1,720,965 research outputs found
Diesel engine VGT Turbocharger controlled by Multi Agent-based algorithm
No full textThis paper provides an innovative technique for the control of a variable-geometry turbine in a turbocharged compression ignition engine. Such a control algorithm is based on a multi-agent System scheme. It is seldom that 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 multi-agent System. 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. In the present paper, a fuzzy logic system has been employed for the agents' internal structure. In order to test the performance of the proposed control technique, a numerical model of the engine has been used, which employs a thermodynamic (zero-dimensional) approach. The paper will show that the proposed control technique is able to take into account the non-linearity of the controlled syste
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
Performance of Gas Turbine Power Plant controlled by Multi Agent scheme
No full textIn latter years the idea of artificial intelligence has been focused around the concept of a 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. In general an agent always tries to carry out an appropriate task. Seldom agents are considered as stand-alone systems. Their main strength can be found in the interaction with other agents in several different ways in a multiagent system. In the present work, multiagent system approach will be used to manage the control process of a single-shaft heavy-duty gas turbine in Multi Input Multi Output mode. 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
A Modular Code for Real Time Dynamic Simulation of Gas Turbines in Simulink
No full textA high-fidelity real-time simulation code based on a lumped, nonlinear representation of gas turbine components is presented. The code is a general-purpose simulation software environment useful for setting up and testing control equipments. The mathematical model and the numerical procedure are specially developed in order to efficiently solve the set of algebraic and ordinary differential equations that describe the dynamic behavior of gas turbine engines. For high-fidelity purposes, the mathematical model takes into account the actual composition of the working gases and the variation of the specific heats with the temperature, including a stage-by-stage model of the air-cooled expansion. The paper presents the model and the adopted solver procedure. The code, developed in Matlab-Simulink using an object-oriented approach, is flexible and can be easily adapted to any kind of plant configuration. Simulation tests of the transients after load rejection have been carried out for a single-shaft heavy-duty gas turbine and a double-shaft aero-derivative industrial engine. Time plots of the main variables that describe the gas turbine dynamic behavior are shown and the results regarding the computational time per time step are discussed
Prediction of Thermoacoustic Instability in Combustion Chamber Equipped With Passive Dampers
No full textThe thermoacoustic mechanism is considered one of the causes
of combustion instability in modern gas turbine combustion
chambers, according to the basic mechanism proposed by
Rayleigh. On this basis, several authors have proposed the use
of acoustic passive dampers, in order to hinder the onset of
instability or, at least, to reduce the amplitude of the pressure
oscillations.
The passive device will produce two main actions, cooperating
to stabilize the system: dissipating the acoustic energy produced
by thermal fluctuations and modifying the phase between
acoustic pressure and heat release in order to reduce the
production of acoustic energy.
The Helmholtz resonators proposed as damping devices act as
acoustic impedances whose characteristics can be modified, not
only by means of the manipulation of their geometrical features
(volume, length and section of the neck) but also by means of
holes and cooling flow.
The present paper aims at describing how a resonator connected
to the combustion chamber is able not only to damp the
pressure oscillation but also to modify the instability conditions
and, under certain conditions, to convert an unstable condition
in a stable one, in a relatively large operating range.
The study has been carried for a cannular type of combustion
chamber by means of a one-dimensional analytical model and
modelling the Helmholtz resonator by means of the electroacoustic
analogy. Two different flame-acoustic interaction
model have been examined.
As a result of the application of the model the optimal design
characteristics of the resonator and its position within the
chamber are obtained. Moreover, unlike what it was expected, it
appears that the optimal resonance frequency of the resonator
does not exactly meet the frequency of the acoustic mode to be damped
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Environmental sustainability analysis of case studies of agriculture residue exploitation
No full textThe agriculture sector produces significant amounts of organic residues and the choice of the management strategy of these flows affects the environmental sustainability of the sector. The scientific literature is rich with innovative processes for the production of bio-based products (BBP) from agriculture residues, aimed at the implementation of circular economy principles. Based on literature data, the present paper performed a life cycle assessment and assessed the environmental sustainability of five processes for the exploitation of rice and wheat straw, tomato pomace, and orange peel. The analysis identified as significant issues the high energy demand and the use of high impact organic solvent. The comparison of BBP with conventional products showed higher environmental loads for the innovative processes that used organic residues (except for rice straw case). The obtained results do not want to discourage the circular strategy in the agriculture sector, but rather to draw the attention of all stakeholders to the environmental sustainability aspects, focusing on the necessity to decrease the electricity demand and identify ecological agents to use in BBP manufacturing, in agreement with the most recent European policies
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