Defence Research Agency

About: Defence Research Agency is a based out in . It is known for research contribution in the topics: Synthetic aperture radar & Radar. The organization has 1211 authors who have published 1109 publications receiving 31542 citations.

Large calibre armature firings at Green Farm electric gun test facility

Abstract: The DNA/Maxwell Laboratories SSG 90 mm Rail Gun has been used to fire a number of solid armature projectiles in conjunction with the United Kingdom, (UK) Defence Research Agency, (DRA). These projectiles have been fully tactical, discarding sabots rounds fired at short range into RHA steel targets. This paper gives details of those shots, the diagnostics used to capture the data and some of the design methodology behind the test. Visual recordings have been assisted in the analysis of the results, showing good sabot discard and flight characteristics. Velocities of over 2000 m/s have been achieved with fully discarding tactical packages and typical accelerating lengths. The tests have shown for a limited sample size, that EM projectiles can be launched as accurately as ones from a conventional powder gun, and that the differing launch conditions do not pose a major problem to the shot designers.

Architecture of knowledge fusion within an Integrated Mobile Security Kit

Abstract: A common challenge for applications requiring information and knowledge fusion is the conversion of data streams into knowledge adapted to the context of usage. In the context of the project Integrated Mobile Security Kit, this paper focuses on the knowledge fusion sub-system. It integrates different fusion aspects based on a common domain model and embedded into a distributed and mobile infrastructure. The fusion aspects considered are attribute and situation fusion, situation recognition and event correlation. The main contribution of the paper are (1) the architecture of the knowledge fusion sub-system, (2) the domain model for integrating the fusion aspects and (3) the specification of the inner workings of the three different fusion aspects.

Untruncated satellite perturbations in a nonrotating gravitational field

Abstract: In previous work it was assumed that the gravitational field was axisymmetric and due only to interior mass. By use of a particular coordinate system, an orbital theory was developed that led to compact perturbation formulas associated with the general zonal harmonic //. No eccentricity truncation was involved in these formulas, although there was an implicit restriction to elliptic orbits. The theory has now been given a logical completeness by three distinct extensions: 1) By allowing for tesseral harmonics, Jim, the assumption of axial symmetry can be dropped; 2) by permitting the index / to be negative, exterior mass can be allowed for; and 3) the formulas can be expressed so that hyperbolic orbits are covered. The extensions are straightforward if the field is time invariant (i.e., nonrotating) and this is assumed. The second extension has involved the most new work, since the planetary equations have to be formulated with a different integration variable when / < 0.

Wavelet transforms on vector spaces as a method of multispectral image characterisation

Abstract: A new form of wavelet-based feature extraction has been developed for the multiresolution analysis of multispectral imagery, in which the wavelet components have vector amplitudes which can be used to characterise multispectral phenomena such as colour, in addition to scalar brightness. A vector-based approach enables the detection of unusual events which do not stand out in any of the individual scalar image components, and a new approach to data compression based on background rejection. The wavelet analysis method described in the paper is applicable to any vector field where the base space is Euclidean (typically R/sup 2/), that is a mapping from a Euclidean space to a vector bundle. The latter is a collection of vector spaces (called fibres) of equal dimension, attached to each point in the Euclidean base space, and do not need to be related to the base space. The field vectors lie in the fibre space, not the base space, and so can be abstract and of much higher dimension than the base space. This property is very useful for the analysis of multispectral imagery.< >