Soliton transmission control has already proved to be an outstanding technique and enable a soliton to be transmit over one million kilometers. This technique is not only applicable to vast distances but also to shorter distances where the amplifier spacing is greater than that of conventional systems. A combination of time and frequency domain control eliminates the noise accumulation and timing jitter caused by soliton interaction and the Gordon-Haus effect, that are the main impediments to extending the transmission distance. In this paper we describe soliton control techniques applied over an astronomical transmission distance of 180,000,000 km, and to a terrestrial system with a large amplifier spacing of up to 100km. We also report the possibility of realizing a sub-tera bit/s soliton transmission system operating over more than 5,000 km in which the soliton self-frequency shift is controlled with the soliton control technique.

We measured the longitudinal electric field of the electrical pulses with a rise time less than 1 ps on a coplanar transmission line by electrooptic sampling. The longitudinal component is a sharp pulse and is only observed at the wavefront. The transverse component has no overshoot or undershoot. The mixing of longitudinal component to the transverse component is discussed for C3v crystals whose electrooptic coefficient is large. We developed the method to estimate the longitudinal and the transverse component of the electric field by the polarization control of a probe light without changing the probe configuration which affects sensitivity severely. The waveform and the rise time of the transverse electric field were eatimated, for the first time, by subtracting the influence of the longitudinal component.

We have fabricated a new analog memory with a floating gate as a key component to store synaptic weights for integrated artificial neural networks. The new analog memory comprises a tunnel junction (poly-Si/poly-si oxide/poly-Si sandwich structure), a thin-film transistor, two capacitors, and a floating gate MOSFET. The diffusion of the charges injected through the tunnel junction is controlled by switching operation of the thin-film transistor, and we refer to the new analog memory as switched diffusion analog memory (SDAM). The obtained characteristics of SDAM are a fast switching speed and an improved linearity between the potential of the floating gate and the number of pulse inputs. SDAM can be used in a neural network in which write/erase and read operations are performed simultaneously.

Most current management systems employ graphic-user-interface displays to visualize the networks being managed. Some networks are so large that it is difficult to display all network elements in a single window alone, and therefore, the hierarchical multi-window style presentation is commonly used. This form of presentation has disadvantages, however, including the fact that window manipulations are complex. Our approach (bifocal network visualization) is able to display both the context and any detail of a network within a single window, and overcomes the disadvantages of hierarchical multi-window presentation. We implemented this bifocal network visualization on a workstation using a frame buffer memory called DUALQUEST that is able to generate images in real-time and is simple to operate. This paper describes bifocal network visualization and its implementation. Furthermore, we present an experiment to compare our interface with conventional hierarchical multi-window presentation.

Zero-pronouns and overt pronouns occur frequently in Japanese text. These must be interpreted by recognizing their antecedents to properly understand' a piece of discourse. The notion of centering" has been used to help in the interpretation process for intersentential anaphors. This is based on the premise that in a piece of discourse, some members have a greater amount of attention put on it than other members. In Japanese, the zero-pronoun is said to have the greatest amount of attention put on it. But, when there are more than one zero-pronoun in a sentence, only one of them would be accountable using centering. Overt pronouns and any other zero-pronouns may as well have appeared as ordinary' noun phrases. In this paper, the notion of centering has been extended so that these can also be interpreted. Basically, zero-pronouns and overt pronouns are treated as being more centered" in the discourse than other ordinary' noun phrases. They are put in an ordered list called the Center List. Any other noun phrases appearing in a sentence are put in another list called the Possible Center List. Noun phrases within both lists are ordered according to their degrees of salience. To see the effect of our approach, it was implemented in a simple system with minimal constraints and evaluated. The result showed that when the antecedent is in either the Center List or the Possible Center List, 80% of all zero-pronouns and overt pronouns were properly interpreted.

Ultrashort pulsed-beam propagation in a Kerr-type bulk medium is studied theoretically through classical and quantum field solutions of a higher-order nonlinear Schrödinger equation, which is valid for transversely localized femtosecond pulses in an anomalous dispersion regime. Quantum-mechanical stability analysis via a Hartree approximation to interacting bosons shows that within a certain range of a parameter the solitary wave could be stabilized even in the three-dimensional transverse space-time. This feature admits of an exotic route to multidimensional solitons.

We describe an application of InGaAs/AlGaAs VCSELs to multiple wavelength light source for optical interconnection. A flip-chip bonding technique is used to integrate the VCSELs lasing at different wavelengths. The integrated VCSELs of different wavelengths are individually grown and processed, so that one can optimize the device characteristics and the wavelength separation or distribution for multiple wavelength interconnection systems. A 9-wavelength VCSEL array with a wavelength separation of 5 nm has been successfully fabricated.

This paper proposes a multi-fisheye distortion method which can show a large-scale telecommunication network in a single window on the display of a workstation or personal computer. This distortion method has three advantages over the conventional single-fisheye distortion method. First, the focus area is magnified smoothly by the fisheye distortion method, and the peripheral area coordinates are calculated linearly to avoid unnecessary distortion. Second, multiple focus areas are magnified smoothly by using an average of the coordinates calculated for the individual focuses. Third, the scale of unnecessary areas is reduced to provide sufficient space for magnification. The effectiveness of this method is demonstrated by applying to the display of large-scale networks. The effect of the resulting network map distortion on the user is tested by a subjective evaluation experiment.

Feasibility of 20 Gbit/s single channel transoceanic soliton transmission systems with a simple EDFA repeaters configuration has been studied. Both a simple and versatile soliton pulse generator and a polarization insensitive optical demultiplexer, which can provide a almost square shape optical gate with duration of full bit time period, have been proposed and demonstrated by using sinusoidally modulated electroabsorption modulators. The optical time-division multiplexing/demultiplexing scheme using the optical demultiplexer results in drastic improvement of bit error rate characteristics. We have experimentally confirmed that the use of alternating-amplitude solitons is an efficient way to mitigate not only soliton-soliton interaction but also Gordon-Haus timing jitter constraints in multi-ten Gbit/s soliton transmission. Timing jitter reduction using relatively wide band optical filter bas been investigated in 20 Gbit/s loop experiments and single-carrier, single-polarization 20 Gbit/s soliton data transmission over 11500 km with bit error rate of below 10-9 has been experimentally demonstrated, using the modulator-based soliton source, the optical demultiplexer, the alternation-amplitude solitons, and wide-band optical filters. Obtained 230 Tbit/skm transmission capacity shows the feasibility of 20 Gbit/s single channel soliton transoceanic systems using fully practical technologies.

A negation-limited circuit is a combinational circuit which includes at most [log(n1)] NOT gates. We show a relationship between the size of negation-limited circuits computing clique functions and the number of NOT gates in the circuits.

For an application to the optical signal processing devices, we propose the optical X coupler which consists of two bending waveguides and a nonlinear dielectric region. To analyze this structure accurately we utilized the iterative finite difference beam propagation method (iterative FD-BPM). In this paper the formulation of the iterative FD-BPM for one wave and two waves cases are presented, respectively. We investigate following two cases. First, we consider the case that the light is launched into one of the input ports. We calculate the evolutions of the field amplitude and the transmission characteristics for the input power. Second, we consider the case that the signal light with the constant power is launched into one of the input ports and that the control light with the wavelength different from that of the signal light is launched into another input port. We calculate the evolutions of the field amplitude and the transmission characteristics of the signal light for the power of control light. As a result of the analysis, we show that all-optical switching operation is possible in the proposed structure.

In this study, after focussing on an energy (or intensity) scaled variable of acoustic systems, first, a new regression analysis method is theoretically proposed by introducing a multiplicative noise model suitable to the positively scaled stocastic system. Then, the effectiveness of the proposed method is confirmed experimentally by applying it to the actual acoustic data.

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.

This paper proposes an electronic retail payment system to provide flexible and efficient funds transfers with adequate security, reliability, circulativity, and anonymity even in large-scale applications. Funds are represented by a portable intelligent device called a card issued by a supervising organization, the system provider. Funds can be transferred from a card to another at an intelligent terminal called a mediator. To update the balance of each card, two digital signatures are generated by a three-party protocol conducted by the cards and mediator, and are encoded and appended to a write-once separate memory in the card. Old signatures are simultaneously nullified. Through a wired or radio non-real-time link, the generated signatures are periodically reported to the system provider to systemically manage possible abuses.

An efficient algorithm is presented for finding all solutions of piecewise-linear resistive circuits containing sophisticated transistor models such as the Gummel-Poon model or the Shichman-Hodges model. When a circuit contains these nonseparable models, the hybrid equation describing the circuit takes a special structure termed pairwise-separability (or tuplewise-separability). This structure is effectively exploited in the new algorithm. A numerical example is given, and it is shown that all solutions are computed very rapidly.

In this paper, chaos synchronization in coupled discrete-time dynamical systems is studied. Computer results display the interesting synchronization behaviors in the mutually coupled systems. As possible applications of chaos synchronization, parameter estimations and secure communications are proposed. Furthermore, a modified OGY method is given, which converts a chaotic motion into a periodic motion.

The current state of development of the television broadcasting system of the future is described with regard to LSI development. It is no need to say that television broadcasting systems are very huge and require a large number of inexpensive LSI's. Hi-Vision broadcasting has already been started in Japan. In the United States, a digital terrestrial broadcasting system (ATV) will be standardized in the near future. On the other hand, the situation in Europe remains unclear but MPEG-2 is now in the stage of system finarizing. We also hear much about "multimedia" but the concept of multimedia broadcasting still requires a lot of time to be translated into reality. Some important current technical topics and related basic technologies are also described in this paper. They include DCT, Hybrid DCT coding, error correcting coding, coded modulation, and improvement of the MUSE system. Finally, the discussion considers the relationship between system development and VLSI technology and the importance of mutual understanding between VLSI engineers and system designers. Some possible requirements for VLSI development are also stated.

The networked reality is defined to be the virtual reality used in networks and using networks. The paper describes several levels of the networked reality and their applications.

Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper, we propose a modified genetic channel router. We adopt the compatible crossover operator and newly designed compatible mutation operator in order to search solution space more effectively, where vertical constraints are integrated. By carefully selected fitness function forms and optimized genetic parameters, the current version speeds up benchmarks on average about 5.83 times faster than that of our previous version. Moreover the total convergence to optimal solutions for benchmarks can be always obtained.

We present a new multi-layer over-the-cell channel router for standard cell layout design using simulated annealing. This new approach, STANZA-M consists of two key features. The first key feature of our router is a new scheme for simulated annealing in which we use a cost function to evaluate both the total net-length and the channel heights, and an effective simulated annealing process by a limited range to obtain an optimal chnnel wiring in practical time. The second feature of our router is a basic layer assignment procedure in which we assign all horizontal wiring inside a channel to feasible layers by considering the height of channel including cell region with a one dimensional channel compaction process. We implemented our three-layer cannel router in C language on a Solbourne Series 5 Work Station (22 MIPS). Experimental results for benchmarks such as Deutsch's Difficult Example and MCNC's PRIMARY1 channel routing problems indicate that STANZA-M can achieve superior results compared to the conventional routers, and the process times are very fast despite the use of simulated annealing.