National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

Development of robust VAD schemes for Voice Operated Switch application in aircrafts: Comparison of real-time VAD schemes which are based on Linear Energy-based Detector, Fuzzy Logic and Artificial Neural Networks

Abstract: In a fighter aircraft, for the optimal usage of resources during transmission of signals, a Voice Operated Switch (VOS) is used, as it is considered as a better option compared to push to talk (PTT), because it gives hands free environment for the pilot to carry out other crucial tasks. The heart of VOS is a Voice Activity Detection (VAD) algorithm. This paper explores the evolution of a reliable, robust VAD scheme for VOS application in aircraft by comparing real-time robust VAD schemes, which are based on energy-based detectors, fuzzy logic and ANN. MATLAB, is used as the simulation platform and actual fighter aircraft cockpit noise record is used for evaluation of the algorithms.

Mean atomic volume, Tg and electrical conductivity of Cux(As0.4Te0.6)100−x glasses

Abstract: Results of measurements of the mean atomic volume (V), the glass transition temperature (Tg) and the electrical conductivity (σ) on 12 compositions of the Cux(As0.4Te0.6)100 − x glasses, with x from 0 to 20 at.%, are reported and discussed. A reduction in V and a constancy of Tg are observed as Cu varies from 0 to 3 at.%. To this stage, the Cu atoms occupy interlayer positions in the layered network of the parent As0.4Te0.6 glass. The σ of glasses with ⩽3 at.% of Cu, are less than that of the parent glass. For Cu>3 at.%, Cu forms bonds with Te and the glasses become regular three component As–Te–Cu glasses. Due to this bonding, changes in slope occur in the V as a function of composition and Tg as a function of composition at Cu content of 3 at.%. The results are examined using a model which envisages the formation of Cu2Te, As2Te3 and As structural units in these glasses. For Cu>3 at.%, a decrease of the conductivity activation energy and an increase of σ occur with increasing Cu content.

Corrosion behaviour of tetrahedral amorphous carbon (ta-C) filled titania nano tubes

Abstract: TiO2 nanotubes were formed by anodic oxidation on Ti–6Al–7Nb and the nanotubes were filled with tetrahedral amorphous carbon (ta-C) by cathodic arc evaporation (CAE). The samples were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and micro Raman studies. The corrosion behaviour of the Ti–6Al–7Nb substrate, substrate with self-organized TiO2 nanotubes (TNT) and ta-C filled TiO2 nano tubes (ta-C TNT) were investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks' solution). The investigations show that the native oxide on the sample is replaced by a self assembled nano array by an anodisation process and the pores can be filled with ta-C. Potentiodynamic polarization and electrochemical impedance studies of ta-C filled TNT sample show that the corrosion resistance is comparable with TNT samples.