Engineering Commons^™

Multiscale Modeling Of Electrolytes For Energy Storage And Conversion, Fatemeh Sepehr

Doctoral Dissertations

Fuel cells, redox flow batteries, and secondary ion batteries are under active investigation to fulfill the requirements of efficient and sustainable energy storage and conversion technologies. The discovery of high-performance stable electrolytes that are relatively cheap and versatile is crucial to the commercialization of these electrochemical devices and necessitates a comprehensive understanding of the materials (i.e., from the atomistic to continuum levels). This dissertation is on multiscale modeling and simulations of several electrolytes under consideration in vanadium redox flow batteries (VRFBs), alkaline fuel cells (AFCs), or secondary magnesium batteries.

The hydrated structure and associated solvation Gibbs energies were determined for …

Adaptive Sampling Trust-Region Methods For Derivative-Based And Derivative-Free Simulation Optimization Problems, Sara Shashaani

Open Access Dissertations

We consider unconstrained optimization problems where only “stochastic” estimates of the objective function are observable as replicates from a Monte Carlo simulation oracle. In the first study we assume that the function gradients are directly observable through the Monte Carlo simulation. We propose ASTRO, which is an adaptive sampling based trust-region optimization method where a stochastic local model is constructed, optimized, and updated iteratively. ASTRO is a derivative-based algorithm and provides almost sure convergence to a first-order critical point with good practical performance. In the second study the Monte Carlo simulation is assumed to provide no direct observations of the …

Simulation Modeling For Energy Consumption Of Residential Consumers In Response To Demand Side Management., Prajwal Khadgi

Electronic Theses and Dissertations

Energy efficiency in the electricity distribution system continues to gain importance as demand for electricity keeps rising and resources keep diminishing. Achieving higher energy efficiency by implementing control strategies and demand response (DR) programs has always been a topic of interest in the electric utility industry. The advent of smart grids with enhanced data communication capabilities propels DR to be an essential part of the next generation power distribution system. Fundamentally, DR has the ability to charge a customer the true price of electricity at the time of use, and the general perception is that consumers would shift their load …

Predicting The Performance Of Queues: A Data Analytic Approach, Kum Khiong Yang, Cayirli Tugba, Mei Wan Low

Research Collection Lee Kong Chian School Of Business

Existing models of multi-server queues with system transience and non-standard assumptions are either too complex or restricted in their assumptions to be used broadly in practice. This paper proposes using data analytics, combining computer simulation to generate the data and an advanced non-linear regression technique called the Alternating Conditional Expectation (ACE) to construct a set of easy-to-use equations to predict the performance of queues with a scheduled start and end time. Our results show that the equations can accurately predict the queue performance as a function of the number of servers, mean arrival load, session length and service time variability. …

Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln

Theses and Dissertations

Computer simulation is a useful tool in the research and treatment of basilar aneurysms. Current technology allows researchers to create 3D models from cerebral vasculature in-vivo, allowing for the investigation of surgical options with minimal risk to the patient. The method used to construct these models overlooks smaller lateral arterial branches which are difficult to discern due to resolution limits of the imaging process. These lateral branches have minimal impact on the overall blood flow through the basilar artery, but they play a significant role in the health of the patient, so it is important to ensure sufficient blood will …

Exploratory Assessment Of Roadway Infrastructure Adaptation To The Impacts Of Sea-Level Rise, Mostafa Batouli

FIU Electronic Theses and Dissertations

Transportation agencies in coastal urban areas face a significant challenge to enhance the long-term resilience of their networks to flooding and storm surge events exacerbated by sea level rise. The problem of sea-level rise adaptation is characterized by deep uncertainty that makes it complex to assess the value of adaptation investments. To enable informed adaptation decisions, the present study created a dynamic stochastic modeling framework based on the theoretical underpinnings of complex adaptive systems that integrates: (i) stochastic simulation of sea-level rise stressors based on the data obtained from downscaled climate studies pertaining to future projections of sea-level and precipitation; …

Bearing Boundary Element Method Based On Geometrically Similar Roller Conditions, Xia Yang, Ya-Chao Li, Chuang Yan, Guang-Ming Liu, Jian-Mei Wang, Hai-Lian Gui

Journal of Marine Science and Technology

To solve the three-dimensional pressure and load distribution of roller bearings, a new boundary element method (BEM) is presented in this report. First, a discrete model of the initial location roller was established, and the other rollers’ discrete data could be obtained using geometrically similar conditions of this model. Based on the three-dimensional elastic contact BEM, all of the bearing rollers could be described as one object; therefore, the roller bearing problem of a multi-object contact system could be simplified as the problem of a threeobject contact system. Bearing boundary elements were used to realize the discontinuous traction on the …

Modelling The Softening Behaviour During Galvanizing Of Various Steel Grades, Kevin Banks, Rorisang Maubane, Thabang Makwena

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Thermodynamic Simulation For Solidification Path In Die Casting Alloy Development, Mohamad Rusydi Mohamad Yasin, Dongke Sun, Qingyou Han

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Simulation For Carbon Nanotube Dispersion And Microstructure Formation In Cnts/Mg Composite Fabricated With Ultrasonic Processing, Yuansheng Yang, Fuze Zhao, Shaozhen Zhu, Xiaohui Feng

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Modelling The Softening Behaviour During Galvanizing Of Various Steel Grades, Kevin Banks, Rorisang Maubane, Thabang Makwena

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Temperature Distributions Influencing Lateral Spread In Industrial Hot Rolling, Baohui Tian, Siegfried Kleber, Silvia Zinner, Peter Markiewicz

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

The Simulation For Ultrasonic Testing Based On Frequency-Phase Coded Excitation, Jiaying Zhang, Wenlong Tian, Tie Gang, Sen Cong, Zhaoyang Sheng

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Study On Growth Model Of Cellular Automata Method In Solidification Simulation, Zhao Guo, Jian-Xin Zhou, Ya-Jun Yin, Chang-Chang Liu

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Integration Of Advanced Simulation And Visualization For Material Processing, Chenn Zhou

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Optimizing The Telescope Assembly Alignment Simulator For Sofia, Zoe E. Sharp, Alex Quyenvo, Jennifer Briggs, Brian Eney

STAR Program Research Presentations

The Stratospheric Observatory for Infrared Astronomy (SOFIA) conducts research on a modified Boeing 747sp aircraft. By using a variety of infrared science instruments mounted on a 2.7 meter telescope, researchers can make discoveries about the galactic center, star formation, and various topics associated with a deeper understanding of our universe. To efficiently collect data through the SOFIA instruments, the instruments must be tested and prepared prior to being placed on the aircraft. Therefore, with the use of the Telescope Assembly Alignment Simulator (TAAS), researchers can design and construct improvements needed for these instruments to efficiently perform while in flight. The …

Metamodels Of Residual Stress Buildup For Machining Process Modeling, Stuart B. Mccrorie, Michael Sangid

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the process of machining materials, stresses, called residual stresses, accumulate in the workpiece being machined that remain after the process is completed. These residual stresses can affect the properties of the material or cause part distortion, and it is important that they be calculated to prevent complications from arising due to the residual stresses. However, these calculations can be incredibly computationally intensive, and thus other methods are needed to predict the residual stresses in materials for quick decision-making during machining. By using metamodels - a method of representing data where few data points exist - we can achieve an …

Characterization Of Impact Properties Of Forged, Layered, And Additive Manufactured Titanium Alloy, Melissa Kathryn Matthes

UNLV Theses, Dissertations, Professional Papers, and Capstones

New additive manufactured (AM) materials have the potential of optimizing the geometry and microstructure of complex components to enhance their structural integrity while creating them quickly. However, the behavior of AM materials under extreme dynamic loading conditions is not fully understood. This is especially important in many applications. For example, spacecraft components may be impacted by micrometeorites at hyper velocities of multiple kilometers per second, inducing extreme dynamic loading.

One type of AM material is created by melting and solidifying metal along a specified path. Depending on the geometry, additional streams will be deposited side-by-side. This process affects the microstructure …

Investigation Of Digital Pump/Motor Control Strategies, Farid El Breidi

Open Access Dissertations

A pump is the heart of fluid power systems, it has a significant impact on the efficiency of many fluid power systems. Motors are the most common rotary actuators in fluid power systems. State-of-the-art pump/motor units can achieve efficiencies higher than 90% when operating at maximum displacement; however, as the displacement drops, the efficiency of these units drops to below 50%. A new digital pump/motor design aims at increasing these efficiencies by utilizing two electrically controlled high speed on/off valves per displacement chamber; these valves provide the ability to achieve variable displacement and allow freedom in choosing operating strategies. Such …

Automatic Sleep Stages Classification, Maryam Zokaeinikoo

Masters Theses

In this thesis, we first develop an efficient automated classification algorithm for sleep stages identification. Polysomnography recordings (PSGs) from twenty subjects were used in this study and features were extracted from the time{frequency representation of the electroencephalography (EEG) signal. The classification of the extracted features was done using random forest classifier. The performance of the new approach is tested by evaluating the accuracy of each sleep stages and total accuracy. The results shows improvement in all five sleep stages compared to previous works.

Then, we present a simulation decision algorithm for switching between sleep interventions. This method improves the percentage …

Modeling Economic Impacts Of The Inland Waterway Transportation System, Furkan Oztanriseven

Graduate Theses and Dissertations

The inland waterway transportation system of the United States (U.S.) handles 11.7 billion tons of freight annually and connects the heartland of the U.S. with the rest of the world by providing a fuel-efficient and environmentally friendly mode of transportation. This dissertation aims to create decision support tools for maritime stakeholders to measure the economic impacts of the inland waterway transportation systems under real world scenarios including disruptions, demand changes, port expansion decisions, and channel deepening investments. Monte Carlo simulation, system dynamics, discrete-event simulation, agent-based modeling, and multiregional input-output modeling techniques are utilized to analyze the complex relationships between inland …

Modeling And Simulation Of 1700 V 8 A Genesic Superjunction Transistor, Staci E. Brooks

Graduate Theses and Dissertations

The first-ever 1.7kV 8A SiC physics-based compact SPICE model is developed for behavior prediction, modeling and simulation of the GeneSiC “Super” Junction Transistor. The model implements Gummel-Poon based equations and adds a quasi-saturation collector series resistance representation from a 1.2 kV, 6 A SiC bipolar junction transistor model developed in Hangzhou, China. The model has been validated with the GA08JT17-247 device data representing both static and dynamic characteristics from GeneSiC. Parameter extraction was performed in IC-CAP and results include plots showing output characteristics, capacitance versus voltage (C-V), and switching characteristics for 25 °C, 125 °C, and 175 °C temperatures.

An Application Of The Universal Verification Methodology, Rui Ma

Masters Theses

The Universal Verification Methodology (UVM) package is an open-source SystemVerilog library, which is used to set up a class-based hierarchical testbench. UVM testbenches improve the reusability of Verilog testbenches. Direct Memory Access (DMA) plays an important role in modern computer architecture. When using DMA to transfer data between a host machine and field-programmable gate array (FPGA) accelerator, a modularized DMA core on the FPGA frees the host side Central Processing Unit(CPU) during the transfer, helps to save FPGA resources, and enhances performance. Verifying the functionality of a DMA core is essential before mapping it to the FPGA. In this thesis, …

Optimal Disposition Decisions For A Remanufacturing System Considering Time Value Of Products, Mostafa Pazoki, Walid Abdul-Kader

Industrial and Manufacturing Systems Engineering Publications

This paper studies disposition decisions of cores where the value of returns deteriorates over time. Mainly in disposition decisions, a remanufacturer is interested to determine how many units to remanufacture and to salvage. To address this research problem along with value deterioration of returns, a rough-cut mathematical model is developed by considering various parameters of interest such as selling price, salvage value and remanufacturing rate with the aim to maximize total profit. Due to uncertainty limitations, the model can provide decision-makers with relevant insights about disposition decisions. Simulation modeling techniques are used to validate the proposed model. Numerical examples are …

A System-Of-Systems Framework For Assessment Of Resilience In Complex Construction Projects, Jin Zhu

FIU Electronic Theses and Dissertations

Uncertainty is a major reason of low efficiency in construction projects. Traditional approaches in dealing with uncertainty in projects focus on risk identification, mitigation, and transfer. These risk-based approaches may protect projects from identified risks. However, they cannot ensure the success of projects in environments with deep uncertainty. Hence, there is a need for a paradigm shift from risk-based to resilience-based approaches. A resilience-based approach focuses on enhancing project resilience as a capability to cope with known and unknown uncertainty. The objective of this research is to fill the knowledge gap and create the theory of resilience in the context …

The Impact On Educational Technology Of A Fatal Airline Accident: A Case Study, Tim Brady

Tim Brady

The name of the company should read Colgan Air not Cogan Airlines. "This is a study of how a virtual technology burden was created that impacted the professional pilot college student and various colleges/universities that offer professional pilot degree programs. A cascading set of events began as a result of U.S. congressional reaction to a tragic airline accident. The resulting legislation forced the Federal Aviation Administration to publish new rules for first officer qualifications that were unmindful of the recommendations of professional pilot groups for simulation-based training. Ultimately, this placed a financial burden on both the college/university training curriculum and …

Fractional Transport Models For Shale Gas In Tight Porous Media, Nadeem A. Malik, Iftikhar Ali

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Modelling the flow of fluid through tight porous media, such as unconventional hydrocarbon reservoirs, is very challenging and it is a growing sector and must be addressed. Shale gas is found in such tight porous rocks which are characterized by nano-scale size porous networks with ultra-low permeability [1,2].

Please download the full abstract below.

Flow Of Shale Gas In Tight Rocks Using A Non-Linear Transport Model With Pressure Dependent Model Parameters, Nadeem A. Malik, Iftikhar Ali, Bilal Chanane, Ryad A. Ghanam

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

A new source of energy has recently been discovered from unconventional hydrocarbon reservoirs, such as shale gas deposits. Shale gas is found in tight porous rocks which are characterised by nano-scale size porous networks with ultra-low permeability [1,2]. The modelling of transport through such tight porous media is very challenging because it is a relatively new discipline and not much is known but transport processes in them, and little data is available; but it is a growing sector and must be addressed. Here, we apply a recently developed non-linear gas transport model [3], to reservoir simulations of single-phase gas through …

Experimental And Numerical Evaluation Of A New Composite Pressure Pipe For A Trenchless Rehabilitation Technology, Xuanchen Yen

Doctoral Dissertations

The information presented in this dissertation is based on research work conducted at Trenchless Technology Center (TTC) at Louisiana Tech University. This work was performed through a contract with China University of Geoscience (CUG) for a gas company. China's gas pipelines need replacement or rehabilitation after 15 to 30 years of service. China's gas industry is looking for suitable techniques to transfer into their market.

When compared to conventional excavation pipeline renewal or replacement methods, there are obvious advantages of TRT for gas pipelines that can impact the triple bottom-line of economic, social and environmental benefits. An introduction of TRT …

Simulation, Measurement, And Emulation Of Photovoltaic Modules Using High Frequency And High Power Density Power Electronic Circuits, Yunas Erkaya

Electrical & Computer Engineering Theses & Dissertations

The number of solar photovoltaic (PV) installations is growing exponentially, and to improve the energy yield and the efficiency of PV systems, it is necessary to have correct methods for simulation, measurement, and emulation. PV systems can be simulated using PV models for different configurations and technologies of PV modules. Additionally, different environmental conditions of solar irradiance, temperature, and partial shading can be incorporated in the model to accurately simulate PV systems for any given condition.

The electrical measurement of PV systems both prior to and after making electrical connections is important for attaining high efficiency and reliability. Measuring PV …