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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.
51

Compact and Integrated Broadband Antennas : for wireless applications

Sadiq, Muhammad Afzal January 2012 (has links)
As the wireless technology maturing, the wireless systems are evolving towards the development of new applications with broad band access and also the higher data rate. This necessity will give rise to the new WLAN standards as well as minimizing the cost, high QoS and security features of the wireless setup. It will also lift the trends towards the miniaturizination of hand-held devices, high data rates, higher bandwidth and robust performance on present and future WLAN standards, IEEE 802.11a/ 802.11b and 802.11g. A Coplanar waveguide (CPW) fed compact and optimized monopole antenna printed on a substrate of Rogers TMM 4 is studied in this paper. The proposed antenna is fabricated and measured to verify the response for Wireless applications. It is broadband antenna which has dual band characristics and can operate simultaneously both at 2.4 GHz and 5.2 GHz frequency bands for Wireless Local Area Network (WLAN) application. Furthermore it is studied in detail that how the antenna performance and operation is affected by changing the parameters of antenna. The antenna has satisfactory return loss characteristics in desired range of frequency. The antenna has acceptable gain and directivity. The proposed antenna has a return loss value S11 < -10 dB. The impedance bandwidth of antenna is high and the radiation pattern of antenna is omnidirectinal which fulfill the WLAN requirements.
52

Repetitive Operation of the University of Saskatchewan Compact Torus Injector

Pant, Andre 06 August 2009 (has links)
Development of fueling technologies for modern and future tokamak reactors is essential for their implementation in a commercial energy production setting. Compared to the presently available fueling technologies, gas or cryogenic pellet injection, compact torus injection presents an effective and efficient method for directly fueling the central core of tokamak plasmas. Fueling of the central core of a tokamak plasma is pivotal for providing efficient energy production. The central core plasma of a reactor contains the greatest density of fusion processes. For consistent and continuous fueling of tokamak fusion reactors, compact torus injectors must be operated in a repetitive mode.<p> The goal of this thesis was to study the feasibility of firing the University of Saskatchewan Compact Torus Injector (USCTI) in a repetitive mode. In order to enable USCTI to fire repetitively, modifications were made to its electrical system, control system and data acquisition system. These consisted primarily of the addition of new power supplies, to enable fast charging of the many capacitor banks used to form and accelerate the plasma. The maximum firing rate achieved on USCTI was 0.33 Hz, an increase from the previous maximum firing rate of 0.2 Hz achieved at UC Davis.<p> Firing USCTI in repetitive modes has been successful. It has been shown that the CTs produced in any given repetitive series are properly formed and repeatable. This is made evident through analysis of data collected from the CTs' magnetic fields and densities as they traveled along the injector barrel. The shots from each experiment were compared to the series' mean data and were shown to be consistent over time. Calculations of their correlations show that there are only minimal deviations from shot to shot in any given series.
53

Design of Compact Antennas in Multilayer Technology for Wireless Communications / WLAN Applications

DeJean, Gerald Reuben 04 February 2005 (has links)
Various compact and packaging-adaptive antennas have been designed for practical wireless communications systems such as global system of mobile communications (GSM), Bluetooth Industrial-Scientific-Medical (ISM) devices, IEEE802.11a WLAN, and Local Multipoint Distribution Systems (LMDS) applications. First, compact stacked patch antennas using LTCC multilayer technology have been presented. A set of design rules is established for the purpose of designing optimized bandwidth compact antennas on LTCC multilayer substrates. To verify its effectiveness, the proposed design rules are applied to three emerging wireless bands. The return loss and the impedance bandwidth are optimized for all three bands. A maximum bandwidth of 7% can be achieved for an antenna operating in the LMDS band. Furthermore, folded shorted patch antennas (SPAs) are designed to significantly reduce the resonant frequency of a standard patch antenna. The design methodology of this structure starts with a conventional half-wave and through a series of procedures, evolves into a smaller, lambda/8 wavelength resonant length structure. Upon varying the height of the lower patch, the resonant length can be reduced to lambda/16. A comparison between a folded SPA and a standard SPA validates the folding technique proposed in this document. The folded SPA is applied to the 2.4 GHz ISM band. The measured results are in good agreement with simulated results. This antenna can be implemented into 3D packages using multilayer laminates such as LTCC or LCP.
54

Datainsamlingskort med Compact PCI Express

Persson, Lotta January 2008 (has links)
<p>In this thesis a prototype board for data aqcusition is designed and manufactured. The board is compliant with Compact PCI Express and it can sample an analog signal with two time interleaved ADC:s. Furthermore, the board is also equiped with one FPGA for the possibility of signal processing. The thesis also include a study for investigation what is needed for a total solution for data aqcusition, represention and managing the sampled data with LabView.</p>
55

Aspects of constructive dynamical systems : a thesis submitted in partial fulfilment of the requirements of the degree for Master of Science in Mathematics at the University of Canterbury /

Hendtlass, Matthew. January 2009 (has links)
Thesis (M. Sc.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 47-48). Also available via the World Wide Web.
56

Applications of elementary submodels in topology /

Dolph Bosely, Laura. January 2009 (has links)
Thesis (Ph.D.)--Ohio University, August, 2009. / Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 110-113)
57

Applications of elementary submodels in topology

Dolph Bosely, Laura. January 2009 (has links)
Thesis (Ph.D.)--Ohio University, August, 2009. / Title from PDF t.p. Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 110-113)
58

Source modelling of extreme and intermediate mass ratio inspirals

Huerta Escudero, Eliu Antonio January 2011 (has links)
No description available.
59

Datainsamlingskort med Compact PCI Express

Persson, Lotta January 2008 (has links)
In this thesis a prototype board for data aqcusition is designed and manufactured. The board is compliant with Compact PCI Express and it can sample an analog signal with two time interleaved ADC:s. Furthermore, the board is also equiped with one FPGA for the possibility of signal processing. The thesis also include a study for investigation what is needed for a total solution for data aqcusition, represention and managing the sampled data with LabView.
60

Compact Dynamical Foliations

Carrasco Correa, Pablo Daniel 09 June 2011 (has links)
According to the work of Dennis Sullivan, there exists a smooth flow on the 5-sphere all of whose orbits are periodic although there is no uniform bound on their periods. The question addressed in this thesis is whether such an example can occur in the partially hyperbolic context. That is, does there exist a partially hyperbolic diffeomorphism of a compact manifold such that all the leaves of its center foliation are compact although there is no uniform bound for their volumes. We will show that the answer to the previous question under the very mild hypothesis of dynamical coherence is no. The thesis is organized as follows. In the first chapter we give the necessary background and results in partially hyperbolic dynamics needed for the rest of the work, studying in particular the geometry of the center foliation. Chapter two is devoted to a general discussion of compact foliations. We give proof or sketches of all the relevant results used. Chapter three is the core of the thesis, where we establish the non existence of Sullivan's type of examples in the partially hyperbolic domain, and generalize to diffeomorphisms whose center foliation has arbitrary dimension. The last chapter is devoted to applications of the results of chapter three, where in particular it is proved that if the center foliation of a dynamically coherent partially hyperbolic diffeomorphism is compact and without holonomy, then it is plaque expansive.

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