What is broken? Expected lifetime, perception of brokenness and attitude towards maintenance and repair

This paper addresses the discrepancy between the expected and actual lifetimes of vacuum cleaners considering perceived ‘brokenness’ as a driver for replacement. Among electrical products, vacuum cleaners have a high rate of domestic ownership in the UK. They also embody large quantities of greenhouse gases which could be reduced by increasing their longevity and resource efficiency (Schreiber et al., 2012). A focus on energy efficiency has only shown limited or even negative results, therefore to meet recent European Union regulations on durability requirements a focus on product longevity is needed. Around one half of new vacuum cleaner purchasers replace one less than 5 years old, below the expected lifespan, with perceived breakage, poor performance and unreliability as the major reasons for replacement. Their relative simplicity could allow vacuum cleaners to last for significantly longer. The nature of the common causes of failure is known, including stretched cords or blockages, and WRAP has developed guidelines for product improvements. However, many working or repairable machines are disposed of because they are perceived to be ‘irremediably’ broken

The joy of vacuuming? How the user experience affects vacuum cleaner longevity

An apparent reduction in the average lifetime of vacuum cleaners is explored in this paper in relation to their perceived usability and increasingly frequent product replacement. Motivations for product disposal combine perceived and real product failure with a perceived or real improved product offer. From an historical perspective, vacuum cleaners typify this pattern, continually offering a ‘cheaper and improved’ product. Vacuum cleaner manufacturers reinvigorate the sense of satisfaction and revulsion associated with extracting dirt from our homes through new performance focused product development. For example, increased motor power, filtration, bag-less machines and clear bin compartments have all acted as sales drivers, whilst cost effective materials and offshore and more efficient manufacturing have reduced purchase prices. The latter, cost-driven, processes can create machines that are more likely to be functionally and aesthetically damaged in use, reinforcing the trend for faster replacement. The market appears likely to continue to focus on improved user experience, with growth in market share for lighter weight cordless battery powered machines posing the risk of an increased environmental burden. Drawing from qualitative and quantitative research undertaken for a study for Defra, we explore the user’s relationship to the product, investigating the frustrations and joys of vacuum cleaner use and ownership. The findings illustrate that the revulsion and attraction of cleaning, as well as the tedium and satisfaction fostered by the product, have direct implications for vacuum cleaner longevity

The relationship between ideas about cleanliness and actions that affect product longevity

As Mary Douglas famously put it, ‘where there is dirt there is system’ (1991 (1966): 35). She was concerned particularly with the cultural systems that determine the ideas about dirt that motivate and constrain people’s actions with material objects. This paper assumes that such motivations and constraints may affect consumers’ willingness to keep or to dispose of their possessions, and therefore have an impact on product longevity. It reports on ongoing empirical research using product analysis, ethnographic interviews, a questionnaire and student design work into the possibility of increasing the longevity of vacuum cleaners by design interventions. Because its object of study is a cleaning product used in everyday cleaning practices, the research naturally connects with Douglas’ ideas as well as more recent work such as Dant 2003 that focuses on how people deal practically with the materiality of dirt, not determined by cultural categories. This paper builds on Vaussard et al.’s (2014) classification of individuals by their degree of concern for keeping their house clean, into ‘Spartan’, ‘Minimalistic’, ‘Caring’ and ‘Committed’ cleaners and their implications for vacuum cleaner replacement. Introducing a short history of concern about dirt since germ theory, it considers whether the desire for a more up to date/efficient/powerful/good looking/clean/shiny machine may accelerate replacement. It finally considers whether a design that ‘ages gracefully’ might have a longer life-span, either as a personal possession or as part of a service system

Autonomous resource-aware scheduling of large-scale media workflows

The media processing and distribution industry generally requires considerable resources to be able to execute the various tasks and workflows that constitute their business processes. The latter processes are often tied to critical constraints such as strict deadlines. A key issue herein is how to efficiently use the available computational, storage and network resources to be able to cope with the high work load. Optimizing resource usage is not only vital to scalability, but also to the level of QoS (e.g. responsiveness or prioritization) that can be provided. We designed an autonomous platform for scheduling and workflow-to-resource assignment, taking into account the different requirements and constraints. This paper presents the workflow scheduling algorithms, which consider the state and characteristics of the resources (computational, network and storage). The performance of these algorithms is presented in detail in the context of a European media processing and distribution use-case

The discovery of a low mass, pre-main-sequence stellar association around gamma Velorum

We report the serendipitous discovery of a population of low mass, pre-main sequence stars (PMS) in the direction of the Wolf-Rayet/O-star binary system gamma^{2} Vel and the Vela OB2 association. We argue that gamma^{2} Vel and the low mass stars are truly associated, are approximately coeval and that both are at distances between 360-490 pc, disagreeing at the 2 sigma level with the recent Hipparcos parallax of gamma^{2} Vel, but consistent with older distance estimates. Our results clearly have implications for the physical parameters of the gamma^{2} Vel system, but also offer an exciting opportunity to investigate the influence of high mass stars on the mass function and circumstellar disc lifetimes of their lower mass PMS siblings.Comment: Monthly Notices of the Royal Astronomical Society, Letters - in pres

Boundary condition at the junction

The quantum graph plays the role of a solvable model for a two-dimensional network. Here fitting parameters of the quantum graph for modelling the junction is discussed, using previous results of the second author.Comment: Replaces unpublished draft on related researc

Human engineering design criteria study Final report

Human engineering design criteria for use in designing earth launch vehicle systems and equipmen

A Preliminary Discussion of the Kinematics of BHB and RR Lyrae Stars near the North Galactic Pole

The radial velocity dispersion of 67 RR Lyrae variable and blue horizontal branch (BHB) stars that are more than 4 kpc above the galactic plane at the North Galactic Pole is 110 km/sec and shows no trend with Z (the height above the galactic plane). Nine stars with Z < 4 kpc show a smaller velocity dispersion (40 +/-9 km/sec) as is to be expected if they mostly belong to a population with a flatter distribution. Both RR Lyrae stars and BHB stars show evidence of stream motion; the most significant is in fields RR2 and RR3 where 24 stars in the range 4.0 < Z < 11.0 kpc have a mean radial velocity of -59 +/- 16 km/sec. Three halo stars in field RR 2 appear to be part of a moving group with a common radial velocity of -90 km/sec. The streaming phenomenon therefore occurs over a range of spatial scales. The BHB and RR Lyrae stars in our sample both have a similar range of metallicity (-1.2 < [Fe/H] < -2.2). Proper motions of BHB stars in fields SA 57 (NGP) and the Anticenter field (RR 7) (both of which lie close to the meridional plane of the Galaxy) show that the stars that have Z 4 kpc have a Galactic V motion that is < -200 km/sec and which is characteristic of the halo. Thus the stars that have a flatter distribution are really halo stars and not members of the metal-weak thick-disk.Comment: Accepted for publication in the March 1996 AJ. 15 pages, AASTeX V4.0 latex format (including figures), 2 eps figures, 2 separate AASTeX V4.0 latex table

Non-Weyl asymptotics for quantum graphs with general coupling conditions

Inspired by a recent result of Davies and Pushnitski, we study resonance asymptotics of quantum graphs with general coupling conditions at the vertices. We derive a criterion for the asymptotics to be of a non-Weyl character. We show that for balanced vertices with permutation-invariant couplings the asymptotics is non-Weyl only in case of Kirchhoff or anti-Kirchhoff conditions, while for graphs without permutation numerous examples of non-Weyl behaviour can be constructed. Furthermore, we present an insight helping to understand what makes the Kirchhoff/anti-Kirchhoff coupling particular from the resonance point of view. Finally, we demonstrate a generalization to quantum graphs with nonequal edge weights.Comment: minor changes, to appear in Pierre Duclos memorial issue of J. Phys. A: Math. Theo