Dynamic Parameters to Characterize the Thermal Behaviour of a Layer Subject to Periodic Phase Changes

Abstract The paper addresses the issue of the dynamic characterization of a layer subject to phase change (PCM) with non-sinusoidal periodic boundary conditions, which are typical of the external walls of air-conditioned building. The dynamic parameters used to characterize a monophase layer are not sufficient to describe how the temperature and heat flux trends in transfer through a layer subject to phase change are modified. Furthermore, a PCM due to the effect of latent heat associated with the phase change significantly modifies the heat storage capacity of the wall. The proposed parameters are determined by means of an explicit finite difference numerical model, considering PCM with different melting temperatures and thermophysical properties. The boundary conditions are such that one or more bi-phase interfaces originate in the layer. These parameters can be used for the thermal design of innovative walls in air-conditioned buildings with the aim of reducing power peaks entering the indoor environment, or to reduce thermal requirements, or to improve the thermal comfort within the building

Dynamic Thermal Characteristics of Opaque Building Components. A Proposal for the Extension of EN ISO 13786

Abstract In order to dynamically characterise the opaque components of a building envelope subject to sinusoidal loadings in steady periodic regime conditions, the use of nondimensional periodic thermal transmittance is proposed. Such a parameter allows for the evaluation of the decrement factor and time lag that the heat flux undergoes while crossing the wall and the efficiency of the heat storage. For non-sinusoidal loadings, dynamic characterisation is obtained by the decrement factor, defined as the ratio between energy in a semi period entering the indoor environment and entering the wall and as the ratio between maximum heat fluxes entering the environment and the wall, and as the ratio between the minimum heat fluxes. These parameters allow to determine the heat storage capacity of the component, the maximum heat flux in summer and winter conditions and their time lags. The defined dynamic properties were calculated considering two commonly used walls and surrounding conditions that are representative of the effective operative conditions

Influence of maternal and perinatal factors on subsequent hospitalisation for asthma in children: evidence from the Oxford record linkage study

Background: There is much interest in the possibility that perinatal factors may influence the risk of disease in later life. We investigated the influence of maternal and perinatal factors on subsequent hospital admission for asthma in children. Methods: Analysis of data from the Oxford record linkage study (ORLS) to generate a retrospective cohort of 248 612 records of births between 1970 and 1989, with follow-up to records of subsequent hospital admission for 4 017 children with asthma up to 1999. Results: Univariate analysis showed significant associations between an increased risk of admission for asthma and later years of birth (reflecting the increase in asthma in the 1970s and 1980s), low social class, asthma in the mother, unmarried mothers, maternal smoking in pregnancy, subsequent births compared with first-born, male sex, low birth weight, short gestational age, caesarean delivery, forceps delivery and not being breastfed. Multivariate analysis, identifying each risk factor that had a significant effect independently of other risk factors, confirmed associations with maternal asthma (odds ratio (OR) 3.1, 95% confidence interval 2.7-3.6), male sex (versus female, 1.8, 1.7-2.0), low birth weight (1000-2999 g versus 3000-3999 g, 1.2, 1.1-1.3), maternal smoking (1.1, 1.0-1.3) and delivery by caesarean section (1.2; 1.0-1.3). In those first admitted with asthma under two years old, there were associations with having siblings (e.g. second child compared with first-born, OR 1.3, 1.0-1.7) and short gestational age (24-37 weeks versus 38-41 weeks, 1.6, 1.2-2.2). Multivariate analysis confined to those admitted with asthma aged six years or more, showed associations with maternal asthma (OR 3.8, 3.1-4.7), age of mother (under 25 versus 25-34 at birth, OR 1.16, 1.03-1.31; over 35 versus 25-34, OR 1.4, 1.1-1.7); high social class was protective (1 and 2, compared with 3, 0.72; 0.63-0.82). Hospital admission for asthma in people aged over six was more common in males than females (1.4; 1.2-1.5); but, by the teenage years, the sex ratio reversed and admission was more common in females than males. Conclusion: Several maternal characteristics and perinatal factors are associated with an elevated risk of hospital admission for asthma in the child in later life. </p

Data demonstrating the influence of the latent storage efficiency on the dynamic thermal characteristics of a PCM layer

Dynamic thermal characteristics, for each month of the year, of PCM layers with different melting temperatures and thermophysical properties, in a steady periodic regime, were determined (Mazzeo et al., 2017 [1]). The layer is subjected to climatic conditions characterizing two locations, one with a continental climate and the second one with a Mediterranean climate. This data article provides detailed numerical data, as a function of the latent storage efficiency, including monthly average daily values: of the latent energy fraction, of the decrement factors of the temperature, of the heat flux and of the energy, and of the time lags of the maximum and minimum peaks of the temperature and of the heat flux

The involvement of area 8B in a switching system to control eye and ear orienting processes in Macaca monkey

Aim: the purpose of this study was to investigate unit activity of area 8B, rostral to the dorsal premotor cortex, in relation to different environmental acoustic stimuli and the effect of the engagement of attention during visual fixation

MAY THE WARNING AUDITORY-VISUAL NEURONS HELP THE MONKEY TO PLAY THE PIANO?

Aim: In previous reports, we showed the involvement of PEEF (area 8B) neurons in auditory information processing and in ear and eye orienting behaviour. For what concerns auditory cells, we observed, by unit activity recording, that their activity was related to complex environmental auditory stimuli but not to pure tones. Our question was: if we train intensively a monkey, much more than previous animals, to receive the reward only after having listened to a particular note, may the monkey's neurons discriminate different notes?Methods: For this aim, we trained intensively a Macaque monkey to receive some drops of fruit juice only after having listened to a particular note (FA), while it did not receive the reward after the presentation of a different note (DO). Moreover, during the experiments also the note SOL was presented without reward. The animal was also trained for a classic visual fixation task.Results: We recorded two types of cells: a) classic auditory environmental neurons and b) neurons that discharged for FA and SOL notes but not for DO note. The discharge was brisk for the FA note, it was less intensive with a rapid adaptation for the SOL note and very weak for the DO note. In addition the discharge was scarce for the clik of the pump, and active during visual fixation task before the clik of the pump.Conclusion: Present data confirm the role of the PEEF in auditory-visual integration and expand the vision of this field. The presence of cross modal neurons (auditory-visual) and the ability to discriminate between different notes suggest to speculate that this field may be involved in music learning

Impianto rinnovabile ibrido fotovoltaico-eolico con accumulo per la produzione di energia elettrica per uso residenziale: studio di fattibilità energetica ed economica

In questo lavoro è presentata un’analisi energetica ed economica di un sistema ibrido connesso alla rete, costituito da un generatore fotovoltaico, un microgeneratore eolico e un sistema di accumulo elettrico, per la fornitura di energia elettrica ad uso residenziale. Lo studio è stato effettuato in ambiente TRNSYS, attraverso la definizione di un modello e un algoritmo dinamico per la valutazione della potenza elettrica in ingresso e in uscita da ciascun componente del sistema ibrido. In particolare, la potenza prodotta e utilizzata dall’utenza, la potenza accumulata e rilasciata dalla batteria, la potenza in eccesso e la potenza prelevata dalla rete sono state calcolate in relazione all’andamento temporale del carico elettrico dell’utenza residenziale. Gli andamenti temporali delle potenze sono state utilizzate per valutare le prestazioni energetiche annuali del sistema al variare della potenza del generatore fotovoltaico e del generatore eolico, per diversi valori della capacità di accumulo elettrico. L’analisi parametrica ha permesso di identificare le configurazioni del sistema che garantiscono valori elevati di energia prodotta e autoconsumata e valori ridotti di energia in eccesso inviata alla rete. I risultati dell’analisi energetica sono stati utilizzati per sviluppare un’analisi economica impiegando il metodo del Net Present Value (NPV), allo scopo di stimare la fattibilità dell’investimento e di definire la migliore configurazione del sistema