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.

High-Resolution Simulation of Mean Convection and Its Intraseasonal Variability over the Tropics in the MRI/JMA 20-km Mesh AGCM

Abstract: Tropical mean convection and its organization on different spatiotemporal scales in a simulation using the Meteorological Research Institute/Japan Meteorological Agency (MRI/JMA) global atmospheric general circulation model (AGCM) at 20-km resolution (TL959L60) has been investigated. Comparison with two lower resolution simulations of 120 km (TL159L40) and 180 km (TL95L40) shows that convection, climatological fields, and moist stability over the Indian Ocean and South Pacific convergence zone are better represented in TL959L60 than in lower resolution simulations. However, the simulated three-dimensional structure of the Walker and Hadley cells, and the vertical structure of convective heating, do not show marked improvement relative to lower resolution simulations. The amplitude and phase speed of convectively coupled equatorial waves show that, although the Kelvin waves, the observed hierarchical structure of cloud clusters associated with the Madden–Julian oscillation (MJO) convection, and th...

Generalized Three-Dimensional Mathematical Models for Force and Stiffness in Axially, Radially, and Perpendicularly Magnetized Passive Magnetic Bearings With “n” Number of Ring Pairs

Abstract: This work deals with generalized three-dimensional (3D) mathematical model to estimate the force and stiffness in axially, radially, and perpendicularly polarized passive magnetic bearings with “n” number of permanent magnet (PM) ring pairs. Coulombian model and vector approach are used to derive generalized equations for force and stiffness. Bearing characteristics (in three possible standard configurations) of permanent magnet bearings (PMBs) are evaluated using matlab codes. Further, results of the model are validated with finite element analysis (FEA) results for five ring pairs. Developed matlab codes are further utilized to determine only the axial force and axial stiffness in three stacked PMB configurations by varying the number of rings. Finally, the correlation between the bearing characteristics (PMB with only one and multiple ring pairs) is proposed and discussed in detail. The proposed mathematical model might be useful for the selection of suitable configuration of PMB as well as its optimization for geometrical parameters for high-speed applications.

Enhanced mechanical properties of acrylate based shape memory polymer using grafted hydroxyapatite

Abstract: In the present study, the effect of grafted and ungrafted hydroxyapatite (HAp) filler on the mechanical properties of acrylate based shape memory polymer (SMP) composite is reported. HAp is grafted with polyethylene glycol methacrylate (PEGMA) monomer to avoid agglomeration and the same is embedded as reinforcement in tBA – PEGDMA matrix (70 wt% tBA: tert-butyl acrylate +30 wt% PEGDMA: polyethylene glycol dimethacrylate). The grafting process improved the interfacial interactions of the particles, dispersed in the polymer system and subsequently enhanced the mechanical properties of the shape memory polymer composites. The morphology of HAp particles is investigated by field emission scanning electron microscopy. The mechanical properties of SMP composites are evaluated at room temperature and above glass transition temperature (Tg) with grafted and ungrafted HAp particles. The addition of grafted HAp significantly improved the tensile strength (40%) and shape recovery rate (25%) of the SMP composite when compared to the SMP composite containing ungrafted HAp. SMP composite containing grafted HAp exhibited higher cell viability compared to the neat SMP and the SMP composite containing ungrafted HAp.