Showing papers by "University of Electro-Communications published in 1985"
TL;DR: In this article, surface fatigue crack studies were carried out and statistically analyzed from rotating bend fatigue tests in the high cycle region for three metals, copper, stainless steel and mild steel with four ferrite grain sizes.
Abstract: Surface fatigue crack studies were carried out and statistically analysed from rotating bend fatigue tests in the high cycle region for three metals, copper, stainless steel and mild steel with four ferrite grain sizes. Quantitative observations of the initiation and growth behavior, including coalescence of closely spaced cracks, are discussed and a limiting condition for coalescence is proposed. Statistical properties of initiation, propagation and propagation rate of surface cracks are examined and the effect of different metals and grain sizes is discussed.
65 citations
TL;DR: An explicit detailed analytic description of a cusp catastrophe in a computer communication system is given and an approximate model is formulated for a slotted Aloha system assuming a single buffer, based on the Markovian model studied by Lam and Carleial.
Abstract: We develop a new tool for performance evaluation of a multiaccess communication system. We give an explicit detailed analytic description of a cusp catastrophe in a computer communication system. An approximate model is formulated for a slotted Aloha system assuming a single buffer, based on the Markovian model studied by Lam [2] and Carleial [3]. Next, we outline the research on quantitative processing of thrashing and its results. Sudden changes, which can be observed in the throughput rate, the average delay, and the average number of backlogged users, are induced by smooth alterations of control parameters in the behavior of a slotted Aloha system. These catastrophic phenomena, such as long lasting periods of vanishing throughput rate and very high delays, are analyzed in line with catastrophe theory. The system behavior in a slotted Aloha system is characterized by the cusp catastrophe. In particular, introducing a new parameter σ in our model, we make it clear why and in what cases these catastrophic phenomena occur. The amount of change is also estimated.
54 citations
TL;DR: In this article, the authors present an effective modal analysis method for a class of recently developed optical fibers with multiple cores, which combines the point-matching procedure with group theory to solve such complicated boundary value problems.
Abstract: The purpose of this paper is to present an effective modal analysis method for a class of recently developed optical fibers with multiple cores. The main feature of the method is to combine the point-matching procedure with group theory to solve such complicated boundary value problems. The results of the numerical computations are compared with those of microwave simulation experiments.
41 citations
TL;DR: In this paper, a new reaction of triplet xanthone, hydrogen abstraction by a benzene ring, was found in the reactions with triethylgermane and sodium borohydride.
38 citations
TL;DR: In this paper, a hydrodynamical model is developed to analyse the vibration of a liquid drop on a horizontal bed, where the fluid is assumed inviscid and to move nearly horizontally, so that the shallow water theory is applied.
Abstract: A hydrodynamical model is developed to analyse vibration of a liquid drop on a horizontal bed. The drop has a flattened shape by the gravity and the surface tension. The fluid is assumed inviscid and to move nearly horizontally, so that the shallow water theory is applied, and a set of governing equations for the vibration is derived. It is applied to a small-amplitude oscillation and a normal mode solution is obtained, where the drop shows a standing wave along its periphery. The predicted vibration frequency agrees with the experiment by the present authors.
36 citations
TL;DR: In this article, SiO2, W and W/SiO2 masks were applied as masks for the selective epitaxial growth of GaAs by metalorganic chemical vapor deposition (MOCVD).
Abstract: Films of SiO2, W and W/SiO2 have been applied as masks for the selective epitaxial growth of GaAs by metalorganic chemical vapor deposition (MOCVD). The deposition selectiveties on SiO2 masks are mainly due to a difference in the absorption coefficients of reactant species between SiO2 and GaAs, while those on W masks are due to the surface migration of reactant species. Reactant species migrating on the surfaces of W masks are (finally) used in the epitaxial growth of opening windows, and selective epitaxial growth maintaining mask surfaces completely free from deposition have been attained for samples in which mask patterns are narrower than 40 µm.
35 citations
TL;DR: In this article, the magnetic field strength at the fundamental frequencies 50Hz and 60Hz, of power line radiation in the topside ionospheric region has been observed by the instrument aboard the satellite “OHZORA” in the global area.
Abstract: The magnetic field strength at the fundamental frequencies 50Hz and 60Hz, of power line radiation in the topside ionospheric region has been observed by the instrument aboard the satellite “OHZORA” in the global area. The observation has started on June 1, 1984, in order to measure the magnetic field strength of the power line radiation in the topside ionospheric region over the eastern Asia. The observation instrument consists of a loop antenna and a receiving unit, which can receive the fundamental frequencies (50 and 60Hz) of power line radiation by means of three narrow-bandwidth filters. It is identified that the origin of the background noises of magnetic fields observed at these frequencies is due to the ELF hisses propagating from the outer plasmasphere. By means of the statistical procedure, the background noise field strength at 50 or 60Hz can be determined in comparison with the strength at 55Hz. If the magnetic field strength is higher than the level of ambiguity, the corresponding position can be specified as the reasonable position of power line radiation. According to the result of observation, the power line radiation at 60Hz radiated from the Japan Islands seems to spread over the wide area. The observation results also show that the power line radiation over the eastern China reveals a correlation between the statistically reasonable positions of magnetic field strength at 50Hz and the possible distribution of power lines on the ground.
27 citations
TL;DR: In this paper, the authors discuss the economics of job shop production under Poisson order-arrival and present an operational basis for job shop control, which consists of job orders with marginal profits, selection function with backlog, and a production centre with fixed capacity.
Abstract: Under Poisson order-arrival, this paper discusses the economics of job-shop production by a policy approach, and presents an operational basis for job shop control. The model consists of job orders with marginal profits, selection function with backlog, and a production centre with fixed capacity. For the two main policies, PSP and DSP, this model is formulated by semi-Markov decision processes, and the operation rate, mean shop-time and reward rate (including idle cost) are obtained. Finally, the relationship of ‘six order-selection policies is given, and the structure of optimal policies is suggested.
20 citations
TL;DR: In this paper, the authors applied the theory for the stress and electric fields produced by moving dislocations in an anisotropic piezoelectric crystal (Phil. Mag. A, 51, 277-285) to calculate the electric fields generated by a uniformly moving infinite straight dislocation in lithium tantalate, bismuth germanium oxide, and zinc oxide.
Abstract: The authors' theory for the stress and electric fields produced by moving dislocations in an anisotropic piezoelectric crystal (Phil. Mag. A, 51, 277-285) is applied to the calculation of the electric fields produced by a uniformly moving infinite straight dislocation in lithium tantalate, bismuth germanium oxide, and zinc oxide.
19 citations
TL;DR: In this article, an enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented.
Abstract: An enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented. When a plume of nitrogen gas was injected from the orbiter into space, a large amount of plasma was detected by an onboard plasma probe. The observed density often increased beyond the background plasma density and was strongly dependent on the attitude of the orbiter with respect to the velocity vector. This effect has been explained by a collisional interaction between the injected gas molecules and the ionospheric ions relatively drifting at the orbital speed.
17 citations
15 Feb 1985
TL;DR: In this paper, the lowest excited nπ* triplet of 9.10-anthraquinone, 1.4-naphthoquinone and 1,4-benzoquinone were studied in glassy matrices at 77 K using a time-resolved ESR method.
Abstract: The lowest excited nπ* triplet of 9.10-anthraquinone, 1.4-naphthoquinone and 1,4-benzoquinone were studied in glassy matrices at 77 K using a time-resolved ESR method. The D value of the triplet state of 9,10-anthraquinone varied from −0.351 cm −1 in a polar solvent to −0.318 cm −1 in a non-polar solvent. Both 1,4-naphthoquinone and 1,4-benzoquinone in polar solvents showed triplet state spectra with a D value of −0.330 cm −1 . A computer simulation revealed the existence of widely distributed zero-field splitting parameters in the glassy condition. These data are compared with an analysis of CIDEP results of para-quinones.
TL;DR: The purpose of this paper is to demonstrate a general technique of the selective labeling of internal energy levels for the analysis of thermal collision processes between neutral molecules using laser-induced fluorescence technique.
Abstract: The purpose of this paper is to demonstrate a general technique of the selective labeling of internal energy levels for the analysis of thermal collision processes between neutral molecules. Laser is undoubtedly one of the most powerful tools for this purpose. Number of studies have been reported on the internal state distribution of molecules after collision using laser-induced fluorescence technique (LIF). However, it is rather difficult to label individual energy level of molecules before the collision. An electronically excited state can be selectively pumped by direct transition using tunable lasers. For vibrationally and rotationally excited states, prohibitive number of lasers are necessary to change large quantum number by direct pumping. An alternative method is to pump out thermal population, which is applicable only for low-lying levels. We have demonstrated folded two photon process via an electronically excited state can be used to pump selectively a vibrationally excited level of a molecular beam [1,2]. This technique can be applied for a wide range of molecules, because the selection rule on vibrational transitions Δv=1 does not apply if the potential surfaces of the excited and ground electronic states have different shape.
TL;DR: In this article, it was shown that the nonselective character of transitions arising from the short range of the interaction between the high-Rydberg atoms and the rare-gas atoms is strongly modified in the following two cases.
Abstract: State changing of high-Rydberg atoms by collisions with rare-gas atoms have been theoretically investigated using the free-electron model. The non-selective character of transitions arising from the short range of the interaction between the high-Rydberg atoms and the rare-gas atoms is found to be strongly modified in the following two cases. First, for the high-Rydberg atoms in the circular states with | m |= l ≃ n , it has been found that transitions take place overwhelmingly between the circular states. This propensity rule originates from a highly anisotropic electron-density distribution of the initial circular states. Second, for the high-Rydberg states with large quantum defects (modulo 1), suppression of the yield of the lower angular momentum states have been observed. This cancels out the fair enhancement of the production of the high-Rydberg states with small | m | seen for the hydrogenic case with small quantum defects. It leads to the m distribution of the final states apparently proportional...
TL;DR: The paper places five different problems (thek-pebble game problem, two problems aboutk finite automata, the reachability problem for Petri nets withk tokens, and the teachable problem for graphs whose “k-dimensional” edge sets are described by Cartesian products ofk factors) into the hierarchyNLk of problems solvable by nondeterministic Turing machines ink-log2n space.
Abstract: The paper places five different problems (thek-pebble game problem, two problems aboutk finite automata, the reachability problem for Petri nets withk tokens, and the teachability problem for graphs whose “k-dimensional” edge sets are described by Cartesian products ofk factors) into the hierarchyNLk of problems solvable by nondeterministic Turing machines ink-log2n space (and binary tape alphabet, to avoid tape “speed-up”). The results, when combined with the conjecture thatNLi contains problems that requireO(nk) deterministic time, show that these problems, while inP for every fixed value ofk, have polynomial deterministic time complexities with the degree of the polynomial growing linearly with the parameterk, and hence are, in this sense, “gradually intractable.”
TL;DR: A practical method for representing Turner Combinators is presented, which needs only O(n log n) space in the worst case for translating lambda expressions of length n, which should be contrasted with Burton's proposal.
01 Jan 1985
TL;DR: In this paper, a planar-structure acoustic lens for the acoustic microscope is presented, whose width and diameter are designed according to the theory of Fresnel zone plate, which can be easily fabricated using the conventional photolithographic technique.
Abstract: In most of the scanning acoustic microscope (SAM), an acoustic lens with a spherical concave 1s used for focusing the sound beam on a small portion of an object to be imaged Since the acoustic microscope operates in a very high frequency range such as VHF and UHF, the tiny spherical lens requires to be fabricated with very high accuracy by a skillful technician Therefore, it is desirable that the spherical lens in the acoustic microscope could be replaced by an alternative one, of which the fabrication is much easier This paper presents a new planar-structure acoustic lens for the acoustic microscope On the radiation surface of the lens are formed a number of concentric annular grooves of uniform depth, whose width and diameter are designed according to the theory of Fresnel zone plate This planar lens can easily be fabricated using the conventional photolithographic technique because of its simple configuration with no spherical surface The lens design and the principle of operation are described, along with the experimental and theoretical evaluation of the focusing capability of a fabricated lens operating at 100 MHz
TL;DR: In this article, the steady state behavior of computer networks employing random access schemes is analyzed in a unified manner in line with the catastrophe theory, where stability can be considered from an analysis of the bifurcation set which gives the necessary and sufficient condition that the system is either monostable or bistable.
Abstract: The steady state behavior of computer networks employing random access schemes is analyzed in a unified manner. The basic model of computer networks is introduced and analyzed in line with the catastrophe theory. The global behavior of the system is determined by the cusp catastrophe. Stability can be considered from an analysis of the bifurcation set which gives the necessary and sufficient condition that the system is either monostable or bistable. The analysis is applied to the pure Aloha, the slotted Aloha, the carrier sense multiple access (CSMA) and the carrier sense multiple access with collision detection (CSMA/CD), with the immediate-first-transmission (IFT) and the delayed-first-transmission (DFT) protocols. Several numerical examples are given to demonstrate the usefulness of the unified analysis developed.
TL;DR: The photochemical reactions between nπ * triplet benzophenone and N,N-diethylaniline have been studied by the CIDEP method in both polar and non-polar media.
01 Jan 1985-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: An automatic calibration system of polygon mirrors that depends on the self-checking method, so that both the polygon mirror and the standard rotary scale are calibrated simultaneously, to detect slight angular difference with high resolution.
Abstract: An automatic calibration system of polygon mirrors is described. This system consists of the four subsystems: a precise rotary mechanism, a rotary magnetic scale for angular standard, a special photo-electric autocollimator which enables dynamic measurement, and a mini-computer system which controls the compiling and handling of data. The basic principle of the system depends on the self-checking method, so that both the polygon mirror and the standard rotary scale are calibrated simultaneously. A time-conversion method is adopted to detect slight angular difference with high resolution. By way of an example, the calibration of a 12-sided polygon is described. The results obtained are as follows: (1) The calibration can be done automatically in a short time without skill, except for the manual operation of setting a polygon relatively for the magnetic scale; (2) 95% confidence interval of instrumental error calibrated on the system is within ±0.07 seconds of arc.
TL;DR: In this article, the elastic modulus calculated from the crack length is far below the shear modulus C 44 of unirradiated pyrolytic graphite, which implies that these cracks and blisters correspond to the grain boundaries and etch pits, respectively.
TL;DR: Based on the weakest link model and linear elastic fracture mechanics, an equation of the defect detection probability PD is derived theoretically as discussed by the authors, assuming that the fracture strengths before and after repair of the detected flaws both follow two-parameter Weibull distributions.
TL;DR: In this article, the authors investigated the glow discharge plasma of SiH4−NH3 mixture by CARS and found that the decomposition rate of NH3 is linearly dependent on SiH 4 partial pressure but that of Si H 4 is not affected by the mixing ratio.
Abstract: We have investigated the glow discharge plasma of SiH4−NH3 mixture by CARS. The decomposition rate of NH3 is linearly dependent on SiH4 partial pressure but that of SiH4 is not affected by the mixing ratio.
TL;DR: In this paper, the optical and electrooptical properties of hot-pressed ceramics of the ternary systems xBa(La 1/2Nb1/2)O3 and Pb(ZryTi1-y)O 3 have been investigated.
Abstract: Hot-pressed ceramics of the solid solution in the ternary systems xBa(La1/2Nb1/2)O3–(1-x)[Pb(ZryTi1-y)O3] show excellent optical and electrooptical characteristics, comparable to PLZT. Linear and quadratic electrooptical coefficients, rc and R, are determined for more than ten specimens of various compositions near the morphotropic phase boundary between the tetragonal and the rhombohedral phases and maximum values of rc=10.73×10-10m/V and R=12.0×10-16 m2/V2 are observed. Dielectric and electromechanical measurements along with X-ray analysis are also carried out to determine the phase diagram.
TL;DR: In this article, a simple layer model was proposed in which real atomic configurations were simulated by multi-layers with homogeneous electron density on each layer, in order to investigate work function of alkali-atom adsorbed graphite.
Abstract: We propose a simple layer model in which real atomic configurations are simulated by multi-layers with homogeneous electron density on each layer, in order to investigate work function of alkali-atom adsorbed graphite. Charge transfer from an alkali-atom layer to graphite layers is determined within the model by minimizing total energy. The calculated decrease in work function of graphite upon alkali-atom adsorption agrees satisfactorily with the experimental data.
TL;DR: In this article, a simple elliptical Abel inversion for calculating spatial distributions of electron density from elliptical shaped plasma is presented, which is applied to an end-on holographic interferogram of a θ-pinch plasma for the first time.
Abstract: A new and simple elliptical Abel inversion for calculating spatial distributions of electron density from elliptical shaped plasma is presented. In this numerical method inversion matrix elements were calculated analytically and examined using a test function. This method was applied to an end-on holographic interferogram of a θ-pinch plasma for the first time.
TL;DR: The growth and crystallization processes of vacuum-deposited films of SbBi alloys (Sb 1− x Bi x ( x = 0−1)) on a collodion film substrate at 30°C were studied using both electron and optical microscopy as mentioned in this paper.
01 Jan 1985
01 Dec 1985
TL;DR: In this paper, the Urakawa-Oki earthquake was detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively, and it was shown that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves.
Abstract: Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.