Assessment of the potential of using phase change materials for latent heat thermal storage

Abstract. This work was part of the European Union’s Horizon 2020 Making-City program aiming to increase information regarding the positive energy districts. In this study as part of the project, possible use of phase change materials (PCM) in thermal storage was studied to increase its capacity by adding encapsulated materials to the conventional hot water tank. Although the use of PCMs has been studied previously, there still is a need for more practical research regarding the increase of energy content and its discharge properties. Therefore, we studied the theory of PCMs, commercial availability, theoretical viability, and practical viability of PCMs to set up practical test equipment to monitor temperature changes and to measure their efficiency in increasing the energy content. Four different PCM materials from multiple commercial PCM producers were tested in comparable tests with temperature measured in the function of time. Encapsulated PCMs were selected as they have been suggested to be the best option to nullify the negative properties according to previous studies. Increased energy gained by using the PCM was calculated for thermal storage based on previous studies and using commercial materials technical specifications. Finally, practical testing equipment was made to test PCMs and compare the results with theoretical calculations. All selected materials were tested in four different temperatures 70, 67.5, 65, and 62.5 °C with three cycles for each temperature. All experiments had consistent PCM/water volume relation (1/3) with additional control tests containing just water. After the automated test cycles were finished, temperature data with 30 seconds intervals were collected. Although, the mean temperature showed that all PCMs increased the overall energy content of the storage, the amount of latent energy stored differed as well as thermal conduction rates. The results revealed that compared to the control test with water, the highest calculated energy increase was in the range of 28 to 37 % depending on test temperature, which was lower in comparison to the expected theoretical energy increase

Maintaining and managing athletic identity among elite athletes

Researchers have studied athletic identity (AI) and explored the impact that having a strong AI can have on an athlete. Additionally, researchers have explored the maintenance of AI, but only among very specific athletic populations. Little is known about how different athletes manage their AI at various stages in their career (i.e., still competing versus retired). Therefore, the purpose of this study was to explore how both retired and non-retired elite athletes from a range of sports maintain and perpetuate their AI. Five male and eight female elite athletes were individually interviewed on two separate occasions. Participants were asked questions regarding their AI, their successes and failures in sport, and how their feelings of self-worth were related to their athletic achievements. An inductive data analysis process was used, and relevant themes were identified. It was also found that there are things athletes do, or that occur in their environment that maintain and perpetuate their AI. The current findings expand this body of literature by exploring the various strategies elite athletes use to support their AI.Los investigadores han estudiado la identidad atlética (AI) y han explorado el impacto que puede generar tener una AI fuerte en un atleta. Además, los investigadores han explorado el mantenimiento de la AI, pero sólo entre las poblaciones atléticas muy específicas. Poco se sabe acerca de cómo los diferentes atletas manejan su AI en varias etapas de su carrera (es decir, siguen compitiendo contra jubilados). Por lo tanto, el propósito de este estudio fue explorar cómo los atletas de elite jubilados y no retirados de una variedad de deportes mantienen y perpetúan su AI. Cinco atletas de élite masculinos y ocho femeninos fueron entrevistados individualmente en dos ocasiones. Se les preguntó a los participantes acerca de su AI, sus éxitos y fracasos en el deporte, y cómo sus sentimientos de autoestima estaban relacionados con sus logros atléticos. Se utilizó un proceso inductivo de análisis de datos y se identificaron temas relevantes. También se encontró que hay cosas que los atletas hacen, o que ocurren en su entorno que mantienen y perpetúan su AI. Los hallazgos actuales amplían este cuerpo de literatura explorando las diversas estrategias que los atletas de élite usan para apoyar su AI

mm-Wave DRW Antenna Phase Centre Determination

This document presents an approach to the phase centre determination of a dielectric rod waveguide (DRW) antenna by means of measurements obtained with a planar measuring system at millimeter wave lengths. Phase centre determination by the least squares fit technique is described in this document for different DRW antennas (silicon and sapphire). Results at different operating frequencies are offered

Use of satellite erythemal UV products in analysing the global UV changes

Long term changes in solar UV radiation affect global bio-geochemistry and climate. The satellite-based dataset of TOMS (Total Ozone Monitoring System) and OMI (Ozone Monitoring Instrument) of erythemal UV product was applied for the first time to estimate the long-term ultraviolet (UV) changes at the global scale. The analysis of the uncertainty related to the different input information is presented. OMI and GOME-2 (Global Ozone Monitoring Experiment-2) products were compared in order to analyse the differences in the global UV distribution and their effect on the linear trend estimation. <br></br> The results showed that the differences in the inputs (mainly surface albedo and aerosol information) used in the retrieval, affect significantly the UV change calculation, pointing out the importance of using a consistent dataset when calculating long term UV changes. The areas where these differences played a major role were identified using global maps of monthly UV changes. Despite the uncertainties, significant positive UV changes (ranging from 0 to about 5 %/decade) were observed, with higher values in the Southern Hemisphere at mid-latitudes during spring-summer, where the largest ozone decrease was observed

Co-designing the knowledge management model

This work-in-progress study reviews co-designing processes through the lens of possibility-driven design (PDD). A knowledge management model (KMM) is co-designed by facilitating the development work of senior and regional innovation actors who share ideas, experience and information in the development of smart products and services for an age-friendly smart living environment. The empirical part is divided into three stages: an orientation workshop, two panel meetings and three co-design and validation workshops where an appropriate knowledge management model is co-designed through iteration rounds. The first stage maps the regional innovation actors, relevant organisations in the region and data flows between all the parties. Ideas of suitable ways to manage knowledge are gathered from the panel meetings of the second stage and are methodologically supported by the strategic options development and analysis (SODA) approach. At the time of writing this paper, the third stage consisting of three workshops with appropriate iteration rounds is on-going. The findings of the study provide insights regarding the use of PDD activities with an inclusion of the SODA approach when facilitating the co-design of a KMM with a multi-professional group of experts. The study contributes to the theory of PDD by integrating systematic methodological aspects to it when working on complex problems.info:eu-repo/semantics/publishedVersio

Quantification of uncertainty in aerosol optical thickness retrieval arising from aerosol microphysical model and other sources, applied to Ozone Monitoring Instrument (OMI) measurements

Satellite instruments are nowadays successfully utilised for measuring atmospheric aerosol in many applications as well as in research. Therefore, there is a growing need for rigorous error characterisation of the measurements. Here, we introduce a methodology for quantifying the uncertainty in the retrieval of aerosol optical thickness (AOT). In particular, we concentrate on two aspects: uncertainty due to aerosol microphysical model selection and uncertainty due to imperfect forward modelling. We apply the introduced methodology for aerosol optical thickness retrieval of the Ozone Monitoring Instrument (OMI) on board NASA's Earth Observing System (EOS) Aura satellite, launched in 2004. We apply statistical methodologies that improve the uncertainty estimates of the aerosol optical thickness retrieval by propagating aerosol microphysical model selection and forward model error more realistically. For the microphysical model selection problem, we utilise Bayesian model selection and model averaging methods. Gaussian processes are utilised to characterise the smooth systematic discrepancies between the measured and modelled reflectances (i.e. residuals). The spectral correlation is composed empirically by exploring a set of residuals. The operational OMI multi-wavelength aerosol retrieval algorithm OMAERO is used for cloud-free, over-land pixels of the OMI instrument with the additional Bayesian model selection and model discrepancy techniques introduced here. The method and improved uncertainty characterisation is demonstrated by several examples with different aerosol properties: weakly absorbing aerosols, forest fires over Greece and Russia, and Sahara desert dust. The statistical methodology presented is general; it is not restricted to this particular satellite retrieval application

Targeted memory reactivation of newly learned words during sleep triggers REM-mediated integration of new memories and existing knowledge

Recent memories are spontaneously reactivated during sleep, leading to their gradual strengthening. Whether reactivation also mediates the integration of new memories with existing knowledge is unknown. We used targeted memory reactivation (TMR) during slow-wave sleep (SWS) to selectively cue reactivation of newly learned spoken words. While integration of new words into their phonological neighbourhood was observed in both cued and uncued words after sleep, TMR-triggered integration was predicted by the time spent in rapid eye movement (REM) sleep. These data support complementary roles for SWS and REM in memory consolidation

Evolution of competitive ability for essential resources

Competition for limiting resources is among the most fundamental ecological interactions and has long been considered a key driver of species coexistence and biodiversity. Species’ minimum resource requirements, their R*, are key traits that link individual physiological demands to the outcome of competition. However, a major question remains unanswered -- to what extent are species’ competitive traits able to evolve in response to resource limitation? To address this knowledge gap, we performed an evolution experiment in which we exposed Chlamydomonas reinhardtii for approximately 285 generations to seven environments in chemostats which differed in resource supply ratios (including nitrogen, phosphorus and light limitation) and salt stress. We then grew the ancestors and descendants in common garden experiments and quantified their competitive abilities for essential resources. We investigated constraints on trait evolution by testing whether changes in resource requirements for different resources were correlated. Competitive abilities for phosphorus improved in all populations, while competitive abilities for nitrogen and light increased in some populations and decreased in others. In contrast to the common assumption that there are trade-offs between competitive abilities for different resources, we found that improvements in competitive ability for a resource came at no detectable cost. Instead, improvements in competitive ability for multiple resources were either positively correlated or not significantly correlated. Using resource competition theory, we then demonstrated that rapid adaptation in competitive traits altered the predicted outcomes of competition. These results highlight the need to incorporate contemporary evolutionary change into predictions of competitive community dynamics over environmental gradients