Browsing by Author "Cousins, Steven"
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Item Open Access Foraging patterns of the wood ant Formica rufa Linnaeus (Hymenoptera: Forrnicidae) at Burnham Beeches, Buckinghamshire(Cranfield University, 1998-12) Fry, Jacqueline M.; Cousins, StevenThis thesis describes a study on the foraging ecology of the wood ant Formica rufa Linnaeus (Hymenoptera: Formicidae) at Burnham Beeches, Buckinghamshire over the period January 1994 to June 1996. Detailed observations were made on the foraging behaviour during this period and the food supply of two colonies was experimentally altered by food supplementation and food denial through grease-banding of trees within a 50 m by 50 m area centred on the nest. The foraging areas of F. rufa colonies were determined by observing trails to trees and showed seasonal variation. The size of the foraging areas, their tree composition, the mean distance travelled by foragers and the extent to which particular trees were repeatedly foraged were monitored. There was stability in foraging areas between years due to colony persistence. Food supplementation did not alter the foraging area of the nest. There was some evidence that the extra resources were channelled into producing more sexuals. Food denial caused the denied nest to expand its foraging area. The amount of honeydew collected by F. rufa was experimentally determined. The amount of prey taken was estimated from a survey of the literature. The proportion of net primary productivity moved by a F. rufa colony across its foraging area was estimated as 0.12 % to 0.47 %. The effects of the distribution of F. rufa on other ground living invertebrates was experimentally investigated. The presence of F. rufa was found to be significantly negatively correlated with the presence of predatory Coleoptera and significantly positively correlated with the presence of the myrmecophilous staphylinid beetle Zyras humeralis (Gravenhorst). The monitoring of the foraging areas and determination of the relationship between the presence of F. rufa and other ecological groupings allows this work to be used to inform the ETM framework, a proposal for spatially delineating ecosystems.Item Open Access Improved vehicle seating systems for managing rear impact events(Cranfield University, 2005-07) Owen, Christopher; Cousins, StevenA study has been conducted into the development of Impact Management Seating Systems (IMSS's) for improved occupant protection during rear impacts. The seating systems incorporate methodologies that enable the supporting surfaces to pivot in a controlled manner during the onset of the impact event. This enables the seated occupant to penetrate an outer perimeter frame, whilst simultaneously having the effective ride height lowered. This response is typically referred to as the 'Catchers- Mitt' principal, and provides the occupant with localised 'ride-down', and optimum positioning with respects to the head restraint. Such seating systems can compliment the 'ride-down' characteristics provided by vehicle' crush-zones', or in the case of small and Low Mass Vehicle (LMV) designs, which can suffer from inefficient 'crush-zones' due to geometric restrictions, can be the primary source of impact management. Pivotal systems typically rely on the use of yielding elements to initiate the desired deployment. However, these are inherently restrictive in their ability to adapt to changes in occupant mass and impact magnitude. Solutions are presented to address this and other limitations. Such solutions include the use automatic inflation/deflation technologies, and Siding Plate Anchorage Systems that provide the seated occupant with a supportive surface during deployment of the pivotal mechanisms, and the reposition of the restraint system to address issues with 'rebound-reactions' and/or multiple impact events. LS-DYNA simulations determined the effectiveness of the developed seating systems in controlling a dummy response. Significant reductions in head acceleration and the movements thought responsible for whiplash and Whiplash Associated Disorders were achieved. The realisation of the seating systems is examined. Consideration is given to issues associated with seat mass, to enable the systems to be installed within Low Mass Vehicle (LMV) designs without compromising environmental gains.