Civil and Environmental Engineering Commons^™

Railroad Condition Monitoring Using Distributed Acoustic Sensing And Deep Learning Techniques, Md Arifur Rahman

Electronic Theses and Dissertations

Proper condition monitoring has been a major issue among railroad administrations since it might cause catastrophic dilemmas that lead to fatalities or damage to the infrastructure. Although various aspects of train safety have been conducted by scholars, in-motion monitoring detection of defect occurrence, cause, and severity is still a big concern. Hence extensive studies are still required to enhance the accuracy of inspection methods for railroad condition monitoring (CM). Distributed acoustic sensing (DAS) has been recognized as a promising method because of its sensing capabilities over long distances and for massive structures. As DAS produces large datasets, algorithms for precise …

Simulation Of Wave Propagation In Granular Particles Using A Discrete Element Model, Syed Tahmid Hussan

Electronic Theses and Dissertations

The understanding of Bender Element mechanism and utilization of Particle Flow Code (PFC) to simulate the seismic wave behavior is important to test the dynamic behavior of soil particles. Both discrete and finite element methods can be used to simulate wave behavior. However, Discrete Element Method (DEM) is mostly suitable, as the micro scaled soil particle cannot be fully considered as continuous specimen like a piece of rod or aluminum. Recently DEM has been widely used to study mechanical properties of soils at particle level considering the particles as balls. This study represents a comparative analysis of Voigt and Best …

Investigating The Effect Of Bead Geometry On Fiber Orientation And Thermomechanical Properties For Large-Format Extrusion-Based Additive Manufacturing, Joanna F. Keaton

Electronic Theses and Dissertations

In large-format extrusion-based additive manufacturing of polymer composites, the relationship between material properties and processing parameters requires further investigation. This thesis focuses on the relationship between fiber orientation and thermomechanical properties for short fiber-filled thermoplastic polymer systems manufactured by extrusion-based additive manufacturing. Fiber orientation is particularly important in determining the thermomechanical properties of the composite material as properties in the direction of deposition are expected to be higher for highly aligned fibers than randomly aligned fibers. Fiber orientation distribution, which is related to processing parameters and deposition conditions, can be efficiently represented by the orientation tensor. The orientation tensor can …

Efficient Sintering Of Lunar Soil Using Concentrated Sunlight, Diprajit Biswas

Electronic Theses and Dissertations

Construction material is one crucial need for long-term habitation on the moon. When concentrated for high heat flux, solar radiation can heat lunar soil or regolith until it sinters at temperatures above 900°C. The solid, sintered soil simulant can be used as construction material. This work explores the conditions leading to effective lunar soil sintering for both direct and indirect irradiated sintering. Lunar soil simulants were sintered using concentrated light from a xenon-arc lamp with varying heat flux intensity. During direct sintering of LHS-1, a sintering range of 860°C-1140°C corresponding to a peak heat flux of 105-120 kW/m2 was identified …

Mechanics And Mechanisms Of Fracture For An Eastern Spruce Subject To Transverse Loading Using Acoustic Emission, Parinaz Belalpour Dastjerdi

Electronic Theses and Dissertations

Due to its excellent structural qualities and accessibility, wood is among the most often utilized structural materials. Despite its ubiquity, wood poses numerous challenges. It is heterogeneous and anisotropic. It has a complex hierarchical ultrastructure, and the properties can have wide variation within a species, and indeed within an individual tree. This work aims to improve our understanding of the strength and fracture behavior of spruce-pine-fir (south) (SPFs), particularly in cross-grain direction. This study’s primary goal is to examine the relationship between crack propagation and cross grain morphology under the following loading configurations: compact tension, compression, and rolling shear. The …

Optimization Of A Lightweight Floating Offshore Wind Turbine With Water-Ballast Motion Mitigation Technology, William Ramsay

Electronic Theses and Dissertations

Floating offshore wind turbines are a promising technology to address energy needs utilizing wind resources offshore. The current state of the art is based on heavy, expensive platforms to survive the ocean environment. Typical design techniques do not involve optimization because of the computationally expensive time-domain solvers used to model motions and loads in the ocean environment. However, this project uses an efficient frequency domain solver with a genetic algorithm to rapidly optimize the design of a novel floating wind turbine concept. The concept utilizes liquid ballast mass to mitigate motions on a lightweight post-tensioned concrete platform, with a target …

Joining Methods For Continuous Fiber Reinforced Thermoplastic Composites In Structural Applications, Andrew Moran

Electronic Theses and Dissertations

Continuous fiber reinforced thermoplastic (CFRTP) composites have been proposed as an alternative to metals in structural applications. CFRTP composites can be used to create structures that are lighter weight, have better resistance to environmental factors, and have the potential to be recycled. However, one of the main challenges to CFRTP composites is connections between structural members. The goal of this thesis is to investigate the feasibility of joining CFRTP composites to both similar and dissimilar materials through literature review, coupon testing, design of a structural joint, and a small scale laboratory prototype of the joint. To achieve this goal the …

Development Of Thermoplastic Composite External Reinforcing Of Concrete Decking System, Jackman A. Mickiewicz

Electronic Theses and Dissertations

The use of reinforced concrete is very common in the construction of a wide variety of structures. In buildings it is used for floors, beams, columns, and walls. It can also be used in infrastructure as parts of bridges, dams, pavements, etc. Typically, concrete is reinforced with steel, primarily rebar, to carry tensile stresses.

Like every other industry, construction is always looking at ways to advance its technology. The work outlined in this thesis looks to assist in that goal, primarily by looking at options for using a different material than the traditional steel reinforcements to create a reinforced concrete …

Thermal And Mechanical Numerical Modeling Of Extrusion-Based 3d Printed Reinforced Polymers For Selecting Manufacturing Process Parameters, Sunil Bhandari

Electronic Theses and Dissertations

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. …

Wave Attenuation Capacity Of Suspended Aquaculture Structures With Sugar Kelp And Mussels, Longhuan Zhu

Electronic Theses and Dissertations

Large aquaculture systems may have the potential to damp wave energy for coastal protection. The performance of these systems are influenced by the dynamics of components such as flexible kelp blades and mussel droppers. In this thesis, the dynamics of kelp blades and mussel droppers were investigated with a consistent-mass cable model with focus on understanding the asymmetric motion of kelp blades. The results showed the asymmetric blade motion in symmetric waves is caused by the spatial asymmetry of the encountered wave orbital velocities due to blade displacements and the asymmetric action on the blade by vertical wave orbital velocities. …

Selecting The Most Effective Energy Modeling Tool Based On A Project Requirement, Sodiq Akande

Electronic Theses and Dissertations

Building energy usage can be derived and controlled by performing building energy modeling. BEM can be performed using numerous software tools such as DesignBuilder, OpenStudio, EnergyPlus etc. These modeling tools can be sorted into three different modeling categories: Black-box, Gray-box and White-box. It is important for a modeler to be able to quickly select the proper tool from the proper category to meet the need of the project. To validate the method of categorizing tools, the three models generated using tools from each category and the modeling outputs required were compared. Each model was designed to estimate the amount of …

Designing And Testing 3-D Printed Wafer-Box With Embedded Pzt Sensors To Identify The Shape Effect On Energy Harvesting, Ahmad Jami Safayet

Electronic Theses and Dissertations

Piezoelectric energy has been recently paid attention in the field of alternative energy. Day by day the traditional energy sources including Coal tar and oils are becoming scarce. People are heading to an alternative energy source to meet the future energy demand. Piezoelectric energy is one of the competitive energy sources compared to the conventional renewable energy sources including solar, wind, and geothermal power and so on. This energy production method bears enormous research potential because it can be used as the roadway for a new method of power generation. This research project aimed to identify which shaped wafer-box produced …

Transformation Of Nonlinear Waves In The Presence Of Wind, Current, And Vegetation, Haifei Chen

Electronic Theses and Dissertations

Accurate prediction of extreme wave events is crucial for the safe maritime activities and offshore operations. Improved knowledge of wave dissipation mechanisms due to breaking and vegetation leads to accurate wave forecast, protecting life and property along the coast. The scope of the thesis is to examine the wave transformations in the presence of wind, current, and vegetation, using a two-phase flow solver based on the open-source platform OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with a Volume of Fluid (VOF) surface capturing scheme and a turbulence closure model. This RANS-VOF model is adapted to develop a numerical wind-wave-current …

Feasibility Of Using 3d Printed Molds For Thermoforming Thermoplastic Composites, Sunil Bhandari

Electronic Theses and Dissertations

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are:

1. a methodology for model-based performance evaluation of 3D printed structural parts, and
2. an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing.

The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D …

Audio-Based Productivity Forecasting Of Construction Cyclic Activities, Chris A. Sabillon

Electronic Theses and Dissertations

Due to its high cost, project managers must be able to monitor the performance of construction heavy equipment promptly. This cannot be achieved through traditional management techniques, which are based on direct observation or on estimations from historical data. Some manufacturers have started to integrate their proprietary technologies, but construction contractors are unlikely to have a fleet of entirely new and single manufacturer equipment for this to represent a solution. Third party automated approaches include the use of active sensors such as accelerometers and gyroscopes, passive technologies such as computer vision and image processing, and audio signal processing. Hitherto, most …

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared …

Enhancing Project Management With Lean World Class Manufacturing In Construction, Jacob Randles

Electronic Theses and Dissertations

In construction, the goal of commercial projects is to turn a profit. This is achieved by minimizing inputs and maximizing outputs while building a product that meets the customer’s perception of value. Value is determined through pre-negotiated specifications, plans, and material quality. Even in U.S. military construction, the unit executing the construction wants to complete the task on time and on budget, which can be difficult to do. Studies on project completion showcase a surprisingly high rate of failure in reaching the aforementioned “on time, on budget” goal. It is important to understand the nuances and details of U.S. Army …

Color Removal From Pulp Mill Effluent Using Coal Ash Produced From Georgia Power Coal Combustion Plants, Christopher B. Willett

Electronic Theses and Dissertations

Two environmental concerns currently face Georgia: coal fly ash (CFA) waste from coal power plants, and the effluent generated by pulp mills. Pulp mill effluent discolors surface waters into which it is discharged, and has been proven to negatively impact the dissolved oxygen and carbon necessary for aquatic life. The proposed solution is a cost-effective adsorption treatment using an inexpensive but abundantly available waste material: CFA. CFA possesses beneficial properties that allow it to effectively remove contaminants, and is available at significantly reduced cost. The primary research objective was to define treatment parameters that would result in the maximum removal …

Development Of A Scale Model Wind Turbine For Testing Of Offshore Floating Wind Turbine Systems, Heather Rae Martin

Electronic Theses and Dissertations

This thesis presents the development of a 1/50th scale 5 MW wind turbine intended for wind and wave basin model testing of commercially viable floating wind turbine structures. The design is based on a popular 5 MW wind turbine designed by the National Renewable Energy Laboratory (NREL) commonly utilized in numerical modeling efforts. The model wind turbine is to accompany generic floating model platforms for basin model testing. The ultimate goal of the model development testing program is to collect data for validating various floating wind turbine simulation codes such as those developed by NREL. This thesis will present an …