Showing papers by "Mitsubishi Electric published in 1990"

The “molecular” traveling salesman

Abstract: We consider a method for optimization of NP-problems motivated by natural evolution. The basic entity is a population of individuals searching in state space defined by the problem. A message exchange mechanism between individuals enables the system to proceed fast and to avoid local optima. We introduce the concept of isolated evolution to maintain a certain degree of variance in the population. The global optimum can be approached to an arbitrary degree. The method is applied to the TSP and its behavior is shown in a couple of simulations.

Y-Ba-Cu-O Superconducting Films with High Jc Values by MOCVD using Ba-Addition Products

Abstract: Y-Ba-Cu-O superconducting films having high Jc of 6.3×106 A/cm2 at 77 K and Tc of 92 K were prepared by metalorganic chemical vapor deposition using a new transport technique with Ba-addition products. This CVD method could realize stable vaporization and smooth transportation of Ba source material due to the increase of the evaporation rate at low sublimation temperatures. Consequently, good reproducibility for preparation of the high Jc films (over 106 A/cm2) was achieved.

Defect inspecting apparatus for disc-shaped information recording media

Abstract: An apparatus which inspects disc-shaped information recording media, such as optical disks and magnetic disks, in a single reproduction. The apparatus detects the type of defect and classifies the defects into defect clusters by the defect position in the radial and circumferential directions. Type of defect or defect cluster, position and size are memorized.

Range Sensing By Projecting Multiple Slits With Random Cuts

Abstract: In this paper, we describe a range sensing method by projecting a single pattern of multiple slits. To obtain 3D data by projecting a single pattern, certain codes for identifying each slit must be contained in the patten. In our method, random dots are used to identify each slit. The random dots are given as randomly distributed cuts on each slit. Thus, each slit is divided into many small line segments and using these segments as features, stereo matching is carried out to obtain 3D data. Using adjacent relations among slit-segments, the false matches are reduced and segment pairs, whose adjacent segments also correspond with each other, are extracted and considered to be correct matches. Then, from the resultant matches, the correspondence is propagated by utilizing the adjacency relationships to get an entire range image.

Optimal midcourse guidance for medium-range air-to-air missiles

Abstract: An advanced midcourse guidance law for medium-range air-to-air missiles is proposed. The law consists of two different guidance modes: the final velocity maximum or the final time minimum, depending on the initial missile-target geometry. The former is preferable against a highly maneuverable target at a great distance, whereas the latter is demanded against a near target. This midcourse guidance law is combined with augmented proportional navigation in the homing phase. Performance is evaluated by computer simulations against conventional and advanced targets. The results show that the proposed guidance law is far superior to the guidance law that employs only augmented proportional navigation throughout the interception course, in regard to extending the launch boundaries or minimizing the interception time.

A multi-level load balancing scheme for OR-parallel exhaustive search programs on the multi-PSI

Abstract: Good load balancing is the key to deriving maximal performance from multiprocessors. Several successful dynamic load balancing techniques on tightly-coupled multiprocessors have been developed. However, load balancing is more difficult on loosely-coupled multiprocessors because inter-processor communication overheads cost more. Dynamic load balancing techniques have been employed in a few programs on loosely-coupled multiprocessors, but they are tightly built into the particular programs and not much attention is paid to scalability. We have developed a dynamic load balancing scheme which is applicable to OR-parallel programs in general. Processors are grouped, and work loads of groups and processors are balanced hierarchically. Moreover, it is scalable to any number of processors because of this multi-level hierarchical structure. The scheme is tested for the all-solution exhaustive search Pentomino program on the mesh-connected loosely-coupled multiprocessor Multi-PSI, and speedups of 28.4 times with 32 processors and 50 times with 64 processors have been attained.

Fiber-optic subcarrier multiplexing video transport employing multilevel QAM

Abstract: The technical feasibility of applying a fiber-optic multilevel QAM (quadrature amplitude modulation) subcarrier multiplexing scheme to a multichannel conventional TV signal transport is explored. This transport scheme has some advantageous features. Because a digital subcarrier modulation scheme is used, a high-quality transmission performance is expected to be achieved, if the bit error is sufficiently small over a transmission line and the required carrier-to-noise ratio (CNR) is relatively small among the many candidates of subcarrier modulation schemes. The use of multilevel modulation allows the bandwidth to be efficiently utilized; consequently, up to 40-channel uncompressed digital TV signals are estimated to be accommodated in the frequency region of the VHF and UHF bands, where well-developed and inexpensive electronics can be easily applied. >

IC card and manufacturing method thereof

Abstract: There is provided an IC card and manufacturing method thereof assuring a highly reliable fixed portion in fixing upper and lower panel members to a frame made of resin as well as an advantage in terms of manufacturing cost. In the IC card in which a pair of upper and lower panel members covering card planar portions are respectively fixed to the upper and the lower surfaces of a resin frame which supports a peripheral portion of an electric circuit board and a connector attached to an end portion of the electric circuit board, the panel members have their peripheral edge portions which are provided with a bent portion extending along the peripherial edge portions and are formed by bending the panel material at a specified angle, and a welding use resin layer is formed on the surface of the bent portion and the periphery of the planar portion of the panel member. On the other hand, the frame is provided with a groove portion for receiving therein the bent portion, and the welding use resin layer is melted in a pressurized state while making the welding use resin layer abut against the frame with the bent portion fitted in to the groove portion, thereby fixing the panel members to the frame.

Spectroscopic Study on a Discharge Plasma of MOCVD Source Gases for High-Tc Superconducting Films

Abstract: Optical emission spectra from a glow-discharge plasma in the vapors of β-diketonate chelates of Ba, Y and Cu element have been measured. They show great changes depending on the temperature of the source-gas oven. In the case of Ba(DPM)2, for example, intensity of the Ba+ emission lines increases drastically at above 220°C, when compared to neutral lines. Referring to the data of thermal analysis and IR absorption experiment, this corresponds to the development of decomposition of the source material. The present experiment opens a future possibility of optical diagnostics to determine the optimum gas feeding condition in the preparation of high-Tc superconducting films by the MOCVD technique.

Experimental study of high speed induction motor varying rotor core construction

Abstract: An experimental study of a high-speed induction motor with various rotor constructions is described. The electrical characteristics of a solid-core-type induction motor are inferior to those of a laminated-core-type motor. A new equivalent circuit for a solid-core-type motor is presented. The behavior of the solid core as secondary conductors is considered. The stray load loss with respect to the rotor construction and the influence of the supply frequency are discussed. >

Improvement of slab-laser beam divergence by using an off-axis unstable-stable resonator

Abstract: Reduction of the beam divergence of a solid-state slab-geometry laser by using an off-axis unstable–stable resonator is described. The resonator acts as an off-axis negative-branch unstable resonator in the slab-width direction. This resonator configuration yields a small beam divergence of 2.5 mrad in the unstable-resonator direction at an average output power of 120 W. This improvement in beam quality is achieved without appreciable loss of efficiency.

Complementary MOS semiconductor device

Abstract: To improve resistance to latch-up of complementary MOS semiconductor device, a high concentration buried layer (16) of same conduction type as a semiconductor substrate (1) and of concentration higher than the silicon semiconductor substrate is formed under a well region (5) of first conduction type in which MOS transistor of second conduction type is formed and a well region (3) of second conduction type in which MOS transistor of first conduction type is formed. The high concentration buried layer (16) reduces parasitic resistance of the semiconductor substrate (1), suppresses transfer of carrier due to surge or the like applied from outside and inside, and inhibits the parasitic transistors (12)(13) from turning on.

Effects of shorted collector on characteristics of IGBTs

Abstract: Vertical insulated gate bipolar tran- sistors with various shorted collector patterns (CS- IGBT) were studied with regard to steady state and transient electrical characteristics at 25OC and 125OC, compared with a conventional IGBT. A two dimensional effect of the shorted collec- tor on the on-state voltage is found to have an ef- fect on an onset voltage of the hole injection from the collector. Furtheremore, the CS-IGBT reveals a positive temperature dependece of the on-state voltage and much less temperature dependence of the turn-off transient in contrast with the conven- tional IGBT.

A new min-cut placement algorithm for timing assurance layout design meeting net length constraint

Abstract: A new VLSI min-cut placement algorithm is presented for timing assurance layout design. When critical nets are given net length constraints, the proposed algorithm can place cells so that the constraints may be met. This algorithm is built into the layout system for gate arrays, called GALOP. The application results are described for the case of clock skew control of an ECL 12K-gate array. >

(11n)-oriented BiSrCaCuO thin film formed on SrTiO3(110) substrate by RF magnetron sputtering

Abstract: A superconducting BiSrCaCuO thin film was grown on a SrTiO3(110) substrate at 660°C by sputtering a single target. The RHEED observation showed that the c-axis of the film meets at an angle of about 42° with the substrate surface. The XRD measurement showed that the film has a main peak at 2 θ=31.2°. From these results, the film is considered to chiefly consist of a 2212 phase with (117) orientation and/or a 2212/2223 superlattice phase with (118) orientation. The film surface has a stripelike texture which probably corresponds to the film orientation. The zero-resistivity temperature of the film was lower by 20 K than that of the film formed on the SrTiO3(100) substrate.

Spectroscopic Measurements of the Production and the Transport of CH Radicals in a Methane Plasma Used for the CVD of a-C:H

Abstract: Spatial and temporal variations of CH radicals in an rf discharge in methane for the deposition of amorphous carbon film were measured by optical emission spectroscopy and laser-induced fluorescence (LIF) spectroscopy. The temporal variation of CH emission from the excited A2Δ state suggested that the electron energy was deeply modulated by the rf field. The spatial distribution of CH in the ground X2Π state showed a broader profile than the time-averaged emission profile of CH(A2Δ), indicating the broader spatial production pattern for the CH(X2Π) and its diffusional transport. The absolute density of CH(X2Π) was also obtained, from which the flux of CH onto the substrate was estimated. The density and the spatial profile of CH were strongly affected by diluent Ar gas. These results were compared with a simulation and discussed in relation to the film deposition.

Preparation of Ca-Doped YBaCuO Thin Films Containing 248 Phase by RF Magnetron Sputtering

Abstract: Ca-doped YBaCuO thin films containing predominantly a 248 phase were prepared on SrTiO3(100) substrates by sputtering three Ca-doped targets at 500°C and annealing at 750°C. The as-deposited films formed at above 500°C predominantly had a 123 phase, and those at 300°C were amorphous. On the other hand, the as-deposited films obtained at 400–500°C had an unidentified major phase with a lattice spacing of 7 A, which changed into a 248 phase by annealing, whereas the phase of amorphous films and the 123 phase did not.

Archaebacterial ATPases: relationship to other ion-translocating ATPase families examined in terms of immunological cross-reactivity.

Abstract: Immunological cross-reactivity among three types of H(+)-ATPases, that is, three archaebacterial ATPases, the F1-ATPase from thermophilic bacterium PS3 (TF1) and the vacuolar membrane ATPase from Saccharomyces cerevisiae, was examined by means of immunoblot analyses. The three archaebacterial ATPases were very similar in immunological cross-reactivity, suggesting that they belong to the same family of ATPases. Cross-reaction was also observed between the ATPase from Sulfolobus acidocaldarius, one of the three archaebacteria, and TF1. S. cerevisiae vacuolar ATPase reacted with the antibodies prepared against each of the three archaebacterial ATPases, but did not react with the antibody against TF1. Electron microscopic examination revealed that the oligomeric structure of Sulfolobus ATPase was very similar to that of F1-ATPase. These results, taken together, suggest that the archaebacterial ATPases share close structural similarities with the vacuolar ATPases, and, to a lesser degree, with the F0F1-ATPases.

Development of CO 2 laser excited by 2.45-GHz microwave discharge

Abstract: A new technique to excite a CO 2 laser by 2.45GHz microwave discharge is developed. Microwave plasma produced by the technique is so stable and homogeneous that any additional means to effectuate laser action such as fast circulation of laser gas and external magnetic field are not necessary. Utilizing the technique, a compact diffusion cooled CO 2 laser with 40cm active length is constructed. A magnetron available for microwave ovens is used as the power source of the laser. Average output power of 116W and maximum conversion efficiency of 18% in CW mode, peak output power of 1.2kW in pulse mode are obtained. Output beam with good focusibility is extracted by applying an unstable-waveguide hybrid resonator.

A circuit design of intelligent CDRAM with automatic write back capability

Abstract: The authors describe a unique intelligent memory based on a distributed CDRAM (cache DRAM) architecture, which consists of three hierarchical memory sections, DRAM, SRAM, and CAM, that constitute on-chip TAG. This architecture provides a high-performance intelligent main memory and a pin compatibility with high-speed address nonmultiplexed memories (DRAM, SRAM, and pseudo-SRAM). This RAM can be fabricated by the standard CMOS DRAM process with little area penalty. The intelligent CDRAM with an automatic write-back function can realize a short average read/write cycle time. The write-back operation without a complex controller minimizes the write cycle time drastically compared with write through

Spindle position/speed control unit

Abstract: The invention relates to a spindle speed/position control system for use in a numerically controlled machine tool such as a lathe. To improve the measurement of spindle speed and position, detected elements are attached directly to the rotatable spindle. A waveform shaping circuit takes the outputs of speed and position detecting sensors, and outputs a variety of sinusoidal and pulse signals. The sinusoidally varying signals are employed in speed detection while the pulse signals are used for position detection and control.

Helium liquefaction by a Gifford-McMahon cycle cryocooler

Abstract: This paper describes the principal design features and performance test results of a three-stage Gifford-McMahon cycle cryocooler by which the authors have achieved no-load temperature of 3.3 K and succeeded in helium liquefaction. The key point of the success is the selection of GdχEr1-χRh compounds as a regenerator material. The refrigeration capacity was 20 mW at 4.2 K and the helium liquefaction rate was 10 cm3/h. This is the first success that a Gifford-McMahon cycle cryocooler has liquefied helium without precooling.

Rotary head recording and playback apparatus and method

Abstract: In a method of recording digital information signals to form tracks on a magnetic tape, the samples of the signals to be recorded are divided into a plurality of odd sample groups and a plurality of even samples groups. The groups containing adjacent samples are disposed on differently-numbered regions of different tracks. Error correcting codeword may be recorded in a plurality of tracks. Errors in one region can be corrected or compensated by samples in different tracks or samples in differently-numbered regions.