SEAGRID: A New Dynamic Modelling Tool for Power System Analysis of Ocean Energy Devices

International audienceAs the ocean energy industry approaches commercial readiness, there will be a greater focus on integration of ocean energy devices (OEDs) into the electrical power system network. Device developers will be required to provide dynamic models of their device for grid connection, and ensure their device operates within the limits laid out in the grid code. Project developers will need to assess the impact of different wavefarm configurations, ratings for the electrical equipment, power losses, and performance during a fault. Grid operators will require dynamic models to investigate the impact an OED will have on the grid and also for future grid planning studies. The SEAGRID dynamic modelling tool attempts to address each of these issues using its generic modelling approach. The SEAGRID model is capable of producing a scalable time domain power system dynamic model using empirical test data and component specifications, bypassing the need for a full hydrodynamic study of the device

Generic Dynamic Modelling for Grid Integration of Ocean Energy Devices

International audienceAs ocean wave and tidal stream technologies approach commercial readiness, grid operators need to assess the impact a wave or tidal device will have on the electrical grid under both normal and fault conditions. In order to achieve this, it will be necessary for each device developer to supply dynamic models of their device to the grid operator. A generic modelling approach is proposed to facilitate the integration of ocean energy devices into the electrical grid, from the perspective of both device developers and grid operators. This paper outlines issues surrounding dynamic modelling for ocean energy devices, and proposes a generic model structure based on data obtained from a recent survey of device developers. The proposed model structure would simulate the power flow through a device using generic parameters which can be obtained from empirical test data and equipment specifications

‘The Rest is Silence’:Psychogeography, Soundscape and Nostalgia in Pat Collins’ Silence

Guy Debord defines the term psychogeography as 'the study of the precise laws and specific effects of the geographical environment, consciously organised or not, on the emotions and behaviour of individuals' (Debord 1955: 23). Similar to the belief of psychogeographers that the geography of an environment has a psychological effect on the human mind, proponents of acoustic ecology such as R. Murray Schafer hold that humans are affected by the sound of the environment in which they find themselves. Further to this, they examine the extent to which soundscapes can be shaped by human behaviour. Recently a body of Irish films has emerged that directly engages with the Irish soundscape and landscape on a psychogeographical level. Rather than using landscape as a physical space for the locus of action, these representations of the Irish landscape allow for an engagement with the aesthetic effects of the geographical landscape as a reflection of the psychological states of the protagonists. Bearing this in mind, this article examines how Silence (Collins 2012) arguably demonstrates the most overt and conscious incursion into this area to date. It specifically interrogates how the filmic representation of the psychogeography and soundscape of the Irish rural landscape can serve to express emotion, alienation and nostalgia, thus confronting both the Irish landscape and the weight of its associated history

Diversity of Methicillin-Resistant Staphylococcus aureus (MRSA) Strains Isolated from Inpatients of 30 Hospitals in Orange County, California

There is a need for a regional assessment of the frequency and diversity of MRSA to determine major circulating clones and the extent to which community and healthcare MRSA reservoirs have mixed. We conducted a prospective cohort study of inpatients in Orange County, California, systematically collecting clinical MRSA isolates from 30 hospitals, to assess MRSA diversity and distribution. All isolates were characterized by spa typing, with selective PFGE and MLST to relate spa types with major MRSA clones. We collected 2,246 MRSA isolates from hospital inpatients. This translated to 91/10,000 inpatients with MRSA and an Orange County population estimate of MRSA inpatient clinical cultures of 86/100,000 people. spa type genetic diversity was heterogeneous between hospitals, and relatively high overall (72%). USA300 (t008/ST8), USA100 (t002/ST5) and a previously reported USA100 variant (t242/ST5) were the dominant clones across all Orange County hospitals, representing 83% of isolates. Fifteen hospitals isolated more t008 (USA300) isolates than t002/242 (USA100) isolates, and 12 hospitals isolated more t242 isolates than t002 isolates. The majority of isolates were imported into hospitals. Community-based infection control strategies may still be helpful in stemming the influx of traditionally community-associated strains, particularly USA300, into the healthcare setting. © 2013 Hudson et al

Interpretation of VHF radar echoes from a complex flow field

Bragg lines on spectra from ocean radar systems are broadened when echoes come into the antenna from different azimuths. Phased-array systems minimise the effects of this by selecting a small target area on the sea surface by beam-forming and range-gating. While phased array systems are better conditioned for high spatial resolution than direction finding systems, in some cases there may be fine structure in the surface current field within the smallest of target areas. In estuaries or other areas where there are sand banks and low islands there is potential for contamination from side-lobes of phased array antennas to contaminate adjacent pixels. This paper uses data from an area of highly complex flow field in Dingle Bay, Ireland to examine the complex structure of Bragg echoes. A numerical hydrodynamic model is used as an aid in understanding the degree of structure to be expected in the Bragg lines, and an improved analysis is described to extract surface current data from the radar echoes

Is UV ornamentation an amplifier in swordtails

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