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A wireless electroencephalogram (EEG) sensor using a stretchable electrode sheet and electrode-tissue impedance measurement module is presented herein. The sensor can be attached to the forehead using biocompatible gel with the electrode sheet. The sensor is compactly designed for 3 cm χ 9 cm × 6 mm with weight of 12 g. Impedance scanning circuit is also proposed to evaluate the skin surface condition...
Thermohydraulic analysis of postulated accidents will identify systems responses to accident scenarios and aid to develop design of safety systems and strategies to prevent and mitigate accident propagation. This paper reports recent progress in analysis of some accident scenarios of a water-cooled fusion DEMO reactor. Four types of accidents are particularly considered: ex-vessel loss-of-coolant...
An accurate, continuously tunable, terahertz synthesizer was proposed by photomixing of two continuous-wave lasers phase-locked to dual optical combs. This synthesizer enables us to perform the precise THz spectroscopy secured by microwave frequency standard.
We demonstrated combination of spectrally interleaved terahertz (THz) frequency comb with dual-comb spectroscopy, enabling us to achieve the spectral sampling equal to linewidth of the comb tooth in the low-pressure gas spectroscopy in THz region.
We demonstrated fast 3D terahertz computed tomography by using real-time line projection of an intense terahertz beam. Peak-to-peak amplitude of the pulsed terahertz electric field and a standard reconstruction algorithm were used to performed final 3D reconstruction of test samples with a total acquisition time to only 6 minutes.
The aim of this study was to examine the SSVEFs associated with the processing of positive and negative impression images. We used the International Affective Picture System (IAPS) which is increasingly used in brain imaging studies to examine emotional processes. Their images also allow valence to be systematically investigated. All 200 images were categorized into three categories of “negative ”,...
We report a systematic study on undoped and Mg-doped InGaN grown by molecular beam epitaxy. Various experiments have been combined to demonstrate p-type InGaN across the entire alloy composition range.
We proposed frequency-swept asynchronous-optical-sampling terahertz time-domain spectroscopy to further improve the spectral resolution. The spectral resolution achieved here was 2.2 MHz, which is two orders of magnitude smaller than the mode-locked frequency.
New RF-MBE growth method called DERI (Droplet Elimination by Radical Beam Irradiation) was proposed as a reproducible growth method of high quality and smooth InN films. Growth process was investigated based on in situ monitoring by RHEED and laser beam reflection. It was suggested that growth proceeds keeping two mono-layers of In and additional In droplets on the growing surface. Growth of InGaN...
We report a systematic investigation on Mg doped InGaN epilayers grown by plasma-assisted molecular beam epitaxy. Hall effect, thermopower and electrochemical capacitance voltage experiments have been combined to investigate the conduction properties. The results show the realization of p-type InGaN across the entire alloy composition range.
We fully interpolated frequency gaps between THz comb modes by tuning mode-locked frequencies in dual fiber lasers used for generation and detection of THz comb. The resulting gapless THz comb implies a possibility to enhance the spectral resolution in THz spectroscopy down to the linewidth of each comb mode.
We improved the spectral accuracy in asynchronous-optical-sampling THz time-domain spectroscopy (ASOPS-THz-TDS) by sweeping the mode-locked frequency in dual fiber lasers. We confirmed from THz spectroscopy of low-pressure water vapor that the achieved spectral accuracy largely exceeds the spectral resolution in ASOPS-THz-TDS.
The surface band bending was investigated by angle-resolved XPS measurements in both metal-polar and N-polar GaN and InN films grown by RF-MBE. Clear difference on the bending direction was observed between GaN and InN films.
We fully interpolated frequency gaps between THz-comb modes by their incremental sweeping at intervals of their linewidth, showing the possibility of enhancing the spectral resolution in THz spectroscopy to the linewidth of THz comb mode.
We observed detailed spectrum of THz frequency comb by extending the measured time window of the pulsed THz electric field up to ten pulse periods with asynchronous-optical-sampling THz-TDS (ASOPS-THz-TDS). Observed spectrum of THz comb mode has a linewidth of 5.6 MHz and a frequency interval of 56 MHz.
Spectral resolution and accuracy in asynchronous-optical-sampling THz-TDS was evaluated with the spectroscopy of low-pressure water vapor. The achieved resolution and accuracy were 72.9 MHz and 10−5 at the absorption line of 0.56 THz and 0.75 THz, respectively.
According to electrical output up rating of a permanent magnet motor and request to operate for a large variable speed range, resonance between structural natural vibration and electromagnetic force inside the motor can take place and make noise. This paper describes the mechanism of a resonance between them and noise lowering procedure by frequency shift when they are applied to the reluctance torque...
Two techniques for terahertz (THz) frequency metrology based on frequency comb, namely, a THz-comb-referenced spectrum analyzer and a continuously tunable, single-frequency continuous-wave (CW)-THz generator, are reviewed. Since the frequency comb enables to coherently link the frequency among microwave, optical, and THz regions, it is possible to establish the THz frequency metrology traceable to...
A continuously tunable, phase-locked, THz synthesizer has been demonstrated. This THz synthesizer is based on photomixing of two optical frequency synthesizers composed of CW laser and optical comb, and its output frequency has the same uncertainty as that of a microwave frequency standard used.
We successfully demonstrated fabrication of InN/InGaN multi quantum well (MQW) structures using a novel growth method by utilizing In droplet elimination by radical-beam irradiation (DERI). First, InGaN was grown under a metal rich (Ga+In>N*) condition by supplying Ga, In and N* simultaneously, in which In was preferentially swept out to the surface. Second, the swept In on the InGaN was transformed...
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