Dissertations / Theses on the topic 'Curved surfaces'
To see the other types of publications on this topic, follow the link: Curved surfaces.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Curved surfaces.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Schoenborn, Oliver Lars. "Phase-ordering kinetics on curved surfaces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0011/NQ35313.pdf.
Full text
2
Yu, Guoxin 1968. "Optimal development of doubly curved surfaces." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9553.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 98-100).
Surfaces of many engineering structures are commonly fabricated as doubly curved shapes to fulfill functional requirements such as hydrodynamic, aesthetic, or structural. Given a three-dimensional design surface, the first step of the fabrication process is flattening or planar development of this surface into a planar shape so that the manufacturer can not only determine the initial shape of the flat plate but also estimate the strain distribution required to form the shape. In this thesis, we develop an algorithm for optimal development of a general doubly curved surface in the sense that the strain from the surface to its planar development is minimized. A planar development corresponding to minimum stretching or shrinkage is highly desirable for the following reasons: (1) it saves material; (2) it reduces the work needed to form the planar shape to the doubly curved design surface. The development process is modeled by tensile strains isoparametric directions, or along principal curvature directions from the curved surface to its planar development. The distribution of the appropriate minimum strain field is obtained by solving a constrained nonlinear programming problem. Based on the strain distribution and the coefficients of the first fundamental form of the curved surface, another unconstrained nonlinear programming problem is solved to obtain the optimal developed planar shape. Convergence, complexity, and accuracy of the algorithm are studied. Examples show the effectiveness of this algorithm.
by Guoxin Yu.
S.M.
3
Streubel, Robert. "Imaging Spin Textures on Curved Magnetic Surfaces." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-178266.
Full textAbstract:
Gegenwärtige Bestrebungen materialwissenschaftlicher Forschung beschäftigen sich unter anderem mit der Überführung zweidimensionaler Elemente elektronischer, optischer, plasmonischer oder magnetischer Funktionalität in den dreidimensionalen (3D) Raum. Dieser Ansatz vermag mittels Krümmung und struktureller Topologie bereits vorhandene Eigenschaften abzuändern beziehungsweise neue Funktionalitäten bereitzustellen. Vor allem Vektoreigenschaften wie die Magnetisierung kondensierter Materie lassen sich aufgrund der Brechung der Inversionssymmetrie in gekrümmten Flächen stark beeinflussen. Neben der Entwicklung diverser Vorgänge zur Herstellung 3D magnetischer Gegenstände sind geeignete Untersuchungsmethoden wie beispielsweise tomografische Abbildungen der Magnetisierung von Nöten, die maßgeblich die physikalischen Eigenschaften bestimmen. Die vorliegende Dissertationsschrift befasst sich mit der Abbildung von magnetischen Domänen in 3D gekrümmten Dünnschichten beruhend auf dem Effekt des zirkularen magnetischen Röntgendichroismus (XMCD). Die in diesem Zusammenhang entwickelte magnetische Röntgentomografie (MXT) basierend auf weicher Röntgenmikroskopie stellt eine zu Elektronenholografie und Neutronentomografie komplementäre Methodik dar, welche großes Anwendungspotential in der elementspezifischen Untersuchung magnetischer gekrümmter Flächen mit örtlicher Auflösung im Nanometerbereich aufweist. Die Schwierigkeit der Interpretation von Abbildungen magnetischer Strukturen in gekrümmten Flächen rührt von der Dreidimensionalität und der Vektoreigenschaft der Magnetisierung her. Die hierzu notwendigen Kenntnisse sind anhand von zwei topologisch verschiedenen Flächen in Form hemisphärischer Kappen und hohler Zylinder erschlossen worden. Die praktische Anwendung von MXT ist abschließend anhand der Rekonstruktion magnetischer Domänen in aufgerollten Dünnschichten mit zylindrischer Form verdeutlichtOne of the foci of modern materials sciences is set on expanding conventional two-dimensional electronic, photonic, plasmonic and magnetic devices into the third dimension. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and three-dimensional (3D) shape. The degree of effect is particularly high for vector properties like the magnetization due to an emergent inversion symmetry breaking. Aside from capabilities to design and synthesize 3D magnetic architectures, proper characterization methods, such as magnetic tomographic imaging techniques, need to be developed to obtain a thorough understanding of the system’s response under external stimuli. The main objective of this thesis is to develop a visualization technique that provides nanometer spatial resolution to image the peculiarities of the magnetic domain patterns on extended 3D curved surfaces. The proposed and realized concept of magnetic soft X-ray tomography (MXT), based on the X-ray magnetic circular dichroism (XMCD) effect with soft X-ray microscopies, has the potential to become a powerful tool to investigate element specifically an entirely new class of 3D magnetic objects with virtually any shape and magnetization. Imaging curved surfaces meets the challenge of three-dimensionality and requires a profound understanding of the recorded XMCD contrast. These experiences are gained by visualizing magnetic domain patterns on two distinct 3D curved surfaces, namely magnetic cap structures and rolled-up magnetic nanomembranes with cylindrical shape. The capability of MXT is demonstrated by reconstructing the magnetic domain patterns on 3D curved surfaces resembling hollow cylindrical objects
4
Chia, Yan Wah. "Radiation from curved (conical) frequency selective surfaces." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/7200.
Full textAbstract:
The thesis deals with the analysis of a microwave Frequency Selective Surface (FSS) on a conical dielectric radome illuminated by a feed hom located at the base. Two approaches have been adopted to solve this problem. The first approach is to calculate the element currents under the assumption that the surface is locally flat. Consequently, the element current at that locality can be determined by employing Floquet modal analysis. The local incidence has been modelled from the radiation pattern of the source or the aperture fields of the feed. Three types of feed model were used to account for the field illumination on the radome. The transmitted fields from the curved surface are obtained from the sum of the radiated fields due to the equivalent magnetic and electric current sources distributed in each local unit cell of the conical surface. This method treats the interaction of neighbouring FSS elements only. In the second approach the curvature is taken into account by dividing the each element into segments which conform to the curved surface. An integral formulation is used to take into account the interaction of all the elements. The current source in each FSS element from the formulation is solved using the method of moments (MOM) technique. A linear system of simultaneous equations is obtained from the MOM and has been solved using elimination method and an iterative method which employs conjugate gradients. The performance of both methods has been compared with regard to the speed of computations and the memory storage capability. New formulations using quasi static approximations have been derived to account for thin dielectric backing in the curved aperture FSS analysis. Computer models have been developed to predict the radiation performance of the curved(conical) FSS. Experiments were performed in an anechoic chamber where the FSS cone was mounted on a jig resting on a turntable. The measuring setup contained a sweep oscillator that supplied power to a transmitting feed placed at the base of the cone. Amplitude and phase values of the far field radiation pattern of the cone were measured with the aid of a vector network analyser. Cones with different dimensions and FSS element geometries were constructed and the measured transmission losses and radiation patterns compared with predictions.
5
Wang, Qiang. "Atmospheric refraction and propagation over curved surfaces." n.p, 1997. http://ethos.bl.uk/.
Full text
6
Wang, Qiang. "Atmospheric refraction and propagation over curved surfaces." Thesis, Open University, 1998. http://oro.open.ac.uk/44453/.
Full textAbstract:
This thesis presents theoretical and experimental investigations of atmospheric refraction and diffraction of sound over curved surfaces. The main contributions of this work are as follows: The development of an alternative method for calculating the influence of wind on sound propagation in the presence of a ground of finite impedance. The development of numerical models to calculate sound propagation due to monopole and dipole sources over cylindrical or spherical convex and concave surfaces of finite impedance. Laboratory measurements of sound propagation over curved surfaces and comparisons with the proposed theoretical and numerical models. The exploration of the theory for surface wave contributions in an upward refracting atmosphere in the light of obtained experimental data and observation of the surface waves above a convex surface. Experimental and theoretical investigations of the effectiveness of a barrier in the presence of sound speed gradients.
7
Chelliah, Joel Eelaraj. "Parallel Methods for Projection on Strongly Curved Surfaces." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14979.
Full textAbstract:
Using the parallel architecture of the graphics processing unit for general purpose programming has become increasingly common in the recent years. The process of creating a mathematically correct transformation of a scene for curved stereoscopic projection is a very expensive task, which would greatly benefit from a massively parallel solution implemented on the GPU.In this thesis, we first investigate two different methods for obtaining a mathematically correct transformation of images intended for stereoscopic projection on strongly curved surfaces. One method revolves around transforming a pre-rendered image, pixel by pixel, while the other method applies the transformation to the projection of the vertices in the scene before they are rendered as an image. We then develop massively parallel solutions for both these methods on the GPU, striving to a reach a real-time rate for the stereoscopic projection of the transformed images.We test both methods for different problem areas, and compare the results to map their strengths and weaknesses. From the obtained results, we conclude that they are both useful in different areas. The vertex transformation performs poorly when the number of vertices in the scene is very high, but for a moderate number of vertices it achieves excellent results, even for exceptionally large image resolutions. The pixel transformation is far less affected by the number of vertices in the scene; however its performance declines rapidly as we increase the size of the image. Both methods were able to execute in real-time for relevant problem sizes.
8
Waddell, Rachel C. "Radar cross section synthesis of doubly curved surfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305445.
Full text
9
Skau, Karl Isak. "Polymer adsorption on curved surfaces : mean field theories /." [S. l.] : [s. n.], 2003. http://catalogue.bnf.fr/ark:/12148/cb39299054x.
Full text
10
Nutter, Jamie Ian. "The stability of boundary layers on curved surfaces and surfaces involving abrupt changes." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/26907.
Full textAbstract:
This thesis is concerned with the effect that boundary-layer instabilities have on laminar- turbulent transition over a commercial aircraft wing. We consider the effect that changing the structure of a wing's surface may have on these instabilities. This thesis is separated into two parts, each concerning a different instability. Firstly our focus is on Tollmien-Schlichting waves; we investigate how abrupt changes may affect boundary-layer transition. The abrupt changes considered are junctions between rigid and porous surfaces. A local scattering problem is formulated; the abrupt changes cause waves to scatter in a subsonic boundary layer. The mechanism is described mathematically by using a triple-deck formalism, while the analysis across the junctions is based in a Wiener- Hopf factorisation. The impact of the wall junctions is characterised by a transmission coefficient, defined as the ratio of the amplitudes of the transmitted and incident waves. From our analysis we determine the effectiveness of porous strips in delaying transition. In the second part of this thesis we concentrate on a curved wing. Over curved sur- faces Görtler vortices may be generated; our focus is on long-wavelength Görtler vortices and the effect of changing curvature. The flow is described using a three-tiered system that balances the displacement and centrifugal forces. Two different problems concerning Görtler vortices are investigated, firstly we consider the effect of slowly varying curvature. Using a WKB approximation we derive multi-scale systems of equations, allowing us to find leading-order analytic solutions. The second problem concerning curved surfaces considers the effect of long-wavelength Görtler vortex-wave interaction. We use vortex-wave interaction theory to describe the evo- lution of this nonlinear interaction over a concave surface, where the curvature is modified in the streamwise direction. Analytical solutions are found for the vortex-induced shear stress and the wave pressure amplitude, using these solutions we solve for the remaining variables numerically.
11
Temmerman, L. "Large eddy simulation of separating flows from curved surfaces." Thesis, Queen Mary, University of London, 2004. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1833.
Full textAbstract:
The capabilities and limitations of LES in predicting separation from curved surfaces at high Reynolds number are at the centre of this Thesis. Issues of particular interest are mesh resolution, subgrid-scale modelling and near-wall approximations aiming to reduce the computational cost. Two cases are examined: a flow separating in a channel with streamwise periodic constrictions (hills), and the flow around a single-element, high-lift aerofoil at a Reynolds number of 2.1 . 106. Prior to these studies, fully-developed channel-flow simulations are considered. These show substantial differences among subgrid-scale models in terms of the subgrid-scale viscosity magnitude and its wall-asymptotic variation. Modelling and numerical errors appear to counteract each other, thus reducing the total error. Wall functions axe shown to be a cost-effective approach, providing a reasonably accurate approximation in near-equilibrium conditions. Adequate resolution remains critical, however, in achieving successful simulations. In the hill flow, separation occurs downstream of the hill crest, reattachment takes place about half-way between two consecutive hills and partial recovery occurs prior to a re-acceleration on the following hill. A highly-resolved simulation, performed to produce -benchmark data, permits an extensive study of the flow properties. Coarser mesh simulations are then compared with the former. These highlight the influence of the streamwise discretisation around the separation point and the role played by the implementation details of the wall treatments, while the subgrid-scale models influence is less significant. The aerofoil, which features transition and separation, is extremely challenging and at the edge of current LES capabilities. None of the simulations reproduce 2 the experimental data well. Indications on the sensitivity to various parameters, including the numerical scheme, the mesh resolution and the spanwise extent, are extracted, however. The studies indicate the need for a structured mesh of about 80 million nodes to achieve the required accuracy. For the present study, this was unaffordable.
12
Jung, Markus Manfred. "Assessment of curved, rotationally symmetric surfaces in three dimensions." Thesis, University of Southampton, 1999. https://eprints.soton.ac.uk/47538/.
Full textAbstract:
Methods for the assessment of curved, rotationally symmetric surfaces in three dimensions are developed and outlined in this thesis. The assessment of electrical switching contacts, contact lens moulds and aspherical leps surfaces is demonstrated. Discrete data for surface assessment is obtained by surface measurement with a profilometer. Hence, surface measurement refers to simultaneous measurement of surface form and surface irregularity. The data is defined in a Cartesian co-ordinate system, and a data set consists of up to 27,000 discrete points on an uniform grid. The grid spacing in x and y is typically between 25um and 125um. The resolution of the data in the vertical axis is lOnm (Inm = 10"9 metre). The key aspects of the research are as follows: A method for data interpretation is proposed. The method is primarily intended to simplify surface assessment of aspherical surfaces. It consists of three key elements: pre-processing, form characterisation and data decomposition into error types. Pre-processing detects the position and orientation of a surface. The surface is then aligned and a separation of surface geometry from position and orientation is achieved. For pre-processing four algorithms are developed, outlined and compared. Form characterisation of rotationally symmetric, aspherical surfaces is then considered. A least squares method is used to fit discrete data to a general solution function in explicit notation. Various problems related to form characterisation with explicit functions are addressed and solutions are presented. Finally, methods for data decomposition into error types are presented. A standardised decomposition method (BS-ISO 10110-5) is compared with an alternative method that is developed in this research. General recommendations for the measurement and the assessment of aspherical surfaces are given. A method for the selection of a form characterisation algorithm for the assessment of nominally spherical surfaces is proposed. Many different sphere fitting algorithms are reported in literature and the best-fit parameters, centre co-ordinates and radius, vary on the same set of discrete data with the algorithm that is used for form characterisation. Five sphere fitting algorithms are investigated in this research: linear and non-linear least squares sphere fit, minimum zone sphere fit, four-point sphere fit and sphere fit by error curve analysis. In conclusion to the investigation it is proposed to use the surface irregularity distribution as a criteria for the selection of a sphere fitting algorithm. The data sampling strategy, distribution of discrete points within a segment and size and location of a segment on a surface, is also investigated. General recommendations for the measurement and the assessment of nominally spherical surfaces are given. The idea of computer aided surface assessment (CASA) is evolved. In CASA, data visualisation and data interpretation are combined for processing of discrete data from the measurement of a surface. Software for computer aided surface assessment is developed and outlined in this thesis.
13
Luo, Jian Yang. "Calculation of turbulent shear layers over highly curved surfaces." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/11500.
Full text
14
Yang, Chang-Gui. "Algorithms for making realistic images of curved surfaces by computer." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278495.
Full text
15
Smith, Jr Philip T. "ANALYSIS AND APPLICATION OF CAPACITIVE DISPLACEMENT SENSORS TO CURVED SURFACES." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/311.
Full textAbstract:
Capacitive displacement sensors have many applications where non-contact, high precision measurement of a surface is required. Because of their non-contact nature they can easily measure conductive surfaces that are flexible or otherwise unable to be measured using a contact probe. Since the output of the capacitance gage is electrical, data points can be collected quickly and averaged to improve statistics. It is often necessary for capacitive displacement sensors to gage the distance from a curved (non-flat) surface. Although displacements can easily be detected, the calibration of this output can vary considerably from the flat case. Since a capacitance gage is typically factorycalibrated against a flat reference, the experimental output contains errors in both gain and linearity. A series of calibration corrections is calculated for rectifying this output. Capacitance gages are also limited in their overall displacement travel. A support stage is described that, along with control electronics, allow the properties of the capacitance gage to be combined with an interferometer to overcome this displacement limitation. Finally, an application is proposed that would make use of the capacitance sensor and support stage assembly.
16
Liu, X. "Shock/boundary-layer interaction on curved surfaces at transonic speeds." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332125.
Full text
17
Smith, Philip T. "Analysis and application of capacitive displacment sensors to curved surfaces." Lexington, Ky. : [University of Kentucky Libraries], 2003. http://lib.uky.edu/ETD/ukymeen2003t00113/ptsmith.pdf.
Full textAbstract:
Thesis (M.S.)--University of Kentucky, 2003.Title from document title page (viewed Sept. 10, 2004). Document formatted into pages; contains x, 146 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 143-144).
18
Tennander, David. "Automatic Projector Calibration for Curved Surfaces Using an Omnidirectional Camera." Thesis, KTH, Optimeringslära och systemteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209675.
Full textAbstract:
This master’s thesis presents one approach to remove distortions generated by projecting onto non flat surfaces. By using an omnidirectional camera a full 360 dome could be calibrated and the corresponding angles between multiple projections could be calculated. The camera was modelled with the Unified Projection Model allowing any omnidirectional camera system to be used. Surface geometry was captured by using Gray code patterns, the optimal image centre was calculated as an quadratic optimisation problem and in the end a Spline surface countering the distortions was generated by using the FAST-LTS regression algorithm. The developed system used a RICOH THETA S camera calibrated by the omnidir module in openCV. A desirable result was achieved and during use of overlapping projectors a maximum error of 0.5° was measured. Testing indicates part of the error could have been introduced in the evaluation measurements. The resulting application is seen as a success and will be used by ÅF Technology AB during calibration of flight simulators.Denna rapport presenterar en metod för att motverka de distorsioner som uppkommer när en bild projeseras på en icke plan yta. Genom att använda en omnidirectional kamera kan en omslutande dome upplyst av flertalet projektorer bli kalibrerad. Kameran modellerades med The Unified Projection Model då modellen går att anpassa för ett stort antal kamerasystem. Projektorernas bild på ytan lästes av genom att använda Gray kod och sedan beräknades den optimala mittpunkten för den kalibrerade bilden genom att numeriskt lösa ett kvadratiskt NLP problem. Till slut skapas en Spline yta som motvärkar projektionsförvrängningen genom FAST-LTS regression. I den experimentella uppställningen användes en RICOH THETA S kamera som kalibrerades men omnidir modulen i openCV. Ett enligt författarna lyckat resultat uppnåddes och vid överlappning av flertalet projektorer så mättes ett maximalt fel på 0.5° upp. Vidare mätningar antyder att delar av detta fel uppkommit på grund av saknad noggrannhet i utrustningen under evalueringsfasen. Resultatet ses som lyckat och den utvecklade applikationen kommer att användas av ÅF Technology AB vid deras calibrering av flygsimulatorer.
19
Charlebois, Mark A. "Exploring the shape of objects with curved surfaces using tactile sensing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq24105.pdf.
Full text
20
Hernandez-Ontiveros, Cesar F. "Numerical analysis of heat transfer during jet impingement on curved surfaces." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002123.
Full text
21
Wong, H. Y. W. "Shear-free turbulence and secondary flow near angled and curved surfaces." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234135.
Full textAbstract:
Turbulence near rigid surfaces is studied in the absence of any gradients in the mean velocity. The theory is valid either when the turbulence is convected downstream along a surface or for a short time after the turbulence is turned on.
22
Cheung, Yim Lui. "Growth and charaterisation of multilayer YBCO coated conductors on curved surfaces." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489288.
Full textAbstract:
Multilayers of STO/YBCO thin films on Ce02/YSZ/CeO2 buffered curved Nibased rolling-assisted biaxially textured substrates (RABiTS) have been grown successfully by pulsed laser deposition in order to demonstrate the feasibility of fabricating an in situ multi-turn superconducting coil on a cylindrical heated former by continuous deposition of sequential layers of superconductor and insulator. Such an approach would offer a radical alternative to the conventional winding of coils from pre-formed long lengths of wires and tapes. AC susceptibility, X-ray diffraction (θ - 20 ω - scans, ψ - scans), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) were used to characterise the superconducting, crystallinity, morphology and microtextural properties of the grown samples. The microstructure and chemical analysis of the interfaces of the curved samples were further investigated by cross-sectional transmission electron microscopy (XTEM) and scanning transmission electron microscopy (STEM). The superconducting and crystallographic properties of the curved composite were similar to those achieved on flat surfaces. The optimum thickness of each YBCO layer in the multilayer architecture was below I gm on a buffered curved surface. In the multilayer structure of six YBCO layers insulated by six STO layers (STO/YBCO)6 on a buffered curved surface, biaxial texture can be still transmitted from the substrate to all the layers and all the YBCO layers had c-axis orientation. Moreover, no interfacial diffusion or chemical reaction was observed at all the interfaces of the multilayer. However, defects such as pores and outgrowths were commonly found which affected the superconducting properties of the curved samples.
23
Bell, Duncan J. "Improving the matching of latent fingerprints on tightly curved surfaces using stereopsis." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540935.
Full text
24
Albarrán, Arriagada Octavio Eduardo, and Arriagada Octavio Eduardo Albarrán. "Curling dynamics of naturally curved surfaces : axisymmetric bio-membranes and elastic ribbons." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-00997537.
Full textAbstract:
Curling deformation of thin elastic surfaces appears in numerous natural and man-made structures where a spontaneous curvature is present. In this thesis, we couple theoretical approaches and macroscopic experiments on elastic ribbons to understand the dynamics of curling of opened bio-membranes, motivated by the need to better understand recent microscopic observations during egress of Malaria infected red blood cells (MIRBC) and bursting of artificial polymersomes.In a first part, we study theoretically pore stability and curling propagation of an initially opened spherical bio-membrane. We model geometrically curling deformation as the revolution of a decentered Archimedean spiral, leading to a prescribed toroidal wrapping of the membrane. In this configuration, we show how the stability of a pore to curling depends strongly on both line-tension and shear elasticity and we discuss these results in relation to the curling of MIRBCs membranes. Moreover, taking into account viscous dissipations, the consequent dynamics we calculate agrees quantitatively well with experimental data obtained during opening of MIRBCs. Our approach shows in particular how the membrane dissipation resulting from the surface redistribution dominates curling dynamics over outer viscous dissipation.However, the complexity of the spherical geometry and the lack of detailed images in microscopic observations hamper the development of more accurate models where the coupling between flow and deformation is fully understood. Subsequently, we study in a second part the curling deformation of macroscopic naturally curved elastic ribbons in different viscous media and elastic conditions. At high Reynolds numbers, due to the tendency of ribbons to localize bending deformations when a curling front travels down the material, we show that curling reaches rapidly a constant propagating velocity. In this regime, the ribbon wraps itself into a compact roll whose size is predicted through the solitary wave solution of the associated Elastica. At low Reynolds numbers, however, closer to the hydrodynamic conditions of curling in microscopic membranes, we show that the strong lubrication forces induce a non-compact curling. The overall size of the spiraling ribbon increases in time leading to a temporal decrease of the released elastic power and therefore a consequent decrease in velocity. We discuss how such discovery sheds a new light on the modeling of curling in MIRBCs and polymersomes.
25
Roland, Jason Howard. "Forced Convection Over Flat and Curved Isothermal Surfaces with Unheated Starting Length." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1418343439.
Full text
26
Albarrán, Arriagada Octavio Eduardo. "Curling dynamics of naturally curved surfaces : axisymmetric bio-membranes and elastic ribbons." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20055/document.
Full textAbstract:
La déformation de matériaux élastique dont l'une au moins des dimensions est petite apparaît dans un grand nombre de structures naturelles ou artificielles pour lesquelles une courbure spontanée est présente. Dans ces travaux de thèse, nous couplons plusieurs approches théoriques à des expériences macroscopiques sur des rubans élastiques afin de comprendre la dynamique d'enroulement de biomembranes ouvertes d'un trou. La motivation est issue d'observations récentes d'enroulements obtenues au cours de la sortie de parasites de la Malaria de globules rouges infectés, et de l'explosion de vésicules polymère. Dans une première partie, nous étudions théoriquement la stabilité d'un pore et la propagation de l'enroulement sur une biomembrane sphérique ouverte. Nous modélisons de façon géométrique l'enroulement toroïdal de la membrane par une spirale d'Archimède de révolution et décentrée. Avec cette hypothèse, nous montrons que la stabilité du pore vis-à-vis de l'enroulement dépend fortement de la tension de ligne et du cisaillement et nous discutons ces résultats dans le cadre de l'enroulement de membranes MIRBCs. De plus, en prenant en compte les différentes sources de dissipation, nous obtenons un très bon accord entre les données expérimentales obtenues pour les MIRBCs et la dynamique d'enroulement obtenue par le calcul. Notre approche montre en particulier que la dissipation dans la membrane due à la redistribution de la matière durant l'enroulement domine sur la dissipation visqueuse dans le milieu.Cependant, la complexité de la géométrie sphérique, ainsi que le nombre limité d'observations microscopiques à l'échelle de la membrane sont une entrave au développement de modèles plus détaillés qui permettraient de décrire complètement le couplage entre écoulement et déformation. Nous avons donc étudié dans une seconde partie la déformation d'enroulement dans le cas de rubans élastiques ayant une courbure spontanée dans différents milieux visqueux et pour différentes conditions élastiques. A grands nombres de Reynolds, en raison de la localisation de la courbure pour les rubans au cours de la propagation du front d'enroulement le long du matériau, nous montrons que l'enroulement atteint rapidement une vitesse de propagation constante. Dans ce régime, le ruban s'enroule sur lui-même de façon compacte, sur un cylindre dont la taille est prévue à partir de la solution de l'onde stationnaire pour l'Elastica. A faible nombre de Reynolds, cependant, se rapprochant des conditions d'enroulement d'une membrane microscopique, nous mettons en évidence l'influence des forces de lubrification sur la nature non-compacte de l'enroulement. La taille globale de la spirale de ruban augmente dans le temps conduisant à une diminution de la puissance élastique libérée et donc à une diminution de la vitesse. Nous discutons dans quelle mesure ces résultats peuvent faire avancer la modélisation de l'enroulement dans les MIRBCs et les vésicules polymèreCurling deformation of thin elastic surfaces appears in numerous natural and man-made structures where a spontaneous curvature is present. In this thesis, we couple theoretical approaches and macroscopic experiments on elastic ribbons to understand the dynamics of curling of opened bio-membranes, motivated by the need to better understand recent microscopic observations during egress of Malaria infected red blood cells (MIRBC) and bursting of artificial polymersomes.In a first part, we study theoretically pore stability and curling propagation of an initially opened spherical bio-membrane. We model geometrically curling deformation as the revolution of a decentered Archimedean spiral, leading to a prescribed toroidal wrapping of the membrane. In this configuration, we show how the stability of a pore to curling depends strongly on both line-tension and shear elasticity and we discuss these results in relation to the curling of MIRBCs membranes. Moreover, taking into account viscous dissipations, the consequent dynamics we calculate agrees quantitatively well with experimental data obtained during opening of MIRBCs. Our approach shows in particular how the membrane dissipation resulting from the surface redistribution dominates curling dynamics over outer viscous dissipation.However, the complexity of the spherical geometry and the lack of detailed images in microscopic observations hamper the development of more accurate models where the coupling between flow and deformation is fully understood. Subsequently, we study in a second part the curling deformation of macroscopic naturally curved elastic ribbons in different viscous media and elastic conditions. At high Reynolds numbers, due to the tendency of ribbons to localize bending deformations when a curling front travels down the material, we show that curling reaches rapidly a constant propagating velocity. In this regime, the ribbon wraps itself into a compact roll whose size is predicted through the solitary wave solution of the associated Elastica. At low Reynolds numbers, however, closer to the hydrodynamic conditions of curling in microscopic membranes, we show that the strong lubrication forces induce a non-compact curling. The overall size of the spiraling ribbon increases in time leading to a temporal decrease of the released elastic power and therefore a consequent decrease in velocity. We discuss how such discovery sheds a new light on the modeling of curling in MIRBCs and polymersomes
27
Smith, Philip T. "Capacitance metrology of curved surfaces study and characterization of a novel probe design /." Lexington, Ky. : [University of Kentucky Libraries], 2007. http://hdl.handle.net/10225/745.
Full textAbstract:
Thesis (Ph. D.)--University of Kentucky, 2007.Title from document title page (viewed on March 24, 2008). Document formatted into pages; contains: xii, 253 p. : ill (some col.). Includes abstract and vita. Includes bibliographical references (p. 244-251).
28
Smith, Jr Philip T. "CAPACITANCE METROLOGY OF CURVED SURFACES: STUDY AND CHARACTERIZATION OF A NOVEL PROBE DESIGN." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/570.
Full textAbstract:
Capacitive sensors are frequently applied to curved target surfaces for precision displacement measurements. In most cases, these sensors have not been recalibrated to take the curvature of the target into consideration. This recalibration becomes more critical as the target surface becomes smaller in comparison to the sensor. Calibration data are presented for a variety of capacitance probe sizes with widely varying geometries. One target surface particularly difficult to characterize is the inner surface of small holes, less than one millimeter in diameter. Although contact probes can successfully measure the inner surface of a hole, these probes are often fragile and require additional sensors to determine when contact occurs. Probes may adhere to the wall of the hole, and only a small number of data points are collected. Direct capacitance measurement of small holes requires a completely new capacitance probe geometry and method of operation. A curved, elongated surface minimizes the gap between the sensor surface and the inner surface of the hole. Reduction in the size of the sensing area is weighed against electronics limitations. The performance of a particular probe geometry is studied using computer simulations to determine the optimal probe design. Multiple, overlapping passes are deconvolved to reveal finer features on the surface of the hole. A prototype sub-millimeter capacitance probe is machined from tungsten carbide, with four additional material layers added using ebeam deposition. Several techniques are studied to remove these layers and create a sensing area along one side of the probe. Both mechanical processes and photolithography are employed.
29
Zogbi, George C. "Reflection and diffraction of general astigmatic Gaussian beams from curved surfaces and edges /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1303147091.
Full text
30
Lee, Young-Lim. "The Perception and Recognition of 3-D Shape from Shadows Cast onto Curved Surfaces." TopSCHOLAR®, 2003. http://digitalcommons.wku.edu/theses/609.
Full textAbstract:
The informativeness of a cast shadow or silhouette boundary contour for the perception of 3-D object shape has been investigated for a long time. Some researchers have focused on the informativeness of static shadows (Attneave, 1954; Koenderink, 1984; Richards, Koenderink, & Hoffman, 1987; Norman, Phillips, & Ross, 2001; Tse, 2002) while other researchers have focused on the informativeness of moving or deforming shadows (Miles, 1931; Wallach, & O'Connell, 1953; Norman, & Todd, 1994; Norman, Dawson, & Raines, 2000; Norman, & Raines, 2002). Past research has shown that changing the angle of illumination does not affect the perception of 3-D shape from cast shadows (Norman et al., 2000). The current experiment extends the prior experiments by further investigating whether curved background surfaces (with both positive and negative Gaussian curvature) affect the perception and recognition of 3-D object shape from deforming and/or static cast shadows. In this experiment, the observers viewed either deforming or static shadows of naturally shaped objects (bell-peppers) cast onto either flat, hemispherical, or saddle-shaped surfaces. The results revealed significant main effects of motion (deforming vs. static shadows), object, and the type of background surface. The results revealed that there were also a number of significant interactions involving particular objects, the presence or absence of motion, and the type of background surface. The observers' ability to recognize objects from deforming shadows was higher than their ability to recognize objects from static shadows. In addition, the observers' ability to recognize objects from the shadows cast onto the hemisphere background surface was generally as accurate as their ability to recognize objects from the shadows cast onto the flat plane. However, the observers' ability to recognize the objects was reduced when the shadows were cast onto the saddle background surface. The results of the experiment confirm previous findings showing that shadow boundary contours, especially deforming contours, are perceptually informative and help observers to perceive and recognize 3-D object shape. This experiment also extends previous studies by showing how differently curved background surfaces affect the perception and recognition of 3-D object shape.
31
Mark, Lewis Paul. "Carbon nanotubes and other highly curved surfaces for field emission and field-promoted ionisation." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3170/.
Full textAbstract:
The thesis describes the development of various novel emitters for the production of gaseous ions from solutions of non-volatile, thermally labile samples for the purposes of mass spectrometry. Nano-electrospray emitters each containing two separated channels running throughout the length of the emitter were fabricated and evaluated. These emitters were made from “theta-shaped” borosilicate capillaries, employing a number of different coating procedures. Loading of different solutions into the channels demonstrated the possibility of studying solute interactions on ultrashort timescales. It is proposed that interactions took place in a shared Taylor cone. The formation of specific adducts from vancomycin and diacetyl-l-lysyld- alanyl-d-alanine was observed by mass spectrometry. From consideration of the extent of H/D exchange between vancomycin and deuterated vancomycin, it was concluded that the interaction times were of the order of 10-5 s. Underlying theoretical considerations, design and fabrication from carbon nanotubes (CNTs) of emitters for field desorption and field ionization ion sources are described and discussed. The emitters fabricated made use of arrays of vertically aligned multi-walled CNTs with in most cases an average length and radius of 15 μm and 35 nm respectively. Emitters using dense coverings of nanotubes and emitters with nanotubes selectively grown so that the height of each nanotube was twice its separation from its nearest neighbour were investigated. Characterisation of the CNTs by field electron-emission confirmed their effectiveness as field emitters. Fowler-Nordhein plots indicated fields of 6.14x109 +/- 0.72x109 V/m at a potential of 700 V. Field ionization of He, Ar, Xe, methane and acetone was achieved with these same CNTs; neither the inert gases nor methane have been field ionised with conventional activated-wire emitters. The fields generally accepted to be required for field ionisation of He and Ar are of the order of several 1010 V/m. To create emitters which would not need to be removed from vacuum between experiments, a means of injecting both liquids and gaseous samples directly to the bottom of the CNTs was devised. This involved drilling 20 μm diameter holes through the silicon substrate between intended sites of nanotube growth, but before actually growing the CNTs. It was discovered that the presence of the holes led to surface migration of the nickel catalysts initiating CNT growth. Experiments undertaken to achieve mass spectrometric measurements with the arrays of CNTs as emitters are described and discussed.
32
Nelson, Todd G. "Art to Engineering: Curved Folding and Developable Surfaces in Mechanism and Deployable Structure Design." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6865.
Full textAbstract:
This work investigates how curved-crease origami and the developable surfaces which compose it can be transitioned to engineering design. Methods for creating flexible, tailorable-property surfaces that function as thick panels in place of paper are presented. Concepts from curved-crease origami and developable surfaces that can describe and extend engineering applications are discussed and demonstrated. These concepts are particularly beneficial to applications where curved surfaces are integral to the function, deployability is desired, and planar manufacturing could be beneficial.The first part of this work uses arrays of compliant elements to create flexible-tailorable property surfaces. The key feature to these arrays is the alignment of the most flexible bending axis of the individual elements to the ruling line arrangement of a developable surface. This alignment can enable bending of thick panels while maintaining lower stresses, a quality necessary for the transitioning of curved-crease origami into thick materials. The stiffness and stress of these arrays is modeled and physical prototypes are demonstrated. Additionally, shape factors are developed for these compliant arrays (CAs) to facilitate material selection for the panels and understand how the geometry of the array changes the effective properties of the panel. The second part of this work describes and demonstrates several concepts of curved-crease origami and developable surfaces that can benefit mechanism and structure design, particularly in the context of rolling-contact mechanisms. The design of a rolling-contact joint connected by flexible bands similar to a Jacob's Ladder toy is extended through incorporating curved creases into the design. The resulting design is deployable from a compact state to a functional state and can be manufactured from a single plane and folded into shape. Mathematical formulations are presented to describe the classes of developable surfaces in terms of properties which are frequently important in mechanism design. These natural equations for a single class of developable surface are conducive to modeling the folding motion of rigid-ruling developables, developables whose ruling lines do change location in a surface during folding. These formulations are used to generalize the design of rolling-contact joints to a family of joints capable of single degree of freedom spatial motions, being manufactured from a plane, and exhibiting a tailorable force response. Finally practical design suggestions for the implementation of rolling-contact joints is given. These include methodology to create sunken flexures which serve to increase the normal force between rolling bodies to prevent slip.
33
Supreeti, Shraddha [Verfasser], Stefan [Akademischer Betreuer] Sinzinger, Martin [Akademischer Betreuer] Hoffmann, and Steffen [Akademischer Betreuer] Strehle. "Soft nanoimprint lithography on curved surfaces / Shraddha Supreeti ; Stefan Sinzinger, Martin Hoffmann, Steffen Strehle." Ilmenau : TU Ilmenau, 2021. http://d-nb.info/1239051182/34.
Full text
34
Gao, Zaixiang. "The numerical treatment of curved boundary surfaces in an unfitted grid formulation for computational fluid dynamics." Thesis, Cranfield University, 1999. http://hdl.handle.net/1826/3405.
Full textAbstract:
In this thesis a new Cartesian cut-cell scheme has been presented which solves the in-
compressible Navier-Stokes equations using a finite volume approach and a staggered
grid. The equations have been solved in conservation-law form upon a network of
cell which were created using a Cartesian, cell-based grid generation procedure. This
method used a recursive subdivision of fixed aspect ratio (Cartesian) cells creating
arbitrarily shaped polygons when the Cartesian cell straddles a boundary, using a
modified polygon clipping algorithm.
The numerical scheme adopted is the finite volume formulation, adaptive multi-
grid algorithm, and the Cartesian cut cell method. The scheme is modified to allow
accurate calculation of flow variables at the intersection of curved body boundaries
on non-aligned grids. A novel method to distinguish boundary cells is developed in
this project.
The outline of the thesis is as follows: firstly, the modelling and simulation of un-
fitted Cartesian grids, structured grids, and unstructured grids are reviewed, together
with the different numerical techniques implemented in the solver. Finite volume dis-
crete equations are then derived on structured, staggered grid. Next, having specified
the solution algorithm, we introduce the Cartesian cut cell method and consider the
accuracy of the solver. Results from several test cases of varying complexity are com-
pared with those of a widely used commercial CFD package and good agreement is
obtained. The results of this method show that the Cartesian cut cell approach is second-
order accurate for the two-dimensional flows. The question of performance of the
algorithm is also addressed in detail, both in terms of robustness and speed of con-
vergence by modified transformations. Good accelerations are obtained using the
adaptive multigrid method but the convergence rates are often not grid-independent.
Convergence rates are much faster than those achieved by single grid solvers and com-
mercial codes, although the solver is not fully optimal. It is confirmed that multigrid
methods offer a good framework for the implementation of grid adaptation, particu-
larly in areas where the flow variable change abruptly/rapidly. Considerable gains in
speed and memory usage, by one further order of magnitude, are achieved.
35
Coe, Edward Olin. "Printing on Objects: Curved Layer Fused Filament Fabrication on Scanned Surfaces with a Parallel Deposition Machine." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101096.
Full textAbstract:
Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short.
The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces.
Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters.Master of Science
36
Shellabarger, Brian Tebelman. "Experimental studies of high-speed liquid films on flat and curved downward-facing surfaces for IFE applications." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180413/unrestricted/shellabarger%5fbrian%5ft%5f200312%5fms.pdf.
Full text
37
Auer, Cornelia [Verfasser]. "Visualization of fundamental structures in two dimensional second order tensor fields on planar and curved surfaces / Cornelia Auer." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1053326599/34.
Full text
38
Chambers, James P. "Scale model experiments on the diffraction and scattering of sound by geometrical step discontinuities and curved rough surfaces." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17858.
Full text
39
Mashina, Giamal A. M. "Prediction of the Solar Performance of Curved Surfaces with Different Cross-Sectional Forms, Using a New Computer Program." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523597.
Full textAbstract:
Curved forms have always been an important part of architecture for visual, structural, religious, or environmental reasons. Nowadays, in many parts of the world, curved surface shapes in building structures quite common, particularly in the hot climate regions. In addition to the traditional curved surfaces (domes and vaults), convex walls have also been extensively used in the construction of modem buildings. Accurate and specific distribution of direct solar radiation on curved surfaces is desired in a variety of fields and an important parameter when simulating the thermal performance of buildings. In this thesis, a computer model is developed to predict the quantity of incident direct solar energy on curved surfaces with a variety of forms and with different cross-sectional ratios at different orientations under a clear sky. The model based on a mesh represents the curved geometrical shape and simple mathematical equations to calculate the direct solar radiation at certain coordinates. In general, the results of the simulations indicate that the amount of direct solar radiation received by horizontal surface can be reduced using the curved surface. Results also reveal that the efficiency of curved surfaces can be significantly improved by choosing the proper design and orientation, which in tum can reduce the overall cost of cooling in hot months. The code has been tested against a number of computer programs for a set of geometrical conditions and. the results show a good agreement. Such a model can provide the architects and building engineers with a new easy-to-use tool that may help them during the early design stages.
40
Abolghasemibizaki, Mehran. "Liquid Interaction with Non-wettable Surfaces Structured with Macroscopic Ridges." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5381.
Full textAbstract:
Self-cleaning, anti-corrosion, anti-icing, dropwise-condensation, and drag-reduction are some applications in which superhydrophobic surfaces are implemented. To date, all the studies associated with superhydrophobic surfaces have been dedicated to understanding the liquid interaction with surfaces that are macroscopically smooth. The current study investigates the solid-liquid interaction of such surfaces which are fully decorated with macroscopic ridges (ribbed surfaces). In particular, the drop motion and impact on our newly designed non-wettable ribbed surface have been investigated in this work. Our experimental investigations have shown that liquid drops move faster on the ribbed surfaces due to lower friction induced by such a surface pattern. Moreover, an impacting droplet shows shorter contact time on ribbed surfaces. This concludes that ribbed surface pattern can be an efficient alternative design for the related applications.
Besides the experimental studies, the theoretical analyses done in this work have led to, firstly a scaling model to predict descent velocity of a rolling viscous drops on an inclined non-wettable surface more accurately. Secondly, for curved superhydrophobic surfaces a scaling model which correlates the contact time of the impacting drop to its impact velocity has been developed. At the end, the knowledge obtained from this work has led to a special surface design which exhibits a contact time shorter than the inertial-capillary time scale, an unprecedented phenomenon.
41
Dobbertean, Mark Michael. "Steady and Transient Heat Transfer for Jet Impingement on Patterned Surfaces." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3076.
Full textAbstract:
Free liquid-jet impingement is well researched due to its high heat transfer ability and ease of implementation. This study considers both the steady state and transient heating of a patterned plate under slot-free-liquid jet impingement. The primary working fluid was water (H2O) and the plate material considered was silicon. Calculations were done for Reynolds number (Re) ranging from 500 to 1000 and indentation depths from 0.000125 to 0.0005 m for three different surface configurations. The effect of using different plate materials and R-134a as the working fluid were explored for the rectangular step case. The distributions of the local and average heat-transfer coefficient and the local and average Nusselt number were calculated for each case. A numerical model based in the FIDAP computer code was created to solve the conjugate heat transfer problem. The model used was developed for Cartesian coordinates for both steady state and transient conditions.
Results show that the addition of surface geometry alters the fluid flow and heat transfer values. The highest heat-transfer coefficients occur at points where the fluid flow interacts with the surface geometry. The lowest heat-transfer coefficients are found in the indentations between the changes in geometry. The jet velocity has a large impact on the heat transfer values for all cases, with increasing jet velocity showing increased local heat-transfer coefficients and Nusselt number. It is observed that increasing the indentation depth for the rectangular and sinusoidal surfaces leads to a decrease in local heat transfer whereas for triangular patterns, a higher depth results in higher heat-transfer coefficient. The transient analysis showed that changing surface geometry had little effect on the time required to reach steady state. The selection of plate material has an impact on both the final maximum temperatures and the time required to reach steady state, with both traits being tied to the thermal diffusivity (α) of the material.
42
Streubel, Robert [Verfasser], Oliver G. [Akademischer Betreuer] Schmidt, Oliver G. [Gutachter] Schmidt, Denys [Akademischer Betreuer] Makarov, and Peter [Gutachter] Fischer. "Imaging Spin Textures on Curved Magnetic Surfaces / Robert Streubel ; Gutachter: Oliver G. Schmidt, Peter Fischer ; Oliver G. Schmidt, Denys Makarov." Chemnitz : Universitätsbibliothek Chemnitz, 2015. http://d-nb.info/1213813646/34.
Full text
43
Genevaux, Chloé. "Structures modulaires de bandes pliées." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1152.
Full textAbstract:
Les structures pliées intéressent architectes et ingénieurs pour leurs qualités structurelles autant que spatiales et plastiques. En prenant comme point de départ la bande rectiligne pliée, ce travail de recherche aborde non pas la conception de surfaces plissées mais celle de structures réticulées. La conception de structures “à trous” à partir de bandes pliées constitue un angle d’approche original. La notion de continuité induite par le pli transforme la manière de concevoir la structure réticulée, habituellement caractérisée par des nœuds et barres dissociés. L’emploi de bandes continues rectilignes est une approche possible pour rationaliser la conception de formes complexes en minimisant la quantité de chutes de matière. Cette recherche explore de nouvelles méthodes de conception des formes courbes. Les objectifs de cette recherche sont :- la classification des différentes approches possibles dans la conception à partir de bandes rectilignes pliées- l'étude d'éléments modulaires pliés dont l’assemblage permet la génération de surfaces courbes variables: la géométrie de différentes configurations de bandes pliées sera décrite ainsi que les assemblages autorisésFolded structures are attractive to architects and engineers for their structural qualities as well as spatial and plastic qualities. Taking as a starting point a linear folded stripe, this research does not address the design of pleated surfaces but that of reticular structures. The design of structures with "holes" from folded stripes is an original angle of approach. From a conceptual point of view, the continuity caused by folds transforms the usual conception by separated nodes and bars of reticular structures. The use of continuous linear stripes is one possible approach to make more efficient the design of complex shapes by minimizing the produced offcuts. This research investigates new methods of designing curved shapes. The aims of this research are:- A classification of different possible approaches encountered when conceiving from folded stripes.- The study a modular folded elements which assembly allows the generation of various curved surfaces : the geometry of different configurations of folded stripes and the assemblies allowed will be described
44
Lyon, Eduardo. "Component based design and digital manufacturing: a design for manufacturing model for curved surfaces fabrication using three axes computer numerical controlled router." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/36531.
Full textAbstract:
This thesis explores new ways to integrate manufacturing processes information in to design phases. Through the use of design for manufacturing (DfM) concept, and looking at relations between its potential application in architectural production and its implementation using digital manufacturing technologies, the author implemented a DfM model that varies from previous models by incorporated learning in the process. This process was based on the incremental development and refinement of design heuristics and metrics.
The DfM model developed in this research is a process model to be implemented as a framework within educational settings. The proposed model is based in two basic strategies; first a process description in the form of alternative design strategies; and second, the implementation of design heuristics and design metrics. Subsequently, the author tested and refined the model using a sequence of case studies with students.
In the final stage, the research evaluated and further developed the DfM model in a component design case study. The general purpose in performing this case studies sequence was to test the proposed DfM model. The second objective was to refine the DfM model by capturing knowledge from the case studies.
As a summary, this research conceptualizes from this top-down development approach to create a design for manufacturing model that integrates design and construction in architecture, based on three possible applications fields; DfM teaching approaches development, design processes improvement; and DfM methods development.
The final purpose is to provide better foundational constructs for architectural education and to improve teaching approaches that integrate design and manufacturing.
45
Forslund, Ola. "Scattering and propagation of electromagnetic waves in planar and curved periodic structures - applications to plane wave filters, plane wave absorbers and impedance surfaces." Doctoral thesis, KTH, Alfvén Laboratory, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3825.
Full textAbstract:
The subject of this thesis is scattering of electromagneticwaves from planar and curved periodic structures. The problemspresented are solved in the frequency domain.
Scattering from planar structures with two-dimensionalperiodic dependence of constitutive parameters is treated. Theconstitutive parameters are assumed to vary continuously orstepwise in a cross section of a periodically repeating cell.The variation along a longitudinal coordinate z is arbitrary. Ageneral skew lattice is assumed. In the numerical examples, lowloss and high loss dielectric materials are considered. Theproblem is solved by expanding the .elds and constitutiveparameters in quasi-periodic and periodic functionsrespectively, which are inserted into Maxwells equations.Through various inner products de.ned with respect to the cell,and elimination of the longitudinal vector components, a linearsystem of ordinary di.erential equations for the transversecomponents of the .elds is obtained. After introducing apropagator, which maps the .elds from one transverse plane toanother, the system is solved by backward integration.Conventional thin metallic FSS screens of patch or aperturetype are included by obtaining generalised transmission andre.ection matrices for these surfaces. The transmission andre.ection matrices are obtained by solving spectral domainintegral equations. Comparisons of the obtained results aremade with experimental results (in one particular case), andwith results obtained using a computer code based on afundamentally di.erent time domain approach.
Scattering from thin singly curved structures consisting ofdielectric materials periodic in one dimension is alsoconsidered. Both the thickness and the period are assumed to besmall. The .elds are expanded in an asymptotic power series inthe thickness of the structure, and a scaled wave equation issolved. A propagator mapping the tangential .elds from one sideto the other of the structure is derived. An impedance boundarycondition for the structure coated on a perfect electricconductor is obtained.
Keywords:electromagnetic scattering, periodicstructure, frequency selective structure, frequency selectivesurface, grating, coupled wave analysis, electromagneticbandgap, photonic bandgap, asymptotic boundary condition,impedance boundary condition, spectral domain method,homogenisation
46
Gauss, Florian [Verfasser], Klaus [Akademischer Betreuer] Rückert, Klaus [Gutachter] Rückert, and Chris [Gutachter] Williams. "The development of computing tools to approximate doubly curved surfaces with quadrilateral planar facets / Florian Gauss ; Gutachter: Klaus Rückert, Chris Williams ; Betreuer: Klaus Rückert." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1219962775/34.
Full text
47
Velásquez, Flores Edgar José. "Graphic platform for curves and surfaces: análisis de curvas planas." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2013. http://hdl.handle.net/10757/273608.
Full textAbstract:
El proyecto profesional que se presenta a continuación tiene como principal el desarrollo de las nuevas características para curvas planas aplicada a Graphic Platform for Curves and Surfaces1 (GPLACS). La meta principal estará en poder incorporar satisfactoriamente las nuevas características al producto ya existente GPLACS en su apartado de curvas planas. Además, también se busca que al terminar la implementación de funcionalidades se pueda adaptar la parte de 2D de GPLACS para poder ser utilizada usando las pizarras digitales que se encuentran en la universidad. En la primera parte de este documento encontraremos la definición del proyecto y su planteamiento. Luego se verá los problemas que este intentará solucionar así como el contexto en el que se encuentra. En la segunda parte se verán los principios matemáticos en los que se basan las nuevas funcionalidades así como también los principios algorítmicos que sirvieron para poder implementarlas. Más adelante, presentaremos los procesos con los cuales se elabora el software teniendo como base de desarrollo la metodología Feature Driven Development2 (FDD). Una vez visto esto se presentan los resultados obtenidos hasta el momento y el cumplimiento según el plan. Luego explicaremos los detalles más técnicos del software como son la lista de funcionalidades e historias de usuario.Tesis
48
Melle, Michael [Verfasser], Martin [Akademischer Betreuer] Schoen, Carol K. [Akademischer Betreuer] Hall, and Sabine H. L. [Akademischer Betreuer] Klapp. "Anisotropic fluids and the manipulation of their ordering at curved surfaces / Michael Melle. Gutachter: Martin Schoen ; Sabine H. L. Klapp ; Carol K. Hall. Betreuer: Martin Schoen ; Carol K. Hall." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1066161313/34.
Full text
49
Pester, M. "Behandlung gekrümmter Oberflächen in einem 3D-FEM-Programm für Parallelrechner." Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199801386.
Full textAbstract:
The paper presents a method for generating curved
surfaces of 3D finite element meshes by mesh
refinement starting with a very coarse grid.
This is useful for parallel implementations where
the finest meshes should be computed and not read from
large files. The paper deals with simple geometries
as sphere, cylinder, cone. But the method may be
extended to more complicated geometries.
(with 45 figures)
50
de, Almeida Otterson James Joaquim. "Curves in algebraic surfaces." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525234.
Full text