685 research outputs found

    Where to build the walls that protect us

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    This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.Working at a tangent to Wrights & Sites' disrupted walking practices and the notion of the architect-walker, commissioned by Kaleider and funded by Arts Council England, Where to build the walls that protect us was an opportunity to imagine a future city. Originally focused on Exeter in 2013-14, the work was later reiterated for Leeds as part of Compass Festival 2016. Framed as an architectural charrette, participants experienced two distinct phases of activity: initially framed by a series of themed reconnaissance excursions; later followed by an iterative period of generating future-facing models of the city. Literal and poetic drift underpinned the work, for example, through the use of: • post-Situationist walking-art practices drawn from Wrights & Sites and others, e.g. Simon Pope's 'constrained drift', where geographical (or temporal) limits bound the scope of the journey; • strategic, location-specific encounters with 'experts' (whether professional, municipal or resident), as spurs to the imagination; • creative intervention into the process of city planning (Exeter was undertaking a consultation process about its new flood defence scheme at the time); • physical interruption of everyday city life, as unsuspecting members of the public suspended their A to B journeys and join in the reimagining of their city

    The Development and Use of A Piloted Flight Simulation Environment for Rotary-Wing Operation to the Queen Elizabeth Class Aircraft Carriers

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    Flight simulation is being used to inform the First of Class Flight Trials for the UK’s new Queen Elizabeth Class (QEC) aircraft carriers. The carriers will operate with the Lockheed Martin F-35B Lightning II fighter aircraft, i.e. the Advanced Short Take-Off and Vertical Landing variant of the F-35. The rotary wing assets that are expected to operate with QEC include Merlin, Wildcat, Chinook and Apache helicopters. An F-35B flight simulator has been developed and is operated by BAE Systems at Warton Aerodrome. The University of Liverpool is supporting this project by using Computational Fluid Dynamics (CFD) to provide the unsteady air flow field that is required in a realistic flight simulation environment. This paper is concerned with a research project that is being conducted using the University’s research simulator, HELIFLIGHT-R, to create a simulation environment for helicopter operations to the QEC. The paper briefly describes how CFD has been used to model the unsteady airflow over the 280m long aircraft carrier and how this is used to create a realistic flight simulation environment. Results are presented from an initial simulation trial in which test pilots have used the HELIFLIGHT-R simulator to conduct simulated helicopter landings to two landing spots on the carrier, one in a disturbed air flow and the other in clean air. As expected, the landing to the spot in disturbed air flow requires a greater pilot workload, shows greater deviation in its positional accuracy and requires more control activity. This initial trial is the first of a planned series of simulated helicopter deck landings for different wind angles and magnitudes

    A Virtual Engineering Approach to the Ship-Helicopter Dynamic Interface; a decade of modelling and simulation research at The University of Liverpool

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    This paper reviews some of the research that has been carried out at the University of Liverpool where the Flight Science and Technology Research Group has developed its Heliflight-R full-motion research simulator to create a simulation environment for the launch and recovery of maritime helicopters to ships. HELIFLIGHT-R has been used to conduct flight trials to produce simulated Ship-Helicopter Operating Limits (SHOLs). This virtual engineering approach has led to a much greater understanding of how the dynamic interface between the ship and the helicopter contributes to the pilot's workload and the aircraft's handling qualities and will inform the conduct of future real-world SHOL trials. The paper also describes how modelling and simulation has been applied to the design of a ship's superstructure to improve the aerodynamic flow field in which the helicopter has to operate. The superstructure aerodynamics also affects the placement of the ship's anemometers and the dispersion of the ship's hot exhaust gases, both of which affect the operational envelope of the helicopter, and both of which can be investigated through simulation

    Conditional Facilitation of an Aphid Vector, Acyrthosiphon pisum, by the Plant Pathogen, Pea Enation Mosaic Virus

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    Plant pathogens can induce symptoms that affect the performance of insect herbivores utilizing the same host plant. Previous studies examining the effects of infection of tic bean, Vicia faba L. (Fabales: Fabaceae), by pea enation mosaic virus (PEMV), an important disease of legume crops, indicated there were no changes in the growth and reproductive rate of its primary vector the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). Here, we report the results of laboratory experiments investigating how A. pisum responded to PEMV infection of a different host plant, Pisum sativum L., at different stages of symptom development. Aphid growth rate was negatively related to the age of the host plant, but when they were introduced onto older plants with well-developed PEMV symptoms they exhibited a higher growth rate compared to those developing on uninfected plants of the same age. In choice tests using leaf discs A. pisum showed a strong preference for discs from PEMV-infected peas, probably in response to visual cues from the yellowed and mottled infected leaves. When adults were crowded onto leaves using clip-cages they produced more winged progeny on PEMV-infected plants. The results indicate that PEMV produces symptoms in the host plant that can enhance the performance of A. pisum as a vector, modify the production of winged progeny and affect their spatial distribution. The findings provide further evidence that some insect vector/plant pathogen interactions could be regarded as mutualistic rather than commensal when certain conditions regarding the age, stage of infection and species of host plant are met

    The Role of Modelling and Simulation in the Preparations for Flight Trials Aboard the Queen Elizabeth Class Aircraft Carriers

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    This paper provides a brief overview of how modelling and simulation has been used to inform preparations for First of Class Flight Trials (FOCFT) aboard HMS Queen Elizabeth, the first of the United Kingdom’s two new Queen Elizabeth Class aircraft carriers, from the perspective of a collaborative research programme undertaken by industry and academia to develop high-fidelity simulations of the carrier’s ‘airwake’.  Computer modelling of the unsteady air flow over the carrier, and of the aircraft flight dynamics, have been integrated into high-fidelity flight simulators at BAE Systems Warton, and at the University of Liverpool.  The Queen Elizabeth Class (QEC) carriers have primarily been designed to operate the Short Take-Off and Vertical Landing (STOVL) variant of the Lockheed Martin F-35 Lightning II multirole fighter aircraft and will also operate a range of rotary-wing assets.  Computational Fluid Dynamics (CFD) has been used to compute the time-varying air flow over and around the 280m long ship, along the F-35B landing approach path and up to 400m astern of the ship.  The paper shows a selection of results from the full-scale CFD analysis, and the results from a small-scale experiment that was conducted to provide confidence in the validity of the computed airwakes.  The QEC airwakes have been employed by BAE Systems in its fixed-wing flight simulator at Warton, where test pilots have conducted simulated deck landings for a variety of wind over deck conditions, so providing experience for F-35B test pilots and the ship’s Flying Control (FLYCO) crew ahead of FOCFT, which will be conducted later this year.  Airwakes have also been implemented in the HELIFLIGHT-R flight simulator at the University of Liverpool, where helicopter landings to the QEC have been simulated using a generic medium-weight maritime-helicopter model. A selection of results from the helicopter flight simulator trials is presented in terms of the workload ratings reported by test pilots, and these are related to the characteristics of the computed airwake at the landing spots tested.  The paper demonstrates how modelling and simulation can be used to reduce both the risk and cost of flight trials, by informing the FOCFT planning process, and by highlighting, in advance of the trials, which wind speed and azimuth combinations may require more focus.  </jats:p

    Reproductive competition triggers mass eviction in cooperative banded mongooses

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    In many vertebrate societies, forced eviction of group members is an important determinant of population structure, but little is known about what triggers eviction. Three main explanations are (1) the reproductive competition hypothesis; (2) the coercion of cooperation hypothesis; and (3) the adaptive forced dispersal hypothesis. The last hypothesis proposes that dominant individuals use eviction as an adaptive strategy to propagate copies of their alleles through a highly structured population. We tested these hypotheses as explanations for eviction in cooperatively breeding banded mongooses (Mungos mungo), using a 16-year dataset on life history, behaviour and relatedness. In this species, groups of females, or mixed-sex groups, are periodically evicted en masse. Our evidence suggests that reproductive competition is the main ultimate trigger for eviction for both sexes. We find little evidence that mass eviction is used to coerce helping, or as a mechanism to force dispersal of relatives into the population. Eviction of females changes the landscape of reproductive competition for remaining males, which may explain why males are evicted alongside females. Our results show that the consequences of resolving within-group conflict resonate through groups and populations to affect population structure, with important implications for social evolution

    Female reproductive competition explains variation in prenatal investment in wild banded mongooses

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    Female intrasexual competition is intense in cooperatively breeding species where offspring compete locally for resources and helpers. In mammals, females have been proposed to adjust prenatal investment according to the intensity of competition in the postnatal environment (a form of ‘predictive adaptive response’; PAR). We carried out a test of this hypothesis using ultrasound scanning of wild female banded mongooses in Uganda. In this species multiple females give birth together to a communal litter, and all females breed regularly from one year old. Total prenatal investment (size times the number of fetuses) increased with the number of potential female breeders in the group. This relationship was driven by fetus size rather than number. The response to competition was particularly strong in low weight females and when ecological conditions were poor. Increased prenatal investment did not trade off against maternal survival. In fact we found the opposite relationship: females with greater levels of prenatal investment had elevated postnatal maternal survival. Our results support the hypothesis that mammalian prenatal development is responsive to the intensity of postnatal competition. Understanding whether these responses are adaptive requires information on the long-term consequences of prenatal investment for offspring fitness
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