The decision logic expression method is generalized so that any two-valued logic utilizing conventional AND, OR, and NOT operations can be expressed in terms of conditional AND. Thus, the scheme is suited to describing decision logics in fields such as education, medicine, and management.

The time delay of magnetostatic wave in a YIG slab has been studied experimentally, where the nonuniform dc magnetic field is applied normal to a slab surface by using the artificially sharpened magnetic pole piece. The non-dispersive group delay characteristics are found, and the effect of nonuniform magnetic field on the propagation loss is also investigated.

In this paper, multi-head and finite-state transducers are proposed, and their computing abilities of number-theoretic functions are investigated. A multi-head transducer is an automaton which maps a unary input into a unary output using a finite number of input heads. A finite-state transduccer is one with single input head. First, it is shown that a two-way finite-state transducer is strictly more powerful than a one-way finite-state transducer, but a two-way finite-state transducer can be simulated by a two-scan finite-state transducer. As for the multi-head transducer, the following results are derived. The upper bound of increasing degree of functions computed by two-way multi-head transducers varies with the number of input heads. However, a two-way two-head transducer can compute an arbitrarily slowly increasing monotone total recursive function, so that there exists no lower bound of increasing degree of a function computed by it. Although the class of two-way multi-head transducers forms an infinite hierarchy of computing abilities with respect to the number of input heads, it is shown that a one-way multi-head transducer is equivalent to a two-way finite-state transducer provided that the number of input heads is more than one.

An analog voice scrambling method Sample Inversion" is presented along with several experimental results. The Sample Inversion" principle is to invert the voice sample polarity according to the key code, smooth it with low pass filter and feed it to the transmission channel. Necessary techniques to utilize the principle, filtering and synchronizing are described. Key code design is examined and an error correcting code is proposed appropriate to the key code. Experimental equipment is assembled to prove the principle. Using the same equipment, spectrum variation is demonstrated and articulation by voice scrambling is measured. The Sample Inversion" method can be realized by circuits assembled with conventional parts. Sample Inversion" provides natural voice to the properly keyed-in receiver and assures that the conversation is completely unintelligible to any other receivers. Lack of voice quality sensitivity to noise is also to be emphasised.

A speech recognition system for programs written in FORTRAN level is described. The acoustic analyser based on a psychological model for phoneme identification can represent the speech sound by a phoneme string which contains some acoustic features such as buzz and silence. Therefore a word, its corresponding item of the word dictionary, is readily expressed in Roman letters accompanied with some acoustic features. The linguistic processor, using global acoustic information in addition to linguistic one, can effectively restrict the number of candidate words. The recognition process has been executed for each block; here, a block is a part of speech uttered in a breath. A new method for matching the input symbol string with errors to the reference symbol strings is also described. The system contains 146 words including letters. The syntax is expressed by state transition diagrams and implemented using tables. It has a back-tracking function. The recognition score is about 91% in terms of blocks when FORTRAN programs are spoken by 3 adult males. Since we cannot yet classify some letters such as P and T, the system has some restrictions of use.

A 65 Kbit dynamic MOSRAM has been realized using short channel and single-level Si-gate technologies and a newly designed, highly sensitive and low power dissipation sense amplifier. Access time and power dissipation are 150 ns and 120 mW, respectively.

We consider an adaptive PCM system, in which the input samples are expanded or compressed by a constant factor c or 1/c each time before quantization. Assuming a stationary Gaussian input with a rational power spectral density, we derive an integral equation for the joint distribution of the input and the state of the system. Its solution provides us with a feasible way to numerical computation. The mean-squared error are computed for the Gauss-Markov input in terms of the constant c, the sampling interval T, bound parameters for the scaler and the number of quantization levels. The numerical results show good performance in comparison with regular PCM.

Variation of power distribution caused by splices is calculated as a function of numbers of splice points and misalignment. The calculated power distribution is verified by experiment. Calculation shows that mode conversion caused by splice makes power distribution approach to steady-state. The numbers of splice points required to make power distribution stationary are calculated as a function of misalignment. Pulse broadenning in the fiber transmission line is calculated for the case that fibers are mode conversion free. Pulse broadenning rate becomes proportional to the square root of transmission distance after optical pulse passes many splice points. These calculated results show that mode conversion caused by splice has similar tendency as that caused by longitudinal inhomogeneity of waveguide.

We formulate an improved lower bound on the maximum number of prime implicants of n-variable Boolean functions. It is given as n!/(n/3!(n1)/3!(n2)/3!)(n, 0, (n1)/32)(n, O, (n2)/32), where (n, 0, r) is evaluated by the following recursive procedure: (n, 0, r)0 for r0, (n, 0, 0)1 and (n, 0, r)n!/(r/2!(nr)!(r1)/2!)(n, 0, (r1)/2 2) for 1rn. The total logarithm computing time cost and the total uniform computing time cost of this lower bound by a random access machine are O (n (log2n)2) and O (n), respectively. The ratio of this new lower bound to the old lower bound is bounded by 1c (1/2)n/3, where c is a constant independent of n.

The statistical model for urban radio propagation has been proposed to describe the characteristic of radio pulse propagation in urban area. A modified Poisson process was used to model the clustering phenomena of the pulse arrival time sequence. In this paper, the model analysis is extended for more flexibility in data fitting, and generalized using a Markov chain to get a clear view of the statistical model. Some numerical results are shown for different values of the clustering parameter (Δ). Referring to the numerical results, the effect of Δ and the another clustering parameter (K) on the pulse number distribution is discussed. Next, the relation between the empirical pulse occupancy rate and the underlying occupancy rate of the model is derived for Δ1 using a Markov chain. By this extension and generalization, the statistical model of the pulse arrival times will be applied to a wide range of the clustering phenomena.

First, it is shown that pole sensitivity with variation of gain-bandwidth product is dominant in an RC active circuit realized by an internal phase-compensated operational amplifier. Second, a method is described, by which a single amplifier 2nd-order RC active circuit with prescribed pole sensitivity with variation of gain-bandwidth product can be realized.

By the term peak frequency" of a short-time power spectrum, we mean a frequency at which the power spectrum takes a maximal value with respect to frequency. Peak frequencies are recognized to be important feature parameters for machine recognition of sound signals. We propose a new method for extracting the peak frequencies from a pitched signal like speech sounds, musical instrument tones, and so on. Our method makes use of the first and the second frequency derivatives of a short-time power spectrum, so that it is called Power Spectrum Derivative Method (PSDM)". PSDM has such an advantage that exact peak frequencies having close relevance to the resonance and harmonic components can be extracted from a short duration signal. PSDM was applied to the analysis of Japanese vowels and guitar sounds with good results.

This paper is concerned with reparing time evaluation for a multi-subequipment system. By Convolution application, a renewal of the system is shown to depend on the repair executing sequence, and to be accomplished merely by replacing 0.264 times located cards.

The bandwidth of the single-mode fiber is derived for both the amplitude-modulation and the heterodyne-detection (AM) system and the intensity-modulation and the intensity-detection (IM) system, in case that the spectral width of the light source is much less than the modulation bandwidth. In the wavelength-division-multiplexing system, the bandwidth per carrier wave is given as a function of the wavelength, and also at the zero-dispersion wavelength. In case of IM system, the frequency dispersion of the fiber causes the harmonic distortion of the signal and reduces the bandwidth to about a third of that in case of AM system.

Two-dimensional diffracted fields from semiinfinite conducting plane with a circular cylinder of various types at its apex are studied for the purpose of suppressing the backward radiations from the reflector antennas. The basic policy for the suppression of the diffracted fields was already obtained by the authors. It concludes that the electrically and magnetically conducting cylinders are most effective in suppressing the diffraction for the E and H wave incidence, respectively. From the practical point of view, the main difficulty in this policy is how to realize the magnetically conducting cylinder which suppresses the H wave diffraction. In this paper, a corrugated cylinder is adopted for the purpose of the suppression of the H wave diffraction. The characteristics of this cylinder are analyzed by the mode-matching techniques and it is indicated that the corrugated cylinder fairly suppresses the diffracted fields, not only for the H wave but also for the E wave incidence, to almost the optimal level. Additionally, the wideband frequency characteristics are introduced. All these theoretical results are confirmed by the equivalent two-dimensional experiments. At the end of this paper, the applicability of the corrugated cylinder to the suppression of the three-dimensional diffracted fields is suggested experimentally.

Several reports have been published on the quantitative analysis of kink formation mechanism in the output vs. current relation in stripe geometry injection lasers. The results, however, contradict with each other in basic points. In seeking for a better quantitative understanding of the transverse mode instabilities manifested by the kink formation, this paper examines basic aspects of the spatial hole-burning induced mode deformation, which is believed to cause the instabilities. Properties of the eigen functions and eigen values corresponding to the light propagation in a complex dielectric waveguide with a spatial gain and/or loss variation are examined, and an efficient approximation scheme is proposed for computing modal gain. This scheme is applied to a numerical model which approximates gain and refractive index profiles with spatially burned holes in a stripe geometry injection laser. It is found that the mode deformation induced by the hole-burning substantially affects the modal gain, and that the extent of the influence depends strongly on the refractive index contribution to the waveguiding.

Aliasing effect of a sampled signal can be reduced by estimating the signal from the samples and then updating the estimate by an iterative technique. This idea can be implemented easily by a multiplier and a feedback loop.

This paper gives an experimental result on the measurement of the maximum coupling coefficient and the coupling length between the active waveguide and the passive output waveguide in GaAs/AlGaAs integrated twin-guide (ITG) injection lasers prepared by LPE. Very high coupling efficiency between the active and the passive waveguides was experimentally confirmed. The maximum coupling coefficient and the coupling length were measured to be about 90% and 250 µm, respectively. These values were in agreement with theory. At properly chosen parameters, the threshold current density on an ITG-type" laser was as low as 3 kA/cm2 at room temperature.

Analytic expressions for evaluating minimum propagation delay time tpd are derived, using a model which is effective for analysis of the device with a merged structure. Calculated results are in good agreement with experimental ones. Junction modifying coefficient k is newly introduced for the theory. k affects tpd through a variable function of current gains, and a deviation from the Klaassen's theory is pointed out. Role of the pnp transistor on the performance of the I2L gate is emphasized.

This paper proposes a heuristic algorithm for constructing a new school timetable by revising partially the school timetable already constructed for the previous year. This algorithm is considered as an extension of the algorithm proposed in the author's previous paper which aims at constructing a new school timetable. It is noted that the assignments in the present algorithm begin with an almost filled school timetable, while the assignments in the previous algorithm begin with an almost empty school timetable. Numerical examples show that the computation time of the present algorithm is considerably shorter than that of the previous algorithm when a timetable for the previous year is available.