The Experts below are selected from a list of 69999 Experts worldwide ranked by ideXlab platform
R G Mani - One of the best experts on this subject based on the ideXlab platform.
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zero resistance states induced by electromagnetic Wave Excitation in gaas algaas heterostructures
Physica E-low-dimensional Systems & Nanostructures, 2004Co-Authors: R G ManiAbstract:Abstract We report the detection of novel zero-resistance states induced by electromagnetic Wave Excitation in ultra high mobility GaAs/AlGaAs heterostructure devices, at low magnetic fields, B , in the large filling factor limit. Vanishing resistance is observed in the vicinity of B =[4/(4 j +1)] B f , where B f =2πfm ∗ /e , where m ∗ is the effective mass, e is the charge, and f is the microWave frequency. The dependence of the effect is reported as a function of f , the temperature, and the power.
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zero resistance states induced by electromagnetic Wave Excitation in gaas algaas heterostructures
Nature, 2002Co-Authors: R G Mani, J H Smet, K V Klitzing, Venkatesh Narayanamurti, W B Johnson, V UmanskyAbstract:The observation of vanishing electrical resistance in condensed matter has led to the discovery of new phenomena such as, for example, superconductivity, where a zero-resistance state can be detected in a metal below a transition temperature Tc (ref. 1). More recently, quantum Hall effects were discovered from investigations of zero-resistance states at low temperatures and high magnetic fields in two-dimensional electron systems (2DESs)2,3,4. In quantum Hall systems and superconductors, zero-resistance states often coincide with the appearance of a gap in the energy spectrum1,2,4. Here we report the observation of zero-resistance states and energy gaps in a surprising setting5: ultrahigh-mobility GaAs/AlGaAs heterostructures that contain a 2DES exhibit vanishing diagonal resistance without Hall resistance quantization at low temperatures and low magnetic fields when the specimen is subjected to electromagnetic Wave Excitation. Zero-resistance-states occur about magnetic fields B = 4/5 Bf and B = 4/9 Bf, where Bf = 2πfm*/e,m* is the electron mass, e is the electron charge, and f is the electromagnetic-Wave frequency. Activated transport measurements on the resistance minima also indicate an energy gap at the Fermi level6. The results suggest an unexpected radiation-induced, electronic-state-transition in the GaAs/AlGaAs 2DES.
Caterina Riconda - One of the best experts on this subject based on the ideXlab platform.
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Steady magnetic-field generation via surface-plasma-Wave Excitation
Physical Review E, 2011Co-Authors: A. Bigongiari, Michelle Raynaud, Caterina RicondaAbstract:The possibility of inducing a magnetic field via surface plasma-Wave Excitation is investigated with a simple nonrelativistic hydrodynamic model. A static magnetic field is predicted at the plasma surface, scaling with the square of the surface-Wave field amplitude, and the influence of the electron plasma density is studied. In the case of resonant surface-Wave Excitation by laser this result can be applied to low intensities such that the electron quiver velocity in the field of the surface Wave is less than its thermal velocity.
A. Bigongiari - One of the best experts on this subject based on the ideXlab platform.
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Steady magnetic-field generation via surface-plasma-Wave Excitation
Physical Review E, 2011Co-Authors: A. Bigongiari, Michelle Raynaud, Caterina RicondaAbstract:The possibility of inducing a magnetic field via surface plasma-Wave Excitation is investigated with a simple nonrelativistic hydrodynamic model. A static magnetic field is predicted at the plasma surface, scaling with the square of the surface-Wave field amplitude, and the influence of the electron plasma density is studied. In the case of resonant surface-Wave Excitation by laser this result can be applied to low intensities such that the electron quiver velocity in the field of the surface Wave is less than its thermal velocity.
C Joshi - One of the best experts on this subject based on the ideXlab platform.
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nonresonant beat Wave Excitation of relativistic plasma Waves with constant phase velocity for charged particle acceleration
Physical Review E, 2004Co-Authors: C V Filip, R Narang, Ya S Tochitsky, C E Clayton, P Musumeci, R Yoder, K A Marsh, J B Rosenzweig, C Pellegrini, C JoshiAbstract:The nonresonant beat-Wave Excitation of relativistic plasma Waves is studied in two-dimensional simulations and experiments. It is shown through simulations that, as opposed to the resonant case, the accelerating electric fields associated with the nonresonant plasmons are always in phase with the beat-pattern of the laser pulse. The Excitation of such nonresonant relativistic plasma Waves is shown to be possible for plasma densities as high as 14 times the resonant density. The density fluctuations and the fields associated with these Waves have significant magnitudes, facts confirmed experimentally using collinear Thomson scattering and electron injection, respectively. The applicability of these results towards eventual phase-locked acceleration of prebunched and externally injected electrons is discussed.
Paolino Tona - One of the best experts on this subject based on the ideXlab platform.
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Wave Excitation Force Estimation for Wave Energy Converters of the Point-Absorber Type
IEEE Transactions on Control Systems Technology, 2018Co-Authors: H.-n. Nguyen, Paolino TonaAbstract:Advanced control strategies play a crucial role in increasing the energy extraction capacity of Wave energy converters (WECs). So far, the most promising control schemes have predominantly been studied in simulation, based on the idealized assumption of the Wave Excitation force availability in real time. In practical WEC implementations, this is not the case, since this force cannot be measured directly when the WECs are running. Hence the force has to be estimated via measurements of other quantities. Two approaches are presented in this paper to fulfill this objective. The first approach is based on a Kalman filter coupled with a random-walk model of the Wave Excitation force, while a receding horizon – unknown input estimation approach is employed for the second one. The proposed estimation methods are evaluated by using real measurements from a laboratory scale WEC.
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Wave Excitation Force Estimation for Wave Energy Converters of the Point-Absorber Type
IEEE Transactions on Control Systems Technology, 2018Co-Authors: H.-n. Nguyen, Paolino TonaAbstract:Advanced control strategies play a crucial role in increasing the energy extraction capacity of Wave energy converters (WECs). So far, the most promising control schemes have predominantly been studied in simulation, based on the idealized assumption of the Wave Excitation force availability in real time. In practical WEC implementations, this is not the case, since this force cannot be measured directly when the WECs are running. Hence, the force has to be estimated via the measurement of other quantities. Two approaches are presented in this brief to fulfill this objective. The first approach is based on a Kalman filter coupled with a random-walk model of the Wave Excitation force, while a receding horizon-unknown input estimation approach-is employed for the second one. The proposed estimation methods are evaluated by using real measurements from a laboratory scale WEC.
