PhD, EngD, DM and MSc by research theses (Silsoe)
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Browsing PhD, EngD, DM and MSc by research theses (Silsoe) by Course name "MPhil"
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Item Open Access Continuous mass flow measurement of granular materials(1997-10) Saunders, Stuart P.; Godwin, R. J.This thesis reports on the development of a double inclined plane (DIP) transducer system based upon the principles of force reaction. This transducer had a design specification to measure the true mass of “free” flowing granular materials, primarily agricultural crops, with an accuracy of ± 2 % on total mass flowed for flow rates between 1 and 10 kg/s. Two absolute values are used to assess accuracy in this study, (i) the total mass flowed (kg), a measure of the mass accumulation and, (ii) the mass flow rate (kg/s), a ‘spot’ reading of flow rate. The performance of the novel system has been evaluated through theoretical, laboratory and field studies and consideration has been given to the commercial and business aspects of the manufacture, marketing and further development of the device. Following mathematical and laboratory studies of the sponsors current force reaction transducer - a single reaction device, angular variations were highlighted as having a significant effect upon output. A further study found that the least sensitive reaction plate angle was 55° To overcome this problem, the double inclined plane (DIP) concept was developed, 2 single reaction plates, joined along their apexes, angled at 55 degrees to the horizontal, mounted upon a horizontal strain gauged beam. Angular compensation when tilting the transducer was provided by generating a higher force from the shallower face and a lower force from the steeper face. A mathematical model of the new transducer allowed the output to be predicted to within 1.7 %. Initial calibration was undertaken in the laboratory and tested using a combine clean grain system simulation apparatus. In-situ machine studies were performed by mounting the transducer in a New Holland TF42 combine, firstly on an extended bubble up auger and finally in the drop box, between the clean grain elevator and bubble up auger. Initial pilot studies were conducted with the combine static to calibrate the system and finally a full harvest field trial was undertaken. Over the harvest field trial, the accuracy on accumulated mass was better than 0.9 % over 127 tonnes. Tramline effects upon transducer output were found to be self cancelling, as the resulting positive and negative ‘spikes’ in the signal, when summed over time approximated to zero. Changes in pitch angle, up to 10 degree caused between 1.5 and -2.8 % randomly distributed error. Roll angles up to 7.5 degrees, caused between -0.9 % and 1.7 % randomly distributed error in static trials. Field beans and oilseed rape required calibration constants 6.8 % and 3.1 % lower than that for 12.5 % moisture content wheat, but with adjusted calibration constants, gave excellent repeatable results. Increasing moisture contents of up to 30 % in wheat resulted in the transducer under reading by, on average, 1.6 %. An assessment of manufacturing costs was made and the unit cost was £154.12 each for 30 units reducing to £109.59 each for 3000 units. It is recommended a pricing objective of maximising sales growth is used which will position the device at the less expensive end of the market. Due to commercial sensitivity, a draft patent has been written to protect the DIP concept. The first stages of commercial adoption already being undertaken by a major multi-national agricultural machinery company, who are evaluating a pre-production prototype. This thesis provides the systems, data and principles required to create a novel, commercially practical transducer system, based upon the principles of force reaction. The problem of angular compensation has been overcome in a simple and effective manner offering a relatively inexpensive but accurate method of measuring mass flow rate, which has already received commercial interest.Item Open Access Effects of 1-MCP on storage of "Queen cox" and "Bramley" apple fruit(2007) Dauny, Paul Trevor; Warner, P.; Joyce, Daryl C.Better maintenance of firmness and suppression of ethylene production in 'Queen Cox' and 'Bramley' apple [Ma/us sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] fruit was achieved by prestorage applications of 1-MCP. 1-MCP concentration, exposure time and exposure temperature ranges of 0.1 to 10.0 µl r1 1-MCP, 6 to 48 h and O to 20°C, respectively, were effective on fruit subsequently stored for 2 ('Cox') and 3 ('Bramley') months in air at 3 to 4°C. However, 1-MCP had little effect on either firmness or ethylene production after 4 ('Cox') or 6 ('Bramley') months storage. Nonetheless, 1-MCP treated 'Bramley' fruit had reduced rot and superficial scald incidence compared with untreated control fruit. 1-MCP application was most effective when applied within 24 h of harvest · compared to 14 d later. Earlier-harvested 'Cox' and 'Bramley' apple fruit showed better response to 1-MCP-treatment than those harvested towards the end of the picking season. 1-MCP-treatment was shown to improve apple storage alone and in combination with controlled atmosphere (CA) storage. Furthermore, 1-MCPtreatment maintained fruit quality during shelf-life better than CA storage alone. Chlorophyll fluorescence was not demonstrated to be an effective method to determine 'Cox' and 'Bramley' apple fruit quality. There was no recorded correlation between the concentration of five antifungal compounds and 1-MCP-treatment after inoculation with Penicillium expansum or Botrytis cinerea. 1-MCP treatment for apple storage was developed for AgroFresh Inc., the holder of the 1-MCP patent. Part of this research was used for the UK efficacy trials for registration of 1-MCP as an apple storage treatment. On the 18th July 2002 the US Environmental Protection Agency (EPA) granted approval for 1-MCP to be applied to food crops. Approval was granted in the UK in time for the 2003 apple harvest, and for 2004 across Europe.Item Open Access A GIS based dataset to assess the influence of countryside planning policies on landscape change in Bedfordshire(1994-02) Peccol, Elisabetta; Bird, Chris A.A GIS database for a study area (96 Km^) within the county of Bedfordshire (southern England) was established to provide statistical and mapped information on the distribution, extent and change through time of land-cover and landscape features between 1968, 1981 and 1991. A major aim of the project was to investigate the character of the countryside designation zones operating in Bedfordshire in terms of detailed local landscape. The effectiveness of the policies for the countryside was assessed in terms of the landscape changes monitored in each area. To this purpose a census of landscape features was carried out by means of aerial photographic interpretation and the differences between the three dates were measured. The classification scheme included 19 land-cover types (area features), 6 linear features and 6 point features. A Digital Terrain Model was used to analyse the land-fonn of the study area and its influence on the distribution of land-cover types. The countryside designation zones were digitised from the Local Plans and processed with the land-cover maps. The results of the project are represented by maps, tables and charts of landscape features for each date and their changes between each date, in the study area and in the countryside designation zones. The study area is shown to be intensively managed since agro-pastoral and developed land cover most of its area. Countryside designation zones showed a strong agro-pastoral character, except for the Sites of Special Scientific Interest and the National Nature Reserve. Generally, over the two decades analysed, both the study area and the countryside designation zones suffered changes in landscape features.Item Open Access Improvements to furrow press performance(1989-03) Hagan, B; Hann, Michael J.The objective of this project was to, improve the performance of the furrow press, with particular regard to three applications: i) consolidation in light land ii) clod breaking in clay soils iii) tilth production in medium soils Work conducted by Ansell (1986) led to the suggestion that a press consisting of different diameter wheels on the same axle might satisfy some or all of these requirements. This project began by studying the action of a press in two dimensions (horizontal-vertical plane) using short sections of press wheels in a glass sided soil tank. Different combinations and spacings were considered and their effectiveness measured by breaking clods in the soil. Different shaped sections were also tested, using loose soil to study the effect of shape on soil movement. Following the two-dimensional testing, a range of different diameter press rings were tested in the Silsoe College Soil Bin. A number of diameter /spacing combinations were used, and each was evaluated at three different weight levels. The resulting soil profiles were measured, together with plate penetrometer tests as an indicator of soil density. It was found that an excess of weight could cause a reduction in average soil strength by greatly reducing surface bulk density. Using the combinations selected from the work in the soil bin a number of full width presses were tested on seven field sites, ranging from a very sandy loam to a wet clay loam. Profiles were measured before and after passing a tractor over the work. The sinkage was proportional to the soil strength. Photographs were taken and analysed to rank the treatments in terms of clod size reduction. Evaluation of the field trials has led to the development of a composite press with a geometry and weight arrangement that has produced significant improvements in light land consolidation, clod size reduction and tilth production.Item Open Access Use of sap flow measuring techniques to estimate water-use of multi-stem plants(2006-01-19) Seymour, Ian Leslie; Burgess, Paul J.In the UK, coppice willow is a potentially high yielding energy crop which if widely planted could have significant effects of hydrology. This is one reason why researchers are interested in developing reliable techniques for estimating whole-plant water use of such trees. In recent years various sap flow measuring techniques have become commercially available. The aim of this thesis was to evaluate the reliability sap flow measurement and to consider issues related to best practice when used on multi-stemmed woody plants. The thesis starts by reviewing methodologies for estimating tree water-use with particular focus on sap flow gauges. Subsequently over three years, experiments were undertaken using a commercially available Stem Heat Balance (SHB) sap flow gauges, manufactured by Dynamax Inc, Houston, Texas, on coppice willow grown in lysimeters. Plant responses were monitored through a range of soil-water conditions from flood to drought. Over three years a methodology for deriving an accurate assessment of total plant water-use using a lysimeter water balance (LWB) was developed. Whole-plant water-use, estimated from scaled up sap flow measurements from individual stems were compared against LWB values. Both, stem basal area and leaf area were used as scalars to derive values of plant water-use. In the final experiment, four out of eight, different sized sap flow gauges, with the appropriate scalar, gave estimates similar (±7%) to LWB values of whole-plant water use over a period of ‘unstressed’ growing conditions. Variation in the accuracy of estimates was considered to be a function of a) error inherent to the SHB technique, b) error in scalar values used to derive whole-plant estimates, and c) apparently autonomous responses of individual stems to changes in soil water status. In non-water stressed conditions and where sap flow rates are high, errors from the technique were minimised by selecting Targe’ stems (16-19 mm diameter). Under extreme water stress conditions, reductions in leaf area can result in errors if the estimate is based on stem diameter. Where individual stem flow rates were perturbed by changes in soil-water conditions, selecting an ‘intermediate’ sized stem (in this case 10-13 mm diameter) appeared to minimise errors.