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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.
41

A shape-based image classification and identification system for digital holograms of marine particles and plankton

Liu, Zonghua January 2018 (has links)
The objective of this project is to develop a shape-based image analysis system, which allows classification and identification of holographic images of marine particles and plankton recorded by an underwater digital holographic camera. In order to achieve this goal, the first step is to extract shape regions of objects from images and to describe the regions by polygonal boundaries. After extraction of the polygonal boundary curve of an object, affine-invariant curve normalisation is implemented on the curve to reduce the influence of object shape deformations on object identification and classification. Six numeric features are then selected to describe shape properties of an object. Before these six shape features are used as a numeric interpretation of an object for image analysis, some processing of them is necessary, consisting of selecting the number of items in each feature and rescaling the selected feature vectors. Afterwards, Gaussian rescaling is adopted to rescale the feature data. Lastly, a shape-based image classification and identification system is built. The system contains two components: semi-automatic image classification (imCLASS) and automatic image identification (imIDENT). In imCLASS, an image retrieval method based on the support vector machine with a feedback mechanism has been developed. The function of imCLASS is to classify given images into different folders with the corresponding labels from the user. These labelled folders can be used to train the artificial neural network in imIDENT. A set of analyses of effects of the proposed methods in the process chain on image analysis are carried out. The whole performance of the system for classifying and identifying marine particles and plankton is also evaluated in terms of the time-cost and accuracy performance. In the end, some main conclusions are listed. The areas of weakness of the system are also highlighted for future work.
42

The waiting room: an art investigation of site in abeyance

Vickers, Sharon Unknown Date (has links)
This art project explores issues of unoccupied space. In particular, the project concerns itself with temporal aspects of site and issues of past, present and potential usage. This space, otherwise inert, invites activation by the spectator's psychological projections. This projected occupation calls on redolence of the past, memory and a sense of the utility of the site.Based on imagery evidence and personal remembered experience, the spectator provides context forthis site. The project uses the painting process to open up areas of sensibility around personal and remembered experience.The thesis is constituted as practice-based work, 80%, accompanied by an exegesis, 20%.
43

Theoretical modeling and experimental studies of particle-laden plumes from wastewater discharges

Li, Chunying, Anna. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
44

Probing the microstructure of yield-stress fluids using multiple particle tracking /

Oppong, Felix K., January 2005 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 133-138.
45

Assessing the Performance of Two Stormwater Management Ponds in Waterloo, Ontario

Mulroy, Kathleen January 2010 (has links)
Stormwater (SW) runoff in urban areas represents a major pathway for pollutant transfer to receiving waters. Best management practices (BMP) were introduced in the 1970s to help mitigate the negative effects of SW. In the 1990s, Stormwater management (SWM) ponds were established as a BMP to help increase the water quality of SW effluent. Many SWM ponds do not provide sufficient water quality treatment. Information on the internal processes influencing the reduction of total phosphorus (TP), soluble reactive phosphorus (SRP) and total suspended solid (TSS) concentrations in SWM ponds with different designs is lacking. Knowledge of the processes affecting TP, SRP and TSS retention can help improve the design of SWM ponds to enhance their treatment performance. The purpose of this thesis is to provide an assessment of the internal chemical processes that affect the trap efficiency (TE) and spatial and temporal variability of TP, SRP and TSS concentrations at two structurally different SWM ponds (Pond 45; conventional and Pond 33; hybrid extended detention) in Waterloo, ON. Water samples were collected at the inflow and outflow at the two SWM ponds during six storm events and 30 baseflow periods. A mass balance approach was used to quantify the TE of TP, SRP and TSS concentrations at each pond. Pond 33 had a TE of 24.3%, 26.7% and 66.8% for baseflow and stormflow samples of TP, SRP and TSS. Pond 45 performed much better with TE of 93.8%, 94.2% and 98% for TP, SRP and TSS concentrations. Pond 33 was a source of TP, SRP and TSS for 3, 4 and 2 storm events sampled during the field season, respectively. Pond 45 was a sink for all parameters on all storm events samples. The spatial and temporal variability of TP, SRP and TSS concentrations were examined to improve knowledge of external factors and internal processes that influence the TE of SWM ponds. The effects of storm magnitude, seasonality and vegetation growth and senescence on effluent water quality were investigated. Additionally, the role of sediment on P cycling in the ponds was evaluated by determining grain size distribution, porewater SRP concentrations, sediment geochemistry and mineralogy, and the sediment P buffering capacity. Vegetation senescence, anoxic conditions, porewater SRP concentrations, sediment characteristics and buffering capacity influenced the poor TE at Pond 33. Pond 45 had more favourable water column conditions, i.e. higher dissolved oxygen concentrations, therefore allowed greater amounts of P to adsorb onto sediment. Design and maintenance considerations are described to help improve the performance at Pond 33. Continual water quality monitoring of SW effluent will identify changes in quality and mitigation measures can be implemented to increase a SWM ponds performance.
46

Fabrication of Novel Suspended Inductors

Woodward, Lisa January 2004 (has links)
With the rapid growth in the wireless industry there has been increasing demand to make devices with better performance. This means lower power, lower voltage, smaller, and in general more efficient. This has lead to the interest in and necessity for good quality passive components. Good quality passive components make better filters, baluns, voltage controlled oscillators, and matching networks. There has been a lot of work over the last ten years focused on improving the quality of inductors. Typical inductors fabricated on silicon have Q factors of approximately 10. This is because silicon is conductive and therefore acts like a lossy ground plane and develops interfering currents. Improvements that have been attempted include thicker metal layers, thicker dielectric layers, patterned ground shields, as well as using multiple metal layers. These methods, however, still do not improve inductors to the quality of those built on insulating substrates such as glass. The main successful attempt on silicon has been where the inductor coil is released so that it is in the air supported by posts. In some work the inductor coil is raised 50 to 100µm above the underpass by methods like etching or photoresist molding. The suspended inductor approach was applied to an insulating substrate to fabricate and characterize unique suspended inductors and transformers. Inductors were released to have 1µm of air underneath the coil by the use of a release etch. Transformers were made in a similar way except two released layers where used. The top coil, done in plated gold, was released as well as an interconnection layer. Such a small air gap and the transformers with two released metal layers are a couple of the unique features of this thesis work. The devices were characterized up to 20GHz before and after release. An improvement in the peak Q factor (up to 70), as well as in the self-resonance frequency (up to 4GHz higher) was noticed after release. This is expected due to the reduction in parasitics. The results were then compared with simulations and a couple closed form expressions, both of which were able to give a reasonable accuracy. There was also success in getting good high frequency transformers. Even though some good high-Q inductors were fabricated as part of this thesis, there is still further work that can be done. This includes packaging, integration with capacitors, and further optimization.
47

Assessing the Performance of Two Stormwater Management Ponds in Waterloo, Ontario

Mulroy, Kathleen January 2010 (has links)
Stormwater (SW) runoff in urban areas represents a major pathway for pollutant transfer to receiving waters. Best management practices (BMP) were introduced in the 1970s to help mitigate the negative effects of SW. In the 1990s, Stormwater management (SWM) ponds were established as a BMP to help increase the water quality of SW effluent. Many SWM ponds do not provide sufficient water quality treatment. Information on the internal processes influencing the reduction of total phosphorus (TP), soluble reactive phosphorus (SRP) and total suspended solid (TSS) concentrations in SWM ponds with different designs is lacking. Knowledge of the processes affecting TP, SRP and TSS retention can help improve the design of SWM ponds to enhance their treatment performance. The purpose of this thesis is to provide an assessment of the internal chemical processes that affect the trap efficiency (TE) and spatial and temporal variability of TP, SRP and TSS concentrations at two structurally different SWM ponds (Pond 45; conventional and Pond 33; hybrid extended detention) in Waterloo, ON. Water samples were collected at the inflow and outflow at the two SWM ponds during six storm events and 30 baseflow periods. A mass balance approach was used to quantify the TE of TP, SRP and TSS concentrations at each pond. Pond 33 had a TE of 24.3%, 26.7% and 66.8% for baseflow and stormflow samples of TP, SRP and TSS. Pond 45 performed much better with TE of 93.8%, 94.2% and 98% for TP, SRP and TSS concentrations. Pond 33 was a source of TP, SRP and TSS for 3, 4 and 2 storm events sampled during the field season, respectively. Pond 45 was a sink for all parameters on all storm events samples. The spatial and temporal variability of TP, SRP and TSS concentrations were examined to improve knowledge of external factors and internal processes that influence the TE of SWM ponds. The effects of storm magnitude, seasonality and vegetation growth and senescence on effluent water quality were investigated. Additionally, the role of sediment on P cycling in the ponds was evaluated by determining grain size distribution, porewater SRP concentrations, sediment geochemistry and mineralogy, and the sediment P buffering capacity. Vegetation senescence, anoxic conditions, porewater SRP concentrations, sediment characteristics and buffering capacity influenced the poor TE at Pond 33. Pond 45 had more favourable water column conditions, i.e. higher dissolved oxygen concentrations, therefore allowed greater amounts of P to adsorb onto sediment. Design and maintenance considerations are described to help improve the performance at Pond 33. Continual water quality monitoring of SW effluent will identify changes in quality and mitigation measures can be implemented to increase a SWM ponds performance.
48

Distribution and Partitioning of Trace Elements in Estuaries and Coasts off Southwestern Taiwan

Ho, Peng 26 January 2011 (has links)
Water samples were collected along salinity gradients during different seasons from three estuaries (Tseng-Wen, Gao-Ping, Er-Ren) and coasts in/off southwestern Taiwan. In order to assess the partitioning of trace metals between solution and particle, the concentrations of dissolve and particulate trace metals (Cd, Cu, Ni, Pb) along with their chemical affinity fractions, were determined. This study investigated the variations in distribution and partitioning of the different metals in estuarine waters, and examined the effects of oxides and particulate organic matter on the partitioning of trace metals in waters from different estuaries. Fractionation of dissolved trace metal species was based on ion exchange (Chelex-100 and AG MP-1 resins) separation techniques. The fractions obtained were operationally defined as labile (Chelex), organic (AG MP-1) and inert. Particles were extracted to three phases (surface adsorbed phases, Fe¡VMn oxide/organic phases and refractory phases) using sequential extraction techniques. Seasonally variable distributions of dissolved trace metals were found in the Tseng-Wen estuary. The behavior of trace metals was mainly influenced by anthropogenic input during the dry season in the upper Tseng-Wen estuary, while mixing processes controlled the distribution of trace metals during the wet season. The dilution effect was a major factor in the metal distribution in the Gao-Ping estuary due to high river discharge. The higher concentration of metals in the Er-Ren estuary, in contrast to other estuaries indicated that the Er-Ren estuary has serious pollution concerns. According to the results of particulate metal fractions obtained, Cd and Pb existed predominantly in the surface adsorbed phase. The speciation and spatial distribution of Cd were similar to those of Mn, indicating that the formation of authigenic Mn oxides affected the distribution of Cd in estuaries. The percentage of oxide /organic phase for Cu accounted for 25% of total particulate Cu, but dose not correlate well with particulate organic carbon, implying that organic carbon is not the only factor controlling particulate Cu distribution. Ni was present mainly in lattice phase, except in the Er-Ren estuary where anthropogenic Ni loading was high. In the Tseng-Wen and Gao-Ping estuaries, the percentages of lattice phase of all metals determined in this study during the wet season were higher than those during the dry season. These seasonal variations are probably resulted from different flushing times in dry/wet seasons, which control the extent of geochemical processes for trace elements.
49

The spatial and temporal variability and budget of suspended sediment in Taiwan major rivers

Chueh, Sheng-An 17 July 2012 (has links)
¡@¡@Sediment loads of Taiwan rivers have increased in recent years because of frequently recurring typhoons. In addition to the dry and wet seasons causing sever erosion and deposition of the riverbed, the long-term records from 1967 to 2009 of suspended sediment concentration and daily discharge observed by the Water Resource Agency in Taiwan Rivers were used in this study. ¡@¡@To understand the sediment deposition or erosion in the rivers, we need to find how the discharge and sediment load interact with each other under the natural and human influences. The hydrological data we used in this study were from Water Resources Agency¡¦s annual reports, including the Danshui River, the Lanyang River, the Zhuoshui River, the Beinan River, and the Gaoping River. ¡@¡@High turbidity happen when sediment concentration exceeds 40 g/L. Judging by this threshold, taking upstream stations of the Zhuoshui River for example, the Nei-Mao-Pu Station (1973-2009) reached this threshold 6 times, Bao-Shih Bridge Station (2004-2009) 19 times, and Yun-Feng Bridge Station (1995-2009) 19 times. But Yen-Ping Bridge Station (2004-2009), which is at the middle part of Zhuoshui River, has never reached the threshold, became the erosion rate and sedimentation rate are balanced here. Chi-Chou Bridge Station (2000-2009) at the downstream reached the threshold for 11 times too. ¡@¡@According to the river graded profile, in the Danshui River, obvious erosion occurred at the Liu-Kwei Bridge Station in 2000, the Po Bridge Station in 2001, and San-Hsia (2) Station in 2004 and 2007. In the Zhuoshui River, significant deposition took place at the Yun-Feng Bridge Station in 2006 and 2010. In the Gaoping River, deposition occurred at the A-Chyi-Ba Bridge Station in 2000, while erosion occurred at Liu-Kwei Station in 2001 and at the A-Chyi-Ba Bridge Station in 2007 and 2008. ¡@¡@Above results show that the major sediments are deposited upstream, forming a temporary sediment storage source region, such as at Li-Lin Bridge Station, Liu-Kwei Station, and Yun-Feng Bridge Station at the Gaoping River, all of which have reached the threshold when a typhoon comes. Investigating daily rainfall data from Taichung Weather Station in 2005, we find that besides typhoon influences, when the rainfall is exceeding 200 mm High turbidity events would occur in the Jhoushuei River. ¡@¡@According to our study, we find that most sediment deposits at the upper reaches, forming temporary sediment storages, so when a typhoon comes, we can see the sediment downstream is often mixed with the sediment coming from upstream storages. That is because the slope in the upper reaches is steeper, and heavy rain makes the temporary deposit easy to erode. On the contrary, the slope in the lower reaches is more gentle so it is easier for sediment to deposit, which is the reason why the stations at downstream often reach the threshold. When the extreme weather occurs, the temporary sediment storages along the entire river course become the source regions to release the sediment out to the sea.
50

Ecological Effects and In-situ Detection of Particulate Contaminants in Aqueous Environments

Fuller, Christopher Byron 2011 May 1900 (has links)
The ecological effects and mechanistic efficiency of chemical oil spill countermeasures must be evaluated prior to their ethical application during real spill response scenarios. Equally important is the ability to monitor the effectiveness of any spill response in real time, permitting informed response management. In-situ sensors are key components of such event based monitoring and continuous monitoring programs. This project investigates crude oil toxicity as a particulate suspension, suitability of in-situ instrumentation to measure crude oil suspensions, and the applicability of using acoustic backscatter to measure suspended solids and sub-surface oil droplet suspension concentrations. The ecological effects to inter- and sub-tidal sediment dwelling organisms exposed to crude oil, both treated with a chemical dispersant and un-treated, was evaluated. Elevated toxicity, expressed as percent mortality and reduced luminescence, and oil concentrations were observed in inter-tidal sediments receiving oil only treatments compared to oil-plus-dispersant treatments. Sub-tidal sediments showed heterogeneous distribution of crude oil with elevated amphipod mortality compared to no oil controls suggesting an oil-sediment aggregation mechanism. A separate laboratory scale study found that the soluble crude oil fractions were responsible for the observed mortality in pelagic species while the more dominant oil droplet fractions were relatively non-toxic. Subsequent studies focused on the in-situ detection of crude oil and particle suspensions in aqueous environments. The first showed that both in-situ fluorescence spectroscopy and Laser In-Situ Scattering Transmissometry (LISST) can effectively measure crude oil concentrations in aqueous environments. The applicability of the LISST implies that crude oil in an aqueous medium can be measured as a particle suspension. Acoustic backscatter (ABS) was investigated for its applicability as a surrogate measurement technology for aqueous particle suspensions. This study showed a log linear correlation between ABS and volume concentration (VC) over a variable particle size distribution. This correlation is due to the dependency of both ABS and VC to the particle size distribution. Log-linear ABS responses to oil-droplet suspension volume concentrations were also demonstrated. However, the inability to reproduce response factors suggests that more work is required to produce viable calibrations that may be used for sub-surface oil plume detection.

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