Theoretical investigaion of the performance of alternative aviation fuels in an aero-enginve combustion chamber

When considering alternative fuels for aviation, factors such as the overall efficiency of the combustion process and the levels of emissions emitted to the atmosphere, need to be critically evaluated. The physical and chemical properties of a fuel influence the combustion efficiency and emissions and therefore need to be considered. The energy content of a biofuel, which is influenced negatively by the presence of oxygen in the molecular structure (i.e. oxygenated chemical compounds), is relatively low when compared with that of conventional jet fuel. This means that the overall efficiency of the process will be different. In this paper two possible scenarios have been investigated in order to assess the potential to directly replace conventional jet fuel with Methyl Buthanoate - MB (a short chain FAME representing biofuel) and a synthetic jet fuel (FT fuel) using Computational Fluid Dynamics (CFD) modelling in a typical Modern Air-Spray Combustor (MAC). In addition the impact of fuel blending on the combustion performance has been investigated. Computational Fluid Dynamics (CFD) has been verified and validated over past decades to be a powerful design tool in industries where experimental work can be costly, hazardous and time consuming, to support the design and development process. With recent developments in processor speeds and solver improvements, CFD has been successfully validated and used as a tool for optimizing combustor technology. Combustion of each fuel is calculated using a mixture fraction/pdf approach and the turbulence-chemistry interaction has been modelled using the Laminar Flamelet approach. Detailed chemical reaction mechanisms, developed and validated recently by the authors for aviation fuel including kerosene, synthetic fuel and bio-aviation fuel have been employed in the CFD modelling. A detailed comparison of kerosene with alternative fuel performance has been made.

Assessment of the performance of alternative aviation fuel in a modern air-spray combustor (MAC)

Recent concerns over energy security and environmental considerations have highlighted the importance of finding alternative aviation fuels. It is expected that coal and biomass derived fuels will fulfil a substantial part of these energy requirements. However, because of the physical and chemical difference in the composition of these fuels, there are potential problems associated with the efficiency and the emissions of the combustion process. Over the past 25 years Computational Fluid Dynamics (CFD) has become increasingly popular with the gas turbine industry as a design tool for establishing and optimising key parameters of systems prior to starting expensive trials. In this paper the performance of a typical aviation fuel, kerosene, an alternative aviation fuel, biofuel and a blend have been examined using CFD modelling. A good knowledge of the kinetics of the reaction of bio aviation fuels at both high and low temperature is necessary to perform reliable simulations of ignition, combustion and emissions in aero-engine. A novel detailed reaction mechanism was used to represent aviation fuel oxidation mechanism. The fuel combustion is calculated using a 3D commercial solver using a mixture fraction/pdf approach. Firstly, the study demonstrates that CFD predictions compare favourably with experimental data obtained by QinetiQ for a Modern Airspray Combustor (MAC) when used with traditional jet fuel (kerosene). Furthermore, the 3D CFD model has been refined to use the laminar flamelet model (LFM) approach that incorporates recently developed chemical reaction mechanisms for the bio-aviation fuel. This has enabled predictions for the bio-aviation fuel to be made. The impact of using the blended fuel has been shown to be very similar in performance to that of the 100% kerosene, confirming that aircraft running on 20% blended fuel should have no significant reduction in performance. It was also found that for the given operating conditions there is a significant reduction in performance when 100% biofuel if used. Additionally, interesting predictions were obtained, related to NOx emissions for the blend and 100% biofuel

The Human-Robot Interaction Operating System

In order for humans and robots to work effectively together, they need to be able to converse about abilities, goals and achievements. Thus, we are developing an interaction infrastructure called the "Human-Robot Interaction Operating System" (HRI/OS). The HRI/OS provides a structured software framework for building human-robot teams, supports a variety of user interfaces, enables humans and robots to engage in task-oriented dialogue, and facilitates integration of robots through an extensible API

Exotic Differentiable Structures and General Relativity

We review recent developments in differential topology with special concern for their possible significance to physical theories, especially general relativity. In particular we are concerned here with the discovery of the existence of non-standard (``fake'' or ``exotic'') differentiable structures on topologically simple manifolds such as $S^7$, \R and $S^3\times {\bf R^1}.$ Because of the technical difficulties involved in the smooth case, we begin with an easily understood toy example looking at the role which the choice of complex structures plays in the formulation of two-dimensional vacuum electrostatics. We then briefly review the mathematical formalisms involved with differentiable structures on topological manifolds, diffeomorphisms and their significance for physics. We summarize the important work of Milnor, Freedman, Donaldson, and others in developing exotic differentiable structures on well known topological manifolds. Finally, we discuss some of the geometric implications of these results and propose some conjectures on possible physical implications of these new manifolds which have never before been considered as physical models.Comment: 11 pages, LaTe

The Effects of Malignant Transformation on Susceptibility of Human Urothelial Cells to CD40-Mediated Apoptosis

Background: The tumor necrosis factor (TNF) superfamily of ligands and receptors mediates immune cell survival. Some members possess a death domain, a protein motif that functions to transmit apoptotic signals, whereas others, such as CD40, do not. CD40 is expressed by both normal and malignant epithelial cells. To investigate the functional significance of this expression, we studied the effects of ligation of CD40, Fas, and TNF receptors (TNFRs) on the proliferation and survival of normal and malignant human urothelial cells and urothelial cells with disabled p53 function. Methods: Normal and malignant human urothelial cells were cultured with soluble TNF family agonists (CD40 ligand [CD40L], TNF-α, anti-Fas antibody, or cocultured with mouse fibroblasts stably transfected with plasmids that caused the cells to constitutively express CD40L or CD32; cell proliferation was estimated by an [3H]thymidine incorporation assay, and apoptosis was determined by Annexin V staining and by a DNA fragmentation assay. Messenger RNA levels for CD40 and potential downstream effector molecules were quantified by polymerase chain reaction-based and ribonuclease protection assays, respectively, and nuclear factor (NF) κB nuclear translocation was detected by immunofluorescence. All statistical tests were two-sided. Results: Soluble trimeric CD40L inhibited the growth of normal and malignant urothelial cells but did not induce apoptosis. Cell surface-presented CD40L induced massive apoptosis in CD40-positive transitional cell carcinoma cells but not in normal urothelial cells. Normal cells underwent CD40L-mediated apoptosis only in the presence of other TNFR agonists. An agonistic anti-CD40 antibody presented on the surface of CD32-transfected fibroblasts also induced apoptosis in transitional cell carcinoma cells and in normal urothelial cells. Apoptotic responses of tumor (but not normal) cells to soluble agonists were enhanced by blocking protein synthesis. Karyotypically normal urothelial cells with disabled p53 function underwent apoptosis during coculture with CD40L-expressing fibroblasts alone but were not additionally sensitive to additional TNFR agonists. Conclusions: Susceptibility to CD40 ligation-induced apoptosis may be a novel mechanism for eliminating neoplastically transformed urothelial cells. Loss of CD40 expression may be an important adaptive mechanism for transitional cell carcinoma development and progressio

Audio Cartography: Visual Encoding of Acoustic Parameters

Our sonic environment is the matter of subject in multiple domains which developed individual means of its description. As a result, it lacks an established visual language through which knowledge can be connected and insights shared. We provide a visual communication framework for the systematic and coherent documentation of sound in large-scale environments. This consists of visual encodings and mappings of acoustic parameters into distinct graphic variables that present plausible solutions for the visualization of sound. These candidate encodings are assembled into an application-independent, multifunctional, and extensible design guide. We apply the guidelines and show example maps that acts as a basis for the exploration of audio cartography