Uplink beamforming for the FDD mode of UTRA

This paper presents some link level simulation results for the evaluation of adaptive antennas in the uplink of the FDD mode of UTRA (UMTS terrestrial radio access). Two families of algorithms were initially considered, the basic difference between them being their ability/disability to suppress the contribution from W-CDMA directional interfering sources. Two distinct schemes were established as representatives for each family and their performance was evaluated in presence of some illustrative interfering scenarios. In the light of the results it is shown that time-reference beamforming algorithms suffer from severe beam pattern distortion effects when applied as such. This in turn causes harsh performance degradation in terms of raw BER, especially at high SINR levels. It is shown that these shortcomings are essentially caused by the uplink multiplexing of the traffic channel, which is seen by the base station as a powerful interfering source coming from the direction of arrival of the desired user.Peer ReviewedPostprint (published version

Optimizing the spatial spread of a quantum walk.

We devise a protocol to build 1D time-dependent quantum walks in 1D maximizing the spatial spread throughout the procedure. We allow only one of the physical parameters of the coin-tossing operator to vary, i.e. the angle θ, such that for θ = 0 we have the ˆσz, while for θ = π/4 we obtain the Hadamard gate. The optimal θ sequences present non-trivial patterns, with mostly θ ≈ 0 alternated with θ ≈ π/4 values after increasingly long periods. We provide an analysis of the entanglement properties, quasi-energy spectrum and survival probability, providing a full physical picture.peer-reviewed1,34 M

Diversity in mobile communications for blind detection of block-coded modulations

Spatial, temporal, and frequency diversity structures are analyzed to address the blind equalization problem in the presence of time-variant frequency selective channels. The aim of the paper is to present equalization schemes useful in front of fast changing channel responses. The best solution is a deterministic blind criterion that allows direct channel equalization and symbol detection. The main contribution of this paper is to present deterministic blind equalization schemes in CDMA systems (frequency diversity) to reduce the impact of the time-variant frequency selective channel.Peer ReviewedPostprint (published version

l-Amino Acid Production by a Immobilized Double-Racemase Hydantoinase Process: Improvement and Comparison with a Free Protein System

Protein immobilization is proving to be an environmentally friendly strategy for manufacturing biochemicals at high yields and low production costs. This work describes the optimization of the so-called “double-racemase hydantoinase process,” a system of four enzymes used to produce optically pure l-amino acids from a racemic mixture of hydantoins. The four proteins were immobilized separately, and, based on their specific activity, the optimal whole relation was determined. The first enzyme, d,l-hydantoinase, preferably hydrolyzes d-hydantoins from d,l-hydantoins to N-carbamoyl-d-amino acids. The remaining l-hydantoins are racemized by the second enzyme, hydantoin racemase, and continue supplying substrate d-hydantoins to the first enzyme. N-carbamoyl-d-amino acid is racemized in turn to N-carbamoyl-l-amino acid by the third enzyme, carbamoyl racemase. Finally, the N-carbamoyl-l-amino acid is transformed to l-amino acid by the fourth enzyme, l-carbamoylase. Therefore, the product of one enzyme is the substrate of another. Perfect coordination of the four activities is necessary to avoid the accumulation of reaction intermediates and to achieve an adequate rate for commercial purposes. The system has shown a broad pH optimum of 7–9, with a maximum activity at 8 and an optimal temperature of 60 °C. Comparison of the immobilized system with the free protein system showed that the reaction velocity increased for the production of norvaline, norleucine, ABA, and homophenylalanine, while it decreased for l-valine and remained unchanged for l-methionine

Investigación de la satisfacción de los turistas extranjeros con el servicio de restauración en la ciudad de Sevilla

El principal objetivo de este estudio es profundizar sobre la satisfacción que tienen los turistas extranjeros que visitan la ciudad de Sevilla con el sector de la restauración. Para poder ver las debilidades y posibles mejoras que se presentan en el mismo a la hora de atender a este segmento de mercado, el cual está en continuo crecimiento. Este estudio, se ha basado en primer lugar, en datos secundarios de webs oficiales, publicaciones gubernamentales y libros, con el fin de obtener datos teóricos y conocimientos sobre este sector y su comportamiento en el mercado analizado. Finalmente se ha desarrollado un estudio empírico. Profundizando en técnicas de observación, Mistery Shopping y cuestionarios a este público, para poder analizar los resultados y valorar los puntos débiles y posibles soluciones propuestas para mejorar este sector.Universidad de Sevilla. Grado en Marketing e Investigación de Mercado

Downlink beamforming in cellular mobile communications

A technique for downlink transmission beamformer design in cellular mobile communications systems using an antenna array at the base station is presented. The method is based on estimation of an underlying spatial distribution associated with each source's spatial downlink channel. The algorithm isPeer ReviewedPostprint (published version

Generalized perfect codes for symmetric classical-quantum channels

We define a new family of codes for symmetric classical-quantum channels and establish their optimality. To this end, we extend the classical notion of generalized perfect and quasi-perfect codes to channels defined over some finite dimensional complex Hilbert output space. The resulting optimality conditions depend on the channel considered and on an auxiliary state defined on the output space of the channel. For certain N-qubit classical-quantum channels, we show that codes based on a generalization of Bell states are quasi-perfect and, therefore, they feature the smallest error probability among all codes of the same blocklength and cardinality.This work was supported in part by the European Research Council (ERC) under Grant 714161; in part by the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, the Spanish Government, under Grant RED2018-102668-T, Grant PID2019-104958RB-C41, and Grant PID2020-116683GB-C21; and in part by the Catalan Government, within the ERDF Program of Catalunya, under Grant 2017 SGR 578 AGAUR and Grant 001-P001644 QuantumCAT.Peer ReviewedPostprint (author's final draft

Experimental behaviour of threaded steel rods glued into high-density hardwood

[Abstract] This paper shows the test results for resin-glued steel rods under axial load. These steel rods are glued into timber using a two component Hilti HIT-RE 500 resin. The timber species used in the tests was Tali. Three different anchorage lengths were combined with two rod diameters and two resin thicknesses. The test failure values have been compared to some available theoretical formulations. The formulation in the Eurocode 5 informative appendix is one of these. The results show a significant difference between the theoretical and the test strength values of these joints. This is mainly due to the fact that the theoretical formulations are based on tests on lower density softwoods. Therefore, the research demands more analytical-experimental work in order to achieve more precise theoretical models