1,111 research outputs found

    Development of pilot training requirements for Personal Aerial Vehicles

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    This paper describes research activities conducted at the University of Liverpool as part of the myCopter project into the development of training requirements for pilots of Personal Aerial Vehicles (PAVs). The work has included a Training Needs Analysis (TNA) to determine the skills required of a PAV pilot and the evaluation of a training programme that covers the development of the skills identified by the TNA. The effectiveness of the training programme has been assessed using the first three Levels of Kirkpatrick's method. The evaluation showed that the developed training programme was effective, in terms of engaging the trainees with the subject, and in terms of developing the skills required to fly a series of PAV-mission related tasks in a flight simulator

    Towards the Development of a Flight Training Programme for Future Personal Aerial Vehicle Users

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    Interest in personal aerial vehicles (PAVs) is resurgent with several flying prototypes made possible through advances in the relevant technologies. Whilst the perceived wisdom is that these vehicles will be highly automated or autonomous, the current regulatory framework assumes that a human will always be able to intervene in the operation of the flight. This raises the possibility of manually operated PAVs and the requirement for an occupant flying training programme. This paper describes the development of training requirements for PAV pilots. The work includes a training needs analysis (TNA) for a typical PAV flight. It then describes the development of a training programme to develop the skills identified by the TNA. Five participants with no real flying experience, but varying levels of driving experience, undertook the training programme. Four completed the programme through to a successful simulation flight test of a commuter flight scenario. These participants evaluated the effectiveness of the training programme using the first three Levels of Kirkpatrick’s method. The evaluation showed that the developed training programme was effective, in terms of both trainee engagement and development of the handling skills necessary to fly PAV mission-related tasks in a flight simulator. The time required for the four successful participants to develop their core flying skills was less than 5 h. This duration indicates that future simulation PAV training would be commensurate with the training duration for current personal transportation modes

    Fractal Characterization of Fracture Networks: An Improved Box-counting Technique

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    Box counting is widely used for characterizing fracture networks as fractals and estimating their fractal dimensions (D). If this analysis yields a power law distribution given by N ∝\propto r−D, where N is the number of boxes containing one or more fractures and r is the box size, then the network is considered to be fractal. However, researchers are divided in their opinion about which is the best box‐counting algorithm to use, or whether fracture networks are indeed fractals. A synthetic fractal fracture network with a known D value was used to develop a new algorithm for the box‐counting method that returns improved estimates of D. The method is based on identifying the lower limit of fractal behavior (rcutoff) using the condition ds/dr → 0, where s is the standard deviation from a linear regression equation fitted to log(N) versus log(r) with data for r \u3c rcutoff sequentially excluded. A set of 7 nested fracture maps from the Hornelen Basin, Norway was used to test the improved method and demonstrate its accuracy for natural patterns. We also reanalyzed a suite of 17 fracture trace maps that had previously been evaluated for their fractal nature. The improved estimates of D for these maps ranged from 1.56 ± 0.02 to 1.79 ± 0.02, and were much greater than the original estimates. These higher D values imply a greater degree of fracture connectivity and thus increased propensity for fracture flow and the transport of miscible or immiscible chemicals

    Phase Transition in Liquid Drop Fragmentation

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    A liquid droplet is fragmented by a sudden pressurized-gas blow, and the resulting droplets, adhered to the window of a flatbed scanner, are counted and sized by computerized means. The use of a scanner plus image recognition software enables us to automatically count and size up to tens of thousands of tiny droplets with a smallest detectable volume of approximately 0.02 nl. Upon varying the gas pressure, a critical value is found where the size-distribution becomes a pure power-law, a fact that is indicative of a phase transition. Away from this transition, the resulting size distributions are well described by Fisher's model at coexistence. It is found that the sign of the surface correction term changes sign, and the apparent power-law exponent tau has a steep minimum, at criticality, as previously reported in Nuclear Multifragmentation studies [1,2]. We argue that the observed transition is not percolative, and introduce the concept of dominance in order to characterize it. The dominance probability is found to go to zero sharply at the transition. Simple arguments suggest that the correlation length exponent is nu=1/2. The sizes of the largest and average fragments, on the other hand, do not go to zero but behave in a way that appears to be consistent with recent predictions of Ashurst and Holian [3,4].Comment: 10 pages, 11 figures. LaTeX (revtex4) with psfig/epsfi

    Development of Occupant-Preferred Landing Profiles for Personal Aerial Vehicles

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    With recent increased interest in autonomous vehicles and the associated technology, the prospect of realizing a personal aerial vehicle (PAV) seems closer than ever. However, there is likely to be a continued requirement for any occupant of an air vehicle to be comfortable with both the automated portions of the flight and their ability to take manual control as and when required. This paper, using the approach to landing as an example maneuver, examines what a comfortable trajectory for PAV occupants might look like. Based upon simulated flight data, a ‘natural’ flight trajectory was designed and then compared to constant deceleration and constant optic flow descent profiles. It was found that PAV occupants with limited flight training and no artificial guidance followed the same longitudinal trajectory as had been found for professionally trained helicopter pilots. Further, the final stages of the approach to hover could be well described using Tau Theory. For automatic flight, PAV occupants preferred a constant deceleration profile. For approaches flown manually, the newly designed natural profile was preferred

    In vivo chemical and structural analysis of plant cuticular waxes using stimulated Raman scattering microscopy.

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    The cuticle is a ubiquitous, predominantly waxy layer on the aerial parts of higher plants that fulfils a number of essential physiological roles, including regulating evapotranspiration, light reflection, and heat tolerance, control of development, and providing an essential barrier between the organism and environmental agents such as chemicals or some pathogens. The structure and composition of the cuticle are closely associated but are typically investigated separately using a combination of structural imaging and biochemical analysis of extracted waxes. Recently, techniques that combine stain-free imaging and biochemical analysis, including Fourier transform infrared spectroscopy microscopy and coherent anti-Stokes Raman spectroscopy microscopy, have been used to investigate the cuticle, but the detection sensitivity is severely limited by the background signals from plant pigments. We present a new method for label-free, in vivo structural and biochemical analysis of plant cuticles based on stimulated Raman scattering (SRS) microscopy. As a proof of principle, we used SRS microscopy to analyze the cuticles from a variety of plants at different times in development. We demonstrate that the SRS virtually eliminates the background interference compared with coherent anti-Stokes Raman spectroscopy imaging and results in label-free, chemically specific confocal images of cuticle architecture with simultaneous characterization of cuticle composition. This innovative use of the SRS spectroscopy may find applications in agrochemical research and development or in studies of wax deposition during leaf development and, as such, represents an important step in the study of higher plant cuticles

    "Black holes in the fabric of the nation": Refugees in Mohsin Hamid’s "Exit West".

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    This article explores the representation of refugees in Mohsin Hamid’s Exit West (2017), a novel which marks an early and particularly prominent literary response to the ‘international refugee crisis’. In a distinct echo of Salman Rushdie’s claim, a quarter of a century ago, that it ‘may be argued that the past is a country from which we have all emigrated’, Hamid’s novel similarly claims that ‘we are all migrants through time.’ Moreover, like Rushdie’s fiction, Hamid’s novel incorporates elements of magical realism and fable. Its protagonists, Nadia and Saeed, escape their unnamed war-torn city through a ‘door’ that instantaneously transports them to Mykonos; they subsequently travel through other such ‘doors’ to London and San Francisco. Their story is interspersed with a series of vignettes in which other refugees also find themselves magically transported to ‘first-world’ nations. As well as considering the ways in which Hamid’s novel seeks to humanize refugees, this article considers the novel’s evocation of a world in which human beings have – like capital, images, and (mis)information – gained access to largely ungovernable networks of instantaneous travel across vast distances. It argues that Hamid’s novel is not just ‘about’ refugees but also constitutes a reflection on how they, and their journeys, are represented and mediated by actually-existing technologies

    myCopter: Enabling Technologies for Personal Air Transport Systems - an Early Progress Report

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    This paper describes the European Commission (EC) Framework 7 funded project myCopter (2011-2014). The project is still at an early stage so the paper starts with the current transportation issues faced by developed countries and describes a means to solve them through the use of personal aerial transportation. The concept of personal air vehicles (PAV) is briefly reviewed and how this project intends to tackle the problem from a different perspective described. It is argued that the key reason that many PAV concepts have failed is because the operational infrastructure and socio-economic issues have not been properly addressed; rather, the start point has been the design of the vehicle itself. Some of the key aspects that would make a personal aerial transport system (PATS) viable include the required infrastructure and associated technologies, the skill levels and machine interfaces needed by the occupant or pilot and the views of society as a whole on the acceptability of such a proposition. The myCopter project will use these areas to explore the viability of PAVs within a PATS. The paper reports upon the early progress made within the project. An initial reference set of PAV requirements has been collated. A non-physical flight simulation model capable of providing a wide range of handling qualities characteristics has been developed and its function has undergone limited verification. Results from this exercise show that the model behaves as intended and that it can deliver a predictable range of vehicle dynamics. The future direction of the themes of work described within the paper are then described

    Progress in the development of unified fidelity metrics for rotorcraft flight simulators

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    Flight simulators are integral to the design/development, testing/qualification, training and research communities and their utilisation is expanding rapidly. The quantification of simulation fidelity underpins the confidence required for the use of flight simulation in design, to reduce real life testing, and to provide a safe environment for pilot training. Whilst regulatory simulator standards exist and new standards are in development, previous research has shown that current standards do not provide a fully quantitative approach for assessing simulation fidelity, even in a research environment. This paper reports progress on developments of the HELFLIGHT-R flight simulator at the University of Liverpool, and its subsequent use in a research project (Lifting Standards) aimed at creating new predicted and perceived measures of simulator fidelity, derived from handling qualities engineering. Results from flight tests on the National Research Council (Canada) Bell 412 ASRA research aircraft and HELIFLIGHT-R piloted simulation trials are presented to show the strong connection between handling qualities engineering and fidelity assessment. The issue of (pilot) perceived fidelity is examined and the development of new metrics discussed. Copyright (c) 2010 by the American Helicopter Society International, Inc. All rights reserved
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