A commercially available Y-TZP ceramic powder was fabricated under four different sintering profiles in order to investigate the effects of conventional single-stage sintering (SSS) with dwell times of 1 min and 2 h, respectively, compared with two-stage sintering (TSS), on the physical and mechanical properties of Y-TZP. Sintering was performed up to 1400 o C at a ramp rate of 10 o C/min. It w...

The paper deals with the supervisory control of a nonlinear uncertain system in which the switching is directed by the recently introduced state-dependent dwell-time switching logic. The proposed supervisory control architecture is shown to regulate to zero the state of the system without requiring the switching to stop in 4nite time. A signi4cant class of systems to which the control architect...

To the Editor—Intravascular devices (IVD) are a vital part of medical care. IVD-associated infections are an important cause of iatrogenic morbidity in inpatients. IVD-related bloodstream infections (BSI) prolong hospital stay and increase costs. IVD-related phlebitis is also a significant problem. The risk of IVD-associated complications correlates with IVD dwell time. The Centers for Disease ...

It is shown that switching among stable linear systems results in a stable system provided that switching is “slow-on-the-average.” In particular, it is proved that exponential stability is achieved when the number of switches in any finite interval grows linearly with the length of the interval, and the growth rate is sufficiently small. Moreover, the exponential stability is uniform over all ...

Polymerization of RNA from a template DNA is carried out by a molecular machine called RNA polymerase (RNAP). It also uses the template as a track on which it moves as a motor utilizing chemical energy input. The time it spends at each successive monomer of DNA is random; we derive the exact distribution of these “dwell times” in our model. The inverse of the mean dwell time satisfies a Michael...

The asymptotic convergence of a switched nonlinear system in the presence of disturbances is studied. The system switches among a family of integral input-to-state stable systems. The time between two consecutive switchings is not less than a value τD. This dwell-time τD is allowed to take different values according to a function whose argument is the state of the system at the switching times....

We study the problem of adaptively stabilizing time-varying plants using supervisory control, which employs multiple controllers and a supervisory unit that orchestrates switching among the controllers. We show that for bounded disturbances and noise, all the closed-loop signals remain bounded provided that the plant varies slowly enough and the unmodeled dynamics are small enough. Slow variati...

BACKGROUND Eye tracking is an accurate and objective means of measuring an instrument scan pattern. The purpose of this study was to determine if prior aircraft experience, phase of flight, and autopilot mode modified the instrument scan pattern of F-117A pilots. METHODS There were 23 F-117A pilots, grouped by prior aircraft experience, who flew an instrument approach manually and with autopi...