A tree structure algorithm using one-dimensional (1-D) multiple signal classification (MUSIC) algorithm is proposed to estimate the two-dimensional direction of arrivals (2-D DOAs) of coherent signals impinging on a uniform rectangular array. The basic idea of the proposed algorithm is to successively apply several times of the 1-D spatial smoothing MUSIC algorithm, in tree structure, to estimate the azimuth and the elevation angles independently. To optimally separate the receive signal, constrained spatial beamformers with adjustable null width are exploited in conjunction with the 1-D spatial smoothing MUSIC algorithm to decompose the received signal into several signals each lead by its own 2-D DOA. Performance analysis is provided to investigate the estimation bias caused by the residue signal propagating in the tree structure.Index Terms-Direction of arrival (DOA) estimation, rectangular antenna array, spatial smoothing.

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This research proposes a power loss analysis and a control strategy of an active cell balancing system based on a bidirectional flyback converter. The system aims to achieve an energy storage application with cells connected in 6 series and 1 parrarel (6S1P) design. To reduce the structural complexity, Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) array commonly used in balancing system is replaced with the photovoltaic Metal-Oxide-Semiconductor (photoMOS) array. Power loss analysis is utilized for the system operating in the proper current to reach higher efficiency. The proposed loss models are divided into conduction loss, switching loss, and copper and core loss of the transformer. Besides, the models are used to estimate the loss of converter operating in different balance conditions to evaluate the system efficiency and verified by the implemented balancing circuit. By way of the loss models, the balancing current can be determined to reach higher efficiency of the proposed system. For further improvement of the balancing process, the system has also applied a control strategy to enhance the balancing performance that reduces 50% maximum voltage difference than traditional cell-to-pack architecture, and 47% balancing duration than traditional pack-to-cell architecture.

The authors deal with the design problem of low-delay perfect-reconstruction filter banks for which the FIR analysis and synthesis filters have equiripple magnitude response. Based on the minimax error criterion, the design problem is formulated in such a manner that the coefficients for the FIR analysis filters can be found by minimising the weighted peak error of the designed analysis filters, subject to the perfectreconstruction constraints. A design technique based on a modified dual-affine scaling variant of Karmarkar's algorithm, in conjunction with approximation schemes, is then developed for solving the resulting nonlinear optimisation problem. The effectiveness of the proposed design technique is demonstrated by several simulation examples. 2 Low-delay perfect-reconstruction FIR filter banks 15

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