There are more and more information services provided on the wireless networks. Due to long network delay of wireless links, transactions will be long-lived transactions. In such a situation, the occurrence of handoff is inevitable, and thus a wireless link held by a mobile unit crossing cell boundaries might be forced to terminate. It is undesirable that an active transaction is forced to terminate. A queueing scheme has been proposed to solve the problem of forced termination of transactions in our previous research. However, when 2PL protocol is employed, suspending an active transaction will elongate the lock holding time and thus degrade the system performance. In this paper, we propose two guard channel schemes (GCS), static and dynamic, to reduce the probability of forced termination of transactions. In dynamic GCS, the number of channels reserved in a base station is dynamically assigned according to the number of transaction calls which may handoff to this cell while the number of guard channels is fixed in static GCS. An analytic model based on Markov chain is derived to evaluate the system performance. The correctness of this model is verified by simulation. The experimental results show that a significant improvement is achieved by using the dynamic GCS.

In this paper, we propose a realtime concatenation technique between basic skeletal motions obtained by the motion capture technique and etc. to generate a lifelike behavior for a humanoid character (avatar). We execute several experiments to show the advantage and the property of our technique and also report the results. Finally, we describe our applied system called WonderSpace which leads participants to the exciting and attractive virtual worlds with humanoid characters in cyberspace. Our concatenation technique has the following features: (1) based on a blending method between a preceding motion and a succeeding motion by a transition function, (2) realizing "smooth transition," "monotone transition," and "equivalent transition" by the transition function called paste function, (3) generating a connecting interval by making the backward and forward predictions for the preceding and succeeding motions, (4) executing the prediction under the hypothesis of "the smooth stopping state" or "the state of connecting motion", (5) controlling the prediction intervals by the parameter indicating the importance of the motion, and (6) realizing realtime calculation.

A new approach for bandwidth allocation of heterogeneous regulated traffics is proposed for cases of lossless multiplexing and statistical multiplexing under the constraint of maximum delay. Minimum bandwidth required for lossless multiplexing can be expressed as 1-dimensional unconstrained-optimization problem. The corresponding optimality condition gives an optimal bandwidth and buffer requirements. This optimality condition is extended to the case of statistical multiplexing. In case of statistical multiplexing with independent, periodic on-off fluid sources, two random variables representing stochastic worst cases for the amount of traffics generated in an arbitrary time interval are introduced and these are combined optimally. This combined model guarantees the worst case bound for the regulated traffics. Using the proposed approach, bandwidth and buffer requirements of each virtual circuit are obtained simultaneously. As these values are sensitive to multiplexing environments, an effective bandwidth considering trade-off between bandwidth and buffer requirements is introduced. The proposed effective bandwidth can be matched directly with the boundary of the acceptance region, which is less sensitive to mutiplexing environments.

In this paper we have presented a new method for seismic signal analysis, based on the ARMA modeling and a fuzzy LVQ clustering method. The objective achieved in this work is to sense the changes made naturally or artificially on the seismogram signal, and to detect the sources, which caused these changes (seismic classification). During the study, we have also found out that the model is sometimes capable to alarm the further seismic events just a little time before the onset of those events (seismic prediction). So the application of the proposed method both in seismic classification and seismic prediction are studied through the experimental results. The study is based on the background noise of the teleseismic short period recordings. The ARMA model coefficients are derived for the consecutive overlapped windows. A base model is then generated by clustering the calculated model parameters, using the fuzzy LVQ method proposed by Nassery & Faez in [19]. The time windows, which do not take part in [19] model generation process, are named as the test windows. The model coefficients of the test windows are then compared to the base model coefficients through some pre-defined composition rules. The result of this comparison is a normalized value generated as a measure of similarity. The set of the consecutive similarity measures generate above, produce a curve versus the time windows indices called as the characteristic curves. The numerical results have shown that the characteristic curves often contain much vital seismological information and can be used for source classification and prediction purposes.

To extract extrinsic resistances, conventional cold-FET methods require additional DC measurements or channel technological parameters. Additionally, the methods need at least two sets of cold-FET S-parameters measured at different cold-FET bias conditions in order to completely determine gate and drain pad capacitance as well as extrinsic gate, source and drain inductance and their resistances. One set of S-parameters handles the extraction of extrinsic inductances, and the other set extracts the gate and drain pad capacitance. To be free from additional DC measurement or channel technological parameters and reduce the number of sets of cold-FET S-parameters, we propose a cold-FET method that can extract all the extrinsic elements including the gate and drain capacitance, using only one set of cold-FET S-parameters. The method has shown excellent agreement between modeled and measured S-parameters up to 62 GHz at 56 different normal operating bias points.

The maximum likelihood estimate of a mixture model is usually found by using the EM algorithm. However, the EM algorithm suffers from a local optima problem and therefore we cannot obtain the potential performance of mixture models in practice. In the case of mixture models, local maxima often have too many components of a mixture model in one part of the space and too few in another, widely separated part of the space. To escape from such configurations we proposed a new variant of the EM algorithm in which simultaneous split and merge operations are repeatedly performed by using a new criterion for efficiently selecting the split and merge candidates. We apply the proposed algorithm to the training of Gaussian mixtures and the dimensionality reduction based on a mixture of factor analyzers using synthetic and real data and show that the proposed algorithm can markedly improve the ML estimates.

In designing a field-programmable gate array (FPGA)-based processor for motion stereo, a parallel memory system and a simple interconnection network for parallel data transfer are essential for parallel image processing. This paper, firstly, presents an FPGA-oriented hierarchical memory system. To reduce the bandwidth requirement between an on-chip memory in an FPGA and external memories, we propose an efficient scheduling: Once pixels are transferred to the on-chip memory, operations associated with the data are consecutively performed. Secondly, a rectangular memory allocation is proposed which allocates pixels to be accessed in parallel onto different memory modules of the on-chip memory. Consequently, completely parallel access can be achieved. The memory allocation also minimizes the required capacity of the on-chip memory and thus is suitable for FPGA-based implementation. Finally, a functional unit allocation is proposed to minimize the complexity between memory modules and functional units. An experimental result shows that the performance of the processor becomes 96 times higher than that of a 400 MHz Pentium II.

The mean reflection and transmission coefficients of electromagnetic waves incident onto a two-dimensional slightly random dielectric surface are investigated by means of the stochastic functional approach. We discuss the shift of Brewster's scattering angle using the Wiener kernels and numerical calculations. It is also shown that the phase shift at the reflection into Brewster's angle for a flat surface does not depend on the rms height of the surface, but does on the correlation length of the surface.

To make clear numerically the scattering characteristics for a body embedded in a random medium, we need to analyze the bistatic cross-section (BCS). The scattering problem can be analyzed as a boundary value problem by using current generator method. The fourth moment of Green's functions in the random medium, which is necessary for the analysis, is obtained approximately by two-scale method. We analyze numerically the BCS of conducting circular cylinders in continuous random media, which are assumed to fluctuate about the dielectric constant of free space. The numerical results agree well with the law of energy conservation. The effects of random media on the BCS are also clarified numerically.

We call a network an anonymous network, if each vertex of the network is given no ID's. For distributed algorithms for anonymous networks, solvable problems depend strongly on the given initial conditions. In the past, initial conditions have been investigated, for example, by computation given the number of vertices as the initial condition, and in terms of what initial condition is needed to elect a leader. In this paper, we study the relations among initial conditions. To achieve this task, we define the relation between initial conditions A and B (denoted by A B) as the relation that some distributed algorithm can compute B on any network satisfying A. Then we show the following property of this relation among initial conditions. The relation is a partial order with respect to equivalence classes. Moreover, over initial conditions, it induces a lattice which has maxima and minima, and contains an infinite number of elements. On the other hand, we give new initial conditions k-LEADER and k-COLOR. k-LEADER denotes the initial condition that gives special condition only to k vertices. k-COLOR denotes the initial condition that divides the vertices into k groups. Then we investigate the property of the relation among these initial conditions.

A two-dimensional algorithm, which combines the well-known Synthetic Aperture Radar (SAR) imaging and the recently developed effective inversion method, is presented and applied to a three-dimensional configuration. During the first stage a two-dimensional image of a realistic three-dimensional buried object is obtained. In the second stage the average permittivity of the object is estimated using a two-dimensional effective inversion scheme where the geometrical information retrieved from the SAR image is employed. The algorithm is applicable in real time.

Binary Decision Diagrams (BDDs) are graph representation of Boolean functions. In particular, Ordered BDDs (OBDDs) are useful in many situations, because they provide canonical representation and they are manipulated efficiently. BDD packages which automatically generate OBDDs have been developed, and they are now widely used in logic design area, including formal verification and logic synthesis. Synthesis of pass-transistor circuits is one of successful applications of such BDD packages. Pass-transistor circuits are generated from BDDs by mapping each node to a selector which consists of two or four pass transistors. If circuits are generated from smaller BDDs, generated circuits have smaller number of transistors and hence save chip area and power consumption. In this paper, more generic BDDs which have no restrictions in variable ordering and variable appearance count on its paths are called Generic BDDs (GBDDs), and an algorithm for generating GBDDs is proposed for the purpose of synthesis of pass-transistor circuits. The proposed algorithm consists of two steps. At the first step, parse trees (PTs) for given Boolean formulas are generated, where a PT is a directed tree representation of Boolean formula(s) and it consists of literal nodes and operation nodes. In this step, our algorithm attempts to reduce the number of literal nodes of PTs. At the second step, a GBDD is generated for the PTs using Concatenation Method, where Concatenation Method generates a GBDD by connecting GBDDs vertically. In this step, our algorithm attempts to share isomorphic subgraphs. In experiments on ISCAS'89 and MCNC benchmark circuits, our program successfully generated 32 GBDDs out of 680 single-output functions and 4 GBDDs out of 49 multi-output functions whose sizes are smaller than OBDDs. GBDD size is reduced by 23.1% in the best case compared with OBDD.

We discuss human collaborative discovery processes using a production system model as a cognitive simulator. We have developed an interactive production system architecture to construct the simulator. Two production systems interactively find targets in which the only experimental results are shared; each does not know the hypothesis the other system has. Through this kind of interaction, we verify whether or not the performance of two systems interactively finding targets exceeds that of two systems independently finding targets. If we confirm the superiority of collaborative discovery, we approve of emergence by the interaction. The results are: (1) generally speaking collaboration does not produces the emergence defined above, and (2) as the different degree of hypothesis testing strategies that the two system use gets larger, the benefits of interaction gradually increases.

This letter points out some flaws in the previous works on UKS (unknown key-share) attacks. We show that Blake-Wilson and Menezes' revised STS-MAC (Station-to-Station Message Authentication Code) protocol, which was proposed to prevent UKS attack, is still vulnerable to a new UKS attack. Also, Hirose and Yoshida's key agreement protocol presented at PKC'98 is shown to be insecure against public key substitution UKS attacks. Finally, we discuss countermeasures for such UKS attacks.

Debye's asymptotic series is frequently used for calculation of cylindrical functions. However, it seems that until now this series has not been used in all-purpose programs for numerical calculation of the cylindrical functions. The authors attempt to develop these all-purpose programs. We present some improvements for the numerical calculation. As the results, Debye's series can be used for the all-purpose programs, and it is found out that the series gives sufficient accuracy if some conditions are satisfied.

This paper deals with a quantitative inversion algorithm for reconstructing the permittivity and conductivity profiles of bounded inhomogeneous buried objects from measured multifrequency and multiincidence backscattered field data. An Edge-Preserving regularization scheme is applied leading to a significant enhancement in the profiles reconstructions. The applications concern civil engineering and geophysics as well as mine detection and localization. The performance of the reconstructions are illustrated with different synthetic data.

CAM (Content Addressable Memory) units are generally designed so that they can be applied to variety of application programs. However, if a particular application runs on CAM units, some functions in CAM units may be often used and other functions may never be used. We consider that appropriate design for CAM units is required depending on the requirements for a given application program. This paper proposes a CAM processor synthesis system based on behavioral descriptions. The input of the system is an application program written in C including CAM functions, and its output is hardware descriptions of a synthesized processor and a binary code executed on it. Since the system determines functions in CAM units and synthesizes a CAM processor depending on the requirements of an application program, we expect that a synthesized CAM processor can execute the application program with small processor area and delay. Experimental results demonstrate its efficiency and effectiveness.

In this paper we propose SAS-Coin, a very practical micro payment scheme based on a hash chain and a simple one time password authentication protocol called SAS. While it has many desirable features of a coin (anonymity etc.), it has no public key operations at any stage and has very little overheads. Moreover authentication is also available and a session key could be generated for encrypted information supply without any additional cost at all. Since there are no public key operations this is extremely useful for mobile telephone applications. This has sufficient security even for larger payments. Comparative analysis with some of the already proposed systems is also done.

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.

In the future Internet, hierarchically classified Quality of Service (QOS) controls will be effective because various connections requiring different QOS are mixed. However, even in such an environment, among the same class connections, performance protection to harmful impact from the other connections and quality differentiation between connections will be required furthermore. In this paper, from this point of view, we focus on the active connections succession time (age of active connections) as a new dimensional criterion for buffer controls. To be concrete, the packet discarding control of congested router's buffer based on active connections is proposed. Moreover, its performance is evaluated through TCP/IP level simulation from the viewpoint of file transfer time. Conventional Internet can be regarded as the environment where only one class traffic exists (unit class environment). The proposed control scheme can provide powerful differentiation capability to avoid the performance disruption of total connections even in the conventional Internet.