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This paper presents a control law based on Hybrid Dynamical Systems (HDS) theory for electronic inverters. This kind of systems are very suited for the use of such theory since they combine both kind of signals: continuous (voltages and currents) and discrete (on-off state of switches). Unlike previous applications of HDS to power converters, the studied problem can be considered as a tracking problem since the objective is to generate a desired ac voltage from a dc source. The effectiveness of the resultant control law is validated by means of simulations and experiments.

Left-sided portal hypertension occurs due to obstruction, stenosis, or thrombosis of the splenic vein. The most common causes are pancreatic, including chronic pancreatitis (31.8%-53.8%), pancreatic pseudocyst, and neoplasms.

To compare various prognostic scales to verify which one has the best performance in predicting 28-day mortality in patients with severe toxic-alcoholic hepatitis (AH).

Dynamic voltage scaling (DVS) is an important method in managing dynamically the system supply voltage for efficient power reduction. This approach is applied in very large scale integration (VLSI). A dc-dc converter is an electronic device which allows to vary the voltage and, thus, to implement DVS technique. In this paper, a high-performance controller is presented for a novel discrete DVS converter. This controller is developed with the aim to deal with the unknown resistive component of the load as well as to minimize the dissipated energy and current peaks, what is very important in the field of microelectronics. Current peaks and power consumption are minimized by computing an optimal evolution for the voltage reference. Likewise, an adaptive controller is proposed to deal with the unknown load resistive parameter. Consequently, the obtained advanced controller can acquires a high consideration on electronic devices. [ABSTRACT FROM PUBLISHER]

This paper presents an advanced model and control structure of a non-linear hybrid system: a gasoline direct injection (GDI) engine. The engine management system proposed in the paper is based on a hierarchical structure that uses Takagi—Sugeno fuzzy models of the engine to define piecewise linear controllers. Thanks to the hierarchical controller structure, engine idle speed regulation is tackled as a high-level requirement and therefore no specific low-level controller is needed. Moreover, the two combustion modes are correctly handled to optimize the engine efficiency. A global stability analysis of the GDI engine working either in homogeneous mode or in stratified mode is also presented, based on bifurcation analysis. Bifurcation analysis can be applied to a wide range of different controllers (even close-to-production), and therefore it can be of significant practical value.

The mining district of Zaruma-Portovelo of southern Ecuador is a deposit of polymetallic sulfides worked since 1908. Currently the small traditional mining operation processes 1800 tons of ore a day, generating environmental waste that is accumulated and systematically discharged into the Calera and Amarillo Rivers. In this watershed area of Puyango-Tumbes, where samples were taken and subjected to gravimetric concentration, a mineralogical analysis of the concentrate was made. Samples of sediments taken from areas of weathered mining shafts were used to isolate native microorganisms for subsequent molecular and physiological characterization. The mineral concentrate contains 66.63 % of pyrite, 175 ppm Ag and 6.9 ppm Au (with 80 % of refractory gold). This mineral was subjected to biooxidation by the isolated native organisms. In experiments with pulp density of 10%, the solubility of the sulfides was very significant, reaching concentrations of Fe3 + 30 g/L and sulfate 60 g/L.

In this paper, a new control law for the pendulum on a cart is proposed. The novelty of the new control law is in the combination of methods that is used to obtain it. First, a control law for transforming the pendulum subsystem in a Hamiltonian system is obtained. The resulting Hamiltonian function has a maximum at the desired position. The objective of the second step is to inject energy (so the pendulum subsystem tends to the maximum of the Hamiltonian) at the same time that the cart is stopped. It is shown that both objectives can be solved using forwarding, which in this case yields solvable partial differential equations.

In this paper the swing-up problem for the Furuta pendulum is analyzed by comparing the results obtained by the conventional Astrom-Furuta strategy, based on a dimension 2 model, with a new strategy based on a dimension 3 control law using the symmetry of the configuration space of the system. The controller design is based on Fradkov's speed-gradient (SG) method (Andrievskii et al.,1996). A comparative analysis whereby the advantages and effectiveness of the new law for swinging the pendulum up are shown is included.

In this paper, a supervisory controller for MIMO fuzzy control systems is presented. It is proven that this controller is able to guarantee global stability in the Lyapunov sense in spite of uncertainties in the plant. After the theoretical considerations, the usefulness of the supervisor is illustrated with the application to the control problem of a waste-water treatment plant.

This paper deals with the analysis of the path tracking system of autonomous vehicles taking into account the nonlinear effects and the pure delay which are present in the control loop. This loop uses a fuzzy controller. A method based on frequency response to analyze the stability of the closed loop system is presented. The method considers explicitly the global state-space stability of the system in situations where multiple steady regimes are involved. The paper describes the implementation of the path tracking system in the ROMEO vehicles developed at the University of Seville. Field experiments show the validity of tiic proposed method.

This paper presents the application of a multivariable frequency response technique to study the stability of autonomous vehicles when tracking a path. Particularly, the stability of a path tracking control loop with a fuzzy controller is considered. The technique is based on the analysis of the solutions of the harmonic balance equation. Necessary and sufficient conditions for stability areobtained by examining a family of characteristic loci parameterized in the amplitude. The method can be applied when pure delays exist in the path tracking control loop. Several simulations experiments have been done. These experiments show a Hopf bifurcation induced by a pure delay, and an unstable limit cycle around a stable origin.

This paper describes a LQG/LTR controller for a solar distributed collector field. When designing a LQG controller it is easy to take into account the trade-off between quick response and avoiding oscillations which is typical of many control problems. The improved robustness reached with the loop transfer recovery LTR allows for good behaviour of the resulting system even when the working conditions are far from the ones the LQG controller has been designed for. The controller also employs serial compensation to cope with measurable external disturbances. The real resulting behaviour is shown by means of experimentation on the plant.