This paper deals with the decomposition of surface data into several fractal signal based on the parameter estimation by the Mean Likelihood and Importance Sampling (IS) based on the Monte Carlo simulations. The method is applied to the feature extraction of surface data. Assuming the stochastic models for generating the surface, the likelihood function is defined by using wavelet coefficients and the parameter are estimated based on the mean likelihood by using the IS. The approximation of the wavelet coefficients is used for estimation as well as the statistics defined for the variances of wavelet coefficients, and the likelihood function is modified by the approximation. After completing the decomposition of underlying surface data into several fractal surface, the prediction method for the fractal signal is employed based on the scale expansion based on the self-similarity of fractal geometry. After discussing the effect of additive noise, the method is applied to the feature extraction of real distribution of surface data such as the cloud and earthquakes.

The authors realize a 50% length reduction of short-slot couplers in a post-wall dielectric substrate by two techniques. One is to introduce hollow rectangular holes near the side walls of the coupled region. The difference of phase constant between the TE10 and TE20 propagating modes increases and the required length to realize a desired dividing ratio is reduced. Another is to remove two reflection-suppressing posts in the coupled region. The length of the coupled region is determined to cancel the reflections at both ends of the coupled region. The total length of a 4-way Butler matrix can be reduced to 48% in comparison with the conventional one and the couplers still maintain good dividing characteristics; the dividing ratio of the hybrid is less than 0.1 dB and the isolations of the couplers are more than 20 dB.

Our goal in this paper is to provide a complete detection analysis for the OS processor along with OSGO and OSSO modified versions, for M postdetection integrated pulses when the operating environment is nonideal. Analytical results of performance are presented in both multiple-target situations and in regions of clutter power transitions. The primary and the secondary interfering targets are assumed to be fluctuating in accordance with the Swerling II target fluctuation model. As the number of noncoherently integrated pulses increases, lower threshold values and consequently better detection performances are obtained in both homogeneous and multiple target background models. However, the false alarm rate performance of OSSO-CFAR scheme at clutter edges is worsen with increasing the postdetection integrated pulses. As predicted, the OSGO-CFAR detector accommodates the presence of spurious targets in the reference window, given that their number is within its allowable range in each local window, and controls the rate of false alarm when the contents of the reference cells have clutter boundaries. The OSSO-CFAR scheme is useful in the situation where there is a cluster of radar targets amongst the estimation cells.

Polling I/O mechanisms on the Unix platform such as select() and poll() cause high processing overhead when they are used in a heavily-loaded network server with many concurrent open sockets. Large waste of processing power incurs not only service degradation but also various troubles such as high electronic power consumption and worsened MTBF of server hosts. It is thus a serious issue especially in large-scale service providers such as an Internet data center (iDC) where a great number of heavily-loaded network servers are operated. As a solution of this problem, we propose a technique of fine-grained control on the invocation intervals of the polling I/O function. The uniqueness of this study is the utilization of POSIX real-time scheduling to enable the fine-grained execution control. Although earlier solutions such as an explicit event delivery mechanism also addressed the problem, they require major modification in the OS kernel and transition from the traditional polling I/O model to the new explicit event-notification model. On the other hand, our technique can be implemented with low cost because it just inserts a few small blocks of codes into the server program and does not require any modification in the OS kernel.

Due to the continuous growth of wireless communication technology and mobile equipment, the need for storing and processing data of moving objects arises in a wide range of location-based applications. In this paper, we propose a new spatio-temporal index structure for moving objects, namely the TPKDB-tree, which supports efficient retrieval of future positions and reduces the update cost.

In order to miniaturize a very low-level dc current amplifier and to speed up its output response speed, we proposed to employ the switched-capacitor circuit (SCC) as its negative feedback circuit, instead of the conventionally used high-ohmage resistor. However, in the case of using SCC, the output waveform had unnecessary components. To decrease the effect of these components and to speed up the response speed, we used a switched-capacitor filter (SCF), an offset controller, and a positive feedback circuit. As a result, we demonstrated that it was useful to use the amplifier using the SCC.

For the purpose of analyzing noise characteristics of a very low-level dc current amplifier using a high-ohmage resistor negative feedback circuit, we made some noise sources in the form of the electronic circuit simulation program PSpice with the C language program and simulated transient analyses of the very low-level dc current amplifier using the PSpice. As a result, it was observed that in terms of rise time and increases in the amplitudes of the noise voltage with or without positive feedback circuit, the behavior of output waveform of the simulated equivalent circuit was similar to that of the experimental circuit.

This paper provides an overview of research in channel modeling for multiple-input multiple-output (MIMO) data transmission focusing on a radio wave propagation. A MIMO channel is expressed as an equivalent circuit with a limited number of eigenpaths according to the singular-value decomposition (SVD). Each eigenpath amplitude depends on the propagation structure not only of the path direction profiles for both transmission and reception points but also of intermediate regions. Inherent in adaptive control is the problem of instability as a hidden difficulty. In this paper these issues are addressed and research topics on MIMO from a radio wave propagation viewpoint are identified.

We show that the necessary and sufficient condition for the existence of a balanced C4-bowtie decomposition of the complete multi-graph λKn is λ(n - 1) 0 (mod 16) and n 7. Decomposition algorithms are also given.

In this letter, a new blind anti-jammer pre-processor is proposed for GPS receivers to alleviate performance degradation due to strong jammers. Since strong jammers have been successfully removed before despreading, the proposed scheme can effectively extract the signals-of-interest, leading to significant performance enhancement as compared with conventional methods.

We proposed a novel structure that improved the linear characteristics of electroabsorption modulator (EAM) with composite quantum-wells as an absorption core layer. We fabricated three types of EAM's whose active cores were 8 nm thick, 12 nm thick and a composite core with 8 nm thick and 12 nm thick quantum-well (QW), respectively. The transfer functions of EAM's were investigated and their third-order inter-modulation distortion (IMD3) was obtained by calculation. The spurious free dynamic range (SFDR) was measured and compared with three types of QW. The linearity of the device with composite quantum-well showed a large enhancement in SFDR by 9.3 dBHz2/3 in TE mode and 7.0 dBHz2/3 in TM mode compared with the conventional EAM.

Nowadays more people have started using their mobile phone to access information they need from anywhere at anytime. In advanced mobile technology, Location Service allows users to quickly pinpoint their location as well as makes a recommendation to fascinating events. However, users desire more appropriate recommendation services. In other words, the message service should push a message at a proper place in time. In consequence, customers obtain a higher level of satisfaction. In this paper, we propose a framework of time, place, purpose and personal profile based recommendation service. We illustrate scenarios in "push", "pull" and "don't disturb" services, where our DB queries can recommend the relevant message to users. The three factors: time, place and purpose are mutually dependent and the basic rules to analyze the essential data are summarized. We also create algorithms for DB query. We are filtering messages by one important factor: personal profile such as user's preference and degree of preference. Furthermore, we discuss an implementation of the prototype system, including results of experimental evaluation.

This paper reports on the suitability of the SUSAN filter for the removal of artifacts that result from quantization errors in wavelet video coding. In this paper two extensions of the original filter are described. The first uses a combination of 2-D spatial filtering followed by 1-D temporal filtering along motion trajectories, while the second extension is a pure 3-D motion compensated SUSAN filter. The SUSAN approach effectively reduces coding artifacts, while preserving the original signal structure, by relying on a simple pixel-difference-based classification procedure. Results reported in the paper clearly indicate that both extensions efficiently reduce ringing that is the prevalent artifact perceived in wavelet-based coded video. Experimental results indicate an increase in perceptual as well as objective (PSNR) decoded video quality, which is competitive with state-of-the-art post-processing algorithms, especially when low computational demands of the proposed approach are taken into account.

A post-wall waveguide slot array with a three-way power divider on a single-layer substrate is designed to have a H-plane sectoral beam and an E-plane cosecant pattern with null-filling. Experiments in the 26 GHz band confirmed the sectoral beam with a -3 dB beam width of 117 deg and a ripple width of 2 dB in the sector.

A new hybrid method for characterizing the irregular power/ground plane pair is developed in this paper by combining the conventional eigen-mode expansion method with the new-presented inverted composition method and a simple model order reduction. By the approach, the eigen-mode expansion method can be extended to the characteristics research of the power/ground plane pair with holes. In this gridless method, ports and decoupling capacitors can be arbitrarily placed on the plane pair. The numerical example demonstrates its good validity.

The linear operation of a HBT with a GaAs/InGaP composite collector structure is demonstrated. The composite collector structure allows for a thin collector design that is suitable for the linear operation of a HBT without critical degradation of the breakdown voltage. The load pull measurements under a 1.95 GHz WCDMA signal have shown that a composite-collector HBT with a 400-nm thick collector layer operates with power-added-efficiency (PAE) as high as 53% at VCE = 3.5 V as a result of improved distortion characteristics. Despite the thin collector design, collector-emitter breakdown voltage of 11 V was achieved even at current density of 10 kA/cm2. The composite-collector HBT has even greater advantage for future low voltage (< 3 V) applications where maintaining PAE and linearity becomes one of the critical issues.

This paper presents a novel algorithm for spectral subtraction (SS). The method is derived from a relation between the spectrum obtained by the discrete Fourier transform (DFT) and that by a subspace decomposition method. By using the relation, it is shown that a noise reduction algorithm based on subspace decomposition is led to an SS method in which noise components in an observed signal are eliminated by subtracting variance of noise process in the frequency domain. Moreover, it is shown that the method can significantly reduce computational complexity in comparison with the method based on the standard subspace decomposition. In a similar manner to the conventional SS methods, our method also exploits the variance of noise process estimated from a preceding segment where speech is absent, whereas the noise is present. In order to more reliably detect such non-speech segments, a novel robust voice activity detector (VAD) is then proposed. The VAD utilizes the spread of eigenvalues of an autocorrelation matrix corresponding to the observed signal. Simulation results show that the proposed method yields an improved enhancement quality in comparison with the conventional SS based schemes.

This paper describes a polarimetric feature extraction method from urban areas using the POLSAR (Polarimetric Synthetic Aperture Radar) data. The scattering characteristic of urban areas is different from that of natural distributed areas. The main point of difference is polarimetric correlation coefficient, because urban areas do not satisfy property of azimuth symmetry, Shh = Shv = 0. The decomposition technique based on azimuth symmetry can not be applied to urban areas. We propose a new model fit suitable for urban areas. The proposed model fit consists of odd-bounce, even-bounce and cross scattering models. These scattering models can represent the polarimetric backscatter from urban areas, and satisfy Shh 0 and Shv 0. In addition, the combination with the proposed model fit and the three component scattering model suited for natural distributed areas is examined. It is possible to apply the combined technique to POLSAR data which includes both urban areas and natural distributed areas. The combined technique is used for feature extraction of actual X-band POLSAR data acquired by Pi-SAR. It is shown that the proposed model fit is useful to extract polarimetric features from urban areas.

We propose an aperture coupling E-bend with step structure as a robust post-wall waveguide interface to an external standard waveguide in which the posts are separated from the aperture. A 61.25 GHz model transformer gives 11.4% bandwidth for the reflection below -25 dB by using a 1.2 mm-height dielectric substrate. We have compared the mechanical tolerances of both the conventional straight structure and the proposed step structure. The step structure is more robust against mechanical errors than the conventional one. Another advantage is that the accuracy of the analysis model for the post-wall to metal-wall replacement is enhanced for the step structure.

This paper proposes a channel allocation principle that prevents TCP throughput degradation in multihop transmissions in a mesh network based on the carrier sense multiple access with collision avoidance (CSMA/CA) MAC protocol. We first address the relationship between the network topology of wireless nodes and the TCP throughput degradation based on computer simulations. The channel allocation principle is discussed in terms of resolution into a coloring problem based on throughput degradation. The number of required channels for the proposed channel allocation principle is evaluated and it is shown that two channels are sufficient for more than 96% simulated multihop patterns. The proposed channel allocation principle is extendable to generic mesh networks. We also clarify the number of required channels for mesh networks. The simulation results show that three channels are sufficient for more than 98% patterns in the generic mesh networks when the number of nodes is less than 10.