Engineering Commons^™

Knot Optimization For Univariate Cubic L^1 Spline Fits With Application In Change Point Detection, Manfei Xie

Graduate Research Theses & Dissertations

Cubic $L^1$ spline fits, as a type of $L^1$ approximating splines, have shown superior performance in shape preservation of geometric data with great changes. To better construct a cubic $L^1$ spline fit, the number and the location of the spline knots should be optimized rather than predetermined. This research investigates knot optimization methods for univariate cubic $L^1$ spline fits. When the number of knots is given, we design an optimization-based method to determine the best location of the knots. When the number and the location are unknown, we propose a heuristic method to find proper knot number and location. Numerical …

Sky Surveys Scheduling Using Reinforcement Learning, Andres Felipe Alba Hernandez

Graduate Research Theses & Dissertations

Modern cosmic sky surveys (e.g., CMB S4, DES, LSST) collect a complex diversity of astronomical objects. Each of class of objects presents different requirements for observation time and sensitivity. For determining the best sequence of exposures for mapping the sky systematically, conventional scheduling methods do not optimize the use of survey time and resources. Dynamic sky survey scheduling is an NP-hard problem that has been therefore treated primarily with heuristic methods. We present an alternative scheduling method based on reinforcement learning (RL) that aims to optimize the use of telescope resources for scheduling sky surveys.

We present an exploration of …

Effect Of Perturbations On The Dominant Flow Structures In A Rectangular Lid-Driven Cavity With Particle Suspensions, Siva Bolisetty

Graduate Research Theses & Dissertations

The lid-driven cavity is a canonical problem in the field of analytical and computational fluid dynamics. This work is focused on a 2-D rectangular cavity with a length twice the size of its width and consists of an incompressible fluid with a moving upper wall/lid while the rest of the wall boundaries are subjected to fixed, no-slip, zero-velocity boundary conditions. The objective is to investigate the effect of perturbations resulting from particle drag and particle collisions on dominant flow structures of the fluid within this cavity. The dominant flow structures in a rectangular lid-driven cavity constitute a primary vortex, a …

Studying The Effect Of Vacancies On The Thermal Conductivity Of Metal-Coated Carbon Nanotubes Using Molecular Dynamics Atomistic Simulations, Ravindra Sunil Dhumal

Graduate Research Theses & Dissertations

Breakthroughs in nanotechnology have made it possible for the size of electronic gadgets to be scaled down to micro/nano level. What follows however, is the side effect of high power densities and overheating as the heat dissipation is restricted to very small surface area. Thus, the need of an effective thermal management system is central to these developments. One way to counter this problem is to use Thermal Interface Materials (TIMs) which promote heat transfer between heat source and sink.

Owing to their high thermal conductivity (up to 6000 W/mK), Carbon Nanotubes (CNTs) are thought of as strong candidates for …

The Social Presence Of Jibo, Parisa Farhadi

Graduate Research Theses & Dissertations

This research is an attempt to investigate how a social robot is perceived by users at the first encounter. And to find out whether a social robot like Jibo is understood merely as a kind of a technological object or a social entity. Previous studies in Human-Robot Interaction have considered social presence as a mediator in users’ social responses toward robots; however, the focus of this study is the social presence itself and investigates whether Jibo produces a sense of presence during initial encounters. To this end, the current study examines individuals’ perceptions of and responses to Jibo. Participants (N=8) …

Steady Flows In Annular Wedge Lid-Driven Cavities, Anandan Ganapathy

Graduate Research Theses & Dissertations

The lid-driven cavity is a well-known canonical problem in the field of analytical and computational fluid dynamics. It is comprised of a square domain of an incompressible fluid with its upper lid has a specified velocity and the remaining wall boundaries are subjected to fixed, no-slip, zero-velocity constraints. There are numerous examples found in the literature that address the well-known, stable behavior of this system, which includes a primary recirculating vortex, secondary corner vortices, and a velocity profile through the center midpoint y-axis that is shown to be dependent on the Reynolds number. In this investigation, the shape of the …

Characterization Of Boron/Iron-Oxide Core/Shell Structure For Boron Neutron Capture Therapy By Stem/Eels-Xeds And Mössbauer Spectroscopy, Mason Douglas Hayward

Graduate Research Theses & Dissertations

Boron/iron-oxide core/shell structured nanoparticles were characterized for application in boron neutron capture therapy (BNCT). BNCT is a cancer treatment method using the ability of boron to absorb thermal neutrons and a proposed drug delivery system utilizing an external magnetic field to direct the boron nanoparticles to targeted cancer sites and to extract the used nanoparticles after treatment. Boron nanoparticles were magnetically functionalized by encapsulating with an iron oxide shell. As such the exact composition, size distribution and oxidation states of the core/shell structures can affect treatment efficacy. Characterization was done by electron energy loss spectroscopy (EELS) and x-ray energy dispersive …

Proper Orthogonal Decomposition Analysis Of Lid-Driven Cavity Flows Containing Particle Suspensions., Nitin Katiki

Graduate Research Theses & Dissertations

Previous experiments done on the square lid driven cavity have shown that its stability and transitional behavior, and by extension the behavior of more complex flows, can be greatly modified by introducing systematic disturbances called perturbations to its flow field. In this study, a square lid driven cavity is calculated in two-dimensional space and perturbed by means of particles suspended in the flow. The perturbations manifest as subtle changes in the flow field velocity and overall flow structure, these are caused by the particle-fluid drag interaction and the particle-particle collision interaction. To understand the nature of these changes and their …

Temporal Dynamics Of Human Emotional Response To Aversive Stimuli, Joseph Lawence Kempel

Graduate Research Theses & Dissertations

Emotions are an integral part of human expression and are often communicated nonverbally through behavioral actions. With advancements in electroencephalography (EEG) technology it is now possible to measure the dynamics of emotion generation in an individual on the basis of patterns in their brain activity. This thesis aims to model the temporal dynamics of human emotion generation upon exposure to aversive stimuli and measure the effect of external distractions as a viable emotion regulation strategy.

This research builds on previous work in the literature that has shown that the ability of humans to regulate their emotions intrinsically (based on their …

Small Non-Profit Website And Social Media Efficacy, Juliana Maria Leprich

Graduate Research Theses & Dissertations

This thesis examines the website design and social media platform usage of small non-profit organizations (defined as less than $1M operating budget and less than ten staff). This research will be completed by first reviewing other studies that have been done on marketing in the non-profit sector, then by exploring marketing challenges firsthand through a mini-ethnographic case study as described in the mini-ethnographic case study approach, and finally through the examination of tax and financial data provided by Guidestar. The researcher was involved in website collaboration with The Gracie Center in a volunteer capacity and was employed with the two …

Tools For Understanding Static Structure Factors And Their Application To Simulations Of Liquids, Travis Mackoy

Graduate Research Theses & Dissertations

Molecular dynamics (MD) simulations can be used to compute static structure factors (��(��)) and provide an interpretation of the underlying periodic atomic ordering. MD simulations complement experimentally measured ��(��) by allowing qualitative assignment of peaks to various ordering, such as cation-anion ordering in ionic liquids, via decomposition of ��(��) into partial ��(��). Here we present a method for classifying interatomic distances that allows for quantitative peak assignment and visualization of atoms that contribute most to each peak in calculated ��(��) for soft materials. The method is illustrated by investigating ��(��) for the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (C4C1pyrrTFSI), which shows two …

Minimizing Total Number Of Tardy Jobs In Parallel Batch Processing Machines Using Column Generation And Simulated Annealing, Sameer Neupane

Graduate Research Theses & Dissertations

This research considers a scheduling problem where jobs need to be grouped into batches and the batches need to be scheduled on parallel batch processing machines with an objective to minimize the total number of tardy jobs. The jobs are assigned to batches in such a way that machine capacity is not violated. This research considers jobs with unequal ready times, unequal processing times and unequal sizes. The machines are identical in processing capabilities; however, their capacities are different. This research aims to develop effective solution approaches to solve the problem under study. A Mixed Integer Linear Programming (MILP) model …

A Lagrangian-Based Heuristic To Consolidate Perishable Products, Samir Babu Bhetwal

Graduate Research Theses & Dissertations

A consolidation center with multiple suppliers and multiple destinations for a perishable product is considered in this research. Perishable products deteriorate with time and this research includes a deterioration cost to measure this behavior. The model considers a variety of suppliers ranging from small to mid-sized. Due to dependencies of inventory and shipment release decisions, an integrated approach of making the operational decisions is necessary. This coordinated approach considers deterioration cost, inventory cost, and transportation cost.

Tradeoff decisions between different supply chain costs are not straightforward as the problem contains constraints like inventory capacity and transportation constraints from suppliers to …

Wavelet-Eigen Analysis For Customizable Flexion Classifier Based On Electromyography Signals, Luke S. Bonnen

Graduate Research Theses & Dissertations

This research will cover Electromyography (EMG) and its use in prosthetics. There are many upper limb amputees that use EMG to control a prosthetic limb. While many of these prostheses are proportionally controlled, meaning they can control one movement proportional to the EMG amplitude, there is a continual need to improve function for quality of life. Proportional control is traditionally utilized for opening and closing of the hand. It is the desire of engineers to find ways to add more functionality without sacrificing reliability. There are systems that do these additional actions, but they have difficulty with reliability because of …

Direct Polymer Grafting As A Method Of Maintaining The Mechanical Properties Of Cellulose Nanocrystals In The Presence Of Moisture, Mary Elizabeth Breen-Lyles

Graduate Research Theses & Dissertations

Cellulose nanocrystals (CNCs) are a distinctive nanomaterial derived from cellulose, the most abundant natural polymer on Earth, and the primary reinforcing structural component of cellulose fibrils found within the plant cell wall. These nanocrystals exhibit mechanical properties comparable to synthetic aramid fibers but are advantageous as they are biodegradable, renewable, and can be produced sustainably as they are predominantly extracted from naturally occurring cellulosic materials. These qualities make it a sustainable, highly renewable and environmentally friendly material to be used in place of synthetic materials in a variety of applications. With their high surface area to volume ratio, low level …

Computational Methods For Bicubic L1 Splines, Priyesh Koyu Rai

Graduate Research Theses & Dissertations

The past two decades have seen the development of L1 splines for interpolation and approximation of geometric data. L1 splines have been shown to preserve shapes better than the conventional L2 splines, especially for data with abrupt changes in the magnitude of spacing. Efficient computation plays an important role in the practical application of L1 splines. This thesis creates new computational methods for constructing bicubic L1 interpolating splines and bicubic L1 spline fits. The bicubic splines in this study are piecewise bicubic polynomials defined on a rectangular grid generated by the tensor product of nodes. We developed a hybrid computational …

Implementation And Evaluation Of Gated Recurrent Unit For Speech Separation And Speech Enhancement, Sagar V. Shah

Graduate Research Theses & Dissertations

Hearing aids, automatic speech recognition (ASR) and many other communication systems work well when there is just one sound source with almost no echo, but their performance degrades in situations where more speakers are talking simultaneously or the reverberation is high. Speech separation and speech enhancement are core problems in the field of audio signal processing. Humans are remarkably capable of focusing their auditory attention on a single sound source within a noisy environment, by de-emphasizing all other voices and interferences in surroundings. This capability comes naturally to us humans. However, speech separation remains a significant challenge for computers. It …

Youtube’S Terms Of Service: Posthumanism, Algorithms, And Professional Writing, Sarah Bresnahan

Graduate Research Theses & Dissertations

This thesis aims to examine YouTube’s Terms of Service as it applies to content creators (known as YouTubers) who use the platform as a means of financial gain and how YouTube’s demonetization policy via an algorithm is negatively affecting them. I conducted a case study featuring one creator, Michelle Guido, and attempted to determine why some of her content is demonetized when it fulfills YouTube’s content standards for monetization. This study is meant as an examination through the lens of Dr. N. Katherine Hayles’s theory of posthumanism as stated in her book, How We Became Posthuman, and will offer insight …

Aluminum And Silicon Metal-Semiconductor-Metal (Msm) X-Ray Photodetector, Cinthya Dallana Barbosa Medina

Graduate Research Theses & Dissertations

The main goal of this research was to construct a metal-semiconductor-metal (MSM) device, that could detect x-rays. The following thesis covers the theory behind MSM devices, as well as the theory of detecting x-rays. More importantly, we showed that aluminum was transparent to x-rays, therefore allowing our MSM device to detect only x-rays.

Both p-type and n-type MSM wafers resulted in the predicted Schottky curve. By analyzing our various configurations, we hypothesis the ideal dimensions for this device configuration. We also showed that the effect caused by the interaction with regular light.

Apart from what was accomplished in this paper …

Fabrication Of Ultra-Fine Cathodes For Cold-Field Emission, Srujana Valluri

Graduate Research Theses & Dissertations

This thesis discusses the different fabrication steps involved in producing ultra-fine cathodes that are suitable for cold field emission. A four-step nanofabrication process has been developed to obtain the cathodes with tip diameters ranging from 10nm to 20 nm. First, a mask is patterned on a 2-inch silicon wafer using monodisperse 1.18µm silica spheres. These particles are self-assembled using vortex-flow enabled assembly technique to form close-packed monolayers. Then the silicon is etched using a reactive ion etching technique. An inductively coupled plasma etcher is used to perform anisotropic and isotropic etching. The etching recipes used are chosen such that they …

Validation Of A Low-Cost Sensor For Development Of Wearable And Handheld Spectrometers, Justin Leslie Cathey

Graduate Research Theses & Dissertations

This study examined the possibility of creating a quantitative radiometric spectrometer from a low-cost relative radiometric spectrometer sensor through the use of statistical analysis and development of a correction factor (p > 0.05). Radiometric spectrometers are able to measure and fully characterize the radiometric and photometric characteristics of light, while relative spectrometers are not able to fully, quantitatively characterize the radiometric response from a light source, thus they are less expensive. The spectrometer created in this research is able to measure and produce comparative lighting parameters as well as an actual radiometer spectrometer.

The photoreceptors cells within the human eye allow …

Implementation Of The Shpb System For Material Property Test Under High Strain Rate Deformation, Jiaqi Zhu

Graduate Research Theses & Dissertations

Since Bertram Hopkinson first raised the concept of Hopkinson pressure bar in 1914, many efforts have been taken by engineers and scholars for developing the system to measure the stress pulse propagation in metal bars for studying the properties of different materials under high strain rate deformation. The Northern Illinois University Material’s Lab has also built two generations of the split Hopkinson pressure bar (SHPB) system with the effort of several senior design teams in history.

The aim of this study is to develop the existing SHPB system of NIU to make it function properly. By redesigning the gun barrel, …

The Short-Term Effects Of Interstate Highways On Small Rural Communities: A Case Study Of I-39, I-49 And I-72, 1990 To 2000, John Paul Metelko

Graduate Research Theses & Dissertations

The presence of interstate highways in rural areas improves access to nearby rural

communities and changes those communities’ spheres of influence. Research into

understanding how improved access from interstate highways affects rural communities

is needed. This case study was designed to investigate how rural communities changed

on the basis of population, vacancy, median home value, and median contract rent in the

short term after an interstate highway was completed nearby in the early 1990s.

The communities included in this study are incorporated cities, towns, villages

and census-designated places in non-metropolitan counties with at least one incorporated

city, town, village and …

Exploring Cyber-Physical Systems, Misbah Uddin Mohammed

Graduate Research Theses & Dissertations

The advances in IOT, Computer Vision, AI and Machine Learning have made these technologies ubiquitous to our daily lives. From Smart Phones to Connected Vehicles, Cyber Physical systems have been interspersed into everything we interact in today’s world. The aim or this thesis was to explore these advances in Cyber Physical Systems and analyze the different sectors they were affecting. We then hand-picked certain domains and explored further by carrying out practical projects using some of the latest software and hardware resources available. Technologies like Amazon Alexa services, NVIDIA Jetson boards, TensorFlow, OpenCV, NodeJS were heavily employed in our various …

The Effects Of Using A Mobile Digital Assistive Tutor For Circuit Analysis On Students’ Academic Achievement, Problem-Solving And Self-Efficacy, Kenie Moses

Graduate Research Theses & Dissertations

This experimental research study examined the effects of using a mobile learning environment (MLE) that provided scaffolded assistive tutoring on student achievement in a Circuit Analysis (Network Theory) course. It also aimed to examine the relationships between students’ user learning analytics and their learning outcomes. The design and development of the mobile app was based on the Model of Contingent Instruction and Metacognitive Support which critically applies scaffolding as its operative in transferring domain knowledge in expert to novice problem-solving.

This experimental research study collected data from eighty-three undergraduate college students who were randomly assigned into one of three groups …

Numerical And Experimental Validation For The Optimization Of Directed Energy Deposition Processing Parameters, Luis Nunez

Graduate Research Theses & Dissertations

In order to capitalize on the cost effectiveness of Metal Additive Manufacturing (MAM) it is critical to understand how to build components with consistency and high quality. Directed Energy Deposition (DED) is a MAM method for creating parts layer by layer through the use of a moving heat source and powder material inserted into the melt pool generated on the substrate. DED like most MAM processes are highly complex due to the rapid thermal gradients experienced during processing. These thermal gradients are determined by a variety of processing parameters which include laser power, powder feed rate, travel speed, layer height …

A Computational Fluid Dynamics Analysis Of The Aerodynamic Performance Of Wind Turbine, Ashkan Ostovari

Graduate Research Theses & Dissertations

Renewable energy resources are likely to be a future energy solution. Among them, the wind has gained a lot of interest. Despite the theoretical limitation in wind energy harnessing efficiency, it is, still, one of the most promising renewable resources with utilizing turbines to extract this energy. Wind turbines, based on their axis of rotation are categorized into vertical axis wind turbine (VAWT) and horizontal axis wind turbine (HAWT), which HAWT’s have shown relatively higher efficiency than VAWT’s. The aim of this thesis is first to develop a scaled-down model of a wind turbine in Computational Fluid Dynamics (CFD) environment …

Energy Analysis For Process Parameter Prediction Of Direct Energy Deposition Metal Additive Manufacturing, Daniel John Pulscher

Graduate Research Theses & Dissertations

Metal Additive Manufacturing with the Direct Energy Deposition (DED) process allows for rapid prototyping and low-volume custom manufacturing of complex geometries at a lower cost than traditional manufacturing methods. Direct energy deposition is a complex process having many inter-related process parameters that effect the overall quality and mechanical properties of the build. When new powder feedstocks are used, calibrating these process parameters is typically done empirically in trials that can contain more than a hundred different combinations of parameters. This time-consuming process can be reduced by performing an analytical analysis on how the energy from the laser transfers into the …

The Treatment Of Contaminated Water Using Electrocoagulation, Adebayo Edward Adejinle

Graduate Research Theses & Dissertations

Wastewater treatment is a process that is used to remove significant amount of contaminant concentration from wastewater, which prevents harm to the environment. Chemical coagulation (CC) is one of the most influential processes used to remove contaminants, and it is the addition of chemicals called coagulants, which causes particles to stick together forming bigger flocs. However, as effective as CC is, it requires bench scale testing for determining the appropriate dosing rate for specific raw water properties, which makes the process time consuming. To eliminate these issues, the introduction of the Electrocoagulation (EC) process is considered. The EC process is …

Thermal Analysis And Design Of Conduction Links For A Superconducting Radio Frequency Resonator, Aaron Mckeown

Graduate Research Theses & Dissertations

The SRF conduction link project at Fermi National Accelerator Laboratory aims to develop an SRF particle accelerator design that is more applicable for industrial use. Collaboration between NIU college of engineering and NIU department of physics provided the bulk of design and analysis for this project. Currently, cooling systems, used in SRF particle accelerators, pump liquid helium across the SRF cavity to provide convection based cooling. The goal of this project is to incorporate a conduction based cooling system. In a conduction based cooling system, heat will flow from the SRF cavity into a cryocooler through a conduction link. In …