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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Educating engineers for a holistic approach to fire safety

Woodrow, Michael January 2013 (has links)
Problems can be solved using existing knowledge and methods derived from past experiences; and in building design, where buildings are sufficiently similar to those already built, this process can be optimised by creating standardised solutions to common problems. There is significant demand for specialist engineers who can apply these standardised solutions to established problems quickly and accurately; but novel designs generate entirely new problems for which established solutions are not always applicable. Generalist engineers working on novel designs must first define the problems before they can develop options and if necessary, create optimised solutions. Fire safety engineering (FSE) is the process of achieving fire safety in our built environment. The field requires both specialists trained in current practice and generalists skilled in creative and critical thinking. Current fire safety engineering education is mostly aimed at producing specialists, yet there is growing demand for generalists in high-end architecture, hindered by a lack of generalist education. Current education literature in FSE explains in detail what to teach, however they do not explain how to motivate students to learn what is taught; how to create the ‘need to know’ - the purpose that drives learning. The purpose can either be intrinsically motivating (i.e. the subject is interesting) or extrinsically motivating (i.e. if you don’t learn it then you will fail the exam). The former is sustained by autonomy and choice; the latter is sustained by control. Control increases the likelihood that the predicted outcome will be realised, but by definition reduces the likelihood of realising any other outcome, including potential innovation.Initially a study was created to test the effects of creating an autonomous learning environment within a traditional lecture-based ‘fundamentals’ course at the University of Edinburgh. This study, along with observations at a range of US universities led to the formation of an overarching theory of education. Ultimately, purpose is the goal students strive to achieve; autonomy creates the opportunity to think and learn independently; and structure provides the constraints that converge students towards an optimised result, supported by sound evidence and reasoning. Thus the key to generalist education was to provide purpose, autonomy and structure (PAS) in that order. The PAS concept was trialled at EPFL (Switzerland) and the participating students, with no prior knowledge of fire engineering, produced work of exceptional quality. In summary, the present study offers an observational validation that Purpose, Autonomy & Structure (PAS) can be used to effectively support the generalist way of thinking and although the examples given in this paper are related to fire safety engineering (due to the need for generalists in that field), the qualitative evidence on which the conclusions are based is not subject-specific, implying that the PAS methodology could be applied to other disciplines.
2

Assessment of the thermal efficiency, structure and fire resistance of lightweight building systems for optimized design

Amundarain, Aitor January 2007 (has links)
The use of lightweight building systems is very controversial as existing knowledge about their performance is limited. Not enough research has been conducted to determine the suitability of these modern construction technologies and there is an ongoing controversy as to whether they are an appropriate replacement to traditional construction techniques. The prime objective of this study is to present a number of methodologies to assess lightweight external walling systems focusing on thermal efficiency, structure and fire performance, which are currently the main driving forces for this industry. Traditionally, these areas have been studied separately but there is a need to integrate them in order to get comprehensive solutions to the way these systems are designed. The drive to achieve improvements in one of these specific areas could potentially result in reduced effectiveness in the others. That is the reason why an integrative approach is recommended. These techniques are meant to be applied in the design phase of building projects so as to provide early quantitative information about the systems analyzed. The methodologies described herein are then applied to real life light steel building solutions. Within this context, two different wall constructions are examined and conclusions made on their relative performance. The study highlights the importance of having analytical and experimental solutions as a framework for further development. Two different approaches have been considered to assess thermal efficiency, structure and fire performance. On the one hand, a prescriptive approach has been employed to establish regulation compliance. On the other hand, a performance based approach is taken to actually understand and explain how these systems work in real life conditions. The outcome is a comprehensive set of tools to assure both industry and other stake holders.
3

An experimental evaluation of the impact of ventilation opening geometry on enclosure fire severity

Lennon, Patrick January 2002 (has links)
No description available.
4

Two-phase flows accompanying fires in enclosures

Kenyon, Yvonne Michelle January 2003 (has links)
The dispersed phase that accompanies enclosure fires, for example, soot, ash, sprinkler droplets and extinguishing powder, could exert a significant influence on the dynamics of the background fluid. In this thesis, the results of a numerical study into the effects of this dispersed phase on the flow in a fire compartment are presented. A two-dimensional computational fluid dynamics solver, with appropriate approximations for low Mach number flows and mathematical sub-models for two­phase flows, has been developed in order to simulate fire induced convective motions in planar compartments. The description of the dispersed particulate is based on a two­continuum approach, whereby the dispersed phase and the gaseous phase are assumed to be two mutually interacting and penetrating continua. In this thesis, two 'passive' models and an 'active' model of the dispersed phase are considered. In the passive models the particulate acts as a tracer only and has no hydrodynamical influence on the gas phase. The second passive model differs from the first in that the production of gases in the fire compartment, for example arising from combustion or propellant gases due to extinguishment of the fire, is taken into account. This second passive model more accurately predicts the growth of pressure in a sealed fire compartment for weak fires. As the volume fraction of the particulate increases the spatial-temporal hydrodynamic influence exerted on the gaseous flow by the dispersed phase becomes significant and, under certain conditions, a passive representation is insufficient. An active one­temperature and one-velocity model is proposed which is appropriate for the description of a hydrodynamically active particulate with an instantaneous velocity and thermal relaxation time. In this thesis, computational fluid dynamics is used as a tool in order to characterise the applicability of the passive models and the active model. The ability of the passive models to accurately predict the growth of pressure in a compartment for 'surface' fires, for example smouldering combustion and weak fires, is investigated. The active model is used to study the hydrodynamics of powder extinguishing media in a compartment with an open doorway.
5

Performance-based methodology for the fire safe design of insulation materials in energy efficient buildings

Hidalgo-Medina, Juan P. January 2015 (has links)
This thesis presents a methodology to determine failure criteria of building insulation materials in the event of a fire that is specific to each typology of insulation material used. This methodology is based on material characterisation and assessment of fire performance of the most common insulation materials used in construction. Current methodologies give a single failure criterion independent of the nature of the material – this can lead to uneven requirements when addressing materials of different characteristics. At present, fire safety codes establish that performance of different materials or assemblies is assumed to be “equivalent” when subject to the same test, where attainment of the unique failure criteria occurs after a required minimum time. Nevertheless, when using extremely different materials this may not be actually the case. Building performance is currently defined in a quantitative way with respect to factors such as energy usage (i.e. global thermal transmittance), element weight (i.e. thickness and mass), space utilisation and cost of application. In the case of fire performance, only a threshold value is required, therefore a quantitative performance assessment is not conducted. As a result, the drivers are those associated with the variables that can be quantified, whereas the thresholds merely need to be met without any alternative for a better performance. This work opens the door to a performance-based-design methodology that takes into account fire performance as an optimisation variable for the building design, to be used with all other quantifiable variables. An added advantage is that the numerical tool required embraces a low level of complexity. As a result, the possibility for any insulation product to achieve quantifiable and acceptable fire safety levels for required energy efficiency targets is established. As a final remark, an application of the performance assessment methodology that introduces fire safety as a quantifiable variable is presented.
6

An exploration of the basis of calculation of 'standards of fire cover' in member states of the European Union and the potential for a rational economic model

Dennett, Michael Frederick January 2002 (has links)
This work has investigated the possibility of developing a model, capable of being used to harmonise standards of fire cover within the EU. The model had to take into account social, humanitarian, economic and environmental factors and the built environment in determining an appropriate emergency response by fire brigades to rescues, fires and contamination of land, air and watercourses. The resulting standards had to be socially acceptable and economically defensible. After examining existing standards of fire cover and the means of determining those standards, all current research into standards of fire cover and related issues was reviewed. A study was also undertaken into fire science, the means of predicting frequency of fire and the means of limiting the incidence and size of fires. Economics, as applied to local and national government and as applied to fire safety systems and fire services was explored. From that initial research it was concluded that the fundamental concepts of fire cover had remained unchanged since the restructuring of fire brigades throughout Europe during the late 1940's and had no relevance to the modern built environment. While some aspects of existing policies and some elements of current research were of value, this work has developed new concepts, including. • Functional requirements for common fire and non-fire emergencies. • Entry preparation time based on the criteria, "The time at which fire fighting shall commence." • Limiting fire size in buildings to "As Small As Reasonably Practicable for a Set Duration" for property protection. • Quantifying the term "As Small As Reasonably Practicable". • Defining a Standard Predetermined Attendance (SPDA) for all incidents. • Determining optimum attendance time limits dependent on the frequency of calls and the installed fire protection features in buildings. • A method of calculating an economic base for determining critical call numbers. • A means of establishing the optimum location of fire stations within a given area. • The number of SPDA's required at each fire station related to total workload. • The provision of assistance to areas that are outside maximum attendance times. The economic model that has resulted, accurately includes all of the potential economic, social, and political variations as the basis of calculation of Standards of Fire Cover in individual Member States of the European Union. It is the contention of this thesis that it is possible to construct formulae, based on sound economic principals, which are capable of being applied to the different fiscal situation in different countries, thereby ensuring similar relative standards.
7

Hazards presented by pyrolysis and combustion products during laboratory experiments and real incidents

Crowder, David January 2015 (has links)
Heat, flame, smoke and fire gases are responsible for the vast majority of fire deaths and injuries and are all products of the chemical and physical processes that occur within fire. This is well known and supported by fire statistics but current fire safety does not directly consider these factors and the hazard they may pose to life. The aim of this thesis is to bring together knowledge from fire science with evidence from fire investigation to provide a way forward for improving fire safety and protecting life using sound scientific principles. A number of major fires and the associated large scale fire reconstructions carried out as part of their investigation have been analysed to assess the way in which polymeric materials contribute towards the overall hazard and whether there are other factors tending to contribute to the hazard. The Stardust Disco fire highlighted the importance of lining materials in their contribution to both rapid fire development and toxicity. Maysfield Leisure Centre demonstrated the link between functional groups in polymers and the major toxicant likely to then contribute to the developing hazard. Harrow Court showed how a modern incident able to develop to flashover would produce a dramatic change in conditions, capable of overcoming fire fighters as well as civilians. Rosepark Care Home demonstrated the importance of simple fire safety measures such as the closing of doors in keeping products of combustion away from relevant persons. The Lakanal fire highlighted the potential complexity of these sorts of incidents and the way in which they tend to be the result of a large number of “things going wrong” all at once. The fire at Atherstone on Stour revealed the potential for rapid fire development to take place across very large environments, again sufficiently quickly to overcome attending fire fighters. The work carried out has demonstrated the intrinsic link between the burning properties of materials with their toxicity, which are then further influenced by the way in which an environment can influence ventilation conditions, thermal insulation and pathways for fire to spread and impose hazards upon people in relevant areas. Fire safety has developed in such a way that flammability and toxicity no longer appear to be considered together, but the findings from the incident analyses indicate there appears to be a need to bring the subjects of toxicity and general fire safety back together.
8

Practical assessment of the dependence of fire service intervention times on life safety

Walker, Richard George January 2017 (has links)
This research identifies realistic timelines for human survivability during accidental dwelling fires (ADF). It also establishes a time window within which the fire service is likely to affect a rescue of the occupants from ADFs. Through a comparison of these two timelines, the likelihood that the fire service will rescue an occupant before they receive a fatal dose of heat and/or smoke (asphyxiant gases) is established. The dependence of fire service intervention times is also assessed in the context of increasing intervention times resulting from cuts to fire authority budgets. The results show that an increase in the time taken to affect a rescue will lead to an increase in the number of fatalities and the severity of injuries which occur when the occupants of a dwelling become trapped by (or are otherwise unable to escape from) fire within the property. Around 80% of all fire deaths and injuries in Great Britain occur in dwellings. This study analyses national and local fire statistics to identify the typical fire situations and common circumstances which lead to fire deaths and injuries. This statistical analysis has been used to inform the carrying out of thirteen large-scale fire experiments. Asphyxiant gas concentrations and compartment temperatures were gathered during these experiments, in order to establish human survival times resulting from the adverse effects of exposure to these. Statistics have also been analysed and a methodology developed to establish fire service intervention times. Establishing survival times on the basis of an analysis of national statistics constitutes new work within the field of community fire safety. In addition, the author is in a preferential position to establish realistic times for fire service interventions, and there is no evidence that these timelines have previously been developed to this extent or compared to timelines for occupant survival. The findings of this research should be considered by fire authorities as they make important decisions for the development of local fire service resourcing activities in continuing times of austerity.
9

Modelling of premixed laminar flame propagating in channels

Li, Fang January 2004 (has links)
The dynamics of the intrinsically unstable premixed flames propagating in channels is studied by means of numerical modelling in this work. Critical conditions of extinction and the influence of the thermal-diffusive effect on the dynamics of flame propagating in planar channels with cold sidewalls under gravity is investigated. For the horizontally propagating flames, the appearance of inversion influences the effect of thermal-diffusion on the asymmetry of flame fronts. For upwards propagating flames, the convex shape of the flame imposed by the mode of ignition combined with buoyancy can suppress the thermal-diffusive effects; in contrast, the buoyancy alone cannot damp the thermal diffusive effects even for quite large Froud numbers in regard to the appearance of inversion. The variation of Lewis number has no essential effect on the planar flame shape formation when flame propagates downward. Lowering Lewis number can significantly decrease the critical conditions of extinction. However, if Lewis number is smaller than some limit, its further effect on the critical extinction conditions is unsignificant. In the two-step consecutive reaction, the effects of the ratio of Damkohler numbers, heat release rates, activation energy and Lewis number on the separation and fragmentation of flames are considered. The inversion is more pronounced in combustion with separated flame fronts than for single-step reactions. However, the inversion is obvious only when the two flame fronts are close enough to each other. Thus, the details of combusiiition chemistry may have a strong effect on the stability of the flame front. The thermal diffusive effect of the first flame is, in certain way, dominant and has influence on the second flame. The presence of the first reaction suppresses the thermal-diffusive effect of the second reaction in regard to the appearance of inversion. The propagation of flames at a variety of Reynolds number ranging from 70 to 1000 are explored. For longer channels or a flat initial flame front, the inversion of the flame is apparent for Reynolds number higher than 200. For large &, the computational grids should be very fine because of the small thickness of preheat zone. The Generalized Curvilinear Coordinate Gridding method is introduced and an elliptic grid generator based on the variational approach is employed to construct the solution-adaptive grids. However, we found out that the global structure of the algorithm required by the adaptive grid approach might be not as efficient as simplified non-adaptive grids for prospective use of massively parallel computers.
10

Examination of the underlying physics in a detailed wildland fire behavior model through field-scale experimentation

Mueller, Eric Victor January 2017 (has links)
Complex computer models, built on basic physical principles, have the potential to aid in the understanding and prediction of wildland fire behavior. However, there remain significant uncertainties and assumptions in the way such models describe the fire, the vegetation, and the interaction of the two. To understand a model’s capabilities, limitations, and the improvements which are still necessary, comparison of model predictions to experimental measurement is critical. Unfortunately, collecting such measurements is particularly difficult at the large scale over which real wildland fires occur and, as a result, this happens infrequently. To address this, an opportunity was seized to collect a detailed set of measurements of fire behavior in a real forest environment. These measurements are thoroughly analyzed for the description they provide of the fire behavior. They are then used as a benchmark to test the capabilities of a particular complex model to describe such a fire and to highlight the limitations and uncertainties. As a result of this evaluation, a set of recommendations for future research, both in experiments and modeling, are offered, in order provide a coherent strategy for the future which will significantly advance these models.

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