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Articles 1 - 9 of 9
Full-Text Articles in Engineering
Investigating The Role Of Iron In The Photogranulation Phenomenon, Abeera Ayaz Ansari
Investigating The Role Of Iron In The Photogranulation Phenomenon, Abeera Ayaz Ansari
Doctoral Dissertations
Oxygenic photogranules (OPGs) are dense spherical microbial aggregates that are used for self-aerating wastewater treatment. Filamentous cyanobacteria are key granulating species, providing structural backbone and integrity in OPGs. Currently, the mechanisms for selecting filamentous cyanobacteria and their ability to form spherical OPGs are not well understood. Literature shows that iron (Fe) availability plays a significant role in the cyanobacterial growth and colony formation. Moreover, Fe availability is known to be dependent upon light, which is an essential growth substrate for the phototrophs. This research has investigated the role of Fe in the photogranulation phenomenon and the impact of light intensity …
3d Study Of Gas Hydrate Formation And Dissociation In Porous Media And Dem Modeling Of Granular Materials, Zaher Jarrar
3d Study Of Gas Hydrate Formation And Dissociation In Porous Media And Dem Modeling Of Granular Materials, Zaher Jarrar
Doctoral Dissertations
Natural methane gas hydrates availability and ongoing rise in demand for energy, motivated researchers to consider gas hydrates as a potential energy source. Production of methane from hydrate-bearing sediments requires hydrate dissociation for releasing mobile methane gas in sediments prior to gas production operations. Fines may migrate through or clog the pore space of sandy sediments depending on the geometry and topology of the pore space. This dissertation employs unique in situ experiments and techniques to gain a comprehensive understanding of the associated physical processes (such as fines migration, clogging and gas driven fracture) and validation of hydrate dissociation models’ …
Investigating The Compactability Of Hot Mix Asphalt Utilizing The Concept Of The Locking Point, Pawel Andrzej Polaczyk
Investigating The Compactability Of Hot Mix Asphalt Utilizing The Concept Of The Locking Point, Pawel Andrzej Polaczyk
Doctoral Dissertations
Compaction is an important process for the asphalt mixture service life. An adequately compacted mixture is crucial for long-lasting pavement. Compaction is a procedure utilized to compress and decrease the volume of the material, which provides essential ingredients that influence the pavement's performance. During asphalt mix compaction, the aggregate coated with asphalt binder are compressed together, following an increase of interparticle friction and surface contact and finally interlocking to provide the resistance to deformation. At the same time, the permeability is decreased, and the durability is increased. Compactability is utilized to evaluate how much compaction energy is required to compact …
Scaling Up The Oxygenic Photogranule (Opg) Wastewater Treatment Process, Joseph G. Gitau
Scaling Up The Oxygenic Photogranule (Opg) Wastewater Treatment Process, Joseph G. Gitau
Doctoral Dissertations
Photogranular biomass has yet to be utilized at large scale for wastewater treatment despite their potential to lower energy demand due to self-aerating capacity in addition to better process control compared to conventional technologies. An evaluation of critical driving factors affecting scaling up has yet to be undertaken. The current generation of oxygenic photogranules under hydrostatic conditions (a deviation from orthodox conditions creating other granules) limit seeding of larger reactors in time and scale. In addition, evaluating the photosynthetic productivity of granules which exist as closely commingled consortia with tightly coupled production and consumption processes, has yet to be undertaken. …
Studying The Effects Of Various Process Parameters On Early Age Hydration Of Single- And Multi-Phase Cementitious Systems, Rachel Cook
Doctoral Dissertations
”The hydration of multi-phase ordinary Portland cement (OPC) and its pure phase derivatives, such as tricalcium silicate (C3S) and belite (ß-C2S), are studied in the context varying process parameters -- for instance, variable water content, water activity, superplasticizer structure and dose, and mineral additive type and particle size. These parameters are studied by means of physical experiments and numerical/computational techniques, such as: thermodynamic estimations; numerical kinetic-based modelling; and artificial intelligence techniques like machine learning (ML) models. In the past decade, numerical kinetic modeling has greatly improved in terms of fitting experimental, isothermal calorimetry to kinetic-based modelling …
Seismic Behavior Of Composite Bridge Columns, Mohanad M. Abdulazeez
Seismic Behavior Of Composite Bridge Columns, Mohanad M. Abdulazeez
Doctoral Dissertations
“This study investigates experimentally and numerically the seismic behavior of large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) innovative bridge columns as a sustainable approach to endure and rapidly recover from natural disasters such as earthquakes. The HC-FCS column consisted of a concrete shell sandwiched between an outer fiber-reinforced polymer (GFRP) tube and an inner steel tube to provided continuous confinement for the concrete shell along with the height of the column. The columns have a slender inner steel tube with diameter-to-thickness (Ds/ts) ratios ranged between 85 to 254. Each steel tube was embedded into the footing, while the …
Minimizing The Negative Effect Of Pumping On Scc Freeze-Thaw Durability, Daniel Galvez-Moreno
Minimizing The Negative Effect Of Pumping On Scc Freeze-Thaw Durability, Daniel Galvez-Moreno
Doctoral Dissertations
“The durability of concrete must be ensured to reduce the carbon footprint of the production of portland cement. If concrete is properly designed to preserve its integrity under adverse exposure conditions, the service life of the material can be extended with minimum maintenance. Nevertheless, bad handling, placing, finishing or curing practices can abate the durability potential and service life of even the best mix design. Pumping concrete is a very efficient placing technique that offers significant cost reduction and versatility at the jobsite, but it also has the potential of altering the air void system parameters, which are key to …
Complexities Observed During The Development Of A Rheological Testing Procedure For Small Cement Paste Samples, Aida Margarita Ley-Hernandez
Complexities Observed During The Development Of A Rheological Testing Procedure For Small Cement Paste Samples, Aida Margarita Ley-Hernandez
Doctoral Dissertations
“Rheology has been widely used to describe the flow properties of fresh cement-based suspensions. The use of a rheometer to characterize these properties is not a straightforward task due to the dependency to different preparation conditions, mixing processes, testing procedures and measuring instruments employed. In addition, shear and time dependency of the material which undergoes chemical and physical particle bonding, caused by hydration of cement and flocculation. Nevertheless, the characterization and understanding of the rheological behavior of cement-based materials have become essential with the recent introduction of novel applications like digital construction in the field of civil engineering, among others. …
Bond Behavior Of Advanced Fiber Reinforced Composite-Concrete Joints, Xingxing Zou
Bond Behavior Of Advanced Fiber Reinforced Composite-Concrete Joints, Xingxing Zou
Doctoral Dissertations
“Externally bonding advanced composite materials to concrete structures is an effective way to improve their strength, ductility, and durability. The interfacial bond behavior is fundamental to understand the overall structural performance of concrete structures strengthened with advanced composite materials. This study includes a comprehensive investigation of the bond behavior of composite-concrete joints with different fiber reinforced composite types. First, a direct approach to determine the bond-slip relationship for fiber reinforced cementitious matrix (FRCM)-concrete joints based on fiber strain measurements was proposed. Then, an analytical solution to predict the full-range response of FRCM-concrete joints was derived by assuming a trilinear bond-slip …