Por qué estudiar un paisaje: ses Salines de Eivissa y Formentera

Aquest article pretén impulsar estudis multidisciplinaris per poder obtenir informacions paleoambientals, tan decisives per explicar la interrelació home-medi en el territori. L’explotació de la sal fou un dels recursos més florents en el desenvolupament comercial durant l’antiguitat. És més que probable que, a través de les rutes marítimes, Eivissa fos un dels centres productors i exportadors de sal més importants de la Mediterrània. La poca documentació sobre aquest tipus d’indústria fa que en aquest estudi s’hagi treballat sobre hipòtesis per poder entendre la dinàmica de la sal

Gestión de activos en estaciones depuradoras de aguas residuales: una aproximación económica

El ciclo del agua, desde la captación hasta el vertido, es un sector que implica una importante inversión en infraestructuras urbanas. En particular, las estaciones depuradoras de aguas residuales (EDARs) juegan un importante papel en la sociedad, evitan que diversos contaminantes lleguen al medio, favorecen la recarga de acuíferos y garantizan caudales mínimos. Con el fin de llevar a cabo la depuración de las aguas residuales son necesarios un conjunto de tratamientos fisicoquímicos, el grado de tratamiento requerido para el agua residual depende fundamentalmente de los límites de vertido para el efluente. La mayor parte de las instalaciones disponen de un tratamiento de tipo convencional, el cual consta de un pretratamiento, un tratamiento primario y un secundario. A su vez, los distintos procesos mencionados implican el uso de una gran variedad de activos y se pueden agrupar en construcción civil, tuberías y equipamiento electromecánico. En estas últimas décadas el número de EDARs ha aumentado de forma considerable, debido principalmente a las distintas normativas que han ido, paulatinamente, incrementando las exigencias en cuanto a seguridad ambiental. En concreto la Directiva 91/271/CEE supuso la construcción de un gran número de estaciones depuradoras debido a la obligación de que todas las aglomeraciones urbanas con más de 2.000 habitantes equivalentes dispusieran de colectores y plantas de tratamiento. Actualmente la gran mayoría de EDARs supera o está próxima a superar su vida útil y su condición estructural decrece a lo largo del tiempo. El deterioro de la infraestructura implica obtener menores rendimientos y asumir mayor número de fallos, debido principalmente a la fatiga de los materiales. Además, el deterioro que sufren no solo pone en jaque la sostenibilidad presente y futura de las plantas de tratamiento de aguas residuales, también incrementa el riesgo de accidente y la probabilidad de sufrir un impacto ambiental derivado. Los operadores públicos y privados, con tal de hacer frente al deterioro y sus consecuencias económicas y ambientales, han mostrado un gran interés en desarrollar programas orientados a los mantenimientos y reparaciones en estas instalaciones. Conocer el impacto económico asociado al envejecimiento permite planificar los reemplazos, así como optimizar los costes de mantenimiento asociados. Por este motivo, en el artículo; “Cost analysis of the facilities deterioration in Wastewater Treatment Plants: A dynamic approach” se desarrolla una función económica que explica los costes de mantenimiento y reparaciones en las EDARs teniendo en cuenta, además de la edad de la planta, sus características técnicas. Entender las consecuencias económicas del deterioro permite abordar la gestión de activos desde una óptica económica, ayudando a los tomadores de decisiones a disminuir la incertidumbre con respecto a la renovación de estas infraestructuras. Una vez modelizado el impacto del deterioro sobre los costes de mantenimiento en las infraestructuras de depuración de aguas residuales, se evalúa la influencia de estos costes en la eficiencia de las EDARs desde un punto de vista económico y ambiental. En el siguiente artículo; “Efficiency of wastewater treatment facilities: The influence of scale economies” se estudia, en primer lugar, los efectos de las economías de escala en el sector y, en segundo, el comportamiento de los costes desagregados que constituyen el proceso de depuración ante su posible influencia. Los resultados constatan que un mayor tamaño de las EDARs (según habitantes equivalentes tratados) supone una reducción global de los costes. Para ello, se identifican las distintas dimensiones que generan estos cambios de eficiencia en las plantas. Además, se señalan aquellos costes con mayor capacidad de mejora, siendo los relativos a la energía usada en el proceso y los mantenimientos realizados. Estos últimos muestran cierta heterogeneidad ya que se observa que las EDARs que tratan menos de 8.000 habitantes equivalentes anuales presentan niveles de eficiencia dispares. Este hecho pone de manifiesto que las políticas orientadas a los mantenimientos preventivos pueden incidir en un menor número de reparaciones y, en consecuencia, ayudaría a reducir los costes generales dedicados a las averías en planta. Finalmente, en el último artículo; “Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants” se analiza la relación entre los mantenimientos preventivos y las reparaciones en las instalaciones de tratamiento de aguas residuales. Este planteamiento resulta novedoso y de gran relevancia por dos motivos, en primer lugar, el cálculo de eficiencia en las instalaciones tendrá en cuenta la minimización de factores que puedan perjudicar al proceso, es decir las roturas y reparaciones que tienen lugar en estas infraestructuras. En este sentido, un mayor coste económico debido a las reparaciones penalizará la eficiencia global de la EDAR analizada. En segundo lugar, obtener un índice de eficiencia asociado a cada entrada y la salida no deseada permite analizar, a posteriori, las implicaciones de las distintas políticas de mantenimiento preventivo llevadas a cabo en las EDARs analizadas. Las conclusiones permiten establecer los niveles de costes dedicados a los mantenimientos preventivos que minimizan las averías y, además, sugieren unos costes óptimos a partir de las EDARs que mayores eficiencias ofrecen al respecto.The urban water cycle, from water collection to discharge, is a process that requires significant investment in urban infrastructure. In particular, wastewater treatment plants (WWTPs) play an important role in society, minimizing the environmental impact of wastewater, favouring the recharge of aquifers, and guaranteeing minimum flow rates. To carry out the purification of the wastewater, a set of physicochemical treatments are necessary, whose pollutants removal will depend fundamentally on the discharge limits of the receiving environment. Most of the facilities have a conventional treatment, which consists of a pretreatment, a primary and a secondary treatment. In turn, the different processes mentioned involve the use of a great variety of assets and can be grouped into civil construction, pipes and electromechanical equipment. In recent decades, the number of WWTPs has increased considerably, mainly due to different regulations that have gradually increased the demands in terms of environmental safety. Specifically, Directive 91/271 / EEC involved the construction of a large number of WWTPs due to the obligation for all urban agglomerations with more than 2,000 equivalent inhabitants to have collectors and treatment plants. Currently, the vast majority of WWTPs exceed or are close to exceeding their useful life and their structural condition decreases over time. The deterioration of the infrastructure implies obtaining lower yields and assuming a greater number of failures, mainly due to the fatigue of the materials. Furthermore, the deterioration they suffer not only jeopardizes the present and future sustainability of the wastewater treatment plants, but also increases the risk of accident and the probability of suffering a derived environmental impact. In order to face deterioration and its economic and environmental consequences, public and private operators have shown great interest in developing programs aimed at the maintenance and repairs of these facilities. Being aware of the economic impact associated with aging makes it possible to plan replacements, as well as to optimize the associated maintenance costs. For this reason, in the article “Cost analysis of the facilities deterioration in Wastewater Treatment Plants: A dynamic approach” an economic function that explains the maintenance and repair costs in WWTPs is developed taking into account the age of the facility and its technical characteristics. Understanding the economic consequences of deterioration makes it possible to approach asset management from an economic perspective, helping decision makers to reduce uncertainty regarding the renovation of these infrastructures. Once the impact of the deterioration on the maintenance costs of the wastewater treatment infrastructures has been modeled, the influence of these costs on the efficiency of the WWTPs is evaluated from an economic and environmental point of view. In the article “Efficiency of wastewater treatment facilities: The influence of scale economies” firstly, the effects of economies of scale in the sector and, secondly, the behavior of the disaggregated costs that constitute the purification process before its possible influence are studied. The results confirm that a larger WWTPs (according to equivalent inhabitants treated) implies a reduction of their costs. For this, the different dimensions that generate these efficiency variations among the facilities are identified. In addition, those costs that could be reduced have been identified, being those related to the energy used in the process and the maintenance. The latter show certain heterogeneity since it is observed that the WWTPs that treat less than 8,000 equivalent inhabitants per year present different levels of efficiency. This fact shows that policies aimed at preventive maintenance can have a lower number of repairs and, consequently, would help to reduce the costs for plant breakdowns. Finally, the last article, "Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants", analyzes the relationship between preventive maintenance and repairs in wastewater treatment facilities. This approach is novel and highly relevant for two reasons. Firstly, the efficiency calculation in the facilities will consider the minimization of factors that may harm the process, that is, the breakages and repairs that take place in these infrastructures. In this sense, a higher economic cost due to repairs will penalize the overall efficiency of the WWTP analyzed. Secondly, obtaining an efficiency index associated with each unwanted input and output makes it possible to analyze, afterwards, the implications of different preventive maintenance policies carried out in the WWTPs analyzed. The conclusions make it possible to establish the levels of costs dedicated to preventive maintenance that minimize breakdowns and, furthermore, suggest the optimal costs that WWTPs should incur taking into account the information of those WWTPs that offer greater efficiencies in this regard

Concrete-filled round-ended steel tubular stub columns under concentric and eccentric loads

[EN] In the past, many works to study the mechanical behaviour of concrete filled steel tubular (CFST) stub columns have been conducted. Some of the applications of these composite columns oblige to meet higher requirements of ductility and load-bearing capacity. Traditionally, circular and rectangular tubes have been employed but recently new cross-sectional shapes of these composite columns are being designed and investigated with the aim of optimizing their mechanical behaviour. In this line, concrete-filled round-ended steel tubular columns (CFRT) have appeared as an alternative. However, the number of experimental programs to characterize their mechanical response is still scarce. In order to contribute to the test results database, in this paper an experimental study of 9 concrete-filled round-ended steel tubular stub columns is presented. All the specimens were designed with the same cross-sectional round-ended shape and have the same dimensions. In this program, both normal and high-strength concrete were employed as infill. During the tests, the columns were subjected to axial compression loads but under different eccentricities. The influence of eccentricity and concrete strength on the ultimate load bearing capacity of the concrete-filled round-ended steel tubular are discussed. Besides, the combined action of both components in this type of concrete-filled tubes as well as the effect of the concrete infill are studied.The authors would like to express their sincere gratitude to Universitat Jaume I and the project P1-1A2015-06 entitled “Análisis experimental de pilares mixtos src. Nuevos modelos de cálculo empleando técnicas de inteligencia artificial” and the BEST/2017/147 granted by Conselleria d’Educació, Investigació, Cultura i Esport, GVA.Piquer Vicent, A.; Hernández-Figueirido, D.; Ibáñez Usach, C. (2018). Concrete-filled round-ended steel tubular stub columns under concentric and eccentric loads. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 275-279. https://doi.org/10.4995/ASCCS2018.2018.7197OCS27527

Influence of steel tube thickness and concrete strength on the axial capacity of stub CFST columns

[EN] In order to study the mechanical response of concrete-filled steel tubular (CFST) columns, several experimental and theoretical studies have been conducted in the last years. However, the influence of thin-walled steel tubes on the axial capacity of these composite columns is not completely stablished, especially when it is combined with high-strength concrete as infill. In this paper, the results of an experimental campaign on 9 concrete-filled steel tubular stub columns subjected to concentric load are presented. Different cross-section shapes are considered in this campaign, i.e. circular, square and rectangular. The influence of the steel tube wall thickness is analysed by including in the tests specimens with thin-walled tubes, whose behaviour needs to be studied in depth given the issues arising when working under compression. The experimental program is designed so the analysis of the results permits to drawn consistent conclusions. For each series, the steel tube thickness is the only geometric parameter modified in order to properly study its effect. Besides, two different concrete strengths were considered for the concrete infill, i.e. normal and high- strength concrete, to observe their effect on the ultimate capacity of the columns. During the tests, the specimens are subjected to axial load and the evolution of the axial displacement with the load is registered. The ultimate capacity of each specimen is obtained and an analysis of the steel tube thickness and concrete strength influence is accomplished. Finally, the study of the dependency of the failure mode on these parameters is carried out.The authors would like to express their gratitude to Universitat Jaume I for the project P1-1A2015-06.Ibáñez Usach, C.; Hernández-Figueirido, D.; Piquer Vicent, A. (2018). Influence of steel tube thickness and concrete strength on the axial capacity of stub CFST columns. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 253-257. https://doi.org/10.4995/ASCCS2018.2018.7196OCS25325

Plan de Acción Tutorial en la Facultad de Educación: percepciones del alumnado sobre sus tutores

El acceso a la universidad es un momento en el que el alumnado de primer curso de grado precisa cierta orientación para resolver sus dudas y conocer todos los servicios que tiene a su disposición en la universidad. La Facultad de Educación de la Universidad de Alicante ofrece el Plan de Acción Tutorial (PAT), iniciativa desarrollada por diversos tutores que aumenta anualmente el interés entre el alumnado. El objetivo de esta investigación fue conocer las percepciones que presenta parte del alumnado que asiste al PAT en cuanto a la función que ejercen sus tutores. La muestra estuvo compuesta por 26 alumnos del grado de Maestro de Educación Primaria e Infantil quienes cumplimentaron un cuestionario de elaboración propia acerca de sus percepciones respecto a la labor de sus tutores universitarios. Los resultados obtenidos señalan que entre las funciones más valoradas por los alumnos se encuentran: la obtención de información acerca de las salidas profesionales, el funcionamiento del Prácticum y los itinerarios educativos y cursos. No obstante, se precisa considerar la intervención de los tutores en el área emocional del alumnado (autoestima, confianza personal, emociones negativas y relaciones sociales entre compañeros) ya que es una de las funciones menos valoradas

Intelligent Municipal Heritage Management Service in a Smart City: Telecommunication Traffic Characterizationand Quality of Service

[EN] The monitoring of cultural heritage is becoming common in cities to provide heritage preservation and prevent vandalism. Using sensors and video cameras for this task implies the need to transmit information. In this paper, the teletraffic that cameras and sensors generate is characterized and the transmissions¿ influence on the municipal communications network is evaluated. Then, we propose models for telecommunication traffic sources in an intelligent municipal heritage management service inside a smart sustainable city. The sources were simulated in a smart city scenario to find the proper quality of service (QoS) parameters for the communication network, using Valencia City as background. Specific sensors for intelligent municipal heritage management were selected and four telecommunication traffic sources were modelled according to real-life requirements and sensors datasheet. Different simulations were performed to find the proper CIR (Committed Information Rate) and PIR (Peak Information Rate) values and to study the effects of limited bandwidth networks. Packet loss, throughput, delay, and jitter were used to evaluate the network¿s performance. Consequently, the result was the selection of the minimum values for PIR and CIR that ensured QoS and thus optimized the traffic telecommunication costs associated with an intelligent municipal heritage management service.This work was partially supported by Spanish Government Projects TIN2013-47272-C2-1-R and TEC2015-71932-REDTRodríguez-Hernández, MA.; Jiang, Z.; Gomez-Sacristan, Á.; Pla, V. (2019). Intelligent Municipal Heritage Management Service in a Smart City: Telecommunication Traffic Characterizationand Quality of Service. Wireless Communications and Mobile Computing (Online). 1-10. https://doi.org/10.1155/2019/8412542S11

Asynchronous sensor fusion of GPS, IMU and CAN-based odometry for heavy-duty vehicles

In heavy-duty vehicles, multiple signals are available to estimate the vehicle's kinematics, such as Inertial Measurement Unit (IMU), Global Positioning System (GPS) and linear and angular speed readings from wheel tachometers on the internal Controller Area Network (CAN). These signals have different noise variance, bandwidth and sampling rate (being the latter, possibly, irregular). In this paper we present a non-linear sensor fusion algorithm allowing asynchronous sampling and non-causal smoothing. It is applied to achieve accuracy improvements when incorporating odometry measurements from CAN bus to standard GPS+IMU kinematic estimation, as well as the robustness against missing data. Our results show that this asynchronous multi-sensor (GPS+IMU+CAN-based odometry) fusion is advantageous in low-speed manoeuvres, improving accuracy and robustness to missing data, thanks to non-causal filtering. The proposed algorithm is based on Extended Kalman Filter and Smoother, with exponential discretization of continuous-time stochastic differential equations, in order to process measurements at arbitrary time instants; it can provide data to subsequent processing steps at arbitrary time instants, not necessarily coincident with the original measurement ones. Given the extra information available in the smoothing case, its estimation performance is less sensitive to the noise-variance parameter setting, compared to causal filtering. Working Matlab code is provided at the end of this work

"In vino veritas": factores competitivos en distritos industriales productores de vino

El sector vitivinícola ocupa una destacada posición en el conjunto de la industria agroalimentaria española. La importancia demostrada por esta actividad se traslada también al mercado internacional donde España ostenta una posición de liderazgo tanto en términos de producción, como de ventas al exterior. Buena parte de las empresas elaboradoras de vino de nuestro país se ubican en distritos industriales, o lo que es lo mismo, en entornos geográficos caracterizados por la elevada concentración de pequeñas y medianas empresas cuya organización productiva responde a un esquema basado en la especialización flexible. En anteriores trabajos, se ha podido constatar cómo las empresas elaboradoras de vino ubicadas en este tipo de enclaves industriales presentan una mayor eficiencia respecto de competidores localizados en otro tipo de entornos. El objetivo de este artículo es profundizar en la investigación de los rasgos específicos de los distritos industriales que podrían explicar este plus de eficiencia de sus empresas. Para la identificación y cuantificación de estos factores determinantes de la eficiencia productiva se utiliza una metodología basada en modelos de ajuste paramétrico. Se lleva a cabo una aplicación empírica sobre una muestra de empresas españolas productoras de vino para los años 2000 y 2010, extraída de la base de datos SABI.The wine sector holds a prominent place within the whole Spanish food and agriculture industry. The importance given to this activity has also been transferred to the international market where Spain holds a position of leadership, both in terms of production as in overseas sales. A large number of the wine-producing firms in our country are located in industrial districts, which is to say in geographical areas characterised by a high concentration of small and medium-sized companies whose productive organisation corresponds to a model based on flexible specialisation. In previous papers, it has been possible to verify how wine-producing industries located in industrial areas show greater efficiency in relation to rivals located in other types of environments. The aim of this article is to further research on the specific features of industrial districts which could explain their firms’ increase in efficiency. For the identification and quantification of these determining factors affecting productive efficiency, a methodology based on parametric adjustments models is to be used. An empirical application is to be carried out on a sample of Spanish wine producers for the years 2000 and 2010, extracted from the SABI database

Drive Force and Longitudinal Dynamics Estimation in Heavy-Duty Vehicles

Modelling the dynamic behaviour of heavy vehicles, such as buses or trucks, can be very useful for driving simulation and training, autonomous driving, crash analysis, etc. However, dynamic modelling of a vehicle is a difficult task because there are many subsystems and signals that affect its behaviour. In addition, it might be hard to combine data because available signals come at different rates, or even some samples might be missed due to disturbances or communication issues. In this paper, we propose a non-invasive data acquisition hardware/software setup to carry out several experiments with an urban bus, in order to collect data from one of the internal communication networks and other embedded systems. Subsequently, non-conventional sampling data fusion using a Kalman filter has been implemented to fuse data gathered from different sources, connected through a wireless network (the vehicle's internal CAN bus messages, IMU, GPS, and other sensors placed in pedals). Our results show that the proposed combination of experimental data gathering and multi-rate filtering algorithm allows useful signal estimation for vehicle identification and modelling, even when data samples are missing