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- Gravitational waves (5)
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Articles 1 - 30 of 49
Full-Text Articles in Physical Sciences and Mathematics
The Nanograv 12.5 Yr Data Set: Observations And Narrowband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia
The Nanograv 12.5 Yr Data Set: Observations And Narrowband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia
Physics and Astronomy Faculty Publications and Presentations
We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars observed from 2004 to 2017 at the Arecibo Observatory and the Green Bank Telescope by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The observing cadence was three to four weeks for most pulsars over most of this time span, with weekly observations of six sources. These data were collected for use in low-frequency gravitational wave searches and for other astrophysical purposes. We detail our observational methods and present a set of TOA measurements, based on "narrowband" analysis, in which many TOAs are calculated within narrow radio-frequency …
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 …
Improving The Robustness Of The Advanced Ligo Detectors To Earthquakes, Eyal Schwartz, A. Pele, J. Warner, B. Lantz, Joseph Betzwieser, K. L. Dooley, S. Biscans, K. E. Ramirez
Improving The Robustness Of The Advanced Ligo Detectors To Earthquakes, Eyal Schwartz, A. Pele, J. Warner, B. Lantz, Joseph Betzwieser, K. L. Dooley, S. Biscans, K. E. Ramirez
Physics and Astronomy Faculty Publications and Presentations
Teleseismic, or distant, earthquakes regularly disrupt the operation of ground–based gravitational wave detectors such as Advanced LIGO. Here, we present EQ mode, a new global control scheme, consisting of an automated sequence of optimized control filters that reduces and coordinates the motion of the seismic isolation platforms during earthquakes. This, in turn, suppresses the differential motion of the interferometer arms with respect to one another, resulting in a reduction of DARM signal at frequencies below 100 mHz. Our method greatly improved the interferometers' capability to remain operational during earthquakes, with ground velocities up to 3.9 μm s−1 rms …
Structural Evolution And Magnetic Properties Of Gd2hf2o7 Nanocrystals: Computational And Experimental Investigations, Madhab Pokhrel, N. Dimakis, Gamage Chamath Dannangoda, Santosh K. Gupta, Karen S. Martirosyan, Yuanbing Mao
Structural Evolution And Magnetic Properties Of Gd2hf2o7 Nanocrystals: Computational And Experimental Investigations, Madhab Pokhrel, N. Dimakis, Gamage Chamath Dannangoda, Santosh K. Gupta, Karen S. Martirosyan, Yuanbing Mao
Physics and Astronomy Faculty Publications and Presentations
Structural evolution in functional materials is a physicochemical phenomenon, which is important from a fundamental study point of view and for its applications in magnetism, catalysis, and nuclear waste immobilization. In this study, we used x-ray diffraction and Raman spectroscopy to examine the Gd2Hf2O7 (GHO) pyrochlore, and we showed that it underwent a thermally induced crystalline phase evolution. Superconducting quantum interference device measurements were carried out on both the weakly ordered pyrochlore and the fully ordered phases. These measurements suggest a weak magnetism for both pyrochlore phases. Spin density calculations showed that the Gd3+ …
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, W. H. Wang
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, W. H. Wang
Physics and Astronomy Faculty Publications and Presentations
We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437−4715, PSR J0711−6830, and PSR J0737−3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835−4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time we are able to match (for PSR J0437−4715) or surpass (for PSR J0711−6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and constrain their equatorial ellipticities to be less than 10−8 …
Interplay Of Quantum Phase Transition And Flat Band In Hybrid Lattices, Gui-Lei Zhu, Hamidreza Ramezani, Clive Emary, Jin-Hua Gao, Ying Wu, Xin-You Lü
Interplay Of Quantum Phase Transition And Flat Band In Hybrid Lattices, Gui-Lei Zhu, Hamidreza Ramezani, Clive Emary, Jin-Hua Gao, Ying Wu, Xin-You Lü
Physics and Astronomy Faculty Publications and Presentations
We establish a connection between quantum phase transitions (QPTs) and energy band theory in an extended Dicke-Hubbard lattice, where the periodical critical curves modulated by wave number k leads to rich equilibrium dynamics. Interestingly, the chiral-symmetry-protected flat band and the localization that it engenders exclusively occurs in the normal phase and disappears in the superradiant phase. This originates from the QPT induced simultaneous breaking up of the on-site resonance condition and off-site chiral symmetry of the system, which prohibits the destructive interference for obtaining a flat band. Our work offers an approach to identify different phases of the lattice via …
Optical Study Of Pks B1322-110, The Intra-Hour Variable Radio Source, Juan P. Madrid, Artem V. Tuntsov, Mischa Schirmer, Mark A. Walker, Carlos J. Donzelli, Keith W. Bannister, Hayley E. Bignall, Jamie Stevens, Cormac Reynolds, Simon Johnston
Optical Study Of Pks B1322-110, The Intra-Hour Variable Radio Source, Juan P. Madrid, Artem V. Tuntsov, Mischa Schirmer, Mark A. Walker, Carlos J. Donzelli, Keith W. Bannister, Hayley E. Bignall, Jamie Stevens, Cormac Reynolds, Simon Johnston
Physics and Astronomy Faculty Publications and Presentations
Observations with the Australia Telescope Compact Array revealed intra-hour variations in the radio source PKS B1322-110 (Bignall et al. 2019). As part of an optical follow-up, we obtained Gemini Hα and Hα continuum (HαC) images of the PKS B1322-110 field. A robust 19 σ detection of PKS B1322- 110 in the Hα−HαC image prompted us to obtain the first optical spectrum of PKS B1322-110. With the Gemini spectrum we determine that PKS B1322-110 is a flat-spectrum radio quasar at a redshift of z = 3.007 ± 0.002. The apparent flux detected in the Hα filter is likely to originate from …
26 Results Of Hyperbolic Partial Differential Equations In B-Poly Basis, Muhammad I. Bhatti, Emilio Hinojosa
26 Results Of Hyperbolic Partial Differential Equations In B-Poly Basis, Muhammad I. Bhatti, Emilio Hinojosa
Physics and Astronomy Faculty Publications and Presentations
A two-variable process to estimate results of Hyperbolic Partial Differentiation (HPD) equations in a B-Polynomial (B-Poly) bases is established. In the proposed process, a linear product of variable coefficients and B-Polys is manipulated to express the predicted solution of the HPD equation. The variable coefficients of the linear mixture in the results are concluded using Galerkin technique. The HPD equation is converted into a matrix which when inverted provided the unknown coefficients in the linear mixture of the solution. The anticipated solution is constructed from the variable coefficients and B-Poly basis set as a product with initial conditions implemented. Both …
Sensitivity And Performance Of The Advanced Ligo Detectors In The Third Observing Run, A. Buikema, C. Cahillane, G. L. Mansell, C. D. Blair, R. Abbott, C. Adams, R. Adhikari, K. E. Ramirez
Sensitivity And Performance Of The Advanced Ligo Detectors In The Third Observing Run, A. Buikema, C. Cahillane, G. L. Mansell, C. D. Blair, R. Abbott, C. Adams, R. Adhikari, K. E. Ramirez
Physics and Astronomy Faculty Publications and Presentations
On April 1st, 2019, the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO), joined by the Advanced Virgo detector, began the third observing run, a year-long dedicated search for gravitational radiation. The LIGO detectors have achieved a higher duty cycle and greater sensitivity to gravitational waves than ever before, with LIGO Hanford achieving angle-averaged sensitivity to binary neutron star coalescences to a distance of 111 Mpc, and LIGO Livingston to 134 Mpc with duty factors of 74.6% and 77.0% respectively. The improvement in sensitivity and stability is a result of several upgrades to the detectors, including doubled intracavity power, the addition of …
Gw190521: A Binary Black Hole Merger With A Total Mass Of 150 M⊙, R. Abbott, T. D. Abbott, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy, W. H. Wang, A. K. Zadrozny
Gw190521: A Binary Black Hole Merger With A Total Mass Of 150 M⊙, R. Abbott, T. D. Abbott, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy, W. H. Wang, A. K. Zadrozny
Physics and Astronomy Faculty Publications and Presentations
On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85+21−14 M⊙ and 66+17−18 M⊙ (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of …
Properties And Astrophysical Implications Of The 150 M ⊙ Binary Black Hole Merger Gw190521, R. Abbott, T. D. Abbott, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy, W. H. Wang, A. K. Zadrozny
Properties And Astrophysical Implications Of The 150 M ⊙ Binary Black Hole Merger Gw190521, R. Abbott, T. D. Abbott, A. Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, P. K. Roy, W. H. Wang, A. K. Zadrozny
Physics and Astronomy Faculty Publications and Presentations
The gravitational-wave signal GW190521 is consistent with a binary black hole (BBH) merger source at redshift 0.8 with unusually high component masses, M ⊙ and M ⊙, compared to previously reported events, and shows mild evidence for spin-induced orbital precession. The primary falls in the mass gap predicted by (pulsational) pair-instability supernova theory, in the approximate range 65–120 M ⊙. The probability that at least one of the black holes in GW190521 is in that range is 99.0%. The final mass of the merger ( M ⊙) classifies it as an intermediate-mass black hole. Under the assumption of a quasi-circular …
Robust Localized Zero-Energy Modes From Locally Embedded Pt-Symmetric Defects, Fatemeh Mostafavi, Cem Yuce, Omar S. Magana-Loaiza, Henning Schomerus, Hamidreza Ramezani
Robust Localized Zero-Energy Modes From Locally Embedded Pt-Symmetric Defects, Fatemeh Mostafavi, Cem Yuce, Omar S. Magana-Loaiza, Henning Schomerus, Hamidreza Ramezani
Physics and Astronomy Faculty Publications and Presentations
We demonstrate the creation of robust localized zero-energy states that are induced into topologically trivial systems by insertion of a PT-symmetric defect with local gain and loss. A pair of robust localized states induced by the defect turns into zero-energy modes when the gain-loss contrast exceeds a threshold, at which the defect states encounter an exceptional point. Our approach can be used to obtain robust lasing or perfectly absorbing modes in any part of the system.
Induced Ferroelectric Phases In Srtio3 By A Nanocomposite Approach, Erik Enriquez, Qian Li, Pamela Bowlan, Ping Lu, Bruce Zhang, Leigang Li, Haiyan Wang, Antoinette J. Taylor, Dmitry Yarotski, Rohit P. Prasankumar
Induced Ferroelectric Phases In Srtio3 By A Nanocomposite Approach, Erik Enriquez, Qian Li, Pamela Bowlan, Ping Lu, Bruce Zhang, Leigang Li, Haiyan Wang, Antoinette J. Taylor, Dmitry Yarotski, Rohit P. Prasankumar
Physics and Astronomy Faculty Publications and Presentations
Inducing new phases in thick films via vertical lattice strain is one of the critical advantages of vertically aligned nanocomposites (VANs). In SrTiO3 (STO), the ground state is ferroelastic, and the ferroelectricity in STO is suppressed by the orthorhombic transition. Here, we explore whether vertical lattice strain in three-dimensional VANs can be used to induce new ferroelectric phases in SrTiO3:MgO (STO:MgO) VAN thin films. The STO:MgO system incorporates ordered, vertically aligned MgO nanopillars into a STO film matrix. Strong lattice coupling between STO and MgO imposes a large lattice strain in the STO film. We have investigated ferroelectricity in the …
Diffuse Spectra Model Of Photoluminescence In Carbon Quantum Dots, S. E. Kumekov, N. K. Saitova, Karen S. Martirosyan
Diffuse Spectra Model Of Photoluminescence In Carbon Quantum Dots, S. E. Kumekov, N. K. Saitova, Karen S. Martirosyan
Physics and Astronomy Faculty Publications and Presentations
The attractive aspect of excitation related to fluorescence nature in carbon quantum dots (CQD) has guided to several assumptions correlated with clusters size distribution, shapes as well as presence of different emissive states. In this study, a dimer–excimer model of photoluminescence (PL) in CQD describing discrete multiple electronic states for the excitation-dependent emission is described. The functional dependence of the characteristic width of the diffuse spectra of PL on the size of a quantum dots are calculated. The effective width of PL spectrum can be tuned from 0.1 to 1 eV.
Adaptive Spline Fitting With Particle Swarm Optimization, Soumya Mohanty, Ethan Fahnestock
Adaptive Spline Fitting With Particle Swarm Optimization, Soumya Mohanty, Ethan Fahnestock
Physics and Astronomy Faculty Publications and Presentations
In fitting data with a spline, finding the optimal placement of knots can significantly improve the quality of the fit. However, the challenging high-dimensional and non-convex optimization problem associated with completely free knot placement has been a major roadblock in using this approach. We present a method that uses particle swarm optimization (PSO) combined with model selection to address this challenge. The problem of overfitting due to knot clustering that accompanies free knot placement is mitigated in this method by explicit regularization, resulting in a significantly improved performance on highly noisy data. The principal design choices available in the method …
A Simple Graphical Method For Calculating The Standing Wave Frequencies On A Rectangular Membrane, Joseph D. Romano, Richard H. Price
A Simple Graphical Method For Calculating The Standing Wave Frequencies On A Rectangular Membrane, Joseph D. Romano, Richard H. Price
Physics and Astronomy Faculty Publications and Presentations
In introductory physics courses, simple arguments based on traveling waves on a string are used to relate the frequency of standing waves to boundary conditions, e.g., the fixed ends of the string. Here, we extend that approach to two-dimensional waves such as the oscillations of a rectangular membrane with edges fixed at the boundary. This results in a graphical method that uses only simple geometry and is suitable for explaining two-dimensional standing-wave oscillations to non-science majors, e.g., in a physics of sound and music class.
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. …
Absence Of Landau-Peierls Instability In The Magnetic Dual Chiral Density Wave Phase Of Dense Qcd, Efrain J. Ferrer, Vivian De La Incera
Absence Of Landau-Peierls Instability In The Magnetic Dual Chiral Density Wave Phase Of Dense Qcd, Efrain J. Ferrer, Vivian De La Incera
Physics and Astronomy Faculty Publications and Presentations
We investigate the stability of the magnetic dual chiral density wave (MDCDW) phase of cold and dense QCD against collective low-energy fluctuations of the order parameter. The appearance of additional structures in the system free energy due to the explicit breaking of the rotational and isospin symmetries by the external magnetic field play a crucial role in the analysis. The new structures stiffen the spectrum of the thermal fluctuations in the transverse direction, thereby avoiding the Landau-Peierls instability that affects single-modulated phases at arbitrarily low temperatures. The lack of Landau-Peierls instabilities in the MDCDW phase makes this inhomogeneous phase of …
Absence Of Landau-Peierls Instability In The Magnetic Dual Chiral Density Wave Phase Of Dense Qcd, Efrain J. Ferrer, Vivian De La Incera
Absence Of Landau-Peierls Instability In The Magnetic Dual Chiral Density Wave Phase Of Dense Qcd, Efrain J. Ferrer, Vivian De La Incera
Physics and Astronomy Faculty Publications and Presentations
We investigate the stability of the magnetic dual chiral density wave (MDCDW) phase of cold and dense QCD against collective low-energy fluctuations of the order parameter. The appearance of additional structures in the system free energy due to the explicit breaking of the rotational and isospin symmetries by the external magnetic field play a crucial role in the analysis. The new structures stiffen the spectrum of the thermal fluctuations in the transverse direction, thereby avoiding the Landau-Peierls instability that affects single-modulated phases at arbitrarily low temperatures. The lack of Landau-Peierls instabilities in the MDCDW phase makes this inhomogeneous phase of …
Astroalign: A Python Module For Astronomical Image Registration, Martin Beroiz, Juan B. Cabral, Bruno Sanchez
Astroalign: A Python Module For Astronomical Image Registration, Martin Beroiz, Juan B. Cabral, Bruno Sanchez
Physics and Astronomy Faculty Publications and Presentations
We present an algorithm implemented in the Astroalign Python module for image registration in astronomy. Our module does not rely on WCS information and instead matches three-point asterisms (triangles) on the images to find the most accurate linear transformation between them. It is especially useful in the context of aligning images prior to stacking or performing difference image analysis. Astroalign can match images of different point-spread functions, seeing, and atmospheric conditions.
Fingerprints Of Binary Black Hole Formation Channels Encoded In The Mass And Spin Of Merger Remnants, Manuel Arca Sedda, Michaela Mapelli, Mario Spera, Matthew Benacquista, Nicola Giacobbo
Fingerprints Of Binary Black Hole Formation Channels Encoded In The Mass And Spin Of Merger Remnants, Manuel Arca Sedda, Michaela Mapelli, Mario Spera, Matthew Benacquista, Nicola Giacobbo
Physics and Astronomy Faculty Publications and Presentations
Binary black holes (BBHs) are thought to form in different environments, including the galactic field and (globular, nuclear, young, and open) star clusters. Here, we propose a method to estimate the fingerprints of the main BBH formation channels associated with these different environments. We show that the metallicity distribution of galaxies in the local universe along with the relative amount of mergers forming in the field or in star clusters determine the main properties of the BBH population. Our fiducial model predicts that the heaviest merger to date, GW170729, originated from a progenitor that underwent 2–3 merger events in a …
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 …
Towards A Real-Time Fully-Coherent All-Sky Search For Gravitational Waves From Compact Binary Coalescences Using Particle Swarm Optimization, M. E. Normandin, Soumya Mohanty
Towards A Real-Time Fully-Coherent All-Sky Search For Gravitational Waves From Compact Binary Coalescences Using Particle Swarm Optimization, M. E. Normandin, Soumya Mohanty
Physics and Astronomy Faculty Publications and Presentations
While a fully-coherent all-sky search is known to be optimal for detecting gravitational wave signals from compact binary coalescences, its high computational cost has limited current searches to less sensitive coincidence-based schemes. Following up on previous work that has demonstrated the effectiveness of particle swarm optimization (PSO) in reducing the computational cost of this search, we present an implementation that achieves near real-time computational speed. This is achieved by combining the search efficiency of PSO with a significantly revised and optimized numerical implementation of the underlying mathematical formalism along with additional multithreaded parallelization layers in a distributed computing framework. For …