A simple hourly wind power simulation for the South-West region of Western Australia using MERRA data

A simple simulator capable of generating synthetic hourly values of wind power was developed for the South West region of Western Australia. The global Modern Era Retrospective Analysis for Research and Applications (MERRA) atmospheric database was used to calibrate the simulation with wind speeds 50m above ground level. Analysis of the MERRA data indicated that the normalised residual of hourly wind speed had a double exponential distribution. A translated square-root transformation function yn=(√(1.96+ ye )−1.4)/0.302 was used to convert this to a normal-like distribution so that autoregressive (AR) time series analysis could be used. There was a significant dependency in this time series on the last three hours, so a third order AR model was used to generate hourly 50m wind speed residuals. The MERRA daily average 50m wind speed was found to have a Weibull-like distribution, so a square root conversion was used on the data to obtain a normal distribution. The time series for this distribution was found to have a significant dependency on the values for the last two days, so a second order AR model was also used in the simulation to generate synthetic time series values for the square root of the daily average wind speed. Seasonal, daily, diurnal, and hourly components were added to generate synthetic time series values of total 50m wind speed. To scale this wind speed to turbine hub height, a time varying wind shear factor model was created and calibrated using measured data at a coastal and an inland site. Standard wind turbine power curves were modified to produce an estimate of wind farm power output from the hub-height wind speed. Comparison with measured grid supervisory control and data acquisition (SCADA) data indicated that the simulation generated conservative power output values. The simulation was compared to two other models: a Weibull distribution model, and an AR model with normally distributed residuals. The statistical fit with the SCADA data was found to be closer than these two models. Spatial correlation using only the MERRA data was found to be higher than the SCADA data, indicating that there is still a further source of variability to be accounted for. Hence the simulation spatial correlation was calibrated to previously reported findings, which were similar to the SCADA data

A large-scale renewable electricity supply system by 2030: Solar, wind, energy efficiency, storage and inertia for the South West Interconnected System (SWIS) in Western Australia

An interactive web tool was created to simulate 100% renewable electricity supply scenarios for the South-West Interconnected System (SWIS) in the south-west of Western Australia. The SWIS is isolated from other grids and currently has no available hydropower. Hence it makes a good case study of how supply and demand might be balanced on an hour-by-hour basis and grid stability maintained without the benefit of energy import/export or pumped hydroelectric storage. The tool included regional models for wind and solar power, so that hypothetical power stations were not confined to sites with existing wind farms or solar power stations, or sites with measurements of wind speed and solar radiation. A generic model for solar thermal storage and simple models for energy efficiency, distributed battery storage and power to gas storage were also developed. Due to the urgency of climate change mitigation a rapid construction schedule of completion by 2030, rather than the more common target of 2050, was set. A scenario with high wind generation, and scenarios with varying levels of solar power, wind power, distributed battery storage, energy efficiency improvements and power to gas systems were considered. The battery storage system and PV arrays were configured to provide synthetic inertia to maintain grid stability (with a small loss in capacity for each), and existing synchronous generators were kept spinning with no fuel input, adding a small increase to the electrical load demand. The level of synthetic inertia provided by battery storage was estimated for each scenario. The results indicated that a balanced mix of solar PV, solar thermal, efficiency, and storage were the most feasible to be built on a rapid time scale. The required capacity and build rate of the generation and storage systems would be reduced if energy efficiency improvements were implemented on a more rapid schedule compared to the current global improvement rate. The scenario with very high levels of wind power (∼80% generation) were found to be capable of meeting SWIS reliability criteria if very large amounts of distributed storage or some high capacity seasonal reserve generation system such as power to gas were present. High levels of battery storage capacity and efficiency improvement could be as effective as a power to gas system. It was confirmed that all scenarios provided the same or greater levels of inertia than presently provided by conventional generators. This tool showed that it is possible to examine renewable energy scenarios for regional electricity networks without high computing power

Understanding the biomechanical “spread” of joint pain: knee pain predicts subsequent shoulder pain and this is mediated by leg weakness. Data from the osteoarthritis initiative

Joint pain is common in older adults; typically multiple joints are involved. A greater number of painful sites is associated with higher levels of pain intensity in affected joints, more functional impairment and poorer quality of life. However, little is known about the pattern of multi-site joint pain development. We aimed to assess whether the number of painful joints increases over time, whether pain in certain joints precedes pain in others, and to assess whether the association is mediated by weakness in a cohort of older adults with painful knee osteoarthritis or at risk of knee osteoarthritis in the NIH Osteoarthritis Initiative (OAI)

Finite temperature stability and dimensional crossover of exotic superfluidity in lattices

We investigate exotic paired states of spin-imbalanced Fermi gases in anisotropic lattices, tuning the dimension between one and three. We calculate the finite temperature phase diagram of the system using real-space dynamical mean-field theory in combination with the quantum Monte Carlo method. We find that regardless of the intermediate dimensions examined, the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state survives to reach about one third of the BCS critical temperature of the spin-density balanced case. We show how the gapless nature of the state found is reflected in the local spectral function. While the FFLO state is found at a wide range of polarizations at low temperatures across the dimensional crossover, with increasing temperature we find out strongly dimensionality-dependent melting characteristics of shell structures related to harmonic confinement. Moreover, we show that intermediate dimension can help to stabilize an extremely uniform finite temperature FFLO state despite the presence of harmonic confinement.Comment: 5 pages, 3 figure

Research methods for subgrouping low back pain

<p>Abstract</p> <p>Background</p> <p>There is considerable clinician and researcher interest in whether the outcomes for patients with low back pain, and the efficiency of the health systems that treat them, can be improved by 'subgrouping research'. Subgrouping research seeks to identify subgroups of people who have clinically important distinctions in their treatment needs or prognoses. Due to a proliferation of research methods and variability in how subgrouping results are interpreted, it is timely to open discussion regarding a conceptual framework for the research designs and statistical methods available for subgrouping studies (a method framework). The aims of this debate article are: (1) to present a method framework to inform the design and evaluation of subgrouping research in low back pain, (2) to describe method options when investigating prognostic effects or subgroup treatment effects, and (3) to discuss the strengths and limitations of research methods suitable for the hypothesis-setting phase of subgroup studies.</p> <p>Discussion</p> <p>The proposed method framework proposes six phases for studies of subgroups: studies of assessment methods, hypothesis-setting studies, hypothesis-testing studies, narrow validation studies, broad validation studies, and impact analysis studies. This framework extends and relabels a classification system previously proposed by McGinn et al (2000) as suitable for studies of clinical prediction rules. This extended classification, and its descriptive terms, explicitly anchor research findings to the type of evidence each provides. The inclusive nature of the framework invites appropriate consideration of the results of diverse research designs. Method pathways are described for studies designed to test and quantify prognostic effects or subgroup treatment effects, and examples are discussed. The proposed method framework is presented as a roadmap for conversation amongst researchers and clinicians who plan, stage and perform subgrouping research.</p> <p>Summary</p> <p>This article proposes a research method framework for studies of subgroups in low back pain. Research designs and statistical methods appropriate for sequential phases in this research are discussed, with an emphasis on those suitable for hypothesis-setting studies of subgroups of people seeking care.</p

Education and older adults at the University of the Third Age

This article reports a critical analysis of older adult education in Malta. In educational gerontology, a critical perspective demands the exposure of how relations of power and inequality, in their myriad forms, combinations, and complexities, are manifest in late-life learning initiatives. Fieldwork conducted at the University of the Third Age (UTA) in Malta uncovered the political nature of elder-learning, especially with respect to three intersecting lines of inequality - namely, positive aging, elitism, and gender. A cautionary note is, therefore, warranted at the dominant positive interpretations of UTAs since late-life learning, as any other education activity, is not politically neutral.peer-reviewe

Why equality? On justifying liberal egalitarianism

The debate over the nature of egalitarianism has come to dominate political philosophy. As ever more sophisticated attempts are made to describe the principles of an egalitarian distribution or to specify the good or goods that should be distributed equally, little is said about the fundamental basis of equality. In virtue of what should people be regarded as equal? Egalitarians have tended to dismiss this question of fundamental equality. In the first part of the paper I will examine some of these strategies of marginalisation and assess whether the issue of fundamental equality matters. Jeremy Waldron has criticised this strategy of avoidance in his recent book God, Locke and equality. He argues that Locke's turn to a theistic grounding for fundamental equality provides a better approach to the problem than the approach taken by contemporary liberals such as John Rawls. I will examine Waldron's critique of Rawls and show that it is wanting. I will conclude by suggesting that Rawls's approach to the issue has a bearing on the way in which equality should be understood as a political value. This argument for the primacy of a political conception of egalitarianism has a bearing on the interconnection between core liberal values and the idea of the state that has been emphasised by Rawls, Dworkin and Nagel

Complete mitochondrial genomes and nuclear ribosomal RNA operons of two species of Diplostomum (Platyhelminthes: Trematoda): a molecular resource for taxonomy and molecular epidemiology of important fish pathogens

© 2015 Brabec et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article

Evolutionary Analysis of Mitogenomes from Parasitic and Free-Living Flatworms

Copyright: © 2015 Solà et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article