Numerical investigation of heat transfer in air channels for thermal energy storage applications in buildings

Energy demand has significantly increased in building sectors over the past decade because of population growth, increased indoor activities, and increased energy requirements for controlling the internal environment due to global climate change. The residential sector accounts for 32% of the total energy consumption. Space and water heating account for most of the fossil fuel use in residential buildings. Several studies have been done to optimize the design of heat transfer fins and channels in space and water heating systems to improve their efficiency. In this study the effects of the cross-sectional shape of air-channels on heat transfer from the channels to the air is investigated. Air channels with circular, triangular, rectangular and sinusoidal shaped cross sections are considered. Further, heat transfer to air flowing through beds comprising these air channels are also investigated. Numerical analyses is performed to investigate the dependency of the outlet temperatures to optimize the shape of the air channels and beds. Results show the sinusoidal channel and bed have better performance in relation to the outlet temperature. Considering channels with a length of 100 mm, a surface area of 1770 m2, and a wall-to-air heat transfer rate of 790 W/m2, the air outlet temperature for the sinusoidal channel is about 57°C higher than that of the circular channel. Considering beds with a height of 5 mm and wall-to-air heat transfer rate of 790 W/m2, the outlet temperature of the sinusoidal bed is about 10°C higher than the outlet temperature for a rectangular bed with similar surface area. The results are applicable to the design of thermal energy storage units that could be used directly or indirectly (such as adsorbent beds for thermal energy storages) to supply heat to air within HVAC systems

The Royal Society of Chemistry:The deposition of Cu2ZnSnS(1-x)Sex thin films with tunable band gaps

ABSTRACT: Thin films of CZTSSe with band gaps ranging from 1.0 to 1.6 eV have been deposited using amolecular-precursor approach in Aerosol Assisted Chemical Vapor Deposition (AACVD). The [S]:[Se] ratiohas been varied and plays a key role in controlling the structure, morphology, electrical and optical propertiesof the deposited films. A Vegard-type analysis on the collected results showed a direct correlation between theconcentration of selenium in the precursor mixture and key performance parameters of the deposited films

Developing a model for e-prints and open access journal content in UK further and higher education

A study carried out for the UK Joint Information Systems Committee examined models for the provision of access to material in institutional and subject-based archives and in open access journals. Their relative merits were considered, addressing not only technical concerns but also how e-print provision (by authors) can be achieved – an essential factor for an effective e-print delivery service (for users). A "harvesting" model is recommended, where the metadata of articles deposited in distributed archives are harvested, stored and enhanced by a national service. This model has major advantages over the alternatives of a national centralized service or a completely decentralized one. Options for the implementation of a service based on the harvesting model are presented

Lens or Binary? Chandra Observations of the Wide Separation Broad Absorption Line Quasar Pair UM425

We have obtained a 110 ksec Chandra ACIS-S exposure of UM425, a pair of QSOs at z=1.47 separated by 6.5 arcsec, which show remarkably similar emission and broad absorption line (BAL) profiles in the optical/UV. Our 5000 count X-ray spectrum of UM425A (the brighter component) is well-fit with a power law (photon spectral index Gamma=2.0) partially covered by a hydrogen column of 3.8x10^22 cm^-2. The underlying power-law slope for this object and for other recent samples of BALQSOs is typical of radio-quiet quasars, lending credence to the hypothesis that BALs exist in every quasar. Assuming the same Gamma for the much fainter image of UM425B, we detect an obscuring column 5 times larger. We search for evidence of an appropriately large lensing mass in our Chandra image and find weak diffuse emission near the quasar pair, with an X-ray flux typical of a group of galaxies at redshift z ~ 0.6. From our analysis of archival HST WFPC2 and NICMOS images, we find no evidence for a luminous lensing galaxy, but note a 3-sigma excess of galaxies in the UM425 field with plausible magnitudes for a z=0.6 galaxy group. However, the associated X-ray emission does not imply sufficient mass to produce the observed image splitting. The lens scenario thus requires a dark (high M/L ratio) lens, or a fortuitous configuration of masses along the line of sight. UM425 may instead be a close binary pair of BALQSOs, which would boost arguments that interactions and mergers increase nuclear activity and outflows.Comment: 13 pages, 9 figures, Accepted for publication in the Astrophysical Journa

Investigating the psychometric properties of the carers’ fall concern instrument to measure carers’ concern for older people at risk of falling at home: A cross-sectional study

© 2020 John Wiley & Sons Ltd Aims: This study aimed to investigate the psychometric properties of the Carers’ Fall Concern Instrument (CFC-I) for measuring carers’ concern for older people (care recipients) at risk of falling. Background: Family carers are crucial in preventing older people from falling at home. Their concerns for older people at risk of falling have severe implications on carers’ psychological well-being and ability to prevent falls. However, there is no validated instrument measuring this concern. Methods: A cross-sectional study was used to examine the validity and reliability of the CFC-I. Carers looking after older people living at home completed the 17-item CFC-I and provided information about their care arrangements and the older people\u27s fall history. Construct validity was tested using exploratory factor analysis and hypothesis testing. Internal consistency was determined by calculating Cronbach\u27s alpha coefficient. Results: 143 carers completed the survey either by face-to-face or by online. After deleting one item with an item-total correlation of below 0.3, the remaining 16-item CFC-I reported a Cronbach alpha of 0.93. Construct validity was supported by strong item-total correlations (0.51–0.76), mean inter-item correlations (0.47) and factor loadings (0.557–0.809). Factor analysis revealed three factors that include concerns about care recipients’ health and function, living environment and carers’ perception of fall and fall risk. The 16-item CFC-I can discriminate between carers of older people with and without recurrent (fallen 3/ more times) falls. Conclusion: The 16-item CFC-I is a valid and reliable scale for measuring carers’ concern for the older people\u27s risk of falling. Future analysis of test–retest and inter-rater reliability of the instrument will further support its clinical use for carers. Implications for practice: The newly developed multi-item CFC-I can be used to quantify the carers’ level of fall concern and inform targeted interventions for carers when caring for older people who are at risk of falling

Caregivers’ Falls Concern For Older Persons In The Singapore Community

This paper discusses the prevalence of caregivers’ concern, its impact on fall prevention strategies, falls risk awareness among older persons, clinical points and study potential. Older persons suffering from fall-related psychological concerns such as fear of falling has been well established in previous research, however little is known about caregivers’ falls concern in its relationship with the risk of older persons falling. In Singapore, families are regarded as the fundamental support system for older people. The potential influence of caregivers’ concern on the outcome of fall prevention strategies and falls risk awareness of older persons is expected given their significant involvement in the older persons’ care. However, it is difficult to accurately appreciate the impact of caregivers’ falls concern on the risk of falls among older persons in the local community given the Singaporean cultural differences and the dearth of Singaporean research on caregiver’s concern. It is promulgated in this paper that further research should address the impact of caregivers’ falls concern on fall-related issues associated with caring for an older person at risk of falling

Impact of Colonoscopy Bowel Preparation on Intestinal Microbiota

The gut microbiota is important in maintaining human health, but numerous factors have the potential to alter its composition. Our aim was to examine the impact of a standard bowel preparation on the intestinal microbiota using two different techniques. Fifteen subjects undergoing colonoscopy consumed a bowel preparation comprised of 10 mg bisacodyl and 2 L polyethylene glycol. The microbiota of stool samples, collected one month before, one week before (pre-colonoscopy), and one week, one month, and three to six months after colonoscopy (post-colonoscopy) was evaluated. Two samples were taken three to six months apart from five healthy subjects who did not undergo colonoscopy. Universal primers targeting the V2-V3 region of the 16S rRNA gene were used to PCR amplify all samples for denaturing gradient gel electrophoresis (PCR-DGGE). Pre- and post-colonoscopy samples were compared using Dice's similarity coefficients. Three samples from ten subjects who underwent colonoscopy, and both samples from the five subjects who didn't, were used for high-throughput sequencing of the V1-V3 region of the 16S rRNA gene. Samples were curated and analysed in Mothur. Results of the DGGE analyses show that the fecal microbiota of a small number of subjects had short-term changes. High-throughput sequencing results indicated that the variation between the samples of subjects who underwent colonoscopy was no greater than the variation observed between samples from subjects who did not. We conclude that bowel preparation does not have a lasting effect on the composition of the intestinal microbiota for the majority of subjects.This work was funded by an Australian Post-Graduate Award scholarship. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript

From Data to Narratives: Scrutinising the Spatial Dimensions of Social and Cultural Phenomena Through Lenses of Interactive Web Mapping

Modern web mapping techniques have enhanced the storytelling capability of cartography. In this paper, we present our recent development of a web mapping facility that can be used to extract interesting stories and unique insights from a diverse range of socio-economic and demographic variables and indicators, derived from a variety of datasets. We then use three curated narratives to show that online maps are effective ways of interactive storytelling and visualisation, which allow users to tailor their own story maps. We discuss the reasons for the revival of the recent attention to narrative mapping and conclude that our interactive web mapping facility powered by data assets can be employed as an accessible and powerful toolkit, to identify geographic patterns of various social and economic phenomena by social scientists, journalists, policymakers, and the public

Investigation of physiological pulsatile flow in a model arterial stenosis using large-eddy and direct numerical simulations

Physiologicalpulsatileflow in a 3D model of arterialstenosis is investigated by using largeeddysimulation (LES) technique. The computational domain chosen is a simple channel with a biological type stenosis formed eccentrically on the top wall. The physiological pulsation is generated at the inlet using the first harmonic of the Fourier series of pressure pulse. In LES, the large scale flows are resolved fully while the unresolved subgrid scale (SGS) motions are modelled using a localized dynamic model. Due to the narrowing of artery the pulsatileflow becomes transition-to-turbulent in the downstream region of the stenosis, where a high level of turbulent fluctuations is achieved, and some detailed information about the nature of these fluctuations are revealed through the investigation of the turbulent energy spectra. Transition-to-turbulent of the pulsatileflow in the post stenosis is examined through the various numerical results such as velocity, streamlines, velocity vectors, vortices, wall pressure and shear stresses, turbulent kinetic energy, and pressure gradient. A comparison of the LES results with the coarse DNS are given for the Reynolds number of 2000 in terms of the mean pressure, wall shear stress as well as the turbulent characteristics. The results show that the shear stress at the upper wall is low just prior to the centre of the stenosis, while it is maximum in the throat of the stenosis. But, at the immediate post stenotic region, the wall shear stress takes the oscillating form which is quite harmful to the blood cells and vessels. In addition, the pressure drops at the throat of the stenosis where the re-circulated flow region is created due to the adverse pressure gradient. The maximum turbulent kinetic energy is located at the post stenosis with the presence of the inertial sub-range region of slope −5/3

Friedman tongue position and cone beam computed tomography in patients with obstructive sleep apnea

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139112/1/lio292.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139112/2/lio292_am.pd