The Experts below are selected from a list of 310266 Experts worldwide ranked by ideXlab platform
M Valovic - One of the best experts on this subject based on the ideXlab platform.
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collisionality and safety factor scalings of h Mode Energy transport in the mast spherical tokamak
Nuclear Fusion, 2011Co-Authors: M Valovic, R J Akers, L Garzotti, A Patel, M De Bock, J Mccone, Clive Michael, G Naylor, C M Roach, R ScannellAbstract:A factor of 4 dimensionless collisionality scan of H-Mode plasmas in MAST shows that the thermal Energy confinement time scales as . Local heat transport is dominated by electrons and is consistent with the global scaling. The neutron rate is in good agreement with the ν* dependence of τE,th. The gyrokinetic code GYRO indicates that micro-tearing turbulence might explain such a trend. A factor of 1.4 dimensionless safety factor scan shows that the Energy confinement time scales as . These two scalings are consistent with the dependence of Energy confinement time on plasma current and magnetic field. Weaker qeng and stronger ν* dependences compared with the IPB98y2 scaling could be favourable for an ST-CTF device, in that it would allow operation at lower plasma current.
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scaling of h Mode Energy confinement with ip and bt in the mast spherical tokamak
Nuclear Fusion, 2009Co-Authors: M Valovic, R J Akers, G Cunningham, L Garzotti, B Lloyd, D Muir, A Patel, D Taylor, M Turnyanskiy, M WalshAbstract:The dependences of Energy confinement on plasma current and toroidal magnetic field have been investigated in the MAST spherical tokamak in H-Mode plasmas. Multivariate fits show that the dependence of Energy confinement time on plasma current Ip is weaker than linear while the dependence on toroidal magnetic field BT is stronger than linear, in contrast to conventional Energy confinement scalings. These Ip and BT dependences have also been confirmed by single parameter scans. Transport analysis indicates that the strong BT scaling of Energy confinement could possibly be explained by weaker q and stronger ν* dependence of heat diffusivity in comparison with conventional tokamaks.
Tong Zhang - One of the best experts on this subject based on the ideXlab platform.
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multi Mode Energy management strategy for fuel cell electric vehicles based on driving pattern identification using learning vector quantization neural network algorithm
Journal of Power Sources, 2018Co-Authors: Ke Song, Wenxu Niu, Tong ZhangAbstract:Abstract The development of fuel cell electric vehicles can to a certain extent alleviate worldwide Energy and environmental issues. While a single Energy management strategy cannot meet the complex road conditions of an actual vehicle, this article proposes a multi-Mode Energy management strategy for electric vehicles with a fuel cell range extender based on driving condition recognition technology, which contains a patterns recognizer and a multi-Mode Energy management controller. This paper introduces a learning vector quantization (LVQ) neural network to design the driving patterns recognizer according to a vehicle's driving information. This multi-Mode strategy can automatically switch to the genetic algorithm optimized thermostat strategy under specific driving conditions in the light of the differences in condition recognition results. Simulation experiments were carried out based on the Model's validity verification using a dynamometer test bench. Simulation results show that the proposed strategy can obtain better economic performance than the single-Mode thermostat strategy under dynamic driving conditions.
Zhengbao Yang - One of the best experts on this subject based on the ideXlab platform.
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distributed parameter Modeling and dynamic analysis of rotational compressive Mode Energy harvesters
Nonlinear Dynamics, 2021Co-Authors: Yilong Wang, Zhengbao Yang, Dengqing CaoAbstract:This paper presents a Modeling and dynamic analysis of a rotational high-efficiency compressive-Mode piezoelectric Energy harvester (HC-PEH) with partially thickened bow-shaped beams. Based on the Euler–Bernoulli beam theory and the extended Hamilton’s principle, the governing equations of the rotational HC-PEH system are formulated. The nonlinear electromechanical coupling partial differential equations of the system are transformed into ordinary differential equations in the truncated modal coordinates. The developed distributed-parameter Model is validated against experimental data, and a good agreement is achieved. The stability and the nonlinear dynamic behavior of the rotational HC-PEH system in conditions of different offset distances and preloaded axial forces are investigated by numerical simulation results. A parametric study of the parameters directly related to the system design is also performed to provide fundamental guidance for understanding the electrical output performance and modulating the voltage–rotation speed responses of the harvester. The result shows that the design parameters of the bow-shaped beam and the PZT plate have apparent effects on the electrical output of the harvester system.
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high efficiency compressive Mode Energy harvester enhanced by a multi stage force amplification mechanism
Energy Conversion and Management, 2014Co-Authors: Zhengbao YangAbstract:Abstract Harnessing ambient vibration Energy using piezoelectric materials is a promising alternative solution to batteries to inexhaustibly power small-scale mobile devices. This paper presents an innovative Energy harvester, named high-efficiency compressive-Mode piezoelectric Energy harvester (HC-PEH). It consists of a pair of elastic beams and a flex-compressive center where the piezoelectric element bears a dynamic compressive load. The compressive Mode is preferred than the commonly-used bending Mode and tensile Mode due to the superior compressive strength of piezoceramics. To cater to the characteristic of piezoceramics: large ultimate stress, but extremely small ultimate strain, a multi-stage force amplification mechanism is developed in the design. The HC-PEH shows superior capability of high power output and favorable nonlinear phenomena at low frequency range. Under an acceleration of 0.5 g (g = 9.8 m/s 2 ), a maximum power of 19 mW is produced at 21 Hz, which is about one order of magnitude higher than the power output of Energy harvesters previously reported. The capability of high power output of the HC-PEH demonstrates the practicability of using Energy harvesters to power most of wireless sensors.
E S Marmar - One of the best experts on this subject based on the ideXlab platform.
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rotation reversal bifurcation and Energy confinement saturation in tokamak ohmic l Mode plasmas
Physical Review Letters, 2011Co-Authors: John E Rice, J W Hughes, M Greenwald, I Cziegler, P H Diamond, B P Duval, Yuri Podpaly, M L Reinke, P Ennever, E S MarmarAbstract:Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-Mode plasmas following electron density ramps. For low density discharges, the core rotation is directed cocurrent, and reverses to countercurrent following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm(-1) <= k(theta) <= 11 cm(-1) and frequencies above 70 kHz. There is a strong correlation between the reversal density and the density at which the Ohmic L-Mode Energy confinement changes from the linear to the saturated regime.
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rotation reversal bifurcation and Energy confinement saturation in tokamak ohmic l Mode plasmas
APS, 2011Co-Authors: John E Rice, J W Hughes, M Greenwald, I Cziegler, P H Diamond, B P Duval, Yuri Podpaly, M L Reinke, P Ennever, E S MarmarAbstract:Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-Mode plasmas following electron density ramps. For low density discharges, the rotation is directed co-current, and reverses to counter-current following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm ≤ kθ ≤ 11 cm and frequencies above 70 kHz. There is a strong correlation between the reversal density and the density at which the Ohmic L-Mode Energy confinement changes from the linear to the saturated regime.
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i Mode an h Mode Energy confinement regime with l Mode particle transport in alcator c mod
Nuclear Fusion, 2010Co-Authors: D G Whyte, A E Hubbard, J W Hughes, B Lipschultz, J E Rice, E S Marmar, M Greenwald, I Cziegler, A Dominguez, T GolfinopoulosAbstract:An improved Energy confinement regime, I-Mode, is studied in Alcator C-Mod, a compact high-field divertor tokamak using ion cyclotron range of frequencies (ICRFs) auxiliary heating. I-Mode features an edge Energy transport barrier without an accompanying particle barrier, leading to several performance benefits. H-Mode Energy confinement is obtained without core impurity accumulation, resulting in reduced impurity radiation with a high-Z metal wall and ICRF heating. I-Mode has a stationary temperature pedestal with edge localized Modes typically absent, while plasma density is controlled using divertor cryopumping. I-Mode is a confinement regime that appears distinct from both L-Mode and H-Mode, combining the most favourable elements of both. The I-Mode regime is investigated predominately with ion ∇B drift away from the active X-point. The transition from L-Mode to I-Mode is primarily identified by the formation of a high temperature edge pedestal, while the edge density profile remains nearly identical to L-Mode. Laser blowoff injection shows that I-Mode core impurity confinement times are nearly identical with those in L-Mode, despite the enhanced Energy confinement. In addition, a weakly coherent edge MHD Mode is apparent at high frequency ~100–300 kHz which appears to increase particle transport in the edge. The I-Mode regime has been obtained over a wide parameter space (BT = 3–6 T, Ip = 0.7–1.3 MA, q95 = 2.5–5). In general, the I-Mode exhibits the strongest edge temperature pedestal (Tped) and normalized Energy confinement (H98 > 1) at low q95 ( 4 MW). I-Mode significantly expands the operational space of edge localized Mode (ELM)-free, stationary pedestals in C-Mod to Tped ~ 1 keV and low collisionality , as compared with EDA H-Mode with Tped . The I-Mode global Energy confinement has a relatively weak degradation with heating power; leading to increasing H98 with heating power.
M Walsh - One of the best experts on this subject based on the ideXlab platform.
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scaling of h Mode Energy confinement with ip and bt in the mast spherical tokamak
Nuclear Fusion, 2009Co-Authors: M Valovic, R J Akers, G Cunningham, L Garzotti, B Lloyd, D Muir, A Patel, D Taylor, M Turnyanskiy, M WalshAbstract:The dependences of Energy confinement on plasma current and toroidal magnetic field have been investigated in the MAST spherical tokamak in H-Mode plasmas. Multivariate fits show that the dependence of Energy confinement time on plasma current Ip is weaker than linear while the dependence on toroidal magnetic field BT is stronger than linear, in contrast to conventional Energy confinement scalings. These Ip and BT dependences have also been confirmed by single parameter scans. Transport analysis indicates that the strong BT scaling of Energy confinement could possibly be explained by weaker q and stronger ν* dependence of heat diffusivity in comparison with conventional tokamaks.