The improved point-matching method with Mathieu function expansion for the accurate analysis of the W-type elliptical fiber with layers of any ellipticity is proposed. Results of our method are reliable, because we expand the electromagnetic fields by a sum of the complete set of wave functions in each layer of the fiber. Numerical results are presented for the highly-birefringent fibers with a hollow layer outside an elliptical core. It is found that such fibers can realize the large value of the modal birefringence as well as they can be suitable for the single-mode and single-polarization transmission. From the convergence tests, it is confirmed that the relative error of the modal birefringence is less than 0.01%. The comparison of our results with those by previously reported method is presented. The proposed method can be extended for analysis of the elliptical-core fibers with hollow pits and electromagnetic scattering by targets of the complex elliptical geometry.

In this paper, we propose a new class of ID-based non-interactive key sharing scheme with a trusted center which generate a common key on the basis of a linear combination of the center secrets. We also discuss the security of the proposed schemes, and show that the proposed schemes prevent the conventional collusion attack, by adding another random integers unique to each user, on the secret vector that is assigned to the user. Furthermore, we present a new type of a statistical collusion attack which is more suitable for the proposed schemes. We also present the lower bound of the threshold of the statistical collusion attack on the proposed schemes. The proposed schemes can be easily implemented compared with other schemes as they require only computing of the inner product of two vectors over finite ring (including finite field) and an Euclidean quotient, for generating the common key. Our proposed schemes can be regarded as modified versions of the Blom's original scheme. However our proposed schemes are secure against our new type of the attack, as well as the collusion attack based on the solving of the linear equations, although Blom's scheme is insecure against both of these collusion attacks.

Memory type polymer dispersed liquid crystal (PDLC) can be applied to a thermal addressing display device cell. Making use of its easy fabrication of large area display using flexible film substrate, the PDLC film can be used as reusable paper for direct-view mode display. In this study, memory type PDLC cells are prepared with an aluminum reflector deposited onto one side of the substrate and the reflection property in the PDLC cell with the reflector is clarified and compared to that without the reflector in the off-, on- and memory-states. The increase of contrast ratio and the decrease of driving voltage can be concurrently realized by decreasing the cell thickness by attaching the reflector. In addition, the reflected light in the off-state is bright and colorless due to the reflector, as compared with the weak, bluish reflected light in the cell without the reflector. Reflected light in the on-state and the memory-state are tinged with blue.

A near-ring is an extended notion of a usual ring. Therefore a ring is a near-ring, but the converse does not necessarily hold. We investigate in this paper one-way functions associated with finite near-rings, and show that if there exists a one-way group homomorphism, there exists a one-way non-ring near-ring homomorphism (Theorem 1); if there exists a one-way ring homomorphism (Theorem 2). Further, we introduce a discrete logarithm problem over a finite near-ring, and show that the integer factoring is probabilistic polynomial-time Turing equivalent to a modified version of this problem (Theorem 3). Theorem 1 implies that under some standard cryptographic assumption, there is an affirmative but trivial solution to the extended version of the open question: Is there an encryption function f such that both f(x+y) and f(xy) are efficiently computed from given f(x) and f(y) ?

This paper compares three typical system-sharing configurations for FTTH networks that provide narrowband and video distribution services and proposes a remote node locating strategy for each configuration. Two new evaluation factors, required land space and service provisioning effort, are included in the calculation, in addition to facility cost and maintenance effort. By considering these factors together, the total network cost is calculated and the sensitivity to the number of remote nodes is evaluated. Finally, the most economical system-sharing configuration is identified on the basis of the evaluations for two typical service areas in Japan, for both present and future cost environments.

A simple solution for the right-angle H-plane waveguide double bend is obtained in analytic series form. The simultaneous equations are solved to obtain the transmission and reflection coefficients in fast convergent series forms. The numerical computations are performed to show the behaviors of the transmission coefficient versus frequency.

Electromagnetic plane wave scattering by a loaded trough on a ground plane has been analyzed by Kobayashi and Nomura's method. The field in each region is expressed first in terms of appropriate eigen functions, whose excitation coefficients are determined by the continuity condition across the aperture of the trough. Simple far field expression which is suitable for numerical calculation for small aperture cases has been derived. Scattering far field patterns and radar cross section are calculated and compared with those obtained by other methods. Good agreements have been observed for all incident angles.

A 3.2 GHz, 50 mW, 1 V, GaAs clock pulse generator (CG) based on a phase-locked loop (PLL) circuit has been designed for use as an on-chip clock generator in future high speed processor LSIs. 0.5 µm GaAs MESFET and DCFL circuit technologies have been used for the CG, which consists of 224 MESFETs. An "enhanced charge-up current" inverter has been specially designed for a low power and high speed voltage controlled oscillator (VCO). In this new inverter, a voltage controlled dMESFET is combined in parallel with the load dMESFET of a conventional DCFL inverter. This voltage controlled dMESFET produces an additional charge-up current resulting in the new VCO obtaining a much higher oscillation frequency than that of a ring oscillator produced with a conventional inverter. With a single 1 V power supply (Vdd), SPICE calculation results showed that the VCO tuning range was 2.25 GHz to 3.65 GHz and that the average VCO gain was approximately 1.4 GHz/V in the range of a control voltage (Vc) from 0 to 1 V. Simulation also indicated that at a Vdd of 1 V the CG locked on a 50 MHz external clock and generated a 3.2 GHz internal clock (=50 MHz64). The jitter and power dissipation of the CG at 3.2 GHz oscillation and a Vdd of 1 V were less than 8.75 psec and 50 mW, respectively. The typical lock range was 2.90 GHz to 3.59 GHz which corresponded to a pull-in range of 45.3 MHz to 56.2 MHz.

This paper describes a new clustering approach for VLSI placement, which is based on a fractal dimension analysis for the topological structure of modules in a logic diagram. A distinctive feature of this approach is that a measure of the 'fractal dimension' has been introduced into a logic diagram in such a way that the clustering of modules is iterated while the fractal dimension among clustered modules is retained in a prescribed range. A part of experimental results is also shown, which demonstrates that our clustering approach raises the placement performance much higher than the conventional clustering methods.

A new approach of data clustering which is capable of detecting linked or crossed clusters, is proposed. In conventional clustering approaches, it is a hard work to separate linked or crossed clusters if the cluster prototypes are difficult to be represented by a mathematical formula. In this paper, we extract the force information from data points using the concept of psychological potential field, and utilize the information to measure the similarity between data points. Through several experiments, the force shows its effectiveness in diiscriminating different clusters even if they are linked or corssed.

We present a novel algorithm to reconstruct the refractive-index profile of a circularly symmetric object from measurements of the electromagnetic field scattered when the object is illuminated by a plane wave. The reconstruction algorithm is besed on an iterative procedure of matching the scattered field calculated from a certain refractive-index distribution with the measured scattered field on the boundary of the object. In order to estimate the convergence of the reconstruction, the mean square error between the calculated and measured scattered fields is introduced. It is shown through reconstructing several examples of lossy dielectric cylinders that the algorithm is quite stable and is applicable to high-contrasty models in situations where the Born approximation is not valid.

An emitter–coupled pair with a dynamic bias current and a source–coupled pair with a dynamic bias current are proposed as an exponential–law element and a square–law element that operate as a floating bipolar junction transistor (BJT) and a floating MOS field–effect transistor (MOSFET). In bipolar technology, a hyperbolic sine function circuit and a hyperbolic cosine function circuit are easily obtained by subtracting and summing the output currents of two symmetrical exponential–law elements with positive and negative input signals. In the same manner, an operational transconductance amplifier (OTA) and a squaring circuit are obtained by subtracting and summing the output currents of two symmetrical square-law elements with positive and negative input signals in CMOS technology. The proposed OTA and squaring circuit possess the widest input voltage range ever reported.

A method is presented for reconstructing the surface profile of a perfectly conducting rough surface boundary from the measurements of the scattered far-field. The proposed inversion algorithm is based on the use of the Kirchhoff approximation and in order to determine the surface profile, the Fletcher-Powell optimization procedure is applied. A number of numerical results illustrating the method are presented.

A three-dimensional analysis of Whispering-Gallery modes (W. G. modes) in a coaxial dielectric resonator is proposed and presented. The coaxial dielectric resonator is constructed from a lossy dielectric disk and ring which have diameters of several tens times as large as wavelength. Eigenvalue equations of the W. G. modes are derived rigorously from field expressions and boundary conditions. The resonant frequencies, unloaded Q values and field distributions are calculated numerically from the eigenvalue equations. These calculated results are in good agreement with experimental ones for an X band model. As a result, it is shown that a considerable quantity of modal energy can be confined in a loss-less gap between the disk and ring, and then the unloaded Q value is higher than that of a conventional dielectric disk and ring resonator.

By addressing design requirements for multicast ATM switching, this paper attempts to provide an integrated view of modular and expandable switch architectures suitable for both unicast and multicast switching for future B-ISDNs. Several large and modular multicast ATM switching architectures are discussed, each of which handles different traffic situations. These architectures consist of multiple shared-buffer copy network modules of adequate size suitable for fabrication on a single chip, and small output memory switch modules. A new modular link-grouped multistage interconnection network is proposed for interconnecting copy network modules and memory switch modules, so that future large multicast ATM switching networks can be built in a modular fashion. The described modular architectures can significantly facilitate signal synchronization in large-scale switching networks.

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.

With advances in the speed, bandwidth and reliability of telecommunications networks and in the performance of workstations, distributed processing has become widespread. Information sharing among distributed nodes and its mutual exclusion are of great importance for efficient distributed processing. This paper systematizes and quantitizes a shared memory called Data-Cyclic Shared Memory (DCSM) from the viewpoints of memory organization and access mode. In DCSM, the propagation delay of transmission lines and the data relaying delay in each node are used for information storage, and memory information encapsuled in the form of "memory cells" circulates infinitely in a logical ring type network. The distinctive feature of DCSM, in addition to the way data is stored, is that data and the access control are completely distributed, which contrasts with existing memory where both are centralized. Therefore, there are no performance bottlenecks caused by concentrating memory access. Distributed Shared Memory (DSM), which has a scheme similar to DCSM's, has also been proposed for distributed environments. In DSM, the data is also distributed but the control for accessing each data is centralized. From the viewpoints of memory organization and the access method, DCSM is very flexible. For instance, word length can be spatially varied by defining data size at each address, and each node can be equipped with mechanisms for special functions such as the content address specification and asynchronous report of change in contents. Because of this flexibility, it can be called a "software-defined memory." The analysis also reveals that DCSM has the disadvantages of large access delay and small memory capacity. The capacity can be enlarged by inserting FIFO type queues into the circulation network, and the delay can be shortened by circulating replicas of original memory cells. However, there is a trade off between the maximal capacity and the mean access time. DCSM has many potential applications, such as in the mutual exclusion control of distributed resources.

We describe the characteristics of scattering and diffraction of plane E-waves by a lossy dielectric elliptic cylinder. The computational programs for calculating the analytic solutions for the diffraction of a lossy dielectric elliptic cylinder can be achieved. From the calculated results of the backscattering cross section (BSCS) (usually the radar cross section: RCS) and the forward-scattering cross section (FSCS) due to the cross-sectional shape and complex dielectric constant of the elliptic cylinder, the features of the BSCS and FSCS can be clarified as follows. (1) There is a cross-sectional shape of the cylinder which results in a minimum BSCS with a complex dielectric constant of the cylinder. (2) The BSCS and FSCS of the lossy dielectric scatterer approach zero as the scatterer approaches a strip. This result means that no material composing such a strip exists, and the features are very different from those in a perfectly conducting strip. (3) The influence of conductivity, σ, of the cylinder on a scattered wave is small for the relative dielectric constant of εr6. (4) The total scattering cross section of the lossy dielectric elliptic cylinder which causes the minimum BSCS is not small. Hence, it may be considered that the minimum BSCS is determined mainly by interference based on the cross-sectional shape and complex dielectric constant of cylinder, and is not caused by incident wave absorption due to the lossy dielectric.

This paper presents a new numerical procedure for solving the scattering wave by the moving surface. Recently, the author and her colleagues have proposed a novel numerical procedure of grid generation having a coordinate line coincident with an arbitrarily shaped moving boundary. The time dependent curvilinear coordinate system which coincides with a contour of moving boundary in a physical region is transformed into fixed rectangular coordinate system. The simple form for the transformation is made possible to choose the function between the physical region and the rectangular computational region. The FD-TD algorithm is exactly solved in this fixed rectangular coordinate system. In this paper, for the application of the FD-TD algorithm to the body fitted grid generation with moving boundary, the stability criterion of FD-TD algorithm for the body fitted grid generation with moving boundary in three dimensions is derived. The stability criterion is shown an upper bound for time step assuring stable numerical solutions. The study of scattering of electromagnetic and acoustic wave from a moving or a rotating body is very important for electromagnetic probing of moving body. The problem has been investigated in the past by numerous authors. One of them is solved by FD-TD method, where the linear interpolation is introduced for the movement. By using the presented transformation technique where time component is added to the grid generation, the time depending coordinate system can be transformed into fixed rectangular coordinate system. Then the problems are directly solved by FD-TD method in the transformed coordinate system. To verify this numemical technique, scattered field is evaluated in the case when a plane wave is normally incident on a moving perfectly conducting flat plate. The numerical results are compared with the exact ones and excellent agreement between them is obtained.

Electromechanical devices such as relays, switches, connectors and printed wiring boards have shown quick growth along with remarkable progress of electronic products in a recent few decades. For the present, outstanding tasks common to these devices are further downsizing, higher density and broading of bandwidth, on the assumption of keeping high performance and high reliability. These tasks are realized by part production improvement for higher precision and automatic assemblies, development of constituent materials and development of breakthrough structural technologies such as a surface mount technology and an active assembly ferrule technology in optical connectors and so on. In this paper, the technical trends as well as the motive technologies are overviewed for each device.