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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Thermo-mechanical stress analysis and interfacial reliabiity for through-silicon vias in three-dimensional interconnect structures

Ryu, Suk-Kyu 26 January 2012 (has links)
Continual scaling of devices and on-chip wiring has brought significant challenges for materials and processes beyond the 32-nm technology node in microelectronics. Recently, three-dimensional (3-D) integration with through-silicon vias (TSVs) has emerged as an effective solution to meet the future interconnect requirements. Among others, thermo-mechanical reliability is a key concern for the development of TSV structures used in die stacking as 3-D interconnects. In this dissertation, thermal stresses and interfacial reliability of TSV structures are analyzed by combining analytical and numerical models with experimental measurements. First, three-dimensional near-surface stress distribution is analyzed for a simplified TSV structure consisting of a single via embedded in a silicon (Si) wafer. A semi-analytic solution is developed and compared with finite element analysis (FEA). For further study, the effects of anisotropic elasticity in Si and metal plasticity in the via on the stress distribution and deformation are investigated. Next, by micro-Raman spectroscopy and bending beam technique, experimental measurements of the thermal stresses in TSV structures are conducted. The micro-Raman measurements characterize the local distribution of the near-surface stresses in Si around TSVs. On the other hand, the bending beam technique measures the average stress and viii deformation in the TSV structures. To understand the elastic and plastic behavior of TSVs, the microstructural evolution of the Cu vias is analyzed using focused ion beam (FIB) and electron backscattering diffraction (EBSD) techniques. To study the impacts of the thermal stresses on interfacial reliability of TSV structures, an analytical solution is developed for the steady-state energy release rate as the upper bound of the driving force for interfacial delamination. The effect of crack length and wafer thickness on the energy release rate is studied by FEA. Furthermore, to model interfacial crack nucleation, an analytical approach is developed by combining a shear lag model with a cohesive interface model. Finally, the effects of structural designs and the variation of the constituent materials on TSV reliability are investigated. The steady state solutions for the energy release rate are developed for various TSV designs and via materials (Al, Cu, Ni, and W) to evaluate the interfacial reliability. The parameters for TSV design optimization are discussed from the perspectives of interfacial reliability. / text
132

Learning 3-D Models of Object Structure from Images

Schlecht, Joseph January 2010 (has links)
Recognizing objects in images is an effortless task for most people.Automating this task with computers, however, presents a difficult challengeattributable to large variations in object appearance, shape, and pose. The problemis further compounded by ambiguity from projecting 3-D objects into a 2-D image.In this thesis we present an approach to resolve these issues by modeling objectstructure with a collection of connected 3-D geometric primitives and a separatemodel for the camera. From sets of images we simultaneously learn a generative,statistical model for the object representation and parameters of the imagingsystem. By learning 3-D structure models we are going beyond recognitiontowards quantifying object shape and understanding its variation.We explore our approach in the context of microscopic images of biologicalstructure and single view images of man-made objects composed of block-likeparts, such as furniture. We express detected features from both domains asstatistically generated by an image likelihood conditioned on models for theobject structure and imaging system. Our representation of biological structurefocuses on Alternaria, a genus of fungus comprising ellipsoid and cylindershaped substructures. In the case of man-made furniture objects, we representstructure with spatially contiguous assemblages of blocks arbitrarilyconstructed according to a small set of design constraints.We learn the models with Bayesian statistical inference over structure andcamera parameters per image, and for man-made objects, across categories, suchas chairs. We develop a reversible-jump MCMC sampling algorithm to exploretopology hypotheses, and a hybrid of Metropolis-Hastings and stochastic dynamicsto search within topologies. Our results demonstrate that we can infer both 3-Dobject and camera parameters simultaneously from images, and that doing soimproves understanding of structure in images. We further show how 3-D structuremodels can be inferred from single view images, and that learned categoryparameters capture structure variation that is useful for recognition.
133

Sparseness-constrained data continuation with frames: Applications to missing traces and aliased signals in 2/3-D

Hennenfent, Gilles, Herrmann, Felix J. January 2005 (has links)
We present a robust iterative sparseness-constrained interpolation algorithm using 2/3D curvelet frames and Fourier-like transforms that exploits continuity along reflectors in seismic data. By choosing generic transforms, we circumvent the necessity to make parametric assumptions (e.g. through linear/parabolic Radon or demigration) regarding the shape of events in seismic data. Simulation and real data examples for data with moderately sized gaps demonstrate that our algorithm provides interpolated traces that accurately reproduce the wavelet shape as well as the AVO behavior. Our method also shows good results for de-aliasing judged by the behavior of the (f-k)-spectrum before and after regularization.
134

Computation of time-lapse differences with 3D directional frames

Bayreuther, Moritz, Cristall, Jamin, Herrmann, Felix J. January 2005 (has links)
We present an alternative method of extracting production related differences from time-lapse seismic data sets. Our method is not based on the actual subtraction of the two data sets, risking the enhancement of noise and introduction of artifacts due to local phase rotation and slightly misaligned events. Rather, it mutes events of the monitor survey with respect to the baseline survey based on the magnitudes of coefficients in a sparse and local atomic decomposition. Our technique is demonstrated to be an effective tool for enhancing the time-lapse signal from surveys which have been cross-equalized
135

Enseñanza de la geometría con utilización de recursos multimedia. Aplicación a la primera etapa de educacioón básica.

Vilchez González, Nieves M. 21 April 2004 (has links)
Enseñar contenidos geométricos a niños de corta edad no es tarea sencilla, más aún, si no se manejan estrategias didácticas adecuadas, junto a medios y recursos ideales para tal fin. A través de este trabajo y producto de reflexiones y acciones sobre la práctica misma de la enseñanza de la Geometría en la 1era. Etapa de Educación Básica (Estudio de caso) se motiva al docente con diferentes software, para iniciarlo en la planificación, diseño y producción de materiales multimedia a través del Programa Clic 3.0, dirigidos éstos, a apoyar el acto didáctico en relación a esos contenidos. Simultáneamente, se detectan dificultades y limitaciones para abordar la enseñanza del Bloque de Geometría del área de matemáticas, dando lugar a una propuesta de mejora hacia la Enseñanza-Aprendizaje de la Geometría(EAG) con utilización de Los multimedia, como recurso didáctico. / To teach geometric contents to children of short age is not simple task, stiller, if appropriate didactic strategies are not managed, next to means and ideal resources for such an end. Through this work and product of reflections and actions on the same practice of the teaching of the Geometry in First Stage of Basic Education (A case Study) is motivated to the educational one with different software, to begin it in the planning, design and production of material multimedia through the Program Clic 3.0, directed these, to support the didactic act in relation to those contents. Simultaneously, difficulties and limitations are detected to approach the teaching of the Block of Geometry of the area of mathematics, giving place to a proposal of improvement toward the Teaching-learning of the Geometry (EAG) with use of the multimedia, as didactic resource.
136

Reconfigurable Logic Architectures based on Disruptive Technologies

Gaillardon, Pierre-Emmanuel 15 September 2011 (has links) (PDF)
For the last four decades, the semiconductor industry has experienced an exponential growth. According to the ITRS, as we advance into the era of nanotechnology, the traditional CMOS electronics is reaching its physical and economical limits. The main objective of this thesis is to explore novel design opportunities for reconfigurable architectures given by the emerging technologies. On the one hand, the thesis will focus on the traditional FPGA architecture scheme, and survey some structural improvements brought by disruptive technologies. While the memories and routing structures occupy the major part of the FPGAs total area and mainly limit the performances, 3-D integration appears as a good candidate to embed all this circuitry into the metal layers. Configuration and routing circuits based on back-end compatible resistive memories, a monolithic 3-D process flow and a prospective vertical FETs process flow are introduced and assessed within a complete architectural context. On the other hand, the thesis will present some novel architectural schemes for ultra-fine grain computing. The size of the logic elements can be reduced thanks to inherent properties of the technologies, such as the crossbar organization or the controllable polarity of carbon electronics. Considering the granularity of the logic elements, specific fixed and incomplete interconnection topologies are required to prevent the large overhead of a configurable interconnection pattern. To evaluate the potentiality of this new architectural scheme, a specific benchmarking flow will be presented in order to explore the ultra-fine grain architectural design space.
137

Novel Approaches in Structured Light Illumination

Wang, Yongchang 01 January 2010 (has links)
Among the various approaches to 3-D imaging, structured light illumination (SLI) is widely spread. SLI employs a pair of digital projector and digital camera such that the correspondences can be found based upon the projecting and capturing of a group of designed light patterns. As an active sensing method, SLI is known for its robustness and high accuracy. In this dissertation, I study the phase shifting method (PSM), which is one of the most employed strategy in SLI. And, three novel approaches in PSM have been proposed in this dissertation. First, by regarding the design of patterns as placing points in an N-dimensional space, I take the phase measuring profilometry (PMP) as an example and propose the edge-pattern strategy which achieves maximum signal to noise ratio (SNR) for the projected patterns. Second, I develop a novel period information embedded pattern strategy for fast, reliable 3-D data acquisition and reconstruction. The proposed period coded phase shifting strategy removes the depth ambiguity associated with traditional phase shifting patterns without reducing phase accuracy or increasing the number of projected patterns. Thus, it can be employed for high accuracy realtime 3-D system. Then, I propose a hybrid approach for high quality 3-D reconstructions with only a small number of illumination patterns by maximizing the use of correspondence information from the phase, texture, and modulation data derived from multi-view, PMP-based, SLI images, without rigorously synchronizing the cameras and projectors and calibrating the device gammas. Experimental results demonstrate the advantages of the proposed novel strategies for 3-D SLI systems.
138

Rotate and Hold and Scan (RAHAS): Structured Light Illumination for Use in Remote Areas

Crane, Eli Ross 01 January 2011 (has links)
As a critical step after the discovery of material culture in the field, archaeologists have a need to document these findings with a slew of different physical measurements and photographs from varying perspectives. 3-D imaging is becoming increasingly popular as the primary documenting method to replace the plethora of tests and measurements, but for remote areas 3-D becomes more cumbersome due to physical and environmental constraints. The difficulty of using a 3-D imaging system in such environments is drastically lessened while using the RAHAS technique, since it acquires scans untethered to a computer. The goal of this thesis is to present the RAHAS Structured Light Illumination technique for 3-D image acquisition, and the performance of the RAHAS technique as a measurement tool for documentation of material culture on a field trip to the Rio Platano Biosphere in Honduras.
139

Direct Structured Finite Element Mesh Generation from Three-dimensional Medical Images of the Aorta

Bayat, Sharareh 06 May 2014 (has links)
Three-dimensional (3-D) medical imaging creates notable opportunities as input toward engineering analyses, whether for basic understanding of the normal function or patho-physiology of an organ, or for the simulation of virtual surgical procedures. These analyses most often require finite element (FE) models to be constructed from patient-specific 3-D medical images. However, creation of such models can be extremely labor-intensive; in addition, image processing and mesh generation are often operator-dependent, lack robustness and may be of suboptimal quality. Focusing on the human aorta, the goal of the present work is to create a fast and robust methodology for quadrilateral surface and hexahedral volume meshing from 3-D medical images with minimal user input. By making use of the segmentation capabilities of the 3-D gradient vector flow field combined with original ray-tracing and orientation control algorithms, we will demonstrate that it is possible to incrementally grow a structured quadrilateral surface mesh of the inner wall of the aorta. The process does not only require minimal input from the user, it is also robust and very fast compared to existing methods; it effectively combines segmentation and meshing into one single effort. After successfully testing the methodology and measuring the quality of the meshes produced by it from synthetic as well as real medical image datasets, we will make use of the surface mesh of the inner aortic wall to derive hexahedral meshes of the aortic wall thickness and of the fluid domain inside the aorta. We will finally outline a tentative approach to merge several structured meshes to process the main branches of the aorta.
140

Finite Element Analysis Of Composite Laminates Subjected To Axial &amp / Transverse Loading

Baskin, Cem Ismail 01 June 2004 (has links) (PDF)
This thesis focuses on the investigation of behavior of thick and moderately thick laminates under transverse and horizontal loading for different boundary conditions and configurations. An efficient finite element solution is proposed for analyzing composite laminates. Based on a combination of composite theory and 3-D Elasticity Theory, a 3-D finite element program is developed in MATLAB for calculating the stresses, strains and deformations of composite laminates under transverse and/or horizontal loading for different boundary conditions. The applicability of the formulation to analysis of laminated rubber bearings is also examined in this study. Since it is very important to calculate the correct stress state when developing models for composite behavior, the 3-D Elasticity Theory is used in this research. Numerical results are presented for various problems with different lamination schemes, loading and boundary conditions. In order to verify the analysis and the numerical calculations, numerical solutions obtained in this study are compared with available closed form solutions in the literature, experiment results and a commercial finite element program, namely ANSYS. The results obtained using the present finite element is found to be in acceptable and good agreement with the closed form solutions in the literature for thick and moderately thick rectangular and square plates.

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