We present two time-domain algorithms derived from the popular Newmark's time integration algorithm, to reconstruct the input force excitation from the vibration measurements. While the first method uses a direct ...
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We present two time-domain algorithms derived from the popular Newmark's time integration algorithm, to reconstruct the input force excitation from the vibration measurements. While the first method uses a direct formulation of the time integration algorithm, the second one uses a regularization tool to solve the associated inverse problem. A modified regularization technique is employed to improve the accuracy of the identification problem. Numerical studies with limited measurements, with measurement noise, multiple load identification etc., are presented to investigate the practical applicability of the two methods. Studies have clearly favored the inverse algorithm with modified regularization technique. Finally modeling errors associated with force reconstruction are investigated and a technique is proposed to identify the system parameters simultaneously while reconstructing the input dynamic force, using a recently developed quantum particle swarm optimization algorithm developed by the authors. The numerical simulation studies presented clearly indicate that the force, as well as the system parameters, can be identified accurately using the proposed algorithm.
A new, reliable and computationally efficient blind method is proposed for joint estimation of channel order and number of active users in a direct sequence code-division multiple-access system with multi-path fading ...
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A new, reliable and computationally efficient blind method is proposed for joint estimation of channel order and number of active users in a direct sequence code-division multiple-access system with multi-path fading channel. The proposed method (i) exploits a parametric model used for equalisation of multi-path channels in finite impulse response multi-input multi-output systems, (ii) first, estimates rank of correlation matrix of observation, by combining the subspace method and information-theoretic criteria, (iii) then, estimates simultaneously channel order and number of active users, by using the estimated rank and the model parameter, without any prior information, (iv) uses only a single antenna, in contrast to the previous methods, while having the ability to jointly estimate higher numbers of active users and channel order in lower signal-to-noise ratios. Numerical results show that the proposed method can estimate higher number of users and also has higher detection probability when using minimum mean square error algorithm.
A simplified frame structure is proposed for fast burst synchronisation in orthogonal frequency division multiplexing systems. A simpler and shorter synchronisation symbol and minimum mean square error algorithm is ex...
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A simplified frame structure is proposed for fast burst synchronisation in orthogonal frequency division multiplexing systems. A simpler and shorter synchronisation symbol and minimum mean square error algorithm is exploited to estimate the frame starting position. The performance of the proposed frame is confirmed by simulation for QPSK systems.
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