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Institution

University of Electro-Communications

EducationTokyo, Japan
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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11mJ Nd:YLF laser, was used to ascertain the true amplified seed energy and the parametric superfluorescence levels.
Abstract: We produce carrier-envelope-phase-stable 15.7-fs (2-cycle) 740-μJ pulses at the 2.1-μm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11-mJ Nd:YLF laser. A novel seed pulse spectral shaping method is used to ascertain the true amplified seed energy and the parametric superfluorescence levels.

127 citations

Journal ArticleDOI
TL;DR: In this article, a general concept of mechanisms of preseismic phenomena in the atmosphere and ionosphere is presented, and the authors conclude that upward migration of fluid substrate matter (bubble) can lead to ousting of hot water/gas near the ground surface and cause an earthquake (EQ) itself in the strength-weakened area.
Abstract: . We present a general concept of mechanisms of preseismic phenomena in the atmosphere and ionosphere. After short review of observational results we conclude: 1. Upward migration of fluid substrate matter (bubble) can lead to ousting of the hot water/gas near the ground surface and cause an earthquake (EQ) itself in the strength-weakened area; 2. Thus, time and place of the bubble appearance could be random values, but EQ, geochemistry anomaly and foreshocks (seismic, SA and ULF electromagnetic ones) are casually connected; 3. Atmospheric perturbation of temperature and density could follow preseismic hot water/gas release resulting in generation of atmospheric gravity waves (AGW) with periods in a range of 6–60min; 4. Seismo-induced AGW could lead to modification of the ionospheric turbulence and to the change of over-horizon radio-wave propagation in the atmosphere, perturbation of LF waves in the lower ionosphere and ULF emission depression at the ground.

126 citations

Journal ArticleDOI
TL;DR: A novel imaging algorithm without range point connection is proposed to accomplish high-quality and flexible 3-D imaging for various target shapes and several comparative studies of conventional algorithms clarify that the proposed method accomplishes accurate and reliable 3- D imaging even for complex or multiple boundaries.
Abstract: Ultrawide-band pulse radars have immeasurable potential for a high-range-resolution imaging in the near field and can be used for noncontact measurement of industrial products with specular or precision surfaces, such as reflector antenna or aircraft fuselage, or identifying and locating the human body in security systems. In our previous work, we developed a stable and high-speed 3-D imaging algorithm, Envelope, which is based on the principle that a target boundary can be expressed as inner or outer envelopes of spheres, which are determined using antenna location and observed ranges. Although Envelope produces a high-resolution image for a simple shape target that may include edges, it requires an exact connection for observed ranges to maintain the imaging quality. For complex shapes or multiple targets, this connection becomes a difficult task because each antenna receives multiple echoes from many scattering points on the target surface. This paper proposes a novel imaging algorithm without range point connection to accomplish high-quality and flexible 3-D imaging for various target shapes. The algorithm uses an accurate estimation for the direction of arrival using signal amplitudes and realizes direct mapping from observed ranges to target points. Several comparative studies of conventional algorithms clarify that our proposed method accomplishes accurate and reliable 3-D imaging even for complex or multiple boundaries.

126 citations

Journal ArticleDOI
TL;DR: In this paper, the authors choose CdSe0.65Te0.35 as a model core material, and CdS shell was then overcoated around the core QD to decrease surface defect density and to increase the stability of the core DQDs.
Abstract: Surface trap defects are the limited factor for quantum dots (QDs) application in solar cells. The trapping states can be efficiently suppressed by coating a shell of wider band gap material around the core QDs. We choose CdSe0.65Te0.35 (simplified as CdSeTe) as a model core material, and CdS shell was then overcoated around the CdSeTe core QD to decrease surface defect density and to increase the stability of the core QDs. By optimizing the thickness of the CdS shell, the power conversion efficiency (PCE) of the CdSeTe/CdS quantum dots sensitized solar cells (QDSCs) is enhanced by 13% in comparison with that of plain CdSeTe QDSCs. Transient absorption (TA), incident-photo-to-carrier conversion efficiency (IPCE), open-circuit voltage decay (OVCD), and electrochemical impedance spectroscopy (EIS) measurements confirmed the suppressed charge recombination process in internal QDs and QD/TiO2/electrolyte interfaces with the overcoating of CdS shell around CdSeTe core QDs. With the further overcoating of a-TiO...

126 citations

Journal ArticleDOI
01 Feb 2006
TL;DR: This paper shows that switching fuzzy controller design conditions based on the switching Lyapunov function are given in terms of bilinear matrix inequalities, which is difficult to design the controller numerically, and proposes a new controller design approach utilizing an augmented system.
Abstract: This paper presents a switching fuzzy controller design for a class of nonlinear systems. A switching fuzzy model is employed to represent the dynamics of a nonlinear system. In our previous papers, we proposed the switching fuzzy model and a switching Lyapunov function and derived stability conditions for open-loop systems. In this paper, we design a switching fuzzy controller. We firstly show that switching fuzzy controller design conditions based on the switching Lyapunov function are given in terms of bilinear matrix inequalities, which is difficult to design the controller numerically. Then, we propose a new controller design approach utilizing an augmented system. By introducing the augmented system which consists of the switching fuzzy model and a stable linear system, the controller design conditions based on the switching Lyapunov function are given in terms of linear matrix inequalities (LMIs). Therefore, we can effectively design the switching fuzzy controller via LMI-based approach. A design example illustrates the utility of this approach. Moreover, we show that the approach proposed in this paper is available in the research area of piecewise linear control.

126 citations


Authors

Showing all 8079 results

NameH-indexPapersCitations
Mildred S. Dresselhaus136762112525
Matthew Nguyen131129184346
Juan Bisquert10745046267
Dapeng Yu9474533613
Riichiro Saito9150248869
Shun-ichi Amari9049540383
Shigeru Nagase7661722099
Ingrid Verbauwhede7257521110
Satoshi Hasegawa6970822153
Yu Qiao6948429922
Yukio Tanaka6874419942
Zhijun Li6861414518
Iván Mora-Seró6723523229
Kazuo Tanaka6353527559
Da Xing6362414766
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202317
202258
2021644
2020815
2019908
2018837