To study material dispersion effects on transmission characteristics in optical fibers, material dispersion properties in GeO₂-P₂O₅-doped silica optical fibers were determined as a function of GeO₂ doping concentration. The material dispersion properties were evaluated from pulse delay measurement with nanosecond pulses in a 0.60-1.65 µm spectral region generated by a nanosecond optical pulse radiator. From the measured delay, refractive index of core glass, material group index, material dispersion, zero-material-dispersion wavelength and zero-dispersion wavelength in a single mode fiber have been determined as a function of GeO₂ doping concentration in the range 4.1 to 19.2 mol %. By extrapolating present data in GeO₂-P₂O₅-SiO₂ ternaries, material dispersion properties in fused GeO₂ glass have been predicted. The zero-material-dispersion wavelength in fused GeO₂ glass can be estimated to be 1.68 0.03 µm.

The m-center problem asks to place m objects on the plane so that the distance from a client (a point) to the closest object is at most a given number r. This problem is often encountered in locating facilities or resources of a geographically distributed system. This paper shows that this problem is NP-complete. The NP-complenteness indicates its computational intractability, i.e., it is most unlikely that some algorithm can solve it in polynomial time of the problem size.

Dependence of GaAs power MESFET performance on the device parameters was experimentally investigated. Power gain and output power were most sensitive to the gate length, giving the degradation rates due to increase of the gate length of 1.7 dB/µm for the power gain and 0.67 dB/µm for the output power. The effect of the gate finger width on the microwave performance was not serious and the performance deterioration at 8 GHz did not begin until the gate finger width of 200 µm. Temperature dependence of the microwave performance of GaAs power MESFET, as well as the dependence of the thermal resistance on the device geometric parameters, was investigated quantitatively. Power gain degraded with increase of the device temperature with the rate of 0.026 dB/.

This paper shows an experimental approach to the understanding system of natural language and pictorial patterns. The system is titles as ISOBAR (an Information understanding System Of BAsic weather Report). It can accept both linguistic and pictorial inputs. Also it produces either linguistic or pictorial, or both, output according to the commands which it received. The most remarkable point of the system is that the performance of the system is based on the semantic processing of the input. As ISOBAR's world is limited within the weather report of Japan and Far East Asian areas with associated weather charts, so the semantic background of the system is very narrow, and is quite a specific one. But the methodologies and algorithms in the system will be the first step for the embodiment of the more complicated and more general systems. ISOBAR has two operating modes in principle. One is the accumulation of meteorological information, and the other is its retrieval. According to the experimental outcomes, the performance of the system is almost good except for the picture processing procedures. Finally, the problems for the future research are remarked.

In this paper, a partial matching problem among pictures composed of multiple closed regions is described by taking a sequence of animation pictures as an example. Closed regions including holes and islands are analyzed and described by a set of edges specified by angles, positions, trailing and leading vectors. Then, a kind of relaxation methods is used to make partial matchings between the preceding picture (template) and the current picture through global and local matching processings. This method was applied to a sequence of cel animation pictures drawn manually, and as the results, more than half of closed regions included in pictures were identified correctly.

A Josephson computer device called a carousel SQUID is proposed which uses an interferometer capable to be used as both a memory cell and logic gate. The principle of the operation of carousel SQUIDs is the rotation of a fluxoid quantum in the device, which makes the device to have excellent performances as computer ones. The memory cell stores one fluxoid quantum and is non-destructive read-out one. For the logic gate, the current gain is much larger than unity and input signal is isolated from the logic gate.

A left identity type automation is defined as a finite automation whose transformation semigroup has a left identity. In this paper, we give a necessary and sufficient condition for a given automaton to be of left identity type in terms of the generators of its transformation semigroup.

It is shown that we can simultaneously make both of Zech's logarithm table and trace table in a finite field by using a feedback shift register which generates a pseudo-random sequence. Convenient method for the initial loading of the feedback shift register is given.

This paper describes an optical demultiplexer whose diffracted light beams are directly detected by a monolithic linear array of six silicon pin photo-diodes for the 0.8 µm wavelength region. The demultiplexer has 6 channels whose wavelength spacing is 23 nm. Insertion losses and crosstalks were less than 2.1 dB and -25 dB, respectively.