A ∑GIi/D/1/∞ queue with heterogeneous input/output slot times

In this paper, we present a ∑GIi/D/1/∞ queue with heterogeneous input/output slot times. This queueing model can be regarded as an extension of the ordinary GI/D/1/∞ model. For this ∑GIi/D/1/∞ queue, we assume that several input streams arrive at the system according to different slot times. In other words, there are different slot times for different input/output processes in the queueing model. The queueing model can therefore be used for an ATM multiplexer with heterogeneous input/output link capacities. Several cases of the queueing model are discussed to reflect different relationships among the input/output link capacities of an ATM multiplexer. In the queueing analysis, two approaches: the Markov model and the probability generating function technique, are adopted to develop the queue length distributions observed at different epochs. This model is particularly useful in the performance analysis of ATM multiplexers with heterogeneous input/output link capacities.

How I became the first Aboriginal person in Australia to lead a national education organisation

In this paper, Bronwyn Fredericks reflects on how, in 1997, she became the National President of the Council of Australian Postgraduate Associations Inc. (CAPA). The paper describes the election process faced by Fredericks, and identifies some of her key achievements during her time as National President. In becoming the National President, Bronwyn became the first Aboriginal person in Australia to lead a national education organisation. The story within this paper is told from the author’s autobiographical memory, drawing on the cultural, social and political context in which the story and the author were (and are) situated (Wojecki 2007). In this way the story teller reveals story lines which have not previously been articulated (Wojecki 2007). Throughout this paper, Fredericks ‘re-stories’ her experiences of leadership.

Curriculum change in testing times

In these new, testing times, we need a new controlled rapid approach to curriculum change. Judy Smeed and TerrI Bourke explain.

Remediation strategies of shaft and common mode voltages in adjustable speed drive systems

AC motors are largely used in a wide range of modern systems, from household appliances to automated industry applications such as: ventilations systems, fans, pumps, conveyors and machine tool drives. Inverters are widely used in industrial and commercial applications due to the growing need for speed control in ASD systems. Fast switching transients and the common mode voltage, in interaction with parasitic capacitive couplings, may cause many unwanted problems in the ASD applications. These include shaft voltage and leakage currents. One of the inherent characteristics of Pulse Width Modulation (PWM) techniques is the generation of the common mode voltage, which is defined as the voltage between the electrical neutral of the inverter output and the ground. Shaft voltage can cause bearing currents when it exceeds the amount of breakdown voltage level of the thin lubricant film between the inner and outer rings of the bearing. This phenomenon is the main reason for early bearing failures. A rapid development in power switches technology has lead to a drastic decrement of switching rise and fall times. Because there is considerable capacitance between the stator windings and the frame, there can be a significant capacitive current (ground current escaping to earth through stray capacitors inside a motor) if the common mode voltage has high frequency components. This current leads to noises and Electromagnetic Interferences (EMI) issues in motor drive systems. These problems have been dealt with using a variety of methods which have been reported in the literature. However, cost and maintenance issues have prevented these methods from being widely accepted. Extra cost or rating of the inverter switches is usually the price to pay for such approaches. Thus, the determination of cost-effective techniques for shaft and common mode voltage reduction in ASD systems, with the focus on the first step of the design process, is the targeted scope of this thesis. An introduction to this research – including a description of the research problem, the literature review and an account of the research progress linking the research papers – is presented in Chapter 1. Electrical power generation from renewable energy sources, such as wind energy systems, has become a crucial issue because of environmental problems and a predicted future shortage of traditional energy sources. Thus, Chapter 2 focuses on the shaft voltage analysis of stator-fed induction generators (IG) and Doubly Fed Induction Generators DFIGs in wind turbine applications. This shaft voltage analysis includes: topologies, high frequency modelling, calculation and mitigation techniques. A back-to-back AC-DC-AC converter is investigated in terms of shaft voltage generation in a DFIG. Different topologies of LC filter placement are analysed in an effort to eliminate the shaft voltage. Different capacitive couplings exist in the motor/generator structure and any change in design parameters affects the capacitive couplings. Thus, an appropriate design for AC motors should lead to the smallest possible shaft voltage. Calculation of the shaft voltage based on different capacitive couplings, and an investigation of the effects of different design parameters are discussed in Chapter 3. This is achieved through 2-D and 3-D finite element simulation and experimental analysis. End-winding parameters of the motor are also effective factors in the calculation of the shaft voltage and have not been taken into account in previous reported studies. Calculation of the end-winding capacitances is rather complex because of the diversity of end winding shapes and the complexity of their geometry. A comprehensive analysis of these capacitances has been carried out with 3-D finite element simulations and experimental studies to determine their effective design parameters. These are documented in Chapter 4. Results of this analysis show that, by choosing appropriate design parameters, it is possible to decrease the shaft voltage and resultant bearing current in the primary stage of generator/motor design without using any additional active and passive filter-based techniques. The common mode voltage is defined by a switching pattern and, by using the appropriate pattern; the common mode voltage level can be controlled. Therefore, any PWM pattern which eliminates or minimizes the common mode voltage will be an effective shaft voltage reduction technique. Thus, common mode voltage reduction of a three-phase AC motor supplied with a single-phase diode rectifier is the focus of Chapter 5. The proposed strategy is mainly based on proper utilization of the zero vectors. Multilevel inverters are also used in ASD systems which have more voltage levels and switching states, and can provide more possibilities to reduce common mode voltage. A description of common mode voltage of multilevel inverters is investigated in Chapter 6. Chapter 7 investigates the elimination techniques of the shaft voltage in a DFIG based on the methods presented in the literature by the use of simulation results. However, it could be shown that every solution to reduce the shaft voltage in DFIG systems has its own characteristics, and these have to be taken into account in determining the most effective strategy. Calculation of the capacitive coupling and electric fields between the outer and inner races and the balls at different motor speeds in symmetrical and asymmetrical shaft and balls positions is discussed in Chapter 8. The analysis is carried out using finite element simulations to determine the conditions which will increase the probability of high rates of bearing failure due to current discharges through the balls and races.

Hoodie-wearing Hamlet mixes horror with humour in a play for our times [REVIEW]

Hamlet By Shakespeare. La Boite Theatre Company, Brisbane, February 10 LA Boite Theatre Company begins this year's season with a new look, a new logo and a new interpretation of Hamlet directed by artistic director David Berthold. In this production, Berthold contemporises Shakespeare's tragedy by focusing on the family relationships and introducing modern references in the set, sound and costume design: this Hamlet wears jeans and a hoodie.

Analysis of HapMap tag-SNPs in dysbindin (DTNBP1) reveals evidence of consistent association with schizophrenia

Dystrobrevin binding protein 1 (DTNBP1), or dysbindin, is thought to be critical in regulating the glutamatergic system. While the dopamine pathway is known to be important in the aetiology of schizophrenia, it seems likely that glutamatergic dysfunction can lead to the development of schizophrenia. DTNBP1 is widely expressed in brain, levels are reduced in brains of schizophrenia patients and a DTNBP1 polymorphism has been associated with reduced brain expression. Despite numerous genetic studies no DTNBP1 polymorphism has been strongly implicated in schizophrenia aetiology. Using a haplotype block-based gene-tagging approach we genotyped 13 SNPs in DTNBP1 to investigate possible associations with DTNBP1 and schizophrenia. Four polymorphisms were found to be significantly associated with schizophrenia. The strongest association was found with an A/C SNP in intron 7 (rs9370822). Homozygotes for the C allele of rs9370822 were more than two and a half times as likely to have schizophrenia compared to controls. The other polymorphisms showed much weaker association and are less likely to be biologically significant. These results suggest that DTNBP1 is a good candidate for schizophrenia risk and rs9370822 is either functionally important or in disequilibrium with a functional SNP, although our observations should be viewed with caution until they are independently replicated.

The influence of platform walking on BRT station bus dwell time estimation

The common approach to estimate bus dwell time at a BRT station platform is to apply the traditional dwell time methodology derived for suburban bus stops. Current dwell time models are sensitive towards bus type, fare collection policy along with the number of boarding and alighting passengers. However, they fall short in accounting for the effects of passenger/s walking on a relatively longer BRT station platform. Analysis presented in this paper shows that the average walking time of a passenger at BRT platform is 10 times more than that of bus stop. The requirement of walking to the bus entry door at the BRT station platform may lead to the bus experiencing a higher dwell time. This paper presents a theory for a BRT network which explains the loss of station capacity during peak period operation. It also highlights shortcomings of present available bus dwell time models suggested for the analysis of BRT operation.

High-challenge teaching for senior English as an Additional Language (EAL) learners in times of change

This paper will present a brief overview of the recent shifts within English and EAL/D (English as an additional language/dialect) curriculum documents and their focus on critical literacy, using the Queensland context as a case in point. The English syllabus landscape in Queensland has continued to morph in recent years. From 2002 to 2009, teachers of senior English and English as an Additional Language (EAL/D) have witnessed no less than four separate syllabus documents that impact on their daily work. The Australian Curriculum, when finally implemented, will also require teachers to navigate and grapple with its particular obligations and affordances. The combined effect of the shifts and tensions between recent policy documents has led to confusion about exactly how to cater for EAL/D learners in mainstream English. We discuss the possible effects of this on teachers as the agents of policy implementation and argue that in spite of such contradictions, EAL/D teachers can productively use syllabus frameworks to craft pedagogy to cater for their EAL/D learners’ language and literacy needs. Following this, we present aspects of the teaching practice of four teachers of senior EAL/D, who provide intellectually-engaging, critical literacy pedagogy that takes into account the language proficiency level of their learners, within the required curriculum. Such practice provides teachers with valuable pedagogic possibilities to meet EAL/D learners’ needs within continually varying policy terrain.

Reproducing successful rituals in bad times : exploring interactions of a new science teacher

Teaching is emotional work. This is especially the case in the first years of teaching when new teachers are particularly vulnerable. By understanding changes in teacher emotions in the early years of teaching we hope to identify strategies that might ultimately reduce teacher attrition. As part of a larger study of the transition of new teachers to the profession, this ethnographic case study explores how a new science teacher produced and reproduced positive emotional interaction rituals with her students in her first year of teaching. We show how dialogical interactions were positive and satisfying experiences for the teacher, and how they were reproduced successfully in different contexts. We also illustrate how both teacher and students used humor to create a structure for dialogical interactions. During these successful interactions the students used shared resources to satisfy their teacher that they were engaging in the relevant science content. The implications of what we have learned for the professional development of new teachers are discussed in relation to an expanded understanding of teacher emotions.

'Being-in-the-world-of-care' : the lived experiences of older people receiving community aged care packages in Queensland

It has been recognised in current literature that, in general, Australia’s population is ageing and that older people are increasingly choosing to continue to live in the community in their own homes for as long as possible. Such factors of social change are expected to lead to larger numbers of older people requiring community care services for longer periods. Despite this, there is little information available in the literature on the perceptions and experiences of older people regarding community-based care and support. This study explores the lived experience of a small group of older people living in South East Queensland who were receiving a level of care consistent with the Community Aged Care Package (CACP). It also sought to examine the impact and meaning of that care on the older person’s overall lifestyle, autonomy, and personal satisfaction. In-depth interviews were undertaken with these older people, and were analysed using Heidegger’s interpretive hermeneutical phenomenological approach. Shared narratives were then explored using Ricoeur’s narrative analysis framework. In order to sensitise the researcher to the unconscious or symbolic aspects of the care experience, Wolfensberger’s social role valorization theory (SRV) was also utilised during a third phase of analysis. Methodological rigour was strengthened within this study through the use of reflexivity and an in-depth member check discussion that was conducted with each participant. The interviews revealed there were significant differences in expectations, understanding, and perceptions between older people and their carers or service providers. The older person perceived care primarily in relational terms, and clearly preferred active participation in their care and a consistent relationship with a primary carer. Older people also sought to maintain their sense of autonomy, lifestyle, home environment, routines, and relationships, as closely as possible to those that existed prior to their requiring assistance. However, these expectations were not always supported by the care model. On the whole, service providers did not always understand what older people perceived was important within the care context. Carers seldom looked beyond the provision of assistance with specific daily tasks to consider the real impact of care on the older person. The study identified that older people reported a range of experiences when receiving care in their own homes. While some developed healthy and supportive connections with their carers, others experienced ageism, abuse, and exploitation. Unsatisfactory interactions at times resulted in a loss, to varying degrees, of their independence, their possessions, and their connectedness with others. There is therefore a need for service providers to pay more attention to the perceptions and self-perceived needs of older people, to avoid unintended or unnecessary negative impacts occurring within care provision. The study provides valuable information regarding the older person’s experience that will assist in supporting the further development and improvement of this model of care. It is proposed that these insights will enable CACPs to cater more closely to the actual needs and preferences of older people, and to avoid causing preventable harm to care recipients.