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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.
11

Gultekin, Burhan 01 September 2012 (has links) (PDF)
This research and development work deals with the design methodology for Cascaded Multilevel Converter (CMC) based Transmission STATCOM (TSTATCOM) and development of a &plusmn / 12MVAR, 12kV line-to-line wye-connected, 11-level CMC. This CMC module constitutes the basic building block of TSTATCOM systems. Sizing of the CMC module, number of H-Bridges in each phase of the CMC, AC voltage rating of the CMC, the number of paralleled CMC modules in the T-STATCOM system, optimum value of series filter reactors and determination of busbar in the power grid to which the T-STATCOM system is going to be connected are also discussed in the thesis in view of IEEE Std.519-1992, current status of HV IGBT technology and the required reactive power variation range for the T-STATCOM application. In the field prototype of the CMC module, the AC voltages are approximated to sinusoidal waves by Selective Harmonic Elimination Method (SHEM) and by the use of an optimized series input filter reactor. The use of n number of HBs in each phase provides us n number of freedom in the application of SHEM. One of them is allocated to the fundamental component while n-1 is for the elimination of low order harmonics. Since n is chosen to five in the prototype system, 5th, 7th,11th and 13th harmonic components are successfully eliminated in the AC voltage waveforms of the CMC module. The equalization of DC link capacitor voltages is achieved according to Modified Selective Swapping (MSS) algorithm. MSS is applied every 400&mu / s period if needed to obtain a perfect equalization of DC link capacitor voltages at the expense of higher switching frequency and hence switching losses. In this research work, an L-shaped laminated bus has been designed and the HV IGBT driver circuit has been modified for optimum switching performance of HV IGBT modules in each HB circuit. The performances of the HB circuit and the resulting 11-level CMC module have been obtained not only in the laboratory but also in the field. Design works for HB and the CMC are based on MATLAB and PSCAD simulations. The laboratory and field performance of the HB circuit and CMC module is found to be satisfactory and quite consistent with the theoretical results and design objectives. In addition to these, 154 kV, &plusmn / 50MVAr T-STATCOM prototype has been designed, implemented and installed at Sincan Transformer Substation-Ankara primarily for the purposes of reactive power compensation and terminal voltage regulation. The T-STATCOM prototype is composed of five parallel operated CMC modules developed within the scope of this PhD thesis research work. The T-STATCOM configuration permits the operation of any number of CMC modules in the range from one to five for experimental purposes. The performance of this T-STATCOM system is also presented in this PhD thesis as a sample application.
12

Estudis sobre el Computus Cottonianus

Gómez i Pallarès, Joan 20 June 1996 (has links)
Estudis paleogràfics de comentari textual i de tot tipos per tal d'esbrinar la naturalesa de l'anomenat per A. Cordoliani Computus Cottonianus als mss. British Museum Cotton Caligula A XV, Paris, BN, nal, 2169 i León, Bibl. de la Catedral n.8. El text del primer ms. no té res a veure amb el dels altres dos: transmet els Argumenta paschalia de Dionysius Exiguus i s'ha de relacionar amb una tradició insular. Els altres dos difonen també obres de Dionís però són mss. visigòtics. La segona part de la tesi posa de manifest la relació del ms. cottonià amb altres mss. de còmput eclesiàstic de tradició insular (per exemple, Oxford, Bodleian Library, Bodl. 309; id. Digby 63; Paris, BN, lat. 16361; Bern 610; Besancon 186; Milano, Ambros. H 150 etc.) i analitza i posa en relació el contingut de tots ells (13 en total) per tal d'oferir una visió del còmput insular prebèdic. / Estudios paleograficos de comentario textual y de todo tipo para dilucidar la verdadera naturaleza del llamado por a. Cordiliani computus cottonianus en los mss. Brit. Mus. Cotton caligula axv; paris bn nat-. 2169 i leon catedral 8. El texto del primer ms. No tiene nada que ver con el de los otros dos: difunde los argumenta paschalia de dionysius exiguus y entronca con una tradicion insular mientras que los otros dos difunden tambien obra de dionisio pero son mss. Visigoticos. La segunda parte de la tesis pone de manifiesto la relacion del ms. Cottoniano con otros mss. De computo eclesiastico de tradicion insular (por ejemplo ms. Oxford bodleian library bodl. 309 id. Di6by 63; paris bn lat. 16361; bern 610; besancon 186; milano ambros. H 150 etc...) Y analiza y pone en relacion el contenido de todos ellos (13 en total) para ofrecer una vision del computo insular pre-bedico.
13

Diagnosis System Conceptual Design Utilizing Structural Methods : Applied on a UAV’s Fuel System / Användande av strukturella metoder vid design av koncept till diagnossystem : Tillämpat på bränslesystemet i en UAV

Axelsson, Tobias January 2004 (has links)
To simplify troubleshooting and reliability of a process, a diagnosis system can supervise the process and alarm if any faults are detected. A diagnosis system can also identify one, or several faults, i.e. isolate faults, that may have caused the alarm. If model-based diagnosis is used, tests based on observations from the process are compared to a model of the process to diagnose the process. It can be a hard task to find which tests to be used for maximal fault detection and fault isolation. Structural Methods require not very detailed knowledge of the process to be diagnosed and can be used to find such tests early in the design of new processes. Sensors are used to get observations of a process. Therefore, sensors placed on different positions in the process gives different possibilities for observations. A specific set of sensors are in this work called a sensor configuration. This thesis contributes with a method to predict and examine the fault detection and fault isolation possibility. By using these two diagnosis properties, a suitable sensor configuration is computed and tests to be used in a future diagnosis system are suggested. For this task an algorithm which can be used in the design phase of diagnosis systems, and a Matlab implementation of this algorithm are described. In one part of this work the Matlab implementation and the algorithm are used to study how a model-based diagnosis-system can be used to supervise the fuel system in an Unmanned Aerial Vehicle (UAV).
14

Assessment of Marine Conditions for Logistics, Operation Envelope and Weather Window for Offshore Projects

Rajesh, Edwin January 2011 (has links)
This thesis describes an assessment of offshore wind farms using a Matlab tool Marine System simulator. This tool helps to analyse the Vessel motion according to different wave heights. From this assessment one can know the correct weather window for offshore operation and other possible techniques to reduce the time delay in operation. This tool is used to simulate a supply vessel motion according to different wave heights. The chosen supply vessel is the default supply vessel in the simulator.
15

Dynamics of One-Dimensional Maps: Symbols, Uniqueness, and Dimension

Brucks, Karen M. (Karen Marie), 1957- 05 1900 (has links)
This dissertation is a study of the dynamics of one-dimensional unimodal maps and is mainly concerned with those maps which are trapezoidal. The trapezoidal function, f_e, is defined for eΣ(0,1/2) by f_e(x)=x/e for xΣ[0,e], f_e(x)=1 for xΣ(e,1-e), and f_e(x)=(1-x)/e for xΣ[1-e,1]. We study the symbolic dynamics of the kneading sequences and relate them to the analytic dynamics of these maps. Chapter one is an overview of the present theory of Metropolis, Stein, and Stein (MSS). In Chapter two a formula is given that counts the number of MSS sequences of length n. Next, the number of distinct primitive colorings of n beads with two colors, as counted by Gilbert and Riordan, is shown to equal the number of MSS sequences of length n. An algorithm is given that produces a bisection between these two quantities for each n. Lastly, the number of negative orbits of size n for the function f(z)=z^2-2, as counted by P.J. Myrberg, is shown to equal the number of MSS sequences of length n. For an MSS sequence P, let H_ϖ(P) be the unique common extension of the harmonics of P. In Chapter three it is proved that there is exactly one J(P)Σ[0,1] such that the itinerary of λ(P) under the map is λ(P)f_e is H_ϖ(P). In Chapter four it is shown that only period doubling or period halving bifurcations can occur for the family λf_e, λΣ[0,1]. Results concerning how the size of a stable orbit changes as bifurcations of the family λf_e occur are given. Let λΣ[0,1] be such that 1/2 is a periodic point of λf_e. In this case 1/2 is superstable. Chapter five investigates the boundary of the basin of attraction of this stable orbit. An algorithm is given that yields a graph directed construction such that the object constructed is the basin boundary. From this we analyze the Hausdorff dimension and measure in that dimension of the boundary. The dimension is related to the simple β-numbers, as defined by Parry.
16

Analysis of post-tensioned concrete box-girder bridges : A comparison of Incremental launching and Movable scaffolding system

El Hamad, Hamad, Tanhan, Furkan January 2018 (has links)
When designing a bridge it is of high importance that the geometry for the cross section is optimized for the structure. This is partly due to the influence of the amount of material needed and its impact on the budget and environment. The influence of choosing the right amount of each material lies in the unit-price of the different material, where they can differ significantly. The Swedish Transport Administration, Trafikverket, has ordered the construction of Stockholm Bypass which is one of Swedens largest infrastructure project and is valued to 27.6 billion SEK according to the price index of the year 2009. The infrastructure project is divided into multiple projects where one of them is assigned to Implenia and Veidekke through a joint venture (Joint venture Hjulsta, JVH) and is valued to nearly 800 MSEK. The reference bridge that is used in the analysis of the master’s thesis is a part of the project. The aim of this masters thesis was to analyze and compare the two construction methods, mov- able scaffolding system (MSS) and incremental launching for the reference bridge with respect to amount post-tensioning and slenderness. Furthermore, an economical comparison between the two construction methods was carried out based on the obtained results. The analysis of the MSS was carried out by modeling the reference bridge structure in the finite element software SOFiSTiK AG. The bridge was modeled with different cross section height, i.e. different slenderness where the optimal amount of post-tension tendons could be determined by iteration until stress conditions from the Eurocode were fulfilled. For the incremental launching method, a numerical analysis was performed. The optimal amount of required post-tensioning was evaluated in the construction stages and final stages with different construction heights i.e. different values of slenderness. A cost analysis was also performed where the aim was to analyze how the total cost of the construc- tion of the bridge would be influenced by the different slenderness of the bridge as a comparison for the two construction methods. This was done by dividing the costs into fixed costs and variable costs. The results showed that the structural rigidity had a large influence on the required amount of prestressing steel for both construction methods. In other words, the smaller the cross section the more prestressing steel was required. Incremental launching proved to require a much greater amount of (PT) tendons compared to the MSS although the identical cross sections and properties for both methods, except for the PT. The prestressing for incremental launching is generally by centrical prestressing during the construction stages. A intersection point was obtained in the cost analysis for the construction methods. The incremental launching was the cheaper solution for slenderness smaller than the intersection point at slenderness between 17 and 18. The MSS was cheaper than the incremental launching for slenderness larger than the intersection point. / Vid dimensionering av tvärsektioner i broar är det av stor vikt att optimera geometrin avseende materialåtgång då mängden material har stor på verkan på ett projekts budget samt miljö. Eftersom konstruktioner ofta består av olika byggnadsmaterial gäller det vid optimering att välja byggnadsmaterialen genom optimerad proportionalitet. Förbifart Stockholm, beställt av Trafikverket, är ett av Sveriges största infrastrukturprojekt och värderas till 27,6 miljarder kronor enligt 2009 års prisnivå. Infrastrukturprojektet är uppdelat i flera mindre entreprenader eller så kallade etapper. Den entreprenad som omfattar trafikplats Hjulsta Södra har blivit tilldelat till Implenia och Veidekke genom ett konsortium (Jointventure Hjulsta, JVH) och värderas till cirka 800 miljoner kronor. Den förspända betongbro som byggs i trafikplats Hjulsta ligger till grund för analysen i detta examensarbete och har använts som referens under vår studie. Syftet med examensarbete var att analysera och jämföra två de två olika produktionsmetoderna, Movable scaffolding system (MSS) och etappvis lansering med hänsyn till erforderlig mängd förspänningskablar och slankhet. Vidare, baserat på erhållna resultat, utfördes en ekonomisk analys och jämförelse mellan produktionsmetoderna. Analysen av MSS utfördes genom att modellera brokonstruktionen i mjukvaruprogrammet SOFiSTiK AG som bygger på finita elementmetoder. Konstruktionen modellerades för olika slankheter, där slankheten definieras som kvoten mellan maximala spannlängden och brons tvärsnittshöjd. Spannlängden hölls konstant medan tvärsnittshöjden varierade för att erhålla olika slankheter. Den optimala slankheten bestämdes genom iterering av mängd förspänningskablar tills spänningsvillkoren var uppfyllda enligt Eurocode. För analysen av etappvis lansering utfördes en numerisk analys vars den optimala mängden förspänningskablar utvärderades i byggskedet (construction stages) samt i slutskedet (final stage). Analysen utfördes på samma sätt för de olika slankheterna. Slutligen genomfördes en konstandsanalys för de olika metoderna. Syftet var att jämföra hur den totala kostnaden för uppförandet av brokonstruktionen skiljde sig för de olika slankheterna. Jämförelsen genomfördes genom att dela upp de olika kostnaderna i fasta kostnader samt rörliga kostnader. Resultaten från analysen visade att den erforderliga mängd förspänningskablar som behövs i en förspänd betongbro är beroende av den strukturella styvheten i tvärsektionen. En högre slankhet, alltså lägre tvärsnittshöjd, ger lägre styvhet och därav mer erforderlig förspänningskablar. Etappvis lansering visade sig vara den metod som krävde mer mängd förspänningskablar. I resultaten för kostnadsanalysen uppmättes en skärningspunkt, för en slankhet mellan 17-18, mellan de två olika metoderna. För förspända betongbroar med slankhet lägre än skärningsupunkten vid 17-18 är etappvis lansering det billigare alternativet. För slankheter högre än 17-18 är MSS det mer ekonomiskt lönsamma alternativet.
17

Florence, Biblioteca del Conservatorio di Musica Luigi Cherubini, Manuscript Basevi 2439: Critical Edition and Commentary

Newton, Paul George, 1930- 06 1900 (has links)
The subject of the present study, Florence, Biblioteca del Conservatorio di Musica Luigi Cherubini, MS Basevi 2439, abbreviated Florence 2439,1 contains secular and sacred vocal music of the late fifteenth and early sixteenth centuries, with texts in French, Dutch, Italian, and Latin.
18

Analyse et Optimisation du Partage de Spectre dans les Systèmes Mobiles Intégrés Satellite et Terrestre / Analysis and Optimization of Spectrum Sharing in Integrated Satellite and Terrestrial Mobile Systems

Deslandes, Vincent 27 June 2012 (has links)
Les technologies mobiles terrestre et satellite sont naturellement complémentaires. Les réseaux cellulaires terrestres sont adaptés aux villes où la densité d'utilisateurs est maximale mais perdent leur rentabilité dans les zones peu peuplées. A l'inverse, les systèmes mobile satellite permettent de couvrir de vastes zones à moindre coût mais n'assurent pas la couverture dans les zones urbaines car le signal est bloqué par les constructions. En les combinant pour assurer la couverture en ville par le réseau terrestre et dans les zones moins denses avec le satellite, on obtient un système à la couverture totale pour un coût optimal. Nous appelons un tel système intégrant une composante satellite et une composante terrestres un "système intégré" satellite/terrestre. Nul doute que d'ici quelques années, le rêve de la communauté satellite de rendre tous les terminaux mobiles capables de se connecter à un satellite sera accessible. Le satellite pourra ainsi être vu par les utilisateurs de terminaux portables comme une énième technologie d'accès à un système "intégré", aux côtés du Bluetooth, du Wifi et des technologies cellulaires (GSM, UMTS, LTE). La réutilisation du spectre satellite par les systèmes terrestres est un facteur déterminant dans le succès de cette intégration car elle permet de justifier les investissements dans le système satellite qui ne peut être rentabilisé par les abonnements seuls. Toutefois sa mise en œuvre pose de nombreux problèmes : règlementaires, commerciaux et bien entendu techniques. Cette thèse apporte des solutions sur ce dernier point et j'espère qu'elle contribuera ainsi à rendre possible ce rêve d'intégration. Nous avons adopté une approche descendante du problème du partage de spectre dans les systèmes mobiles satellite-terrestre. Nous avons tout d'abord établi une synthèse sur les aspects recouverts par l'intégration des systèmes mobiles satellite et terrestre. Nous avons ensuite dressé l'état de l'art sur la problématique de la réutilisation du spectre satellite par les systèmes terrestres, que nous avons complété par nos analyses. Nous avons décidé dans cette thèse de nous focaliser sur un des problèmes majeurs soulevés par cette réutilisation : les interférences co-fréquence du système terrestre sur le lien montant satellite. A partir de l'analyse d'une solution de partage statique de spectre par coordination des plans de fréquence (principe de zone d'exclusion), nous avons élaboré puis analysé les performances de mécanismes innovants d'allocation de ressources dans le système terrestre qui permettent de réduire de façon importante les interférences. De plus, nous proposons une méthode pour garantir au système satellite que les interférences subies sur son lien montant soient inférieures à une valeur limite. Enfin, nous définissons une architecture et les mécanismes associés qui permettent l'implantation des solutions proposées dans un système satellite-terrestre fondé sur la technologie LTE. L'étude du sujet de partage de spectre dans les systèmes mobiles satellite-terrestre est relativement nouvelle et cette thèse constitue donc un travail novateur important qui pourra être utilisé comme base à de futurs travaux. / Terrestrial and satellite mobile technologies are naturally complementary. Terrestrial cellular systems are adapted to urban areas where the user density is maximal but their cost-effectiveness is much lower in sparsely populated areas. On the contrary, mobile satellite systems cover large zones at a relatively low cost but they cannot ensure coverage in urban areas because of signal blockage due to buildings. By combining both systems for ensuring coverage in cities with terrestrial networks and in less dense areas with the satellite, we obtain a system with complete coverage for an optimal cost. Such a system is called mobile terrestrial and satellite "integrated system". It is likely that in a few years, the dream of enabling satellite connectivity on all mobile terminals will be within reach. The satellite will then be perceived for mobile terminal users as an additional access technology to an "integrated network" comparable to Wifi, Bluetooth or cellular technologies (GSM, UMTS, LTE). The spectrum reuse by terrestrial systems is a key for the success of this integration because it justifies part of the investments in the satellite systems that cannot be supported by user subscriptions only. However, implementation of spectrum sharing generates many issues: regulatory, commercial and obviously technical. This thesis brings answers on the latter and I hope it will contribute to make this dream of integration become reality. We used a descending approach of the issue of spectrum sharing in terrestrial and satellite mobile systems. First, we establish a synthesis of all the aspects covered by the integration of mobile satellite and terrestrial systems. Then, we made the state of the art on the issue of satellite spectrum reuse by terrestrial systems and we completed it with our analysis. We decided to focus our work on one of the major issues raised by this reuse: co-frequency interference generated by the terrestrial system on the satellite uplink. From the analysis of a solution proposing a static spectrum sharing by coordination of frequency plans (the exclusion zone principle), we elaborated and analyzed performances of innovative mechanisms of resources allocation in the terrestrial system that allows to reduce significantly the interferences. Moreover, we proposed a method for guaranteeing to the satellite system that interferences from the terrestrial system will not exceed a given threshold. At last, we define an architecture and the associated mechanism that allow the implementation of our solution in an integrated terrestrial-satellite systems based on LTE technology. The study of spectrum sharing in terrestrial-satellite mobile systems is rather new and this thesis represents an innovative work that may serve as a basis for future studies on this issue.
19

Identifying Land Use Changes and It's Socio-Economic Impacts : A Case Study of Chacoria Sundarban in Bangladesh

Musa, Khalid Bin January 2008 (has links)
Human intervention and natural phenomenon cause change in land use day by day. Availability of accurate land use information is essential for many applications like natural resource management, planning and monitoring programs. Landuse Change has become a central component in current strategies for managing natural resources and monitoring environmental change. Because of the rapid development in the field of land use mapping, there is an increase in studies of land use change worldwide. Providing an accurate assessment of the extent and health of the world’s forest, grassland and agricultural resources has become an important priority. By printed maps without any statistics or only statistics without any map can not solve this visualization problem. Because printed maps have not attracted as much attention as statistics among the people because of it is limited applications (Himiyama, 2002). Remotely sensed data like aerial photographs and satellite imageries are undoubtedly the most ideal data for extracting land use change information. Satellite images are the most economical way of getting data for different times. The multitude of existing software helps getting information from satellite image also in manipulating the information. The approach used in this study to classify satellite images and change detection based on Satellite images Landsat MSS (1972), Landsat TM (1989) and Landsat ETM (1999) for using supervised classification methods like maximum likelihood (MAXLIKE), MAHALCLASS and time series analysis of CROSSTAB. After performed these hard and soft classifiers the research showed the significant Landuse change in the study area of Chakoria Sundarban mangrove forest. Remote sensing is the modern tools for detecting change pattern and behaviours of coastal environment (Saifuzzaman, 2000). So, those tools are used in the research work for better change analysis of the study area. For analyzing, evaluation and mapping environmental change detection of different years remotely sensed data have been undertaken. The present research provides some suggestions and recommendations as per research findings in order to optimize the utility of coastal resources and to maintain the sustainability of the resources, coastal land use control and there by stabilizing the coastal vulnerable area of chakoria Sundarban.
20

Processing And Characterization Of Textured Barium Ferrite Ceramics

Aydogan, Eda 01 July 2012 (has links) (PDF)
Technological advances results in the fact that quite a large number of electronic equipment interacts with its environment leading to the malfunction of the devices. This brings about the necessity of using proper electromagnetic (EM) wave absorbers/shields to avoid such interactions. In order to absorb EM waves in a large frequency band from several MHz to GHz, barium hexaferrite (BaHF) ceramics which are produced as textured ceramics as well as in multilayered form can be used. Textured ceramics are processed by tape casting using templated grain growth (TGG) phenomenon. In order to obtain textured ceramics, BaHF powders and platelets are required as raw materials in such a way that during sintering small size powders are directioned by large platelet surfaces. In this study, ferrite powders were synthesized by mixed oxide technique while the platelets were produced by both molten salt synthesis (MSS) and reactive templated grain growth (RTGG) methods. In the case of platelet synthesis by MSS, effects of calcination temperature and time as well as type and composition of the flux on the formation and morphology of platelets were investigated based on the XRD and SEM results. Studies have shown that KCl flux led to the formation of sharper platelet morphology, while NaCl resulted in more round shapes. However, extent of BaHF formation in the case of NaCl was higher when compared to KCl flux due to its higher wettability characteristic, and hence faster interaction with the raw materials. Since the aspect ratio of the synthesized platelets was only ca. 2-4, these platelets were not efficient for further TGG studies. Alternatively, BiFeO3 (BiF) particles having ~30-40 &mu / m average size were synthesized as seed crystals for the synthesis of BaHF platelets by RTGG method. After the washing of these platelets with dilute HNO3, pure BaHF powders and platelets were directed by tape casting which was followed by sintering using TGG phenomenon. Degree of achieved texturing in the processed ceramics was studied using Rietveld analysis, pole figure measurement and electron backscattered diffraction (EBSD).

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