Engineering Commons^™

Numerical Modelling Of Downburst Interaction With Bluff Body, Aditi Jog

Electronic Thesis and Dissertation Repository

The objective of this study is to investigate the interaction of a bluff body with a downburst flow. Numerical investigation of the flow field using CFD analysis was carried out for three different downburst sizes (h/d=1, 2, 4) under suitable boundary conditions subjected to constant jet velocity. The downburst-structure interaction study was conducted for two jet diameters (h/d=1 and 4) and two radial locations from the downburst center.

The results showed that the downburst size greatly dominates the intensity of the flow. The largest downburst resulted in the highest velocity magnitude near the ground and also covered a larger area …

Specimen Size Effect On Shear Behavior Of Loose Sand In Triaxial Testing, Tarek Omar

Electronic Thesis and Dissertation Repository

Triaxial tests are widely used to determine the behavior and strength characteristics of soils without due attention to the differences in specimen size. Several drained and undrained monotonic triaxial compression shear tests are performed on three different specimen sizes of the same sand to investigate the influence of specimen size and scale effect on the shear behavior. The test results indicate that the behavior of loose sand is strongly influenced by the specimen size, with larger specimens exhibiting a stiffer behavior during isotropic compression, and mobilizing smaller shear strengths and effective friction angles. Triaxial testing also involves many sources of …

Experimental Modeling Of Wind Farm Topography And Canopy, Dan S. Parvu

Electronic Thesis and Dissertation Repository

As an important renewable energy source for electricity generation, wind energy must rely on efficient and accurate wind resource assessment for the siting and the design of wind farms. Traditionally relying on numerical modeling, current wind farms built in Canada, notably, experience an under-performance in terms of power generation. This work studies an alternative approach to wind farm modeling through experimental wind tunnel testing.

The objective of the work is to develop methodologies on how topographic and forest canopy models should be built as scale models of full scale wind farms. The models developed are validated by comparing the data …

Investigation Of Hollow Bar Micropiles In Cohesive Soil, Osama F. El Hadi Drbe

Electronic Thesis and Dissertation Repository

Micropiles are used in various applications, including low capacity micropile networks, underpinning and seismic retrofitting of existing foundations and high capacity foundations for new structures. They facilitate fast installation with a high degree of ground improvement. The current Federal Highway Administration (FHWA) design guidelines designate hollow bar micropiles as Type B micropiles, even though their construction technique is different than typical Type B, which results in overly conservative design. In addition, the current practice for construction of hollow bar micropiles is limited to drilling bit/hollow bar diameter ratio of 2.5 or less. In this thesis, full-scale load tests were conducted …

Treatment Of Combined Sewer Overflows Using Ferrate (Vi), Rohan Gandhi

Electronic Thesis and Dissertation Repository

Prevention of pollution from combined sewer overflows (CSOs) is currently a major concern due to their impact on aquatic and human environment. With the stringent regulations related to the CSOs treatment, it is necessary to develop an efficient, fast and low cost treatment technique that meets the applicable criteria. In this work, the comprehensive study was done to determine the efficiency of ferrate (VI) for the treatment of CSOs. At a Fe (VI) dose of 0.24 mg/l, TCOD, SCOD, TBOD₅, SBOD₅, TSS, VSS, TP, TN and soluble TN removal efficiencies of 71%, 75%, 69%, 68%, 72%, …

Cyclic And Post-Cyclic Response Of Silt And Sandy Silt Soils, Ali El Takch

Electronic Thesis and Dissertation Repository

A series of cyclic and monotonic constant-volume ring shear tests were carried out to determine the cyclic and post-cyclic response of silts and sandy silts with 25% and 50% sand. The elastic soil behavior at very small shear strain (γ < 10^-4%) was investigated through shear wave velocity (Vs) measurements using bender elements at vertical stresses ranging from 50 to 300 kPa, while strain-controlled constant volume cyclic ring shear tests were conducted to establish shear modulus (G) and damping ratio (D) at larger shear strain amplitudes (γ > 0.01%). Liquefaction and strain-softening occurred at excess pore water pressure ratios (r_{u …}

Hydrogeological And Thermal Sustainability Of Geothermal Borehole Heat Exchangers, S. Emad Dehkordi

Electronic Thesis and Dissertation Repository

Assessment of the current approach taken by guidelines and design methods of vertical closed loop heat exchangers shows that often groundwater flow is either disregarded or is not methodically incorporated. The state of scientific research in this arena reveals that overlooking the groundwater flow in the design procedure may not always be a correct assumption. The significance of advective heat transport compared to conduction is defined by the groundwater flux or Darcy velocity which heavily depends on the hydraulic conductivity of the ground, followed by the hydraulic gradient which has a relatively limited range. A sensitivity analysis on ground and …

Numerical Evaluation Of Aerodynamic Roughness Of The Built Environment And Complex Terrain, Daniel S. Abdi

Electronic Thesis and Dissertation Repository

Aerodynamic drag in the atmospheric boundary layer (ABL) is affected by the structure and density of obstacles (surface roughness) and nature of the terrain (topography). In building codes and standards, average roughness is usually determined somewhat subjectively by examination of aerial photographs. For detailed wind mapping, boundary layer wind tunnel (BLWT) testing is usually recommended. This may not be cost effective for many projects, in which case numerical studies become good alternatives. This thesis examines Computational Fluid Dynamics (CFD) for evaluation of aerodynamic roughness of the built environment and complex terrain.

The present study started from development of an in-house …

Optimisation Of The Transesterification Stage Of Biodiesel Production Using Statistical Methods, Arnold Paintsil

Electronic Thesis and Dissertation Repository

The present research examines solely the transesterification stage of the biodiesel production process. Six process variables that affect the yield of biodiesel at this stage are examined using the 12 run Plackett-Burman Design. To study the effect of FFA[1] and to replicate real life situations where oil (feedstock) contain varying amounts of FFA, linoleic acid is used as FFA and intentionally added to high oleic acid canola oil containing less than 0.07% FFA. The process is catalyzed with potassium carbonate and evaluated at varying temperatures, stirring rates, reaction times and methanol oil ratios. The yields at the end of …

Numerical And Experimental Analysis Of Retrofit System For Light-Framed Wood Structures Under Wind Loading, Ryan B. Jacklin

Electronic Thesis and Dissertation Repository

Past high speed wind events have exposed the vulnerability of the roof systems of existing light-framed wood structures to the uplift forces resulting from high speed winds, contributing greatly to economic and human loss. This research focuses on developing a retrofit system to increase the uplift capacity of these structures using numerical and experimental techniques. The proposed system provides the uplift forces an alternate load path to the ground, reducing the demand placed on the weak, nailed connections within the structure. A three-dimensional finite-element model of a roof system of full-scale wood structure has been developed. The model is compared …

Carbon-Nzvi Nanocomposites For Dechlorination Of Halogenated Hydrocarbons, Jing Cheng

Electronic Thesis and Dissertation Repository

A family of hybrid nanocarbon/nanoiron composites has been developed with the aim to carry out simultaneous adsorption and dechlorination of chlorinated hydrocarbons from aqueous solutions. Several methodologies for the synthesis of these materials are evaluated in terms of their adsorption capacities and dechlorination activities. Detailed spectroscopic and microscopy studies indicate that the adsorption ability of the carbonaceous support is greatly improved after acid oxidization, attributed to the formation of oxygenated functional groups on their surfaces. When iron nanoparticles are incorporated on the composites, the materials show a much higher trichloroethylene (TCE) removal efficiency compared to bare metallic nanoiron particles or …

Finite Element Analyses Of Single-Edge Bend Specimens For J-R Curve Development, Yifan Huang

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve such as the J-integral resistance curve (J-R curve) is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). Two studies about the development of the J-R curve are carried out and reported in this thesis. In the first study, the plastic geometry factor, i.e. the η_pl factor, used to evaluate J in a J-R curve test based on the single-edge bend (SE(B)) specimen is developed based on the three-dimensional (3D) finite element analysis (FEA). The main …

Static And Seismic Soil Culvert Interaction, Osama Salem A. Abuhajar

Electronic Thesis and Dissertation Repository

Failures of box culverts under static and earthquake loads can cause significant economic loss. Therefore, it is important to investigate the soil-culvert interaction of box culverts to understand their responses to such loads. The response of buried box culverts is a complex soil-structure interaction problem, where the relative stiffness between the soil and the structure is a critical factor. Soil arching is an important aspect of the soil-culvert interaction problem, and results in the redistribution of free-field stresses due to the presence of buried structures and leads to an increase or decrease in the loading around box culverts.

A series …

Effect Of Instantaneous Load Eccentricities On The Inelastic Torsional Responses Under Bi-Directional Seismic Excitations, Xiaojing Cui

Electronic Thesis and Dissertation Repository

This study evaluated the inelastic torsional response due to instantaneous load eccentricities. The load eccentricities, which caused by the motion of the center of mass are time-dependent, even exist for two-way symmetric structures under seismic excitations. The eccentricities and bi-directional horizontal excitations can lead to the torsional motion. The study of the impacts of such a second-order effect (called A-Delta effect) on structural systems and, this effect in combination with the P-Delta effect on structural systems has not been reported in the literature.

This study is focused on the investigation of the structural responses under the A-Delta …

Ignition Method Development And First Field Demonstration Of In Situ Smouldering Remediation, Grant C. Scholes

Electronic Thesis and Dissertation Repository

Self-sustaining Treatment for Active Remediation (STAR), a smouldering combustion-based technology for remediating sites contaminated by industrial liquids, has been extensively studied in the laboratory. The technology had not been demonstrated at a real site. Moreover, the ignition method (based on heat conduction) for the process used in the laboratory was not appropriate for field deployment and an alternative was required. This work first presents the development of a new ignition method for smouldering combustion. This ignition technique (based on heat convection) was proven effective via laboratory tests, and then applied and improved through two field tests. These field tests, conducted …

Second-Order Analysis Of Cable-Stayed Bridge Deck Slabs, Zachary Mcneil

Electronic Thesis and Dissertation Repository

Current provisions in CSA S6-06 “Canadian Highway Bridge Design Code” for computing second-order effects in slender concrete beam-columns were derived for columns in buildings, where these effects can often be neglected, so their applicability to extremely slender cable-stayed bridge decks warrants investigation. The research reported in this thesis first reviews the provisions in CSA S6-06, as well as eight equations proposed by others, for computing the flexural rigidity, EI, of slender concrete beam-columns. Methods for quantifying the rotational restraint provided at deck slab supports by steel or concrete floorbeams are presented and validated: steel floorbeams provide negligible restraint but …

Investigation Of Discharge Behaviour From A Sharp-Edged Circular Orifice In Both Weir And Orifice Flow Regimes Using An Unsteady Experimental Procedure, Phil R. Spencer

Electronic Thesis and Dissertation Repository

An unsteady experimental study was completed with the intention of identifying a transition region between partially full weir flow and fully developed orifice flow for a circular sharp-edged orifice. Three orifices of different diameter were tested. The head-discharge relationships were obtained by pressure recordings and directly compared by using dimensional analysis. The presence of true weir and orifice flow behaviour was evaluated by an original technique where the head exponent in the head-discharge relationship is considered. The study found that true orifice behaviour was achieved in the experiments. Correspondingly, based on the head exponent, no evidence was obtained to support …

Capacity Assessment Of A Transmission Tower Under Wind Loading, Thomas G. Mara

Electronic Thesis and Dissertation Repository

Transmission towers play a vital role in power distribution networks and are often subject to strong wind loads. Lattice tower design is often based on a linear elastic response to wind loading using methodology derived for atmospheric boundary layer (ABL) winds. A number of failures have been attributed to high intensity wind (HIW) events such as downbursts and tornadoes. This thesis investigates extreme winds on a self-supported lattice transmission tower and ultimately makes comparisons of the capacity under ABL and HIW. The force-deformation relation between the base shear and the displacement of the tip of the tower are used to …

Calibration Of Fatigue Design Wind Pressure For Sign, Luminaire, And Traffic Signal Support, Guigui Zu

Electronic Thesis and Dissertation Repository

The study is focused on calibration of fatigue design wind pressure for sign, luminaire and traffic signal support under natural and truck-induced wind gusts. The design of the support structures in Canada is governed by the current Canadian Highway Bridge Design Code (CHBDC). However, the code is not specific on the fatigue design wind pressure (natural or truck-induced) for these structures. Although there are equivalent static natural and truck-induced wind pressures for fatigue design recommended in the provisions of the American Association of State Highway and Transportation Officials (AASHTO), none of relevant studies discussed the implied reliability by using these …

Study Of Vertical Dense Jet Dilution In A Marine Environment, Nadeem Ahmad

Electronic Thesis and Dissertation Repository

Brine is a byproduct of many industrial and mining processes, including desalination. Brine is commonly conveyed in long pipe lines and disposed in the bottom of the sea through multiport diffusers, forming dense jets, also known as fountains. An acceptable level of brine concentration is required to be achieved at the boundary of a regulatory mixing zone surrounding a point of discharge. Such mixing zones are allocated with the objective of limiting environmental deterioration within their boundaries. Mixing zones are, nevertheless, not allowed when discharging brine in sensitive areas and when brine is toxic.

The main contribution of this study …

Numerical Evaluation Of Community-Scale Aquifer Storage, Transfer And Recovery Technology, Jessica Barker

Electronic Thesis and Dissertation Repository

Communities in the coastal regions of south-western Bangladesh currently experience severe seasonal water scarcity and groundwater sources of unsuitable salinity. Aquifer storage, transfer and recovery (ASTR), using a seasonal surplus of potable water, is being tested as a potential low-cost (less than $8000 USD) water supply alternative for these communities. A variable-density numerical groundwater model was developed to investigate the engineering technical feasibility of small-scale ASTR systems for the coastal communities in Bangladesh and specifically to support future field site selection and system design. The numerical model was calibrated based on an existing ASTR site and applied to explore the …

Stochastic Simulation Of Multiple-Station Ground Motions And Its Applications, Taojun Liu

Electronic Thesis and Dissertation Repository

Approaches to simulate single- and multiple-component multiple-station ground motion records with target spatial coherency and spatial correlation structures are developed for scenario events in this study. To develop the approaches, spatial correlation of the Fourier amplitude spectrum for a random orientation and for two orthogonal directions is assessed, and empirical equations are suggested. Moreover, spatial coherency of ground motions for two orthogonal horizontal directions is estimated using actual records from seven seismic events. Empirical coherency function is suggested for the components of records in two orthogonal horizontal directions at single and multiple recording stations. It was also found that the …

A System Dynamics Approach To Water Resources And Food Production In The Gambia, Jordan T. Atherton

Electronic Thesis and Dissertation Repository

The Gambia, a country in West African, faces an increasingly daunting situation. They do not produce enough food needed to feed the population, yet population growth remains high, and the current area of land under cultivation is approaching total arable land available. Climate changes complicate matters further as the majority of farms lack irrigation and are dependent on rainfall to provide water to their crops. The purpose of this thesis is to provide the first 1st iteration of a system dynamics model that could be useful as a tool to assist decision in the Gambia better understand long-term implications of …

Upgrading Pyrolysis Oil To Produce Liquid Transportation Fuels, Ehsan Reyhanitash

Electronic Thesis and Dissertation Repository

The effects of stabilizing fast pyrolysis oil via catalytic alcohol pretreatment on upgrading via hydrodeoxygenation or thermal treatment was studied by comparing the properties of upgraded-stabilized oils with those of upgraded-non-stabilized oils (benchmarks). The major expected effect was reduction in molar mass of upgraded oils, as stabilization was expected to reduce the reactivity of fast pyrolysis oil, thereby reducing polymerization. It was observed that molar mass reduction was induced by dilution effect of the alcohol rather than reactivity reduction due to stabilization. Also, the effects of different alcohols on stabilization and subsequent upgrading were examined at minimized dilution effect conditions. …

Treatment Of Aqueous Biomass And Waste Via Supercritical Water Gasification For The Production Of Ch4 And H2, Izad Behnia

Electronic Thesis and Dissertation Repository

The present study targets to convert aqueous fraction of fast pyrolysis oil into methane and hydrogen gases via supercritical water gasification (SCWG). Water above its critical point is referred to as supercritical water, which has unique properties such as a loss of hydrogen bonding, becoming an excellent solvent for organic compounds. In this thesis, SCWG was used to gasify slurry materials into high calorific gases including CH₄ and H₂. Production selectivity towards more methane or hydrogen was affectively controlled by operational conditions. However, in the absence of catalyst (bank test), gas formation was very minimal. SCWG of …

Fate Of Estrogens In Anaerobic Digestion And Their Removal In Advanced Oxidation, Shubhajit Sarkar

Electronic Thesis and Dissertation Repository

Estrogenic compounds are most significant endocrine disrupting compounds (EDC), which are of primary concern due to their widespread presence in the aqueous environment and also due to their adverse impact both on aquatic life and potential risk to human health. Conventional wastewater treatment plants are not designed to remove EDC, with biosorption on biosolids as the predominant removal mechanism. Anaerobic digestion is one of the most preferred processes employed for sludge stabilization in wastewater treatment plants. Advanced oxidation processes (AOPs) are seen as promising technologies for removal of estrogens from the environment. In this research, a controlled degradation study of …

Prediction Of Wind Loads On Tall Buildings: Development And Applications Of An Aerodynamic Database, Bernard Kim

Electronic Thesis and Dissertation Repository

The Western University Aerodynamic Database (WAD) has been developed as an alternative means for structural engineers to estimate the preliminary design wind loads on tall buildings. The database consists of aerodynamic loads obtained from either the force-balance or pressure model tests on 56 tall buildings in their simulated actual surroundings carried out in the Boundary Layer Wind Tunnel Laboratory at Western University. The data for a given building include the statistics of the normalized aerodynamic loads such as the means, root-mean squares, and power spectral density functions of the base bending moments in two orthogonal directions and base torque. To …

Application Of Mixed Iron Oxides In Subsurface Remediation Technologies, Saidur Rahman Chowdhury

Electronic Thesis and Dissertation Repository

Heavy metal contamination of soil and groundwater has been a concern in water supply and public health in many countries where the water supply system draws primarily from groundwater. In the present study, mixed maghemite-magnetite nanoparticles have been used as adsorbents for Cr(VI), As and Cd(II) removal. From the study, it is apparent that the removal of Cr(VI ), Cd(II) and As(V) by mixed iron oxide nanoparticles depends on pH, temperature, contact time, solid/liquid ratio and initial concentration of heavy metals. The results showed that Cr(VI) adsorption on mixed maghemite-magnetite was dependent on solution pH between 3 and 6. Theoretical …

Climate Change Impact On Flood Hazard In The Grand River Basin, Ontario, Canada, Abhishek Gaur

Electronic Thesis and Dissertation Repository

Rapidly changing climatic conditions across the globe are believed to have an impact on key climate variables and the hydrologic cycle. Changes in magnitude and frequency of peak flow patterns have been noted in rivers worldwide. The associated risk is projected to increase many folds during the 21^st century. Therefore, it is necessary to quantify these impacts for effective water resource planning and management in future. Methodology chosen to do so should be able to capture variations in climate variables at fine temporal, spatial and distributional scales. Also, it should be able to cover uncertainties associated with future climatic, …

Effect Of Groundwater-Lake Interactions On The Distribution Of Arsenic In A Freshwater Beach, Jacky Sk Lee

Electronic Thesis and Dissertation Repository

This thesis presents field measurements and numerical modeling that provide insight into the nearshore geochemical conditions and groundwater flows controlling the mobility of arsenic (As) in a freshwater beach aquifer and its potential discharge to Lake Erie. Field measurements were performed via shore-normal monitoring transects installed at beaches (Little Beach and Main Beach) located adjacent to a brownfield industrial harbour site that has elevated sediment and groundwater As concentrations. Detailed pore water chemistry analyses revealed elevated As (up to 0.056 mg/L) 1 - 2 m below the shoreline at all transect locations. The distributions of species in the aqueous and …