Simultaneous environmental and economic process synthesis of Isobutane Alkylation

This multidisciplinary study concerns the optimal design of processes with a view to both maximizing profit and minimizing environmental impacts. This can be achieved by a combination of traditional chemical process design methods, measurements of environmental impacts and advanced mathematical optimization techniques. More to the point, this paper presents a hybrid simulation-multiobjective optimization approach that at once optimizes the production cost and minimizes the associated environmental impacts of isobutane alkylation. This approach has also made it possible to obtain the flowsheet configurations and process variables that are needed to manufacture isooctane in a way that satisfies the above-stated double aim. The problem is formulated as a Generalized Disjunctive Programming problem and solved using state-of-the-art logic-based algorithms. It is shown, starting from existing alternatives for the process, that it is possible to systematically generate a superstructure that includes alternatives not previously considered. The optimal solution, in the form a Pareto curve, includes different structural alternatives from which the most suitable design can be selected. To evaluate the environmental impact, Life Cycle Assessment based on two different indicators is employed: Ecoindicator 99 and Global Warming Potential.Spanish Ministry of Science and Innovation (CTQ2012-37039-C02-02)

Modelización generalizada de resortes espirales a torsión. Aplicación en almacenamiento de energía.

Las necesidades energéticas actuales requieren una transformación de las técnicas eficaces en eficientes tanto en producción, transporte como consumo energético. Estas necesidades han impulsado nuevos desarrollos en el ámbito energético, entre los que se encuentran los sistemas de almacenamiento de energía. El avance en ingeniería de materiales hace pensar en la posibilidad del almacenamiento mediante deformación elástica de resortes espirales a torsión. Para ello es necesario estudiar metodológicamente en profundidad este tipo de resortes, así como las posibles vías de optimizar sus características. Hasta la fecha han sido escasos los desarrollos al respecto. Se realiza un análisis de los resorte espiral a torsión, como el elemento constitutivo básico del sistema de almacenamiento; estudiando los diferentes factores de influencia sobre su curva de comportamiento: longitud del fleje, geometría de la espiral de fabricación, variación de la rigidez a flexión a lo largo de la longitud, características de la sección resistente del fleje, espesor del fleje... La selección correcta de dichos parámetros posibilita modular la relación entre el par y el ángulo girado, permitiendo obtener curvas características tanto de baja como de alta variabilidad del par. Se plantea el procedimiento general de diseño en función de la curva de par requerida y de las restricciones establecidas, para cualquier tipo de resorte espiral a torsión, así como uno específico para los resortes clotoidales. Se establece un procedimiento para el caso de tener como variable de diseño el espesor del fleje, comprobándose la coherencia entre ambos en el límite de validez. El procedimiento se ve complementado con un análisis energético del resorte tanto en reposo como en el proceso de deformación con el par aplicado. Existe un caso de estudio particular, los resortes cuya curva generatriz es una espiral clotoidal (curvatura dependiente de la longitud) con variación del módulo resistente a flexión a lo largo de la longitud de forma inversamente proporcional a la misma. La importancia de este caso radica en la posibilidad de realizar un estudio analítico de su comportamiento, tanto de la curva característica par - ángulo girado, como de la influencia de parámetros de diseño, tensiones en el fleje, condiciones de resistencia o bloqueo de espiras. El planteamiento y estudio, requiere de la validación experimental. Se diseñan dos resortes espirales a torsión, uno de baja variabilidad del par, con variación de la rigidez a flexión a lo largo de la longitud y otro de alta variabilidad del par y rigidez a flexión constante. Ambos resortes son fabricados en fibra de vidrio con matriz epoxy debido a su alta tensión admisible respecto al módulo elástico y su baja densidad (alta capacidad de almacenamiento de energía). Para ambos casos se realiza tanto el diseño de la instalación como del plan de ensayos y sistemas de adquisición de datos. Los ensayos llevados a cabo indican la alta correlación entre el modelo teórico y el experimental, aunque dejan patente la necesidad de tener en cuenta el espesor del fleje en el modelo y la necesidad de procesos de fabricación que proporcionen unas características geométricas y resistivas con baja variabilidad. El análisis general planteado se complementa con la optimización del resorte, tanto en la sección resistente (como es el caso de sólido de igual resistencia) como de las configuraciones de montaje. Se estudia la influencia de la geometría de la sección resistente y de los materiales empleados. Se analizan las posibles configuraciones serie y/o paralelo así como la optimización de periféricos y dimensiones del sistema. Como futuras líneas de investigación se plantean la validación del modelo energético desarrollado y aumento de la densidad de energía del sistema mediante materiales avanzados o el empleo de secciones resistentes multicomponentes optimizada

Economic and environmental assessment of directly converting CO2 into a gasoline fuel

The threat posed by Climate Change demands urgent action on finding clean energy solutions with a view to cutting fossil fuel consumption. However, a sudden stop in the use of fossil fuels is not possible without a profound disruption of the economy. This transition is expected to take several decades, and therefore every type of renewable energy should be considered as part of the solution mix. In this work, we propose including gasoline synthesized from atmospheric CO2 as one possible interim solution while the transition away from liquid fossil fuels intensifies. To that end, we have designed a novel process that produces green gasoline in one stage on an industrial scale. This contrasts with the two or three stages needed in the classical Fischer-Tropsch based processes. Furthermore, we have optimized this process through mass and heat integration, and propose three different options that make the most of the waste streams. Finally, we have studied a total of 144 realistic scenarios that take into account the origin of H2 and CO2 as well as their environmental impacts and costs. According to our findings, such a process will be capable of producing high-quality gasoline to be manufactured competitively in the near future. The significance of our findings is that it is realistic to reduce carbon emissions while also promoting the circular economy.The authors J.A.C and M.J.F.T thank Generalitat Valenciana for the financial support under the project PROMETEO 2020/064

A bi-objective model for the integrated frequency-timetabling problem

The urban transport planning process has four basic activities: network design, timetable construction, vehicle scheduling and crew scheduling. In this work we focus on the urban bus timetable construction problem which has two sub-activities: bus frequency calculation and bus departures setting. Typically, these sub-activities are done sequentially, which has some drawbacks: to overcome these drawback we propose to integrate both these sub-activities. We take into consideration: multiple planning periods, synchronizations events (a synchronization occurs when two buses from different routes arrive to a node within a time window), fixed and variable operations costs and uncertain demand in each period

The role of catch portfolios in characterizing species' economic linkages and fishers' responses to climate change impacts

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGThe collective harvest behavior of fishers, as revealed by their catch portfolios, gives rise to an economic linkage among targeted species. Mapping the economic connectivity among species helps identify species that may play a role in fishers’ adaptive capacity to climate change impacts. In this study, we used survey data and network analysis to map the connectivity among species harvested by small-scale Galician fishers holding the same set of fishing permits. We characterized species by describing their roles in the system of connected species via four network centrality measures: degree, closeness, betweenness, and eigenvector. We used connectivity metrics in a discrete choice framework to evaluate the relation between species roles and fishers' species choices under a hypothetical climate change impact. In particular, we asked the following question: Which species are likely to be added to a catch portfolio in response to a climate-driven negative impact on fishing returns? Galician fishers responded to hypothetical scenarios by adding species not central to the network and species that are likely to be located within clusters in the network and by diversifying their portfolios of permits. Our work suggests that species connectivity due to fishers' behavior deserves serious consideration for practitioners who seek to improve institutional arrangements that promote the resilience of small-scale fisheries

Evaluation of brain functional connectivity from electroencephalographic signals under different emotional states

The identification of the emotional states corresponding to the four quadrants of the valence/arousal space has been widely analyzed in the scientific literature by means of multiple techniques. Nevertheless, most of these methods were based on the assessment of each brain region separately, without considering the possible interactions among different areas. In order to study these interconnections, this study computes for the first time the functional connectivity metric called cross-sample entropy for the analysis of the brain synchronization in four groups of emotions from electroencephalographic signals. Outcomes reported a strong synchronization in the interconnections among central, parietal and occipital areas, while the interactions between left frontal and temporal structures with the rest of brain regions presented the lowest coordination. These differences were statistically significant for the four groups of emotions. All emotions were simultaneously classified with a 95.43% of accuracy, overcoming the results reported in previous studies. Moreover, the differences between high and low levels of valence and arousal, taking into account the state of the counterpart dimension, also provided notable findings about the degree of synchronization in the brain within different emotional conditions and the possible implications of these outcomes from a psychophysiological point of view.- This publication is part of the R&D Projects Nos. PID2020-115220RB-C21, EQC2019-006063P, funded by MCIN/AEI/10.13039/501100011033/, and 2018/11744, funded by "ERDF A way to make Europe". This work was partially supported by Biomedical Research Networking Centre in Mental Health (CIBERSAM) of the Instituto de Salud Carlos III. Beatriz Garcia-Martinez holds FPU16/03740 scholarship from Spanish Ministerio de Educacion y Formacion Profesional

An extensive search algorithm to find feasible healthy menus for humans.

Promoting healthy lifestyles is nowadays a public priority among most public entities. The ability to design an array of nutritious and appealing diets is very valuable. Menu Planning still presents a challenge which complexity derives from the problems’ many dimensions and the idiosyncrasies of human behavior towards eating. Among the difculties encountered by researchers when facing the Menu Planning Problem, being able of fnding a rich feasible region stands out. We consider it as a system of inequalities to which we try to fnd solutions. We have developed and implemented a two-phase algorithm -that mainly stems from the Randomized Search and the Genetic- that is capable of rapidly fnding an pool of solutions to the system with the aim of properly identifying the feasible region of the underlying problem and proceed to its densifcation. It consists of a hybrid algorithm inspired on a GRASP metaheuristic and a later recombination. First, it generates initial seeds, identifying best candidates and guiding the search to create solutions to the system, thus attempting to verify every inequality. Afterwards, the recombination of diferent promising candidates helps in the densifcation of the feasible region with new solutions. This methodology is an adaptation of other previously used in literature, and that we apply to the MPP. For this, we generated a database of a 227 recipes and 272 ingredients. Applying this methodology to the database, we are able to obtain a pool of feasible (healthy and nutritious) complete menus for a given D number of days.Open Access granted by Universidad de Málaga / CBUA. This work has been partially supported by the Spanish *Ministerio de Ciencia, Innovación y Universidades *(MCIU/AEI/FEDER, UE) with grant ref PID2019-104263RBC42; and Junta de Andalucía with grant refs. P18-RT-1566, (contract ref CI-21-228) UMA18-FEDERJA- 065. Funding for open access charge: Universidad de Málaga / CBU

Virtual reality simulation of a quadrotor to monitor dependent people at home

Unmanned aerial vehicles (UAVs) represent an assistance solution for home care of dependent persons. These aircraft can cover the home, accompany the person, and position themselves to take photographs that can be analyzed to determine the person's mood and the assistance needed. In this context, this work principally aims to design a tool to aid in the development and validation of the navigation algorithms of an autonomous vision-based UAV for monitoring dependent people. For that, a distributed architecture has been proposed based on the real-time communication of two modules, one of them in charge of the dynamics of the UAV, the trajectory planning and the control algorithms, and the other devoted to visualizing the simulation in an immersive virtual environment. Thus, a system has been developed that allows the evaluation of the behavior of the assistant UAV from a technological point of view, as well as to carry out studies from the assisted person's viewpoint. An initial validation of a quadrotor model monitoring a virtual character demonstrates the advantages of the proposed system, which is an effective, safe and adaptable tool for the development of vision-based UAVs to help dependents at home.This work was partially supported by Ministerio de Ciencia, Innovación y Universidades, Agencia Estatal de Investigación/European Regional Development Fund under PID2019106084RB-I00 and DPI2016-80894-R grants, and by CIBERSAM of the Instituto de Salud Carlos III

Immediate effects of neurodynamic versus muscle stretching on hamstring flexibility in subjects with short hamstring syndrome

To compare the effectiveness of an isolated neurodynamic sciatic sliding technique (Neurodynamic group) versus static stretching (Stretching group) in comparison to a Control group receiving a placebo intervention