The 230 V CBEMA curve - Preliminary studies

The ITI, formerly CBEMA, curve was developed by the Information Technology Industry Council of the United States of America. The curve describes an AC input voltage envelope which typically can be tolerated by most Information Technology (IT) Equipment. Although the curve ostensibly applies only to IT equipment it is often used throughout the electricity supply industry to provide an indication of the input voltage tolerance of a wide range of equipment. In spite of the fact that the curve was designed to apply to equipment supplied at 120 V 60 Hz nominal voltages it is widely used in Australia which has a 230 V 50 Hz system. This paper details a preliminary study aimed at developing a CBEMA style curve to suit Australian conditions. A range of domestic equipment has been tested to determine sag susceptibility. The types of equipment tested are not limited to IT equipment and represent a cross section of appliances likely to be found in most homes. Overall, results for domestic appliances show that equipment connected to the Australian 230 V network has sag immunity considerably greater than that defined by the ITI Curve. As such, the applicability of the curve for individual pieces of equipment connected to Australian 230 V electricity networks is highly questionable and the need for further work in this area is apparent

The electrical performance of modern compact fluorescent lamps

Compact Fluorescent Lamps (CFL) are highly non-linear devices which are likely to experience very high growth in penetration levels, especially in domestic environments, in Australia over the next 2 – 3 years. This will occur due to the decision taken by the Australian Federal Government to ban the sale of incandescent light globes after 2009 as measures towards meeting the needs for demand side management and climate change abatement. While CFL technology has been in existence since the late 1980s penetration levels are now increasing to a point where the total CFL load cannot be considered negligible compared to other non-linear domestic loads. This paper seeks to redress the lack of concise data available describing the performance of modern CFLs over a range of influence factors such as input voltage magnitude and harmonic distortion. It seeks to provide definitive characterisation of the modern CFL in terms of harmonic and power factor performance over a range of input supply conditions. This aim is achieved through laboratory testing of 25 CFLs of different brands, construction types and rated power levels

Narcolepsy and Cataplexy – a practical approach to diagnosis and managing the impact of this chronic condition on children and their families

Narcolepsy is a relatively common neurological condition affecting the regulation of normal sleep/wake cycles leading to excessive daytime sleepiness (EDS). It is almost certainly under-recognised as it has a prevalence of 20–50 per 100,000 population and most cases have an onset in adolescence. Cataplexy (attacks of muscle weakness often precipitated by strong emotions) is a hallmark of this condition and represents the intrusion of REM sleep into wakefulness. Narcolepsy is caused by destruction of hypocretin producing cells due to an autoimmune process often by an infective trigger. Hypocretin is found in the hypothalamus and plays a role in stabilisation of the transition between wake and sleep states. In establishing a diagnosis a comprehensive history to exclude other causes of EDS, including poor sleep habits, is essential. Primary sleep related conditions such as sleep apnoea should be excluded. Investigations for confirmation of the diagnosis include Actigraphy, Polysomnography (PSG), Multiple Sleep Latency Testing (MSLT) and CSF analysis. The symptoms of this debilitating condition can have a huge impact on a child's life and are often vastly underestimated. The impact of EDS on cognitive function is an important factor in difficulties at school, mood, quality of life and future career opportunities. Advances in understanding the pathophysiology have led to trials of novel treatment approaches. The aim of this article is to briefly summarise the recent advances in understanding and give an overview of this important condition for those who are involved in the care of a child with this disease

Monitoring intelligent distribution power systems: a power quality plan

Power system monitoring capabilities and requirements are evolving rapidly. The traditional monitoring framework in Australian distribution networks involves biannual readings of maximum demand at each distribution substation. As utilities respond to developments in metering and communications technology, automated collection and retrieval of quasi-real-time system data between substations and central repositories is now feasible. This gives network managers a significantly increased understanding of distribution network dynamic activity such as daily and seasonal load profiles. This leads to the increased ability of utilities to exploit metering data for power quality analysis purposes. This paper examines the scope for, and challenges associated with, integration of power quality monitoring with advanced metering. Emphasis is directed towards technical and regulatory conditions applying to Australian distribution utilities. Particular consideration is given to the different characteristics of the various types of sites where monitoring is required

Order Parameter Equations for Front Transitions: Planar and Circular Fronts

Near a parity breaking front bifurcation, small perturbations may reverse the propagation direction of fronts. Often this results in nonsteady asymptotic motion such as breathing and domain breakup. Exploiting the time scale differences of an activator-inhibitor model and the proximity to the front bifurcation, we derive equations of motion for planar and circular fronts. The equations involve a translational degree of freedom and an order parameter describing transitions between left and right propagating fronts. Perturbations, such as a space dependent advective field or uniform curvature (axisymmetric spots), couple these two degrees of freedom. In both cases this leads to a transition from stationary to oscillating fronts as the parity breaking bifurcation is approached. For axisymmetric spots, two additional dynamic behaviors are found: rebound and collapse.Comment: 9 pages. Aric Hagberg: http://t7.lanl.gov/People/Aric/; Ehud Meron: http://www.bgu.ac.il/BIDR/research/staff/meron.htm

Four-phase patterns in forced oscillatory systems

We investigate pattern formation in self-oscillating systems forced by an external periodic perturbation. Experimental observations and numerical studies of reaction-diffusion systems and an analysis of an amplitude equation are presented. The oscillations in each of these systems entrain to rational multiples of the perturbation frequency for certain values of the forcing frequency and amplitude. We focus on the subharmonic resonant case where the system locks at one fourth the driving frequency, and four-phase rotating spiral patterns are observed at low forcing amplitudes. The spiral patterns are studied using an amplitude equation for periodically forced oscillating systems. The analysis predicts a bifurcation (with increasing forcing) from rotating four-phase spirals to standing two-phase patterns. This bifurcation is also found in periodically forced reaction-diffusion equations, the FitzHugh-Nagumo and Brusselator models, even far from the onset of oscillations where the amplitude equation analysis is not strictly valid. In a Belousov-Zhabotinsky chemical system periodically forced with light we also observe four-phase rotating spiral wave patterns. However, we have not observed the transition to standing two-phase patterns, possibly because with increasing light intensity the reaction kinetics become excitable rather than oscillatory.Comment: 11 page

Large Scale Proactive Power-Quality Monitoring: An Example from Australia

In Australia and many other countries, distribution network service providers (DNSPs) have an obligation to their customers to provide electrical power that is reliable and of high quality. Failure to do so may have significant implications ranging from financial penalties theoretically through to the loss of a license to distribute electricity. In order to ensure the reliability and quality of supply are met, DNSPs engage in monitoring and reporting practice. This paper provides an overview of a large long-running power-quality monitoring project that has involved most of Australia\u27s DNSPs at one time or another. This paper describes the challenges associated with conducting the project as well as some of the important outcomes and lessons learned. A number of novel reporting techniques that have been developed as part of the monitoring project are also presented. A discussion about large-volume data management, and issues related to reporting requirements in future distribution networks is included

Transcriptomic discovery and comparative analysis of neuropeptide precursors in sea cucumbers (Holothuroidea)

This research was supported by Agricultural Research Development Agency (Public Organization), Thailand

Stable periodic waves in coupled Kuramoto-Sivashinsky - Korteweg-de Vries equations

Periodic waves are investigated in a system composed of a Kuramoto-Sivashinsky - Korteweg-de Vries (KS-KdV) equation, which is linearly coupled to an extra linear dissipative equation. The model describes, e.g., a two-layer liquid film flowing down an inclined plane. It has been recently shown that the system supports stable solitary pulses. We demonstrate that a perturbation analysis, based on the balance equation for the field momentum, predicts the existence of stable cnoidal waves (CnWs) in the same system. It is found that the mean value U of the wave field u in the main subsystem, but not the mean value of the extra field, affects the stability of the periodic waves. Three different areas can be distinguished inside the stability region in the parameter plane (L,U), where L is the wave's period. In these areas, stable are, respectively, CnWs with positive velocity, constant solutions, and CnWs with negative velocity. Multistability, i.e., the coexistence of several attractors, including the waves with several maxima per period, appears at large value of L. The analytical predictions are completely confirmed by direct simulations. Stable waves are also found numerically in the limit of vanishing dispersion, when the KS-KdV equation goes over into the KS one.Comment: a latex text file and 16 eps files with figures. Journal of the Physical Society of Japan, in pres

Is Thermal Instability Significant in Turbulent Galactic Gas?

We investigate numerically the role of thermal instability (TI) as a generator of density structures in the interstellar medium (ISM), both by itself and in the context of a globally turbulent medium. Simulations of the instability alone show that the condenstion process which forms a dense phase (``clouds'') is highly dynamical, and that the boundaries of the clouds are accretion shocks, rather than static density discontinuities. The density histograms (PDFs) of these runs exhibit either bimodal shapes or a single peak at low densities plus a slope change at high densities. Final static situations may be established, but the equilibrium is very fragile: small density fluctuations in the warm phase require large variations in the density of the cold phase, probably inducing shocks into the clouds. This result suggests that such configurations are highly unlikely. Simulations including turbulent forcing show that large- scale forcing is incapable of erasing the signature of the TI in the density PDFs, but small-scale, stellar-like forcing causes erasure of the signature of the instability. However, these simulations do not reach stationary regimes, TI driving an ever-increasing star formation rate. Simulations including magnetic fields, self-gravity and the Coriolis force show no significant difference between the PDFs of stable and unstable cases, and reach stationary regimes, suggesting that the combination of the stellar forcing and the extra effective pressure provided by the magnetic field and the Coriolis force overwhelm TI as a density-structure generator in the ISM. We emphasize that a multi-modal temperature PDF is not necessarily an indication of a multi-phase medium, which must contain clearly distinct thermal equilibrium phases.Comment: 18 pages, 11 figures. Submitted to Ap