Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 44 for “"light attenuation"”.
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Effect of Crude Oil on Light Attenuation and the Resulting Impacts on Marine Microbial Phototrophs and Heterotrophs
… over the surface of the seawater which cause the attenuation of light passing through it. Then, we showed that crude oil preferentially attenuates the shorter wavelengths of photosynthetically active radiation. Therefore, we proposed that this change in the spectrum and reduction in light …
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Observations and modelling of the variability of the Solent-Southampton Water estuarine system
… flood. The temporal and spatial variability of light attenuation is also investigated.<br/>Turbidity is demonstrated to be the major contribution to light attenuation using a time-series of discrete data collected in 2001, 2002 and 2003. A typical seasonal cycle of the coefficient of light …
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Diatom Assemblages in Relation to Water-Depth Gradients in Eight Boreal Shield Lakes From Northwestern Ontario, Canada
… variables (e.g. DOC, TP) that are related to light attenuation. Deeper pelagic to benthic transitions occurred in lakes with the lowest DOC and TP (i.e. generally more light attenuation in lakes with higher concentrations of TP or DOC). Other findings included a decrease in species evenness …
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Phytoplankton Ecology in the Skidaway River Estuary
… such as salinity, nutrient concentration, and light availability strongly influence total phytoplankton biomass but less is known about their effects on species-level changes due to difficulties associated with identifying and enumerating individual taxa. Understanding taxon-specific shifts is …
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Seasonal and Spatial Variation in Leaf Area Index, Litter Production, and Light Levels in Myrica Cerifera,Shrub Thickets Across a Barrier Island Chronsequence
… index (LAI), litter production and understory light levels of Myrica cergera shrub thickets were assessed on Hog Island, Virginia to quantify spatial and seasonal variations in leaf area and light attenuation among four thickets representing a successional chronosequence and compare methods of …
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Evaluation and Mitigation of Industrial Fire Hazards
… large uncertainties involved when transforming light attenuation measurements into soot volume fraction. Simulations of tests according to the EN54 detector standard were also carried out. The agreement differed for different fuels. In addition, there is a problem with comparing light …
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Behavioral Responses of Rainbow Smelt to Sensory Deterrent Systems
… sound projector array (SPA) and (2) strobe lights as fish deterrents for avoidance and acclimation behavior of rainbow smelt; 3) to determine physical characteristics that affect light attenuation in Lake Oahe; and 4) to evaluate predator-prey interactions of rainbow smelt and zooplankton in …
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Fluorescent materials for short-wave infrared imaging
… in vivo. As the scattering and absorption of light through biological tissue impose significant restrictions on imaging penetration depth, acquisition speed, and spatial resolution, the development of novel optical imaging technologies has increasingly shifted toward the use of light of longer …
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Changes in climate and catchment processes over the middle and late Holocene in the boreal region of northeastern Ontario, Canada
… studies. This thesis also examines the role of light attenuation in structuring modern diatom assemblages within lakes. Diatoms collected from surface sediments in depth-gradient transects suggest that light attenuation is a strong driver of benthic-planktonic (B:P) assemblage separation …
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Mixing in axisymmetric gravity currents and volcanic conduits
… with distance downstream was measured using a light attenuation technique. Additional experiments were performed by injecting parcels of dye in different regions of the flow in order to visualise the motion of fluid in and surrounding the gravity current. Unlike currents introduced by the …
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Ecological effects of turbidity variations in and around dredging areas in the Port of Tauranga
Turbidity is the scattering of light in water bodies and is an important measurement for assessing water quality in coastal systems. Suspended particles in the water column can greatly impact on light penetration and measured turbidity levels. These suspended particles can originate from a range of …
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Optical and chemical properties of molten salt mixtures for use in high temperature power systems
… was the objective of this Thesis. The light attenuation coefficient of two reagent grade molten salt mixtures (KNO 3 - NaNO 3, 40- 60 wt% and NaCI-KCI, 50-50 wt%) was measured and characterized over the wavelength range 400nm- 800nm and for different operating temperature ranges: …
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Characterization of water-based liquid scintillator response to gammas and neutrons at varying scintillator-surfactant concentrations
… organic scintillator. Investigation into the light yield and light attenuation of this material is conducted, providing promising results. The scintillator pair PPO and POPOP serve as the primary and secondary fluor for the bulk scintillator, dissolved in Triton-X surfactant to fix the issue …
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Underwater Refractive Camera Calibration and 3D Scene Reconstruction
… vehicles equipped with waterproof camera-light systems. Despite prior research addressing related challenges, these tasks remain challenging due to two key issues: (1) geometric distortions caused by distance-dependent light refraction when the light rays travel through the housing …
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Non-invasive optical methodologies to evaluate and enhance Chlorella vulgaris biomass
… hydrogels with added scattering elements to aid light attenuation within the matrix. Cellulose microparticles served as broadband diffusive scatterers which were demonstrated to increase the light path throughout the hydrogel, and the resulting effect on biomass growth was shown to be improved in …
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Synthesis of Complex Plasmonic Nanostructures for Applications in Surface-Enhanced Raman Spectroscopy and Biomedicine
… for biomedical applications due to reduced light attenuation in soft tissue. In this section, I will describe how the nanostructures resulting from galvanic replacement reactions can be engineered by controlling the morphology of the Ag nanostructures used as templates or the metal salt(s) …
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Nondestructive investigation of soil moisture level using optical system
… multiclass ANN model, wherein measurement of light attenuation (from nondestructive system) was correlated with percent soil moisture (from destructive gold standard approach). Since there is a considerable overlap in the value of the measurables (for both soil types), this work employed ANN …
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Reflectance spectroscopy system for real time and non-invasive detection of transcutaneous bilirubin level
… verified validity of the predicted value using light attenuation data from TracePro for a single-layered skin model with varying bilirubin concentration. The results revealed some promising trends in estimated bilirubin concentration and considerably good accuracy with percent mean relative …
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Concentration and Size Distribution of Microparticles in the NGRIP Ice Core (Central Greenland) during the Last Glacial Period
… novel, optical detector which is based on laser light attenuation by individual particles. The device works on a flow-through basis, and together with sample preparation via continuous melting allows for very efficient analyses at high depth resolution. The presented work also covers the partial …
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