A risk review of a fuel cell-based distributed co-generation (FC-Based DCG) system was conducted to identify and quantify the major technological system risks in a worst-case scenario. A risk review entails both a risk assessment and a risk analysis of a designed system, and it is part of risk engineering. Thorough literature reviews and expert interviews were conducted in the field of fuel cells. A thorough literature review of the risk engineering field was also conducted. A procedure for a risk review of the FC-Based DCG System was developed. The representative system design was identified by the current DCG design technology. The risk assessment was carried out, identifying the system components and potential failure modes and consequences. Then, using probabilities of failure for the various system components, the risk associated with a particular system design was determined. A Monte Carlo simulation on the total system reliability was used to evaluate the potential for system failure at a time of 1 hour, 5 hours, 10 hours, 50 hours, 100 hours and 500 hours of continuous operation. The original system was found to be acceptable at the initial times, but after 100 hours was predicted to fail. The components which consistently contribute significantly to the overall system risk are the membrane electrode assembly (MEA) and the nickel-metal foam flow fields. A revised system was analyzed with the reliability of the MEA and the Ni-foam set to 100%. After the revision, the components which contributed significantly to the system risk were the pumps. Simulations were run for several alternative systems to provide feedback on risk management suggestions. The risk engineering process developed with the design approach for this research is applicable to any system and it accommodates the use of many different risk engineering tools.

A risk review of a fuel cell-based distributed co-generation (FC-Based DCG) system was conducted to identify and quantify the major technological system risks in a worst-case scenario. A risk review entails both a risk assessment and a risk analysis of a designed system, and it is part of risk engineering. Thorough literature reviews and expert interviews were conducted in the field of fuel cells. A thorough literature review of the risk engineering field was also conducted. A procedure for a risk review of the FC-Based DCG System was developed. The representative system design was identified by the current DCG design technology. The risk assessment was carried out, identifying the system components and potential failure modes and consequences. Then, using probabilities of failure for the various system components, the risk associated with a particular system design was determined. A Monte Carlo simulation on the total system reliability was used to evaluate the potential for system failure at a time of 1 hour, 5 hours, 10 hours, 50 hours, 100 hours and 500 hours of continuous operation. The original system was found to be acceptable at the initial times, but after 100 hours was predicted to fail. The components which consistently contribute significantly to the overall system risk are the membrane electrode assembly (MEA) and the nickel-metal foam flow fields. A revised system was analyzed with the reliability of the MEA and the Ni-foam set to 100%. After the revision, the components which contributed significantly to the system risk were the pumps. Simulations were run for several alternative systems to provide feedback on risk management suggestions. The risk engineering process developed with the design approach for this research is applicable to any system and it accommodates the use of many different risk engineering tools.

The successful management of solid wastes arising from the combustion of low-rank coal for electricity generation presents significant engineering and environmental challenges. The power stations in the Latrobe Valley region of Victoria, Australia, have long recognised the need for improved long term understanding of ash disposal. This thesis presents the work undertaken in evaluating the mechanisms which lead to the transport of solutes from ash disposal and develops a methodology to quantify their potential long term impacts on groundwaters beneath a disposal site. The Loy Yang power station is used as a case study. A detailed literature review is presented on the mechanisms involved in the leaching of solutes from ash disposal. In general, the release of solutes is well understood and is related to the dissolution of more soluble minerals in the ash and advective transport through pore waters as leachate, although the exact controls for trace elements is less well documented. The proportions of particular solutes and/or trace elements is site specific. For the Latrobe Valley, however, there remains little research undertaken on the behaviour of Loy Yang ash, especially aged or leached ash excavated from a disposal pond after a period of some 6 to 12 months. The principal environmental concerns relating to the disposal of ash are the potential for groundwater contamination from salt fluxes and the transport of trace elements. Thus long term disposal requires a thorough understanding of both the solute fluxes from the ash as well as the controls on the transport of these solutes through groundwater. Predicting the behaviour of ash and the leached solutes under field conditions is difficult and common laboratory tests have been found to be inadequate. The transport of sulfate in seepage was investigated through back analysis of monitoring data, field monitoring, bacterial analysis and modelling. Sulfate was shown to be undergoing strong biogeochemical reactions which attenuate its rate of migration in shallow groundwaters at the Loy Yang power station. The application of a kinetic solute transport model was able to model the monitoring data obtained to date. The chemical quality of the ash, and its source from the power station, is a critical aspect of disposal since this primarily determines the leachability and potential fluxes. After slurrying and disposal in a saturated pond, the amount of soluble minerals is lower and therefore the ash presents a lower potential for groundwater impacts. For ash excavated from a disposal pond and placed within a low moisture environment, such as an Overburden Dump, the potential for leaching and solute transport must be considered differently to that in a saturated disposal pond. Two field trial cells were operated for about 14 months to investigate such behaviour, one artificially irrigated (Wet) and a second open to rainfall only (Dry). Both cells showed the importance of unsaturated flow mechanisms in controlling the water balance and leachate generation, due mainly to the potential of ash to retain moisture in its pores. The irrigated cell showed a marked reduction in leachate salinity as irrigation continued, although some trace elements demonstrated complex leaching patterns. To further quantify ash leaching rates, a series of laboratory leaching columns were constructed and operated, with electronic logging of soil moisture using Time Domain Reflectometry (TDR). The use of TDR, although able to detect relative changes in soil moisture, was less than successful. The leachate results from the columns were encouraging and provided additional confirmation of leaching curves for particular solutes and trace elements. The soil water characteristic curve (SWCC) was established for the ash through a Tempe Cell test. This quantified more accurately the water retention properties highlighted through the field and laboratory research. Importantly, analysis of the SWCC for the ash shows that it appears to maintain high hydraulic conductivity over typical ranges of matric suctions. The geochemical controls on solutes in the various ash leachates generated in the field and laboratory were investigated through geochemical speciation modelling and plotting. The major solutes in leachate appeared to be controlled by dissolution from more soluble minerals, such as gypsum and halite, while for other species the controls were more complex. Most trace elements appeared to be controlled by a mix of mineral dissolution, co-precipitation and adsorption mechanisms. A solute transport and leaching model was developed and applied to the various data sets obtained for this thesis. The model, describing the leaching and transport of solute in one-dimensional steady state flow, gave reasonable calibration to the different column experiments. Extension of this approach to unsaturated flow and solute transport is discussed in light of the experience from the field trials. The conversion of this model to non-dimensional form was then examined and provided a useful approach for assessing the scale effects from different sized column leaching experiments and field trials. The use of batch leaching tests, although not generally representative of field conditions, can be incorporated into this approach and used to estimate the initial concentration of a solute in leachate. The use of these models provides the methodology to quantify leaching over time and at various scales, important in the engineering design of ash disposal sites. In summary, this thesis presents a detailed qualitative study of ash leaching and solute transport mechanisms, and develops a quantitative methodology for the design and assessment of ash disposal sites.

Deterministic computer fire models have progressed over recent years to the point of providing good predictions for some parameters of fire behaviour. However, input data are not always available, and many factors that affect the course of a fire are probabilistic in nature and cannot be determined from physics. One way of surmounting the problem of unavailability of the values of the input parameters is to take them as random variables. By specifying an unsafe region in the output space and calculating its probability, we can obtain a figure for the reliability of the design being tested, in terms of the probability of the unsafe region. In practice, evaluation of the probability distribution of the output space cannot in general be carried out analytically because of the complexity of the computer fire models. An alternative method is to use Monte-Carlo simulation. But it usually requires a large amount of calculation to reach sufficient accuracy, particularly if the probability of the unsafe region is small, as it should be if the design is to be reasonably reliable. Also, if the probability distribution of the input is changed, the whole Monte-Carlo simulation must be redone ab initio. An approach that has been recently advocated in the structural reliability context is that of the response surface method. It consists in representing each output parameter by a nonlinear function of the input parameters. Usually, a quadratic function of the input parameters turns out to be sufficient. Fitting of the response surface is carried out by regression. However, if the range of the input parameters is comparatively large, it is unlikely that one quadratic function will fit the whole range. It then becomes necessary to break up the full range of input parameters into smaller subranges and fit a quadratic function separately to each subrange.

The aims of the research for this thesis were fourfold, all of which focused at reducing employee exposure to diesel particulate in underground coal mines. The four aims were to: a) Develop a method to test disposable diesel exhaust filters and if possible improve their performance b) Investigate the relationship between maintenance and diesel particulate generation c) Highlight the benefits of newer design engines in emission reduction d) Review the research of the Tower Colliery Research group as their findings have been the basis for the development of control technologies for diesel particulate in NSW underground coal mines. Methods used to achieve these aims involved: a) The construction of a test rig to measure the efficiency and backpressure of new and used disposable filters b) The testing of the in service fleet at four of BHP Billiton Illawarra Coal mines using an R&P Series 5100 diesel analysis system mounted in a trailer c) Comparison of a newer design engine with three current vehicles under mining conditions d) A detailed statistical review of all available data from the Tower Colliery Research group. Key outcomes from research conducted for this thesis are: a) The filtration efficiency and backpressure of disposable diesel exhaust filters used by BHP Billiton Illawarra Coal have been improved. These improvements, together with changes to work practices, generate potential cost savings of $395,000 per annum while affording increased protection to equipment operators. b) Seven engines with unacceptable raw exhaust elemental carbon emissions were identified in a fleet of 66 tested. Some faults identified as causing these elevated emission levels were- blocked exhaust flame traps (scrubber tanks), incorrectly set tappets and worn injectors. c) Testing of a prototype 4WD fire protected vehicle powered by an "over the road" engine as against three current vehicles, highlighted reductions in atmospheric elemental carbon concentrations of 67 90%. Significant reductions in raw exhaust elemental carbon levels were also observed. d) A statistical review of data produced by the Tower Colliery Diesel Research group identified elevated exposures within mine transportation roadways. This outcome is significant as much research within the mining industry has focused on other areas in the belief that high air quantities in transportation roadways would limit exposures. This does not appear to be the case. The project has had a number of positive outcomes, all of which have assisted in the reduction of equipment operators to excessive levels of diesel particulate.

The general aim of this research is to find an effective and applicable method of prediction of pyrolysis and ignition of certain furnishing materials in a real fire environment.

This research paper creates a comprehensive statistical model, relating financial impact of risk engineering activity, and insurance claims costs. Specifically, the model shows important statistical relationships among six variables including: types of risk engineering activity, risk engineering dollar cost, duration of risk engineering service, and type of customer by industry classification, dollar premium amounts, and dollar claims costs. We accomplish this by using a large data sample of approximately 15,000 customer-years of insurance coverage, and risk engineering activity. Data sample is from an international casualty/property insurance company and covers four years of operations, 2006-2009. The choice of statistical model is the linear mixed model, as presented in SAS 9.2 software. This method provides essential capabilities, including the flexibility to work with data having missing values, and the ability to reveal time-dependent statistical associations.

Over the last few decades, the world has witnessed rapid urbanisation. One of the many complex problems resulting from increased urbanisation is related to management of stormwater from developed areas. If stormwater is not managed properly, it may lead to flooding of urban areas, and deterioration of water quality in rivers and receiving waters. Urban drainage systems are used to manage urban stormwater. For design of effective and economic urban drainage systems, it is important to estimate the design flows accurately. Many computer based mathematical models have been developed to study catchment runoff (or flows) in urban environments. These models may be used in different stages of the projects such as screening, planning, design and operation. Each stage may require a different model, although some models can be used for several of these stages. A customer survey was conducted in May 1997 to study the current practice in Victoria (Australia) on stormwater drainage design and analysis, as part of this thesis. The survey was restricted to city/shire councils and consultants, who are engaged in design and analysis of urban drainage systems. The results of the survey showed that 95% of respondents used the Statistical Rational method. Also, it was revealed that most respondents were reluctant to use stormwater drainage computer models, since there were no adequate guidelines and information available to use them especially for ungauged catchments. According to 5% of the respondents, who used models, ILSAX was the most widely used stormwater drainage computer model in Victoria. The 1987 edition of the Australian Rainfall-Runoff (ARR87) suggests the ILSAX model as one of the computer models that can be used for stormwater drainage design and analysis. Due to these reasons, the ILSAX model was used in this study in an attempt to produce further guidance to users in development and calibration of ILSAX models of urban drainage systems. In order to use the ILSAX model, it is necessary to estimate the model parameters for catchments under consideration. The model parameters include loss model parameters (i.e. infiltration and depression storage parameters) and other parameters related to the catchment (such as percent imperviousness, soil cover and conveyance system parameters). Some of these parameters can be estimated from available maps and drawings of the catchment. The ideal method to determine these parameters (which cannot be reliably determined from available maps and drawings) is through calibration of these models using observed rainfall and runoff data. However, only few urban catchments are monitored for rainfall and runoff, and therefore calibration can be done only for these catchments. At present, there are no clear guidelines to estimate the model parameters for ungauged catchments where no rainfall-runoff data are available. In this PhD project, first the ILSAX model was calibrated for some gauged urban catchments. From the results of calibration of these catchments, regression equations were developed to estimate some model parameters for use in gauged and ungauged urban stormwater catchments. Before calibrating the ILSAX model for gauged catchments, a detailed study was conducted to; - select the most appropriate modelling option (out of many available in ILSAX) for modelling various urban drainage processes, - study the sensitivity of model parameters on simulated storm hydrographs, and - study the effect of catchment subdivision on storm hydrographs. This detailed study was conducted using two typical urban catchments (i.e. one 'small' and one 'large') in Melbourne metropolitan area (Victoria) considering four design storms of different average recurrence intervals (ARI). Three storms with ARI of 1, 10 and 100 years, and one with ARI greater than 100 years were considered in the study. The results obtained from this detailed study were subsequently used in model calibration of the study catchments. The results showed that the runoff volume of 'large' storm events was more sensitive to the antecedent moisture condition and the soil curve number (which determines soil infiltration) and less sensitive to the pervious and impervious area depression storages. However, for 'small' storm events, the runoff volume was sensitive to the impervious area depression storage. The peak discharge was sensitive to pipe roughness, pit choke factor, pit capacity parameters and gutter characteristics for both 'small' and 'large' storm events. The results also showed that the storm hydrograph was sensitive to the catchment subdivision. The accuracy of rainfall-runoff modelling can be adversely influenced by erroneous input data. Therefore, the selection of accurate input data is crucial for development of reliable and predictive models. In this research project, a number of data analysis techniques were used to select good quality data for model calibration. For calibration of model parameters, parameter optimisation was preferred to the trial and error visual comparison of observed and modelled output responses, due to subjectivity and time-consuming nature of the latter approach. It was also preferred in this study, since the model parameters obtained from calibration were used in the development of regional equations for use in gauged and ungauged catchments. Therefore, it was necessary to have a standard method which can be repeated, and produced the same result when the method is applied at different times for a catchment. An optimisation procedure was developed in this thesis, to estimate the model parameters of ILSAX. The procedure was designed to produce the 'best' set of model parameters that considered several storm events simultaneously. The PEST computer software program was used for the parameter optimisation. According to this procedure, the impervious area parameters can be obtained from frequent 'small' storm events, while the pervious area parameters can be obtained from less-frequent 'large' storm events. Twenty two urban catchments in the Melbourne metropolitan area (Victoria) were considered in the model parameter optimisation. Several 'small' and 'large' storm events were considered for each catchment. However, it was found during the analysis that the selected 'large' storm events did not produce any pervious area runoff, and therefore it was not possible to estimate the pervious area parameters for these catchments. The Giralang urban catchment in Canberra (Australia) was then selected to demonstrate the optimisation procedure for estimating both impervious and pervious area parameters, since data on 'small' and 'large' storm events were available for this catchment. The calibration results were verified using different sets of storm events, which were not used in the calibration, for all catchments. The optimised model parameters obtained for each catchment were able to produce hydrographs similar to the observed hydrographs, during verification. The impervious area parameters obtained from optimisation agreed well with the information obtained from other sources such as areal photographs, site visits and published literature. Similarly, the pervious area parameters obtained for the Giralang catchment agreed well with the values given in the published literature. If ILSAX is to be used for ungauged drainage systems for which no storm data are available, then the model parameters have to be estimated by some other means. One method is to estimate them through regional equations, if available. These regional equations generally relate the model parameters to measurable catchment properties. In this study, analyses were conducted to develop such regional equations for use in ungauged residential urban catchments in the Melbourne metropolitan area. The Melbourne metropolitan area was considered as one hydrologically homogeneous group, since the urban development is similar in the area. The equations were developed for the land-use parameters of directly connected impervious area percentage (DCIA) and supplementary area percentage (SA), and the directly connected impervious area depression storage (DSi). Several influential catchment parameters such as catchment area, catchment slope, distance from the Central Business District to the catchment and household density were considered as independent variables in these regional equations. A regional equation was developed for DCIA as a function of the household density. A similar equation was also developed to determine SA as a function of household density. DCIA was obtained from the model parameter optimisation using rainfall-runoff data (i.e. calibration), while SA and household density were obtained from the available drawings and field visits. These two equations showed a very good correlation with household density and therefore, DCIA and SA can be estimated accurately using these two equations. The city/shire councils generally have information on the household density in already developed urban areas and therefore, these two equations can be used to estimate DCIA and SA for these areas. For new catchments, these equations can be used to estimate DCIA and SA based on the proposed household density. The directly connected impervious area depression storage (DSi) is the only ILSAX model loss parameter that was obtained from the calibration, and this is the loss parameter that is more sensitive for 'small' storm events of the urban drainage catchments. A regional equation was attempted for this parameter by relating with the catchment slope, since the catchment slope was found to have some correlation with DSi according to past studies. However, the results in this study did not show a correlation between these two variables. Therefore, based on the results of this study, a range of 0 - 1 mm was recommended for DSi. Because of the recommended range for DSi, the sensitivity of DSi against DCIA was revisited and found that DSi was less sensitive compared to DCIA, in simulating the peak discharge and time to peak discharge for both 'small' and 'large' storm events. However, there is a little impact for runoff volume and hydrograph shape for 'small' storm events. Therefore, defining a range for DSi is justified for modelling purposes and the user can choose a suitable value within this range from engineering judgement.

Packaging plays an important role in protecting and preserving the quality of food and is therefore significant in any food manufacturing and distribution process. The shelf life of any food is limited due to the occurrence of many deteriorative processes and reactions within the food material. These include physical and chemical reactions and interactions between food and the ambient environment across the packaging material. Milk powder like any other food, is prone to such reactions and interactions with package resulting in degradation of its edible quality due to changes in smell, colour and texture, which ultimately renders it nutritionally and economically unacceptable. During distribution and storage the packaging system needs to stabilize the powder by ensuring optimum storage conditions are maintained. To ensure maximum shelf life it is essential to apply packaging systems that are optimally designed, to meet the requirements with respect to manufacturing as well as product protection in the distribution environment. In this thesis, the interactions between ambient environmental conditions, packaging material properties and the shelf life of a particular filled milk powder were investigated. Consequently, the requirements for a packaging system that can provide a two-year shelf life for the powder were determined. The filled milk powder is manufactured and packaged in bulk in Europe, imported into Africa via sea freight containers to be repacked into small portion packs and distributed in multiple African countries. Because of Africa's tropical conditions the packaged product is exposed to rather high levels of relative humidity and temperature during transportation and storage which influences the stability of the powder. The storage stability of the filled milk powder along with the barrier characteristics of the packaging was assessed in order to evaluate the theoretical shelf life of the powder in its current packaging system.

A 'spray and hay' method was developed which replaces the noxious weed serrated tussock (Nassella trichotoma (Nees) Arech.) with indigenous kangaroo grass (Themeda triandra Forrsk.) in partly disturbed remnants of western (basalt) plains indigenous grassland, a community listed as vulnerable to extinction. Investigations were carried out on Melbourne's north-west urban fringe. Refinements of the 'spray and hay' method resulted in low densities of other weeds amongst the newly established T. triandra swards. First steps in the method involved removal of weeds by slashing and follow-up treatment with either of the herbicides, glyphosate (as Monsanto Roundup®) or atrazine (as Nufarm Nutrazine®). These steps resulted in close to 100% kill of mature N. trichotoma plants. Greater than 98% replacement of N. trichotoma with T. triandra was achieved by thatching over herbicide-treated plots with seed-bearing T. triandra hay harvested from remnant grasslands and then removal of the hay several months later by either burning or physical removal. The type and timing of herbicide application, thatching and removal of thatch were found to be central for successfully establishing competitive densities of T. triandra seedlings and minimizing re-establishment of N. trichotoma and other weed seedlings. A treatment set involving: slashing weed biomass in summer (January), herbicide application in autumn (April) followed by thatching with seed-bearing T. triandra hay in winter (July) and removal of thatch in spring (October) produced the best results. Assessing the seed content of hay and germinability of seed prior to revegetation were also important for calculating the amount of hay laid and subsequent seedling densities established. The seed content and germinability of seed-bearing hay was found to vary markedly in samples harvested in three different years, across discrete remnant grassland sites and even within undisturbed grassland sites. Reasons for the success of the method, and why other variations are less successful are discussed, as is the wider application of the method for weed control and replacement with indigenous grasses in lowland grassland remnants.