School of Applied Sciences (SAS) (2006-July 2014)
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Browsing School of Applied Sciences (SAS) (2006-July 2014) by Publisher "Blackwell Publishing Ltd"
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Item Open Access Amplitude of probability density function (APDF) of vibration response as a robust tool for gearbox diagnosis(Blackwell Publishing Ltd, 2012-12-31T00:00:00Z) Rzeszucinski, P. J.; Sinha, J. K.; Edwards, Rodger; Starr, Andrew G.; Allen, B.A ‘Go' or ‘No Go' assessment is a safety requirement for quick and robust estimation of the condition of gearboxes used in helicopters and other critical machines. A range of vibration-based condition indicators (CIs) has been developed to meet this requirement. CIs are compared automatically with pre-set threshold values representing a healthy system, so that the health of the gearbox can be assessed and diagnosis made where necessary. The use of kurtosis of the residual signal of the measured vibration data, computed as part of the ‘FM4' method, is widespread, because it is accepted as a good and reliable indicator. However, it has been observed in some cases that FM4 may not show a continually increasing trend with the propagation of a fault. This behaviour may lead to improper assessment of the severity of the fault. Hence, a new CI, based on the deviation in the normal probability density function (PDF) of the measured vibration data, is suggested which demonstrates an increasing trend that is more robustly and monotonically correlated with the fault propagation.Item Open Access Ecohydrology of a seasonal wetland in the Rift Valley: ecological characterization of Lake Solai(Blackwell Publishing Ltd, 2009-09-30T00:00:00Z) De Bock, Tanguy; Kervyn De Meerendré, Baptiste; Hess, Tim M.; Gouder De Beauregard, Anne-ChristineThe following research describes through an ecohydrological approach, the first assessment of the ecology of Lake Solai, with a particular emphasis on the vegetation. Lake Solai is located 50 km north of Nakuru in the Rift Valley in Kenya at E36°80′-36°84′ to N00°05′- 00°08′. It is a shallow lake that follows a very peculiar seasonal water regime, and that faces conflicts between agriculture and conservation water users. In the upper catchment, an overview of the agricultural practices was implemented and river water uses were identified to assess river flows. Crops/grassland and woodland/shrubland were the major land uses, covering c. 65% of the catchment. Closer to the lake, vegetation samples were collected around the lake together with samples of environmental factors such as soil and water quality. Thirteen vegetation communities were identified within four main zonations: forest, grassland, river inlet and rocky outcrop. These communities showed abundance, distribution and diversity determined mostly by the human pressures, the flooding periods and the salinity. Cynodon, Cyperus and Sporobolus genera were the most abundantItem Open Access Influence of the number of samples on prediction error of visible and near infrared spectroscopy of selected soil properties at the farm scale.(Blackwell Publishing Ltd, 2013-01-23) Kuang, Boyan Y.; Mouazen, Abdul MounemAlthough visible and near infrared (vis-NIR) spectroscopy has proved to be a fast, inexpensive and relatively accurate tool to measure soil properties, considerable research is required to optimise the calibration procedure and establish robust calibration models. This paper reports on the influence of the number of samples used for the development of farm-scale calibration models for moisture content (MC), total nitrogen (TN) and organic carbon (OC) on the prediction error expressed as root mean square error of prediction (RMSEP). Fresh (wet) soil samples collected from four farms in Czech Republic, Germany, Denmark and the UK were scanned with a fibre type vis-NIR, AgroSpec spectrophotometer (tec5 Technology for Spectroscopy, Germany) with a spectral range of 305 - 2200 nm. Spectra were divided into calibration (two-third) and prediction (one-third) sets and the calibration spectra were subjected to a partial least squares regression (PLSR) with leave-one-out cross validation using Unscrambler 7.8 software (Camo Inc., Oslo, Norway). The RMSEP values of models with large sample number (46 - 84 samples from each farm) were compared with those of models developed using small sample number (25 samples selected from the large sample set of each farm) for the same variation range. Both large set and small set models were validated by the same prediction set for each property. Further PLSR analysis was carried out on samples from the German farm, with different sample number of the calibration set of 25, 50, 75 and 100 samples. Results showed that the large-size dataset models resulted in lower RMSEP values than the small-size dataset models for all the soil properties studied. The results also demonstrated that with the increase in sample number used in the calibration set, RMSEP decreased in almost linear fashion, although the largest decrease was between 25 and 50 samples. Therefore, it is recommended to chose the number of samples according to accuracy required, although 50 soil samples is considered appropriate in this study to establish calibration models of TN, OC and MC with smaller expected prediction errors as compared with smaller sample numbers.Item Open Access Integrated models of livestock systems for climate change studies. 1. Grazing systems.(Blackwell Publishing Ltd, 2001-01-01T00:00:00Z) Parsons, David J.; Armstrong, A. C.; Turnpenny, J. R.; Matthews, A. M.; Cooper, K. C.; Clark, J. A.The potential impact of climate change by the year 2050 on British grazing livestock systems is assessed through the use of simulation models of farming systems. The submodels, consisting of grass production, livestock feeding, livestock thermal balance, the thermal balance of naturally ventilated buildings and a stochastic weather generator, are described. These are integrated to form system models for sheep, beef calves and dairy cows. They are applied to scenarios representing eastern (dry) lowlands, western (wet) lowlands and uplands. The results show that such systems should be able to adapt to the expected climatic changes. There is likely to be a small increase in grass production, possibly allowing an increase in total productivity in some cases.Item Open Access Integrated models of livestock systems for climate change studies. 2. Intensive systems.(Blackwell Publishing Ltd, 2001-01-01T00:00:00Z) Turnpenny, J. R.; Parsons, David J.; Armstrong, A. C.; Clark, J. A.; Cooper, K. C.; Matthews, A. M.The potential impact of climate change by the year 2050 on intensive livestock systems in Britain is assessed through the use of simulation models of farming systems. The submodels comprise livestock feeding, livestock thermal balance and the thermal balance of controlled environment buildings and a stochastic weather generator. These are integrated to form system models for growing pigs and broiler chickens. They are applied to scenarios typical of SE England, which is the warmest region of the country and represents the worst case. For both species the frequency of severe heat stress is substantially increased, with a consequent risk of mortality. To offset this, it would be necessary to reduce stocking densities considerably, or to invest in improved ventilation or cooling equipment. Other effects on production are likely to be small.Item Open Access Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis(Blackwell Publishing Ltd, 2012-12-31T00:00:00Z) Rzeszucinski, P. J.; Sinha, J. K.; Edwards, Rodger; Starr, Andrew G.; Allen, B.Quick assessment of the condition of gearboxes used in helicopters is a safety requirement. One of the most widely used helicopter on-board-mounted condition monitoring system these days is the Health and Usage Monitoring System. It has been specifically designed to monitor the condition of all safety-critical components operating in the helicopter through calculation of so-called condition indicators (CIs) - signal processing routines designed to output a single number that represents the condition of the monitored component. Among number of available parameters, there is a couple of CIs that over the years of testing have earned a reputation of being the most reliable measures of the gear tooth condition. At the same time, however, it has been observed that in some cases, those techniques do not properly indicate the deteriorating condition with the propagation of a gear tooth fault with the period of operation. Hence, three more robust methods have been suggested, which are discussed in this article.Item Open Access A systems approach to the policy-level risk assessment of exotic animal diseases: network model and application to classical swine fever.(Blackwell Publishing Ltd, 2013-08-31T00:00:00Z) Delgado, Joao Pedro Correa; Pollard, Simon J. T.; Snary, E. L.; Black, Edgar; Prpich, George; Longhurst, Philip J.Exotic animal diseases (EADs) are characterized by their capacity to spread global distances, causing impacts on animal health and welfare with significant economic consequences. We offer a critique of current import risk analysis approaches employed in the EAD field, focusing on their capacity to assess complex systems at a policy level. To address the shortcomings identified, we propose a novel method providing a systematic analysis of the likelihood of a disease incursion, developed by reference to the multibarrier system employed for the United Kingdom. We apply the network model to a policy-level risk assessment of classical swine fever (CSF), a notifiable animal disease caused by the CSF virus. In doing so, we document and discuss a sequence of analyses that describe system vulnerabilities and reveal the critical control points (CCPs) for intervention, reducing the likelihood of U.K. pig herds being exposed to the CSF virus.Item Open Access Using stochastic dynamic programming to support weed management decisions over a rotation(Blackwell Publishing Ltd, 2009-04-01T00:00:00Z) Benjamin, L. R.; Milne, Alice E.; Lutman, P. J. W.; Parsons, David J.; Cussans, J.; Storkey, J.This study describes a model that predicts the impact of weed management on the population dynamics of arable weeds over a rotation and presents the economic consequences. A stochastic dynamic programming optimisation is applied to the model to identify the management strategy that maximises gross margin over the rotation. The model and dynamic programme were developed for the weed management decision support system -'Weed Manager'. Users can investigate the effect of management practices (crop, sowing time, weed control and cultivation practices) on their most important weeds over the rotation or use the dynamic programme to evaluate the best theoretical weed management strategy. Examples of the output are given in this paper, along with discussion on their validation. Through this study, we demonstrate how biological models can (i) be integrated into a decision framework and (ii) deliver valuable weed management guidance to users.Item Open Access Will European soil-monitoring networks be able to detect changes in topsoil organic carbon content?(Blackwell Publishing Ltd, 2008-10-31T00:00:00Z) Saby, N. P. A.; Bellamy, Patricia H.; Morvan, X.; Arrouays, D.; Jones, Robert J. A.; Verheijen, Frank G. A.; Kibblewhite, Mark G.; Verdoodt, A.; Üveges, J.; Freudenschuß, A.; Simota, C.Within the United Nations Framework Convention on Climate Change, articles 3.3 and 3.4 stipulate that some voluntary activities leading to an additional carbon (C) sequestration in soils could be accounted as C sinks in national greenhouse gas inventories. These additional C stocks should be verifiable. In this work, we assess the feasibility of verifying the effects of changes in land use or management practice on soil organic carbon (SOC), by comparing minimum detectable changes in SOC concentration for existing European networks suitable for soil monitoring. Among the tested scenarios, the minimum detectable changes differed considerably among the soil-monitoring networks (SMNs). Considerable effort would be necessary for some member states to reach acceptable levels of minimum detectable change for C sequestration accounting. For SOC, a time interval of about 10 years would enable the detection of some simulated large changes in most European countries. In almost all cases, the minimum detectable change in SOC stocks remains greater than annual greenhouse gases emissions. Therefore, it is unlikely that SMNs could be used for annual national C accounting. However, the importance of organic C in soil functions, and as an indicator of soil condition and trends, underlines the importance of establishing effective national SMNs.