3 resultados para clustering and QoS-aware routing

em Glasgow Theses Service


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Earlier histories of the Scottish parliament have been somewhat constitutional in emphasis and have been exceedingly critical of what was understood to be parliament's subservience to the crown. Estimates by constitutional historians of the extreme weakness of parliament rested on an assessment of the constitutional system. The argument was that many of its features were not consistent with a reasonably strong parliament. Because the 'constitution' is apparently fragmented, with active roles played by bodies such as the lords of articles, the general council and the convention of estates, each apparently suggesting that parliament was inadequate, historians have sometimes failed to appreciate the positive role played by the estates in the conduct of national affairs. The thesis begins with a discussion of the reliability of the printed text of APS and proceeds to an examination of selected aspects of the work of parliament in a period from c 1424-c 1625. The belief of constitutional historians such as Rait that conditions In Scotland proved unfavourable to the interests and. effectiveness of parliament in the fifteenth and sixteenth centuries, is also examined. Chapter 1 concludes that APS is a less than reliable text, particularly for the reign of James I. Numerous statutes were excluded from the printed text and they are offered below for the first time. These statutes have been a useful addition to our understanding of the reign of James I. Chapter 2 analyses the motives behind the schemes for shire representation and concludes that neither constitutional theory nor political opportunism explains the support which James I and James VI gave to these measures. Both these monarchs were motivated by the realisation that their particular ambitions were dependent on winning the support of the estates whose ranks should include representatives from the shires. Chapter 3 examines the method of electing the lords of articles, the composition of this committee, and some aspects of its operation. The conclusion is that in the main the estates were the deciding force in the choice of the lords of articles. The committee's composition was more a reflection of a desire for a balance between representatives from north and south of the Forth and for the most important burghs and clergy to be selected than an attempt at electing government favourites. The articles did exercise a significant control over the items which came before parliament but this control was not absolute and applied to government as well as private legislation. Chapter 4 questions the traditional view that the general council and convention of estates were the same body. It is argued that they were two different institutions with different powers, but that they nevertheless worked within certain limits and were careful not to usurp the authority of parliament. Chapter 5 concedes that taxation was sometimes decided outside parliament; that the irregularity of taxation certainly weakened the bargaining power of the estates and that the latter did not appear to capitalise on these occasions when taxation was an issue. But the tendency was to ensure that, whether in or out of parliament, the decision to impose taxation was taken by a large number of each estate. The infrequency of taxation was a direct consequence of an unwillingness among the estates to agree to a regular taxation and their preference to ensure for the crown an alternative source of income. Moreover taxation was one issue, which more than any other, would be subject to contentious opposition by the estates, and could lead to the crown's defeat. Chapter 6 is concerned with ecclesiastical representation after the Reformation and the church's attitudes to the possibility of ministerial representation. Some ministers had doctrinal misgivings but the majority came to believe that the church's absence from parliament bad severely reduced. the influence of the church. That no agreement was forthcoming on a system of ministerial representation, particularly after 1597, is attributable to the estates' unwillingness to compromise and, not to the strength of opposition in the church. Chapter 7 examines the institutions which are sometime seen as 'rivals' of parliament and concludes that institutions such as the privy council were generally very careful in matters which needed the approval of parliament, and seemed aware of the greater authority of parliament. Chapter 8 which illustrates how parliament had the right to be consulted in all important matters of state, brings together the main points of the earlier chapters and offers further illustrations of the essential role which parliament played in the conduct of national affairs. Whether or not the system can be regarded as constitutionally sound, the estates in Scotland could observe parliament's day-to-day operation with some satisfaction. All in all, there is little convincing evidence that parliament was as weak as some historians would have us believe.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The Internet has grown in size at rapid rates since BGP records began, and continues to do so. This has raised concerns about the scalability of the current BGP routing system, as the routing state at each router in a shortest-path routing protocol will grow at a supra-linearly rate as the network grows. The concerns are that the memory capacity of routers will not be able to keep up with demands, and that the growth of the Internet will become ever more cramped as more and more of the world seeks the benefits of being connected. Compact routing schemes, where the routing state grows only sub-linearly relative to the growth of the network, could solve this problem and ensure that router memory would not be a bottleneck to Internet growth. These schemes trade away shortest-path routing for scalable memory state, by allowing some paths to have a certain amount of bounded “stretch”. The most promising such scheme is Cowen Routing, which can provide scalable, compact routing state for Internet routing, while still providing shortest-path routing to nearly all other nodes, with only slightly stretched paths to a very small subset of the network. Currently, there is no fully distributed form of Cowen Routing that would be practical for the Internet. This dissertation describes a fully distributed and compact protocol for Cowen routing, using the k-core graph decomposition. Previous compact routing work showed the k-core graph decomposition is useful for Cowen Routing on the Internet, but no distributed form existed. This dissertation gives a distributed k-core algorithm optimised to be efficient on dynamic graphs, along with with proofs of its correctness. The performance and efficiency of this distributed k-core algorithm is evaluated on large, Internet AS graphs, with excellent results. This dissertation then goes on to describe a fully distributed and compact Cowen Routing protocol. This protocol being comprised of a landmark selection process for Cowen Routing using the k-core algorithm, with mechanisms to ensure compact state at all times, including at bootstrap; a local cluster routing process, with mechanisms for policy application and control of cluster sizes, ensuring again that state can remain compact at all times; and a landmark routing process is described with a prioritisation mechanism for announcements that ensures compact state at all times.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Conventional web search engines are centralised in that a single entity crawls and indexes the documents selected for future retrieval, and the relevance models used to determine which documents are relevant to a given user query. As a result, these search engines suffer from several technical drawbacks such as handling scale, timeliness and reliability, in addition to ethical concerns such as commercial manipulation and information censorship. Alleviating the need to rely entirely on a single entity, Peer-to-Peer (P2P) Information Retrieval (IR) has been proposed as a solution, as it distributes the functional components of a web search engine – from crawling and indexing documents, to query processing – across the network of users (or, peers) who use the search engine. This strategy for constructing an IR system poses several efficiency and effectiveness challenges which have been identified in past work. Accordingly, this thesis makes several contributions towards advancing the state of the art in P2P-IR effectiveness by improving the query processing and relevance scoring aspects of a P2P web search. Federated search systems are a form of distributed information retrieval model that route the user’s information need, formulated as a query, to distributed resources and merge the retrieved result lists into a final list. P2P-IR networks are one form of federated search in routing queries and merging result among participating peers. The query is propagated through disseminated nodes to hit the peers that are most likely to contain relevant documents, then the retrieved result lists are merged at different points along the path from the relevant peers to the query initializer (or namely, customer). However, query routing in P2P-IR networks is considered as one of the major challenges and critical part in P2P-IR networks; as the relevant peers might be lost in low-quality peer selection while executing the query routing, and inevitably lead to less effective retrieval results. This motivates this thesis to study and propose query routing techniques to improve retrieval quality in such networks. Cluster-based semi-structured P2P-IR networks exploit the cluster hypothesis to organise the peers into similar semantic clusters where each such semantic cluster is managed by super-peers. In this thesis, I construct three semi-structured P2P-IR models and examine their retrieval effectiveness. I also leverage the cluster centroids at the super-peer level as content representations gathered from cooperative peers to propose a query routing approach called Inverted PeerCluster Index (IPI) that simulates the conventional inverted index of the centralised corpus to organise the statistics of peers’ terms. The results show a competitive retrieval quality in comparison to baseline approaches. Furthermore, I study the applicability of using the conventional Information Retrieval models as peer selection approaches where each peer can be considered as a big document of documents. The experimental evaluation shows comparative and significant results and explains that document retrieval methods are very effective for peer selection that brings back the analogy between documents and peers. Additionally, Learning to Rank (LtR) algorithms are exploited to build a learned classifier for peer ranking at the super-peer level. The experiments show significant results with state-of-the-art resource selection methods and competitive results to corresponding classification-based approaches. Finally, I propose reputation-based query routing approaches that exploit the idea of providing feedback on a specific item in the social community networks and manage it for future decision-making. The system monitors users’ behaviours when they click or download documents from the final ranked list as implicit feedback and mines the given information to build a reputation-based data structure. The data structure is used to score peers and then rank them for query routing. I conduct a set of experiments to cover various scenarios including noisy feedback information (i.e, providing positive feedback on non-relevant documents) to examine the robustness of reputation-based approaches. The empirical evaluation shows significant results in almost all measurement metrics with approximate improvement more than 56% compared to baseline approaches. Thus, based on the results, if one were to choose one technique, reputation-based approaches are clearly the natural choices which also can be deployed on any P2P network.