7 research outputs found
An Electric Model of Cracked Solar Cells Accounting for Distributed Damage Caused by Crack Interaction
No full textAbstractElectric models based on a distributed series resistance along the grid line can be used to predict the current through the thickness of the Silicon solar cell, as well as the current and the voltage along the grid line. In the presence of a crack intersecting a finger, a localized electrical resistance dependent on the crack opening has to be introduced in that intersection point. In the present study, a refinement of these electric models is proposed by introducing a sheet resistance dependent on the amount of damage induced by cracks in the surrounding material. The proposed model is successfully validated in reference to experimental data on mono-crystalline Silicon solar cells with cracks artificially created by Vickers indentation, providing an insight into the electric degradation mechanisms caused by crack interaction phenomena
Simulation of Spalling with a Non-planar Bi-layered Interface Due to the Reuse of the Substrate
No full textAbstractKerfless wafering techniques have the potential to reduce the cost of crystalline silicon (Si) in photovoltaics by saving material and production costs. Thermomechanical spallation from thick wafers with aluminium (Al) in the double function as stressor layer and contacting layer in the final solar cell is one attractive option. In principle this technique might allow to produce multiple thin film solar cells via thermo-mechanical exfoliation, which is essential to be ascertaining for the technique in an industrial context. The aim of this study concerns the feasibility to reuse the parental Si substrate in the presence of non-planar Si-Al interface originated by the first exfoliation. A numerical method based on the Finite Element Method (FEM) and Linear Elastic Fracture Mechanics (LEFM) is used to simulate the evolution of the non-planar Si-Al interface after successive exfoliations. We find a partial reduction in the amplitude of the transferred groove on the Si-Al interface for grooves having typical realistic dimension. The numerical results are confirmed by the reduction of the amplitude of the groove observed in the experimental tests. These results are promising for the repeated exfoliation from one substrate, inasmuch as the possible roughness on the parental substrate after the first use does not significantly affect the subsequent exfoliations
Spongelike porous ZnO photoanodes for highly efficient Dye Sensitized Solar Cells
No full textWe propose a 3D branched ZnO nanostructure for the fabrication of highly efficient dye-sensitized solar cell photoanodes. A coral-shaped structured Zn layer was deposited by radio frequency magnetron sputtering at room temperature onto fluorine-doped tin oxide/glass sheets and then thermally oxidized in ambient atmosphere, obtaining a high-density branched ZnO film. The porous structure provides a large surface area, and, as a consequence, a high number of adsorption sites, and the size and spacing of the nanostructures (on the order of the exciton diffusion length) are optimal for good electron collection efficiency. The proposed synthesis technique is simple and scalable and the reproducibility of the growth results was tested. The crystalline phase of the film was investigated, evidencing the complete oxidation and the formation of a pure wurtzite crystalline structure. ZnO-based solar harvesters were fabricated in a microfluidic architecture, using conventional sensitizer and electrolyte. The dependence of the cell efficiency on dye incubation time and film thickness was studied with I-V electrical characterization and electrochemical impedance spectroscopy. The obtained conversion efficiency values, with a maximum value of 4.83%, confirm the highly promising properties of this material for the implementation in dye-sensitized solar cell photoanodes
A content analysis of sponsor representation across professional sport websites : extension of attribute typology
No full textThe sport industry has identified the importance of using the internet as a tool that can benefit the organisation. Much like the purpose of entering into sponsorship of sporting events, corporate partners are also attracted to the opportunities that professional sport team websites offer to fulfil similar objectives. The major purpose of this research is to explore the various ways in which sponsor logos are represented across professional sport websites and to extend previous advertising research, specifically the work developing advertising attribute typologies. The subjects for this research are professional sport websites and a qualitative approach is adopted with a content analysis as the main method of analysis used. To ensure reliability and validity within the coding instruments used, percentage agreement and Cohen’s kappa were adopted as indexes to verify this. The findings show sponsors’ logos exist on most professional sport websites and are represented in a variety of ways. Furthermore, a typology for sponsor representation and location across sport websites has been established to present a reliable foundation for future research in the area of consumer attitudes, behaviour and response towards sponsors and their presence on sport websites.<br
SIRIO : Integrated Forest Firesmonitoring, detection and decision supportsystem with low cost commercial sensorssuited for complex orography
No full textForest Fires in our society cause a lot of damage, in particular regarding the economic and environmental landscape. In order to monitor a large portion of territory automatically, with a good cost/performances trade-off, it is necessary to develop new early warning systems. We propose a ground-based system with modular architecture, equipped with low cost commercial sensor. The idea is to develop the software able to manage the forest fires monitoring. The technique is based on Static and Dynamic analysis of chromatic changes between images, tailored for our case of study in a large scale monitoring of vegetation and using different sensors to reduce or eliminate the false alarm rate. Concerning the image geo-referencing tool, the present work describes an innovative projective geo-referencing algorithm able to geo-reference complex orography regions using fixed ground station images. Besides, it does not need the collection of Ground Control Points, which is a very hard task in complex orography environments. In order to make a user oriented product and to help the operator during extinguishing activities, a decision support tool has been developed as well. This work presents the results of one year monitoring campaign conducted in cooperation with the Civil Protection Offices in Sanremo (IM), Ital
Investigation of RNA-mediated pathogenic pathways in a Drosophila model of expanded repeat disease.
No full textExpansion of a repeat sequence beyond a pathogenic range has been identified as the cause of a group of neurodegenerative diseases known as the expanded repeat diseases. Disease-associated repeat tracts have been found both within the coding region of genes, such as the CAG repeat coding for polyglutamine, or within noncoding regions. Despite the identification of the mutation involved in these diseases, the mechanism by which this type of mutation leads to cell death remains unclear. There is a substantial amount of evidence to suggest that RNA-mediated toxicity plays a role in pathogenesis of both the polyglutamine diseases and the untranslated dominant expanded repeat diseases. A common feature of the expanded repeats involved in each of these diseases is the ability of the repeat-containing RNA to form a hairpin secondary structure and therefore it has been predicted that similar mechanisms may be responsible for initiating cellular dysfunction and death in each case. This study uses a Drosophila model to investigate the intrinsic, RNA-mediated toxicity of three repeat sequences (CUG, CAG and AUUCU) associated with
degeneration in human disease. Using a combination of hypothesis-driven and nonbiased approaches, early changes elicited in response to neuronal expression of these expanded repeat tracts have been investigated. A hypothesis of a role for RNA editing in CAG repeat pathogenesis was explored using this Drosophila model. Microarray and proteomic approaches were also utilised to identify pathways which are perturbed by the expression of these repeat sequences. The results described in this thesis demonstrate a degree of sequence- and context-independent toxicity of expanded repeat RNA in this model, suggesting that this kind of effect may also be a component of pathogenesis in the disease situation. Pathways commonly perturbed in response to expression of these RNA species may represent particularly valuable therapeutic targets, since preventing this type of effect could provide positive outcomes in a number of diseases.Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 201
