Mediated Cognition: Information Technologies and the Sciences of Mind

This dissertation investigates the interconnections between minds, media, and the cognitive sciences. It asks what it means for media to have effects upon the mind: do our tools influence the ways that we think? It considers what scientific evidence can be brought to bear on the question: how can we know and measure these effects? Ultimately, it looks to the looping pathways by which science employs technological media in understanding the mind, and the public comes to understand and respond to these scientific discourses. I contend that like human cognition itself, the enterprise of cognitive science is a deeply and distinctively mediated phenomenon. This casts a different light on contemporary debates about whether television, computers, or the Internet are changing our brains, for better or for worse. Rather than imagining media effects as befalling a fictive natural mind, I draw on multiple disciplines to situate mind and the sciences thereof as shaped from their origins through interaction with technology. Our task is then to interrogate the forms of cognition and attention fostered by different media, alongside their attendant costs and benefits. The first chapter positions this dissertation between the fields of media studies and STS, developing a case for the reality of media effects without the implication of technological determinism. The second considers the history of technological metaphor in scientific characterizations of the mind. The third section consists of three separate chapters on the history of cognitive science, presenting the core of my case for its uniquely mediated character. Across three distinct eras, what unifies cognitive science is the quest to understand the mind using computational systems, operating by turns as generative metaphors and tangible models. I then evaluate the contemporary cognitive-scientific research on the question of media effects, and the growing role of electronic media in science. My fifth and final section develops a content analysis: what is said in the media about the popular theory that media themselves, in one way or another, are causing attention deficit disorders? The work concludes with a summary and some reflections on mind, culture, technoscience and markets as recursively interwoven causal systems

Reliability comparison of wind turbines with DFIG and PMG drive trains

Modern wind turbines vary greatly in their drive train configurations. With the variety of options available, it can be difficult to determine which type is most suitable for on and offshore applications. A large percentage of modern drive trains consist of either doubly fed induction generators with partially rated converters or permanent magnet generators with fully rated converters. These configurations are the focus of this empirical reliability comparison. The turbine population for this analysis contains over 1800 doubly fed induction generators, partially rated converter wind turbines, and 400 permanent magnet generator fully rated converter wind turbines. The turbines analyzed are identical except for their drive train configurations and are modern MW scale turbines making this population the largest and most modern encountered in the literature review. Results of the analysis include overall failure rates, failure rates per operational year, failure rates per failure mode, and failure rates per failure cost category for the two drive train configurations. These results contribute toward deciding on the most suitable turbine type for a particular site, as well as toward cost of energy comparisons for different drive train types. A comparison between failure rates from this analysis and failure rates from similar analyses is also shown in this paper

Quantifying O&M savings and availability improvements from wind turbine design for maintenance techniques

Design for maintenance has the potential to significantly reduce the cost of offshore wind energy. This paper shows the results of an O&M cost and availability analysis when different design for maintenance techniques are applied to wind turbines. The design for maintenance techniques considered, reduce repair times and the need for jack up vessels as well as introducing redundancy to the power train of the wind turbines. A detailed lifetime O&M cost and availability model is used in this analysis and populated with empirical operational and cost data from a population of ~350 offshore wind turbines from between 5 and 10 offshore wind farms throughout Europe. A base line availability and O&M cost per MWh are obtained from the model and input data, these inputs are then adjusted based on different design for maintenance techniques. The subsequent outputs from the model using the adjusted inputs allow for the quantification of O&M savings and availability improvements for the different design for maintenance techniques. These design for maintenance techniques may have different effects on different wind turbine types. As a means of investigating this, a comparison of the O&M saving and availability improvements will be carried out for both a DFIG turbine type and a PMG FRC turbine type. For a hypothetical site located 50km offshore using a verified O&M model and empirical operational and cost data this paper shows that the overall combination of these improvements reduces the total O&M cost by ~16% for the DFIG and ~17% for the PMG FRC. It also shows that in both turbine types the largest reduction in O&M costs are seen to come from the elimination of the need for heavy lifting vessels

Availability improvements from condition monitoring systems and performance based maintenance contracts

Condition monitoring systems and performance based maintenance contracts have the potential to significantly reduce the cost of energy (CoE) for offshore wind turbines. This paper describes the condition monitoring systems (CMS) available for offshore wind turbines. It details how CMS can be used in condition based maintenance (CBM) strategies and discusses the advantages and disadvantages of using CBM strategies over time based maintenance (TBM) strategies. The paper also provides and compares the results from an empirical availability analysis on an offshore wind turbine population that has condition monitoring systems and a population that does not. Based on the comparison of these results conclusions are drawn on the value added by condition monitoring systems. This paper also focuses on performance based maintenance contracts (PBMC) and provides an overview of what performance based contracts are currently on offer and what guarantees they provide. An empirical availability analysis is also carried out on a population of offshore wind turbines with performance based maintenance contracts and a population without. These results are then compared and conclusions are drawn on how much value PBMCs add. These analyses show that offshore wind turbines that utilise CMS have on average ~4% higher availability per year and the population with PBMCs showed an availability ~2.5% higher than the population without

Offshore wind turbine sub-assembly failure rates through time

O&M costs can make up to 30% of the lifetime CoE of an offshore wind farm [1]. As a means of reducing this cost operators and O&M providers need a greater understanding of what is driving that O&M cost. Failure rates of wind turbines and their components are a key driver of O&M costs. Past papers have modelled O&M costs assuming a fixed average failure rate for wind turbine subsystems [2]. This work aims to determine if it is accurate to assume a fixed failure rate or if a failure rate distribution through time can be provided to allow for more accurate O&M cost modelling and in turn CoE modelling. This paper shows the results of an analysis of offshore wind turbine annual failure rates over an 8 year period. The analysis is based on around 350 modern multi MW offshore turbines located in 5-10 offshore wind farms throughout Europe. The literature review for this paper indicated that a constant average failure rate should only be used if the shape parameter of the failure distribution is around 1. However results from the failure rate analysis in this paper have shown that in many cases a constant failure rate is not correct for O&M Modelling

Availability, operation & maintenance costs of offshore wind turbines with different drive train configurations

Different configurations of gearbox, generator and power converter exist for offshore wind turbines. This paper investigated the performance of four prominent drive train configurations over a range of sites distinguished by their distance to shore. Failure rate data from onshore and offshore wind turbine populations was used where available or systematically estimated where no data was available. This was inputted along with repair resource requirements to an offshore accessibility and operation and maintenance model to calculate availability and operation and maintenance costs for a baseline wind farm consisting of 100 turbines. The results predicted that turbines with a permanent magnet generator and a fully rated power converter will have a higher availability and lower operation and maintenance costs than turbines with doubly-fed induction generators. This held true for all sites in this analysis. It was also predicted that in turbines with a permanent magnet generator, the direct drive configuration has the highest availability and lowest operation and maintenance costs followed by the turbines with 2 stage and 3 stage gearboxes

Limiting wave conditions for the safe maintenance of floating wind turbines

This paper investigates the limiting wave conditions at which a wind turbine technician can complete maintenance activities safely and effectively on a 15MW floating offshore wind turbine. Through linear, frequency-domain statistical analysis of floating turbine motion and applying acceptable motion limits for technician working, significant wave height and peak wave period limits are investigated. It was found that over the range of wave conditions considered, the turbine nacelle motion did not exceed the motion limits for technician working considered in this analysis. Further analysis found that the turbine nacelle motion increased with increasing significant wave height and was also significantly influenced by peak wave period. The impact of differing wave characteristics is also investigated through the use of different wave energy spectra and also found to have an impact on turbine nacelle motion

Cost of energy for offshore wind turbines with different drive train types

Drive train configurations differ in many of the modern MW scale wind turbines available. These differences occur from manufacturer to manufacturer and even within a single manufactures own portfolio. The wind energy industry aims to reduce the cost of ene rgy (CoE) for offshore wind turbines to make it cost competitive with ot her forms of energy generation (gas, coal, onshore wind etc.) This paper aims to assist with t hat CoE reduction by modelling four wind turbine types with different drive trains to dete rmine which turbine type offers the lowest CoE