This paper describes a method for describing a three-dimensional (3-D) scene by integrating color and range data. Range data is obtained by a feature-based stereo method developed in our laboratory. A color image is segmented into uniform color regions. A plane is fitted to the range data inside a segmented region. Regions are classified into three types based on the range data. A certain types of regions are merged and the others remain unless the region type is modified. The region type is modified if the range data on a plane are selected by removing of the some range data. As a result, the scene is represented by planar surfaces with homogeneous colors. Experimental results for real scenes are shown.

We have proposed a new omnidirectional image sensor COPIS (COnic Projection Image Sensor) for guiding navigation of a mobile robot. Its feature is passive sensing of the omnidirectional image of the environment in real-time (at the frame rate of a TV camera) using a conic mirror. COPIS is a suitable sensor for visual navigation in real world environment with moving objects. This paper describes a method for estimating the location and the motion of the robot by detecting the azimuth of each object in the omnidirectional image. In this method, the azimuth is matched with the given environmental map. The robot can always estimate its own location and motion precisely because COPIS observes a 360 degree view around the robot even if all edges are not extracted correctly from the omnidirectional image. We also present a method to avoid collision against unknown obstacles and estimate their locations by detecting their azimuth changes while the robot is moving in the environment. Using the COPIS system, we performed several experiments in the real world.

This paper describes the potential of KrF excimer laser lithography for the development and production of 64 M and 256 Mbit DRAMs on the basis of our recent developed results. Quarter micron KrF excimer laser lithography has been developed. A new chemically amplified positive resist realizes high stability and process compatibility for 0.25 micron line and space patterns and 0.35 micron contact hole patterns. This developed resist is characterized as the increase of dissolution characteristics in exposed areas, and hence means the high resolution is obtained. A multiple interference effect was greatly reduced by using our over coat film or anti-reflective coating. This over coat film has no intermixing to the resist and it is simultaneously removed when the resist is developed. This anti-reflective coating has low etch selectivity to the resist, and hence the over coat film is etched away when etching the substrate. The two major results indicate that the KrF excimer laser lithography is promising for the development of 256 MDRAMs.

Gradient-based methods for the computation of the velocity from image sequences assume that the velocity field varies smoothly over image. This creates difficulties at regions where the image intensity changes abruptly such as the occluding contours or region boundaries. In this letter, we propose a method to overcome these difficulties by incorporating the information of discontinuities in image intensity into a standard local optimization method. The presented method is applied to the synthetic and real images. The results show that the velocity field computed by the proposed method is less blurred at region boundaries than that of the standard method.

This paper presents an optimal constraint graph generation algorithm for graph-based one-dimensional layout compaction. The first published algorithm for this problem was the shadow-propagation algorithm. However, without sophisticated implementation of a shadow-front, complexity of the algorithm could fall into O(n2), where n is the number of layout objects. Although our algorithm, called the enhanced plane-sweep based graph generation algorithm, is an extension of the shadow-propagation algorithm, such a drawback is resolved by introducing an enhanced plane-sweep technique. The algorithm maintains multiple shadow-fronts simultaneously by storing them in a work-list called previous-boundary. Since a balanced search tree is selected for implementation of the worklist, total complexity of the algorithm is O(n log n) which is optimal. Experimental results show that the enhanced plane-sweep based graph generation algorithm runs in almost linear time with respect to the number of layout objects and is faster than the perpendicular plane-sweep algorithm which is also optimal in terms of time complexity.

Periodic schedules are seldom treated in the theory but abound in practice (air flight schedule, train schedule, manufacturing schedule, etc). This paper introduces a Petri Net based perspective to periodic schedules. These are classified, according to the time interpretation into single-server and multiple-server semantics and, according to transitions firing periodicity constraints, into strict and general periodic schedules. Using a net transformation rule, the computation of the general schedule class can be done through techniques for the strict subclass. Introducing truncation error terms ε for the floor functions, a necessary and sufficient condition for the feasibility of a strict periodic schedule is given in terms of a large size system of nonlinear inequalities containing ε terms. Moreover averaging this condition on subperiods allows to get a small size linear system of inequalities as necessary conditions for speeding up iterative computation processes. This paper aims to present qualitative analysis of periodic schedules for deterministically timed Petri net systems, as a precursor to quantitative analysis that requires large-scale computational experiments and hence will be dealt in later work.

The concentration of the electric field at the edge of the electrode has been simulated in several types of flat DRAM cell capacitors with high permittivity dielectrics. The results indicated that the permittivity of the material surrounding the edge of the electrode as well as the geometrical structure affected the concentration of the electric field. The electric field strength was minimized and most evenly distributed by utilizing the structure in which the sidewall of the capacitor dielectric was terminated at the edge of the electrode by a low-dielectric constant insulator. High-precision fabrication of the capacitor's profile is required for the minimization and uniformity of the electric field.

Correspondence based on regions rather than lines seems to be effective, as regions are usually fewer than other image features and provide global information such as size, color, adjacency, etc. In this paper, we present a region matching approach for solving the correspondence problem. Images are segmented into regions and are individually described by classification tables using region adjacencies. From the structural description of the two images, the region matching process based on color and structural similarity is carried out. First, a small number of significant regions are selected and matched by using color, and then they are used as handles for constraint propagation to match the remaining regions by using structures. Our technique was implemented by using an efficient selection and propagation algorithm and was tested with a variety of scenes.

We present a navigation system using ultrasonic sensors for unknown and dynamic indoor environments. To achieve the robustness and flexibility of the mobile robot, we develop a behavior-based system architecture, consisting of multi-layered behaviors. Basic behaviors required for the navigation of a mobile robot, such as, avoiding obstacles, moving towards free space, and following targets, are redundantly developed as agents and combined in a behavior-based system architecture. An extended potential filed method is developed to produce the appropriate velocity and steering commands for the behaviors of the robot. We demonstrate the capabilities of our system through real world experiments in unstructured dynamic office environments using an indoor mobile robot.

In this paper, we propose an algorithm of O(|V|min{k,|V|,|A|}|A|) time complexity for finding all k-edge-connected components of a given digraph D=(V,A) and a positive integer k. When D is symmetric, incorporating a preprocessing reduces this time complexity to O(|A|+|V|2+|V|min{k,|V|}min{k|V|,|A|}), which is at most O(|A|+k2|V|2).

The 22 mechanical optical switch for single mode fiber (SMF) is reported. By using the precision grinding and molding techniques all-plastic multiple-fiber connector, 22 pin-referenced indirect slide switch is developed. The characteristics and the reliability test's results of this optical switch are also reported. Evaluations confirm that the switch has low insertion loss, high-speed switching, stable switching operations and reliability in practical applications.

Broadband ISDN based on ATM technologies is expected to offer enhanced and sophisticated services to customers. Since ATM will first be introduced in the business communication world, it will be worth to discuss the future image of desirable ATM customer premises network (CPN). In this paper, we first consider the possible migration scenario of Broadband CPN and some important requirements for the realization of the scenario. Then, we discuss the key issues to be solved for future ATM-CPN, which include network topology, traffic control and connectionless communication services.

Robust-fault tolerance is a property that a computational result becomes nearly equal to the correct one at the occurrence of faults in digital system. There are many cases where the safety of digital control systems can be maintained if the property is satisfied. In this paper, robust-fault-tolerant three-valued arithmetic modules such as an adder and a multiplier are proposed. The positive and negative integers are represented by the number of 1's and 1's, respectively. The design concept of the arithmetic modules is that a fault makes linearly additive effect with a small value to the final result. Each arithmetic module consists of identical submodules linearly connected, so that multi-stage structure is formed to generate the final output from the last submodule. Between the input and output digits in the submodule some simple functional relation is satisfied with respect to the number of 1's and 1's. Moreover, the output digit value depends on very small portion of the submodules including the input digits. These properties make the linearly additive effect with a small value to the final result in the arithmetic modules even if multiple faults are occurred at the input and output of any gates in the submodules. Not only direct three-valued representation but also the use of three-valued logic circuits is inherently suitable for efficient implementation of the arithmetic VLSI system. The evaluation of the robust-fault-tolerant three-valued arithmetic modules is done with regard to the chip size and the speed using the standard CMOS design rule. As a result, it is made clear that the chip size can be greatly reduced.

Widespread penetration of data communications in a LAN environment is generating a demand for high speed data transfer over wide area networks. It is anticipated that the connectionless (CL) service based on IEEE802.6 technology, called Switched Multi-megabit Data Service (SMDS), will be employed before this is realized by B-ISDN based technology. An important early application of B-ISDN will be interconnections between LANs, and continued support of the IEEE802.6 based CL service. This paper first reviews relevant technologies, clarifies comparison between IEEE802.6 based and B-ISDN based CL services, and points out that the important feature for users is that both CL services conform to the E.164 ISDN numbering plan for message addressing. Since an addressing scheme is the key to network services, conformity between the two will easily rationalize service migration from the IEEE802.6 based CL service to the B-ISDN based CL service. To permit such a service migration, this paper considers interworking scenarios for two CL services taking account of the penetration of inter-LAN communications. An exploring path is also presented to that users will not need to be aware of an alternation of network configuration, and smooth migration can take place. For facilitating high volume CL communications in the B-ISDN era, a virtual CL network is discussed to utilize ATM functionalities and to realize broadcasting and robust connectionless service capabilities. An overall comparison between a ring and mesh/star topology for the CL network is presented, and a detailed performance study is addressed in the context of Quality of Service which may depend on the particular application. This paper then describes a connectionless switch architecture in which a message switch combined with an ATM cell channel switch is presented. One scheme which receives specific attention here is a non-assembly message switching method to achieve robust switching capabilities. Typical performance evaluation results based on an M/G/1 queueing model are also reported.

An accurate numerical solution is presented for the electromagnetic scattering from a double strip grating, where the strip planes are each supported by a dielectric slab. This structure is a model of polarization diplexers. The direction of propagation and the polarization of the incident plane wave are arbitrary. We derive a set of singular integral equations and solve it by the moment method, where the Chebyshev polynomials are successfully used as the basis and the testing functions. By numerical computations we examine the dependence of the diplexing properties on grating parameters in detail. The cross-polarization characteristics at skew incidence are also referred. From these results we construct an algorithm for the design of polarization diplexers.

The properties of the Haar Transform (HT) are discussed based on the Wavelet Transform theory. A system with two channels at resolution 2-1 and 2-2 for detecting paroxysm-spike in human's EEG is presented according to the multiresolution properties of the HT. The system adopts a coarse-to-fine strategy. First, it performs the coarse recognition on the 2-2 channel for selecting the candidate of spike in terms of rather relaxed criterion. Then, if the candidate appears, the fine recognition on the 2-1 channel is carried out for detecting spike in terms of stricter criterion. Three features of spike are extracted by investigating its intrinsic properties based on the HT. In the case of having no knowledge of prior probability of the presence of spike, the Neyman-Pearson criteria is applied to determining thresholds on the basis of the probability distribution of background and spike obtained by the results of statistical analysis to minimize error probability. The HT coefficients at resolution 2-2 and 2-1 can be computed individually and the data are compressed with 4:1 and 2:1 respectively. A half wave is regarded as the basic recognition unit so as to be capable of detecting negative and positive spikes simultaneously. The system provides a means of pattern recognition for non-stationary signal including sharp variation points in the transform domain. It is specially suitable and efficient to recognize the transient wave with small probability of occurrence in non-stationary signal. The practical examples show the performance of the system.

In this paper we propose a new timing optimization technique for multi-level networks by restructuring multiple nodes simultaneously. Multi-output subcircuits on critical paths are extracted and resynthesized so that the delays of the paths are reduced. The complete design space of the subcircuits is captured by Boolean relations, which allow us to perform more powerful resynthesis than previous approaches using don't cares. Experimental results are reported to show the effectiveness of the proposed technique.

Broadband ISDN, using asynchronous transfer mode, are expected to carry traffic of different classes, each with its own set of traffic characteristics and performance requirements. To achieve the quality of service in ATM networks, a suitable buffer management scheme is needed. In this paper, we propose a buffer management scheme using a priority service discipline to improve the delay time of delay-sensitive class and the packet loss ratio of loss-sensitive class. The proposed priority scheme requires simple buffer management logic and minor processing overhead. We also analyze the delay time and the packet loss ratio for each class of service. The results indicate that the required buffer size of the proposed priority scheme is reduced and the delay time of each class of service is controlled by a parameter. If the control parameter is appropriately chosen, the quality of service of each class is improved.

Two computational-geometric approaches to linear programming are surveyed. One is based on the prune-and-search paradigm and the other utilizes randomization. These two techniques are quite useful to solve geometric problems efficiently, and have many other applications, some of which are also mentioned.

The evolution of Multiple-Valued Logic (MVL) circuits has been inexorably tied to the rapid technological changes induced by evolving needs and emerging developments in computing methodologies. Unfortunately for MVL, the numbers of designers of technologies and circuits whose lives are dedicated to the improvement of binary techniques, are large and overwhelming. Correspondingly, technological developments in MVL typically await the appearance of a problem or technique in the larger binary world to motivate and/or make possible some new advance. Such opportunities are inevitably quite transient since each such problem is simultaneously attacked by many others of a more conventional bent, and, as well, each technological change begets yet another, quickly. It is in the sensing of this reality that the present paper is written. Correspondingly, its thrust is two-fold: One target is the possibility of encouraging a leap ahead through modest technological projection. The other is the possibility of identifying application areas that already exist in this unbalanced competition, but which are specially suited to multiple-valued solutions. For example, it has been clear for decades that one such area is that of arithmetic. Correspondingly, we in MVL must strive quickly to concentrate our efforts on applications that exploit such demonstrable strengths. Some such applications are includes here; others are visible historically, many probably remain to be found: Search on!