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.

Systolic array for recursive least squares by inverse iterations

Abstract: A novel systolic array for implementing recursive least squares based on the method of inverse iterations is described. It is based on Givens rotations and takes the form of a relatively simple orthogonally connected array. Since the inverse iterations method involves a major computational feedback loop, the derivation of a pipelined processor array is highly non-trivial. >

The Avoidance of Collisions for Newtonian Bodies with Hidden Variables

Abstract: : The collision avoidance of a pair of uniformly moving bodies is considered in three dimensions. The relative motion of the bodies yields an expression relating the time to closet approach, the minimum range, the current range and its rate of change, other variables being unobservable. A Boolean relation is then proposed that is satisfied whenever the minimum range and time to closet approach simultaneously fall below given thresholds. The relation is further studied, in particular with regard to the issue of false and premature alarms. An airborne collision avoidance system is a possible application.

A study of the polymerization behaviour of N -(4-phenoxy)-phenylmaleimide using DSC analysis

Abstract: The thermal cure of a monofunctional maleimide N-(4-phenoxy)-phenylmaleimid (1) was examined using differential scanning calorimetry (DSC). The analogous bis-maleimide bis-(4-maleimidophenyl)ether (2) was also analyzed in the same manner for comparison. Polymerization kinetics derived from scanning DSC measurements showed an order of reaction varying between n=1 and 2 for (1), compared to an order of reaction between n=2 and 3 (by multiple linear regression analysis) for (2). The overall enthalpy of polymerization (ΔHo) for N-(4-phenoxy)-phenylmaleimide (94kJ/mole) agrees well with that obtained for maleimide itself (89kJ/mole) using conventional calorimetric techniques indicating that polymerization appears complete within the timescale of the experiment. In contrast the analogous BMI displays a markedly lower overall polymerization enthalpy (ca. 66kJ/mole) indicating an apparent conversion of only 37%.

Accelerated training: the use of faster-than-real-time speeds can reduce the time-to-skill factor in simulator training

Abstract: Reports of training, where a simulator is run above normal speed, suggest potential benefits, but are confounded by the use of mixed training schedules. We report how two groups of participants were trained on a target tracking and acquisition simulator,with simulator speed as the only between-groups variable. Each group had two familiarization, and 20 training runs, where circular targets travelled in sets of two or three across an out-of-focus, digitized, real-world landscape, and could be tracked and acquired in a sequence chosen by each participant. The sole difference between groups was that one were given targets travelling 90 percent faster than normal speeds over the same distance. 24 hours later, each group was tested on sets of four targets travelling at normal speed. Those participants trained in accelerated conditions were significantly faster at acquiring each target than the control group, and equally accurate. The accelerated group came near to peak performance during training, while the control group were still improving throughout the test phase. It is considered that training under accelerated conditions can offer the alternative potential advantages of reaching a specified standard in a shorter training period, or of attaining a higher standard with the same amount of training time.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.