Abstract-In this paper, a novel source localization scheme is proposed based on the unitary ESPRIT algorithm with back ray tracing technique and the city electronic maps. Our scheme can be summarized into two steps. First, the unitary ESPRIT algorithm is employed to estimate the angles and delays of the arrival rays radiated from the source. Second, based on the obtained information we devise a back ray tracing technique to recover the signal propagation paths according to the Geometrical Theory of Reflections and the city electronic map. After these two steps the source position can be obtained by averaging all the estimated positions. In order to minimize estimated errors caused by the Unitary ESPRIT, a valid-range selection criterion for the judgment of the validity of the estimated position data is proposed. On the other hand, we introduce a path length weighting factor to reduce the estimated errors caused by the terrain data inaccuracy. This position method can locate both the line of sight (LOS) and non-line of sight (NLOS) sources efficiently and it also can locate multi-sources simultaneously. Six simulations are carried out in three terrain scenarios. The numerical results demonstrate that our model can be applied to estimate the positions for both 2D and 3D cases. The accuracy of our model for a cell of 80 m × 45 m can reach 10 m when SNR is greater than 10 dB.

In this paper, a simple, efficient and environmental friendly method was proposed to fabricate TiO2/CdS nanotube arrays. The composite nanotubes with a core-shell coaxial structure were fabricated via a simple method of liquid deposition and double diffusion using anodic aluminum oxide (AAO) templates. The photocatalytic properties of the nanotube arrays (TiO2, TiO2/CdS) were confirmed by the degradation of methyl orange (MO) under UV irradiation. Compared to bare TiO2 nanotube arrays, TiO2/CdS composite nanotube arrays showed improved photocatalytic performance: The degradation efficiency of TiO2/CdS and TiO2 nanotube arrays towards methyl orange was 65% and 39%, respectively.

We develop a novel three-dimensional (3D) numerical model for rigorously simulating mutual coupling effects on the channel capacity of the multiple input multiple output (MIMO) systems. In this model, the efficient integral equation method mutlilevel Green's function interpolation method (MLGFIM) is for the first time employed to calculate the input admittances and radiation patterns of the transmit and receive antennas of MIMOs. Comparing with the Method of Moments whose complexity is ( 2 ), MLGFIM has an efficiency of ( log ) and is suitable for efficiently solving antenna arrays problems. To accurately model the EM wave propagation, we 1) use the ray tracing method to obtain the multi-paths and 2) rigorously obtain the dyadic path loss factor model from which a novel stochastic path loss model that is flexible for both the environments with PEC walls and that with infinite thick lossless dielectric walls is devised. Using the proposed model, we successfully analyze mutual coupling effects on the 3D correlation of a 2-by-2 monopole array and the indoor channel capacity of a 20-by-20 planar array and a 20-by-20 icosahedron array. The numerical examples in this paper demonstrate the efficiency of our model for simulating the MIMO system with complex radiators.Index Terms-Integral equation method, multilevel Green's function interpolation method (MLGFIM), multiple input multiple output (MIMO), mutual coupling.

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