We apply a novel methodology, based on statecharts, to the design of large scale asynchronous systems. The design is specified at multiple levels, simulated, animated, and compiled into synthesizable VHDL code by using the ExpressV-HDL CAD tool. We add a validation sub-system to chech correct operation. ExpressV-HDL is originally synchronous, but we employ it for asynchronous design by avoiding any design dependence on the clock, and simulating with fast clock and on-line delays. The tool is demonstrated through a simple FSM. The synthesized synchronous circuit can be converted into an asynchronous one. Some results of a post-synthesis conversion example are given.

Significant traffic variations occur in telecommunication networks. This paper focuses on hour-to-hour traffic variations during 24 hours and investigates the possibility of using idle periods effectively by introducing non-realtime service at a discount rate. In order to provide non-realtime service, memory is placed at each telecom center. When immediate service is not available, messages of non-realtime calls are stored in the memory and served later when network resources are available. Realtime calls are served with preference. A basic model and a method of dimensioning the memory capacity are presented. The basic model is extended to the network model, and methods of designing a minimum cost network and pricing and profit issues are presented. The results for a basic model are verified by traffic simulation. Numerical examples are given to show the effectiveness of non-realtime service.

The present paper describes a novel approach to interconnecting and assembling components of MEMS at room temperature. The main drawback of the conventional bonding methods is their rather high process temperatures. The new method, which is referred as the surface activated bonding (SAB), utilizes the phenomena of the adhesion between two atomically clean solid surfaces to enable the bonding at lower temperature or even at room temperature. In the bonding procedure, the surfaces to be bonded are merely brought into contact after sputter-cleaning by Ar fast atom in ultrahigh vacuum conditions. TEM observations of the bonded interfaces show that a direct bonding in atomic scale is achieved in the interface between the micro-components. Based on the concept of this new bonding technology, a micro-assembly system was developed. The micro-assembly system is operated by means of a virtual manipulation system in which 3D model of the micro-components are manipulated virtually in a computer graphics constructed in the world wide web (WWW) scheme. The micro-assembly system will provide a new design tool of three dimensional MEMS by combining the possibility of the flexible assembly and the intuitive operations.

In this paper, we analyze the multiple access interference of a variable processing gain DS/CDMA system and define discrete partial crosscorrelation functions. We also evaluate the bit error rate of the system using Gaussian approximation and bounding technique. Three kinds of spreading codes (long, short, and random codes) are considered in the analysis of the system. It is shown that the bit error rate of a user is not relevant to the processing gain of interfering users: it is relevant only to the processing gain of the user, transmitted powers, PN sequences, and spreading codes. The performance of short codes turns out to be better than that of long and random codes as in other systems.

Verification of timed bisimulation equivalence is generally difficult because of the state explosion caused by concrete time values. In this paper, we propose a verification method to verify timed bisimulation equivalence of two timed processes using a symbolic technique similar to [1]. We first propose a new model of timed processes, Alternating Timed Symbolic Labelled Transition System (A-TSLTS). In an A-TSLTS, each state has some parameter variables, whose values determine its behaviour. Each transition in an A-TSLTS has a quard predicate. The transition is executable if and only if its guard predicate is true underspecified parameter values. In the proposed method, we can obtain the weakest condition for a state-pair in a finite A-TSLTS, which the parameter values in the weakest condition must satisfy to make the state-pair be timed bisimulation equivalent.

This paper proposes the concept of information retrieval for fine arts database system on the fuzzy set theory, especially concerning to sensitive impression and location data. The authors have already reported several important formulations about the data structure and information retrieval models based on the fuzzy set theory for multimedia database. The fuzzy models of the information retrieval are implemented in the fine arts database system, which has the following features: (1) The procedure of information retrieval is formulated in the fuzzy set theory; (2) This database can treat multimedia data such as document data, sensitive impression, location information, and imagedata. (3) It is possible to retrieve the stored data based on sensitive impression and the location data such as "joyful pictures which have a mountain in the center and there is a tree in the right"; (4) Users can input impression words as a retrieval condition, and estimate their grades such as "low," "medium," and "high"; (5) For the result of information retrieval, the satisfaction grade is calculated based on fuzzy retrieval model; and (6) The stored data are about 400 fine arts paintings which are inserted by the textbook of fine arts currently used at the junior high school and high school in Japan. These features of this system give an effects of the fine arts education, and should be useful for information retrieval of fine arts. The results of this study will become increasingly important in connection with development of multimedia technology.

For object analysis and recognition, an original shape often needs to be described by using a small number of vertices. Polygonal approximation is one of the useful methods for the description. In this paper, we propose the curvature-based polygonal approximation (CBPA) method that is an application of the weighted polygonal approximation problem which minimizes the number of vertices of an approximate curve for a given error tolerance (the weighted minimum number problem). The CBPA method considers the curvature information of each vertex of an input curve as the weight of the vertex, and it can be executed in O(n2) time where n is the number of vertices of the input curve. Experimental results show that this method is effective even in the case when relatively few vertices are given as an original shape of a planar object, such as handwritten letters, figures (freehand curves) and wave-form data.

In this letter, a theoretical estimation of pick-up characteristics of the fiber probe of Photon Scanning Tunneling Microscopy based on the Wiener-Hopf technique taken account of the weakly guiding approximation are reported. As a result, it is found that diffracted waves by the extremity of the fiber probe mainly act on the mode excitation rather than transmitted waves, then the pick-up characteristics are well accordance with typical experiments quality and quantity.

In this paper, we propose a practical and secure electronic voting scheme which meets the requirements of large scale general elections. This scheme involves voters, the administrator or so called the government and some scrutineers. In our scheme, a voter only has to communicate with the administrator three times and it ensures independence among voters without the need of any global computation. This scheme uses the threshold cryptosystem to guarantee the fairness among the candidate's campaign and to provide mechanism for achieving the function that any voter can make an open objection to the tally if his vote has not been published. This scheme preserves the privacy of a voter against the administrator, scrutineers, and other voters. Completeness, robustness, and verifiability of the voting process are ensured and hence no one can produce a false tally, corrupt or disrupt the election.

In this paper, we propose a new transaction numbering scheme and a new validation scheme for controlling transactions optimistically in client-server architectural mobile distributed database systems (MDDBSs). In the system, mobile units (MUs) request transaction-related services, e.g., concurrency control, commit process, then the mobile support stations (MSSs) provide the required services. The mobile computing environment makes it very difficult for each MU to assign unique transaction number to transactions since it is allowed to move in communication disconnected states. Besides, validating transactions numbered by the previous transaction numbering scheme could wait indefinitely in the case of data transfer delay. Thus, we propose a new transaction numbering scheme called datatransfer time oriented transaction numbering scheme (DATTO) ,in which we can remove waiting time for validation by determining validation-start time with data-transfer completion time. However, if the previous validation scheme for the static environment is directly applied transactions numbered by DATTO, undesirable results could occur in abnormal cases due to latency on the wireless communication. Thus, we also propose a new validation scheme, called commit-order oriented validation (COOV) ,which is always able to produce correct results by applying backward validation to the abnormal cases.

A new simple cell spacing architecture that guarantees the peak cell interval and realizes preferential contention resolution is proposed. Scheduling the cell emission on departure of the previous cell, not arrival, allows the source peak cell interval to be regenerated without clumping. Priority control is also realized in the proposed spacer. A connection is scheduled either at the head or tail of the contention chain depending on its priority. The proposed method is applied to realize the UPC function. The proposed cell spacer eliminates the clumping effects of CDV completely and achieves high bandwidth efficiency.

A new learning algorithm is proposed to enhance fault tolerance ability of the feedforward neural networks. The algorithm focuses on the links (weights) that may cause errors at the output when they are open faults. The relevances of the synaptic weights to the output error (i.e. the sensitivity of the output error to the weight fault) are estimated in each training cycle of the standard backpropagation using the Taylor expansion of the output around fault-free weights. Then the weight giving the maximum relevance is decreased. The approach taken by the algorithm described in this paper is to prevent the weights from having large relevances. The simulation results indicate that the network trained with the proposed algorithm do have significantly better fault tolerance than the network trained with the standard backpropagation algorithm. The simulation results show that the fault tolerance and the generalization abilities are improved.

We propose an InGaAlAs waveguide p-i-n photodiode (WG-PD) with a thick symmetric double-core for surface-hybrid integration onto optical platforms, which can be applied to low cost optical modules for access networks. The waveguide structure is designed to efficiently couple to flat-ended single mode fibers while maintaining low-voltage (less than 2 V) operation. Crystal growth conditions and a passivation technique are also investigated for obtaining high responsivity, low dark current and highly reliable operation. Fiber-coupled responsivity as high as 0.95 A/W, at a 1.3-µm wavelength, and vertical coupling tolerance as wide as 2.6 µm are demonstrated for a dispersion-shifted fiber (DSF) coupling at an operating voltage of 2 V. Dark current is as low as 300 pA at 25 and 12 nA at 100. A temperature accelerated aging test is performed to show the feasibility of using the WG-PD in long-term practical applications.

In direction of arrival estimation, the locations of point sources are usually assumed to be fixed during the observation of data, which is reasonable in many cases. If the locations of the point sources are perturbed due to some reasons in a statistical way during the observed period and the signal sources are not far away from receiver array, however, direction of arrival estimation methods based on the fixed point source assumption may provide with incorrect results. In this paper, we propose a perturved-location source model. Under the model, an estimation method based on eigen-decomposition is investigated. In addition, the asymptotic distributions of the estimation errors of the parameters are obtained to show the statistical properties of the parameters are obtained to show the statistical properties of the estimation method.

In this paper we discuss the limiting behavior of the search direction of the steepest descent method in minimizing the Rayleigh quotient. This minimization problem is equivalent to finding the smallest eigenvalue of a matrix. It is shown that the search direction asymptotically alternates between two directions represented by linear combinations of two eigenvectors of the matrix. This is similar to the phenomenon in minimizing the quadratic form. We also show that these eigenvectors correspond to the largest and second-smallest eigenvalues, unlike in the case of the quadratic form.

Periodic reservation allows periodic and random packets to share the same satellite random access channel efficiently. The periodic reservation protocol is particularly suitable for mobile satellite position reporting services, where some of the information messages, such as dispatch function, are classified as "periodic" and others, such as signaling, are classified as "random." When a new mobile terminal logs on to the system, Network Management Center (NMC) reserves subsequent time slots for transmitting periodic packets without contention. A mobile terminal recognizes each time slot as "reserved" or "unreserved (available)" according to the broadcast message received from NMC. Other random packets use the slotted ALOHA protocol to contend with other mobile terminals for an unreserved time slot. The performance results suggest that the use of the periodic reservation protocol can be regarded as a viable solution for mobile satellite position reporting services such as automatic dependent surveillance (ADS).

A simple extension to treat evanescent modal excitation at the aperture of a parallel plane waveguide is shown here by GTD diffracted rays with complex propagation angles. Numerical comparison with other solution confirmed that our simple solution can be used for modal excitation estimation below the cut-off frequency.

In this paper, we show an entropy-based approach to the privacy of multi-party protocols. First, we formulate the amount of leaked information by using mutual information for a two-party case. This is a better measure for some situations than the combinatorial measure known so far. Next, we apply multi-terminal information theoty to more than two parties and give the first formulation of the leaked information for more than two parties.

The fault tolerant computer (FTC) is applied as a communication or database server in the information service and computer aided process control fields. User requires of the FTC are to provide the current level of performance and software transparency needing no additional dedicated program for fault tolerance. To meet these requirements, we propose quadprocessor redundancy (QPR) architecture that combines dualRISC based duplicated CPUs integrating main memories, and duplicated I/O subsystems by using some additional hardware. Duplicated CPUs run under the instruction level synchronization (lock step operation) , and the duplicated I/O subsystems are managed by an operating system. When a fault is detected, the faulty CPU is isolated by hardware. User program is continuously executed by the remaining CPU. We applied the QPR to our UNIX servers, and achieved satisfactory levels of performance.

A method of motion segmentation in RGB image sequences is presented in details. The method is based on moving object modeling by a six-variate Gaussian distribution and a hidden Markov random field (MRF) framework. It is an extended and improved version of our previous work. Based on mathematical principles the energy expression of MRF is modified. Moreover, an initialization procedure for the first frame of the sequence is introduced. Both modifications result in new interesting features. The first involves a rather simple parameter estimation which has to be performed before the use of the method. Now, the values of Maximum Likelihood (ML) estimators of the parameters can be used without any user's modifications. The last allows one to avoid finding manually the localization mask of moving object in the first frame. Experimental results showing the usefulness of the method are also included.