The current paper presents an effective deblocking algorithm for block-based coded images using singularity detection in a wavelet transform. Blocking artifacts appear periodically at block boundaries in block-based coded images. The local maxima of a wavelet transform modulus detect all singularities, including blocking artifacts, from multiscale edges. Accordingly, the current study discriminates between a blocking artifact and an edge by estimating the Lipschitz regularity of the local maxima and removing the wavelet transform modulus of a blocking artifact that has a negative Lipschitz regularity exponent. Experimental results showed that the performance of the proposed algorithm was objectively and subjectively superior.

Carrier frequency and symbol timing errors may greatly degrade the performance of the orthogonal frequency division mulitplexing (OFDM) system, especially in multipath environment. In this paper, we explore the cyclostationarity of OFDM signals, which only relies on second order statistics, to estimate the synchronization offset. First, a coarse carrier frequency offset estimator for multipath environment is developed using the second order statistics of the received OFDM signal. It has a wide capture range though not accurate. Second, we introduce a new synchronization algorithm based on cyclostationarity and matched filter theories, which can get the maximal estimation SNR in multipath environment. Both estimators utilize channel state information to achieve better estimation performance and are non-pilot aided. They can be combined to form a whole OFDM synchronizer for multipath environment. Finally, simulations confirm the performance of the estimation algorithm.

This paper presents the design consideration of a polarization-transformation transmission filter, which is composed of a multilayered chiral slab. The optimal material parameters and thickness of each layer of the slab can be determined by using a genetic algorithm (GA). Substituting the constitutive relations for a chiral medium into Maxwell's equations, the electromagnetic field in the medium is obtained. A chain-matrix formulation is used to derive the relationship between the components of the incident, the reflected, and the transmitted electric fields. The cross- and co-polarized powers carried by the transmitted and reflected waves are represented in terms of their electric field components. The procedure proposed for the design of a polarization-transformation filter is divided into two stages. An ordinary filter without polarization-transformation and a polarization-transformation filter for the transmitted wave are designed with a multilayered non-chiral slab and a multilayered chiral slab at the first and the second stages, respectively. According to the specifications of the filters, two functionals are defined with the transmitted and reflected powers. Thus the optimal design of a polarization-transformation filter with the multilayered chiral slab is reduced to an optimization problem where the material parameters and thickness of each chiral layer are found by maximizing the functionals. Applying the GA to the maximization of the functionals, one can obtain the optimal material parameters and thicknesses of the multilayered chiral slab. Numerical results are presented to confirm the effectiveness of the two-stage design procedure. For three types of multilayered chiral slabs, optimal values of refractive indices, thicknesses, and chiral admittances are obtained. It is seen from the numerical results that the proposed procedure is very effective in the optimal design of polarization-transformation filters for the transmitted wave.

A problem of estimating biopotential sources in the brain based on EEG signals observed on the scalp is known as an important inverse problem of electrophysiology. Usually there is no closed-form solution for this problem and it requires iterative techniques such as the Levenberg-Marquardt algorithm. Considering the nonlinear properties of inverse problem, and signal to noise ratio inherent in EEG signals, a back propagation neural network has been recently proposed as a solution. In this paper, we investigated the properties of neural networks and its localization accuracy for single dipole source localization. Based on the results of extensive studies, we concluded the neural networks are highly feasible in single-source localization with a small number of electrodes (18 electrodes), also examined the usefulness of this method for clinical application with a case of epilepsy.

In this paper, we propose a blind adaptive channel identification and equalization algorithm with phase offset compensation for single-input multiple-output (SIMO) channel. It is based on the one-step forward multichannel linear prediction error method and can be implemented by an RLS algorithm. Phase offset problem is inherent part of any second-order statistics-based blind identification and equalization. To solve this problem, we use a blind adaptive algorithm called the constant modulus derotator (CMD) algorithm based on constant modulus algorithm (CMA). Moreover, unlike many known subspace (SS) methods or cross relation (CR) methods, our proposed algorithms do not require channel order estimation. Therefore, our algorithms are robust to channel order mismatch.

We propose a new input arbitration method for an input buffered switch with a buffered crossbar. In the proposed method, each input module selects the first eligible queue from the starting point. The starting points of input modules are different from each other in any case. We show that the uniqueness of the starting points improves the switch performance. Finally, using computer simulations, we confirm the proposed method is better than the conventional method under the uniform and on-off traffic.

Recently, we have discovered wave propagation phenomena which are continuously existing waves of changing phase states between two adjacent oscillators from in-phase to anti-phase or from anti-phase to in-phase in van der Pol oscillators coupled by inductors as a ladder. We named the phenomena as "phase-inversion waves." In this study, phase-inversion waves which exist in the state of in-and-anti-phase synchronization have been found. We observe the phenomena by circuit experiments and computer calculations, and investigate them.

A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. (1) The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on local information in each mobile device. (2) The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the network, which satisfy the above requirements.

The present paper introduces a new approach to the construction of a class of ternary sequences having a zero-correlation zone. The cross-correlation function of each pair of the proposed sequences is zero for phase shifts within the zero-correlation zone, and the auto-correlation function of each proposed sequence is zero for phase shifts within the zero-correlation zone, except for zero-shift. The proposed sequence set has a zero-correlation zone for periodic, aperiodic, and odd correlation functions. As such, the proposed sequence can be used as a finite-length sequence with a zero-correlation zone. A set of the proposed sequences can be constructed for any set of Hadamard sequences of length n. The constructed sequence set consists of 2n ternary sequences, and the length of each sequence is (n+1)2m+2 for a non-negative integer m. The periodic correlation function, the aperiodic correlation function, and the odd correlation function of the proposed sequences have a zero-correlation zone from -(2m+1-1) to (2m+1-1). The member size of the proposed sequence set is of the theoretical upper bound of the member size of a sequence having a zero-correlation zone. The ratio of the number of non-zero elements to the the sequence length of the proposed sequence is also .

Evaluating the generalization performance of learning machines without using additional test samples is one of the most important issues in the machine learning community. The subspace information criterion (SIC) is one of the methods for this purpose, which is shown to be an unbiased estimator of the generalization error with finite samples. Although the mean of SIC agrees with the true generalization error even in small sample cases, the scatter of SIC can be large under some severe conditions. In this paper, we therefore investigate the causes of degrading the precision of SIC, and discuss how its precision could be improved.

This paper considers a wireless coherent system that enables high-speed-data transmission in the presence of carrier phase error over an additive white Gaussian noise (AWGN) channel. Carrier phase noise is caused by imperfect carrier tracking of the coherent demodulation. The channel characteristics of the system were modeled using phase noise whose stochastic process followed the Tikhonov distribution. For this model, we first propose an optimum detector that produces the most suitable decoding metric for a soft-input/soft-output (SISO) decoder, and then develop some simpler forms of the optimum detector to obtain efficient implementation at close to optimal performance. Those simple detectors that have a wide range of performance/complexity tradeoffs are promising in various applications. To evaluate the effectiveness of the proposed detectors, we have applied them to a bandwidth-efficient turbo-coded modulation scheme in which a component decoder based on SISO principles necessitates more exact channel measurement than is possible with a conventional decoder based on Viterbi decoding. Simulation results have demonstrated that the optimum detector enables excellent bit error rate (BER) performance that exceeds that with a normal detector designed for AWGN channels by more than 1 dB at a BER of 10-6 under a severe phase noise environment.

The complexities of many previous scheduling algorithms for IRIS tasks are too high to apply them to practical systems handling many tasks. The high complexities stem from the fact that the algorithms perform scheduling on all tasks in a system, producing an optimal solution. As a way to reduce the complexity of scheduling, we propose a heuristic on-line scheduling algorithm that schedules the IRIS tasks only in a scheduling window, producing a sub-optimal solution. A scheduling window contains W important tasks determined by a selection policy. The performance of the proposed algorithm is verified by simulation.

This paper proposes an automated 3D visualization method of embedded tubes applicable to the scanned result of pulse-radar Non-Destructive Testing (NDT). The proposed method consists of three stages. First, our method defines the processing region which includes a pattern generated by a tube. This region is determined by referring to the composition of a received wave. Second, after expert knowledge of a tube is translated into fuzzy inference rules, the positions of embedded tubes are identified by inferring them. Third, 3D links of the identified positions are formed to visualize the continuous shape of the tubes. Consequently, the tubes are extracted, and their 3D shapes are visualized. The experimental result on the specimens shows that our method was able to find all tubes that exist in the radiograph and the schematic. Our method could thus provide the internal information of concrete with sufficient accuracy required in the practical construction work.

This Letter presents a fast codeword search algorithm based on ordered Hadamard transform. Before encoding, the ordered Hadamard transform is performed offline on all codewords. During the encoding process, the ordered Hadamard transform is first performed on the input vector, and then a new inequality based on characteristic values of transformed vectors is used to reject the unlikely transformed codewords. Experimental results show that the algorithm outperforms many newly presented algorithms in the case of high dimensionality, especially for high-detail images.

A decentralized estimation system usually contains a number of remotely located local sensors that can pre-process observed signal and convey the processed data to a fusion center that makes a final estimation. The local sensors are linked to the data fusion center by transmission channels. When the observation (or estimate of parameter) is quantized at the peripheral sensors and an assumption of conditionally independent sensor data is made, due to potential communication constraints on the channels, the problem of quantization design and bandwidth allocation among the channels linking local sensors to the fusion center is studied in this letter.

In the problem of determining the major frequency components of a signal disturbed by noise, a model selection criterion has been proposed. In this paper, the criterion has been extended to cover a penalized cost function that yields a componentwise shrinkage estimator, and it exhibited a consistent model selection when the proposed criterion was used. Then, a simple numerical simulation was conducted, and it was found that the proposed criterion with an empirically estimated componentwise shrinkage estimator outperforms the original criterion.

The authors propose a circular polarization generator using a square waveguide with L-type probe located on a side wall of waveguide. The sides of the L-probe forming the right angle are placed perpendicular to the direction of propagation. The position of the right angle is kept at a distance of a quarter-wave length from the side wall. The device provides 27% bandwidth for 3 dB axial ratio at 8.4 GHz on azimuth interval of 160.

In this paper, we describe our study on a novel high-frequency magnetic field probe based both on the BiRIG rotation magnetization (RM) phenomenon and the third-generation optical probing scheme. First, we explain our experimental investigation on RF sensitivity and frequency response of the RM-based Faraday effect in a commercially available Bi-substituted rare-earth iron garnet plate. Second, we report on the implementation of fiber-optic magneto-optic (MO) probe heads with bandwidths of 10 GHz or broader, which have been brought about by careful arrangement of the magnetization axis of a single-domain crystal and the highly sensitive fiber-edge optical probing scheme. Third, we describe a few RF magnetic field distribution measurements carried out successfully over GHz-band microstrip line circuits. The results of the study imply the substantial potential of the present MO probe head for the RF current visualization.

This paper presents a novel mm-wave and THz device concept, with a detailed physical modeling and quantitative performance evaluation, called as CW HTS (high temperature superconductive) photomixer/antenna. Optical heterodyne photomixing in the DC-biased HTS strip has been employed to create mm-wave and THz signal, and the size of strip on the grounded dielectric substrate is designed to have an efficient broadside radiation. Incorporating the HTS microstrip configuration as both photomixing media and radiation element at the same time not only increases the CW photocurrent but also the radiation power, while it reduces the radiation loss associated with the patch antenna. Two possible configurations called as longitudinal and transversal will be introduced and their photomixing efficiency and output radiation power will be compared. The detailed analysis along with the optimum design of the geometrical parameters of the microstrip structure shows that the transversal scheme exhibits higher radiation power. The typical nW output power can be obtained by mW laser pump power for frequencies up to the gap frequency of the HTS material. The output power of the proposed device is theoretically higher than the experimentally available data from a Low-Temperature-Grown (LTG) GaAs photomixer integrated with dipole or bow-tie antenna reported in the literature.

Many fuzzy traffic controllers adjust the extension time of the green phase with the fuzzy input variables, arrival and queue. However, in our experiments, we found that the two input variables are not sufficient for an intersection where traffic flow rates change and thus, in this paper, traffic volume is used as an additional variable. Traffic volume is defined as the number of vehicles entering an intersection every second. In designing a fuzzy traffic controller, an ad-hoc approach is usually used to find membership functions and fuzzy control rules showing good performance. That is, initial ones are generated by human operators and modified many times based on the results of simulation. To partially overcome the limitations of the ad-hoc approach, we use genetic algorithms to automatically determine the membership functions for terms of each fuzzy variable when fuzzy control rules are given by hand. The experimental results indicate that a fuzzy logic controller with volume variable outperforms conventional ones with no volume variable in terms of the average delay and the average velocity. Also, the controller shows better performance when membership functions generated by a genetic algorithms instead of ones generated by hand are used.