Field measurements and statistical analysis of perforated grating surfaces for grating fresh cassava into mash in Ghana

Processing of cassava into mash requires grating of fresh cassava tubers through the abrasive action of the grating surfaces of cassava graters that grind against the cassava and transforms it into mash. Over the years, improved cassava graters have been designed and made available on the market. In spite of improvements in design, there are no standards for the manufacture of grating surfaces and this affects interchangeability of the product. Mechanised grating of fresh cassava into mash contributes to reduce postharvest losses of cassava, increase its shelf life and improve food security. However, majority of the cassava grating surfaces are poorly made with substandard measurements that affect the desired particle size of mash for gari, a staple food for millions of people in West Africa. This study assessed cassava grating surfaces focusing on the abrasive elements (tooth diameter and inter-tooth spacing). Qualitative data were gathered from local metal fabricators and female gari processors in separate focus group discussions. The purpose was to gather the narratives underlying the issues being studied so as to complement and enrich the quantitative data. 112 tooth diameters and 112 inter-tooth spacing of perforated cassava grating surfaces were randomly measured in 16 different study areas in 3 regions of Ghana, namely Western, Central and Ashanti. Results from the qualitative data showed that grating of cassava was done repeatedly (about 2-3 times) before reaching the desired particle size of mash for gari. Most customers desire grating surfaces that ensure effective contact between the cassava and the metal grating surface to reduce grating time. Results from the field measurements showed high variation in existing tooth diameters (min=1.80, max=4.50 mm) and inter-tooth spacings (min=3.50, max=12.00 mm) that resulted in non-uniform particle size of cassava mash. Using statistical analysis, tooth diameters (min=3.18, max=3.42mm) and inter-tooth spacings (min=7.12, max=7.78mm) were determined at 95% confidence interval. For practical purposes, tooth diameter of 3 mm and inter-tooth spacing of 8 mm are recommended. The availability of such data will contribute significantly to standardise perforated cassava grating surfaces to achieve product interchangeability and desired quality of grated mash for gari. This will contribute to improve the manufacture of cassava graters and sustainable gari processing business in Ghana and Africa.Keywords: Fresh cassava, cassava grating surface, gari, food quality, Ghan

Comparison of binned and Gaussian Process based wind turbine power curves for condition monitoring purposes

Performance monitoring based on available SCADA data is a cost effective approach to wind turbine condition appraisal. A power curve of a wind turbine describes the relationship between power output and wind speed and is a key measure of wind turbine performance. The standard IEC method calculates a binned power curve from extensive measured data, however this approach requires an extended measurement period in order to limit the uncertainty associated with the calculated power curve, and is far too slow to be used directly for condition monitoring where any changes in operation need to be identified quickly. Hence an efficient approach needs to be developed to overcome this limitation and be able to detect anomalies quickly, thus detecting damage at an early stage so as to prevent catastrophic damage. A Gaussian Process (GP), which is a non-parametric machine learning approach, has the potential fit power curves quickly and effectively. This paper deals with the application of a Gaussian Process to power curve fitting and anomaly detection. This is compared with the conventional approach based on a binned power curve together with individual bin probability distributions to identify operational anomalies. The paper will outline the advantages and limitations of the Gaussian Process approach

A Diagrammatic Notation for Visualizing Epistemic Entities and Relations

This paper presents a diagrammatic notation for visualizing epistemic entities and relations. The notation was created during the Visualizing Worldviews project funded by the University of Toronto’s Jackman Humanities Institute and has been further developed by the scholars participating in the university’s Research Opportunity Program. Since any systematic diagrammatic notation should be based on a solid ontology of the respective domain, we first outline the current state of the scientonomic ontology. We then proceed to providing diagrammatic tools for visualizing the epistemic entities and relations of this ontology. These basic diagramming techniques allow us to construct diagrams of various types for both synchronic and diachronic visualizations. The paper concludes by highlighting some future research directions. As the notation presented here is de facto accepted and used in scientonomy, the paper suggests no modifications