19 resultados para transportation routing

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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Much of the interest in sustainable cities relates to the inexorable rise in the demand for car travel and the contribution that certain urban forms and land-use relationships can make to reducing energy consumption. Indeed, this demand is fuelled more by increased spatial separation of homes and workplaces, shops and schools than by any rise in trip making. This paper evaluates recent efforts to integrate land-use planning and transportation policy in the Belfast Metropolitan Area by reviewing the policy formulation process at both a regional and city scale. The paper suggests that considerable progress has been made in integrating these two areas of public policy, both institutionally and conceptually. However, concerns are expressed that the rhetoric of sustainability may prove difficult to translate into implementation, leading to a further dislocation of land-use and transportation.

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Much of the interest in promoting sustainable development in planning for the city-region focuses on the apparently inexorable rise in the demand for car travel and the contribution that certain urban forms and land-use relationships can make to reducing energy consumption. Within this context, policy prescription has increasingly favoured a compact city approach with increasing urban residential densities to address the physical separation of daily activities and the resultant dependency on the private car. This paper aims to outline and evaluate recent efforts to integrate land use and transport policy in the Belfast Metropolitan Area in Northern Ireland. Although considerable progress has been made, this paper underlines the extent of existing car dependency in the metropolitan area and prevailing negative attitudes to public transport, and argues that although there is a rhetorical support for the principles of sustainability and the practice of land-use/transportation integration, this is combined with a selective reluctance to embrace local changes in residential environment or in lifestyle preferences which might facilitate such principles.

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Salt weathering is a crucial process that brings about a change in stone, from the scale of landscapes to stone outcrops and natural building stone facades. It is acknowledged that salt weathering is controlled by fluctuations in temperature and moisture, where repeated oscillations in these parameters can cause re-crystallisation, hydration/de-hydration of salts, bringing about stone surface loss in the form of, for example, granular disaggregation, scaling, and multiple flaking. However, this ‘traditional’ view of how salt weathering proceeds may need to be re-evaluated in the light of current and future climatic trends. Indeed, there is considerable scope for the investigation of consequences of climate change on geomorphological processes in general. Building on contemporary research on the ‘deep wetting’ of natural building stones, it is proposed that (as stone may be wetter for longer), ion diffusion may become a more prominent mechanism for the mixing of molecular constituents, and a shift in focus from physical damage to chemical change is suggested. Data from ion diffusion cell experiments are presented for three different sandstone types, demonstrating that salts may diffuse through porous stone relatively rapidly (in comparison to, for example, dense concrete). Pore water from stones undergoing diffusion experiments was extracted and analysed. Factors controlling ion diffusion
relating to ‘time of wetness’ within stones are discussed, (continued saturation, connectivity of pores, mineralogy, behaviour of salts, sedimentary structure), and potential changes in system dynamics as a result of climate change are addressed. System inputs may change in terms of increased moisture input, translating into a greater depth of wetting front. Salts are likely to be ‘stored’ differently in stones, with salt being in solution for longer periods (during prolonged winter wetness). This has myriad implications in terms of the movement of ions by diffusion and the potential for chemical change in the stone (especially in more mobile constituents), leading to a weakening of the stone matrix/grain boundary cementing. The ‘output’ may be mobilisation and precipitation of elements leading to, for example, uneven cementing in the stone. This reduced strength of the stone, or compromised ability of the stone to absorb stress, is likely to make crystallisation a more efficacious mechanism of decay when it does occur. Thus, a delay in the onset of crystallisation while stonework is wet does not preclude exaggerated or accelerated material loss when it finally happens.

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With the over-provisioned routing resource on FPGA, the topology choice for NoC implementation on FPGA is more flexible than on ASIC. However, it is well understood that the global wire routing impacts the performance of NoC on FPGA because the topology is routed by using fixed routing fabric. An important question that arises is: will the benefit of diameter reduction by using a highly connective topology outweigh the impact of global routing? To answer this question, we investigate FPGA based packet switched NoC implementations with different sizes and topologies, and quantitatively measure the impact of global routing to each of these networks. The result shows that with sufficient routing resources on modern FPGA, the global routing is not on the critical path of the system, and thus is not a dominating factor for the performance of practical multi-hop NoC system. © 2011 IEEE.

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The book acts as a companion to the Irish pavilion at the 2014 Venice Biennale for Architecture. This chapter examines the context of roads transport and then analyses how its architectural infrastructure developed in this period, concentrating on the work carried out mainly by one Irish firm: Michael Scott and Partners.

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The starfish, Asterias rubens, is widely distributed throughout the northern hemisphere and is an important predator on benthic mussel (Mytilus edulis) beds. Whilst several studies have examined how the size of individuals determines this predator–prey relationship, less is known about how the physiological condition of the prey (mussels) and the extent of their fouling may alter these relationships. Such issues are of particular interest to those working within the benthic mussel cultivation industry to inform best management practice and to help minimise losses during the aquaculture process. The potential role of starfish in the removal of epibiotic barnacles from mussels, the presence of which increases processing costs within the industry, is also of interest. We tested whether stressing mussels by aerial exposure for 48 h and whether the extent of barnacle fouling on mussels affected the feeding rates of three different size classes of starfish feeding on two different size classes of mussels. Feeding rates on stressed and unstressed mussels were similar for each starfish–mussel size combination. Barnacle fouling reduced the feeding rate of medium-sized starfish on larger-sized mussels. We also observed starfish, of all size classes, preying directly on the epibiotic barnacles on mussels, however, feeding rates were low and considered unlikely to reduce the extent of fouling on mussels. Our findings show that the predator–prey relationship between starfish and mussels does not differ between unstressed mussels and those experimentally stressed by aerial exposure for 48 h so that this level of stress is unlikely to affect predation rates by A. rubens following relaying in commercial operations. Whilst barnacle fouling suppressed predation rates in one of our experimental treatments, it does not appear that fouling by barnacles would provide a significant refuge from predation for the majority of mussels in benthic aquaculture stocks. Instead we found the size relationship between starfish and mussels was more important in determining predation rates. Starfish are also unlikely to help reduce barnacle fouling on cultured mussels by preying solely on fouling barnacles and the need to control starfish predation during culture remains.