The encoding of high quality and super high definition images requires new approaches to the coding problem. The nature of such images and the applications in which they are used prohibits the introduction of perceptible degradation by the coding process. In this paper, we discuss techniques for the perceptually transparent coding of images. Although technically lossy methods, images encoded and reconstructed using these techniques appear identical to the original images. The reconstructed images can be postprocessed (e.g., enhanced via anisotropic filtering), due to the absence of structured errors, commonly introduced by conventional lossy methods. The compression, ratios obtained are substantially higher than those achieved using lossless means.

Threre are two types of nonlinear associative silicon retinas. One is a sparse Hopfield type neural network which is called a H-type retina and the other is its dual network which is called a DH-type retina. The input information sequences of H-type and HD-type retinas are given by nodes and links as voltages and currents respectively. The error correcting capacity (minimum basin of attraction) of H-type and DH-type retinas is decided by the minimum numbers of links of cutset and loop respectively. The operation principle of the regeneration is based on the voltage or current distribution of the neural field. The most important nonlinear operation in the retinas is a dynamic quantization to decide the binary value of each neuron output from the neighbor value. Also, the edge is emphasized by a line-process. The rates of compression of H-type and DH-type retinas used in the simulation are 1/8 and (2/3) (1/8) respectively, where 2/3 and 1/8 mean rates of the structural and binarizational compression respectively. We could have interesting and significant simulation results enough to make a chip.

This paper introduces a modeling of the human rotation invariant recognition mechanism at the neural level. In the model, mechanisms of memory search and mental rotation are realized in the process of minimizing the energy of a bi-directional connection network. The thrust of the paper is to explain temporal mental activities such as successive memory retrievals and continuous mental rotation in terms of state transitions of collective neurons based on nonequilibrium dynamics. We conclude that regularities emerging in the dynamics of intermittent chaos lead the recognition process in a structural and meaningful way.

A new error rate formula for narrowband Differential Quaternary Phase Shift Keyed system in a Rayleigh fading channel is obtained in closed-form. The formula predicts a non-zero error probability for noiseless reception. As predicted, the computed error rates approach some constant or floor values as the signal-to-noise ratio is increased beyond a certain limit. In the presence of various Doppler frequency shifts, an IF filter bandwidth of about one times the symbol rate is found to lead to a minimum error probability prior to the appearence of the error rate floor.

Topographic maps begin to be recognized as one of the major computational structures underlying neural computation in the brain. They provide dimension-reducing projections between feature spaces that seem to be established and maintained under the participation of selforganizing, adaptive processes. In this contribution, we investigate how well the structure of such maps can be replicated by simple adaptive processes of the kind proposed by Kohonen. We will particularly address the important issue, how the dimensionality of the input space affects the spatial organization of the resulting map.

Recently much attention has been devoted to the problem of translating a set of geometrical objects in a given direction, one at a time, without allowing collisions between the objects. This paper studies the translation problem in three dimensions on a set of c-oriented faces", that is, the faces whose bounding edges have a constant number c of orientations. We solve the problem in O(N log2 NK) time and O(N log N) space, where N is the total number of edges of the faces and K is the number of edge intersections in the projection plane. As an intermediate step, we also solve a problem related to ray-shooting. The algorithm for translating c-oriented faces finds uses in computer graphic systems.

An organization may suffer large losses if its computer service is interrupted. For protection, it can purchase computer backup service from the outside market which temporarily provides service replacement from a central facility. A dynamic probabilistic model is developed which describes such a computer backup service system. The parties involved have conflicting motivations. The supplier is interested in optimizing his expected profits subject to a given set of parameters while the subscriber will evaluate the service contract to his own best interest. This paper analyzes how the economic interests of the supplier and subscribers interact based on a dynamic reliability analysis of their respective computer systems. Assuming all physical parameters fixed, the supplier's optimal value in terms of economic parameters is determined. An algorithmic procedure is developed for computing such values. Some numerical examples are presented in order to gain insights into the system.

Information geometry is a new powerful method of information sciences. Information geometry is applied to manifolds of neural networks of various architectures. Here is proposed a new theoretical approach to the manifold consisting of feedforward neural networks, the manifold of Boltzmann machines and the manifold of neural networks of recurrent connections. This opens a new direction of studies on a family of neural networks, not a study of behaviors of single neural networks.

This paper examines the key technologies and applications of optical frequency division multiplexing (OFDM) systems. It is clarified that a 100-channel OFDM system is feasible as a result of multichannel frequency stabilization, common optical amplification and channel selection utilizing a tunable optical filter. Transmission limitation due to fiber four-wave mixing is also described. Major functions and applications of the OFDM are summarized and the applicability of OFDM add/drop multiplexing is examined.

An application of wavelength conversion laser diodes (WCLDs) to a photonic cross-connect system using wavelength-division (WD) technology is presented. We propose a novel WD photonic cross-connect node architecture with multiwavelength selective filters. By using the filters, we can construct a nonblocking cross-connect switch by 2-stage connection. Next we describe the requirements to the optical devices in our switch, especially to the wavelength conversion devices in configuring a multistage connection of our switch. Finally, we have conducted the wavelength switching experiments using our wavelength conversion laser diode at a bit rate of 125Mb/s and shown its applicability to a WD photonic cross-connect system with over 3,000 channels.

A frame-installed lightwave synthesizer is constructed for optical frequency-division-multiplexing (FDM) communication. The synthesizer consists of two DFB diode lasers, electrical feedback loops, and an HCN gas cell used as a frequency reference at v0=192,843GHz (1.55459µm in wave-length). Output frequency can be stabilized at anywhere within v0(220) GHz. The beat note observed between the synthesizer and another HCN-stabilized DFB laser is constant within 2MHz over 100 hours. Frequency stability better than 410-10 (80kHz, without normalization) is obtained for an averaging time of 200s.

This paper presents a simple method for avoiding both numerical errors and degeneracy in an incremental-type algorithm for constructing the Voronoi diagram with respect to points on a plane. It is assumed that the coordinates of the given points are represented with a certain fixed number of bits. All the computations in the algorithm are carried out in four times higher precision, so that degeneracy can be discerned precisely. Every time degeneracy is found, the points are perturbed symbolically according to a very simple rule and thus are reduced to a nondegenerate case. The present technique makes a computer program simple in the sense that it avoids all numerical errors and requires no exceptional branches of processing for degenerate cases.

A new type of optical frequency domain reflectometry is demonstrated. Optical carrier frequency is swept so that a phase of the backscattered light is shifted. Then, an interference output of the backscattered light is Fourier transformed. The farther the scattering point locates, the faster the phase of the backscattered light changes. Hence, the Fourier spectrum of the interference output displays the fault distribution along a wave-guide. In the present scheme, the theoretical resolution is inversely proportional to the frequency sweeping range of the optical source and is given by z=c/2nf, where f is the frequency sweeping range of the optical source. In a preliminary experiment, a Michelson type interferometer in which a target fiber of 20cm length is inserted in a probing arm. The reference arm is adjusted to be longer than the probing arm by about 1.8m. This is because the interference term between the backscattering light and the reference light should be separated from the interference term formed by the backscattering light itself. A LD pumped Nd: YAG ring laser whose frequency sweeping range is 20GHz is used as a variable wavelength source. The calculated resolution is 5mm for n=1.5 in fiber. A resultant spectrum in which the two peaks correspond to the reflections at both the fiber ends is obtained.

Multiple-site diversity systems are foreseen for earth to satellite paths operating at frequencies above 10GHz in localities with high rain-induced attenuation. In some severe cases double-site protection can be proved to be inadequate and consequently triple-site diversity becomes indispensable. In the present paper, an approach for the prediction of the triple-site diversity performance based on an appropriate three-dimensional gamma distribution is proposed. The model is oriented for application to earth-space paths located in Japan and other locations with similar climatic conditions. Numerical results are compared with the only available set of experimental data taken from some parts of the United States. Some useful conclusions are deduced.

The effect of the externally reflected light on the mode partition characteristics of 1.3 µm Fabry-Perot laser diodes is studied experimentally and numerically. It is observed that the k-value increases monotonically with the DC bias current and the external reflection coefficient. Based on these experimental results, a numerical model to study the mode partition characteristics of laser diodes in the presence of external reflections is developed. The results calculated using this model agree well with the experimental ones. It is found that the mode partition noise is mainly caused by the interference between the light in the laser diode and the reflected light, and also by the fluctuations of the induced emission and absorption. In the time domain, their contribution to the mode partition noise is almost localized in the time region within 0.1nsec at the time when the optical pulse turns on.

This paper describes a new approach towards the performance-driven layout for analog LSIs. Based on our approach, we developed an automatic performance-driven layout system LIBRA. The performance-driven layout has an advantage that numerical evaluations of performance requirements may exactly specify layout requirements so that a better layout result will be expected with regard to both the size and the performances. As the first step to the final goal, we only concern with the DC characteristics of analog circuits affected by the placement and routing. First of all, LIBRA performs the sensitivity analysis with respect to process parameters and wire parasitics, which are major causes for DC performance deviations of analog LSIs, so as to describe every perfomance deviation by its first order approximation. Based on the estimations of those performance deviations, LIBRA designs the placement of devices. The placement approach here is the simulated annealing method driven by their circuit performance specification. The routing of inter-cell wires is performed according to the priority of the larger total wire sensitivities in the net by the maze router. Then, the simple compaction eliminates the empty space as much as possible. After that, the power lines optimization is performed so as to minimize the ferformance deviations. Finally, an advantage of the performance improvement by our approach is demonstrated by showing a layout result of a practical bipolar circuit and its excellent performance evaluations.

Information technology equipment connected to telecommunications line can be a source of electromagnetic interference. Two sources of interference have been under evaluation. One is the digital pulses in the switching regulator and the clock oscillator, and the other is the signal's common mode voltage. In this paper, the interference-inducing mechanism for the signal's common mode voltage and a method for measuring the interference are described. An equivalent circuit representing both the equipment and the line is derived on the basis of the interference-inducing model. A method for estimating the signal's common mode voltage from the differential mode voltage and the line unbalance is obtained using the equivalent circuit. It is confirmed that the level difference between the estimated and the measured common mode level is less than 3dB.

This paper investigates the compositionality of operational models for concurrency induced by labeled transition systems (LTS's). These models are defined on the basis of a metric domain first introduced by de Bakker and Zucker; the domain is a complete metric space consisting of tree-like structures called processes. Transition system specifications (TSS's) define LTS's; the set of states of such a LTS A is the set of terms generated by a signature Σ. For the syntactical operators F contained in Σ, semantic operations (on processes) associated with F are derived from the TSS S by which A is defined, provided that S satisfies certain syntactical restrictions. By means of these operations, the compositionality of the operational model induced by A is established. A similar result was obtained by Rutten from TTS's which define finitely branching LTS's. The main contribution of this paper is generalization of Rutten's result to be applicable to TSS's which are based on applicative languages including recursion, parameterized statements, and value passing, and which define infinitely branching LTS's. A version of typed λ-calculus incorporating µ-notation is employed as a formalism for treating recursion, parameterized statements, and value-passing. Infinitely branching LTS's are needed to treat programming languages including value passing such as CCS.

Radiation properties of magnetic noise from the harness wires of a spacecraft (GEOTAIL) have been studied experimentally and theoretically. A simulation experiment on the noise radiation using a minimum set of subsystems of the spacecraft has shown that the intensity and the directional patterns of the noise radiation from the wires were largely changed by the existence of a conductive plate near the harness wires. The change in the noise characteristics is explained by eddy currents induced in the conductive plate by the signal current flowing in the wires. The eddy currents distributed in the conductive plate were calculated by the Finite Element analysis Method (FEM). The magnetic flux densities calculated from both the source signal current and its induced eddy currents for the wiring configuration of the simulation experiment have shown to be consistent with the values obtained in the experiment. The results in the present study have provided us an important information on a wiring method to diminish noise radiation from harness wires.

Anechoic chambers have been effectively used for microwave propagation, electromagnetic interference (EMI) and immunity testing. The electromagnetic compatibility (EMC) problem has recently become serious and many of these chambers have been constructed. The results of a questionnaire survey sent to anechoic chamber manufacturers are described that a total of 450 anechoic chambers have been constructed in Japan since 1964. Twenty years ago the purpose of the chambers was microwave propagation research, but more than 50 each year have recently being built for EMC/EMI and immunity testing. Their size has gradually been reduced by the use of absorbing materials such as ferrite with dielectric materials. The lowest frequency of most chambers is 30MHz for the 3 m method of site attenuation.