In this paper, we propose a method to minimize multiple-valued decision diagrams (MDDs) for multiple-output functions. We consider the following: (1) a heuristic for encoding the 2-valued inputs; and (2) a heuristic for ordering the multiple-valued input variables based on sampling, where each sample is a group of outputs. We first generate a 4-valued input 2-valued multiple-output function from the given 2-valued input 2-valued functions. Then, we construct an MDD for each sample and find a good variable ordering. Finally, we generate a variable ordering from the orderings of MDDs representing the samples, and minimize the entire MDDs. Experimental results show that the proposed method is much faster, and for many benchmark functions, it produces MDDs with fewer nodes than sifting. Especially, the proposed method generates much smaller MDDs in a short time for benchmark functions when several 2-valued input variables are grouped to form multiple-valued variables.

Recently, two approaches investigated indexing and retrieving videos. One approach utilized the visual features of individual objects, and the other approach exploited the spatio-temporal relationships between multiple objects. In this paper, we integrate both approaches into a new video model, called the Visual-Spatio-Temporal (VST) model to represent videos. The visual features are modeled in a topological approach and integrated with the spatio-temporal relationships. As a result, we defined rich sets of VST relationships which support and simplify the formulation of more semantical queries. An intuitive query interface which allows users to describe VST features of video objects by sketch and feature specification is presented. The conducted experiments prove the effectiveness of modeling and querying videos by the visual features of individual objects and the VST relationships between multiple objects.

In this paper, we propose fast bitmap search algorithms to reduce the computational complexity of transform-based vector quantization (VQ) techniques, which achieve better quality in reconstructed images than the ordinary VQ. By removing the unlikely codewords in each step, the bitmap search method, which starts from the most significant bitmap then the successive significant ones, can save more than 90% computation of the ordinary transformed VQ. By applying to the singular value decomposition (SVD) VQ as an example, theoretical analyses and simulation results show that the proposed bitmap search methods dramatically reduce the computation and achieve invisible distortion in the reconstructed images.

In this paper, we define content-identifier (ContentID) to represent the characteristics of shot. The ContentID carries both positional and temporal color information. Based on the concept of ContentID, we propose a video retrieval method. The method is robust to compression, format conversion, frame dropping and noise such as watermark and so on. Furthermore, based on our retrieval method, we implemented a copyright protection system for digital video using spread-spectrum based watermarking technique.

A workflow is a flow of work carried out in parallel and in series by people. In order to improve efficiency, it is required to change the current workflow dynamically. Since dynamic change of workflows may probably make the series of work inconsistent, it is necessary to find out consistent change of workflow. As consistent ways, three types of dynamic changes: flush, abort, and synthetic cut-over (SCO), have been proposed. However, the concrete analysis and evaluation have not been done. To do the performance evaluation for the dynamic workflow changes, comparison of the times (called change time) cost in the individual change and the methods how to obtain such times become ever important. In this paper, we first give a definition of change time and then propose the computation methods individually for each change type. Finally, we do experiments to evaluate the performance of three changes by doing the comparison of the change times.

In this study, the shielding effect of high-loss dielectric and magnetic materials themselves and also an oval human model placed behind these material, were investigated by the FDTD method, for near- and far-field exposure, using the half-wave length dipole antenna. According to the results, a high-loss magnetic material showed a large shielding effect (average 20 dB) compared to the high-loss dielectric material, for near- and far-field shields. Also, the reduction of the shielding effect was small (2 dB) for the high-loss magnetic material, while it was large for the high loss dielectric material, on decreasing the distance between the antenna and shield. Moreover, the variation of the shielding effect on a human model placed behind the shield was small (0.2-1.5 dB) for the high-loss magnetic material, but large for the high-loss dielectric material. This is similar to the results of the shield materials themselves, for the close antenna-shield and human-shield distances, respectively.

A new timing estimation algorithm for asynchronous DS/CDMA multiuser communication system is proposed in this paper. The algorithm is based on the Minimum Variance Distortionless Response (MVDR) beamforming technique that minimizes the beamformer's output power with the constraint that only the signal with exact timing is distortionlessly passed. Exploiting the characteristics that the MVDR beamformer's output power is severely degraded according to erroneous timing estimation, we develop an efficient algorithm to estimate each user's timing by scanning the beamformer's output power variation. Compared to the maximum a posteriori (MAP) or maximum likelihood (ML) based multiuser timing estimator, the complexity is extensively reduced by separating the multi-dimensional optimization problem into several one-dimensional optimization problems. Furthermore, the algorithm is computationally feasible than the subspace-based timing estimator since no eigendecomposition (EVD) is required. Moreover, the proposed algorithm is near-far resistant since the MVDR beamformer is inherently energy independent to the interferers.

Most distributed systems are based on either the C/S (Client/Server) model or the P-to-P (Peer to Peer) model. In C/S based distributed systems, a client invokes a server and waits for the server reply. Because of this sequential nature, C/S based distributed systems can be implemented by the RPC (Remote Procedure Call) scheme. Most tools for developing distributed objects are based on the RPC scheme. Whereas, in P-to-P based distributed systems, each distributed objects work concurrently, by exchanging asynchronous messages, without waiting for the receiver's action. To implement these P-to-P distributed systems, the RPC scheme is not powerful enough, and the active object model using asynchronous messages is suitable. This paper explains the pure Java library CAPE for developing P-to-P based distributed active object systems.

If the direction of arrival (DOA) of a source is perturbed due to some reasons in a statistical way as in the environment of wireless mobile communications, a new model appropriate for such environment should be used instead of the point source model. In this paper, an angle-perturbed source model is proposed and an estimation method based on the eigen-decomposition technique is investigated under the model. The asymptotic distribution of the estimation errors is obtained to see the statistical properties.

This paper proposes the binary second-order recurrent neural networks (BSRNN) equivalent to the modified finite automata (MFA) and presents the learning algorithm to construct the stable BSRNN for inferring regular grammar. This network combines two trends; one is to transform strings of a regular grammar into a recurrent neural network through training with no restriction of the number of neurons, the number of strings, and the length of string and the other is to directly transform itself into a finite automaton. Since neurons in the BSRNN employ a hard-limiter activation functions, the proposed BSRNN can become a good alternative of hardware implementation for regular grammars and finite automata as well as grammatical inference.

This paper proposes an on-chip memory-path architecture employing the dynamically variable line-size (D-VLS) cache for high performance and low energy consumption. The D-VLS cache exploits the high on-chip memory bandwidth attainable on merged DRAM/logic LSIs by replacing a whole large cache line in one cycle. At the same time, it attempts to avoid frequent evictions by decreasing the cache-line size when programs have poor spatial locality. Activating only on-chip DRAM subarrays corresponding to a replaced cache-line size produces a significant energy reduction. In our simulation, it is observed that our proposed on-chip memory-path architecture, which employs a direct-mapped D-VLS cache, improves the ED (Energy Delay) product by more than 75% over a conventional memory-path model.

As a preprocessor of the automatic speech recognizer in a noisy environment, a microphone array system has been investigated to reduce the environmental noise. In usual microphone array design, a plane wave is assumed for the sake of simplicity (far-field assumption). However, this far-field assumption does not always hold, resulting in distortion in the array output. In this report, the subspace method, which is one of the high resolution spectrum estimator, is applied to the near-field source localization problem. A high resolution method is necessary especially for the near-field source localization with a small-sized array. By combining the source localization technique with a spatial inverse filter, the signal coming from the multiple sources in the near-field range can be separated. The modified minimum variance beamformer is used to design the spatial inverse filter. As a result of the experiment in a real environment with two sound sources in the near-field range, 60-70% of word recognition rate was achieved.

An iterative decoder of turbo code over an inter-symbol interference channel is proposed. A component decoder realizes decoding and equalization simultaneously with the soft-output Viterbi algorithm (SOVA). A decoding algorithm and simulation results are shown.

We are interesting in the error exponent for source coding with fidelity criterion. For each fixed distortion level Δ, the maximum attainable error exponent at rate R, as a function of R, is called the reliability function. The minimum rate achieving the given error exponent is called the minimum achievable rate. For memoryless sources with finite alphabet, Marton (1974) gave an expression of the reliability function. The aim of the paper is to derive formulas for the reliability function and the minimum achievable rate for memoryless Gaussian sources.

With a view to virtual studio applications, we design an optimal grid pattern such that the observed image of a small portion of it can be matched to its corresponding position in the pattern easily. The grid shape is so determined that the cross ratio of adjacent intervals is different everywhere. The cross ratios are generated by an optimal Markov process that maximizes the accuracy of matching. We test our camera calibration system using the resulting grid pattern in a realistic setting and show that the performance is greatly improved by applying techniques derived from the designed properties of the pattern.

The transmission S-parameter between two dipole-elements is a measure to evaluate sites for measuring complex antenna factors (CAF). In this paper, the S-parameter between two dipole-elements on a ground plane is measured using a network analyzer with its TRL (Thru-Reflect-Line) calibration. The S-parameter is also calculated by the method of moment (MoM) and compared to the measurement results. The comparison shows that the calculated S-parameter is usable as a reference value in the evaluation of CAF measurement sites. As an example of the evaluation and selection of measurement sites, the transmission S-parameter on a finite ground plane is calculated using the hybrid method combined the geometrical theory of diffraction (GTD) and MoM. As a result, a preferable antenna setting on the finite ground plane is recommended.

In this paper we study general complex eigenvalue problems in engineering fields. The eigenvalue problems can be transformed into the associated problems for solving large systems of nonlinear ordinary differential equations (dynamic equations) by optimization techniques. The known waveform relaxation method in circuit simulation can then be successfully applied to compute the resulting dynamic equations. The approach reported here, which is implemented on a message passing multi-processor system, can determine all eigenvalues and their eigenvectors for general complex matrices without any restriction on the matrices. The numerical results are provided to confirm the theoretical analysis.

In this paper, we propose a call arrival history-based location tracking strategy for a variable call arrival rate over time. The basis of the proposed strategy is a time-based location tracking strategy. A mobile terminal obtains the up-to-date information about changes in the call arrival rate by maintaining its call arrival history, from which it can calculate an appropriate timeout interval for a variable call arrival rate. We present a simple analytical model and numerical results to investigate its performance for both a fixed and a variable call arrival rate which is modeled by a Markov-modulated Poisson process.

In this paper, we propose an adaptive IIR equalizer based on prefiltering techniques. The proposed equalizer has a cascade structure of an ARMA prefilter and an adaptive FIR equalizer. The ARMA prefilter is designed based on the transfer function estimated by the gradient-type instrumental variable algorithm. Simulation results are shown to confirm the performance of the proposed adaptive IIR equalizer.

A WDM (Wavelength Division Multiplexing) technology is a new optical technology, providing multiple wavelengths at the rate of 10 Gbps on the fiber. IP (Internet Protocol) over WDM networks where IP packets are directly carried on the WDM network is expected to offer an infrastructure for the next generation Internet. For IP over WDM networks, a WDM protection mechanism is expected to provide a highly reliable network (i.e., robustness against the link/node failures). However, conventional IP also provides a reliability mechanism by its routing function. In this paper, we first formulate an optimization problem for designing IP over WDM networks with protection functionalities of WDM networks, by which we can obtain IP over WDM networks with high reliability. Our formulation results in a mixed integer linear problem (MILP). However, it is known that MILP can be solved only for a small number of variables, in our case, nodes and/or wavelengths. We therefore propose two heuristic algorithms, min-hop-first and largest-traffic-first approaches in order to assign the wavelength for backup lightpath. Our results show that the min-hop-first approach takes fewer wavelengths to construct the reliable network, that is, all of lightpaths can be protected using the WDM protection mechanism. However, our largest-traffic-first approach is also a good choice in the sense that the approach can be saved the traffic volume increased at the IP router by the link failure.