This paper presents a new data hiding scheme under fractal image generation via Fourier filtering method for Computer Graphics (CG) applications. The data hiding operations are achieved in the frequency domain and a method similar to QAM used in digital communication is introduced for efficient embedding in order to explore both phase and amplitude components simultaneously. Consequently, this scheme enables us not only to generate a natural terrain surface without loss of fractalness analogous to the conventional scheme, but also to embed larger amounts of data into an image depending on the fractal dimension. This scheme ensures the correct decoding of the embedded data under lossy data compression such as JPEG by controlling the quantization exponent used in the embedding process.

In this paper we propose a subsequence matching algorithm that supports moving average transform of arbitrary order in time-series databases. Moving average transform reduces the effect of noise and has been used in many areas such as econometrics since it is useful in finding the overall trends. The proposed algorithm extends the existing subsequence matching algorithm proposed by Faloutsos et al. (SUB94 in short). If we applied the algorithm without any extension, we would have to generate an index for each moving average order and would have serious storage and CPU time overhead. In this paper we tackle the problem using the notion of index interpolation. Index interpolation is defined as a searching method that uses one or more indexes generated for a few selected cases and performs searching for all the cases satisfying some criteria. The proposed algorithm, which is based on index interpolation, can use only one index for a pre-selected moving average order k and performs subsequence matching for arbitrary order m ( k). We prove that the proposed algorithm causes no false dismissal. The proposed algorithm can also use more than one index to improve search performance. The algorithm works better with smaller selectivities. For selectivities less than 10-2, the degradation of search performance compared with the fully-indexed case--which is equivalent to SUB94--is no more than 33.0% when one index is used, and 17.2% when two indexes are used. Since the queries with smaller selectivities are much more frequent in general database applications, the proposed algorithm is suitable for practical situations.

This report describes an acceleration technique to synthesize time-domain macromodels of interconnects using FDTD method. In FDTD calculation, the characteristic impedance of the interconnect is inserted into every terminal in order to damp quickly the transient waveforms. Additionally, an efficient technique for analyzing the macromodels is proposed. We demonstrate the efficiency of this method with examples.

Within the next few decades, high-end telecommunication systems on the larger nationwide network will require a switching capacity of over 5 Tbps. Advanced optical transmission technologies, such as wavelength division multiplexing (WDM) will support optical-fiber data transmission at such speeds. However, semiconductors may not be capable of high-throughput data switching because of the limitations by power consumption and operating speed, and pin count. Superconducting single flux quantum (SFQ) technology is a promising approach for overcoming these problems. This paper proposed an optical-electrical-SFQ hybrid switching system and a novel switch architecture. This architecture uses time-shifted internal speedup, shuffle and grouping exchange and a Batcher-Banyan switch. Our proposed switch consists of an interface circuit with small buffers, a Batcher sorter, a time-shift-speedup buffer (TSSB), a Banyan switch, and a slowdown buffer. Simulations showed good scalability up to 100 Tbps, which no router could ever offer such features.

This paper is, in half part, written in review nature, and presents recent theoretical results on linear-filtering and -prediction problems of nonstationary Gaussian processes. First, the basic concepts, signal and noise, are mathematically characterized, and information sources are defined by linear stochastic differential equations. Then, it is shown that the solution to a conventional problem of filtering or prediction of a nonstationary time series is, in principle, reducible to a problem, of which solution is given by Kalman-Bucy's theory, if one can solve a problem of finding the canonical representation of a Gaussian process such that it has the same covariance functions as those of the time series under consideration. However, the problem mentioned above is left open. Further, the problem of time-frequency analysis is discussed, and physical realizability of the evolutionary, i.e., the online, spectral analyzer is shown. Methods for dealing with differential operators are presented and their basic properties are clarified. Finally, some of related open problems are proposed.

System capacity of a system consisting of N classes of users is characterized by N-vectors representing the number of users that can be accommodated under a specified BER (bit error rate) constraint in each class. In this paper, system capacity of the reverse link of a wireless multimedia CDMA system with processing gain control is analyzed in the asymptotic regime, when the processing gain G, for receivers with and without CCI cancellers. A new scheme for processing gain control with an optimized power allocation is proposed and its system capacity is compared with the conventional processing gain control scheme as well as the previously discussed power control scheme. It is shown that the proposed scheme has a certain advantage over other schemes.

This paper proposes a statistical method to estimate the optimal software release time which minimizes the expected total software cost incurred in both testing and operation phases. It is shown that the underlying cost minimization problem can be reduced to a graphical one. This implies that the software release problem under consideration is essentially equivalent to a time series forecasting for the software fault-occurrence time data. In order to predict the future fault-occurrence time, we apply three extraordinary auto-regressive models by Singpurwalla and Soyer (1985) as the prediction devices as well as the well-known AR and ARIMA models. Numerical examples are devoted to illustrate the predictive performance for the proposed method. We compare it with the classical exponential software reliability growth model based on the non-homogeneous Poisson process, using actual software fault-occurrence time data.

In the beginning of the new century, many information appliance (IA) products will replace traditional electronic appliances to help people in smart, efficient, and low-cost ways. These successful products must be capable of communicating multimedia information, which is embedded into the electronic appliances with high integration, innovation, and power-throughput tradeoff. In this paper, we develop a codesign procedure to analyze, compare, and emulate the multimedia communication applications to find the candidate implementations under different criteria. The experimental results demonstrate that in general, memory technology dominates the optimal tradeoff and ALU improvements impact greatly on particular applications. The results also show that the proposed procedure is effective and quite efficient.

In practice, the DS-CDMA system is equipped with a finite number of Channel Element (CE)s that performs the baseband spread signal processing for a given channel in the base station. In this situation, the call blocking can be caused not only by the insufficient number of channel elements but also by the limit of available traffic channels. In this paper, we focus on analyzing the effect of the limited number of CEs on the Erlang capacity of multimedia DS-CDMA systems in the reverse link when the CDMA cells are sectorized with 3 sectors. For the performance analysis, a multi-dimensional Markov chain model is developed. As a result, the more CE results in the larger Erlang capacity. However, the Erlang capacity is saturated after a certain value of CEs where the call blocking is mainly caused by the insufficient channels per sector.

In this paper we develop a robust control theory to achieve fault-tolerant behaviors of timed discrete event systems (DESs) with model uncertainty represented as a set of some possible models. To demonstrate the effectiveness of the proposed theory, we provide a case study of a resistance spot welding process.

In computer science, concepts of resource such as data consumption and of time such as execution time are very important. Logical systems which can treat them have been applied in that field. Linear logic has been called a resource conscious logic. The expressive power is enough to describe a dynamic change in process environments. However, linear logic is not enough to treat a dynamic change in environments with the passage of time since it does not include a concept of time directly. A typical example is the relation between linear logic and Petri nets. It is well known that the reachability problem for Petri nets is equivalent to the provability for the corresponding sequent of linear logic. But linear logic cannot naturally represent timed Petri nets which are extensions of ordinary Petri nets with respect to time concept. So we extend linear logic with respect to time concept in order to introduce a resource-conscious and time-dependent logical system, that is, temporal linear logic. This system has some temporal operators "" which means a resource usable only once at the next time, "" which means a resource usable only once at anytime, and a modal storage operator "!" which means a resource usable any times at anytime. We can show that the reachability problem for timed Petri nets is equivalent to the provability for the corresponding sequent of temporal linear logic. In this paper, we also represent the description of synchronous communication model by temporal linear logic. The expressive power of temporal linear logic will be applicable to various fields of computer science.

In this paper, a novel chaos circuit with long working-life is proposed. The proposed circuit consists of NMOS-coupled discrete-time chaotic cell circuits. By employing chaos synchronization phenomenon, the proposed circuit can achieve long working-life. Since the proposed circuit is less susceptible to breakdown, the rate of the acceptable product for chaos IC can be improved. Furthermore, thanks to the coupling by using NMOSFET's, the loss of the connection line between chaotic cell circuits can be controlled electronically. Therefore, the proposed system designed by using switched-current (SI) techniques is useful as an experimental tool to analyze chaos synchronization phenomena. The validity of the proposed circuits is confirmed by computer simulations and experiments.

Petri net is a mathematical model for concurrent systems. Petri net is known to have less modeling power than that of Turing machine. Lack of zero testing ability is the main reason of this fact. Indeed, every extended Petri net model that can perform zero testing is equivalent to Turing machine. Time Petri net is one of the models with ability of zero testing. It is of theoretical interest what structure enables zero testing. This paper shows that time asymmetric choice net can simulate register machines. The result implies reachability problem of this subclass of time Petri net is undecidable.

The Real-time VLBI Correlator (RVC) is a new type processor for the Very-Long-Baseline Interferometry (VLBI). This correlator was primarily designed for supporting the VLBI Space Observatory Programme (VSOP). Two particular techniques, the fringe rotator after correlation and the lag-time extension technique, are newly developed for the RVC. The correlation circuit size of VLBI correlator is reduced to half by introducing the new fringe rotator, and it makes possible to realize a large delay window being essential in finding a cross correlation in real-time. The delay window can be changed flexibly with the lag-time extension technique, and its technique is useful to detect the fringe peak in a VSOP observation. The new correlator was installed at the Usuda Deep Space Center in Japan, and is used in VSOP and other domestic VLBI observations. In this paper, the key features of the Real-time VLBI Correlator (RVC) focusing on these advanced techniques are presented, and the results of its performance test are shown.

A distributed system is said to be self-stabilizing if it converges to some legitimate state from an arbitrary state in a finite number of steps. The number of steps required for convergence is usually referred to as the stabilization time, and its reduction is one of the main performance issues in the design of self-stabilizing systems. In this paper, we propose an automated method for computing the stabilization time. The method uses Boolean functions to represent the state space in order to assuage the state explosion problem, and computes the stabilization time by manipulating the Boolean functions. To demonstrate the usefulness of the method, we apply it to the analysis of existing self-stabilizing algorithms. The results show that the method can perform stabilization time analysis very fast, even when an underlying state space is very huge.

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.

The problem of self-timed implementation of Boolean functions is explained. The notions of combinational delay-insensitive code and delay-insensitive function are defined, giving precise conditions under which memoryless self-timed implementation of Boolean functions is feasible. Examples of combinational delay-insensitive code and delay-insensitive function are given. Generic design style, using standard CAD library, for constructing quasi delay-insensitive self-timed function blocks is suggested. Our design style is compared to other self-timed function block design styles.

A new method is introduced for sequential estimation of TDOA (time delay of arrival) and FDOA (frequency delay of arrival) in a two sensor array. The proposed scheme is basically a two step algorithm utilizing 1-dimensional slice functions of the third order cumulants between two signal measurements, and is capable of suppressing the effect of correlated Gaussian measurement noises. It is demonstrated that the proposed algorithm outperforms existing TDOA/FDOA estimation algorithms from the viewpoint of computational burden and in the sense of mean squared error as well.

GSRI Pragmatic TCM, which is a Pragmatic Trellis Coded Modulation allowing bandwidth expansion, has been proposed. In [1], it is shown that this scheme can achieve higher performance than conventional Pragmatic TCM scheme. On the other hand, a real-time video multimedia communication is one of the possible applications for the third generation mobile communication systems. This video multimedia communication system needs a multiplexer which mixes various types of media such as video, voice and data into a single bitstream. ITU-T has standardized H.223 Annex A, B, C and D multimedia multiplexing protocols for low bit-rate mobile communications. This paper evaluates the performance of the GSRI Pragmatic TCM with an application of a mobile multimedia system using H.223 Annex D multiplexing scheme and MPEG-4 video coding.

This paper describes how to generate, analyze and design a novel current-mode filter model using tunable multiple-output operational transconductance amplifiers and grounded capacitors (MO-OTA-Cs) for synthesizing both transmission poles and zeros. Transfer functions of low-order, high-order, general type, and special type are realized based on the filter model. The theory focuses mainly on establishing a relationship between the cascaded MO-OTA-Cs and the multiple-loop feedback matrix, which makes the structural generation and design formulas. Adopting the theory allows us to systematically generate many interesting new configurations along with some known structures. All the filter architectures contain only grounded capacitors, which can absorb parasitic capacitances and require smaller chip areas than floating ones. The paper also presents numerical design examples and simulation results to confirm the theoretical analysis.