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On the refractive index of rutile

REA Auditado

There are several reports on the measurement of the refractive indices of single-crystal rutile. Whereas the ordinary refractive indices estimated are in close agreement over a wide range of wavelengths, there is a significant difference in the corresponding values of the extraordinary refractive indices. Observations on the `prism-coupling technique' using rutile prisms are reported, to show that for the refractive indices of rutile, the work of W.H. Bond, see J. Appl. Phys., vol.36, p.1674, 1965; represents a better standard

Tema: general: 

• Ciencias›Física

Evaluation of generation system reliability indices by fast transform techniques

REA Auditado

Two computationally ejicient Fourier transform methods namely, the mixed radix Fast Fourier transform algorithm (FFTA) and the Winograd Fourier transform algorithm ( WFTA) for evaluating the reliability of a power system are presented in this paper. Both the methods are used to evaluate the reliability of the IEEE reliability test system and they are compared with the direct discrete Fourier transform method and the basic recursive approach in terms of accuracy and computer time. A sensitivity analysis has been performed by variation of a few system variables to compare the two methods.

Tema: general: 

• Ciencias

Surface analysis of a black copper selective coating

REA Auditado

This paper presents the surface analysis of a black copper selective coating using AES and XPS techniques. This study indicates that the textured black copper selective coating is a multiphase system. These surfaces are stable up to 250°C in air and under vacuum conditions. Subsequent annealing of these surfaces to temperatures > 370°C shows significant changes. The external environment exposed surface has indicated no significant change.

Tema: general: 

• Ciencias›Física

An approach to the estimation of the value of agricultural residues used as biofuels

REA Auditado

A simple demand side approach for estimating the monetary value of agricultural residues used as biofuels is proposed. Some of the important issues involved in the use of biomass feedstocks in coal-fired boilers are briefly discussed along with their implications for the maximum acceptable price estimates for the agricultural residues. Results of some typical calculations are analysed along with the estimates obtained on the basis of a supply side approach (based on production cost) developed earlier.

Tema: general: 

• Ciencias

Biofuel mix for cooking in rural areas:implications for financial viability of improved cookstove

REA Auditado

An attempt to study the financial implications of
replacing a traditional biofuel cookstove with an
improved one has been made. The role of several
factors influencing the cost of an improved cookstove has been discussed. The capital cost of a l~opular port- able metallic cookstove design in India has been expressed in functional form and the fuel savings have been quantified in terms of two cookstove performance indicators--overall thermal efficiency of a pot-cook- stove combination and specific fuel consumption of a cookstove.

Tema: general: 

• Ciencias

Raman, photoluminescence and optical absorption studies on nanocrystalline silicon

REA Auditado

Raman, photoluminescence (PL) and optical absorption results on silicon nanocrystals in SiO2 matrices prepared by RF sputtering method are presented. The samples have varying Si/SiO2 compositional fraction and are annealed at different temperature and duration. The average size of the nanocrystals is determined by the lineshape analysis of the first-order Raman spectra. Raman results further indicate the existence of a threshold annealing temperature for the formation of nanocrystals and increase in the nanocrystal size with increasing temperature and duration.

Tema: general: 

• Ciencias›Física

Mechanism in Nb doped titania oxygen gas sensor

REA Auditado

Doping in titania (TiO2) with pentavalent Nb+5 metal ion has shown significant enhancement in the sensitivity which is about 65 times higher than the undoped material at lower operating temperatures. The higher sensitivity and the shorter response time has been observed with low concentration of Nb doping i.e. 0.05, 0.2 and 0.4 wt.% Nb at 400°C. The electronic interaction of TiO2 with Nb metal ion has been investigated using x-ray photoelectron spectroscopy (XPS).

Tema: general: 

• Ciencias›Física

Raman investigation of InSe doped with GaS

REA Auditado

The Raman spectrum of lnSe doped with GaS exhibits appreciable changes at low doping densities indicating considerable changes on introducing GaS. The photoluminescence as well as resonance Raman study shows that the exciton energy is shifted towards higher energy as a result of doping. At resonance, both the one- and two-phonon polar modes are observed, although
considerably broadened. This indicates that the GaS-doped InSe develops significant topological disorder.

Tema: general: 

• Ciencias›Física

Hydrogen Profiling and the Stoichiometry of an a-Sin:H Film

REA Auditado

The stoichiometry of a-SiN, : H films is determined by conventional elastic recoil detection analysis (ERDA) using 90 MeV 58 Ni ions. Hydrogen depth profiling indicated that the non-uniformity in H concentration across the film thickness is about 12%. The present experiment indicated the capability of conventional ERDA for
simultaneous multi-element detection in a thin film sample (having well-separated masses) without the use of a sophisticated detection system.

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• Ciencias›Física

Preparation and characterization of spray-pyrolysed BaTiO3 films

REA Auditado

Thin films of BaTiO3 were prepared by spray pyrolysis of BaTiO3 sol. The structural and dielectric characteristics of these films are reported in this study. The results indicate that spray pyrolysis could be an useful technique to prepare homogenous, capacitor-grade BaTiO3 thin films. The pyroelectric characteristics of BaTiO3/PVDF composites prepared from spray-pyrolysed BaTiO3 films are also reported.

Tema: general: 

• Ciencias›Física