16 resultados para Whole-life costing
em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast
Resumo:
In recent years, there has been growing emphasis on the need to provide transparency in the costs of engineering programmes, leading to growing emphasis on Whole Life Cost (WLC) modelling techniques. This has arisen largely due to the increased interested in longer timescale projects and programmes, combined with the emergence of system-of-systems and network enabled capability concepts. This change in the implementation and management of large scale projects has necessitated the development of alternative methods of evaluating performance. This work seeks to address the shortfalls in current costing methodologies when applied to these highly flexible environments, and to propose a conceptual model for dealing with the encountered complexities. The approach has a fundamental role and potential significance in the future of whole life costing for Network Enabled Capability (NEC) but can also offer a potential paradigm shift for costing in traditional engineering environments.
Resumo:
Fibre-Reinforced Plastics (FRPs) have been used in civil aerospace vehicles for decades. The current state-of-the-art in airframe design and manufacture results in approximately half the airframe mass attributable to FRP materials. The continual increase in the use of FRP materials over metallic alloys is attributable to the material's superior specific strength and stiffness, fatigue performance and corrosion resistance. However, the full potential of these materials has yet to be exploited as analysis methods to predict physical failure with equal accuracy and robustness are not yet available. The result is a conservative approach to design, but one that can bring benefit via increased inspection intervals and reduced cost over the vehicle life. The challenge is that the methods used in practice are based on empirical tests and real relationships and drivers are difficult to see in this complex process and so the trade-off decision is challenging and uncertain. The aim of this feasibility study was to scope a viable process which could help develop some rules and relationships based on the fundamental mechanics of composite material and the economics of production and operation, which would enhance understanding of the role and impact of design allowables across the life of a composite structure.
Resumo:
The use of carbon fibre composites is growing in many sectors but their use remains stronger in very high value industries such as aerospace where the demands of the application more easily justify the high energy input needed and the corresponding costs incurred. This energy and cost input is returned through gains over the whole life of the product, with for example, longer maintenance intervals for an aircraft and lower fuel burn. Thermoplastic composites however have a different energy and cost profile compared to traditional thermosets with notable differences in recyclability, but this profile is not well quantified or documented. This study considers the key process control parameters and identifies an optimal window for processing, along with the effect this has on the final characteristics of the manufactured parts. Interactions between parameters and corresponding sensitivities are extracted from the results.
Resumo:
Increasing energy consumption has exerted great pressure on natural resources; this has led to a move towards sustainable energy resources to improve security of supply and to reduce greenhouse gas emissions. However, the rush to the cure may have been made in haste. Biofuels in particular, have a bad press both in terms of competition with good agricultural land for food, and also in terms of the associated energy balance with the whole life cycle analysis of the biofuel system. The emphasis is now very much on sustainable biofuel production; biofuels from wastes and lignocellulosic material are now seen as good sustainable biofuels that affect significantly better greenhouse gas balances as compared with first generation biofuels. Ireland has a significant resource of organic waste that could be a potential source of energy through anaerobic digestion. Ireland has 8% of the cattle population of the EU with less than 1% of the human population; as a result 91% of agricultural land in Ireland is under grass. Residues such as slurries and slaughter waste together with energy crops such as grass have an excellent potential to produce biogas that may be upgraded to biomethane. This biomethane may be used as a natural gas substitute; bio-compressed natural gas may then be an avenue for a biofuel strategy. It is estimated that a maximum potential of 33% of natural gas may be substituted by 2020 with a practical obtainable level of 7.5% estimated. Together with biodiesel from residues the practical obtainable level of this strategy may effect greater than a 5% substitution by energy of transport. The residues considered in this strategy to produce biofuel (excluding grass) have the potential to save 93,000 ha of agricultural land (23% of Irish arable land) when compared to a rapeseed biodiesel strategy. © 2009 Elsevier Ltd. All rights reserved.
Resumo:
Abstract. Modern business practices in engineering are increasingly turning to post manufacture service provision in an attempt to generate additional revenue streams and ensure commercial sustainability. Maintainability has always been a consideration during the design process but in the past it has been generally considered to be of tertiary importance behind manufacturability and primary product function in terms of design priorities. The need to draw whole life considerations into concurrent engineering (CE) practice has encouraged companies to address issues such as maintenance, earlier in the design process giving equal importance to all aspects of the product lifecycle. The consideration of design for maintainability (DFM) early in the design process has the potential to significantly reduce maintenance costs, and improve overall running efficiencies as well as safety levels. However a lack of simulation tools still hinders the adaptation of CE to include practical elements of design and therefore further research is required to develop methods by which ‘hands on’ activities such as maintenance can be fully assessed and optimised as concepts develop. Virtual Reality (VR) has the potential to address this issue but the application of these traditionally high cost systems can require complex infrastructure and their use has typically focused on aesthetic aspects of mature designs. This paper examines the application of cost effective VR technology to the rapid assessment of aircraft interior inspection during conceptual design. It focuses on the integration of VR hardware with a typical desktop engineering system and examines the challenges with data transfer, graphics quality and the development of practical user functions within the VR environment. Conclusions drawn to date indicate that the system has the potential to improve maintenance planning through the provision of a usable environment for inspection which is available as soon as preliminary structural models are generated as part of the conceptual design process. Challenges still exist in the efficient transfer of data between the CAD and VR environments as well as the quantification of any benefits that result from the proposed approach. The result of this research will help to improve product maintainability, reduce product development cycle times and lower maintenance costs.
Resumo:
The recent judgment of the Grand Chamber of the European Court of Human Rights (ECtHR) in Vinter and others v United Kingdom provides a much needed clarification of the parameters of the prohibition on inhuman and degrading punishment under Article 3 of the European Convention on Human Rights (ECHR) as it applies to whole life orders of imprisonment under mandatory life sentences – essentially, life imprisonment without parole. The Grand Chamber’s judgment refines Strasbourg doctrine on life imprisonment and the prospect of release and illuminates key principles concerning inhuman and degrading punishment under Article 3 of the ECHR. This article considers the judgment’s profound significance in relation to both human rights and penology.
Resumo:
The increasing need to understand complex products and systems with long life spans, presents a significant challenge to designers who increasingly require a broader understanding of the operational aspects of the system. This demands an evolution in current design practice, as designers are often constrained to provide a subsystem solution without full knowledge of the global system operation. Recently there has been a push to consider value centric approaches which should facilitate better or more rapid convergence to design solutions with predictable completion schedules. Value Driven Design is one such approach, in which value is used as the system top level objective function. This provides a broader view of the system and enables all sub-systems and components to be designed with a view to the effect on project value. It also has the capacity to include value expressions for more qualitative aspects, such as environmental impact. However, application of the method to date has been restricted to comparing value in a programme where the lifespan is fixed and known a priori. This paper takes a novel view of value driven design through the surplus value objective function, and shows how it can be used to identify key sensitivities to guide designers in design trade-off decisions. By considering a new time based approach it can be used to identify optimum programme life-span and hence allow trade-offs over the whole product life.
Resumo:
1. We collated information from the literature on life history traits of the roach (a generalist freshwater fish), and analysed variation in absolute fecundity, von Bertalanffy parameters, and reproductive lifespan in relation to latitude, using both linear and non-linear regression models. We hypothesized that because most life history traits are dependent on growth rate, and growth rate is non-linearly related with temperature, it was likely that when analysed over the whole distribution range of roach, variation in key life history traits would show non-linear patterns with latitude.
Resumo:
Enumeration of various lymphocyte subsets is used widely in the diagnosis and monitoring of various disease states. With the development of flow cytometric technology and whole blood analysis, methodologies have become more sensitive. It is therefore important to establish reference intervals in normal, healthy individuals using these techniques to give a better indication of the border between health and disease. Since some lymphocyte subpopulations are known to change with age, we have enumerated common subsets in healthy individuals from all decades of adult life, including nonagenarian subjects. We report reference intervals for these subsets in each age group, which will be of use in diagnosis and disease monitoring, particularly in elderly subjects, the most rapidly expanding group within the population today.
Resumo:
OBJECTIVE: The purpose of this study is to examine the perspectives of both the spousal caregiver and care recipient on the caregiving experience in home-based palliative care. METHODS: A qualitative research strategy involving home-based face-to-face interviews with older palliative care patients and their spousal caregivers was used to examine the caregiving experience. RESULTS: Ten spousal caregivers and care recipient dyads participated in the study. Most informal caregivers viewed caregiving as an extension of the family relationship where caregiving responsibilities evolved over time. Spousal caregivers identified many negative reactions to caregiving, such as fatigue or weariness, depression, anger and sadness, financial stresses, and lack of time. Care recipients acknowledged the emotional and financial strain and expressed concern for their spouses. Both caregivers and care recipients were appreciative of home care services although they identified the need for additional services. They also identified difficulties in communication with formal providers and poor coordination of care among the various services. Both caregivers and care recipients disclosed some challenges with informal supports, but on the whole felt that their presence was positive. Additional positive aspects of caregiving reported by spouses included strengthened relationship with their spouse and discovering emotional strength and physical abilities in managing care. SIGNIFICANCE OF RESULTS: Health care and social service professionals need to recognize and understand both caregiver and care recipient perspectives if they are to successfully meet the needs of both members of the dyad.