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“Computer Graphics and Evidence Presentation” Abstract In the UK forensic animations are becoming an increasingly important visual aid in courtroom situations, where complex data relating to a sequence of events is being visualised before a general public who may have little or no understanding of established forensic procedure or methodology. This paper will introduce and discuss a spectrum of new technologies that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for a range of incident investigation and presentation scenarios.

Abstract

In the UK forensic animations are becoming an increasingly important visual aid in courtroom situations,where complex data relating to a sequence of events is being visualized before a general public who may have little or no understanding of established forensic procedure or methodology. This paper will introduce and discuss a spectrum of new technologies that use new developments in Computer Graphics (CG) and Virtual Reality (VR) for a range of incident investigation and presentation scenarios.

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The detection of adulteration of fuels and its use in criminal scenes like arson has a high interest in forensic investigations. In this work, a method based on gas chromatography (GC) and neural networks (NN) has been developed and applied to the identification and discrimination of brands of fuels such as gasoline and diesel without the necessity to determine the composition of the samples. The study included five main brands of fuels from Spain, collected from fifteen different local petrol stations. The methodology allowed the identification of the gasoline and diesel brands with a high accuracy close to 100%, without any false positives or false negatives. A success rate of three blind samples was obtained as 73.3%, 80%, and 100%, respectively. The results obtained demonstrate the potential of this methodology to help in resolving criminal situations.

Research Article

The detection of adulteration of fuels and its use in criminal scenes like arson has a high interest in forensic investigations. In thiswork, a method based on gas chromatography (GC) and neural networks (NN) has been developed and applied to the identification and discrimination of brands of fuels such as gasoline and diesel without the necessity to determine the composition of the samples.The study included five main brands of fuels from Spain, collected from fifteen different local petrol stations. The methodology allowed the identification of the gasoline and diesel brands with a high accuracy close to 100%, without any false positives or false negatives. A success rate of three blind samples was obtained as 73.3%, 80%, and 100%, respectively. The results obtained demonstrate the potential of this methodology to help in resolving criminal situations.

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Abstract

Free-burning experimental fires were conducted in a wind tunnel to explore the role of ignition type and thus fire spread mode on the resulting emissions profile from combustion of fine (< 6 mm in diameter) Eucalyptus litter fuels. Fires were burnt spreading with the wind (heading fire), perpendicular to the wind (flanking fire) and against the wind (backing fire). Greenhouse gas compounds (i.e. CO2, CH4 and N2O) and CO were quantified using off-axis integratedcavity-output spectroscopy. Emissions factors calculated using a carbon mass balance technique (along with statistical testing) showed that most of the carbon was emitted as CO2, with heading fires emitting 17 % more CO2 than flanking and 9.5 % more CO2 than backing fires, and about twice as much CO as flanking and backing fires. Heading fires had less than half as much carbon remaining in combustion residues. Statistically significant differences in CH4 and N2O emissions factors were not found with respect to fire spread mode. Emissions factors calculated per unit of dry fuel consumed showed that combustion phase (i.e. flaming or smouldering) had a statistically significant impact, with CO and N2O emissions increasing during smouldering combustion and CO2 emissions decreasing. Findings on the equivalence of different emissions factor reporting methods are discussed along with the impact of our results for emissions accounting and potential sampling biases associated with our work. The primary implication of this study is that prescribed fire practices could be modified to mitigate greenhouse gas emissions from forests by judicial use of ignition methods to induce flanking and backing fires over heading fires.

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INTRODUCTION This report describes new full-scale compartment fire experiments, which include local measurements of temperature, heat flux and species composition, and global measurements of heat release rate and mass burning rate. The measurements are unique to the compartment fire literature. By design, the experiments provided a comprehensive and quantitative assessment of major and minor carbonaceous gaseous species and soot at two locations in the upper layer of fire in a full scale ISO 9705 room [1]. Fire protection engineers, fire researchers, regulatory authorities, fire service and law enforcement personnel use fire models (such as the NIST Fire Dynamics Simulator, FDS[2]) for design and analysis of fire safety features in buildings and for post-fire reconstruction and forensic applications. Fire field models have historically showed limited ability to accurately and reliably predict the thermal conditions and chemical species in underventilated compartment fires. Formal validation efforts have shown that for well ventilated compartment fires, with the exception perhaps of soot, field models do quite well in predicting temperature and species when experimental uncertainty is accounted for. Inaccurate predictions of incomplete burning and soot levels impact calculations of radiative heat transfer, burning rates, and estimates of human tenability. High-quality (relatively low, quantified uncertainty) measurements of fire gas species, temperature, and soot from the interior of underventilated compartment fires are needed to guide the development and validation of improved fire field models.

Introduction

This report describes new full-scale compartment fire experiments, which include localmeasurements of temperature, heat flux and species composition, and global measurements ofheat release rate and mass burning rate. The measurements are unique to the compartment fireliterature. By design, the experiments provided a comprehensive and quantitative assessment ofmajor and minor carbonaceous gaseous species and soot at two locations in the upper layer offire in a full scale ISO 9705 room [1].

Fire protection engineers, fire researchers, regulatory authorities, fire service and lawenforcement personnel use fire models (such as the NIST Fire Dynamics Simulator, FDS[2]) fordesign and analysis of fire safety features in buildings and for post-fire reconstruction andforensic applications. Fire field models have historically showed limited ability to accuratelyand reliably predict the thermal conditions and chemical species in underventilated compartmentfires. Formal validation efforts have shown that for well ventilated compartment fires, with theexception perhaps of soot, field models do quite well in predicting temperature and species whenexperimental uncertainty is accounted for. Inaccurate predictions of incomplete burning and sootlevels impact calculations of radiative heat transfer, burning rates, and estimates of humantenability. High-quality (relatively low, quantified uncertainty) measurements of fire gasspecies, temperature, and soot from the interior of underventilated compartment fires are neededto guide the development and validation of improved fire field models.

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From Out of the Abyss...

This week’s article from the past is titled Incendiary Fires Can Be Spotted and was written by Benjamin Horton, CPCU, who was President of the National Adjuster Traing School in Louisville, Kentucky..  It is taken from the Decembe 1968 Vol. XVI No.5 issue.

Incendiary Fires Can Be Spotted 

ABSTRACT The open kitchen design in small residential units where fire load density and occupant load are very high introduces additional fire risk. One big concern is that whether flash-over can occur which may trigger a big post flashover fire, resulting in severe casualties and big property damage. It is important to understand and predict the critical conditions for flashover in this kind of units. Based on a two-layer zone model, the probability of flashover is investigated by a nonlinear dynamical model. The temperature of the smoke layer is taken as the only state variable and the evolution equation is developed in the form of a simplified energy balance equation for the hot smoke layer. Flashover is considered to occur at bifurcation points. Then the influence of the floor dimensions and the radiation feedback coefficient on flashover conditions is examined. When the dimensions of the floor vary, the resulting changes in internal surface area or size of floor area both have effect on the flashover conditions. When the radiation feedback coefficient is of small value, there is no possibility of flashover. With the increase of the radiation feedback coefficient, at first it significantly affects the conditions for flashover and then moderately when it reaches a larger value. It is proved that the flashover phenomenon can be demonstrated well by nonlinear dynamical system and it helps to understand the effect of various control parameters.

Abstract

The open kitchen design in small residential units where fire load density and occupant load are very high introduces additional fire risk. One big concern is that whether flash-over can occur which may trigger a big post flashover fire, resulting in severe casualties and big property damage. It is important to understand and predict the critical conditions for flashover in this kind of units. Based on a two-layer zone model, the probability of flashover is investigated by a nonlinear dynamical model. The temperature of the smoke layer is taken as the only state variable and the evolution equation is developed in the form of a simplified energy balance equation for the hot smoke layer. Flashover is considered to occur at bifurcation points. Then the influence of the floor dimensions and the radiation feedback coefficient on flashover conditions is examined. When the dimensions of the floor vary, the resulting changes in internal surface area or size of floor area both have effect on the flashover conditions. When the radiation feedback coefficient is of small value, there is no possibility of flashover.  With the increase of the radiation feedback coefficient, at first it significantly affects the conditions for flashover and then moderately when it reaches a larger value. It is proved that the flashover phenomenon can be demonstrated well by nonlinear dynamical system and it helps to understand the effect of various control parameters.

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