Cryogenic cyclic aging effect on thermal, mechanical and tribological performance of PEEK-based materials [Elektronisk resurs]

The impact of cryogenic cyclic aging on the thermal, mechanical, and tribological properties of polyetheretherketone (PEEK) and its composites was investigated to reveal the mechanisms and factors affecting the durability of high-performance materials under prolonged exposure to extreme environments. Cryogenic cyclic aging involved twelve cycles, each consisting of 6-day aging in liquid nitrogen (−196 °C) and 1-day in oven at 40 °C in normal ambient (relative humidity ∼30 %), mimicking operational conditions of cryogenic systems. Tribological tests were conducted using a ball-on-disk configuration with a stainless steel (SS 316L) ball counterface. Tests were performed at 25 °C in air and high vacuum (10⁻⁵ Pa). The thermal stability of the materials was slightly affected. Thermal stresses developed during aging led to polymer embrittlement. Fracture toughness decreased by approximately 22 % after cyclic aging. Abrasive wear increased significantly for unreinforced PEEK, while PEEK composites showed a rise in adhesive wear with prolonged aging. In air, the wear rate increase reached 510 %, whereas in vacuum, some compositions exhibited a wear rate reduction of up to 56 %.</p

Impact of cryogenic aging and test-environment on mechanical properties and tribological performance of PI-based materials [Elektronisk resurs]

This study investigates the effect of test-environment, temperature, and cryogenic aging in liquid nitrogen for 5 months on mechanical and tribological performance of polyimide (PI) and PI composites. Tribological tests were conducted at 25 °C in air, and at both 25 °C and −100 °C in a high vacuum (10-5 Pa) environment. Impact of cryogenic aging, testing condition on PI-based materials varied depending on the polymer structure and composition. Cryogenic aging led to embrittlement, increasing the coefficient of friction and wear rate up to 77 % and 165 %, respectively. Some polyimides exhibited the lowest coefficient of friction (0.04) in vacuum at 25 °C, while the temperature reduction to −100 oC in vacuum generally decreased the tribological performance, increased contact stresses and abrasive wear of the materials.</p

Innovative CO₂ capture technologies: Exploring the potential of porous liquids containing deep eutectic solvents and hypercrosslinked polymers [Elektronisk resurs]

The current study presented a porous liquid (PL) prepared from propylene glycol-based deep eutectic solvent (DES) and hyper-crosslinked polymers (HCP) that are liquids over wide temperature ranges, including ambient temperature. It was shown that the solvent molecules are too large to penetrate the pores of HCP, so the PL is maintained as a suspension with permanent free volume for several months and can absorb large amounts of gases. This study marks the pioneering use of DESs as the liquid medium, replacing ionic liquids due to their closely matched properties. The structural features of both DES and HCP are retained; the increase in CO2 absorption capacity compared to pure DES is due to the presence of a porous solid and is proportional to the amount of solid. The absorbed CO2 amount rises from 1.0105 mmol·g−1 in pure DES to 1.3232, 1.6027, and 1.2168 mmol·g−1 in PL-1, PL-2, and PL-3, respectively. Thermodynamic analysis revealed that the enthalpy of gas absorption allows straightforward regeneration of the PLs in the studied cases. The investigated PLs show great potential as gas absorbents, with the incorporation of just 0.5 wt% of porous polymer material leading to an impressive increase in solvent absorption capacity, up to 59 %.</p

Middle-range theorising supporting and supported by action research: focusing on practitioner preparedness [Elektronisk resurs]

Increased demand for actionable knowledge in operations- and supply chain management has fuelled the interest in collaborative, action-oriented research design as well as modes of theorising that generate adaptable and actionable frameworks. Whilst action research (AR) design as well as middle-range theories (MRT) offer guiding principles herein, they are researcher centric in nature. It is taken for granted that practitioners that enter such an endeavour have a certain level of knowledge or experience prior to the initial stages of formalising the research problem. Practitioners in non-academic, operations management-intensive industries or craftsmanship-based industries, such as construction or carpeting (often in the SME range) are often neither prepared nor equipped with the principles necessary to convey their managerial challenges into collaborative research design. This risk limiting or even hindering altogether such participation. This paper elaborates on combining the logic of AR and MRT. By conceptualising a preparatory phase for initiating practitioner engagement, complementing the conventional AR cycle, a four-step approach is presented: (1) Identifying a joint interest; (2) Teaching – Awakening interest in the topic through MRT frameworks; (3) Accepting buy-in to the AR cycle and determining the problem; and (4) Proposing MRT frameworks for analysis and entering the traditional AR cycle

Securitising information in European borders : how can democracies balance openness with curtailing Russian maligninformation influence?

The EU views malign information influence (MII) as a threat, and this has been enhanced with the Russian invasion of Ukraine resulting in a ban on several Russian media. This article adds to research on the dilemmas of democracies in combatting MII, by consulting the public on whether the ban was a proportionate and effective measure and if it stained the EU’s moral authority. Combining focus groups with a survey of the Swedish population, we found robust support for the ban – slightly stronger among women and increasing with age – and little backlash towards the EU. Respondents supported active countermeasures yet recognised problems with curtailing the free flow of information. The results indicate a need for refinement of an ideal-type model of countermeasures to MII (Hellman and Wagnsson Citation2017). We suggest a new category – “fortifying” – that highlights shared state/individual responsibility and the strengthening of citizens, authorities and the media. We conclude by suggesting a need for additional research on how to balance values of freedom and security and whether public support of bans relies on the precarious geopolitical situation resulting from the Russian invasion of Ukraine or if securitisation of information is an enduring trend.</p

Psychological Coaching for Performing Artists [Elektronisk resurs] : Perceptions of and Reflections on Finding Ways to Manage Performance Anxiety

Performance anxiety is a major issue for performing artists. This qualitative paper extends our recent mixed-methods collective case study showing the beneficial effects of psychological interventions for managing performance anxiety, tailored in individual coaching settings. Here, we report on participants’ experiences of being coached, their understanding of how and why the interventions were effective, and the researcher-coach's experiences. Ten performing artists received five individual coaching sessions and were interviewed about their experiences pre- and post-intervention. A qualitative synthesis of transcripts of sessions and interviews, and of the coach's field notes and journal entries, was conducted. Findings suggest that change mechanisms have to be understood in the context of participants’ enhanced self-awareness during coaching, and the process of co-creating solutions and building a coaching relationship through mutual understanding and appreciation. While disentangling mechanisms and effects may not always be possible, we discuss useful strategies in coaching performing artists to manage performance anxiety. </p

Facilitating co-design among older adults in a digital setting : methodological challenges and opportunities

Healthy ageing is a global priority due to a growing older population, which increases the need for preventive measures and tailored technology. In health technology development, co-design is emphasised as a valuable strategy to support a person-centred approach. Co-design, a value-driven and collaborative approach, involves end users in development processes to overcome barriers connected to capability, opportunity, and motivation. While a growing number of older adults are involved in design processes, there is a deficit of suitable methodologies for achieving active involvement. Additionally, the COVID-19 pandemic necessitated a shift to developing methodological skills and tools to facilitate co-design remotely in a digital setting. Here, we draw on experiences of conducting iterative co-design workshops with a Canadian and a Swedish cohort of older adults about technology development to support mobility, balance, and confidence in daily movement. We describe and discuss methodological and ethical challenges and opportunities to provide recommendations for conducting co-design research in a digital setting with older adults (+65 years). Our recommendations include the use of live mind mapping to facilitate participation involvement, and we address the issue of 'homework' in co-design and the importance of setting expectations.</p

Imagining novel colours

Some philosophers, most notably David Hume, think that you can imagine colours that you’ve never seen before. Other philosophers, among them David Lewis, L.A. Paul, and Hume again, think that you can’t imagine sensory qualities that lie outwith your past experience. An easy way to reconcile these views is to say that you can imagine colours and other qualities sufficiently similar to those you’ve experienced before: a missing shade of blue, but not totally novel properties. Hence the widespread intuition that someone raised in a monochrome environment could not imagine colours. However, this reconciliation merely raises the questions of why, and how, past experience can facilitate some imaginings and not others. Through consideration of hallucinations, imprisoned colour scientists, flavour design, and the Wagner tuba, this chapter argues against the view that past experience furnishes qualitative material for imaginative blending, and in favour of the Lewisian view that past experience develops the know-how required to imaginatively blend: put somewhat abstractly, it develops the ability to conceive of the experiential space within which novel qualitative appearances might be manifested. The chapter ends by considering extensions of this view from imaginings of novel sensory properties to imaginings of novel sensory and qualitative experiences in the broadest sense. </p

Beyond conventional leadership [Elektronisk resurs] : on Homo academicus (dux) and ontological assumptions in academia

With the premise that ontological assumptions about Homo academicus and Homo academicus dux (the academic leader) must include knowledge and analysis of the organisational context where they act, this chapter sets out to challenge some common (and we argue incorrect) assumptions in contemporary management literature regarding how power is distributed, the role of dependencies among units and practices, and how a sense of belonging is formed. Three (alternative) conditions are introduced—reversed hierarchy, lateral independence, and community-based belonging—upon which academic practice and leadership implications are discussed. The alternative conditions thus explain why and how Homo academicus and Homo academicus dux acts the way (s)he acts, which consequently makes out the contours of a new academic rationality.</p

Using remote sensing data to derive built-form indexes to analyze the geography of residential burglary and street thefts [Elektronisk resurs]

By deploying remotely sensed data together with spatial statistical modeling, we use regression modeling to investigate the relationship between the density of the built environment and two types of crime. We show how the Global Human Settlement Layer (GHSL) data set, which is a measure of building density generated from Sentinel 2A satellite imagery, can be used to create different indexes to describe the built environment for the purpose of analyzing crime patterns for indoor crimes (residential burglary) and open space crimes (street theft). Analysis is at neighborhood level for Stockholm, Sweden. Modeling is then extended to incorporate six planning areas which represent different neighborhood types within the city. Modeling is further extended by adding selected social, economic, demographic and land use variables that have been found to be significant in explaining spatial variation in the two crime categories in Stockholm. Significant associations between the GHSL-based indexes and the two crime rates are observed but results indicate that allowance for differences in neighborhood type should be recognized. Average income and transport hubs were also significant variables in the investigated crime categories. The article provides a practical demonstration and assessment of the use of high-resolution satellite data to examine the association between urban density and two common types of crime and offers reflections about the use of satellite image data in crime analysis.</p