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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.
41

Integration of Micropore and Nanopore Features with Optofluidic Waveguides for Single Particle Sensing

Holmes, Matthew R. 28 June 2011 (has links) (PDF)
This dissertation outlines the research and development of ground-breaking nanometer sized openings (nanopores) integrated with an on-chip optofluidic platform. This platform represents a significant advancement for single nanoparticle sensing. In this work specifically, the integrated optofluidic platform has been used to electrically and optically filter and detect single nanoparticles using ionic current blockade and fluorescence experiments. The correlation of electrical and optical signal has provided the highest sensitivity single nanoparticle measurements ever taken with integrated optofluidic platforms. The particular optofluidic platform used for this work is an antiresonant reflecting optical waveguide (ARROW). ARROW hollow and solid core waveguides are interference based waveguides that are designed to guide light in low index media such as liquids and gases. Because of this unique guiding property, ARROW hollow cores can be used to sense and analyze low concentrations of single particles. Additionally, because ARROW platforms are based upon standard silicon processing techniques and materials, they are miniature sized (~1 cm2), inexpensive, highly parallelizable, provide a high degree of design flexibility, and can be integrated with many different optical and electrical components and sources. Finally, because of the miniature, integrated nature of the ARROW platform, it has the potential to be incorporated into hand held devices that could provide quick, inexpensive, user-friendly diagnostics. The ARROW platform has been through many revisions in the past several years in an attempt to improve performance and functionality. Specifically, advanced fabrication techniques that have been used to decrease the production time, increase the yield, and improve the optical quality of ARROW platforms are discussed in the first part of this work. These advancements were all developed in order to facilitate the production of high quality integrated nanopores and ARROW platforms. The second part of this work then focuses on the actual integration of micrometer sized openings (micropores) and nanopores in the hollow waveguide section of ARROW platforms for filtering, detecting, and analyzing single nanoparticles. The successes and attempts at achieving these results are the basis of this dissertation of work.
42

Développement d’antennes à base de structures métamatériaux pour les applications aéronautiques (GPS/DME, bande L) et de communications haut débit (en bade E – 80 GHz) / Development of antennas based on metamaterial structures for aeronautical applications (DME/GPS, L band) and for high bit rate communications in the E-band (at 80GHz)

Meng, Fanhong 21 December 2015 (has links)
Les travaux présentés dans ce manuscrit sont relatifs à la conception et au développement d’antennes basées sur les structures artificielles – métamatériaux. La première antenne conçue et réalisée est une antenne bi-fonction en bande L (~1GHz) (GPS et DME) à diversité de bande/de polarisation, destinée aux applications aéronautiques. Ces travaux rentrent dans le cadre du projet MSIE (pôle de compétitivité ASTHEC) pour lequel notre LEME a été très actif. Les partenaires industriels de ce projet sont EADS/IW, Dassault aviation, INEO-Défense, SATIMO. Les résultats montrent la faisabilité d’une antenne unique pouvant avoir simultanément deux fonctions avec une diversité de polarisation et de bande spectrale. L’utilisation des métamatériaux a permis en particulier le maintien de la polarisation circulaire de l’antenne GPS -L1 à L5. La fonction DME a été consolidée avec le maintien de son gain. La seconde antenne est une antenne cavité Fabry-Pérot mettant en œuvre une structure partiellement réfléchissante double couche. Nous avons démontré le phénomène physique d’inversion de la phase du coefficient de réflexion de la PRS. Nous avons obtenu un gradient positif de phase sur une bande de 5 GHz autour de 80GHz. Grace à ce profil nouveau de la phase obtenu par la structure métamatériau PRS, on dispose d’une avance linéaire de la phase qui compense le retard du à la cavité Fabry-Pérot. Ainsi on maintient les conditions de résonance de la cavité sur une large bande, 5GHz. Nous démontrons, que la mise en œuvre de cette structure aux caractéristiques inédites permet de réaliser une antenne cavité ultra-directive sur une très large bande spectrale de 5GHz. Les performances atteintes sont une directivité de 35 à 40dBi sur 5 GHz, une adaptation parfaite (gain ~ directivité) avec très peu de sources primaires. L’antenne est compacte avec une hauteur totale inférieure au 10mm (connecteur compris) et une surface de 100mmx100mm. / The work presented in this manuscript is related to the design and development of antennas based on artificial structures - metamaterials. The first designed and built antenna is a GPS and DME dual-function in the L (~ 1GHz). It is an antenna designed with polarization and spectral diversities for aeronautical applications. The work is within the MSIE project of ASTHEC cluster for which our laboratory (LEME) was very active. The industrial partners of the project are EADS/IW, Dassault Aviation, INEO-Defense SATIMO. The results show the feasibility of a single antenna having simultaneously two functions with a diversity of polarization and spectral band. The use of metamaterials enabled in particular the preservation of circular polarization of the GPS antenna on the bands ranging from L1 to L2. The DME function was consolidated with the same gain.The second antenna is an antenna Fabry-Perot cavity employing a partially reflective structure (PRS) Double-layer. We have demonstrated by numerical simulation and experimental characterization, the physical phenomenon of inversion phase of the reflection coefficient PRS. We obtain a positive gradient of the phase over a broad band of 5 GHz around 80GHz. Thanks to this new profile obtained by the PRS metamaterial structure, it has a linear advance of the phase which compensates for the delay of the Fabry-Perot cavity. Thus the cavity resonance conditions are maintained over a wide band, 5GHz. We demonstrate that the implementation of this structure with unique features allows a highly directive antenna cavity over a very wide spectral band 5GHz. The performance are a directivity of 35-40 dBi over 5 GHz, a perfect adaptation (gain ~ directivity) with very few primary sources.
43

On an epidemic model given by a stochastic differential equation

Zararsiz, Zarife January 2009 (has links)
We investigate a certain epidemics model, with and without noise. Some parameter analysis is performed together with computer simulations. The model was presented in Iacus (2008).
44

On an epidemic model given by a stochastic differential equation

Zararsiz, Zarife January 2009 (has links)
<p>We investigate a certain epidemics model, with and without noise. Some parameter analysis is performed together with computer simulations. The model was presented in Iacus (2008).</p>
45

Weak Boundary and Interface Procedures for Wave and Flow Problems

Abbas, Qaisar January 2011 (has links)
In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems. The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case. The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach. Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks. Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability. Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.
46

Absolute continuity of the laws, existence and uniqueness of solutions of some SDEs and SPDEs

Yue, Wen January 2014 (has links)
This thesis consists of four parts. In the first part we recall some background theory that will be used throughout the thesis. In the second part, we studied the absolute continuity of the laws of the solutions of some perturbed stochastic differential equaitons(SDEs) and perturbed reflected SDEs using Malliavin calculus. Because the extra terms in the perturbed SDEs involve the maximum of the solution itself, the Malliavin differentiability of the solutions becomes very delicate. In the third part, we studied the absolute continuity of the laws of the solutions of the parabolic stochastic partial differential equations(SPDEs) with two reflecting walls using Malliavin calculus. Our study is based on Yang and Zhang \cite{YZ1}, in which the existence and uniqueness of the solutions of such SPDEs was established. In the fourth part, we gave the existence and uniqueness of the solutions of the elliptic SPDEs with two reflecting walls and general diffusion coefficients.
47

A Grounded Theory Study of Working Adults Navigating Advanced Degrees

Slider, Charles Valent 01 January 2015 (has links)
There is considerable body of research about adults navigating advanced degrees, but little regarding adults in graduate degree programs while in full-time educational careers. Guided by Mezirow's transformative learning theory, the purpose of this study was to develop a grounded theory (GT) that reflected the lived experiences of fulltime teachers within a school district as they progressed through advanced degrees. Fourteen adult learner participants were asked to talk about their experiences as both fulltime educators and graduate students. The constant comparative analysis method was employed to analyze the data to develop a theory entitled enduring driven succeeding. The theory explained stages that the participants underwent as they pursued an advanced degree. Four stages emerged from this GT study. Each stage represented behaviors one can expect in similar contexts: (a) visioning experiences in which the learner arrives at a clear mental picture the desired outcome; (b) investing experiences which occur when a learner decides on following a course of action towards the accomplishment of a goal; (c) clicking experiences in which learners begin to understand and apply their learning in meaningful ways; and (d) reflecting experiences which occur as adult learners reflect and rethink their successes and failures in order to move forward to pursue their goals. This theory can be useful in preparing university administrators, recruiters, or trainers to understand the challenges faced by fulltime working adult students as they navigate advanced degree programs. Extending this theory through the method of grounded action (GA) may also assist in providing good action plans for resolving the issues faced by adult learners as they pursue advanced degree programs.
48

»chugga chug, rrrrrrsplat« (Tom Johnson): Kommunizieren über Klänge und Geräusche

Klassen, Janina 24 October 2023 (has links)
Ausgehend von Tom Johnsons Rezension über David Tudors Aufführung von Pulsers werden unterschiedliche Reflexionen und Strategien verfolgt, wie über Klang und Geräusch kommuniziert werden kann. / Starting from Tom Johnson’s article on David Tudor’s performance Pulsers, this essay discusses different reflections on and ways to talk about sound.
49

Relational Learning: A Study of Peer Mentoring Experiences among Undergraduate Teacher Education Majors

Chorba, Kristen 16 December 2013 (has links)
No description available.
50

The role and position of Jewish women between 200 BCE - 200 CE

Lief, Hélène Rhona 11 1900 (has links)
This dissertation examines the role and position of Jewish women in the Near East between 200 BCE - 200 CE. This was a very important period in Jewish legal and cultural history. The redaction of the Mishnah, the oldest extant body of Jewish law, was completed at approximately the end of the time under review, and was to have a lasting influence on the Jewish people. No society exists in a vacuum. During these years the Jews lived within the GraecoRoman Empire and this reflected on their attitudes towards women. To appreciate this it has been necessary to go back in time to the Hebrew Bible and to trace any attitudinal changes which occurred over the centuries. Although the Mishnah has been regarded as the terminus ad quem of this investigation, brief mention is also made of prevailing attitudes affecting women in present day Jewish society. / Biblical and Ancient Studies / M.A. (Judaica)

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