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.

Novel Privacy Preserving Authentication Scheme Based on Physical Layer Signatures for Mobile Payments

Abstract: Financial transaction through smart mobile devices is an attractive feature in today’s modern wireless network era. Despite having various advantages, privacy and security are always challenging in such services. A novel hybrid security scheme based on physical layer signature and cryptography has been proposed to provide a secured authentication scheme preserving user’s privacy, for the application of mobile payments. This scheme provides two levels of authentication, privacy preserving location authentication and device authentication. User’s privacy is preserved by encrypting the identity of the user by physical layer encryption based on user’s location. Physical layer signatures such as channel state information and carrier frequency offset are used for physical layer encryption. In conventional techniques, Media Access Control (MAC) address is used for initial authentication and they are shared without encryption. In this proposed technique, MAC is encrypted using the secret key derived from physical layer signatures using Singular Value Decomposition (SVD) to preserve privacy. Since secret key, generated using SVD, is location specific and varies with respect to the location, it is used for the location authentication. User authentication, required for mobile payment, is realised using asymmetric key cryptography technique. Since, physical layer security is used for privacy preserving location authentication in addition to the conventional cryptographic methods, the proposed method provides significant improvement in the security. The performance of the proposed method has been analysed in terms of information leakage to adversary, bit error rate performance, and transaction time in comparison with existing method which uses cryptography and provides only device authentication for mobile payment. The proposed technique gives better performance than existing technique in terms of privacy and authentication for mobile payment.

Microstructures and Mechanical Properties of Dissimilar Metal Gas Tungsten Arc Welds of 15CDV6 Steel and AISI 304 Stainless Steel

Abstract: The pressure pipeline applications demand high strength steels and stainless steels based on the requirement of strength and corrosion point of view, respectively Welding is one of the widely practiced metal joining techniques in such kind of applications due to the high-pressure environment The present work is primarily aimed at understanding the feasibility and producing X-ray radiography quality gas tungsten arc welds of dissimilar steels, particularly, 15CDV6 steel and AISI 304 stainless steel The sound dissimilar GTA welds are subjected to evaluation of microstructures, mechanical properties such as microhardness across the weldment and tensile properties The mechanical properties are further correlated to microstructures of dissimilar weld joints The filler wire material has profound influence on the microstructures and mechanical properties (both tensile strength and hardness) of dissimilar steel weld joints The dissimilar weld made with 8CD12 filler wire demonstrated higher tensile strength and joint efficiency as compared to the dissimilar weld made with ER 308L filler wire

Effect of Intake Geometry on Longitudinal Aerodynamics of Airbreathing Vehicles

Abstract: A wind-tunnel test program was conducted to generate a systematic aerodynamic database for airbreathing vehicles. Generic models consisting of tangent ogival nose, cylindrical body with cruciform intakes or twin intakes were tested at freestream Mach numbers ranging from 0.5 to 3.0. The length and span of intakes were varied. The intakes were two-dimensional with blocked entry. Normal force and pitching moment were nondimensionalized using planform area and distance of centroid (from nose tip) of the planform of the model rather than body cross-sectional area and body diameter, which are traditionally used. When normal-force and pitching-moment coefficients nondimensionalized this way are plotted against angle of incidence, the coefficients of different configurations coalesce for zero roll. In addition, data for different roll angles are found to coalesce when an empirical function of roll angle is introduced in the nondimensionalizing. A prediction method was developed to estimate the normal force and pitching moment of similar body-intake configurations based on this trend. Nomenclature A = cross-sectional area A B = body cross-sectional area of the configuration, = πr 2 A P = planform area of configuration APB = planform area of body API = planform area of intakes alone, A P − APB A R = reference area (equal to A P unless otherwise specified) Cdn = crossflow drag coefficient of circular cylindrical section Cm = pitching-moment coefficient about nose, M p/ qA R X CmNL = nonlinear component of pitching-moment coefficient about nose C N = normal-force coefficient, = N/ qA R C N NL = nonlinear component of normal-force coefficient cn = local normal-force coefficient per unit length d = body diameter H = height of air intake l = length of model li = length of air intake M = freestream Mach number M p = pitching moment about nose N = normal force q = freestream dynamic pressure r = body radius s = total span of body-intake configuration W = width of air intake

Computer Recognition Method as Applied to Codification Process for Inventory System of a Large Multidisciplined Laboratory

Abstract: A variety of algorithms are existing to retrieve the information by means of furnished keys'. As suggested by Nakatsu N. et al . algorithm for the LCS problem can be used to find string which contain some given words or words similar to them. Some such LCS algorithms with their time responses are discussed 2-6 This paper also describes an effective method of recognizing the information. The method involves two way search giving the weightages to each. Finally the two values are combined to produce a match factor for recognition of information. Its application to codification in inventory system is discussed.