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Investigation of Shallow Sedimentary Structure of the Anchorage Basin, Alaska, Using Simulated Annealing Inversion of Site Response
This study deals with shallow sedimentary structure of the Anchorage basin in Alaska. For this purpose, inversion of site response [SR(f)] data in the frequency range 0.5-11.0 Hz from various sites of the basin has been performed using the simulated annealing method to compute subsurface layer thickness, shear-wave velocity (beta), density, and shear-wave quality factor. The one-dimensional (1D) models for the aforementioned parameters were obtained with preset bounds on the basis of available geological information such that the L-2 norm error between the observed and computed site response attained a global minimum. Next, the spatial distribution of the important parameter beta was obtained by interpolating values yielded by the 1D models. The results indicate the presence of three distinct velocity zones as the source of spatial variation of SR(f) in the Anchorage basin. In the uppermost part of the basin, the beta values of fine-grain Quaternary sediments mainly lie in the range of 180-500 m/sec with thickness varying from 15 to 50 m. This formation overlies relatively thick (80-200 m) coarse-grain Quaternary sediments with beta values in the range of 600-900 m/sec. These two Quaternary units are, in turn, overlain on Tertiary sediments with beta > 1000 m/sec located at depths of 100 and 250 m, respectively, in the central and western side along the Knik Arm parts of the basin. The important implication of the result is that the sources of spatial variation of SR(f) in the Anchorage basin for the frequency band 0.5-11 Hz, besides in the uppermost 30 m, are found to be deeper than this depth. Thus, use of commonly considered geological formations in the depth intervals from 0 to 30 m for the ground-motion interpretation will likely yield erroneous results in the Anchorage basin.GIEnvironment and Natural Resources InstituteSchool of Engineering of the University of Alaska, AnchorageGeological Science
Neutrinos from Stellar Collapse: Comparison of signatures in water and heavy water detectors
Signatures of neutrino and antineutrino signals from stellar collapse in
heavy water detectors are contrasted with those in water detectors. The effects
of mixing, especially due to the highly dense matter in the supernova core, are
studied. The mixing parameters used are those sets allowed by current
understanding of available neutrino data: from solar, atmospheric and
laboratory neutrino experiments. Signals at a heavy water detector, especially
the dominant charged current reactions on deuteron, are very sensitive to some
of these sets of allowed mixing parameters. Theoretical uncertainties on
supernova neutrino spectra notwithstanding, a combination of supernova
measurements with water and heavy water detectors may be able to distinguish
many of these mixing possibilities and thus help in ruling out many of them.Comment: 36 pages Latex file, with 13 postscript figures; important
improvements in the analysis and more detailed presentation of results. To
appear in Phys. Rev.
Neutrino Mixing Predictions of a Minimal SO(10) Model with Suppressed Proton Decay
During the past year, a minimal renormalizable supersymmetric SO(10) model
has been proposed with the following properties: it predicts a naturally stable
dark matter and neutrino mixing angles theta_atm and theta_13 while at the same
time accommodating CKM CP violation among quarks with no SUSY CP problem.
Suppression of proton decay for all allowed values of tan beta strongly
restricts the flavor structure of the model making it predictive for other
processes as well. We discuss the following predictions of the model in this
paper, e.g. down-type quark masses, and neutrino oscillation parameters, U_e3,
delta_MNSP, which will be tested by long baseline experiments such as T2K and
subsequent experiments using the neutrino beam from JPARC. We also calculate
lepton flavor violation and the lepton asymmetry of the Universe in this model.Comment: 22 pages, 11 figure
Aspects of Horava-Lifshitz cosmology
We review some general aspects of Horava-Lifshitz cosmology. Formulating it
in its basic version, we extract the cosmological equations and we use
observational data in order to constrain the parameters of the theory. Through
a phase-space analysis we extract the late-time stable solutions, and we show
that eternal expansion, and bouncing and cyclic behavior can arise naturally.
Concerning the effective dark energy sector we show that it can describe the
phantom phase without the use of a phantom field. However, performing a
detailed perturbation analysis, we see that Horava-Lifshitz gravity in its
basic version suffers from instabilities. Therefore, suitable generalizations
are required in order for this novel theory to be a candidate for the
description of nature.Comment: 10 pages, 4 figures, invited talk given at the 2nd International
Workshop on Dark Matter, Dark Energy and Matter-Antimatter Assymetry,
National Tsing Hua University, Hsinchu, Taiwan, November 5-6, 201
Novel thiol-ene hybrid coating for metal protection
Published: 7 April 2016A novel hybrid anticorrosion coating with dual network of inorganic (Si–O–Si) and organic bonds (C–S–C) was prepared on metal through an in situ sol-gel and thiol-ene click reaction. This novel interfacial thin film coating incorporates (3-mercaptopropyl) trimethoxysilane (MPTS) and 1,4-di(vinylimidazolium) butane bisbromide based polymerizable ionic liquid (PIL) to form a thiol-ene based photo-polymerized film, which on subsequent sol-gel reaction forms a thin hybrid interfacial layer on metal surface. On top of this PIL hybrid film, a self-assembled nanophase particle (SNAP) coating was employed to prepare a multilayer thin film coating for better corrosion protection and barrier performance. The novel PIL hybrid film was characterised for structure and properties using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The corrosion protection performance of the multilayer coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results reveal that this novel double layer coating on metal offers excellent protection against corrosion and has remarkably improved the barrier effect of the coating.Mona Taghaviksih, Surya Subianto, Naba Kumar Dutta and Namita Roy Choudhur
Generating Cosmological Gaussian Random Fields
We present a generic algorithm for generating Gaussian random initial
conditions for cosmological simulations on periodic rectangular lattices. We
show that imposing periodic boundary conditions on the real-space correlator
and choosing initial conditions by convolving a white noise random field
results in a significantly smaller error than the traditional procedure of
using the power spectrum. This convolution picture produces exact correlation
functions out to separations of L/2, where L is the box size, which is the
maximum theoretically allowed. This method also produces tophat sphere
fluctuations which are exact at radii . It is equivalent to
windowing the power spectrum with the simulation volume before discretizing,
thus bypassing sparse sampling problems. The mean density perturbation in the
volume is no longer constrained to be zero, allowing one to assemble a large
simulation using a series of smaller ones. This is especially important for
simulations of Lyman- systems where small boxes with steep power
spectra are routinely used.
We also present an extension of this procedure which generates exact initial
conditions for hierarchical grids at negligible cost.Comment: 12 pages incl 3 figures, accepted in ApJ Letter
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