2 resultados para metropolitan cities

em CORA - Cork Open Research Archive - University College Cork - Ireland


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The increased emphasis within Europe on the role of second-tier cities has implications for the ways in which these urban centres are considered within national spatial planning strategies. In centralised, monocentric states like Ireland, there has been a general ambivalence towards urban policy for cities outside the capital city, and historically this has prevented the development of a strong, diversified urban hierarchy undermining prospects for balanced regional development. This paper examines the extent to which a new found emphasis on Ireland’s second-tier cities which emerged in the ‘Gateways’ policy of the National Spatial Strategy (NSS, 2002) was matched by subsequent political and administrative commitment to facilitate the development of these urban centres. Following a discussion of the position of second-tier cities in an international context and a brief overview of recent demographic and economic trends, the paper assesses the relative performance of Ireland’s second-tier cities in influencing development trends, highlighting a comprehensive failure to deliver compact urban growth. In this context, the paper then discusses the implications of current development plans for the second-tier cities and proposals for Irish local government reform for securing compact urban development.

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The development of ultra high speed (~20 Gsamples/s) analogue to digital converters (ADCs), and the delayed deployment of 40 Gbit/s transmission due to the economic downturn, has stimulated the investigation of digital signal processing (DSP) techniques for compensation of optical transmission impairments. In the future, DSP will offer an entire suite of tools to compensate for optical impairments and facilitate the use of advanced modulation formats. Chromatic dispersion is a very significant impairment for high speed optical transmission. This thesis investigates a novel electronic method of dispersion compensation which allows for cost-effective accurate detection of the amplitude and phase of the optical field into the radio frequency domain. The first electronic dispersion compensation (EDC) schemes accessed only the amplitude information using square law detection and achieved an increase in transmission distances. This thesis presents a method by using a frequency sensitive filter to estimate the phase of the received optical field and, in conjunction with the amplitude information, the entire field can be digitised using ADCs. This allows DSP technologies to take the next step in optical communications without requiring complex coherent detection. This is of particular of interest in metropolitan area networks. The full-field receiver investigated requires only an additional asymmetrical Mach-Zehnder interferometer and balanced photodiode to achieve a 50% increase in EDC reach compared to amplitude only detection.