This study describes the feasibility of using the penalty-function nonlinear programming neural network method to find the optimal power generating output which minimizes both the costs of generating power and power transmission losses. This method depends on neural network technology in acquiring exterior penalty function. Employing nonlinear function in equality and inequality constraints, the model is established using a neural network and additional objective functions; these additional objective functions expand cost function by using an appropriate penalty function. In this study, a 26-busbar including six generators was used to test the penalty function nonlinear programming neural network method. A comparison with the sequential unconstrained minimization technique (SUMT) demonstrates the reliability and precision of the optimal solution obtained using the new method.

In this paper, we propose a method to introduce an A* search control into sentential matching mechanism for question-answering systems, in order to reduce the response time while the accuracy of the answer is preserved. The question answering is a new technology to retrieve not relevant documents but the answer(s) directly by combining several methodology including IR and IE. One of the essential processes is the sentential matching between the user's query and each sentence in documents. In general, in order to obtain matching score precisely in higher resolution, we need some processes with higher computational costs. We therefore introduce an A* search in which both the processing cost and the resolution of matching score are took into account simultaneously. According to the experiments in NTCIR3 QAC1 Task1, the system with the controlled search is 3.4-8.5 times faster than the system with no control.

The objective of this study was to explore suitable spatial filters for inverse estimation of cortical potentials from the scalp electroencephalogram. The effect of incorporating noise covariance into inverse procedures was examined by computer simulations. The parametric projection filter, which allows inverse estimation with the presence of information on the noise covariance, was applied to an inhomogeneous three-concentric-sphere model under various noise conditions in order to estimate the cortical potentials from the scalp potentials. The present simulation results suggest that incorporation of information on the noise covariance allows better estimation of cortical potentials, than inverse solutions without knowledge about the noise covariance, when the correlation between the signal and noise is low. The method for determining the optimum regularization parameter, which can be applied for parametric inverse techniques, is also discussed.

This letter investigates the peak-to-average power ratio (PAR) reduction scheme employing a simple symbol transform in OFDM-CDMA systems. This approach is very simple because of no additional complexity and works with arbitrary numbers of subcarriers and without restriction on the allocation of spreading code, maintaining an original transmission efficiency. Simulation results show that the investigated scheme gives the PAR reduction gain of 2-3 dB compared to the original OFDM and OFDM-CDMA signals, and can provide the further PAR reduction by combing the partial transmit sequence (PTS) scheme, which is less complex compared to the ordinary PTS approach.

Finding DC operating points of nonlinear circuits is an important and difficult task. The Newton-Raphson method adopted in the SPICE-like simulators often fails to converge to a solution. To overcome this convergence problem, homotopy methods have been studied from various viewpoints. For the global convergence of homotopy methods, it is a necessary condition that a given initial solution is the unique solution to the homotopy equation. According to the conventional criterion, such an initial solution, however, is restricted in some very narrow region. In this paper, considering the circuit interpretation of homotopy equations, we prove theorems on the uniqueness of an initial solution for globally convergent homotopy methods. These theorems give new criteria extending the region wherein any desired initial solution satisfies the uniqueness condition.

Cochannel interference and multipath propagation reduce the performance of mobile communication systems. Multi-input MLSE with whitening processing can mitigate the influence of the interference and provide path diversity gain. In conventional considerations, however, the required complexity rapidly rises with the number of array elements. In this paper, we propose multi-input MLSE that whitens error signals in the signal space by using a multibeam adaptive array. This scheme can reduce the computational load of multi-input MLSE than the conventional type when using a large-element array. The results of an analysis show that the proposed type is equivalent to conventional one in the sense of the metric and provides less computational complexity.

The file sizes of on going flows are fairly disparate on the current network. In this letter, we propose an "age-based" packet discard scheme in the Traffic Conditioner (TC) of a gateway to improve the performance of file transmission. The on going flows will be grouped to three classes of priority according to their "age" as network congestion occurs and the simulation results show that the proposed model can work efficiently in most of the congestion conditions.

We present a design and implementation of a QoS control mechanism in an Adaptive Multimedia Communication System (AMCS) using multiagent-based computing technology. In this paper, we first define functional requirements for AMCS. Subsequently we describe the design and implementation of AMCS with a knowledge-based multiagent framework to fulfill the functional requirements. Moreover we evaluate the adaptability of the prototype systems of AMCS with the operational situations observed in its experiments. From the result of the experiments, we conclude that the multiagent-based design and implementation is reasonable for construction of AMCS.

Integration of the IP/MPLS network and the WDM optical mesh network is a promising approach to realizing an efficient backbone network. Because of the great volumes of traffic carried, the social cost incurred by a failure will be extremely high, so survivability is very important in the backbone network. In survivable IP/MPLS over WDM backbone networks, cooperation of the optical level fault recovery and the IP/MPLS level fault recovery is essential. This paper analyzes cost characteristics of the optical level fault recovery and the IP/MPLS level fault recovery. A mathematical programming method is proposed to minimize the initial network cost when the IP/MPLS level fault recovery is utilized in the survivable IP/MPLS over WDM networks. Using this method, the initial network cost needed for the IP/MPLS level fault recovery is compared with that for the optical level fault recovery. The initial network cost for the LSP (Label Switched Path) protection scheme is smaller than that for the shared light-path protection scheme and larger than that for the pre-plan type light-path restoration scheme. The LSP protection scheme is suitable for the best-effort type traffic while the shared light-path protection scheme may be suitable for the bandwidth guaranteed type traffic.

In this paper, we propose a scalable Extended Differentiated-Services (EDS) architecture to guarantee edge-to-edge explicit rate allocation. In presence of flows with explicit rate allocation, to share bandwidth fairly, a new fairness definition is proposed. Based on EDS and the proposed fairness definition, a scalable fair Edge-to-Edge Congestion Control Algorithm with Explicit Rate Allocation (ECC-ERA) is presented to solve the bandwidth assurance problem facing Differentiated Service architecture, where EDS uses congestion control packets to carry the flow-related states and congestion control information. By designing efficiency control and fairness control separately, the ECC-ERA can achieve good scalability to link capacity, round-trip time and number of flows. It will be shown that EDS plus ECC-ERA outperforms the general Diff-Serv bandwidth guarantee approaches. The main advantages of EDS+ECC-ERA are as follows: (1) it not only can guarantee explicit rate allocation, but also can guarantee near-zero packet loss in core routers, high utilization, lower and smoother queueing delay, better fairness and better protection from unresponsive traffic. (2) Neither resource pre-reservation nor sophisticated scheduling mechanisms are required. The simple FIFO at core routers is enough. (3) EDS plus EC-ERA is very efficient and can be used as end-to-end QoS building block.

In this paper, our aim is to extract real-time movement-related potentials, especially readiness-potentials, from EEGs with a small number of scalp electrodes. We proposed a method composed of independent component analysis (ICA), dipole tracing (DT) and scalp Laplacian methods. The proposed method shows a good real-time RP extraction capability from a single-trial of movement by means of the selection of EEGs with high reliability based on the DT and the improvement of the spatial resolution of the scalp potentials based on the scalp Laplacian.

In this paper, we consider the problem of estimating the time-varying directions-of-arrival (DOAs) of coherent narrowband cyclostationary signals impinging on a uniform linear array (ULA). By exploiting the cyclostationarity of most communication signals, we investigate a new computationally efficient subspace-based direction estimation method without eigendecomposition and spatial smoothing (SS) processes. The proposed method uses the inherently temporal property of incident signals and a subarray scheme to decorrelate the signal coherency and to suppress the noise and interfering signals, while the null subspace is obtained from the resulting cyclic correlation matrix through a linear operation. Then an on-line implementation of this method is presented for tracking the DOAs of slowly moving coherent signals. The proposed algorithm is computationally simple and has a good tracking performance. The effectiveness of the proposed method is verified through numerical examples.

This paper first presents an active integrated antenna configuration designed for broadband mobile wireless access systems using the 25-GHz band. This active integrated antenna comprises a microstrip antenna array and RF front-end circuits adopting spatial power combining schemes for reduced power consumption of the power amplifiers. Furthermore, the antenna and RF circuits are integrated into each side of a thick copper backing plate and both are connected through microstrip line /slot transitions. The developed active integrated antenna achieves the output power of 14.6 dBm and a noise figure of less than 5 dB. The wireless system using the developed active integrated antenna achieves a 6-dB improvement in the packet error rate compared to that using a passive antenna with the same array design as the active integrated antenna. Furthermore, we obtained the first license of the active integrated antenna for commercial use in high-speed wireless communication systems in Japan.

In this paper, we derive spatial correlation functions of linear and circular antenna arrays for three types of angular energy distributions: a Gaussian angle distribution, the angular energy distribution arising from a Gaussian spatial distribution, and uniform angular distribution. The spatial correlation functions are investigated carefully. The spatial correlation is a function of antenna spacing, array geometry and the angular energy distribution. In order to emphasize the research and their applications in diversity reception, as an example, performance of the antenna arrays with MRC in correlated Nakagami fading channels is investigated, in which analytical formulas of average BER for the spatial correlation are obtained.

The system uses spectral shaping of a supercontinuum source followed by wavelength-to-time mapping to generate ultra wideband RF waveforms with arbitrary modulation. It employs an adaptive computer control to mitigate the non-ideal features inherent in the optical source and in the spectrum modulation process. As proof of concept, ultra-wideband frequency hopped CDMA waveforms are demonstrated.

A wide variety of visual textures could be successfully modeled as spatially variant by quantitatively describing them through the variation of their local spatial frequency and/or local orientation components. This class of patterns includes flow-like, granular or oriented textures. Modeling is achieved by assuming that locally, textured images contain a single dominant component describing their local spatial frequency and modulating amplitude or contrast. Spatially variant textures are non-homogeneous in the sense of having nonstationary local spectra, while remaining locally coherent. Segmenting spatially variant textures is the challenging task undertaken in this paper. Usually, the goal of texture segmentation is to split an image into regions with homogeneous textural properties. However, in the case of image regions with spatially variant textures, there is no global homogeneity present and thus segmentation passes through identification of regions with globally nonstationary, but locally coherent, textural content. Local spatial frequency components are accurately estimated using Gabor wavelet outputs along with the absolute magnitude of the convolution of the input image with the first derivatives of the underlying Gabor function. In this paper, a frequency estimation approach is used for segmentation. Indeed, at the boundary between adjacent textures, discontinuities occur in texture local spatial frequency components. These discontinuities are interpreted as corresponding to texture boundaries. Experimental results are in remarkable agreement with human visual perception, and demonstrate the effectiveness of the proposed technique.

The joint histogram of second order scale space differential invariants of natural images (including textures) is typically clustered about parabolic surface patches, whereas symmetrical elliptical patches (local convexities or concavities) are very rare and symmetrical hyperbolical patches also occur less frequently than parabolic patches. We trace the origin of this striking effect in the context of Gaussian random noise. For this case one may derive the joint histogram of curvedness and shape index analytically. The empirical observations are fully corroborated. In deriving these results we introduce a polar coordinate system in the space of second order scale space derivatives that turns out to be particularly useful in the study of the statistics of local curvature properties. The empirical observations apply also to non-Gaussian noise (e.g., Brownian noise) as well as to photographs of natural scenes. We discuss general arguments that help explain these observations.

In 2002, Hwang, Lee, and Lai presented an attack on the untraceability property of Fan and Lei's partially blind signature scheme. In this letter, their attack is demonstrated as being invalid.

The key elements of sub-100 nm MOSFET modeling for circuit simulation are accurate representation of new physical phenomena arising from advancing technologies and numerical efficacy. We summarize the history of MOSFET modeling, and address difficulties faced by conventional methods. The advantage of the surface-potential-based approach will be emphasized. Perspectives for next generations will be also discussed.

A linear-in-dB VGA of the current-divider type is fabricated in 0.25 µm CMOS technology. Two gain compensation techniques are proposed in order to compensate the gain deviations due to a MOSFET which has a square-law characteristic or an exponential-law characteristic determined by its current density. Temperature compensation techniques are also proposed. Measure results obtained at 380 MHz are a gain range of 80 dB, a gain error of 3 dB, and an NF of 11 dB.