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1
Siepman, Halle Diane. « Tilted ». Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1755.
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2
Meng, J., Stefan Frauendorf et Jens Reif. « Tilted Cranking ». Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-32231.
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Meng, J., Stefan Frauendorf et Jens Reif. « Tilted Cranking ». Forschungszentrum Rossendorf, 1994. https://hzdr.qucosa.de/id/qucosa%3A22050.
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Frauendorf, Stefan, et J. Meng. « Tilted Rotation of Triaxial Nuclei ». Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31369.
Texte intégralRésumé :
The Tilted Axis Crankiug theory is applied to the model of two particles coupled to a triaxial rotor. Cornparirig with the exact quantal solutions, the interpretation and quality of the mean field approximations studied. Conditions are discussed when the axis of rotation lies inside or outside of the principal planes of the triaxial density distribution. The planar solutions represent ∆ I = 1 bands, whereas the aplanar solutions represent pairs of identical ∆ I = 1 bands with the same parity. The two bands differ by the chirality of the principal axes with respect to the angular momentum vector. The transition from planar to chiral solutions is evident in both the quantal and the mean field calculations. Its physical origin is discussed.
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Trescher, Maximilian [Verfasser]. « Tilted Weyl Semimetals / Maximilian Trescher ». Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1176708244/34.
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Frauendorf, Stefan, et J. Meng. « Tilted Rotation of Triaxial Nuclei ». Forschungszentrum Rossendorf, 1996. https://hzdr.qucosa.de/id/qucosa%3A21963.
Texte intégralRésumé :
The Tilted Axis Crankiug theory is applied to the model of two particles coupled to a triaxial rotor. Cornparirig with the exact quantal solutions, the interpretation and quality of the mean field approximations studied. Conditions are discussed when the axis of rotation lies inside or outside of the principal planes of the triaxial density distribution. The planar solutions represent ∆ I = 1 bands, whereas the aplanar solutions represent pairs of identical ∆ I = 1 bands with the same parity. The two bands differ by the chirality of the principal axes with respect to the angular momentum vector. The transition from planar to chiral solutions is evident in both the quantal and the mean field calculations. Its physical origin is discussed.
7
Yan, Zhijun. « Advanced tilted fiber gratings and their applications ». Thesis, Aston University, 2013. http://publications.aston.ac.uk/25297/.
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This thesis presents a detailed numerical analysis, fabrication method and experimental investigation on 45º tilted fiber gratings (45º-TFGs) and excessively tilted fiber gratings (Ex-TFGs), and their applications in fiber laser and sensing systems. The one of the most significant contributions of the work reported in this thesis is that the 45º-TFGs with high polarization extinction ratio (PER) have been fabricated in single mode telecom and polarization maintaining (PM) fibers with spectral response covering three prominent optic communication and central wavelength ranges at 1060nm, 1310nm and 1550nm. The most achieved PERs for the 45º-TFGs are up to and greater than 35-50dB, which have reached and even exceeded many commercial in-fiber polarizers. It has been proposed that the 45º-TFGs of high PER can be used as ideal in-fiber polarizers for a wide range of fiber systems and applications. In addition, in-depth detailed theoretical models and analysis have been developed and systematic experimental evaluation has been conducted producing results in excellent agreement with theoretical modeling. Another important outcome of the research work is the proposal and demonstration of all fiber Lyot filters (AFLFs) implemented by utilizing two (for a single stage type) and more (for multi-stage) 45º-TFGs in PM fiber cavity structure. The detailed theoretical analysis and modelling of such AFLFs have also been carried out giving design guidance for the practical implementation. The unique function advantages of 45º-TFG based AFLFs have been revealed, showing high finesse multi-wavelength transmission of single polarization and wide range of tuneability. The temperature tuning results of AFLFs have shown that the AFLFs have 60 times higher thermal sensitivity than the normal FBGs, thus permitting thermal tuning rate of ~8nm/10ºC. By using an intra-cavity AFLF, an all fiber soliton mode locking laser with almost total suppression of siliton sidebands, single polarization output and single/multi-wavelength switchable operation has been demonstrated. The final significant contribution is the theoretical analysis and experimental verification on the design, fabrication and sensing application of Ex-TFGs. The Ex-TFG sensitivity model to the surrounding medium refractive index (SRI) has been developed for the first time, and the factors that affect the thermal and SRI sensitivity in relation to the wavelength range, tilt angle, and the size of cladding have been investigated. As a practical SRI sensor, an 81º-TFG UV-inscribed in the fiber with small (40μm) cladding radius has shown an SRI sensitivity up to 1180nm/RIU in the index of 1.345 range. Finally, to ensure single polarization detection in such an SRI sensor, a hybrid configuration by UV-inscribing a 45º-TFG and an 81º-TFG closely on the same piece of fiber has been demonstrated as a more advanced SRI sensing system.
8
Withers, Ian Michael. « A computer simulation study of tilted smectic mesophases ». Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/20557/.
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Results are presented from a series of simulations undertaken to determine the effect of a novel form of molecular biaxiality upon the phase behaviour of the well established Gay-Berne (GB) liquid crystal model. Firstly, the simulation of a bulk system interacting via the Internally-Rotated Gay-Berne (IRGB) potential, which offers a single-site representation of a molecule rigidly constrained into a zig-zag conformation, is presented. The results of simulations performed for systems of IRGB particles with an aspect ratio of 3:1 confirm that the introduction of biaxiality into the model results in the destabilisation of the orientationally ordered phases. For particles with a sufficiently pronounced zig-zag conformation, this results in the complete destabilisation of the smectic A phase and the smectic B phase being replaced by the tilted smectic J phase. Following these observations, the effect upon the phase behaviour of increasing molecular elongation is also considered, with an increase in the aspect ratio from 3:1 to 4:1 resulting in the nematic and smectic J phases being replaced by smectic A and smectic G phases respectively. Secondly, a version of the IRGB potential modified to include a degree of molecular flexibility is considered. Results obtained from bulk systems interacting via the flexible IRGB for 3:1 and 4:1 molecules show that the introduction of flexibility results in the destabilisation of the smectic A phase and the stabilisation of the nematic and tilted hexatic phases. Finally, the effect upon the phase behaviour of the rigid IRGB model of the inclusion of a longitudinal linear quadrupole is examined. These results show that increasing quadrupole moment results in the destabilisation of the tilted hexatic phase, although the biaxial order parameter is increased with increasing quadrupole moment. There is no clear correlation between quadrupole magnitude and the other observed phase transitions, with the nematic and smectic A phases being variously stabilised and destabilised with increasing quadrupole magnitude. For the 4:1 molecules with large quadrupole moments, buckled smectic layers are observed where some molecules are tilted with respect to a local layer normal. Of all the systems considered here, this buckled structure is the one which most closely resembles the elusive smectic C phase.
9
Meng, J., et Stefan Frauendorf. « Interpretation and Quality of the Tilted Axis Cranking Approximation ». Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31485.
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Comparing with the exact solutions of the model system of one and two particles coupled to an axial rotor, the quality of the semi classical tilted axis cranking approximation is investigated. Extensive comparisons of the energies and M1 and E2 transition probabilities are carried out for the lowest bands. Very good agreement is found, except near band crossings. Various recipes to take into account finite K within the frame of the usual principal axis cranking are included into the comparison. A set of rules is suggested that permits to construct the excited bands from the cranking configurations, avoiding spurious states.
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Nelson, Erica. « H I line profiles of galaxies : tilted ring models ». Pomona College, 2008. http://ccdl.libraries.claremont.edu/u?/stc,46.
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Two-dimensional information on the kinematics and spatial distribution of gas in spiral galaxies is encoded in radio observations of their one-dimensional 21-cm neutral hydrogen (HI) line profiles. More than ten thousand HI profiles have been published and are publicly available. In order to explore the parameter space mapped out by the 21-cm neutral hydrogen line pro file, we have modified and run a FORTRAN-based computer simulation code. We have identified 7 control parameters that define the morphology of the modelled galaxy: they describe the neutral hydrogen gas distribution (density and spatial location of the gas), characteristics of its rotation curve, warps, asymmetries, and finally, the viewing angle. All except the last of these parameters tell us significant physical information about the galaxy but a determination of them is not immediately apparent from the two-dimensional 21-cm line profile. Hence, the goal of this exploration is to find meaningful correlations between the observed 21-cm line profile features and the underlying physical parameters.
11
Meng, J., et Stefan Frauendorf. « Interpretation and Quality of the Tilted Axis Cranking Approximation ». Forschungszentrum Rossendorf, 1996. https://hzdr.qucosa.de/id/qucosa%3A21976.
Texte intégralRésumé :
Comparing with the exact solutions of the model system of one and two particles coupled to an axial rotor, the quality of the semi classical tilted axis cranking approximation is investigated. Extensive comparisons of the energies and M1 and E2 transition probabilities are carried out for the lowest bands. Very good agreement is found, except near band crossings. Various recipes to take into account finite K within the frame of the usual principal axis cranking are included into the comparison. A set of rules is suggested that permits to construct the excited bands from the cranking configurations, avoiding spurious states.
12
Duclut, Charlie. « Nonequilibrium critical phenomena : exact Langevin equations, erosion of tilted landscapes ». Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066241/document.
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L'objet de cette thèse est l'étude de phénomènes critiques hors-équilibre. Pour décrire ces systèmes, l'utilisation d'équations de Langevin est souvent incontournable car elles permettent une description heuristique relativement simple du phénomène, construite en ajoutant un terme de bruit à la dynamique macroscopique. J'ai montré qu'il est toutefois possible, dans le cas des processus de réaction-diffusion, d'aller au delà de cette approche et de dériver une équation de Langevin exacte qui décrit la dynamique au niveau microscopique. Une seconde partie de ma thèse est consacrée à l'étude de modèles spécifiques de phénomènes critiques hors-équilibre à l'aide du groupe de renormalisation non-perturbatif (NPRG), une version moderne des blocs de spins de Wilson et Kadanoff. À l'équilibre, cet outil tire son succès de sa capacité à contrôler les fluctuations au voisinage de la transition grâce à un régulateur. Hors équilibre, les fluctuations temporelles doivent être traitées de la même façon, et j'ai donc conçu un régulateur qui contrôle à la fois les fluctuations spatiales et temporelles. Enfin, j'ai appliqué le NPRG à un modèle d'érosion. En effet, l'apparition générique de lois d'échelles dans les paysages suggère l'existence d'un mécanisme sous-jacent qui conduit ces systèmes à leur point critique. L'équation de Kardar-Parisi-Zhang modélise l'érosion à grande échelle (>2 km), mais ne s'accorde pas aux observations à plus petite échelle. Un modèle différent, tenant compte de l'anisotropie (la pente d'une montagne), fut donc suggéré. À l'aide du NPRG, je montre que ce modèle possède une ligne de points fixes qui correspond à un domaine continu d'exposants d'échelleThis manuscript is focused on the study of critical phenomena taking place out-of-equilibrium. In the description of such phenomena, Langevin equations are ubiquitous and are usually derived in a phenomenological way by adding a noise term to a deterministic mean-field equation. However, I show that for reaction-diffusion processes it is in fact possible to derive an exact Langevin equation from the microscopic process. A second part of my thesis work has been devoted to the study of specific nonequilibrium critical phenomena using the nonperturbative renormalization group (NPRG), which is a modern implementation of Wilson and Kadanoff's block-spin idea. This tool, very powerful in an equilibrium context, takes care of the growing spatial fluctuations that arise near criticality through the use of a regulator. In a nonequilibrium context, the temporal fluctuations also have to be controlled. I have therefore designed a regulator that tackles both spatial and temporal fluctuations. Finally, I have applied the NPRG techniques to a model of landscape erosion: indeed, the generic scaling behaviour that appear in erosional landscapes suggests the existence of an underlying mechanism naturally fine-tuned to be critical. The Kardar-Parisi-Zhang equation seems to give a correct model for landscape erosion at large length scale (>2 km), but fails to predict the scaling observed at smaller scale. A different model was thus suggested which takes into account the intrinsic anisotropy at smaller length scale (the slope of the mountain). Using NPRG techniques, I show that this model possesses a line of fixed points associated with a continuous range of scaling exponents
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Murphy, Graham James. « Cluster combinatorics and derived equivalences for m-cluster tilted algebras ». Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490965.
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Using the polygonal models for the m-cluster complexes developed in [25] we classify maximal m-orthogonal subsets, defined in [38], of the translation quiver Z~ where t1 is a Dynkin diagram of type Am En/en or Dn by describing explicitly a bijective correspondence between the maximal facets of the m-cluster complexes and the maximal m-orthogonal subsets of Z~. This generalizes results appearing in [38]. We then apply our result to classify the blocks of group algebras whose defect group is not quatemion and for which a maximal m-orthogonal module exists. We also describe the m-cluster tilted algebras of type An using the facets of the m-cluster complex. We introduce tilting complexes which correspond in a natural way to the algebra mutations induced by the exchange relation between facets of the m-cluster complex of type An- We prove that known necessary conditions on the Cartan matrix for the derived equivalence of two m-cluster tilted algebras of type An [17], are in fact sufficient, thereby classifying up to derived equivalence the m-cluster tilted algebras of type An. To achieve this we provide an algorithm which uses the tilting complexes associated with the algebra mutations in type An in order to reduce connected components of m-cluster tilted algebras of type An with the same number of simple modules and cycles in their quivers to a normal form. This generalizes a result of Buan and Vatne [22] which classifies the I-cluster tilted algebras of type An up to derived equivalence.
14
Tanner, Richard Kevin. « From maldistribution to mass transfer in a tilted packed column ». Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/1087.
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Parsons, Mark James. « On indecomposable modules over cluster-tilted algebras of type A ». Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30538.
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Gabriel's Theorem describes the dimension vectors of the finitely generated indecomposable modules over the path algebra of a simply-laced Dynkin quiver. It shows that they can be obtained from the expressions for the positive roots of the corresponding root system in terms of the simple roots. Here, we present a method for finding the dimension vectors of the finitely generated indecomposable modules over a cluster-tilted algebra of Dynkin type A.;It is known that the quiver of a cluster-tilted algebra of Dynkin type A is given by an exchange matrix of the corresponding cluster algebra. We define a companion basis for such a quiver to be a Z -basis of roots of the integral root lattice of the corresponding root system whose associated matrix of inner products is a positive quasi-Cartan companion of the corresponding exchange matrix.;Our main result establishes that the dimension vectors of the finitely generated indecomposable modules over a cluster-tilted algebra of Dynkin type A arise from expressions for the positive roots of the corresponding root system in terms of a companion basis (for the quiver of that algebra). This can be regarded as a generalisation of part of Gabriel's Theorem in the Dynkin type A case. The proof uses the fact that the quivers of the cluster-tilted algebras of Dynkin type A have a particularly nice description in terms of triangulation of regular polygons.
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GUO, YUPING. « A FAST COMPUTATIONAL METHOD IN TILTED PEPTIDE INSERTION ANGLE PREDICTION ». University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1075217984.
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Ugarte-Almeyda, Orlando J. « Thermal analysis of tilted roofs composed of two separated surfaces ». Morgantown, W. Va. : [West Virginia University Libraries], 2008. http://hdl.handle.net/10450/5983.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains xii, 58 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 54-58).
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Monroe, Catherine Sue 1947. « The tilted family : its effects on mothers : an exploratory study ». Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558104.
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Jobe, Oli. « Hyperbolic-umbilic diffraction catastrophe from oblate water drops with tilted illumination ». Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/O_JOBE_073008.pdf.
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Earl, Samantha C. « The tilted trajectory of public art : New York City, 1979 - 2005 ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/69530.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 142-148).
This thesis explores the relationship between urban planning and public art, and questions the efficacy of past and current models, whilst pushing us to develop new ones. It strives to glean the most salient issues universal to all instances of public art, and uses four case studies to illuminate such issues in practice. Tilted Arc by Richard Serra and Metronome by Jones and Ginzel adhere to a conventional model of public art - an object in a public space, commissioned by a small group of "experts," with an essentially passive role accorded to audience. The Gates and the work of artist Mierle Laderman Ukeles emphasize ephemerality, integration and participation. While vastly different from one another, the latter two also strive to engage more directly with urban planning and political processes. Tilted Arc is the watershed public artwork, and sets the stage upon which the other three case studies unfold. Within the context of New York City's neoliberal transformation, this thesis seeks to situate public art's role in the process, capping the story with The Gates in 2005. With modernist notions of public art losing relevance, this thesis argues that unrealistic expectations are still all-too-often placed on public art, using vestigial notions of the relationship between artist and audience. Simultaneously such outdated ideas undermine the potential for us as urban planners and public art producers to find new ways of working together in the service of cities that are "revitalized, cosmopolitan, just and democratic."' Instead this thesis argues that we deconstruct concepts of form, process, and audience/intention, and reconstitute new models for public art in our cities. Optimistically I argue that such thinking is already underway in cities like New York. It is fundamental that we consider how to refine and consolidate what is working for public art, and integrate such aspects into urban planning and policy from the outset. With both public art and urban planning at a crossroads, the potential exists to think and act boldly as we move forward. Professional silos need to be regularly challenged - collaboration will be the most important ingredient needed to redefine and shape the trajectory of public art in the 21st century.
by Samantha C. Earl.
M.C.P.
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Adebayo, Daniel. « Development of high function in-fibre tilted gratings and their applications ». Thesis, Aston University, 2016. http://publications.aston.ac.uk/30068/.
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This thesis presents a detailed description of the fabrication process, spectral characteristics and applications of in-fibre gratings of normal structures, such as fibre Bragg gratings and long period gratings, and tilted structures of small, large and 45 angle tilted fibre gratings. All these in-fibre gratings were fabricated by UV-laser inscription in standard telecom single mode fibres. The key part of this research work is the fabrication and systematic spectral and sensitivity characterisation of the fibre Bragg gratings (FBGs) and long period gratings (LPGs). Their temperature sensitivities were compared for different wavelength ranges from near-IR to mid-IR. The LPGs, which have multiple transmission loss peaks were characterised for temperature and refractive index sensitivities for each transmission loss peak, obtaining the correlation between the cladding mode order and sensitivity. The results of this investigation have enabled to select the best LPGs for two bio sensing applications: (i) investigation of Foetal Bovine Degradation due to change in temperature and (ii) sensing different haemoglobin concentrations. The other major contribution of this Ph.D. research is the systematic approach used in fabricating and characterising tilted fibre gratings (TFGs) with small, large and 45°angle tilted structures. All these types of TFG have been investigated in terms of inscription methods, spectral characteristics, polarisation properties and thermal responses. The three fabrication techniques used to inscribe TFG structures, two-beam holographic, phase-mask and amplitude-mask, have been fully discussed. The TFGs were subjected to various temperature sensing experiments to evaluate their responses and how the temperature change could affect their performance in real environment. In addition, for the small and large angle TFGs, their refractive index (RI) sensing characteristics have been investigated to show their unique RI sensing capability to the surrounding medium. And due to the unique polarisation property of large angle TFG, it was employed in an all fibre twist sensor. Finally, a chemical sensing application was evaluated using a pair of large angle TFGs forming a high sensitivity interferometer. Based on their unique optical properties, a power tapper working at 800nm wavelength region has been demonstrated using 45°-TFGs. The in-fibre tapper system was characterised for its dispersion, side-tapped beam width and side-tapped power variation along the grating length. This system was then used as a temperature sensor, showing side-tapping functionality. Finally, as another major contribution, the 800nm 45°-TFG combined with CCD array were developed into an optical fibre signal interrogation system and evaluated for FBG temperature sensing, which clearly demonstrated the design concept of an in-fibre spectrometer of low cost, compact structure and high function. In collaboration with Bern University of Applied Sciences, Bangor University and Jiangnan University, the 800nm 45°-TFG was first used to develop an OCT system for bio sensing applications.
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Müller, Paul, Mirjam Schürmann, Chii J. Chan et Jochen Guck. « Single-cell diffraction tomography with optofluidic rotation about a tilted axis ». SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35046.
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Optical diffraction tomography (ODT) is a tomographic technique that can be used to measure the threedimensional (3D) refractive index distribution within living cells without the requirement of any marker. In principle, ODT can be regarded as a generalization of optical projection tomography which is equivalent to computerized tomography (CT). Both optical tomographic techniques require projection-phase images of cells measured at multiple angles. However, the reconstruction of the 3D refractive index distribution post-measurement differs for the two techniques. It is known that ODT yields better results than projection tomography, because it takes into account diffraction of the imaging light due to the refractive index structure of the sample. Here, we apply ODT to biological cells in a micro uidic chip which combines optical trapping and microfluidic flow to achieve an optofluidic single-cell rotation. In particular, we address the problem that arises when the trapped cell is not rotating about an axis perpendicular to the imaging plane, but instead about an arbitrarily tilted axis. In this paper we show that the 3D reconstruction can be improved by taking into account such a tilted rotational axis in the reconstruction process.
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Jaara, Fatimeh. « On the structure of flow in an inclined settling column ». Thesis, University of Strathclyde, 1988. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21310.
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Although there have been useful developments in the theory of solid-liquid separation in inclined tubes, many assumptions and concepts have not been tested. In the present study the principal objective was to gain a clearer understanding of the settling mechanism through observation of the flow fields within a particle-free fluid layer which exists at the upper face of the bulk suspension and within the bulk suspension itself. Experimental investigations were carried out using glass beads in an aqueous glycerol solution. Preliminary tests in a vertical column showed that the relationship between the settling velocity Vc, and the solids concentration C could be described by Vc=A(1-C)n when n=4.66 In the subsequent work in an inclined column the flow field in the clear fluid channel and within the suspension core was studied for suspension under the concentration conditions Co = 0.1 and Co 0.2. Characteristics features (width, velocity and average flow) of the clear-fluid layer were measured and compared with existing theory. Generally it was shown that there is a fairly good agreement between theory and experiments especially at early stages of settling and away from the top interface. Particular attention was paid to mode of infiltration from the bulk suspension into the clear-fluid channel. Measurements of the concentration distribution along the settling column were carried out using an electro-conduct ivity technique from suspension. Fluid velocity was measured by a dye-tracer. From the data, it was seen that the fluid velocities within the suspension were exceedingly high, being roughly 10 times the buck settling velocity of the suspension. All the characteristics of the flow field within the clear-fluid channel indicate a change in behaviour between the upper and lower parts of the settling column and take place as if there was a form of rotation above and below a horizontal axis at the middle of the tube. Existing theory (PNK) was modified to take account of the height of the sediment layer at the bottom of the tube. This provided goodagreement with experimental data over the range of conditions studied, apart from the final stages of settlement.
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Rogers, Jeremy David. « Miniature Microscope Design And Construction Based On Tilted Rotationally Asymmetric Printed Lenses ». Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194489.
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Successful treatment of many types of cancer is improved when early detection is possible. One method of early detection is microscopic inspection of the tissue at risk. Microscopic inspection can be performed by extracting a biopsy and using traditional microscopes, but biopsy is painful and inconvenient which limits its use. An alternative is in vivo microscopy using an endoscope or microendoscopy. This dissertation describes the design, construction, and evaluation of a miniature microscope or microendoscope based on new microfabrication technologies.All components typically found in a traditional bench-top microscope were designed and built on a miniature scale. The objective was comprised of one planoconvex spherical glass lens and three printed microlenses. The printed lenses were patterned using grayscale lithography in a custom engineered photosensitive hybrid sol-gel glass material. Illumination was delivered by high-brightness Light Emitting Diodes (LEDs) via multimode fiber. The design incorporated a custom imaging detector and a Micro-Electrical-Mechanical-Systems (MEMS) actuator for optical sectioning using structured illumination. The opto-mechanical system is designed using a new concept called "zero alignment assembly" in which the lens elements snap into place and are constrained to a precise position with tolerances tighter than the optical tolerances. This scheme requires no post-assembly alignment or adjustment and simplifies system assembly. The miniature microscope was designed to image in several modes including reflectance, fluorescence, and using structured illumination for optical sectioning. A unique optical design incorporated tilted elements to remove ghost images and internal reflections from the image plane. This design enabled microscopic imaging of extremely low reflectance samples like tissue where the "in-focus" component of the object reflects only 0.04% of the illumination. The miniature microscope was built and tested by imaging a variety of test objects including cancer tissue phantoms and pig tissue. The results demonstrated the successful implementation of many new microfabrication technologies and design concepts to build a working prototype miniature microscope measuring only 3x4x15 mm capable of imaging cellular structure of tissue in reflectance or flourescence.
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Bastian, Janine [Verfasser]. « Derived equivalences for cluster-tilted algebras of types Ãn and Dn / Janine Bastian ». Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/1021441562/34.
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Fortmeier, Ines [Verfasser], et Wolfgang [Akademischer Betreuer] Osten. « Zur Optimierung von Auswerteverfahren für Tilted-Wave Interferometer / Ines Fortmeier ; Betreuer : Wolfgang Osten ». Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118507746/34.
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Le, Quang Tuan. « Magnetodynamics in Spin Valves and Magnetic Tunnel Junctions with Perpendicular and Tilted Anisotropies ». Doctoral thesis, KTH, Materialfysik, MF, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191176.
Texte intégralRésumé :
Spin-torque transfer (STT) effects have brought spintronics ever closer to practical electronic applications, such as MRAM and active broadband microwave spin-torque oscillator (STO), and have emerged as an increasingly attractive field of research in spin dynamics. Utilizing materials with perpendicular magnetic anisotropy (PMA) in such applications offers several great advantages such as low-current, low-field operation combined with high thermal stability. The exchange coupling that a PMA thin film exerts on an adjacent in-plane magnetic anisotropy (IMA) layer can tilt the IMA magnetization direction out of plane, thus creating a stack with an effective tilted magnetic anisotropy. The tilt angle can be engineered via both intrinsic material parameters, such as the PMA and the saturation magnetization, and extrinsic parameters, such as the layer thicknesses. STOs can be fabricated in one of a number of forms—as a nanocontact opening on a mesa from a deposited pseudospin-valve (PSV) structure, or as a nanopillar etching from magnetic tunneling junction (MTJ)—composed of highly reproducible PMA or predetermined tilted magnetic anisotropy layers. All-perpendicular CoFeB MTJ STOs showed high-frequency microwave generation with extremely high current tunability, all achieved at low applied biases. Spin-torque ferromagnetic resonance (ST-FMR) measurements and analysis revealed the bias dependence of spin-torque components, thus promise great potential for direct gate-voltage controlled STOs. In all-perpendicular PSV STOs, magnetic droplets were observed underneath the nanocontact area at a low drive current and low applied field. Furthermore, preliminary results for microwave auto-oscillation and droplet solitons were obtained from tilted-polarizer PSV STOs. These are promising and would be worth investigating in further studies of STT driven spin dynamics.Effekter av spinnvridmoment (STT) har fört spinntroniken allt närmare praktiska elektroniska tillämpningar, såsom MRAM och den spinntroniska mikrovågsoscillatorn (STO), och har blivit ett allt mer attraktivt forskningsområde inom spinndynamik. Användning av material med vinkelrät magnetisk anisotropi (PMA) i sådana tillämpningar erbjuder flera stora fördelar, såsom låg strömförbrukning och funktion vid låga fält i kombination med hög termisk stabilitet. Den utbyteskoppling (”exchange bias”) en PMA-tunnfilm utövar på ett intilliggande skikt med magnetisk anisotropi i planet (IMA) kan få IMA-magnetiseringsriktningen att vridas ut ur planet, vilket ger en materialstack med en effektivt sett lutande magnetisk anisotropi. Lutningsvinkeln kan manipuleras med både inre materialparametrar, såsom PMA och mättningsmagnetisering, och yttre parametrar, såsom skikttjocklekarna. STO:er kan tillverkas som flera olika typer - som en nanokontaktsöppning på en s.k. mesa av en deponerad pseudospinnventilstruktur (PSV) eller som en nanotråd etsad ur en magnetisk tunnlingsövergång (MTJ) –och bestå av mycket reproducerbar PMA eller av skikt med på förhand bestämt lutning av dess magnetiska anisotropi. MTJ-STO:er av CoFeB med helt vinkelrät anisotropi visar högfrekvent mikrovågsgenerering med extremt stort frekvensomfång hos strömstyrningen, detta vid låg biasering. Mätning och analys av spinnvridmoments-ferromagnetisk resonans (ST-FMR) avslöjade ett biasberoende hos spinnvridmomentskomponenter, vilket indikerar en stor potential för direkt gate-spänningsstyrda STO:er. I helt vinkelräta PSV-STO:er observerades magnetiska droppar under nanokontaktområdet vid låg drivström och lågt pålagt fält. Dessutom erhölls preliminära resultat av mikrovågssjälvsvängning och av s.k. ”droplet solitons” hos PSV-STO:er med lutande polarisator. Dessa är lovande och skulle vara värda att undersökas i ytterligare studier av STT-driven spinndynamik.
QC 20160829
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Inumoh, Lawrence Oyedeji. « Tilted wheel : 3 DoF torque generation for three axis control of a rigid satellite ». Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.656322.
Texte intégralRésumé :
Generation of control torque at low cost for highly agile satellite missions is generally achieved with momentum exchanged devices, such as momentum or reaction wheels and control moment gyros (CMGs) with high slew manoeuvrability. However, the generation of a high control torque from the respective actuators requires high power, large mass and high cost. The main objective of this research is to introduce a novel type of attitude control actuator that generates control torques about all three principal axes of a rigid satellite using only a spinning wheel and tilt mechanisms. The tilt mechanism changes the spin axis of the spinning wheel about the tilt plane axes thereby generating control torque about an axis in the plane that is orthogonal to both the tilt axes and the spinning wheel axis. To complete the 3 DoF torque generation, torque is generated about the spinning wheel axis by varying the spinning wheel speed. Few literature sources describe the concept of inertial actuator with 3 DoF torque capabilities. But in this research, a novel equation of motion is developed for the proposed inertial actuator from the fundamental laws of physics that does not require the popular pseudo-inversion as obtained with CMG systems. An extended LQR control law named HPB (High Performance Bounded) control that uses gain-scheduling and bounded torque control to provide better attitude performance than classical LQR with the advantage of incorporating a maximum torque constraints, was adapted to control a mathematical model of a rigid satellite. A prototype of the proposed actuator was built using commercial off the shelf components (COTS). The entire hardware design process is described and is accompanied with extended hardware and software simulations developed using CAD and MatLab/Simulink software. The newly proposed actuator has several distinct advantages compared to other existing inertial actuators. This includes the ability to generate active control torque in all principal axes of a rigid satellite compared to having conventional reaction wheels aligned to each of the three principal axes of the satellite or a cluster of CMGs. This translates to the lower mass, lower power requirement and low cost that are the critical driving factors in the design of any small satellite ACS. This new concept presents advantages for earth observation missions where the required slew angle is limited and for small satellites where accommodating multiple actuators reduces the size that can be allocated to payloads. Academically, significant contributions have been made to the field including: development of a new set of dynamic equations of motion for the inertial actuator, extending the conventional LQR control logic for a more time efficient control, 3 DoF testbed development, systematic design and build of the proposed actuator using commercial of the shelf components, and 3 DoF torque capability experimentation.
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Shkurmanov, Alexander, Chris Sturm, Jörg Lenzner, Guy Feuillet, Florian Tendille, Mierry Philippe De et Marius Grundmann. « Selective growth of tilted ZnO nanoneedles and nanowires by PLD of patterned sapphire substrates ». Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-210898.
Texte intégralRésumé :
We report the possibility to control the tilting of nanoneedles and nanowires by using structured sapphire substrates. The advantage of the reported strategy is to obtain well oriented growth along a single direction tilted with respect to the surface normal, whereas the growth in other directions is suppressed. In our particular case, the nanostructures are tilted with respect to the surface normal by an angle of 58°. Moreover, we demonstrate that variation of the
nanostructures shape from nanoneedles to cylindrical nanowires by using SiO2 layer is observed.
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Gintaute, Aiste [Verfasser], et Wael [Akademischer Betreuer] Att. « Accuracy of computerized and conventional impression-making procedures of straight and tilted dental implants ». Freiburg : Universität, 2016. http://d-nb.info/1119718031/34.
Texte intégral
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Aydt, Wayne. « EXPERIMENTAL STUDIES ON A SOLAR POWERED WATER PURIFICATION SYSTEM WITH PHASE CHANGE MATERIAL ENERGY STORAGE ». OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2323.
Texte intégralRésumé :
Accessibility to clean water which is necessary for a healthy lifestyle is a problem that spans the globe. Many societies that lack clean water are also without the energy resources such as electricity or gas that are used for purification. This project is on the development of a solar powered water purification system with Phase Change Material (PCM) energy storage and experimental studies on the system. Water distillation was achieved and analyses were performed on the effects of weather conditions on the distillate production. Solar systems are affected by limited sunshine which occurs only during daylight hours. A second part of the research involved adding a PCM heat exchanger to the system to extend distillation beyond the daylight hours. The analyses evaluated distillate production against outdoor conditions such as temperature, wind speed, and use of the PCM heat exchanger, to determine how they affect the performance of the system. Results show that increased outdoor temperature and clear atmospheric conditions yield greater distillate production. The effects of wind speed were less conclusive. Use of the PCM heat exchanger shifted production to later in the day, but overall, resulted in lower daily production than when the heat exchanger was bypassed. The most definite indicator of distillate production was the temperature differential between the water entering the still and the outdoor temperature.
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Dauson, Erin. « Microparticle Separation Using Bulk Acoustic Waves in a PMMA Prism with a Tilted-Angle Channel ». Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/639.
Texte intégralRésumé :
Separation of microparticles without tagging or relying on charge, polarization or magnetic properties is important in many applications including biological and chemical analysis. Piezoelectric transducers can be used to create a standing acoustic wave field in a microfluidic channel, and these acoustic fields have been used to separate particles by size. In a standing acoustic wave field, particles experience a force towards the acoustic nodes which is proportional to the particle volume. This force is opposed by the drag force on the particle from the fluid. The drag force is proportional to particle radius. Consequently, larger particles move faster towards acoustic nodes than smaller particles. By applying these forces at an angle it is possible to separate particles by size in a continuous flow device. The tilted angle design enables particle separation of greater than a single wavelength. The overarching objective of the research was to sort particles by size. I developed standing surface acoustic wave (SSAW) devices on lithium niobate, and used PDMS (polydimethylsiloxane) as a microfluidic channel material. I used these devices to demonstrate particle concentration and understand the acoustic behavior of the devices and particle behavior in this acoustic environment. PDMS has the drawbacks of high attenuation, and difficulty in fabrication for large scale applications, so it is advantageous to use PMMA (Poly(methyl methacrylate)) as a channel material because of its mechanical robustness, its lower attenuation, and its suitability for manufacturing. Consequently, I developed SSAW devices with PMMA channels to understand this material. v I explored the idea of using an acoustic field, tilted (rotated, yawed) with respect to microfluidic flow, to separate particles by size in a SSAW device. Though effective, this separation scheme has limits on channel height (which reduces throughput), and limits the size range of particles that can be separated. To address the limitations of SAW (surface acoustic wave) tilted angle particle separation devices, I created a PMMA prism and excited bulk acoustic waves (BAW) using PZT (lead zirconate titanate) transducers through the PMMA into a tilted angle channel in the prism. I used microfluidic flow in this acoustic field to separate particles by size. The PMMA prism tilted angle channel design is easier to fabricate and more mechanically robust than a tilted angle SAW device. By analyzing particle trajectories using simulated and experimental results, I have determined how changing design and operation parameters of the separation device influences how particles move. Understanding the particle trajectories of different particle sizes allows us to choose design and operational parameters to enable particle separation. Particle separation in PMMA prism devices works, but a particle separation device should be optimized for a specific separation application for the most effective particle separation. My key contributions include: the tilted angle configuration, the PMMA prism and BAW configuration, and combining simulated and experimental results to generate phase diagrams characterizing particle trajectories.
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BRESCHIGLIARO, SARA. « Valutazione radiografica del rimodellamento osseo crestale su impianti inclinati : follow up da 1 a 10 anni ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/104991.
Texte intégralRésumé :
The aim of this study is evaluate on radiographic examination bone resorption on tilted implants placed with a minimal angulation of 15 degrees compared with the occlusal plane. The purpose is to demonstrate if a correlation between tilted implants and crestal bone resorption exist.
In this study we evaluated orthopantomography done at T0 moment when implants have been loaded and at T1 moment: between 1 and 10 years from loading.
Values are calculated using a specific program: we have measured the importance of bone resorption in mm both mesial and distal from the implant surface and catalogued only implants with more then 15 degrees angulation.
This study demonstrated that the use of tilted implants is safe and is not associated to a higher marginal bone loss as compared to axially placed implants: no statistically significant difference in implant success was observed. Obviously is compulsory evaluate different aspects: for example if the implant is rehabilitated individually or if is in a full-arch fixed restoration, or if the implant is located in natural bone or in presence of bone grafted.
This study demonstrate that increasing of angulation of implant insertion doesn’t mean necessary an increasing of implant failure; considering different variables is necessary to obtain a predictable study. New studies with a larger number of patients and implants inserted are essentials.
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Moros, Eduardo Gerardo 1960. « SIMULATIONS OF SCANNED FOCUSSED ULTRASOUND HYPERTHERMIA : THE EFFECTS OF SCANNING SPEED, SCANNING PATTERN AND MULTIPLE TILTED TRANSDUCERS ». Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276440.
Texte intégralRésumé :
A transient three-dimensional simulation program was developed to study the effects of scanning speed, scanning pattern, blood perfusion, transducer choice and multiple tilted transducers with overlapping foci during scanned focussed ultrasound hyperthermia. The results showed that (1) the temperature fluctuations increase linearly with decreasing scanning speed, (2) the temperature fluctuations are a weak, increasingly exponential function of the blood perfusion rate, and (3) that the largest temperature fluctuation is always located at the acoustical focal depth on the scan path independently of focal plane depth. Simulations using multiple scan paths showed that relatively uniform average temperature distributions can be achieved at the focal zone as long as the spacing between the concentric scans was not greater than the diameter of the focus of the power field. Finally, the results showed that using multiple tilted transducers with overlapping foci, increased focussing can be obtained at the focal depth.
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Tsai, Chin-Lai, et 蔡金來. « Studies on tunable tilted magnetic anisotropy ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/38068200948283715886.
Texte intégralRésumé :
碩士國立臺灣大學
物理研究所
102
The exchange spring behaviors and title magnetic anisotropy were studied on L11-CoPt/NiFe bilayer systems. In this investigation L11-CoPt alloy film and Ni81Fe19 ( Permalloy ) films were exploited for the hard-layer with out-of-plane (OOP) and for the soft-layer with in-plane (IP) anisotropy, respectively. Through adjusting the interlayer exchange coupling between hard-layer and soft-layer, the tunable tilted magnetic anisotropy of the soft layer can be obtained. All the films studied herein were prepared by magnetron sputtering using glass as substrates along with a seed Pt layer of 20 nm. Before the L11 CoPt/NiFe bilayer systems were intensively investigated, the magnetic properties of bare L11 CoPt or NiFe layer were studied first. Afterwards three different approaches as shown below were adopted to investigate the exchange spring behaviors of L11 CoPt/NiFe bilayer systems: Varying the thickness of NiFe layer while keeping the thickness of L11 CoPt constant. Varying the deposition temperature of L11-CoPt layer while depositng the NiFe layer always at room temperature.. Inserting a nonmagnetic layer by using either Pt or Ru between L11 CoPt and NiFe layers. Our results reveal that the tilted magnetization angle of NiFe layer can be varied from 0° to 75°;Secondly, different processing temperature results in different interlayer coupling strength, casuing different magnetization tilted angle of NiFe layer; Third, the interlayer coupling strength decays rapidly as the thickness of Pt spacer is increased. The magnetization of NiFe is almost lying on the film plane when the thickness of Pt reachs 4 nm. Lastly, the two layer coupling strength as well as the tilted angle of NiFe layer oscillates with the thickness of Ru layer. The above results demonstrate that the tunable tilted exchange springs can be realized with L11-type CoPt/NiFe bilayers. Furthermore, the possibilities of future applications in three-axis magnetic sensors or advanced spintronic devices demanding inclined magnetic anisotropy polarizer are justified.
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Wang, Shiang-Yu, et 王祥宇. « The study of diffractive propagation on a tilted plane or through a tilted device with angular spectrum ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/3x4gyw.
Texte intégralRésumé :
碩士國立臺北科技大學
光電工程系研究所
95
An angular spectrum, with special features of obvious physical meaning, fast calculation and unnecessary approximation, can be used to facilitate optical diffraction. In order to get a picture about the properties of angular spectrum as a method of light propagation, Several studies have been conducted to apply the scalar diffraction theory to examine optical diffraction on tilted plane. Pioneers in this field adopted the Rayleigh-Sommerfeld diffraction integral to tackle with the problem, using fast Fourier transform that required complicated substitution. Subsequent researchers started to use angular spectrum of plane wave to achieve faster calculation by saving fast Fourier transform from the trouble of complex approximation and substitution,and our study also use this way. The new method, though more efficient, fails to offer a workable solution to the problem about the corresponding spatial frequency on the tilted plane. Since this problem, if not solved, at first we can obstruct the direct and smooth application of fast Fourier transform, this paper proposes to solve the problem by means of interpolation and shift in frequency domain. Moreover, the Jacobin factor is used to compensate the problem that total energy cannot be conserved after rotational transformation. In addition to the above problems related to the tilted plane, angular spectrum of plane waves has its own restriction, notably its narrow observation range in diffraction plane . In order to expand the observation range, the paper has examined and analyzed the relationships between relevant parameters such as the sampling number, the size of aperture. As focus has been placed on near field in previous studies, the paper has further discussed the diffractive field by using angular spectrum of plane wave in far field.
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Lin, Chun-Wei, et 林俊偉. « A calibration of the tilted geometric distortion ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/15684910237200908381.
Texte intégralRésumé :
碩士中華大學
電機工程學系碩士班
102
When the picture of an object is not perpendicularly taken by a camera, the captured image is distorted due to the view angle and the magnifying power that depends on object distance. For an example, if a circle is shot with a small tilt angle, its captured image resembles an ellipse due to view angle. If it is shot with a large tilt angle, its captured image apparently does not resemble an ellipse due to magnifying power in addition to view angle. This thesis measured and analyzed the geometric distortions of images due to the tilt angle. The images are calibrated and recovered. A restoration function based on the distance from the center point of the image is defined. We showed that images can be recovered with this restoration distortion. But for the case with a large tilt angle, the recovered image is blurred due to the limited depth of field. For the experimental condition of this thesis, the recovered image is poor for the tilt angle larger than about 60 degrees.
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Dinis, Marco Rafael Basílio. « Drusen do disco óptico e tilted disc ». Master's thesis, 2014. http://hdl.handle.net/10451/24362.
Texte intégralRésumé :
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014The drusen of the optic disc is an uncommon disease that's due to the abnormal accumulation of hyalin-like material in this structure, being itself a cause for pseudopapilledema. It affects 0,3-2,0% of the population, with major incidence on the caucasians, and it's just identifiable from the first decade of life on. It can be expressed by peripheral visual loss, sudden or progressively, and can also cause retinian hemorrhage. Its etiology isn't completely known, it is thought that the accumulation of calcified debris is caused by a defect on the axonal metabolism. On another hand, tilted disc is an anatomic variation which is responsible for refractive errors such as myopia and astigmatism, rarely being associated with drusen. Knowing the etiology, signs and symptoms, as well as the diagnostic plan, is essential for the clinical intervention. Therefore, there will be a theorical review and a clinical case discussion.
O drusen do Disco Óptico (DO) é uma patologia incomum que se deve à acumulação anormal de material hialino nesta estrutura, sendo uma causa de pseudopapiledema. Afecta 0,3-2,0% da população, com maior incidência caucasiana, e apenas é identificável a partir da primeira década de vida. Poderá manifestar-se por perda de visão periférica súbita ou progressiva, podendo também provocar hemorragia retiniana. De etiologia não totalmente conhecida, pensa-se que a acumulação de detritos calcificados seja devido a um defeito no metabolismo axonal. O tilted disc, por sua vez, é uma variante anatómica que é responsável por erros de refracção como a miopia e o astigmatismo, estando raras vezes associado ao drusen. O conhecimento etiológico, os sinais e sintomas, bem como o plano diagnóstico, é essencial para a intervenção clínica. Assim, será feita uma revisão teórica e abordado um caso clínico.
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Lin, Meng-Wei, et 林孟緯. « Terahertz parametric amplifier with wavefront tilted pump ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5z8a7n.
Texte intégral
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Huang, Zhiqi Jr. « Probing Early and Late Inflations Beyond Tilted LambdaCDM ». Thesis, 2010. http://hdl.handle.net/1807/26193.
Texte intégralRésumé :
The topic of this thesis is about cosmic inflations, including the early-universe inflation that seeds the initial inhomogeneities of our universe, and the late-time cosmic acceleration triggered by dark energy. The two inflationary epochs have now become part of the standard $\Lambda$CDM cosmological model. In the standard paradigm, dark energy is a cosmological constant or vacuum energy, while the early-universe inflation is driven by a slowly rolling scalar field. Currently the minimal $\Lambda$CDM model with six parameters agrees well with cosmological observations.
If the greatest achievement of the last twenty golden years of cosmology is the $\Lambda$CDM model, the theme of future precision cosmology will be to search for deviations from the minimal $\Lambda$CDM paradigm. It is in fact expected that the upcoming breakthroughs of cosmology will be achieved by observing the subdominant anomalies, such as non-Gaussianities in the Cosmic Microwave Background map. The aim of this thesis is then to make theoretical predictions from models beyond $\Lambda$CDM, and confront them with cosmological observations. These models include: 1) a new dark energy parametrization based on quintessence models; 2) reconstructing early-universe inflationary trajectories, going beyond the slow-roll assumption; 3) non-Gaussian curvature fluctuations from preheating after the early-universe inflation; 4) infra-red cascading produced by particle production during inflation; 5) preheating after Modular inflation; 6) decaying cold dark matter. We update the cosmological data sets -- Cosmic Microwave Background, Type Ia supernova, weak gravitational lensing, galaxy power spectra, and Lyman-$\alpha$ forest -- to the most current catalog, and run Monte Carlo Markov Chain calculations to obtain the likelihood of parameters. We also simulate mock data to forecast future observational constraints.
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Li, Kuan-ting, et 李冠廷. « Surface Plasmon Resonance Sensor Based on Tilted Gratings ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/17467017292843528539.
Texte intégralRésumé :
碩士逢甲大學
自動控制工程學系
104
In this study, an optical fiber-based microsensor is developed by designing tilted optical fiber grating measurement system based on surface plasmon resonance technology. The tilted fiber gratings were applied to excite the surface plasma wave and evanescent coupling with a surface plasmon resonance. In order to improve its sensing sensitivity, we have polished single side of optical fiber in the written tilted fiber gratings. The fabrication process is divided into three steps. First, by writing tilted fiber gratings in optical fiber, the light can enter into cladding. Second, by using side polishing fabrication in the written tilted fiber gratings, enhance the evanescent field can be enhanced obviously. Finally, by using a sputtering machine to deposit metal films on the surface of optical fibers, they are main media of surface plasma resonance. The sensors have been completed after above-mentioned fabrication. In this study, the incident light with 780 nm wavelength was used as the laser source because the wavelength approaches surface plasmon resonance wavelength. It have good sensing sensitivity and the space of tilted fiber gratings is 780 nm. Experimental results show that the sensitivity of brine and blanching water are 48.11 nm/RIU and 158.73 nm/RIU respectively.
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Lei, Shih-Cing, et 雷士慶. « Analysis of First Order Tilted Fiber Bragg Gratings ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/50441805917088698698.
Texte intégralRésumé :
碩士義守大學
電機工程學系
102
In this paper, we measure the transmission, the reflection and the radiation spectrum of first-order titled fiber Bragg gratings (TFBGs). We change the parameters of titled fiber gratings to measure the characteristics of TFBGs, where these parameters include the titled angle, fiber material and exposure time. For the TFBGs made by SMF28 with tilted angle of 1˚, the resonance region is from 1539.6nm to 1540.8nm. The maximum reflection efficiency and minimum transmission efficiency are -0.3dB and -31.57dB, respectively, in the resonance region. The radiation has non-wavelength selective property. The radiation efficiency is -27.5dB out of the resonant region. The radiation efficiency of titled 45˚ TFBGs is bigger than the other TFBGs. The resonance region of tilted 45˚ FBGs with exposure time of 3 minutes ranges from 1539.4nm to 1540.4nm. The maximum reflection efficiency and minimum transmission efficiency are -1.84dB and -34.68dB, respectively, in the resonance region. Off resonance, the radiation efficiency is -11.03dB. We also discover an image of a near field intensity an 3D view of field pattern scans by using infrared camera an Beam profile.
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Chang, Che-Yu, et 張哲瑜. « Comparison of non-tilted and tilted mesial implants for mandibular “All-on-four” treatment protocol : A 3-D finite element analysis ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/nthq89.
Texte intégralRésumé :
碩士國立陽明大學
牙醫學系
103
Purpose: The aim of this study was to evaluate the biomechanical effect of peri-implant bone between non-tilted and tilted mesial implants for mandibular “All-on-four” treatment protocol. The difference of the biomechanical effect between the conditions of complete and imperfect osseointegration would be evaluated as well. Materials and methods: Three-dimensional FE models were consisted of mandibular bone, dental implants and superstructures with two different configurations: one model follow the “All-on-four” protocol, the other one changed the inserted angle of bilateral mesial implants with mesially tilted by 30 degrees. Imperfect and complete osseointegration were simulated and 250 N oblique occlusal loading was applied on the occlusal surface of left first molar. Stress of peri-implant bone and micromotion of implants were determined. Results: Under the same bone-to-implant interface, the distribution of peri-implant bone stress was similar in tilted and non-tilted models; however, the stress value of peri-implant bone was lower (up to 66%) in tilted model. Stress concentrated in cortical bone and implant near loading area when complete osseointegrated; however, under imperfect osseointegration, stress more evenly distributed in both cortical and cancellous bone and around each implant. The micromotion of implants were similar in both models under imperfect osseointegration. Conclusions: Changing the inserted angle of mesial implants in “All-on-four” protocol did not obviously alter the pattern of stress distribution and the primary stability of implants under imperfect osseointegration. However, the stress value of peri-implant bone was lower than non-tilted model after complete osseointegration.
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Chang-Chung, Wen, et 文長中. « Improvement of CDMA cellular system performance by Tilted Antenna ». Thesis, 1995. http://ndltd.ncl.edu.tw/handle/05675093774917440821.
Texte intégralRésumé :
碩士國立中央大學
電機工程研究所
83
CDMA 系統目前已列為第二代數位式行動電話系統的標準之一，稱之為 IS-95。 而本論文探討在實際行動電話系統中，各扇區(sector)之話務 量(traffic)為非均勻(nonhomogenous)時，如何將"Hot-Spot"扇區的話務 量，疏解至其相鄰的扇區，進而降低掌控"Hot-Spot"扇區基地台之阻絕機 率(blocking probability)，使整個系統都能在服務品質(QoS)為1%之下 運作。由於CDMA系統與FDMA及TDMA系統不同，其頻率重用因素( frequency reuse factor)趨近1.0，也就是各扇區都使用相同的頻譜範 圍(spectrum range)，所以我們利用傾斜式天線(tilted antenna)減少其 他扇區所產生的同頻干擾，進而改善話務量不均勻的現象，提高系統的服 務品質。本篇論文針對話務量非均勻現象，首先，提出" 固定式天線傾斜 機制 "，以疏解"Hot-Spot"扇區的話務量。此外，本論文亦提出" 天線傾 斜角之動態調整機制"，採用中央控制模式(centralized control)調整各 基地台天線傾斜角度，以改進話務量不均所導致的問題，此方法較前者容 易應用在實際的系統中。經由模擬驗證，證實此二種方法確實都能增進系 統之效能，使位在服務區(service area)內的用戶都享受公平的服務品質 。
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Chao, Wei-Chi, et 趙文祺. « Measurement of Tilted Fiber Bragg Gratings using polarization controller ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/c7ms4e.
Texte intégralRésumé :
碩士義守大學
電機工程學系
104
The transmission, reflection and radiation spectrum of fiber Bragg gratings (FBGs) with a polarization controller are measured in this thesis, where FBGs include first-order FBGs, tilted FBGs (TFBGs) and second-order FBGs. The experimental results show that polarization controllers do not affect the properties of FBGs. However, the radiated efficiencies increase 5.55dB and 5.88dB by a polarization controller for 1° and 45° TFBGs, respectively. The maximum radiation efficiency of TFBGs can reach 6.25dB. In addition, we measured the radiation efficiency as a function of an angle for second-order FBGs. We find the radiative angles of second-order FBGs are near 45°, 90° and 135°, where the maximum radiated angle is 135°. In this study, the maximum radiation efficiency at 135° is -26.70dB and occurs at the short wavelength side boundary of the resonant region.
46
SHIH-CHIEH, CHANG, et 張仕杰. « STRESS ANALYSIS OF FIXED PROSTHESES ON MANDIBULAR TILTED ABUTMENT ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/54722232212226177792.
Texte intégralRésumé :
碩士高雄醫學院
牙醫學研究所
87
The purpose of this study was to evaluate the stress distributions to the abutments of a fixed partial denture with tilted molar abutments. In cases of the lower first molar being missing, photoelastic models were made with 3-unit fixed partial dentures of which the second molars were tilted 0 degrees, 10 degrees, 20 degrees, 30 degrees, and 40 degrees mesially towards the occlusal surface. A vertical load of 79.0 Newton was applied distally to the pontic 9mm from the marginal ridge of the second premolar. Quasi-3D photoelastic stress analysis was used, and the stresses were recorded photographically. The quasi-3D technique of photoelastic stress analysis method was used to evaluate the stress of mandibular posterior fixed partial dentures (FPD) with mandibular second molar mesio-tipping. The points located at 5 mm directly below the root apexes and at 3mm away from the roots were chosen as the "standard points". The "material fringe value" is introduced into the definition of the "stress concentration index" by multiplying the fringe orders. And the fringe orders were counted with a null-balance compensator. Five photoelastic models were compared quantitatively by determining the stress concentration. From the isochromatic patterns and the Id values, a fourfold increase in stress in the artificial bone at the mesial aspect of the terminal abutment was observed when the load to the long axis was altered from 0 degrees to 30 degrees. The photoelastic models showed that the variation in the stress concentration index also increased directly with inclination, and incrementally increased from 30 degrees to 40 degrees. In the models studied, it should be emphasized that a mandibular posterior fixed partial denture being placed with terminal abutment tilted more than 30 degrees must be critically evaluated.
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Lin, Bing-Hua, et 林炳樺. « Heat Transfer Analysis and Enhancement of Tilted Smart Phones ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/47363967043495069428.
Texte intégralRésumé :
碩士國立臺灣海洋大學
機械與機電工程學系
103
Smart phones have become a slim, multifunctional, and high-density mobile communication device. Chips need to possess sound and stable processing performance under various operating conditions. In order to eliminate high temperature effects and to assure longer life circle, heat dissipation in smart phones is an important topic. This study measures the temperature distribution in a horizontally oriented cell phone as the benchmark. Numerical simulation is conducted to obtain the thermal field under same condition. It is found that the agreement between the two is within a reasonable range (less than 10 %). Thus the numerical model can be regarded as accurate and acceptable. More simulations are executed for phones with various inclination angles. The associated buoyancy effects on the thermal field are observed. Since the heat generated in the CPU accumulates in the PCB, so the neighboring chips are influenced. Heat transfer enhancement via conduction is proposed to correct the waste heat accumulation problem. It is understood from simulation and analysis that CPU is the primary component for waste heat. It also has significant impact on the power management IC, the audio decoder, and the multichip package RAM. Therefore the temperatures of the four chips are monitored. Several heat dissipation improvements are proposed and the associated effects are examined, such as changing the packaging material, PCB material, and the casing material, and inserting heat sinks on top of CPU with different materials. A combination of the above improvements can decrease the operating temperatures of the chips and solve the waste heat problem effectively. It is also found that the buoyancy effect diminishes with the use of improvements; that is, the thermal fields do not change significantly for different inclination angles.
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Wang, Yuan-Chang, et 王元昌. « Study of the Tilted Fiber Bragg Grating Biochemical Sensor ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20563537297923520535.
Texte intégralRésumé :
碩士國防大學中正理工學院
電子工程研究所
94
The purpose of this study is to implement a biochemical sensor based on a tilted fiber Bragg grating (TFBG). For the slanted gratings, the number of cladding modes and the intensity of the loss peaks of cladding modes are dependant on the tilted angle. This phenomenon can be confirmed by the theoretical calculations and experimental results. However the sensing sensitivity of the higher modes comparing with that of the core mode or lower order modes should be better for monitoring the biochemical media. The detection performance of cladding modes of this fiber sensor will be improved. In this thesis, the spectrum of organic compounds, such as the alcohol, is firstly to be investigated and then by means of experimental measurement, the difference between the carbon bonds and concentration variation can be distinguished. Moreover, TFBG sensor may provide a better performance to recognize an alcohol metamer from other types with the same number of carbon and hydrogen bonds but chemical structure. For sensing the isopropanol, the wavelength shift of the 9th cladding mode is greatly more than that of the fundamental core mode. For measuring biochemical experiments, we could monitor the nitrobacteria decompose and nitrify amino compounds in water. By the daily measurement, we would also observe the pH value of samples to be decreased and the number of bacteria to be increased. The quality of water tends to steady after about the 7th day. Therefore, we could apply this sensor to monitor the quality of water in environmental protection or aquatic farm. Finally, a fiber sensor based on the polyaniline coating technique on the surface of an etched TFBG as a sensing film is developed for detecting volatile toxic vapors. It can effectively be used to detect harmful vapors, such as hydrochloride (HCl) and ammonia (NH3). Besides, it can be extended to the applications of monitoring air pollution and the water quality.
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Tseng, T. W., et 曾大衛. « Experiment and Thermal Analysis on the Tilted LED Streetlamp ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/92350600628358066778.
Texte intégralRésumé :
碩士國立臺灣海洋大學
機械與機電工程學系
100
This study conducts experiment and numerical simulations to investigate the heat transfer problem of heat modules in an LED streetlamp under various inclination angles from the horizontal plane. The tilt angles vary from 0 degree to 60 degrees with an increment of 10 degrees. As the angle increases, the temperatures of the front MCPCB’s and the LED lenses increase accordingly whereas the rear temperatures decrease at first and then increase. The experimental results depict similar trend to the numerical simulations. At the inclination angle of 10 degrees, possible improvements are discussed. It is found that 8 or 9 fins for the heat sink render lower components temperatures. With fin height of 70 mm, a decrease of 4℃ can be achieved. As the thickness increases from 2.3 mm to 3.3 mm, the temperatures of MCPCB’s and LED lenses drop down. As for the opening effect, the opening at the front end renders higher temperatures while the bottom opening enhances the convection flow and lowers MCPCB’s and LED lenses temperatures 1 to 2 degrees, and 6 to 7 degrees at the upper air flow exit. An improvement on the coating material decreases the LED lenses temperatures 3 to 5 degrees. The replacement of silica gel for epoxy resin renders lower temperatures (down 1 to 2 degrees). The use of aluminum on the LED chip cover decreases the lenses temperatures more than 5 degrees; a combination of the aluminum cover and the improved coating material renders even lower temperature, down by 7 to 8 degrees. This work provides feasible solution to the cooling of the LED streetlamps by ventilation and natural convection. As such, the operating temperature can be decreased effectively and hence the life of the LED streetlamps can be extended.
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HSU, YA-CHUN, et 許雅淳. « Innovational Implementation and Application of Tilted Fiber Bragg Gratings ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e7ksmq.
Texte intégral