Our world and our lives are changing in many ways. Communication, networking, and computing technologies are among the most influential enablers that shape our lives today. Digital data and connected worlds of physical objects, people, and devices are rapidly changing the way we work, travel, socialize, and interact with our surroundings, and they have a profound impact on different domains, such as healthcare, environmental monitoring, urban systems, and control and management applications, among several other areas. Cities currently face an increasing demand for providing services that can have an impact on people's everyday lives. The CityPulse framework supports smart city service creation by means of a distributed system for semantic discovery, data analytics, and interpretation of large-scale (near-)real-time Internet of Things data and social media data streams. To goal is to break away from silo applications and enable cross-domain data integration. The CityPulse framework integrates multimodal, mixed quality, uncertain and incomplete data to create reliable, dependable information and continuously adapts data processing techniques to meet the quality of information requirements from end users. Different than existing solutions that mainly offer unified views of the data, the CityPulse framework is also equipped with powerful data analytics modules that perform intelligent data aggregation, event detection, quality assessment, contextual filtering, and decision support. This paper presents the framework, describes its components, and demonstrates how they interact to support easy development of custom-made applications for citizens. The benefits and the effectiveness of the framework are demonstrated in a use-case scenario implementation presented in this paper

The use of pumps working as turbines (PATs) connected to the electric system, in the replacement of pressure reduction valves to reduce the excessive pressure in water distribution networks, have been studied for the last years. The introduction of PATs is very important in the water-energy nexus to promote the increase of the energy savings. As consequence, the majority of the water systems does not have access to the electrical grid and, therefore, the need to study the PATs operation off-grid is necessary. In this line, the novelty of this research is the application and optimization of a PAT in water systems when the recovery solution is off-grid type. To operate correctly, the induction machine requires an external source of reactive power, which is typically provided by the electrical grid. To supply the required reactive power, a bank of capacitors is installed at the machine terminals, so-called self-excited induction generator (SEIG). The analytical model, simulation and experimental works were performed, to analyse the SEIG behaviour. The results were applied in a SEIG-PAT system obtaining the global efficiency of the system for different speeds and loads. The global efficiency decreases 47% when off-grid operation, showing the need to optimize the electrical parameters of the generator to operate as off-grid with acceptable efficiency levels. In this framework, a tuning methodology for the SEIG capacitor bank values was developed to be automatically adjusted according to the operating point of the PAT to maximize its efficiency.

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This work focuses on the performance study of the PowerCollector™, a concentrated photovoltaic thermal system with a custom-made geometry and a photovoltaic cell cooling technology. To do so, a model that portrays the behavior of this concentrating solar system was developed. In order to validate all the information obtained with its simulation, measurements were taken from an experimental setup and were compared to the respective results predicted by this exact same model. It should be noted that all these procedures were based on the fluid for which the PowerCollector™ has been designed (water). Hence, the efficiency enhancement using nanofluids was also considered, as data from some studies addressing this issue were analyzed. Alongside all of this, the corrosion and erosion effects on the pipes incorporated in this system and originated by all the fluids mentioned throughout this investigation were also evaluated. In summary, with this entire study, it could be concluded that nanofluids may represent an appropriate alternative to water, as long as they are chosen according to all particularities of each case.

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Reuse of tire crumb in sport facilities is currently a very cost-effective waste management measure. Considering that incorporation of the waste materials in artificial turf would be facilitated if the rubber materials were already colored green, coatings were specifically developed for this purpose. This paper presents an experimental toxicological and environmental assessment aimed at comparing the obtained emissions to the environment in terms of polycyclic aromatic hydrocarbons (PAHs), heavy metals, and ecotoxicity for coated and noncoated rubber granulates. This study is a comprehensive evaluation of the major potential critical factors related with the release of all of these classes of pollutants because previous studies were not systematically performed. It was concluded that between the two types of coatings tested, one is particularly effective in reducing emissions to the environment, simultaneously meeting the requirements of adherence and color stability.

Original scientific paper https://doi.org/10.2298/TSCI171231273TThe aim of this work is the redesign of the reflector geometry in hybrid concentrating collectors that are currently manufactured by SOLARUS Sunpower AB ** to improve the energy efficiency of their solar collectors. The analysis is first accomplished using a numerical model that uses geometrical optics to study the interaction between the sunlight and a concentrating collector along the year. More complex physical models based on open-source and advanced objectoriented Monte Carlo ray tracing programs (SolTrace, Tonatiuh) have been used to study the relation between the collector annual performance and its geometry. On an annual performance basis, a comparative analysis between several solar collector geometries was effectuated to search for higher efficiencies but with controlled costs. Results show that efficiency is deeply influenced by reflector geometry details, collector tilt and location (latitude, longitude) of the solar panel installation and, mostly, by costumer demands. Undoubtedly, the methodology presented in this paper for the design of the solar collector represents an important tool to optimize the binomial cost/effectiveness photovoltaic performance in the energy conversion process. The results also indicate that some modified concentrating solar collectors are promising when evaluating the yearly averaged energy produced per unit area, leading to evident improvements in the performance when compared to the current standard solar concentrating SOLARUS systems. Increases of about 50% (from 0.123 kW/m 2 to 0.1832 kW/m 2 ) were obtained for the yearly average collected power per reflector area when decreasing the collector height in 3.5% (from 143 mm to 138 mm). ability of future generations to meet their own needs * [1]. Apart from the social aspects, the two other pillars of sustainability currently referred to are environmental and economic features. The former has enhanced the RES, the economic aspects deal with the energy efficiency. Among the most used alternatives within renewable energies, solar energy plays a fundamental role.In the last few years, the costs of photovoltaic (PV) modules have dropped rapidly benefitting from technical improvements. Taking into account that the solar cells prices are still responsible for a great percentage of the overall costs related to conversion energy system, different techniques have been implemented to increase the solar energy production without the use of more solar cells. Example of this is the inclusion of reflector concentrators in the concentrating PV-thermal (C-PVT) collector to increase the solar irradiance in the solar cells [2,3]. This may have a higher importance in world regions where the average irradiation is low. However, concentrators present some drawbacks, namely a decrease in the conversion efficiency, related to a partial absorption of the incident radiation by the reflector, and a reduction in the reflectivity features, related to dirt or aging [4,5]. Additionally, the...