Multimedia communication services are being made available with the advent of broadband optical fiber networks. As many different services will be accommodated in such networks, network survivability has been recognized to be a crucial concern. In this paper, we propose a new restoration algorithm for ATM networks providing multimedia services. Our proposed restoration algorithm adopts the message bundling scheme of the Multi-Destination Flooding (MDF) algorithm which was previously proposed for STM-based networks to handle catastrophic failures such as multiple link and node failures. Virtual Paths (VP) with the same communication speed are bundled and Operation Administration and Maintenance (OAM) cells are used for communication of restoration messages. In addition, the following modifications are made on the original MDF to improve restoration performance. The pre-cancellation scheme is adopted to arbitrate reservation contention to realize high restoration ratio. The dual queue scheme is applied to avoid congestion of restoration messages. Moreover, the connection control scheme for VPI connections is proposed to prevent alternative routes from being misconnected. This paper describes the design concept of our restoration algorithm, processes in each restoration phase, and the performance evaluation by computer simulation.

Any minimum test set (MLTS) for locally exhaustive testing of multiple output combinational circuits (CUTs) has at least 2w test patterns, where w is the maximum number of inputs on which any output depends. In the previous researches, it is clarified that every CUT with up to four outputs has an MLTS with 2w elements. On the other hand, it can be easily shown that every CUT with more than five outputs does not have such an MLTS. It has not been however known whether every CUT with five outputs has such an MLTS or not. In this paper, it is clarified that every CUT with five outputs has such an MLTS. First, some terminologies are introduced as preliminaries. Second, features of 5(w1) dependence matrices of CUTs with five outputs and (w1) inputs are discussed. Third, an equivalence relation between dependence matrices of two CUTs is introduced. The relation means that if it holds and one of the CUTs has an MLTS with 2w elements, then the other CUT also has such an MLTS. Based on the features described above, a theorem is established that there exists a 5w dependence matrix which is equivalent to each of the above 5(w1) matrices. Finally, it is proved by the use of the theorem that every CUT with five outputs has an MLTS with 2 w elements.

A method to design one-dimensional cellular arrays to be used as TPG circuits of BIST is described. The interconnections between cells are not limited to adjacent ones but allowed to some neighbors. Completely regular structures that have full-transition coverages for every k-dimensional subspace of state variables are first shown. Then, almost regular arrays which can operate on maximum cycles are derived based on fast parallel implementations of LFSRs.

We reported that a competitive learning neural network had the ability of self-organization in the classification of questionnaire survey data. In this letter, its self-organized learning was evaluated by means of mutual information. Mutual information may be useful to find efficently the network which can give optimal classification.

In this paper, the computational model of Quasi-Ecosystem that is constructed in the way of bottom up, i.e., that consists of herbivores, carnivores and plants is proposed and the simulation result is shown. The behavior pattern of the model is represented by finite state automata. Simple adaptive behavior of animals was observed in this simulation. This indicates that mutation is effective method for self adaptive behavior and the possibility that the model can be used as a framework for autonomous agents.

We have investigated the Josephson microwave self-radiation and the linewidth from different types of YBa2Cu3Oy(YBCO) grain boundary junctions: natural grain boundary junctions, step-edge junctions and bicrystal junctions. The Josephson self-rediation was directly observed using a total power radiometer receiver with receiving frequencies fREC=1.7-72 GHz. All junctions exhibited microwave self-radiation peaks with intensity of order of 10-12-10-14 W. For step-edge and bicrystal junction, they appeared at a voltage related to the Josephson frequency-voltage relation, V=n(h/2e)f, while for natural grain boundary junctions, the above relation did not hold, suggesting a Josephson medium property. For all types of junctions the observed Josephson linewidth deviated from the theoretical RSJ values due to the extra noise source in the grain boundary junction. The Josephson linewidth decreased with increasing the receiving frequency for all type of junctions. The reduction of Josephson linewidth at higher frequencies indicates that the critical current fluctuations due to a critical current spread at small bias voltages and a crystalline disorientation at the junction boundary generate an additional noise in grain boundary junctions.

A high-speed high-density self-aligned pnp technology for complementary bipolar ULSIs has been developed to achieve high-speed and low-power performance simultaneously. It is fully compatible with the npn process. A low sheet-resistance p+ buried layer and a low sheet-resistance extrinsic n+ polysilicon layer with U-grooved isolation enable the transistor size to be scaled down to about 20 µm2. Current gain of 85 with 4-V collector-emitter breakdown voltage was obtained without any leakage current arising from emitter-base forward tunneling or recombination, which indicates no extrinsic base encroachment problem. A shallow emitter junction depth of 45 nm and narrow base width of 30 nm, obtained by utilizing an optimized retrograded p-well, an arsenic-implanted intrinsic base, and emitter diffusion from BF2-implanted polysilicon, improve the maximum cutoff frequency to 35 GHz. The power dissipation of the pnp pull-down complementary emitter-follower ECL circuit with load capacitances is calculated to be reduced to 20-40% of a conventional ECL circuit.

A self-induced-transparent (SIT) system that takes advantage of morphology dependent resonances (MDR's) in a Mie-sized microsphere doped with a resonant material is proposed. The present system is doubly resonant: one has microscopic origin (the two-level system), while the other has macroscopic origin (the MDR). In this geometry, owing to the feedback action of MDR's, the pulse area can be much expanded, and thus the electric-field amplitude of the incident pulse can be reduced substantially compared with the conventional one-way SIT propagation. Theoretical results that incorporate dephasing due to structural imperfections are shown.

We developed an eye-contact technique using a blazed half-transparent mirror (BHM), which is a micro-HM array arranged on the display surface, to make a compact eye-contact videophone. This paper describes a new BHM structure that eliminates ghosts and improves image quality. In the new BHM, the reflection and transmission areas are separated to exclude ghosts from appearing in the captured image. We evaluated the characteristics of the captured and displayed images. The results show that the contrast ratio of the captured image and the brightness of both captured and displayed images are much better than with the previous BHM.

The polarization dependence of femtosecond soliton-soliton interactions is investigated in detail. When the polarization direction of two solitons is orthogonal, the soliton interaction can be reduced in comparison to that for parallel polarization. The soliton self-frequency shift (SSFS) is still observed even in the orthogonal condition, but the quantity of the SSFS is much smaller than in the parallel condition. A stronger soliton interaction is observed between two solitons in an in-phase condition, than in an out-of-phase condition. The largest SSFS occurs in-phase with parallel polarization. The polarization dependence of femtosecond soliton interaction in a distributed erbium-doped fiber amplifier (DEDFA) is also investigated. It is shown that when the optical gain of the DEDFA is given adiabatically, the input pulse separation at which the first soliton occurs is less with orthogonal polarization. This is because the soliton pulse width is reduced due to the adiabatic soliton narrowing caused by the optical amplification.

Self-modelocking of Ti:sapphire laser has obtained with less than 2 W of argon-ion laser pumping. Two independent lasers with 36 fsec and 63 fsec in pulse duration were operated by a 6 W pump laser. In the low-threshold lasers, not only an ordinary mode-locking but also a double-pulse mode-locking, where two pulses circulating in the cavity, was stable.

A new approach to implement queues for controlling ATM switch LSI is presented. In many conventional architecture, external FIFOs are provided for each output link and used to manage the address of the buffer in an ATM switch. We reduce the number of FIFOs by using a self-timed queue with a search circuit that finds the earliest entry for each output link. Using this architecture, number of the FIFOs is reduced to 1/N, where N is the switch size. Delay priority and multicasting can be supported without doubling the number of the queues. This new queue can also be utilized as an ATM switch by itself. Evaluation chip was fabricated using 0.5-µm CMOS process technology. Inter-stage transfer speed over 500 MHz and cycle time over 125 MHz was obtained. This performance is enough for a 622-Mbps 1616 ATM Switch.

Fractal image coding using iterated transformations compresses image data by exploiting the self–similarity of an image. Its compression performance has already been discussed in [2] and several other papers. However the relation between the performance and the self–similarity remains unclear. In this paper, we evaluate fractal coding from the perspective of this relationship.

This paper describes small AlGaAs/GaAs HBT's for low-power and high-speed integrated circuits. The device fabrication is based on a new bridged base electrode technology that permits emitter width to be defined down to 1 µm. The new technology features oxygen-ion implantation for emitter-base junction isolation and zinc diffusion for extrinsic base formation. The oxygen-ion implanted emitter-base junction edge has been shown to provide a periphery recombination current much lower than that for the previous proton implanted edgs, the result being a much higher current gain particularly in small devices. The zinc diffusion offers high device yield and good uniformity in device characteristics even for a very thin (0.04 µm) base structure. An HBT with emitter dimensions of 12.4 µm2 yields an fT of 103 GHz and an fmax of 62 GHz, demonstrating that the new technology has a significant advantage in reducing the parasitic elements of small devices. Fabricated one-by-eight static frequency dividers and one-by-four/one-by-five two-modulus prescalers operate at frequencies over 10 GHz. The emitters of HBT's used in the divider are 12.4 µm2 in size, which is the smallest ever reported for AlGaAs/GaAs HBT IC's. These results indicate that the bridged base electrode technology is promising for developing a variety of high-speed HBT IC's.

This paper describes highly parallel analog image coding and decoding by cellular neural networks (CNNs). The communication system in which the coder (C-) and decoder (D-) CNNs are embedded consists of a differential transmitter with an internal receiver model in the feedback loop. The C-CNN encodes the image through two cascaded techniques: structural compression and halftoning. The D-CNN decodes the received data through a reconstruction process, which includes a dynamic current distribution, so that the original input to the C-CNN can be recognized. The halftoning serves as a dynamic quantization to convert each pixel to a binary value depending on the neighboring values. We approach halftoning by the minimization of error energy between the original gray image and reconstructed halftone image, and the structural compression from the viewpoints of topological and regularization theories. All dynamics are described by CNN state equations. Both the proposed coding and decoding algorithms use only local image information in a space inveriant manner, therefore errors are distributed evenly and will not introduce the blocking effects found in DCT-based coding methods. In the future, the use of parallel inputs from on-chip photodetectors would allow direct dynamic quantization and compression of image sequences without the use of multiple bit analog-to-digital converters. To validate our theory, a simulation has been performed by using the relaxation method on an 150 frame image sequence. Each input image was 256256 pixels whth 8 bits per pixel. The simulated fixed compression rate, not including the Huffman coding, was about 1/16 with a PSNR of 31[dB]35[dB].

Recent achievements in low-voltage and low-power circuit techniques are reported in this paper. DC current in low-voltage CMOS circuits stemming from the subthreshold current in MOS transistors, is effectively reduced by applying switched-power-line schemes. The AC current charging the capacitance in DRAM memory arrays is reduced by a partial activation of array blocks during the active mode and by a charge recycle during the refresh mode. A very-low-power reference-voltage generator is also reported to control the internal chip voltage precisely. These techniques will open the way to using giga-scale LSIs in battery-operated portable equipment.

An asynchronous spread spectrum (SS) modem for 2.4-GHz wireless LAN has been implemented using an efficient ZnO-SiO2-Si surface acoustic wave (SAW) convolver. The design of the highly efficient SAW convolver was developed at Tohoku University and commercially manufactured by Clarion Co., Japan. The modem can operate under full-duplex transmission in the same frequency range of the 2.4-GHz SS band. The SS modem is based on a direct-sequence/code-shift-keying (DS/CSK) method for the modulation. Pseudo-noise (PN) codes are chosen from a preferred pair of 127-chip m-sequences and the code rate is 14MHz. The asynchronous demodulation is simply realized utilizing the coherent correlation characteristics of the SAW convolver. Under full-duplex transmission, the self-jamming caused by a transmitted signal in the modem itself is effectively reduced by an RF isolator and the SS processing gain. The implemented modem has been tested using a coaxial cable with attenuator. A bit error rate of 10-6 under full-duplex transmission is observed at 78.3dB of a desired to undesired signal ratio. The effective range is estimated on the basis of two-path propagation model. From self-jamming rejection of 78.3dB, the effective range under real-time full-duplex is estimated to be about 200m.

An improvement of Q evaluation is discussed. The Resonance Curve Area method was confirmed to give a deviation in the order of 6104. The result was three times more accurate than the widely known Q evaluating method which utilizes the cursor function installed in a network analyzer. A discussion is also made on the physical validity of the RCA method. It is shown that the application of the RCA method improves the accuracy of the cavity perturbation method. Actual measurements have shown that the deviation of dielectric constant is less than 1% and that of the loss tangent is less than 3%, in the order of 104. The accuracy of the RCA method was estimated to be three times that of the conventional cavity perturbation technique. The consistency of the perturbation with other methods has also confirmed. The accuracy comparison to more accurate formulae derived from a rigorous solution have shown that the difference is sufficiently small.

For the study of the biological effects of ELF (Extremely Low Frequency) electric fields, the perception mechanism of ELF electric fields was analyzed. When a human body is exposed to an electric field, the hair on the body surface moves due to the electric force exerted on the hair. In theoretical analysis, it was shown that the force is approximately proportional to the dielectric constant of hair and the spatial gradient of the square of the electric field at the hair. The dielectric constant of hair was measured with different temperatures and humidities of the surrounding air. A technique was developed to estimate the electric force exerted on a hair during the field exposure. After experiments with model hair, the technique was applied to a body hair of a living human being. It was found that the force increased with field strength and relative humidity. The variations of the force agreed well with those expected from the theoretical analysis and the measurement of hair dielectric constants. These results explain the cause of the reported variation in the threshold of biological effects of an electric field. The results will help to establish a practical safety standard for the held exposure.

A pseudoinverse rule, one of major rule to determine a weight matrix for associative memory, has large capacity comparing with other determining rules. However, it is wellknown that the rule has small domains of attraction of memory vectors on account of many spurious states. In this paper, we try to improve the problem by means of subtracting a constant from all diagonal elements of a weight matrix. By this method, many spurious states disappear and eigenvectors with negative eigenvalues are introduced for the orthocomplement of the subspace spanned by memory vectors. This method can be applied to two types of networks: binary network and analog network. Some computer simulations are performed for both two models. The results of the simulations show our improvement is effective to extend error correcting ability for both networks.