A methodology for discriminant time series analysis applied to microclimate monitoring of fresco paintings

[EN] The famous Renaissance frescoes in Valencia¿s Cathedral (Spain) have been kept under confined temperature and relative humidity (RH) conditions for about 300 years, until the removal of the baroque vault covering them, carried out in 2006. In the interest of longer-term preservation and in order to maintain these frescoes in good condition, a unique monitoring system was implemented to record both air temperature and RH. Sensors were installed in different points at the vault of the apse, during the restoration process. The present study proposes a statistical methodology for analyzing a subset of RH data recorded in 2008 and 2010, from the sensors. This methodology is based on fitting different functions and models to the time series, in order to classify the sensors. The methodology proposed, computes classification variables and applies a discriminant technique to them. The classification variables correspond to estimates of parameters of the models and features such as mean and maximum, among others. These features are computed using values of the functions such as spectral density, sample autocorrelation (sample ACF), sample partial autocorrelation (sample PACF), and moving range (MR). The classification variables computed were structured as a matrix. Next, Sparse Partial Least Squares Discriminant Analysis (sPLS-DA) was applied in order to discriminate sensors according to their position in the vault. It was found that the classification of sensors derived from Seasonal ARIMA-TGARCH showed the best performance (i.e., lowest classification error rate). Based on these results, the methodology applied here can be useful for characterizing the differences in RH, measured at different positions in a historical building.This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 814624. Furthermore, the project was partially supported by Instituto Colombiano de Credito Educativo y Estudios Tecnicos en el Exterior (ICETEX) by means of Programa credito Pasaporte a la Ciencia ID 3595089, and also by Pontificia Universidad Javeriana Cali (Nit 860013720-1) through the Convenio de Capacitacion para Docentes O. J. 086/17.Ramírez, S.; Zarzo Castelló, M.; Perles, A.; García Diego, FJ. (2021). A methodology for discriminant time series analysis applied to microclimate monitoring of fresco paintings. Sensors. 21(2):1-28. https://doi.org/10.3390/s21020436S12821

Characterization of temperature gradients according to height in a baroque church by means of wireless sensors

[EN] The baroque church of Saint Thomas and Saint Philip Neri (Valencia, Spain), which was built between 1727 and 1736, contains valuable paintings by renowned Spanish artists. Due to the considerable height of the central nave, the church can experience vertical temperature gradients. In order to investigate this issue, temperatures were recorded between August 2017 and February 2018 from a wireless monitoring system composed of 21 sensor nodes, which were located at different heights in the church from 2 to 13 m from the floor level. For characterizing the temperature at high, medium and low altitude heights, a novel methodology is proposed based on sparse Partial Least Squares regression (sPLS), Linear Discriminant Analysis (LDA), and the Holt-Winters method, among others, which were applied to a time series of temperature. This approach is helpful to discriminate temperature profiles according to sensor height. Once the vertical thermal gradients for each month were characterized, it was found that temperature reached the maximum correlation with sensor height in the period between August 10th and September 9th. Furthermore, the most important features from the time series that explain this correlation are the mean temperature and the mean of moving range. In the period mentioned, the vertical thermal gradient was estimated to be about 0.043 ºC/m, which implies a difference of 0.47 ºC on average between sensor nodes at 2 m from the floor with respect to the upper ones located at 13 m from the floor level. The gradient was estimated as the slope from a linear regression model using height and hourly mean temperature as the predictor and response, respectively. This gradient is consistent with similar reported studies. The fact that such gradient was only found in one month suggests that the mechanisms of dust deposition on walls involved in vertical thermal gradients are not important in this case regarding the preventive conservation of artworks. Furthermore, the methodology proposed here was useful to discriminate the time series at high, medium and low altitude levels. This approach can be useful when a set of sensors is installed for microclimate monitoring in churches, cathedrals, and other historical buildings, at different levels and positions.This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 814624.Ramírez, S.; Zarzo Castelló, M.; Perles, A.; García Diego, FJ. (2021). Characterization of temperature gradients according to height in a baroque church by means of wireless sensors. Sensors. 21(20):1-35. https://doi.org/10.3390/s21206921S135212

Behavioural Study of the Force Control Loop Used in a Collaborative Robot for Sanding Materials

[EN] The rise of collaborative robots urges the consideration of them for different industrial tasks such as sanding. In this context, the purpose of this article is to demonstrate the feasibility of using collaborative robots in processing operations, such as orbital sanding. For the demonstration, the tools and working conditions have been adjusted to the capacity of the robot. Materials with different characteristics have been selected, such as aluminium, steel, brass, wood, and plastic. An inner/outer control loop strategy has been used, complementing the robot¿s motion control with an outer force control loop. After carrying out an explanatory design of experiments, it was observed that it is possible to perform the operation in all materials, without destabilising the control, with a mean force error of 0.32%. Compared with industrial robots, collaborative ones can perform the same sanding task with similar results. An important outcome is that unlike what might be thought, an increase in the applied force does not guarantee a better finish. In fact, an increase in the feed rate does not produce significant variation in the finish¿less than 0.02 m; therefore, the process is in a ¿saturation state¿ and it is possible to increase the feed rate to increase productivity.Rodrigo Perez-Ubeda is grateful to the Ph.D. Grant CONICYT PFCHA/Doctorado Becas Chile/2017-72180157 and the University of Antofagasta, Chile.Pérez Ubeda, R.; Gutiérrez, SC.; Zotovic Stanisic, R.; Perles, A. (2020). Behavioural Study of the Force Control Loop Used in a Collaborative Robot for Sanding Materials. Materials. 14(1):1-19. https://doi.org/10.3390/ma14010067S11914

A Methodology for the Multi-Point Characterization of Short-Term Temperature Fluctuations in Complex Microclimates Based on the European Standard EN 15757:2010: Application to the Archaeological Museum of L'Almoina (Valencia, Spain)

[EN] The monitoring and control of thermo-hygrometric indoor conditions is necessary for an adequate preservation of cultural heritage. The European standard EN 15757:2010 specifies a procedure for determining if seasonal patterns of relative humidity (RH) and temperature are adequate for the long-term preservation of hygroscopic materials on display at museums, archives, libraries or heritage buildings. This procedure is based on the characterization of the seasonal patterns and the calculation of certain control limits, so that it is possible to assess whether certain changes in the microclimate can be harmful for the preventive conservation of artworks, which would lead to the implementation of corrective actions. In order to discuss the application of this standard, 27 autonomous data-loggers were located in different points at the Archaeological Museum of l¿Almoina (Valencia). The HVAC system (heating, ventilation and air conditioning) at the museum tries to reach certain homogeneous environment, which becomes a challenge because parts of the ruins are covered by a skylight that produces a greenhouse effect in summer, resulting in severe thermo-hygrometric gradients. Based on the analysis of temperatures recorded during 16 months, the air conditions in this museum are discussed according to the standard EN 15757:2010, and some corrective measures are proposed to improve the conservation conditions. Although this standard is basically intended for data recorded from a single sensor, an alternative approach proposed in this work is to find zones inside the museum with a homogeneous microclimate and to discuss next the average values collected in each area. A methodology is presented to optimize the application of this standard in places with a complex microclimate like this case, when multiple sensors are located at different positions.This research was funded by the European Unions Horizon 2020 research and innovation program under grant agreement No. 814624.Díaz-Arellano, I.; Zarzo Castelló, M.; García Diego, FJ.; Perles, A. (2021). A Methodology for the Multi-Point Characterization of Short-Term Temperature Fluctuations in Complex Microclimates Based on the European Standard EN 15757:2010: Application to the Archaeological Museum of L'Almoina (Valencia, Spain). Sensors. 21(22):1-20. https://doi.org/10.3390/s21227754120212

Multivariate characterization of temperature fluctuations in a historical building using energy-efficient IoT wireless sensors

[EN] Adequate thermic conditions are required for the preventive conservation of artworks, but such optimum conditions cannot always be achieved in historical buildings such as ancient churches. In those cases, it is of interest to assess the potential risk of punctual changes in indoor environments that can be harmful to artworks. These conditions can be assessed by means of a microclimate monitoring system comprised of a set of energy¿efficient wireless sensors connected to the cloud using IoT techniques. This approach was followed at the baroque church of Saint Thomas and Saint Philip Neri in Valencia (Spain). A set of 26 wireless nodes was installed, which recorded values of temperature and relative humidity every hour for a period of 7 months. Small differences of temperature were obtained among sensors, so that an efficient methodology based on principal component analysis (PCA) was applied for the characterization of similarities and dissimilarities between sensors. Daily ranges of temperatures were studied as well as mean trajectories, differences between days of the week, and changes in the correlation structure of daily median values over time. Results provide a framework for an efficient characterization of temperatures in heritage buildings based on a network of wireless sensors. Such a framework is useful to assess the potential risk of temperature fluctuations on the preventive conservation of historical buildings and artworks.Funding This research was funded by the European Unions Horizon 2020 research and innovation program under grant agreement No. 814624.Zarzo Castelló, M.; Perles, A.; Mercado Romero, R.; García Diego, FJ. (2021). Multivariate characterization of temperature fluctuations in a historical building using energy-efficient IoT wireless sensors. Sensors. 21(23):1-32. https://doi.org/10.3390/s21237795S132212

Adaptación de la Escala de Creencias sobre el Bienestar a la población española

The study of happiness and well-being is receiving increased attention in different fields. Recent research into well-being has focused on delving deeper into the individual’s conception about the experience of well-being. McMahan and Estes (2011a) created a scale that assesses lay conceptions of well-being (BWBS) based on four dimensions: the experience of pleasure, avoidance of negative experience, self-development and contribution to others. The goal of this study was to adapt this scale, the Beliefs about Well-Being Scale, to the Spanish population. The sample consisted of 1,024 participants from the general population ranging in age interval from 17 to 87 years old. The confirmatory factorial analysis results in a structure of four dimensions, similar to the original scale, although in the adaptation of the scale the items decrease from 16 to 12. The results of the reliability analysis reveal indexes similar to those of the original scale. These results confirm the validity of Beliefs about Well-Being Scale with general population in a cultural context different from the original study. This will allow cross-cultural studies to analyze the influence of culture in the perception of well-being.El estudio de la felicidad y el bienestar está recibiendo cada vez más atención en diferentes campos. Las investigaciones recientes sobre el bienestar se han centrado en profundizar en la concepción del individuo sobre la experiencia del bienestar. McMahan y Estes (2011a) crearon una escala que evalúa las concepciones legas del bienestar en base a cuatro dimensiones: la experiencia de placer, la evitación de la experiencia negativa, el autodesarrollo y la contribución a los demás. El objetivo de este estudio fue adaptar esta escala, Beliefs about Well-Being Scale (BWBS), a la población española. La muestra estuvo formada por 1.024 participantes de la población general con un intervalo de edad entre 17 y 87 años. El análisis factorial confirmatorio da como resultado una estructura de cuatro dimensiones, similar a la escala original, aunque en la adaptación de la escala los ítems disminuyen de 16 a 12. Los resultados del análisis de fiabilidad revelan índices similares a los de la escala original. Estos resultados confirman la validez de la Escala de Creencias sobre el Bienestar con población general en un contexto cultural diferente al del estudio original. Esto permitirá realizar estudios transculturales para analizar la influencia de la cultura en la percepción del bienesta

Ultra-Low Power Optical Sensor for Xylophagous Insect Detection in Wood

[EN] The early detection of pests is key for the maintenance of high-value masterpieces and historical buildings made of wood. In this work, we the present detailed design of an ultra-low power sensor device that permits the continuous monitoring of the presence of termites and other xylophagous insects. The operating principle of the sensor is based on the variations of reflected light induced by the presence of termites, and specific processing algorithms that deal with the behavior of the electronics and the natural ageing of components. With a typical CR2032 lithium battery, the device lasts more than nine years, and is ideal for incorporation in more complex monitoring systems where maintenance tasks should be minimizedThis work was funded by the Generalitat Valenciana's project AICO/2016/058.Perles Ivars, A.; Mercado Romero, R.; Capella Hernández, JV.; Serrano Martín, JJ. (2016). Ultra-Low Power Optical Sensor for Xylophagous Insect Detection in Wood. Sensors. 16(11). https://doi.org/10.3390/s16111977S1977161

Smart destinations and the evolution of ICTs: a new scenario for destination management?

[EN] The impact of information and communication technologies (ICTs) on tourism and their foreseeable future evolution seem to be shaping a new scenario for destination management. This new context has given rise to the need for new management models. One of these models is the emerging smart tourism destination (STD), although it requires greater conceptual precision in order to become a new paradigm for destination management. This paper proposes a systemic model for STDs which facilitates the interpretation of the role of ICTs in the management of tourism destinations. Accordingly, the Delphi technique has been applied so as to determine the opinion of experts regarding the feasibility of the STD approach, its advantages and limitations and also the size of the impact of ICTs on the management and marketing of tourism destinations. This prospective exercise highlights the intensification of the impact of ICTs over the coming years which will shape a new scenario for management characterised by technology and data management. However, the efficiency of the STD approach will not depend exclusively only on technology but also on an appropriate governance of the destination that systematically incorporates the three levels of the STD, namely the strategic¿relational, instrumental and applied levels.This research has been carried out within the framework of the project "New approaches for tourism destinations planning and management: conceptualization, case studies and problems. Definition of smart tourist destinations models" (CSO2014-59193-R) under the Spanish National R&D&I Plan financed by the Ministry of Economy and Competitiveness.Ivars-Baidal, JA.; Celdrán-Bernabeu, MA.; Mazón, JN.; Perles Ivars, A. (2019). Smart destinations and the evolution of ICTs: a new scenario for destination management?. 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From concept to validation of a wireless environmental sensor for the integral application of preventive conservation methodologies in low-budget museums

[EN] The effective implementation of preventive conservation strategies requires tools to continuously measure the environmental conditions to which the cultural objects are exposed. In this sense, the European Horizon 2020 project CollectionCare aims to provide an affordable preventive conservation service for individual objects focused to small museums with limited budgets. Although the use of data loggers has been a must in the past, new deployments tend to use wired and wireless sensors that provide real-time information and the ability to instantly analyse the data, allowing immediate action to be taken in the event of a threat towards a cultural object. For already constructed buildings, wireless systems have the advantage that, a priori, deployments are simpler, faster and cheaper, but have to deal with complex heritage environments with long distances to be covered and very thick walls to cross. In many cases, commercial systems of this type are not economically viable for small museums with limited budgets. Moreover, conservators who try to approach such solutions are often overwhelmed by unclear technical specifications that do not allow them to determine whether the solution fits their environment or not, giving rise to great frustration. Among others, the CollectionCare includes the design of a specific low-cost wireless sensor, being the aim of this article to present to both technical and non-technical readers, the design choices made regarding the housing, attachment method, power source, wireless transmission technique and selection of the environmental sensors following European standards. Also, the effective implementation of the device in three stages to prove the concep until to get a near-production version is presented. The developed device has been deployed in museums in Belgium, Italy, Greece, Latvia, Denmark and Spain, and the validation results are presented, showing that it is feasible to have a cost-effective proposal that it is easy to install and configure and can operate for 10 years without the need for maintenance or battery replacement except if it is needed to comply with annual recalibration if standards such as ISO 11799:2015 are required.This research was funded by the European Union's Horizon 2020 research and innovation programme under Grant agreement No.814624.Laborda, J.; García-Castillo, AM.; Mercado Romero, R.; Peiró-Vitoria, A.; Perles, A. (2022). From concept to validation of a wireless environmental sensor for the integral application of preventive conservation methodologies in low-budget museums. Heritage Science. 10(1):1-17. https://doi.org/10.1186/s40494-022-00837-911710

Historical Building Monitoring Using an Energy-Efficient Scalable Wireless Sensor Network Architecture

We present a set of novel low power wireless sensor nodes designed for monitoring wooden masterpieces and historical buildings, in order to perform an early detection of pests. Although our previous star-based system configuration has been in operation for more than 13 years, it does not scale well for sensorization of large buildings or when deploying hundreds of nodes. In this paper we demonstrate the feasibility of a cluster-based dynamic-tree hierarchical Wireless Sensor Network (WSN) architecture where realistic assumptions of radio frequency data transmission are applied to cluster construction, and a mix of heterogeneous nodes are used to minimize economic cost of the whole system and maximize power saving of the leaf nodes. Simulation results show that the specialization of a fraction of the nodes by providing better antennas and some energy harvesting techniques can dramatically extend the life of the entire WSN and reduce the cost of the whole system. A demonstration of the proposed architecture with a new routing protocol and applied to termite pest detection has been implemented on a set of new nodes and should last for about 10 years, but it provides better scalability, reliability and deployment properties