This paper presents a novel model of optical associative memory using an optoelectronic neurochips, which detects and processes a two-dimensional input image at the same time. The original point of this model is that the optoelectronic neurochips allow direct image processing in terms of parallel input/output interface and parallel neural processing. The operation principle is based on the nonlinear transformation of the input image to the corresponding the point attractor of a fully connected neural network. The learning algorithm is the simulated annealing and the energy of the network state is used as its cost function. The computer simulations show its usefulness and that the maximum number of stored images is 150 in the network with 64 neurons. Moreover, we experimentally demonstrate an optical implementation of the model using the optoelectronic neurochip. The chip consists of two-dimensional array of variable sensitivity photodetectors with 8 16 elements. The experimental results shows that 3 images of size 8 8 were successfully stored in the system. In the case of the input image of size 64 64, the estimated processing speed is 100 times higher than that of the conventional optoelectronic neurochips.

For systems in which the probability that an incorrect output is observed differs with input values, we adopt the redundant usage of n copies of identical systems which we call the n-redundant system. This paper presents a method to find the optimal redundancy of systems for minimizing the probability of dangerous errors. First, it is proved that a k-out-of-n redundancy or a mixture of two kinds of k-out-of-n redundancies minimizes the probability of D-errors under the condition that the probability of output errors including both dangerous errors and safe errors is below a specified value. Next, an algorithm is given to find the optimal series-parallel redundancy of systems by using the properties of the distance between two structure functions.

Koblitz and Miller proposed a method by which the group of points on an elliptic curve over a finite field can be used for the public key cryptosystems instead of a finite field. To realize signature or identification schemes by a smart card, we need less data size stored in a smart card and less computation amount by it. In this paper, we show how to construct such elliptic curves while keeping security high.

A 10 GHz MMIC predistortion linearizer fabricated on a single chip is demonstrated for the first time. It employs less hybrid circuits compard with conventional devices, and is suitable for miniaturization. The total chip size of the fabricated MMIC is about 3.5 mm3.0 mm. The distortion reduction effect is examined using this linearizer. The improvement in IM3 is more than 15 dB between 10.45 GHz and 10.70 GHz, and more than 8 dB between 10.05 GHz and 10.90 GHz.

A two-dimensional quasi-exact active imaging method for detecting the conducting objects buried in a dielectric half-space is proposed. In this imaging method, an image function which is a projection of buried object to an arbitrary direction, is introduced exactly by taking account of the presence of the planar boundary. The image function is synthesized from the scattering fields which are measured by moving a transmitting antenna (a current source) and a receiving antenna (an observation point) simultaneously along the ground surface. The scattering field is generated by the physical optics current assumed on the surface of buried object. Because the effectiveness of physical optics approximation has been confirmed for this problem, this is a quasi-exact active imaging method. The validity of this imaging method is confirmed by some numerical simulations and an experiment.

The beam propagation method (BPM) is a powerful and manageable method for the analysis of wave propagation along weakly guiding optical waveguides. However, the effects of reflected waves are not considered in the original BPM. In this paper, we propose two simple modifications of the BPM to make it relevant in characterizing abrupt discontinuities in weakly guiding waveguides at which a significant amount of reflection is expected to be observed. Validity of the present modifications is confirmed by the numerical results for abrupt discontinuities in step-index slab waveguides and butt-joints between different slab waveguides.

The Akebono satellite observed the Australian Omega signals when it passed about 1000km over the Omega station. In this paper, we compare the observed Omega signal intensities with the values obtained using a full wave calculation and we discuss a mechanism of modulation of the signals. The relative spatial variations of the calculated Omega intensities are quite consistent with those observed, but the absolute calculated intensities themselves are several dB larger than the observed intensities. This difference in intensity may be due to the horizontal inhomogeneity of the D region, which is not modeled in the full wave calculation, or to an incorrect assumption about radiation characteristics of the Omega antenna. It is found that modulation of the observed signals is caused by the interference between the waves with different k vectors.

A best-fit panel model in the radio holographic metrology taking into account locations and sizes of actual surface panels in a large reflector antenna is presented. A displacement and tilt of each panel can be estimated by introducing the best-fit panel model. It was confirmed by simulations that the distinction can be drawn between a continuous surface error and a discontinuous one. Errors due to truncation of the radiation pattern were calculated by simulations. It was found that a measurement of a 128128 map is optimum for the 45-m telescope. The reliability of the measurements using this model was examined by experiments with panel displacements. Panel adjustments using the best-fit panel model successfully improved the surface accuracy of the antenna from 138µm rms to 84µm rms (/D=210-6).

This letter proposes a microstrip band elimination filter having an optically controlled small gap on a resonant section for the shift of the eliminated frequency range using the semiconductor plasma. The basic characteristics of this filter are analized theoretically utilizing the (FD)2TD method.

The regulatory mechanism of protein synthesis on a messenger RNA was analyzed from view point of the optimal control and discussed about availability for artificial production of peptide and protein. The transient movements of a ribozome through a messenger RNA with its production of peptide was based on the theory proposed by Gordon (1968). The optimal state of total process was defined as the state at which the time dependent change of each process of peptide synthesis has been minimized during a given time interval. This biological problem was converted into mathematical one by setting state variables and utilizing the optimal control theory with the help of Hamiltonian function. The first process of transition of a ribozome on a messenger RNA showed the largest change and with progress of state, the magnitude of change of each process decreased and became a simpler pattern. The effect of weighting coefficient relating with individual process was not confined only to its proper process but extended to all other processes. Each process was affected from all other processes. These were manifestations of effective and rational control strategies particularly for regulation of the sequential reaction in peptide synthesis. Such results were originated in the operation of the optimal control. By simulating physiological experimental data, it is possible to predict at what process and at what degree, the synthesis is regulated in order to achieve the optimal synthesis state. By analyzing the optimal synthesis process in combination with physiological experimental data, it would be possible to create artificial peptide and protein.

A theoretical and experimental study of a thin card-sized antenna is presented. The method of moment with a wire-grid model is used to analyze this antenna. In order to validate numerical efficiency, measurements using Wheeler method are preformed on this antenna and its wire-grid models. The experimental and theoretical results are in good agreement if the wire conductivity is well chosen. And the noise reduction of measured Wheeler efficiency using least mean square method is also examined.

An omnidirectional microstrip antenna using a parasitic cylinder is presented. A rectangular patch is formed on a dielectric substrate and it's completely covered with an aluminum cylinder which is somewhat shorter than a half of free space wavelength. Under such configuration the aluminum cylinder works as a parasitic element. This antenna can provides uniform omnidirectional radiation patterns and a broad frequency bandwidth. In this paper an experimental method for designing such an element is described. Measured input impedance characteristics, current distribution around the surface of the cylinder and patterns are also shown. By properly adjusting the coupling intensity between the patch and the parasitic cylinder a broad bandwidth antenna element can be realized. Some methods to adjust the coupling intensity are shown. A wide bandwidth element up to 14% for VSWR1.5 is obtained. Arranging many patches lengthways on a substrate and placing metallic cylinders around each patches, we can realize a high-gain and broad bandwidth collinear antenna.

When used for automotive applications, microcomputers have to meet two requirements more demanding than those for general use. One of these requirements is to respond to external events within a time scale of microseconds; the other is the high quality and high reliability necessary for the severe environmental operating conditions and the ambitious market requirements inherent to automotive applications. These needs especially the latter one have been responded to by further elaboration of each basic technology involved in semiconductor manufacturing. At the same time, various logic parts have been built into the microcomputer. This paper deals with several design approaches to the high quality and high reliability objective. First, testability improvement by the logical separation method focusing on the logic simulation model for generating test vectors, which enables us to reduce the time required for test vector development in half. Next, noise suppression methods to gain electromagnetic compatibility (EMC). Then, simplified memory transistor's analysis to evaluate the V/I-characteristics directly via external pins without opening the model seal, removing the passivation and placing a probe needle on the chip. Finally, increased reliability of on-chip EPROM using a special circuit raising the threshold value by approximately 1(V) compared to EPROM's without such a circuit.

This paper proposed a new algorithm of data compression for ambulatory ECG, where no distortion was included in the reconstructed signal, templates were constructed selectively from detected beats, and categorized ECG morphologies (templates) could be displayed in decoding the compressed data. This algorithm consisted of subtracting a best-fit template from the detected beat with an aid of multi-template matching, first differencing of the resulting residuals and modified Huffman coding. This algorithm was evaluated by applying it to ECG signals of the American Heart Association (AHA) data base in terms of bit rates. Following features were indicated. (1) Decompressed signal coincided completely with the original sampled ECG data. (2) Bit rate was approximately 800 bps at the appropriate threshold 50-60 units (1 unit2.4µVolt) for the template matching. This bit rate was almost the same as that of the direct compression (encoding the first differenced signal of original signal). (3) The decompressed templates could make it easy to classify the templates into the normal and abnormal beats; this could be executed without fully decompressing the ECG signal.

A two-cascaded image processing approach to enhance the subtle differences in X-ray CT image is proposed. In the method, an asymmetrical non-linear subfilter is introduced to reduce the noise inherent in the image while preserving local edges and directional structural information. Then, a subfilter is used to compress the global dynamic range of the image and emphasize the details in the homogeneous regions by performing a modular transformation on local image den-sities. The modular transformation is based on a dynamically defined contrast fator and the histogram distributions of the image. The local contrast factor is described in accordance with Weber's fraction by a two-layer neighborhood system where the relative variances of the medians for eight directions are computed. This method is suitable for low contrast images with wide dynamic ranges. Experiments on X-ray CT images of the head show the validity of the method.

For the effective control of microwaves in the frequency domain, we propose a new method utilizing current distributions of standing waves on the terminated microstrip line. We analized a short ended microstrip line using the (FD)2TD method to indicate the effectiveness of our proposal. Further we proposed an optically controlled microstrip filter as an application of this method.

High variability of object features and bad class separation of objects are the main causes for the difficulties encountered during the interpretation of ground-level natural scenes. For coping with these two problems we propose a method which extracts those regions that can be segmented and immediately recognized with sufficient reliability (core regions) in the first stage, and later try to extend these core regions up to their real object boundaries. The extraction of reliable core regions is generally difficult to achieve. Instead of using fixed sets of features and fixed parameter settings, our method employs multiple local features (including textural features) and multiple parameter settings. Not all available features may yield useful core regions, but those core regions that are extracted from these multiple features make a cntributio to the reliability of the objects they represent. The extraction mechanism computes multiple segmentations of the same object from these multiple features and parameter settings, because it is not possible to extract such regions uniquely. Then those regions are extracted which satisfy the constraints given by knowledge about the objects (shape, location, orientation, spatial relationships). Several spatially overlapping regions are combined. Combined regions obtained for several features are integrated to form core regions for the given object calss.

The potential distribution around a linear array of donor atoms in a semiconductor crystal is calculated, approximating the linear array by a continuous line charge. Two methods are used for the analysis. One is the self-consistent calculation of Poisson's equation and the effective mass Schrödinger's equation, and the other is the Thomas-Fermi approximation. Results of both methods agree very well, and it is shown that it is possible to form a potential distribution as fine as the electron wavelength by appropriate arrangement of the impurity atoms. Arrays of impurity atoms therefore can act as buiding elements for future electron wave devices.

We analyze the nonlinear dynamics of PLL from the "complex" singularity structure by introducing the complex time. The most important results which we have obtained in this work are as follow: (1) From the psi-series expansion of the solution, the local behavior in the neighbourhood of a movable singularity is mapped onto an integrable differential equation: the Ricatti equation. (2) From the movable pole of the Ricatti equation, a set of infinitly clustered singularities about a movable singularity is shown to exist for the equation of PLL by the multivalued mapping. The above results are interesting because the clustering and/or the fractal distribution of singularities is known to be a characteristic feature of the non-integrability or chaos. By using the method in this letter, we can present a circumstantial evidence for chaotic dynamics without assuming any small parameters in the equation of PLL.

In this article, we consider a hysteresis oscillator which includes periodic thresholds. This oscillator relates to a model of human's sleep-wake cycles. Deriving a one dimensional return map rigorously, we can clarify existence regions of various periodic attractors in some parameter subspace. Also, we clarify co-existence regions of periodic attractors and existence regions of quasi-periodic attractors. Some of theoretical results are confirmed by laboratory measurements.