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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.
21

Distribution of sulphur, iron, copper and zinc in modern marine sediments of Mud Bay, Crescent Beach, B.C.

Northcote, Kenneth Eugene January 1961 (has links)
The purpose of this thesis was to investigate the pattern of distribution of some elements in the tidal flat environment at Mud Bay near Crescent Beach, B.C. Samples of sediment were collected in a regular pattern over the bay. Quantitative chemical analyses of the samples were made for acid-soluble copper, zinc, lead, and molybdenum. The same samples were analysed spectrochemically for iron and sulphur. The results of the analyses were plotted on base maps and contoured. It was found that there was a definite pattern of sedimentation. Because of the shallow depth of water at high tide and the bay's sheltered aspect, deposition of finer-grained material occurred near shore. In slightly deeper and more exposed parts of the bay fine-grained material was winnowed leaving coarse-grained sediment. Most of the elements showed a definite pattern of distribution. Sulphur, copper, and zinc showed a tendency to concentrate in finer-grained materials. Iron, in the form of magnetite, was deposited with coarser-grained materials near river mouths and exposed parts of the bay. Lead values were too low to permit conclusions regarding its distribution. Molybdenum concentrations were below the detection level of the method of chemical analysis. No attempt was made to determine the form in which the elements were present nor to determine the reason for their concentration other than to suggest the most obvious possibilities. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
22

Sedimentation solutions for the Port of Pascagoula

Johnson, Hunter Neal 13 December 2008 (has links)
The purpose of this work, which is designed for the Port of Pascagoula, is to locate sedimentation problems, identify sediment characteristics, and devise a method to decrease the port’s dredging costs. In order to understand what sediment problems are typical of the Port of Pascagoula the characteristics that are associated with sediment transportation in the port’s harbors are examined. This examination consists of a field investigation followed by an extensive evaluation of the data. Once the characteristics that are unique to the harbors are identified, potential solutions are examined. These potential solutions are evaluated until a feasible and efficient plan is devised to reduce the ports dependency on dredging. Recommendations include agitation, a fluid mud trap, and the practice of active nautical depth. Each of these solutions would allow the port to reduce its dredge costs.
23

Development of a mixing device for red mud flocculants.

Dougherty, David J. January 1999 (has links)
The performance of flocculants used in the solid-liquid separation of red mud is often compromised by the methods used to mix the fast acting polymers into the slurry. A simple model of the relationship between flocculant performance and intensity of mixing is proposed and a device for mixing flocculant and slurry has been developed on the basis of the model.The intensity of mixing at the point of distributing the flocculant into the slurry is arguably the most important variable influencing the final flocculant performance. This relationship is established using data from flocculation tests in an agitated tank. The flocculant performance is monitored using an optical sensor and the settling rate of the solid-liquid interface is used as a comparison for the optical sensor. The difficulties, errors and merits of the optical sensor to study the flocculation of red mud and automatic control of flocculation processes are also assessed.The mixing device is connected to a pipe for flocculation tests with red mud. For the tests carried out, a high level of flocculation was recorded.The mixing device combines the flocculant and slurry as thin annular jets directed into one another. The opening for the slurry jet can be altered to provide a variation of the mixing that is achieved. The capability of the device to mix rapidly has been assessed using the diazo coupling reactions between l-naphthol and diazotised sulphanilic acid in alkaline, aqueous solution at room temperature. Variables studied included flow rate and slurry jet opening. Better mixing was indicated at higher flow rates and at reduced jet opening. The use of the diazo coupling reactions for studying micromixing is also assessed.
24

Seismic interpretation and classification of mud volcanoes of the South Caspian Basin, offshore Azerbaijan.

Yusifov, Mehdi Zahid 01 November 2005 (has links)
Understanding the nature of mud volcanism, mechanisms of formation, types of eruptions and their relationship to the hydrocarbon systems provides important information about subsurface conditions and geological processes within the South Caspian Basin. A 2D seismic grid in southeastern offshore Azerbaijan is used to define the areal distribution of mud volcanoes and to make a classification of the mud volcanoes based on characteristic seismic features. As a result detailed database for each determined mud volcano is constructed. Analysis of different parameters from this database shows that there is a high concentration of mud volcanoes at the southern part of the study area. It is coincides with the distribution of the subsurface structures within the basin. Mud volcanoes with low relief (several tens of meters) are mainly concentrated in the northeast. Conversely, mud volcanoes with large vertical relief (greater than 200 m) are clustered in the southwest part of the basin. Mud volcano development in the South Caspian Basin is generally linked to faults, which in some instances are detached at the basement level. By using interpreted seismic surfaces it is possible to determine relative time of mud flows from the mud volcanoes. Timing of mud flows reveals to the actual activity of the mud volcanoes and it gives valuable information about possible mechanism of mud volcanism within the South Caspian Basin. Previous studies of the onshore mud volcanoes in Azerbaijan and the results from current work conclude that mud volcano formation within the South Caspian Basin is mainly controlled by tectonic forces and overpressured sediments. Mud volcano activity is not always related to the Maykop organic reach shale succession. It can occur at shallow depths by pressure breakthrough from any stratigraphic zone.
25

Study of the seismic attenuation generated by the mud layer in Lake Maracaibo, Venezuela

Perez Arredondo, Javier Antonio 30 September 2004 (has links)
Several seismic properties of Lake Maracaibo are unique and difficult to understand. However, studies show that the two principal factors that affect the seismic data are likely to be the low compressional and shear wave velocities generated by the gassy sediment in the mud layer, and the high attenuation of the compressional and shear waves. This mud layer sediment is heavy and is not suspended in the water. Furthermore, it is compacted enough to support shear stresses and, therefore, has a finite shear wave velocity. In theory, the gas content of the sediment reduces the compressional wave velocity by an order of magnitude below the values for water saturated sediments, but in Lake Maracaibo several studies show that gassy sediment reduces the compressional wave velocity from 1500 m/s to between 300 m/s and 700 m/s. This situation produces high attenuation of the compressional waves that are traveling through the sediment in the first 100 m. However, the results of seismic modeling show that this velocity has to be between 700 m/s and 900 m/s in order to get reasonable results, at least in the study area. The results show that there are very important lithological differences between the zones with and without gassy sediments in the mud layer. The best match between the raw data and the synthetic seismogram was found when an embedded rigid shale layer was located within the mud layer, in the first 100 m. Unrealistic results were produced when the rigid shale layer was removed in the modeling. This rigid layer produces a destructive interference in the Stoneley wave that could be observed in the seismic data and the synthetic seismogram. In this research, the attenuation quality factor Q, an intrinsic property of rock, will be studied. Common attenuation mechanisms include grain sliding, viscous flow of pore fluid or gas, viscous relaxation and other features. Additionally, it will be shown that other factors can be proposed to account for the attenuation of compressional and shear waves in Lake Maracaibo sediments. They include: the viscous losses between the particles and the fluid immediately above the mud layer; and the solid friction losses between the particles, the mud layer and the gassy sediment. This research shows That the attenuation in the mud layer in the zone with gassy sediment is very different from the attenuation in the zone without gassy sediment, and that the compressional wave attenuation is larger in the mud layer zone with gassy sediment than in the mud layer zone without gassy sediment. Finally, the research shows that the ringing is an important phenomenon associated with the low velocity in the mud layer and that this ringing has more frequency content in the zone without gassy sediment than in the zone with gassy sediment.
26

Material virtualities : approaching online textual embodiment /

Sundén, Jenny, January 2002 (has links) (PDF)
Diss. Linköping : Univ., 2002.
27

Laboratory Experiments on Mud Flocculation Dynamics in the Fluvial and Estuarine Environments

Abolfazli, Ehsan 06 June 2023 (has links)
Due to the flocculation process, suspended mud aggregates carried by rivers and streams can undergo changes in their size, shape, and settling velocity in response to environmental drivers such as turbulence, sediment concentration, organic matter (OM), and salinity. Some have assumed that salt is necessary for floc formation, and that mud, therefore, reaches the estuary unflocculated. Yet mud flocs exist in freshwater systems long before the estuarine zone, likely due to the presence of OM and ions in the water that facilitate binding and aggregation of mud particles. This research aimed to examine the flocculation state of mud over the fluvial as well as fluvial to marine transition (FtMT) zones of the Mississippi River basin and how salinity, or the ion concentration of water, and organic matter independently and together affect flocculation. Suspended mud was found to be mostly flocculated in the headwaters of the Mississippi River in southwest Virginia, USA. However, increasing the ion concentration of water samples to levels measured following winter storms changed the size distribution of suspended particles, led to more of the mud existing in large flocs, and resulted in an overall increase in average size by about 40%, thereby increasing the settling rate of the mud relative to the suspensions without salt. These results suggested that potential negative effects of road salts on mud deposition should be investigated further. Additional experiments were used to examine the flocculation of a natural mud sample with and without OM showed that the rate of floc growth and equilibrium size both increase with salinity regardless of the presence or absence of OM. However, the response of both to salinity was stronger when OM was present. In deionized water, natural sediment with OM was seen to produce large flocs. However, the size distribution of the suspension tended to be bimodal. With the addition of salt, increasing amounts of unflocculated material became bound within flocs, producing a more unimodal size distribution. Here, the enhancing effects of salt were noticeable at even 0.5 ppt, and increases in salinity past 3 to 5 ppt only marginally increased the floc growth rate and final size. A salinity-dependent model to account for changes in floc growth rate and equilibrium size was presented. Laboratory experiments on the sediment suspended in the lower reaches of the Mississippi River were used to provide further insight on the mud flocs behavior in the FtMT. Turbulence shear rate, a proxy for the river hydrodynamics, was found to be the most influential factor in mud floc size. While artificial increase in salinity by adding of salts did not lead to considerable increase in floc size, addition of water collected from the Gulf of Mexico enhanced the flocculation. These effects were speculated to originate from the biomatter composition of the Gulf water, particularly where the nutrient-rich Mississippi River water reaches the marine water. / Doctor of Philosophy / Rivers bring a substantial amount of mud to coastal regions. Where this mud deposits is important in shaping the coastal land and nutrient dynamics. Mud particles are different from sand and gravel in that they can form aggregates known as flocs that constantly change shape and size under different conditions. As they change size, they change how fast they sink, and this influences where they deposit. Due to their small size, mud particles are also considered a pollutant as they can clog up fish gills and destroy freshwater habitats. Findings of this dissertation showed that the roadway deicing salts that make their way to streams can enhance the aggregation of mud particles, causing them to sink faster. This can be harmful to the species that live on streambeds. While salts are known to enhance flocculation, there is ample evidence that flocs exist in rivers before reaching the sea. It is possible, therefore, that flocs in estuaries are due to biological matter acting as a glue to bind mud particles together and may not be influenced by salt. This dissertation looked at the effects of saltwater on mud flocculation when biological matter is present and when it is absent. Findings showed that salinity increased the size of mud flocs, even more so than when organic matter was absent. However, organic matter was needed for flocs to reach sizes often found in nature. An equation was also provided to aid in the prediction of floc size under different salinities. Observations on the lower Mississippi River flocs showed that the turbulence of water was the most influential factor in determining the size of flocs.
28

Contrasting patterns of habitat-specific recruitment success in sympatric species of thalassinidean shrimp : effects of epibenthic bivalve shell with implications for population control in areas with commercial oyster culture /

Feldman, Kristine Ladyka. January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 164-192).
29

Archaeometrical Investigation Of Mud Plasters On Hittite Buildings In Sapinuwa-corum

Guducu, Gulnur 01 January 2004 (has links) (PDF)
The study aimed to identify mud brick and mud plaster technology of Hittites by examining some burnt mud brick walls of Shapinuwa Hittite city and to point out repair and conservation needs of those burnt mud brick structures. The walls were documented by mapping the visual decay forms. The bulk density, total porosity, water absorption by capillarity and water vapour permeability were obtained as basic physical properties. The mechanical properties were expressed by the modulus of elasticity and the uniaxial compressive strength. Compositional and mineralogical properties were determined by optical microscopy, XRD, TGA and SEM coupled with EDX, and by XRF analyses. In addition, pozzolanic activity of powdered samples was determined.. The samples studied had low bulk density, high porosity and high water vapour permeability. The Emod values and the UCS values showed that their mechanical properties were comparable with some historic mortars and bricks. The petrographic and mineralogical analyses of burnt materials indicated a mud brick composition containing fine and medium sized siliceous aggregates mainly composed of quartz. The binder was concluded to be composed of kaolinite illite and micritic calcite that indicated the use of ideal soil compositions by Hittites to make lime stabilized mud bricks, in terms of today standards. The temperature during the fire was estimated to be around 700-800 C. The high pozzolanicity of burnt mud bricks and plasters, provided an opportunity to repair the structure using pozzolanic lime mortars to produce good adhesion. The first results of consolidation treatments had shown that the physical and mechanical properties of burnt mud brick can be improved by impregnation with ethylsilicates such as Tegovakon V.
30

An In-depth Investigation of an Aluminum Chloride Retarded Mud Acid System on Sandstone Reservoirs

Aneto, Nnenna 2012 May 1900 (has links)
Sandstone acidizing using mud acid is a quick and complex process where dissolution and precipitation occur simultaneously. Retarded mud acids are less reactive with the rock reducing the reaction rate hence increased penetration into the formation to remove deep damage. To understand thoroughly the retarded mud acid system, an in-depth investigation of the reaction of HF (hydrofluoric) and H2SiF6 (fluorosilic acid) with alumino silicates and the retarded system is undertaken using coreflood analysis and mineralogy analysis using the inductively coupled plasma. Coreflood analysis is used to understand and investigate the permeability changes in the sandstone rock as the retarded mud acid is injected at different conditions and the inductively coupled plasma (ICP) is used to investigate the effluent samples from the coreflood analysis to properly understand this system. Several issues that have not been addressed previously in literature are identified and discussed, including an optimum flowrate when sandstone is acidized, by acidizing the sandstone rock with a retarded acid system at various flowrates and determining the initial and final permeabilities. Also investigated is the retarded acids compatibility with ferric iron and a comparison of the retarded acid system to regular acid to consequently enable a thorough understanding of the retarded mud acid system using aluminum chloride (AlRMHF). Based on the work done, it is found that the absence of a hydrochloric (HCl) preflush is very detrimental to the sandstone core as calcium fluoride is precipitated and the retarded acid system is found to be compatible with iron(III) as an impurity. The regular acid (RMHF) dissolves considerably more silicon and produces more fines than the AlRMHF. 1cc/min is found to be the optimum flowrate when a sandstone core is acidized with AlRMHF. At this low flowrate, less silicon is dissolved, more aluminum is seen in the effluent and more calcium is dissolved. The retarded aluminum acid system considerably reduces the rate of reaction as evidenced in the dissolution reaction when compared to a regular mud acid system. This reduced rate of reaction implies deeper acid penetration and ultimately deeper damage removal.

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