Effect of the shape of contact surface on the contact resistance property of contaminated surface was examined in conjunction with the radius of curvature of the hemisphere contact surface. As the results, the dependence of the radius of curvature on the contact resistance was found. And the existence of the radius which gives maximum contact resistance was also found.

Anodization behavior of Al/Mo/Al multilayer films is studied by the method of depth profiling with Auger electron spectroscopy. The leaving out of the molybdenum layer by the drastic transport is observed. The results are discussed on the basis of the mobility of molybdenum cations.

The accumulated metallic phase arc duration in Ag electrical contacts was log-proportional to the amount of electrode mass change, and the relationship was irrespective of the air pressure condition. It can be considered that the electrode mass change closely depends on the metallic phase arc.

Holographic pattern measuring system (HPMS) which has been developed by the authors as applied to measure a thermal deformation of contact spring due to current flow. As the results of investigations, a microscopical rolling of contact point was clarified and a relationship between the changing spring shape and the contact voltage was qualitatively mode clear.

Relationships between temperature and specific gravity of methanol solution of urea were measured under various concentration. Solubility and supersolubility curves to methanol were obtained. It was found that methanol is relatively suitable as solvent to the growth of urea crystal.

This letter presents the results of Auger analysis of surface products by steady arc on Ag/Pd contacts. Black products formed on Ag contact surfaces, which make contact resistance high and unstable, are silver oxide. In the case of Pd contacts, contact resistance of which remains low and stable, white-colored products seen after operations seem to be powdery palladium.

This letter describes the occurrence-frequencies of the microarcs in the carbon sliding-contacts which are known to give the low radio-noises. A method is presented for statistically evaluating the arc occurrence-frequencies. The measurement results are also shown.

This letter presents a new method of estimating the discontact rate of the pantograph using the noise currents in arc discharges, which is independent of the BPF overlapped responses that give large estimation error for the previous methods. The validity is confirmed experimentally.

Y-Ba-Cu-O films sputter-deposited at about 650 in high oxygen concentration gas are superconductive without heat treatment after the deposition. The films of 700 nm thickness have T_{c end} of 72 K on SrTiO₃ and 65 K on sapphire substrates. Reduced interdiffusion, compared with post-annealed films at high temperatures, between the film and the substrate is confirmed.

An electron-wave device consisting of a hot electron transistor structure with a transversal potential grating in a base region is proposed. A reduced transit time and extremely small charging times provide significant potential for high-speed operation.

The high performance and versatile electronic volume IC has been realized by the 15 V high voltage Bi-CMOS process. Mixed use of bipolar and MOS devices has introduced new functions such as buffer amplifiers, a low level oscillator, a temperature compensated D/A converter and a reference voltage generator.

Gallium nitride single crystals were grown on (0001) oriented sapphire substrates by metalorganic vapor-phase epitaxy. The films on the initially nitrided sapphire surface showed an uneven surface with prominent hexagonal pyramids, while the films on the non-nitrided sapphire surface exhibited a relatively smooth surface although some fine pits were observed. All the films exhibited n-type conduction with carrier concentrations of 10¹⁷-10¹⁸ cm^-3 and electron mobilities of 30-143 cm²/V sec.

Using an improved calculation method, the transmission coefficient of a quadruple barrier resonant tunneling diode is calculated. Using this result, extreme values of the transmission coefficient and the full widths at half maximum (FWHM) of the resonant peaks are calculated. It is shown that the first terms of the expressions |θ|, which are proportional to the FWHM, are given by the same formula in double, triple, and quadruple barrier diodes.

We fabricated a-Si: H thin films outside the microwave discharge plasma and we varied the substrate bias to investigate the effect of ion bombardments of the film surface. Dark conductivity of the film decreases with increasing negative bias of the substrate with no dependence on the substrate temperature.

Axisymmetric modes of axisymmetric resonant cavities are studied by using the hybrid boundary element method (H-BEM). We can see that H-BEM solutions have high accuracies from comparison of numerical solutions with exact solutions. It is shown that H-SEM is useful to study axisymmetric modes of axisymmetric cavities.

A 5λ/2 rat-race-type directional coupler for arbitrary power divisions with high isolation and a method of improvement on its matching bandwidth are described. A close agreement between the theoretical and measured scattering parameters is observed also.

Three methods to compute the electromagnetic characteristics of square-opening meshes of finite thickness are numerically evaluated. The mode matching method is precise but time-consuming. Error bounds of the two expedient methods--single-mode matching and equivalent circuit methods--are presented in terms of mesh parameters.

In order to effectively solve a three-dimensional unsteady convective diffusion equation, kernel approximation is introduced into the boundary integral procedure in the boundary-element method. It is shown that the present method gives a good approximate solution of the convective diffusion equation in case of not a dominant convection. Also, we find that very fast numerical integration can be carried out on supercomputers.

A simple approximation method to calculate scattering from a grid with straight strips of finite size (the equivalent grid method) was proposed by the authors. This method can deal with arbitrarily polarized incidence with arbitrary plane of incidence. In this letter, the applicability of this analysis to the scattering from a grid with curved strips is demonstrated by experiments.

Thermal properties of InGaAlP laser diodes have been analyzed by computer simulation. Self-consistent analysis considering heat conduction, current distribution and optical waveguide mode has made it clear that there exist optimum structural parameters minimizing the threshold current.

A new type of a dynamic-single-mode laser, which has distributed reflector (DR) both in active and passive regions, is proposed and analyzed to attain high output efficiency with the superior single mode property without increase of threshold current density.

Optical characteristics of the Bragg filter fabricated with a Ta₂O₅/SiO₂ optical waveguide are studied. The Bragg reflector was formed by the holographic method using an He-Cd laser. Filter responses were measured with the color-center laser and the stopband bandwidth was found to be 3.5 Å.

The Dynamic Readout performance of a micro-optical head, consisting of a semiconductor laser on a flying slider and a glass substrate disk medium has been examined. An antireflection coated (ARC) laser diode, whose reflectivity facing a medium, is less than 5%, is useful in decreasing signal amplitude fluctuation due to the head-to-medium spacing.

A three-parallel thin-film waveguide is analyzed numerically, using mode-matching method that matches the boundary conditions in the sense of least squares. The precise numerical results of the dispersion relations and field distributions are presented for the lowest three hybrid modes.

The purpose of this research is to improve the process and the characteristics of computer generated hologram (CGH). In this paper we propose the method of the direct laser recording of CGH (DLR-CGH). At first we construct the direct laser recording system. Then we consider the most suitable hologram coding and scanning scheme for DLR-CGH. It becomes clear that the process of making CGH is considerably reduced by this recording system.

Light intensity variation is performed in a multilayer optical circuit element consisting of stacked crossing thin film optical waveguides. The principle of operation is the interference of two guided light waves coupled with each other at the intersection of the waveguide of the optical circuit element. Measurements are carried out for each case of the coupling coefficient of the optical circuit element equal to 3 dB and not equal to 3 dB. The percentage variation obtained is 45%.

A multimode variable directional coupler has been fabricated by piling up films. It uses an electrostrictive element. The output powers can be continuously controlled over a wide range. The output powers from the two output ports of the coupler were equalized at a stress of 16.8 kg/cm², and the loss due to the stress was small (0.19 dB).

This letter reports the 10 ns (100 MHz) optoelectronic memory utilizing the mode-hopping phenomenon of a semiconductor laser. The hysteresis (wavelength bistability) features hold even at the speed of nanosecond. Some influences of VHF current modulation on mode-hopping are also measured.

A plastics such as polycarbonate take a graded birefringent orientation when a high dc ununiform electric field is applied to its molten phase. This ununiformity is maintained even in a solid phase after decreasing the temperature. Therefore, the plastic plate operating as a variable retardation plate is easily and inexpensively fabricated by using this bulk plastics with graded birefringence.

The design practice of resonant electrodes is reported for guided-wave light modulators using coplanar waveguide electrodes. A matching stub built with the resonator provides compact structure and satisfactory electrical performance. It is notable that the wide-gap resonator electrode yields the decrease in driving power.

An interferometric method for measuring frequency deviation of semiconductor lasers in wide range of modulation frequencies has been developed. Fringe visibilities of an interfered IM- and FM-modulated light depend on frequency deviation, time delay difference and intensity modulation depth. The applicability of this method has been also discussed.

A heterodyne interferometer utilizing a light source with short coherence length has led to a significant improvement in distance resolution of an optical reflectometer. The resolution less than 1 cm along a fiber is easily achieved by a Fabry-Perot type diode as a short coherence length source.

A simple length measuring method for single mode fiber coiled around a drum using Sagnac effect, is proposed. Phase difference variation caused by rotating the coil is measured, and fiber length can be derived by processing the measured results. Typically, a length measurement accuracy of 1% is obtained.

An experimental relationship between byte-organizations and byte-error characteristics for optical disks is discussed. A two-dimensional byte-organization is proposed to decrease byte-errors, based on measured results. This byte-organization is effective in parallel-track recording.

A performance evaluation of various sector alternation methods for optical disks is discussed. The alternation frequency and defect-proof effects are described quantitatively for alternation methods. This evaluation makes it clear that the group alternation method of the on-the-fly alternation methods is suitable for high speed data processing operations.

This letter describes a magnetic sensor using a parametric oscillation of a RLC parallel circuit. It is shown that the sensing output voltage of the proposed sensor is proportional to the input and constant against the frequency.

This letter describes the comparison of the impulse force detection method for a head slider and a disk medium using a small piezoelectric transducer (PZT) stuck on the head slider, with the method using visible laser interferometry. The experimental results for the signal level of the PZT agree very well with the acceleration measured from laser interferometry method. There is also good agreement between the spectrum of signal output of the PZT and laser interferometry, when the head slider flies over a rectangular bump made on a glass disk.

A method is proposed to detect the surface wave propagation direction on the outer conductors of the transmission lines in cable systems, by means of a probe having a property of a directional coupler.

It was clarified from the traveling-wave analysis that the output power from the injection-locked oscillator becomes smaller as the injection power increases. The objective of this letter is to confirm this principle of the injection-locked oscillator by using the phase-plane approach.

This letter presents a method for real-time visualization of static electricity distribution which can be achieved by rapidly measuring the voltages induced on the array electrodes. For verifying the validity of this method, the measurement examples on the charged sheets are demonstrated.

For the effectively therapeutic conditions of laser acupuncture, as a first step, this letter examines the thermal stress inside the skin tissue produced by laser acupuncture. A method is presented of calculating the 3-dimensional thermal stress. The numerical results are also shown.

The advantage of nonstandard quantum states such as two-photon coherent state (or squeezed states) and photon number state as transmitter state is strongly degraded by transmission loss in quantum communications. To cope with such a problem, a new application of these states is proposed, and it is shown that its system has infinite capacity.

High-speed retiming circuit using a dielectric resonator filter are proposed. An active band-pass filter with a dielectric resonator filter suppresses the dielectric resonator filter's inherent higher resonance modes and successfully extracts an 8-GHz timing clock.

Switched-Capacitor (SC) low-pass ladder filters based on the LDI transformation, have been successfully designed using the Lossless Discrete Integrators (LDIs) as their basic building blocks. However, the design of highpass ladder filters with the LDIs are not straightforward as the low-pass or bandpass case. On the other hand, a high-pass design is achieved easily by using a differentiator as the building block, instead of an integrator. Thus, a new design technique of Switched-Capacitor Modified Lossless Discrete Differentiators (MLDDs) is proposed in this paper. By using them as the basic building block, SC high-pass ladder filters are directly constructed based on the low-pass to high-pass transformation. Furthermore, a fully-differential architecture is applied to this MLDD design, and some MLDD alternatives are investigated for high-frequency and time-sharing applications.

With the development of LSI technologies, conventional circuit simulation using only single type of method has become unsatisfactory, i.e. circuit-level analysis based on device model spends much simulation time and relaxation methods have the problems on their accuracy. Therefore, it is necessary to develop the better methods to realize both high-speed and good accuracy. In this paper, a mixed-mode circuit-timing simulation method has been studied. It uses a new kind of automatic circuit partition approach--dynamic circuit partition process based on checking coupling factors between circuit nodes at every time point for better convergence. This method is based on examining the characteristic of circuit equations rather than circuit topology or function blocks. A mixed-mode simulation program--MMAPC for transient analysis of CMOS large-scale circuit has been developed and some simulation examples have been performed. The results show that MMAPC can be more than two orders of magnitude faster than a standard" circuit-level simulator (SPICE-like) while providing comparable waveform accuracy, and has better convergence property than general timing-level simulators.

Reliability of single-loop networks can be improved using double loops: forward loops advancing to the neighboring node and backward loops skipping by a certain distance. In this type of double loop networks, when some nodes break down, there exist possibilities that a message can not be transmitted to some nodes and many messages concentrate on some specific nodes to take a roundabout route. Then, the delay may happen in date transmission. These phenomena depend on the situation of faulty nodes. This paper, first, presents a routing algorithm to find a route where a message can be transmitted to the destination node when a multi-node failure arises. Next, the upper bound of transmission steps required to transmit n packets in parallel from respective starting nodes to respective destination nodes is investigated.

A novel flexible ferrule only 0.8 mm in diameter is proposed and demonstrated as a key element in optical fiber connectors. Miniature aggregated multiple fiber connectors with a fiber pitch of 2-5 mm are possible with this Flexible Fine ferrule" (FF-ferrule). This paper presents the fundamental concept of the FF-ferrule. Then, ferrule bending characteristics, a distinctive mechanical feature of this ferrule, are discussed in detail both theoretically and experimentally. The method of designing the FF-ferrule is also described based on the theoretical results. A prototype FF-ferrule was made by precision transfer molding. Connection loss was as small as 0.6 dB, because the ferrule bending can compensate for axial misalignments up to 0.5 mm. In addition, 20% of the measured connections showed a connection loss of less than 0.3 dB. The high pressure contact from the small cross-section of the ferrule makes physical contact" between the endfaces of the fiber.

In this paper, we introduce the concepts of multi-node and mono-node to expand the expansive graph grammar given by Shi and Fu to a larger family, the family that contains all rooted acyclic directed graphs. Shi and Fu's approach deals with rooted acyclic digraphs containing only mono-nodes. The ways of numbering and representing rooted acyclic directed graphs are modified and grammars for such graphs are given so that directed graphs containing even multi-nodes can be treated. Parsing algorithms are also given which are described with State-Space representation. Our algorithms are as efficient as those of Ref.(6). We have removed a constraint that the basis graph must be a tree from the expansive graph grammars of Ref.(6) without increasing the space or time complexity of numbering, rewriting and parsing.

Two fast parallel sorting algorithms on a mesh-connected model are described. These algorithms are some combinations of row and column sorts, and use just the compare-exchange as their basic operation. The computing time of the first algorithm for sorting n² items is 6.5n+2 log n-5 steps and the computing time of the second one is not more than 5.5n+0.5 log n+0.5 +1.5 log n-3 steps. The control structures of these algorithms are particularly simple. The correctness of the algorithms are proved in a lucid way by using a function POTENTIAL. The function evaluates the exact number of steps to sort items by parallel bubble sort.

Expansive graph grammar is one of the suitable tools for describing pattern structures in syntactic pattern recognition. To describe the numerical features of patterns and relations among them simultaniously with pattern structure, in this paper we show with expansive graph grammar: (1) how to describe the dependent relations among attributes of (sub) patterns with the concepts of inherited and synthesized attributes, (2) how to describe conditions supposed to be satisfied by attributes of patterns with the concept of predicate. An interpreter for such processing is presented based on the Problem-Reduction Representation (PRR). Some features of the method and the interpreter are discussed. It is showed that the method introduced in this paper is suitable for describing patterns in scene analysis when numerical features of patterns are considered.

An approach for parallel processing of test-pattern generation for combinational circuits is described. In general, difficulty in test-pattern generation lies in two points; how to deal with a large number of faults, and what to do with faults that are hard to generate their test patterns. These problems can be resolved in a parallel-processing environment on a variable number of processors. Test-pattern generation is shown to be a good application of parallel processing techniques. The proposed method has been implemented on a multi-microcomputer system called LINKS-1 in order to estimate its performance. The results show that the proposed parallel processing method can get a high parallelism and achieve a high degree of acceleration of test-pattern generation.