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Hyderabad, India

Karunanidhi S.,Research Center Imarat | Singaperumal M.,Indian Institute of Technology Madras
Sensors and Actuators, A: Physical | Year: 2010

Flapper-nozzle type Electro Hydraulic Servo Valve (EHSV) operated by conventional torque motor actuators has been used in wide range of industrial applications. As their bandwidths are limited, they are not suitable for high-speed applications. The work presented in this paper deals with the mechatronic approach for the design of a magnetostrictive actuator with flexure amplifier and a magnetically biased magnetostrictive actuator for application in high frequency flapper-nozzle servo valve. A magnetostrictive actuator has been designed, built and integrated into an existing flapper-nozzle servo valve by replacing the torque motor. Incorporating the dynamics of the magnetostrictive actuator, the dynamics of the valve was simulated. Necessary parameters for the actuator have been arrived by finite element model. No load flow characteristics are analyzed and compared with experimental values. Step response has been compared with conventional valve. The results show that the valve has satisfactory static and dynamic characteristics for applications in high-speed actuation systems. © 2009 Elsevier B.V. All rights reserved. Source


Das A.K.,International Institute of Information Technology, Hyderabad | Sharma P.,International Institute of Information Technology, Hyderabad | Chatterjee S.,Research Center Imarat | Sing J.K.,Jadavpur University
Journal of Network and Computer Applications | Year: 2012

Most queries in wireless sensor network (WSN) applications are issued at the point of the base station or gateway node of the network. However, for critical applications of WSNs there is a great need to access the real-time data inside the WSN from the nodes, because the real-time data may no longer be accessed through the base station only. So, the real-time data can be given access directly to the external users (parties) those who are authorized to access data as and when they demand. The user authentication plays a vital role for this purpose. In this paper, we propose a new password-based user authentication scheme in hierarchical wireless sensor networks. Our proposed scheme achieves better security and efficiency as compared to those for other existing password-based approaches. In addition, our scheme has merit to change dynamically the users password locally without the help of the base station or gateway node. Furthermore, our scheme supports dynamic nodes addition after the initial deployment of nodes in the existing sensor network. © 2012 Elsevier Ltd. Source


Jahagirdar D.R.,Research Center Imarat
IEEE National Radar Conference - Proceedings | Year: 2012

A miniature DDS-based FMCW radar has been realized with dynamic range as high as 80 dB. A FMCW radar has many application as on-board sensor. The FMCW radar is a precision range measuring instrument. Hence it can be used for a variety of applications in aircrafts, helicopters and missiles. This paper describes in brief the design of one unique system which has been designed to operate in various modes. The difference come only at software level and setting of different thresholds for different applications. The major design difference here is the use of DDS to directly generate FMCW waveform and up-convert it to RF. It has many advantages over conventional FMCW signal generation. A linear FMCW system has been designed around this concept which resulted in sensitivity as good as -122 dBm and a high degree of slope linearity and repeatable in multiple units. A variety of antennas designed for different roles have made the system adaptable to various platform. The paper also shows results obtained and a critical comments on performance of total system and subsystems. © 2012 IEEE. Source


Karunanidhi S.,Research Center Imarat | Singaperumal M.,Indian Institute of Technology Madras
Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering | Year: 2010

A conventional two-stage servo valve basically consists of an electrically operated torque motor as the first stage and spool valve as the second stage. Owing to the limitation in the band width, servo valves are not suitable for high-frequency applications. The work presented in this paper deals with the methodology of the mechatronics approach for the design of a piezoelectric actuator with a mechanical amplifier and its integration into a servo valve. The analysis and simulation of a multilayer piezoelectric actuator (MLA) a with mechanical amplifier for high-frequency application has been done using icon-based bond graph technique and finite element coupled field analysis for the commercially available piezoelectric actuator. The designed piezoelectric actuator was integrated into an existing flapper-nozzle servo valve by replacing the first stage. The dynamics of the valve integrated into a piezoelectric actuator has been simulated. The required simulation parameters for the actuator have been derived from a finite element model. An experimental set-up has been designed and the integrated testing of the servo valve with piezoelectric actuator has been carried out to determine the no-load flow gain of the valve. Also the time response has been measured for a conventional servo valve and servo valve with piezoelectric actuator. The designed valve with a piezoelectric actuator has satisfactory static and dynamic characteristics for high-speed applications. © Authors 2010. Source


Chattaraj S.,Bengal Engineering and Science University | Mukherjee A.,Bengal Engineering and Science University | Chaudhuri S.K.,Research Center Imarat
Gyroscopy and Navigation | Year: 2013

Transfer alignment is the process of initializing the navigation sensors of tactical guided munitions launched from a platform. Through this method the misalignment between aligning and aligned body is estimated, which facilitates navigation of aligning system during its post-ejection course of flight. Measurements provided by navigation sensors of aligning system are noisy compared to those of the launch platform. Thus, excitation of the platform in the form of some deliberate manoeuvre is important in order to discriminate the signal from noise in the available measurement so that the misalignment can be effectively estimated. With advancement of technology, the prerequisites of accurate alignment have changed and with it the algorithms have also undergone continuous transformations. Extensive work has been done on this topic over the years. Here a detailed review of the evolution of transfer alignment problem has been presented. Emphasis is on statistical and algorithmic aspects of the problem rather than time line of work already done. This review provides a general guideline for new entrants to this field and should help practitioners with information regarding trends of research on this topic. © Pleiades Publishing, Ltd., 2013. Source

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