54 resultados para Systems evaluation

em CentAUR: Central Archive University of Reading - UK


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The main objective of this study is to revisit the fundamental postulations of autopoietic self-production wrapped within the autopoietic six-point key and to investigate whether or not firms as specific social systems can be treated as autopoietic unities. In order to do so firms have to be defined as simple and composite unities whereupon their boundaries have to be clearly identifiable. The test of social autopoiesis reveals that firms can be viewed as autopoietic social systems that exist in the communicative space with employees' firm-specific communicative sub-domains as their components. Furthermore, it is argued that the social reification of autopoiesis (autokoinopoiesis) in firms is quintessentially interconnected with physical autopoiesis of their employees (autophysiopoiesis). Discontiguous focus on productivity as firms' obvious physical implication may thus be upgraded by a very social nature of ideactivity, firms' only real survival force.

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We introduce a technique for assessing the diurnal development of convective storm systems based on outgoing longwave radiation fields. Using the size distribution of the storms measured from a series of images, we generate an array in the lengthscale-time domain based on the standard score statistic. It demonstrates succinctly the size evolution of storms as well as the dissipation kinematics. It also provides evidence related to the temperature evolution of the cloud tops. We apply this approach to a test case comparing observations made by the Geostationary Earth Radiation Budget instrument to output from the Met Office Unified Model run at two resolutions. The 12km resolution model produces peak convective activity on all lengthscales significantly earlier in the day than shown by the observations and no evidence for storms growing in size. The 4km resolution model shows realistic timing and growth evolution although the dissipation mechanism still differs from the observed data.

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Grass-based diets are of increasing social-economic importance in dairy cattle farming, but their low supply of glucogenic nutrients may limit the production of milk. Current evaluation systems that assess the energy supply and requirements are based on metabolisable energy (ME) or net energy (NE). These systems do not consider the characteristics of the energy delivering nutrients. In contrast, mechanistic models take into account the site of digestion, the type of nutrient absorbed and the type of nutrient required for production of milk constituents, and may therefore give a better prediction of supply and requirement of nutrients. The objective of the present study is to compare the ability of three energy evaluation systems, viz. the Dutch NE system, the agricultural and food research council (AFRC) ME system, and the feed into milk (FIM) ME system, and of a mechanistic model based on Dijkstra et al. [Simulation of digestion in cattle fed sugar cane: prediction of nutrient supply for milk production with locally available supplements. J. Agric. Sci., Cambridge 127, 247-60] and Mills et al. [A mechanistic model of whole-tract digestion and methanogenesis in the lactating dairy cow: model development, evaluation and application. J. Anim. Sci. 79, 1584-97] to predict the feed value of grass-based diets for milk production. The dataset for evaluation consists of 41 treatments of grass-based diets (at least 0.75 g ryegrass/g diet on DM basis). For each model, the predicted energy or nutrient supply, based on observed intake, was compared with predicted requirement based on observed performance. Assessment of the error of energy or nutrient supply relative to requirement is made by calculation of mean square prediction error (MSPE) and by concordance correlation coefficient (CCC). All energy evaluation systems predicted energy requirement to be lower (6-11%) than energy supply. The root MSPE (expressed as a proportion of the supply) was lowest for the mechanistic model (0.061), followed by the Dutch NE system (0.082), FIM ME system (0.097) and AFRCME system(0.118). For the energy evaluation systems, the error due to overall bias of prediction dominated the MSPE, whereas for the mechanistic model, proportionally 0.76 of MSPE was due to random variation. CCC analysis confirmed the higher accuracy and precision of the mechanistic model compared with energy evaluation systems. The error of prediction was positively related to grass protein content for the Dutch NE system, and was also positively related to grass DMI level for all models. In conclusion, current energy evaluation systems overestimate energy supply relative to energy requirement on grass-based diets for dairy cattle. The mechanistic model predicted glucogenic nutrients to limit performance of dairy cattle on grass-based diets, and proved to be more accurate and precise than the energy systems. The mechanistic model could be improved by allowing glucose maintenance and utilization requirements parameters to be variable. (C) 2007 Elsevier B.V. All rights reserved.

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Very large scale scheduling and planning tasks cannot be effectively addressed by fully automated schedule optimisation systems, since many key factors which govern 'fitness' in such cases are unformalisable. This raises the question of an interactive (or collaborative) approach, where fitness is assigned by the expert user. Though well-researched in the domains of interactively evolved art and music, this method is as yet rarely used in logistics. This paper concerns a difficulty shared by all interactive evolutionary systems (IESs), but especially those used for logistics or design problems. The difficulty is that objective evaluation of IESs is severely hampered by the need for expert humans in the loop. This makes it effectively impossible to, for example, determine with statistical confidence any ranking among a decent number of configurations for the parameters and strategy choices. We make headway into this difficulty with an Automated Tester (AT) for such systems. The AT replaces the human in experiments, and has parameters controlling its decision-making accuracy (modelling human error) and a built-in notion of a target solution which may typically be at odds with the solution which is optimal in terms of formalisable fitness. Using the AT, plausible evaluations of alternative designs for the IES can be done, allowing for (and examining the effects of) different levels of user error. We describe such an AT for evaluating an IES for very large scale planning.

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In this paper, we evaluate the Probabilistic Occupancy Map (POM) pedestrian detection algorithm on the PETS 2009 benchmark dataset. POM is a multi-camera generative detection method, which estimates ground plane occupancy from multiple background subtraction views. Occupancy probabilities are iteratively estimated by fitting a synthetic model of the background subtraction to the binary foreground motion. Furthermore, we test the integration of this algorithm into a larger framework designed for understanding human activities in real environments. We demonstrate accurate detection and localization on the PETS dataset, despite suboptimal calibration and foreground motion segmentation input.

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Integrated Arable Farming Systems (IAFS), which involve a reduction in the use of off-farm inputs, are attracting considerable research interest in the UK. The objectives of these systems experiments are to compare their financial performance with that from conventional or current farming practices. To date, this comparison has taken little account of any environmental benefits (or disbenefits) of the two systems. The objective of this paper is to review the assessment methodologies available for the analysis of environmental impacts. To illustrate the results of this exercise, the methodology and environmental indicators chosen are then applied to data from one of the LINK - Integrated Farming Systems experimental sites. Data from the Pathhead site in Southern Scotland are used to evaluate the use of invertebrates and nitrate loss as environmental indicators within IAFS. The results suggest that between 1992 and 1995 the biomass of earthworms fell by 28 kg per hectare on the integrated rotation and rose by 31 kg per hectare on the conventional system. This led to environmental costs ranging between £2.24 and £13.44 per hectare for the integrated system and gains of between £2.48 and £14.88 for the conventional system. In terms of nitrate, the integrated system had an estimated loss of £72.21 per hectare in comparison to £149.40 per hectare on the conventional system. Conclusions are drawn about the advantages and disadvantages of this type of analytical framework. Keywords: Farming systems; IAFS; Environmental valuation; Economics; Earthworms; Nitrates; Soil fauna

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The prebiotic effect of oligosaccharides recovered and purified from caprine whey, was evaluated by in vitro fermentation under anaerobic conditions using batch cultures at 37ºC with human faeces. Effects on key gut bacterial groups were monitored over 24h by fluorescence in situ hybridisation (FISH), which was used to determine a quantitative prebiotic index score. Production of short-chain fatty acids (SCFAs) as fermentation end products was analysed by high-performance liquid chromatography (HPLC). Growth of Bifidobacterium spp was significantly higher (p ≥ 0.05) with the purified oligosaccharides compared to the negative control. Lactic and propionic acids were the main SCFAs produced. Antimicrobial activity of the oligosaccharides was also tested, revealing no inhibition though a decrease in Staphylococcus aureus and Escherichia coli growth. These findings indicate that naturally extracted oligosaccharides from caprine whey could be used as new and valuable source of prebiotics.

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Information systems integration aims at the interaction, information exchange and interoperability between information systems, devices and units. Research efforts have contributed in evaluation of information systems integration on the development of evaluation frameworks. To improve the usability and measurability of evaluation, a review of existing evaluation frameworks including their evolution and classifications of different interoperability levels is conducted. The theory of organisational semiotics is used for a comparative analysis of the frameworks and future work.

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Lactobacillus plantarum C4 has been tested in in vitro pH-controlled anaerobic faecal batch cultures as compared to Lactobacillus rhamnosus GG to determine changes caused to the composition of faecal bacteria. Effects upon major groups of the microbiota and levels of short-chain fatty acids (SCFA) were assessed over 24 h. Concomitantly, hydrophobic character and ability of both bacterial cells to adhere in vitro to Caco-2 cells were investigated. Quantitative analysis of bacterial populations revealed that there was a significant increase in Lactobacillus/Enterococcus numbers in vessels with probiotic supplemented with fructooligosaccharides (FOS), compared to the negative control. L. plantarum C4 showed to have more hydrophilic behaviour and fulfilled better adhesive properties, compared to L. rhamnosus GG. Thus, L. plantarum C4 can modulate the intestinal microbiota in vitro, promoting changes in some numerically and metabolically relevant microbial populations and shifts in the production of SCFA.