4 resultados para Challenges to their management
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
Development aid involves a complex network of numerous and extremely heterogeneous actors. Nevertheless, all actors seem to speak the same ‘development jargon’ and to display a congruence that extends from the donor over the professional consultant to the village chief. And although the ideas about what counts as ‘good’ and ‘bad’ aid have constantly changed over time —with new paradigms and policies sprouting every few years— the apparent congruence between actors more or less remains unchanged. How can this be explained? Is it a strategy of all actors to get into the pocket of the donor, or are the social dynamics in development aid more complex? When a new development paradigm appears, where does it come from and how does it gain support? Is this support really homogeneous? To answer the questions, a multi-sited ethnography was conducted in the sector of water-related development aid, with a focus on 3 paradigms that are currently hegemonic in this sector: Integrated Water Resources Management, Capacity Building, and Adaptation to Climate Change. The sites of inquiry were: the headquarters of a multilateral organization, the headquarters of a development NGO, and the Inner Niger Delta in Mali. The research shows that paradigm shifts do not happen overnight but that new paradigms have long lines of descent. Moreover, they require a lot of work from actors in order to become hegemonic; the actors need to create a tight network of support. Each actor, however, interprets the paradigms in a slightly different way, depending on the position in the network. They implant their own interests in their interpretation of the paradigm (the actors ‘translate’ their interests), regardless of whether they constitute the donor, a mediator, or the aid recipient. These translations are necessary to cement and reproduce the network.
Resumo:
This PhD thesis reports on car fluff management, recycling and recovery. Car fluff is the residual waste produced by car recycling operations, particularly from hulk shredding. Car fluff is known also as Automotive Shredder Residue (ASR) and it is made of plastics, rubbers, textiles, metals and other materials, and it is very heterogeneous both in its composition and in its particle size. In fact, fines may amount to about 50%, making difficult to sort out recyclable materials or exploit ASR heat value by energy recovery. This 3 years long study started with the definition of the Italian End-of-Life Vehicles (ELVs) recycling state of the art. A national recycling trial revealed Italian recycling rate to be around 81% in 2008, while European Community recycling target are set to 85% by 2015. Consequently, according to Industrial Ecology framework, a life cycle assessment (LCA) has been conducted revealing that sorting and recycling polymers and metals contained in car fluff, followed by recovering residual energy, is the route which has the best environmental perspective. This results led the second year investigation that involved pyrolysis trials on pretreated ASR fractions aimed at investigating which processes could be suitable for an industrial scale ASR treatment plant. Sieving followed by floatation reported good result in thermochemical conversion of polymers with polyolefins giving excellent conversion rate. This factor triggered ecodesign considerations. Ecodesign, together with LCA, is one of the Industrial Ecology pillars and it consists of design for recycling and design for disassembly, both aimed at the improvement of car components dismantling speed and the substitution of non recyclable material. Finally, during the last year, innovative plants and technologies for metals recovery from car fluff have been visited and tested worldwide in order to design a new car fluff treatment plant aimed at ASR energy and material recovery.
Resumo:
Turfgrasses are ubiquitous in urban landscape and their role on carbon (C) cycle is increasing important also due to the considerable footprint related to their management practices. It is crucial to understand the mechanisms driving the C assimilation potential of these terrestrial ecosystems Several approaches have been proposed to assess C dynamics: micro-meteorological methods, small-chamber enclosure system (SC), chrono-sequence approach and various models. Natural and human-induced variables influence turfgrasses C fluxes. Species composition, environmental conditions, site characteristics, former land use and agronomic management are the most important factors considered in literature driving C sequestration potential. At the same time different approaches seem to influence C budget estimates. In order to study the effect of different management intensities on turfgrass, we estimated net ecosystem exchange (NEE) through a SC approach in a hole of a golf course in the province of Verona (Italy) for one year. The SC approach presented several advantages but also limits related to the measurement frequency, timing and duration overtime, and to the methodological errors connected to the measuring system. Daily CO2 fluxes changed according to the intensity of maintenance, likely due to different inputs and disturbances affecting biogeochemical cycles, combined also to the different leaf area index (LAI). The annual cumulative NEE decreased with the increase of the intensity of management. NEE was related to the seasonality of turfgrass, following temperatures and physiological activity. Generally on the growing season CO2 fluxes towards atmosphere exceeded C sequestered. The cumulative NEE showed a system near to a steady state for C dynamics. In the final part greenhouse gases (GHGs) emissions due to fossil fuel consumption for turfgrass upkeep were estimated, pinpointing that turfgrass may result a considerable C source. The C potential of trees and shrubs needs to be considered to obtain a complete budget.
Resumo:
The ever increasing demand for new services from users who want high-quality broadband services while on the move, is straining the efficiency of current spectrum allocation paradigms, leading to an overall feeling of spectrum scarcity. In order to circumvent this problem, two possible solutions are being investigated: (i) implementing new technologies capable of accessing the temporarily/locally unused bands, without interfering with the licensed services, like Cognitive Radios; (ii) release some spectrum bands thanks to new services providing higher spectral efficiency, e.g., DVB-T, and allocate them to new wireless systems. These two approaches are promising, but also pose novel coexistence and interference management challenges to deal with. In particular, the deployment of devices such as Cognitive Radio, characterized by the inherent unplanned, irregular and random locations of the network nodes, require advanced mathematical techniques in order to explicitly model their spatial distribution. In such context, the system performance and optimization are strongly dependent on this spatial configuration. On the other hand, allocating some released spectrum bands to other wireless services poses severe coexistence issues with all the pre-existing services on the same or adjacent spectrum bands. In this thesis, these methodologies for better spectrum usage are investigated. In particular, using Stochastic Geometry theory, a novel mathematical framework is introduced for cognitive networks, providing a closed-form expression for coverage probability and a single-integral form for average downlink rate and Average Symbol Error Probability. Then, focusing on more regulatory aspects, interference challenges between DVB-T and LTE systems are analysed proposing a versatile methodology for their proper coexistence. Moreover, the studies performed inside the CEPT SE43 working group on the amount of spectrum potentially available to Cognitive Radios and an analysis of the Hidden Node problem are provided. Finally, a study on the extension of cognitive technologies to Hybrid Satellite Terrestrial Systems is proposed.