Dissertations / Theses on the topic 'Topography'
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1
Reid, G. T. "Automatic moire topography." Thesis, University of Strathclyde, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314722.
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Wiemer, Jan C. "Learning topography in neural networks towards a better understanding of cortical topography /." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962378798.
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Mengesha, Yoseph Gebrekidan. "Atmospheric boundary-layer flow over topography data analysis and representations of topography /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39212.pdf.
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Coller, Bryan. "The topography of relief." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12737.
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Thesis (M.F.A.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
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Cenedese, Claudia. "Baroclinic eddies over topography." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624104.
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Thompson, LuAnne. "Flow over finite isolated topography." Thesis, Woods Hole, Mass. : Woods Hole Oceanographic Institution, 1990. http://catalog.hathitrust.org/api/volumes/oclc/23822687.html.
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Carter, Glenn S. "Turbulent mixing near rough topography /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/10976.
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Zankofski, Deborah Ann. "Interaction of fronts with topography." Thesis, Monterey, California. Naval Postgraduate School, 1985. http://hdl.handle.net/10945/21389.
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Tate, Nicholas J. "The fractal dimension of topography." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318094.
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Winterbourne, Jeffrey Richard. "Dynamic topography in the oceans." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610506.
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Fallon, Martin. "Surface topography of silicon microcircuits." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/13812.
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The shrinking dimensions of silicon microcircuits have reached the point where the vertical and lateral features are comparable in size. The consequence can be seen in each aspect of the manufacture of devices. The 2D layout of the physical routing becomes a convoluted maze when put into fabrication. The diminishing dimensions have focused greater attention on the edge effects since these play a proportionately greater role in the device performance. The consequences of the edge interactions can be categorised into two sections: those on the silicon surface and those on the subsequent layers. The MOS transistor is directly impacted by the silicon surface profile. A fundamental parameter is the transistor width, which until recently has received little attention. This thesis correlates the different definitions commonly used, and investigates the impact of the individual processing parameters on the surface topography and consequently on the transistor width. Different measurement techniques are used and a novel extraction process is proposed. The weakness of the current generic electrical extraction technique is exposed and recommendations made to overcome this. Further work on SEM sample preparation and processing is presented.
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Campbell, James Matthew. "On topography and crystal nucleation." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/6829/.
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The influence of topography on crystal nucleation is investigated, mostly with regards to nucleation from vapour but also regarding nucleation from the melt and from solution. Two mechanisms are discussed for acute features to promote nucleation: a thermodynamic reduction in the free energy barrier provided by a favourable geometry, and the formation of a confined condensate of a metastable phase which then transitions to the crystalline phase. Organic compounds nucleating from vapour are used to demonstrate the efficacy of scratches and mineral steps as preferable nucleation sites. A study of various compounds on mica demonstrates that highly acute features provide the most favourable nucleation sites. High-magnification study of the growth of crystals from such features reveals the presence of small condensates prior to the appearance of bulk crystals, and the growth of these is studied quantitatively. Ice is shown to have a similar nucleation site preference to the organic compounds, although no condensate was seen prior to bulk nucleation. Well-defined 100 nm-wide trenches were milled into silicon substrates and shown to have a great ability to direct ice nucleation. The freezing of picolitre droplets of water was studied on smooth and roughened silicon, glass and mica substrates, and the roughening was shown to have little to no effect. Calcium carbonate growth and its dependence on topography was investigated, and found to be broadly anomalous and greatly dependent on surface chemistry.
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Wilkinson, Andrew James. "Biomimetic topography in orthopaedic ceramic." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7791/.
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The primary objective of this research was to perform an in vitro assessment of the ability of microscale topography to alter cell behaviour, with specific regard to producing favourable topography in an orthopaedic ceramic material suitable for implantation in the treatment of arthritis. Topography at microscale and nanoscale alters the bioactivity of the material. This has been used in orthopaedics for some time as seen with optimal pore size in uncemented hip and knee implants. This level of topography involves scale in hundreds of micrometres and allows for the ingrowth of tissue. Topography at smaller scale is possible thanks to progressive miniaturisation of technology. A topographic feature was created in a readily available clinically licensed polymer, Polycaprolcatone (PCL). The effect of this topography was assessed in vitro. The same topography was transferred to the latest generation composite orthopaedic ceramic, zirconia toughened alumina (ZTA). The fidelity of reproduction of the topography was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). These investigations showed more accurate reproduction of the topography in PCL than ZTA with some material artefacts in the ZTA. Cell culture in vitro was performed on the patterned substrates. The response of osteoprogenitor cells was assessed using immunohistochemistry, real-time polymerase chain reaction and alizarin staining. These results showed a small effect on cell behaviour. Finally metabolic comparison was made of the effects created by the two different materials and the topography in each. The results have shown a reproducible topography in orthopaedic ceramics. This topography has demonstrated a positive osteogenic effect in both polycaprolactone and zirconia toughened alumina across multiple assessment modalities.
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Klöcking, Marthe. "Continental magmatism and dynamic topography." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271750.
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Isostasy, flexure and dynamic processes all influence the shape of the Earth’s surface. While the first two processes are well understood, dynamic topography remains controversial. On the continents, dynamic uplift is often expressed by positive long-wavelength gravity anomalies, radial drainage patterns, and slow seismic velocity anomalies within the upper mantle. Volcanic activity and elevated heat flow are also often observed. The aim of this study is to investigate the link between geochemical compositions of intracontinental magmatism and geophysical, geomorphological and geodetic observations of dynamic uplift. Three volcanic regions are considered in detail: western North America, northeast Brazil and Madagascar. The combined database includes 348 new whole-rock geochemical analyses. Rare earth element concentrations of mafic, asthenospheric-derived volcanic samples are exploited to calculate the depth and temperature of melt generation by inverse modelling. A sensitivity test of this modelling scheme is carried out. Lithospheric thickness and mantle temperature are independently determined from shear wave velocity models. Beneath western North America, a negative correlation between shear wave velocities at depths of 70–150 km and degree of melting is observed. Temperatures obtained from igneous compositions and from shear wave velocity profiles beneath volcanic fields closely agree. Melts are produced within, or close to, the spinel-garnet transition zone at depths shallower than $\sim$70 km, yielding mantle potential temperatures of up to 1380$^{\circ}$C. Calculated uplift and heat flow based upon these results match observed surface elevation and heat flow measurements. In northeast Brazil, Jurassic, Cretaceous and Cenozoic phases of mafic igneous activity are recognised. Jurassic magmatic activity probably resulted from spinel-field melting at potential temperatures of $\sim$1380$^{\circ}$C. This episode is associated with regional magmatism during break-up of the Central Atlantic Ocean. Cretaceous compositions record melting at potential temperatures of 1330–70$^{\circ}$C at similar depths. This activity is linked to extension at the time of break-up of the equatorial and South Atlantic Ocean. Cenozoic volcanism comprises low-degree melts within the spinel-garnet transition zone at ambient potential temperature. Shear wave velocity models support these results. Cenozoic volcanism in Madagascar is predominantly alkaline and records small-degree melting with minor temperature anomalies within the spinel-garnet transition zone. Rare tholeiitic basalts record temperatures up to 1360$^{\circ}$C. Analysis of global and regional shear wave velocity models closely matches these results. The principal control on continental magmatism appears to be temperature anomalies within the upper mantle beneath thin lithosphere. Highest mantle potential temperatures correlate with largest dynamic uplift. Mantle potential temperatures $ < $1350$^{\circ}$C are matched with minimal or negative dynamic topography.
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Beyer, Andreas. "Seafloor analysis bsed on multibeam bathymetry and backscatter data = Meeresbodenanalyse auf der Basis von Bathymetrie und akustischer Rückstreuung /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2006. http://www.loc.gov/catdir/toc/fy0711/2007403021.html.
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Beyer, Andreas. "Seafloor analysis based on multibeam bathymetry and backscatter data = Meeresbodenanalyse auf der Basis von Bathymetrie und akustischer Rückstreuung /." Bremerhaven : Alfred-Wegener-Inst. für Polar- und Meeresforschung, 2006. http://www.loc.gov/catdir/toc/fy0711/2007403021.html.
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Kunz, Jacob Andrew. "Probabilistic modeling of microgrinding wheel topography." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49118.
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This work addresses the advanced probabilistic modeling of the stochastic nature of
microgrinding in the machining of high-aspect ratio, ceramic micro-features. The
heightened sensitivity of such high-fidelity workpieces to excessive grit cutting force
drives a need for improved stochastic modeling. Statistical propagation is used to
generate a comprehensive analytic probabilistic model for static wheel topography.
Numerical simulation and measurement of microgrinding wheels show the model
accurately predicts the stochastic nature of the topography when exact wheel
specifications are known. Investigation into the statistical scale affects associated
microgrinding wheels shows that the decreasing number of abrasives in the wheel
increases the relative statistical variability in the wheel topography although variability in
the wheel concentration number dominates the source of variance. An in situ
microgrinding wheel measurement technique is developed to aid in the calibration of the
process model to improve on the inaccuracy caused by wheel specification error. A
probabilistic model is generated for straight traverse and infeed microgrinding dynamic
wheel topography. Infeed microgrinding was shown to provide a method of measuring
individual grit cutting forces with constant undeformed chip thickness within the grind
zone. Measurements of the dynamic wheel topography in infeed microgrinding verified
the accuracy of the probabilistic model.
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Sacerdotti, Franco. "Surface topography characterisation of autobody panels." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326923.
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Loxley, Neil. "X-ray topography of semiconductor silicon." Thesis, Durham University, 1988. http://etheses.dur.ac.uk/6647/.
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This thesis describes the examination and characterisation of semiconductor silicon by the various methods of X-Ray Diffraction Topography. A brief introduction is given to the dynamical theory of X-ray diffraction and its relevance to the formation of contrast in X-ray topographs. The experimental methods used and contrast formation mechanisms are introduced. The design and construction of an inexpensive Automated Bragg Angle Controller (ABAC) is described, based around a microcomputer and using many of the existing features of the Lang camera. This enables Lang topographs of the whole of distorted crystals to be taken. Using the ABAC, the contrast of defects in Lang topographs of cylindrically bent silicon wafers is explored. A comparison is made between this data and images in Hirst topographs and contrast differences between the techniques are attributed to the presence of an inhomogeneous bending moment. The change in contrast in section and Lang topographs upon homogeneous bending for asymmetric reflections is also investigated and mechanisms for the contrast changes are suggested. A bipolar device wafer is examined with double crystal topography using synchrotron radiation and a highly asymmetric reflection with a glancing angle of incidence. By exploiting the wavelength tuneability of the synchrotron radiation, the depth penetration of the X-rays is varied and the optimum experimental conditions for observing both defects and devices determined. Using this technique it is possible to image both devices and process related defects to a high resolution and contrast. The Lang, section and glancing angle double crystal topography techniques are compared for the examination of a CMOS device wafer. The relative strengths and weaknesses of each technique are highlighted and many defects are imaged and characterised. Finally, results showing the appearance of fringes in the double crystal topographs for low angles of incidence are presented. These are attributed to the' presence of along range strain, and the dependence of the fringes upon curvature is explored for moderate bending conditions (R ~35m).
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Cunha, Darryl Anthony de. "Measurement of corneal topography and transparency." Thesis, City University London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282074.
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Senin, Nicola. "Feature-based characterisation of surface topography." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/54266/.
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In recent years surface metrology has undergone a revolution: non-contact technologies have driven the transition from profile to areal measurement, and topography in- formation can now be obtained in the form of three-dimensional geometric models. However, the conceptual approach underlying topography characterisation has not changed as much, and surfaces are still predominantly quantified in terms of "rough- ness". This thesis explores feature-based characterisation, an approach that merges technologies from computer vision, image processing, geometric modelling, and statistical modelling, to forge a new set of tools for the analysis of three-dimensional surface topography. Feature-based characterisation provides the end-user with the capability of identifying, isolating and characterising any topographic formation of interest which may be found on a measured surface, addressing characterisation needs that may go well beyond the mere assessment of surface roughness. Feature-based characterisation of surface topography offers new ways to approach cur- rently challenging metrology problems, and offers new opportunities to explore original pathways in the development of advanced manufacturing processes, materials and products. This thesis illustrates original methods developed by the candidate for feature-based characterisation, and presents a first attempt at unifying such methods into a comprehensive framework where feature-based characterisation is seen as an alternative to conventional characterisation based on quantifying roughness. Throughout the thesis, the foundational elements of feature-based characterisation framework will be illustrated and discussed with the help of examples from real-life applications.
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Straub, Kyle M. "Quantifying turbidity current interactions with topography." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40864.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 196-205).
This thesis advances our understanding of how transport properties of turbidity currents are mediated by interactions with seafloor topography, specifically channelized surfaces. Turbidity currents are responsible for crafting the morphology of continental margins. Unfortunately, very few direct observations exists defining turbidity current interactions with submarine channels and canyons because infrequent occurrence, great water depths, and high current velocities make measurements difficult to obtain. To overcome this problem, I utilize reduced scale laboratory experiments, remote sensing of the seafloor and subsurface deposits, and numerical analysis of transport processes. I focus on resolving the topography and composition of the evolving water-sediment interface with additional measurements that characterize the sediment transport and flow fields. I begin by quantifying interactions between turbidity currents and channel-bounding levees. Levees are the primary elements of self-formed channels and act to confine flows within channels, thereby increasing transport efficiency. I quantify the morphology and growth of levees in a submarine channel network offshore Borneo. Levee deposit trends are interpreted using laboratory observations and a morphodynamic model describing levee growth. Channel and levee deposits resulting from interactions between turbidity currents and sinuous submarine channels are then studied using reduced-scale laboratory experiments. Measurements of current superelevation in channel bends are used to illustrate the importance of current runup onto the outer banks of channel bends. This runup resulted in focused overbank flow and production of thick, coarse, steep levees at these sites.
(cont.) Additional laboratory experiments illustrate the importance of current-channel bend interactions to the runout length of turbidity currents. I observed enhanced mixing in channel bends that reduced proximal deposition rates in sinuous channels compared to straight channels. I hypothesize that a wholesale vertical mixing of suspended sediment within turbidity currents at channel bends is a necessary condition for the construction of submarine channels greater than 100 km in length. Finally, I document the deepening of submarine canyons under net depositional conditions using an industry-grade seismic volume from the continental slope offshore Borneo. Interpretation of seismic horizons suggests deposition resulted from sheet-like turbidity currents, highlighting the importance of unconfined currents to the evolution of seascapes.
by Kyle M. Straub.
Ph.D.
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BELL, BERNARD WHITE JR. "DIGITAL HETERODYNE TOPOGRAPHY (MOIRE, CONTOURING, PROFILOMETRY)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187971.
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Digital heterodyne methods are employed in conjunction with periodic fringe projection to produce a fast automated surface relief measurement technique. A method of sampling the image with a solid state detector array which produces a moire fringe image free of the noise terms normally present with moire techniques is presented along with an extension to Whittaker-Shannon sampling theory to cover the moire aliasing phenomena. The limitations imposed on the surface slopes by the requirement that the properly moire sampled image spectra must be confined to a moire interval are given. Moire sampling allows an optical processing step (removal of the reference surface tilt), while classical nonaliased sampling produces the same information with respect to a tilted surface. General additive noise is analyzed as regards both integrating bucket and phase stepping algorithms and yields a signal to noise ratio dependent error with twice the frequency of the fringes for some algorithms. A phase averaging technique which eliminates these oscillatory errors as well as those caused by reference phase shift errors in all the algorithms is demonstrated. Both parallel and divergent geometries are discussed. The feasibility is experimentally demonstrated with results for the parallel case based on a system composed of commercially obtainable components.
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Sotoudeh, Neda. "Modelling surface topography from reflected light." Thesis, Middlesex University, 1997. http://eprints.mdx.ac.uk/6565/.
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This thesis is concerned with the use of the modulus of the Fourier spectrum to characterise object features and also to reconstruct object surfaces in the complete absence of phase information. In general, a phaseless synthesis is completely meaningless and many characteristic features of the object are obliterated when the modulus of the spectral components is inverse Fourier transformed with zero phase. However, the outcome is different when the object possesses some form of regularity and repetition in its characteristics. In such circumstances, the utilisation of both the modulus and the intensity of the spatial spectrum can reveal information regarding the characteristic features of the object surface. The first part of this research has utilised the intensity of the spectral components as a means of surface feature characterisation in the study of a machined surface. Two separate approaches were adopted for assessing the zero-phase images. Both the optically recorded Fourier spectrum and the computer simulated Fourier spectrum were used to extract surface related parameters in the zero-phase synthesis. Although merely a characterisation, the zero-phase synthesis of the spectral components revealed periodic behaviour very similar to that present in the original surface. The presence of such cyclic components was confirmed by their presence in travelling microscope images and in scanning electron microscope images of the surface. Additionally, a novel approach has been adopted to recover finer periodicities on the surface. The scale sensitivity of the frequency domain fosters an exceptional means through which digital magnification can be performed with the added advantage that it is accompanied by enhanced resolution. Magnification realised through spatial frequency data is by far superior to any spatial domain magnification. However, there are limitations to this approach. The second part of this research has been centred around the possible use of a non-iteratively based approach for extracting the unknown phases from the modulus of the Fourier spectrum and thus retrieving the 3-D geometrical structure of the unknown object surface as opposed to characterising its profile. The logarithmic Hilbert transform is one such approach which allows a non-iterative means of extracting unknown phases from the modulus of the Fourier spectrum. However, the technique is only successful for object surfaces which are well-behaved and display well-behaved spectral characteristics governed by continuity. For real object surfaces where structure, definition and repetition governs the characteristics, the spectrum is not well behaved. The spectrum is populated by maxi ma, minima and many isolated regions which are occupied by colonies of zeros disrupting the continuity. A new and unique approach has been devised by the author to reform the spectral behaviour of real object surfaces without affecting the fidelity that it conveys. The resultant information enables phase extraction to be achieved through the logarithmic Hilbert transform. It is possible to reform the spread of spectral behaviour to cultivate better continuity amongst its spectral components through an object scale change. The combination of the logarithmic Hilbert transform and the Fourier scaling principle has led to a new approach for extracting the unknown phases for real object structures which would otherwise have been impossible to perform through the use of Hilbert transformation alone. The validity of the technique has been demonstrated in a series of simulations conducted on one-dimensional objects as well as the two-dimensional object specimens. The limitations of the approach, improvements and the feasibility for practical implementation are ail issues which have been addressed.
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Maude, Ulrika. "Beckett's landscapes : topography, body and subject." Thesis, University of York, 2001. http://etheses.whiterose.ac.uk/9755/.
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Loven, Bjoern. "The zea shipsheds - topography and architecture." Thesis, Royal Holloway, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529037.
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Rosa, André Luís Beling da. "An accessible approach for corneal topography." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/95987.
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Topografias da córnea consistem em medir a forma da córnea, que é um fator chave para a acuidade visual. O exame é usado, por exemplo, na detecção de ceratocone, ajuste personalizado de lentes de contato, e pre e pós procedimentos associados com cirurgias refrativas e transplante de córnea. Esta dissertação apresenta, uma abordagem acessível e portátil para realizar topografias da córnea. Os resultados obtidos com o nosso protótipo mostram uma diferença média por volta de 0.02 milimetros, equivalente a 0.5% do raio médio da córnea, quando comparadas com topografias adquiridas com um topografo comercial. Nossa abordagem é baseada no disco de Plácido, a um conjunto de círculos concêntricos que são colocados na frente do olho do paciente e refletidos na córnea. Observando a deformação do padrão projetado, podemos identificar algumas condições refrativas (e.g. astigmatismo, ceratocone) e estimar a topografia da córnea do paciente. Nós construimos um dispositivo para ser utilizado com um celular para emitir os padrões, estes são então capturados pela câmera do celular. Nós usamos um sequência de procedimentos para melhor as imagens, segmentar os padrões, associar o padrão capturado com o emitido para amostrar o sinal, e finalmente estimar a superfície da córnea. A forma estimada é então decomposta, usando-se os polinômios de Zernike, em componentes com significado ótico específico. Nós avaliamos os resultados obtidos com o nosso protótipo de três maneiras: inspeção visual de ceratoscopias, detecção de ceratocone, e comparação com os resultados produzidos por um topográfo de córnea comercial. De acordo com essa análise, nosso dispositivo pode ser utilizado para o exame de indivíduos com ceratocone, e obter topografias com 0.02 milimetros de diferença em relação aos resultados obtidos com um topógrafo comercial.Corneal topography consists of measuring the corneal shape, which is a key factor for visual acuity. The exam is used, for instance, in keratoconus detection, personalized contact lens fitting, in pre- and post-procedures associated with refractive surgery and corneal transplants. This thesis presents an accessible, inexpensive and portable approach to perform corneal topographies. The results obtained with our prototype show a mean difference of about 0.02 millimeters, equivalent to 0.5% of the mean corneal radius, when compared to topographies acquired with a commercial device. Our approach is based on Placido’s disks, a set of concentric disks that are placed in front of the patient’s eye and reflected on the cornea. Observing the deformation of the projected pattern, one can identify some refractive conditions (e.g., astigmatism, keratoconus) and estimate the patient’s corneal topography. We have built a clip-on device to be used with a cell phone to emit the patterns, which are then captured by the cell phone camera. We use a software pipeline to enhance the images, segment the patterns, associate the emitted pattern with the captured one to sample the signal, and finally estimate the corneal surface. The estimated shape is then decomposed using Zernike polynomials in components with specific optical meanings. We have evaluated the results obtained with our prototype in three ways: visual inspection of keratoscopies, keratoconus detection, and comparison with the results produced by a commercial corneal topographer. According to such analysis, our device can be used for screening of individuals with keratoconus, and to obtain corneal topographies with 0.02-millimeter differences with respect to the results obtained with a commercial corneal topographer.
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Yang, Junjun. "Seafloor Topography Estimation from Gravity Gradients." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512048462472145.
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Johnston, Thomas Michael Shaun. "Internal tide scattering at midocean topography." Thesis, University of Hawaii at Manoa, 2003. http://proquest.umi.com/pqdweb?index=0&did=765959661&SrchMode=2&sid=6&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209407173&clientId=23440.
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Micali, Jason Daniel. "Interferometer for Measuring Dynamic Corneal Topography." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/581129.
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The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an ongoing research project that has spanned multiple dissertations. For this research, the instrument was tested on human subjects and resulted in refinements to the interferometer design. The final configuration of the tear film interferometer and results from human subjects testing are presented. Feedback from this instrument was used to support the development and construction of the interferometric corneal topographer system. A calibration is performed on the instrument, and then verified against simulated eye surfaces. Finally, the instrument is validated by testing on human subjects. The result is an interferometer system that can non-invasively measure the dynamic corneal topography with greater accuracy and resolution than existing technologies.
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Lewis, Nathan Dean. "Corneal Topography Measurements for Biometric Applications." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203470.
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The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.
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Lee, Phillip Alan. "Control of crystallisation using surface topography." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17568/.
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The purpose of this research project was to realise the control of crystallisation using surface topography. Calcium carbonate crystallisation was primarily used as this is a model system for crystallisation studies. The first experimental chapter involves the precipitation of calcium carbonate on a plasma-treated poly(dimethylsiloxane) (PPDMS) substrate. Exposure to atmospheric air-plasma results in oxidation of the surface of the poly(dimethylsiloxane), causing a superficial silica-like (SiOx) surface layer to form. Cracks in this surface, which arise because of its rigidity compared to the underlying bulk, were found to act as effective nucleation sites for calcium carbonate precipitation. Crystals were often observed only at the cracks and were absent elsewhere on the substrate. The surface chemistry was altered using a carboxylate terminated alkylthiol self-assembled monolayer (SAM), formed from the monomer 16-mercaptohexadecanoic acid. The presence of this monomer on the PPDMS substrate caused a significant increase in crystal population and enhanced the localising effect of the cracks. Further control of crystallisation was achieved by varying the initial ion ratio (Ca2+:CO32-) and by the presence of magnesium ions in solution. The substrate also proved effective at causing the localised precipitation of other inorganic materials: strontium carbonate, barium carbonate, manganese carbonate, basic copper carbonate and calcium oxalate. Through the application of contact masks or a tensile stress during plasma-treatment, it was possible to control the distribution of the cracks across the surface and therefore pattern the crystallisation of calcium carbonate. The second research chapter is a quantitative analysis of the system discussed in the first chapter. Here, an image analysis software, ImageJ, was used to obtain data from electron micrographs of the PPDMS substrate after crystallisation. Calcium carbonate had been precipitated on the PPDMS substrate once the surface chemistry had been modified using a variety of differently terminated alkylthiol SAMs. The research revealed that not only is it possible to control crystal populations at the surface features, but also the crystal polymorph. In the third research chapter, silicon wafers that had been spincoated with reduced-graphene oxide were used as substrates for calcium carbonate precipitation. Interestingly, the vast majority of crystals that had formed on these wafers were aragonite, a metastable phase of calcium carbonate. In order to understand why this was so, a series of investigations followed that were aimed at elucidating if it was a topographical effect or due to the presence of impurities. The data suggested that the large proportion of aragonite was due to topographical effects. The final research chapter involved cleanroom microfabrication techniques common to the semiconductor industry to construct surface structures on silicon wafers that were used as substrates. Crystallisation was locallised to these features, proving that it is possible to design surface topographies that can be used to control crystallisation.
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Antonacci, Gianluca. "Air pollution modelling over complex topography." Doctoral thesis, University of Trento, 2004. http://eprints-phd.biblio.unitn.it/612/1/Gianluca_Antonacci-2004.pdf.
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The present study deals with air pollution modelling over complex topography, both from the phenomenological and numerical point of view.
The theme of air pollution modelling has been faced at first from a phenomenological point of view. Then a numerical approach for the resolution of the diffusion-advection equation has been followed. Two different methods have been explored: puff-models and lagrangian particle models.
The eulero-lagrangian puff-model CALPUFF (released by Earth Tech) has been used as a reference: closures and parametrizations adopted by this software have been tested over complex terrain and some minor changes have been introduced into the original code.
A further step was the development of a lagrangian particle-tracking program, suitable for not homogenous not stationary flows, and also adapted to complex terrain cases, accounting for vertical skewed turrbulence in any atmospheric stability class. Langevin equation were solved following Thomson's (1987) approach. Special attention was put on near field dispersion processes. In fact, lagrangian models turn out to be the most advanced numerical schemes for pollutant transport simulations but at now only suitable for short term simulations, at least in complex errain where high spatial resolution is needed.
An extension for the lagrangian model has been then developed, using the so called "kernel method"; this feature improves considerably the calculation performance, dramatically reducing computation time, so that simulations also become praticable for longer temporal scales; nevertheless it seems the kernel method seems to lead to unreliable results for narrow valleys or very steep slopes, so results cannot be generalized.
Moreover, the problem of the determination of vertical profiles of turbulent diffusivity on complex orography has been faced. Both a local approach and a global one (suitable for compact valleys) for the estimate of eddy diffusivity in valley have been investigated. The first one has been adopted in the lagrangian problem previously developed. Since atmospheric turbulence is mostly generated by solar thermal flux, a procedure for the calculation of the effective solar radiation was developed. The method, which can be introduced into meteorological models which use complex orography as input, takes into account for shadowed areas, soil coverage and the possible precense of clouds which filter and reduce the incoming solar radiation. Tests have been carried out using a modified version of model CALMET (EarthTech Inc.).
Results are in agreement with turbulence data acquired by means of a sonic anemometer during a field campain performed by the Department.
Finally, the analysis of near field dispersion over complex terrain has been extended to the urban context, adopting, basically, the same conceptual tools on a smaller scale. A finite volume three-dimensional numerical model has been developed and tested in simulating dispersion of traffic derived pollutants in the town of Trento. For ground level sources geometry of the domain and emission condition turn out to be very important with respect to meteorological conditions (especially atmospheric stability). The roughness, i.e. the buildings of the study area has been therefore explicitely considered, using a high resolution deigital elevation map of the urban area. This approach has turned out to be necessary for near field dispersion, when the emission source is located inside the roughness and the impact area entirely fall inside the near field.
Here a comparison has been made between the predicted numerical solution and data measured by air quality stations which are present in the urban area, showing a good agreement.
A further refinement of the study has lead to the development of a two-dimensional x-z lagrangian model at the "street scale", for the study of canyon effects which tends to trap pollutant inside an urban canyon with behaviours which typically depends on geometric features, atmospheric turbulence and wind speed.
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Raja, Keshav Jayakrishnan. "Internal waves and mean flow in the presence of topography." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU006/document.
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Les ondes internes jouent un rôle important dans de nombreux processus dans les océans.L’interaction entre les vagues internes et la topographie océanique a longtemps été un champ de recherche actif. Pourtant, il reste beaucoup de questions sur le sujet. Dans cette thèse, deux processus principaux sont examinés, à savoir la réflexion de faisceaux d’ondes internes sur une pente, et la génération d’ondes sous le vent sur un obstacle tridimensionnel, en utilisant des expériences de laboratoire et des simulations numériques.La réflexion non linéaire d’un faisceau d’onde interne sur une pente uniforme est étudiée à l’aide de la théorie des invisques bidimensionnels et de simulations numériques. Les interactions triadiques résonnantes entre les faisceaux d’ondes incidentes, réfléchies et de deuxième harmonique sont étudiées en développant la théorie existante et en les vérifiant avec des résultats pour des simulations numériques.Dans le cas de la réflexion de faisceaux d’ondes internes tridimensionnels, un fort flux horizontal moyen est induit par le faisceau d’onde, qui perturbe le champ d’onde et affaiblit les secondes harmoniques. La génération de ce flux moyen induit par les vagues est examinée à l’aide des résultats d’expériences et de simulations numériques tridimensionnelles. De plus,les effets de la rotation de fond sur le débit moyen induit par les vagues sont également étudiés à l’aide de simulations numériques.Le courant circumpolaire antarctique est considéré comme l’une des principales sources de mélange dans les océans. La modélisation en laboratoire du courant circumpolaire antarctique a été réalisée sur la plate-forme de Coriolis à LEGI pour étudier la traînée induite par la topographie sur le courant. L’expérience et ses résultats sont également présentésInternal waves play an important role in many processes in oceans. The interaction be-tween internal waves and ocean topography has been an active field of research for long. Yetthere are many questions remaining on the topic. In this thesis, two main processes are ex-amined namely, the reflection of internal wave beams on a slope, and generation of lee wavesover a three-dimensional obstacle, using laboratory experiments and numerical simulations.The nonlinear reflection of an internal wave beam on a uniform slope is studied using two-dimensional inviscid theory and numerical simulations. The resonant triadic interactionsamong the incident, reflected and second harmonic wave beams are investigated developingon existing theory and verifying them with results for numerical simulations.In the case of reflection of three-dimensional internal wave beams, a strong mean horizon-tal flow is found to be induced by the wave beam, which perturbs the wave field and weakensthe second harmonics. The generation of this wave-induced mean flow is examined usingresults from experiments and three-dimensional numerical simulations. Furthermore, theeffects of background rotation on the wave induced mean flow are also studied using numer-ical simulations.The Antarctic Circumpolar Current is considered as one of the main sources of mixing inoceans. Laboratory modelling of the Antarctic Circumpolar Current was done in the Coriolisplatform at LEGI to study the topography induced drag on the current. The experiment andits results are also presented
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Wichura, Henry. "Topographic evolution of the East African Plateau : a combined study on lava-flow modeling and paleo-topography." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5236/.
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The East African Plateau provides a spectacular example of geodynamic plateau uplift, active continental rifting, and associated climatic forcing. It is an integral part of the East African Rift System and has an average elevation of approximately 1,000 m. Its location coincides with a negative Bouguer gravity anomaly with a semi-circular shape, closely related to a mantle plume, which influences the Cenozoic crustal development since its impingement in Eocene-Oligocene time.
The uplift of the East African Plateau, preceding volcanism, and rifting formed an important orographic barrier and tectonically controlled environment, which is profoundly influenced by climate driven processes. Its location within the equatorial realm supports recently proposed hypotheses, that topographic changes in this region must be considered as the dominant forcing factor influencing atmospheric circulation patterns and rainfall distribution. The uplift of this region has therefore often been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While the far-reaching influence of the plateau uplift is widely accepted, the timing and the magnitude of the uplift are ambiguous and are still subject to ongoing discussion. This dilemma stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift.
In order to quantify the amount of plateau uplift and to find evidence for the existence of significant relief along the East African Plateau prior to rifting, I analyzed and modeled one of the longest terrestrial lava flows; the 300-km-long Yatta phonolite flow in Kenya. This lava flow is 13.5 Ma old and originated in the region that now corresponds to the eastern rift shoulders. The phonolitic flow utilized an old riverbed that once drained the eastern flank of the plateau. Due to differential erosion this lava flow now forms a positive relief above the parallel-flowing Athi River, which is mimicking the course of the paleo-river.
My approach is a lava-flow modeling, based on an improved composition and temperature dependent method to parameterize the flow of an arbitrary lava in a rectangular-shaped channel. The essential growth pattern is described by a one-dimensional model, in which Newtonian rheological flow advance is governed by the development of viscosity and/or velocity in the internal parts of the lava-flow front. Comparing assessments of different magma compositions reveal that length-dominated, channelized lava flows are characterized by high effusion rates, rapid emplacement under approximately isothermal conditions, and laminar flow. By integrating the Yatta lava flow dimensions and the covered paleo-topography (slope angle) into the model, I was able to determine the pre-rift topography of the East African Plateau.
The modeling results yield a pre-rift slope of at least 0.2°, suggesting that the lava flow must have originated at a minimum elevation of 1,400 m. Hence, high topography in the region of the present-day Kenya Rift must have existed by at least 13.5 Ma. This inferred mid-Miocene uplift coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa.
Accordingly, the combination of my results regarding the Yatta lava flow emplacement history, its location, and its morphologic character, validates it as a suitable “paleo-tiltmeter” and has thus to be considered as an important topographic and volcanic feature for the topographic evolution in East Africa.Das Ostafrikanische Plateau ist ein eindrucksvolles Beispiel für aktive, kontinentale Grabenbildung, aber auch für geodynamische Hochebenenbildung mit weitreichendem klimatischen Einfluss auf die gesamte Region. Als integraler Bestandteil des Ostafrikanischen Grabensystems beläuft sich die mittlere Höhe des Plateaus auf durchschnittlich 1000 m ü.NN. Seine Lage korreliert gut mit der Präsenz einer halbkreisförmigen negativen Bouguer-Schwereanomalie, die an den Aufstieg eines Manteldiapirs im Untergrund gekoppelt ist. Dieser prägte die känozoische Krustenentwicklung seit seinem Aufstieg im Eozän-Oligozän. Die Hebungsgeschichte und topographische Entwicklung des Hochlandes steht seither in enger Beziehung zum einsetzenden Vulkanismus, der Bildung erster Abschiebungssysteme und führte schließlich zur Entwicklung des heutigen Vollgrabensystems. Neueste Hypothesen lassen den Schluss zu, dass topographische Veränderungen als dominierende Einflussgrößen atmosphärischer Zirkulationsmuster sowie der regionalen Niederschlagsverbreitung anzusehen sind. Zusätzlich werden diese Prozesse durch die äquatoriale Lage des Ostafrikanischen Plateaus verstärkt und die Hebung dieser Region oft mit wichtigen Klima- und Umweltveränderungen in Ostafrika und angrenzende Gebiete in Verbindung gebracht. Während der weitreichende klimatische Einfluss des Hochlandes größtenteils akzeptiert ist, sind Zeitpunkt und Ausmaß seiner Heraushebung nicht eindeutig bestimmt und daher noch immer Grundlage bestehender Diskussionen. Diese Zwangslage hat ihre Ursache im Fehlen aussagekräftiger und datierbarer Referenzhorizonte. Um den Hebungsbetrag zu quantifizieren und Beweise signifikanten Reliefs vor der Entwicklung des Grabensystems entlang des Ostafrikanischen Hochlandes zu erbringen, analysierte und modellierte ich einen der längsten terrestrischen Lavaströme. Dieser vor 13,5 Ma abgelagerte Yatta-Lavastrom hat mit 300 km Länge seinen Ursprung in der Region der heutigen östlichen Grabenschulter des zentralen Kenia-Rifts. Die phonolitische Lava ergoss sich entlang eines Flussbettes, das einst die östliche Flanke des Hochlandes entwässerte. Aufgrund unterschiedlicher Erosionspotentiale bildet der Lavastrom gegenwärtig ein positives Relief und befindet sich oberhalb des Athi Flusses, der parallel zum Paläofluß, und somit versetzt zu seinen früheren Verlauf, strömt. Mein Ansatz der Lavastrom-Modellierung basiert auf einer Methode, die das Fließverhalten einer beliebigen Lava in Abhängigkeit von Temperatur und Magmenzusammensetzung in einem rechtwinkligen Kanal berechnet. Die wesentlichen Wachstumsmuster des Lavastroms sind durch ein eindimensionales Modell beschrieben, wobei Newtonsches Fließverhalten im Innern hinter der Lavastromfront von der zeitlichen Entwicklung der Viskosität und/oder der Fließgeschwindigkeit bestimmt wird. Vergleiche meiner Resultate mit verschiedenen Magmenzusammensetzungen zeigen, dass sich lange, kanalisierte Lavaströme mit hohen Ergussraten und schneller Platznahme bilden können. Dies geschieht unter annähernd isothermalen Bedingungen und erfordert laminares Fließen. Die Integration der Yatta- Lavastrom-Dimensionen und der bedeckten Paläotopographie (Neigungswinkel) in das Modell, erlaubte es mir die Topographie des Ostafrikanischen Hochlandes vor der Grabenbildung zu modellieren. Das Ergebnis der Modellierung ergibt einen Neigungswinkel von mindestens 0,2° und impliziert, dass der Lavastrom seinen Ursprung in einer Höhe von mindestens 1400 m ü.NN gehabt haben muss. Somit existierte bereits vor 13,5 Ma hohe Topographie in der heutigen Region des zentralen Kenia-Rifts. Diese abgeleitete regionale Hebungsgeschichte im mittleren Miozän korreliert mit der zweistufigen Ausbreitung der Graslandschaften, sowie dem Aufkommen neuer Arten im tropischen Afrika. Die Kombination aus Fließverhalten, Entstehungsort und morphologischer Eigenschaften macht den Yatta-Lavastrom zu einem “Paläoneigungsmesser” und wichtigen vulkanischen Untersuchungsobjekt für die topographische Entwicklung in Ostafrika.
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Mahieu, Vincent. "Temps, espace et identités : recherches sur les coexistences religieuses dans la Rome tardo-antique (312-410)." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEP029.
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Le IVe siècle de notre ère représente indéniablement un tournant majeur dans l’histoire de l’Europe occidentale. Le passage du christianisme du statut de culture marginale d’une communauté religieuse à celui de pôle culturel et normatif à l’échelle d’une société constitue une transition caractéristique de l’Antiquité tardive, qui s’est d’abord opérée sur le terrain des systèmes sociaux de référence que sont le temps et l’espace – lieux d’expression identitaire. La richesse documentaire de l’"Vrbs" ajoutée à sa position de capitale historique et de cité de première importance pour le christianisme en font un cadre d’étude singulier. Cette enquête sur le partage du temps et de l’espace, entre la victoire du Pont Milvius (312) et le sac d’Alaric (410), propose une reconstruction des temps de la cité et une exploration des mécanismes de développement de l’organisation calendaire de l’Église et d’insertion au sein de la trame temporelle urbaine (partie 1). Sur la base d’un catalogue qui actualise le "LTVR(S)", elle reconstitue la topographie polythéiste et examine l’inscription de l’ancrage matériel du culte chrétien au sein du territoire romain (partie 2). Au travers de ces analyses transversales et d’études de cas (partie 3), elle tente aussi de comprendre des modes d’interaction, de coexistence religieuse au sein d’une société. La recherche replace le curseur sur la continuité plutôt que la rupture. Elle révèle un modèle prioritairement intégratif et une stratégie de conformité aux dynamiques romaines dans le partage du temps et de l’espace. Elle argumente sur une cohabitation religieuse globalement pacifique portée par un investissement identitaire commun focalisé sur la "Romanitas"The fourth century AD is admittedly a major turning point in the history of Western Europe. The evolution of Christianity from the status of a marginal culture within a religious group to that of a cultural and normative pole within society constitutes an important transition specific to Late Antiquity. This transition from margin to norm started from the social frameworks of time and space, acting as strong identity markers. The great amount of evidence from the "Vrbs", its position as historical capital, as its recognized status as important city for the development of Christianity, make it a specific research framework. This study, which focuses on the sharing of time and space between the victory of the Milvius Bridge (312) and the sack of Alaric (410), reconstructs the organization of the times in the city and explores the mechanisms behind the development of the calendar structure of the Church within this urban space (part 1). On the basis of a catalogue that brings up to date the "LTVR(S)", this study rebuilds the polytheistic topography and scrutinizes the material inscription of the Christian cult on the Roman territory (part 2). On the basis of these cross-sectional analyses and case studies (part 3), it also attempts at understanding the modes of religious co-existence and interaction within a society. The results point towards a sense of continuity rather than breaking. This dissertation reveals a model that favours integration and conformation strategies to the Roman dynamics in the sharing of time and space. It argues in favour of a religious cohabitation mostly peaceful led by a common identity investment focused on the "Romanitas"
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Buchanan, Timothy John. "Computer aided analysis of human iris topography and its relationship to systemic disease." Thesis, University of Central Lancashire, 1993. http://clok.uclan.ac.uk/21060/.
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The research was conducted to investigate the claims made by certain alternative medicine practitioners, namely iridologists, that the majority of systemic diseases are accompanied by changes in the colour and/or structure of discrete regions of the anterior surface of the iris. Colour photographic slides of the left and right irides of between 22 and 30 patients' clinically diagnosed as suffering from one of 5 named disease states; asthma (30 patients), coronary heart disease (25), diabetes mellitus (22), psoriasis (30) and ulcerative colitis (30), were analysed and subsequently compared with slides obtained from an equal number of control subjects. Computer software, designed to map the position of defined iridic features types, relative to a standard reference point, was executed for each of the iris images digitised onto an image processing system. The resulting data, expressed as 360 x 100-bit binary words, for the left and right irides of patients representing each of the five experimental groups was compared with that for the corresponding control group by means of four differing methodologies. Comparison of the data based on the discrete regions of the iris which, for each of the five diseases under study, should, according to practitioners of iridology undergo changes as a result of the onset of the disease, failed to demonstrate significant differences between each of the experimental and associated control groups. Further, comparison of the data based on regions of the iris, for which either the size or position varied from that specified by iridology practitioners, also failed to demonstrate any significant differences between experimental and control groups. A detailed visual comparison of iris images obtained from patients with those from control subjects, on the basis of lesions within the regions of the iris designated by iridology practitioners as being of primary importance, did not illustrate any significant differences. This study demonstrated that iridology is not a useful tool for the diagnosis of asthma, coronary heart disease, diabetes mellitus, psoriasis or ulcerative colitis.
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Coelho, Emanuel Ferreira. "Tidal dynamics and mixing over steep topography." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283535.
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Lerede, Niclas. "Topography based fan control for heavy trucks." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17101.
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This thesis is a study of how cooling fan control can be improved by using road topography information. Two such controllers are presented, one that uses information available in vehicles produced today, and one that combines GPS-information with digital topographic maps to use information about the road ahead of the vehicle.
Simulations show that significant energy savings can be obtained, especially during warm conditions and hilly roads. Compared to conventional fan controllers, energy consumption can be cut by up to three quarters. Moreover, this is possible without any hardware redesign.
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Zettler, Tamara Elizabeth. "Operational induced changes in Geomembrane surface topography." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20295.
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Gagnon, Jean Sebastien. "Multiscaling and multifractality in the earth's topography." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33761.
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Topographic transects corning from four different Digital Elevation Models (DEMs) which collectively span different ranges of scales from 20000 km to 0.5 m are analyzed. Power spectra, trace moments and structure functions are used to show that continents and oceans have the same moment scaling function K(q) but different (scale by scale) nonconservation H and also that the Earth's topography is multiscaling from planetary scales down to a few meters. The results also suggest that topography can be described statistically at all scales by a global K(q). The form of K(q) shows that the statistics of topography are close to those predicted by universal multifractals. It seems that the multiscaling of topography is broken because of the presence of trees on the DEM: they introduce a characteristic length in the vertical that is approximately 9 m.
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Burrows, Justin. "Vector modelling three-dimensional engineering surface topography." Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286805.
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O'Rourke, Eleanor Anne. "The effect of topography on thermohaline adjustment." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511044.
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Lawrence, Daniel William. "On the digital-political topography of music." Thesis, Michigan Technological University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3643826.
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The persuasive power of music is often relegated to the dimension of pathos: that which moves us emotionally. Yet, the music commodity is now situated in and around the liminal spaces of digitality. To think about how music functions, how it argues across media, and how it moves us, we must examine its material and immaterial realities as they present themselves to us and as we so create them. This dissertation rethinks the relationship between rhetoric and music by examining the creation, performance, and distribution of music in its material and immaterial forms to demonstrate its persuasive power. While both Plato and Aristotle understood music as a means to move men toward virtue, Aristotle tells us in his Laws, through the Athenian Stranger, that the very best kinds of music can help guide us to truth. From this starting point, I assess the historical problem of understanding the rhetorical potential of music as merely that which directs or imitates the emotions: that which "Soothes the savage breast," as William Congreve writes. By furthering work by Vickers and Farnsworth, who suggest that the Baroque fascination with applying rhetorical figures to musical figures is an insufficient framework for assessing the rhetorical potential of music, I demonstrate the gravity of musical persuasion in its political weight, in its violence--the subjective violence of musical torture at Guantanamo and the objective, ideological violence of music--and in what Jacques Attali calls the prophetic nature of music. I argue that music has a significant function, and as a non-discursive form of argumentation, works on us beyond affect. Moreover, with the emergence of digital music distribution and domestic digital recording technologies, the digital music commodity in its material and immaterial forms allows for ruptures in the former methods of musical composition, production, and distribution and in the political potential of music which Jacques Attali describes as being able to foresee new political realities. I thus suggest a new theoretical framework for thinking about rhetoric and music by expanding on Lloyd Bitzer's rhetorical situation, by offering the idea of "openings" to the existing exigence, audience, and constraints. The prophetic and rhetorical power of music in the aleatoric moment can help provide openings from which new exigencies can be conceived. We must, therefore, reconsider the role of rhetorical-musical composition for the citizen, not merely as a tool for entertainment or emotional persuasion, but as an arena for engaging with the political.
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Coffey, Paul Anthony. "The influence of topography upon rotating magnetoconvection." Thesis, University of Newcastle Upon Tyne, 1996. http://hdl.handle.net/10443/1572.
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Aspects of thermal convection in the Earth's fluid core in the presence of a strong azimuthal magnetic field may be understood by considering a horizontal plane layer, rotating about the vertical z axis, with gravity acting downwards and containing an applied magnetic field aligned in the y (azimuthal) direction. Since the OMB is not smooth, the effects of adding bumps (with axes perpendicular to the applied magnetic field) to the top boundary of the layer are investigated in the magnetogeostrophic limit. The arbitrary geostrophic flow that arises under this limit is evaluated using a modified Taylor constraint. The bumps distort the isotherms so that they are not aligned with equipotential surfaces, leading to an imperfect configuration. This means that a hydrostatic balance is not possible, and motion ensues. This motion takes the form of a steady transverse convection roll, with axis parallel to the bumps. The roll exists for all values of the Rayleigh number, except that value for which the corresponding homogeneous problem in the standard plane layer has a solution. The roll obeys Taylor's constraint, and has no associated geostrophic flow. The stability of this roll to perturbation by oblique rolls (which are preferred for 0(1) values of the Elsasser number) is considered. It is found that the most unstable linear mode consists of a pair of these oblique rolls, aligned so that no geostrophic flow is accelerated by their interaction with the basic state. Hence, the stability results obtained here are identical to those found by perturbing the hydrostatic conduction solution with oblique rolls in the standard layer. Finally, the nonlinear evolution through the Ekman regime of these linear instabilities is considered. It is found that the nonlinear convection behaves similarly to mean field dynamo models which incorporate a geostrophic nonlinearity. Various types of Ekman solution are found, and evolution to Taylor states is observed.
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Hughes, Christopher William. "The effect of topography on ocean flow." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:37b3f6b2-ce5f-45b3-b2ed-3325518b06bb.
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The rôle which topography plays in constraining ocean flow is investigated in several ways, mostly aimed at application to the Southern Ocean where topography is known to be important. The physics of topographic Rossby waves is discussed in some depth and a description of ocean flow in terms of a sum of topographic normal modes is developed. It is shown that the apparent incompleteness of topographic modes can often be circumvented by including a function which absorbs the nett input of potential vorticity. Some subtle problems with this description are dealt with, and a calculation of topographic modes for the Southern Ocean is presented, which shows that the modes are very localised, making the use of them to describe basin-wide flows difficult. The effect of interactions between stratification and topography is investigated in terms of a quasi-two-dimensional model which deals only with the depth-integrated flow, and the assumptions which go into the model are examined in detail both analytically and by calculating terms of interest from a data set produced by the Fine Resolution Antarctic Model. It is shown that advection of density in the Southern Ocean can be described to a first approximation as being due to a barotropic current with no vertical velocity, the horizontal component of the baroclinic flow producing very little effect. The balance of terms reveals interesting features in the modelled flow in the Southern Ocean, showing the value of this type of analysis. Finally, insight developed in the course of the investigation allows a simple model to be constructed representing the feedback between density advection and forcing due to density gradients. This model is used to provide an explanation for the fact that the FRAM model spins up linearly, where most simple models would predict a component of quadratic behaviour in the spin-up.
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Hartley, Robert. "Cell sensing of micro and nano topography." Thesis, University of Glasgow, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248248.
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Hoogenboom, Trudi. "Gravity and topography signatures of Venusian coronae." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400956.
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Staziker, David J. "Water wave scattering by undulating bed topography." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260670.
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Holmes, Damian J. "Gravity waves in uniform windflow over topography." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336449.
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