Hidenori Takahashi

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Transmitter and receiver IQ imbalance causes image interference that degrades performance in high capacity and high spectral efficiency optical orthogonal frequency division multiplexing (OFDM) schemes. Digital compensation is an attractive method to relax component specifications. In this paper we report the details of a hybrid compensation method for IQ(More)
We have developed an imaging Fourier transform spectrometer (FTS) for space-based far-infrared astronomical observations. The FTS employs a newly developed photoconductive detector arrays with a capacitive trans-impedance amplifier, which makes the FTS a completely unique instrument. The FTS was installed as a function of the far-infrared instrument (FIS:(More)
We derive the glueball masses in noncommutative super Yang–Mills theories in four dimensions via the dual supergravity description. The spectrum of glueball masses is discrete due to the noncommutativity and the glueball masses are proportional to the noncommutativity parameter with dimension of length. The mass spectrum in the WKB approximation closely(More)
Space-division multiplexing (SDM) with multi-core/multi-mode fibers has potential to increase the transmission capacity drastically. In this paper, we investigate the feasibility of trans-oceanic transmission towards beyond 100 Tbit/s using multi-core fibers. Experimental results using 7-core fibers/EDFAs are also presented.
We observed an area of 10 deg 2 of the Large Magellanic Cloud using the Infrared Camera on board AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and 24 micron) and a dispersion prism (2 – 5 micron, λ/∆λ ∼ 20) equipped in the IRC. This paper describes the outline of our survey project and presents some initial results using(More)
The work in the Touch Lab (formal name: Laboratory for Human and Machine Haptics) is guided by a broad vision of haptics which includes all aspects of information acquisition and object manipulation through touch by humans, machines, or a combination of the two; and the environments can be real or virtual. We conduct research in multiple disciplines such as(More)
We present a unified description of the spontaneous symmetry breaking and its associated bosons in fermion field theory. There is no Goldstone boson in the fermion field theory models of Nambu-Jona-Lasinio, Thirring and QCD 2 after the chiral symmetry is spontaneously broken in the new vacuum. The defect of the Goldstone theorem is clarified, and the "(More)