University of Seville

About: University of Seville is a education organization based out in Seville, Andalucía, Spain. It is known for research contribution in the topics: Population & Model predictive control. The organization has 20098 authors who have published 47317 publications receiving 947007 citations. The organization is also known as: Universidad de Sevilla.

A Review of Power Electronics for Grid Connection of Utility-Scale Battery Energy Storage Systems

Abstract: The increasing penetration of renewable energy sources (RES) poses a major challenge to the operation of the electricity grid owing to the intermittent nature of their power output. The ability of utility-scale battery energy storage systems (BESS) to provide grid support and smooth the output of RES in combination with their decrease in cost has fueled research interest in this technology over the last couple of years. Power electronics (PE) is the key enabling technology for connecting utility-scale BESS to the medium-voltage grid. PE ensure energy is delivered while complying with grid codes and dispatch orders. Simultaneously, the PE must regulate the operating point of the batteries, thus for instance preventing overcharge of batteries. This paper presents a comprehensive review of PE topologies for utility BESS that have been proposed either within industry or the academic literature. Moreover, a comparison of the presently most commercially viable topologies is conducted in terms of estimated power conversion efficiency and relative cost.

Importance of the Metal–Oxide Interface in Catalysis: In Situ Studies of the Water–Gas Shift Reaction by Ambient‐Pressure X‐ray Photoelectron Spectroscopy

Abstract: The traditional approach to the optimization of metal/oxide catalysts has focused on the properties of the metal and the selection of the proper oxide for its dispersion. The importance of metal–oxide interfaces has long been recognized, [1] but the molecular determination of their properties and role is only now emerging. [2] Atoms with properties ranging from metallic to ionic are available at the interface and create unique reaction sites. We show herein how sites associated with a metal–ceria interface can dramatically change the reaction mechanism of the water–gas shift reaction (WGSR; CO + H2O!H2 + CO2). The WGSR is critical in the production of hydrogen. Multiple reaction mechanisms have been proposed. [3] In the redox mechanism, CO reacts with oxygen derived from the dissociation of H2O. In the associative process, the formation of a carbonaceous COxHy intermediate must precede the production of H2 and CO2. In situ studies are essential for the detection of surface species and active phases only present under the reaction conditions. [4] We present a combination of near-ambient-pressure X-ray photoelectron spectroscopy (NAP XPS), infrared reflection absorption spectroscopy (IRRAS), and density functional theory (DFT) calculations used to study the WGSR on CeOx nanoparticles deposited on Cu(111) and Au(111). Under WGSR conditions, adsorbed bent carboxylate (CO2 d� ) species were identified over both CeOx/Cu(111) and CeOx/ Au(111), with the ceria in a highly reduced state. By combining in situ experimental results with calculations, we

Lyapunov-Based Model Predictive Control of Nonlinear Systems Subject to Data Losses

Abstract: In this work, we focus on model predictive control of nonlinear systems subject to data losses. The motivation for considering this problem is provided by wireless networked control systems and control of nonlinear systems under asynchronous measurement sampling. In order to regulate the state of the system towards an equilibrium point while minimizing a given performance index, we propose a Lyapunov-based model predictive controller which is designed taking data losses explicitly into account, both in the optimization problem formulation and in the controller implementation. The proposed controller allows for an explicit characterization of the stability region and guarantees that this region is an invariant set for the closed-loop system under data losses, if the maximum time in which the loop is open is shorter than a given constant that depends on the parameters of the system and the Lyapunov-based controller that is used to formulate the optimization problem. The theoretical results are demonstrated through a chemical process example.

Slant submanifolds in sasakian manifolds

Abstract: . In this paper, we show new results on slant submanifolds of analmost contact metric manifold. We study and characterize slant submanifolds of K-contact and Sasakian manifolds. We also study the special class of three-dimen-sional slant submanifolds. We give several examples of slant submanifolds.1991 Mathematics Subject Classification. 53C15, 53C40.0. Introduction. Slant immersions in complex geometry were defined by B.-Y.Chen as a natural generalization of both holomorphic immersions and totally realimmersions [2]. Examples of slant immersions into complex Euclidean spaces C 2 andC 4 were given by Chen and Tazawa [2, 4, 5], while slant immersions of Ka¨hler C-spaces into complex projective spaces were given by Maeda, Ohnita and Udagawa[9].In a recent paper [7], A. Lotta has introduced the notion of slant immersion of aRiemannian manifold into an almost contact metric manifold and he has provedsome properties of such immersions. A. Lotta and A. M. Pastore have obtainedexamples of slant submanifolds in the Sasakian-space-form R