2,312 research outputs found
Interview with Sandy Stephens
No full textAnn Pflaum interviews Sandy Stephens, former Gophers football player.Stephens, Sandy; Pflaum, Ann M.. (1999). Interview with Sandy Stephens. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/48352
Experimental measurement of the nearfield longitudinal wake profiles of a high-speed prismatic planing hull
No full textThis study details an extensive investigation into the nearfield longitudinal wake profiles of a high-speed planing hull. Developing understanding this flow is benaficial to the designers of stepped hulls in determining how the forebody’s wake intersects with the afterbody. As no experimental data was available, a novel small-scale model-testing programme was undertaken, measuring Centreline (CL) and Quarter Beam (QB) nearfield longitudinal wake profiles, as well as the forces. The nearfield wake profile was found to exhibit trends in agreement with the findings of studies investigating the mid and far-field wake. The results of this experimental work are provided in full as validation data. Savitsky’s Wake Equations and the Linear Wake Assumption are then assessed to determine the level of confidence with which they may be used to model this flow. Savitsky’s Wake Equations displayed a surprising level of accuracy whereas the Linear Wake Assumption was invalid for the conditions investigated
Ark Ride
No full textSandy Steele's Ark - (German made) - A6 - photographed Great Dorset Steam Fair 1991
Ark Ride
No full textSandy Steele's Ark - (German made) - A6 - photographed Great Dorset Steam Fair1991
Willow growth in response to nutrients and moisture on a clay landfill cap soil. II: Water use
No full textThis paper describes studies into the effects of soil factors and water stress on water use by willow (Salix viminalis L.) on a clay landfill cap soil and a sandy loam. Individual plants were grown in lysimeters containing these soils under different watering regimes and with different soil amendment treatments. Stemflow and throughfall were measured to determine rainfall entering the lysimeters and evapotranspiration (ET) calculated from a water balance. With plentiful water, seasonal ET increased annually in most treatments, reflecting increases in plant leaf area and dry matter production. For the most vigorous plants, in the sandy loam treatment, it increased from about 360 l plant-1 in the establishment year to almost 1200 l plant-1 in the third year. Seasonal ET was highly correlated with leaf area duration. Nutritional amendment of Oxford clay resulted in plants with larger leaf area and higher dry matter production and seasonal ET than in the unamended treatment. Water stress reduced seasonal ET by up to 41%, as a result of defoliation and stomatal closure. In unstressed plants, in the sandy loam treatment, daily ET rates per unit leaf area reached a maximum of about 1.5 l m-2 d-1 in July. Without nutritional amendment, water use efficiency (WUE) calculated from plant ET and root, stump and stem dry weight, was low for the unamended Oxford clay treatment (1.4 g kg-1) but was similar in the amended clay (5.0 g kg-1) and sandy loam (4.9 g kg-1) treatments. The study has shown the dependence of biomass production by willow on Oxford clay on both nutritional amendment and water availability. Although both nutrients and water could be supplied at these sites by growing SRC within a leachate management system, there are several practical issues like the narrow window of opportunity for mechanised operations and concerns about long-term sustainability which still need to be addressed
Non-discursive knowledge and the construction of identity. Potters, potting and performance at the bronze age tell of Százhalombatta, Hungary
No full textThis article explores the relationship between the making of things and the making of people at the Bronze Age tell at Százhalombatta, Hungary. Focusing on potters and potting, we explore how the performance of non-discursive knowledge was critical to the construction of social categories. Potters literally came into being as potters through repeated bodily enactment of potting skills. Potters also gained their identity in the social sphere through the connection between their potting performance and their audience. We trace degrees of skill in the ceramic record to reveal the material articulation of non-discursive knowledge and consider the ramifications of the differential acquisition of non-discursive knowledge for the expression of different kinds of potter's identities. The creation of potters as a social category was essential to the ongoing creation of specific forms of material culture. We examine the implications of altered potters' performances and the role of non-discursive knowledge in the construction of social models of the Bronze Ag
The impact of climatic variability over the period 1961- 1990 on the soil water balance of upland soils in the North East Arid Zone of Nigeria
No full textOver the period 1961 – 90 the North East Arid Zone of Nigeria experienced a decline
in annual rainfall totals and increased aridity which placed increasing pressure on
rain fed, millet-based farming systems. The changes in seasonal rainfall total and
distribution have been examined and it has been shown that the rate of decline has
been consistent across the region. The decline has been dominated by reduction in
the number of rain days during the middle of the rainy season and there is no
evidence of a significant change in the length of the growing season. Over the same
time period, there has been a small, but significant, increase in mean air temperature
which has resulted in a small increase in potential evapotranspiration. Other climatic
parameters (vapour pressure, solar radiation and wind speed) appear to have
remained stable, although the paucity and dubious quality of much of the historical
meteorological data make rigorous statistical analysis difficult.
A water balance model (BALANCE) developed by the author, was calibrated for a
millet crop grown on a typical sandy loam soil in Maiduguri (Nigeria). The model
was necessarily parsimonious, but was shown to perform well when calibrated
against observed soil water content. However, the empirical nature and high
sensitivity of key parameters relating to bare soil evaporation and drainage mean that
it is difficult to parameterise the model by laboratory, or independent field
measurements.
Applying the calibrated model to daily rainfall and average evapotranspiration data
from Nguru (Nigeria) for the period 1961 – 93 showed that, with the exception of
extreme drought years, the increased aridity would have had little impact on the
viability of traditional millet and millet-cowpea intercropping systems prior to the
early 1980s. However, after that date, predicted seasonal millet transpiration, and
hence predicted yields, have declined, and long duration cowpea intercrops, which
were traditionally matured on residual soil moisture after the millet harvest have had
insufficient water.
Whilst the BALANCE model has been useful in examining the impact of climatic
variability on agro-hydrology, it is not a crop physiological model and the interaction
between soil water and crop development is poorly represented. The model cannot, therefore be applied with confidence to investigate the potential yield benefits of
physical or agronomic interventions to alleviate the impacts of aridity. Although
more complex models exist to do this, they require detailed parameterisation of the
crop physiology, which was not possible within the scope of this study
Structural analysis and parametric study ballasted track in sandy regions
No full textThe sand intrusion in railway tracks in sandy regions can significantly change the mechanical behaviour of tracks and thus threaten the safety of train operation. This paper presents substantial field tests on both sandy and clean railway tracks to study the effect of sand intrusion on the longitudinal resistance of ballast bed and the vibration behaviour of track structures. After that, a 3D multi-scale the discrete element model is developed to study the micro-contact between ballast particles and the vibration behaviour of sandy tracks during train passing in detail. Also, the effect of train speeds and axle loads on the mechanical behaviour of sandy tracks is discussed. The results show that the sand intrusion increases the vibration acceleration amplitude of rail and sleeper by 11.3% and 50.3%, while ballast bed decreases by 44.9%. Besides, the sand intrusion significantly changes the energy distribution in the track, wherein the frequencies of the highest energy of rail and sleeper are increased while that of the ballast bed is decreased. The parametric study shows the high train speed can cause the increase in overall acceleration of the ballast bed and high axle load can cause an increase in the micro-contact forces between ballast particles, diffusion angle of the contact force chain, displacements of ballast particles, acceleration of ballast particles, and sleeper displacements.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mechanics and Physics of Structure
Crushed rock and clay amelioration of a nutrient decifient, sandy soil of Maputaland
No full textBibliography: leaves 57-62.Various studies have suggested the possibility that food derived through subsistence agriculture in the Mseleni region of Maputaland contributes to malnutrition within the local community, particularfy within the high proportion of the population which suffers from a severe, disabling form of osteoarthritis. This study was conducted to determine if the application of local crushed rock or black clay to these nutrient deficient, sandy soils would increase available nutrient concentrations and improve the growth of plants in the ameliorated soil
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