ORCID Profile
0000-0002-1831-6754
Current Organisation
Victoria University
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Computational Heat Transfer | Interdisciplinary Engineering | Natural Hazards | Atmospheric Dynamics | Computational Fluid Dynamics | Environmental Impact Assessment | Physical Geography and Environmental Geoscience
Expanding Knowledge in the Environmental Sciences | Environmental Management Systems | Urban and Industrial Air Quality | Natural Hazards in Forest and Woodlands Environments | Environmental Health |
Publisher: Elsevier BV
Date: 03-2020
Publisher: Springer Science and Business Media LLC
Date: 28-07-2021
DOI: 10.1140/EPJC/S10052-023-11837-9
Abstract: A determination of the jet energy scale is presented using proton–proton collision data with a centre-of-mass energy of $$\\sqrt{s}=13$$ s = 13 TeV, corresponding to an integrated luminosity of 140 fb $$^{-1}$$ - 1 collected using the ATLAS detector at the LHC. Jets are reconstructed using the ATLAS particle-flow method that combines charged-particle tracks and topo-clusters formed from energy deposits in the calorimeter cells. The anti- $$k_\\textrm{t}$$ k t jet algorithm with radius parameter $$R=0.4$$ R = 0.4 is used to define the jet. Novel jet energy scale calibration strategies developed for the LHC Run 2 are reported that lay the foundation for the jet calibration in Run 3. Jets are calibrated with a series of simulation-based corrections, including state-of-the-art techniques in jet calibration such as machine learning methods and novel in situ calibrations to achieve better performance than the baseline calibration derived using up to 81 fb $$^{-1}$$ - 1 of Run 2 data. The performance of these new techniques is then examined in the in situ measurements by exploiting the transverse momentum balance between a jet and a reference object. The b -quark jet energy scale using particle flow jets is measured for the first time with around 1% precision using $$\\gamma $$ γ +jet events.
Publisher: Elsevier BV
Date: 06-2017
Publisher: Springer Science and Business Media LLC
Date: 31-10-2023
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/WF19046
Abstract: The effect of ignition protocol on the development of grassfires is investigated using physics-based simulation. Simulation allows measurement of the forward rate of spread of a fire as a function of time at high temporal resolution. Two ignition protocols are considered: the inward ignition protocol, where the ignition proceeds in a straight line from the edges of the burnable fire plot to the centre of the plot and the outwards ignition protocol, where the ignition proceeds from the centre of the burnable fire plot to the edges of the plot. In addition to the two ignition protocols, the wind speed, time taken for the ignition to be completed and ignition line length are varied. The rate of spread (R) of the resultant fires is analysed. The outwards ignition protocol leads to an (approximately) monotonic increase in R, whereas the inward ignition protocol can lead to a peak in R before decreasing to the quasi-equilibrium R. The fires simulated here typically take 50m from the ignition line to develop a quasi-equilibrium R. The results suggest that a faster ignition is preferable to achieve a quasi-equilibrium R in the shortest distance from the ignition line.
Publisher: MDPI AG
Date: 11-08-2020
Abstract: As a part of our ongoing investigations on passively fire protecting polymeric materials, we have been employing both reactive and additive routes involving phosphorus-containing compounds. These included inorganic and organic substances, and in the latter case, the phosphorus-bearing groups differed in terms of the chemical environments (phosphite, phosphate, phosphine, phosphine oxide and phosphonate ester) and oxidation state of the P atom (i.e., III, or V). The overall flammability profiles of wood substrates coated with the phosphorus-containing compounds were obtained through cone calorimetric measurements. The elemental composition, morphology and chemical natures of the char residues, obtained from the cone tests, were analysed through a variety of spectroscopic, chromatographic and spectrometric means. From the complementary information, obtained through these analyses, some probable mechanistic pathways that underpin the condensed- and gaseous-phase activities of the different additives are suggested. It was found that the inorganic solid additive, i.e., (NH4)2HPO4, underwent a two-step degradation, yielding ammonia gas and phosphoric acid. Furthermore, the liquid additives, owing to their volatility as compared to the solid ones, showed a relatively higher presence in the vapour phase than volatile fragments emanating from the latter ones (i.e., from phosphine and the phosphine oxides).
Publisher: Springer Science and Business Media LLC
Date: 03-12-2019
Publisher: American Physical Society (APS)
Date: 05-09-2023
Publisher: MDPI AG
Date: 20-10-2023
DOI: 10.3390/FIRE6100406
Publisher: Wiley
Date: 06-2009
DOI: 10.1002/FAM.986
Publisher: Springer Science and Business Media LLC
Date: 23-08-2023
Abstract: This paper describes a search for the single production of an up-type vector-like quark ( T ) decaying as T → Ht or T → Zt . The search utilises a dataset of pp collisions at $$ \\sqrt{s} $$ s = 13 TeV collected with the ATLAS detector during the 2015–2018 data-taking period of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb − 1 . Data are analysed in final states containing a single lepton with multiple jets and b -jets. The presence of boosted heavy resonances in the event is exploited to discriminate the signal from the Standard Model background. No significant excess above the Standard Model expectation is observed, and 95% CL upper limits are set on the production cross section of T quarks in different decay channels. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength ( κ ) of the vector-like quark. For singlet T quarks, κ values above 0.53 are excluded for all masses below 2.3 TeV. At a mass of 1.6 TeV, κ values as low as 0.35 are excluded. For T quarks in the doublet scenario, where the production cross section is much lower, κ values above 0.72 are excluded for all masses below 1.7 TeV, and this exclusion is extended to κ above 0.55 for low masses around 1.0 TeV.
Publisher: MDPI AG
Date: 08-01-2022
DOI: 10.3390/FIRE5010006
Abstract: Firebrand spotting is a potential threat to people and infrastructure, which is difficult to predict and becomes more significant when the size of a fire and intensity increases. To conduct realistic physics-based modeling with firebrand transport, the firebrand generation data such as numbers, size, and shape of the firebrands are needed. Broadly, the firebrand generation depends on atmospheric conditions, wind velocity and vegetation species. However, there is no experimental study that has considered all these factors although they are available separately in some experimental studies. Moreover, the experimental studies have firebrand collection data, not generation data. In this study, we have conducted a series of physics-based simulations on a trial-and-error basis to reproduce the experimental collection data, which is called an inverse analysis. Once the generation data was determined from the simulation, we applied the interpolation technique to calibrate the effects of wind velocity, relative humidity, and vegetation species. First, we simulated Douglas-fir (Pseudotsuga menziesii) tree-burning and quantified firebrand generation against the tree burning experiment conducted at the National Institute of Standards and Technology (NIST). Then, we applied the same technique to a prescribed forest fire experiment conducted in the Pinelands National Reserve (PNR) of New Jersey, the USA. The simulations were conducted with the experimental data of fuel load, humidity, temperature, and wind velocity to ensure that the field conditions are replicated in the experiments. The firebrand generation rate was found to be 3.22 pcs/MW/s (pcs-number of firebrands pieces) from the single tree burning and 4.18 pcs/MW/s in the forest fire model. This finding was complemented with the effects of wind, vegetation type, and fuel moisture content to quantify the firebrand generation rate.
Publisher: Springer Science and Business Media LLC
Date: 14-06-2017
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/WF20046
Publisher: Wiley
Date: 15-05-2017
DOI: 10.1002/FAM.2439
Publisher: Elsevier BV
Date: 10-2018
Publisher: Springer Science and Business Media LLC
Date: 26-09-2023
Publisher: Elsevier BV
Date: 10-2021
Publisher: Springer Science and Business Media LLC
Date: 07-05-2019
Publisher: MDPI AG
Date: 10-2020
DOI: 10.3390/EN13195117
Abstract: Lithium-ion batteries (LiBs) are a proven technology for energy storage systems, mobile electronics, power tools, aerospace, automotive and maritime applications. LiBs have attracted interest from academia and industry due to their high power and energy densities compared to other battery technologies. Despite the extensive usage of LiBs, there is a substantial fire risk associated with their use which is a concern, especially when utilised in electric vehicles, aeroplanes, and submarines. This review presents LiB hazards, techniques for mitigating risks, the suppression of LiB fires and identification of shortcomings for future improvement. Water is identified as an efficient cooling and suppressing agent and water mist is considered the most promising technique to extinguish LiB fires. In the initial stages, the present review covers some relevant information regarding the material constitution and configuration of the cell assemblies, and phenomenological evolution of the thermal runaway reactions, which in turn can potentially lead to flaming combustion of cells and battery assemblies. This is followed by short descriptions of various active fire control agents to suppress fires involving LiBs in general, and water as a superior extinguishing medium in particular. In the latter parts of the review, the phenomena associated with water mist suppression of LiB fires are comprehensively reviewed.
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Physical Society (APS)
Date: 31-01-2018
Publisher: Elsevier BV
Date: 11-2023
Publisher: Springer Science and Business Media LLC
Date: 26-08-2020
Publisher: Springer Science and Business Media LLC
Date: 28-09-2202
Publisher: MDPI AG
Date: 28-06-2020
Abstract: The behavior of a grassland fire propagating downstream of a forest canopy has been simulated numerically using the fully physics-based wildfire model FIRESTAR3D. This configuration reproduces quite accurately the situation encountered when a wildfire spreads from a forest to an open grassland, as can be the case in a fuel break or a clearing, or during a prescribed burning operation. One of the objectives of this study was to evaluate the impact of the presence of a canopy upstream of a grassfire, especially the modifications of the local wind conditions before and inside a clearing or a fuel break. The knowledge of this kind of information constitutes a major element in improving the safety conditions of forest managers and firefighters in charge of firefighting or prescribed burning operations in such configurations. Another objective was to study the behavior of the fire under realistic turbulent flow conditions, i.e., flow resulting from the interaction between an atmospheric boundary layer (ABL) with a surrounding canopy. Therefore, the study was ided into two phases. The first phase consisted of generating an ABL/canopy turbulent flow above a pine forest (10 m high, 200 m long) using periodic boundary conditions along the streamwise direction. Large Eddy Simulations (LES) were carried out for a sufficiently long time to achieve a quasi-fully developed turbulence. The second phase consisted of simulating the propagation of a surface fire through a grassland, bordered upstream by a forest section (having the same characteristics used for the first step), while imposing the turbulent flow obtained from the first step as a dynamic inlet condition to the domain. The simulations were carried out for a wind speed that ranged between 1 and 12 m/s these values have allowed the simulations to cover the two regimes of propagation of surfaces fires, namely plume-dominated and wind-driven fires.
Publisher: MDPI AG
Date: 14-03-2021
DOI: 10.3390/APP11062590
Abstract: Given that existing fire risk models often ignore human and organizational errors (HOEs) ultimately leading to underestimation of risks by as much as 80%, this study employs a technical-human-organizational risk (T-H-O-Risk) methodology to address knowledge gaps in current state-of-the-art probabilistic risk analysis (PRA) for high-rise residential buildings with the following goals: (1) Develop an improved PRA methodology to address concerns that deterministic, fire engineering approaches significantly underestimate safety levels that lead to inaccurate fire safety levels. (2) Enhance existing fire safety verification methods by incorporating probabilistic risk approach and HOEs for (i) a more inclusive view of risk, and (ii) to overcome the deterministic nature of current verification methods. (3) Perform comprehensive sensitivity and uncertainty analyses to address uncertainties in numerical estimates used in fault tree/event trees, Bayesian network and system dynamics and their propagation in a probabilistic model. (4) Quantification of human and organizational risks for high-rise residential buildings which contributes towards a policy agenda in the direction of a sustainable, risk-based regulatory regime. This research contributes to the development of the next-generation building codes and risk assessment methodologies.
Publisher: Springer Science and Business Media LLC
Date: 03-10-2023
Publisher: Elsevier BV
Date: 11-2005
Publisher: MDPI AG
Date: 07-11-2019
Abstract: In the present work, some materials that are commonly used in the construction industry were studied with regard to their thermal degradation characteristics and combustion attributes. These included façade materials for pre-fabricated houses, such as the layers of cross-laminated timber (CLT) and the inner core of aluminium composite panels (ACPs). The relevant investigations were carried out by employing thermo-gravimetric analysis (TGA) and pyrolysis combustion flow calorimetry (PCFC). The Arrhenius parameters and the associated calorimetric quantities, i.e., heat release rates, temperature to the peak heat release rate, heats of combustion, heat release capacities, and char yields, were also evaluated. These parameters showed that CLT is more fire retarded than the polymeric internal core of ACP façade materials. Furthermore, some valuable correlations among the various test quantities were found. For instance, a good correlation exists between the general profiles of the thermograms obtained through TGA runs and the heat release rate (HRR) traces from PCFC measurements. Depending on the nature of the materials, the char yields measured by PCFC can be 4–20 times higher than the ones obtained through TGA.
Publisher: American Physical Society (APS)
Date: 30-10-2023
Publisher: American Physical Society (APS)
Date: 16-08-2023
Publisher: Springer Science and Business Media LLC
Date: 13-10-2023
Publisher: Springer Science and Business Media LLC
Date: 02-10-2023
Publisher: Wiley
Date: 18-06-2021
DOI: 10.1002/FAM.2872
Abstract: While probabilistic risk assessment (PRA) is an explicit methodology for complying with the performance requirements of the Building Code of Australia (BCA) or similar codes, it traditionally focuses only on technical risks of fire safety systems in a building. There are growing concerns that performance‐based fire engineering designs underestimate safety risk levels in high‐rise residential buildings. Existing fire risk models account for failures of technical systems but ignore human and organizational errors (HOEs) and the complex interactions among these variables. Probabilistic models in other applications, such as offshore platforms and nuclear plants, demonstrate the importance of HOE inclusion in risk models and the resulting impacts on overall risk. This paper proposes a comprehensive technical‐human‐organizational risk (T‐H‐O‐Risk) methodology to enhance the PRA approach by quantifying human and organizational risks in a probabilistic model using Bayesian Network (BN) analysis of HOEs and System Dynamics (SD) modelling for dynamic characterization of risk variations over time. While risk modelling itself is not novel, the current research develops unique and specific enhancements to existing risk approaches by integrating HOE risks with technical risks in a comprehensive dynamic and probabilistic model for high‐rise residential buildings. Three case studies are conducted to demonstrate the application of this comprehensive approach to the designs of various high‐rise residential buildings ranging from 18 to 24 storeys. Societal risks are represented in F‐N curves. Results show that in general, fire safety designs that do not consider HOEs underestimate overall risks generally by~20%—and can reach up to 42% in an extreme case. Furthermore, risks over time due to HOEs vary by as much as 30% over a 10‐year period. A sensitivity analysis indicates that deficient training, poor safety culture and ineffective emergency plans have significant impact on overall risk.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Elsevier BV
Date: 05-2023
Publisher: MDPI AG
Date: 05-03-2020
Abstract: In the present article, we report on the chemical modifications of some carbohydrate-based substrates, such as potato starch, dextran, β-cyclodextrin, agar agar and tamarind, by reacting with diethylchlorophosphate (DECP), in dispersions in dichloromethane (DCM), in the presence of triethylamine (TEA) as the base. The modified substrates, after recovery and purification, were analyzed for their chemical constitutions, thermal stabilities and calorimetric properties using a variety of analytical techniques. These included: solid-state 31P NMR, inductively coupled plasma-optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA) and pyrolysis combustion flow calorimetry (PCFC). The unmodified counterparts were also subjected to the same set of analyses with a view to serving as controls. Phosphorus analyses, primarily through ICP-OES on the recovered s les, showed different degrees of incorporation. Such observations were optionally verified through solid-state 31P NMR spectroscopy. The thermograms of the modified substrates were noticeably different from the unmodified counterparts, both in terms of the general profiles and the amounts of char residues produced. Such observations correlated well with the relevant parameters obtained through PCFC runs. Overall, the modified systems containing phosphorus were found to be less combustible than the parent substrates, and thus can be considered as promising matrices for environmentally benign fire-resistant coatings.
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 07-2017
Publisher: American Physical Society (APS)
Date: 16-10-2023
Publisher: Springer Science and Business Media LLC
Date: 09-2023
Publisher: Elsevier BV
Date: 09-2020
Publisher: MDPI AG
Date: 12-09-2020
Abstract: In this study, numerical simulations of coupled solid-phase reactions (pyrolysis) and gas-phase reaction (combustion) were conducted. During a fire, both charring and non-charring materials undergo a pyrolysis as well as a combustion reaction. A three-dimensional computational fluid dynamics (CFD)-based fire model (Fire Dynamics Simulator, FDS version 6.2) was used for simulating the PMMA (non-charring), pine (charring), wool (charring) and cotton (charring) flaming fire experiments conducted with a cone calorimeter at 50 and 30 kW/m2 irradiance. The inputs of chemical kinetics and the heat of reaction were obtained from s le mass change and enthalpy data in TGA and differential scanning calorimetry (DSC) tests and the flammability parameters were obtained from cone calorimeter experiments. An iso-conversional analytical model was used to obtain the kinetic triplet of the above materials. The thermal properties related to heat transfer were also mostly obtained in house. All these directly measured fire properties were inputted to FDS in order to model the coupled pyrolysis–combustion reactions to obtain the heat release rate (HRR) or mass loss. The comparison of the results from the simulations of non-prescribed fires show that experimental HRR or mass loss curve can be reasonably predicted if input parameters are directly measured and appropriately used. Some guidance to the optimization and inverse analysis technique to generate fire properties is provided.
Publisher: MDPI AG
Date: 29-01-2021
DOI: 10.3390/APP11031247
Abstract: Lithium-ion batteries (LIBs) are used extensively worldwide in a varied range of applications. However, LIBs present a considerable fire risk due to their flammable and frequently unstable components. This paper reviews experimental and numerical studies to understand parametric factors that have the greatest influence on the fire risks associated with LIBs. The LIB chemistry and the state of charge (SOC) are shown to have the greatest influence on the likelihood of a LIB transitioning into thermal runaway (TR) and releasing heats which can be cascaded to cause TR in adjacent cells. The magnitude of the heat release rate (HRR) is quantified to be used as a numerical model input parameter (source term). LIB chemistry, the SOC, and incident heat flux are proven to influence the magnitude of the HRR in all studies reviewed. Therefore, it may be conjectured that the most critical variables in addressing the overall fire safety and mitigating the probability of TR of LIBs are the chemistry and the SOC. The review of numerical modeling shows that it is quite challenging to reproduce experimental results with numerical simulations. Appropriate boundary conditions and fire properties as input parameters are required to model the onset of TR and heat transfer from thereon.
Publisher: MDPI AG
Date: 20-01-2022
DOI: 10.3390/APP12031073
Abstract: The physical characteristics of water sprays profoundly influence the efficacy with which fires are extinguished. One of the most important physical characteristics of water sprays is the median diameter of the water droplets. However, this parameter is difficult to measure without resorting to the use of specialised equipment. Furthermore, the distribution of the size of water droplets and their initial velocity are profoundly sensitive to the pressure at the nozzle head. This paper presents a simple technique to determine the median droplet size of a water spray produced by a nozzle. The method required only two experiments to determine the mass flux distribution generated by a nozzle operating at two known pressures. A computational fluid dynamics (CFD) program was then used to estimate the median diameter of the water spray under these conditions. The median droplets generated when the nozzle was operating under a different pressure can be calculated using an established empirical relationship. The approach advocated in this paper is supported by invoking Whewell’s principle of consilience of inductions. This was achieved by observing that the CFD software accurately predicts the mass flux distribution when the new pressure and estimated median diameter of the droplets were used as inputs. This provides independent evidence that the proposed approach has some merit. The findings of this research may contribute to establish a technique in calculating the median diameter of droplets when direct measurement of droplet diameter is not available.
Publisher: Elsevier BV
Date: 2019
Publisher: SAGE Publications
Date: 26-01-2009
Publisher: Elsevier BV
Date: 07-2020
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 25-01-2023
DOI: 10.5098/HMT.20.2
Publisher: CSIRO Publishing
Date: 13-05-2022
DOI: 10.1071/WF21088
Abstract: Firebrands (often called embers) increase the propagation rate of wildfires and often cause the ignition and destruction of houses. Predicting the motion of firebrands and the ignition of new fires is therefore of significant interest to fire authorities. Numerical models have the potential to accurately predict firebrand transport. The present study focuses on conducting a set of benchmark experiments using a novel firebrand generator, a device that produces controlled and repeatable sets of firebrands, and validating a numerical model for firebrand transport against this set of experiments. The validation is conducted for the transport of non-burning and burning cubiform firebrand particles at two flow speeds. Four generic drag sub-models used to estimate drag coefficients that are suited for a wide variety of firebrand shapes are verified for their applicability to firebrand transport modelling. The four sub-models are found to be good in various degrees at predicting the transport of firebrand particles.
Publisher: Frontiers Media SA
Date: 28-06-2019
Publisher: CSIRO Publishing
Date: 20-01-2023
DOI: 10.1071/WF21125
Abstract: The interaction of wind and fire on a sloped terrain is always complex owing to the mechanisms of heat transfer and flame dynamics. Heating of unburned vegetation by attached flames may increase the rate of spread. The relative intensities of convective and radiative heat fluxes may change fire behaviour significantly. This paper presents a detailed analysis of flame dynamics, mode of fire propagation and surface radiative and convective heat fluxes on sloped terrain at various wind speeds using physics-based simulations. It was found that with increasing slope angles and wind velocity, the plume inclines more towards the ground and becomes elongated in upslope cases, whereas in downslope cases, the plume rises from the ground earlier. For higher wind velocities, the flame and near-surface flame dynamics appear to show rising, even though the plume is attached. The flame contour results indicate that the near-surface flame dynamics are difficult to characterise using Byram’s number. A power-law correlation was observed between the simulated flame lengths and fireline intensities. The convective heat fluxes are more relevant for wind-driven fire propagation and greater upslopes, whereas both fluxes are equally significant for lower driving wind velocities compared with higher wind velocities.
Publisher: CSIRO Publishing
Date: 20-01-2023
DOI: 10.1071/WF21124
Abstract: This study focuses on physics-based modelling of grassfire behaviour over flat and sloped terrains through a set of field-scale simulations performed using the Wildland–urban Interface Fire Dynamics Simulator (WFDS), with varying wind speeds (12.5, 6 and 3 m s−1) and slope angles (−30° to +30°). To ensure the accuracy of this Large Eddy Simulation (LES), a sensitivity study was carried out to select the converged domain and grid sizes. Fire isochrones, locations of fire front, dynamic and quasi-steady rates of spread (RoS), and fire intensity results from the simulations are presented. Within the simulations conducted, the RoS and fire intensity were found to be higher with increasing slope angles, as well as with wind velocity. RoS comparisons are made with various empirical models. At different slope angles and driving wind velocities, different empirical quasi-steady RoS broadly match with particular dynamic maximum, minimum and averaged RoS values from this study. It appears that the ideal nature of grassfire propagation simulation and challenges related to measuring quasi-steady values in experimental studies are likely reasons for the observed differences. Additionally, for lower wind velocities, the RoS–fire intensity relationship (Byram’s) deviates from linearity for greater upslopes.
Publisher: MDPI AG
Date: 16-03-2021
DOI: 10.3390/APP11062631
Abstract: Conventional (diesel-electric) submarines can provide improved stealth compared to nuclear submarines once submerged. This is because nuclear submarines are generally larger and are required to operate their nuclear reactors at all times, unlike diesel-electric submarines which are generally smaller and can run exclusively on batteries when submerged which generally requires fewer moving parts. These characteristics normally result in a smaller acoustic, thermal and magnetic signature which afford diesel-electric submarines greater stealth when submerged. However, the current underwater range and endurance is limited by the energy storage or generation for submerged operation. The application of emerging energy storage technology seeks to address this limitation and provide significant tactical and operational advantages to the conventional submarine operator. From a fire safety perspective, the potential addition of technologies such as rechargeable lithium-ion batteries, Air Independent Propulsion (AIP) systems and increasingly sophisticated electronic equipment dramatically changes the risk space in an already challenging and unforgiving underwater environment. This study reviews the functions, failure modes and maturity of emerging technologies that have serious submarine fire safety implications. A semi-quantitative assessment of the fire risk associated with potential large future conventional submarine design options for batteries and AIP is provided. This assessment concludes that lithium-ion batteries pose the greatest challenge with regard to integration into conventional submarines without compromising reliability or safety.
Publisher: Cambridge University Press (CUP)
Date: 25-07-2004
Publisher: Springer Science and Business Media LLC
Date: 28-11-2020
Publisher: Springer Science and Business Media LLC
Date: 22-06-2023
DOI: 10.1007/S10965-023-03641-6
Abstract: A novel fire-retardant epoxy thermoset, containing boron polyol complex, was prepared and characterised. The fire-retardant additive was a stoichiometric mixture of boric acid and glycerol. Flame retardancy of the epoxy resin was improved by the formation of stable char layer that protected the underlying epoxy from further burning. Phonon transport through the polymer matrix via hydrogen bonding was identified. The hydrogen bonding acted as a thermal bridge for intermolecular phonon transport to gain improved thermal conductivity resulting early char formation. The hydrogen bonding between the complex and the epoxy matrix was demonstrated using Fourier Transform Infrared Spectroscopy. The phonon transport and a high degree of graphitization was confirmed using Raman Spectroscopy. Thermogravimetric analysis was used for polymer decomposition to confirm a char yield of over 20%. Reaction to fire test revealed enhancement in fire retardancy and self-extinguishing properties of the blend compared to the neat epoxy. Cone calorimetry testing confirmed decreased peak heat release rate and total smoke production by the effect of boron compound in the epoxy matrix. Hydrogen bonding, formation of thick stable layer of char at the polymer surface, and a blowing out effect caused by pyrolytic gases escaping to the gaseous phase, were attributed to the improved fire retardancy. This research may find applications in thermal insulation material of electronic circuit boards, coating in aerospace materials, as well as building and construction industries.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 10-2017
Publisher: MDPI AG
Date: 25-10-2021
Abstract: The disruptions to wildland fires, such as firebreaks, roads and rivers, can limit the spread of wildfire propagating through surface or crown fire. A large forest can be separated into different zones by carefully constructing firebreaks through modification of vegetation in firebreak regions. However, the wildland fire behaviour can be unpredictable due to the presence of either wind- or buoyancy-driven flow in the fire. In this study, we aim to test the efficacy of an idealised firebreak constructed by unburned vegetation. The physics-based large eddy simulation (LES) simulation is conducted using Wildland–urban interface Fire Dynamic Simulator (WFDS). We have carefully chosen different wind velocities with low to high values, 2.5~12.5 m/s, so the different fire behaviours can be studied. The behaviour of surface fire is studied by Australian grassland vegetation, while the crown fire is represented by placing cone-shaped trees with grass underneath. With varying velocity and vegetation, four values of firebreak widths (Lc), ranging from 5~20 m, is tested for successful break distance needed for the firebreak. For each failure or successful firebreak width, we have assessed the characteristics of fire intensity, mechanism of heat transfer, heat flux, and surface temperature. It was found that with the inclusion of forest trees, the heat release rate (HRR) increased substantially due to greater amount of fuel involved. The non-dimensional Byram’s convective number (NC) was calculated, which justifies simulated heat flux and fire characteristics. For each case, HRR, total heat fluxes, total preheat flux, total preheat radiation and convective heat flux, surface temperature and fire propagation mode are presented in the details. Some threshold heat flux was observed on the far side of the firebreak and further studies are needed to identify them conclusively.
Publisher: International Association for Fire Safety Science
Date: 2008
Publisher: Springer Science and Business Media LLC
Date: 10-10-2023
Publisher: Springer Science and Business Media LLC
Date: 05-09-2023
Publisher: Elsevier BV
Date: 04-2019
Publisher: MDPI AG
Date: 15-08-2020
Abstract: In the present paper, we report on a detailed study regarding the thermal degradation behaviours of some bio-sourced substrates. These were previously identified as the base materials in the formulations for fireproofing wood plaques through our investigations. The substrates included: β-cyclodextrin, dextran, potato starch, agar-agar, tamarind kernel powder and chitosan. For deducing the Arrhenius parameters from thermograms obtained through routine thermogravimetric analyses (TGA), we used the standard Flynn–Wall–Ozawa (FWO) method and employed an in-house developed proprietary software. In the former case, five different heating rates were used, whereas in the latter case, the data from one dynamic heating regime were utilized. Given that the FWO method is essentially based on a model-free approach that also makes use of multiple heating rates, it can be considered in the present context as superior to the one that is dependent on a single heating rate. It is also relevant to note here that the values of energy of activation (Ea) obtained in each case should only be considered as apparent values at best. Furthermore, some useful, but limited, correlations were identified between the Ea values and the relevant parameters obtained earlier by us from pyrolysis combustion flow calorimetry (PCFC).
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 15-10-2021
DOI: 10.5098/HMT.17.13
Publisher: Springer Science and Business Media LLC
Date: 14-04-2021
Publisher: MDPI AG
Date: 14-12-2020
DOI: 10.3390/APP10248918
Abstract: The current paper presents an application of an alternative probabilistic risk assessment methodology that incorporates technical, human, and organizational risks (T-H-O-Risk) using Bayesian network (BN) and system dynamics (SD) modelling. Seven case studies demonstrate the application of this holistic approach to the designs of high-rise residential buildings. An incremental risk approach allows for quantification of the impact of human and organizational errors (HOEs) on different fire safety systems. The active systems considered are sprinklers, building occupant warning systems, smoke detectors, and smoke control systems. The paper presents detailed results from T-H-O-Risk modelling for HOEs and risk variations over time utilizing the SD modelling to compare risk acceptance in the seven case studies located in Australia, New Zealand, Hong Kong, Singapore, and UK. Results indicate that HOEs impact risks in active systems up to ~33%. Large variations are observed in the reliability of active systems due to HOEs over time. SD results indicate that a small behavioral change in ’risk perception’ of a building management team can lead to a very large risk to life variations over time through the self-reinforcing feedback loops. The quantification of difference in expected risk to life due to technical, human, and organizational risks for seven buildings for each of 16 trial designs is a novel aspect of this study. The research is an important contribution to the development of the next generation building codes and risk assessment methods.
Publisher: MDPI AG
Date: 15-08-2022
DOI: 10.3390/FIRE5040116
Abstract: This paper presents work on investigating the effect of the initial size of water mist droplets on the evaporation and removal of heat from the fire-induced hot gas layer while travelling through the air in a compartment. The histories of the temperature, diameter and position of droplets with different initial diameters (varied from 100 µm to 1000 µm) are determined considering surrounding air temperatures of 75 °C and 150 °C and a room height of 3.0 m. A water droplet evaporation model (WDEM) developed in a previous study (Fire and Materials 2016 40:190–205) is employed to navigate this work. The study reveals that tiny droplets (for ex le, 100 µm) have disappeared within a very short time due to evaporation and travelled a very small distance from the spray nozzle because of their tiny size. In contrast, droplets with a larger diameter (for ex le, 1000 µm) reached the floor with much less evaporation. In the case of this study, the relative tiny droplets (≤200 µm) have absorbed the highest amount of energy from their surroundings due to their complete evaporation, whereas the larger droplets have extracted less energy due to their smaller area/volume ratios, and their traverse times are shorter. One of the key findings of this study is that the smaller droplets of spray effectively cool the environment due to their rapid evaporation and extraction of heat from the surroundings, and the larger droplets are effective in traversing the hot air or smoke layer and reaching the floor of the compartment in a fire environment. The findings of this study might help in understanding the behaviour of water-mist droplets with different initial diameters in designing a water-mist nozzle.
Publisher: Springer Science and Business Media LLC
Date: 23-01-2118
Publisher: MDPI
Date: 30-08-2022
Publisher: Springer Science and Business Media LLC
Date: 09-2023
Publisher: Elsevier BV
Date: 05-2003
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/WF20091
Publisher: Springer Science and Business Media LLC
Date: 13-10-2023
Publisher: SPIE
Date: 09-08-2013
DOI: 10.1117/12.2027959
Publisher: Elsevier BV
Date: 07-2017
Publisher: Elsevier BV
Date: 12-2022
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/WF17126
Abstract: Grid-independent rate of spread results from a physics-based simulation are presented. Previously, such a numerical benchmark has been elusive owing to computational restrictions. The grid-converged results are used to systematically construct correlations between the rate of spread (RoS) and both wind speed and grass height, separately. The RoS obtained from the physics-based model is found to be linear with wind speed in the parameter range considered. When wind speed is varied, the physics-based model predicts faster RoS than the Mk III and V (McArthur) models (Noble et al. 1980) but slower than the CSIRO model (Cheney et al. 1998). When the grass height is varied keeping the bulk density constant, the fire front changes from a boundary layer flame mode to plume flame mode as the grass height increases. Once the fires are in plume mode, a higher grass height results in a larger heat release rate of the fire but a slower RoS.
Publisher: Inderscience Publishers
Date: 2011
Publisher: Elsevier BV
Date: 02-2008
Publisher: MDPI AG
Date: 16-01-2023
DOI: 10.3390/FIRE6010035
Abstract: Appropriate estimates of ignition frequency derived from fire statistics are crucial for quantifying fire risks, given that ignition frequency underpins all probabilistic fire risk assessments for buildings. Rahikainen et al. (Fire Technol 2004 40:335–53) utilized the generalized Barrois model to evaluate ignition frequencies for different buildings in Finland. The Barrois model provides a good prediction of the trend of the ignition frequency however, it can underestimate the ignition frequency depending on the building type. In this study, an analysis of the Australian fire statistical data from 2012 to 2019 was performed and compared with studies from Finland. A new coefficient is proposed to improve the Barrois model for a better fit for buildings in Australia. Several categories, such as hotels and hospitals, which were absent in previous studies, have been included as separate categories in this study. Office and retail spaces in Finland have an ignition frequency one order of magnitude lower than in Australia. On the other hand, other buildings (retail and apartments in particular) are much more prone to fire ignition in Australia than in Finland. The improved generalized Barrois model based on the Australian fire statistical data will be useful for determining ignition frequency for risk quantification in the Australian context.
Publisher: Elsevier BV
Date: 11-2023
Publisher: CSIRO Publishing
Date: 02-03-2023
DOI: 10.1071/WF22121
Abstract: Background Junction fires occur when two fire fronts merge. The rate of spread (ROS) and heat release rate (HRR) of the junction increase more quickly than that of each fire front, this effect exacerbated by slopes. Aims Numerical modelling of junction fires and an interpretation of their behaviour are given examining the key influencing factors. Methods Twenty physics-based simulations of laboratory-scale junction fires were performed for a shrub fuel bed using FIRESTAR3D, varying slope (0°–40°) and junction angles (15°–90°). Key results Accelerative and decelerative behaviours were observed for junction angles lower than 45°, but above this, deceleration was absent. The behaviour was firmly related to junction angle evolution, which controlled the flame and interactions between fire fronts. HRR followed similar trends maximum HRR increased with increasing junction angle. Convection was the primary heat transfer mode in the initial propagation phase. In no-slope cases, radiation was the dominant method of heat transfer, but convection dominated fires on slopes. Conclusions The physics-based model provided great insight into junction fire behaviour. The junction angle was critical for determining ROS and fire behaviour. Implications The research helped to assess the effects of some topographical parameters in extreme fires. Situational awareness, operational predictions and firefighter safety will consequently improve.
Publisher: Elsevier BV
Date: 11-2023
Publisher: ASMEDC
Date: 2002
Abstract: This work continues the studies of Moinuddin et al. [1], where experiments were performed on a streamwise external corner. The streamwise development of turbulent boundary layer over an external corner (chine) is influenced by secondary flow which is driven three-dimensionally. The direct effect of this secondary flow is to increase the drag force. Here secondary flow, which is known as Prandtl’s second kind, is induced by inequality of Reynolds stresses around the corner. This flow is expected to exhibit symmetry about the corner bisector. Moinuddin et al. [2,3] have established the symmetry of this flow based upon mean flow measurements. Normal wire measurements for the streamwise turbulence intensity profiles u′2+, measured at about Reθ 5700 and 4.7 m from the model leading edge, are presented in this paper. Mean flow measurements show excellent agreement between Pitot tube and normal wire measurements. Comparisons are made for u′2+, profiles at equal spanwise distance, from the corner, on both surfaces. The profiles agree quite well having nominal deviation depending on spanwise and normal distance from the corner. Isointensity contours also depict symmetrical turbulence distribution. It is also revealed that far from the corner, turbulence profiles agree well with the standard two-dimensional turbulence profile. The measurements agrees with the general behaviour expected from this kind of flow as reported by Xu & Pollard [4] from their LES calculation of flow in an annular square duct.
Publisher: Elsevier BV
Date: 2014
Publisher: Wiley
Date: 29-10-2014
DOI: 10.1002/FAM.2279
Publisher: CSIRO Publishing
Date: 21-02-2023
DOI: 10.1071/WF22009
Abstract: Homogeneous vegetation is widely used in wildland fire behaviour models, although real vegetation is heterogeneous in nature and composed of different kinds of fuels and non-combustible parts. Many features of fires can arise from this heterogeneity. For land management and firefighting, creating heterogeneous fuel areas may be useful to reduce fire intensity and rate of spread (ROS), and alter fire geometry. Recently, an empirical model for fire spread in spinifex grasslands was developed and validated against experimental measurements. In this study, physics-based grassland fire behaviour simulations were conducted with varying percentages of fuel cover and alternating square and rectangular patches of burnable and non-burnable material. The environmental conditions and thermophysical properties of the grassland were kept constant throughout the simulation to separate the effects of fuel heterogeneities from other parameters. For three sets of nominal wind velocities, 3, 5.6 and 10 m s−1, we identified ‘go’ and ‘no go’ fires. Reasonable agreement between the non-dimensionalised simulated ROS and observed ROS in spinifex was found. There is a significant reduction of fire intensity, ROS, flame length, fire width and fire line length due to the heterogeneous effect of vegetation.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 08-2024
Publisher: SAGE Publications
Date: 05-2007
Publisher: Elsevier BV
Date: 11-2011
Publisher: AIP Publishing
Date: 11-2007
DOI: 10.1063/1.2803346
Abstract: Turbulent boundary layer development, with zero pressure gradient, over an orthogonal external corner was investigated both experimentally and numerically. The results suggest that within the experimental and numerical limitations of the study that a similarity solution for the mean streamwise velocity profile exists along an external corner bisector. However, to confirm the self-similar solution, further independent measurement of the wall shear stress would be required. For the numerical simulation the Reynolds stress model was used. The experimental and numerical results were all consistent with a logarithmic self-similar solution. However the constants appearing in the self-similar solution were found to differ between the experimental and numerical results and reasons for these discrepancies are discussed. The results also provide scope for benchmarking of commercial software packages against a generic three-dimensional turbulent boundary layer that occurs in many engineering applications.
Publisher: BMJ
Date: 05-09-2019
Publisher: Wiley
Date: 07-06-2020
DOI: 10.1111/NPH.16661
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 05-2018
Publisher: Springer Science and Business Media LLC
Date: 09-12-2019
Publisher: American Physical Society (APS)
Date: 23-10-2023
Publisher: American Physical Society (APS)
Date: 13-10-2023
Publisher: Elsevier BV
Date: 11-2023
Publisher: American Physical Society (APS)
Date: 11-10-2023
Start Date: 2020
End Date: 2021
Funder: Defence Science Institute
View Funded ActivityStart Date: 2021
End Date: 2024
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 2024
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2021
End Date: 12-2024
Amount: $250,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2021
End Date: 08-2024
Amount: $590,000.00
Funder: Australian Research Council
View Funded Activity