108 research outputs found
Optimization and sensitivity analysis of computer simulation models by the score function method
No full textExperimental Design;Simulation;Optimization;Queueing Theory
Optimal design of simulation experiments with nearly saturated queues
No full textSimulation Models;Interpolation;Queueing Network;Extrapolation
Research and development on climate change and greenhouse gases in support of climate-smart livestock production and a vibrant industry
No full textClimate change represents a feedback-loop in which livestock production both contributes to the problem and suffers from the consequences. The impact of global warming and continued, uncontrolled release of greenhouse gasses (GHG) has twofold implications for the livestock industry, and consequently food security. Firstly, the continuous increase in ambient temperature is predicted to have a direct effect on the animal, as well as on food and nutrition security, due to changes associated with temperature itself, relative humidity, rainfall distribution in time and space, altered disease distribution, changes in the ecosystem and biome composition. Secondly, the responsibility of livestock production is to limit the release of greenhouse gases (GHG) or the carbon footprint, in order to ensure future sustainability. This can be done by implementing new or adapted climate-smart production systems, the use of known and new technologies to turn waste into assets, and by promoting sustainable human diets with low environmental impacts. The following elements, which are related to livestock production and climate change, are discussed in this paper: (1) restoring the value of grasslands/rangelands, (2) pastoral risk management and decision support systems, (3) improved production efficiency, (4) global warming and sustainable livestock production, (5) the disentanglement between food and nutritional needs, focusing on nutrient rich core foods, (6) GHG from livestock and carbon sequestration, and (7) water and waste management. No single organization (or industry) within South Africa can perform this research and the implementation thereof on its own. The establishment of a (virtual) centre of excellence in climate-smart livestock production and the environment for the livestock industries, with the objective to share research expertise and information, build capacity and conduct research and development studies, should be a priority.This work is based on research supported in part by Red Meat Research and Development South Africa and the National Research Foundation of South Africa (NRF), under grant UID 75123.http://www.sasas.co.za/am201
Effects of active immunization against androstenedione on the reproductive performance of Merino ewes
No full textNo Abstrac
The induction of puberty in female Boer goat kids
No full textThe effects of season, nutrition and presence of a ram at the onset of puberty in female Boer goat kids were studied. Permanent presence of a vasectomised ram with the female goat kids induced puberty earlier (P0.05) from female goat kids put on a low energy diet. Female Boer goat kids born in summer and weaned in autumn attained puberty earlier (P<0.05) than those born in spring and weaned in summer. The results of this study suggest that the reproductive functions, such as puberty, in female Boer goat kids can be manipulated through management techniques such as permanent exposure to the ram, good nutrition and strategic weaning and breeding
Sensitivity analysis and related analysis: A survey of statistical techniques
No full textThis paper reviews the state of the art in five related types of analysis, namely (i) sensitivity or what-if analysis, (ii) uncertainty or risk analysis, (iii) screening, (iv) validation, and (v) optimization. The main question is: when should which type of analysis be applied; which statistical techniques may then be used? This paper distinguishes the following five stages in the analysis of a simulation model. 1) Validation: the availability of data on the real system determines which type of statistical technique to use for validation. 2) Screening: in the simulation's pilot phase the really important inputs can be identified through a novel technique, called sequential bifurcation, which uses aggregation and sequential experimentation. 3) Sensitivity analysis: the really important inputs should be This approach with its five stages implies that sensitivity analysis should precede uncertainty analysis. This paper briefly discusses several case studies for each phase.Experimental Design;Statistical Methods;Regression Analysis;Risk Analysis;Least Squares;Sensitivity Analysis;Optimization;Perturbation;statistics
Synchronization of oestrus in sheep: The use of controlled internal drug release (CIDR) dispensers
No full textNo Abstrac
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