Abstracts of Paper's Published in 2020

In the following:

  1. Mark Ian Nelson and Bronwyn H. Bradshaw-Hajek. An analysis of organic carbon removal in a two-reactor cascade with recycle and a two-reactor step-feed cascade with recycle. Asia-Pacific Journal of Chemical Engineering, 15(1), 2020. DOI: 10.1002/apj.2392.
  2. M. Berryp, M.I. Nelson, B. Monaghan and B. Whale. The effects of oscillating boundary conditions on thermal ignition. In Christopher C. Tisdell, Zlatko Jovanoski, William Guo, Judith Bunder editors, Proceedings of the 14th Biennial Engineering Mathematics and Applications Conference, EMAC-2019, volume 61 of ANZIAM J., pages C45--C48, 2020. https://doi.org/10.21914/anziamj.v61i0.15035 .

An analysis of organic carbon removal in a two-reactor cascade with recycle and a two-reactor step-feed cascade with recycle

Abstract

We analyse the steady-state operation of two process configurations that employ a reactor cascade with recycle. The first process configuration is a two-reactor cascade in which the feed stream enters into the first reactor. The second process configuration is a two-reactor step-feed cascade in which the feed stream enters the second reactor. In each process configuration, part of the effluent stream is recycled back into the first reactor. The reactors in the cascade need not be of equal volume. The reaction is assumed to be a biological process governed by Monod growth kinetics with a decay coefficient for the microorganisms. The stability of the washout solution is determined analytically for both process configurations. It follows from the stability analysis that that there is a range of residence times over which the effluent concentration leaving a step-reactor cascade is lower than that leaving a standard reactor cascade. Steady-state diagrams are presented showing the effluent concentration as a function of the residence time. We find that if the desired effluent concentration is not too low, then the process configuration that minimises the residence time is the step-feed reactor cascade. However, for much cleaner waste streams, the process configuration that minimises the residence time is the standard reactor cascade.

Keywords: activated sludge, multistage continuous culture, staging, step-feed reactor, wastewater, water treatment .

Mark Ian Nelson and Bronwyn H. Bradshaw-Hajek. An analysis of organic carbon removal in a two-reactor cascade with recycle and a two-reactor step-feed cascade with recycle. Asia-Pacific Journal of Chemical Engineering, 15(1), 11 pages, 2020. DOI: 10.1002/apj.2392.

The effects of oscillating boundary conditions on thermal ignition

Abstract

We investigate the effect that oscillating ambient temperatures have on the ignition times of supercritical stockpiles. Large stockpiles are exposed to seasonal and diurnal temperature variation. We analyse the effects of seasonal temperature variation. When considering ignition within a year of construction, stockpiles built in spring ignited with a lower critical parameter than those built at other times. Consequently, seasonal temperature variation needs to be accounted for when predicting stockpile ignition times.

Keywords: Ambient Tempertature Oscillation, Thermal Ignition. .

M. Berryp, M.I. Nelson, B. Monaghan and B. Whale. The effects of oscillating boundary conditions on thermal ignition. In Christopher C. Tisdell, Zlatko Jovanoski, William Guo, Judith Bunder editors, Proceedings of the 14th Biennial Engineering Mathematics and Applications Conference, EMAC-2019, volume 61 of ANZIAM J., pages C45--C48, 2020. https://doi.org/10.21914/anziamj.v61i0.15035 .

A model fix gone wrong: investigation of an SIS model with saturating treatment

Abstract

A textbook model of a contagious disease, the dynamics of which are represented by the SIS epidemic model with saturating treatment, is considered. I show that this model, as originally formulated, is not dimensionally consistent. The model can be fixed by including a dimensional constant a of value one (with units individuals-1). At first sight, it appears that this is a cosmetic book-keeping exercise that will have no flow-on effects on the analysis of the model. In fact, we will discover that setting the value a=1 individuals-1 produces very unrealistic outcomes and that the parameter must have value a << 1 individuals-1. Necessary skills for students to work through this model are an understanding of steady-state solutions and linearised stability for a scalar differential equation and, most importantly, an understanding of units.

Keywords: Modelling, SIS, steady-state solutions, units.

Mark Ian Nelson. A model fix gone wrong: investigation of an SIS model with saturating treatment. International Journal of Mathematical Education in Science and Technology, ??, pages 1-11, 2020. https://doi.org/10.1080/0020739X.2020.1745916.

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Page Created: 11th February 2020.
Last Updated: 11th October 2020.