cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Faraday waves in radial outflow
Creators: name: Horsley, DE
Publisher: name: University Of Tasmania
Year: 2023

description: Faraday waves are a type of free surface standing waves that occur, by the common definition, when a fluid is subject to an oscillating body force in the vertical direction. The scales on which this phenomenon occurs in nature span an enormous range. At the centimetre level, they can be found on the backs of alligators during their water dance‚ÄövÑvp, or in the cup of an unlucky coffee drinker. On the decametre scale, Faraday waves can be involved in the stability of ships and tankers; and on the thousands and millions of kilometers scale, they can affect the planets and stars. It is this last topic that is the motivation of this thesis. In this work, we extend the definition of Faraday waves to cover waves that are excited by oscillating radial outflow in the presence of a gravitational sink. Waves covered by this definition, unlike their classical counterparts, have seen little study. Before examining this extended problem, we begin with a review of the original formulation, as well as some new results attained by adding damping terms to boundary conditions of the ideal fluid model. We study the linearized theory and stability of this model then give some nonlinear results found with numerical methods extended in this thesis. We use these nonlinear results to find the maximum amplitude of Faraday waves in this system. We then go on to give our first radial outflow model consisting of a fluid line-source surrounded by a cylindrical free surface in an ideal fluid. We again study the linear theory of this model, which is complicated by the new geometry, and produce plots of the stability of the system. We produce nonlinear results with numerical methods developed in this thesis, as well as estimates of the maximum amplitude of these waves. Before continuing on to study Faraday waves in more complex fluid models, we take an aside to study the topic of Bessel function cross products and phase functions. In this aside, the contents of which are used in a later section, we develop new asymptotic expansions and inequalities for the Bessel phase functions of both theoretical and practical interest. We use these to produce new efficient and robust algorithms to calculate the roots of linear and cross-product combinations of Bessel functions. With these tools in-hand, we return to the study of Faraday waves excited by a line-source, but this time in a Boussinesq fluid with non-zero viscosity. We use our new Bessel function cross-product root finder to assist in calculating the eigenfunctions of an annulus, which we use as our domain for a numerical method to solve the Boussinesq model. We conclude with an exploration of the parameter space of this Boussinesq model, guided by the ideal model, and present some detailed plots of numerical solutions.
Stellar tracers of the Cygnus Arm. II: A young open cluster in Cam OB3
Creators: name: Negueruela, Ignacio
name: Marco, Amparo
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Cam OB3 is the only defined OB association believed to belong to the Outer Galactic Arm or Cygnus Arm. Very few members have been observed and the distance modulus to the association is not well known. We attempt a more complete description of the population of Cam OB3 and a better determination of its distance modulus. We present uvby photometry of the area surrounding the O-type stars BD +56 864 and LS I +57 138, finding a clear sequence of early-type stars that define an uncatalogued open cluster, which we call Alicante 1. We also present spectroscopy of stars in this cluster and the surrounding association. From the spectral types for 18 very likely members of the association and UBV photometry found in the literature, we derive individual reddenings, finding a extinction law close to standard and an average distance modulus DM=13.0+-0.4. This value is in excellent agreement with the distance modulus to the new cluster Alicante 1 found by fitting the photometric sequence to the ZAMS. In spite of the presence of several O-type stars, Alicante 1 is a very sparsely populated open cluster, with an almost total absence of early B-type stars. Our results definitely confirm Cam OB3 to be located on the Cygnus Arm and identify the first open cluster known to belong to the association.
description: Accepted for publication in Astronomy & Astrophysics. Tables 7 & 8 to appear only in electronic format
The financial statements of New Zealand 1970-2011
Creators: name: Amoako, BA
Publisher: name: University Of Tasmania
Year: 2023

description: The construction and analysis of financial statements for an accounting entity allows its stakeholders to assess its financial position and performance. This is the case for individuals, corporations and countries. Baydoun et al. (2015) proposed a simplified method in constructing an income statement, a balance sheet and cash flow statement. This study extends their work by modifying and applying their one sector model to estimate financial statements for New Zealand and assess its economic performance between 1970 and 2011. The performance assessment is conducted based upon financial ratios. The findings from the analysis will add to the body of knowledge explaining New Zealand's economic performance and the factors that are influential to the New Zealand economy. The significant findings of the study are as follows: 1) there has been gradual but economically significant decrease in the rate of return ratios of the New Zealand economy. The factors responsible for the decrease in New Zealand's return ratios are: 1) asset utilisation inefficiency; 2) a significant increase in the gearing ratio of the New Zealand economy, indicating increased financial risk; 3) consumption levels that mitigate against improvements in the return and risk profile of the New Zealand economy.
Computer modeling of natural silicate melts: what can we learn from ab initio simulations
Creators: name: Vuilleumier, R.
name: Sator, N.
name: Guillot, B.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: The structural and dynamical properties of four silicate liquids (silica, rhyolite, a model basalt and enstatite) are evaluated by ab initio molecular dynamics simulation using the density functional theory and are compared with classical simulations using a simple empirical force field. For a given composition, the structural parameters of the simulated melt vary little between the two calculations (ab initio versus empirical) and are in satisfactory agreement with structure data available in the literature. In contrast, ionic diffusivities and atomic vibration motions are found to be more sensitive to the details of the interactions. Furthermore, it is pointed out that the electronic polarization, as evaluated by the ab initio calculation, contributes significantly to the intensity of the infrared absorption spectra of molten silicates, a spectral feature which cannot be reproduced using nonpolarizable force field. However the vibration modes of TO4 species and some structural details are not accurately reproduced by our ab initio calculation, shortcomings which need to be improved in the future.
description: 87 pages, 16 figures
The Impact of New EUV Diagnostics on CME-Related Kinematics
Creators: name: McIntosh, S. W.
name: De Pontieu, B.
name: Leamon, R. J.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present the application of novel diagnostics to the spectroscopic observation of a Coronal Mass Ejection (CME) on disk by the Extreme Ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. We apply a recently developed line profile asymmetry analysis to the spectroscopic observation of NOAA AR 10930 on 14-15 December 2006 to three raster observations before and during the eruption of a 1000km/s CME. We see the impact that the observer's line-of-sight and magnetic field geometry have on the diagnostics used. Further, and more importantly, we identify the on-disk signature of a high-speed outflow behind the CME in the dimming region arising as a result of the eruption. Supported by recent coronal observations of the STEREO spacecraft, we speculate about the momentum flux resulting from this outflow as a secondary momentum source to the CME. The results presented highlight the importance of spectroscopic measurements in relation to CME kinematics, and the need for full-disk synoptic spectroscopic observations of the coronal and chromospheric plasmas to capture the signature of such explosive energy release as a way of providing better constraints of CME propagation times to L1, or any other point of interest in the heliosphere.
description: Accepted to appear in Solar Physics Topical Issue titled "Remote Sensing of the Inner Heliosphere". Manuscript has 14 pages, 5 color figures. Movies supporting the figures can be found in http://download.hao.ucar.edu/pub/mscott/papers/Weather
Quality Relationships of American Egyptian Cotton between Selected Measures of Quality and Fiber, Yarn and Processing Qualities: Means, Standard Deviations, Simple and Multiple Correlation Analysis, 1956-1960
Creators: name: Smith, Harvin R.
name: Smith, Harvin R.
Publisher: name: Unknown
Year: 1965
Subjects: Crop Production/Industries
Research and Development/Tech Change/Emerging Technologies
Research Methods/ Statistical Methods

description: Excerpts from the report Introduction: Cotton quality relationship studies made in past years by the Cotton Division of the Consumer and Marketing Service have been generally limited to upland type cotton (G. hirsutum). Very few studies have been made with American Egyptian type cotton (G. barbadense) which has extra long staple length. The statistical studies reported here are designed to reveal the relationship, contribution and importance which various fiber quality measurements of American Egyptian type cottons have to the processing performance of these cottons and to the quality of the finished product. These studies are used to test the validity and usefulness of grade and staple standards as well as laboratory measurements, and to show where improvements might be made in describing the quality of raw cotton. These studies also provide mathematical equations which a mill can use to help predict and control its manufacturing performance and its product quality by measuring and controlling the quality of the various fiber properties in the raw stock
Localization of resonance eigenfunctions on quantum repellers
Creators: name: Ermann, Leonardo
name: Carlo, Gabriel G.
name: Saraceno, Marcos
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We introduce a new phase space representation for open quantum systems. This is a very powerful tool to help advance in the study of the morphology of their eigenstates. We apply it to two different versions of a paradigmatic model, the baker map. This allows to show that the long-lived resonances are strongly scarred along the shortest periodic orbits that belong to the classical repeller. Moreover, the shape of the short-lived eigenstates is also analyzed. Finally, we apply an antiunitary symmetry measure to the resonances that permits to quantify their localization on the repeller.
description: 4 pages, 4 figures
Prefetching of VoD Programs Based On ART1 Requesting Clustering
Creators: name: Jayarekha, P.
name: Nair, T. R. GopalaKrishnan
Publisher: name: arXiv
Year: 2009
Subjects: subject: Multimedia (cs.MM)
subject: FOS: Computer and information sciences

description: In this paper, we propose a novel approach to group users according to the VoD user request pattern. We cluster the user requests based on ART1 neural network algorithm. The knowledge extracted from the cluster is used to prefetch the multimedia object from each cluster before the users request. We have developed an algorithm to cluster users according to the users request patterns based on ART1 neural network algorithm that offers an unsupervised clustering. This approach adapts to changes in user request patterns over period without losing previous information. Each cluster is represented as prototype vector by generalizing the most frequently used URLs that are accessed by all the cluster members. The simulation results of our proposed clustering and prefetching algorithm, shows enormous increase in the performance of streaming server. Our algorithm helps the servers agent to learn user preferences and discover the information about the corresponding sources and other similar interested individuals.
description: 7 pages IEEE format, International Journal of Computer Science and Information Security, IJCSIS 2009, ISSN 1947 5500, Impact Factor 0.423, http://sites.google.com/site/ijcsis/
Neutrino mixing and mass hierarchy in Gaussian landscapes
Creators: name: Hall, Lawrence J.
name: Salem, Michael P.
name: Watari, Taizan
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The flavor structure of the Standard Model may arise from random selection on a landscape. In a class of simple models, called "Gaussian landscapes," Yukawa couplings derive from overlap integrals of Gaussian zero-mode wavefunctions on an extra-dimensional space. Statistics of vacua are generated by scanning the peak positions of these wavefunctions, giving probability distributions for all flavor observables. Gaussian landscapes can account for all of the major features of flavor, including both the small electroweak mixing in the quark sector and the large mixing observed in the lepton sector. We find that large lepton mixing stems directly from lepton doublets having broad wavefunctions on the internal manifold. Assuming the seesaw mechanism, we find the mass hierarchy among neutrinos is sensitive to the number of right-handed neutrinos, and can provide a good fit to neutrino oscillation measurements.
description: 11 pages, 2 figures
Critical current of a Josephson junction containing a conical magnet
Creators: name: Halász, Gábor B.
name: Robinson, J. W. A.
name: Blamire, M. G.
name: Annett, James F.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We calculate the critical current of a superconductor/ferromagnetic/superconductor (S/FM/S) Josephson junction in which the FM layer has a conical magnetic structure composed of an in-plane rotating antiferromagnetic phase and an out-of-plane ferromagnetic component. In view of the realistic electronic properties and magnetic structures that can be formed when conical magnets such as Ho are grown with a polycrystalline structure in thin-film form by methods such as direct current sputtering and evaporation, we have modeled this situation in the dirty limit with a large magnetic coherence length ($ξ_f$). This means that the electron mean free path is much smaller than the normalized spiral length $λ/2π$ which in turn is much smaller than $ξ_f$ (with $λ$ as the length a complete spiral makes along the growth direction of the FM). In this physically reasonable limit we have employed the linearized Usadel equations: we find that the triplet correlations are short ranged and manifested in the critical current as a rapid oscillation on the scale of $λ/2π$. These rapid oscillations in the critical current are superimposed on a slower oscillation which is related to the singlet correlations. Both oscillations decay on the scale of $ξ_f$. We derive an analytical solution and also describe a computational method for obtaining the critical current as a function of the conical magnetic layer thickness.
description: Extended version of the published paper. Additional information about the computational method is included in the appendix
A quantum statistical approach to simplified stock markets
Creators: name: Bagarello, Fabio
Publisher: name: arXiv
Year: 2009
Subjects: subject: General Finance (q-fin.GN)
subject: FOS: Economics and business

description: We use standard perturbation techniques originally formulated in quantum (statistical) mechanics in the analysis of a toy model of a stock market which is given in terms of bosonic operators. In particular we discuss the probability of transition from a given value of the {\em portfolio} of a certain trader to a different one. This computation can also be carried out using some kind of {\em Feynman graphs} adapted to the present context.
description: in press in Physica A
Quasi-specular albedo of cold neutrons from powder of nanoparticles
Creators: name: Cubitt, R.
name: Lychagin, E. V.
name: Muzychka, A. Yu.
name: Nekhaev, G. V.
name: Nesvizhevsky, V. V.
name: Pignol, G.
name: Protasov, K. V.
name: Strelkov, A. V.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We predicted and observed for the first time the quasi-specular albedo of cold neutrons at small incidence angles from a powder of nanoparticles. This albedo (reflection) is due to multiple neutron small-angle scattering. The reflection angle as well as the half-width of angular distribution of reflected neutrons is approximately equal to the incidence angle. The measured reflection probability was equal to ~30% within the detector angular size that corresponds to 40-50% total calculated probability of quasi-specular reflection.
Racemization and resolution in the organic solid state
Creators: name: Wilson, Keith Rainier
Publisher: name: University of British Columbia
Year: 2011

description: Two examples of the simplest type of organic solid-state reaction - the thermal interconversion of optical isomers - have been extensively studied by means of polarimetry, differential scanning calorimetry, and X-ray powder diffraction. The first reaction investigated was the reverse Diels-Alder reaction and recombination of the cyclopentadiene-fumaric acid adduct. Polycrystalline samples of (+)-enantiomer (m.p. 176°) racemize completely in the solid state from 130° to 165°. First-order kinetics (ΔH = 40.0 kcal mole⁻¹, ΔS = 14 cal deg⁻¹mole⁻¹) are strictly obeyed; the racemization rate is insensitive to variations in crystal size and optical purity. The reaction, which is only five times slower than the melt rate extrapolated to these temperatures (for the melt from 176° to 194°, ΔH = 29.7 kcal mole⁻¹, ΔS = -6.9 cal deg⁻¹mole⁻¹) occurs throughout the polycrystalline sample rather than at crystallite boundaries, dislocations, or other preferred sites. Phase studies show that the product separates as a racemic compound (m.p. 186°) which forms a eutectic (at 165°) with the resolved enantiomers. From 165° to 176°, the racemization shows autoacceleration and sigmoid-shaped kinetic curves characteristic of concurrent reactions in the solid and melt phases. The second system studied was that formed between R-(-)- and S-(+)-1,1'-binaphthyl, and surprisingly, resolution, rather than racemization, was observed to occur from 76° to 158°. This unprecedented solid-state resolution is made possible by a solid-solid phase change from a racemic compound (m.p. 145°) to a. eutectic mixture (m.p. 158°) of crystals of pure enantiomers, at temperatures where interconversion occurs in the reactant-product interface. Polycrystalline 1,1’-binaphthyl samples of very low optical activity having the correct phase content (racemate plus crystals of only one enantiomer) for a controlled resolution can be easily and reproducibly prepared. These samples resolve from [α][sub D] = 2° to [α][sub D] = ca. 210° (in either (+) or (-) directions) in less than one hour at 150°. The limit of resolution ([α][sub D] = ±245°) is attained simply by recrystallization of the resolved sample from acetone. The resolution therefore involves the conversion of all of a racemic material to only one enantiomer. Kinetic studies of the solid-state resolution show a smooth development of optical activity with time. A Prout-Tompkins analysis indicates that crystallites of growing enantiomer spread throughout the racemic sample, requiring 62 kcal mole⁻¹ activation energy. Crystallization of completely racemic 1,1'-binaphthyl melt in a closed system gives rise to optical activity. The probability distribution of 200 individual crystallizations is symmetric about [α][sub D] = 0° and proves that optically active samples can be created under absolutely spontaneous conditions (i.e., in the complete absence of external dissymmetric influences).
Neutral B-meson mixing from unquenched lattice QCD with domain-wall light quarks and static b-quarks
Creators: name: Albertus, Conrado
name: Aoki, Yasumichi
name: Boyle, Peter A.
name: Christ, Norman H.
name: Dumitrescu, Thomas T.
name: Flynn, Jonathan M.
name: Ishikawa, Tomomi
name: Izubuchi, Taku
name: Loktik, Oleg
name: Sachrajda, Christopher T.
name: Soni, Amarjit
name: Van de Water, Ruth S.
name: Wennekers, Jan
name: Witzel, Oliver
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We demonstrate a method for calculating the neutral B-meson decay constants and mixing matrix elements in unquenched lattice QCD with domain-wall light quarks and static b-quarks. Our computation is performed on the "2+1" flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice spacing of a approx 0.11 fm (a^-1 = 1.729 GeV) and a lattice spatial volume of approximately (1.8 fm)^3. We simulate at three different light sea quark masses with pion masses down to approximately 430 MeV, and extrapolate to the physical quark masses using a phenomenologically-motivated fit function based on next-to-leading order heavy-light meson SU(2) chiral perturbation theory. For the b-quarks, we use an improved formulation of the Eichten-Hill action with static link-smearing to increase the signal-to-noise ratio. We also improve the heavy-light axial current used to compute the B-meson decay constant to O(alpha_s p a) using one-loop lattice perturbation theory. We present initial results for the SU(3)-breaking ratios f_{B_s}/f_{B_d} and xi = f_{B_s} sqrt{B_{B_s}}/f_{B_d} sqrt{B_{B_d}}, thereby demonstrating the viability of the method. For the ratio of decay constants, we find f_{B_s}/f_{B_d} = 1.15(12) and for the ratio of mixing matrix elements, we find xi = 1.13(12), where in both cases the errors reflect the combined statistical and systematic uncertainties, including an estimate of the size of neglected O(1/m_b) effects.
description: 60 pages, 9 figures
Influence of the Dzyaloshinskii-Moriya exchange interaction on quantum phase interference of spins
Creators: name: Wernsdorfer, W.
name: Stamatatos, T. C.
name: Christou, G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Magnetization measurements of a Mn12mda wheel single-molecule magnet with a spin ground state of S = 7 show resonant tunneling and quantum phase interference, which are established by studying the tunnel rates as a function of a transverse field applied along the hard magnetization axis. Dzyaloshinskii-Moriya (DM) exchange interaction allows the tunneling between different spin multiplets. It is shown that the quantum phase interference of these transitions is strongly dependent on the direction of the DM vector.
description: 5 pages, 5 figures
Cosmological properties of eternally collapsing objects (ECOs)
Creators: name: Mitra, Abhas
Publisher: name: arXiv
Year: 2009
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: We show that the integration constant in the vacuum Schwarzschild solution has the unique value, alpha_0=0, accordingly Black Holes too have the same unique value of mass M0=0. Therefore the so-called Black Holes Candidates (BHC) cannot be true BHs. It is also shown that continued collapse of sufficiently massive bodies would generate radiation pressure and energy dominated quasistatic objects having surface gravitational redshifts z>>1. Under the assumption of baryon number conservation, such objects would take infinite time to collapse to the idealized BH state with M=0 and z=infty. The local temperature of such a stellar mass Eternally Collapsing Object (ECO) would be above Quark Gluon Phase transition. ECOs would undergo intermittent violent radiative eruptions and pollute the interstellar medium with freshly made hydrogen out of their QGP and also the light elements cooked in their envelope. It is shown that the extremely redshifted observed temperature of an ECO could be 2.75 K and superposition of ECO background radiation might generate the microwave back ground radiation. The predicted 2.75 K luminosity for the galactic centre ECO, i.e., Sgr A*, L~3x1036 erg/s, nicely matches with the corresponding estimate by Wilkinson Microwave Anisotropy Probe (WMAP).
description: 10 pages, pdf only
Random Hamiltonian in thermal equilibrium
Creators: name: Brody, Dorje C.
name: Ellis, David C. P.
name: Holm, Darryl D.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A framework for the investigation of disordered quantum systems in thermal equilibrium is proposed. The approach is based on a dynamical model--which consists of a combination of a double-bracket gradient flow and a uniform Brownian fluctuation--that `equilibrates' the Hamiltonian into a canonical distribution. The resulting equilibrium state is used to calculate quenched and annealed averages of quantum observables.
description: 8 pages, 4 figures. To appear in DICE 2008 conference proceedings
Even-dimensional topological gravity from Chern-Simons gravity
Creators: name: Merino, Nelson
name: Perez, Alfredo
name: Salgado, Patricio
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: It is shown that the topological action for gravity in 2n-dimensions can be obtained from the 2n+1-dimensional Chern-Simons gravity genuinely invariant under the Poincare group. The 2n-dimensional topological gravity is described by the dynamics of the boundary of a 2n+1-dimensional Chern-Simons gravity theory with suitable boundary conditions. The field $ϕ^{a}$, which is necessary to construct this type of topological gravity in even dimensions, is identified with the coset field associated with the non-linear realizations of the Poincare group ISO(d-1,1).
Climate Mitigation Approaches and Sustainable Housing: A Case Study of Flood Management in Rivers State
Creators: name: Sarah, Mitchell
name: Liam, Carter
Publisher: name: AYDEN JOURNAL
Year: 2024
Subjects: Climate Mitigation Strategies, Sustainable Housing Development, Flooding, Rivers State

description: This examined the impact of climate mitigation strategies and sustainable housing developmental Rivers State. In conducting the study, a descriptive survey design was used. The Population covered all the employees of federal and state ministries, agencies, real estate developers and registered surveyors. A multi-stage random Sampling technique was used to select the respondent for the study. A sample size of 266 was used. Quantitative data collected were analyzed by the use of descriptive statistics presented through percentages, means, standard deviations and frequencies. The study found that that 3.17 and a standard deviation of 1.103, the mean indicated the significant impact of Sustainable drainage systems in mitigating climate change for sustainable development. From the second variable, the study found that a mean of 2.78 which proved that flood risk management and spatial planning affect sustainable housing development. The result found a mean of 3.00 and indicated that disaster vulnerability and preparedness affect sustainable housing development. The study found a mean of 2.41 and proved that spatial planning and land use management impact on sustainable housing development. From the findings, the study concludes that mitigation strategies significantly impact on sustainable housing development in Rivers State. It therefore recommends implementable policies and strategies to advances climate mitigation to enhance sustainable housing development in the state.
Risk and reliability assessment of marine operations
Creators: name: Abaei, Mohammad
Publisher: name: University Of Tasmania
Year: 2023

description: Marine structures are widely used in the oil and gas industry, marine transportation and exploration areas and renewable energy applications. Understanding dynamic behaviour of these structures is necessary to allow their evaluation under the effects of environmental loads such as wave, wind and currents. However, the sea environment is very complex, and the response of these structures is affected by considerable uncertainties that should be predicted accurately. Due to the stochastic trend of the sea environment, different types of failure are expected to be observed during the life time of a structure. Consequently, failure of a marine structure may pose various major risks in terms of environmental pollution and loss of assets for companies. Therefore, a great deal of research on the improvement of marine safety is carried out to mitigate the associated risks. It is also necessary to take into account the process of risk escalation in a more realistic way than relying only on either precursor data or expert judgments. This requires a comprehensive approach when it comes to accident modelling and risk analysis of marine structures. This PhD research is focused on developing advanced probabilistic models for representing dynamic risk assessment of marine structures in a harsh environment. The developed frameworks will assist industries to model marine accidents and improve the reliability of marine structures to minimize the risk of failure. The main content of the thesis investigates a developing practical framework for incorporating the reliability of floating offshore structures while considering hydrodynamic performance of the structure as real monitoring data based on modelling the physics of the failure. In order to evaluate response of the marine structure in harsh environment, the storm condition was developed to help researchers to generate necessary data for conducting reliability assessment of the system. The outcome of this achievement led to analysis performance of either the marine structure or the human on board for future risk analysis and decision-making. As a result, the developed methodologies include time-dependent reliability strategies that can model long-term failure scenarios in marine environment which is able to consider marine accident and human failure in respect to the time of operations. Overall, this thesis provides a comprehensive probability model for evaluating the dynamic risk assessment of marine structures under different operational conditions. The outcome of this research will assist industries to improve the reliability of the structures in the design phase or in their operating conditions to mitigate the associated risks to assets, human life and the environment.
Comment on the Black Hole Recoil Candidate Quasar SDSS J092712.65+294344.0
Creators: name: Shields, G. A.
name: Bonning, E. W.
name: Salviander, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: SDSS J092712.65+294344.0 has been proposed as a candidate for a supermassive black hole (~10^8.8 solar masses) ejected at high speed from the host galactic nucleus by gravitational radiation recoil, or alternatively for a supermassive black hole binary. This is based on a blueshift of 2650 km/s of the broad emission lines ("b-system") relative to the narrow emission lines ("r-system") presumed to reflect the galaxy velocity. New observations with the Hobby-Eberly Telescope (HET) confirm the essential features of the spectrum. We note a third redshift system, characterized by weak, narrow emission lines of [O III] and [O II] at an intermediate velocity 900 km/s redward of the broad line velocity ("i-system"). A composite spectrum of SDSS QSOs similar to J0927 illustrates the feasibility of detecting the calcium K absorption line in spectra of sufficient quality. The i-system may represent the QSO host galaxy or a companion. Photoionization requires the black hole to be ~3 kpc from the r-system emitting gas, implying that we are observing the system only 10^6 yr after the recoil event and contributing to the low probability of observing such a system. The HET observations give an upper limit of 10 km/s per year on the rate of change of the velocity difference between the r- and b-systems, constraining the orbital phase in the binary model. These considerations and the presence of a cluster of galaxies apparently containing J0927 favor the idea that this system represents a superposition of two AGN.
description: 18 pages, 4 figures, ApJ in press, revised discussion of stellar absorption features and binary black hole model
Triggering Eruptive Mass Ejection in Luminous Blue Variables
Creators: name: Harpaz, Amos
name: Soker, Noam
Publisher: name: arXiv
Year: 2009
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We study the runaway mass loss process of major eruptions of luminous blue variables (LBVs) stars, such as the 1837-1856 Great Eruption of Eta Carinae. We follow the evolution of a massive star with a spherical stellar evolution numerical code. After the star exhausted most of the hydrogen in the core and had developed a large envelope, we remove mass at a rate of 1 Mo/year from the outer envelope for 20 years. We find that after removing a small amount of mass at a high rate, the star contracts and releases a huge amount of gravitational energy. We suggest that this energy can sustain the high mass loss rate. The triggering of this runaway mass loss process might be a close stellar companion or internal structural changes. We show that a strong magnetic field region can be built in the radiative zone above the convective core of the evolved massive star. When this magnetic energy is released it might trigger a fast removal of mass, and by that trigger an eruption. Namely, LBV major eruptions might be triggered by magnetic activity cycles. The prediction is that LBV stars that experience major eruptions should be found to have a close companion and/or have signatures of strong magnetic activity during or after the eruption.
description: Accepted by New Astronomy
Lepton Number Violating Processes Mediated by Majorana Neutrinos at Hadron Colliders
Creators: name: Kovalenko, Sergey
name: Lu, Zhun
name: Schmidt, Ivan
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the Lepton number violating like-sign dilepton processes $h_1 h_2 \to l^\pm l^{\prime \pm} jj X$ and $h_1 h_2 \to l^\pm l^{\prime \pm} W^\pm X$, mediated by heavy GeV scale Majorana neutrinos. We focus on the resonantly enhanced contributions with a nearly on-mass-shell Majorana neutrino in the s-channel. We study the constraints on like-sign dilepton production at the Tevatron and the LHC on the basis of the existing experimental limits on the masses of heavy neutrinos and their mixings $U_{αN}$ with $α= ν_{e}, ν_μ, ν_τ$. Special attention is paid to the constraints from neutrinoless double beta decay. We note that searches for like-sign $e^{\pm} e^{\pm}$ events at Tevatron and LHC may shed light on CP-violation in neutrino sector. We also discuss the conditions under which it is possible to extract individual constraints on the mixing matrix elements in a model independent way.
description: 18 pages,6 figures
Hedged maximum likelihood estimation
Creators: name: Blume-Kohout, Robin
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This paper proposes and analyzes a new method for quantum state estimation, called hedged maximum likelihood (HMLE). HMLE is a quantum version of Lidstone's Law, also known as the "add beta" rule. A straightforward modification of maximum likelihood estimation (MLE), it can be used as a plugin replacement for MLE. The HMLE estimate is a strictly positive density matrix, slightly less likely than the ML estimate, but with much better behavior for predictive tasks. Single-qubit numerics indicate that HMLE beats MLE, according to several metrics, for nearly all "true" states. For nearly-pure states, MLE does slightly better, but neither method is optimal.
description: 4 pages + 2 short appendices
Observational systematics for galaxy clustering: transitioning from DES to LSST-DESC
Creators: name: Rodríguez Monroy, Martín
Publisher: name: Zenodo
Year: 2024
Subjects: cosmology
galaxy clustering
LSST
DESC
observational systematics

description: One of the main cosmological probes that LSST-DESC will use to obtain cosmological constraints is the combination of galaxy clustering, cosmic shear and galaxy-galaxy lensing, resulting in the so-called 3x2pt probe. Given the astonishing amount of data that LSST will provide, statistical errors will shrink even lower than in previous stage surveys, such as DES, so systematic errors will become the main sources of uncertainty. Therefore it will be essential to know in detail the different sources of systematic effects and to correct for them appropriately in order to avoid significant biases on the results. In this sense, galaxy clustering measurements are not an exception to this problem, with observational systematics being of particular relevance. In this contribution we present how we can apply the different methodologies developed during DES-Y3 and Y6 to the treatment of the observational systematics in LSST-DESC's future galaxy clustering measurements. We will also discuss the additional methods that we are currently studying at the IFT.
Activities of the Loja W-STEM node
Creators: name: Loja W-STEM Node
Publisher: name: Zenodo
Year: 2021
Subjects: Women, Science, CBHE, EU, gender, STEM, W-STEM

description: The 3rd meeting of the W-STEM ERASMUS + Capacity-building in Higher Education European Project (Ref. 598923-EPP-1-2018-1-ES-EPPKA2-CBHE-JP) had scheduled to be held in Guadalajara (Mexico). The COVID-19 pandemic did not allow us to meet face-to-face, and we decided to organize the meeting online on January 12-14, 2021. The Loja W-STEM node presented its activities related to the project in the Guadalajara project meeting.

description: W-STEM (Building the future of Latin America: engaging women into STEM) is a project funded under European Union ERASMUS + Capacity-building in Higher Education Programme (598923-EPP-1-2018-1-ES-EPPKA2-CBHE-JP) The European Commission support for the production of this publication does not constitute an endorsement of the contents which reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.
Prefix based Chaining Scheme for Streaming Popular Videos using Proxy servers in VoD
Creators: name: Dakshayini, M
name: Nair, T R GopalaKrishnan
Publisher: name: arXiv
Year: 2009
Subjects: subject: Multimedia (cs.MM)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: Streaming high quality videos consumes significantly large amount of network resources. In this context request to service delay, network traffic, congestion and server overloading are the main parameters to be considered in video streaming over the internet that effect the quality of service (QoS). In this paper, we propose an efficient architecture as a cluster of proxy servers and clients that uses a peer to peer (P2P) approach to cooperatively stream the video using chaining technique. We consider the following two key issues in the proposed architecture (1) Prefix caching technique to accommodate more number of videos close to client (2) Cooperative client and proxy chaining to achieve the network efficiency. Our simulation results shows that the proposed approach yields a prefix caching close to the optimal solution minimizing WAN bandwidth usage on server-proxy path by utilizing the proxy-client and client-client path bandwidth, which is much cheaper than the expensive server proxy path bandwidth, server load, and client rejection ratio significantly using chaining.
description: 9 pages IEEE format, International Journal of Computer Science and Information Security, IJCSIS 2009, ISSN 1947 5500, Impact Factor 0.423, http://sites.google.com/site/ijcsis/
Clues to the Metallicity Distribution in the Galactic Bulge: Abundances in MOA-2008-BLG310 and MOA-2008-BLG311
Creators: name: Cohen, Judith G.
name: Thompson, Ian B.
name: Sumi, Takahiro
name: Bond, Ian
name: Gould, Andrew
name: Johnson, Jennifer A.
name: Huang, Wenjin
name: Burley, Greg
Publisher: name: arXiv
Year: 2009
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present abundance analyses based on high dispersion and high signal-to-noise ratio Magellan spectra of two highly microlensed Galactic bulge stars in the region of the main sequence turnoff with Teff ~ 5650 K. We find that MOA-2008-BLG310 has [Fe/H]= +0.41 (+,- 0.09 dex) and MOA-2008-BLG311 has +0.26 (+, - 0.09 dex). The abundance ratios for the ~20 elements for which features could be detected in the spectra of each of the two stars follow the trends with [Fe/H] found among samples of bulge giants. Combining these two bulge dwarfs with the results from previous abundance analysis of four other Galactic bulge turnoff region stars, all highly magnified by microlensing, gives a mean [Fe/H] of +0.29dex. This implies that there there is an inconsistency between the Fe-metallicity distribution of the microlensed bulge dwarfs and that derived by the many previous estimates based on surveys of cool, luminous bulge giants, which have mean [Fe/H] ~ -0.1 dex. A number of possible mechanisms for producing this difference are discussed. If one ascribes this inconsistency to systematic errors in the abundance analyses, we provide statistical arguments suggesting that a substantial systematic error in the Fe-metallicity for one or both of the two cases, bulge dwarfs vs bulge giants, is required which is probably larger than can realistically be accommodated.
description: Accepted to the ApJ, 36 pages with 7 figures. Updated to conform to the published version, two references added, other very minor changes
A general synthetic route to monoterpenes and sesquiterpenes
Creators: name: Hodgson, Gordon Lewis
Publisher: name: University of British Columbia
Year: 2011

description: A biogenetic hypothesis concerned with an alternative route to monoterpenes and sesquiterpenes bearing the bicyclo(2.2.1)heptane framework has led to a general synthetic route to this class of compound. In particular, consideration of an oxygenated monocyclic cyclohexenyl substrate resembling dihydrocarvone enol phosphate as possible intermediate in the biogenesis of camphor has resulted in development of an efficient laboratory synthesis of (±)-camphor 17 and related compounds including borneol 18, tricyclene 19 and camphene 20. Extention of this work in the monoterpene field to the related sesquiterpenes provided synthetic entry to (±)-campherenone 42, (±)-epicampherenone 47, (±)-∝-santalene 47, (±)-β-santalene 48 and (±)-epi-β-santalene 50. As a further simplification of the biogenesis of sesquiterpenes, campherenone enol phosphate was considered a possibl precursor of such polycyclic sesquiterpenes as copacamphor, ylango-camphor, longicamphor and structurally related compounds. Laboratory analogy for this biogenetic relationship was established in the synthesis of (±)-copacamphor 52, (±)-ylangocamphor 53 and related compounds starting from campherenone. The success of the synthetic investigations led to refinements in the initial biogenetic postulate and necessitated the establishment of the absolute configurations of various sesquiterpenes encompassed in the postulate. (-)-Cryptomerion 99a was prepared starting from (-)-carvone 79a. A synthesis of (+)-epicampherenone 45a and (-)-campherenone 42b starting from (+)-camphor has allowed assignment of absolute configuration to these compounds and to β-santalene and epi-β-santalene. Formal access to optically active copacamphor, ylangocamphor and related compounds is implied from the synthesis of (-)-campherenone.
Is Fertilizer Use Inconsistent With Profitability? Evidence From Sorghum Production In Nigeria
Creators: name: Omonona, B. T.
name: Liverpool-Tasie, L. S. O.
name: Sanou, A.
name: Ogunleye, W. O.
name: Omonona, B. T.
name: Liverpool-Tasie, L. S. O.
name: Sanou, A.
name: Ogunleye, W. O.
Publisher: name: Unknown
Year: 2019
Subjects: subject: Agricultural and Food Policy
subject: Sorghum
subject: Yield response
subject: Marginal physical product
subject: Fertiliser profitability

description: This article contributes to a limited but growing literature challenging a core assumption that it is profitable for smallholder farmers in sub-Saharan Africa to use more fertilizer than currently obtains. Using panel data from Nigeria, Africa’s largest economy, we empirically estimated the effect of applied nitrogen on sorghum yields. We explored if fertilizer use was profitable for sorghum farmers and the conditions that could facilitate profitable use of the input. We found that while input subsidies or reducing the high transportation costs for securing inputs could increase the profitability of fertilizer use for sorghum farmers, increasing the yield response rate of applied nitrogen is a more effective approach to improve the profitability of fertilizer application for these farmers. This involves addressing key challenges smallholders’ face including poor fertilizer and soil quality, limited use of complementary inputs and management practices.
O questionamento dos alunos em ambientes virtuais de aprendizagem
Creators: name: Almeida, Carolina
name: Martins, Micaela
Publisher: name: Internet Latent Corpus Journal
Year: 2016

description: Vários são os estudos realizados no âmbito do questionamento dentro da sala de aula. Uma grande parte deles aponta para o mesmo resultado: o professor é o detentor da maior percentagem de perguntas colocadas na sala de aula, monopolizando o tempo lectivo com o seu discurso. No entanto, em ambientes virtuais, as estatísticas apontam para a situação inversa: é o aluno o ponto central do questionamento. O presente estudo teve por base uma metodologia de investigação qualitativa, no qual foram analisadas as perguntas efetuadas pelos alunos da Unidade Curricular de Cálculo II num grupo do Facebook. O objetivo do grupo é complementar a Orientação Tutorial e as aulas presenciais, funcionando como um espaço onde cada aluno deixa as suas dúvidas, sendo estas respondidas pelos restantes alunos ou pelos professores. Com esta análise, pretendemos perceber até que ponto os alunos utilizam esta ferramenta para acompanhar os conteúdos lecionados na aula.
description: Internet Latent Corpus Journal, vol. 6 n.º 1 (2016)