An analysis of the use of mass appraisal methods for agricultural properties

There are numerous factors that influence the price of a farm and some of these factors are not monetary related. This makes the task of the valuer complex and increases the possibility of large differences in the estimated market value determined and the actual selling price. This article reports the results of a study that analysed the unique and distinctive attributes of farms, in order to determine whether it is possible to develop a linear multiple regression model for the valuation of farms (which satisfies accuracy requirements) with reasonably available data. The improvement of accuracy levels of Multiple Regression Analysis (MRA) models as well as the limitations of using these MRA models during farm evaluations was also studied. By following a stepwise regression approach, 60 farms, primarily located in the eco-zone “mixed bushveld” western area of the Limpopo province, were analysed using ten independent variables. Three models have been developed. The results showed that a fairly accurate regression model could be developed. However, a model that achieves a high level of accuracy could not be developed, due to multifaceted reasons, including non-farm factors and the size of the geographical areas. Accurate MRA valuation estimates will be to the advantage of individual farm owners regarding their municipal tax assessments. It will lead to a wider use of MRAs for the valuation of farms, but great circumspect should be taken when using MRA models in farm valuations. This is due to the possibility that the MRA models do not satisfy minimum accuracy requirements. It is difficult, but possible, to develop a fairly accurate MRA model for the valuation of farms. Therefore, if currently used MRA models are not fairly accurate for municipal valuation purposes, it should be possible to improve the accuracy. Further research is recommended in the use of other regression techniques such as non-linear, geographic weighted regression and quantile regression. These other techniques would, however, require a larger data sample, in order to provide meaningful results

Powder Characterization for a New Selective Laser Sintering Polypropylene Material (Laser PP CP 60) after Single Print Cycle Degradation

ArticleExperiments were conducted to characterise a new polymeric powder (Laser PP CP 60) from Diamond Plastics GmbH used in selective laser sintering (SLS) additive manufacturing (AM). Three different batches of the powder were tested in the study; virgin powder, used powder, and a mixture (50% virgin: 50% used) powder. The three batches of powder were subjected to scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and melt flow index (MFI) testing. Scanning electron microscopy was used to determine the morphology of particles. The distribution of powder particle sizes was established by analysing the acquired SEM images using ImageJ software. Differential scanning calorimetry was used to determine the peak melting point, degree of crystallisation, and the sintering window of the powder. Thermogravimetric analysis was utilised to determine temperatures of degradation of the powder considered in the study. Lastly, MFI testing was used to determine the variation of flowability of the powder. It was found that the three batches of powder considered showed poor, but allowable morphology and particle size distribution. The sintering window of the virgin Laser PP CP 60 polypropylene powder increased after a single cycle of printing by 28%, from 21.04℃ (virgin powder) to 26.95℃ (used powder). The sintering window was lower than that for polyamide polymer, which might have contributed to the high shrinkage rates observed during processing of the material, as a narrow sintering window results in difficulties of regulating the cooling rate of the printed parts. The three batches of powder showed high degradation temperatures, which makes the material suitable for SLS processing. Finally, the three batches of powder showed low values of MFI, which indicates that the molten material has a high viscosity. This explains the difficulties experienced in processing the material

Do mathematics learning facilitators implement metacognitive strategies?

It is widely accepted that mathematical skills are critically important in our technologically sophisticated world. Educators' metacognition directs, plans, monitors, evaluates and reflects their instructional behaviour and this can promote learners' learning with understanding. The purpose of this study was to investigate the extent to which mathematics educators implemented and taught metacognitive strategies. Results of the quantitative part of the study were triangulated with the results of the qualitative part. Results suggested that whereas mathematics educators may well have possessed metacognitive skills and utilised them intuitively, these skills were not implemented to a satisfactory extent in the classes we observed

A Review of Methods Used to Reduce the Effects of High Temperature Associated with Polyamide 12 and Polypropylene Laser Sintering

The polymer laser sintering (PLS) process is one of the most promising additive manufacturing (AM) technologies for polymeric materials. However, the technique has challenges because the physical, mechanical, and chemical properties of the polymeric powder deteriorate due to the high temperatures prevailing in the build chamber during manufacture. These high temperatures cause agglomeration of powder, which leads to a decrease in the flowability of powder. There is also a related drop in the coalescence of the powder granules during PLS, which results in porosity that undermines the mechanical integrity of printed parts. Moreover, the viscosity of the melt increases due to cross-linking of molecular chains. This, in turn, increases the tensile strength of the printed components at the expense of the percentage elongation at break. Thus, high prolonged processing temperatures decrease the reusability of polymeric materials used in PLS. In this paper, a review of the studies conducted to investigate ways of reducing the effects of high temperature on polymeric powders is presented

An investigation regarding metacognition in the learning of mathematics in the senior phase

South African learners' insufficient achievement in mathematics is a source of great concern. This is especially the case since mathematics is regarded as a vital life skill in the postmodern, technologically sophisticated era. The concept "metacognition" is referred to both directly and indirectly in the Critical Outcomes in Curriculum 2005 - after all, most of the outcomes referred to imply that learners should be directed to reflect on their own thoughts. The primary aim of this study was to investigate the possible value of metacognition for the learning of mathematics. Both quantitative and qualitative research methods were implemented. The findings indicate, inter alia, that the metacognitive strategies with regard to prediction, evaluation, monitoring and reflection of learners in the research group are insufficient. AFRIKAANS:Suid-Afrikaanse leerders se ontoereikende wiskundeprestasie wek kommer. Dit is by uitstek die geval aangesien wiskunde in die postmoderne, tegnologies-gesofistikeerde era as 'n onontbeerlike lewensvaardigheid beskou word. Die konsep "metakognisie" is direk en indirek terug te vind in die Kritieke Uitkomste in Kurrikulum 2005 - die meeste van die bepaalde uitkomste impliseer immers dat leerders begelei behoort te word om oor hul eie denke na te dink. Die primêre doel van hierdie studie was om die stand van metakognisie in wiskundeleer te ondersoek. Sowel kwantitatiewe as kwalitatiewe navorsingsmetodes is gevolg. Daar is bevind dat die metakognitiewe strategieë rakende voorspelling, evaluering, monitering en refleksie van die leerders in die ondersoekgroep moontlik ontoereikend is

A mathematics vocabulary questionnaire for use in the intermediate phase

Teachers and psychologists need an instrument to assess learners’ language proficiency in mathematics to enable them to plan and evaluate interventions and to facilitate best practice in mathematics classrooms. We describe the development of a mathematics vocabulary questionnaire to measure learners’ language proficiency in mathematics in the intermediate phase. It covers all the steps from designing the preliminary questionnaire to standardising the final instrument. A sample of 1 103 Grades 4 to 7 Afrikaans-, English- and Tswana-speaking learners in North West Province completed the Mathematics Vocabulary questionnaire (Primary) (MV(P)), consisting of 12 items. We analysed the data by calculating discrimination values, performing a factor analysis, determining reliability coefficients, and investigating item bias by language, gender, and grade. We concluded that there was strong evidence of validity and reliability for the MV(P)