The development and use of aircraft evacuation modelling as a viable tool for the certification and safety analysis of passenger aircraft

Evacuation modelling technology offers designers and regulators of aircraft new opportunities to rigorously test designs and theories. However, before evacuation models can be used effectively they need to be understood by the regulatory and aviation industry, validated and developed further. This thesis tackles each of these aspects. This thesis provides a detailed review of evacuation modelling with special emphasis on aviation evacuation models and the available data upon which models and understanding can be based. Of these the airEXODUS model is selected for this thesis and it is described in detail and critically evaluated. The evaluation revealed three main issues that needed to be addressed in order for aircraft evacuation modelling to advance. These issues relate to, (1) the limited quantity of model verification, (2) the inability of models to represent crew procedures, and (3) the limited behavioural capabilities of these models with regard to simulating real accidents as opposed to certification scenarios. The fundamental accuracy and predictive capability of airEXODUS is evaluated. This is followed by a comprehensive investigation of cabin crew and passenger behaviour in 90-second certification trials and real emergency evacuations. The conclusions from this investigation serve as the basis for the development of new algorithms to addresses issues (2) and (3). Behavioural algorithms are developed to simulate cabin crew bypass in conjunction with algorithms for passengers exit choice and methods for simulated passengers to optimise their chosen route to an exit. Finally, this thesis concludes by demonstrating the value of evacuation modelling in the design of future aircraft, the regulation of current aircraft and in understanding some of the contributing factors involved in past evacuation related disasters

An aeroacoustic study of industrial gas turbine intake and exhaust systems.

The purpose of this study was to seek a means of numerically simulating and analyzing the aerodynamic and acoustic behaviour of industrial gas turbine intake or exhaust systems. The method was developed in an effort to advance the current state of the art employed for the prediction of intake and exhaust noise. Current methods rely upon the summation of experimentally gathered insertion loss data for individual system components. This approach requires that physical testing of chosen components be undertaken which can be both costly and time consuming. The proposed numerical method is based upon a two stage finite volume solution of the two dimensional non linear Euler equations whereby an aerodynamic solution for the mean flow is first obtained followed by a solution for the acoustic field. The method has been found to be both accurate and easy to implement, furthermore being numerically based it eliminates the need for the costly and time consuming procurement and testing of physical prototypes. In this respect it is considered to advance the present state of the art. The two step Euler solver developed herein employs a multiblock finite volume formulation wherein the hyperbolic Euler equations are solved using a cell centred finite volume technique employing a second order central differencing method for spatial discretisation on a multiblock grid and with temporal integration being undertaken using an explicit time marching two stage second order Runge Kutta scheme. In the first step the mean flow is solved using the finite volume method to obtain a transient or pseudo steady state solution. This provides both the general aerodynamic characteristics of the system and a baseline steady state solution for the acoustic analysis. In the second step a perturbation representing an acoustic disturbance is introduced to the mean flow and the non linear Euler equations are again solved using the finite volume scheme. Spurious non physical numerical reflections at the domain boundaries are prevented by the application of the characteristic based non reflecting boundary conditions. The resulting unsteady pressure field is then post processed to generate the unsteady pressure disturbance due to the applied acoustic perturbation. The interaction of the acoustic disturbance can then be evaluated by examination of the pressure amplitudes and frequency spectra at any location within the domain. The scheme was applied to the study of the aerodynamic and acoustic characteristics of an industrial gas turbine emergency shutdown compressor bleed system. It was found to accurately predict the acoustic attenuation characteristics of the system, furthermore it was shown that it could also be usefully applied as a design tool and as an example of this a change of attenuation performance of the bleed system is demonstrated by a simple relocation of the baffle silencer within the system ducting. It is concluded that the method developed herein demonstrates that a numerical solution to predict the acoustic attenuation characteristics of an industrial gas turbine silencing system is possible and as such offers an improved means for undertaking the acoustic design of products for noise control in industrial gas turbine applications. In this respect it is considered to advance the present state of the art

Giving in India: A Guide for Funders and Charities

This report looks at the current state of philanthropy in India, and provides a framework for increasing its impact through an analysis of local issues and organizations. The final section examines priority areas in water and sanitation to demonstrate how existing evidence can be used to channel funding to areas where it is likely to have the greatest impact. With bibliographical references

Methodologies for the Evaluation and Mitigation of Distribution Network Risk

Security of supply to customers is a major concern for electricity distribution network operators. This research concentrates in particular on the UK distribution system, and on sub-transmission and extra high voltage networks within that system. It seeks first to understand the principal causes of network risk and consequent loss of supply to customers as a result of faults at these voltage levels. It then develops a suite of methodologies to evaluate that risk, in terms of expected annual cost to the network operator, under a range of different scenarios and for both simple and complex network topologies. The scenarios considered include asset ageing, network automation and increasing utilisation as a consequence of electric vehicles and heat pumps. The methodologies also evaluate possible mitigation options, including active network management, and capital expenditure for both asset replacement and network reinforcement. A composite methodology is also developed, to consider combinations of scenarios and combinations of mitigation strategies. The thesis concludes by considering issues likely to affect the extent and possible increase of network risk over the period 2010-2030

Measurement of Star-Formation Rate from H-alpha in field galaxies at z=1

We report the results of J-band infrared spectroscopy of a sample of 13 z=1 field galaxies drawn from the Canada-France Redshift Survey, targeting galaxies whose redshifts place the rest frame H-alpha line emission from HII regions in between the bright night sky OH lines. As a result we detect emission down to a flux limit of ~10^{-16} ergs cm^{-2} s^{-1} corresponding to a luminosity limit of ~10^{41} ergs at this redshift for a H_0=50 km s^{-1} Mpc,^{-1} q_0=0.5 cosmology. From these luminosities we derive estimates of the star-formation rates in these galaxies which are independent of previous estimates based upon their rest-frame ultraviolet (2800A) luminosity. The mean star-formation rate at z=1, from this sample, is found to be at least three times as high as the ultraviolet estimates. The standard dust extinction in these galaxies is inferred to be A_V=0.5-1.0 mags, comparable to local field galaxies, suggesting that the bulk of star-formation is not heavily obscured unless one uses greyer extinction laws. Star-forming galaxies have the bluest colours and a preponderance of disturbed/interacting morphologies. We also investigate the effects of particular star-formation histories, in particular the role of bursts vs continuous star-formation in changing the detailed distribution of UV to H-alpha emission. Generally we find that models dominated by short, overlapping, bursts at typically 0.2 Gyr intervals provide a better model for the data than a constant rate of star-formation. The star-formation history of the Universe from Balmer lines is compiled and found to be typically 2--3\times higher than that inferred from the UV {\em at all redshifts}. It can not yet be clearly established whether the star-formation rate falls off or remains constant at high-redshift.Comment: 15 pages including 8 figures. MNRAS in pres

A robust data driven approach to quantifying common-cause failure in power networks.

The standard alpha-factor model for common cause failure assumes symmetry, in that all components must have identical failure rates. In this paper, we generalise the alpha-factor model to deal with asymmetry, in order to apply the model to power networks, which are typically asymmetric. For parameter estimation, we propose a set of conjugate Dirichlet-Gamma priors, and we discuss how posterior bounds can be obtained. Finally, we demonstrate our methodology on a simple yet realistic example

Using imprecise continuous time Markov chains for assessing the reliability of power networks with common cause failure and non-immediate repair.

We explore how imprecise continuous time Markov chains can improve traditional reliability models based on precise continuous time Markov chains. Specifically, we analyse the reliability of power networks under very weak statistical assumptions, explicitly accounting for non-stationary failure and repair rates and the limited accuracy by which common cause failure rates can be estimated. Bounds on typical quantities of interest are derived, namely the expected time spent in system failure state, as well as the expected number of transitions to that state. A worked numerical example demonstrates the theoretical techniques described. Interestingly, the number of iterations required for convergence is observed to be much lower than current theoretical bounds

Probing planet formation and disk substructures in the inner disk of Herbig Ae stars with CO rovibrational emission

Context. CO rovibrational lines are efficient probes of warm molecular gas and can give unique insights into the inner 10 AU of proto-planetary disks, effectively complementing ALMA observations. Recent studies find a relation between the ratio of lines originating from the second and first vibrationally excited state, denoted as v2∕v1, and the Keplerian velocity or emitting radius of CO. Counterintuitively, in disks around Herbig Ae stars the vibrational excitation is low when CO lines come from close to the star, and high when lines only probe gas at large radii (more than 5 AU). The v2∕v1 ratio is also counterintuitively anti-correlated with the near-infrared (NIR) excess, which probes hot and warm dust in the inner disk. Aims. We aim to find explanations for the observed trends between CO vibrational ratio, emitting radii and NIR excess, and to identify their implications in terms of the physical and chemical structure of inner disks around Herbig stars. Methods. First, slab model explorations in local thermal equilibrium (LTE) and non-LTE are used to identify the essential parameter space regions that can produce the observed CO emission. Second, we explore a grid of thermo-chemical models using the DALI code, varying gas-to-dust ratio and inner disk radius. Line flux, line ratios, and emitting radii are extracted from the simulated lines in the same way as the observations and directly compared to the data. Results. Broad CO lines with low vibrational ratios are best explained by a warm (400–1300 K) inner disk surface with gas-to-dust ratios below 1000 (N_(CO) 10¹⁸ cm⁻²) at the cavity wall. In all cases, the CO gas must be close to thermalization with the dust (T_(gas) ~ T_(dust)). Conclusions. The high gas-to-dust ratios needed to explain high v2∕v1 in narrow CO lines for a subset of group I disks can be naturally interpreted as due to the dust traps that are proposed to explain millimeter dust cavities. The dust trap and the low gas surface density inside the cavity are consistent with the presence of one or more massive planets. The difference between group I disks with low and high NIR excess can be explained by gap opening mechanisms that do or do not create an efficient dust trap, respectively. The broad lines seen in most group II objects indicate a very flat disk in addition to inner disk substructures within 10 AU that can be related to the substructures recently observed with ALMA. We provide simulated ELT-METIS images to directly test these scenarios in the future