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Thermal performance profiling of phase change materials integrated building envelopes through simulation-data envelopment analysis approach
Full text linkPhase change materials (PCM) regulate the heat flow between the ambient and the indoor spaces by their latent capacitance. Performance assessment of PCM integrated wall systems are often based on the gross energy demand reduction or reduction in heat gain over the year. However, the efficacy of PCM integrated wall systems is also driven by the effective utilization of the maximum latent thermal energy storage capacity. This paper presents a framework for thermal performance profiling of PCM-integrated envelopes using a relative performance metric termed thermal calibre. Data Envelopment Analysis technique is used for determining the thermal calibre, where minimizing the heat gains & inside surface temperature of the envelope and maximizing the utilization of the latent heat capacity of PCM are the objective functions. The approach is demonstrated by considering 190 PCM-integrated building envelopes applied to a residential building in a hot-dry climatic region. The thermal calibre of the envelopes vary from 0.62 to 1. Thermal calibre effectively captures the impact of thermo-physical property, location of PCM in the envelope, variations in thermal boundary conditions, seasonal and diurnal variations. The thermal calibre of envelopes increases with an increase in thickness of internal PCM layers. In contrast, the thickness of external PCM layers does not significantly affect their thermal calibre. This approach reveals the efficacy of the wall system over time of the year and presents an opportunity to solicit season-optimal performance. This method can be used as a post-hoc assessment to building simulations and pareto optimization facilitating informed decision making in the material selection process.</p
Involving community members in designing behavioural weight management programmes:A scoping review
Full text linkBackgroundInvolving community members when developing health programmes can improve intervention outcomes. We undertook a scoping review to describe how community members contributed to the development of Behavioural Weight Management Programmes (BWMPs). Different terms have been used to describe this process, including co-design, co-production, Community-Based Participatory Research, or Patient and Public Involvement and Engagement. Our aim was to describe: (1) at what stage(s) communities were involved (e.g. planning, delivering and/or evaluating); (2) what level of involvement they had (e.g. leading, collaborating, consulted, informed or not involved); and (3) examples of how they were involved.MethodsWe searched MEDLINE, EMBASE and CINAHL databases from 2010 to 2023. Two authors independently screened papers and extracted information using predefined criteria. We extracted data on study characteristics, and stages, levels and methods of community involvement.ResultsWe identified 58 BWMPs reported in 91 papers. Most were conducted in the US (n = 48, 83%). Their focus included race and ethnicity (n = 43, 73%), gender (n = 17, 29%) or low-income/underserved communities. Community members initiated the development of BWMPs in 36% of programmes (n = 21). Most programmes used community involvement to adapt an existing intervention (n = 33, 57%). Community involvement was highest at the planning stage where 55% (n = 32) of studies included community members as collaborators and 9% (n = 5) had community members leading the process. At the delivery stage, nine studies (16%) were led by community members and 19 (33%) included them as collaborators. In the evaluation stage, no studies were led by community members but a quarter (n = 14, 24%) included them as collaborators. Few programmes reported either the cost (n = 3, 5%) or the duration (n = 13, 22%) of community involvement. Programme adaptations ranged from relatively easy-to-implement changes such as changing language or menus, to more substantive adaptations like format, activity and personnel.ConclusionsOur review identified substantial levels of community involvement (leadership or collaboration) in planning BWMPs, but less so in their delivery, and rarely in evaluation. Greater involvement of communities in evaluation would ensure programmes focus on what matters most to them. Reporting of community involvement, especially costs and time involved, should be improved to allow for shared learning
Understanding the Molecular Basis of Amyloid-beta Interaction by Neprilysin in Alzheimer’s Disease
No full textInvestigation of Non-Inductive Bifilar Pancake SFCL Losses in Electric Aircraft Cryogenic Propulsion
Full text linkSuperconducting powertrain is critical for nextgeneration electric aircraft, allowing for lossless power transmission and significantly increasing efficiency, performance, and range. A superconducting fault current limiter (SFCL) is a device on the DC side that uses superconducting materials to control excessive current during faults, thereby protecting the powertrain and enhancing system stability. Among several superconducting fault current limiters (SFCLs), resistive SFCLs (R-SFCLs) have benefits such as compactness, lightweight, high reliability, and a fail-safe nature. When subjected to alternating magnetic fields or currents, superconducting materials exhibit hysteresis, eddy currents, and flux flow effects, which lead to energy dissipation and reduced efficiency. This also applies to RSFCLs operating under normal conditions in the superconducting state, where AC losses occur and require appropriate thermal management to mitigate heat generation and prevent unexpected quenching. DC current ripple and its harmonic contents in an R-SFCL cause additional losses, increasing joule heating and potentially driving the superconductor out of its superconducting state, reducing its efficiency and fault-limiting capability. This research was conducted from two perspectives: theoretical calculations and experiments. The objective is to study the losses in the R-SFCL within the superconducting system, including ripple and harmonic effects, and to determine the design parameters of the R-SFCL cooling system to minimise thermal impacts
The Influence of Axial Throughflow Swirl on Buoyancy-Induced Flow in a Compressor Cavity
Full text linkNext-generation aero-engine compressors will operate with overall pressure ratios exceeding 70:1. This will require shorter compressor blades, presenting a challenge to the designer when predicting tip clearance and efficiency. Buoyancy-induced flow within co-rotating compressor discs drives the heat transfer that determines rotor expansion and the resulting blade-tip clearance. This inherently unstable flow is influenced by the radial temperature distribution of the discs, rotational speed, as well as enthalpy and momentum exchange with an axial throughflow of cooled air at low radius. Due to the rotation of the engine compressor, this throughflow may become swirled, altering the temperature, mass exchange, and swirl within the rotating cavity. The University of Bath Compressor Cavity Rig has been adapted to introduce preswirl into the axial throughflow by passing it through rotating holes. The effects of inlet swirl have been characterized in terms of Rossby and Reynolds numbers. Measurements of disc temperature, shroud heat flux, and unsteady pressure in the rotating frame of reference are used to quantify the effects of ingestion (entrainment) of fluid into the cavity. The unsteady dynamics and rotation of the core relative to the disc have been measured in both the stationary and rotating frames of reference with consistent results. A single correlation between shroud Nusselt and Grashof numbers has been established, effectively capturing the impact of swirl, Rossby number, and free convection
Will hope light the way? The interplay of hope, loneliness and extraversion in shaping entrepreneurs’ business exit intentions
Full text linkPurposeThe neglect of hope, a powerful yet under-researched psychological capital in entrepreneurship research, has left an obtrusive gap in understanding entrepreneurial behaviour. This study develops and tests a model showing that trait hope reduces entrepreneurs’ business exit intentions by alleviating their loneliness. It also shows how extraversion influences this relationship, highlighting when trait hope affects business exit.Design/methodology/approachWe conducted two three-wave, time-lagged surveys with entrepreneurs in Indonesia (n = 227) and the United States (US) (n = 215).FindingsOur findings reveal that entrepreneurs’ loneliness mediates the relationship between trait hope and business exit intentions in both countries. Extraversion further shapes this relationship, with stronger effects of trait hope on entrepreneurs’ loneliness and exit intentions generally observed among more extraverted entrepreneurs.Originality/valueThis research highlights trait hope as a psychologically potent yet dependent on entrepreneurs’ extraversion as an individual difference. We thereby contribute to hope research in the entrepreneurship context and the business exit literature. In addition, our study extends current research on entrepreneurs’ loneliness by identifying hope as a factor that can act as the source of “light” to combat loneliness in entrepreneurs
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