10 research outputs found
Optimization of mechanical properties of chitosan/phenol formaldehyde composite
The Frechet distribution which has a scale and shape parameters, has been found to have wide application in modelling extreme events such as radioactive emission, flood, rainfall, seismic analysis, wind speed, etc. In this research paper, the Bayesian analysis of scale parameter of Frechet distribution was considered. It is necessary to know the best combination of prior distribution and loss function for the parameter estimation. Posterior distribution was derived by uniform and Jeffrey’s prior under the square error, Precautionary, Quadratic and Weighted balance loss function. Bayes estimation and their corresponding risk was obtained by the above stated priors and loss function. Monte Carlo simulations was conducted to compare the performance of the estimators. It is evident that weighted balance loss function when used with uniform prior provides the least posterior risk.Keywords: Frechet Distribution, Non-Informative Prior, Bayesian Estimation, Loss Functions, Monte Carlo Simulation
Effect of particle size on tensile properties and density of Delonix regia seed particles filled unsaturated polyester resin composites
This study was aimed at examining the effect of particle size on the tensile properties and density of Delonix regia seed particles (DSP) filled unsaturated polyester resin (UPR) composites. The composites were fabricated using a glass mould via hand mixing, and the average DSP particle sizes of 100, 200, 300, 400, and 500 μm were used at 12 % filler loading. The effect of particle size on the tensile properties and density of DSP-filled unsaturated polyester resin was investigated. The results showed a decrease in tensile strength, tensile modulus, elongation at break, and density as the filler particle size increased. The smallest particle size (100 μm) has the highest values of tensile strength, tensile modulus, elongation at break (%) and density with the corresponding values of 35.43 MPa, 0.47 GPa, 7.09% and 1.22 g/cm3 and the largest particle size (500 μm) with values of 15.25 MPa, 0.28 GPa, 5.17% and 1.12 g/cm3 respectively
Reconstruction of the Primordial Power Spectrum by Direct Inversion
We introduce a new method for reconstructing the primordial power spectrum,
, directly from observations of the Cosmic Microwave Background (CMB). We
employ Singular Value Decomposition (SVD) to invert the radiation perturbation
transfer function. The degeneracy of the multipole to wavenumber
linear mapping is thus reduced. This enables the inversion to be carried out at
each point along a Monte Carlo Markov Chain (MCMC) exploration of the combined
and cosmological parameter space. We present best--fit obtained
with this method along with other cosmological parameters.Comment: 23 pages, 9 figure
Smooth hybrid inflation in supergravity with a running spectral index and early star formation
It is shown that in a smooth hybrid inflation model in supergravity adiabatic
fluctuations with a running spectral index with \ns >1 on a large scale and
\ns <1 on a smaller scale can be naturally generated, as favored by the
first-year data of WMAP. It is due to the balance between the nonrenormalizable
term in the superpotential and the supergravity effect. However, since smooth
hybrid inflation does not last long enough to reproduce the central value of
observation, we invoke new inflation after the first inflation. Its initial
condition is set dynamically during smooth hybrid inflation and the spectrum of
fluctuations generated in this regime can have an appropriate shape to realize
early star formation as found by WMAP. Hence two new features of WMAP
observations are theoretically explained in a unified manner.Comment: 12 pages, 1 figure, to appear in Phys. Rev.
Reconstruction of the Primordial Power Spectrum using Temperature and Polarisation Data from Multiple Experiments
We develop a method to reconstruct the primordial power spectrum, P(k), using
both temperature and polarisation data from the joint analysis of a number of
Cosmic Microwave Background (CMB) observations. The method is an extension of
the Richardson-Lucy algorithm, first applied in this context by Shafieloo &
Souradeep. We show how the inclusion of polarisation measurements can decrease
the uncertainty in the reconstructed power spectrum. In particular, the
polarisation data can constrain oscillations in the spectrum more effectively
than total intensity only measurements. We apply the estimator to a compilation
of current CMB results. The reconstructed spectrum is consistent with the
best-fit power spectrum although we find evidence for a `dip' in the power on
scales k ~ 0.002 Mpc^-1. This feature appears to be associated with the WMAP
power in the region 18 < l < 26 which is consistently below best--fit models.
We also forecast the reconstruction for a simulated, Planck-like survey
including sample variance limited polarisation data.Comment: 8 pages, 5 figures, comments welcom
Primordial power spectrum from WMAP
The observed angular power spectrum of the cosmic microwave background
temperature anisotropy, , is a convolution of a cosmological radiative
transport kernel with an assumed primordial power spectrum of inhomogeneities.
Exquisite measurements of over a wide range of multipoles from the
Wilkinson Microwave Anisotropy Probe (WMAP) has opened up the possibility to
deconvolve the primordial power spectrum for a given set of cosmological
parameters (base model). We implement an improved (error sensitive)
Richardson-Lucy deconvolution algorithm on the measured angular power spectrum
from WMAP assuming a concordance cosmological model. The most prominent feature
of the recovered is a sharp, infra-red cut off on the horizon scale. The
resultant spectrum using the recovered spectrum has a likelihood far
better than a scale invariant, or, `best fit' scale free spectra
( {\it w.r.t.} Harrison Zeldovich, and, {\it w.r.t.} power law with ). The recovered has a
localized excess just below the cut-off which leads to great improvement of
likelihood over the simple monotonic forms of model infra-red cut-off spectra
considered in the post WMAP literature. The recovered , in particular,
the form of infra-red cut-off is robust to small changes in the cosmological
parameters. We show that remarkably similar form of infra-red cutoff is known
to arise in very reasonable extensions and refinements of the predictions from
simple inflationary scenarios. Our method can be extended to other cosmological
observations such as the measured matter power spectrum and, in particular, the
much awaited polarization spectrum from WMAP.Comment: 20 pages, 12 figures, uses Revtex4, Matches version accepted to Phys.
Rev. D. More extensive discussion of the method in the appendix, references
added and typos correcte
Effects on the electro-mechanical properties of aniline-doped polyester fibric
The effects of Electro-mechanical properties of doped polyester fabric with aniline were investigated. The effects of various concentrations on the electrical as well as mechanical were examined and the percolation threshold was established. Chemical polymerization of aniline on Polyester in hydrochloric acid using potassium dichromate as oxidant was carried out. Polyester based conductive polymer composites were prepared by means of melt mixing with a twin screw. The samples were investigated for electrocoductivity and mechanical properties. The results obtained shows polyester fabric became electrically conductive at a percolation threshold between 1-2.5% concentrations and also the electrical conductivity increased with the concentration, up to 5.0x10-3 S/m at 5 % concentration. The tensile characteristics such as average breaking force, work-to-rupture, and % elongation, of the fabric were all improved. Also Scanning Electron Microscope (SEM) analysis of the samples was studied.Keywords: Doped, percolation, threshold, conductivity, elongatio