An optimum condition in diffusion-exchange and heat-treatment process in fabricating fibers was obtained theoretically by applying the thermal diffusion. It has been made clear that both fourth and sixth order coefficients in refractive index distribution can be their optimum values for low aberration simultaneously.

In this paper, a numerically exact analyzing method is formulated for the diffused optical waveguide which consist of anisotropic or isotropic medium. By this analytical method, the guided modes of the diffused waveguide are determined and a measurement method for the diffusion coefficient is proposed as an application of this analysis. In the case that there is gradient of the dielectric constant, the exact analysis of the TM-modes is ordinarily difficult. In this analysis the index distribution for the anisotropic medium whose optical-axis is perpendicular to the waveguide or parallel to the waveguide-axis is sliced into multi-layers for successive numerical calculation. It is found, from the waveguides can be discussed with the equivalent film-width defined analytical results, that the propagation properties of the diffused in this paper which is analogous to that of the slab-waveguides. The diffusion coefficients and the activation energies of T1 and Ag in a fused-quartz and Vycor glass are measured with application of the analytical results.

It was found that an oxide power-epoxi resin mixture is an optimum material for surface acoustic wave absorbers oberlayed on LiNb03, Using a SAW device with edge reflection absorbers of this mixture for an FM discriminator, 0.05% distortion at 10.7 MHz center frequency, and 75 KHz frequency deviation, were obtained.

This paper descrives a deterministic parse algorithm for a context-sensitive language. The algorithm is an extension of the Cocke-Kasami-Younger's parse algorithm for a contest-free language to an algorithm for a context-sensitive language. The execution labor by the algorithm is more than 0(n3) for an input with length n.

This letter deals with a horn for radiating focused surface acoustic waves launched from circular arc interdigital electrodes into a narrow waveguide. A simple method of designing a horn using geometric optics was given and some experiments using a v/v waveguide were performed.

This article gives the realization of floating pure inductance using two operational amplifiers and four capacitors, and some examples of its applications. It also includes investigations of the maximum permissible value E1max of the input voltage of this circuit.

The paper considers the fault tree evaluation using the list processing technique. A tree sequence is newly introduced as a representation of the fault tree; it represents completely the branching structure of the tree. The properties and algorithms concerning the tree sequence are indicated. A method for computing the probability of occurrence of the top event is presented, which is featured by the recursive implementation of partition and reduction of the fault tree, through the combined use of the reverse Polish sequence and the tree sequence. This method enables us to evaluate the fault tree containing not only common primary events but also mutually exclusive primary events. By this method we can obtain the results in reasonable computation time for a fairly large scale fault tree having a few hundred primary events. The method can also be used for sensitivity analysis.

A three-terminal optical branch for multimode fiber was fabricated. Two pieces of optical fiber were side ground and glued together with the ground surfaces, the third optical fiber was butt-joined to the coupled fibers. The distribution ratio was 1:0.84 and the insertion loss was 3.2 dB for incoherent LED (8700) as well as for coherent He-Ne laser (6328).

In this paper, the electrochemical device is introduced, the behavior of which is suggested by the chronopotentiometry. A sudden increase in resistance of the device occurs after some charge passes through the device. This novel device inexpensively constructs a ULF rectangular waveform generator together with one O. P. amplifier and three resistors only.

This paper is concerned with an experimental approach to determining the feasibility of an optical PCM system at high bit rates. One necessary development is a high speed modulation technique using a semiconductor injection laser. The other is a high sensitivity receiving technique. First, this paper shows that high speed modulation with less pattern effect and less extinction ratio degradation can be effectively performed by adding the undershoot and overshoot to the driving current pulse in an injection laser. Second, this paper shows that a current feedback amplifier, consisting of an emitter-grounded bipolar transistor, is advantageous in high sensitivity of a high speed optical PCM receiving circuit, and to increase in repeater spacing. Finally, it is shown experimentally that the repeater spacing can be lengthened up to 5 km with a conventional graded index multimode fiber or up to 5.9 km with a single-mode fiber. It is confirmed by experiments that an optical transmission could be applied to a long distance and large capacity transmission system.

This paper demonstrates that the practical implementation of single b-Adjacent bit-group Error Correcting (SbEC) Code gives a modularized high reliability memory unit. By the application of rotational coding techniques to this code, not only a high speed parallel encoding/decoding network (memory translator), but also a memory unit can be organized in modular distributed forms, well suited for applying the LSI logic technologies to this memory translator and for achieving the high reliability and high maintainability memory unit. The parity check matrix of this code, which is easily decodable, can be expressed by the rotational operating matrix and the basic generating-submatrix. The basic hardware implementation of each modular organized translator consists of three circuitry portions which can be well designed for LSI logic. As an illustrative example, the most practical and optimum rotational (72, 64) S2EC code is implemented. The translator of this code is organized in four modular distributed forms. LSI logic patterns of each translator module require 30 to 50 input-output leads and 100 to 270 gates. The operational speed of this translator is almost equal to that of the conventional high speed SEC-DED (Single Error Correcting - Double Error Detecting) codes. As a result, this memory unit consists of four identical modules, each of which includes not only one of these translator modules, but also a storage portion and a input-output selector portion.

Given a set of n data records with Li, data length and Pi, access frequency of data record Ri (1in), each data record is allocated in one of buckets, whose size is L, minimizing the access delay D, DPiPjdij dij: distance from allocated data record Ri to Rj, while satisfying the constraint that the size of data records in each bucket does not exceed L. The property of optimal allocation is investigated and an allocation heuristic is given whose slight modification gives the optimal allocation for the data records of up to 2 unit data length.

In this paper, the authors propose a new mode analyzer. This mode analyzer is composed of an obliquely polished optical fiber and a high index prism placed in contact with the oblique section. Modes which have the different equivalent refractive indices are separated due to the different angles of refraction. A mode analyzer using a focusing fiber was made, and modes were successfully separated. The refractive index n(0) at the center axis, the coefficient g of the parabolic term in the refractive index distribution, and the refractive index in the cladding were evaluated from the measurement of angles of refraction. The obtained value of refractive index n(0) at the center axis almost agreed with the value obtained by the interference method. As the application of this mode analyzer, the measurement of group-delay differences of modes and amplitude distribution of modes in a long fiber, and the measurement of the constants of fiber are considered.

A new method of the information reduction of the three-dimensional image is proposed and experimentally verified. This method, the optically sectionned holography, is based on the principle of the coincidence of the time of arrival of the object and the reference beam in the holography. The resolution in depth is analyzed by taking into account the phantom imaging of the optical sectioned holography. The result gives the information content of the obtained hologram. The resulted information content is in the same order to that of the monocular three-dimensional image. So, this system can reduce the fairly amount of the information, comparing to the Burckhard's sampled holography. The system for the optically sectioned hologram by using the mode-locked, and the second harmonic generating c. w. Nd: Y AG laser is experimentally realized, and the optically sectioned holograms are obtained. From these holograms, the three-dimensional image of the original object is restored. A c. w. dye-laser is also used to obtain the optically sectioned hologram. The resulted resolution in depth is about 5 mm, which corresponds to the pulse width of the Nd: Y AG laser.

We have developed LITHAN (LIsten-THink-ANswer) speech understanding system which automatically recognizes continuously uttered speech utilizing higher linguistic information such as syntactic, semantic and pragmatic information. This system predicts possible words utilizing linguistic information at the unrecognized portion of the input utterance, and identifies each predicted word by the use of the optimum matching algorithm between a recognized phoneme string and the representative one in the word dictionary. We propose an effective tree search method of parsing when the results of phoneme recognition and word identification are not error free. LITHAN uses many types of a priori information; the statistic of each phoneme; the similarity matrix between phonemes; the word dictionary; the spoken grammar with the additional information as regards the spoken grammar; the semantic and pragmatic information. We have applied this efficient, flexible system to restricted utterances with vocabulary of about 100 words which concerned with operational commands and queries of the status of a computer network. According to the results tested on a sample 200 sentences spoken by 10 male speakers at a normal speed, 64% of the sentences and 93% of the output words were correctly recognized.

Atmospheric refractivity gradient in the vicinity of the equator were analyzed, based on the radiosonde data in Indonesia and Singapore. Further study was made for estimation on the variation of refractivity gradient in the South-East Asian area, by means of combining with the results in and around Japan.

As a new method to improve pulse code modulation properties of semiconductor lasers, optical feedback is proposed where a part of the light output from a modulated laser is fed back into itself, with a time delay considerably less than one relaxation oscillation (RO) period. Rate equation approach is applied to investigate the modulation characteristics. Modulation bit rates for small pattern effects depend on the RO period and the current pulse width, and they appear discontinuously. By optical feedback, the RO period increases, and it becomes possible to decrease pattern effects at any given modulation period, if it is larger than the RO period without optical feedback. For current pulses with a short duration, output waveforms are improved by optical feedback through increase in the first RO spike width and elimination of its second spike. In preliminary experiments, using GaAs-AlXGa1XAs double heterostructure lasers with a combination of a microlens and a flat mirror, qualitative agreements were obtained between theoretical and experimental results. Improvements in the modulated output waveforms were observed for PCM-RZ pulses at up to 500 Mb/s.

Anomalous re-entrant hysteresis loops and maximum of the coercive force have been found near 130 K in polycrystalline GdIG ferrite. A qualitative explanation of the observed phenomena is given. It is suggested based on the Snoek's model of magnetic after effect that Fe2 ion may be responsible for pinning the domain wall.

Several basic properties of minimum-comparison selection algorithms are shown, and some exact values are obtained for Vt(n) for small n, where Vt(n) denotes the number of comparisons necessary to select the t-th largest of n elements. The upper bound for V5(10) is reduced to 16. Those results improve the table of the best upper bounds known for Vt(n) in the Knuth's book (Sorting and Searching).

This paper considers a 2-dissimilar unit warm standby system. The failure rates are constant but the repair rates need not be constant. We shall say that a major breakdown occurs in the system when both unit fail. The system fails if one unit under repair is not repaired within a fixed time measured from the instant at which major breakdown occurs, or if the number of major breakdowns during the mission period exceeds a fixed number. As a special case, this number is allowed to be infinite". The Laplace transform of the reliability and the mean time to system failure (MTSF) are derived. The special case of constant failure and repair rates is treated. We present the asymptotic results which describe the performance of system with short mean repair time. Also the case when allowed down time is negligible, compared to the mission time, is discussed.