Defence Research and Development Laboratory

About: Defence Research and Development Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Mach number & Turbulence. The organization has 404 authors who have published 420 publications receiving 4183 citations. The organization is also known as: DRDL.

2 Loop Nonlinear Dynamic Inversion Fuel Flow Controller Design for Air to Air Ducted Ramjet Rocket

Abstract: Fuel Flow controller based ramjet propulsion system have a flexibility to change rocket velocity depending on guidance requirement by controlling the fuel flow rate as a function of atmospheric conditions like altitude, Mach no. and angle of attack. In this paper, Design objectives & requirements of fuel flow controller have been brought out from guidance loop for air-to-air target engagement. 2-loop non-linear dynamic inversion (DI) based controller design has been proposed to track the commanded thrust and to meet the time constant requirement as a function of altitude, Mach no. and angle of attack. The outer thrust loop is to control commanded thrust and to generate the demand for gas generator pressure loop and inner pressure loop is to meet outer loop demand by controlling throttle valve area. The engine state space plant model has been adapted with improvement of existing model. Throttle valve actuator specifications requirement are also brought out.

New Trends in Cryptography by Quantum Concepts

Abstract: Communication of key to the receiver of cipher message is an important step in any cryptographic system. But the field of cryptanalysis is also progressing keeping pace with progress in cryptography and everyday newer and faster computers with more and more memory space are appearing. Increasing the vulnerability of key distribution process and in turn vulnerability of secret message. People are exploring totally different areas of technology in search of a secure key distribution system. "Quantum cryptography" is one such technology with promises for future. This paper describes issues related to integrity check of quantum cryptography based on qbits.

Design of Fixture for Trimming of a Composite Material Shim by Abrasive Water Jet Machining

Abstract: The fixtures required in manufacturing must correctly locate workpiece in a given orientation with respect to cutting tool. The present work aims at design of fixture for trimming of a component called shim which is made of composite material. The trimming is done by abrasive water jet machine. Machining by conventional methods compromise the strength of the composite materials and/or cause delamination, making it less suitable for aerospace applications, thus Abrasive Water Jet (AWJ) technology is used for machining composite materials. In present work, the shim made of composite material is required to be cut at specified orientation at given location in a circular path. Since the shim is a thin-walled structure, excess clamping force may deform it and it may not get cut at required positions, although sufficient support and clamping is required to hold the component during trimming operation by water jet machining. The fixture needs to be designed for an abrasive water jet machine in which the water jet nozzle head is stationary and automation, e.g., rotary table is not available for maintaining circular cut at specified location and orientation. A fixture is designed to meet the above requirements. The suitable rotational speed to cut the shim is found experimentally and the shim is cut in circular path at desired location on the fixture.

Integrated Process for Smooth Transition from Development to Production of Weapon Systems

Abstract: Production of weapon systems has proven to be as difficult as their development. The transition from development to production encompasses innumerable efforts to take a weapon system from laboratory into full-scale production. These efforts may span the development and production phases and constitute a major determinant of a weapon system's production costs. Besides, Indian manufacturers/production units, who seek know-how, generally go to foreign manufacturers and obtain complete production know-how. Obviously, they expect same kind of technological support, which are the preserves of the manufacturers'. An attempt has been made for the first time by Defence Research & Development Laboratory (DRDL), Hyderabad for a technology transfer of highly sophisticated missiles to production agency. Experiences show that the technology receiver (i.e. production agency) should have a willingness to receive the technology and the technology donor should understand the culture of technology receiver and recode/restructure the technological information to fit into the technology receiver's domain. Production planning and preparations were conducted throughout the development phase to identify production requirements and to resolve the difficulties before production begins to achieve quality products. A unique technology transfer mechanism has been evolved and implemented successfully for one of the weapon systems developed by DRDL, Hyderabad. Production agencies have demonstrated their capability to produce subsystems of a weapon system of desired quality within the time schedule and cost by the time the weapon system performance was demonstrated to the users. Also, the deliveries of systems of development hardware continued into the production phase and production deliveries began with no line interruption.

Design of a Dual Mode Tunable Narrow Bandpass Filter

Abstract: This paper describes the design of a dual mode [1] tunable narrow bandpass circular waveguide cavity filter operating in two orthogonal TE12, modes. One of the end walls of the cavity is moved to change the tuned frequency. Circular waveguide cavity is coupled on the sidewalls from a standard rectangular waveguide end through a thin iris. Quantitative details for such type of coupling are not available in the literature. Coupling coefficients are evaluated using the modal analysis [2] and the results are used for the design of the filter.