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Effect of the irradiation intensity on the photo-thermal conversion performance of composite phase change materials : an experimental approach
No full textComposite phase change materials (CPCM) containing photo absorbers are regarded as promising conversion and thermal energy storage materials for solar energy. Understanding the impact of irradiation intensity on the photo-thermal conversion process is of crucial significance for improving the photo-thermal conversion efficiency (PTCE) of CPCM. However, previous studies have overlooked the evolution of temperature patterns and the solid-liquid phase interface in CPCM, posing challenges in revealing photo-thermal conversion characteristics. In response to these challenges, the present study introduces an improved test method that integrates monitoring plane and infrared thermography. Paraffin/graphite nanoparticles CPCM are used as conversion and thermal storage material. The results show that the dominated heat transfer mode in different stages is different, and the natural convection within the liquid CPCM has enhanced the melting process. When the irradiation intensity is increased from 450 W/m2 to 1250 W/m2, the average temperature and average charging rate increase by 33.75% and 197.27%, respectively. At an irradiation intensity of 1050 W/m2, the CPCM achieves the highest overall PTCE of 42.40%, which is an 8.85% increase in contrast to the irradiation intensity of 450 W/m2. The results provide guidance for improving the PTCE of CPCM in the application of direct absorption solar collectors
Sustainability across the medical device lifecycle : a scoping review
Get PDFMedical devices are instrumental in servicing the healthcare sector and promoting well-being in modern societies. However, their production and use contribute significantly to greenhouse gas emissions, thus causing indirect harm to global health. With a share of approximately 4.4% of global emissions, the healthcare sector exhales CO2 throughout its value chain; sources of this range from direct electricity consumption and water heating in healthcare facilities to the supply chains delivering healthcare services and products. Within this context, the environmental impact of medical devices is present across their production, distribution, usage, and eventual disposal. Each step in the lifecycle of medical devices consumes energy and natural resources, and the end product, after its often single use, is discarded, generating plastic or electronic waste. This study aims to present the key findings from a scoping review of academic research on the topic, which focuses on reducing the environmental impact of medical devices and equipment. The review, conducted according to the PRISMA checklist for scoping reviews, examined 41 studies and categorised them based on the lifecycle stages of medical devices (design and development, manufacturing, usage, and end of life) and the sustainability aspects (economic, environmental, and social) discussed by the authors. The findings suggest that while efforts have been made to enhance economic and environmental sustainability throughout the design, development, and usage of medical devices, there is still room for improvement in mitigating their ecological impact at the end of their lifecycle and maximising their social impact by design
Thermo-oxidative degradation behavior of natural rubber vulcanized by different curing systems
No full textIn this work, the effects of three types of curing systems: conventional vulcanization (CV), semi-efficient vulcanization (SEV) and efficient vulcanization (EV) on the degradation efficiency of sulfur cured natural rubber (NR) were investigated. NR vulcanizates were prepared and degraded at 210 °C in air for different periods of time. The sol fraction, molecular weight, element contents and degradation kinetics were studied in detail. The degradation efficiency of the NR vulcanizates was decreased in the order of CV, SEV and EV cured NR, which was caused by the lower crosslink density, apparent activation energy and bond dissociation energy of polysulfide bonds formed in the NR vulcanizates with CV, as compared to others. The results of Horikx theory and contents of carbonyl and sulfone group in degraded rubber indicated both sulfide scission and main chain scission occurred in the NR vulcanizates prepared with CV and SEV. Both the type of sulfidic crosslinks and crosslink density affect the degradative efficiency and products. The type of sulfidic crosslinks was the main factor affecting the degradation degree of NR vulcanizates, while the crosslink density mainly influenced the sol molecular weight of the degraded products. Moreover, the degradation mechanism of the three types of NR vulcanizates was proposed. This work demonstrated that the thermo-oxidative degradation efficiency of vulcanized rubber is affected by curing systems, which may provide guidance for upcycling waste rubber effectively
Clearing the fog : a scoping literature review on the ethical issues surrounding artificial intelligence-based medical devices
Get PDFThe use of AI in healthcare has sparked much debate among philosophers, ethicists, regulators and policymakers who raised concerns about the implications of such technologies. The presented scoping review captures the progression of the ethical and legal debate and the proposed ethical frameworks available concerning the use of AI-based medical technologies, capturing key themes across a wide range of medical contexts. The ethical dimensions are synthesised in order to produce a coherent ethical framework for AI-based medical technologies, highlighting how transparency, accountability, confidentiality, autonomy, trust and fairness are the top six recurrent ethical issues. The literature also highlighted how it is essential to increase ethical awareness through interdisciplinary research, such that researchers, AI developers and regulators have the necessary education/competence or networks and tools to ensure proper consideration of ethical matters in the conception and design of new AI technologies and their norms. Interdisciplinarity throughout research, regulation and implementation will help ensure AI-based medical devices are ethical, clinically effective and safe. Achieving these goals will facilitate successful translation of AI into healthcare systems, which currently is lagging behind other sectors, to ensure timely achievement of health benefits to patients and the public
Probing the local thermal conductivity of single- and multidomain ferroelastic variants of BiFeO3 by Raman thermometry
No full textOn the curvilinear effect of suspicion on consumer judgement suspension : the role of uncertainty towards the brand and product imagery
Get PDFWhen exposed to advertisements, consumers are often suspicious of brand claims. To that end, prior research has explored how individuals evaluate claims to form a judgement under a state of suspicion. Yet, consumer research has not examined how suspicion affects consumers' suspension of their judgement towards the brand. We experimentally investigate the effects of three (low vs. moderate vs. high) levels of consumer suspicion on judgement suspension. Study 1 shows that compared with low or high levels, moderate levels of suspicion lead to significantly higher judgement suspension. Studies 2 and 3 replicate this inverted U-shaped effect for additional brand and product category contexts and unveil that uncertainty towards the brand mediates the effect of suspicion on judgement suspension. In turn, the impact of uncertainty towards the brand on judgement suspension is mediated by product imagery. This research corroborates the effects of suspicion on consumer judgement suspension
Demonstrating software reliability using possibly correlated tests : Insights from a conservative Bayesian approach
No full textThis paper presents Bayesian techniques for conservative claims about software reliability, particularly when evidence suggests the software's executions are not statistically independent. We formalise informal notions of “doubting” that the executions are independent, and incorporate such doubts into reliability assessments. We develop techniques that reveal the extent to which independence assumptions can undermine conservatism in assessments, and identify conditions under which this impact is not significant. These techniques – novel extensions of conservative Bayesian inference (CBI) approaches – give conservative confidence bounds on the software's failure probability per execution. With illustrations in two application areas – nuclear power-plant safety and autonomous vehicle (AV) safety – our analyses reveals: (1) the confidence an assessor should possess before subjecting a system to operational testing. Otherwise, such testing is futile – favourable operational testing evidence will eventually decrease one's confidence in the system being sufficiently reliable; (2) the independence assumption supports conservative claims sometimes; (3) in some scenarios, observing a system operate without failure gives less confidence in the system than if some failures had been observed; (4) building confidence in a system is very sensitive to failures – each additional failure means significantly more operational testing is required, in order to support a reliability claim
Making predictions based on data : holistic and atomistic procedures
No full textSubjects were asked to predict the choice made by a hypothetical individual, based on a small sample of his past choices in identical situations. Each of the alternatives facing the individual has a number of components. When the data is presented explicitly as a distribution of past choices, most subjects use the holistic procedure according to which the prediction is the most common choice made in the past. Nevertheless, a significant minority of subjects use atomistic procedures, which relate to the various components individually. When the distribution is not explicitly presented but can be derived from the data, subjects apply both atomistic procedures and holistic rules of thumb