Generator coherency and area detection in large power systems

This paper provides a new general approach for defining coherent generators in power systems based on the coherency in low frequency inter-area modes. The disturbance is considered to be distributed in the network by applying random load changes which is the random walk representation of real loads instead of a single fault and coherent generators are obtained by spectrum analysis of the generators velocity variations. In order to find the coherent areas and their borders in the inter-connected networks, non-generating buses are assigned to each group of coherent generator using similar coherency detection techniques. The method is evaluated on two test systems and coherent generators and areas are obtained for different operating points to provide a more accurate grouping approach which is valid across a range of realistic operating points of the system.

Making the case for improved structural design : tornado outbreaks of 2011

A total of 1,625 tornadoes occurred in the United States in 2011, resulting in economic losses that exceeded $25 billion. Two tornado outbreaks stand out because they caused more than half of those losses. The tornadoes that cut through Tuscaloosa, Alabama, on April 27 and Joplin, Missouri, on May 22 were responsible for a combined 223 fatalities and more than 13,000 damaged buildings in the two cities. Although the economic losses associated with tornado damage are well documented, the writers argue that the overall impact should encompass longer term, broader considerations such as the social disruption and psychological effects that impact communities. This paper examines observations by tornado damage assessment teams led by the first author in these two medium-sized cities and suggests that the evolution of building codes and past approaches to construction have led to conditions that made this extent of damage possible. The authors outline a multidisciplinary path forward that incorporates engineering research and social and economic studies into a new design paradigm leading to building code changes and social practices that will improve resistance and mitigate future losses at a community level from tornadoes.

SKMA - A Key Management Architecture for SCADA Systems

Supervisory Control And Data Acquisition (SCADA) systems are widely used in the management of critical infrastructure such as electricity and water distrubution systems. Currently there is little understanding of how to best protect SCADA systems from malicious attacks. We review the constraints and requirements for SCADA security and propose a suitable architecture (SKMA) for secure SCADA communications. The architecture includes a proposed key management protocol (SKMP). We compare the architecture with a previous proposal from Sandia Labs.

Why ask new questions?

It can probably be said those people who work in the world of the natural sciences— chemistry, biology, mathematics, and so on—regard themselves as inhabiting a fairly straight-forward epistemological world. They have a body of knowledge to draw upon from within any given area, much like a set of bricks in a wall, and when they conduct their experiments, they add another brick to that wall … and the wall gets taller, and they know more than they did before. Such scientists would contend that the questions they ask as part of their research flow naturally from the very nature of the world itself. But even then, they could also argue that the specifics of the question ultimately don‟t really matter that much, because if enough people work on any given brick, the truth will eventually emerge anyway.

Analysing policy values in a knowledge economy

This fascinating handbook defines how knowledge contributes to social and economic life, and vice versa. It considers the five areas critical to acquiring a comprehensive understanding of the knowledge economy: the nature of the knowledge economy; social, cooperative, cultural, creative, ethical and intellectual capital; knowledge and innovation systems; policy analysis for knowledge-based economies; and knowledge management. In presenting the outcomes of an important body of research, the handbook enables knowledge policy and management practitioners to be more systematically guided in their thinking and actions. The contributors cover a wide disciplinary spectrum in an accessible way, presenting concise, to-the-point discussions of critical concepts and practices that will enable practitioners to make effective research, managerial and policy decisions. They also highlight important new areas of concern to knowledge economies such as wisdom, ethics, language and creative economies that are largely overlooked.

Astronomy on the high seas

This article describes the development and launching of a stargazing activity on two cruise ships, Pacific Dawn and Pacific Sun, which sail from Australian ports. The session included a presentation entitled “Voyage to the Stars” that gave passengers an overview of the life cycle of stars from star-birth nebulae to white dwarfs and black holes. In the presentation it was noted that ancient mariners used the celestial sphere to navigate. The presentation was followed by on-deck observing sessions in which objects shown in the presentation were viewed with the naked eye, binoculars and a small telescope. The activity seemed to be well received and resulted in numerous questions to the presenter of the activity. Many people said that the activity had kindled or rekindled their interest in astronomy.

Analytical modeling and sensitivity analysis for travel time estimation on signalized urban networks

This paper presents a model for estimation of average travel time and its variability on signalized urban networks using cumulative plots. The plots are generated based on the availability of data: a) case-D, for detector data only; b) case-DS, for detector data and signal timings; and c) case-DSS, for detector data, signal timings and saturation flow rate. The performance of the model for different degrees of saturation and different detector detection intervals is consistent for case-DSS and case-DS whereas, for case-D the performance is inconsistent. The sensitivity analysis of the model for case-D indicates that it is sensitive to detection interval and signal timings within the interval. When detection interval is integral multiple of signal cycle then it has low accuracy and low reliability. Whereas, for detection interval around 1.5 times signal cycle both accuracy and reliability are high.

Getting that piece of paper : mental health nurses' experience of undertaking doctoral studies in Victoria, Australia

The aim of this study was to explore the experience of mental health nurses undertaking doctoral studies. The study was conducted in Victoria, Australia. A descriptive exploratory approach to inquiry was used for this study. Participants were mental health nurses who had successfully completed a doctoral qualification. Eligibility for inclusion required participants to be residing in Victoria (irrespective of where their doctoral studies were undertaken) and to have conducted their research within the domain of mental health and/or currently employed in the field of mental health nursing. Of the 20 potential participants invited, 16 accepted the invitation. Five emergent themes were explicated from narrative analyses. These themes were being a trail blazer, positioning for professional advancement, achieving a balance between competing priorities, maintaining a commitment to the development of the profession, and a point of affirmation. An understanding of the experience of undertaking doctoral studies can be used to influence the development of strategies to encourage more mental health nurses to consider undertaking a doctoral degree.

Oxford Companion to Australian Gardens [contributions: entries S-V]

Shelton, Edward Mason; p.548 Sherwood Arboretum; p.550 Soutter, William; pp.563-564 Styles or gardens and designed landscapes; pp.575-576 Summer-house; pp.579-580 Trapnell, Walter George; p.602 Tropical Gardens; pp.604-605 Wickham Park; p.642 Wijaya, Made; p.642 Williams, George; p.644 Williams, Keith A.W.; p.644 Verandah Garadening; p.614

Commitment issues in delegation process

Delegation is a powerful mechanism to provide flexible and dynamic access control decisions. Delegation is particularly useful in federated environments where multiple systems, with their own security autonomy, are connected under one common federation. Although many delegation schemes have been studied, current models do not seriously take into account the issue of delegation commitment of the involved parties. In order to address this issue, this paper introduces a new mechanism to help parties involved in the delegation process to express commitment constraints, perform the commitments and track the committed actions. This mechanism looks at two different aspects: pre-delegation commitment and post-delegation commitment. In pre-delegation commitment, this mechanism enables the involved parties to express the delegation constraints and address those constraints. The post-delegation commitment phase enables those parties to inform the delegator and service providers how the commitments are conducted. This mechanism utilises a modified SAML assertion structure to support the proposed delegation and constraint approach.

New insights into Crustal Contributions to Large-volume Rhyolite Generation in the Mid-Tertiary Sierra Madre Occidental Province, Mexico, revealed by U Pb Geochronology

Voluminous (≥3·9 × 105 km3), prolonged (∼18 Myr) explosive silicic volcanism makes the mid-Tertiary Sierra Madre Occidental province of Mexico one of the largest intact silicic volcanic provinces known. Previous models have proposed an assimilation–fractional crystallization origin for the rhyolites involving closed-system fractional crystallization from crustally contaminated andesitic parental magmas, with <20% crustal contributions. The lack of isotopic variation among the lower crustal xenoliths inferred to represent the crustal contaminants and coeval Sierra Madre Occidental rhyolite and basaltic andesite to andesite volcanic rocks has constrained interpretations for larger crustal contributions. Here, we use zircon age populations as probes to assess crustal involvement in Sierra Madre Occidental silicic magmatism. Laser ablation-inductively coupled plasma-mass spectrometry analyses of zircons from rhyolitic ignimbrites from the northeastern and southwestern sectors of the province yield U–Pb ages that show significant age discrepancies of 1–4 Myr compared with previously determined K/Ar and 40Ar/39Ar ages from the same ignimbrites; the age differences are greater than the errors attributable to analytical uncertainty. Zircon xenocrysts with new overgrowths in the Late Eocene to earliest Oligocene rhyolite ignimbrites from the northeastern sector provide direct evidence for some involvement of Proterozoic crustal materials, and, potentially more importantly, the derivation of zircon from Mesozoic and Eocene age, isotopically primitive, subduction-related igneous basement. The youngest rhyolitic ignimbrites from the southwestern sector show even stronger evidence for inheritance in the age spectra, but lack old inherited zircon (i.e. Eocene or older). Instead, these Early Miocene ignimbrites are dominated by antecrystic zircons, representing >33 to ∼100% of the dated population; most antecrysts range in age between ∼20 and 32 Ma. A sub-population of the antecrystic zircons is chemically distinct in terms of their high U (>1000 ppm to 1·3 wt %) and heavy REE contents; these are not present in the Oligocene ignimbrites in the northeastern sector of the Sierra Madre Occidental. The combination of antecryst zircon U–Pb ages and chemistry suggests that much of the zircon in the youngest rhyolites was derived by remelting of partially molten to solidified igneous rocks formed during preceding phases of Sierra Madre Occidental volcanism. Strong Zr undersaturation, and estimations for very rapid dissolution rates of entrained zircons, preclude coeval mafic magmas being parental to the rhyolite magmas by a process of lower crustal assimilation followed by closed-system crystal fractionation as interpreted in previous studies of the Sierra Madre Occidental rhyolites. Mafic magmas were more probably important in providing a long-lived heat and material flux into the crust, resulting in the remelting and recycling of older crust and newly formed igneous materials related to Sierra Madre Occidental magmatism.

The Brisbane Cordon scheme : part A - preliminary investigation

It could be said that road congestion is one of the most significant problems within any modern metropolitan area. For several decades now, around the globe, congestion in metropolitan areas has been worsening for two main reasons. Firstly, road congestion has significantly increased due to a higher demand for road space because of growth in populations, economic activity and incomes (Hensher & Puckett, 2007). This factor, in conjunction with a significant lack of investment in new road and public transport infrastructure, has seen the road network capacities of cities exceeded by traffic volumes and thus, resulted in increased traffic congestion. This relentless increase in road traffic congestion has resulted in a dramatic increase in costs for both the road users and ultimately the metropolitan areas concerned (Bureau of Transport and Regional Economics, 2007). In response to this issue, several major cities around the world, including London, Stockholm and Singapore, have implemented congestion-charging schemes in order to combat the effects of road congestion. A congestion-charging scheme provides a mechanism for regulating traffic flows into the congested areas of a city, whilst simultaneously generating public revenue that can be used to improve both the public transport and road networks of the region. The aim of this paper was to assess the concept of congestion-charging, whilst reflecting on the experiences of various cities that have already implemented such systems. The findings from this paper have been used to inform the design of a congestion-charging scheme for the city of Brisbane in Australia in a supplementary study (Whitehead, Bunker, & Chung, 2011). The first section of this paper examines the background to road congestion; the theory behind different congestion-charging schemes; and the various technologies involved with the concept. The second section of this paper details the experiences, in relation to implementing a congestion-charging scheme, from the city of Stockholm in Sweden. This research has been crucial in forming a list of recommendations and lessons learnt for the design of a congestion-charging scheme in Australia. It is these recommendations that directly inform the proposed design of the Brisbane Cordon Scheme detailed in Whitehead et al. (2011).