1,112 research outputs found
Development of pilot training requirements for Personal Aerial Vehicles
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
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
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 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
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
In vivo chemical and structural analysis of plant cuticular waxes using stimulated Raman scattering microscopy.
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
Multiscale Soil Investigations: Physical Concepts And Mathematical Techniques
Soil variability has often been considered to be composed of “functional” (explained) variations plus random fl uctuations or noise. However, the distinction between these two components is scale dependent because increasing the scale of observation almost always reveals structure in the noise (Burrough, 1983). Soils can be seen as the result of spatial variation operating over several scales, indicating that factors infl uencing spatial variability differ with scale. Th is observation points to variability as a key soil attribute that should be studied
Development of Occupant-Preferred Landing Profiles for Personal Aerial Vehicles
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
Towards the development of a flight training programme for future personal aerial vehicle users
First Reported Case of Cryptococcus gattii in the Southeastern USA: Implications for Travel-Associated Acquisition of an Emerging Pathogen
In 2007, the first confirmed case of Cryptococcus gattii was reported in the state of North Carolina, USA. An otherwise healthy HIV negative male patient presented with a large upper thigh cryptococcoma in February, which was surgically removed and the patient was started on long-term high-dose fluconazole treatment. In May of 2007, the patient presented to the Duke University hospital emergency room with seizures. Magnetic resonance imaging revealed two large CNS lesions found to be cryptococcomas based on brain biopsy. Prior chest CT imaging had revealed small lung nodules indicating that C. gattii spores or desiccated yeast were likely inhaled into the lungs and dissemination occurred to both the leg and CNS. The patient's travel history included a visit throughout the San Francisco, CA region in September through October of 2006, consistent with acquisition during this time period. Cultures from both the leg and brain biopsies were subjected to analysis. Based on phenotypic and molecular methods, both isolates were C. gattii, VGI molecular type, and distinct from the Vancouver Island outbreak isolates. Based on multilocus sequence typing of coding and noncoding regions and virulence in a heterologous host model, the leg and brain isolates are identical, but the two differed in mating fertility. Two clinical isolates, one from a transplant recipient in San Francisco and the other from Australia, were identical to the North Carolina clinical isolate at all markers tested. Closely related isolates that differ at only one or a few noncoding markers are present in the Australian environment. Taken together, these findings support a model in which C. gattii VGI was transferred from Australia to California, possibly though an association with its common host plant E. camaldulensis, and the patient was exposed in San Francisco and returned to present with disease in North Carolina
Perfect weddings abroad
Approximately 16% of UK couples are currently married abroad. However, academic or practitioner focused research that explores the complex nature of a couple’s buying preferences or the development of innovative marketing strategies by businesses operating within the weddings abroad niche sector, is almost non-existent. This exploratory paper examines the role and relevance of marketing within the weddings abroad sector. The complex nature of customer needs in this high emotional and involvement experience, are identified and explored. A case study of Perfect Weddings Abroad Ltd highlights distinctive features and characteristics. Social networking and the use of home-workers, with a focus on reassurance and handholding are important tools used to develop relationships with customers. These tools and techniques help increase the tangibility of a weddings abroad package. Clusters of complementary services that are synergistic and provide sources of competitive advantage are identified and an agenda for future research is developed
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