Search results for "Time control"
showing 10 items of 21 documents
Real-time Control of Metallurgic Processes
1996
The careful control of the liquid metal solidification and the solid shell growth is of central importance in all metallurgic processes. These have a considerable influence on the formation of cracks and other defects which can be formed in the cast material. To ensure defect free products, the liquid metal is to be cooled down according to a pattern which depends i.e. on metal grade, product dimension, cooling speed and machine design. On the other hand, the control of the liquid/solid interface is a key element in optimising the liquid solidification with respect to good productivity. So, the heat transfer plays a very important role in metallurgic casting processes, especially when casti…
Predictive dead time controller for GaN-based boost converters
2017
A dynamic dead time controller is presented, specifically intended to operate in synchronous boost converters based on GaN field-effect transistor switches. These transistors have a reduced stored charge with respect to silicon metal–oxide–semiconductor field-effect transistors with similar breakdown voltage and series resistance, and can operate at higher frequencies with reduced switching losses. On the other hand, the voltage drop in reverse conduction is typically more than doubled with respect to silicon devices resulting in relevant power losses during the free-wheeling phases. Therefore, dynamic control of dead time can be profitably applied even in converters operating in the tens o…
Time and Performance Pressure
2018
Abstract. Time pressure and performance pressure are among the most crucial job demands of today’s workforce. However, the literature on psychological stress barely distinguishes between these constructs. Therefore, we aimed to examine time pressure and performance pressure as two qualitatively different job demands in terms of unique moderators for both demands. We investigated whether time control would moderate the relationship between time pressure and both emotional exhaustion and work engagement. As a vulnerability factor for dealing with performance pressure, we investigated perfectionism. The cross-sectional data of 167 employees showed that time control was a significant moderator…
The effects of using participatory working time scheduling software on sickness absence: A difference-in-differences study.
2020
Abstract Background Participatory working time scheduling is a collaborative approach to scheduling shift work. As a potential way of improving work time control, it may provide a means to reducing sickness absence in shift work. So far, experimental and quasi-experimental studies on the effects of increased work time control on sickness absence are lacking. Objective To investigate the effects of using digital participatory working time scheduling software on ward-level sickness absence among Finnish hospital employees. Participants and methods This quasi-experimental study compared the amount of sickness absence in hospital wards using a participatory working time scheduling software (n=1…
Controlling Domains with High Levels of Hysteresis Using Qualitative Modelling
1997
Abstract Dans ce papier, on se propose I'architecture d'un systeme expert pour controle a temps reel basee sur un modele qualitatif- Le susteme de controle utilise le modele qualitatif pour predire problemes futures et pour manier dounees incompletes et imprecises des sensors. Cettes habilites sout tres precieses pour controler systemes avec une grande niveau d'hysteresis, et foumissent un controle doux et rapide. Nous avans applique l'architecture proposee a le domaine du control de trafic urbain, caracterise par grandes problemes d'hysteresis.
Toward more realistic viscosity measurements of tyre rubber–bitumen blends
2014
AbstractThe measurement of rheological properties of the tyre rubber bitumen blends is often challenging due to presence of suspended tyre rubber’s crumbs. Furthermore, the phase separation during the course of measurements makes the viscosity of these non-homogeneous blends difficult to ascertain. In this study, a new dual helical impeller was designed and manufactured to be used with a rotational viscometer in order to have a real-time control of the viscosity while performing a laboratory mixing of the blends. Layer based manufacturing techniques showed to be a convenient method to produce complex shaped impeller prototypes before manufacturing the more expensive stainless steel assembly…
The effects of using participatory working time scheduling software on working hour characteristics and wellbeing : a quasi-experimental study of irr…
2020
Background: Studies in the health care sector indicate that good work time control is associated with better perceived wellbeing but also with non-ergonomic work schedules, such as compressed work schedules. Participatory working time scheduling is a collaborative approach to scheduling shift work. Currently, there is a lack of information on whether working hour characteristics and employees' wellbeing in irregular shift work change after implementing participatory working time scheduling. Objective: To investigate the effects of using digital participatory working time scheduling software on working hour characteristics and well-being among Finnish hospital employees. Participants and met…
Time minimization versus energy minimization in the one-input controlled Kepler problem with weak propulsion
2014
International audience
Robust delay-dependent H∞ control of uncertain time-delay systems with mixed neutral, discrete, and distributed time-delays and Markovian switching p…
2011
Author's version of an article published in the journal: IEEE Transactions on Circuits and Systems I: Regular Papers. Also available from the publisher at: http://dx.doi.org/10.1109/tcsi.2011.2106090 The problem of robust mode-dependent delayed state feedback H ∞ control is investigated for a class of uncertain time-delay systems with Markovian switching parameters and mixed discrete, neutral, and distributed delays. Based on the LyapunovKrasovskii functional theory, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities for the stochastic stability and stabilization of the considered system using some free matrices. The desired control is …