ALBERT

Description: Energies, Vol. 11, Pages 1082: Modelling, Analysis and Performance Evaluation of Power Conversion Unit in G2V/V2G Application—A Review Energies doi: 10.3390/en11051082 Authors: María Garcés Quílez Mohamed Abdel-Monem Mohamed El Baghdadi Yang Yang Joeri Van Mierlo Omar Hegazy In response to climate change, which is caused by the increasing pollution of the environment and leads to the deterioration of human health, future electricity generations should reduce reliance on fossil fuels by growing the use of clean and renewable energy generation sources and by using clean vehicle technologies. Battery storage systems have been recognized as one of the most promising approaches for supporting the renewable energy generation sources and cleanly powering vehicles instead of burning gasoline and diesel fuel. However, the cost of batteries is still a prominent barrier for their use in stationary and traction applications. As a rule, the cost of batteries can be decreased by lowering material costs, enhancing process efficiencies, and increasing production volume. Another more effective solution is called Vehicle-to-grid (V2G) application. In V2G application, the battery system can be used to support the grid services, whereas the battery is still in the vehicle. To make a battery system economically viable for V2G/G2V applications, an effective power-electronics converter should be selected as well. This converter should be supported by an advanced control strategy. Therefore, this article provides a detailed technical assessment and review of V2G/G2V concepts, in conjunction with various power-electronics converter topologies. In this paper, modeling and detailed control strategies are fully designed and investigated in terms of dynamic response and harmonics. Furthermore, an extensive design and analysis of charging systems for low-duty/high-duty vehicles are also presented.

Description: Sustainability, Vol. 10, Pages 2004: Improving Sustainability through Corrosion Resistance of Reinforced Concrete by Using a Manufactured Blended Cement and Fly Ash Sustainability doi: 10.3390/su10062004 Authors: Hector Gerardo Campos Silva Pedro Garces Terradillos Emilio Zornoza Jose Manuel Mendoza-Rangel Pedro Castro-Borges Cesar Antonio Juarez Alvarado The objective of this paper is to report the improvement of sustainability through the increase of reinforced concrete corrosion resistance by using a blended cement and fly ash. Different reinforced concrete mixtures were prepared with partial substitution of a manufactured blended cement with fly ash from a thermal power plant in Andorra (Teruel, Spain). These mixtures were manufactured using three different water/cement ratios (0.46, 0.59, and 0.70) and three substitution percentages of cement by fly ash (0%, 25%, and 50%). The test cylinders underwent an accelerated carbonation process and exposure to different chloride levels, with the aim of characterizing the corrosion level of the different mixtures. The addition of local FA matched or even improved the resistance of the control mixture against carbonation and chlorides.

Description: In this research, strain-sensing and damage-sensing functional properties of cement composites have been studied on a conventional reinforced concrete (RC) beam. Carbon nanofiber (CNFCC) and fiber (CFCC) cement composites were used as sensors on a 4 m long RC beam. Different casting conditions (in situ or attached), service location (under tension or compression) and electrical contacts (embedded or superficial) were compared. Both CNFCC and CFCC were suitable as strain sensors in reversible (elastic) sensing condition testing. CNFCC showed higher sensitivities (gage factor up to 191.8), while CFCC only reached gage factors values of 178.9 (tension) or 49.5 (compression). Furthermore, damage-sensing tests were run, increasing the applied load progressively up to the RC beam failure. In these conditions, CNFCC sensors were also strain sensitive, but no damage sensing mechanism was detected for the strain levels achieved during the tests. Hence, these cement composites could act as strain sensors, even for severe damaged structures near to their collapse.

Description: Energies, Vol. 10, Pages 1316: Maximum Power Point Tracking of Photovoltaic Panels by Using Improved Pattern Search Methods Energies doi: 10.3390/en10091316 Authors: Andrés Tobón Julián Peláez-Restrepo Juan Villegas-Ceballos Sergio Serna-Garcés Jorge Herrera Asier Ibeas This paper deals with the optimization of maximum power point tracking when a photovoltaic panel is modelled as two diodes. The adopted control is implemented using a sliding mode control (SMC) and the optimization is implemented using an improved Pattern Search Method. Thus, the problem of maximum power point tracking is reduced to an optimization problem whose solution is implemented by Pattern Search Techniques, inheriting their convergence properties. Simulation examples show the effectiveness of the proposed technique in practice, being able to deal with different radiations. In addition, improved pattern search method (IPSM) is compared with other techniques such as perturb & observe and Particle Swarm optimization, after which IPSM presents lower energy losses in comparison with the other two algorithms, with the advantage of ensuring the location of the optimal power point in all cases.

Description: Sustainability, Vol. 9, Pages 1327: How is Environmental Proactivity Accomplished? Drivers and Barriers in Firms’ Pro-Environmental Change Process Sustainability doi: 10.3390/su9081327 Authors: Jesús Valero-Gil Pilar Rivera-Torres Conchita Garcés-Ayerbe The contaminating effects of economic activity and the scarcity of natural resources has led firms to a situation in which corporate strategy has been compromised by environmental issues. The objective of this paper is to analyse some of the factors determining the pro-environmental change process by considering the drivers encouraging firms to progress in environmental protection and the barriers that curb this progress. Using a structural equation model implemented on a sample of 303 firms, our results confirm a direct and positive effect of stakeholder pressure and of the expectations of obtaining competitive advantages from the pro-environmental change process. The results also confirmed the indirect effect of stakeholder pressure on pro-environmental change through managers’ expectations of obtaining competitive advantages, which play a mediating role in the firm’s response. Although managers interpret the barriers we have studied as obstacles to adopting environmental protection measures, they do not prevent any firm from reaching advanced levels of pro-environmental change.

Description: Sustainability, Vol. 9, Pages 1821: Corporate Social Responsibility Drivers and Barriers According to Managers’ Perception; Evidence from Spanish Firms Sustainability doi: 10.3390/su9101821 Authors: José Agudo-Valiente Concepción Garcés-Ayerbe Manuel Salvador-Figueras Corporate Social Responsibility (CSR) is becoming a dominant issue in both research and practice of management. However, the underlying processes in the relationship between the degree of development of CSR in companies and the drivers/barriers that determine this development are still at the center of an intense debate. The purpose of this empirical study is to examine these relationships. We investigate a sample of 416 Spanish firms; based on a multifactorial framework, our study considers both the subjective and objective drivers/barriers, analyzing their joint effect on the final degree of sustainability. A structural equation model is established and a Bayesian approach is used, enabling exact inferences about the model’s parameters and handling missing data with random imputation, thus increasing the study’s reliability. The results show that this degree is related to what managers believe CSR to be (subjective drivers/barriers) and what managers expect it to accomplish or outcomes (objective drivers/barriers).

Description: Materials, Vol. 11, Pages 1266: Antimicrobial Porous Surfaces Prepared by Breath Figures Approach Materials doi: 10.3390/ma11081266 Authors: Alexandra Muñoz-Bonilla Rocío Cuervo-Rodríguez Fátima López-Fabal José L. Gómez-Garcés Marta Fernández-García Herein, efficient antimicrobial porous surfaces were prepared by breath figures approach from polymer solutions containing low content of block copolymers with high positive charge density. In brief, those block copolymers, which were used as additives, are composed of a polystyrene segment and a large antimicrobial block bearing flexible side chain with 1,3-thiazolium and 1,2,3-triazolium groups, PS54-b-PTTBM-M44, PS54-b-PTTBM-B44, having different alkyl groups, methyl or butyl, respectively. The antimicrobial block copolymers were blended with commercial polystyrene in very low proportions, from 3 to 9 wt %, and solubilized in THF. From these solutions, ordered porous films functionalized with antimicrobial cationic copolymers were fabricated, and the influence of alkylating agent and the amount of copolymer in the blend was investigated. Narrow pore size distribution was obtained for all the samples with pore diameters between 5 and 11 µm. The size of the pore decreased as the hydrophilicity of the system increased; thus, either as the content of copolymer was augmented in the blend or as the copolymers were quaternized with methyl iodide. The resulting porous polystyrene surfaces functionalized with low content of antimicrobial copolymers exhibited remarkable antibacterial efficiencies against Gram positive bacteria Staphylococcus aureus, and Candida parapsilosis fungi as microbial models.

Description: Materials, Vol. 11, Pages 733: Maintaining High Strength in Mg-LPSO Alloys with Low Yttrium Content Using Severe Plastic Deformation Materials doi: 10.3390/ma11050733 Authors: Gerardo Garces Sandra Cabeza Rafael Barea Pablo Pérez Paloma Adeva Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equal channel angular pressing (ECAP) have been considered for effective methods of maintaining the high mechanical strength of Mg-Y-Zn alloys containing long-period stacking ordered structures with respect to the alloy processed by the conventional extrusion of as-cast ingots with the advantage of minimizing the yttrium content. A yield stress similar to that found for extruded Mg97Y2Zn1 alloy can be attained with only half of the usual yttrium and zinc additions thanks to the grain refinement induced by ECAP processing. The properties of Mg98.5Y1Zn0.5 subjected to ECAP are maintained up to 200 °C, but superplastic behavior is found above this temperature when the alloy is processed through a powder metallurgy route.

Description: Sensors, Vol. 18, Pages 1514: Analysis of Soot Propensity in Combustion Processes Using Optical Sensors and Video Magnification Sensors doi: 10.3390/s18051514 Authors: Hugo O. Garcés Andrés Fuentes Pedro Reszka Gonzalo Carvajal Industrial combustion processes are an important source of particulate matter, causing significant pollution problems that affect human health, and are a major contributor to global warming. The most common method for analyzing the soot emission propensity in flames is the Smoke Point Height (SPH) analysis, which relates the fuel flow rate to a critical flame height at which soot particles begin to leave the reactive zone through the tip of the flame. The SPH and is marked by morphological changes on the flame tip. SPH analysis is normally done through flame observations with the naked eye, leading to high bias. Other techniques are more accurate, but are not practical to implement in industrial settings, such as the Line Of Sight Attenuation (LOSA), which obtains soot volume fractions within the flame from the attenuation of a laser beam. We propose the use of Video Magnification techniques to detect the flame morphological changes and thus determine the SPH minimizing observation bias. We have applied for the first time Eulerian Video Magnification (EVM) and Phase-based Video Magnification (PVM) on an ethylene laminar diffusion flame. The results were compared with LOSA measurements, and indicate that EVM is the most accurate method for SPH determination.

Description: Sensors, Vol. 17, Pages 2926: Choice of Magnetometers and Gradiometers after Signal Space Separation Sensors doi: 10.3390/s17122926 Authors: Pilar Garcés David López-Sanz Fernando Maestú Ernesto Pereda Background: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer. Methods: First, we provide theoretical evidence that both gradiometers and magnetometers result from the backprojection of the same SSS components. Then, we compare resting state and task-related sensor and source estimations from magnetometers and gradiometers in real MEG recordings before and after SSS. Results: SSS introduced a strong increase in the similarity between source time series derived from magnetometers and gradiometers (r2 = 0.3–0.8 before SSS and r2 > 0.80 after SSS). After SSS, resting state power spectrum and functional connectivity, as well as visual evoked responses, derived from both magnetometers and gradiometers were highly similar (Intraclass Correlation Coefficient > 0.8, r2 > 0.8). Conclusions: After SSS, magnetometer and gradiometer data are estimated from a single set of SSS components (usually ≤ 80). Equivalent results can be obtained with both sensor types in typical MEG experiments.