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- Gao, L. (author) conference paper 2000
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Baselmans, J. (author), Hajenius, M. (author), Gao, J. (author), De Korte, P. (author), Klapwijk, T. (author), Voronov, B. (author), Gol'tsman, G. (author)NbN hot electron bolometer (HEB) mixers are at this moment the best heterodyne detectors for frequencies above 1 THz. However, the fabrication procedure of these devices is such that the quality of the interface between the NbN superconducting film and the contact structure is not under good control. This results in a contact resistance between...conference paper 2004
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Klapwijk, T.M. (author), Barends, R. (author), Gao, J.R. (author), Hajenius, M. (author), Baselmans, J.J.A. (author)Improved and reproducible heterodyne mixing (noise temperatures of 950 K at 2.5 THz) has been realized with NbN based hot-electron superconducting devices with low contact resistances. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, has been used to understand the physical...conference paper 2004
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Khosropanah, P. (author), Laauwen, W.M. (author), Gao, J.R. (author), Hajenius, M. (author), Hovenier, J.N. (author), Klapwijk, T.M. (author)We have characterized a heterodyne receiver based on an NbN hot electron bolometer integrated with spiral antenna as mixer and an optically pumped FIR ring laser at 4.3 THz as local oscillator (LO). We succeeded in measuring the receiver output power, responding to the hot/cold load, as a function of bias voltage at optimum LO power. From the...conference paper 2007
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Khosropanah, P. (author), Laauwen, W.M. (author), Hajenius, M. (author), Gao, J.R. (author), Klapwijk, T.M. (author)We have studied the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a spiral antenna at 4.3 THz. Using hot/cold blackbody loads and a beam splitter all in vacuum, we measured a double sideband receiver noise temperature of 1300 K at the optimum local oscillator (LO) power of 330 nW, which is about 12 times the...conference paper 2008
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Mauskopf, P. (author), Morozov, D. (author), Glowacka, D. (author), Goldie, D. (author), Withington, S. (author), Bruijn, M. (author), De Korte, P. (author), Hoevers, H. (author), Ridder, M. (author), Van der Kuur, J. (author), Gao, J.R. (author)We describe the optimization of transition edge superconducting (TES) detectors for use in a far-infrared (FIR) Fourier transform spectrometer (FTS) mounted on a cryogenically cooled space-borne telescope (e.g. SPICA). The required noise equivalent power (NEP) of the detectors is approximately 10?19 W/ ?Hz in order to be lower than the photon...conference paper 2008
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Verhagen, S. (author), Grejner-Brzezinska, D. (author), Retscher, G. (author), Santos, M. (author), Ding, X. (author), Gao, Y. (author), Jin, S. (author)This contribution focuses on geodetic sensor systems and sensor networks for positioning and applications. The key problems in this area will be addressed together with an overview of applications. Global Navigation Satellite Systems (GNSS) and other geodetic techniques play a central role in many applications like engineering, mapping and...conference paper 2009
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Verhagen, S. (author), Retscher, G. (author), Santos, M.C. (author), Ding, X.L. (author), Gao, Y. (author), Jin, S.G. (author)GNSS, InSAR and LIDAR are identified as important techniques when it comes to monitoring and remote sensing of our planet Earth and its atmosphere. In fact, these techniques can be considered as key elements of the Global Geodetic Observing System. Examples of applications are: environmental monitoring; volcano monitoring, land slides, tectonic...conference paper 2009
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Barends, R. (author), Van Vliet, S. (author), Baselmans, J.J.A. (author), Yates, S.J.C. (author), Gao, J.R. (author), Klapwijk, T.M. (author)We present measurements of the quasiparticle relaxation time in Ta superconducting films shaped as planar resonators using the response of the complex conductivity to photon flux. These films have been implanted with magnetic (Mn) as well as non-magnetic atoms (Al). We find a significant decrease of the relaxation time with increasing impurity...conference paper 2009
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Ren, Y. (author), Gao, J.R. (author), Hovenier, J.N.Higgins, R. (author), Zhang, W. (author), Bell, A. (author), Klein, B. (author), Klapwijk, T.M. (author)High-resolution heterodyne spectrometers operating at above 2 THz are crucial for detecting, e.g., the HD line at 2.7 THz and oxygen OI line at 4.7 THz in astronomy. The potential receiver technology is a combination of a hot electron bolometer (HEB) mixer and a THz quantum cascade laser (QCL) local oscillator (LO).Here we report the first...conference paper 2010
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Zhang, W. (author), Gao, J.R. (author), Khosropanah, P. (author), Bansal, T. (author), Klapwijk, T.M. (author), Miao, W. (author), Shi, S.C. (author)We report the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a tight spiral antenna at 5.3 THz. Using a measurement setup with black body calibration sources and a beam splitter in vacuo, and an antireflection coated Si lens, we obtained a double sideband receiver noise temperature of 1150 K, which is 4.5 times...conference paper 2010
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- Khosropanah, P. (author), Dirks, B. (author), Parra-Borderias, M. (author), Ridder, M. (author), Hijmering, R. (author), Van der Kuur, J. (author), Gottardi, L. (author), Bruijn, M. (author), Popescu, M. (author), Gao, J.R. (author), Hoevers, H. (author) conference paper 2010
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- Gao, Lingfeng (author), Ghaemi, Reza (author), Sun, Jing (author) conference paper 2011
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Gao, M. (author), Roelvink, J.A. (author)It is estimated that the waterway in North Passage would not be able to meet the demand of shipping development soon and it is necessary to open a new deep navigation channel with a depth of 10 m in North Channel in the near future. A pilot study on the regulation of North Channel was proposed by Yangtze Estuary Waterway Administration Bureau...conference paper 2011
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Bozdag, V.E. (author), Gao, Q. (author), Warnier, M.E. (author), Houben, G.J.P.M. (author)Information diversity has a long tradition in human history. Recently there have been claims that diversity is diminishing in information available in social networks. On the other hand, some studies suggest that diversity is actually quite high in social networks such as Twitter. However these studies only focus on the concept of source...conference paper 2013
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- Tao, Y. (author), Gao, D.W. (author), Wang, H.Y. (author), Zhang, X. (author), Ghasimi, S.M.D. (author), Ozgun, H. (author), Ersahin, M.E. (author), Zhou, Z.B. (author), Liu, G. (author), Temudo, M.F. (author), Kloek, J. (author), Spanjers, H. (author), De Kreuk, M.K. (author), Van Lier, J.B. (author) conference paper 2014
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Luo, Y.C. (author), Liu, X.X. (author), Hayton, D.J. (author), Wei, L. (author), Gao, J.R. (author), Groppi, C. (author)A Fourier phase grating mirror will be applied to split a single, coherent terahertz source beam into multi-beams, which are spatially distributed as required for the local oscillator in an array receiver. We report on the simulation, design and fabrication of a Fourier phase grating at 1.25 THz for generating 2×2 beams, and the measurements at...conference paper 2015
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The evolution of coherent structures in a flat plate boundary layer transition induced by the cylinder wake is investigated using the particle image velocimetry (PIV) technique. The finite-time Lyapunov exponent (FTLE), which characterizes the amount of stretching about the flow trajectory, is used to extract the Lagrangian coherent structures....conference paper 2015
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Gao, L. (author), Zhang, L.M. (author), Chen, H.X. (author)Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the...conference paper 2015
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Alonso Del Pino, M. (author), Cavallo, D. (author), Thippur Shivamurthy, H. (author), Gao, H. (author), Spirito, M. (author)This contribution presents the development of an integrated power combiner in Bi-CMOS technology employing artificial dielectric layers (ADLs) at submillimeter wave frequencies. The power is gathered from frequency multiplier chains into a single waveguide which is loaded with ADL in order to reduce the structure footprint.conference paper 2015