1,683 research outputs found

    A design framework for agile virtual enterprise collaboration

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    The market in which engineering companies must operate is increasingly turbulent and unpredictable, largely due to the global nature of the engineering industry in the 21st century. This turbulent environment is further exacerbated by the increasing focus on customisation for individual consumers, rather than the mass manufacturing market of the past. In order to thrive in this turbulent environment companies are increasingly focussing on their core competences, and building strategic alliances with complementary partner companies to satisfy the overall needs of an individual project. This is true of the design as well as manufacturing stages of product development. The increasing levels of collaboration and the requirement for companies to be agile in their response to unexpected events are the background to this research. Specifically, this research addressed the ability of collaborating groups of companies to respond to unexpected events during the design stages of product development. The hypothesis was that through the specific implementation of a novel collection of tools and techniques the agility of collaborative design projects can be increased. A multi-method approach was adopted for the research, beginning with an industrial survey identifying those tools and techniques from the literature which are linked to an increased level of agility. These results form the basis for the definition of the Agile Design Framework which takes the form of a series of implementation steps carried out by a collaborative design team to put in place tools and techniques for increasing their responsiveness to unexpected events. The second stage of the research tested the Agile Design Framework in a controlled laboratory environment with both an experimental and control group undertaking the same collaborative design project. Unexpected events were introduced and the responses of both groups are analysed. The experiment group using the Agile Design Framework had a Key Agility Index score of 0.04 compared with a score of 0.13 for the control group. A low score on the Key Agility Index indicates a higher level of agility while high scores tending to 1 have a lower agility level. The results supported further calibration of the Agile Design Framework for the final stage of the research which was an implementation of the framework in industry for a real-life collaborative design project. This industrial implementation showed an improvement in the agility of the collaborative design project using the Agile Design Framework, improving the Key Agility Index from 0.54 to 0.43.The research makes three novel contributions to knowledge in this field. The first is the Agile Design Framework which is a set of tools and techniques with a specific implementation process, which has been shown to increase agility for collaborative design projects. Secondly, a four-level classification scheme for unexpected events will be presented which allows categorisation of unexpected events into Trivial, Minor, Major and fatal, based on specific criteria. Finally, through the use of easily obtainable data the Key Agility Index is validated as a meaningful quantitative metric for the measurement of agility at the project or departmental level

    Discovery of a lipid synthesising organ in the auditory system of an insect

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    Weta possess typical Ensifera ears. Each ear comprises three functional parts: two equally sized tympanal membranes, an underlying system of modified tracheal chambers, and the auditory sensory organ, the crista acustica. This organ sits within an enclosed fluid-filled channel–previously presumed to be hemolymph. The role this channel plays in insect hearing is unknown. We discovered that the fluid within the channel is not actually hemolymph, but a medium composed principally of lipid from a new class. Three-dimensional imaging of this lipid channel revealed a previously undescribed tissue structure within the channel, which we refer to as the olivarius organ. Investigations into the function of the olivarius reveal de novo lipid synthesis indicating that it is producing these lipids in situ from acetate. The auditory role of this lipid channel was investigated using Laser Doppler vibrometry of the tympanal membrane, which shows that the displacement of the membrane is significantly increased when the lipid is removed from the auditory system. Neural sensitivity of the system, however, decreased upon removal of the lipid–a surprising result considering that in a typical auditory system both the mechanical and auditory sensitivity are positively correlated. These two results coupled with 3D modelling of the auditory system lead us to hypothesize a model for weta audition, relying strongly on the presence of the lipid channel. This is the first instance of lipids being associated with an auditory system outside of the Odentocete cetaceans, demonstrating convergence for the use of lipids in hearing

    Polymers and inflammation: disease mechanisms of the serpinopathies

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    Members of the serpin (serine proteinase inhibitor) superfamily play a central role in the control of inflammatory, coagulation, and fibrinolytic cascades. Point mutations that cause abnormal conformational transitions in these proteins can trigger disease. Recent work has defined three pathways by which these conformers cause tissue damage. Here, we describe how these three mechanisms can be integrated into a new model of the pathogenesis of emphysema caused by mutations in the serpin α1-antitrypsin

    Why has it been so difficult to prove the efficacy of alpha-1-antitrypsin replacement therapy? Insights from the study of disease pathogenesis

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    Alpha-1-antitrypsin is the most abundant circulating protease inhibitor. It is mainly produced by the liver and secreted into the circulation where it acts to prevent excessive proteolytic damage in the lungs by the enzyme neutrophil elastase. The most common severe deficiency allele is the Z mutation, which causes the protein to self-associate into ordered polymers. These polymers accumulate within hepatocytes to cause liver damage. The resulting lack of circulating α1-antitrypsin predisposes the Z homozygote to proteolytic lung damage and emphysema. Other pathways may also contribute to the development of lung disease. In particular, polymers of Z α1-antitrypsin can form within the lung where they act as a pro-inflammatory stimulus that may exacerbate protease-mediated lung damage. Researchers recognized in the 1980s that plasma α1-antitrypsin levels could be restored by intravenous infusions of purified human protein. Alpha-1-antitrypsin replacement therapy was introduced in 1987 but subsequent clinical trials have produced conflicting results, and to date there remains no widely accepted clinical evidence of the efficacy of α1-antitrypsin replacement therapy. This review addresses our current understanding of disease pathogenesis in α1-antitrypsin deficiency and questions why this treatment in isolation may not be effective. In particular it discusses the possible role of α1-antitrypsin polymers in exacerbating intrapulmonary inflammation and attenuating the efficacy of α1-antitrypsin replacement therapy

    The expanding house : extensions to domestic buildings and their impact on energy consumption

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    The energy impact of extensions, defined as the percentage increase in total household energy consumption caused by an extension, has been investigated and quantified. This has been achieved through a two-step process. Firstly, a set of typical extension sizes and prevalence was defined through a survey using publicly available aerial imagery and GIS mapping software. Secondly the energy impact of these extensions was predicted through the application of a reduced data Standard Assessment Procedure. A catalogue of extension types has been created and statistically significant relationships between extension prevalence and tenure, household income and building archetype have been proven. The energy impact of extensions has been estimated to be 16% on average across all building and extension types; which would account for 3.8% of England’s domestic energy demand if the results of this study were scaled nationally

    Estimation of building heat transfer coefficients from in-use data: Impacts of unmonitored energy flows

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    PurposeThe purpose of this paper is to identify the impact of traditionally unmonitored energy sources and sinks on assessment of the as-built thermal performance of occupied homes. The analysis aims to demonstrate the potential scale of uncertainties introduced in a heat balance estimation of the heat transfer coefficient (HTC) when using in-use monitored data. Design/methodology/approach Energy flows for two UK homes – one a 1930s dwelling with high heat loss, the second a higher-performing 2014-built home – are predicted using the UK Government’s standard assessment procedure (SAP) and visualised using Sankey diagrams. Selected modelled energy flows are used as inputs in a quasi-steady state heat balance to calculate in-use HTCs as if from measured data sets gathered in occupied homes. The estimated in-use HTCs are compared against SAP-calculated values to illustrate the impact of including or omitting various heat sources and sinks. Findings The results demonstrate that for dwellings with low heat loss, the increased proportion of heating demand met by unmetered internal and solar gains informs a greater sensitivity of a heat balance estimation of the HTC to their omission. While simple quasi-steady state heat balance methods may be appropriate for dwellings with very high heat loss, alternative approaches are likely to be required for those with lower heat loss. Originality/value A need to understand the impacts of unmetered heat flows on the accuracy with which a building’s thermal performance may be inferred from in-use monitored data is identified: this paper illustrates the scale of these impacts for two homes at opposite ends of the energy performance scale.</div

    Early-stage design decision-making for Community Energy Schemes

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    A model and an assessment framework have been developed to support the transition of residential districts from passive energy consumers to active prosumers linked within Community Energy Systems (CES). Three hypothetic districts form the case studies on which an assumed scenario was applied and examined for the financial, environmental and energy efficiency outcomes it achieves. The case studies consider houses of different types and thermal efficiencies. The results show a promising level of detail, enough to enhance decisionmaking during the early concept design of projects. The model and assessment framework can evaluate a range of applications including the transformation of old districts into CESs, the expansion of recently built CESs to include adjacent districts with older and usually less efficient dwellings and the designing of CESs for new housing developments
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