Two-scale computational modelling of unsaturated flow in soils exhibiting small scale heterogeneities

Unsaturated water flow in soil is commonly modelled using Richards’ equation, which requires the hydraulic properties of the soil (e.g., porosity, hydraulic conductivity, etc.) to be characterised. Naturally occurring soils, however, are heterogeneous in nature, that is, they are composed of a number of interwoven homogeneous soils each with their own set of hydraulic properties. When the length scale of these soil heterogeneities is small, numerical solution of Richards’ equation is computationally impractical due to the immense effort and refinement required to mesh the actual heterogeneous geometry. A classic way forward is to use a macroscopic model, where the heterogeneous medium is replaced with a fictitious homogeneous medium, which attempts to give the average flow behaviour at the macroscopic scale (i.e., at a scale much larger than the scale of the heterogeneities). Using the homogenisation theory, a macroscopic equation can be derived that takes the form of Richards’ equation with effective parameters. A disadvantage of the macroscopic approach, however, is that it fails in cases when the assumption of local equilibrium does not hold. This limitation has seen the introduction of two-scale models that include at each point in the macroscopic domain an additional flow equation at the scale of the heterogeneities (microscopic scale). This report outlines a well-known two-scale model and contributes to the literature a number of important advances in its numerical implementation. These include the use of an unstructured control volume finite element method and image-based meshing techniques, that allow for irregular micro-scale geometries to be treated, and the use of an exponential time integration scheme that permits both scales to be resolved simultaneously in a completely coupled manner. Numerical comparisons against a classical macroscopic model confirm that only the two-scale model correctly captures the important features of the flow for a range of parameter values.

‘Doing’ social justice in early childhood : the potential of leadership

Early childhood education has long been connected with objectives related to social justice. Australian Early Childhood Education and Care (ECEC) has its roots in philanthropic and educational reform movements prevalent at the turn of the 20th century. More recently, with the introduction of the National Early Childhood Reform Agenda, early childhood education has once more been linked to the achievement of aims associated with redressing inequality and disadvantage. According to Jean-Marie, Normore and Brooks (2009), educational leaders have a moral and social obligation to foster equitable practices through advocating for traditionally marginalised and poorly served students while creating a new social order “...that subverts the long standing system that has privileged certain students while oppressing or neglecting others” (p.4). Drawing on extant literature, including data from two previously reported Australian studies in which leadership emerged as having a transformational impact on service delivery, this paper examines the potential of early childhood leadership to generate ‘socially just’ educational communities. With reference to critical theory, we argue that critically informed, intentional and strategic organisational leadership can play a pivotal role in creating changed circumstances and opportunities for children and families. Such leadership includes positional and distributed elements, articulation of values and beliefs, and collective action that is mindful and informed.

Variation in risk seeking behaviour following large losses : a natural experiment

This study explores people's risk taking behaviour after having suffered large real-world losses following a natural disaster. Using the margins of the 2011 Australian floods (Brisbane) as a natural experimental setting, we find that homeowners who were victims of the floods and face large losses in property values are 50% more likely to opt for a risky gamble -- a scratch card giving a small chance of a large gain ($500,000) -- than for a sure amount of comparable value ($10). This finding is consistent with prospect theory predictions regarding the adoption of a risk-seeking attitude after a loss.

Applying threshold learning theory to teach sustainable business practice in post-graduate engineering education

This paper presents the results of a qualitative action-research inquiry into how a highly diverse cohort of post-graduate students could develop significant capacity in sustainable development within a single unit (course), in this case a compulsory component of four built environment masters programs. The method comprised applying threshold learning theory within the technical discipline of sustainable development, to transform student understanding of sustainable business practice in the built environment. This involved identifying a number of key threshold concepts, which once learned would provide a pathway to having a transformational learning experience. Curriculum was then revised, to focus on stepping through these targeted concepts using a scaffolded, problem-based-learning approach. Challenges included a large class size of 120 students, a majority of international students, and a wide span of disciplinary backgrounds across the spectrum of built environment professionals. Five ‘key’ threshold learning concepts were identified and the renewed curriculum was piloted in Semester 2 of 2011. The paper presents details of the study and findings from a mixed-method evaluation approach through the semester. The outcomes of this study will be used to inform further review of the course in 2012, including further consideration of the threshold concepts. In future, it is anticipated that this case study will inform a framework for rapidly embedding sustainability within curriculum.

Joint identification of infinite-frequency added mass and fluid-memory models of marine structures

This paper addresses the problem of joint identification of infinite-frequency added mass and fluid memory models of marine structures from finite frequency data. This problem is relevant for cases where the code used to compute the hydrodynamic coefficients of the marine structure does not give the infinite-frequency added mass. This case is typical of codes based on 2D-potential theory since most 3D-potential-theory codes solve the boundary value associated with the infinite frequency. The method proposed in this paper presents a simpler alternative approach to other methods previously presented in the literature. The advantage of the proposed method is that the same identification procedure can be used to identify the fluid-memory models with or without having access to the infinite-frequency added mass coefficient. Therefore, it provides an extension that puts the two identification problems into the same framework. The method also exploits the constraints related to relative degree and low-frequency asymptotic values of the hydrodynamic coefficients derived from the physics of the problem, which are used as prior information to refine the obtained models.

A derivation of high-frequency asymptotic values of 3D added mass and damping based on properties of the Cummins' equation

This brief paper provides a novel derivation of the known asymptotic values of three-dimensional (3D) added mass and damping of marine structures in waves. The derivation is based on the properties of the convolution terms in the Cummins's Equation as derived by Ogilvie. The new derivation is simple and no approximations or series expansions are made. The results follow directly from the relative degree and low-frequency asymptotic properties of the rational representation of the convolution terms in the frequency domain. As an application, the extrapolation of damping values at high frequencies for the computation of retardation functions is also discussed.

Control of an underactuated-slender-hull unmanned underwater vehicle using Port-Hamiltonian theory

This paper presents a control design for tracking of attitude and speed of an underactuated slender-hull unmanned underwater vehicle (UUV). The control design is based on Port-Hamiltonian theory. The target dynamics (desired dynamic response) is shaped with particular attention to the target mass matrix so that the influence of the unactuated dynamics on the controlled system is suppressed. This results in achievable dynamics independent of uncontrolled states. Throughout the design, insight of the physical phenomena involved is used to propose the desired target dynamics. The performance of the design is demonstrated through simulation with a high-fidelity model.

Justice in human research ethics : a conceptual and practical guide

One of the core values to be applied by a body reviewing the ethics of human research is justice. The inclusion of justice as a requirement in the ethical review of human research is relatively recent and its utility had been largely unexamined until debates arose about the conduct of international biomedical research in the late 1990s. The subsequent amendment of authoritative documents in ways that appeared to shift the meaning of conceptions of justice generated a deal of controversy. Another difficulty has been that both the theory and the substance of justice that are applied by researchers or reviewers can be frequently seen to be subjective. Both the concept of justice – whether distributive or commutative - and what counts as a just distribution or exchange – are given different weight and meanings by different people. In this paper, the origins and more recent debates about the requirement to consider justice as a criterion in the ethical review of human research are traced, relevant conceptions of justice are distinguished and the manner in which they can be applied meaningfully in the ethical review all human research is identified. The way that these concepts are articulated in, and the intent and function of, specific paragraphs of the National Statement on Ethical Conduct in Human Research (NHMRC, ARC, UA, 2007) (National Statement) is explained. The National Statement identifies a number of issues that should be considered when a human research ethics committee is reviewing the justice aspects of an application. It also provides guidance to researchers as to how they can show that there is a fair distribution of burdens and benefits in the participant experience and the research outcomes. It also provides practical guidance to researchers on how to think through issues of justice so that they can demonstrate that the design of their research projects meets this ethical requirement is also provided

Management of multiple heterogeneous UAVs using capability and autonomy visualisation: theory, experiment and result

The interest in utilising multiple heterogeneous Unmanned Aerial Vehicles (UAVs) in close proximity is growing rapidly. As such, many challenges are presented in the effective coordination and management of these UAVs; converting the current n-to-1 paradigm (n operators operating a single UAV) to the 1-to-n paradigm (one operator managing n UAVs). This paper introduces an Information Abstraction methodology used to produce the functional capability framework initially proposed by Chen et al. and its Level Of Detail (LOD) indexing scale. This framework was validated through comparing the operator workload and Situation Awareness (SA) of three experiment scenarios involving multiple autonomously heterogeneous UAVs. The first scenario was set in a high LOD configuration with highly abstracted UAV functional information; the second scenario was set in a mixed LOD configuration; and the final scenario was set in a low LOD configuration with maximal UAV functional information. Results show that there is a significant statistical decrease in operator workload when a UAV’s functional information is displayed at its physical form (low LOD - maximal information) when comparing to the mixed LOD configuration.

Theory based production and project management

This paper gives an overview of an ongoing project endeavouring to advance theory-based production and project management, and the rationale for this approach is briefly justified. The status of the theoretical foundation of production management, project management and allied disciplines is discussed, with emphasis on metaphysical grounding of theories, as well as the nature of the heuristic solution method commonly used in these disciplines. Then, on-going work related to different aspects of production and project management is reviewed from both theoretical and practical orientation. Next, information systems agile project management is explored with a view to its re-use in generic project management. In production management, the consequences and implementation of a new, wider theoretical basis are analyzed. The theoretical implications and negative symptoms of the peculiarities of the construction industry for supply chains and supply chain management in construction are observed. Theoretical paths for improvements of inter-organisational relationships in construction which are fundamental for improvement of construction supply chains are described. To conclude, the observations made in this paper vis-à-vis production, project and supply chain management are related again to the theoretical basis of this paper, and finally directions for theory development and future research are given and discussed.

Out of their minds: legal theory in neural networks

This paper examines the use of connectionism (neural networks) in modelling legal reasoning. I discuss how the implementations of neural networks have failed to account for legal theoretical perspectives on adjudication. I criticise the use of neural networks in law, not because connectionism is inherently unsuitable in law, but rather because it has been done so poorly to date. The paper reviews a number of legal theories which provide a grounding for the use of neural networks in law. It then examines some implementations undertaken in law and criticises their legal theoretical naïvete. It then presents a lessons from the implementations which researchers must bear in mind if they wish to build neural networks which are justified by legal theories.

Using communicative ecology theory to scope the emerging role of social media in the evolution of urban food systems

Urban agriculture plays an increasingly vital role in supplying food to urban populations. Changes in Information and Communications Technology (ICT) are already driving widespread change in diverse food-related industries such as retail, hospitality and marketing. It is reasonable to suspect that the fields of ubiquitous technology, urban informatics and social media equally have a lot to offer the evolution of core urban food systems. We use communicative ecology theory to describe emerging innovations in urban food systems according to their technical, discursive and social components. We conclude that social media in particular accentuate fundamental social interconnections normally effaced by conventional industrialised approaches to food production and consumption.

Artefact ecologies : supporting embodied meeting practices with distance access

Frameworks such as activity theory, distributed cognition and structuration theory, amongst others, have shown that detailed study of contextual settings where users work (or live) can help the design of interactive systems. However, these frameworks do not adequately focus on accounting for the materiality (and embodiment) of the contextual settings. Within the IST-EU funded AMIDA project (Augmented Multiparty Interaction with Distance Access) we are looking into supporting meeting practices with distance access. Meetings are inherently embodied in everyday work life and that material artefacts associated with meeting practices play a critical role in their formation. Our eventual goal is to develop a deeper understanding of the dynamic and embodied nature of meeting practices and designing technologies to support these. In this paper we introduce the notion of "artefact ecologies" as a conceptual base for understanding embodied meeting practices with distance access. Artefact ecologies refer to a system consisting of different digital and physical artefacts, people, their work practices and values and lays emphasis on the role artefacts play in embodiment, work coordination and supporting remote awareness. In the end we layout our plans for designing technologies for supporting embodied meeting practices within the AMIDA project.