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, $P(k)$, 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 $\ell$ to wavenumber $k$ 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 $P(k)$ and cosmological parameter space. We present best--fit $P(k)$ 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, $C_l$, is a convolution of a cosmological radiative transport kernel with an assumed primordial power spectrum of inhomogeneities. Exquisite measurements of $C_l$ 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 $P(k)$ is a sharp, infra-red cut off on the horizon scale. The resultant $C_l$ spectrum using the recovered spectrum has a likelihood far better than a scale invariant, or, `best fit' scale free spectra ($\Delta\ln{\cal L}=25$ {\it w.r.t.} Harrison Zeldovich, and, $\Delta\ln{\cal L}=11$ {\it w.r.t.} power law with $n_s=0.95$). The recovered $P(k)$ 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 $P(k)$, 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