An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries from the heart and brain. Biodegradable stent-assisted coiling is expected to be the ideal treatment of wide-neck complex aneurysms. A number of biodegradable stents are promising, but also with issues and/or several limitations to be addressed. From the design point of view, biodegradable stents are typically designed without structure optimization. The drawbacks of these stents often cause weaker mechanical properties than native arterial vessels. From the fabrication point of view, the conventional methods of the fabricating stent are time-consuming and expensive, and also lack precise control over the stent microstructure. As an emerging fabrication technique, dispensing-based rapid prototyping (DBRP) allows for more accurate control over the scaffold microstructure, thus facilitating the fabrication of stents as designed. This thesis is aimed at developing methods for fabrication and optimal design of biodegradable stents for treating aneurysms. Firstly, a method was developed to fabricate biodegradable stents by using the DBRP technique. Then, a compression test was carried out to characterize the radial deformation of the stents fabricated. The results illustrated the stent with a zigzag structure has a higher radial stiffness than the one with a coil structure. On this basis, the stent with a zigzag structure was chosen to develop a finite element model for simulating the real compression tests. The result showed the finite element model of biodegradable stents is acceptable within a range of radial deformation around 20%. Furthermore, an optimization of the zigzag structure was performed with ANSYS DesignXplorer, and the results indicated that the total deformation could be decreased by 35% by optimizing the structure parameters, which would represent a significant advance of the radial stiffness of biodegradable stents. Finally, the optimized stent was used to investigate its deformation in a blood vessel. The deformation is found to be 0.25 mm in the simulation, and the rigidity of biodegradable stents is 7.22%, which is able to support the blood vessel all. It is illustrated that the finite element analysis indeed helps in designing stents with new structures and therefore improved mechanical properties.

The objective of this research is to achieve high-efficiency, low-cost, commercial-ready, screen-printed Silicon (Si) solar cells by reducing material costs and raising cell efficiencies. Two specific solutions to material cost reduction are implemented in this thesis. The first one is low to medium concentrator (2-20 suns) Si solar cells. By using some optics to concentrate sunlight, the same amount of output power can be achieved with cell area reduced by a factor equal to the concentration ratio. Since the cost of optics is less than the semiconductor material, electricity price from the concentrator photovoltaics (PV) system is therefore reduced. The second solution is the use of epitaxially grown Si (epi-Si) wafers. This epi-Si technology bypasses three costly process steps (the need for polycrystalline silicon feedstock, ingot growth, and wafer slicing) compared to the traditional Si wafer technology and therefore reduces the material cost by up to 50% in a finished PV module. In addition, high efficiency Si solar cells with reduced metal contact recombination are studied and modeled by implementation of passivated contacts composed of tunnel oxide, n+ polycrystalline Si and metal on top of n-type Si absorber to reduce the cost ($/Wp) of PV module.

This dissertation presents the investigation of several additive manufactured components in RF and THz frequency, as well as the applications of gradient index lens based direction of arrival (DOA) estimation system and broadband electronically beam scanning system. Also, a polymer matrix composite method to achieve artificially controlled effective dielectric properties for 3D printing material is studied. Moreover, the characterization of carbon based nano-materials at microwave and THz frequency, photoconductive antenna array based Terahertz time-domain spectroscopy (THz-TDS) near field imaging system, and a compressive sensing based microwave imaging system is discussed in this dissertation. First, the design, fabrication and characterization of several 3D printed components in microwave and THz frequency are presented. These components include 3D printed broadband Luneburg lens, 3D printed patch antenna, 3D printed multilayer microstrip line structure with vertical transition, THz all-dielectric EMXT waveguide to planar microstrip transition structure and 3D printed dielectric reflectarrays. Second, the additive manufactured 3D Luneburg Lens is employed for DOA estimation application. Using the special property of a Luneburg lens that every point on the surface of the Lens is the focal point of a plane wave incident from the opposite side, 36 detectors are mounted around the surface of the lens to estimate the direction of arrival (DOA) of a microwave signal. The direction finding results using a correlation algorithm show that the averaged error is smaller than 1º for all 360 degree incident angles. Third, a novel broadband electronic scanning system based on Luneburg lens phased array structure is reported. The radiation elements of the phased array are mounted around the surface of a Luneburg lens. By controlling the phase and amplitude of only a few adjacent elements, electronic beam scanning with various radiation patterns can be easily achieved. Compared to conventional phased array systems, this Luneburg lens based phased array structure has a broadband working frequency and has no scan angle coverage limit. Because of the symmetry of Luneburg lens, no beam shape variation would occur for the entire scanning range. Moreover, this alternative phased array requires much less system complexity to achieve a highly directional beam. This reduction in system complexity allows the electronic scanning system to be built at much lower cost than traditional phased arrays. Fourth, the characterization of carbon based (Graphene and carbon nanotube) thin films on different substrates via Terahertz time-domain spectroscopy are presented in this dissertation. The substrate permittivity is first characterized. The film under test is then treated as a surface boundary condition between the substrate and air. Using the uniform field approximation, the electromagnetic properties of the film can be extracted. To improve accuracy, precise thickness of sample substrate is calculated through an iteration process in both dielectric constant extraction and surface conductivity extraction. Uncertainty analysis of the measured thin film properties is performed. Fifth, a coded transmitter TDS near field imaging system by employing photoconductive antenna (PCA) array is reported. Silicon lens array is used to couple and focus the femto-second laser onto each PCA. By varying the bias state of each PCA element, the ON/OFF state or power level for different PCAs can be controlled independently. The sample object is placed 10m away from the PCA array to measure the THz near field image. A Hadamard matrix is applied to code the 2x2 antenna array to improve the SNR. Measured results clearly indicate an improved SNR compared to individual antenna measurement. In addition, Multiphysics COMSOL and a FDTD algorithm combined with HFSS time domain simulation is used to model the physics of TDS photoconductive antenna and optimize the performance of TDS transmitter and receiver. Good agreement between simulation and experiment is obtained. Finally, a design of a Principal Component Analysis (PCA) based microwave compressive sensing system using reconfigurable array is presented. An iterative beam synthesis process is used to realize the required radiation patterns obtained from PCA. A human body scanning system is studied as an example to investigate the compressive sensing performance using PCA generated radiation patterns. Optical images are used as surrogates for the RF images in implementation of the training PCA dictionary. Compared to random patterns based compressive sensing system, this PCA based compressive sensing system requires fewer numbers of measurements to achieve the same performance.

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A Portrait of the Artist as a Young Man is viewed traditionally by many critics and scholars alike more or less, if not entirely, as Joyce’s autobiographical novel. The identity of the narrator and his relationship to the focalizer and the narrative text are aspects that have thus not been sufficiently examined and explored. An analysis of the passage when Stephen clarifies to himself his relationship to words which makes possible the revelation of his calling as an artist will reveal the intimacy of the narrator and Stephen, indicating they are one and the same. But it will also disclose the structure of the narration of Portrait to be the result of Stephen’s very discovery of the meaning of words to him. And the view of Stephen as a narrator, as well as the main focalizer, turns Portrait into a work of fictional autobiography. His thoughts and contemplations monopolize the narration, granting him exclusive authority over the presentation of his story. Furthermore, the suggestion in the title of the novel that he is also the writer begs the question of reliability. Can Stephen’s story be trusted, or is Portrait a fabrication of his childhood in order to convince the world that he really was born to become an artist? The opening and ending of the novel suggest that the narrative is not “based on a true story” of Stephen’s life but instead that it is composed in the fantasy world which Stephen withdraws into as his meagre output does not meet his expectations. Thus Stephen writes his first novel entitled A Portrait with which he hopes to achieve the fame and receive the recognition he desires. But Stephen is still a struggling artist when the narrative finishes, hence the ambiguous ending as Stephen is the novel itself, its inconclusive narrative. Stephen’s A Portrait is a glorious act of self-creation.

The production of an efficient and low cost device has been the ultimate goal in the photovoltaic cell development. The fabrication and application of nanostructured materials in the field of energy conversion has been attracting a lot of attention. In this work, applications of surface plasmons (SPs) and photonic nanostructures to the field of energy conversion, specifically in the area of silicon solar cells and lanthanide energy upconversion (UC) luminescence applications were studied. Enhanced power conversion efficiency in bulk (single crystalline) silicon solar cells was demonstrated using an optimized mixture of the silver and gold nanoparticles (NPs) on the front of the cell to tackle the negative effect in the Au NPs plasmonic application. Then, a comparison of identically shaped metallic (Al, Au and Ag) and nonmetallic (SiO2) NPs integrated to the back contact of amorphous thin film silicon solar cells were investigated to solve a controversy issue in literature. The result indicates that parasitic absorption from metallic NPs might be a drawback to the SPs enhancement. A cost-effective fabrication of large area (5x5 cm2) honeycomb patterned transparent electrode for “folded” thin film solar cell application by combining the nanosphere lithography and electrodeposition were realized. Furthermore, the SPs enhanced tunable energy upconversion from NaYF4:Yb3+/Er3+ NPs in nanoslits were also demonstrated, our results shows that the relative red/green emission can be controlled by different plasmonic mode coupling. / Graduate / phwang@uvic.ca

SIGRADI 2010. XIV Congreso de la Sociedad Iberomaericana de Gráfica Digital, desarrollados los días 17, 18 y 19 de Noviembre del 2010. Bogotá, Colombia / Since 2008 the preference for using different programming methods (Rhinoscript) had been analyzed using blogs. Searching for answers to explain the negative tendency of this year (from 48,063 to 16,332), a second repository was created (Grasshopper) featuring interactive methods and techniques. It has been discovered that of the five geographic regions analyzed Latin America is the only one that preferred the interactive interface (18% over programming). This shows that we are still keeping a strong dependency on the use of stable and safe technologies over disruptive ones that proved to be more efficient in design and fabrication.

Latin American experiences are analyzed in order to identify adverse factors, describing the complexity of the implementation of a Fabrication Laboratory in the region. As a starting point we take the implementation done by groups of academics coming back to their origin countries, and others that after the implementation they were born or adapted to an academic supervision (Fab Lab MIT) or a technical and commercial one (Rhino FabLab). In the whole, the results allow to identify opportunities for the future.

Conference: 16th International Conference, CAAD Futures 2015 - "The next city". São Paulo, Brazil, July 8-10, 2015, At São Paulo, Brazil., Volume: Computer-Aided Architectural Design Futures. The Next City - New Technologies and the Future of the Built Environment ( Communications in Computer and Information Science, Volume 527 - 2015) / The present paper is a mapping study of digital fabrication laboratories in Latin America. It presents and discusses results from a survey with 31 universities’ fab labs, studios and independent initiatives in Latin America. The objective of this study is fourfold: firstly, to draw the cultural, social and economic context of implementation of digital fabrication laboratories in the region; secondly, to synthesize relevant data from correlations between organizational structures, facilities and technologies, activities, types of prototypes, uses and areas of application; thirdly, to draw a network of people and institutions, recovering connections and the genealogy of these fab labs; and fourthly, to present some fab labs that are intertwined with local questions. The results obtained indicate a complex “homo faber” network of initiatives that embraces academic investigations, architectural developments, industry applications, artistic propositions and actions in social processes.