Aeronautical Development Agency
Aeronautical Development Agency
Kumar D.A.,Government Arts College |
Venugopalan S.R.,Aeronautical Development Agency
International Journal of Advanced Intelligence Paradigms | Year: 2017
Increased use of computer networks, internet and online transactions pose higher risk of intrusions and protecting the information from the hackers/intruders is a new area in computers and network security. The major factors which affect intrusion detection are the system's detection rate and time required to detect intrusions. Many researchers have focused in this area and have used data mining techniques for detecting the intrusions. This paper proposes to classify the dataset initially based on 'protocol type' feature and the performance improvements over traditional way of considering the full data without initial classification. This paper does not advocate any techniques or algorithms, but establishes the fact that by splitting the dataset on Protocol Type feature enhances performance with respect to detection rate and time to build model for intrusion detection. In this study, the well-known KDD Cup 99 intrusion dataset has been tested with the proposed approach. The computational study reveals that the initial classification based on protocol type' attribute increases the performance with respect to rate of detection and time to build model. © 2017 Inderscience Enterprises Ltd.
Padmanabhan M.A.,Aeronautical Development Agency |
Dowell E.H.,Duke University
AIAA Journal | Year: 2017
The presence of a static preload can significantly alter the limit cycle oscillation response of nonlinear aeroelastic systems. This paper reports a numerical study of two distinct types of preload, mechanical (i.e., independent of flow velocity) and aerodynamic (i.e., dependent on flow velocity), and their effects on limit cycle behavior. Simulations are carried out on models of a wing-with-store and an all-moving surface, respectively, with linear potential flow aerodynamics and a localized structural nonlinearity. Novel, computationally efficient methods based on dual-input describing functions are proposed and employed for calculating limit cycles, thereby generalizing earlier work that used single-input describing functions for the no-preload situation. Results are presented for a smooth nonlinearity (cubic hardening) and a nonsmooth one (classical freeplay), along with selected time marching responses. Finally, the feasibility of including nonlinear aerodynamics in the present framework is discussed. Copyright © 2017 by Madhusudan A. Padmanabhan.
Srinivasan P.,Aeronautical Development Agency |
Joshi A.,Indian Institute of Technology Bombay
Advances in Aircraft and Spacecraft Science | Year: 2017
In a flexible airvehicle, an assessment of the structural coupling levels through analysis and experiments provides structural data for the design of notch filters which are generally utilized in the flight control system to attenuate the flexible response pickup. This is necessitated as during flight, closed loop control actuation driven with flexible response inputs could lead to stability and performance related problems. In the present work, critical parameters influencing servoelastic response have been identified. A sensitivity study has been carried out to assess the extent of influence of each parameter. A multi-parameter tuning approach has been implemented to achieve an enhanced analytical model for improved predictions of aircraft servoelastic response. To illustrate the model updation approach, initial and improved test analysis correlation of lateral servoelastic responses for a generic flexible airvehicle are presented. © 2017 Techno-Press, Ltd.
Shishir R.,Aeronautical Development Agency
Proceedings of the International Conference on Electromagnetic Interference and Compatibility | Year: 2017
A Cognitive Radio (CR) is a reconfigurable radio system, consisting of both hardware and software. The presence of hardware entails implementation of Electromagnetic Interference (EMI) protection and also resolution of Electromagnetic Compatibility (EMC) issues. It is of paramount importance that these aforementioned aspects are dealt with correctly by proper design in multi-Transceiver CR networks, so as to negate performance degradation or complete loss of communication. Both generic methodologies of ensuring this aim as well as applicable standards that may be tailored for this application are discussed. Details of a measurement setup that may be utilized are also briefly elucidated in this paper along with simulation results. © 2016 IEEE.
Antony Gratas V.,Aeronautical Development Agency |
Prakash R.,Aeronautical Development Agency
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017
Maintenance of any item during its life cycle plays vital role in determining the effectiveness of the item to customer and the total life cycle cost associated with it, in the long run, till a decision on discard is accorded. It is imperative to minimize the MDT [Mean Down Time] of any item/system so as to achieve the on-demand availability, as high as possible. Designing for maintainability in coherence with functionality and reliability requirements would eventually determine the operational effectiveness of the item. Especially, in the case of fighter aircraft, where availability is required to be ensured to the maximum possible, which is one of the critical factors in determining the battle strike capability of the armed forces. In other words, Maintenance Man Hour per Flight Hour [MMH/FH] is required to be as low as possible, so as to ensure the on-demand availability of the fighting platform. In this aspect, every stages of the design should cater for the target MMH/FH. The MMH/FH is required to be allocated from the user requirements to the systems, through sub-systems to the LRUs. This paper is aimed at, presenting one of the methodologies to allocate the MMH/FH goal to the systems/sub-systems/LRUs, considering all the applicable factors of influence, during the design stage. The proposed Allocation Model has been validated, using a typical fighter aircraft, ensuring correctness and completeness. © 2017, Springer International Publishing AG.
Chennu R.,Aeronautical Development Agency
International Journal of Numerical Methods for Heat and Fluid Flow | Year: 2016
Purpose - The purpose of this paper is to carry out numerical modeling of single-blow transient analysis using FLUENT porous media model for estimation of heat transfer and pressure drop characteristics of offset and wavy fins. Design/methodology/approach - A computational fluid dynamics program FLUENT has been used to predict the design data in terms of j and f factors for plate-fin heat exchanger wavy and offset strip fins, which are widely used in aerospace applications. Findings - The suitable design data in terms of Colburn j and Fanning friction f factors is generated and presented correlations for wavy fins covering the laminar, transition and turbulent flow regimes. Originality/value - The correlations for the friction factor f and Colburn factor j have been found to be good by comparing with other references. The correlations can be used by the heat exchanger designers and can reduce the number of tests and modification of the prototype to a minimum for similar applications and types of fins. © Emerald Group Publishing Limited.
Chennu R.,Aeronautical Development Agency |
Paturu P.,National Institute of Technology Warangal
International Journal of Numerical Methods for Heat and Fluid Flow | Year: 2011
Purpose - In aerospace applications, due to the severe limitations on the weight and space envelope, it is mandatory to use high performance compact heat exchangers (CHEs) for enhancing the heat transfer rate. The most popularly used ones in CHEs are the plain fins, offset strip fins (OSFs), louvered fins and wavy fins. Amongst these fin types, wavy and offset fins assume a lot of importance due to their enhanced thermo-hydraulic performance. The purpose of this paper is to investigate the influence of geometrical fin parameters, in addition to Reynolds number, on the thermo-hydraulic performance of OSFs. Design/methodology/approach - A computational fluid dynamics approach is used to conduct a number of numerical experiments for determination of thermo-hydraulic performance of OSFs considering the various geometrical parameters, which are generally used in the aerospace industry. These investigations include the study of flow pattern for laminar, transition and turbulent regions. Studies are conducted with different fin geometries and comparisons are made with available data in open literature. Finally, the generalized correlations are developed for OSFs taking all geometrical parameters into account for the entire range of operations of the aerospace industry covering laminar, transition and turbulent regions. In addition, the effects of various geometrical parameters are presented as parametric studies. Findings - Thermo-hydraulic design of CHEs is strongly dependent upon the predicted/measured dimensionless performance (Colburn factor "j" and Fanning friction "f" vs Reynolds number Re) of heat transfer surfaces. Several types of OSFs used in the compact plate-fin heat exchangers are analyzed numerically. Research limitations/implications - The present numerical analysis is carried out for "air" media and hence these results may not be accurate for other fluids with large variations of Prandtl numbers. Practical implications - In open literature, these fins are generally evaluated as a function of Reynolds number experimentally, which are expensive. However, their performance will also depend to some extent on geometrical parameters such as fin thickness, fin spacing, offset fin length and fin height. Originality/value - This numerical estimation can reduce the number of tests/experiments to a minimum for similar applications. © Emerald Group Publishing Limited.
Sheik Ismail L.,Aeronautical Development Agency |
Velraj R.,Anna University |
Ranganayakulu C.,Aeronautical Development Agency
Renewable and Sustainable Energy Reviews | Year: 2010
Renewable energy sources like solar energy, wind energy, etc. are profusely available without any limitation. Heat exchanger is a device to transfer the energy from one fluid to other fluid for many applications in buildings, industries and automotives. The optimum design of heat exchanger for minimum pumping power (i.e., minimum pressure drop) and efficient heat transfer is a great challenge in terms of energy savings point of view. This review focuses on the research and developments of compact offset and wavy plate-fin heat exchangers. The review is summarized under three major sections. They are offset fin characteristics, wavy fin characteristics and non-uniformity of the inlet fluid flow. The various research aspects relating to internal single phase flow studied in offset and wavy fins by the researchers are compared and summarized. Further, the works done on the non-uniformity of this fluid flow at the inlet of the compact heat exchangers are addressed and the methods available to minimize these effects are compared. © 2009.
Angappan M.,Aeronautical Development Agency |
Sampath V.,Indian Institute of Technology Madras |
Ashok B.,Aeronautical Development Agency |
Deepkumar V.P.,Aeronautical Development Agency
Materials and Design | Year: 2011
The influence of retrogression and re-aging treatment (RRA) on short transverse tensile properties of 7010 aluminium alloy extrusions was studied. The short transverse ductility of extrusions, which was much lower in the T6 condition, was improved to the optimum level after retrogression and re-aging treatment. It is found that short transverse ductility is influenced by the nature of precipitate particles located along the grain boundary. It is observed that coarsening of the grain boundary precipitates and its copper enrichment that occurs during RRA are found to be the factors responsible for improvement in stress corrosion cracking (SCC) resistance. The optimum retrogression and re-aging schedule is established that gives rise to the best combination of strength, ductility and SCC resistance. © 2011 Elsevier Ltd.
Varuvel A.G.,Aeronautical Development Agency
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015
Loss of control of aircraft is one of the catastrophic safety critical events in the aerospace domain, which results usually into risks of loss of human lives and/or environmental hazards. Triggering of this undesired event could be at any level of hardware and/or software in the digital fly-by-wire fighter aircraft. The contributing factors for this undesirable event and the interrelationships among the basic events are to be carefully accounted, while estimating the loss of control of the fighter aircraft, probabilistically. Components which have the potential to cause failures are required to be treated carefully, by properly considering the failure modes of those components. This paper brings out, the data driven methodology to estimate the probability of control of the aircraft considering all the interdependent components along with the associated failure modes, which have the potential to trigger the occurrence of the undesired event-‘Loss of Control of Aircraft’. The approach presented here would serve as a guideline for estimating the PLOC of any types of aircraft. © Springer International Publishing Switzerland 2015.