The multirate ITA for a linear circuit is proven to converge under a weaker condition on the capacitance matrix of the circuit or under a stronger condition on the conductance matrix than those for the global-timestep ITA to converge.

It is shown that error correcting code improves an essential perfomance limitation of photon communications with energy loss. The coded photon signals allow us the loss about 13 dB to keep the advantage of photon number state signals while uncoded one is about 7 dB. Furthermore the necessity of weight distribution control of code words is discussed.

Rademacher transform possesses a superior quantization which is free from accumulation of quantizing errors. The quantization is applicable to the coding of a large image which saves a transform steps. Such a fast transform is desirable for the real time processing of a television pictures.

This letter proposes a novel type of 12 optical switch with a plastic-molded ferrule wherein an alignment mechanism is formed. Discussing the errors in ferrule fabrication, the insertion loss of the switch has been evaluated. The constructed switch for multimode fibers has shown an insertion loss of 0.7 dB and a switching time of 4 msec.

Microwave brightness temperatures expected to be measured by MOS-1 MSR over rain are calculated theoretically over the ocean background. The influence of ocean surface wind is evaluated by using a composite rough surface model. An algorithm for rain rate estimation by MOS-1 MSR is developed for each season of a year based on the theoretical calculation.

In this paper, the fundamental characteristics of wave propagation in a through-hole is reported by presenting of time variations of the Poynting vector and the electric fields in three-dimensional space and time.

The critical temperature T_c of recent oxide superconductors in Ba-Y-Cu-O systems is considered from the complete electron-phonon interactions in two-dimensional [CuO₂]-layers. It is concluded that the value of T_c does not exceed 110 K, so long as the phonon-mechanism is assumed.

A modified Read model analysis is proposed for millimeter-wave IMPATT diodes. The energy relaxation time and the ionization rates which have been obtained from the microscopic model are taken into account in this modified analysis. The validity of applying this analysis to millimeter-wave IMPATT diodes is examined.

Characteristics of all-hard Nb micro-contact Josephson junctions are investigated under 70 GHz millimeter wave radiation. Typical I_c(T) of the junction is identical with that of an ideal point-contact junction. In the voltage region, higher than the energy gap voltage of Nb, no-heating effect is observed.

This letter shows that an m-valued majority function is realized by m-1 two-valued threshold functions with common weight vector. A necessary and sufficient condition for an m-valued logical function to be a majority function is provided by using the concept of asummability.

An exact method determining optical flow from a sequence of images is presented. We adopt a pixel-based analysis calculating mutual-correlation functions between temporal change of brightness at a targer pixel and that at neighboring ones. Local velocity at the target pixel is deceided analytically from lag times of the correlation functions.

A wideband and high efficiency underwater ultrasonic transducer with a single acoustic matching plate has been presented. The transducer consists of a piezoelectric ceramic resonator, operating in unstiffened longitudinal mode, and a single acoustic matching plate bonded to the ceramic resonator. The matching plate is made of a Al₂O₃-epoxy composite. The ceramic resonator is T-shaped with a taper, where its polarized part is a thin rectangular bar, which can be driven with low voltage, and where its non-polarized parts comprise a horn part and a head part. The transducer has been designed based on a double mode filter synthesis theory, because it has two resonant modes, whose phases differ byπfrom each other. The optimum specific acoustic impedance and length for the matching plate have been calculated. The 30 kHz array, including four transducers supported at their vibrational nodes, has been fabricated and evaluated. As a result, it has been confirmed that the array has the following characteristics: 33% fractional bandwidth, 211.6 dB sound pressure level re lµPa at l meter,177 dB receiving voltage sensitvity re 1 V/µPa and possible operating depth over 3000 meters. Excellent agreement between theoretical values and experimental results has been obtained. It has been proved that this transducer is useful as a transducer with high resolution for deep oceans.

This paper proposes a new discrte optimization method which is mainly directed toward saving computing time for high-order FIR filters. In the proposed method, a transfer function is first approximated in a cascade form of a low-order function W(z) with pre-rounded coefficients and a high-order function F(z) with infinite precision coefficients. Second, rounded F(z) coefficients are discretely optimized so as to minimize the mean square error of the amplitude response. In other words, the roundoff error spectrum is shaped so as to be suppressed by a weighting function W(z). In order to save computing time, the error is equivalently evaluated in a time domain, and the F(z) coefficients are divided into small groups in the discrete optimization procedure. Design examples for 200 tap FIR filters demonstrate practical usefullness.

It is known that the modified van der Poloscillator proposed by Shinriki et al. can exhibit various interesting phenomena such as a period-doubling-bifurcation, chaos, windows, and a Double Scroll like attractor. But the mechanism of the generation of such phenomena has not yet been explained and cleared. In this paper, it is shown that the phenomena generated in the Shinrikis' circuit could be well explained by a simplified model which we hereafter call as the Ideal System. Here the idealization means that the element of diodes in the circuit operates as an ideal switch. The Ideal System is extremely simple because it contains 3 reactance elements, one linear negative coductance and only one nonlinear element constructed from diodes where the operation of such nonlinear element is very simple. The advantages of using the Ideal System to analyze the mechanism of chaos are as follows: Poincaré map could be derived strictly as a 1-dimensional discrete map from this model and from this obtained Poincaré map, the phenomena could be well explained. Moreover, the theoretical results are verified in the circuit experiments. The Ideal System makes clear the mechanism of chaos gonerated in the circuit.

Hypergaphs play an important role in the modeling of structures, especially in databases, information systems and knowledge representation. This paper attempts to fuzzify the concept of hypergraphs so that they can be used to represent soft structures. Basic definitions and properties of fuzzy hypergraphs, their duals, paths, path strength, partial fuzzy hypergraphs and sub-fuzzy-hypergraphs are given and investigated. The strongest path problem in fuzzy hypergraphs is also formulated and an algorithm to solve it developed.

Radiation patterns of an offset cylindrical reflector antenna are computed numerically by BEM (boundary element method), and compared with the corresponding measured patterns in order to seek the validity of the approach to the radiation pattern analysis for the whole angles without paying any attention to the combination of PO (physical optics) and GTD (geometrical theory od diffraction). First, a parallel-plate small horn antenna to be used as the primary feed for the offset reflector is analysed for the frequency range of 8 GHz to 12 GHz, and good agreement between the BEM and the measured radiation patterns (amplitude) is ascertained for the levels from 0 dB down to about 20 dB. Next, a small offset reflector antenna is manufactured, where the aperture width, the focal length, the offset angle, and the aperture angle are chosen 432 mm, 200 mm, 65and 40, respectively. It is shwon that the computed patterns by BEM (H-plane) is well verified by the measured data from the mainbeam to wide-angle regions, proving the validity of the approach to the field analysis of two-dimensional reflector antennas.

A typical event of quasi-periodic scintillations measured simultaneously at 1.5 GHz and 4 GHz is presented. Moreover, the probable electron density and spatial scale of irregularities in the ionosphere necessary for producing such a phenomenon are evaluated. Results indicate that estimated electron density at the center of a columnar irregularity assumed in the ionospheric E- or F-region ranges from 2 10¹² to 2 10¹³(m^-3), the value of which represents a level several to several hundred times as high as the average ionospheric electron density. In addition, such irregularities must have small effecctive radii of 100 to 300 meters.

A novel temperature-to-frequency converter consisting of the thermistor-controlled current source, comparator, and monostable multivibrator is developed. Linearization is made by comparing the voltage developed across the current source with an exponentially growing voltage. A prototype converter built using standard components shows an excellent linearity with the residual error less than 0.2% over the range from 273 K to 353 K. The converter features the simple configuration, high accuracy, and single supply operation.