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Full-Text Articles in Engineering

Experimental Simulation Of Density-Driven Thunderstorm Downbursts, Roghayyeh Babaei Koli Apr 2018

Experimental Simulation Of Density-Driven Thunderstorm Downbursts, Roghayyeh Babaei Koli

Electronic Thesis and Dissertation Repository

Evaporative cooling of the precipitation within the thunderstorm cloud results in the formation of a mass of cold and dense air which moves toward the ground and after impingement turns into strong radial winds near the surface. In this study, an experimental approach was taken to investigate the downbursts. The two-fluid model was used, and the various features of the experimental setup of previous researchers were modified to incorporate the specifications of natural downbursts. First, two new release cylinders were manufactured and their capabilities in producing repeatable and symmetric outflows were examined. Then, the effects of cylinder wall design, density ...


Hybrid Attitude Control And Estimation On So(3), Soulaimane Berkane Nov 2017

Hybrid Attitude Control And Estimation On So(3), Soulaimane Berkane

Electronic Thesis and Dissertation Repository

This thesis presents a general framework for hybrid attitude control and estimation design on the Special Orthogonal group SO(3). First, the attitude stabilization problem on SO(3) is considered. It is shown that, using a min-switch hybrid control strategy designed from a family of potential functions on SO(3), global exponential stabilization on SO(3) can be achieved when this family of potential functions satisfies certain properties. Then, a systematic methodology to construct these potential functions is developed. The proposed hybrid control technique is applied to the attitude tracking problem for rigid body systems. A smoothing mechanism is proposed ...


Free-Surface Wall-Jet Flow At Moderate Reynolds Number As Applied To Slot And Blade Coating, Mohammad Tanvir Hossain Nov 2017

Free-Surface Wall-Jet Flow At Moderate Reynolds Number As Applied To Slot And Blade Coating, Mohammad Tanvir Hossain

Electronic Thesis and Dissertation Repository

The flow of a two-dimensional steady wall jet observed in the slot and blade coating processes has been examined theoretically near the channel exit. The Newtonian free surface jet emerges from a channel and deposits onto an infinite moving wall with an adverse or favorable pressure gradient applied inside the channel. The Reynolds number considered is within the moderate range, and fully developed Couette-Poisueille flow conditions are assumed to prevail far upstream inside the channel. The effects of inertia and pressure gradient on the velocity, the shape of the free surface, and the stress are emphasized. It is found that ...


Metal Sulfides As Anode For Lithium Ion And Sodium Ion Battery, Ali Abdulla Oct 2017

Metal Sulfides As Anode For Lithium Ion And Sodium Ion Battery, Ali Abdulla

Electronic Thesis and Dissertation Repository

Abstract

Nanomaterials have been studied intensively in the last decades due to their unique physical and chemical properties and their potential for applications in different domains. Among these applications, energy storage has become the center of focus by many research groups and companies to develop high efficiency and reliable energy devices such as the commercial lithium ion batteries (LIBs). However, LIBs has not yet met the growing requirements of the high demand for increasing energy density. More efforts are requested to improve the performance of the batteries by designing better electrode materials and increasing the battery safety. Another type of ...


Influence Of Scapular Notching On Contact Mechanics And Simulator Wear Of Reverse Total Shoulder Arthroplasty Implants, Michael William Griffiths Oct 2017

Influence Of Scapular Notching On Contact Mechanics And Simulator Wear Of Reverse Total Shoulder Arthroplasty Implants, Michael William Griffiths

Electronic Thesis and Dissertation Repository

Scapular notching is a common complication of reverse total shoulder arthroplasty (RTSA) wherein the predominant focus of current literature has been on changes in osseous anatomy. However, the implications on RTSA performance from the damaged humeral cup is largely unknown. Therefore the present work describes the effects of the initiation and propagation of the humeral cup defect resulting from scapular notching through the use of finite element modeling and wear simulation, in order to assess changes in RTSA contact mechanics and tribological properties. A significant decrease in articular contact area and increase in maximum contact stress values was found for ...


Influence Of Turbulence On The Aerodynamics Of Low-Rise Buildings, Fakhruzzaman Arif Sep 2017

Influence Of Turbulence On The Aerodynamics Of Low-Rise Buildings, Fakhruzzaman Arif

Electronic Thesis and Dissertation Repository

During extreme wind events, roofing failures may lead to damage of the whole structure. In order to alleviate the effect, surface pressure coefficients on the roofs have been extensively investigated. This research aims to determine the roof pressures acting on low-rise buildings with consideration of the effects of turbulence (terrain). Pressure measurements, as well as wind speed data, were taken at the Boundary Layer Wind Tunnel Laboratory (BLWTL) of the University of Western Ontario (UWO) to examine the influence of turbulence level (i.e., terrain condition) on the critical wind directions corresponding to the largest surface roof pressure coefficients for ...


The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet Sep 2017

The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet

Electronic Thesis and Dissertation Repository

The motivation of this thesis is the development of simple microscopic-scale model (representative elemental volume; REV) that can be used to conduct flow and heat transfer simulations from which closure coefficients can be established for the volume-averaged transport equations for porous media (packed bed). The thesis provides a brief introduction to the computational technique adopted for the geometric generation of the REV (YADE), followed by a parametric study undertaken to reveal the minimum number of particles inside the REV that are required to mimic the appropriate physics. Additional analysis was conducted with the goal of determining the influence of deviation ...


3d Printing Of Functional Materials: Surface Technology And Structural Optimization, Dongxing Zhang Sep 2017

3d Printing Of Functional Materials: Surface Technology And Structural Optimization, Dongxing Zhang

Electronic Thesis and Dissertation Repository

There has been a surge in interest of 3D printing technology in the recent 5 years with respect to the equipment and materials, because this technology allows one to create sophisticated and customized parts in a manner that is more efficient regarding both material and time consumption. However, 3D printing has not yet become a mainstream technology within the established manufacturing routes. One primary factor accounting for this slow progress is the lack of a broad variety of 3D printable materials, resulting in limited functions of 3D printed parts.

To bridge this gap, I present an integrated strategy to fabricate ...


Numerical Simulations Of Two-Phase Flows In The Liquid Solid Circulating Fluidized Bed, Hao Luo Sep 2017

Numerical Simulations Of Two-Phase Flows In The Liquid Solid Circulating Fluidized Bed, Hao Luo

Electronic Thesis and Dissertation Repository

The liquid-solid circulating fluidized bed (LSCFB) has many potential applications in biochemical and petroleum industries, as well as in wastewater treatments, given its higher contact efficiency and being able to accommodate two reactions under one system. With extensive experimental results becoming available, there is clearly a need for computational fluid dynamics (CFD) modeling to expand our understandings of LSCFBs and to predict the hydrodynamic behaviors of the two-phase flows within LSCFB.

In this research, the Eulerian-Eulerian two-phase model combined with the kinetic theory for the granular phase is applied to simulate the two-phase flows in LSCFBs. The key factors affecting ...


Experimental Measurements Of Far Field Cough Airflows Produced By Healthy And Influenza- Infected Human Subjects, Ahmed Faraj Alarbi Mohamed Sep 2017

Experimental Measurements Of Far Field Cough Airflows Produced By Healthy And Influenza- Infected Human Subjects, Ahmed Faraj Alarbi Mohamed

Electronic Thesis and Dissertation Repository

The present work details an experimental study of the cough airflow fields produced by subjects infected with influenza and when they are convalescent, together with data from healthy cohorts. The PIV and HWA measurements were taken far downstream at 1 m from the source within a cough chamber, along with droplet sampling at two different locations and nasal swabs from the sick subjects. The measured data over different seasons were used to evaluate and compare the results from sick, convalescent and healthy subjects. Although a total of 8 sick participants from winter 2014 and 2017 yielded positive nasal swab analysis ...


The Onset Of Convection In Rarefied Gases, Md Asif Zobaer Sep 2017

The Onset Of Convection In Rarefied Gases, Md Asif Zobaer

Electronic Thesis and Dissertation Repository

The onset of convection in the Rayleigh-Bénard problem for a monatomic rarefied gas at small Knudsen number has been investigated. Compressibility-induced density variations have been considered without imposing any restriction on the magnitude of temperature difference. A linear temporal stability analysis has been conducted for a compressible slip-flow model considering a Maxwellian gas and the dispersion relation is calculated using a Chebyshev collocation method. A neutral stability curve obtained in the Froude-Knudsen number plane marks transition to convection from a pure conduction state. The critical wave number observed for the onset of convection is in good agreement with the existing ...


Additive Manufacturing Process Of 3d Polyaniline Transducers Via Direct Ink Writing, Frederick Benjamin Holness Aug 2017

Additive Manufacturing Process Of 3d Polyaniline Transducers Via Direct Ink Writing, Frederick Benjamin Holness

Electronic Thesis and Dissertation Repository

Electroactive polymers exhibit a change in properties, typically size or shape, in response to electrical stimuli. One class of electroactive polymer of particular interest are the conjugated polymers, whose conjugated backbone structure imparts electrical conductivity. However, this structure imposes processing limitations restricting their form to 2D structures. To overcome this, we develop specially formulated polyaniline- based blends via counter-ion induced thermal doping for the fabrication of 3D conductive structures via direct ink writing. This approach employs multi-material extrusion for the production of structures with passive and active features, rapid device fabrication, and improved design freedom. A model of the thermal ...


Flow Characterization Under Idealized Stenosis Geometry And Performance Assessment Of The Hemodynamic Flow Facility, Marin Vratonjic Jul 2017

Flow Characterization Under Idealized Stenosis Geometry And Performance Assessment Of The Hemodynamic Flow Facility, Marin Vratonjic

Electronic Thesis and Dissertation Repository

It is well known that regions inside the human arterial network susceptible to atherosclerosis experience a complex flow environment. Endothelial Cells (ECs) lining the inner wall of arteries are sensors to spatially and temporally varying shear stress (i.e. wall shear stress gradients). This complex force-loading can disrupt local cell-to-cell attachment regions triggering a cascade of biological events leading to the formation of atherosclerotic lesions. Consequently, researchers predominantly use a Parallel Plate Flow Chamber (PPFC) to study the hemodynamic-cell cycle relationship due to its simplicity and ability to achieve a two-dimensional fully-developed steady laminar flow across the cell monolayer. Researchers ...


Full-Scale And Wind Tunnel Investigation Of The Flow Field Over A Coastal Escarpment, Julien Lotufo May 2017

Full-Scale And Wind Tunnel Investigation Of The Flow Field Over A Coastal Escarpment, Julien Lotufo

Electronic Thesis and Dissertation Repository

A multiscale experimental approach, consisting of full-scale measurements and physical modeling in a laboratory environment, was conducted to investigate the flow field over a coastal escarpment on the Wind Energy Institute of Canada’s research and development wind park. The influence of sea breeze inflow conditions, thermal stability and local topographic features on the flow field were examined.

The results of the full-scale study show that the near surface flow field is significantly influenced by the sea breeze circulatory coastal flow regime, creating larger shear layers with a smaller recirculation regions compared to cases of typical boundary layer flow typical ...


Effects Of Turbulence On The Separating-Reattaching Flow Above Surface-Mounted, Three-Dimensional Bluff Bodies, Abul Fahad Akon Mar 2017

Effects Of Turbulence On The Separating-Reattaching Flow Above Surface-Mounted, Three-Dimensional Bluff Bodies, Abul Fahad Akon

Electronic Thesis and Dissertation Repository

Investigations of separated and reattaching flows over three-dimensional bluff bodies in turbulent boundary layers are important because of the large aerodynamic loads that these flows cause. For example, roofs of low-rise buildings are vulnerable to this kind of wind loading. Turbulence in the upstream flow affects the pressure distributions and the mean size of separation bubbles formed on bluff body surfaces. Whereas a number of studies have focussed on two-dimensional separation bubbles and surface pressures, a comprehensive understanding of the surface pressures and the separating-reattaching flows in relation to the turbulence in the incident boundary layers for surface-mounted, three-dimensional bluff ...


Convection In Corrugated Slots, Seyed Arman Abtahi Feb 2017

Convection In Corrugated Slots, Seyed Arman Abtahi

Electronic Thesis and Dissertation Repository

This thesis consists of two parts. The first part deals with the development of proper methodology, i.e. a spectrally accurate algorithm suitable for analysis of convection problems in corrugated slots. The second part is devoted to the study of natural convection in corrugated slots.

The algorithm uses the immersed boundary conditions (IBC) concept to deal with the irregular form of the solution domain associated with the presence of corrugated plates. The field equations are discretized on a regular domain surrounding the flow domain using Fourier expansions in the horizontal direction and Chebyshev expansions in the vertical direction. The boundary ...


Fabrication Of Large Mechanically Flexible Multi-Layered Pdms Optical Devices, Robert S. Green Sep 2016

Fabrication Of Large Mechanically Flexible Multi-Layered Pdms Optical Devices, Robert S. Green

Electronic Thesis and Dissertation Repository

Mechanically flexible large area polydimethylsiloxane (PDMS) optical devices are fabricated using soft-lithography techniques based on replica moulding. These non-rigid optical devices can be designed as sheets to act as either light concentrators (collectors) or diffusers (illuminators) based on the position and geometry of micro-optical structures (MOSs) embedded within the sheet or imprinted on its surface. The active surface area of the device can range from less than a sq. cm to several sq. m. The performance of the large area optical device is a function of the location and geometry of micro-optical structures, thickness and shape of the flexible waveguide ...


Controlled Guidance Of Light In Large Area Flexible Optical Waveguide Sheets, Chloë O. Nicholson-Smith Sep 2016

Controlled Guidance Of Light In Large Area Flexible Optical Waveguide Sheets, Chloë O. Nicholson-Smith

Electronic Thesis and Dissertation Repository

Large surface area, thin, polymer optical waveguides are an emerging technology that enable a wide variety of light collection and illumination systems to be created for passive lighting, solar collectors, and safety lighting for motorized vehicles. This research builds on design of rigid concentrator and diffuser waveguides, proposing and evaluating modifications for the design of a flexible waveguide combining both concentrating and diffusing functionalities. The waveguides are thin, mechanically flexible sheets with thicknesses in the range of mm, and active surfaces from a few cm2 to several m2. Regions of the functional surface are designed to act as ...


Numerical Studies For Improving Fracture Toughness Resistance Curve Testing Using Single-Edge (Notched) Tension Specimens, Yifan Huang Sep 2016

Numerical Studies For Improving Fracture Toughness Resistance Curve Testing Using Single-Edge (Notched) Tension Specimens, Yifan Huang

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve, i.e. the J-integral resistance curve (J-R curve) or the crack tip opening displacement resistance (CTOD-R) curves, is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). This thesis deals with issues related to the experimental determination of the J(CTOD)-R curves using the newly-developed single-edge (notched) tension (SE(T)) specimens. In the first study, the plastic geometry factor, i.e. the ηpl factor, used to evaluate J in a J-R curve test based on the SE(T ...


Parametric Design, Modeling, And Optical Evaluation Of Retroreflective Prismatic Structures, Sama Hussein Aug 2016

Parametric Design, Modeling, And Optical Evaluation Of Retroreflective Prismatic Structures, Sama Hussein

Electronic Thesis and Dissertation Repository

Retroreflectors (RR) are defined as passive optical structures that redirect incident light to its originating source. Specific types of retroreflectors called inverted cubes (ICs) function through total internal reflection (TIR) and are used in various applications such as measurement tools, traffic signs and automotive rear and side lighting. This thesis aims to model, analyze, fabricate and study a novel type of IC retroreflectors called right triangular prism (RTP). A parametric approach is used to model existing IC geometries from a generic unit cube and is then implemented to model the novel RTP geometry. Those elements are then tested by optical ...


Ultraprecise Single Point Inverted Cutting Strategies For Multi-Axis Fabrication Of Right Triangular Prismatic Retroreflectors, Benjamin W. Hamilton Aug 2016

Ultraprecise Single Point Inverted Cutting Strategies For Multi-Axis Fabrication Of Right Triangular Prismatic Retroreflectors, Benjamin W. Hamilton

Electronic Thesis and Dissertation Repository

The optical phenomenon of retroreflection (RR) is described as light rays contacting a surface and being redirected back to their originating source. While applications are many and varied, their primary focus is safety in low-light conditions, and the focus of this research is toward automotive applications. Few geometric shapes are capable of retroreflection. Among them are the lens-and-mirror, and cube corner geometry; however, the right triangular prism (RTP) has been introduced as a viable alternative. This study demonstrates a more efficient fabrication technology when compared to current industry practices.

The ultraprecise single point inverted cutting (USPIC) technology was envisioned as ...


Hybrid Magneto-Rheological Actuators For Human Friendly Robotic Manipulators, Masoud Moghani Jul 2016

Hybrid Magneto-Rheological Actuators For Human Friendly Robotic Manipulators, Masoud Moghani

Electronic Thesis and Dissertation Repository

In recent years, many developments in the field of the physical human robot interaction (pHRI) have been witnessed and significant attentions have been given to the subject of safety within the interactive environments. Ensuring the safety has led to the design of the robots that are physically unable to hurt humans. However, Such systems commonly suffer from the safety-performance trade-off. Magneto-Rheological (MR) fluids are a special class of fluids that exhibit variable yield stress with respect to an applied magnetic field. Devices developed with such fluids are known to provide the prerequisite requirements of intrinsic safe actuation while maintaining the ...


The Effect Of Mesh-Type Bubble Breakers On Two-Phase Vertical Co-Flow, Alan Kalbfleisch Jun 2016

The Effect Of Mesh-Type Bubble Breakers On Two-Phase Vertical Co-Flow, Alan Kalbfleisch

Electronic Thesis and Dissertation Repository

It is proposed that mesh-type bubble breakers can be used in two-phase gas-liquid vertical cocurrent pipe flow to enhance the heat and mass transfer rates. Two experimental studies were performed to investigate the effect of mesh-type bubble breakers with varying geometries on two-phase flow behaviour. The first used highspeed imaging to measure bubble size and observe the resulting flow regime for two-phase vertical co-flow consisting of air and water. A Froude number correlation that can be used to predict the bubble size generated by mesh-type bubble breakers is proposed. Flow regime maps for two-phase flow in the presence of bubble ...


Characterization Of Mean And Turbulent Flow Over Complex Topography Under Various Inflow And Geometric Configurations, Ryan J. Kilpatrick May 2016

Characterization Of Mean And Turbulent Flow Over Complex Topography Under Various Inflow And Geometric Configurations, Ryan J. Kilpatrick

Electronic Thesis and Dissertation Repository

An experimental investigation of flow over a complex topography was undertaken to study the influence of inflow conditions including Reynolds number, upstream roughness, and inflow shear profile on mean and turbulent flow behaviour.

Large-scale physical testing was employed over the escarpment of a hill, covering a Reynolds number range of 3.6×104 to 5.2×105. Measurements taken using Particle Image Velocimetry (PIV) and Cobra Probes were analyzed in terms of mean and turbulent statistics. Coherent structures were characterized through Proper Orthogonal Decomposition (POD).

The results show that the Reynolds number had little effect on the flow ...


Thermal Modeling For Light Armored Vehicle, Marc-André H. Brooks May 2016

Thermal Modeling For Light Armored Vehicle, Marc-André H. Brooks

Electronic Thesis and Dissertation Repository

Light Armored vehicles are required to operate in a variety of extremely hot and arid climates. As such, these vehicles are often subject to large heat gains due to environmental factors. The current systems employed for vehicle cooling do not always perform to the levels that are required, mainly due to the lack of a good estimate of the cooling load. A thermal analog circuit was created which separated each of the heat sources into its own module. Using material properties provided by General Dynamics Land Systems as well as information from acquired from CFD studies and ASHRAE, the values ...


Experimental Investigation Of The Melting Behavior And The Transient Heat Transfer In A Phase Change Material (Pcm), Mohammad A. Bashar Apr 2016

Experimental Investigation Of The Melting Behavior And The Transient Heat Transfer In A Phase Change Material (Pcm), Mohammad A. Bashar

Electronic Thesis and Dissertation Repository

Phase change materials (PCMs) used in thermal energy storage (TES) system as heat storage media can play crucial role in various engineering applications. PCMs have the inherent ability to store large amount of heat by exploiting their heat of fusions, predominantly during their solid-liquid phase-change period. The present study reports an experimental investigation on the melting process in a PCM and the associated heat transfer in a transient manner. The experiments were conducted in a rectangular chamber filled with paraffin wax used as the PCM and, a cylindrical copper tube with different geometries and orientations as the heat source.

The ...


Numerical Investigation Of Full Scale Thunderstorm Downbursts: A Parametric Study And Comparison To Meteorological Model, Christopher Oreskovic Apr 2016

Numerical Investigation Of Full Scale Thunderstorm Downbursts: A Parametric Study And Comparison To Meteorological Model, Christopher Oreskovic

Electronic Thesis and Dissertation Repository

A series of Large Eddy Simulations using an atmospheric meteorological cloud model have been used to investigate the important geometric and thermal parameters that influence a thunderstorm downburst outflow, as it pertains specifically to the idealized cooling source model. A separate set of Large Eddy Simulations make use of the same idealized cooling source model, in a realistic atmospheric base state using real field sounding data, in an attempt to make a quantifiable comparison to a downburst from a full cloud simulation. Randomness has been added to the cooling source forcing function to mimic the thermal variation in a real ...


A Model For Complex Heat And Mass Transport Involving Porous Media With Related Applications, Furqan A. Khan Apr 2016

A Model For Complex Heat And Mass Transport Involving Porous Media With Related Applications, Furqan A. Khan

Electronic Thesis and Dissertation Repository

Heat and mass transfer involving porous media is prevalent in, for example, air-conditioning, drying, food storage, and chemical processing. Such applications require non-equilibrium heat and mass (or moisture) transfer modeling inside porous media in conjugate fluid/porous/solid framework. Moreover, modeling of turbulence and turbulent heat and mass transfer becomes essential for many applications. A comprehensive literature review shows a scarcity of models having such capabilities. In this respect, the objectives of the present thesis are to: i) develop a formulation that simulates non-equilibrium heat and mass transfer in conjugate fluid/porous/solid framework, ii) demonstrate the capabilities of the ...


Optimizing The Rehabilitation Of Elbow Lateral Collateral Ligament Injuries, Ranita Harpreet Kaur Manocha Mar 2016

Optimizing The Rehabilitation Of Elbow Lateral Collateral Ligament Injuries, Ranita Harpreet Kaur Manocha

Electronic Thesis and Dissertation Repository

Elbow lateral collateral ligament (LCL) injuries frequently arise following trauma, and can result in disabling instability. Typically such injuries are managed with immobilization followed by a graduated exercise regime; however there is minimal biomechanical evidence to support current treatment protocols. This investigation examines the in vitro effectiveness of several rehabilitation techniques using a custom elbow motion simulator. It was found that active range of motion is safest in the overhead position (n = 7). Early motion in this position may reduce the incidence of elbow stiffness without compromising ligament healing following LCL injury. Forearm pronation and active motion stabilize the LCL-deficient ...


Application Of Natural Convection For Photovoltaic Cooling And Photocatalytic Disinfection, Usman J. Rajput Mar 2016

Application Of Natural Convection For Photovoltaic Cooling And Photocatalytic Disinfection, Usman J. Rajput

Electronic Thesis and Dissertation Repository

Two investigations for improving renewable technologies are engaged. First is the examination of the enhancement of heat transfer at the rear of a hot photovoltaic panel by natural convection using various configurations and the other is analyzing a new photocatalytic collector for water heating and cleaning. A 20 Watt polycrystalline panel is exposed to indoor simulated solar light, under constant ambient temperature and stagnant wind conditions. Three configurations are considered: a partial heat sink, a water cavity and a water channel. The experimentally obtained convective heat transfer coefficients are 4.4 W•m-2•K-1 at the rear of ...