Engineering Commons^™

Enhancement Of Biohydrogen And Biomethane Production From Wastes Using Ultrasonication, Elsayed Elrefaey Elbeshbishy

Electronic Thesis and Dissertation Repository

This thesis demonstrated the feasibility of using ultrasonication to solubilize the particulate matter, suppress the growth of methanogens, and enrich the biohydrogen producers, thus overcoming the main challenge of biohydrogen systems i.e. long-term stability and contamination with methanogens. Furthermore, this work emphasized the benefits of applying ultrasonication inside a bioreactor over using it as a pretreatment for biohydrogen and biomethane production from wastes. The results of this work showed that sonicating hog manure at specific energy (SE) of 500 kJ/kg TS resulted in a 20% increase in methane production and 36% increase in VSS destruction. The viability of using ultrasonication …

A System Dynamics Based Integrated Assessment Modelling Of Global-Regional Climate Change: A Model For Analyzing The Behaviour Of The Social-Energy-Economy-Climate System, Mohammad Khaled Akhtar

Electronic Thesis and Dissertation Repository

The feedback based integrated assessment model ANEMI (version 2) represents the society-biosphere-climate-economy-energy system of the earth and biosphere. The development of the ANEMI model version 2 is based on the system dynamics simulation approach that (a) allows for the understanding and modelling of complex global change and (b) assists in the investigation of possible policy options for mitigating, and/or adopting to changing global conditions within an integrated assessment modelling framework. This thesis presents the ANEMI model version 2 and its nine individual sectors: climate, carbon cycle, land-use, population, food production, hydrologic cycle, water demand, water quality, and energy-economy. Two levels …

Thermal And Mechanical Studies Of Thin Spray-On Liner (Tsl) For Concrete Tunnel Linings, Taesang Ahn

Electronic Thesis and Dissertation Repository

The thesis presents a summary of Thin Spray-On Liner (TSL) effects on concrete. Three aspects, fire insulation, adhesion strength on concrete surface and load carrying capacity (i.e. flexural strength) on segmental concrete liners, are presented. Small-scale to full-scale laboratory tests were conducted using ASTM standards or devised methods. The TSL effects on three aspects were then compared with the results for uncoated concrete specimens. Numerical analyses using TEMP/W for the thermal response of TSL and a FE program, ABAQUS for the mechanical response of TSL were respectively carried out and compared with the measured results. Additionally, numerical analyses in respect …

Seismic Microzonation Of Great Toronto Area And Influence Of Building Resonances On Measured Soil Responses, Dimitar Genchev Mihaylov

Electronic Thesis and Dissertation Repository

A pilot seismic microzonation of the Greater Toronto Area (GTA) is used to establish the conditions and limitations of geophysical methods for site response investigations in city conditions. Maps of fundamental soil resonant frequencies, amplifications at these frequencies and interpolated average shear wave velocity of top 30 m of soil profile (VS- 30) used in soil classification were compared to the maps of drift thickness and surficial geology for the GTA. The non-applicability of the interpolated VS-30 map for site classification between measured test points is indicated. It is also shown that the soil response cannot be estimated properly using …

Vortex Shedding From Elongated Bluff Bodies, Zachary J. Taylor

Electronic Thesis and Dissertation Repository

As the spans of suspension bridges increase, the structures become inherently flexible. The flexibility of these structures, combined with the wind and particular aerodynamics, can lead to significant motions. From the collapse due to flutter of the Tacoma Narrows Bridge to the case of vortex-induced vibrations (VIV) of the Storebælt Bridge, it is evident that a better understanding of the aerodynamics of these geometries is necessary. The work herein is motivated by these two problems and is presented in two parts.

In the first part, the focus is on the physical mechanisms of vortex shedding. It is shown that the …

Investigation Of Hybrid Monopile-Footing Foundation Systems Subjected To Combined Loading, Mohamed El-Marassi

Electronic Thesis and Dissertation Repository

Laterally loaded structures such as wind turbines, offshore platforms, earth retaining structures, bridge abutments and many other structures impose complex loading regimes on the supporting foundations. These foundations are typically subjected to combinations of vertical, horizontal and moment loadings resulting from the vertical self-weight of the foundation system, superstructure, soil fill and surface surcharge, in addition to significant lateral loads and moments due to soil pressures, wind loads, waves and currents. In the case of shallow foundations, the weight and dimensions must be sufficient to resist tilting and sliding, whilst at the same time preventing failure of the subsoil and …

The Analysis Of Extreme Synoptic Winds, David A. Gatey

Electronic Thesis and Dissertation Repository

Time histories of wind speed and direction from 394 surface observation stations were obtained to calculate synoptic 50-year return period wind speeds for 11 countries in Europe. Preliminary investigation indicated wind speed differences along national borders were successfully reduced by application of a simple consistent methodology to wind speed data. This study considers the ideal methodology for calculating synoptic 50-year return period wind speeds.

Wind speed data requires standardisation through quality control measures, exposure correction and adjustment for disjunct sampling. A quality control algorithm was successfully applied to identify shifts of monthly mean wind speeds and data conversion issues. Three …

Geotechnique, Physico-Chemical Behaviour And A New Erosion Model For Mine Tailings Under Environmental Loading, Rozalina S. Dimitrova

Electronic Thesis and Dissertation Repository

Comprehensive geotechnical characterisation of mine tailings is required for the design, construction and safe operation of mine waste management facilities against the large number of potential failure risks. It is important that the characterization is carried out under the stress range and drainage conditions relevant to those encountered in the field.

The present research utilized mine tailings samples from a copper/nickel base-metal mine. Kaolinite and bentonite clays were added to the mine tailings in order to study the effect of clay percentage and clay mineralogy on the behaviour of saturated tailings/clay systems with varying composition. Slurries with moderate or high …

Vibration Isolation Using In-Filled Geofoam Trench Barriers, Ashref Mohamed A. Alzawi

Electronic Thesis and Dissertation Repository

A significant amount of numerical and experimental research has been conducted to study the vibration isolation by wave barriers considering open trenches, in-filled concrete or bentonite trenches, sheet-pile walls, and rows of piles. A few studies have investigated the use of expanded polystyrene (EPS) geofoam material as wave barriers, which indicated that in-filled geofoam trenches can be used as effective wave barriers. However, no engineering design method is available to date for the design of such type of wave barriers. This dissertation presents comprehensive experimental and numerical investigations on the use of in-filled geofoam trench barriers to scatter machine foundations …

Dynamic And Static Performance Of Large-Capacity Helical Piles In Cohesive Soils, Mohamed A. Elkasabgy

Electronic Thesis and Dissertation Repository

Large-capacity helical piles can provide immense construction and performance advantages over the conventional concrete and steel piles. Nowadays, there is significant interest in using large-capacity helical piles to support foundations that would be subjected to both dynamic and static loading.

The main objectives of this thesis are to: investigate the dynamic response and impedances of large-capacity helical piles; develop an analysis methodology for their dynamic response; and investigate their static axial compression and lateral behaviour, considering installation effects on their dynamic and static performances. The thesis presents the first full-scale vertical and horizontal dynamic field testing program executed on large-capacity …

Experimental And Numerical Development Of Anchor-Jointed Precast Structural Wall System And Optimum Design Of Prestressed Slabs, Mohamed El Semelawy

Electronic Thesis and Dissertation Repository

Precast concrete shear walls are used to resist lateral loads in low- to medium-rise buildings. An innovative joining technique is proposed to accelerate construction process and to reduce concrete damage possibility and capital loss during an earthquake event. Panels are jointed using steel anchor bolts, therefore, the system is designated "anchor-jointed precast structural wall system". In this system, anchors are utilized as a structural fuse. Damaged anchors are easily replaced after an earthquake, thus minimizing repair costs and serviceability disruptions. In the first part of this thesis, conceptual development of the system is carried out. A research program of combined …

Uncertainty Estimation Of Extreme Precipitations Under Climate Change: A Non-Parametric Approach, Tarana A. Solaiman

Electronic Thesis and Dissertation Repository

Assessment of climate change impacts on hydrology at watershed scale incorporates (a) downscaling of global scale climatic variables into local scale hydrologic variables and (b) assessment of future hydrologic extremes. Atmosphere-Ocean Global Climate Models (AOGCM) are designed to simulate time series of future climate responses accounting for human induced green house gas emissions. The present study addresses the following limitations of climate change impact research: (i) limited availability of observed historical information; (ii) limited research on the detection of changes in hydrologic extremes; and (iii) coarse spatio-temporal resolution of AOGCMs for use at regional or local scale. Downscaled output from …

Early-Age Shrinkage Of Ultra High-Performance Concrete: Mitigation And Compensating Mechanisms, Ahmed Mohammed Soliman

Electronic Thesis and Dissertation Repository

The very high mechanical strength and enhanced durability of ultra high-performance concrete (UHPC) make it a strong contender for several concrete applications. However, UHPC has a very low water-to-cement ratio, which increases its tendency to undergo early-age shrinkage cracking with a risk of decreasing its long-term durability. To reduce the magnitude of early-age shrinkage and cracking potential, several mitigation strategies have been proposed including the use of shrinkage reducing admixtures, internal curing methods (e.g. superabsorbent polymers), expansive cements and extended moist curing durations. To appropriately utilize these strategies, it is important to have a complete understanding of the driving forces …

Investigation On Rheology Of Oil Well Cement Slurries, Anjuman Shahriar

Electronic Thesis and Dissertation Repository

The rheology of OWC slurries is generally more complicated than that of conventional cement paste. In order to contend with bottom hole conditions (wide range of pressure and temperature), a number of additives are usually used in the OWC slurries and the slurry shows different characteristics depending on the combination of admixture used. The objective of this research is to develop a fundamental understanding on the important mechanisms that affects the rheology of cement slurry incorporating various chemical and mineral admixtures. The thesis aimed at developing cement slurries by partial replacement of oil well cement using different mineral admixtures, offering …

Biological Nutrient Removal From Municipal And Industrial Wastewater Using A Twin Circulating Fluidized Bed Bioreactor, Mehran Andalib

Electronic Thesis and Dissertation Repository

Biological nutrient removal (BNR) refers to removal of carbon (C), nitrogen (N) and phosphorus (P) from wastewater (WW) by the aid of various microorganisms. Because of the public concern for the environment C, N and P effluent standards have become stricter. Different BNR processes such as suspended growth and attached growth have been studied during the last three decades in order to meet the increasingly stringent discharge standards.

In this work, two novel processes called Twin Fluidized Bed Bioreactor (TFBBR) and Twin Circulating Fluidized Bed Bioreactor (TCFBBR) were developed and tested for BNR from municipal WW. Both TFBBR and TCFBBR …

Evaluation Of Wind-Induced Resuspension On The Performance Of A Mine Tailings Storage Facility, Laxmi Kant Kachhwal

Electronic Thesis and Dissertation Repository

Proper management of sulphide rich reactive mine tailings is a growing concern for mining industries. Oxidation of tailings can release acids and toxic metals into the surroundings, which can potentially pollute the ecosystem. Confining tailings under shallow water covers is one of the most successfully applied technologies for long-term storage. The water has lower solubility and diffusivity of oxygen than air and can significantly reduce the influx of oxygen to the bed tailings. However, wind-induced waves and currents in the water can resuspend bed tailings and ultimately result in oxidation.

Extensive field investigations were carried out to evaluate the performance …

The Behaviour Of Cement Stabilized Clay At High Water Contents, Saeed Sasanian

Electronic Thesis and Dissertation Repository

Artificial cementation of soft clays has been used for several years for different ground improvement projects. Although considerable work has been done to develop advanced machinery and techniques for the implementation of artificial cementation, less knowledge is available on the mechanisms involving the formation of the artificial structure and the resulting mechanical behaviour. The primary objectives of the present work were to investigate the formation of microstructure in artificially cemented material with Portland cement, find the relationships between cementitious bonding and clay mineralogy, and create constitutive frameworks for predicting the mechanical behaviour of cement-treated clays.

Qualitative and quantitative microstructural characterisation …

Numerical Simulation Of Tornado-Like Vortices, Diwakar Natarajan

Electronic Thesis and Dissertation Repository

The thesis investigates by numerical simulation the flow characteristics of tornado like vortices produced by three types of vortex generators, namely, Ward-type Tornado Vortex Chamber (TVC), WinDEEE Dome and Atmospheric Vortex Engine (AVE).

Laboratory scale (Ward-type TVC) tornado-like vortices were simulated for swirl ratios 0.1 to 2.0 using the CFD code Fluent 6.3. The simulations with Reynolds stress model compare well with past experimental results. Multiple vortices were observed for high swirl ratios in LES simulation. These simulations have generated a comprehensive benchmark data for future modelers and experimenters.

The effects of translation and surface roughness on laboratory scale tornado-like …