Showing papers by "Mitsubishi Electric published in 1982"
TL;DR: A computer method is proposed for the extraction of blood vessels from the retinal background; the recognition of arteries and veins; the detection and analysis of peculiar regions such as hemorrhages, exudates, optic discs and arterio-venous crossings.
195 citations
TL;DR: In this paper, the amplitude variation of the composite electric field of the entire array was measured when the phase of each element was modified. But, the amplitude and phase were not accurately measured under specific operating conditions.
Abstract: In the phased array system, excitation amplitudes and phases based on the design are specified for each antenna element in order to synthesize desired beam scannings and radiation patterns. However, due to fluctuations of antenna and feed network characteristics, the amplitude and phase of each antenna element deviate from the desired values. To correct these deviations, the amplitude and phase of each antenna element must be accurately measured under specific operating conditions. In this paper, we employ variable phase shifters connected to the antenna elements and measure only the amplitude variation of the composite electric field of the entire array when the phase of each element is modified. The rotating element electric field vector method in which the measured amplitude variation is numerically processed for obtaining the amplitude and phase of the particular element is theoretically discussed and experimentally tested for its usefulness. The present method can be easily attained by simply adding software to the computer-controlled phased array system.
132 citations
24 May 1982
TL;DR: The design method which minimizes the phase error on the aperture of the linear array antenna has been shown and makes it possible to design small and low-loss Rotman lens antennas.
Abstract: A Rotman lens is used to feed a linear array antenna for wideband use. A relationship between design parameters for realizing a Rotman lens has been derived by introducing a new design variable. The design method which minimizes the phase error on the aperture of the linear array antenna has been shown. For large array length, the above phase error due to this method becomes considerably smaller than that due to a conventional method. This improved method makes it possible to design small and low-loss Rotman lens antennas.
98 citations
TL;DR: In this article, a fiber-optic measurement instrument for temperature was constructed consisting of a small sensor responding to optical absorption change in a semiconductor, and a unique signal processing system with two different-wavelength light emitting diodes (LED's).
Abstract: A practical fiber-optic measurement instrument for temperature was constructed consisting of a small sensor responding to optical absorption change in a semiconductor, and a unique signal processing system with two different-wavelength light emitting diodes (LED's). The fiber-optic sensor with a semiconductor chip is quite small, very sensitive, highly reliable, and easy to manufacture at low cost. The most outstanding feature of this system is that it is free from optical-stray-loss. The accuracy of about \pm1\deg and the response time of about 2 s were obtained in the temperature range from -10°C to 300°C.
98 citations
TL;DR: In this article, the authors discussed the characteristics of the insulating oils used in large power transformers and proposed a method for streaming electrification of large transformers from the point of view of characteristics of these oils.
Abstract: Streaming electrification of large power transformers is discussed here from the standpoint of characteristics of insulating oils used in them.
85 citations
TL;DR: In this article, the grain size effect of the tin and tin-lead coatings on whisker growth was examined by means of high voltage electron microscopy, and it was found that the tin coatings from which whiskers hardly grew consisted of well-polygonized grains which were a few micrometre in size.
Abstract: Tin and tin-lead coatings electro-plated in various solutions have been observed by means of high voltage electron microscopy, and the grain size effect of the coatings on whisker growth has been examined As a result, it was found that the tin and tin-lead coatings from which whiskers hardly grew consisted of well-polygonized grains which were a few micrometre in size, and that the tin coatings from which whiskers easily grew consisted of irregular-shaped grains which were a few tenths of a micrometre in size The irregularshaped grains contained dislocation rings which might be formed by clustering of vacancies or interstitial atoms upon electro-plating
84 citations
TL;DR: An efficient design method is presented for a vector quantiser of 16-dimensional vectors based on a long training sequence of normalised video signals.
Abstract: An efficient design method is presented for a vector quantiser of 16-dimensional vectors based on a long training sequence of normalised video signals. The basic properties are demonstrated by examples.
70 citations
TL;DR: In this paper, a digital fault location scheme is presented based on the transient analysis of a faulted network, and the theoretical basis is first described using the Laplace transform technique, and an attempt is made to clear its relation to the Fourier transform scheme.
Abstract: Digital fault location scheme is presented based on the transient analysis of a faulted network. The theoretical basis is first described using the Laplace transform technique, and an attempt is made to clear its relation to the Fourier transform scheme. With the theoretical fault data, location performances are analyzed regard to system characteristics. Finally, the study is extended to determine the optimal operator value for numerical Laplace transform. The proposed scheme will be suitable for implementation at an integrated digital protection and control system for transmission substations.
65 citations
01 Jan 1982
TL;DR: In this article, reversible DC power-supply systems with thyristor inverters are described, together with principal designs, solutions adopted to overcome the technical difficulties and some operational results, and some more examples of application are referred to as further experiences of the system.
Abstract: Reversible DC power-supply systems with thyristor inverters are described. Design principles applicable to and technical difficulties encountered by the reversible DC power-supply system are discussed. To give an example of application, the power-supply system of Kobe Metro is described in detail, together with principal designs, solutions adopted to overcome the technical difficulties and some operational results. Some more examples of application in Japan are referred to as further experiences of the system. The designs described are supported by service experience.
56 citations
Abstract: A practical fiber optic measuring system for heavy electric current was developed by using the magnetooptic (Faraday) material. In order to obtain better SNR and smaller temperature dependence, the most suitable combination of the light source and Faraday material was experimentally and theoretically determined. Consequently, it was emphasized that an LED and diamagnetic SF-6 flint glass gave the superiority of overall system capability over LD's and para- or ferromagnetics. A novel type of fiber optic current sensor was constructed of the Faraday rotator of SF-6 flint glass with two thin-film polarizers. By using this sensor and a high radiance LED, high accuracy within ±0.5 percent was obtained for magnetic field between 20 and 500 Oe, and at temperatures from -25°C up to 80°C.
33 citations
TL;DR: In this article, a practical method for deriving operational impedances from load tests is proposed, which differs from well-known frequency response methods from stator or rotor circuit, and is suited for dynamic stability studies.
Abstract: A practical method for deriving operational impedances from on load tests is proposed. This method differs from well-known frequency response methods from stator or rotor circuit [3-5]. The operational impedances are calculated from the data of small perturbations of the generator voltage, current and rotor angle during system disturbances using Laplace transforms. They include the saturation effect and are suited for dynamic stability studies.
TL;DR: In this paper, the surge degradation of zinc oxide elements under constant ac stress is investigated experimentally and the results are summed up in a set of formulae and figures from which the degradation of any given condition can be evaluated.
Abstract: The surge degradation of zinc oxide elements under a constant ac stress is investigated experimentally. The results are summed up in a set of formulae and figures from which the degradation of any given condition can be evaluated. The increase ratio of leakage current from the initial value is successfully sed as the indicator of degradation of elements. The two types of elements are investigated concurrently-Formation I being used in production and Formation II a new material. Formation II is found to be remarkably resistant to surges and particularly to ac stress. The influence of degradation on the life of metal oxide surge arrester is discussed on the basis of a dynamic thermal stability. The permissible number of surges during the life is determined for the two types of elements. The performance of arrester is expected to be greatly improved by the use of Formation II.
15 Jun 1982
TL;DR: In this paper, a waveguide power divider using a metallic septum was described, and a high isolation and a low insertion loss were obtained by using a resistive coupling slot.
Abstract: This paper describes a waveguide power divider using a metallic septum. In this divider, a high isolation and a low insertion loss were obtained by using a resistive coupling slot in the septum.
TL;DR: In this article, the results for the NH 3 chemisorption were consistent with the model that NH 3 molecules are adsorbed in a molecular state at 300 K, being distinct from the atomic N and H chemisorsption states.
TL;DR: In this paper, a fiber-optic measurement instrument for temperature was constructed consisting of a small sensor responding to optical absorption change in a semiconductor, and a unique signal processing system with two different-wavelength light emitting diodes (LED's).
Abstract: A practical fiber-optic measurement instrument for temperature was constructed consisting of a small sensor responding to optical absorption change in a semiconductor, and a unique signal processing system with two different-wavelength light emitting diodes (LED's). The fiber-optic sensor with a semiconductor chip is quite small, very sensitive, highly reliable, and easy to manufacture at low cost. The most outstanding feature of this system is that it is free from optical-stray-loss. The accuracy of about +-1° and the response time of about 2 s were obtained in the temperature range from -10° C to 300°C.
TL;DR: In this article, a generalized coordinate control system and a method of compensating for variations in flux and torque resulting from a difference between actual constants and controller constants are described. But this is achieved by a coordinate transformation of the electrical quantities of an induction motor.
Abstract: An induction motor drive which can replace a high performance dc motor drive in steel and paper mill applications has long been desired. The authors have brought this into reality by accurate coordinate control of a combination of a caged rotor induction motor and controlled current inverter. The concept of the improved coordinate control is that the exciting current and torque current are controlled independently by controlling slip and stator current vector. This is achieved by a coordinate transformation of the electrical quantities of an induction motor. A generalized coordinate control system and a method of compensating for variations in flux and torque resulting from a difference between actual constants and controller constants are described.
TL;DR: A novel type of sensing system is currently being developed, in which optical fibres are used as sensing elements or transmission lines, and the principles, performance, and problems of some typical fibre optic sensing systems are described in detail.
01 Nov 1982
TL;DR: A computer method of recognizing blood vessel networks in color ocular fundus images which are used in the mass diagnosis of adult diseases such as hypertension and diabetes, and a deterministic labeling and a probabilistic relaxation labeling are proposed.
Abstract: We propose a computer method of recognizing blood vessel networks in color ocular fundus images which are used in the mass diagnosis of adult diseases such as hypertension and diabetes. A line detection algorithm is applied to extract the blood vessels, and the skeleton patterns of them are made to analyze and describe their structures. The recognition of line segments of arteries and/or veins in the vessel networks consists of three stages. First, a few segments which satisfy a certain constraint are picked up and discriminated as arteries or veins. This is the initial labeling. Then the remaining unknown ones are labeled by utilizing the physical level knowledge. We propose two schemes for this stage : a deterministic labeling and a probabilistic relaxation labeling. Finally the label of each line segment is checked so as to minimize the total number of labeling contradictions. Some experimental results are also presented.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, the arc traveling velocity due to magnetic force, gas pressure rise and metal melting time were measured in an SF6 gas-filled enclosure, and the internal arcs in the SF6 enclosure were experimentally investigated.
Abstract: Internal arcs in an SF6 gas-filled enclosure were experimentally investigated. The arc traveling velocity due to magnetic force, gas pressure- rise and metal melting time were measured.
01 Jan 1982
TL;DR: In this article, field tests using stored earth energy and water energy in combination with heat pipes for snow melting were conducted at the Nojiri Snow Removal Station, Lake Njiri, Nagano Prefecture, and Karls Hot Spring, Noboribetsu, Hokkaido, during 1978 and 1981.
Abstract: Field tests using stored earth energy and water energy in combination with heat pipes for snow melting were conducted at the Nojiri Snow Removal Station, Lake Nojiri, Nagano Prefecture, and Karls Hot Spring, Noboribetsu, Hokkaido, during 1978 and 1981. The results of these test show that the capability of the earth heat systems ranged from 40 to 100 W/m2, while the water system was capable of delivering a maximum of about 400 W/m2. Earth heating systems are the effective means of snow melting and deicing in moderate climate zones. One of several merits of these systems is that maintenance and power costs are eliminated. But the demerits are high construction costs and low power generation. Studies conducted over a three-year period show that the energy dissipated during the winter is naturally restored to the earth by the following October. However, owing to an insufficient thermal capacity, the snow melting capability decreases in late winter. This creates the problem of ensuring the earth heat system's performance capability in climates of unpredictable severity. This paper gives an outline of the designs, construction, and test results of these systems at two test sites in Japan; also included is a discussion on the economic feasibility of utilizing the two systems discussed.
01 Jan 1982
TL;DR: In this article, a premixed laminar flame was excited by a speaker-driver unit, and the velocity fluctuations in a methane-air premixed flame and the flame front movement were measured with a laser Doppler velocimeter and a CH* emission photodetector, respectively, for various mean velocities, excitation frequencies and mixture strengths.
Abstract: A premixed laminar flame was excited by a speaker-driver unit, and the velocity fluctuations in a methane-air premixed flame and the flame front movement were measured with a laser Doppler velocimeter and a CH* emission photodetector, respectively, for various mean velocities, excitation frequencies and mixture strengths. It was found that the fluctuation which propagates along the reaction zone of the flame is an instability wave similar to that observed in an isothermal jet (Tollmien-Schlichting wave). A transfer function of the flame is derived based on a simplified model taking into account the growth of the fluctuation. It is shown that the frequency dependencies of the gain and the phase observed in the measurement of CH* emission and the pyro-acoustic amplification are explained satisfactorily by the above function.
TL;DR: In this paper, high-pressure oxidation of silicon was performed at a pressure of 8.9 kg/cm2 at a temperature range of 650 to 950°C, and the oxidation temperature dependence of the film density, refractive index, chemical etching rate, and residual stress was measured.
Abstract: High-pressure oxidation of silicon was performed at a pressure of 8.9 kg/cm2at a temperature range of 650 to 950°C. The oxidation temperature dependence of the film density, refractive index, chemical etching rate, and residual stress was measured. The film density of the oxide film was found to increase with decreasing oxidation temperature. The refractive index of the film also increased with decreasing oxidation temperature. The residual stress was found to be dependent on the oxidation temperature. The dielectric breakdown strength of the oxide film was measured by the voltage ramping method. The defect density of the oxide film calculated from the distribution of dielectric breakdown strength slightly decreased with decreasing oxidation temperature. The surface-state density of the oxide film was about 1.1 × 1011cm-2throughout the oxidation temperature range. The oxide grown on a doped polysilicon layer at a temperature of 750°C was five times as thick as the oxide simultaneously grown on the silicon substrate. The high-pressure and low-temperature oxidation was applied to the fabrication process of a device with a double polysilicon layer structure.
Proceedings Article•
01 Sep 1982TL;DR: Shunt current flowing through p-n-p-n current blocking layers is examined as a possible cause of excess temperature sensitivity of Ith and -ex which is often observed in InGaAsP BC and BH lasers as mentioned in this paper.
Abstract: Shunt current flowing through p-n-p-n current blocking layers is examined as a possible cause of excess temperature sensitivity of Ith and -ex which is often observed in InGaAsP BC and BH lasers. Under certain conditions, the shunt current reduces the T0 value of Ith from 65 K to 45 K and that of -ex from 130 K to 40 K.
TL;DR: In this paper, the surface fields excited by a horizontal magnetic source located on a conducting concave spherical surface have been formulated as a combination of ray-optical fields and simplified integrals under the condition that the radius of the spherical surface is much greater than the wavelength.
Abstract: The surface fields excited by a horizontal magnetic source located on a conducting concave spherical surface have been formulated. The field expressions are obtained as a combination of ray-optical fields and simplified integrals under the condition that the radius of the spherical surface is much greater than the wavelength. Numerical calculations have been performed, and the calculated results for the surface fields have been corroborated with experiments. The results of these basic studies have been used in calculating the mutual coupling between rectangular slot antennas on the conducting concave spherical surface assuming the aperture field as the dominant mode in the wave guides connected with the slots. The numerical results have been compared with those for slots on a convex conducting surface. Experimental investigation of the mutual coupling has also been carried out.
TL;DR: In this article, the authors investigated discharge stabilization, long-term operation, output power characteristics, and efficiency of the high-pressure CW CO 2 laser under sealed conditions, and showed that high efficiency can be obtained in spite of high pressure and sealed operation.
Abstract: Discharge stabilization, long-term operation, output power characteristics, and efficiency of the high-pressure CW CO 2 laser have been investigated under sealed conditions. A comparison is made with low-pressure CW CO 2 lasers. Two types of electrode structures suitable for operations in the pressure range 100-760 torr are presented. Effects of O 2 and CO on the discharge stability and unsaturated gain are described. By using molecular sieve 3A as an adsorbent of water vapor, which was the most detrimental impurity, sealed operation with no decrease in output power was achieved at 0.5-1.5 kW for more than 150 h elapsed time including about 30 h of discharge time. It has been demonstrated that high efficiency can be obtained in spite of high-pressure and sealed operation. The efficiency was improved by reducing the cavity loss due to the absorption of intracavity radiation by CO 2 molecules in the unexcited region, and by finding the optimum of gas mixture. A maximum efficiency of 19 percent was obtained at a 1 kW power level for a 100 torr gas mixture of either CO 2 -CO-N 2 -He = 2-1-19-19 or CO 2 -CO-N 2 -He-Ar = 2-1-18-10-10. The effects of Ar and N 2 proportion on the unsaturated gain and saturation parameter are discussed.
TL;DR: In this article, the design and fabrication of high power and high breakdown-voltage static induction transistor (SIT) with a high maximum frequency of oscillation are described and then the experimental characteristics are presented.
Abstract: The design and fabrication of high-power and high-breakdown-voltage static induction transistor (SIT) with a high maximum frequency of oscillation are described and then the experimental characteristics are presented. A field plate is used to make the breakdown voltage high, and a fine stripe structure is adopted to make the maximum frequency of oscillation high. As a result, the gate-drain breakdown voltage of 300 V, the gate-source breakdown voltage of 70 V, and the maximum frequency of oscillation of 700 MHz are obtained. The maximum output power of 216 W with 7.5-dB gain and 55- percent drain efficiency is obtained at 100 MHz without a thermal runaway from an amplifying SIT with four pellets mounted in a single package.
TL;DR: In this paper, a fully oxide isolated bipolar transistor is fabricated in recrystallized silicon film on the substrate with the double insulating structure, and it shows following characteristics; typical values of hFE, BVCBO, BVEO, and BVEBO are 29, 73 V, 30 V and 5.2 V, respectively.
Abstract: Double layer structure of thin nitride on thick oxide is used as an insulating material in order to get a good quality of silicon layer on insulator by laser recrystallization. This structure makes deposited polycrystalline silicon (polysilicon) more resistant to stripping off at high power laser irradiation and results in large grains of silicon layer with random crystal orientations. Laser scanning steps of 20 to 30 µm/step are obtained as optimum values for the largest grain size and smooth surface by investigation of grain growth and surface features. A fully oxide isolated bipolar transistor is fabricated in recrystallized silicon film on the substrate with the double insulating structure, and it shows following characteristics; typical values of hFE, BVCBO, BVCEO, and BVEBO are 29, 73 V, 30 V and 5.2 V, respectively. This is the first demonstration of the bipolar transistor in silicon layer on insulator. Quite similar results in grain sizes after laser irradiation and electrical characteristics of transistors are obtained between two kinds ofpolysilicon by conventional LPCVD furnace and an epitaxial reactor at relatively high temperatures, while original grain sizes of the latter are apparently larger than that of the former.
TL;DR: In this paper, a theory of modulation of optical bistability of a main (signal) beam by an additional (control) beam is presented, where it is assumed that the mirrors composing a Fabry-Perot cavity are highly reflective to the signal beam but transparent to the control beam.
Abstract: A theory of modulation of optical bistability of a main (signal) beam by an additional (control) beam is presented. It is supposed that the mirrors composing a Fabry-Perot cavity are highly reflective to the signal beam but transparent to the control beam. We show that the property of a medium in the cavity, and hence the transmission of the signal beam through the cavity, is modulated by the control beam which changes the dielectric susceptibility of the intracavity medium. Amplification of the signal beam occurs in the limit of a strong control beam. The process can be viewed as a parametric transfer of energy between the signal beam and the control beam with the nonlinear medium providing the nonlinear susceptibility that couples the beams. In addition, multibistability in the transmission characteristics of the signal beam is predicted and attributed to the saturation effect of the multiphoton processes.