382 research outputs found
Numerical simulations of strong wind situations near the Mediteranean French Coast: comparison with FETCH data
No full textA detailed analysis is made of some typical strong wind situations near the French Mediterranean coast. Special attention has been paid to the wind from the north-northwest in the Gulf of Lion, also called the mistral. The analysis is made from both the synoptic and mesoscale point of view with the aid of numerical simulations carried out with the Regional Atmospheric Modeling System (RAMS) to study the main atmospheric, climatic, and meteorological characteristics of this wind in the Gulf of Lion. Simulations were made with this model during the periods of 20-22 March and 24-26 March 1998. Afterward, a comparison was made with the meteorological measurements collected during the international Flux, Etat de la Mer et Te´le´de´tection en Condition de Fetch Variable (FETCH) campaign (Gulf of Lion, March-April 1998). The comparison between the simulated wind fields and the values measured by the coastal meteorological stations, an oceanographic buoy, and the ship Atalante at sea help to give full understanding of the complicated physical processes that characterize strong wind situations in coastal zone
Finite-Element Tree Crown Hydrodynamics model (FETCH) using porous media flow within branching elements - a new representation of tree hydrodynamics
No full textEstimating transpiration and water flow in trees remains a major challenge for quantifying water exchange between the biosphere and the atmosphere. We develop a finite element tree crown hydrodynamics (FETCH) model that uses porous media equations for water flow in an explicit three‐dimensional branching fractal tree‐crown system. It also incorporates a first‐order canopy‐air turbulence closure model to generate the external forcing of the system. We use FETCH to conduct sensitivity analysis of transpirational dynamics to changes in canopy structure via two scaling parameters for branch thickness and conductance. We compare our results with the equivalent parameters of the commonly used resistor and resistor‐capacitor representations of tree hydraulics. We show that the apparent temporal and vertical variability in these parameters strongly depends on structure. We suggest that following empirical calibration and validation, FETCH could be used as a platform for calibrating the “scaling laws” between tree structure and hydrodynamics and for surface parameterization in meteorological and hydrological models
Summit oat
No full text Mitchell Fetch, J. W., Brown, P. D., Ames, N., Chong, J., Fetch, Jr., T. G., Haber, S. M., Menzies, J. G., Tekauz, A., Townley-Smith, T. F. and Stadnyk, K. D. 2011. Summit oat. Can. J. Plant Sci. 91: 787–791. Summit is a white-hulled spring oat (Avena sativa L.) cultivar postulated to carry the crown rust resistance combination Pc38, Pc39, Pc48, and Pc68, which was effective against the prevalent pathotypes of crown rust on the Canadian prairies at the time of its release. It has very good resistance to loose and covered smut, moderately good resistance to most of the prairie stem rust races (likely due to the presence of Pg2 and Pg13) and is resistant to moderately resistant to barley yellow dwarf virus (BYDV). Summit has good kernel weight, percent plump kernels, and percent thin kernels. Summit exhibits high yielding capacity in the oat growing areas of western Canada. Summit was registered (Reg. No. 6529) in Canada 2008 November 29. </jats:p
Stainless oat
No full text Mitchell Fetch, J. W., Brown, P. D., Ames, N., Chong, J., Fetch, Jr., T. G., Haber, S. M., Menzies, J. G., Townley-Smith, T. F. and Stadnyk, K. D. 2011. Stainless oat. Can. J. Plant Sci. 91: 357–361. Stainless is a grey-hulled spring oat (Avena sativa L.) cultivar postulated to carry the crown rust resistance gene, Pc91, which was effective against the prevalent pathotypes of crown rust races on the Canadian prairies at the time of its release. Stainless could possibly also carry one or more of the crown rust resistance genes, Pc38, Pc39, and Pc68. It had very good resistance to loose and covered smut, good resistance to the prairie stem rust races (likely due to the presence of Pg2, Pg13, and Pga) and moderate tolerance to barley yellow dwarf virus (BYDV). Stainless had high kernel weight, intermediate percent plump kernels, intermediate percent thin kernels, and high levels of total dietary fibre. Stainless exhibited high yielding capacity in the eastern portion of the Black soil zone of western Canada where resistance to rust diseases is important. Stainless was supported for registration by the Prairie Grain Development Committee in February 2007. Stainless was registered (Reg. No. 6422) on 2008 Apr. 07. </jats:p
Wind-profile measurements above a maize crop
No full textAn experiment of wind-profile measurements above a maize crop was described. First the mean ratio between the height of the adapted layer and the fetch was deduced from profile measurements at several positions in the field. The height-to-fetch ratio amounted to 1/64. Because of too small a fetch, the vertical transport of momentum between the maize crop and the atmosphere could not be estimated accurately enough from the windprofile measurements only. The parameters of the assumed logarithmic wind profile, the zero-plane displacement and the roughness length, could only be estimated from a comparison of wind-profile measurements with simultaneous eddy-correlation measurements. In the present experiment, the zeroplane displacement d and the roughness length z0 could be expressed in the height h of the full-grown crop as d = 0.5 h and z0 = 0.11 h, respectively. The application of a common empirical relationship from the literature (e.g. d = 0.6 h ) led to considerable systematic errors of the estimated friction velocity above maize
Norman barley
No full text Legge, W. G., Tucker, J. R., Bizimungu, B., Tekauz, A., Noll, J. S., Fetch Jr., T. G., Menzies, J. G., Haber, S., Savard, M. E., Vigier, B. J., Choo, T. M., Martin, R. A., Turkington, T. K., Rossnagel, B. G. and Harvey, B. L. 2011. Norman barley. Can. J. Plant Sci. 91: 1105–1113. Norman is a hulled two-row spring malting barley (Hordeum vulgare L.) cultivar derived from the cultivar CDC Kendall that was widely grown in western Canada and utilized commercially by the malting and brewing industry. Developed in 2000 by in vitro selection using deoxynivalenol mycotoxin in the medium of an anther culture system, Norman was evaluated in the Western Cooperative Two-row Barley Registration Test in 2005 and 2006, and the malting and brewing industry Collaborative Malting Barley Trials in 2006 and 2007, before being registered in 2009. Norman was also evaluated extensively for deoxynivalenol concentration in fusarium head blight (Fusarium graminearum Schwabe) nurseries from 2001 to 2009. Norman accumulates 25 to 30% less deoxynivalenol than its parent cultivar, CDC Kendall, but is similar in all other traits including malting quality. </jats:p
The fetch effect on aeolian sediment transport on a sandy beach: a case study from Magilligan Strand, Northern Ireland
No full textExperiments were conducted on Magilligan Strand, Northern Ireland, to assess the influence of the fetch effect on aeolian sediment transport. During each experiment surface sediments were uniformly dry and unhindered by vegetation or debris. The leading edge of erodible material was well defined, with the limit of wave up-rush demarcating the wet-dry boundary; the work was conducted during low tides. A number of electronic and integrating traps were utilised, with two ultrasonic anemometers used to measure wind direction and velocity at 1 Hz. The combination of 1 degrees direction data and trap locations resulted in a range of fetch distances, from 2 to 26 m. Data integrated over 15-minute intervals (corresponding to the integrating trap data) revealed a distinct trend for all the experiments. An initial rapid increase in the transport rate occurred over a short distance (4-9 m). This maximum transport rate was maintained for a further 5-6 m before a steady decay in the flux followed, as fetch distance increased. A measured reduction in wind speed (6-8%) across the beach suggests a negative feedback mechanism may be responsible for the diminishing transport rate: the saltating grains induce energy dissipation, thus reducing the capability of the wind to maintain transport. For one experiment, the presence of compact sediment patches may also have contributed to the reduction of the transport rate. The decay trend calls into question the utility of the fetch effect as an important parameter in aeolian studies that seek to understand sediment budgets of the foredune-beach zone. Copyright (C) 2016 John Wiley & Sons, Ltd.This work is part of a Vice Chancellor\u27s Research Scholarship funding for PhD studies at the Centre for Coastal and Marine Research, School of Environmental Sciences, University of Ulster
Supporting aspect-based video browsing - analysis of a user study
No full textIn this paper, we present a novel video search interface based on the concept of aspect browsing. The proposed strategy is to assist the user in exploratory video search by actively suggesting new query terms and video shots. Our approach has the potential to narrow the "Semantic Gap" issue by allowing users to explore the data collection. First, we describe a clustering technique to identify potential aspects of a search. Then, we use the results to propose suggestions to the user to help them in their search task. Finally, we analyse this approach by exploiting the log files and the feedbacks of a user study
Mapping Fetch and Diel Movements of Silver Carp Hypophthalmichthys molitrix Within Kentucky Lake and Lake Barkley With GIS
No full textTitle: Mapping Silver Carp movements, relative exposure, and fetch within inland reservoirs using Geographic Information Systems.
Author: Levi G Umland
Invasive species across our country have continued to threaten our native species, compete for habitat via interspecific competition, and have caused economic impacts. Silver Carp (Hypophthalmichthys molitrix), commonly referred to as Asian Carp, have remained in the invasive species spotlight throughout the southern and mid-western states as they have continued to spread. Silver Carp have successfully spread through our rivers and reservoirs, but little is known about Silver Carp movement rates/behavior within reservoirs due to their lower abundance within reservoirs. Within this tracking study, we have mapped the diel movements of Silver Carp, relative exposure, and fetch within Kentucky Lake and Lake Barkley using a Geographic Information System (GIS) and time series analysis. The goal of this project is to discover if Silver Carp movement rates and/or habitat usage are influenced by wind. Initial results indicate that wind direction/velocity may indeed impact movement rates and habitat use
Predicting agronomic performance of barley using canopy reflectance data
No full textThe ability to accurately and rapidly predetermine agronomic performance would be desirable in most plant breeding programs. Remote sensing of canopy reflectance is a quick and nondestructive method that may be useful in the estimation of agronomic performance. Studies were conducted at Fargo and Langdon, North Dakota, to determine the effectiveness of a multispectral radiometer in estimating yield, kernel plumpness (KP), and 1000-kernel weight (TKW) in barley. Canopy reflectance was measured in eight (500–850 nm) discrete narrow-wavelength bands. Three types of reflectance models were evaluated: simple models using one to four wavelengths, simple ratio and normalized difference vegetation indices (NDVI) using green, red, and near-infrared wavelengths, and soil-adjusted vegetation indices (SAVI). The relationship between canopy reflectance and agronomic performance was significantly influenced by environment, growth stage, and plant genotype. Grain yield was best estimated near GS73 (0.84 < R2 < 0.92) at Fargo and at GS83 (0.55 < R2 < 0.81) at Langdon. In contrast, KP and TKW could be estimated at both late (GS83; 0.68 < R2 < 0.93) and early (GS24–GS47; 0.72 < R2 < 0.91) growth stages. The 550-nm and 800-nm wavelengths are critical for development of predictive models. A simple model using 550-nm, 600-nm, and 800-nm from GS47-GS73 gave significant (0.45 < R2 < 0.64) estimation of agronomic performance across all environments. In contrast, simple ratio, NDVI, and SAVI were less effective (0.05 < R2 < 0.77) in predicting agronomic performance. Remote sensing using canopy reflectance is a potential tool to estimate agronomic performance of barley, but genotypic and crop stage factors affect this method. Further studies are needed to improve the usefulness of multispectral radiometry in predicting agronomic performance.Steffenson, Brian; Fetch, T.G.; Pederson, V.D.. (2004). Predicting agronomic performance of barley using canopy reflectance data. Retrieved from the University Digital Conservancy, 10.4141/P02-195
- …
