enhancement Algorithm With Coherent Waveburst And A Convolutional Neural Network, Michael Gale Benjamin
Analyzing The On Source Window Of Supernova Sn2019ejj With A Multi Layered Signal Enhancement Algorithm With Coherent Waveburst And A Convolutional Neural Network, Michael Gale Benjamin
Theses and Dissertations
Core collapse supernovae (CCSN) are highly anticipated sources of gravitational waves during the fourth observation run (O4). CCSN signals are weak and unmodeled and the rate of occurrence in our galaxy is very low. Because of this, they provide a greater challenge to detect than previously detected GW sources. CCSN simulations are used to test the detection pipeline in the event a CCSN is detected. CCSN GW signals are often indistinguishable from the noise sources present in GW data. We present a multi layered signal enhancement pipeline which we have applied Machine Learning (ML) techniques. We have used a Convolutional …
Determination Of Effective Index Of Refraction Of Structured Materials (Photonic Crystals), Md Arafat Hossain
Determination Of Effective Index Of Refraction Of Structured Materials (Photonic Crystals), Md Arafat Hossain
Theses and Dissertations
Photonic crystals have been widely studied by researchers due to their ability to control light propagation in all spatial directions. For example, 2D photonic crystals can be made of dielectric rods arranged in a square lattice. When light propagates through 2D photonic crystals, it experiences multiple scatterings by the crystal centers. The superposition of all scattered waves forms the transmitted field largely dependent upon the effective index of refraction of the structured material. We propose a method to determine the effective index of refraction through such materials with the Finite-Difference Time-Domain (FDTD) model. We set up the interface of two …
Search For Gravitational Waves From Core Collapse Supernovae In Ligo's Observation Runs Using A Network Of Detectors, Shahrear Khan Faisal
Search For Gravitational Waves From Core Collapse Supernovae In Ligo's Observation Runs Using A Network Of Detectors, Shahrear Khan Faisal
Theses and Dissertations
Core-Collapse Supernova (CCSN) is one of the most anticipated sources of Gravitational Waves (GW) in the fourth observation run (O4) of LIGO and other network of GW detectors. A very low rate of galactic CCSN, coupled with the fact that the CCSN waveforms are unmodeled, make detection of these signals extremely challenging. Mukherjee et. al. have developed a new burst search pipeline, the Multi-Layer Signal Enhancement with cWB and CNN or MuLaSEcC, that integrates a non-parametric signal estimation and Machine Learning. MuLaSEcC operates on GW data from a network of detectors and enhances the detection probability while reducing the false …
Glitch Estimation And Removal Using Adaptive Spline Fitting And Wavelet Shrinkage On The Gravitational Wave Data, Mohammad Abu Thaher Chowdhury
Glitch Estimation And Removal Using Adaptive Spline Fitting And Wavelet Shrinkage On The Gravitational Wave Data, Mohammad Abu Thaher Chowdhury
Theses and Dissertations
The false alarm rate and reduced sensitivity of searches for astrophysical signals are caused by transient signals of earthly origin, or "glitches," in gravitational wave strain data from groundbased detectors. The greater number of observable astrophysical signals will increase the likelihood of glitch overlaps and exacerbate their negative impact for future detectors with higher sensitivities. The wide morphological diversity and unpredictable waveforms of glitches, and with the vast majority of cases lacking supplemental data present the main obstacles to their mitigation. Thus, nonparametric glitch mitigation techniques are required, which should operate for a wide range of glitches and, in the …
Conceptual Insight Into The Application Of Innovative Educational Methods In Astronomy, Wahltyn A. Rattray
Conceptual Insight Into The Application Of Innovative Educational Methods In Astronomy, Wahltyn A. Rattray
Theses and Dissertations
University students taking introductory astronomy courses were studied with a control group enrolled in a class with standard curriculum and an experimental group enrolled in a class with a curriculum using innovative instructional methods. Using multiple assessments, I analyzed the students’ astronomy knowledge and overall class experience to determine which curriculum was more instructionally effective. The innovative methods were developed with the ADDIE method and were based on the Karplus learning cycle which provided the framework for the astronomy curriculum. The end goal of the innovative curriculum is to produce graduates with better conceptual understanding of astronomy than with the …
Dynamical Casimir Effect In A Superconducting Circuit Periodic Lattice, Andres Cuellar Vega
Dynamical Casimir Effect In A Superconducting Circuit Periodic Lattice, Andres Cuellar Vega
Theses and Dissertations
The dynamical Casimir effect (DCE) is the generation of real photons out of the quantum vacuum due to a rapid modulation of boundary conditions for the electromagnetic field, such as a mirror oscillating at speeds comparable to the speed of light. Previous work demonstrated experimentally that DCE radiation can be generated in electrical circuits based on superconducting microfabricated waveguides, where a rapid modulation of boundary conditions corresponding to semi-transparent mirrors is realized by tuning the applied magnetic flux through superconducting quantum-interference devices (SQUIDs) that are embedded in the waveguide circuits. We propose a novel SQUID periodic lattice architecture, in which …
Contributions To The Heat Capacity Of Neutron Stars, Pedro Paulo Barboza Sanson
Contributions To The Heat Capacity Of Neutron Stars, Pedro Paulo Barboza Sanson
Theses and Dissertations
In this thesis, we review the contribution to the heat capacity of different matter phases that can appear inside a Neutron Star's core, paying special attention to the magnetic dual chiral density wave (MDCDW) phase, which is characterized by an inhomogeneous chiral condensate in the presence of a magnetic field and that is expected to be favored at intermediate densities and low temperatures. Furthermore, we compare our results with the observational lower limit of the core heat capacity established from observations of transiently accreting neutron stars which give us crucial information whether certain phases are feasible to appear in the …
Effects Of Collaborative Group Activities On Students’ Interest, Course Participation, And Performance In An Online Physics Course, Airik R. Sanchez
Effects Of Collaborative Group Activities On Students’ Interest, Course Participation, And Performance In An Online Physics Course, Airik R. Sanchez
Theses and Dissertations
The purpose of this study was to investigate the impact of the use of collaborative work activities in online physics courses as perceived by students. Nearly identical surveys were administered at the beginning and end of two semesters to ascertain student perception on the impact of the utilization on their level of interest, participation, performance as well as teamwork skills. The results show that the majority of the population tested strongly agree that collaborative work had significant effect on all core areas tested, and they support the notion that it should be further utilized in both lecture and lab portions …
Numerical Modeling For Patch Antennas, Luis Mario Bres Castro
Numerical Modeling For Patch Antennas, Luis Mario Bres Castro
Theses and Dissertations
This thesis will focus on creating a number of designs that will be tested in a simulation environment using an electromagnetic solver software called Computer Simulation Technology(CST) as well as we are going to develop our own model to be able to simulate more complex design due to the limitations of CST licensing. The simulations will help us optimize the parameters of gain-frequency allocation for future projects of antenna building. After doing a parametric study of a patch antenna we will develop a model for the return signal of a signal patch antenna, we will present four potential models. The …
Design And Modeling A Tunable Non-Hermitian Acoustic Filter, Sandeep Puri
Design And Modeling A Tunable Non-Hermitian Acoustic Filter, Sandeep Puri
Theses and Dissertations
In this thesis, we explore an application of a non-Hermitian acoustic system with tunable loss in filtering specific frequencies from an upcoming signal at will. Using the commercial computational software, we design our proposed tunable filter made of a phononic super-lattice. The super-lattice consists of two sublattices connected in series. The first sublattice is Hermitian, whereas the other can be Hermitian or Non-Hermitian depending on the amount of loss induced in it. By introducing the loss in the system, we observe the generation of absorbed resonances that can be seen in the reflection spectrum. The range of the filtered frequencies …
Automated Identification Of Lines In Data From Gravitational Wave Detectors, Thomas A. Cruz
Automated Identification Of Lines In Data From Gravitational Wave Detectors, Thomas A. Cruz
Theses and Dissertations
On the frontier of gravitational wave (GW) astronomy, the LIGO detectors record vast quantities of data that need to be analyzed constantly for rare and transient GW signals. A foundational problem in LIGO data analysis is the identification of spectral line features in the Power Spectral Density (PSD) of the data. Such line features correspond to high power terrestrial or instrumental signals that must be removed from the data before any search for GW signals can take place. In this study the method developed aims to automate the extraction of the frequencies and bandwidths of the lines, treated as sharp …
Topologically Robust Bulk State In Non-Hermitian Acoustic System, Jannatul Ferdous
Topologically Robust Bulk State In Non-Hermitian Acoustic System, Jannatul Ferdous
Theses and Dissertations
A closed system associated with Hermitian Hamiltonian allows real eigenvalues. However, the behavior and dynamics an open system (with gain and loss) will be addressed through the Non-Hermitian Hamiltonian. Though a non-Hermitian operator can allow only imaginary eigenvalues, if the Hamiltonian of a non-Hermitian operator obey the combined parity time (PT)-reversal symmetry it exhibits the real eigenvalues or energy spectrum. That is where the topology comes into account. If we add gain, loss or disorder in the system in such a way that the topology of the system does not change and keeping the …
Enhanced Detection Efficiencies And Reduced False Alarms In Searching For Gravitational Waves From Core Collapse Supernovae, Gaukhar Nurbek
Enhanced Detection Efficiencies And Reduced False Alarms In Searching For Gravitational Waves From Core Collapse Supernovae, Gaukhar Nurbek
Theses and Dissertations
A supernova is a star that flares up very suddenly and then slowly returns to its former luminosity or, explodes violently with energy $10^{52}$ erg. There are stars which are 10 times or more massive than the Sun, which usually end their lives going supernova. When there is no longer enough fuel for the fusion process in the core of the star and inward gravitational pull of the star’s great mass takes place, the star starts to explode. A series of nuclear reactions starts taking place after the star begins shrinking due to gravity. In the final phase of this …
Developing A Uhf/Vhf Phased-Array Satellite Ground Station, Brent K. Cole
Developing A Uhf/Vhf Phased-Array Satellite Ground Station, Brent K. Cole
Theses and Dissertations
Earth-satellite communications and tracking of spacecraft are accomplished using ground stations. Traditionally, this has been achieved by using a large parabolic antenna or pair of antennas that point at a source of interest and mechanically steer the antenna(s) as the source moves throughout the sky. Phased arrays, which have often been used in radio astronomy, can provide multiple benefits when used as a ground station including fast scanning speeds across the sky, tracking and communication of multiple sources simultaneously, and significant improvements to overall gain, signal-to-noise ratio (SNR), and data bandwidth. This thesis presents a preliminary analysis of a 20-element …
Methods For Multi-Source Resolution In Pulsar Timing Array Based Gravitational Wave Detection, Yiqian Qian
Methods For Multi-Source Resolution In Pulsar Timing Array Based Gravitational Wave Detection, Yiqian Qian
Theses and Dissertations
With next-generation radio telescopes, namely the Five-hundred-meter Aperture Spherical Telescope(FAST) and Square Kilometer Array(SKA), scheduled to come online during this decade, hundreds of well-timed millisecond pulsars (MSPs) will be added to the Pulsar Timing Arrays (PTAs) being used currently for Gravitational Wave (GW) searches. This will greatly increase the distances to which GW sources in the very low frequency band can be detected. Among these sources will be super massive black hole binaries (SMBHBs) formed out of gigantic black holes weighing in at million to billion times the mass of our Sun. Although the large number of MSPs will improve …
Searching For Low Frequency Fast Radio Bursts With Vlite, Suryarao Bethapudi
Searching For Low Frequency Fast Radio Bursts With Vlite, Suryarao Bethapudi
Theses and Dissertations
The VLITE (VLA Low Band Ionosphere and Transient Experiment; http://vlite.nrao.edu) program performs commensal observations using 16 antennas of the Very Large Array radio telescope from 320-384 MHz. The VLITE-Fast program searches for short time-scale (<100ms) transients, such as Fast Radio Bursts (FRBs), in real time and triggers recording of baseband voltages for offline imaging. Searches are made possible by a 12 node cluster, each housing GPUs for digital signal processing. A real-time Message Passing Interface (MPI)-based co-adder incoherently sums the data streams from all the antennas to boost the signal-to-noise. To undo the dispersion effects of signal propagation through the ionized interstellar medium, the co-added stream is de-dispersed and matched-filtered to search for transients. This operation is completely performed on GPUs by the software package Heimdall . A selection logic is applied to the candidates and interesting candidates with their corresponding data are processed and packaged in a binary file along with a diagnostic plot. Furthermore, a Machine Learning classification is applied on the reduced data product and, based on its decision, baseband voltages are recorded. Reduced data products collected over 126 days of on-sky operation form the VLITE-Fast Pathfinder Survey (VFPS). This pipeline has triggered on single pulses from 7 known radio pulsars. Lastly, the pipeline capabilities are tested against pure random noise and simulated injected signals.
Searching For Pulsars Using The Long Wavelength Array Telescope, Keeisi A. Caballero Valdez
Searching For Pulsars Using The Long Wavelength Array Telescope, Keeisi A. Caballero Valdez
Theses and Dissertations
Radio pulsars are fascinating celestial objects known to display both periodic and transient behavior. Pulsars are characterized by narrow electromagnetic radiation beams which restrict the number of pulsars visible from Earth due to the necessary alignment of the radiation beam across an observer’s line of sight. Pulsars are useful tools for a broad range of applications and provide important information about the process of stellar evolution, tests for relativistic theories of gravity and the search for low-frequency gravitational waves. Over 2,500 pulsars have been observed since their initial discovery in 1967 but the search for these objects is continuously warranted. …
Searching For Optical Counterparts To Gravitational Waves, Richard Camuccio
Searching For Optical Counterparts To Gravitational Waves, Richard Camuccio
Theses and Dissertations
The era of multi-messenger astronomy has begun. The coordinated activities of multiple, distinct observatories play a critical role in both responding to astrophysical transients and building a more comprehensive interpretation otherwise inaccessible to individual observations. The Transient Robotic Observatory of the South (TOROS) Collaboration has a global network of instruments capable of responding to several transient targets of opportunity. The purpose of this thesis is to demonstrate how optical observatories with small fields of view (degree) can follow up and observe astrophysical transients. TOROS facilities responded to three unique gravitational wave events during the second and third observational campaigns of …
Topography Estimation Using Particle Swarm Optimization, Yelbir Kazhykarim
Topography Estimation Using Particle Swarm Optimization, Yelbir Kazhykarim
Theses and Dissertations
The Earth’s Vertical Gravity Gradient (VGG) can be used to map seafloor topography but presents a challenging inverse problem. A promising approach is forward modeling, in which one searches over a set of candidate topographies and selects the one whose predicted VGG best fits the observed one. The main bottleneck here is solving the associated high-dimensional and non-linear optimization problem. Yang et al (2018) demonstrated a method in which the topography is parametrized by heights of mass elements on a rectangular grid and the ≈ 104 dimensional optimization problem is tackled with simulated annealing (SA). We propose a computationally much …
Exploring Mechanical Properties And Configurational Energetics Of Toxbox Using Molecular Dynamics Simulation, Shams Mehdi
Exploring Mechanical Properties And Configurational Energetics Of Toxbox Using Molecular Dynamics Simulation, Shams Mehdi
Theses and Dissertations
All-atom Molecular Dynamics Simulations (MDS) have been performed to obtain 5 ns trajectory of the solvated, neutralized, and equilibrated toxbox system in NPT ensemble at 300 K. This trajectory data has been used to calculate the configurational entropy of toxbox by employing a quantum mechanical approach. The method is based on evaluating determinant of the covariance matrix, built from generalized coordinates of all atoms for each frame. The upper limit to the configurational entropy of toxbox has been calculated to be 30,030 J/mol-K. A preliminary investigation has been conducted to study the effects of sequence-dependent DNA conformation (DNA Crookedness) on …
Magnesium Diboride Embedded Multi-Walled Carbon Nanotube Yarns, Ujjal Lamichhane
Magnesium Diboride Embedded Multi-Walled Carbon Nanotube Yarns, Ujjal Lamichhane
Theses and Dissertations
The discovery of superconductivity in a simple hexagonal binary compound of MgB2 at a relatively high critical temperature ~39 K renewed the interest in the field of superconductivity. Twisted laminar superconducting composite structures based on coiled multi-walled carbon nanotube (MWCNT) yarns were crafted by integrating magnesium and boron homogeneous mixture into the carbon nanotube sheets. After the ignition of the Mg/B/MWCNT system, under the controlled argon environment and uniform heating rate, the high exothermic reaction between magnesium (Mg) and boron (B) with stoichiometric ratio produced the MgB2/MWCNT superconducting composite yarns. The XRD analysis confirmed that the heated sample consists of …
Multi Wall Carbon Nanotube (Mwcnt) Laminar Composite Structures Reinforced With Titanium Carbide (Tic), Rakibul Alam Shohan
Multi Wall Carbon Nanotube (Mwcnt) Laminar Composite Structures Reinforced With Titanium Carbide (Tic), Rakibul Alam Shohan
Theses and Dissertations
Laminated composites have been widely used in weight critical structures, such as aircraft, spacecraft, bullet-proof vests, radiation protection suits, spacesuits etc., owing to their high stiffness, strength, and thermal stability. Multi Wall Carbon Nanotube (MWCNT) laminar composite have attracted a good attention for these laminar composites due to its outstanding physical and mechanical properties as well as extraordinary electrical, optical, and thermal properties. Laminar composite structures based on twisted MWCNT yarn were crafted by integrating titanium and graphene mixture at (80:20) wt. %, respectively into multi wall carbon nanotube sheets. Titanium and Graphene mixture addition has been used to improve …
Effects Of Incubation Temperature On Nanomechanical Properties Of Β-Lactoglobulin Amyloid Fibers, Santosh Khatri
Effects Of Incubation Temperature On Nanomechanical Properties Of Β-Lactoglobulin Amyloid Fibers, Santosh Khatri
Theses and Dissertations
Amyloid fibrils constitute a class of highly ordered nanomaterials formed by aggregates of the protein. Although The irreversible fibril formation of various proteins is related to the disorders like Alzheimer’s diseases, Creutzfeldt-Jacob and many more, amyloid fibrils have also been noticed in many physiologically beneficial roles such as in adhesive and hormone storage. Here, we compare the stiffness and structural properties of the amyloid fibers examined by the statistical approaches of single molecule atomic force microscopy images of heat-denatured β-lactoglobulin fibrils at different incubation time period (24, 48, and 72 hours). We demonstrate the gradual decrease in stiffness of the …
A Search For A High-Order Excitation Of Surface Phonon Polaritons On Silicon Carbide Metasurfaces, Md Litan Ali
A Search For A High-Order Excitation Of Surface Phonon Polaritons On Silicon Carbide Metasurfaces, Md Litan Ali
Theses and Dissertations
Metasurfaces promise a control of light in free and confined spaces like optical waveguides using subwavelength-scale nanostructures. In this work, we experimentally investigate a variety control of light in more confined spaces which is localized surface waves of light. A control of surface waves has been challenged because of a lack of efficient nanostructures. For example, conventional and widely used metallic nanostructures have a high coupling efficiency of light due to free charge carriers but the charge carriers induce a high optical power loss. We recently designed and fabricated metal/dielectric multilayer aperture on ionic crystal, which shows a strong resonance …
Enhancing Transport In Classical And Quantum Systems Using Non-Hermiticity, Fatemeh Mostafavi
Enhancing Transport In Classical And Quantum Systems Using Non-Hermiticity, Fatemeh Mostafavi
Theses and Dissertations
Non-Hermiticity, the presence of gain and loss in the structures, provides a flexible platform to utilize the wave propagation in classical and quantum system. Here in this thesis by using this advantage we aim to enhance the transport in both realms.
The Conical Diffraction And Adiabatic Elimination In Pt-Symmetric Systems, Mojgan Dehghani
The Conical Diffraction And Adiabatic Elimination In Pt-Symmetric Systems, Mojgan Dehghani
Theses and Dissertations
Dehghani, Mojgan, The Conical Diffraction and Adiabatic Elimination in PT-Symmetric Systems. Master of Science (MS), July, 2019, 75 pp., 32 figures, references, 69 titles. Since almost two decades ago, the non-Hermitian Hamiltonians with combined parity and time-reversal symmetry, having entirely real spectra, have been outstanding candidates for characterizing the features of open systems. In this thesis, we investigate the dynamics of certain PT systems. In chapter I, we present a brief review of the fundamentals of PT-symmetric systems. Chapter II focuses on the conical diffraction in a PT-symmetric waveguide lattice. We explore the evolution of a wave packet, which forms …
Bubble Nucleation And Cooperativity In Duplex Stretching Of A Helicoidal Dna Model, Pawan Kumar Thapaliya
Bubble Nucleation And Cooperativity In Duplex Stretching Of A Helicoidal Dna Model, Pawan Kumar Thapaliya
Theses and Dissertations
Denaturation of DNA means separation of dsDNA into ssDNA due to the breaking of hydrogen bond by the application of heat or another mechanical method to carry out the processes like translation,transcription, and replication. Single-molecule DNA stretching experiments displayed a force-induced transition at a force of 65pN for long dsDNA molecules. In these experiments, double stranded DNA molecules are stretched by a force applied to opposite ends of the DNA, e.g., in anatomic force microscope or an optical tweezers instrument. Here we study the thermal and force-induced denaturation of the helicoidal DNA bubble-in-the middle sequence by Monte-Carlo simulations technique. We …
Object Enhancement, Noise Reduction, Conversion And Collection Of Spatiotemporal Image Data, Michael Izaguirre Jr.
Object Enhancement, Noise Reduction, Conversion And Collection Of Spatiotemporal Image Data, Michael Izaguirre Jr.
Theses and Dissertations
In this report, a variety of cellular dynamics are enhanced and analyzed utilizing various algorithms and filter for contrast enhancement. This report will also illustrate the underlying complexities of processing compressed data received from certain type of sensors, their default applications, various methods in converting compressed data to compatible universal uncompressed formats allowed in scientific applications, various methods of image and video capture, guidelines in ethical image manipulation, various methods of frame extraction, and analyzing/processing video images. These methods and processes purposely utilize freeware and public domain software to lower the cost of reproducibility for all.