Enhancement of transient stability limit and voltage regulation with dynamic loads using robust excitation control

In stressed power systems with large induction machine component, there exist undamped electromechanical modes and unstable montonic voltage modes. This article proposes a sequential design of an excitation controller and a power system stabiliser (PSS) to stabilise the system. The operating region, with induction machines in stressed power systems, is often not captured using a linearisation around an operating point, and to alleviate this situation a robust controller is designed which guaruntees stable operation in a large region of operation. A minimax linear quadratic Gaussian design is used for the design of the supplementary control to automatic voltage regulators, and a classical PSS structure is used to damp electromechanical oscillations. The novelty of this work is in proposing a method to capture the unmodelled nonlinear dynamics as uncertainty in the design of the robust controller. Tight bounds on the uncertainty are obtained using this method which enables high-performance controllers. An IEEE benchmark test system has been used to demonstrate the performance of the designed controller

Observation of deformation modes in Mg-3Al-1Zn

Since magnesium alloys are the lightest metallic materials, they are very attractive for automotive and aerospace industries. The main problem of these alloys is limited ductility due to a shortage of independent slip systems. In order to improve the formability in these alloys, an understanding of the deformation modes is required. In the present work, different slip systems were investigated in rolled Mg-3Al-IZn by means of in situ tensile tests in the SEM. These permitted electron backscatter diffraction (EBSD) and electron backscatter diffraction imaging (QBSD) to be carried out during the test. The results show that non-basal slip systems are active at room temperature.

Students` perceptions of study modes

This paper reports on a survey of how Australian undergraduate students perceive the benefits of broad study modes: face-to-face classes, web-based study, and print-based study. Two benefit types were identified through factor analysis: engagement and functionality. Respondents rated face-to-face classes highest on engagement and print-based study highest on functionality. However, they distinguished only marginally between the engagement and functionality benefits of print-based and web-based study. Two variables associated with differences in students' perceptions of study modes were attendance mode and student tenure. The findings raise questions about the learning and marketing rationales for offering web-based delivery of educational programmes at the expense of both the traditional face-to-face experience and the traditional “distance” experience in Australia using print materials.

The impact of teaching models, group structures and assessment modes on cooperative learning in the student design studio

As a result of ever diminishing teaching resources, an increasing number of architectural educators are setting group design projects, rather then spreading their time thinly over a large number of individual projects. This allows them to co-ordinate longer and more in-depth review sessions on a smaller number of assignment submissions. However, while the group
model may offer an authentic learning model by reflecting design in practice, the approach is not without its obvious shortcomings as a teaching archetype for the assessment of the knowledge and skill competencies of individual students. Hence, what is clear is the need for a readily adoptable andragogy for the teaching and assessment of group design projects.
The following paper describes the background, methodology and findings of a Strategic Teaching and Learning Grant funded research project carried out in the year 2005 at the School of Architecture and Building at Deakin University. The project aimed to inform a change of classroom/studio practice governing the assemblage, teaching and assessment of student design teams. The development through these changes of cooperative and student centred learning principles focused on effective design collaboration and fair assessment should, it will be argued, lead to an enhanced group-learning experience in studio, which will subsequently and ultimately enhance professional practice.

EBSD analysis of deformation modes in Mg-3A1-1Zn

Wrought magnesium alloys exhibit poor cold formability and the accepted explanation is the shortage of independent slip systems. In order to improve the formability in these alloys, an understanding of the deformation modes is required. In the present work, activation of different slip and twinning systems are investigated in rolled Mg–3Al–1Zn using electron back scattering diffraction. Analysis was performed on deformed surfaces and on metallographically prepared cross-sections following deformation at room temperature. The results reinforce the importance of prismatic slip and c-axis compression double twinning.