Effect of fins and nanoparticles in the discharge performance of PCM thermal storage system with a multi pass finned tube heat exchange

This work studies the heat exchange process of a latent heat thermal energy storage (LHTES) system equipped with a compact finned tubes heat exchanger (HE) as this is one of the most important aspects of the storage system, the capacity for effectively delivering its stored energy. This work fills in a literature gap for 3D, transient heat transport fluid (HTF) flow models concerning storage systems with phase change materials (PCMs) with fins and nanoparticles allowing for an evaluation on the quality of heat delivered by the system. Numerical simulations, for full turbulent conditions of the HTF flow, were developed to access the influence of the fin pitch and the PCM thermal properties in the performance of the energy discharge process. Samples of commercial paraffin-wax A53 doped with graphene based nanoplatelets were tested and characterised. Different types of nanoplatelets were employed in the range of 0.5% to 6% weight. Measured data of the thermal conductivity, specific heat and fusion latent heat are presented. The simulations were developed for three fin pitch values 5 , 10 and 20 mm and for 1%wt and 6%wt nanoparticles loads. The effect of fins and combination of fins and nanoparticles in the outlet temperature and liquid fraction distribution inside the LHTES unit during the discharge process in a 3D full scale model was analysed. The system performance was evaluated based of off the outlet temperature of HTF to ascertain both the quantity and quality of the heat provided. The results show that the PCM thermal conductivity is significantly enhanced by the addition of graphene nanoparticles with a high aspect ratio. The addition of only 1%wt doubled the solid phase PCM thermal conductivity and for a 6%wt load the thermal conductivity increased by a factor of 3.5. Meanwhile, specific and latent heat values of the samples are relatively unaffected. The numerical results further show that applying thin fins is an effective approach to enhance LHTES systems discharge performance. Increasing the fin number significantly enhances the heat transfer rate and the HTF discharge temperature during solidification and has a positive impact in the useful discharge heat capacity, providing better quality heat. Combining fins and nanoparticles improves the discharge process, nevertheless the role of nanoparticles becomes secondary as the fins number increases. The results demonstrate that standardised compact finned heat exchangers ubiquitously used in the HVAC industry can successfully overcome the low thermal conductivity of common PCMs without compromising the useful heat discharge capacity or resorting to nanoparticles decreasing the discharge time between 60 and 77% with adequate fin number.info:eu-repo/semantics/publishedVersio

Disability in multiple sclerosis is related to thalamic connectivity and cortical network atrophy.

BACKGROUND: Thalamic atrophy is proposed to be a major predictor of disability progression in multiple sclerosis (MS), while thalamic function remains understudied. OBJECTIVES: To study how thalamic functional connectivity (FC) is related to disability and thalamic or cortical network atrophy in two large MS cohorts. METHODS: Structural and resting-state functional magnetic resonance imaging (fMRI) was obtained in 673 subjects from Amsterdam (MS: N = 332, healthy controls (HC): N = 96) and Graz (MS: N = 180, HC: N = 65) with comparable protocols, including disability measurements in MS (Expanded Disability Status Scale, EDSS). Atrophy was measured for the thalamus and seven well-recognized resting-state networks. Static and dynamic thalamic FC with these networks was correlated with disability. Significant correlates were included in a backward multivariate regression model. RESULTS: Disability was most strongly related (adjusted R2 = 0.57, p < 0.001) to higher age, a progressive phenotype, thalamic atrophy and increased static thalamic FC with the sensorimotor network (SMN). Static thalamus-SMN FC was significantly higher in patients with high disability (EDSS ⩾ 4) and related to network atrophy but not thalamic atrophy or lesion volumes. CONCLUSION: The severity of disability in MS was related to increased static thalamic FC with the SMN. Thalamic FC changes were only related to cortical network atrophy, but not to thalamic atrophy

A randomized trial predicting response to cognitive rehabilitation in multiple sclerosis:Is there a window of opportunity?

BACKGROUND: Cognitive training elicits mild-to-moderate improvements in cognitive functioning in people with multiple sclerosis (PwMS), although response heterogeneity limits overall effectiveness. OBJECTIVE: To identify patient characteristics associated with response and non-response to cognitive training. METHODS: Eighty-two PwMS were randomized into a 7-week attention training (n = 58, age = 48.4 ± 10.2 years) or a waiting-list control group (n = 24, age = 48.5 ± 9.4 years). Structural and functional magnetic resonance imaging (MRI) was obtained at baseline and post-intervention. Twenty-one healthy controls (HCs, age = 50.27 ± 10.15 years) were included at baseline. Responders were defined with a reliable change index of 1.64 on at least 2/6 cognitive domains. General linear models and logistic regression were applied. RESULTS: Responders (n = 36) and non-responders (n = 22) did not differ on demographics, clinical variables and baseline cognition and structural MRI. However, non-responders exhibited a higher baseline functional connectivity (FC) between the default-mode network (DMN) and the ventral attention network (VAN), compared with responders (p = 0.018) and HCs (p = 0.001). Conversely, responders exhibited no significant baseline differences in FC compared with HCs. Response to cognitive training was predicted by lower DMN-VAN FC (p = 0.004) and DMN-frontoparietal FC (p = 0.029) (Nagelkerke R(2) = 0.25). CONCLUSION: An intact pre-intervention FC is associated with cognitive training responsivity in pwMS, suggesting a window of opportunity for successful cognitive interventions

Incorporating temporal-bounded CBR techniques in real-time agents

Nowadays, MAS paradigm tries to move Computation to a new level of abstraction: Computation as interaction, where large complex systems are seen in terms of the services they offer, and consequently in terms of the entities or agents providing or consuming services. However, MAS technology is found to be lacking in some critical environments as real-time environments. An interaction-based vision of a real-time system involves the purchase of a responsibility by any entity or agent for the accomplishment of a required service under possibly hard or soft temporal conditions. This vision notably increases the complexity of these kinds of systems. The main problem in the architecture development of agents in real-time environments is with the deliberation process where it is difficult to integrate complex bounded deliberative processes for decision-making in a simple and efficient way. According to this, this work presents a temporal-bounded deliberative case-based behaviour as an anytime solution. More specifically, the work proposes a new temporal-bounded CBR algorithm which facilitates deliberative processes for agents in real-time environments, which need both real-time and deliberative capabilities. The paper presents too an application example for the automated management simulation of internal and external mail in a department plant. This example has allowed to evaluate the proposal investigating the performance of the system and the temporal-bounded deliberative case-based behaviour. 2010 Elsevier Ltd. All rights reserved.This work is supported by TIN2006-14630-C03-01 projects of the Spanish government, GVPRE/2008/070 project, FEDER funds and CONSOLIDER-INGENIO 2010 under Grant CSD2007-00022.Navarro Llácer, M.; Heras Barberá, SM.; Julian Inglada, VJ.; Botti Navarro, VJ. (2011). Incorporating temporal-bounded CBR techniques in real-time agents. Expert Systems with Applications. 38(3):2783-2796. https://doi.org/10.1016/j.eswa.2010.08.070S2783279638

Investigating aspects of health among older Greeks The development and utilisation of an Hellenic version of a multidimensional and functional assessment questionnaire

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN043816 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Mechanisms of Coordination between healthcare policy and other public policy sectors to speed up the response to the Coronavirus crises: Greece

Costis Prouskas (Aktios SA).-- Proyecto “Diseño de mecanismos de coordinación entre la política sanitaria y otros sectores de política pública para agilizar la respuesta a las crisis a partir del estudio de caso de las relaciones entre el sistema sanitario y la atención institucionalizada a mayores en contexto de pandemia en España y en Europa” (Mc-COVID19), financiado por el CSIC como Proyecto Intramural en el marco de la Plataforma Temática Interdisciplinar Salud Global.-- Los principales investigadores son Eloísa del Pino y Francisco Javier Moreno (CCHS-IPP, CSIC).Financiado por el CSIC como Proyecto Intramural en el marco de la Plataforma Temática Interdisciplinar Salud Global.Peer reviewe

Alternative tandem geometries for high efficiency thin film solar cells

In the global effort to reduce greenhouse gas emissions and the planet's energy dependence on fossil fuels with a corresponding transition to green energy, solar radiation is of great interest, which can provide huge amounts of exploitable energy. In the field of solar photovoltaics, the scientific community is oriented towards flexible solar cell technologies that are more environmentally friendly and have lower production costs in order to increase their efficiency. These technologies include photovoltaics that use perovskites or organic compounds as photosensitive material as well as Dye-Sensitized Solar Cells (DSSC). In particular, DSSC technology is used more for energy production inside buildings where the corresponding intensities are low and the solar cells operate more efficiently.The purpose of this study is to investigate the alternative geometries that could improve the characteristics of the existing technology of DSSCs, without any intervention or modification in the materials it uses, but only by optical methods and to make possible their use in external spaces. An extensive study was made of the mechanism used by DSSC technology to generate electricity, dealing with different laboratory methods of making the solar cells (doctor-blade, spin coating and screen printing) as well as using two different methods for the fabrication of TiO2 thin film and different types of pigments in the role of the sensitizer (natural and commercial dyes) in order to achieve repeatability and stable characteristics of the fabricated solar cells. The characterization of the individual successive layers of the thin films that consist photoanode was done by optical methods. We were not focused on achieving high efficiencies of solar cells but only on the success of their fabrication with the aim their stable characteristics in order to study their behavior in conjunction with the alternative geometries to increase their efficiency and lifetime under high radiation intensities.An original method of trapping sunlight through a new type of architectural design was investigated. The methodology developed was a "U" type architecture on the vertical sides at which are located the pigment-sensitized solar cells. The bottom of this new geometry evenly distributes the vertically incoming solar radiation on its vertical sides where the intensity of the radiation is significantly reduced and the solar cells operate in suitable conditions to become more efficient. The absorption of incoming photons is done gradually by the individual cells through the mechanism of multiple reflections between the parallel vertical sides of the device. The important advantages of the new vertical architecture are both the optimization of the filling factor of the cells located inside it resulting in a significant increase in their lifespan as well as the indirect increase of the total active surface of the cells per unit of exposed horizontal surface. Indirect increase of the total active surface area means that more photons are absorbed simultaneously by different solar cells which may have different absorption spectra. This creates a hybrid light trapping cell that may comprise at least two or more DSSC type solar cells which are suitably interconnected.Σκοπός της παρούσας μελέτης είναι να ερευνηθούν οι εναλλακτικές γεωμετρίες οι οποίες θα μπορούσαν να βελτιώσουν τα χαρακτηριστικά της ήδη υπάρχουσας τεχνολογίας των DSSCs, χωρίς καμία παρέμβαση ή τροποποίηση στα υλικά που αυτή χρησιμοποιεί παρά μόνο με εναλλακτικές αρχιτεκτονικές και οπτικές μεθόδους ώστε να γίνει εφικτή η χρησιμοποίησή τους σε εφαρμογές εξωτερικών χώρων Το ενδιαφέρον δεν επικεντρώθηκε στην επίτευξη υψηλών αποδόσεων των ηλιακών κυττάρων παρά μόνο στην επιτυχία της μεθοδολογίας κατασκευής τους με στόχο τη μελέτη της συμπεριφοράς τους σε συνεργασία με εναλλακτικές γεωμετρίες για την αύξηση της απόδοσης και της διάρκειας ζωής τους κάτω από υψηλές εντάσεις ακτινοβόλησης.Διερευνήθηκε μια πρωτότυπη μέθοδος παγίδευσης της ηλιακής ακτινοβολίας δια μέσου μιας νέου τύπου αρχιτεκτονικής σχεδίασης. Η μεθοδολογία που αναπτύχθηκε ήταν μια αρχιτεκτονική τύπου “U” στις κατακόρυφες πλευρές της οποίας βρίσκονται τοποθετημένα τα ευαισθητοποιημένα με χρωστικές ηλιακά κύτταρα. Ο πυθμένας της νέας αυτής γεωμετρίας διαμοιράζει εξίσου την κατακόρυφα εισερχόμενη ηλιακή ακτινοβολία στις κατακόρυφες πλευρές της όπου η ένταση της ακτινοβολίας υποβιβάζεται σημαντικά και τα ηλιακά κύτταρα λειτουργούν σε συνθήκες κατάλληλες ώστε να γίνουν αποδοτικότερα. Η απορρόφηση των εισερχόμενων φωτονίων γίνεται σταδιακά από τα επιμέρους κύτταρα μέσω του μηχανισμού των πολλαπλών ανακλάσεων μεταξύ των παράλληλων κατακόρυφων πλευρών της διάταξης. Τα σημαντικά πλεονεκτήματα της νέας κατακόρυφης αρχιτεκτονικής είναι τόσο η βελτιστοποίηση του συντελεστή πλήρωσης των κυττάρων που βρίσκονται τοποθετημένα στο εσωτερικό της με αποτέλεσμα την σημαντική αύξηση της διάρκειας ζωής τους όσο και της έμμεσης αύξησης της συνολικής ενεργού επιφάνειας των κυττάρων ανά μονάδα εκτιθέμενης οριζόντιας επιφάνειας. Δημιουργείται έτσι μια υβριδική κυψελίδα παγίδευσης του φωτός η οποία μπορεί να περιλαμβάνει τουλάχιστον δύο ή και περισσότερα ηλιακά κύτταρα τύπου DSSC τα οποία είναι κατάλληλα διασυνδεδεμένα μεταξύ τους

Διερευνώντας πτυχές της υγείας ηλικιωμένων Ελλήνων: η ανάπτυξη και η χρήση της ελληνικής έκδοσης ενός ερωτηματολογίου πολυδιάστατης και λειτουργικής αξιολόγησης

The purpose of the research reported in this thesis was to develop a Greek version of the OARS assessment instrument, to validate this instrument in a Greek setting and then use it to investigate gender and geographical differences in the health and well being of two population subgroups in Greece. Three hundred people over the age of 65 from Athens and Thessaloniki were interviewed using the Greek version of the OMFAQ. The interviews were held in two stages. During the first stage the validity of the mental health and the physical health scale was examined using a hospitalised and a community sample of fifty people each. During the second stage two hundred people from two Athenian and two Thessalonician KAPI (Social Clubs for elderly people) were interviewed. Data were analysed using factor analysis and logistic regression in order to investigate the instrument’s factorial structure and the relationships between several domains of health. The validation study indicated that the instrument had good validity and reliability values. The main study showed there were several statistically significant geographical and gender differences in the populations examined. For example, rather surprisingly, it was found that KAPI users in Athens had more social ties and contacts than their counterparts in Thessaloniki. In addition, the study showed relationships between variables which followed a logical pattern, thus enhancing the instrument’s agreement to the theoretical framework, and increasing its construct validity. One of the outcomes of the research report is the validated instrument in Greek which can be used for further research on elderly people in Greece.Ο σκοπός αυτής της διδακτορικής διατριβής ήταν η δημιουργία πκ Ελληνικής έκδοσης του οργάνου αξιολόγησης OARS (Older American Resources and Services), η μελέτη της εγκυρότητας του οργάνου σε Ελληνικό πλαίσιο και με ελληνικό πληθυσμό και, ύστερα, η χρησιμοποίηση του νια να διερευνηθούν οι γεωγραφικές διαφορές και οι διαφορές μεταξύ των δύο φύλων στην υγεία και ευεξία δύο υποομάδων πληθυσμού στην Ελλάδα.Λήφθηκαν συνεντεύξεις από τριακόσιους ηλικιωμένους άνω της ηλικίας των 65 ετών από την Αθήνα και τη Θεσσαλονίκη χρησιμοποιώντας την ελληνική έκδοση του ερωτηματολογίου OARS. Οι συνεντεύξεις λήφθηκαν σε δύο στάδια. Κατά το πρώτο στάδιο (πιλοτική μελέτη) εξετάστηκε η εγκυρότητα των τμημάτων Ψυχικής και Σωματικής υγείας. Χρησιμοποιήθηκαν δύο δείγματα, ένα νοσοκομειακό και ένα κοινοτικό, πενήντα ατόμων το κάθε ένα. Στο δεύτερο στάδιο προσεγγίστηκαν διακόσια άτομα από τέσσερα ΚΑΠΗ. δύο των Αθηνών και δύο της Θεσσαλονίκης.Για την ανάλυση των στοιχείων χρησιμοποιήθηκαν παραγοντικές αναλύσεις και λογιστικές παλινδρομήσεις. Με αυτόν τον τρόπο επιχειρήθηκε να διερευνηθεί η παραγοντική δομή των κλιμάκων του ερωτηματολογίου και οι συσχετισμοί μεταξύ διαφόρων διαστάσεων της υγείας.Η πιλοτική μελέτη απέδειξε ότι το όργανο είναι έγκυρο και αξιόπιστο και άρα κατάλληλο για χρήση με ελληνικό πληθυσμό. Από την κύρια μελέτη προέκυψαν αρκετές στατιστικώς σημαντικές γεωγραφικές διαφορές και διαφορές μεταξύ των δύο φύλων στους πληθυσμούς οι οποίοι εξετάστηκαν. Για παράδειγμα, βρέθηκε ότι οι χρήστες ΚΑΠΗ στην Αθήνα είχαν περισσότερες κοινωνικές επαφές και κοινωνικούς δεσμούς από ότι αυτοί στη Θεσσαλονίκη.Η μελέτη βρήκε συσχετισμούς μεταξύ διαφόρων μεταβλητών οι οποίοι έχουν εντοπιστεί και σε άλλες ερευνητικές προσπάθειες. Επίσης, η παραγοντική δομή του οργάνου συμφωνεί με τα ευρήματα της υπάρχουσας διεθνούς και ελληνικής βιβλιογραφίας. Με αυτόν τον τρόπο επιβεβαιώνεται η συμφωνία του οργάνου με το θεωρητικό υπόβαθρο και ενισχύεται η εγκυρότητα εννοιολογικής κατασκευής του.Με τα ευρήματα της παρούσας ερευνητικής προσπάθειας προκύπτει η ελληνική έκδοση του οργάνου αξιολόγησης OARS. Με θεμελιωμένη και εξακριβωμένη την εγκυρότητα και την αξιοπιστία του, το όργανο, τα ευρήματα και τα συμπεράσματα αυτής της έρευνας παραδίδονται προς χρήση στους επαγγελματίες υγείας και ψυχικής υγείας νια την εκτίμηση της υγείας των ηλικιωμένων Ελλήνων