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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.
1

Development of Uniform Artificial Soil Deposition Techniques on Glass and Photovoltaic Coupons

January 2016 (has links)
abstract: Soiling is one of the major environmental factors causing the negative performance of photovoltaic (PV) modules. Dust particles, air pollution particles, pollen, bird droppings and other industrial airborne particles are some natural sources that cause soiling. The thickness of soiling layer has a direct impact on the performance of PV modules. This phenomenon occurs over a period of time with many unpredictable environmental variables indicated above. This situation makes it difficult to calculate or predict the soiling effect on performance. The dust particles vary from one location to the other in terms of particle size, color and chemical composition. These properties influence the extent of performance (current) loss, spectral loss and adhesion of soil particles on the surface of the PV modules. To address this uncontrolled environmental issues, research institutes around the world have started designing indoor artificial soiling stations to deposit soil layers in various controlled environments using reference soil samples and/or soil samples collected from the surface of PV modules installed in the locations of interest. This thesis is part of a twin thesis. The first thesis (this thesis) authored by Shanmukha Mantha is related to the development of soiling stations and the second thesis authored by Darshan Choudhary is associated with the characterization of the soiled samples (glass coupons, one-cell PV coupons and multi-cell PV coupons). This thesis is associated with the development of three types of indoor artificial soiling deposition techniques replicating the outside environmental conditions to achieve required soil density, uniformity and other required properties. The three types of techniques are: gravity deposition method, dew deposition method, and humid deposition method. All the three techniques were applied on glass coupons, single-cell PV laminates containing monocrystalline silicon cells and multi-cell PV laminates containing polycrystalline silicon cells. The density and uniformity for each technique on all targets are determined. In this investigation, both reference soil sample (Arizona road dust, ISO 12103-1) and the soil samples collected from the surface of installed PV modules were used. All the three techniques are compared with each other to determine the best method for uniform deposition at varying thickness levels. The advantages, limitations and improvements made in each technique are discussed. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016
2

The Significance of the Depositional Microenvironment in the Decomposition of Dismembered Body Parts

Franicevic, Branka January 2018 (has links)
A scarcity of experimental studies covering the decomposition of dismembered body parts has created a gap in knowledge of the effect of dismemberment on the estimation of post-mortem interval (PMI) and their post-mortem history in a forensic context. The aim of this study was to record the decay of detached body parts in some depositional settings where they are likely to be disposed of: burial, wrapping and freezing. A series of controlled laboratory experiments was carried out using Sus scrofa body parts and pork belly, to understand how ambient temperature, soil moisture, and wrapping and freezing of body parts affected their decomposition. Rates of decay were subject to a higher temperature and soil moisture level in a burial microenvironment, with metabolic microbial activity confirming the results. Temperature was a predominant factor in the decay rates of wrapped body parts, with a raised ambient temperature causing even higher temperature in the wrapped microenvironment, resulting in accelerated decay rates. Freezing decelerated the decomposition of body parts, retarding microbial growth and activity and causing differential decomposition between body parts. Freezing demonstrated morphological changes in body parts specific to this microenvironment. Predominantly Gram-negative bacteria that may be associated with body microflora were involved in decomposition in all three microenvironments. Taphonomic, chemical and microbiological analyses carried out in this study have a potential for forensic application in the examination of dismembered remains that have been deposited in freezing and indoor settings. Further experiments are necessary to understand buried decomposition patterns in field conditions.

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