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.

Biologically inspired adaptive walking of a quadruped robot

Abstract: We describe here the efforts to induce a quadruped robot to walk with medium-walking speed on irregular terrain based on biological concepts. We propose the necessary conditions for stable dynamic walking on irregular terrain in general, and we design the mechanical and the neural systems by comparing biological concepts with those necessary conditions described in physical terms. PD-controller at joints constructs the virtual spring–damper system as the viscoelasticity model of a muscle. The neural system model consists of a central pattern generator (CPG), reflexes and responses. We validate the effectiveness of the proposed neural system model control using the quadruped robots called ‘Tekken1&2’. MPEG footage of experiments can be seen at http://www.kimura.is.uec.ac.jp.

Big-Data-Based Intelligent Spectrum Sensing for Heterogeneous Spectrum Communications in 5G

Abstract: Although spectrum sensing is commonly used in modern wireless communications to determine spectrum resources, the rapid development of wireless communications has generated massive heterogeneous spectrum data, which has dramatically increased the complexity of spectrum sensing. Machine-learning-assisted spectrum sensing, as an emerging and promising technique, provides an effective way to find available spectrum resources through the analysis of big spectrum data. In this article, a bigdata- based intelligent spectrum sensing method is proposed to improve heterogeneous spectrum sensing. Specifically, a cooperative spectrum sensing network is designed and established to realize wide-area broadband spectrum sensing and obtain big spectrum data. The effectiveness of such a network has been verified through detection probability simulation. To improve the reliability of spectrum sensing data, the correlations of the big spectrum data in time domain, frequency domain and space domain have been investigated, and the spectrum similarity has been obtained. Then a novel dual-end machine learning model is proposed to improve the precision and real-time prediction of heterogeneous spectrum states. Furthermore, a big spectrum data clustering mechanism is adopted to facilitate data matching and heterogeneous spectrum prediction. Finally, the comprehensive spectrum state is obtained through heterogeneous spectrum data fusion.

Frequency-Dependent Squeezed Vacuum Source for Broadband Quantum Noise Reduction in Advanced Gravitational-Wave Detectors

Abstract: The astrophysical reach of current and future ground-based gravitational-wave detectors is mostly limited by quantum noise, induced by vacuum fluctuations entering the detector output port. The replacement of this ordinary vacuum field with a squeezed vacuum field has proven to be an effective strategy to mitigate such quantum noise and it is currently used in advanced detectors. However, current squeezing cannot improve the noise across the whole spectrum because of the Heisenberg uncertainty principle: when shot noise at high frequencies is reduced, radiation pressure at low frequencies is increased. A broadband quantum noise reduction is possible by using a more complex squeezing source, obtained by reflecting the squeezed vacuum off a Fabry-Perot cavity, known as filter cavity. Here we report the first demonstration of a frequency-dependent squeezed vacuum source able to reduce quantum noise of advanced gravitational-wave detectors in their whole observation bandwidth. The experiment uses a suspended 300-m-long filter cavity, similar to the one planned for KAGRA, Advanced Virgo, and Advanced LIGO, and capable of inducing a rotation of the squeezing ellipse below 100 Hz.

Possible spin-tripletf-wave pairing due to disconnected fermi surfaces in NaxCoO2.yH2O.

Abstract: We propose that the spin-triplet pairing mechanism due to disconnected Fermi surfaces proposed in our previous study [Phys. Rev. B 63, 174507 (2001)] may be at work in a recently discovered superconductor ${\mathrm{N}\mathrm{a}}_{x}{\mathrm{C}\mathrm{o}\mathrm{O}}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}_{2}\mathrm{O}$. We introduce a single band effective model that takes into account the pocketlike Fermi surfaces along with the van Hove singularity near the K point found in the band calculation results. Applying the fluctuation exchange method and solving the linearized \'Eliashberg equation, the most dominant pairing is found to have spin-triplet $f$-wave symmetry, where the nodes of the gap function do not intersect the pocket Fermi surfaces. The presence of finite ${T}_{c}$ is suggested in sharp contrast to cases when the gap nodes intersect the Fermi surface.

Recycling prosodic boundaries.

Abstract: The present study investigates the role of prosodic structure in selecting a syntactic analysis at different stages of parsing in silent reading of Japanese relative clauses. Experiments 1 and 2 (sentence-completion questionnaires) revealed an effect of the length of the sentence-initial constituent on the resolution of a clause boundary ambiguity in Japanese. Experiment 3 (fragment-reading) showed that this length manipulation is also reflected in prosodic phrasing in speech. Its influence on ambiguity resolution is attributed to “recycling” of prosodic boundaries established during the first-pass parse. This explanation is based on the implicit prosody proposals of Bader (1998) and Fodor (1998). Experiment 4 (self-paced reading) demonstrated the immediacy of the influence on ambiguity resolution on-line. Experiment 5 (self-paced reading) found support for the additional prediction that when no boundary is available to be recycled, processing the relative clause construction is more difficult.