Η Ορθογώνια Πολυπλεξία Διαίρεσης Συχνότητας (OFDM) έχει προταθεί ως τεχνική διαμόρφωσης σε οπτικά δίκτυα, λόγω της καλής φασματικής απόδοσής της, της ευελιξίας και της ανοχής της σε βλάβες. Η διαμόρφωση OFDM επιτρέπει την ελαστική ανάθεση φάσματος, χρησιμοποιώντας μεταβλητό πλήθος υποφερουσών, καθώς και την επιλογή του κατάλληλου επιπέδου διαμόρφωσης με βάση την απόσταση της μετάδοσης. Το «Πρόβλημα Δρομολόγης και Ανάθεσης Φάσματος» (RSA) έχει αποδειχθεί ότι είναι ένα NP-πλήρες πρόβλημα, γεγονός που υποδηλώνει τη χρήση γραμμικού προγραμματισμού για τη λύση του. Στόχος της διπλωματικής εργασίας είναι η βελτίωση της απόδοσης του υπάρχοντος αλγορίθμου ακέραιου γραμμικού προγραμματισμού, με χρήση μεταευριστικών, έτσι ώστε στο ίδιο χρονικό διάστημα να υπολογίζεται αποδοτικότερη χρησιμοποίηση του συνολικού απαιτούμενου φάσματος, για το σύνολο των μεταδόσεων στο δίκτυο. / Orthogonal Frequency Division Multiplexing (OFDM) has been proposed as a modulation technique for optical networks, because of its good spectral efficiency, flexibility, and tolerance to impairments. OFDM modulation allows elastic spectrum allocation, using a variable number of subcarriers and choosing an appropriate modulation level, taking into account the transmission distance. The “Routing and Spectrum Allocation” (RSA) problem has been proved to be a NP-complete problem, which suggests the usage of linear programming in order to be solved. This diploma thesis aims to improve the efficiency of the existing integer linear programming algorithm, by using metaheuristics, so that at the same time period a more efficient utilization of the required spectrum is computed, for all network transmissions.

Κατά την διάδοση του σήματος στα οπτικά δίκτυα η ποιότητα του λαμβανόμενου σήματος εξασθενεί λόγω των διαφόρων ειδών απωλειών που υπεισέρχονται κατά τη μετάδοση. Οι κυριότερες εξ’ αυτών είναι: ο θόρυβος λόγω των οπτικών ενισχυτών, η διαφωνία, η χρωματική διασπορά, η διασπορά τρόπων πόλωσης, η μείξη τεσσάρων κυμάτων, η αυτοδιαμόρφωση φάσης κτλ. Προκειμένου να επιτευχθεί αποδεκτή ποιότητα λαμβανόμενου σήματος στον δέκτη είναι απαραίτητη, ιδιαίτερα για μεγάλα μονοπάτια, η χρήση οπτικών 3R αναγεννητών σε κάποιους ενδιάμεσους κόμβους για την περιοδική αναμετάδοση του σήματος. Στην παρούσα διπλωματική εργασία σχεδιάζονται και υλοποιούνται στατικοί αλγόριθμοι δρομολόγησης και ανάθεσης μηκών κύματος για ημιδιαφανή οπτικά δίκτυα. Συγκεκριμένα, θεωρώντας μια δικτυακή τοπολογία, έναν αριθμό διαθέσιμων μηκών κύματος, μια μήτρα κίνησης και μια (αραιή) τοπολογία 3R αναγεννητών για το εξεταζόμενο δίκτυο (ή εκφράζοντάς το διαφορετικά έναν αριθμό ελεύθερων πομποδεκτών για κάθε κόμβο του δικτύου) επιχειρείται η μεγιστοποίηση του αριθμού των συνδέσεων που μπορούν να επιτευχθούν, διατηρώντας παράλληλα την επιθυμητή ποιότητα μετάδοσης. Έτσι, το πρόβλημα της επιλογής της ακολουθίας των αναγεννητών μέσα από τους οποίους θα δρομολογηθεί η κάθε αδιαφανής αίτηση σύνδεσης, μοντελοποιείται σαν ένα πρόβλημα εικονικής τοπολογίας (virtual topology problem). Στην συνέχεια το πρόβλημα αυτό επιλύεται με τη βοήθεια μιας σειράς αλγορίθμων από πολύπλοκους που βασίζονται σε σχηματισμούς ακέραιου γραμμικού προγραμματισμού (Integer Linear Programming – ILP) έως απλούστερους αλλά πάντα πρακτικούς ως προς την εύρεση λύσης, ευριστικούς αλγόριθμους. Ύστερα από την επιλογή της ακολουθίας των χρησιμοποιούμενων αναγεννητών για κάθε αδιαφανή αίτηση σύνδεσης, η μήτρα κίνησης μετασχηματίζεται σε μια ισοδύναμη διαφανή, όπου κάθε αδιαφανής αίτηση έχει αντικατασταθεί από μια σειρά διαφανών συνδέσεων που τερματίζουν και ξεκινούν από τους συγκεκριμένους 3R κόμβους αναγέννησης. Ακολούθως, εφαρμόζεται ένας διαφανής IA-RWA αλγόριθμος για τη μετασχηματισμένη μήτρα κίνησης, ενώ τυχόν συνδέσεις που μποκάρονται ύστερα από την εφαρμογή του διαφανή αλγορίθμου επαναδρομολογούνται χρησιμοποιώντας τους υπολοιπόμενους αναγεννητές. Η Ποιότητα Μετάδοσης (Quality of Transmission QoT) των δημιουργουμένων lightpaths υπολογίζεται με τη βοήθεια ενός εκτιμητή της παραμέτρου Q του κάθε lightpath. Για την μοντελοποίηση των φυσικών περιορισμών του δικτύου χρησιμοποιούνται αναλυτικές φόρμουλες. Η απόδοση του προτεινόμενου αλγορίθμου υπολογίστηκε διεξάγοντας εξομοιώσεις για μια παραλλαγή του DTnet δικτύου εισάγοντας τη μοναδιαία μήτρα κίνησης. Η απόδοση του αλγορίθμου κρίνεται ικανοποιητική όχι μόνο για μεσαία, αλλά και για μεγάλης κλίμακας δίκτυα παρέχοντας βέλτιστες λύσεις. Το μεγαλύτερο μέρος του χρόνου εκτέλεσης του αλγορίθμου, οφείλεται στον υπολογισμό του διαφανούς IA-RWA αλγόριθμου της δεύτερης φάσης. Σχετικά με την απόδοση των εξεταζόμενων αλγορίθμων της πρώτης φάσης, φαίνεται ότι ο αλγόριθμος που παρουσιάζει τα καλύτερα αποτελέσματα είναι αυτός που ελαχιστοποιεί τον μέγιστο αριθμό των χρησιμοποιούμενων αναγεννητών μεταξύ των διαφορετικών κόμβων αναγέννησης του σήματος. / Physical impairments in optical fiber transmission necessitate the use of regeneration at certain intermediate nodes, at least for certain lengthy lightpaths. We design and implement impairment-aware algorithms for routing and wavelength assignment (IA-RWA) in translucent optical networks. We focus on the offline version of the problem, where we are given a network topology, the available wavelengths, a traffic matrix and a (sparse) placement of 3R regenerators in the network (or, in a slightly different setting, the number of available transceivers at each network switch), and we aim at maximizing the number of connections served with adequate quality of transmission. We formulate the problem of choosing the sequence of regenerators to be used by non-transparent connections as a virtual topology design problem, and address it using various algorithms, ranging from an integer linear program (ILP) to simple heuristic algorithms. Once the sequence of regenerators to be used has been determined, we transform the traffic matrix by replacing non-transparent connections with a sequence of transparent connections that terminate and begin at the specified 3R intermediate nodes. Using the transformed matrix we then apply an IA-RWA algorithm designed for transparent (as opposed to translucent) networks to route the traffic. Connections that are blocked are re-routed using any remaining regenerator(s).

No description available.

Any unexpected disruption to WDM (Wavelength Division Multiplexing) based optical networks which carry data traffic at tera-bit per second may result in a huge loss to its end-users and the carrier itself. Thus survivability has been well-recognized as one of the most important objectives in the design of optical Internet. This thesis proposes a novel survivable routing architecture for the optical Internet. We focus on a number of key issues that are essential to achieve the desired service scenarios, including the tasks of (a) minimizing the total number of wavelengths used for establishing working and protection paths in WDM networks; (b) minimizing the number of affected working paths in case of a link failure; (c) handling large scale WDM mesh networks; and (d) supporting both Quality of Service (QoS) and best-effort based working lightpaths. To implement the above objectives, a novel path based shared protection framework namely Group Shared protection (GSP) is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy, and optimization is performed on these PGs. To the best of our knowledge this is the first work done in the area of group based WDM survivable routing approaches where not only the resource sharing is conducted among the PGs to achieve the best possible capacity efficiency, but also an integrated survivable routing framework is provided by incorporating the above objectives. Simulation results show the effectiveness of the proposed schemes.

Multi-relational learning has become popular due to the limitations of propositional problem definition in structured domains and the tendency of storing data in relational databases. As patterns involve multiple relations, the search space of possible hypotheses becomes intractably complex. Many relational knowledge discovery systems have been developed employing various search strategies, search heuristics and pattern language limitations in order to cope with the complexity of hypothesis space. In this work, we propose a relational concept learning technique, which adopts concept descriptions as associations between the concept and the preconditions to this concept and employs a relational upgrade of association rule mining search heuristic, APRIORI rule, to effectively prune the search space. The proposed system is a hybrid predictive inductive logic system, which utilizes inverse resolution for generalization of concept instances in the presence of background knowledge and refines these general patterns into frequent and strong concept definitions with a modified APRIORI-based specialization operator. Two versions of the system are tested for three real-world learning problems: learning a linearly recursive relation, predicting carcinogenicity of molecules within Predictive Toxicology Evaluation (PTE) challenge and mesh design. Results of the experiments show that the proposed hybrid method is competitive with state-of-the-art systems.

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No. of bitstreams: 2 Dissertação - Rubia Santos Corrêa - 2014.pdf: 2181864 bytes, checksum: f7194eae8a762b1a93fbddf736eda76d (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Climate changes is of global importance influencing local and international policy decisions. It is important that sectors and human activities that contribute to worsen the global warming scenario are identified. Nitrous oxide (N2O) is an important greenhouse gas, despite its low concentration in the atmosphere this gas stands out due to its long residence time and to potential for absorption of infrared radiation of its molecule and to its hence high of global warming potential. N2O in the atmosphere has the ability to absorb infrared radiation of the earth and increase the average temperature of the planet. As consequences we observe the effects of warming on many environmental disasters, changes in rainfall patterns, melting glaciers and other phenomena caused by climate disorders. The magnitudes of the gas fluxes coming from the farm system are relevant, highlighting the need to identify sources sinks of greenhouse gas emissions (GGE) in agriculture. In Brazil the most commonly used method for measuring the greenhouse gas is the static chamber. It is supposed that with this method the fluxes GGE are underestimated. In this work this hypothesis was tested by comparing the N2O fluxes obtained with manuals static chambers with those obtained by a micrometeorological method, the flux-gradient, and characterizing the dynamics of the flux of N2O in the Integrated Crop-Livestock system (ICL). The study was conducted at Embrapa Rice and Beans, in Santo Antônio de Goiás, in clay Rhodic Ferralsol typical, under ICL system the pasture phase. Initial studies have been made to define sampling times and best time to perform the sampling by the manual static chamber method. The sampling times used were 0, 15 and 30 minutes and the best period for routine sampling was around 10 am. In calculating fluxes, whenever possible the Hutchinson & Mosier function was used. When this function not was applied a simple linear function was used. The flux calculated by the linear function was considered when R2 was greater than or equal to 0.80. The measured fluxes by the two quantification methods manuals static chambers and flux-gradient were comparable, however in 69.77% of the assessed days the values positive obtained by the flux-gradient method were higher than those obtained by the manual static chamber method. As to the physical and chemical attributes of the soil, considering the entire period under study, in pasture soil, it was observed that N2O fluxes were positively correlated with the nitrate concentration, WFPS and the soil temperature. In the rainy season there was a positive correlation between N2O fluxes and WFPS of soil. In the dry season there was a positive correlation between N2O fluxes and the ammonium and nitrate concentrations of soil. During the study not was observed emission of N2O in of reference area, area this formed by a native forest fragment. / As mudanças do clima são de importância global influenciando decisões políticas locais e internacionais. É importante que sejam identificados os setores e as atividades antrópicas que contribuem para agravar o cenário do aquecimento global. O óxido nitroso (N2O) é um importante gás de efeito estufa, apesar de sua baixa concentração na atmosfera esse gás se destaca devido ao seu longo tempo de permanência e ao potencial de absorção de radiação infravermelha de sua molécula e, consequentemente, ao seu alto potencial de aquecimento global. O N2O presente na atmosfera tem capacidade de absorver radiação infravermelha da Terra e aumentar a temperatura média do planeta. Como consequências observam-se os efeitos do aquecimento em diversos desastres ambientais, mudanças nos padrões de chuvas, derretimento das geleiras e outros fenômenos provocados pelas desordens climáticas. As magnitudes dos fluxos de gases oriundos do sistema agrícola são relevantes, destacando-se a necessidade de identificar fontes e sumidouros de gases de efeito estufa (GEE) na agricultura. No Brasil o método mais comumente utilizado para a medição de fluxos de GEE é a câmara estática. Supõe-se que, com este método, os fluxos de GEE são subestimados. Neste trabalho esta hipótese foi testada comparando os fluxos de N2O obtidos com câmaras estáticas manuais com os obtidos por um método micrometeorológico, o fluxo-gradiente, além da caracterização da dinâmica do fluxo de N2O no sistema de integração lavoura-pecuária (ILP). O estudo foi realizado na Embrapa Arroz e Feijão, no município de Santo Antônio de Goiás, em Latossolo Vermelho Acriférrico típico, sob sistema ILP na fase pastagem. Estudos iniciais foram feitos para definir o tempo de amostragem dos fluxos e o melhor horário para a realização das amostragens pelo método da câmara estática manual. Os tempos de amostragem utilizados foram de 0, 15 e 30 minutos e o melhor período para a rotina de amostragem se concentrou em torno das 10 h. No cálculo dos fluxos, sempre que possível foi utilizada a função de Hutchinson & Mosier. Quando esta função não era aplicável foi utilizada uma função linear simples. O fluxo calculado através da função linear era considerado quando o R2 era maior ou igual a 0,80. Os fluxos medidos pelos dois métodos de quantificação, câmaras estáticas manuais e fluxo-gradiente foram comparáveis, entretanto em 69,77% dos dias avaliados os valores positivos obtidos através do método do fluxo-gradiente foram superiores aos obtidos pelo método da câmara estática manual. Quanto aos atributos físicos e químicos do solo sob pastagem, considerando o período em estudo, observou-se que os fluxos de N2O apresentaram correlação positiva com o teor de nitrato, EPPA e a temperatura do solo. Na estação chuvosa houve correlação positiva entre os fluxos de N2O e o EPPA do solo. Na estação seca foi observada correlação positiva entre os fluxos de N2O e os teores de amônio e nitrato do solo. Durante o estudo não foi observada emissão de N2O na área de referência, área esta formada por um fragmento de floresta nativa.

This thesis deals with an optimization of Triple play services and security in optical access networks. The first chapter provides theory basics which are necessary for results evaluation. The second chapter describes optical access networks with their parameters such as transmission speed, split ratio, line code, bit error rate etc. defined by ITU. Next chapter summaries the current state in optical networks construction field according to the European Union developing plan. The practical part of this thesis is divided into several subchapters. The significant part of the thesis is dedicated to the security of passive optical networks and design of proper security model for current networks. For this purpose, the unique parameter time propagation Tprop, with the novel security model was developed. Next part of the thesis provides an analysis of control traffic and data traffic in the gigabit passive optical networks. For a novel algorithm in activation process in gigabit passive optical networks the measurement results were used. The novel algorithm decreases the total time needed for this process. The last but one subchapter deals with an ILP model for Triple Play services. The last subchapter contains the own implementation of the transmission converge layer in VPIphotonics simulation tool.

Radio spectrum has become increasingly scarce due to the proliferation of new wireless communication services. This problem has been exacerbated by fixed bandwidth licensing policies that often lead to spectral underutilization. Cognitive radio networks (CRN) can address this issue using flexible spectrum management that permits unlicensed (secondary) users to access the licensed spectrum. Supporting real-time quality-of-service (QoS) in CRNs however, is very challenging, due to the random spectrum availability induced by the licensed (primary) user activity. This thesis considers the problem of real-time voice transmission in CRNs with an emphasis on secondary network ``friendliness''. Friendliness is measured by the secondary real-time voice capacity, defined as the number of connections that can be supported, subject to typical QoS constraints. The constant bit rate (CBR) air interface case is first assumed. An offline scheduler that maximizes friendliness is derived using an integer linear program (ILP) that can be solved using a minimum cost flow graph construction. Two online primary scheduling algorithms are then introduced. The first algorithm is based on shaping the primary spectral hole patterns subject to primary QoS constraints. The second applies real-time scheduling to both primary traffic and virtual secondary calls. The online scheduling algorithms are found to perform well compared to the friendliness upper bound. Extensive simulations of the primary friendly schedulers show the achievable secondary voice capacity for a variety of parameters compared to non-friendly primary scheduling. The thesis then considers the variable bit rate (VBR) air interface option for primary transmissions. Offline and online approaches are taken to generate a primary VBR traffic schedule that is friendly to secondary voice calls. The online VBR schedulers are found to perform well compared to the friendliness upper bound. Simulation results are presented that show the effect of the primary traffic load and primary network delay tolerance on the primary network friendliness level towards potential secondary voice traffic. Finally, secondary user friendliness is considered from an infrastructure deployment point of view. A cooperative framework is proposed, which allows the primary traffic to be relayed by helper nodes using decode-and-forward (DF) relaying. This approach decreases the primary traffic channel utilization, which, in turn, increases the capacity available to potential secondary users. A relay selection optimization problem is first formulated that minimizes the primary channel utilization. A greedy algorithm that assigns relay nodes to primary data flows is introduced and found to perform well compared to the optimum bound. Results are presented that show the primary network friendliness for different levels of primary channel utilization. / Dissertation / Doctor of Philosophy (PhD)

From the 1850s Glasgow was a major industrial, commercial and mercantile city, with notoriously poor working-class housing. During the 1915 Rent Strike many women physically resisted rent increases and prevented evictions from the tenements. The strikes ended when the Government passed the Rent Restrictions Act 1915, which returned rents to pre-war levels. This was in response to a political and working-class struggle that challenged the rule of law. Rather than focussing narrowly on the role of the women alone, or on the strike as inspiration for anti-capitalist resistance, the 2015 Centenary seemed opportune to examine why the Rent Strike was successful, its place in the longer struggle for decent housing, the role of the Independent Labour Party (ILP) and its leaders, and their collaborations with labour and women’s organisations. From the 1890s the ILP was central to labour’s campaign in elections and in fostering political collaboration with many groups representing labour. John Wheatley and Patrick Dollan, former miners, were leaders in strengthening the ILP organisation and its community relations. This collaborative structure supported the women leading the rent resistance in the tenements. It was also the platform for Wheatley and Dollan, nationally and municipally, to continue their life-long work to improve the housing and living standards of working people. Wheatley became Minister of Health in 1924 in Britain’s first Labour Government, and Dollan was Lord Provost in Glasgow’s first majority Labour Council in 1938. Glasgow’s systemic anti-Irish and anti-Catholic prejudice has, surprisingly, remained unexamined in relation to the Rent Strike. Two historians claimed, without presenting evidence, that bigotry was overcome or briefly transcended. The evidence reviewed here indicated that it did not go away, but that it had no impact on the Rent Strike as it simply offered no stimulus or opportunity to express the existing racist or religious prejudice. / Thesis / Master of Arts (MA) / Glasgow, with notoriously poor working-class housing, was a major centre in 1915 for British engineering, munitions and shipbuilding industries during the First World War. Women who lived in Glasgow’s tenements organised rent strikes and physically resisted rent increases and evictions. They were supported by the Independent Labour Party and the collaborations it developed before and during the war with organisations representing the interests of women and labour. These strikes, the rent agitations in England, and the threat of industrial action in Glasgow, forced the Government to pass the Rent Restrictions Act 1915, which limited rents to pre-war levels. Two former miners, John Wheatley and Patrick Dollan, were leaders in organising this class victory. They recognised the Act’s limitations and then worked nationally and municipally in the longer struggle for better working-class housing. Glasgow’s systemic anti-Irish and anti-Catholic bigotry did not disappear but played no significant role during the Rent Strike.

Avec l'évolution de la technologie, l'homme a procédé à la conception de systèmes de plus en plus complexes mais aussi de plus en plus sensibles aux défauts qui peuvent les affecter. Une procédure de diagnostic contribuant au bon déroulement du processus est ainsi nécessaire. Dans ce contexte, le but de cette thèse est le diagnostic des systèmes à événements discrets modélisés par des Réseaux de Petri Étiquetés (RdPE) partiellement observables. Sous l'hypothèse que chaque défaut est modélisé par le tir d'une transition non observable, deux approches de diagnostic à base d'estimation d'état sont développées. Une première approche composée de deux étapes consiste à estimer l'ensemble des marquages de base sur un horizon élémentaire glissant. La première étape consiste à déterminer un ensemble de vecteurs candidats à partir d'une approche algébrique. La deuxième étape consiste à éliminer les solutions candidates calculées qui ne sont pas associées à une trajectoire possible du RdPE. Comme l'ensemble des marquages de base pourra aussi être important, une deuxième approche de diagnostic évitera cet écueil en n'estimant pas les marquages. Une technique de relaxation des problèmes de Programmation Linéaire en Nombres Entiers (PLNE) sur un horizon fuyant est utilisée afin d'avoir un diagnostic en temps polynomial. / With the evolution of technology, humans have made available systems increasingly complex but also increasingly sensitive to faults that may affect it. A diagnostic procedure which contributes to the smooth running of the process is thus necessary. In this context, the aim of this thesis is the diagnosis of discrete event systems modeled by partially observed Labeled Petri Nets (LPNs). Under the assumption that each defect is modeled by the firing of an unobservable transition, two diagnostic approaches based on state estimation are developed. A first approach is to estimate the set of basis markings on a sliding elementary horizon. This approach is carried out in two steps. The first step is to determine a set of candidate vectors from an algebraic approach. The second step is to eliminate the calculated candidate solutions that are not associated with a possible trajectory of the LPN. As the set of basis markings can also be huge, a second diagnostic approach will avoid this pitfall by not estimating the markings. A relaxation technique of Integer Linear Programming (ILP) problems on a receding horizon is used to have a diagnosis in polynomial time.