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.

INS/GPS fusion architectures for unmanned aerial vehicles

Abstract: Purpose – The purpose of this paper is to present fusion of inertial navigation system (INS) and global positioning system (GPS) for estimating position, velocities, attitude and heading of an unmanned aerial vehicle (UAV). Design/methodology/approach – A 15-state extended Kalman filter (EKF) and a split architecture consisting of six-state nonlinear complementary filter (NCF) and nine-state EKF are investigated in detail. In both these fusion architectures GPS and inertial measurement unit consisting of three axis accelerometers, three axis rate gyros and three axis magnetometer have been fused in open loop fashion (loosely coupled) to estimate the navigation states. Findings – These architectures have been implemented in MATLAB/SIMULINK environment and evaluated in closed loop guidance of Black-Kite MAV with software-in-the-loop-simulation (SILS) setup. Furthermore, both the algorithms are validated with flight test data obtained from on-board data logger using an off-the shelf autopilot board (Ardupilo...

Microstructure and electrical properties of plasma sprayed Gd0.15Ce0.85O2-δ coatings from solution combustion synthesized flowable powders

Abstract: tPowders of Gadolinia doped Ceria (Gd0.15Ce0.85O2-�(GDC)), a promising electrolyte material for inter-mediate temperature solid oxide fuel cell has been prepared by solution combustion (SC) synthesis.Variation of fuel to oxidizer ratio in the synthesis results in the GDC powder with varied powder charac-teristics. Fuel deficient combustion reaction results in GDC powder with smaller crystallites size but withlarger agglomerates; whereas reaction with near stochiometric amount of fuel leads to the GDC powderwith larger crystallite size and smaller agglomerates. Powders with large agglomerates possess requiredparticle size, shape and flowability characteristics appropriate for plasma spraying. Electrolyte coatingsfabricated from the synthesized plasma spray grade powders exhibit superior inter splat adhesion andconductivity (∼0.02 S/cm at 600◦C). Dense nature of the coating is ascribed to the complete melting ofthe porous GDC particles in the plasma flame. Powders prepared with stochiometric fuel are suitable fortape casting process.

Thermal and toughness property studies on a polybenzimidazole-modified epoxy resin system

Abstract: The effect of polybenzimidazole (Pill) on a silica-filled epoxy resin matrix has been investigated. Polybenzimidazole (PBI) was incorporated into a difunctional epoxy resin matrix to the extent of 10%, before being cured with an anhydride hardener. The effects of Pill on the curing reaction and glass transition temperature (Tg) and on the toughness of the cured epoxy matrix have been studied using differential scanning calorimetry (OSC), thermogravimetric ctric analysis (TGA) and a universal testing machine (Instron). The results indicate that the PBI modifier enhanced not only the glass transition temperature of the difunctional epoxy m.atrix but also its toughness, by its catalytic action. Further investigations have been carried out on the fractured specimens, using scanning electron microscopy (SEM) to support the enhanced toughness property of the epoxy matrix.

Exact solutions for Stokes flow in and around a sphere and between concentric spheres

Abstract: A general method is suggested for deriving exact solutions to the Stokes equations in spherical geometries. The method is applied to derive exact solutions for a class of flows in and around a sphere or between concentric spheres, which are generated by meridional driving on the spherical boundaries. The resulting flow fields consist of toroidal eddies or pairs of counter-rotating toroidal eddies. For the concentric sphere case the exact solution when the inner sphere is in instantaneous translation is also derived. Although these solutions are axisymmetric, they can be combined with swirl about a different axis to generate fully three-dimensional fields described exactly by simple formulae. Examples of such complex fields are given. The solutions given here should be useful for, among other things, studying the mixing properties of three-dimensional flows.