Effect of Chemically Modified Banana Fibers on the Mechanical Properties of Poly-Dimethyl-Siloxane-Based Composites

The study presents the mechanical properties of polymer-based composites reinforced with chemically modified banana fibers, by alkalization in different concentrations of sodium hydroxide (NaOH). The fiber weight fraction has a great effect on the mechanical properties of the composites. Stiff composites were obtained at 6 wt% fiber fractions with Young’s modulus of 254.00 ±12.70 MPa. Moreover, the yield strength was 35.70 ±1.79 MPa at 6 wt% fiber fractions. However, the ultimate tensile strength (UTS) and toughness of the composites were obtained at 5 wt% fiber fractions. Statistical analyses were used to ascertain the significant different on the mechanical properties of the fibers and composites. The implication of the results is then discussed for potential applications of PDMS-based composites reinforced with chemically modified banana fibers

Light Trapping in Plasmonic Solar Cells

Subwavelength nanostructures enable the manipulation and molding of light in nanoscale dimensions. By controlling and designing the complex dielectric function and nanoscale geometry we can affect the coupling of light into specific active materials and tune macroscale properties such as reflection, transmission, and absorption. Most solar cell systems face a trade-off with decreasing semiconductor thickness: reducing the semiconductor volume increases open circuit voltages, but also decreases the absorp- tion and thus the photocurrent. Light trapping is particularly critical for thin-film amorphous Si (a-Si:H) solar cells, which must be made less than optically thick to enable complete carrier collection. By enhancing absorption in a given semiconductor volume, we can achieve high efficiency devices with less than 100 nm of active region. In this thesis we explore the use of designed plasmonic nanostructures to couple incident sunlight into localized resonant modes and propagating waveguide modes of an ultrathin semiconductor for enhanced solar-to-electricity conversion. We begin by developing computational tools to analyze incoupling from sunlight to guided modes across the solar spectrum and a range of incident angles. We then show the potential of this method to result in absorption enhancements beyond the limits for thick film solar cells. The second part of this thesis describes the integration of plasmonic nanos- tructures with a-Si:H solar cells, showing that designed nanostructures can lead to enhanced photocurrent over randomly textured light trapping surfaces, and develops a computational model to accurately simulate the absorption in these structures. The final chapter discusses the fabrication of a high-efficiency (9.5%) solar cell with a less than 100 nm absorber layer and broadband, angle isotropic photocurrent enhance- ment. Moreover, we discuss general design rules where light trapping nanopatterns are defined by their spatial coherence spectral density.</p

Procedural content generation in gaming via evolutionary algorithms

Dissertation presented as the partial requirement for obtaining a Master's degree in Data Science and Advanced Analytics, specialization in Data ScienceThe aim of this thesis is to investigate the possibility of creating content using the Genetic Algorithms. To this end a simple system of interconnected algorithms were developed using concepts from Role Playing Games, specifically Dungeons and Dragons to create game content as characters, quests, and encounters. To be able to produce context, subsystems of map, character, quest, and encounter generators were created. These systems or engines not only define the game space to be populated, but they also provide each other input to create maps, quests, locations, animals, and events that are sensible and coherent. Randomness of the generation was essential as such a variety of noise maps and random number generation were added to every engine in the system. Layered or singular noise maps allowed for logical assumptions to be made, like seeing camels in a location with no rain and high temperatures. With the base truth coming from a random noise map such as danger, civilisation, faction etc., each system built on top of each other can get more complex. There are several Genetic Algorithms with custom operators within the system. These algorithms take their inputs and individuals from the respective engines and tie them all to each other through their physical coordinates in the gaming space. The most impactful part of these algorithms is the Fitness Functions defined with concepts from literature or CGI. The proposed system can populate a game space with elements of desired attributes given the constraints. The output produced consists of coherently tied story beats with some attributes already set. Even in this simple level, this can allow not only game designers but anyone who wants to build any kind of fictional work

Novel light trapping techniques for silicon solar cells.

Thin-film silicon photovoltaic (PV) solar cells have attracted significant interest for decades due to the increasing demand for clean and sustainable energy resources. Further reduction of the cost of materials and manufacturing processes is required to reach the grid parity where the cost of electricity from solar PV cells is equal to the cost of other nonrenewable resources. Crystalline and thin-film silicon solar cells are anticipated to continue to be one of the dominant solar PV cell technologies. This anticipation is due to the abundance of silicon and the successful history of a continuous drop in cost in silicon-based PV cells. In this thesis, several designs were investigated to enhance absorption of sunlight in the active layers of silicon-based solar cells. In the first design, a plasmonic enhancement to silicon solar cells using (Titanium nitride) TiN as a replacement for silver is studied. In the second, a new design for tandem thin-film silicon solar cells is proposed using a periodic layer between the two subcells. Finally, a low-cost easily fabricated nanocone facial textures is proposed and showed promising experimental and simulation antireflection properties. 3D electromagnetic analysis was performed using finite difference time domain (FDTD) simulations to all structures and 3D Device simulations were additionally used to study the tandem cell structure. These contributions which were published are believed to contribute towards achieving high efficiency and cost-effective solar cells

Non-parametric synthesis of laminar volumetric texture

International audienceThe goal of this paper is to evaluate several extensions of Wei and Levoy's algorithm for the synthesis of laminar volumetric textures constrained only by a single 2D sample. Hence, we shall also review in a unified form the improved algorithm proposed by Kopf et al. and the particular histogram matching approach of Chen and Wang. Developing a genuine quantitative study we are able to compare the performances of these algorithms that we have applied to the synthesis of volumetric structures of dense carbons. The 2D samples are lattice fringe images obtained by high resolution transmission electronic microscopy (HRTEM)

06221 Abstracts Collection -- Computational Aestethics in Graphics, Visualization and Imaging

From 28.05.06 to 02.06.06, the Dagstuhl Seminar 06221 ``Computational Aesthetics in Graphics, Visualization and Imaging\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

State of the Art in Example-based Texture Synthesis

International audienceRecent years have witnessed significant progress in example-based texture synthesis algorithms. Given an example texture, these methods produce a larger texture that is tailored to the user's needs. In this state-of-the-art report, we aim to achieve three goals: (1) provide a tutorial that is easy to follow for readers who are not already familiar with the subject, (2) make a comprehensive survey and comparisons of different methods, and (3) sketch a vision for future work that can help motivate and guide readers that are interested in texture synthesis research. We cover fundamental algorithms as well as extensions and applications of texture synthesis

A journey in a procedural volume Optimization and filtering of Perlin noise

National audiencePerlin noise is the most widely used tool in procedural texture synthesis. It is a simple and fast method to enhance the quantity of detail or to render natural materials with no use of storage resources. However, this technique is very sensitive to aliasing artifacts, especially when composed with shape and color functions. Moreover, it is computationally intensive and can become slow, especially when generating procedural volumes of density in real time. This study aims at analyzing Perlin noise properties in order to control the apparition of artifacts and optimize the computational cost. We present a method for computing a maximum and minimum frequency threshold per noise component, we propose an idea to handle the case of non linear transforms of the noise, and show an optimization method for volume generation

Solar canvas:Nanoscale light management for ultra-thin, semi-transparent, and colourful solar cells

This thesis provides new solutions for integrable PV by exploiting nanophotonic principles in nanoscale architectures. It shows a high degree of control over the absorption/transmission spectrum by using optical waveguiding in either nanowires (NW) or thin films. In Chapter 2, we focus on understanding the optical properties of vertically standing semiconductor NWs as promising building blocks for next generation photonics and photovoltaics. In Chapter 3, we explore in detail the potential of semiconductor NW-based solar cells as a powerful and tunable-in-design approach for wavelength-selective semi-transparent solar cells for BIPV. Optical simulations and experimental demonstration of PMDS-embedded NW arrays confirm that by changing diameter and periodicity one can engineer the absorption and transmission spectra of the NW array to provide a broad range of bright colours, semi-transparency and high PV performance. Chapter 4 focuses on ultrathin, high efficiency and flexible Si solar cells as another photonic-based solution to minimize the compromise of high conversion efficiency for aesthetics in solar cells. Here we present a new family of surface texturing, based on correlated disordered hyperuniform patterns, capable of manipulating scattering spectrum of the incident light to be efficiently coupled into the silicon slab optical modes. We experimentally demonstrate 66.5% solar light absorption in free-standing 1um c-Si layers by using these nanotextures. Finally, in Chapter 5, we combine the unique light waveguiding and absorption in vertically standing NWs with k-space engineering given by their arrangement into arrays to increase absorption in an ultra-thin tandem cell beyond the bulk limits. The photonic and design concepts presented here combined with highly-performing PV materials make the intersection between high-efficiency, flexibility, colour-tunability and transparency closer to reality