The concept of essential minimality for closed sets of multiple-valued logical functions is introduced and studied. Principal results include: (1) any essentially minimal closed set can be generated by a single function and (2) the number of essentially minimal closed sets is finite.

Acoustic distributed feedback (ADFB) lasers with stripe active regions for current injections have been theoretically analysed. The theory is based on a coupled-mode analysis employing Bragg guided modes. The characteristic equation of oscillation for the two-dimensional DFB laser is derived in an explicit form. The mode spectra and the threshold gains for the onset of the oscillation of the ADFB laser are obtained, and the characteristics of the two-dimensional mode structure is discussed. Also discussed is the effect of complex photoelastic constants.

An experimental high pressurized ink-jet device is described for reproducing gray level pictures by the pulse-width modulation of picture signals. A reproduced picture with the resolution of about two lines/mm, and seven gray level is obtained for a facsimile test chart which is scanned with the scanning density of five lines/mm, and also a good reproduced picture is obtained for a halftone dot picture.

Equivalent network approach has been applied to the guided wave problems in the dielectric thin-film waveguides for optical integrated circuits. The results by this approach for the rib waveguide and the optical strip waveguide agree well with the results by the numerical approaches.

Formal descriptions for constructing a Joel's permutation network are discussed. We show that a setting algorithm of the network can be described in terms of bipartite graphs. We then study a fast parallel algorithm for setting the network. We show that it can be implemented by a parallel computer with N processors in O((log2 N)2) time, where N is the size of permutations produced on the network.

Self-healing breakdowns of anodic Y2O3 films with the thickness of 500 to 2000 have been measured. The measurements reveal that the breakdown is a single-hole type and that the breakdown field, which is closely correlated to the anodizing field, is independent of the Y2O3 thickness. An ionic motion is considered to the effective in initiating the breakdown which forms a conducting channel through the Y2O3 film. The energy of the breakdown spot formation is calculated assuming the thermochemical evaporation process of the substances. It agrees well with the discharged energy of the specimen capacitor at the breakdown.

This paper deals with an elementary alternative approach to the notion of the principal partition of a matroid into strongly irreducible minors. This approach makes use of the matroid union theorem and the concept of the density of a matroid introduced in this paper. For a matroid M on S the density d(M)S/r(M). The principal partition of a matroid M on S is constructed by first constructing a partition of S called the P-sequence of M. On the resulting sub-sets irreducible minors are constructed. An irreducible minor is further partitioned into strongly irreducible minors by examining all its restrictions of density equal to its own. It is constructively shown that the P-sequence of a matroid M can be obtained by considering the intersections of sets of coloops of matroids obtained from M by repeated use of the matroid union () and the dualization (*) operator. It is shown that the principal partition for such matroids can be immediately constructed if the principal partition for the original matroid were given. Finally, efficient algorithms are outlined for constructing the principal partition.

The authors implemented a directionally-constrained adaptive array system in an audio-frequency range. This system has a good prospect of applications since it does not require a rigorous a priori knowledge of the desired signal. Its algorithm contains matrix calculation, for which some technique has to be devised in implementation. For this, data are sampled and A-D converted so that the necessary processing for feedback control may be done by a microcomputer in digital form. The signal path remains in analog form, which will allow us to extend the system to higher frequency range. The performance of the system is demonstrated through the experiments. Effects of hardware errors are found: (1) Nulling behavior against the interference is not affected at all by virtue of the feedback control. (2) A little deviation from the constrained response to the desired signal is perceived. The behavior against a wideband interference is investigated analytically and experimentally. It was found that the final SIR becomes lower with wider frequency bandwidth.

This paper describes designing on required signal to crosstalk power ratio of symmetrical cable for bipolar pulse transmission. Error rate in bipolar pulse transmission is discussed taking into account average signal to far-end crosstalk power ratio, average signal to near-end crosstalk power ratio and their standard deviation. Experiments were conducted with regard to the relation among average signal to crosstalk power ratio, its standard deviation and error rate. Calculated and measured results show good agreements. From these results, designing on required signal to crosstalk power ratio and its standard deviation in dB for required error rate is clarified.

The performance of a pulsed HF chemical laser with an F2/H2 chain reaction system is widely compared to that of an F/H2 non-chain reaction system by using a chemical laser simulation code based on the constant gain method. According to the simulation results, peak power differs little between both systems; laser pulse duration is more than an order of magnitude shorter in the F/H2 system than that in the F2/H2 system; laser pulse energy in the F2/H2 system is greater than that in the F/H2 system; difference in these energies is exponentially proportional to the inverse of the initial fluorine atom concentration; laser pulse energy per mol of HF() produced prior to termination of the lasing differs little between both systems; the thermodynamical efficiency is a decreasing function of the initial fluorine atom concentration in the F2/H2 system while in the F/H2 system it has a maximum value at the certain concentration.

The authors have previously reported the algorithm of a lowpass-type variable cosine equalizer in the case of relatively rough input data. As a continuation of this work, in this paper we will propose a new algorithm applicable to the bandpass-type input data.

In this paper, an algorithm for implementing a high-speed FFT processor and the memory structure relating with it are mainly discussed. The problem to be considered when implementing a hard-wired high-speed FFT processor will be as follows: (1) How to simplify the decision of data addresses to be accessed. (2) How to avoid the memory access conflict when introducing the parallelization of memory. New method presented in this paper gives a drastic solution to them. Namely, utilizing the proposed memory structure allows any number of butterfly computations as well as single one to be carried out substantially in only one memory cycle. Furthermore, there is no theoretical restriction in any level of parallelization. Therefore, it is easy to implement the FFT processor having a reasonable throughput for particular application. The discussion in this paper is primarily proceeded from the hardware standpoint of implementation. However, there is no essential disparity between the proposed organization and that of conventional computers. The only difference between them is a conceptual one with respect to memory structure. Thus the presented method is useful enough for implementation of the algorithm on a conventional computer system such as multi-processors, and for its implementation by hardware as well.

The reliability of the FE method and the CV method for determining the localized state distribution N(E) in GD a-Si are evaluated by computer simulation. It is shown that calculation by the CV method is almost exact and the FE method is less reliable. But the FE method may be more reliable than the CV method about the accuracy of measured values. The new calculation method combining both methods and the iteration method are suggested for obtaining almost true distribution N(E). And the effect of surface states on calculation of N(E) is evaluated; the allowable surface state density is shown to be below 1011cm-2eV-1. The effect of the Fermi-Dirac distribution function F(E) at room temperature is estimated. The results indicate that correction by room temperature F(E) is necessary.

This paper describes an analytical investigation of mode-coupled graded index (GI) fibers. The analysis is based on the Scattering Matrix Method. The mode coupling parameters of the fibers are clarified in calculations and experiments, and the results obtained are used to determine the actual transmission characteristics of long, spliced GI fibers, for the wavelength region near 1.3 µm, as well as for the region near 0.85 µm. It is determined that coupling between adjacent modes is dominant and that a microbending loss of an order of about 0.1 dB/km results in an extremely large increase in the bandwidth of GI fibers larger than 20 km. In this paper the propagation constant for mode groups with the same propagation angle is derived directly from a WKB analysis.

Asynchronous sequential circuits, obtained by generalizing the astable multivibrator and monostable one as sequential circuits having state-transitions among any number of stable states and quasi-stable states, are called sequential circuits having quasistable states (SCQ's). Moreover, a mathematical model of the SCQ is called the sequential machine having quasi-stable states (SMQ). This paper is devoted mainly to the state reduction problem of the SMQ. There are two types of the SMQ's (celled type I and type II). The difference between the types is the specifications of each quasi-stable duration. Thus this paper describes state reduction methods for type I and type II, where the latter utilizes the former. The systematic state reduction methods described in this paper become considerably more complicated than that for conventional sequential machines, because of the particularity of the quasistable state. Of course, this method is an extension of the state reduction method for the conventional asynchronous sequential machine. This paper includes a definition and representations of the SMQ, definitions of concepts available for the SMQ's, and their systematic state reduction methods.

Filtering techniques on a finite ring are paralleled to the techniques on the usual complex number field. A z-transform is defines over a finite ring which assimilates the complex number field. This z-transform is related to the usual z-transform and shown to have many properties in common. This z-transform can uniquely represent a filter on the finite ring with a given impulse response or frequency sample response function. The z-transform representation enable one to design recursive FIR (Finite Impulse Response) filter on the finite ring by the analogous methods of the usual z-transform. An interesting property of the recursive filter design on the finite ring is that stability problems due to particular design configulations need not to be considered so long as the inputs are limited to a certain value so that the design problem becomes primarily a problem of complexity reduction.

Several long (11.0-30.4 km) graded-index fibers with good transmission properties in the wavelength bands of 1.3 and 1.55 µm have been fabricated by the VAD method. Special attention was paid during the deposition process to improve the longitudinal uniformity in transmission characteristics of the fibers. The transmission loss uniformities of the VAD fibers along axial direction have been measured by the back scattering technique with use of Nd-YAG laser at 1.06 µm. The bandwidth uniformities of these fibers were also ascertained to be satisfactory. Preliminary transmission experiments on spliced 65.1 km and 116.5 km fiber systems were also made by use of 1.3 µm and 1.55 µm laser diodes.

The filter characteristics of electromagnetic TM waves in a dielectric slab waveguide having a sinusoidal variation of its permittivity in the propagation direction are investigated. With the aid of a singular perturbation procedure, the coupled-mode equations governing the nature of TM waves interactions are deduced for both symmetric and asymmetric first-order Bragg interactions. Omitting the end effects, an expression describing the characteristics of reflection of TM wave is derived from the boundary value problem in the propagation direction. Experiments on reflection characteristics have been performed in the millimeter wave region where the dielectric slab created by arranging an Aflon slab in periodic fashion in a Teflon slab is tested as a permittivity-modulated slab waveguide. Return loss data and observed stopband responses are reasonably consistent with theory.

The "relativized Turing machines" are introduced as media executing program schemas. On these machines, it is proved that, for any a, 0a1, there exists an O(na) space and O(n2-a log n) time bounded program schema to sort n elements, and any O(na) space bounded schema to sort n elements requires more than O(n2-a) time. Furthermore, it is shown that there exists a problem which causes a large scale time-space trade off. That is, we show the existence of a problem Q such that there is an O(n2) space and polynomial time bounded schema to compute Q, and there is an O(n log n) space bounded schema to compute Q, and further, any S(n) space bounded schema requires more than exponential time if S(n)n2.

Candidate plans for adaptive digital transmission are briefly reviewed. It is suggested that adaptive format transmission with asynchronous multiplexing capability is attractive and promising from the standpoint of practical application. Feasibility and efficiency of this new transmission plan are investigated. A formula for predicting the minimum required transmission rate is derived. Upper and lower bounds of transmission efficiencies are analysed. A signal distributing technique for improving transmission efficiency is also developed. Investigation of memory requirements anticipates the possibility of simple implementations for format conversion and reconversion. Results of simulations prove the reliability of theoretical predictions. Fiber optic transmission is expected to be suitable for realizing this new communications concept.