Mitsubishi Electric

About: Mitsubishi Electric is a company organization based out in Ratingen, Germany. It is known for research contribution in the topics: Signal & Voltage. The organization has 23024 authors who have published 27591 publications receiving 255671 citations. The organization is also known as: Mitsubishi Electric Corporation & Mitsubishi Denki K.K..

Mode locking in Fabry-Perot semiconductor lasers

Abstract: Passive mode-locking (ML) operation in semiconductor quantum-well (QW) lasers with Fabry-Perot (FP) cavities is investigated theoretically and experimentally. Structural and operational conditions for a semiconductor QW laser to exhibit ``amplitude modulation (AM)'' or ``frequency modulation'' ML operations are investigated by numerical analysis based on a semiclassical laser model. It is shown experimentally that clear AM ML pulses self-build and persist under continuous current injection in ${\mathrm{In}}_{1\ensuremath{-}x}{\mathrm{Ga}}_{x}\mathrm{As}/{\mathrm{In}}_{1\ensuremath{-}x}{\mathrm{Ga}}_{x}{\mathrm{As}}_{y}{\mathrm{P}}_{1\ensuremath{-}y}/\mathrm{InP}$-based FP QW lasers with cavity lengths of $300\ensuremath{-}600 \ensuremath{\mu}\mathrm{m}.$ The observed ML features are explained in terms of the laser model.

High-precision tracking control system for digital video disk players

Abstract: The advent of digital video disks (DVD) has lead to narrower tracks along with a demand for higher density in the field of optical disks. This general and recent trend requires the improvement of follow-up capability within limits which are not detrimental to stability and speed of response. We have developed a new adaptive repetition control system that can improve follow-up capability by applying repetition control theory to tracking control, and which can change the learning capacity according to such nonperiodic components as insufficient stability margin (one of the problems in repetition control), disk drive vibration and disk defects, in response to the degree of track correlation. Furthermore, the division of the learning portion into two stages, namely long-term and short-term storage memories, compensates for the short-term memory being degraded by insufficient correlation and enhance the learning capability when disturbance occurs. As a result we were able to reduce the track error by disk eccentricity down to 0.02 /spl mu/m or less in a DVD disk with an eccentricity similar to compact disks (CD), and can confirm that the disk functions in a stable fashion even with interference from irregular disturbances. >

Collisional history of Ryugu’s parent body from bright surface boulders

Abstract: The asteroid (162173) Ryugu and other rubble-pile asteroids are likely re-accumulated fragments of much larger parent bodies that were disrupted by impacts. However, the collisional and orbital pathways from the original parent bodies to subkilometre rubble-pile asteroids are not yet well understood1–3. Here we use Hayabusa2 observations to show that some of the bright boulders on the dark, carbonaceous (C-type) asteroid Ryugu4 are remnants of an impactor with a different composition as well as an anomalous portion of its parent body. The bright boulders on Ryugu can be classified into two spectral groups: most are featureless and similar to Ryugu’s average spectrum4,5, while others show distinct compositional signatures consistent with ordinary chondrites—a class of meteorites that originate from anhydrous silicate-rich asteroids6. The observed anhydrous silicate-like material is likely the result of collisional mixing between Ryugu’s parent body and one or multiple anhydrous silicate-rich asteroid(s) before and during Ryugu’s formation. In addition, the bright boulders with featureless spectra and less ultraviolet upturn are consistent with thermal metamorphism of carbonaceous meteorites7,8. They might sample different thermal-metamorphosed regions, which the returned sample will allow us to verify. Hence, the bright boulders on Ryugu provide new insights into the collisional evolution and accumulation of subkilometre rubble-pile asteroids. The Hayabusa2 team has discovered two types of bright boulder on the dark, carbonaceous asteroid Ryugu. One type has a spectrum consistent with material from an anhydrous silicate-rich asteroid, likely introduced by one or more collisions in Ryugu’s past.

Communication apparatus and communication system

Abstract: A communication apparatus that can suppress an increase in circuit size and reduce influence of interference, includes reception array antenna elements, a reception digital beam forming (DBF) network that generates a reception beam signal for forming M reception beams using a reception signal, and reception filter banks (FBs) that generate frequency split reception beam signals obtained by frequency-splitting the reception beam signal. The communication apparatus includes an interference-source detecting unit that stores, for each reception beam, an interference candidate beam area estimated based on an initial reception beam characteristic, calculates, based on the frequency split reception beam signals, a reception spectrum, and calculates, based on the reception spectrum and a reception spectrum of a reception beam to the interference candidate beam area, an interference source area. The reception DFB network generates a reception beam signal to perform null formation in the direction of the interference source area.

Antialiasing with Line Samples

Abstract: A method, using a filter function, generates an anti-aliased discrete image from a continuous image including an edge. The method defines a line sample. A progressive convolution is derived from the filter function and the line sample. A pixel at a predetermined location in the discrete image is selected, and the line sample is oriented with respect to the selected pixel. A distance is measured from a point in the continuous image corresponding to the selected pixel to the edge along the oriented the line sample. The progressive convolution is evaluated at the measured distance to produce a weighted coverage value, and the weighted coverage value is associated with the pixel to anti-alias the pixel in the discrete image.