University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Space gravitational-wave antennas DECIGO and B-DECIGO

Abstract: DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO) is a future Japanese space gravitational-wave antenna. The most important objective of DECIGO, among various sciences to be aimed at, is to detect gravitational waves coming from the inflation of the universe. DECIGO consists of four clusters of spacecraft, and each cluster consists of three spacecraft with three Fabry–Perot Michelson interferometers. As a pathfinder mission of DECIGO, B-DECIGO will be launched, hopefully in the 2020s, to demonstrate technologies necessary for DECIGO as well as to lead to fruitful multimessenger astronomy. B-DECIGO is a small-scale or simpler version of DECIGO with the sensitivity slightly worse than that of DECIGO, yet good enough to provide frequent detection of gravitational waves.

Collisional pumping of SiO masers in evolved stars

Abstract: ALTHOUGH SiO masers (lasing systems at microwave frequencies) have been detected in many old red-giant stars1,2, several fundamental questions, such as what drives the masers and where in the stars' environment they are located3, remain unresolved. Evolved stars are known to have winds, which distribute enriched material throughout the interstellar medium, but the acceleration mechanism and the point in the stellar atmosphere at which the winds are initiated, are unknown4. SiO masers have high brightness temperatures, which allows them to be studied with high spatial and spectral resolution using very-long-baseline interferometry (VLSI) techniques, and thereby potentially determine how the stellar winds are generated. This will only be possible, however, once the physical conditions giving rise to the maser emission are known. Here we present images of positionally coincident maser emission from the J = 1 → 0 rotational transition of the first two vibrational levels in the SiO masers in VY Canis Majoris and W Hydrae. These results clearly demonstrate that the maser emission is collisionally pumped in distinct regions, rather than radiatively pumped. This means that SiO maser emission can be used to follow the clumps of gas as they are accelerated in the stellar atmosphere.

Electronic structure of periodic curved surfaces: Topological band structure

Abstract: The electronic band structure for electrons bound on periodic minimal surfaces is differential-geometrically formulated and numerically calculated. We focus on minimal surfaces because they are not only mathematically elegant (with the surface characterized completely in terms of ``navels'') but represent the topology of real systems such as zeolites and negative-curvature fullerenes. The band structure turns out to be primarily determined by the topology of the surface, i.e., how the wave function interferes on a multiply connected surface, so that the bands are little affected by the way in which we confine the electrons on the surface (thin-slab limit or zero thickness from the outset). Another curiosity is that different minimal surfaces connected by the Bonnet transformation (such as Schwarz's P and D surfaces) possess one-to-one correspondence in their band energies at Brillouin-zone boundaries.