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Institution

National Aerospace Laboratories

FacilityBengaluru, India
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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, microstructural, thermo-optical and electrical properties along with XPS studies for evaluating oxidation states of the as-received and degraded GBP films have been investigated thoroughly.
Abstract: Sunshield membranes made of germanium coated black polyimide (GBP) or Kapton are often used on the reflector/transmitter antenna of satellites for thermal control applications. However, the germanium top layer is prone to degrade during ground storage and implementation. Hence vacuum/inert gas sealed packaging is required for storing the membranes, followed by a staggered fabrication schedule as the shelf-life of the GBP is identified as only ~ 6 months. In the present study, microstructural, thermo-optical and electrical properties along with XPS studies for evaluating oxidation states of the as-received and degraded GBP films have been investigated thoroughly. The radio frequency (RF) loss behaviour of both the films has also been studied for S band (2.5 GHz- 3.5 GHz), Ku band (10.5 GHz- 14.5 GHz) and Ka Band (30 GHz- 35 GHz).

11 citations

Journal ArticleDOI
TL;DR: In this article, a finite element formulation based on the Fourier law of heat conduction is presented to analyze the transient temperature distribution in rectangular fiber-reinforced composite plates, where three-dimensional twenty-noded brick elements are used to discretize the spatial domain of the plate.
Abstract: A finite element formulation based on the Fourier law of heat conduction is presented to analyze the transient temperature distribution in rectangular fiber-reinforced composite plates. Three-dimensional twenty-noded brick elements are used to discretize the spatial domain of the plate. A Crank-Nicolson time marching scheme is used to solve the resulting time-dependent ordinary differential equations. The finite element solution is tested for convergence of results with mesh refinement. Further, the FEM is validated comparing the qualitative nature of results obtained for a plate made of aluminium and steel laminae with that of Tanigawa et al. Results are presented for graphite/epoxy and graphite-kevlar/epoxy plates subjected to different thermal boundary conditions. Laminae with fiber orientations of 0°, ±45°, and 90° are considered for the analysis. The results indicate that the temperature variation in the plane of the plate (x-y plane) is very much dependent on the boundary conditions. When the faces ...

11 citations

Journal ArticleDOI
TL;DR: Variable-to-fixed-length coding implementations, according to the Tunstall algorithm, are shown to be significantly less complex than fixed- to-variable- length coding schemes such as the Huffman scheme.
Abstract: Variable-to-fixed-length coding implementations, according to the Tunstall algorithm, are shown to be significantly less complex than fixed-to-variable-length coding schemes such as the Huffman scheme. A modified version of Tunstall coding is presented, with improved compression ratio.

11 citations

Journal ArticleDOI
TL;DR: In this article, the influence of rare earth cerium on the ternary NiCeP-2 deposit properties was analyzed, and it was observed that the co-deposition of cerium in NiP matrix improved the continuous salt spray exposure for 168 h.

11 citations

Proceedings ArticleDOI
16 Aug 2001
TL;DR: In this paper, the effects of surface distortion on antenna performance on a side-looking airborne radar (SLAR) antenna on a reconnaissance pod mounted on a fighter type aircraft were investigated.
Abstract: Conformal antennas on aircraft allow the use of non-conventional antenna locations such as the skin of the aircraft. However, when antennas are installed at these locations they are subject to steady and unsteady aerodynamic loads. The inertial forces and these aerodynamic loads will cause deformations and vibrations of the total antenna surface. The effect of these distortions on antenna performance will be most significant on highly directional antennas. The aim of the present paper is to describe technology development for estimating the effects of surface distortion on antenna performance. The technology is applied to a Side-Looking Airborne Radar (SLAR) antenna on a reconnaissance pod mounted on a fighter type aircraft. This generic SLAR antenna is a phased array antenna covering two faces of the pod: one part on the vertical side face and one part on the lower face of the pod. Radiation patterns are computed for distorted antenna surfaces. The computational model for the determination of the disturbed radiation pattern is based on geometrical parameterisation of the Stratton-Chu integral equations.

11 citations


Authors

Showing all 1850 results

NameH-indexPapersCitations
Harish C. Barshilia462366825
K.S. Rajam42834765
Kozo Fujii394115845
Parthasarathi Bera391365329
R.P.S. Chakradhar361664423
T. N. Guru Row363095186
Takashi Ishikawa361545019
Henk A. P. Blom341685992
S. Ranganathan332115660
S.T. Aruna331014954
Arun M. Umarji332073582
Vinod K. Gaur33924003
Keisuke Asai313503914
K. J. Vinoy302403423
Gangan Prathap302413466
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202310
202216
2021143
2020100
201996
2018119