A new leaky surface wave on lithium tetraborate that propagates along the surface with a higher phase velocity than that of ordinary leaky surface waves, radiating two bulk wave terms into the solid, is described.

Coupling optics for a monolithic array LD module has been developed. High efficient and small sized confocal optics with aspheric lenses based on hyperbolic surfaces has been designed to achieve the uniformity of coupling loss. A small sized (7.2 cc) 4 channel array LD module with this optics was fabricated. This module has low (4.2 dB) and uniform (0.5 dB) coupling loss.

Along with the improvement of micro processors and local area networks, a distributed system becomes useful to realize a telecommunication system. It has potential advantage to achieve both high performance and high reliability. However, the design of a distributed system tends to be more complicated compared to a conventional centralized system. For the purpose of the standardization of distributed processing, ISO and ITU-T study the Open Distributed Processing (ODP) and are currently standardizing the Basic Reference Model of ODP (RM-ODP). To avoid dealing with the complexity of distributed systems, RM-ODP defines five viewpoints. The viewpoint approach of RM-ODP is proposed as a framework for the design of a distributed system. Although some previous works give the design methods of distributed systems based on the ODP viewpoint approach, the detailed design method has not been fully specified or all of the five viewpoints are not taken into account. In this paper, we describe a detailed design method for a distributed telecommunication system based on the ODP viewpoint approach. The method applies the five viewpoints to the three phases of design of a distributed system, that is, requirement analysis, functional design and detailed design phase. It clarifies what specifications for the target system should be made from the individual viewpoints and how the specifications are related each other. It also takes account of the platform which provides the distribution support, and gives the design method for both the platform and the application specific functions on the platform. The design method is examined by applying it to the design of a distributed MHS system supporting X.400 series protocols. In this example, the remote procedure call based on the client-server model is selected as the base of the platform. The result shows that our method is useful to simplify the complexity of the design for a distributed telecommunication system.

In this paper, we subjects the case that frequency–shift–keying (FSK) modulation and phase locked loop (PLL) demodulator are used in frequency hopped spread spectrum (FH–SS) communication system. So the carrier frequencies of undesired transmitters may come into collision with the carrier frequency of desired transmitter in this communication system, we evaluate the response of PLL by two sinusoidal inputs so as to estimate how the response of PLL demodulator is affected by the collision of carrier frequencies. First, we compute the synchronization diagrams of PLL with two sinusoids. From this, it is indicated that allowable value of amplitude ratio of interference transmitter's signal to disired transmitter's signal decreases with increasing FSK modulation width of desired transmitter. Next, we calculated the output of PLL demodulator with two sinusoids. To this end, it is shown that the allowable value of amplitude ratio is bounded by a constant value even if FSK modulation width is enough small.

In this paper, the power dissipation issue is considered in the gate sizing procedure. In order to observe the tradeoff among area, delar and power dissipation in a circuit, gate sizing algorithms which can minimize power under delay constraints or minimize area under power and delay constraints are formulated. Experiments are performed to investigate the properties of area–power–delay tradeoff in the gate sizing procedure.

The analytic structure of the governing equation for a 2nd order Phase–Locked Loops (PLL) is studied in the complex time plane. By a local reduction of the PLL equation to the Ricatti equation, the PLL equation is analytically shown to have singularities which form a fractal structure in the complex time plane. Such a fractal structure of complex time singularities is known to be characteristic for nonintegrable, especially chaotic systems. On the other hand, a direct numerical detection of the complex time singularities is performed to verify the fractal structure. The numerical results show the reality of complex time singularities and the fractal structure of singularities on a curve.

Binary sequences with good correlation properties are required for a variety of engineering applications. We previously proposed simple methods to generate binary sequences based on chaotic nonlinear maps. In this paper, statistical properties of chaotic binary sequences generated by Chebyshev maps are discussed. We explicitly evaluate the correlation functions by means of the ensemble–average technique based on the Perron–Frobenius (P–F) operator. As a consequence, we can confirm an important role of the P–F operator in evaluating statistics of chaos by means of the ensemble-average technique.

Numerical studies of reaction–diffusion systems which consist of chaotic oscillators are carried out. The Rössler oscillators are used, which are arranged two–dimensionally and coupled by diffusion. Pacemakers where the average periods of the oscillators are artificially changed are set to produce target patterns. It is found that target patterns emerge from pacemakers and grow up as if they were in a regular oscillatory medium. The wavelength of the pattern can be varied and controlled by changing the parameters (size and frequency) of the pacemaker. The behavior of the coupled system depends on the size of the system and the strength of the pacemaker. When the system size is large, the Poincar return maps show that the behavior of the coupled system is not simple and the orbit falls into a high–dimensional attractor, while for a small system the attractor is rather simple and a one–dimensional map is obtained. Moreover, for appropriate strength of pacemakers and for certain sizes of the systems the oscillations become periodic. It is also found that the largest and local Lyapunov exponents of the system are positive and these values are uniformly distributed over the pattern. The values of the exponents are smaller than that of the uncoupled Rössler oscillator; this is due to the fact that the diffusion reduces the exponents and modifies the form of the attractor. We conclude that the large scale patterns can stably exist in the chaotic medium.

This letter presents the results of an analysis concerning the global, dynamical structure of a second order phase–locked loop (PLL) in the presence of the continuous wave (CW) interference. The invariant manifolds of the PLL equation are focused and analyzed as to how they are extended from the hyperbolic periodic orbits. Using the Melnikov integral which evaluates the distance between the stable manifolds and the unstable manifolds, the transversal intersection of these manifolds is proven to occur under some conditions on the power of the interference and the angular frequency difference between the signal and the interference. Numerical computations were performed to confirm the transversal intersection of the system–generated invariant manifolds for a practical set of parameters.

In this paper we propose a formal linearization method which permits us to transform nonlinear systems into linear systems by means of the Chebyshev interpolation. Nonlinear systems are usually represented by nonlinear differential equations. We introduce a linearizing function that consists of a sequence of the Chebyshev polynomials. The nonlinear equations are approximated by the method of Chebyshev interpolation and linearized with respect to the linearizing function. The excellent characteristics of this method are as follows: high accuracy of the approximation, convenient design, simple operation, easy usage of computer, etc. The coefficients of the resulting linear system are obtained by recurrence formula. The paper also have error bounds of this linearization which show that the accuracy of the approximation by the linearization increases as the order of the Chebyshev polynomials increases. A nonlinear filter is synthesized as an application of this method. Numerical computer experiments show that the proposed method is able to linearize a given nonlinear system properly.

Precise measurements of temperature dependence of the Andreev reflection current for the N–I–S junctions were carried out. Au and Pb were used as N (normal metal) and S (superconducting material), respectively. The experimental results agreed with the analyses based on the Arnold theory.

It is known that homogeneous networks are ones which perform parallel algorithms, and the dynamics of neural networks are applied to practical problems including combinatorial optimization problems. Both homogeneous and neural networks are parallel networks, and are composed of Boolean elements. Although a large number of studies have been made on the applications of homogeneous threshold networks, little is known about the relation of the dynamics of these networks. In this paper, some results about the dynamics, used to find the lengths of periodic and transient sequences, as built by parallel networks including threshold and homogeneous networks are shown. First, we will show that for non–restricted parallel networks, threshold networks which permit only two elements to transit at each step, and homogeneous networks, it is possible to build periodic and transient sequences of almost any lengths. Further, it will be shown that it is possible for triangular threshold networks to build periodic and transient sequences with short lengths only. As well, homogeneous threshold networks also seem to build periodic and transient sequences with short lengths only. Specifically, we will show a sufficient condition for symmetric homogeneous threshold networks to have periodic sequences with the length 1.

We propose and demonstrate an excellent linearly frequency-swept laser diode (LD) for sensing system utilizing frequency-moduleted continuous-wave (FMCW) technique. In order to linearly sweep the optical frequency, we adopt a reference interferometer and an electric phase comparator. The interference beat signal of the reference interferometer is phase-compared with an external reference rectangular signal having a fixed frequency near the interference beat signal frequency by a lock-in amplifier. The error signal from the lock-in amplifier is fed back to the modulating signal of the injection current of the LD. Thus, a phase-locked loop composed of optical and electric circuits can be established, and the beat signal frequency is locked to the frequency of the reference signal. The optical frequency of the LD is, therefore, excellently linearly swept in time. In order to experimentally confirm the linearlity of the proposed method, we apply this light source to the FMCW reflectometry. Resultingly, the improvement of the linearity is estimated to be about 10 dB. And the theoretically limited spatial resolution of the FMCW reflectometry is achieved.

In this letter we present an electronic circuit based on a neural net to compute the discrete Walsh transform. We show both analytically and by simulation that the circuit is guaranteed to settle into the correct values.

The access control method adopted by UNIX is simple, understandable, and useful. However, it is quite possible that unexpected information flows occur when we are cooperating with some group members on UNIX. Introducing notions such as "flow right," "maximal permission" and "minimal umask value", this note proposes a simple method, can be seen as a natural extension of UNIX, to control indirect information flows without losing availability and understandability of UNIX.

In this letter we propose an interpolation technique for low-quality fingerprint images for highly reliable feature extraction. To improve the feature extraction rate, we extract fingerprint features by referring to both the interpolated image obtained by using a directional Laplacian filter and the high-contrast image obtained by using histogram equalization. Experimental results show the applicability of our method.

A novel optoelectronic mesoscopic neural device is proposed. This device operates in a neural manner, involving the electron interference and the laser threshold characteristics. The optical output is a 2–dimensional image, and can also be colored, if the light emitting elements are fabricated to form the picture elements in 3–colors, i.e. R, G, and B. The electron waveguiding in the proposed device is analyzed, on the basis of the analogy between the Schrödinger's equation and the Maxwell's wave equation. The nonlinear neural connection is achieved, as a result of the superposition an the interferences among electron waves transported through different waveguides. The sizes of the critical elements of this device are estimated to be within the reach of the present day technology. This device exceeds the conventional VLSI neurochips by many orders of magnitude, in the number of neurons per unit area, as well as in the speed of operation.

There has been an increasing demand for telecommunication services that satisfy individual users' requirements such as personal telecommunication services and intelligent network services. This demand for advanced telecommunications services is having a great impact on the control architecture and mechanism. In this paper, we propose a new representation of processing power for telecommunications services, using TPS (Transaction Per Second), instead of BHCA, which has been the most commonly used parameter for conventional telephone networks. In developing an IN benchmark, telecommunications services are compared with the TPC-A (Transaction Processing Performance Council-A) benchmark model based on TPS. This benchmark is then used to estimate the requirements for processing power, which, in turn, indicate the necessity for a distributed control. A layered architecture, compatible architecture, and control mechanism for user services are employed to adapt to the distributed network environment.

In this paper, the influences of the cross-sectional deformation on the coplanar waveguide (CPW) characteristics for the use of Ti: LiNbO3optical modulator are presented based on quasi-static analysis. In particular, the influences of the changes in the thickness of Ti: LiNbO3 substrate and the cross-sectional shape of electrodes are studied in detail by using the finite element method proposed previously. As a result, it is found that the propagation characteristics of the dominant mode change significantly with the thickness of LiNbO3 substrate when it is less than 100 µm. It is also shown that an inverted trapezoidal deformation of the electrode cross section is promising because a wider electrode gap and thinner electrodes are available in the design of optical modulators.

We prove that the maximum likelihood estimator for estimating 3-D motion from noisy optical flow is not optimal", i.e., there is an unbiased estimator whose covariance matrix is smaller than that of the maximum likelihood estimator when a Gaussian noise distribution is assumed for a sufficiently large number of observed points. Since Gaussian assumption for the noise is given, the maximum likelihood estimator minimizes the mean square error of the observed optical flow. Though the maximum likehood estimator's covariance matrix usually reaches the Cramér-Rao lower bound in many statistical problems when the number of observed points is infinitely large, we show that the maximum likelihood estimator's covariance matrix does not reach the Cramér-Rao lower bound for the estimation of 3-D motion from noisy optical flow under such conditions. We formulate a superior estimator, whose covariance matrix is smaller than that of the maximum likelihood estimator, when the variance of the Gaussian noise is not very small.