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.

Relaminarization in highly favourable pressure gradients on a convex surface

Abstract: The active stiffening and active compensation analyses are carried out to present the influence of active stiffness on the dynamic behaviour of piezo-hygro-thermo-elastic laminates. A coupled piezoelectric finite element formulation involving a hygrothermal strain field is derived using the virtual work principle and is employed in a nine-noded field consistent Lagrangian element. The closed-loop system is modelled with elastic stiffness, active stiffness introduced by isotropic actuator lamina and geometric stiffness due to stresses developed by hygrothermal strain. Through a parametric study, the influence of active stiffening and active compensation effects or the dynamics of cross-ply and angle-ply laminated plates and shells are highlighted. The active stiffening on thin shells is significantly influenced by boundary effects and the actuator efficiency further decreases with increase in curvature. The reduction in natural frequencies of cross-ply laminates due to hygrothermal strain is actively compensated by active stiffening; however, it is observed that the actuator performance reduces significantly with increase in curvature particularly in angle-ply laminates, which demands the use of directional actuators. The active stiffening and active compensation effects are low in moderately thick piezo-hygro-thermo-elastic plates and shells, which are less influenced by boundary conditions

Volumetric effect of topology in chalcogenide glass systems

Abstract: Topological models of glass structure predict features in the property versus the average coordination number, Z, plots at Z ⋍ 2.40 and at Z ⋍ 2.67 . Topological and chemical ordering effects coexist in chalcogenide network glasses and therefore features due to topological effects are not clearly seen in many systems. The volumetric effect, Vt, of topological origin has been determined by subtracting from the measured mean atomic volume, Vm, the volume, Vc, calculated by taking into account the effects of chemical ordering. The Vm versus Z and Vt versus Z plots have been examined for several binary and ternary systems. While the Vm versus Z plots of these systems have different appearances, their Vt versus Z plots exhibit similar features, with a minimum in V t at Z ⋍ 2.40 and a local maximum in V t at Z ⋍ 2.67 .

Mitigating the Surface Degradation and Voltage Decay of Li1.2Ni0.13Mn0.54Co0.13O2 Cathode Material through Surface Modification Using Li2ZrO3.

Abstract: In the quest to tackle the issue of surface degradation and voltage decay associated with Li-rich phases, Li-ion conductive Li2ZrO3 (LZO) is coated on Li1.2Ni0.13Mn0.54Co0.13O2 (LNMC) by a simple wet chemical process. The LZO phase coated on LNMC, with a thickness of about 10 nm, provides a structural integrity and facilitates the ion pathways throughout the charge–discharge process, which results in significant improvement of the electrochemical performances. The surface-modified cathode material exhibits a reversible capacity of 225 mA h g–1 (at C/5 rate) and retains 85% of the initial capacity after 100 cycles. Whereas, the uncoated pristine sample shows a capacity of 234 mA h g–1 and retains only 57% of the initial capacity under identical conditions. Electrochemical impedance spectroscopy reveals that the LZO coating plays a vital role in stabilizing the interface between the electrode and electrolyte during cycling; thus, it alleviates material degradation and voltage fading and ameliorates the elec...