In this paper, we improve upon the automatic building extraction method, which uses a variational inference Gaussian mixture model for performing color clustering, by accelerating its computational speed. The improved method decreases the computational time using an image with reduced resolution upon applying color clustering. According to our experiment, in which we used 106 scenery images, the improved method could extract buildings at a rate 86.54% faster than that of the conventional methods. Furthermore, the improved method significantly increased the extraction accuracy by 1.8% or more by preventing over-clustering using the reduced image, which also had a reduced number of the colors.

In this paper, the problem of lifetime extension of wireless sensor networks (WSNs) with redundant sensor nodes deployed in 3D vegetation-covered fields is modeled, which includes building communication models, network model and energy model. Generally, such a problem cannot be solved by a conventional method directly. Here we propose an Artificial Bee Colony (ABC) based optimal grouping algorithm (ABC-OG) to solve it. The main contribution of the algorithm is to find the optimal number of feasible subsets (FSs) of WSN and assign them to work in rotation. It is verified that reasonably grouping sensors into FSs can average the network energy consumption and prolong the lifetime of the network. In order to further verify the effectiveness of ABC-OG, two other algorithms are included for comparison. The experimental results show that the proposed ABC-OG algorithm provides better optimization performance.

We propose a method of crosstalk analysis for two bent transmission lines with vias at both ends on a PCB using a circuit-concept approach in the quasi-static condition. In this condition, the electromagnetic fields can be approximately estimated by the quasi-static terms of the accurate Green's function in an inhomogeneous medium. Thus we obtain a circuit model in an ABCD matrix by taking account of the fields generated by a longitudinal line and a vertical via on a PCB. To verify the proposed approach, we conducted some experiments and compared our approach's results with measured results and a commercial electromagnetic solver's results.

The crosstalk phenomenon, wich occurs between transmission lines, is caused by electromagnetic fields of currents flowing through the lines. Crosstalk between two bent lines is studied by using a set of solutions of modified telegrapher's equations. By expressing electromagnetic fields in terms of voltages and currents in the line ends, the resultant network function in the form of an ABCD matrix is obtained. Electromagnetic fields caused by currents flowing in risers at transmission line ends are taken into account in addition to those fields in line sections. The validity of the proposed approach was confirmed by comparing experimental results with computed results and those simulated by a commercial electromagnetic solver for some bent-line models.

In this paper, the absorbing property of the discrete Green's function ABC, which was based on a powerful concept of the TLM method, has been improved by relocating loss process from the time domain to the space domain. The proposed scheme simply adds a loss matrix to the connection matrix in the basic TLM algorithm to make the formulation of the ABC more efficient. Various lengths of absorbing layers discretized for a WR-90 empty waveguide have been tested in terms of reflection property. An expression for an optimum absorbing property has been also derived with respect to the length of the layer. Comparison of the layer with the discrete Green's function ABC shows that the layer in this study has improved reflection property better than approximately 3 and 6 dB, respectively, when 50Δ and 60Δ absorbing layers have been adopted for the WR-90 waveguide. Finally, the layer has been applied to a WR-75 metal insert filter as an example.

This paper is concerned with a point-oriented finite volume time domain (FVTD) method in the Cartesian coordinate system for analyzing electromagnetic wave scattering by arbitrary shaped metallic gratings. The perfectly matched layer (PML) is used for the absorbing boundary conditions (ABC's) in the directions corresponding to transmitted and reflected wave regions. An FVTD version of the Floquet's theorm is described to impose the periodic condition in the direction where conducting rods are located periodically. The boundary conditions for a conductor rod which is not well suited to the Cartesian coordinate system are satisfied in an average fashion by introducing image fields at image points. It is shown that the present method gives accurate numerical results. Numerical calculations are also carried out for thick conducting rods which seem difficult to deal with in an analytical way.

This paper is concerned with a point-oriented finite volume time domain (FVTD) method in the Cartesian coordinate system and its application to the analysis of electro-magnetic wave propagation in a bended waveguide as well as radiation from and receiving by a horn antenna with a flange of arbitrary angle. The perfectly matched layer (PML) is used for the absorbing boundary conditions (ABC's). The boundary conditions for a perfect conductor not well suited to the Cartesian coordinate system are also proposed. According to this algorithm, the boundary conditions are satisfied in an average fashion at the conductor surface without changing the computational scheme. In this sense, numerical computations based on the present method are simple but flexible. Numerical results show good convergence.

Structure and resistivity of BaBiOy were compared with those of Ba1-xLaxBiO3. Decrease in an average Bi valence from 3.91 to 3.03 for BaBiOy leads to an increase in the lattice parameter c from 4.37 to 4.53 , in the unit cell volume from 81 3 to 87 3, and in the resistivity from 10 Ωcm to 2105 Ωcm. It was found that the increase in the unit cell volume and the resistivity was due to change in the average Bi valence. The resistivity of BaBi1-xLaxO3 was compared with that of BaBiOy and Ba1-xLaxBiO3. We also found that pseudocubic Ba1-xLaxBiO3 remains semiconducting as well as pseudotetragonal BaBiOy. The high resistivity in the Ba1-xLaxBiO3 and the BaBi1-xLaxO3 will be useful to the application for the SIS junction.