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.

Surface engineering of PbS quantum dot sensitized solar cells with a conversion efficiency exceeding 7

Abstract: The power conversion efficiencies (PCEs) of PbS quantum dot sensitized solar cells (QDSCs) reported are typically below 6%. This poor efficiency is mainly derived from the serious charge recombination in internal QDs and at the interface of QDs/TiO2/electrolyte. In this work, PbS/CdS QDs with a core/shell structure, which were used as the photosensitizer to fabricate sensitized solar cells, were prepared through the ion exchange method. With the reduced trapping state defects on the surface of the PbS QDs and resulting effective suppression of adverse charge recombination, the PbS/CdS QD-based cells have been improved remarkably in comparison with the pristine PbS-based QDSCs. By optimization of the thickness of the CdS shell, a PCE of 7.19% under one full sun illumination was obtained on the fabricated devices, which is among the best performances for liquid-junction PbS QDSCs.

Generalized Berlekamp-Massey decoding of algebraic-geometric codes up to half the Feng-Rao bound

Abstract: Summary form only given, as follows. Efficient decoding of BCH- and Reed-Solomon codes can be done using the Berlekanp-Massey (1969) algorithm, and it is natural to try to use the extension of this to N dimensions of Sakata (see Inform. Computat., vol.84, no.2, p.207, 1990) to decode algebraic geometry codes. We treat a general class of algebraic geometry codes and show how to decode these up to half the Feng-Rao (see IEEE Trans. Inform. Theory, vol.IT 39, no.1 p.37-45, 1993) bound, using an extension and modification of the Sakata algorithm. >

Coherent optical frequency transfer over 50-km physical distance using a 120-km-long installed telecom fiber network.

Abstract: Optical frequency at 1542 nm was coherently transferred over a 120-km-long installed telecom fiber network between two cities (Tsukuba and Tokyo) in Japan separated by more than 50 km. The phase noise induced by the fiber length fluctuations was actively reduced by using a fiber stretcher and an acousto-optic modulator. The fractional frequency instability of the one-way transmitted light was reduced down to less than 8.0 x 10(-16) at an averaging time of 1s, which is limited by the theoretical limit deduced from the length and the intrinsic noise of the fiber.

Operando Time-Resolved X-ray Absorption Fine Structure Study for Surface Events on a Pt3Co/C Cathode Catalyst in a Polymer Electrolyte Fuel Cell during Voltage-Operating Processes

Abstract: The structural kinetics of surface events on a Pt3Co/C cathode catalyst in a polymer electrolyte fuel cell (PEFC) was investigated by operando time-resolved X-ray absorption fine structure (XAFS) with a time resolution of 500 ms. The rate constants of electrochemical reactions, the changes in charge density on Pt, and the changes in the local coordination structures of the Pt3Co alloy catalyst in the PEFC were successfully evaluated during fuel-cell voltage-operating processes. Significant time lags were observed between the electrochemical reactions and the structural changes in the Pt3Co alloy catalyst. The rate constants of all the surface events on the Pt3Co/C catalyst were significantly higher than those on the Pt/C catalyst, suggesting the advantageous behaviors (cell performance and catalyst durability) on the Pt3Co alloy cathode catalyst.