No abstract

In this study, the authors investigate the problem of source localisation based on the time difference of arrival (TDOA) in a group of sensors. Aiming to minimise the squared range-difference errors, the problem leads to a quadratically constrained quadratic programme. It is well known that this approach results in a non-convex optimisation problem. By proposing a relaxation technique, they show that the optimisation problem would be transformed to a convex one which can be solved by semi-definite programming (SDP) and Lagrange multiplier methods. Moreover, these methods offer the exact solution of the original problem and the affirmation of its uniqueness. In contrast to other complicated state-of-the-art SDP algorithms presented in the TDOA localisation literature, the authors methods are derived in a few straightforward reformulations and insightful steps; thus, there are no confusing and unjustifiable changes in the main optimisation problem. Furthermore, complexity analysis and a new approach for performance analysis, which show the merit of their methods, are introduced. Simulations and numerical results demonstrate that the positioning estimators resulted from the proposed algorithms outperform existing SDP-based methods presented so far.

A new level converter for use in dual voltage SOI digital circuits is presented. This technique uses the idea of keeper transistors, and consumes less power compared to the traditional methods. The effects of load capacitance on the circuit are studied by extensive simulations.

In this paper, we report the use of the Genetic Algorithm (GA) to determine the optimum size of the leakage control transistor for low power applications. In the optimization, the energy-delay product is minimized. The transistor is modeled by a neural network to increase the speed and the accuracy of the calculations.

Abstract-This paper deals with the possibilities of cancellation of unwanted signals by steering nulls of the pattern in the direction of arrival of signal while keeping the main beam to the desired direction. New iterative adaptive digital beam forming technique is presented here to enhance the conventional effectiveness of beam forming in common commercial application. Simulation and measurement results confirm that this algorithm can achieve effective Co-Channel Interference (CCI) suppression, while increasing the strength of the desired signal.