Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract: Power converter reliability is critical for permanent magnet synchronous generator (PMSG) wind turbines. Converter failures are linked to power module thermal loading but studies often neglect turbine dynamics, control and the impact of wind speed sampling rate on lifetime estimation. This paper addresses this using a 2MW direct-drive PMSG wind turbine model with a 2-level converter, and simulating junction temperatures (T j ) using a power module thermal equivalent circuit under various synthetic wind speed conditions. These synthetic wind conditions include constant and square wave profiles representing stable and gusty wind conditions. Responses to square wave wind speeds showed that the lower the gust frequency, the higher ∆T j becomes, demonstrating that low turbulence sites have greater thermal variation in the converter. In contrast, wind speed variations with frequencies greater than 0.25Hz deliver only small increases in ∆T j . It is concluded that reasonable approximations of T j profiles can be made with 0.25Hz wind speed data, but that lower data rate wind measurements miss essential, damaging characteristics.
Nothing has so characterized the British School at Rome's approach, from its inception, as the commitment to landscape archaeology in one form or another. This paper discusses the origins of this commitment in the work of Thomas Ashby, but focuses on the major contribution of J.B. Ward-Perkins and the South Etruria Survey. This survey is set in the context both of intellectual developments in landscape archaeology, and the specific circumstances of the BSR, and its Director, after the Second World War. The article traces the impact of this work on subsequent landscape archaeology.
The gens, a key social formation in archaic Rome, has given rise to considerable interpretative problems for modern scholarship. In this comprehensive exploration of the subject, Professor Smith examines the mismatch between the ancient evidence and modern interpretative models influenced by social anthropology and political theory. He offers a detailed comparison of the gens with the Attic genos and illustrates, for the first time, how recent changes in the way we understand the genos may impact upon our understanding of Roman history. He develops a concept of the gens within the interlocking communal institutions of early Rome, which touches on questions of land ownership, warfare and the patriciate, before offering an explanation of the role of the gens and the part it might play in modern political theory. This significant work makes an important contribution not only to the study of archaic Rome, but also to the history of ideas.
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