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Constant Delay (constant + delay)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Monitoring of CBFV and time characteristics of oxygen-induced acute CNS toxicity in humans

EUROPEAN JOURNAL OF NEUROLOGY, Issue 7 2008
A. E. Koch
Background:, Hyperbaric oxygen can cause central nervous system (CNS) toxicity with seizures. We tested the hypothesis that CNS toxicity could be predictable by cerebral blood flow velocity (CBFV) monitoring. Method:, We monitored 369 mandatory oxygen tolerance tests (30 min, 280 kPa O2) by video-documentation and since May 2005 by additional CBFV registration (n = 61). Results:, The onset of early manifestations of CNS toxicity was documented in 11 of 369 tests within 22 ± 3 min. These included twitches and/or agitation, 6 of 11 and tonic,clonic seizures in 5 of 11 cases. In both cases with CBFV monitoring, an increase in CBFV preceded symptom onset, once followed by seizure, once without seizure after timely oxygen reduction. Conclusions:, During exposure to 280 kPa oxygen at rest a constant delay of approximately 20 min precedes the onset of central nervous oxygen toxicity. An increase in CBFV may indicate the impending seizure. [source]

Temporal filtering by prefrontal neurons in duration discrimination

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2008
Ken-ichi Oshio
Abstract Neural imaging studies have revealed that the prefrontal cortex (PFC) participates in time perception. However, actual functional roles remain unclear. We trained two monkeys to perform a duration-discrimination task, in which two visual cues were presented consecutively for different durations ranging from 0.2 to 2.0 s. The subjects were required to choose the longer cue. We recorded single-neuron activity from the PFC while the subjects were performing the task. Responsive neurons for the first cue period were extracted and classified through a cluster analysis of firing rate curves. The neuronal activity was categorized as phasic, ramping and sustained patterns. Among them, the phasic activity was the most prevailing. Peak time of the phasic activity was broadly distributed about 0.8 s after cue onset, leading to a natural assumption that the phasic activity was related to cognitive processes. The phasic activity with constant delay after cue onset might function to filter current cue duration with the peak time. The broad distribution of the peak time would indicate that various filtering durations had been prepared for estimating C1 duration. The most frequent peak time was close to the time separating cue durations into long and short. The activity with this peak time might have had a role of filtering in attempted duration discrimination. Our results suggest that the PFC contributes to duration discrimination with temporal filtering in the cue period. [source]

Linear quadratic regulation for systems with time-varying delay

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3 2010
Huanshui Zhang
Abstract In this paper we study the linear quadratic regulation (LQR) problem for discrete-time systems with time-varying delay in the control input channel. We assume that the time-varying delay is of a known upper bound, then the LQR problem is transformed into the optimal control problem for systems with multiple input channels, each of which has single constant delay. The optimal controller is derived by establishing a duality between the LQR and a smoothing estimation for an associated system with a multiple delayed measurement. Copyright © 2009 John Wiley & Sons, Ltd. [source]

STABILITY CONDITION OF DISTRIBUTED DELAY SYSTEMS BASED ON AN ANALYTIC SOLUTION TO LYAPUNOV FUNCTIONAL EQUATIONS

ASIAN JOURNAL OF CONTROL, Issue 1 2006
Young Soo Suh
ABSTRACT An analytic solution to Lyapunov functional equations for distributed delay systems is derived. The analytic solution is computed using a matrix exponential function, while conventional computation has been relied on numerical approximations. Based on the analytic solution, a necessary and sufficient stability condition for distributed delay systems with unknown but bounded constant delay is proposed. [source]