Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Purdue University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 10441 - 10470 of 50121

Full-Text Articles in Entire DC Network

Droplet Spreading On A Substrate, Chao-Ying Chen May 2018

Droplet Spreading On A Substrate, Chao-Ying Chen

Open Access Theses

The present work focuses on spreading dynamics of thin viscous droplets on a planar and smooth substrate in a small Reynolds number regime. The droplets are affected by gravity, surface tension and viscous forces. For triple-phase zone, the moving contact-line models are provided to remove the singularity at the edge of the droplet. Our aim of this study is to predict the experimental results and extend the analysis to spreading on a porous substrate. Besides, we quantify the role of rheological parameters, for example, exponent for power-law liquids, on the spreading dynamics. The mathematical models for a Newtonian droplet and …

Go to article

Predicting Customer Complaints In Mobile Telecom Industry Using Machine Learning Algorithms, Chiyoung Choi May 2018

Predicting Customer Complaints In Mobile Telecom Industry Using Machine Learning Algorithms, Chiyoung Choi

Open Access Theses

Mobile telecom industry competition has been fierce for decades, therefore increasing the importance of customer retention. Most mobile operators consider customer complaints as a key factor of customer retention. We implement machine learning algorithms to predict the customer complaints of a Korean mobile telecom company. We used four machine learning algorithms ANN (Artificial Neural Network), SVM (Support Vector Machine), KNN (K-Nearest Neighbors) and DT (Decision Tree). Our experiment utilized a database of 10,000 Korean mobile market subscribers and the variables of gender, age, device manufacturer, service quality, and complaint status. We found that ANN’s prediction performance outperformed other algorithms. We …

Go to article

Experimental Study Of Fractional Order Behavior In Dynamic Systems, Rajarshi Choudhuri May 2018

Experimental Study Of Fractional Order Behavior In Dynamic Systems, Rajarshi Choudhuri

Open Access Theses

Common applications of engineering-based systems are theoretically modeled utilizing integer order based mathematical operations. On occasion, integer order based mathematical methods do not accurately model the complete system behavior due to the underlying physics of the system. However, fractional order models are applied to better assess the accuracy of these systems and create the appropriate model. Fractional calculus is considered by mathematicians to be a special case for real system analysis. However, a specific case of fractional order analysis of real systems has the tendency of resulting in solutions that are paradoxical in nature. Therefore, fractional order models have not …

Go to article

Categorizing Hbsi Errors Using Wearable Trackers., Jeffrey Chudik May 2018

Categorizing Hbsi Errors Using Wearable Trackers., Jeffrey Chudik

Open Access Theses

In this thesis, the categorization of Human-Biometric Sensor Interaction (HBSI) metrics, which include errors resulting from human interaction with a biometric device, using a wearable fitness tracker in a variety of biometric use cases is illustrated with a proposed methodology. This answers the question “Is it possible for the stream of data from the sensors in a wearable wristband be classified using the HBSI model?”. The use cases examined are gait recognition, heart rate RR recognition, and liveness detection using heart rate (bpm). The study was conducted on a convenience sample of three subjects. The proposed methodology could classify some …

Go to article

Evaluation Of Additive Manufacturing Technology For Microchannel Heat Sinks, Ivel Lee Collins May 2018

Evaluation Of Additive Manufacturing Technology For Microchannel Heat Sinks, Ivel Lee Collins

Open Access Theses

Microchannel heat sinks allow removal of dense heat loads from high-power electronic devices at modest chip temperature rises. Such heat sinks are produced primarily using conventional subtractive machining techniques or anisotropic chemical etching, which restricts the geometric features that can be produced. Owing to their layer-by-layer and direct-write approaches, additive manufacturing (AM) technologies enable more design-driven construction flexibility and offer improved geometric freedom. Various AM processes and materials are available, but their capability to produce features desirable for microchannel heat sinks has received limited assessment. Following a survey of commercially mature AM techniques, three technologies were identified as meeting the …

Go to article

Synthesis And Characterization Of Novel Double Perovskites, Andrew Kent Bowser May 2018

Synthesis And Characterization Of Novel Double Perovskites, Andrew Kent Bowser

Open Access Theses

Double perovskite oxides make up an extremely large and diverse set of compounds in the realm of solid state chemistry. Capable of incorporating nearly every element of the periodic table, these perovskites possess tunable and mixed physical properties. As such, the substitutions of many elements into the various crystal structures of double perovskites have not been well explored. One such of these elements is Os, which displays a large range of possible oxidation states and the capability to create complex magnetic systems when paired with other magnetic cations in the B-site sublattice of double perovskites. I have undertaken several projects …

Go to article

The Mnemonic Effect Of Choice, Michelle E. Coverdale May 2018

The Mnemonic Effect Of Choice, Michelle E. Coverdale

Open Access Theses

Making choices during encoding leads to better memory than having the same choices made for you. Beyond a mnemonic benefit for choosing, our laboratory has shown a benefit for items that have been chosen over those that are not chosen. Though many experiments in the fields of memory and education involve a choice component, little consideration has been paid to how an item’s status as chosen or unchosen affects memory. Prior research comparing memory for chosen and unchosen items has confounded choice and congruity, making the source of the recall benefit unclear. We conducted three experiments to dissociate choice and …

Go to article

Exploring Double Consciousness: The Rhetoric And Retention Of Black Graduate Students At Predominantly White Institutions, Kimberly Nicole Broughton May 2018

Exploring Double Consciousness: The Rhetoric And Retention Of Black Graduate Students At Predominantly White Institutions, Kimberly Nicole Broughton

Open Access Theses

This is an exploration of theoretical approaches to W. E. B. DuBois’ notion of “double consciousness,” which specifically looks at how other scholars have defined DuBois’ philosophy and what it means for Black graduate students in the 21st century. This project seeks to explore theorists’ application of this concept, its relations to one another, and its implications for Black students and faculty in academia. As such, this project examines existing vantage points of what it means to practice dual identities in various capacities, and how this contributes to students of color’s understanding and navigation of Black culture within predominantly white …

Go to article

Living In A Liminal Space: Standing Rock And Storytelling As A Tool Of Activism, Janelle Cronin May 2018

Living In A Liminal Space: Standing Rock And Storytelling As A Tool Of Activism, Janelle Cronin

Open Access Theses

To recall on the past through oral tradition is a source of strength, so why not study the stories and actions of female Native leaders today by analyzing the stories and artifacts they leave behind. With the current political climate, it has become opportunistic and necessary to redefine identity, to challenge the dominant narrative, to question history and plan for the future through critical engagement of the present. This research will provide other Native women leaders, writers, poets and storytellers inspiration and confidence in their current actions and skills, as they are tools in resisting and surviving the various systems …

Go to article

Identifying Pollinator Species Of Indiana Soybean Fields And Their Potential Contributions To Yield, Brooke Dennis May 2018

Identifying Pollinator Species Of Indiana Soybean Fields And Their Potential Contributions To Yield, Brooke Dennis

Open Access Theses

Indiana has a wide array of native pollinators, but where they are foraging and their pollination role, if any, in Indiana soybean fields is unclear. In two Indiana soybean fields sampled in 2016, a total of 33 pollinator species and 1,180 individuals from five different families (Andrenidae, Collectidae, Syrphidae, Apidae and Halictidae) were collected in a transect line including bee bowls at varying distances (0m, 5m, 10m, 25m, 50m, 100m and 250m). Species richness and abundance was similar across the varying bee bowl distances with soybean growth stage R2 and R3 collecting the most individuals and species totals. Field experiments …

Go to article

Ultrasonic Attenuation Of Bridge Steels And Narrow-Gap Improved Electroslag Welds, Bridget M. Crowley May 2018

Ultrasonic Attenuation Of Bridge Steels And Narrow-Gap Improved Electroslag Welds, Bridget M. Crowley

Open Access Theses

Ultrasonic testing is a nondestructive inspection technique currently required during the inspection of complete joint penetration bridge welds. Ultrasonic testing utilizes sound wave reflections to find and characterize internal features and defects. Inspection with ultrasound is readily used in both fabrication shops and in the field to detect and locate critical defects detrimental to the safety and performance of bridges. Current inspection guidelines and acceptance criteria for bridge welds are found in the 2015 American Welding Society (AWS) D1.5 Bridge Welding Code. Variables such as frequency, modes of wave propagation, velocity, grain structure, and equipment calibration all separately impact ultrasonic …

Go to article

Characterization Of An Aluminum-Lithium Alloy Based Composite Propellant At Elevated Pressures, Gabriel Diez May 2018

Characterization Of An Aluminum-Lithium Alloy Based Composite Propellant At Elevated Pressures, Gabriel Diez

Open Access Theses

Aluminum-lithium (Al-Li) alloys have demonstrated a mechanism to improve composite propellant performance by reducing agglomerates through microexplosions. In addition, use of Al-Li significantly reduces hydrochloric acid production in ammonium perchlorate based propellants while also improving theoretical performance. Full combustion characterization (e.g., at various pressures) of the Al-Li based propellant has not been performed previously. Measurement of the aluminum-lithium composite propellant’s burning rate and quantification of agglomerate production at various pressures is presented. Agglomerate size of the aluminum-lithium appeared to be smaller at lower pressures than at higher pressures, likely due to increased microexplosions at low pressures. Additionally, at high pressures …

Go to article

Quality And Economic Analysis Of Green Coffee Beans Stored In Purdue Improved Crop Storage Bags, Natalie Kay Donovan May 2018

Quality And Economic Analysis Of Green Coffee Beans Stored In Purdue Improved Crop Storage Bags, Natalie Kay Donovan

Open Access Theses

Coffee farmers and cooperatives in Colombia are plagued by the high humidity that engulfs the Central Andean Mountain Ranges, where the majority of the country’s coffee farming presides. Farmers are forced to sell their yields immediately after harvests in order to mitigate quality loss due to the high moisture. Cooperatives are generally forced to store green coffee until enough volume is collected for export. Farmers and cooperatives are unable to utilize optimal storage methods to capitalize on price seasonality, leading to lower profits. Coffee is a luxury commodity and its price is almost entirely dependent on its quality, making it …

Go to article

Simulating Composite Delamination With A Damage-Type Cohesive Zone Model, Haodong Du May 2018

Simulating Composite Delamination With A Damage-Type Cohesive Zone Model, Haodong Du

Open Access Theses

Interlaminar damage (delamination) is one of the predominant forms of failure in laminated composites, which is broadly used in aerospace, astronautical and automobile industry and many other fields. Engineering problems about damage tolerance and structure durability requires the ability to simulate mixed mode delamination in laminated composites. The objective of the research is to develop an implicit scheme for a recently developed damage-type cohesive zone model (CZM) with an associated systematic calibration method. The CZM is formulated based on thermodynamics, and the damage evolution is derived with the principle of maximum dissipation. A stable implicit scheme using the Newton–Raphson method …

Go to article

Habitat And Interspecific Interactions Affect Mesocarnivore Occupancy In The Eastern U.S., Michael Egan May 2018

Habitat And Interspecific Interactions Affect Mesocarnivore Occupancy In The Eastern U.S., Michael Egan

Open Access Theses

Interspecific competition is important to carnivore communities because of the propensity of carnivores toward aggressive interactions. Interactions among members of the eastern U.S.A. mesocarnivore community have been impacted by the loss of top predators and urbanization. Changes to interspecific interactions and habitat result in changes in many populations of mesocarnivores. Interactions between these two factors further explain contrasting patterns among the members of the mesocarnivore community. These patterns have been studied at scales from the effects of microhabitat to landscape scale factors on mesocarnivore occupancy, however they have not been studied throughout multiple independent landscapes in the eastern U.S.A. Here, …

Go to article

Improving Hotel Demand Forecasting Accuracy By Identifying Seasonality-Adjusted Outliers, Tingting Duan May 2018

Improving Hotel Demand Forecasting Accuracy By Identifying Seasonality-Adjusted Outliers, Tingting Duan

Open Access Theses

Forecasting accuracy determines the effectiveness of revenue optimization. Although researchers have evaluated demand forecasting models applied to various types of hotel, their results have differed considerably because the forecasting methods tested were based on varying hotel demand patterns. The objectives of this thesis are to improve forecasting accuracy and to provide general guidance on method selection. To achieve the objectives, the author proposes two stages. In the first stage, the author tests the performance of each of the selected forecasting models in 13 scenarios classified by location and scale. The selected forecasting methods are (1) Same Day Last Year (SD), …

Go to article

The Effects On User Perception Of Uniqueness Of Three Factors As Applied To 3-Dimensional Tree Models, Ge Gao May 2018

The Effects On User Perception Of Uniqueness Of Three Factors As Applied To 3-Dimensional Tree Models, Ge Gao

Open Access Theses

The gaming industry always faces the continual challenges of striking balance between real-time computing performance and graphics presentation quality. This is particularly apparent for a game with vast wild-lands scenes which demands for a large number of tree models. From the visual perception perspective, this paper investigated whether people can distinguish trees with uniqueness of various features (relative orientation, density of branches, leaf color) using the same tree model in a virtual environment. During the controlled experiment, quantitative research methods were used, which measured the statistics of tree variations. The results suggested that our methods successfully contributed a strategy in …

Go to article

The Acquisition Of Aspectual Properties In Reflexive Psych Predicates And Physical Change Of State Verbs, Aida Garcia Tejada May 2018

The Acquisition Of Aspectual Properties In Reflexive Psych Predicates And Physical Change Of State Verbs, Aida Garcia Tejada

Open Access Theses

The present study examines the acquisition of the aspectual values of Spanish clitic se with psychological verbs and physical change of state verbs. Specifically, we examine the inchoative aspect of se with these verbs within an eventive interpretation. Twenty Spanish heritage speakers, twenty English-speaking L2 learners of Spanish, and twenty controls from Mexico completed an elicited production task an acceptability judgement task and a preference task. Results showed a clear advantage of HSs over L2 learners across conditions. Moreover, the target performance of L2 learners increased in the interpretation task as opposed to the production task where their target performance …

Go to article

Refiguring Hybridity In Star Trek, Elizabeth Gellis May 2018

Refiguring Hybridity In Star Trek, Elizabeth Gellis

Open Access Theses

In this thesis, I explore the ways in which the Star Trek franchise posits hybridity. Examining three hybrid characters—Spock and B’Elanna, both half-human, half-alien, and Data, an android—I explore how each character relates to their hybrid identity and envisions their own hybridity. Rejecting previous models for hybridity that use an additive, percentage-based logic, I use these characters to create a new framework for hybridity. Beginning with the figure of the Jew as an example of alternative Otherness, I posit hybridity as an emergent entanglement, a unifying force that reconciles and reinforces the disparate parts of the self—while retaining an Otherness …

Go to article

Synthesis Of Next Generation Open-Shell Small Molecules: Effects Of Functional Group Modulation Of Blatter’S Radical, Stephen Gilbert May 2018

Synthesis Of Next Generation Open-Shell Small Molecules: Effects Of Functional Group Modulation Of Blatter’S Radical, Stephen Gilbert

Open Access Theses

Polymers containing pendant radical groups have recently come into spotlight for implementation in organic electronic devices. With the synthesis and application of these materials comes many challenges centered around the reactive nature of the radical species. The 1,3diphenyl-1,4-dihydro-1,2,4-triazin-4-yl (i.e., Blatter’s) radical has been described in literature as a stable, conjugated, planar molecule. As such, it presents an excellent opportunity for further evaluation of charge transport mechanism in radical polymers. The essence of this work will focus on the synthesis and characterization of Blatter’s radical as well as plans consisting of synthetic schemes for the polymerization of this novel molecule.

Go to article

Determining The Critical Success Factors In Big Data Projects, Aishwarya Gupte May 2018

Determining The Critical Success Factors In Big Data Projects, Aishwarya Gupte

Open Access Theses

Critical success factors are activities that need to be given prime importance in order to achieve quality project success and can also help to prioritize tasks as a part of the project plan. In recent times, research on Big Data has been concentrated on effective algorithms and robust data models (Saltz & Shamshurin, 2016); however, minimal work has focused on the best methodology for executing such projects (Saltz, 2015). The exploratory nature of Big Data projects demands a more specific methodology that can handle the uncertain business requirements of such projects (Saltz, 2015). To help address this shortcoming, Big Data …

Go to article

Acorn Dispersal And Oak Regeneration In A Managed Landscape, Skye M. Greenler May 2018

Acorn Dispersal And Oak Regeneration In A Managed Landscape, Skye M. Greenler

Open Access Theses

Oaks (Quercus)are a dominant tree genus and foundational component of many eastern North American forests. In these forests, they shape the structure, wildlife habitat, and understory light conditions; produce acorns that are a high value food source for wildlife; and are a high-value timber resource. Across the region oaks are regenerating poorly in many forests, in part, because of widespread fire suppression and decades of management practices that did not align with oak disturbance ecology. This regeneration failure has spurred substantial research on historic disturbance regimes and led to an increased use of silvicultural methods that produce intermediate light levels, …

Go to article

Polarization In Media: Perception And Reality, Parag Guruji May 2018

Polarization In Media: Perception And Reality, Parag Guruji

Open Access Theses

This research aims at exploring the polarization in the news based on reports of the 2017 “Travel Ban” executive order using natural language processing and clustering techniques. The study uses a 2014 report from Pew Research Center as a source of perceived relative positioning of various mainstream news sources on an ideological scale. This positioning is compared to the relative positioning and grouping of news articles from selected news sources; the positioning is revealed by the analysis of their news content. The dataset for this study comprises of 2178 news articles about the 2017 executive order on immigration, commonly known …

Go to article

Visualization In The Teaching Of Agricultural And Biological Engineering Concepts, Claire E. Haselhorst May 2018

Visualization In The Teaching Of Agricultural And Biological Engineering Concepts, Claire E. Haselhorst

Open Access Theses

Continued innovation and design is necessary within all aspects of engineering education to improve the quality of the field and meet the growing needs of students. The projects discussed in this paper were designed under the principles of Bloom’s taxonomy to improve the efficiency student learning. As concepts, processes, and devices become more complex, interactive innovations within teaching techniques become more critical for effective instruction. The use of these teaching methods to promote deeper and more intuitive knowledge gains in students allow for a stronger foundation for covering the foundational skills and methods of the engineering practice. Instructors in the …

Go to article

Brain Atlas And Neuronal Connectivity Visualization And Interaction In Virtual Reality, Lindun He May 2018

Brain Atlas And Neuronal Connectivity Visualization And Interaction In Virtual Reality, Lindun He

Open Access Theses

Brain atlases can provide a lot of information about the anatomy of the human brain. However, understanding the shapes of regions and the overall hierarchical structure of a brain atlas can be difficult. Brain atlases contain hundreds of regions with shapes which are hard to distinguish. The transformations of those shapes make them very difficult to visualize because the brain regions are usually packed tightly together and occlude each other. This thesis presents a visualization system based on virtual reality interactions. It enables interactive exploration of brain atlases and an underlying medical image by creating exploded views using VR technology …

Go to article

A Thermally-Actuated Micro Shutter Array Device For Mask-Less Lithography, Zitao He May 2018

A Thermally-Actuated Micro Shutter Array Device For Mask-Less Lithography, Zitao He

Open Access Theses

Photolithography is a fundamental and important step in semiconductor manufacturing. It transfers the pattern (the structure of device to be fabricated) from photomask to silicon wafer. However, the traditional mask is un-flexible and costly. Here, an innovative cost-effective thermally-actuated dynamic mask is proposed which has flexibility of switching pattern arbitrarily by dividing the pattern into pixels. In this work, we demonstrated that a micro-shutter array device has the ability to operate as a dynamic mask for optical mask-less lithography. This device utilizes thermal expansion of bi-material cantilever for actuation. It has the ability to switch on and off to enable …

Go to article

Experimental Wave And Material Property Measurements For An Elastomer Binder And Particulate Composite Material, Caleb R. Heitkamp May 2018

Experimental Wave And Material Property Measurements For An Elastomer Binder And Particulate Composite Material, Caleb R. Heitkamp

Open Access Theses

The purpose of the work discussed here is to characterize the wave and material properties of polymer-bonded explosives (PBXs) at high frequencies. Knowing these properties could assist in the on-going development of methods for the detection and neutralization of improvised explosive devices (IEDs). The goal of this research was to experimentally measure these properties for mock energetic materials and develop a numerical model to replicate the experiment for the purpose of fully understanding and potentially bypassing the experimental procedures. Common materials science experiments were also performed on the materials studied in this work in order to maximize the fidelity of …

Go to article

Design, Modeling, And Control Of A Flying-Insect-Inspired Quadrotor With Rotatable Arms, Jin Hu May 2018

Design, Modeling, And Control Of A Flying-Insect-Inspired Quadrotor With Rotatable Arms, Jin Hu

Open Access Theses

Aerial manipulation and delivery using quadrotors are becoming more and more popular in recent years. However, the displacement of the center of gravity (CoG) is a common issue experienced by these applications due to various eccentric payloads carried. Conventional quadrotors with eccentric payloads are usually stabilized by robust control strategies through adjusting rotation speeds of BLDC motors, which has negative effects on stability and energy efficiency of quadrotors. In this thesis, a flying-insect-inspired quadrotor with rotatable arms is proposed. With four rotatable arms, the proposed quadrotor can automatically estimate the displacement of the CoG and drive the four arms to …

Go to article

Unsteady Fluid–Structure Interactions In Soft-Walled Microchannels, Tanmay C. Inamdar May 2018

Unsteady Fluid–Structure Interactions In Soft-Walled Microchannels, Tanmay C. Inamdar

Open Access Theses

A one-dimensional model is developed for the transient (unsteady) fluid–structure interaction (FSI) between a soft-walled microchannel and viscous fluid flow within it. An Euler–Bernoulli beam bending equation, which accounts for both transverse bending rigidity and nonlinear axial tension, is coupled to a one-dimensional fluid model obtained by depth-averaging (across the channel height) the two-dimensional incompressible Navier– Stokes equations. A novel feature of the proposed model is that the Navier–Stokes equations are scaled in the viscous (lubrication) limit relevant to microfluidics. The resulting set of coupled nonlinear partial differential equations are solved numerically through a segregated approach employing fully-implicit time stepping …

Go to article

Condensed Droplet Experiment For Nasa In Sub-Orbital Spaceflight, Trevor Mark Jahn May 2018

Condensed Droplet Experiment For Nasa In Sub-Orbital Spaceflight, Trevor Mark Jahn

Open Access Theses

Purdue’s Condensed Droplet Experiment for NASA in Sub-Orbital Spaceflight (ConDENSS) experiment was chosen by NASA’s Flight Opportunities Program for sub-orbital flight testing on a future Blue Origin New Shepard sub-orbital mission. ConDENSS seeks to test several predictions of existence and stability of static capillary droplets, plugs, and annular sleeves predicted by computational modeling. Application of the results includes advancing zero-gravity condenser technology and several possible applications on Earth. The payload is designed to form droplets, plugs, and sleeves of liquid by pumping pre-determined volumes of the liquid onto the walls of elliptical cone test sections. Four test sections with a …

Go to article

First Prev Next Last