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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

The influence of a central groove on static and dynamic characteristics of an annular liquid seal with laminar flow

Graviss, Matthew Sheridan 29 August 2005 (has links)
This thesis provides experimental static and dynamic results for four pairs of seals, including a pair of smooth seals and three pairs of centrally grooved seals. The grooved seals have groove depth to clearance ratios (Dg/C) of 5, 10, and 15. The radial clearance of each test seal is 0.0891 mm. Test conditions include three shaft rotational speeds from 4000 to 10000 rpm, three inlet oil pressures from 24 to 70 bars, and seal dimensionless eccentricities from 0 (centered) to 0.7. For each pair of test seals, dynamic results include stiffness and damping coefficients; static results include stator position, attitude angles, and seal leakage. Stiffness, damping, and leakage are compared among the seal pairs with various groove depths. Results show that all rotordynamic coefficients consistently decrease with increasing seal groove depths, and seal leakage remains constant through varying groove depths. Additionally, a comparison is made between experimental results of all test seals and XLLubeGT. XLLubeGT is a computer model developed at Texas A&M University, which uses a Reynolds equation + energy equation model to predict dynamic performance of a grooved seal. It operates on the assumption that the groove is large enough to create separate lands within the seal, creating a zero or negligible pressure perturbation across the seal. A comparison with XLLubeGT shows that even the seal with the largest groove depth tested is not deep enough to agree with XLLubeGT predictions.
92

The effects of revolutionary and Napoleonic policy on the artistic patrimony of Venice (1797 and 1806-1814)

Gietz, Nora January 2013 (has links)
This dissertation investigates the effects of Revolutionary (1797) and Napoleonic (1806-14) rule on the artistic patrimony of the city of Venice. Its aim is to explore just how far-reaching the spoliation of Venetian buildings was during the short lived Provisional Municipality, as well as in the wake of the suppressions and closures of parish churches, convents, monasteries, and confraternities during the eight years that Venice was part of the Italian Kingdom. Dealing with a vast amount of hitherto unpublished evidence, the dissertation sheds light on the motivations for, and the logistics of, the appropriation, transfer, and disposal of artworks and liturgical furnishings. It investigates the various government bodies involved, and their hierarchies and responsibilities, while a number of case studies detail how the suppressions themselves were carried out, and how the buildings and their contents were treated and affected in their aftermath. The two distinct periods in the history of Venice saw great differences in approaches to artistic patrimony: in 1797, a limited number of artworks had been allocated to France in a peace treaty, while, later on, the sheer quantities of objects made it close to impossible to achieve a systematic method. Using archival materials such as official correspondence, and inventories and valuations drawn up by government delegates, alongside published eighteenth- and nineteenth-century guidebooks of Venice, the thesis provides a detailed account of the effects of Revolutionary and Napoleonic rule on the city’s artistic heritage. In order to do so, it is divided into four chapters. The first two are more general in scope, the first tracing the events of 1797, and the activity of the Committee of Public Instruction and Commission Temporaire des Arts during this time, the second exploring the Demanio administration of state property, and the roles of delegates Pietro Edwards and Giuseppe Baldassini, as well as private sales and auctions, and the removal and transportation of objects from suppressed institutions. Case studies of two diocesan churches, Santa Marina and San Nicolò di Castello, and two monastic foundations, Santa Maria dei Frari and Santa Maria dei Servi, as well as eight scuole grandi follow. Venetian buildings and their patrimony have not yet been studied as much in detail for the period in question as this dissertation endeavours to do. These microcosmic studies will contribute greatly to the understanding of the effects of Revolutionary and Napoleonic France on the artistic patrimony of Europe.
93

Distributed generation and demand side management : applications to transmission system operation

Hayes, Barry Patrick January 2013 (has links)
Electricity networks are undergoing a period of rapid change and transformation, with increased penetration levels of renewable-based distributed generation, and new influences on electricity end-use patterns from demand-manageable loads and micro-generation. This creates a number of new challenges for the delivery of a reliable supply of electrical energy. The main aim of this PhD research is to provide a methodology for a more detailed and accurate assessment of the effects of wind-based distributed generation (DG) and demand side management (DSM) on transmission network operation. In addition, the work investigates the potential for co-ordinated implementation and control of DG and DSM to improve overall system performance. A significant amount of previous literature on network integration of DG and DSM resources has focused on the effects at the distribution level, where their impact is direct and often easily observed. However, as penetration levels increase, DG and DSM will have a growing influence on the operation and management of the bulk transmission system. Modelling and analysis of the impact of embedded and highly-dispersed DG and DSM resources at transmission voltage levels will present a significant challenge for transmission network operators in the future. Accordingly, this thesis presents a number of new approaches and methodologies allowing for a more accurate modelling and aggregation of DG and DSM resources in power system studies. The correct representation of input wind energy resources is essential for accurate estimation of power and energy outputs of wind-based DG. A novel modelling approach for a simple and accurate representation of the statistical and temporal characteristics of the wind energy resources is presented in the thesis. An "all-scale" approach to modelling and aggregation of wind-based generation is proposed, which is specifically intended for assessing the impact of embedded wind generation on the steady state performance of transmission systems. The methodology allows to include in the analysis wind-based generation at all scales and all levels of implementation, from micro and small LV-connected units, through medium-size wind plants connected at MV, up to large HV-connected wind farms. The thesis also presents an assessment of the potential for DSM in the UK residential and commercial sectors, based on the analysis and decomposition of measured demands at system bulk supply points into the corresponding load types. Using a section of the Scottish transmission network as a case study, a number of DG and DSM scenarios are investigated in detail. These results demonstrate the importance of accurately modelling the interactions between the supply system and various DG and DSM schemes, and show that the aggregated effects of highly-distributed DG and DSM resources can have significant impacts on the operation of the bulk transmission system.
94

Absolute beginners of the 'Belpaese' : Italian youth culture and the Communist Party in the years of the economic boom

Perfetti, Guglielmo January 2018 (has links)
This study has the aim of exploring aspects of youth culture in Italy during the economic boom of the late 1950s and early 1960s. Its theoretical framework lies between the studies around Italian youth culture and those around the Italian Communist Party (PCI), investigating the relationship between young people and contemporary society and examining, for the first time, the relationship of the former with the PCI, its institutions and media organs. The arrival of an Anglo-American influenced pop culture (culture transmitted by the media and targeted at young people) and of its market, shaped the individualities of part of the pre-baby boomers that, finally, were able to create bespoke identities somewhat disconnected from the traditional party-related narrative while remaining on the left of the political spectrum. Pop symbols that blossomed in the late 1950s, such as the striped t-shirt, would characterise the style of young protesters who included them in their collective imagination from the early 1960s onwards. Simultaneously, a flourishing pop market gave space to other cultural experiences including Cantacronache, a group of young musicians based in Turin who vividly depicted Italy of the boom through their lyrics. Their efforts can be read as belonging to a pop market that finally starts to open up towards new musical stimuli. They aimed to make their music available beyond the circle of left-wing activism as well and they were produced by a label linked to the PCI that in those years was reshaping its approach towards society, getting rid of its radical fringes and opening to a dialogue with diverse strata of the public, including young people, women and non-members. The thesis investigates how the Communists and its Youth Federation (FGCI), reacted to the development of youth culture as an aspect of modernisation in general. Through an examination of the party’s approach to the youth revolts of the early 1960s and of its formal documents targeted at young people in general, we analyse how – and how successfully – the Communists tried to engage with young people while often, internal strands, the monolithic nature of the party and other elements, posed severe obstacles in meeting their demands, creating a fracture that would grow in the following years. The thesis also investigates how the party’s attempt to address young people was translated into the promotion of magazines in which serious political topics were discussed alongside other themes such as investigations into society and into the “questione giovanile.” In this respect, we will see how the FGCI journal Nuova generazione tried, in the late 1950s, to take account of youth inclinations paying attention to other important topics such as the emancipation of young women. The generation we look at is the first to claim the right to build its individual identities by drawing on pop culture and modernisation, developing codes and behaviours that pulled away from those set by the institutions.
95

Memory, perception, reception : following the fate of the victims of Italy's anni di piombo through the writing of their children

Ryder, Emily Jennifer Hana January 2015 (has links)
This thesis considers some of those who were killed in politically-motivated attacks, often referred to as ‘terrorism’, which took place during Italy’s anni di piombo. Six works written by victims’ children will be used as a lens through which to examine the collective memory and the victims’ place therein. In recent years, there has been a shift in the way that this period of Italian history - the anni di piombo – has been remembered. Where previously the perpetrators of the violence of those years dominated public discourse, in the last decade the principal narrative has become more victim-centred. The biographical works written by victims’ children have inevitably contributed to this change in the memory narrative. The techniques employed in their writing in order to change the existing public image of their fathers will be analysed in this thesis, along with certain themes that recur throughout the six works and broader victim-centred discussion of this period. Analysis begins with a thorough outline of the political and historical context of the anni di piombo, including case studies of two of the most famous victims of this period and a consideration of the written works of some of the former terrorists. Following this preliminary contextualisation, each of the six books and their authors will be studied in detail to provide a foundation for the analysis contained in the final three chapters. The themes examined in the second half of the thesis are second-generation writing, forgiveness and commemoration. Using these themes as a framework, a rigorous investigation of the place that the victims hold in collective memory; the role their children’s writing has played in shaping and maintaining their public image and the longer-term impact that these changes can be seen to have had within a broader societal and political perspective is undertaken. On the basis of this study, it is evident that the victims’ place in the collective memory of the anni di piombo has changed dramatically since that period of violence concluded. The victims’ children have been very significant in enacting this change and their writing has placed them in a position from which they can continue to exert influence and promote a victim-centred approach to history.
96

Role of a-Subunit VISIT-DG Sequence Residues Ile-346 and Ile-348 in the Catalytic Sites of Escherichia Coli ATP Synthase.

Zhao, Chao 07 May 2011 (has links) (PDF)
F1FO-ATP synthase is the primary source of cellular energy production in most living organisms. Malfunction of this enzyme is implicated in diseases. There are many functional motifs in and around the catalytic sites of this enzyme. One of them is the highly conserved α-subunit VISIT-DG sequence that is close to the Pi binding subdomain. The questions arise "Are they involved in Pi binding? Or are they there simply for the structural integrity of the catalytic sites?" Here, αIle-346and αIle-348, two important residues of the conserved VISIT-DG sequence, are discussed. Each residue was mutated to A/R/D/Q. Growth assays in limiting glucose media and on succinate plates suggests αIle-346 and αIle-348 are critical for the normal enzymatic function (oxidative phosphorylation). And the biochemical assays do suggest both αI-346 and αI-348 are required to maintain catalytic site, involved in Pi binding indirectly, but αI-348 plays more important role than αI-346.
97

Technical and Economic Feasibility Considerations of Alternative Energy Distributed Generation

Brahmandhabheri, Vishwanatha Raju 08 May 2004 (has links)
The pressing needs for cost effective electric power that provides both high reliability and high quality is creating an opportunity for alternative energy distributed generation (DG). To determine the economic and technical feasibility of such alternative energy distributed generation facilities, electric power customers must understand their electric usage patterns, economic considerations, local alternative fuel supplies and available DG technologies. This thesis discusses the economic and technical feasibility of establishing a distributed generation installation. As a part of technical feasibility, an evaluation has been done to compare DG size and location impact on the operation of the I 13 node test distribution systems. This evaluation was carried out by performing the distribution power flow that provides the information about voltage profile, losses in the system and feeder power factor. This information was used to determine the optimal location of DG in the test distribution system. Additionally, this part focuses on the importance of power utilization assessment in distributed generation planning. It also discussed the load utilization assessment that focus on step-by-step analysis of load profiles of different facilities such as Choctaw Laundromat, Choctaw Geyser Falls (water park) and Golden Moon Casino. The second part of this thesis?s work resulted in an informative and useful economic analysis tool, DG-ECON with which the user can document the study results and analyze them for economic feasibility with minimal effort. The economic feasibility of a biomass-based renewable energy installation is clearly shown by developing a user interface spreadsheet in Microsoft Excel. The spreadsheet calculates project-screening information in the form of a 20-year life cycle cost analysis. This cost analysis that enables users to define projects that are most energy efficient and offer the greatest financial benefit. The emphasis is on the user interface features of the application to make the application as user friendly as possible. The application has both numerical and graphical data representation using some of the features of Microsoft Visual Basic.
98

Distribution Network Reconfiguration Considering Security-Constraint and Multi-DG Configurations

Anthony, Ikenna O., Mokryani, Geev, Zubo, Rana H.A., Ezechukwu, O.A. 11 May 2021 (has links)
Yes / This paper proposes a novel method for distribution network reconfiguration considering security-constraints and multi-configuration of renewable distributed generators (DG). The objective of the proposed method is to minimize the total operational cost using security constrained optimal power flow (SCOPF). The impact of multi-configuration of renewable DGs in a meshed network is investigated. In this work, lines were added to the radial distribution network to analyse the network power flow in different network configurations. The added lines were connected to the closest generator bus which offered least operating cost. A 16-bus UK generic distribution system (UKGDS) was used to model the efficiency of the proposed method. The obtained results in multi-DG configuration ensure the security of the network in N-1 contingency criteria.
99

Dielectric Resonator Antennas (DRA) for satellite and body area network applications / Étude et réalisation de antennes diélectriques pour les applications satellitaires et corps (BAN)

Alam, Muhammad Faiz 02 July 2012 (has links)
Dans cette thèse, on vise deux types d'applications de l’antenne à résonateur diélectrique (DRA): 1) La réalisation d’un élément rayonnant pour un réseau phasé embarqué sur un véhicule terrestre ou un avion. Cet élément de base requiert une couverture en élévation supérieure à celle des éléments imprimés pour permettre une poursuite typique comprise entre ±70°. La couverture dans un cône large est assurée avec une bonne pureté de polarisation circulaire en alimentant l’antenne à travers deux ouvertures à fente en H orthogonales parfaitement découplées en bande X. 2) La deuxième structure est destinée à la diversité d’antennes dans le contexte des réseaux corporels embarqués ou Body Area Network (BAN). L’antenne à diversité combine une antenne fente en boucle avec un DRA ce qui permet dans un espace compact de réaliser des diagrammes de type “broadside” et “endfire” respectivement. Les alimentations considérées sont de 2 types; Soit purement planaire (microruban et coplanaire) soit mixte en combinant une alimentation coaxiale et une alimentation coplanaire. Caractéristiques principales des antennes à résonateur diélectrique (DRA): Pour répondre aux attentes des utilisateurs en termes de débit, les systèmes de communication sans fils se tournent vers des fréquences de plus en plus élevées. La conséquence de cette montée en fréquence est notamment l’augmentation des pertes au niveau des éléments conducteurs et donc une diminution de l’efficacité globale des systèmes de communication. Dans ces circonstances, les DRA offre de meilleurs résultats par rapport à d'autres familles d'antennes à base d’éléments métalliques. De plus, les DRA offrent des pertes diélectriques négligeables, elles sont peu sensibles aux variations de température et s’intègrent facilement sur des technologies de fabrication planaires / Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios
100

Simulation und Optimierung neuartiger SOI-MOSFETs

Herrmann, Tom 21 December 2010 (has links) (PDF)
Die vorliegende Arbeit beschreibt die Berechnung und Optimierung von Silicon-On-Insulator-Metal-Oxide-Semiconductor-Field-Effect-Transistors, einschließlich noch nicht in Massenproduktion hergestellter neuartiger Transistorarchitekturen für die nächsten Technologiegenerationen der hochleistungsfähigen Logik-MOSFETs mit Hilfe der Prozess- und Bauelementesimulation. Die neuartigen Transistorarchitekturen umfassen dabei vollständig verarmte SOI-MOSFETs, Doppel-Gate-Transistoren und FinFETs. Die statische und dynamische Leistungsfähigkeit der neuartigen Transistoren wird durch Simulation bestimmt und miteinander verglichen. Der mit weiterer Skalierung steigende Einfluss von statistischen Variationen wird anhand der Oberflächenrauheit sowie der Polykantenrauheit untersucht. Zu diesem Zweck wurden Modelle für die Generierung der Rauheit erarbeitet und in das Programmsystem SIMBA implementiert. Die mikroskopische Rauheit wird mit der makroskopischen Bauelementesimulation kombiniert und deren Auswirkungen auf die Standardtransistoren und skalierte Bauelemente aufgezeigt. Zudem erfolgt eine ausführliche Diskussion der Modellierung mechanischer Verspannung und deren Anwendung zur Steigerung der Leistungsfähigkeit von MOSFETs. Die in SIMBA implementierten Modelle zur verspannungs-abhängigen Änderung der Ladungsträgerbeweglichkeit und Lage der Bandkanten werden ausführlich dargestellt und deren Einfluss auf die elektrischen Parameter von MOSFETs untersucht. Weiterhin wird die Verspannungsverteilung für verschiedene Herstellungsvarianten mittels der Prozess-simulation berechnet und die Wirkung auf die elektrischen Parameter dargestellt. Exponential- und Gaußverteilungsfunktionen bilden die Grundlage, um die mechanische Verspannung in der Bauelementesimulation nachzubilden, ohne die Verspannungsprofile aus der Prozesssimulation zu übernehmen. Darüber hinaus werden die Grenzfrequenzen der Logiktransistoren in Bezug auf die parasitären Kapazitäten und Widerstände und zur erweiterten MOSFET-Charakterisierung dargestellt.

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