@article {bnh-8372, title = {Physics-based simulations of grassfire propagation on sloped terrain at field scale: flame dynamics, mode of fire propagation and heat fluxes}, journal = {International Journal of Wildland Fire}, year = {2023}, month = {01/2023}, 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{\textquoteright}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.

}, keywords = {Byram number, fire propagation, flame, grassfire, heat fluxes, plume, rate of spread (RoS), slope, wind velocity}, doi = {https://doi.org/10.1071/WF21125}, url = {https://www.publish.csiro.au/wf/WF21125$\#$FN1}, author = {Jasmine Innocent and Duncan Sutherland and Nazmul Khan and Khalid Moinuddin} } @article {bnh-8375, title = {Physics-based simulations of grassfire propagation on sloped terrain at field scale: motivations, model reliability, rate of spread and fire intensity}, journal = {International Journal of Wildland Fire}, year = {2023}, month = {01/2023}, 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{\textendash}urban Interface Fire Dynamics Simulator (WFDS), with varying wind speeds (12.5, 6 and 3 m s-1) and slope angles (-30{\textdegree} to +30{\textdegree}). 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{\textendash}fire intensity relationship (Byram{\textquoteright}s) deviates from linearity for greater upslopes.

}, keywords = {Fire behaviour, fire front, grass fire, intensity, rate of spread (RoS) of fire, simulations, slope, wind speed}, doi = {https://doi.org/10.1071/WF21124}, url = {https://www.publish.csiro.au/wf/WF21124}, author = {Jasmine Innocent and Duncan Sutherland and Nazmul Khan and Khalid Moinuddin} } @article {bnh-8367, title = {Simulated behaviour of wildland fire spreading through idealised heterogeneous fuels}, journal = {International Journal of Wildland Fire}, year = {2023}, month = {02/2023}, 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 {\textquoteleft}go{\textquoteright} and {\textquoteleft}no go{\textquoteright} 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.

}, keywords = {fire line length, flame length, heterogeneity, homogeneous vegetation, Rate of spread, spinifex, wildland fire, wind spee}, doi = {https://doi.org/10.1071/WF22009}, url = {https://www.publish.csiro.au/wf/WF22009}, author = {Nazmul Khan and Duncan Sutherland and Khalid Moinuddin} } @article {bnh-8376, title = {Determining firebrand generation rate using physics-based modelling from experimental studies through inverse analysis}, journal = {Fire}, volume = {5}, year = {2022}, month = {01/2022}, 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.

}, keywords = {FDS, Firebrands, physics-based modeling, wildland fire, Wildland-urban interface}, doi = {https://doi.org/10.3390/fire5010006}, url = {https://www.mdpi.com/2571-6255/5/1/6}, author = {Amila Wickramasinghe and Nazmul Khan and Khalid Moinuddin} } @article {bnh-8373, title = {A review of firebrand studies on generation and transport}, journal = {Fire Safety Journal}, volume = {134}, year = {2022}, month = {09/2022}, abstract = {

Firebrands play a vital role in the propagation of fire by starting new fires called spotfires, ahead of the fire front during wildfire progression. Firebrands are a harbinger of damage to infrastructure; their effects particularly pose a threat to people living within the wildland-urban-interface, they can hamper the suppression of wildfire and block evacuation routes for communities and emergency services. Short-range firebrands which travel along with the wind, with little or no lofting, are particularly crucial in increasing fire front propagation and damaging structures situated close to the wildland-urban interface. In the Daylesford fire of 1962 in Australia, massive short-range spotting (the process of spot fire ignition and merging of spots caused by firebrands) occurred in the eucalyptus forest and increased the rate of fire spread by roughly three times more than that computed using an operational fire model. Similarly, long-range firebrands can be transported by the fire plume and ambient wind and can ignite new fire up to 30{\textendash}40\ km from the source of fire as observed in the 2009 Black Saturday fire in Australia.

A large amount of experimental research has been conducted to quantify the effects of firebrands, to develop empirical models and to benchmark results for\ Computational Fluid Dynamic\ (CFD) based fire model validations. In recent years, some CFD models have been studied primarily for their validation purposes. These studies have been reviewed here. To perform useful\ parametric studies\ of firebrand transport using CFD models as well as further development of CFD models, more targeted studies need to be conducted.

}, keywords = {firebrand generator, Firebrand spotting, Firebrand transport, wildfires}, doi = {https://doi.org/10.1016/j.firesaf.2022.103674}, url = {https://www.sciencedirect.com/science/article/pii/S0379711222001515}, author = {Rahul Wadhwani and Catherine Sullivan and Amila Wickramasinghe and Matthew Kyng and Nazmul Khan and Khalid Moinuddin} } @article {bnh-7996, title = {Fire spread across different fuel types: research and utilisation {\textendash} final project report}, number = {668}, year = {2021}, month = {05/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

It is crucial for emergency and disaster management organisations to predict of the rate of spread and intensity of bushfires for operational planning, community warnings and the deployment of their resources. Currently, this is achieved by simulation using simplified operational models that have the useful attribute of providing results on time scales commensurate with those required by emergency managers. However, when Cruz \& Alexander [1] reviewed the performance of the operational fire models used by fire and emergency service analysts on seven vegetation types found in Australia, they found that on an average most of the fire models have an error of 20{\textendash}80\% in estimating the rate of fire spread. These differences in prediction are due to the assumptions and limitations of these models. Therefore, it is essential that these simplified operational tools be refined so that they can better predict fire behaviour. Additionally, a more physically based firebrand model needs to be included in operational models to predict firebrand distribution and subsequent spotting, which lead to an increased rate of fire spread (ROS). Currently, no such model exists. With an increased population in the rural{\textendash}urban interface (or wildland{\textendash}urban interface, WUI), it is also important to understand the vulnerability of houses from radiant heat and firebrand flux in order to minimise such vulnerability.

In this project, we tested two established reliable physics-based models: Fire Dynamics Simulator (FDS) and FIRESTAR3D to simulate bushfire scenarios in three broad areas:

(1)\  sub-canopy wind flow,

(2)\  firebrand transport, and

(3)\  propagation of grass and forest fires.

We have made significant inroads into providing usable outputs as well understanding various aspects of bushfire behaviour. The following are particular highlights:

This project was also established to create a capability and capacity in Australia to conduct research and understand physical-based wildfire modelling approaches. There are several international groups developing these models, and it is imperative that Australia can interact and work alongside these researchers to translate the findings to the Australian context.

Overall, we have achieved our goal of obtaining greater insight into bushfire physics and we are now utilising those insights to parameterise various phenomena for operational models.

This report explains these issues in more detail.

[1] Meaning WRF will vary for the geographical location and driving wind velocity and direction

}, keywords = {Fire, fuel, research, spread, types, utilisation}, issn = {668}, author = {Nazmul Khan and Amila Wickramasinghe and Mahmood Rashid and Khalid Moinuddin} } @article {bnh-8157, title = {Numerical study on effect of relative humidity (and fuel moisture) on modes of grassfire propagation}, journal = {Fire Safety Journal}, year = {2021}, month = {08/2021}, abstract = {

Relative humidity of air is directly related to fuel moisture. Fuel moisture is often considered as the index of flammability in the context of bushfire. Variation of relative humidity and fuel moisture is considered to have a significant effect on the rate of spread of grassfire propagation and fire intensity. In this study, four sets of grassfire simulations have been conducted: three sets with 210 mm high grass and another set with 175 mm high grass. For all sets, the ambient temperature was kept constant while relative humidity and fuel moisture were varied, with fuel moisture deduced from the McArthur MKV GFDI model. With 210 mm grass heights, driving wind velocities were varied. Lower relative humidity (and fuel moisture) was observed to lead to higher fire intensity and a faster rate of spread, which are intuitively expected. Byram number analysis showed that relative humidity (and fuel moisture) can lead to change in the fire propagation mode (wind-driven vs buoyancy-driven), but the greater factor is the wind velocity.

}, keywords = {Byram number, grassfire, Mode of fire propagation, Physics-based modelling, relative humidity}, doi = {https://doi.org/10.1016/j.firesaf.2021.103422}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0379711221001636}, author = {Khalid Moinuddin and Nazmul Khan and Duncan Sutherland} } @article {bnh-6819, title = {Physics-based simulation of firebrand and heat flux on structures in the context of AS3959}, number = {560}, year = {2020}, month = {04/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Firebrand is known as one of the most dangerous airborne components of wildfires having the potential to ignite structures in Wildland-Urban Interface (WUI). Quantifying the firebrand and heat flux on structures is essential to determine the wildfire risks and prepare strategic plans to mitigate the hazard. We endeavor to use a physics-based model, Fire Dynamic Simulator (FDS) to map firebrand and heat flux to determine the vulnerability of structures in WUI. In this study, we have validated FDS{\textquoteright} tree burning and firebrand transporting sub-models against the experiment conducted in no wind condition at the National Institute of Standards and Technology (NIST). The experimental data of firebands were processed to use as inputs in the numerical simulation and the grid convergence was appraised in terms of mass loss rate (MLR). The intial velocity and direction of firebrands, the number of generations were determined as model inputs by a reverse analysis through comparing firebrand distribution with the experiment. As the FDS{\textquoteright} sub-models were validated, we attempted to quantify the heat flux and firebrand risk on a structure at three different driving wind velocities. Increasing wind speed showed more firebrands transported towards the structure but none of them landed on the house because of the low height of the tree and insufficiency of fire-induced buoyancy to lift them enough to carry a longer distance by the wind field. Similarly, heat flux computed on the structure is well below Australian building standard AS3959{\textquoteright}s bushfire attack level (BAL). it is due to the low heat release by single tree burning instead of a 100m wide fire line assumed in the standard. In future study, simulations will be conducted with a cluster of taller trees (100m wide) to quantify the heat flux and firebrand hazard on structures to apprise AS3959.

}, keywords = {firebrand, heat flux, physics simulation, structures}, issn = {560}, author = {Amila Wickramasinghe and Nazmul Khan and Khalid Moinuddin} } @article {bnh-6638, title = {Recirculation regions downstream of a canopy on a hill}, number = {538}, year = {2020}, month = {01/2020}, institution = {Bushfire \& Natural Hazards CRC}, address = {Melbourne}, abstract = {

The large eddy simulation (LES) is performed to study the flow characteristics of atmospheric boundary layer over forested hills. The sparse and dense canopies are introduced in the hill structure and modelled by homogenous leaf area density. A pressure driven flow is established under neutrally stratified condition to explore the effect of hill and canopy induced perturbations including velocity speed-up, separation, attachment and recirculation. The presence of recirculation zone in the lee side of the can change the behavior of the flow field significantly. To be specific, the smoke and firebrand transport, spotfire ignition and fire intensity can be influenced by the formation of recirculation zone in the lee side forested hill. Moreover, the flow separation and attachment in the lee side of the hill or in near forest clearing can change the fire behavior and rate of spread significantly. This study extends previously developed physics-based simulations for the flow through forest canopies over flat surfaces by Duncan et al. [1] with inclusion of hilly terrains. The motivation is to develop a predictive model for the firebrand transport and spotfire ignition model extending the previous work of Rahul et al. [2], where a physics based firebrand model is developed and validated against laboratory-scale experimental data. How the recirculation can affect the formation and growth of firebrand transport and spotfire ignition in the hilly terrain is the long-term goal of this study. The streamwise mean velocity is increases with increases of hill height and canopy densities over a forested hill. The flow recirculation zone is nicely captured on the lee side of the hill with various degrees of size and shape with respect to vegetation densities and hill sizes. The size and shape of the recirculation zones largely depend on the steepness of the hill although canopy density has some contribution as well. The results of streamwise mean velocities, mean pressure, Reynolds stresses and streamlines of velocity fields are captured in this study, which are qualitatively in good agreement with the existing literature. Overall the simulation results show the applicability of FDS in such complex simulation that can be used in future studies for the fire simulation of hilly terrain.

}, keywords = {canopy, downstream, fire simulation, hilly terrain, recirculation}, issn = {538}, author = {Nazmul Khan and Duncan Sutherland and Khalid Moinuddin} } @article {bnh-6642, title = {A report on WRF software development (preliminary)}, number = {539}, year = {2020}, month = {01/2020}, institution = {Bushfire \& Natural Hazards CRC}, address = {Melbourne}, abstract = {

Bushfire is one of the major natural hazards Australia encounters every year because of its dry weather and widespread bushlands. During the dry season, occurrence of simultaneous bushfires at different locations is quite common. The fire management authorities face challenges on deployment of resources (human and other logistics) properly to mitigate multiple bushfires. To prioritize, they depend on the modelling of real-time behaviours of the fire under consideration. Fire rate of spread (RoS) is one of the most important parameters that the authority wants to determine before proceeding to resource allocation. RoS during forest fire can be slowed by reduced sub-canopy wind. In operational models, it is accounted by a parameter, wind reduction factor (WRF). Current values used as WRF are not based on science. In this work, we are presenting a software (preliminary version) that can calculate WRF scientifically. We apply a dynamic WRF obtained from a mathematical model in an operation model, Spark. This will lead to better prediction of RoS, once fully implemented.

}, keywords = {Bushfire, fire management, model, Rate of spread, software development}, issn = {539}, author = {Mahmood Rashid and James Hilton and Nazmul Khan and Duncan Sutherland and Khalid Moinuddin} } @article {bnh-6830, title = {Simulation of flows through canopies with varying atmospheric stability}, number = {562}, year = {2020}, month = {04/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Large eddy simulation is performed of a flow through forest canopy over a range of atmospheric stabilities. A heat source is introduced at the top of the tree canopy to model the heating of canopy top by solar energy, Unlike our previous report [1] where an ideal Monin-Obukhov method was used for the surface heat flux variation, this study has introduced a varying volumetric heat flux in a sub-canopy region. The flow field develops naturally with the applied thermal stratification and pressure-driven flow. The forest canopy modelled using the leaf area density (LAD) of pine trees. The simulation is allowed for a sufficient time, of the order of 20000 s, to adjust with the applied heat flux in the domain. The simulation is attempted for two broad classes: stable and unstable situations with varying negative and positive fluxes, respectively. The simulation results are validated against the numerical study of Nebenfuhr et al. [2] and the field measurement taken at Ryningsnas, Sweden [3]; which shows a good agreement. The effect of canopy top heat flux on different atmospheric stabilities are studied in detail and we present mean velocity and Reynolds stresses. These results suggest that atmospheric stability may affect the rate of spread and pollution dispersion, especially in the case of unstable stratifications. There is a need to understand atmospheric stabilities for accurate analysis of wildland fire spread and fire intensity. Most importantly, flame characteristics must be carefully diagnosed with due account for different atmospheric conditions prevailing in real wildland fire for reducing property damage and loss of lives.

}, keywords = {atmospheric boundary layer, forest canopy, thermal stratification, turbulence, turbulent kinetic energy}, issn = {562}, author = {Nazmul Khan and Duncan Sutherland and Khalid Moinuddin} } @article {bnh-5675, title = {Physics-Based Simulation of Heat Load on Structures for Improving Construction Standards for Bushfire Prone Areas}, journal = {Frontiers in Mechanical Engineering}, volume = {5}, year = {2019}, month = {06/2019}, abstract = {

Australian building standard AS 3959 provides mandatory requirements for the construction of buildings in bushfire prone areas in order to improve the resilience of the building to radiant heat, flame contact, burning embers, and a combination of these three bushfire attack forms. The construction requirements are standardized based on the bushfire attack level (BAL). BAL is based on empirical models which account for radiation heat load on structure. The prediction of the heat load on structure is a challenging task due to many influencing factors: weather conditions, moisture content, vegetation types, and fuel loads. Moreover, the fire characteristics change dramatically with wind velocity leading to buoyancy or wind dominated fires that have different dominant heat transfer processes driving the propagation of the fire. The AS 3959 standard is developed with respect to a quasi-steady state model for bushfire propagation assuming a long straight line fire. The fundamental assumptions of the standard are not always valid in a bushfire propagation. In this study, physics based large-eddy simulations were conducted to estimate the heat load on a model structure. The simulation results are compared to the AS 3959 model; there is agreement between the model and the simulation, however, due to computational restrictions the simulations were conducted in a much narrower domain. Further simulations were conducted where wind velocity, fuel load, and relative humidity are varied independently and the simulated radiant heat flux upon the structure was found to be significantly greater than predicted by the AS 3959 model. The effect of the mode of fire propagation, either buoyancy-driven or wind dominated fires, is also investigated. For buoyancy dominated fires the radiation heat load on the structure is enhanced compared to the wind dominated fires. Finally, the potential of using physics based simulation to evaluate individual designs is discussed.

}, keywords = {building standards, emissions, forest fire, physics-based simulation, wildland fire, wildfire, fire spread}, doi = { https://doi.org/10.3389/fmech.2019.00035}, url = {https://www.frontiersin.org/articles/10.3389/fmech.2019.00035/full}, author = {Nazmul Khan and Duncan Sutherland and Rahul Wadhwani and Khalid Moinuddin} } @article {bnh-5477, title = {A preliminary report on simulation of flows through canopies with varying atmospheric stability}, number = {469}, year = {2019}, month = {03/2019}, institution = {Bushfire and Natural hazards CRC}, address = {Melbourne}, abstract = {

Large eddy simulation is performed for a flow through forest canopy applying various atmospheric stability conditions. The canopy is modelled as a horizontally homogenous region of aerodynamic drag with a leaf-area density (LAD) profile approximating the profile of a Scots pine tree. Varying atmospheric stability is incorporated into the simulation by applying varying heat flux in two different ways; (i) a surface heat flux prescription using Monin-Obukhov similarity functions and, (ii) a canopy heat flux model where heat from the canopy is modelled as distributed volume heat source. When the surface heat flux was prescribed, five stability classes: very unstable, unstable, neutral, stable and very stable are modelled while for canopy heat flux model three classes: stable, unstable and neutral are simulated for this study. We observe, realistically, that the stable and very stable velocity profiles are leaned towards right to neutral velocity profile indicating wind dominated flow. On the other hand, unstable and very unstable velocity profiles become more vertical indicating buoyancy dominated flow. In all velocity profiles, an inflection point is observed in the dense canopy region. Expected variations in the temperature profiles are also observed {\textendash} higher near-ground temperature for unstable and very unstable cases and converse is true for stable and very stable cases. Simulations involving exponential heat source variation vertically for forest canopy is ongoing for validation with experimental data and other similar studies. Once validation is obtained, parametric study with various atmospheric stability can be carried out in order to improve operational models. \ 

}, keywords = {atmospheric surface layer, forest canopy, thermal stratification, turbulence, turbulent kinetic energy}, author = {Nazmul Khan and Duncan Sutherland and Jimmy Philip and Andrew Ooi and Khalid Moinuddin} } @article {bnh-4976, title = {Improvements to wind field generation in physics-based models to reduce spin-up time and to account for terrain, heated earth surface}, year = {2018}, month = {10/2018}, institution = {Bushfire and Natural Hazards CRC}, abstract = {

Wind is one of the most important environmental variables that affects the wildland fire spread and intensity. Previously, fire analysts and managers have relied on local measurements and site-specific forecasts to determine winds influencing a fire. However, advances in computer hardware increased the availability of electronic topographical data, and advances in numerical methods for computing winds have led to the development of new tools capable of simulating wind flow. Several numerical models have been developed for fire prediction. The most widely used physics-based models come with a limitation of computational expenses, because of which these are not suitable for operational use. Our main intention of this study is to reduce this limitation of physics-based models so that fire forecasts can be made faster and easier. Modelling wind in physics-based models such as Fire Dynamics Simulator (FDS) has been shown to reproduce promising results, but at an inordinate cost. So, we will be using FDS as physics-based model to simulate fire. There are various methods available to generate wind field in FDS. The conventional methods of wind field generation are either an unperturbed inlet profile with a roughness-trip or the by embedding artificial turbulence at the inlet. The wind fields generated by these inlet conditions are compared with each other as well as to the wind field generated using a mean-forcing method for neutral atmospheric conditions. We have then used these inlet conditions to study the effects of fire spread in FDS. Currently, we are working on introducing a method in FDS known as penalization method, so that we can use real time wind data from other wind models, such as Windninja into FDS and perform fire simulations. Our hypothesis is that introduction of this method would reduce the simulation time of fire cases to some extent and moreover can include terrain effect in the wind profiles.

}, issn = {415}, author = {Khalid Moinuddin and Sesa Singha Roy and Duncan Sutherland and Nazmul Khan} }