Patel P.,University of Central Lancashire |
Hull T.R.,University of Central Lancashire |
Stec A.A.,University of Central Lancashire |
Lyon R.E.,William ghes Technical Center
Polymers for Advanced Technologies | Year: 2011
The relationship between physical properties and fire performance as measured in the cone calorimeter is not well understood. A number of studies have identified relationships between the physical and chemical properties of polymeric materials and their gasification behavior which can be determined through numerical pyrolysis models. ThermaKin, a one-dimensional pyrolysis model, has recently been employed to predict the burning behavior in fire calorimetry experiments. The range of thermal, chemical, and optical properties of various polymers have been utilized to simulate the processes occurring within a polymer exposed to a uniform heat flux, such as in a cone calorimeter. ThermaKin uses these material properties to predict the mass flux history in a cone calorimeter. Multiplying the mass flux history by the heat of combustion of the fuel gases gives the HRR history and these have been calculated for cone calorimeter experiments at 50kWm-2 incident heat flux for the lowest, average, and highest values of physical parameters exhibited by common polymers. In contrast with actual experiments in fire retardancy, where several parameters change on incorporation of an additive, this study allows for the effect of each parameter to be seen in isolation. The parameters used in this study are grouped into physical properties (density, heat capacity, and thermal conductivity), optical properties (absorption and reflectivity), and chemical properties (heat of decomposition, kinetic parameter, and heat of combustion). The study shows how the thermal decomposition kinetic parameters effect the surface burning (pyrolysis) temperature and resulting heat release rate history, as well as the relative importance of other properties directly related to the chemical composition. It also illustrates the effect of thermal inertia (the product of density, heat capacity, and thermal conductivity) and of the samples' ability to absorb radiant heat. © 2011 John Wiley & Sons, Ltd.
Borst C.W.,University of Louisiana at Lafayette |
Tiesel J.-P.,La Well GmbH |
Best C.M.,William ghes Technical Center
IEEE Transactions on Visualization and Computer Graphics | Year: 2010
We present and evaluate a new approach for real-time rendering of composable 3D lenses for polygonal scenes. Such lenses, usually called volumetric lenses, are an extension of 2D Magic Lenses to 3D volumes in which effects are applied to scene elements. Although the composition of 2D lenses is well known, 3D composition was long considered infeasible due to both geometric and semantic complexity. Nonetheless, for a scene with multiple interactive 3D lenses, the problem of intersecting lenses must be considered. Intersecting 3D lenses in meaningful ways supports new interfaces such as hierarchical 3D windows, 3D lenses for managing and composing visualization options, or interactive shader development by direct manipulation of lenses providing component effects. Our 3D volumetric lens approach differs from other approaches and is one of the first to address efficient composition of multiple lenses. It is well-suited to head-tracked VR environments because it requires no view-dependent generation of major data structures, allowing caching and reuse of full or partial results. A Composite Shader Factory module composes shader programs for rendering composite visual styles and geometry of intersection regions. Geometry is handled by Boolean combinations of region tests in fragment shaders, which allows both convex and nonconvex CSG volumes for lens shape. Efficiency is further addressed by a Region Analyzer module and by broad-phase culling. Finally, we consider the handling of order effects for composed 3D lenses. © 2006 IEEE.
Mahoney C.M.,U.S. National Institute of Standards and Technology |
Fahey A.J.,U.S. National Institute of Standards and Technology |
Steffens K.L.,U.S. National Institute of Standards and Technology |
Benner Jr. B.A.,U.S. National Institute of Standards and Technology |
Lareau R.T.,William ghes Technical Center
Analytical Chemistry | Year: 2010
The application of surface analytical techniques such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) is explored as a means of differentiating between composition C4 plastic explosives (C-4). Three different C-4 samples including U.S. military grade C-4, commercial C-4 (also from the United States), and C-4 from England (PE-4) were obtained and analyzed using both ToF-SIMS and XPS. ToF-SIMS was able to successfully discriminate between different C-4 samples with the aid of principal component analysis, a multivariate statistical analysis approach often used to reduce the dimensionality of complex data. ToF-SIMS imaging was also used to obtain information about the spatial distribution of the various additives contained within the samples. The results indicated that the samples could potentially be characterized by their 2-D chemical and morphological structure, which varied from sample to sample. XPS analysis also showed significant variation between samples, with changes in the atomic concentrations, as well as changes in the shapes of the high-resolution C 1s and O 1s spectra. These results clearly demonstrate the feasibility of utilizing both ToF-SIMS and XPS as tools for the direct characterization and differentiation of C-4 samples for forensic applications. © 2010 American Chemical Society.
Zarzecki M.,Rutgers University |
Quintiere J.G.,University of Maryland University College |
Lyon R.E.,William ghes Technical Center |
Rossmann T.,Rutgers University |
Diez F.J.,Rutgers University
Combustion and Flame | Year: 2013
An experimental study of the flammability properties of PMMA at low pressures and oxygen concentrations was performed. The work was motivated by the importance of these effects on fire safety in the aviation industry. Measurements were obtained in a mass loss calorimeter inside a large 10m3 pressure vessel capable of reaching pressures as low as 0.1atm. The PMMA flammability was characterized by measuring the burning rate and the time to ignition of small test samples. These were ignited and burned under different external heat fluxes, total pressures and oxygen concentrations. The combined effects of pressure and oxygen concentration on the burning rate, combustion flow field, and ignition were evaluated. Results showed that at low pressure, the burning rate was less intense with a decrease in the mass loss rate. However, the reduction in pressure caused a shortened ignition delay time. Experimental measurements were compared with a simple analytical model showing good agreement. The results also show how pressure and oxygen concentration contributed to the heat transfer from the flame. The model revealed that a single function in oxygen and pressure could account for both flame radiative and convective effects. As a result, a power law fit was obtained for the relation of the combined pressure and oxygen effect on the burning rate. This correlation shows a good agreement with the measurements and predicts the burning rate behavior for the full range of pressure and oxygen tests. © 2013 The Combustion Institute.
Baldwin W.C.,William ghes Technical Center |
Felder W.N.,U.S. Federal Aviation Administration |
Sauser B.J.,Stevens Institute of Technology
International Journal of Industrial and Systems Engineering | Year: 2011
Systems engineers are responsible for systems ranging from the very simple to the extremely complex. The various types of systems create a need for differentiation of properties and identification using some common nomenclature. While other system taxonomies exist, we propose a unique classification mechanism which utilises a finite set of characteristics. Welldefined attributes provide a basis to develop unambiguous mathematical descriptions in future work. Application of the classification scheme will help employ the appropriate systems engineering methodology to systems in development. Copyright © 2011 Inderscience Enterprises Ltd.