405 research outputs found
Heart "timing" versus artery "timing". Neurovegetative effects in compensated and decompensated heart failure
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Performance of gas turbine power plants controlled by the multiagent scheme
No full textIn recent years the idea of artificial intelligence has been focused around the concept of rational
agent. An agent is a (software or hardware) entity that can receive signals from the environment and act
upon that environment through output signals, trying to carry out an appropriate task. Seldom agents are
considered as stand-alone systems; on the contrary, their main strength can be found in the interaction
with other agents, constituting the so called multiagent system.
In the present work, a multiagent system was chosen as control system of a single-shaft heavy-duty
gas turbine in Multi Input Multi Output mode. The shaft rotational speed (power frequency) and stack
temperature (related to the overall gas turbine efficiency) represent the controlled variables; on the other
hand, the fuel mass flow (VCE) and the Variable Inlet Guide Vanes (VIGV) have be chosen as manipulating
variables.
The results will show that the multiagent approach to the control problem effectively counteracts the
load reduction (including the load rejection condition) with limited overshoot in the controlled variables
(as other control algorithms do) while showing good level adaptivity readiness, precision, robustness and
stability
Sicurezza per le donne o strategia neoliberale? : Un'analisi critica attraverso la lente riproduzione sociale
No full textRight ventricular myocardial function in ARF patients: PEEP as a challenge for right heart - Reply
No full textControl of Gas turbine power plants by means of the weighted one-step-ahead adaptive technique
No full textThe one-step-ahead controllers represent a branch of minimum prediction error adaptive controllers. They combine the parameter estimation of the controlled system model with the control scheme; therefore, they are especially suitable for non-linear and time-varying systems. Since the estimated parameters are updated at each time step (by using the sampled data), these methods can be adopted for non-linear applications. Consequently, the one-step-ahead controllers do not require knowledge of the dynamic characteristics of the controlled system (e.g. state-space systems or transfer functions). Sometimes, in the gas turbine field, the control system could produce an excessive control effort, due to sudden variations of the electric load. In order to reduce this control action, the weighted one-step-ahead adaptive (WOSAA) control algorithm considers a penalty associated with the control effort using an appropriate cost function. In this way, the control variable does not assume values that are too large, even when the gas turbine undergoes sudden changes in the external load. As a consequence, the robustness and stability features of the WOSAA control system are increased. The results show that the WOSAA control technique, applied to both the double-shaft aero-derivative gas turbine and the single-shaft heavy-duty gas turbine, effectively counteracts the load reduction with limited overshoot in the controlled variables with reduced control effort
Intrinsic PEEP and cardiopulmonary interaction in patients with COPD and acute ventilatory failure. Eur Respir J. 1996 Jun;9(6):1283-92. Review
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Performance of Gas Turbine Power Plants Controlled by One Step Ahead Adaptive Technique
No full textThe One Step Ahead Controllers represent a branch of the Minimum Prediction Error Adaptive Controllers. They combine the parameter estimation of the controlled system model with a particular control scheme; therefore, they are especially suitable for non-linear and time-varying systems. Since the estimated parameters are updated at each time step (by using the sampled data), these methods can be adopted for real-time applications. Consequently, the One Step Ahead Controllers do not require the knowledge of the dynamic characteristics of the controlled system (e.g. state space systems or transfer functions).
The One Step Ahead Adaptive (OSAA) algorithm combines the Least Square Algorithm (LSA) parameter estimator with a Deterministic Auto-Regressive Moving Average (DARMA) control scheme. The DARMA model can be characterized with a different number of time steps in the past (order of the estimated model) in relation to the dynamic feature of the controlled system.
Sometimes, an excessive control effort could arise, caused by sudden variations of the electric load. In order to reduce this control action, the OSAA control technique has been applied also in Weighted fashion. The Weighted One Step Ahead Adaptive (WOSAA) control algorithm considers a penalty associated with the control effort by use an appropriate cost function. In this way, the control variable does not assume too large values, even when the Gas Turbine undergoes sudden changes in the external load. As a consequence, the robustness and the stability features of the WOSAA control system are increased with respect to the OSAA algorithm.
The proposed techniques have been applied to a single shaft heavy-duty gas turbine (WOSAA) and to a double-shaft aero-derivative gas turbine (OSAA). They have been tested in Single-Input Single Output (SISO) mode. In the simulation tests, the plant is assumed to undergo sudden variations of the electric load. Second order schemes of the OSAA estimated model have been derived and applied to the double-shaft aero-derivative gas turbine.
The results show that the OSAA control technique, applied to the double-shaft aero-derivative gas turbine, effectively counteracts the load reduction with limited overshoot in the controlled variables and, introducing an integral correction, with a negligible static error. On the other hand, the WOSAA control algorithm is able to efficiently regulate the single shaft heavy-duty gas turbine, and to counteract the sudden variations of the electric load, with reduced control effort
Right ventricle-afterload matching during mechanical ventilation with positive end expiratory pressure
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