The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Glenn R. Heppler - One of the best experts on this subject based on the ideXlab platform.
-
Shaped Input Control of a System With Multiple Modes
Journal of Dynamic Systems Measurement and Control-transactions of The Asme, 1993Co-Authors: T Singh, Glenn R. HepplerAbstract:This paper describes a method for limiting vibration in flexible systems that have more than one Characteristic Frequency and mode. It is only necessary to have knowledge of the component mode frequencies and damping ratios in order to be able to calculate the timing and magnitudes of the impulse sequence used in the shaping. Only two impulses, in the nonrobust case, or three impulses in a more robust case, are necessary regardless of the number of component frequencies. Simple tests are established to determine when this technique can be used and examples are presented.
-
ICRA (3) - Shaped inputs for a multimode system
[1993] Proceedings IEEE International Conference on Robotics and Automation, 1993Co-Authors: T Singh, Glenn R. HepplerAbstract:A method for limiting vibration in flexible systems that have more than one Characteristic Frequency and mode is presented. It is only necessary to have knowledge of the component mode frequencies and damping ratios in order to be able to calculate the timing and magnitudes of the impulse sequence used in the shaping. Only two impulses, in the nonrobust case, or three impulses, in a more robust case, are necessary regardless of the number of component frequencies. >
Bassam Bamieh - One of the best experts on this subject based on the ideXlab platform.
-
Calibration of the Characteristic Frequency of an optical tweezer using a recursive least-squares approach
Proceedings of the 2004 American Control Conference, 2004Co-Authors: A. Ranaweera, Bassam BamiehAbstract:We describe the use of a recursive least-squares approach for calibration of the Characteristic Frequency of an optical tweezer. Unlike commonly used off-line calibration methods, the RLS algorithm does not require data averaging to reduce the effects of Brownian motion. We use computer simulations to demonstrate that the RLS algorithm can be used to efficiently calibrate the Characteristic Frequency of a trapped, 10-micron diameter polystyrene bead. However, experimental results suggest that applying the RLS method to an actual optical tweezer system is more difficult because of the measurement errors and laboratory noise.
-
Calibration of the Characteristic Frequency of an optical tweezer using an adaptive normalized gradient approach
Proceedings of the 2003 American Control Conference 2003., 1Co-Authors: A. Ranaweera, Bassam BamiehAbstract:We describe the use of a normalized gradient approach for calibration of the Characteristic Frequency of an optical tweezer. Unlike existing methods that require purely off-line data analysis, the method discussed here can be performed on-line, provided a running average is periodically computed to reduce the effects of Brownian motion. We describe the experimental setup used for calibration of the optical tweezers and calculate the Characteristic Frequency of a trapped, 10-micron diameter polystyrene bead by processing experimental data using the normalized gradient algorithm and two existing off-line calibration methods. The three methods yield similar values for the Characteristic Frequency.
T Singh - One of the best experts on this subject based on the ideXlab platform.
-
Shaped Input Control of a System With Multiple Modes
Journal of Dynamic Systems Measurement and Control-transactions of The Asme, 1993Co-Authors: T Singh, Glenn R. HepplerAbstract:This paper describes a method for limiting vibration in flexible systems that have more than one Characteristic Frequency and mode. It is only necessary to have knowledge of the component mode frequencies and damping ratios in order to be able to calculate the timing and magnitudes of the impulse sequence used in the shaping. Only two impulses, in the nonrobust case, or three impulses in a more robust case, are necessary regardless of the number of component frequencies. Simple tests are established to determine when this technique can be used and examples are presented.
-
ICRA (3) - Shaped inputs for a multimode system
[1993] Proceedings IEEE International Conference on Robotics and Automation, 1993Co-Authors: T Singh, Glenn R. HepplerAbstract:A method for limiting vibration in flexible systems that have more than one Characteristic Frequency and mode is presented. It is only necessary to have knowledge of the component mode frequencies and damping ratios in order to be able to calculate the timing and magnitudes of the impulse sequence used in the shaping. Only two impulses, in the nonrobust case, or three impulses, in a more robust case, are necessary regardless of the number of component frequencies. >
Sherri E. Kroening - One of the best experts on this subject based on the ideXlab platform.
-
The origin of a Characteristic Frequency in hard thermal turbulence
Physics of Fluids, 1991Co-Authors: Alain P. Vincent, Andrei V. Malevsky, Ulrich Hansen, Sherri E. KroeningAbstract:New methods are proposed for filtering the time series of heat flux which is useful for detecting the Characteristic frequencies in hard turbulent convection. High‐resolution solutions have been obtained for a Rayleigh (Ra) of 108 and infinite Prandtl number in a box with an aspect ratio of 1.8, in which the finest grid consisting of 140×400 bicubic splines was used. Successively higher temporal derivatives and high‐pass spectral filtering of the Nusselt number at this high Ra reveal the existence of bursts. They are closely related to the presence of plumes in the thermal boundary layer in that there is a relative absence of activity in the boundary layer just before the onset of a burst and, on the other hand, there is a period of intense activity shortly before the end of a burst. These bursts are spaced evenly in time, thus yielding a single Characteristic Frequency, which may be related to a period associated with a pulsation mechanism in hard turbulent convection.
Raju Metherate - One of the best experts on this subject based on the ideXlab platform.
-
Spectral integration in primary auditory cortex: laminar processing of afferent input, in vivo and in vitro.
Neuroscience, 2005Co-Authors: Simranjit Kaur, Heather J. Rose, Ronit Lazar, Kevin Liang, Raju MetherateAbstract:Auditory cortex neurons integrate information over a broad range of sound frequencies, yet it is not known how such integration is accomplished at the cellular or systems levels. Whereas information about frequencies near a neuron’s Characteristic Frequency is likely to be relayed to the neuron by lemniscal thalamocortical inputs from the ventral division of the medial geniculate nucleus, we recently proposed that information about frequencies spectrally distant from Characteristic Frequency is mainly relayed to the neuron via “horizontal” intracortical projections from neurons with spectrally-distant Characteristic frequencies [J Neurophysiol 91 (2004) 2551]. Here we test this hypothesis by using current source density analysis to determine if Characteristic Frequency and spectrally-distant non-Characteristic Frequency stimuli preferentially activate thalamocortical and horizontal pathways, respectively, in rat auditory cortex. Characteristic Frequency stimuli produced current source density profiles with prominent initial current sinks in layers 3 and 4—the termination zone of lemniscal inputs from medial geniculate nucleus. In contrast, stimuli three octaves below Characteristic Frequency produced initial current sinks mainly in the infragranular layers. Differences between current source density profiles were only apparent for initial current sinks; profiles for longer-latency current sinks evoked by Characteristic Frequency and non-Characteristic Frequency stimuli overlapped to a greater degree, likely due to shared mechanisms of intracortical processing or to longer-latency thalamocortical contributions (lemniscal and nonlemniscal). To identify current source density profiles produced by activation of lemniscal thalamocortical inputs alone, we utilized the mouse auditory thalamocortical slice preparation. Electrical stimulation of the medial geniculate nucleus in vitro produced major current sinks in cortical layers 3/4, and excitation spread horizontally from this point throughout primary auditory cortex to produce current sinks in multiple cortical layers. These data support the hypothesis that relay of thalamocortical information throughout auditory cortex via horizontal intracortical projections may be the basis of broad spectral integration in vivo.