16,886 research outputs found
Zero overshoot and fast transient response using a fuzzy logic controller
In some industrial process control systems it is
desirable not to allow an overshoot beyond the setpoint or a threshold, this could be a safety constraint or the requirement of the system. This paper outlines our work in designing a fuzzy PID controller to achieve a step-response with zero overshoot while improving the output transient response. Our designed fuzzy PID controller is applied to stable, marginally stable and unstable systems and their step responses are compared with a tuned conventional PID controller. A comparative case study shows that the proposed fuzzy controller is highly effective and
outperforms the PID controller in achieving a zero overshoot response and enhancing the output transient response
Translational perspectives on perfusion-diffusion mismatch in ischemic stroke
Magnetic resonance imaging has tremendous potential to illuminate ischemic stroke pathophysiology and guide rational treatment decisions. Clinical applications to date have been largely limited to trials. However, recent analyses of the major clinical studies have led to refinements in selection criteria and improved understanding of the potential implications for the risk vs. benefit of thrombolytic therapy. In parallel, preclinical studies have provided complementary information on the evolution of stroke that is difficult to obtain in humans due to the requirement for continuous or repeated imaging and pathological verification. We review the clinical and preclinical advances that have led to perfusion–diffusion mismatch being applied in phase 3 randomized trials and, potentially, future routine clinical practice
Nonlinear polarisation and dissipative correspondence between low frequency fluid and gyrofluid equations
The correspondence between gyrofluid and low frequency fluid equations is
examined. The lowest order conservative effects in ExB advection, parallel
dynamics, and curvature match trivially. The principal concerns are
polarisation fluxes, and dissipative parallel viscosity and parallel heat
fluxes. The emergence of the polarisation heat flux in the fluid model and its
contribution to the energy theorem is reviewed. It is shown that gyroviscosity
and the polarisation fluxes are matched by the finite gyroradius corrections to
advection in the long wavelength limit, provided that the differences between
gyrocenter and particle representations is taken into account. The dissipative
parallel viscosity is matched by the residual thermal anisotropy in the
gyrofluid model in the collision dominated limit. The dissipative parallel heat
flux is matched by the gyrofluid parallel heat flux variables in the collision
dominated limit. Hence, the gyrofluid equations are a complete superset of the
low frequency fluid equations.Comment: RevTeX 4, 28 pages, no figures, final revised version for Physics of
Plasmas prior to proof stag
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