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Since 2004, the Australian Learning and Teaching Council (ALTC) and its predecessor, the Carrick Institute for Learning and Teaching in Higher Education, have funded numerous teaching and educational research-based projects in the Mathematical Sciences. In light of the Commonwealth Government's decision to close the ALTC in 2011, it is appropriate to take account of the ALTCs input into the Mathematical Sciences in higher education. We overview altc projects in the Mathematical Sciences, as well as report on the contributions they made to the discipline.
Keywords learning; teaching; education; ALTC
D. Mallet, M.I. Nelson, A. Porter, A. Dekkers, M. Townley-Jones, I. Hudson, S. Belward, C. Coady, and D. King. Australian learning and teaching council projects in the mathematical sciences: A retrospective. In M. Nelson, M. Coupland, H. Sidhu, T. Hamilton and A.J. Roberts, editors, Proceedings of the 10th Biennial Engineering Mathematics and Applications Conference, EMAC 2011, ANZIAM J, 53, pages C576-C591, 2013. Download the paper from http://journal.austms.org.au/ojs/index.php/ANZIAMJ/article/view/5150 .
Prior to discharge into rivers municipal and industrial waste waters may be treated in a reactor cascade that employs a settling unit to recycle biomass from the final cascade reactor to the first. In this paper we use steady-state analyse to examine the process efficiency of such a reactor configuration. The Contois specific growth rate model is used to describe biomass growth.
It is found that there is a critical value of the total residence time which identifies a turning point in the performance of the reactor cascade. In particular, if the total residence time is below the critical value then the settling unit improves the performance of an n-reactor cascade (n = 2, 3, 4 & 5), whereas, if the residence time is above the critical value then the performance of an n-reactor cascade (n = 2, 3, 4, & 5) with the settling unit is inferior to that of a cascade without one. It is shown that the critical values of residence time depends upon the values of the recycle ratio R and the concentration factor C.
We compare the performance of a reactor configuration employing recycle around the whole cascade with that of a cascade in which the settling unit recycles the effluent stream leaving the ith reactor into the feed stream for the ith reactor.
Keywords: Bioreactor; Chemostat; Contois growth kinetics; Nonlinear dynamics; Recycle.
R.T. Alqahtani p, M.I. Nelson and A. Worthy. A fundamental analysis of continuous flow bioreactor models governed by Contois kinetics. IV. Recycle around the whole reactor cascade. Chemical Engineering Journal, 218, 99-107, 2013.
We analyse the steady-state operation of a continuous flow bioreactor in which the biochemical reaction is governed by noncompetitive substrate inhibition (Andrews kinetics). A generalised reactor model is used in which the well-stirred bioreactor and the idealised membrane bioreactor are special cases. As generic properties of systems subject to substrate inhibition have been obtained by earlier authors we discuss reaction engineering features specific to Andrews kinetics.
M.I. Nelson, T. Nicholls u and N. Hamzah. A biological process subject to noncompetitive substrate inhibition in a generalized flow reactor. The ANZIAM Journal, 54(4):273--290, 2013. http://dx.doi.org/10.1017/S1446181113000126. Trackable link: https://goo.gl/J9owaL.
One drawback associated with the activated sludge process is the production of `sludge'. The expense for treating excess sludge can account for 50-60% of the running costs of a plant. Traditional methods for disposing of excess sludge, which include incineration, the use of landfill sites and dumping at sea are becoming increasingly regulated due to concerns about the presence of potentially toxic elements in it. Furthermore, a combination of the limited amount of land available for landfill, particularly in urban areas, with stringent legislation has seen the economic costs of using landfill sites increasingly sharply. Thus there is a growing interest in methods that reduce the volume and mass of excess sludge produced as part of biological wastewater treatment processes.
We investigate a simple model for the activated sludge process in which the influent contains a mixture of soluble and biodegradable particulate substrate. Within the bioreactor the biodegradable particulate substrate is hydrolyzed to form soluble substrate. The soluble organics are used for energy and growth by the biomass. We investigate how the amount of sludge formed depends upon both the residence time and the use of a settling unit.
A.O.M. Alharbi p, M.I. Nelson, A.L. Worthy, and H.S. Sidhu. Sludge formation in the activated sludge process: Mathematical analysis. In Proceedings of the Australasian Chemical Engineering Conference, CHEMECA 2013, ( http://www.conference.net.au/chemeca2013/index.php) pages 1--7. Chemical College, Engineers Australia, 2013. Download the paper from http://www.conference.net.au/chemeca2013/papers/29490.pdf. CDROM. ISBN 978 1 922107 07 7.
A uniformly distributed mathematical model (based on Semenov's theory of thermal explosions) is formulated to model the thermal behaviour of cellulosic materials in compost piles. The model consists of a mass balance equation for oxygen, a heat balance equation and incorporates the heat release due to biological activity within the pile. Singularity theory and degenerate Hopf bifurcation theory are used to investigate the generic properties of the model as well as to determine the loci of different singularities: the isola, cusp, double-limit points, boundary limit set, double-Hopf bifurcation, generalised Hopf (Bautin) bifurcation and Bogdanov-Takens bifurcation. These loci divide the secondary parameter plane into different regions of solution behaviours. Conditions under which biological activity can result in the initiation of an elevated-temperature branch within the compost pile which does not pose the risk of spontaneous ignition are identified. These are the ideal conditions for composting. The regions of parameter space when spontaneous ignition is likely are also determined.
T. Luangwilai p, H.S. Sidhu and M.I. Nelson. Biological self-heating in compost piles: A Semenov formulation. Chemical Engineering Science, 101:533--542, 2013.
Spray drying is the primary process for the formation of dairy powders. In multistage drying operations, the post-spray-drying stage - for example, a fluidized bed drying stage - may not alter much of the surface composition formed earlier due to the extremely high surface viscosity. Spray drying of high-sugar-content product without a retardant on the surface to prevent sticky powder deposition in drying chamber may produce very low yields due to drying chamber wall deposition or cyclone deposition. The powder products are not flow able. A functional spray-dried product begins with its efficient incorporation into water; hence, surface composition plays a key role. This study is an attempt to explore the solid formation around the outermost layer of a single droplet of protein-sugar solution during the drying process using a continuum approach (diffusion-convection equations). The main feature of this model is that the multicomponent effect is lumped into the viscosity of the fluid at the surface, which inversely affects the diffusivities of individual components in the solution droplets or suspension droplets. The trend (and the order of magnitudes) of surface composition development of the caseinate/lactose system (from a 20/80 ratio down to 0.01/99.99) has been explored and the phenomeno has been explained with the aid of the continuum model, coupled with a simplified, geometrical, molecular-level interpretation. Based on the current study, we were able to make some useful conclusions.
X.D. Chenm, H. Sidhu, and M. Nelson. On the addition of protein (casein) to aqueous lactose as a drying aid in spray drying --- theoretical surface composition. Drying Technology, 31: 1504--1512, 2013 http://www.tandfonline.com/doi/full/10.1080/07373937.2013.780247 .
Self-heating/ignition is one of the well-known practical causes for fires and explosions in industry and in nature. The Transient Method (or Chen Method) is a cost-effective approach for determining the thermal ignition parameters of packed particulate or loose materials (activation energy E, the product of the heat of reaction and the pre-exponential constant QA). The crossing-point-temperature (CPT) method to establish the ignition kinetics was initiated by the first author in 1994. A finite difference solution obtained in 1998 showed that for Biot number approaching infinity the dimensionless CPT, θcpt (when the conduction term becomes zero at symmetry), is proportional to the Frank-Kamenetskii reactivity parameter δ, i.e. θcpt=0.1δ. In this study, this relationship has been re-confirmed firstly by new Matlab simulations, and secondly, derived analytically with the characteristic transport dimension concept and a new simple idea of a three-region approximation. The dimensionless thickness of the third region (next to the solid-gas boundary), defined as (1-β2)self-heat, is remarkably similar to that for the heat conduction (1-β2)cond=0.333 which leads to θcpt = 0.093δ. A small adjustment of (1-β2)self-heat to 0.339 leads to the exact relationship. This work shows a general applicability of the approximate linear relationship, making the method more useful
X.D. Chenm, H. Sidhu, and M. Nelson. A linear relationship between dimensionless crossing-point-temperature and Frank-Kamenetskii reactivity parameter in self-heating test at infinite Biot number for slab geometry. Fire Safety Journal, 61: 138--143, 2013.
This paper analyses a model for the production of bioethanol that has been calibrated against laboratory data by previous researchers. The authors investigate the improvement in productivity that can be obtained when a centrifuge is used to recycle cells that would otherwise leave the reactor system in the efficient stream. The authors compare the performance of a double reactor cascade, possible employing a settling unit, against that of a single reactor. For the former case, this paper considers the reactor configuration in which the settling unit recycles from the effluent stream of a reactor back in the influent of the same reactor.
M.I. Nelson and N. Hammzah. Performance evaluation of bioethanol production through continuous fermentation with a settling unit. Journal of Energy and Power Engineering, 7, 2083--2088, 2013.
Video capture technology allows video to be readily recorded and edited. The distribution of videos through e-learning systems provides learning support to students. This article discusses our experiences in developing video genre resources. The `overview' video resource is found to be a useful technique for conveying the structure of a topic. Video resources can be combined in a variety of ways using concept maps, learning design maps and/or folder based approaches. We provide our perspective regarding the production of video resources using tablet technology tools. The relative ease and flexibility of the technology is discussed. The aim of this article is to encourage lecturers to learn from our experiences, enabling them to develop their own resources.
B. Bukhatwa p, A.L. Porter, and M.I. Nelson. Video resources for supporting learning in mathematics rich disciplines: A teaching perspective. In Mark Nelson, Mary Coupland, Harvinder Sidhu, Tara Hamilton, and A.J. Roberts, editors, Proceedings of the 10th Biennial Engineering Mathematics and Applications Conference, EMAC-2011, volume 53 of ANZIAM J., pages C606--C620, July 2013. http://journal.austms.org.au/ojs/index.php/ANZIAMJ/article/view/5082 .