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Guaranteeing Communication Quality in Real World WSN Deployments
No full textNetworks of smart interconnected objects have allowed the integration of the artificial world into the physical one. The interaction over a wireless medium is simultaneously the technology enabler and the primary hindering factor. The complexity and variability of the behavior of low power wireless communication is one of the challenges making the design and deployment of a system based on this technology a unique and demanding experience. In this thesis, we describe the deployment of two operational systems for structural health monitoring and adaptive lighting, undertaken by our research group. Our major contribution, among others, covers the definition and implementation of the system services enabling the monitoring infrastructure to guarantee the required quality. The resulting unique design and reliability provide concrete support to the vision of wireless sensor networks as dependable monitoring infrastructure.
Despite the success in meeting the user needs, the simple yet effective solutions exploited in the aforementioned deployments make apparent the limitations of the widely used approaches to coordinate access to the communication medium. This thesis also argues that the currently employed solutions at the MAC layer are insufficient to provide guarantees to the resource user. Therefore, we introduce Reins-MAC, a Time-Division Multiple-Access (TDMA) communication scheduler that coordinates access to the medium in a fully decentralized fashion. Limited flexibility, scalability, robustness, as well as increased overhead and complexity are commonly recognized shortcomings of TDMA approaches. Reins-MAC overcomes these limitations by adapting the scheduling to match local availability and natural connectivity variations. Moreover, each node is empowered with full control over its own communication resources.
The ability to anarchically apply changes to the communication schedule allows the steering of the resource allocation towards individual needs, dictated by the higher layers in the network stack. The resulting quality and anarchy in accessing the communication resource affect the design and implementation of WSNs, opening new horizons where the application regains control of the primary resource: communication
Integrated water design for a decentralized urban landscape: [text and figures]
Get PDFIn the Veneto Città Diffusa, the decentralized urban landscape of the Veneto Region, Northeast Italy, the economic growth of recent decades brought about increased urbanization and agricultural intensification. The process of change has been accompanied by the extension and/or maximization of centralized services of drinking water, irrigation, waste water and drainage to meet greater demands for the provision and disposal of water. Accordingly, the structure of a formerly poor rural landscape has been adapted to support an affluent industrialized and urban one. However, all this has had detrimental side effects, which, in time might seriously compromise the quality of life in this landscape. On one side, the transformations that occurred have in fact given rise to unexpected problems of drought, flooding and pollution of water; and recent changes in climate patterns have further intensified these risks. On the other side, the long term fine grained carrying structures of the landscape fabric –like roads, field ditches, stream and river corridors, dirt roads, paths etc.-, as the very basis of the landscape’s unique ecological diversity, and once used to convey the area’s flows now risk general extinction. The existing road system is also increasingly under pressure to intensify traffic that creates congestion, pollution and unsafe conditions. From a planning and design perspective, this calls for adequate methods and tools that can help designers to tackle the needs for more sustainable water flows as well as the needs for a recovered ecological integrity (including spatial intelligibility) of this urban landscape. This can be of a great importance also for a better understanding of other territories of urban dispersion which are spreading especially over the European and –although in very different forms- the American continents. The present research aims to contribute to the planning and design answers to these urgent problems. For this purpose, the urban landscape of the Veneto Città Diffusa was approached with principles derived from an Integrated Water Management approach (IWM) that, recently, has been successfully applied in the urban context as an alternative to the technocratic approach of maximizing flows. Storage of water is the key principle, for it can bring about decentralized storage, which means new and different water flow management and spatial arrangements. This can ultimately be obtained through the placement and implementation of small scale and decentralized infrastructures.
By focusing on the interrelation between flow patterns and spatial arrangements in a small portion of the Veneto Città Diffusa –i.e. the case study landscape- the study has elaborated and confirmed two specific closely related assumptions.
The first assumption is that the recent loss of landscape diversity and the increasing problems of flood, drought and water pollution of the Veneto Città Diffusa are closely related and ascribable also to the processes of centralization of the water flows that accompanied the area’s economic growth. The changes of flow patterns and spatial arrangements of the case study area that happened over the last decades were systematically observed in a threefold area-flow-actor perspective. Insights into the present arrangements of irrigation, drainage, drinking water and waste water at the scale of the Consorzio di Bonifica Valli Grandi e Medio Veronese waterboard also accompanied the investigation. The diagnosis showed that the centralized systems arranged to perform greater inflows and outflows, draw heavily on resources and often risk exceeding the region’s ecological carrying capacity. Moreover, the centralized arrangement often conflicts with the decentralized character of the settlements. No synergetic relations have been developed between the man-made water system and the existing pervasive fine grained elements of the landscape. Instead, this rich capital asset has been left behind and even neglected. And such forms of negligence have ultimately brought about a massive loss of biodiversity, accessibility and spatial intelligibility of the local landscape.
This leads to the second assumption that has been researched: in the decentralized urban landscape of the Veneto Città Diffusa, answers that design measures can give in response to increasing water-flow dysfunctions and loss of diversity can be based on decentralized water storage systems that make use of the existing fine grain structures of local landscapes –ditches, streams, land depressions, former pits, hedge-rows, dirt roads, paths etc.- and promote a local-based utilisation of resources (resilience), while fostering a stronger local identity, biodiversity and accessibility for more coherent spatial arrangements. Building on the Ecological Conditions Strategy conceived by Tjallingii (1996), a set of guiding models was developed. In the models, the principles of Integrated Water Management were tuned to those fine grained landscape elements that still structure the low plains of the Veneto –the built lot system, the agricultural field system, the road system, the stream system and the excavation site system. Principles and models of integration and decentralization drove the exploration of design options for different levels of decentralized management of water in the case study area. The creative design process of learning produced a useful toolbox of design models. The design exploration also proved that the dispersed urbanization of the Città Diffusa can be made suitable to accommodate modern integrated and decentralized water systems that, by re-activating the existing carrying structures, also contribute to recovering the landscape. Decentralized urbanization can actually be an ally in the search for sustainable and legible settlements that also reuse and recycle water locally.
Designing an integrated water system that fits with the Città Diffusa and contributes to the ecological integrity of this urban landscape remains an important challenge. The tools that can be of practical help to designers and decision-makers who are willing to undertake this challenge were investigated and worked out. Nonetheless, the way to realize the outlined strategies is complex and affected by uncertainty. In this context more research is needed to investigate the effects of decentralization at the level of the region on one side, and on the other side to investigate how these integrated systems can be set to fit present institutional and market frameworks. In conclusion, the study generated concrete proposals for one or more pilot projects that will be extremely important to creating consensus in the decision process during the testing of models and strategies
The neural correlates of verbs and nouns: a MEG study on Italian homophones
No full textThe neural correlates of nouns and verbs are the central issue of a long-standing debate in neuropsychology. The double dissociability of the two grammatical categories and of the respective morphosyntactic processes has been firmly established in neuropsychological studies (eg, Shapiro & Caramazza, 2003a; Drucks, 2002) leading to the hypothesis that verbs and nouns, as well as the involved morphosyntactic operations, have distinct neural representations. However, neuroimaging findings provide only inconsistent support to these hypotheses, which could be due in part to the limitations intrinsic to the various neuroimaging tools. In the present study, the neural representation of Noun/Verb distinctions is studied by means of a novel technique - magnetoencephalography (MEG), which is characterized by excellent temporal resolution and good spatial resolution. The goal of the study is to establish whether distinct neural substrates are involved in processing nouns and verbs in the context of phrases.
In an adaptation paradigm we presented Italian homophonous noun and verbs. Homophones were selected because they share the same word form but belong to different grammatical categories. The homophones nouns and verbs were presented in minimal syntactical context: article and noun, pronoun and verb (eg, il ballo/i balli, the dance/the dances; io ballo/tu ballii, I dance/you dance). Twelve healthy participants performed a silent reading task, and their spatiotemporal information was measured during the processing of homophones.
The analysis conducted on the evoked responses of noun and verb phrases identified the response components of lexical processing and the differences between the two grammatical categories. A localization technique was employed to isolate the corresponding differences in the cerebral topographies.
The resultant differences revealed partially matching neural substrates during the early processing of both grammatical categories that diverged in the later stages of processing. Both nouns and verbs activated the occipital, left temporal and parietal regions but only verbs engaged the left inferior frontal gyrus during the late time window. Our results are comparable to findings of the clinical reports: verbs were mainly processed at the left frontal cortex while nouns activated the left temporal lobe.
These findings support the hypothesis that at least partially distinct neural structures are involved in the processing/representation of verbs and nouns and of their respective morphosyntactic operations. MEG appears to be a promising tool for the analysis of the spatiotemporal dynamics of the networks implicated in language processing
Data Driven Models for Language Evolution
No full textNatural languages that originate from a common ancestor are genetically related, words are the core of any language and cognates are words sharing the same ancestor and etymology. Cognate identification, therefore, represents the foundation upon which the evolutionary history of languages may be discovered, while linguistic phylogenetic inference aims to estimate the genetic relationships that exist between them.
In this thesis, using several techniques originally developed for biological sequence analysis, we have designed a data driven orthographic learning system for measuring string similarity and we have successfully applied it to the tasks of cognate identification and phylogenetic inference.
Our system has outperformed the best comparable phonetic and orthographic cognate identification models previously reported in the literature, with results statistically significant and remarkably stable, regardless of the variation of the training dataset dimension. When applied to phylogenetic inference of the Indo-European language family, whose higher structure does not yet have consensus, our method has estimated phylogenies which are compatible with the benchmark tree and has reproduced correctly all the established major language groups and subgroups present in the dataset
The Determinants of Migration: Household and Community Networks: An Application to Mexico and other Central American Countries
No full textDespite the great efforts scholars have devoted to the study of migration a unified and coherent theory of international migration does not yet exist. Particularly, only in recent years, scholars have developed models of labor mobility to take into account social interaction across agents. Similarly, empirical analysis lacks an adequate approach to social interaction in migration, often using very rough measures as, for example, the stock of compatriots in the receiving country. The aim of this dissertation is to examine economic migrants decision to migrate, focusing specifically on potential migrants who can choose if and where to migrate, and which conditions facilitate their migration. It investigates how wealth, social networks and education interact in determining households’ migration strategies and the aggregate dimension and composition of migration flows. Household income maximization strategy evaluates migration as a possible, but costly investment. In a context of underdeveloped financial and insurance markets, budget constraints play a key role in determining migration behavior. Poorer households have higher incentives, but fewer opportunities to migrate, whereas better-off households have fewer incentives, but greater possibilities of migrating. Social networks, reducing costs and risks of migration and thus counterbalancing budget constraints, mitigate this effect and allow new social strata to migrate. In the empirical analysis we examine Mexican migration to the U.S., proposing two new tools to apply in empirical analysis and showing that household and community networks act as complements in the probability of migration, and as substitutes in the optimal number of migrants. We also examine migration to the U.S. from five Central American countries, comparing findings with those obtained for Mexico
Bioreactor Design for Dynamic Process Optimization in Tissue Engineering
No full textTissue engineering is an interdisciplinary field in which cell biology, biomaterials science, and surgery are combined and its main goal is to repair, replace and reproduce tissues and organs.
Following this procedure, cells are seeded on proper scaffolds and induced in sequence to adhere, eventually differentiate, proliferate and finally to produce the wanted extracellular matrix (ECM). During cell culture, the usefulness of applying proper physiological-like stimuli, i.e., biochemical but also mechanical signals to drive and accelerate both cell differentiation and ECM production has been demonstrated.
Tissue regeneration can be either conducted entirely in vivo or assisted by a previous in vitro phase. Considering the latter situation, a bioreactor can be defined as any apparatus that attempts to mimic physiological conditions in order to maintain and encourage tissue regeneration in dynamic conditions. Dynamic cell cultures using bioreactors can be considered a good intermediate step between the conventional in vitro static approach and in vivo studies. Therefore it is possible to promote the formation of the specific tissue by simulating physiological conditions via the application of specific mechanical and biochemical stimuli.
The proposed work is focused on the design and development of bioreactors for bone and cartilage regeneration, in which optimal cell culture conditions are controlled (temperature, nutrients, carbon dioxide and oxygen levels), and mechanical stimuli are applied on the cell constructs. This study presents a wide investigation concerning these mechanical stimulations in order to understand the best cell culture parameters for the activations of cells, naturally accustomed to similar stresses inside the joint. In particular, direct compression, change in hydrodynamic pressure and perfusion modes are compared and analyzed
Creolizing Diaspora: Home and Identity, Language and Hospitality in Arab Diasporic Literature
No full textThis research investigates the extent to which diaspora can be considered a useful term of reference for the exploration and critical interrogation of the literary works written by authors of Arab origin in Europe, Canada and the United States.
The aim of this study is to develop an alternative theoretical model to analyze and critically interrogate works that have been written beyond the boundaries of a national literature and that blur the opposition "migrant" vs. "national" or "ethnic" vs. "mainstream."
This study makes use of an integrated methodology and draws its theoretical tools from deconstruction, post-colonial studies, feminist theory, and Edouard Glissant's poetics of creolization. It is an interdisciplinary and multilingual work that puts in dialogue literature with philosophy and sociology and explores texts written in English, French, German, and Italian
Gli ebrei in Romania e Ungheria dal punto di vista dell'American Jewish Yearbook e della diplomazia vaticana (1920-1938).
No full textLa tesi analizza la situazione delle due comunità ebraiche durante il periodo preso in considerazione attraverso la documentazione archivistica vaticana e il materiale pubblicato nell'annuario ebraico americano
Displacement Capacity of Load-Bearing Masonry as a Basis for Seismic Design
Get PDFThe masonry still one of the widespread construction system for low-rise residential buildings even for countries prone to seismic risk. Seismic design methods yet in use are based on idea that controlling forces is better way to control earthquake induced damages. In recent decades, however, was highlighted as the differences in strength between two levels of damage is low, and therefore as the damage is better correlated to the displacement. Also, in recent years, has arose a widespread expectation for being able to control the damage based on the probability of occurrence of an earthquake or being able to base the design on different performance levels ("performance-based design").
In this context, the design of masonry buildings needs to develop these design methods. The results of experimental tests performed at the University of Padua in the recent years on different masonry systems both reinforced and unreinforced with different horizontal and vertical joints typologies, which were aimed to characterization under combined in-plane vertical and horizontal cyclic loading, were used to make different strategies of finite element modeling that reproduce and extend the experimental results using parametric analyses. These analyses allow a comparison and a validation of an analytical model which was then developed. This model is able to reproduce the envelope curves of the cyclic shear-compression tests and it is able to interpret the performances of panels linking them with limit states resulting from integration of cross-section equilibrium equations. Finally, it was applied a model able to reproduce the hysteretic behavior of masonry and were carried out dynamic analyses using the input data derived from the envelope curves. The data thus collected can be used as database and as input for displacement-based design methods
Essays on Spatial Inequalities in Income and Education: Econometric Evidence from Pakistan
No full textFrom the industrial revolution to the emergence of the so-called knowledge economy, history has shown that economic development has taken place unevenly across regions. National economies are a complex mix of varying types of geographical configurations which in turn involve varying economic systems, infrastructure, and human capital. In this context recent literature in regional growth and development has highlighted how crucial it is to analyse socio-economic phenomena through the lens of spatial concepts such as density, distance, neighbourhood, and agglomeration. This dissertation emphasizes this fact in three interrelated studies that have analyzed the spatial aspects of income and human capital inequalities in Pakistan.
The first study investigates the evolution and trend of earnings income distribution in Pakistan between 1993 and 2006—a period characterised by macroeconomic reforms and a decent average GDP growth rate. Specifically, it shows the extent to which changes in the returns to human capital have contributed towards changes in earnings inequality across Pakistan. The second study utilizes exploratory spatial data techniques to analyze the extent of spatial clustering of economic inequalities, growth and development across Pakistani districts between 1998 and 2006. The final study then investigates for the first time income convergence across Pakistani districts between 1998 and 2005 using spatial and non spatial econometric techniques.
The main empirical findings from the first study reveal that the returns to low levels of education have declined while the returns to higher education levels have increased. Moreover these returns are much higher for females as compared to males. It has also been shown that earnings inequality has consistently remained higher within provinces as compared to inequality between them. Finally this study demonstrates that females in general and rural females in particular are most sensitive to policies that can affect earnings inequality and labour market outcomes in Pakistan. The findings from the second study demonstrate how neighbouring districts share each other’s development levels, confirming that economic geography does matter for regional inequalities, growth, and development across Pakistan. Finally, the convergence analysis carried out in the third study, demonstrates that conditional convergence may be observed across Pakistan once spatial effects have been taken into account.
In summary, this dissertation contributes to the literature and policy debate on economic inequalities and convergence in developing economies and in particular to district level research in Pakistan, by applying counter factual regression analysis and spatial econometric techniques for the first time to Pakistani data