Abbas El-Zein

Associate Professor of Environmental Engineering

My research falls in the area of applied mathematics and environmental science and engineering. It covers both theoretical and applied topics using deterministic, stochastic and statistical approaches, with focus on computational and environmental geomechanics, as well as environmental risk. I am currently working on the mathematical modelling of problems of seepage and contaminant migration in soil and groundwater, sequestration of carbon dioxide in geologic formations to mitigate climate change and waste management decision-making under conditions of uncertainty. The goal of research of this nature is to develop better theories that account for the behaviour of the lithosphere under environmental stress as well as a better understanding of human-environment interactions and, consequently, better environmental policy-making. One spinoff of my research is the finite-element computational software in 2D and 3D that is used to simulate problems of water, heat and chemical transport in the environment. In addition, I have an active interest in educational research, specifically teaching computing and environmental sustainability to science and engineering students. My own teaching covers environmental, geo-mechanical and computational topics.

On Motion, Carbon and Mathematical Modelling (or How to Approach your Local Grocer)

Background

Research

Recent Scientific Publications

Contact Details: Abbas El-Zein, Civil Engineering, Building J05, University of Sydney, NSW 2006, Australia. Phone: 61-2-9351 7351, Fax: 61-2-9351 3343, Email: aelzein@usyd.edu.au.

On Motion, Carbon and Mathematical Modelling (or How to Approach your Local Grocer)

Mathematical modelling has become a crucial part of technological development and scientific research

in the last fifty years or so. Mathematical models allow us to simulate and predict the behaviour of engineered

or natural systems, sometimes to very high accuracy: the flow of water in the soil, the movement of pollutants

in the ground surface or the atmosphere, the cycle of carbon in forest soils, the build up of heat in a car engine,

the propagation of a fracture in a metallic plate under stress and so on. In my own research, I have

worked on all of these problems using remarkably similar numerical approaches, despite the vast differences in the

nature of these systems. While the problems are different, mathematics offer a unified and potent way of

approaching them!

Mathematical models are reductionist of course. In other words, they only represent one or more aspects of the system

in question and often leave out other aspects. There is nothing wrong with this per se. Our minds operate in a

reductionist way. When did you ever consider ALL aspects of your local grocer when buying your fruits and vegetables?

Most of the times, you have to think of her as "Your Grocer" even though you know there is much more to her than this.

If you do not "reduce" her in your mind in this way, you would find it very hard, if not impossible, to cope with reality.

The challenge for mathematical modelling is to capture all aspects of a system that are relevant to the outcome in

question. If you are trying to predict whether your saxophone might wake up your neighbours, chances are the

clothes you are wearing while you play your instrument are not relevant to the outcome. Where in the house you

perform, on the other hand, is not something you can leave out of your equations! (Acoustic waves equations,

by the way, are similar to the ones that describe some of the problems listed above!).

The mathematical models are quite complex and can run into tens of thousands of lines in a computer code.

Nevertheless, to find that the mathematical equations that you have derived and turned into a computer algorithm

can actually predict the behaviour of the real world is one of the many pleasures of research and applied mathematics!

Background

BE in Civil Engineering, 1986, American University of Beirut, Lebanon.
MSc in Structural Engineering (with distinction), 1987, University of Southampton, UK.
MSc in Environmental Science and Technology (DEA), 1993, Ecole Nationale des Ponts et Chaussees, Universite Paris XII, Ecole Nationale du Genie Rural des Eaux et des Forets, Paris, France.
PhD in Computational Mechanics, 1990, University of Southampton, UK.

Research: Current Research Projects

1. New Forms of Adaptivity in Subsurface Transport Problems. Soil layering is frequently encountered in natural environments, as well as subsurface engineering structures. Road pavements, water treatment systems, landfill liners, vertical low-permeability barriers such as cut-off walls and waste repositories are examples of engineering design solutions which use a complex array of soil layers to achieve specific structural or environmental outcomes. Finite-element modeling of flow and solute transport through such media often suffers from solution instability and/or high computational cost, which can become prohibitive in 2D and 3D. This is because the existence of different spatial scales translates into over-refined meshes or abrupt changes in element sizes, at and around the thin layers. The project develops a new, general-purpose finite element types for the Poisson equation and the reactive diffusion-advection equation, representing seepage and mass transport problems, respectively. The new elements remove the need for explicit representation and meshing of any thin layer and simulates it instead as an interface discontinuity of the unknown potential (total hydraulic head in seepage analysis or solute concentration in mass transport problems). This research is currently extended to develop a new type of non iso-dimensional finite-element adaptivity.

2. Leakage through Geomembranes in GCL and CCL Liners. Geomembranes are effective barriers to contaminant migration in soils. However, leakage through defects in the geomembranes and diffusion of organic compounds through its intact parts reduces its insulating capacity. While regulators and practitioners have attempted to keep a lid on the rate of water leakage through these defects, little is known about the impact of defects on groundwater quality and their implications for liner designs. The project develops innovative finite-element techniques for more advanced modelling of the multi-layered and highly heterogeneous nature of the liner and surrounding soils in order a. to assess the impact of leakage on groundwater and the viability of simple 1D models of contamination in the presence of leakage and b. to develop liner designs which offset a priori the effects of leakage. A by-product of this work is the development of an interactive simulation system (SPAS) for the analysis of liner systems in 2D; see item 5 below (collaborators: Prof. R Kerry Rowe, Queen's University, Canada; Dr Nathalie Touze-Foltz, CEMAGREF, France; PhD Student: Farzad Meysami Azad).

3. Stochastic Multi-Criteria Environmental Decision-Making: Developing environmental solutions (e.g., waste management, water usage, transport), at local, regional and national levels, can be a complex exercise, owing to conflicting environmental, social and economic criteria incorporated in the decision-making process. Furthermore, various sources of uncertainty are inherent to the exercise, such as uncertain waste generation data, future projections, subjective assessments of criteria weights and decision thresholds in outranking procedures. This multiple uncertainty adds a new layer of difficulty and calls into question the validity of decision-making outcomes. The project integrates a life-cycle analysis system with a multi-criteria outranking procedure and a new approach to the quantification of social criteria, all within a stochastic framework which takes into account various sources of uncertainty. It will allow decision-makers to reach more robust decisions and develop a better understanding of its limits of validity and can have implications for, in addition to the waste-management sector, other environmental disciplines such as water management (PhD Student: Ali El-Hanandeh).

4. Teaching Computing to Science and Engineering Students: Although science and engineering students enjoy a relatively high degree of numeracy, learning how to use computing environments (e.g., Matlab, MS Excel) and computer languages (e.g., FORTRAN, Matlab, Python) is a difficult task for a large number of students. The projects consist of designing, developing and evaluating various flexible tools for aiding in the teaching of computing in order to improve the learning ability of students. This is an empirical research area which builds upon emerging IT technology to transform the tertiary learning experience. The tools in question are:

a) The Self-Practice Online Tool (SPOT) for the blended teaching of Matlab programming has been in use since 2006 (Faculty of Engineering Funding: $20,000; joint Civil and Chemical Engineering Project; project leader: Abbas El-Zein).

b) EXcel Interactive Tool (EXIT) for self-directed learning and teaching of MS Excel to science and engineering students is under development due to be released in early 2010 (joint project between the faculties of Engineering and Science; University of Sydney TIES funding: circa $114,000; project leader: Abbas El-Zein; developer: Peter Cafe)

c) for self-directed learning of computer programming (joint School of IT, Chemical and Civil Engineering Project; University TIES funding: circa $113,000; project leader: James Curran from the school of IT).

Research Application: Development of Soil Pollution Analysis System SPAS. SPAS is a computer software, based on the finite-element engine CONFEM, which solves various problems of water seepage and chemical contamination in soil. It includes such features as global mass-conserving boundary conditions, automatic generation of detailed liner features and multiple-porosity mass transport. CONFEM is the outcome of eight years of contamination research by Abbas. In 2008, an advanced, user-friendly graphic interface has been developed by Dr Nigel Balaam for CONFEM. This interface, together with CONFEM, constitute a complete computer simulation tool known as SPAS. A new 3D version of CONFEM has been recently completed (collaborators: Dr Nigel Balaam).

Recent Scientific Publications

Abbas El-Zein. 2009. A non-isodimensional finite-element approach to the modeling of transient flow and mass transport through domains with thin layers. Computers and Structures (special journal issue for 5^th MIT Conference on Computational Fluid and Solid Mechanics, Advances in CFD), in press.

Ali El Hanandeh and Abbas El-Zein. 2009. Strategies for the municipal waste management system to take advantage of carbon trading under competing policies: the role of energy from waste in Sydney. Waste Management, in press.

Abbas El-Zein, Tim Langrish and Nigel Balaam. 2009. Blended teaching and learning of computer programming skills in engineering curricula. Advances in Engineering Education, in press.

Abbas El-Zein and R. Kerry Rowe. 2008. Impact on groundwater of concurrent leakage and diffusion of dichloromethane through geomembranes in landfill liners. Geosynthetics International, 15(1):55-71.

Abbas El-Zein. 2008. A generalized approach to the modelling of contaminant transport through intact and leaking geomembranes. International Journal for Numerical and Analytical Methods in Geomechanics, 32(3):265-287.

Abbas El-Zein, David Airey, Peter Bowden, Henriikka Clarkeburn. 2008. Sustainability and ethics as decision-making paradigms in engineering curricula. International Journal for Sustainability in Higher Education, 9(2):170-182.

Abbas El-Zein and Nigel Balaam. 2008. SPAS: A New Finite-Element tool for modelling transport through damaged landfill liners, with advanced mass-conserving boundary conditions 4^th European Conference on Geosynthetics, Edinburgh, September 2008, paper number 280.

Abbas El-Zein and R. Kerry Rowe. 2008. Parametric study of the effect on groundwater quality of leakage of benzene and toluene through composite liners. 4^th European Conference on Geosynthetics, Edinburgh, September 2008, paper number 231.

Ali El-Hanandeh and Abbas El-Zein. 2008. The viability of using film plastics in Sydney municipal solid waste as a source of energy. International Conference on Environmental Research and Technology (ICERT 08).

Ali El-Hanandeh and Abbas El-Zein. 2008. Waste to Energy: The Sydney Case. First International Conference of Institution of Engineering and Technology (IET) Brunei Darussalam Network, 26-27 May 2008.

Abbas El-Zein, Iman Nuwayhid, Mutassem Fadel, Salman Mroueh. 2007. Did a ban on diesel-fuel reduce emergency respiratory admissions for children? Science of the Total Environment,384:134-140.

Abbas El-Zein and R. Kerry Rowe. 2007. Simultaneous leakage and diffusion of organic pollutants through damaged geomembranes. Numerical Model in Geomechanics, edited by Pande and Pietruszczak, Taylor and Francis Publishers, Proceedings of the 10^th International Symposium on Numerical Models in Geomechanics NUMOG X, Rhodes, Greece, 25-27 April 2007, 297-301.

Ali El-Hanandeh and Abbas El-Zein. 2007. A new stochastic multi-criteria decision analysis tool based on ELECTRE III method. Australia New Zealand Conference on Ecological Economics, 2007, Brisbane, Australia, July 2007 (awarded prize for best PhD paper).

Abbas El-Zein, Timothy Langrish, Nigel Balaam. 2007. A self-practice online tool for teaching and learning computational skills in engineering curricula. International Conference on Engineering Education (INEER), Portugal, September 2007, in press.

Abbas El-Zein, David Airey, Peter Bowden, Henriikka Clarkeburn. 2007. Teaching sustainability and ethics in engineering degrees. International Conference on Engineering Education (INEER), Portugal, September 2007, in press.

Abbas El-Zein. 2006. Steady-state diffusion-advection by exponential finite elements. International Journal of Geomechanics ASCE, 6(6):428-434.

Samer Jabbour, Abbas El-Zein, Iman Nuwayhid, Rita Giacaman. 2006. Can actions for better health be a vehicle for social and political reform? British Medical Journal, 333:837-839.

Hala Tamim, Ghassan Akkari, Abbas El-Zein, Rana El Roueiheb, Zena El Shemaly. 2006. Exposure of school children to environmental cigarette and narghile smoke in Beirut. European Journal of Public Health, 16:509-512.

Abbas El-Zein, Rola Nasrallah, Iman Nuwayhid, Lea Kai, Jihad Makhoul. 2006. Why do neighbours have different environmental priorities? An analysis of environmental risk perception in a Beirut neighbourhood. Risk Analysis, 26(2):423-436.

Abbas El-Zein, John P. Carter and David W. Airey. 2006. Three-dimensional finite element method for the analysis of soil contamination. International Journal for Numerical and Analytical Methods in Geomechanics, 30(7), 577-597.

Abbas El-Zein. 2006. A Laplace boundary-element model of thermo-elastic consolidation of multi-layered media. Technical note. International Journal of Geomechanics ASCE, 6(2):136-140.

Abbas El-Zein, Rola Nasrallah, Iman Nuwayhid. 2006. Determinants of the willingness-to-participate in an environmental intervention. Environmental Management, 37(2):200-208.

Abbas El-Zein. 2006. A mass-conservation boundary condition for the modeling of contaminant transport through leaking geo-membranes. Proceedings of the ISSMGE's 5^th International Conference on Environmental Geotechnics, Edited by HR Thomas, Cardiff, Wales, June 2006, Volume 2, 1131-1137.

Peter Bowden, David W. Airey and Abbas El-Zein. 2006. Underpinning a discipline-specific ethics course. Thirteenth Annual Australian Association for Professional and Applied Ethics Conference, June 12-14, Sydney.

Abbas El-Zein. 2005. Exponential finite elements for diffusion-advection problems. International Journal for Numerical Methods in Engineering, 62(15):2086-2103.

Abbas El-Zein, John Carter and David Airey. 2005. Multiple-porosity contaminant migration by finite-elements. International Journal of Geomechanics ASCE, 5(1):24-36.

Abbas El-Zein, Mylene Tewtel-Salem. 2005. On the association between high temperature and mortality in warm climates. Letter to the Editor. Science of the Total Environment, 343(1-3):273-275.

Abbas El-Zein, Mylene Tewtel-Salem and Gebran Nehme. 2004. A time-series analysis of daily mortality and air temperature in Greater Beirut. Science of the Total Environment, 330(1-3):71-80.