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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.
11

Data-driven human body morphing

Zhang, Xiao 01 November 2005 (has links)
This thesis presents an efficient and biologically informed 3D human body morphing technique through data-driven alteration of standardized 3D models. The anthropometric data is derived from a large empirical database and processed using principal component analysis (PCA). Although techniques using PCA are relatively commonplace in computer graphics, they are mainly used for scientific visualizations and animation. Here we focus on uncovering the underlying mathematical structure of anthropometric data and using it to build an intuitive interface that allows the interactive manipulation of body shape within the normal range of human variation. We achieve weight/gender based body morphing by using PCA. First we calculate the principal vector space of the original data. The data then are transformed into a new orthogonal multidimensional space. Next, we reduce the dimension of the data by only keeping the components of the most significant principal vectors. We then fit a curve through the original data points and are able to generate a new human body shape by inversely transforming the data from principal vector space back to the original measuring data space. Finally, we sort the original data by the body weight, calculating males and females separately. This enables us to use weight and gender as two intuitive controls for body morphing. The Deformer program is implemented using the programming language C++ with OPENGL and FLTK API. 3D and human body models are created using Alias MayaTm.
12

Image morphing based on compatible triangulation and mesh interpolation

余康煒, Yue, Hong-wai. January 1999 (has links)
published_or_final_version / Computer Science and Information Systems / Master / Master of Philosophy
13

Shape Optimization and Modular Discretization for the Development of a Morphing Wingtip

Morley, Joshua 22 November 2012 (has links)
Better knowledge in the areas of aerodynamics and optimization has allowed designers to develop efficient wingtip structures in recent years. However, the requirements faced by wingtip devices can be considerably different amongst an aircraft’s flight regimes. Traditional static wingtip devices are then a compromise between conflicting requirements, resulting in less than optimal performance within each regime. Alternatively, a morphing wingtip can reconfigure leading to improved performance over a range of dissimilar flight conditions. Developed within this thesis, is a modular morphing wingtip concept that centers on the use of variable geometry truss mechanisms to permit morphing. A conceptual design framework is established to aid in the development of the concept. The framework uses a metaheuristic optimization procedure to determine optimal continuous wingtip configurations. The configurations are then discretized for the modular concept. The functionality of the framework is demonstrated through a design study on a hypothetical wing/winglet within the thesis.
14

Shape Optimization and Modular Discretization for the Development of a Morphing Wingtip

Morley, Joshua 22 November 2012 (has links)
Better knowledge in the areas of aerodynamics and optimization has allowed designers to develop efficient wingtip structures in recent years. However, the requirements faced by wingtip devices can be considerably different amongst an aircraft’s flight regimes. Traditional static wingtip devices are then a compromise between conflicting requirements, resulting in less than optimal performance within each regime. Alternatively, a morphing wingtip can reconfigure leading to improved performance over a range of dissimilar flight conditions. Developed within this thesis, is a modular morphing wingtip concept that centers on the use of variable geometry truss mechanisms to permit morphing. A conceptual design framework is established to aid in the development of the concept. The framework uses a metaheuristic optimization procedure to determine optimal continuous wingtip configurations. The configurations are then discretized for the modular concept. The functionality of the framework is demonstrated through a design study on a hypothetical wing/winglet within the thesis.
15

Variable Geometry Scramjet Combustor Cavity Multi-Dimensional Treatise for Performance Analysis

Sorensen, Andrew Liam 02 November 2021 (has links)
The abilities of Scramjets and Ramjets, in their respective operating ranges, are partially bridged by dual-mode Scramjets. The limitations of operation are due to making a static motor that is designed to function in both modes resulting in low and high speed restrictions. This study covers the analysis into the ability of morphing the combustor in a Scramjet to allow for expanded operational capacities through simple mechanisms. Through the restriction and expansion of combustor cavity volume, operational capabilities of the engine can, therefore, be modified to best match scenario requirements. Due to the engine's ability to match a wide variety of scenarios the limitations seen in that of the dual-mode Scramjet are avoided through the usage of a morphing combustor. From initial findings using the quasi-1D Canonical REactor Scramjet Simulation (CReSS) solver, progress was made to confirm results through the usage of Computational Fluid Dynamics (CFD). Prior analysis of the momentum balance between stages two and four of the simulated Scramjet engines, the results showed that the variable geometry matched or outperformed the baseline HiFiRE geometry. The analysis revealed points of Mach and altitude where certain combustor volumes demonstrated greater performance. This greater performance is only gained by the ability to tune the engine in flight to react to external factors as there is no dominant geometry for a given range of Machs and altitudes. This tuning allows for the usage of performance mapping to extract the greatest performance possible over a variety of conditions. Further, it allows for the project to be continuously expanded into mapping appropriate reactions to other initial conditions and stimuli. Using CFD modeling to perform a parametric study on the prior work allows for finer control and analysis of said initial conditions and the resulting flow paths in the variety of tested combustor volumes. From this a discussion is made in regards to the effectiveness of the prior CReSS based analysis of the novel approach. / Master of Science / The abilities of Scramjets and Ramjets (engines which contain no moving parts as the compression of the incoming air is accomplished by the speed at which they operate with the separating factor being that the scramjets internal flow does not go below supersonic speeds), in their respective operating ranges, are partially bridged by dual-mode Scramjets. Dual-mode Scramjets are scramjets which can function with both sub- and super-sonic internal flow speeds. This being below or above Mach 1 (343 m/s, 767.3 mph) respectively. The limitations of operation are due to making a static motor where the geometry does not change that is designed to function in both modes resulting in low and high speed restrictions. This study continues the analysis into the ability of morphing the combustor, the volume in which the air fuel mixture combusts, in a Scramjet to allow for expanded operational capacities through simple mechanisms. Through the restriction and expansion of combustor volume, operational capabilities of the engine can, therefore, be modified to best match scenario requirements. Due to the engine's ability to match a wide variety of scenarios the limitations seen in that of the dual-mode Scramjet are avoided through the usage of a morphing combustor where morphing in this case is a simple volume change equivalent to that of a slide whistle. From initial findings using the quasi-1D Canonical REactor Scramjet Simulation (CReSS) solver, progress was made to confirm results through the usage of Computational Fluid Dynamics (CFD). Prior analysis of the momentum balance between stages two and four of the simulated Scramjet engines, the results showed that the variable geometry matched or outperformed the baseline HiFiRE geometry. The analysis revealed points of Mach and altitude where certain combustor volumes demonstrated greater performance. This greater performance is only gained by the ability to tune the engine in flight to react to external factors as there is no dominant geometry for a given range of Machs and altitudes. This tuning allows for the usage of performance mapping to extract the greatest performance possible over a variety of conditions. Further, it allows for the project to be continuously expanded into mapping appropriate reactions to other initial conditions and stimuli. Using CFD modeling to perform a parametric study on the prior work allows for finer control and analysis of said initial conditions and the resulting flow paths in the variety of tested combustor volumes. From this a discussion is made in regards to the effectiveness of the prior CReSS based analysis of the novel approach.
16

Analysis and Design of a Morphing Wing Tip using Multicellular Flexible Matrix Composite Adaptive Skins

Hinshaw, Tyler 10 August 2009 (has links)
The material presented in this thesis uses concepts of the finite element and doublet panel methods to develop a structural-aerodynamic coupled mathematical model for the analysis of a morphing wing tip composed of smart materials. Much research is currently being performed within many facets of engineering on the use of smart or intelligent materials. Examples of the beneficial characteristics of smart materials might include altering a structure's mechanical properties, controlling its dynamic response(s) and sensing flaws that might progressively become detrimental to the structure. This thesis describes a bio-inspired adaptive structure that will be used in morphing an aircraft's wing tip. The actuation system is derived from individual flexible matrix composite tube actuators embedded in a matrix medium that when pressurized, radical structural shape change is possible. A driving force behind this research, as with any morphing wing related studies, is to expand the limitations of an aircraft's mission, usually constrained by the wing design. Rather than deploying current methods of achieving certain flight characteristics, changing the shape of a wing greatly increases the flight envelope. This thesis gives some insight as to the structural capability and limitations using current numerical methods to model a morphing wing in a flow. / Master of Science
17

Spatially Targeted Activation of a SMP

Puttmann, John Paul 05 June 2018 (has links)
No description available.
18

Image-Based View Synthesis

Avidan, Shai, Evgeniou, Theodoros, Shashua, Amnon, Poggio, Tomaso 01 January 1997 (has links)
We present a new method for rendering novel images of flexible 3D objects from a small number of example images in correspondence. The strength of the method is the ability to synthesize images whose viewing position is significantly far away from the viewing cone of the example images ("view extrapolation"), yet without ever modeling the 3D structure of the scene. The method relies on synthesizing a chain of "trilinear tensors" that governs the warping function from the example images to the novel image, together with a multi-dimensional interpolation function that synthesizes the non-rigid motions of the viewed object from the virtual camera position. We show that two closely spaced example images alone are sufficient in practice to synthesize a significant viewing cone, thus demonstrating the ability of representing an object by a relatively small number of model images --- for the purpose of cheap and fast viewers that can run on standard hardware.
19

Pixel-level Image Fusion Algorithms for Multi-camera Imaging System

Zheng, Sicong 01 December 2010 (has links)
This thesis work is motivated by the potential and promise of image fusion technologies in the multi sensor image fusion system and applications. With specific focus on pixel level image fusion, the process after the image registration is processed, we develop graphic user interface for multi-sensor image fusion software using Microsoft visual studio and Microsoft Foundation Class library. In this thesis, we proposed and presented some image fusion algorithms with low computational cost, based upon spatial mixture analysis. The segment weighted average image fusion combines several low spatial resolution data source from different sensors to create high resolution and large size of fused image. This research includes developing a segment-based step, based upon stepwise divide and combine process. In the second stage of the process, the linear interpolation optimization is used to sharpen the image resolution. Implementation of these image fusion algorithms are completed based on the graphic user interface we developed. Multiple sensor image fusion is easily accommodated by the algorithm, and the results are demonstrated at multiple scales. By using quantitative estimation such as mutual information, we obtain the experiment quantifiable results. We also use the image morphing technique to generate fused image sequence, to simulate the results of image fusion. While deploying our pixel level image fusion algorithm approaches, we observe several challenges from the popular image fusion methods. While high computational cost and complex processing steps of image fusion algorithms provide accurate fused results, they also makes it hard to become deployed in system and applications that require real-time feedback, high flexibility and low computation ability
20

Miniature Hourglass Shaped Actuator Geometry Study Using A Finite Element Simulation

Elwell, Roston Clement 2010 May 1900 (has links)
This project investigated a miniature, hourglass-shaped actuator (MHA) and how its geometry affects performance. A custom, self-contained, finite-element simulation code predicts how each MHA deforms when pressurized internally. This analysis describes the MHA geometry's effects on four characteristics: a) work density b) mechanical advantage, c) work advantage and d) percent elongation. The first three characteristics are compared to a traditional actuator operating at the same pressure and elongation. A finite-element modeling code was tailored to study the MHA at 5 MPa internal pressure when 1) MHA height and side-wall thickness are constant and side-wall arc length varies; 2) MHA side-wall arc length and thickness are constant and the height varies; and 3) MHA side-wall thickness varies while height and side-wall arc length are fixed. Case 3 was studied using the MHA geometry with the highest work density found in either condition 1 or 2. Peak mechanical advantage, 6.47, occurs in a constant height MHA-Case 1-when the side-wall arc length is shortest. Highest elongation, 8.67%, occurs in the Case 1 MHA with the longest side-wall arc length. Finally, under Case 3, work density reaches 0.434 MJ/m3 when the side-wall thickness is 1.9 mm. The MHA has potential for active structures because its work density is high-higher than traditional actuators with the same elongation. Their small elongations limit their use; however, much work remains to determine how MHAs might be arranged in a useful array. Never the less, morphing airfoils and other active structures might benefit from embedded MHAs.

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