A class B switch-mode assisted linear amplifier

A switch-mode assisted linear amplifier (SMALA) combining a linear (Class B) and a switch-mode (Class D) amplifier is presented. The usual single hysteretic controlled half-bridge current dumping stage is replaced by two parallel buck converter stages, in a parallel voltage controlled topology. These operate independently: one buck converter sources current to assist the upper Class B output device, and a complementary converter sinks current to assist the lower device. This topology lends itself to a novel control approach of a dead-band at low power levels where neither class D amplifier assists, allowing the class B amplifier to supply the load without interference, ensuring high fidelity. A 20 W implementation demonstrates 85% efficiency, with distortion below 0.08% measured across the full audio bandwidth at 15 W. The class D amplifier begins assisting at 2 W, and below this value, the distortion was below 0.03%. Complete circuitry is given, showing the simplicity of the additional class D amplifier and its corresponding control circuitry.

A class E resonant inverter for use as electronic fluorescent lamp ballast

Class E Resonant Inverters are theoretically capable of delivering any power to a load and achieve 100% efficiency at any frequency of operation. In practice efficiency in the “high 90's” can be achieved into megahertz frequencies regardless of inverter output powers. The topology also allows the manipulation of output power through sub-optimal operation, with a negligible efficiency penalty. The 24W inverter discussed in this paper was specifically designed to harness the benefits, and discuss the shortcomings, of the Class E topology for use in the growing market for portable, battery powered lighting. It exhibits a peak recorded power efficiently of over 98%, and a conservatively measured efficiency of 95% across a range of dimming settings.

Exploiting Web 2.0 technologies to forge live connectedness in class

The economics of supporting learning has seen institutional encouragement of a wide range of blended learning initiatives in face to face and online teaching and learning. This has become one of the key drivers for the adoption of technology in teaching, in a manner occassionally guilty of putting the cart before the horse. Learning spaces are increasingly equipped with a dizzying array of technological options testifying to institutional and governmental investment and commitment in supporting face to face blended learning (QUT, 2011, C/4.2). Yet innovation within traditional learning and teaching models faces a number of challenges both at an institutional level and at the teaching coal face. Web 2.0 technologies present a vast array of opportunities to harness and capture the attention of students in engaging learning opportunitites. This presentation will explore technologies supportive of active learning pedagogies.

The use of Facebook in tertiary education : case study of a unit-related Facebook page in a university justice class

Purpose – This study aims to evaluate the usefulness of a university unit Facebook page, which was established to support a first-year university justice unit. The study pays particular regard to the Facebook page's impact on students learning outcomes and communications amongst students and between students and teaching staff. Design/methodology/approach – All students enrolled in the unit were asked to complete an online survey, which sought to determine whether they used the unit Facebook page and if so, the nature and extent of their use. Findings – The study found that the unit Facebook page was useful in achieving most learning objectives for the unit. This included enhancing students' knowledge and understanding of unit content, as well as their ability to critically analyse unit materials. Students also indicated that they found the Facebook page better than the university's central learning management system across a range of areas. It was particularly useful for facilitating unit-related discussions. Research limitations/implications – The survey results reported in this paper are based on a relatively small sample of students (n=67) from a first-year university justice unit. Future studies should seek to garner evidence from broader and larger samples that transcend specific unit populations. However, the findings of this study do indicate further support for the use of Facebook as a supplementary tool in university education. Originality/value – This study focuses on two aspects of social networking technologies that have not been previously researched and thus contributes to the growing literature on the uses and benefits of Facebook in tertiary education.

A CLASS act : the teaching team approach to subject coordination

Advancing the development of good practice around the teaching team has been the focus of a recently completed, nationally funded Australian grant entitled Coordinators Leading Advancement of Sessional Staff (CLASS). The project focused on developing leadership capacity of subject coordinators to provide supportive contexts for sessional staff to enhance their knowledge of teaching practice and contribute to subject improvement through a team approach. An action learning approach and notions of distributed leadership underpinned the activities of the teaching teams in the program. This paper provides an overview of a practical approach, led by the subject coordinator, to engaging sessional staff through the facilitation of a supportive network within the teaching team. It addresses some of the gaps identified in the recent literature which includes lack of role clarity for all members of the team and provides some examples of initiatives that teams engaged with to address some of the challenges identified. Resources to support this approach were developed and are shared through the project website. Recommendations for future direction include improved policy and practice at the institutional level, better recognition and reward for subject coordinators and resourcing to support the participation and professional development needs of sessional staff.

'In the Room' and 'School Chemistry Class'

Two poems in journal Axon. 2013 Issue 4.

Theoretical and practical issues in team teaching a large undergraduate class

Attempts by universities to provide an improved learning environment to students have led to an increase in team-teaching approaches in higher education. While the definitions of team-teaching differ slightly, the benefits of team-teaching have been cited widely in the higher education literature. By tapping the specialist knowledge of a variety of staff members, students are exposed to current and emerging knowledge in different fields and topic areas; students are also able to understand concepts from a variety of viewpoints. However, while there is some evidence of the usefulness of team-teaching, there is patchy empirical support to underpin how well students appreciate and adapt to team-teaching approaches. This paper reports on the team-teaching approaches adopted in the delivery of an introductory journalism and communication course at the University of Queensland. The success of the approaches is examined against the background of quantitative and qualitative data. The study found that team-teaching is generally very well received by undergraduate students because they value the diverse expertise and teaching styles they are exposed to. Despite the positive feedback, students also complained about problems of continuity and cohesiveness.

Domestic artefacts: Sustainability in the context of Indian middle class

Sustainability has become one of the important research topics in the field of Human Computer Interaction (HCI). However, the majority of work has focused on the Western culture. In this paper, we explore sustainable household practices in the developing world. Our research draws on the results from an ethnographic field study of household women belonging to the so-called middle class in India. We analyze our results in the context of Blevis' [4] principles of sustainable interaction design (established within the Western culture), to extract the intercultural aspects that need to be considered for designing technologies. We present examples from the field that we term "domestic artefacts". Domestic artefacts represent creative and sustainable ways household women appropriate and adapt used objects to create more useful and enriching objects that support household members' everyday activities. Our results show that the rationale behind creating domestic artefacts is not limited to the practicality and usefulness, but it shows how religious beliefs, traditions, family intimacy, personal interests and health issues are incorporated into them.

Binary image steganographic techniques classification based on multi-class steganalysis

In this paper, we propose a new multi-class steganalysis for binary image. The proposed method can identify the type of steganographic technique used by examining on the given binary image. In addition, our proposed method is also capable of differentiating an image with hidden message from the one without hidden message. In order to do that, we will extract some features from the binary image. The feature extraction method used is a combination of the method extended from our previous work and some new methods proposed in this paper. Based on the extracted feature sets, we construct our multi-class steganalysis from the SVM classifier. We also present the empirical works to demonstrate that the proposed method can effectively identify five different types of steganography.

Fault diagnosis of low speed bearing based on acoustic emission signal and multi-class relevance vector machine

This study presents an acoustic emission (AE) based fault diagnosis for low speed bearing using multi-class relevance vector machine (RVM). A low speed test rig was developed to simulate the various defects with shaft speeds as low as 10 rpm under several loading conditions. The data was acquired using anAEsensor with the test bearing operating at a constant loading (5 kN) andwith a speed range from20 to 80 rpm. This study is aimed at finding a reliable method/tool for low speed machines fault diagnosis based on AE signal. In the present study, component analysis was performed to extract the bearing feature and to reduce the dimensionality of original data feature. The result shows that multi-class RVM offers a promising approach for fault diagnosis of low speed machines.

Total energy shaping of a class of underactuated Port-Hamiltonian Systems using a new set of closed-loop potential shape variables

This paper proposes a method for designing set-point regulation controllers for a class of underactuated mechanical systems in Port-Hamiltonian System (PHS) form. A new set of potential shape variables in closed loop is proposed, which can replace the set of open loop shape variables-the configuration variables that appear in the kinetic energy. With this choice, the closed-loop potential energy contains free functions of the new variables. By expressing the regulation objective in terms of these new potential shape variables, the desired equilibrium can be assigned and there is freedom to reshape the potential energy to achieve performance whilst maintaining the PHS form in closed loop. This complements contemporary results in the literature, which preserve the open-loop shape variables. As a case study, we consider a robotic manipulator mounted on a flexible base and compensate for the motion of the base while positioning the end effector with respect to the ground reference. We compare the proposed control strategy with special cases that correspond to other energy shaping strategies previously proposed in the literature.

Systematic differences in membrane acyl composition associated with varying body mass in mammals occur in all phospholipid classes : an analysis of kidney and brain

The acyl composition of membrane phospholipids in kidney and brain of mammals of different body mass was examined. It was hypothesized that reduction in unsaturation index (number of double bonds per 100 acyl chains) of membrane phospholipids with increasing body mass in mammals would be made-up of similar changes in acyl composition across all phospholipid classes and that phospholipid class distribution would be regulated and similar in the same tissues of the different-sized mammals. The results of this study supported both hypotheses. Differences in membrane phospholipid acyl composition (i. e. decreased omega-3 fats, increased monounsaturated fats and decreased unsaturation index with increasing body size) were not restricted to any specific phospholipid molecule or to any specific phospholipid class but were observed in all phospholipid classes. With increase in body mass of mammals both monounsaturates and use of less unsaturated polyunsaturates increases at the expense of the long-chain highly unsaturated omega-3 and omega-6 polyunsaturates, producing decreases in membrane unsaturation. The distribution of membrane phospholipid classes was essentially the same in the different-sized mammals with phosphatidylcholine (PC) and phosphatidylethanolamine (PE) together constituting similar to 91% and similar to 88% of all phospholipids in kidney and brain, respectively. The lack of sphingomyelin in the mouse tissues and higher levels in larger mammals suggests an increased presence of membrane lipid rafts in larger mammals. The results of this study support the proposal that the physical properties of membranes are likely to be involved in changing metabolic rate.

Configurations of Gender, Class and Rurality in Resource Affected Rural Australia

Historically, class has been a key concern in studies of resource affected communities (e.g., Williamson 1982, Warwick and Littlejohn 1992). While work continues, particularly in Britain, today it reflects the rationalization of the British mining sector, and thus focuses largely on mining heritage (e.g., Strangleman et al. 1999, Dicks 2008). In contrast, this chapter examines class relations as manifest in a contemporary setting in rural Australia. This site, the Ravensthorpe Shire in the south west of Western Australia, relied largely on agriculture until 2004 when BHP Billiton commenced construction of a nickel mine in the area. This affected the entire Shire as well as the two rural communities of Ravensthorpe and Hopetoun. The mine, which was officially opened in June 2008, is one of a large number of new mineral and energy developments being established in non metropolitan areas of the country as high international demand for resources fuels significant growth in the sector. In a single six month period in 2009, for example, 15 major minerals and energy projects were completed across the nation and a further 74 projects were at advanced stages (Australian Bureau of Agricultural Economics 2009). A number of these were, as was the case in Ravensthorpe, in what had been traditionally agricultural communities.