Management and routing algorithms for ad-hoc and sensor networks

Large scale wireless adhoc networks of computers, sensors, PDAs etc. (i.e. nodes) are revolutionizing connectivity and leading to a paradigm shift from centralized systems to highly distributed and dynamic environments. An example of adhoc networks are sensor networks, which are usually composed by small units able to sense and transmit to a sink elementary data which are successively processed by an external machine. Recent improvements in the memory and computational power of sensors, together with the reduction of energy consumptions, are rapidly changing the potential of such systems, moving the attention towards datacentric sensor networks. A plethora of routing and data management algorithms have been proposed for the network path discovery ranging from broadcasting/floodingbased approaches to those using global positioning systems (GPS). We studied WGrid, a novel decentralized infrastructure that organizes wireless devices in an adhoc manner, where each node has one or more virtual coordinates through which both message routing and data management occur without reliance on either flooding/broadcasting operations or GPS. The resulting adhoc network does not suffer from the deadend problem, which happens in geographicbased routing when a node is unable to locate a neighbor closer to the destination than itself. WGrid allow multidimensional data management capability since nodes' virtual coordinates can act as a distributed database without needing neither special implementation or reorganization. Any kind of data (both single and multidimensional) can be distributed, stored and managed. We will show how a location service can be easily implemented so that any search is reduced to a simple query, like for any other data type. WGrid has then been extended by adopting a replication methodology. We called the resulting algorithm WRGrid. Just like WGrid, WRGrid acts as a distributed database without needing neither special implementation nor reorganization and any kind of data can be distributed, stored and managed. We have evaluated the benefits of replication on data management, finding out, from experimental results, that it can halve the average number of hops in the network. The direct consequence of this fact are a significant improvement on energy consumption and a workload balancing among sensors (number of messages routed by each node). Finally, thanks to the replications, whose number can be arbitrarily chosen, the resulting sensor network can face sensors disconnections/connections, due to failures of sensors, without data loss. Another extension to {WGrid} is {W*Grid} which extends it by strongly improving network recovery performance from link and/or device failures that may happen due to crashes or battery exhaustion of devices or to temporary obstacles. W*Grid guarantees, by construction, at least two disjoint paths between each couple of nodes. This implies that the recovery in W*Grid occurs without broadcasting transmissions and guaranteeing robustness while drastically reducing the energy consumption. An extensive number of simulations shows the efficiency, robustness and traffic road of resulting networks under several scenarios of device density and of number of coordinates. Performance analysis have been compared to existent algorithms in order to validate the results.

Le politiche giudiziarie inglesi degli anni 2000: mutamento di paradigma e rafforzamento dell'incisività politica dei giudici

The Ph.D. dissertation analyses the reasons for which political actors (governments, legislatures and political parties) decide consciously to give away a source of power by increasing the political significance of the courts. It focuses on a single case of particular significance: the passage of the Constitutional Reform Act 2005 in the United Kingdom. This Act has deeply changed the governance and the organization of the English judicial system, has provided a much clearer separation of powers and a stronger independence of the judiciary from the executive and the legislative. What’s more, this strengthening of the judicial independence has been decided in a period in which the political role of the English judges was evidently increasing. I argue that the reform can be interpreted as a «paradigm shift» (Hall 1993), that has changed the way in which the judicial power is considered. The most diffused conceptions in the sub-system of the English judicial policies are shifted, and a new paradigm has become dominant. The new paradigm includes: (i) stronger separation of powers, (ii) collective (as well as individual) conception of the independence of the judiciary, (iii) reduction of the political accountability of the judges, (iv) formalization of the guarantees of judicial independence, (v) principle-driven (instead of pragmatic) approach to the reforms, and (vi) transformation of a non-codified constitution in a codified one. Judicialization through political decisions represent an important, but not fully explored, field of research. The literature, in particular, has focused on factors unable to explain the English case: the competitiveness of the party system (Ramseyer 1994), the political uncertainty at the time of constitutional design (Ginsburg 2003), the cultural divisions within the polity (Hirschl 2004), federal institutions and division of powers (Shapiro 2002). All these contributes link the decision to enhance the political relevance of the judges to some kind of diffusion of political power. In the contemporary England, characterized by a relative high concentration of power in the government, the reasons for such a reform should be located elsewhere. I argue that the Constitutional Reform Act 2005 can be interpreted as a result of three different kinds of reasons: (i) the social and demographical transformations of the English judiciary, which have made inefficient most of the precedent mechanism of governance, (ii) the role played by the judges in the policy process and (iii) the cognitive and normative influences originated from the European context, as a consequence of the membership of the United Kingdom to the European Union and the Council of Europe. My thesis is that only a full analysis of all these three aspects can explain the decision to reform the judicial system and the content of the Constitutional Reform Act 2005. Only the cultural influences come from the European legal complex, above all, can explain the paradigm shift previously described.

Il Maquis nella letteratura spagnola contemporanea. Storia, memoria e rappresentazione narrativa

La tesi analizza la rappresentazione del maquis nella letteratura spagnola contemporanea, scritti in castigliano e pubblicati dal 1985 ad oggi. La tesi si articola in tre capitoli: il primo presenta a livello teorico la metodologia e gli strumenti utilizzati nello svolgimento dello studio, ed è incentrato innanzitutto sul tentativo di definizione e catalogazione dei romanzi del maquis, con una particolare attenzione alla temperie culturale cui fanno riferimento, presentando le estetiche postmoderna e neomoderna e cercando di situare le opere narrative facenti parte del corpus della ricerca. Nel secondo capitolo è centrale in cambio l’analisi dei rapporti tra Storia e narrazione: oltre a concentrarsi sul dibattito interdisciplinare circa le connessioni tra la Storia e la narrativa, si cerca di dar conto dei riflessi di questa riflessione contemporanea all’interno delle opere facenti parte del corpus. Infine, il terzo capitolo riguarda l’analisi delle metafore animali rintracciabili nei romanzi sul maquis scelti, concentrandosi principalmente su Luna de lobos di Julio Llamazares e La agonía del búho chico di Justo Vila. L’impiego di questa figura retorica, che si ritrova in vari gradi in tutte le opere narrative scelte, risponde tanto ad una ricerca di verosimiglianza quanto alle modalità di rappresentazione della realtà empirica, riportando l’attenzione sui metodi atti alla figurazione e all’accesso alla conoscenza del mondo. La proposta di un cambio di paradigma estetico e narrativo in atto nella letteratura contemporanea spagnola cerca quindi una conferma nel momento dell’analisi, attraverso la quale si cerca di indagare se, e in che misura, il romanzo sul maquis si inserisce nel dibattito letterario odierno, e quanto contribuisce allo sviluppo del medesimo paradigma estetico in via di definizione – quello neomoderno –, cercando una conferma che si basa sulla presenza di quelle tematiche segnalate nel momento della discussione teorica e metodologica come tratti basilari e strutturanti le opere.