Thermal stability in a stockpile of reactive materials is analyzed in this article. The combustion process is modelled in a long cylindrical pipe that is assumed to lose heat to the surrounding environment by convection and radiation. The study of effects of different kinetic parameters embedded on the governing differential equation, makes it easier to investigate the complicated combustion process. The combustion process results with nonlinear molecular interactions and as a result it is not easy to solve the differential equation exactly, and therefore the numerical approach by using the Finite Difference Method (FDM) is applied. The numerical solutions are depicted graphically for each parameter’s effect on the temperature of the system. In general, the results indicate that kinetic parameters like the reaction rate promote the exothermic chemical reaction process by increasing the temperature profiles, whilst kinetic parameters such as the order of the reaction show the tendency to retard the combustion process by lowering the temperature of the system.
Examinations are used to promote students. Promotions are in terms of moving to higher-level studies or graduations. Students who failed the main examinations were given a second chance. At this South African University of Technology (UoT), two types of second chance were given. From the beginning of the institution to 2009, the second chance examination used was called Supplementary Examination. Supplementary Examination (SE) was the examination written by students who obtained 45% to 49% in their main examination. From 2010 onwards, the institution decided to replace the SE with unconditional rewrite examination (URE). The UREera students were granted unrestricted permission to write a second examination, even if they got zero in the main examination. The rationale was that their performance would improve. In this investigation, the main - examination marks of SE-era students were compared with those of URE-era students. What prompted the study was the question: “How does provision of second chance impact on the student’s preparation of the main examination”? Does the stricter second chance conditions impact positively or negatively on the student’s preparation for the main examination? The research design was quantitative. The sample used was the main examination results of 2009, the last SE year, and those of 2011, the URE second year. Data analysis indicated that the means (averages) of SE-era students were generally higher than those of URE-era students. With all things being the same, the conclusion is that if students know that they have an unrestricted chance to rewrite, they prepare less for the main examination.
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