Doubly Fed Induction Generators : Overview and Intelligent Control Strategies for Wind Energy Conversion Systems

Adjustable speed induction generators, especially the Doubly-Fed Induction Generators (DFIG) are becoming increasingly popular due to its various advantages over fixed speed generator systems. A DFIG in a wind turbine has ability to generate maximum power with varying rotational speed, ability to control active and reactive by integration of electronic power converters such as the back-to-back converter, low rotor power rating resulting in low cost converter components, etc, DFIG have become very popular in large wind power conversion systems. This chapter presents an extensive literature survey over the past 25 years on the different aspects of DFIG. Application of H8 Controller for enhanced DFIG-WT performance in terms of robust stability and reference tracking to reduce mechanical stress and vibrations is also demonstrated in the chapter.

Insulation coordination study for a 50 kV traction feeder station

The heavy haul rail network in Queensland Australia generally adopts a lightning impulse withstand voltage rating of 250 kV for the switchgear and autotransformers within its 50 kV ac traction feeder stations. The aging switchgear across a number of feeder stations in this network are undergoing upgrade and the rail network operator is considering the possibility of using 200 kV rating for the upgraded switchgear. This paper investigates the lightning over-voltages that could occur at the feeder stations under review. Fast front transient models of the feeder stations and the associated traction corridors are developed in PSCAD/EMTDC software. Simulations are conducted to evaluate the likely over-voltages under various scenarios and the results are presented. Finally, the required lightning impulse withstand voltage rating for the switchgear is determined based on the simulation results.

Energy use assessment of educational buildings: Toward a campus-wide sustainable energy policy

The purpose of this article is to assess the viability of blanket sustainability policies, such as Building Rating Systems in achieving energy efficiency in university campus buildings. We analyzed the energy consumption trends of 10 LEED-certified buildings and 14 non-LEED certified buildings at a major university in the US. Energy Use Intensity (EUI) of the LEED buildings was significantly higher (EUILEED= 331.20 kBtu/sf/yr) than non-LEED buildings (EUInon-LEED=222.70 kBtu/sf/yr); however, the median EUI values were comparable (EUILEED= 172.64 and EUInon-LEED= 178.16). Because the distributions of EUI values were non-symmetrical in this dataset, both measures can be used for energy comparisons—this was also evident when EUI computations exclude outliers, EUILEED=171.82 and EUInon-LEED=195.41. Additional analyses were conducted to further explore the impact of LEED certification on university campus buildings energy performance. No statistically significant differences were observed between certified and non-certified buildings through a range of robust comparison criteria. These findings were then leveraged to devise strategies to achieve sustainable energy policies for university campus buildings and to identify potential issues with portfolio level building energy performance comparisons.

Nothing new in Indigenous reform agenda

Indigenous leader Pat Dodson – who revealed he has met Prime Minister Tony Abbott only once, and then in passing – said last week that removal of frontline services from Indigenous organisations working towards Closing the Gap in Indigenous health “would seem counter intuitive to any fair-minded Australian”. But that, he said in this Age OpEd, has been the result of the Federal Government’s much-awaited Indigenous Advancement Strategy...

Behaviour of LSF floor systems with improved joist sections under fire conditions

Fire safety design of buildings is essential to safeguard lives and minimize the loss of damage to properties. Light-weight cold-formed steel channel sections along with fire resistive plasterboards are used to construct light gauge steel frame floor systems to provide the required fire resistance rating. However, simply adding more plasterboard layers is not an efficient method to increase FRR. Hence this research focuses on using joists with improved joist section profiles such as hollow flange sections to increase the structural capacity of floor systems under fire conditions and thus their FRR. In this research, the structural and thermal behaviour of LSF floor systems made of LiteSteel Beams with different plasterboard and insulation configurations was investigated using four full scale tests under standard fires. Based on the ultimate failure load of the floor joist at ambient temperature, transient state fire tests were conducted for different Load Ratios. These fire tests showed that the new LSF floor system has improved the FRR well above that of those made of lipped channel sections. The joist failure was predominantly due to local buckling of LSB compression flanges near mid-span with severe yielding of tension flanges. Fire tests have provided valuable structural and thermal performance data of tested floor systems that included time-temperature profiles, and failure times and temperatures. Average failure temperatures of LSB joists and reduced yield strengths were used to predict their ultimate moment capacities, which were compared with corresponding test capacities. This allowed an assessment in relation to the accuracy of current design rules for steel joists at elevated temperatures. This paper presents the details of full scale fire tests of LSF floor systems made of LSB joists with different plasterboard and insulation configurations and their results along with some important findings.

The on-road experiences and awareness of sleepiness in a sample of Australian highway drivers: A roadside driver sleepiness study

Objective Driver sleepiness contributes substantially to road crash incidents. Simulator and on-road studies clearly reveal an impairing effect from sleepiness on driving ability. However, the degree to which drivers appreciate the dangerousness of driving while sleepy is somewhat unclear. This study sought to determine drivers’ on-road experiences of sleepiness, their prior sleep habits, and personal awareness of the signs of sleepiness. Methods Participants were a random selection of 92 drivers travelling on a major highway in the state of Queensland, Australia, who were stopped by police as part of routine drink driving operations. Participants completed a brief questionnaire that included demographic information, sleepy driving experiences (signs of sleepiness and on-road experiences of sleepiness), and prior sleep habits. A modified version of the Karolinska Sleepiness Scale (KSS) was used to assess subjective sleepiness in the 15 minutes prior to being stopped by police. Results Participants rating of subjective sleepiness were quite low, with 90% reporting being alert to extremely alert on the KSS. Participants were reasonably aware of the signs of sleepiness, with many signs of sleepiness associated with on-road experiences of sleepiness. Additionally, the number of hours spent driving was positively correlated with the drivers’ level of sleep debt. Conclusions The results suggest the participants had moderate experience of driving while sleepy and many were aware of the signs of sleepiness. The relationship between driving long distances and increased sleep debt is a concern for road safety – increased education regarding the dangers of sleepy driving seems warranted.

The implicit structure of positive characteristics

The implicit structure of positive character traits was examined in two studies of 190 and 100 undergraduates. Participants judged the pairwise covariation or semantic similarity of 42 positive characteristics using a sorting or a rating task. Characteristics were drawn from a new classification of strengths and virtues, the Five-Factor Model, and a taxonomy of values. Participants showed consistent patterns of perceived association among the characteristics across the study conditions. Multidimensional scaling yielded three consistent dimensions underlying these judgments (“warmth vs. self-control,” “vivacity vs. decency,” and “wisdom vs. power”). Cluster analyses yielded six consistent groupings—“self-control,” “love,” “wisdom,” “drive,” “vivacity,” and “collaboration”—that corresponded only moderately to the virtue classification. All three taxonomies were systematically related to this implicit structure, but none captured it satisfactorily on its own. Revisions to positive psychology’s classification of strengths are proposed.

The development of an instrument for assessing cognitive ability and screening for the cognitive decline associated with dementia in people with moderate to profound intellectual disability

Individuals with intellectual disability have a greater risk of developing dementia.The diagnosis of dementia relies on accurate testing of cognitive function however existing tests have limited utility in people whose intellectual disability is moderate or greater. A new test was developed and underwent preliminary testing to determine use across a wider ability spectrum. The Cognitive Baseline & Screener for People with Intellectual Disability (CBS-ID) was administered to a sample of 17 dyads (n=34) (people with intellectual disability (who completed CBS-ID) and caregivers (who provided an independent rating of function)).The CBS-ID performed well on several usability metrics across all intellectual disability level and was highly correlated with existing measures of cognitive function to which it was compared.Further research with a larger sample is needed to assess the test's ability to detect change in cognition over time & determine if it aids the process of diagnosing dementia.

Decision support system for infrastructure sustainability in operations

There is an increasing awareness of sustainability and climate change and its impact on infrastructure and engineering asset management in design, construction, and operations. Sustainability rating tools have been proposed and/or developed that provide ratings of infrastructure projects in differing phases of their life cycle on sustainability. This paper provides an overview of decision support systems using sustainability rating framework that can be used to prioritize or select tasks and activities within projects to enhance levels of sustainability outcomes. These systems can also be used to prioritize projects within an organization to optimize sustainability outcomes within an allocated budget.

Understanding the business case for infrastructure sustainability

The relationship between corporate and sustainability performance continues to be controversial and unclear, not withstanding numerous theoretical and empirical studies. Despite this, views on corporate responsibilities “meet where management can show how voluntary social and environmental management contributes to the competitiveness and economic success of the company.” This approach is fundamental to the business case for infrastructure sustainability. It suggests that beyond-compliance activities undertaken by companies are commercially justified if they can be shown to contribute to profitability and shareholder value. Potential public good benefits range across a wide spectrum of economic (for example employment, local purchasing, reduced demand for electricity generation), social (indigenous employment and development, equity of access), and environmental (lower greenhouse gas emission, reduced use of non-renewable resources and potable water, less waste, enhanced biodiversity). Some of these benefits have impacts that lie in more than one of the economic, social, and environmental areas of public goods. Using a sustainability rating schemes and potential business benefits from sustainability initiatives, this paper presents a brief summary of an online survey of industry that identifies how rating scheme themes and business benefits relate. This allows for a case to be built demonstrating which sustainability themes offer particular business benefits.

Sustainability in infrastructure asset management

The expectation to integrate sustainability aspects (social, environmental, and economic success) into the design, delivery, and operation of infrastructure assets is growing rapidly and globally. There are now several tools and frameworks available to benchmark and measure sustainable performance of infrastructure projects and assets. This paper briefly describes the infrastructure sustainability (IS) rating tool developed by the Australian Green Infrastructure Council (AGIC) that was launched in February 2012. This tool evaluates sustainability initiatives and potential environmental, social, and economic impacts of infrastructure projects and assets. The rating tool provides the following benefits to industry: a common national language for sustainability; a vehicle for consistent application and evaluation of sustainability in tendering processes; assists in scoping whole-of-life sustainability risks, enabling smarter solutions that reduce risks and costs; fosters resource efficiency and waste reduction, reducing costs; fosters innovation and continuous improvement in sustainability outcomes; and builds an organization’s credentials and reputation in its approach to sustainability. The infrastructure types covered by this tool include transport, energy, water, and communication. The key themes of sustainability evaluation will be briefly presented in this paper, and they include management and governance; use of resources; emissions, pollution, and waste; ecology; people and place; and innovation.

Geography and international assessment: Opportunity or distraction

Assessments of students in primary and secondary education are debated among practitioners, policy-makers, and parents. In some countries, assessment scores serve a criterion for passage between levels of education, for example, from secondary school to post-secondary education. Those practices are often traditions and while they come under criticism, they are a long-accepted part of the educational practices within a country. In those countries, the students’ assessment and examination scores are posted in public places or published in local news media. In other countries, assessments are used for the periodic checks on individual student progress. The results of assessments may be used for rating schools, and in some cases, they are used for evaluating the performance of teachers. Assessments are used less often to analyze student performance and make judgments regarding the performance of the curriculum. Even less often, assessments serve to critically establish strategies for the improvement of student learning and educational practices. The ends on the continuum of the assessment debate often focus on the opportunities that assessments present to improve education on one end. The other end is that assessments serve as a major distraction from the important work of teachers by removing classroom room time from instruction. The debate on those issues continues.

Submission to Communications Alliance Industry Code: Copyright Notice Scheme

In making this submission, we suggest that Australia learn from the experiences of other jurisdictions, and avoid some of the mistakes that have been made. In particular, this involves: * Ensuring that adequate information is available to evaluate the success of the scheme * Ensuring that notices sent to consumers provide full and accurate information that helps them understand their rights and options * Limiting the potential abuse of the system, and particularly attempts to intimidate consumers into paying unfair penalties through ‘speculative invoicing’ * Avoiding the potential for actual or perceived bias in the scheme’s oversight body

Cross-cultural adaptation, reliability and validity of the Turkish version of the spine functional index

Background The Spine Functional Index (SFI) is a patient reported outcome measure with sound clinimetric properties and clinical viability for the determination of whole-spine impairment. To date, no validated Turkish version is available. The purpose of this study is to cross-culturally adapted the SFI for Turkish-speaking patients (SFI-Tk) and determine the psychometric properties of reliability, validity and factor structure in a Turkish population with spine musculoskeletal disorders. Methods The SFI English version was culturally adapted and translated into Turkish using a double forward and backward method according to established guidelines. Patients (n = 285, cervical = l29, lumbar = 151, cervical and lumbar region = 5, 73% female, age 45 ± 1) with spine musculoskeletal disorders completed the SFI-Tk at baseline and after a seven day period for test-retest reliability. For criterion validity the Turkish version of the Functional Rating Index (FRI) was used plus the Neck Disability Index (NDI) for cervical patients and the Oswestry Disability Index (ODI) for back patients. Additional psychometric properties were determined for internal consistency (Chronbach’s α), criterion validity and factor structure. Results There was a high degree of internal consistency (α = 0.85, item range 0.80-0.88) and test-retest reliability (r = 0.93, item range = 0.75-0.95). The factor analysis demonstrated a one-factor solution explaining 24.2% of total variance. Criterion validity with the ODI was high (r = 0.71, p < 0.001) while the FRI and NDI were fair (r = 0.52 and r = 0.58, respectively). The SFI-Tk showed no missing responses with the ‘half-mark’ option used in 11.75% of total responses by 77.9% of participants. Measurement error from SEM and MDC90 were respectively 2.96% and 7.12%. Conclusions The SFI-Tk demonstrated a one-factor solution and is a reliable and valid instrument. The SFI-Tk consists of simple and easily understood wording and may be used to assess spine region musculoskeletal disorders in Turkish speaking patients.

Enhanced cortisol suppression following administration of low-dose dexamethasone in first-episode psychosis patients

OBJECTIVE Impaired regulation of the hypothalamic-pituitary-adrenal (HPA) axis and hyper-activity of this system have been described in patients with psychosis. Conversely, some psychiatric disorders such as post-traumatic stress disorder (PTSD) are characterised by HPA hypo-activity, which could be related to prior exposure to trauma. This study examined the cortisol response to the administration of low-dose dexamethasone in first-episode psychosis (FEP) patients and its relationship to childhood trauma. METHOD The low-dose (0.25 mg) Dexamethasone Suppression Test (DST) was performed in 21 neuroleptic-naive or minimally treated FEP patients and 20 healthy control participants. Childhood traumatic events were assessed in all participants using the Childhood Trauma Questionnaire (CTQ) and psychiatric symptoms were assessed in patients using standard rating scales. RESULTS FEP patients reported significantly higher rates of childhood trauma compared to controls (p = 0.001) and exhibited lower basal (a.m.) cortisol (p = 0.04) and an increased rate of cortisol hyper-suppression following dexamethasone administration compared to controls (33% (7/21) vs 5% (1/20), respectively; p = 0.04). There were no significant group differences in mean cortisol decline or percent cortisol suppression following the 0.25 mg DST. This study shows for the first time that a subset of patients experiencing their first episode of psychosis display enhanced cortisol suppression. CONCLUSIONS These findings suggest there may be distinct profiles of HPA axis dysfunction in psychosis which should be further explored.