Distributed infrastructures (e.g., water networks and electric Grids) are difficult to manage due to their scale, lack of accessibility, complexity, ageing and uncertainties in knowledge of their structure. In addition they are subject to loads that can be highly variable and unpredictable and to accidental events such as component failure, leakage and malicious tampering. To support in-field operations and central management of these infrastructures, the availability of consistent and up-to-date knowledge about the current state of the network and how it would respond to planned interventions is argued to be highly desirable. However, at present, large-scale infrastructures are “data rich but knowledge poor”. Data, algorithms and tools for network analysis are improving but there is a need to integrate them to support more directly engineering operations. Current ICT solutions are mainly based on specialized, monolithic and heavyweight software packages that restrict the dissemination of dynamic information and its appropriate and timely presentation particularly to field engineers who operate in a resource constrained and less reliable environments. This thesis proposes a solution to these problems by recognizing that current monolithic ICT solutions for infrastructure management seek to meet the requirements of different human roles and operating environments (defined in this work as field and central sides). It proposes an architectural approach to providing dynamic, predictive, user-centric, device and platform independent access to consistent and up-to-date knowledge. This architecture integrates the components required to implement the functionalities of data gathering, data storage, simulation modelling, and information visualization and analysis. These components are tightly coupled in current implementations of software for analysing the behaviour of networks. The architectural approach, by contrast, requires they be kept as separate as possible and interact only when required using common and standard protocols. The thesis particularly concentrates on engineering practices in clean water distribution networks but the methods are applicable to other structural networks, for example, the electricity Grid. A prototype implementation is provided that establishes a dynamic hydraulic simulation model and enables the model to be queried via remote access in a device and platform independent manner.This thesis provides an extensive evaluation comparing the architecture driven approach with current approaches, to substantiate the above claims. This evaluation is conducted by the use of benchmarks that are currently published and accepted in the water engineering community. To facilitate this evaluation, a working prototype of the whole architecture has been developed and is made available under an open source licence.

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<p>This licentiate thesis work investigates two medium access control (MAC) methods, when used in traffic safety applications over vehicular <em>ad hoc</em> networks (VANETs). The MAC methods are carrier sense multiple access (CSMA), as specified by the leading standard for VANETs IEEE 802.11p, and self-organizing time-division multiple access (STDMA) as used by the leading standard for transponders on ships. All vehicles in traffic safety applications periodically broadcast cooperative awareness messages (CAMs). The CAM based data traffic implies requirements on a predictable, fair and scalable medium access mechanism. The investigated performance measures are <em>channel access delay</em>, <em>number of consecutive packet drops</em> and the <em>distance between concurrently transmitting nodes</em>. Performance is evaluated by computer simulations of a highway scenario in which all vehicles broadcast CAMs with different update rates and packet lengths. The obtained results show that nodes in a CSMA system can experience <em>unbounded channel access delays</em> and further that there is a significant difference between the best case and worst case channel access delay that a node could experience. In addition, with CSMA there is a very high probability that several <em>concurrently transmitting nodes are located close to each other</em>. This occurs when nodes start their listening periods at the same time or when nodes choose the same backoff value, which results in nodes starting to transmit at the same time instant. The CSMA algorithm is therefore both <em>unpredictable</em> and <em>unfair</em> besides the fact that it <em>scales badly</em> for broadcasted CAMs. STDMA, on the other hand, will always grant channel access for all packets before a predetermined time, regardless of the number of competing nodes. Therefore, the STDMA algorithm is <em>predictable</em> and <em>fair</em>. STDMA, using parameter settings that have been adapted to the vehicular environment, is shown to outperform CSMA when considering the performance measure <em>distance between concurrently transmitting nodes</em>. In CSMA the distance between concurrent transmissions is random, whereas STDMA uses the side information from the CAMs to properly schedule concurrent transmissions in space. The price paid for the superior performance of STDMA is the required network synchronization through a global navigation satellite system, e.g., GPS. That aside since STDMA was shown to be scalable, predictable and fair; it is an excellent candidate for use in VANETs when complex communication requirements from traffic safety applications should be met.</p>

This thesis argues that George MacDonald's literary influence upon C. S. Lewis-concerning the themes of pain, suffering, evil and goodness-was transforming and long-lasting. It is argued in the opening chapter that MacDonald's work had a great deal to do with the change in young Lewis's imagination, helping to convert him from a romantic doubter to a romantic believer in God and his goodness. A review of both writers' first works suggests that such influence may have begun earlier in Lewis's career than has been noticed. The second chapter examines how both authors contended with the problems that pain and suffering present, and how both understood and presented the nature of faith. Differences in their treatment of these subjects are noted, but it is argued that these views and depictions share fundamental elements, and that MacDonald's direct influence can be demonstrated in particular cases. The view that MacDonald was primarily a champion of feelings is challenged, as is the idea that either man's later writing displays a loss of faith in God and his goodness. The third chapter, in specifically refuting the assertion that MacDonald's view of evil was inclusive in the Jungian or dualistic sense, shows how both authors' work maintains an unmistakable distinction between evil fortune and moral evil. The next two chapters examine fundamental similarities in their treatment of evil and goodness. Special care is taken in these two chapters to trace MacDonald's direct influence, especially regarding the differences they believed existed between hell's Pride and what they believed God to be. The fifth chapter reviews their ideas and depictions of heaven in summing up the study's argument concerning the overall influence of MacDonald's writing upon Lewis's imagination-in particular the change in Lewis's understanding of the relations between Spirits, Nature, and God.

This licentiate thesis work investigates two medium access control (MAC) methods, when used in traffic safety applications over vehicular ad hoc networks (VANETs). The MAC methods are carrier sense multiple access (CSMA), as specified by the leading standard for VANETs IEEE 802.11p, and self-organizing time-division multiple access (STDMA) as used by the leading standard for transponders on ships. All vehicles in traffic safety applications periodically broadcast cooperative awareness messages (CAMs). The CAM based data traffic implies requirements on a predictable, fair and scalable medium access mechanism. The investigated performance measures are channel access delay, number of consecutive packet drops and the distance between concurrently transmitting nodes. Performance is evaluated by computer simulations of a highway scenario in which all vehicles broadcast CAMs with different update rates and packet lengths. The obtained results show that nodes in a CSMA system can experience unbounded channel access delays and further that there is a significant difference between the best case and worst case channel access delay that a node could experience. In addition, with CSMA there is a very high probability that several concurrently transmitting nodes are located close to each other. This occurs when nodes start their listening periods at the same time or when nodes choose the same backoff value, which results in nodes starting to transmit at the same time instant. The CSMA algorithm is therefore both unpredictable and unfair besides the fact that it scales badly for broadcasted CAMs. STDMA, on the other hand, will always grant channel access for all packets before a predetermined time, regardless of the number of competing nodes. Therefore, the STDMA algorithm is predictable and fair. STDMA, using parameter settings that have been adapted to the vehicular environment, is shown to outperform CSMA when considering the performance measure distance between concurrently transmitting nodes. In CSMA the distance between concurrent transmissions is random, whereas STDMA uses the side information from the CAMs to properly schedule concurrent transmissions in space. The price paid for the superior performance of STDMA is the required network synchronization through a global navigation satellite system, e.g., GPS. That aside since STDMA was shown to be scalable, predictable and fair; it is an excellent candidate for use in VANETs when complex communication requirements from traffic safety applications should be met.

In this project we review the method of using c-extremization and computing anomalies to obtain AdS/CFT theories. We start with a quick introduction to CFT's and AdS/CFT correspondence which gives us the tools to later understand the 2D N= (2,0) SCFT and its gravity duals in particular AdS_5xS^5 and AdS_7xS^4 compactified on Riemann surfaces.

Landscape in Roman literature is manifest with symbolic potential: in particular, Vergil and Ovid respond to ideologically loaded representations of abundance in nature that signal the dawn of the Augustan golden age. Vergil's Eclogues foreground a locus amoenus landscape which articulates both the hopes of the new age as well as the political upheaval that accompanied the new political regime; Ovid uses the same topography in order to suggest the arbitrary and capricious use of power within a deceptively idyllic landscape. Moreover, for Latin poets, depictions of landscape are themselves sites for poetic reflection as evidenced by the discussion of landscape ecphrases in Horace's Ars Poetica. My thesis focuses upon the depiction and refiguration of the locus amoenus landscape in the post-Augustan epics of the first century AD: Lucan's Bellum Civile, Valerius Flaccus' Argonautica, Statius' Thebaid and Silius Italicus' Punica. Landscape in these poems retains the moral, political and metapoetic force evident in the Augustan archetypes. However, I suggest that Lucan's Neronian Bellum Civile fundamentally refigures the landscapes of Latin epic poetry, inscribing the locus amoenus with the nefas of civil war in such a manner that it redefines the perception of landscape in the succeeding Flavian poets. Lucan perverts the landscape, making the locus horridus, a landscape of horror, fear and disgust, the predominant landscape of Latin epic; consequently, the poems of Valerius, Statius and Silius engage with Lucan's refiguration of landscape as a means of expressing the horror of civil war. In the first part of my thesis I examine archetypal landscapes, including those of the Augustan poets and Lucan's Bellum Civile. Taking an approach which engages with literary reception theory and the concept of the â horizon of expectationâ as a framework within which literary topographies can be understood as articulating a response to the thematics of civil war, in the second part of my thesis I demonstrate the manner in which landscapes represent a coherent and paradigmatic response to Lucan's imposition of his civil war narrative within the literary landscape of Roman literature.