Considered is the theory of several dielectric waveguide phenomena for which the vector nature of the electromagnetic field is essential. These phenomena are the following rotation of the plane of polarization in chiral and twisted waveguides, Bragg's reflection in a twisted waveguide in a narrow frequency band, and excitation of a waveguide at a near-cutoff frequency.

We believe that virtual world communication will subsume BBS and visual communication. Accordingly, we proposed the networked virtual world "Interspace" for visual communication. If we are to achieve education and training in this world, techniques to receive and transmit information without any special training are necessary. The traditional "easy" ways of transmitting information are talking and drawing. In Interspace, users can already talk each other. In this paper we focus on drawing. In daily life we communicate through drawings in various situations. At this time it is important to recognize who is drawing and where the participants are watching. It is difficult to realize these functions using conventional media, but it is possible to realize them in virtual space. In virtual space, the system can clearly represent who is drawing and where participants are watching; expressing topics in virtual space frees us from many physical restrictions. In this paper we discuss the process of drawing when many participants share topics in virtual space; the necessary conditions for our system are considered. We design a system that offers functions to make drawing sheets, to display the view fields of participants, and to share visual fields. Furthermore, we propose the mode of InterSheet called "InterMirror" which shows mirror images of partners and their drawings. We make a prototype and evaluate it. The results indicate the synergistic effect of drawing with voice and the usefulness of drawing for communication in virtual space.

Realizing an effective channel connection scheme and a useful human-machine interface is important for popularizing the audio-visual communication services that should become significant in the near future. This paper describes a terminal design that is applicable to various audio-visual communication services. First, future audio-visual services are classified into three types: Videophone, Tele-monitoring and Video On Demand(VOD). The requirements for these services are discussed in detail. Second, a channel connection scheme is specified taking into consideration for the requirements and characteristics of various networks such as N-ISDN and LANs. Terminals based on these specifications are developed as prototypes and demonstrated to confirm the validity of these specifications.

We propose a new high-performance message router for k-ary n-cube multicomputer systems, called the Tokky router. The router utilizes a small number of queues at the outputs of its communication ports to allow fully adaptive routing, misrouting to prevent deadlocks and randomization to prevent livelock. Uncongeste network performance is improved by the inclusion of the packet expressway. Accurate models are developed to predict the switch and buffer performance of routers for varying radix and dimension and these models can be used in the design of routers for networks other than those investigated here. The simulated performance of the router exceeds that of published results for oblivious routers and is equal to or exceeds those reported for other adaptive routers. These performance predictions are especially encouraging when the simplicity of the control structures required to implement the router are taken into consideration.

On a simple model, the quality of the security tag is simulated theoretically and experimentally. A simple correction makes both results correspond exactly and a simulation formula is provided. By using novel insulating film, a small-sized tag of high quality is developed.

In this paper a priori estimation method is presented for calculating solution of convex optimization problems (COP) with some equality and/or inequality constraints by so-called Newton type homotopy method. The homotopy method is known as an efficient algorithm which can always calculate solution of nonlinear equations under a certain mild condition. Although, in general, it is difficult to estimate a priori computational complexity of calculating solution by the homotopy method. In the presented papers, a sufficient condition is considered for linear homotopy, under which an upper bound of the complexity can be estimated a priori. For the condition it is seen that Urabe type convergence theorem plays an important role. In this paper, by introducing the results, it is shown that under a certain condition a global minimum of COP can be always calculated, and that computational complexity of the calculation can be a priori estimated. Suitability of the estimation for analysing COP is also discussed.

Portable terminals have the potential of providing information and communication services not only to computer experts at their offices but also to many users being in a variety of daily life situations. The current user interfaces (UIs) of portable terminals are not suitable for a novice user of computers; they require some knowledge on computers from a user. To overcome this problem, the authors tried to implement their knowledge on the daily life in the design of a UI for novice users. As a result, two UI mechanisms, called Novice Interface and Graphical Metaphor Interface, which provide operations, expressions, and data structures in a way similar to those usually used in daily life are proposed. Novice Interface is to provide easy to use environment. It adopts a direct manipulation device with three buttons and a model of data structures, called Small World Model, that limits the number of functions and the depth of hierarchical menu. Graphical Metaphor Interface, being an extension of Novice Interface, is to provide services with a display screen that makes them well-understandable for any user. The proposed UI mechanisms were implemented in a prototype terminal and its software platform. The former offers several applications of the information services (like teleshopping, home banking, or database retrieval) and the communication services (like pen-based image mail, software fax, or telewriting); the latter enables those application programs to provide a consistent UI.

The classification of remotely sensed multispectral data using classical statistical methods has been worked on for several decades. Recently there have been many new developments in neural network (NN) research, and many new applications have been studied. It is well known that NN approaches have the ability to classify without assuming a distribution. We have proposed an NN model to combine the spectral and spacial information of a LANDSAT TM image. In this paper, we apply the NN approach with a normalization method to classify multi-temporal LANDSAT TM images in order to investigate the robustness of our approach. From our experiments, we have confirmed that our approach is more effective for the classification of multi-temporal data than the original NN approach and maximum likelihood approach.

We present that event-transition diagrams are useful to analyze event concurrent response visually. Event-transition diagrams are dual for state-transition diagrams in graph theory. As an example of an usage of an event-transition diagram, a simple model of a railroad crossing is presented.

In practical applications of the artificial boundary surfaces, such as corrugation and strips on a grounded dielectric slab, the surfaces have finite sizes. The diffraction fields from anisotropic surface of this kind can not be calculated using conventional diffraction coefficients. In this paper, uniform diffraction coefficients for the strips on a grounded dielectric slab are given in the sense of physical optics, as functions of incident angle, polarization and structural parameters of the surface. Firstly, the incident plane wave is decomposed into the two special polarization directions. Then uniform diffraction coefficients originally derived for isotropic surfaces with arbitrary impedance can be applied for each polarization component. Finally, expressions for the diffraction coefficients from the anisotropic surface are given as the sum of those for two polarization components. The validity of the diffraction coefficients is verified theoretically and experimentally.

The emphasis on nonisotropic media in the electromagnetics research community has recently brought forward a large amount of new literature on the material effects. The material phenomena affecting the electromagnetic characterization are contained in the constitutive relations between an electric and a magnetic excitation and an electric and a magnetic response. Starting from the constitutive equations, this article is an attempt to cast light on the labels, terms, notation, and classification of linear electromagnetic materials. Using dyadic analysis and physical concepts like reciprocity and magnetoelectric coupling, the different classes within bi-anisotropic media are presented in systematic form. Simple isotropic media can be characterized by two material parameters: the electric polarizability is measured by permittivity ε, and the magnetic polarizability by the permeability µ. For bi-isotropic media, there exists magnetoelectric coupling, but due to isotropy (independence of the direction of the field vectors) the two additional material parameters are scalars. The physical interpretation to these two parameters are chirality and nonreciprocity. The two subclasses of bi-isotropic materials are Pasteur and Tellegen media. If there is direction dependence in the medium, we call the material anisotropic, and a scalar quantity has to be described by a dyadic with nine components. Finally, the most general material is called bi-anisotropic, which means that in addition to a dyadic permittivity and permeability, the two magnetoelectric material parameters are dyadics. The essential feature in the classification of the present paper is the separation of all the four material parameter dyadics into symmetric and antisymmetric parts. For permittivity and permeability, the symmetric parts correspond to reciprocal media and the antisymmetric parts are nonzero for nonreciprocal media. In the cross-coupling dyadics the decomposition into symmetric and antisymmetric parts disriminates chiral media, omega media, classical magnetoelectric media, and moving media. Finally, possible alternative characterrizations of bi-anisotropic materials are discussed.

The dielectric rod waveguides with corrugation consisting of nonintegral-ratio period waves are investigated numerically. The leakage characteristics of HE11-type wave in the waveguide is analyzed by applying Yasuura's method. The complex propagation constants and the far field patterns are presented. The radiation pattern of a fabricated waveguide with corrugation agrees well with the calculated value. The dependence of radiation characteristics on the corrugation form is discussed. It is shown that the leakage directions and the intensity of leaky waves are controlled independently one another. The radiation pattern can be synthesized by choosing the geometric parameters of the corrugation properly.

In this paper, the diffusion parameter-values in the K+-ion diffused waveguides made by diluted KNO3 with NaNO3 in the soda-lime glass, which are determined from measured values of the effective index, are presented together with a simple method for the determination. The surface-index changes are measured for the waveguides by KNO3 melts with 75%-, 50%- and 30%-dilutions (weight ratio), and for comparison purpose, also by the pure KNO3, and the dependence of the index-profile on the dilution of KNO3 in the ion-source melt is shown. Change of the two-dimensional index profile in the diffused channel waveguide with the KNO3-dilution is also shown, which is calculated with the measured diffusion parameters.

This paper proposes a new algorithm called the fast Projection algorithm, which reduces the computational complexity of the Projection algorithm from (p+1)L+O(p3) to 2L+20p (where L is the length of the estimation filter and p is the projection order.) This algorithm has properties that lie between those of NLMS and RLS, i.e. less computational complexity than RLS but much faster convergence than NLMS for input signals like speech. The reduction of computation consists of two parts. One concerns calculating the pre-filtering vector which originally took O(p3) operations. Our new algorithm computes the pre-filtering vector recursively with about 15p operations. The other reduction is accomplished by introducing an approximation vector of the estimation filter. Experimental results for speech input show that the convergence speed of the Projection algorithm approaches that of RLS as the projection order increases with only a slight extra calculation complexity beyond that of NLMS, which indicates the efficiency of the proposed fast Projection algorithm.

We present a framework for the unsupervised segmentation of time series. It applies to non-stationary signals originating from different dynamical systems which alternate in time, a phenomenon which appears in many natural systems. In our approach, predictors compete for data points of a given time series. We combine competition and evolutionary inertia to a learning rule. Under this learning rule the system evolves such that the predictors, which finally survive, unambiguously identify the underlying processes. The segmentation achieved by this method is very precise and transients are included, a fact, which makes our approach promising for future applications.

This paper presents a theoretical study on transmission properties of bent optical waveguides of uniaxial anisotropic material. The waveguiding structure consists of two parallel straight slab waveguides connecting by an oblique section. By arranging the direction of the optical axis in the oblique section so that the wave normal always points to the same direction throughout the waveguiding structure, low loss transmission can be realized. The analysis of wave propagation through the structure is based on the finite difference beam propagation method. Numerical results indicate that by optimally arranging the direction of the optical axis in the oblique section power coupling coefficients better than 95% can be obtained for any tilt angle of the oblique section when the tilt angle is smaller than 2 degrees. Some field distributions are also presented along the waveguiding structure.

The number of solutions of a nonlinear equation x = sgn(Wx) is discussed. The equation is derived for the determination of equilibrium points of a kind of Hopfield neural networks. We impose some conditions on W. The conditions correspond to the case where a Hopfield neural network has n neurons arranged on a ring, each neuron has connections only from k preceding neurons and the magnitude of k connections decrease as the distance between two neurons increases. We show that the maximum number of solutions for the above case is extremely few and is independent of the number of neurons, n, if k is less than or equal to 4. We also show that the number of solutions generally increases exponentially with n by considering the case where k = n-1.

The main purpose of this paper is to give a new representation method of the convergence characteristics of the LMS algorithm using tap-input vectors. The described representation method is an extended version of the interpretation method based on the orthogonal projection. Using this new representation, we can express the convergence characteristics in terms of tap-input vectors instead of the eigenvalues of the input signal. From this representation, we consider a general method for improving the convergence speed.

We propose an equivalent circuit model described by the Rössler equation. Then we can consider a coupled Rössler system with a physical meaning on the connection. We consider an oscillatory circuit such that two identical Rössler circuits are coupled by a resistor. We have studied three routes to entirely and almost synchronized chaotic attractors from phase-locked periodic oscillations. Moreover, to simplify understanding of synchronization phenomena in the coupled Rössler system, we investigate a mutually coupled map that shows analogous locking properties to the coupled Rössler System.

The complex refractive indices n-jχ of typical magnetic fluids were evaluated for the sake of utilizing them as optical materials. Transmission and reflection spectra were measured in the wavelength range of 0.6-1.6 µm by using monochromators. Magnetic fluids were put into glass cells of 2.5-14-µm thickness for transmission measurement. Due to the absorption by magnetic fluids, the transmittance decreased notably with the increase of the sample thickness. The extinction coefficient χ was evaluated from the dependence of the transmittance on the sample thickness. χ was found to vary between 0.003 and 0.03 depending upon wavelength. The refractive index n was evaluated by fitting theoretical curves to the reflectances that were measured for various incident angles. n was found to vary between 1.6 and 1.7 depending slightly on wavelength. Since a magnetic fluid is a composite of ferrite particles and a solvent, the refractive index can be calculated by using the effective medium theory. The calculated value agreed well with the experimental value. Preliminary experiment of optical switching was also demonstrated by utilizing the mobility of a magnetic fluid.