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 1561 - 1590 of 8612

Full-Text Articles in Entire DC Network

Sustainable Supply Planning Of By-Product Minerals: A Case Study On Indium, Chul Hun Choi May 2018

Sustainable Supply Planning Of By-Product Minerals: A Case Study On Indium, Chul Hun Choi

Open Access Dissertations

Clean energy technologies represent a promising solution to the global warming challenge. However, many clean energy technologies depend on some rare materials, and concerns about demand of the materials have been raised recently. To make the concerns getting even worse, the materials are usually by-products of base metals, thus the supplies highly rely on the demand and production of the base metals. Indium is one of these materials. It is critical for two emerging clean energy applications, that is, copper indium gallium selenide photovoltaic, and light-emitting diode lighting. Like other rare materials, indium is also a by-product of base metal, …

Go to article

Choosing Wickedness: Moral Evil In Kant's Religion, Changtze Chia May 2018

Choosing Wickedness: Moral Evil In Kant's Religion, Changtze Chia

Open Access Dissertations

This dissertation concerns Kant’s doctrine of radical evil. The doctrine consists in the following two claims: (1) The propensity to evil is a universal propensity, found in every human being. It is therefore an innate disposition. (2) Every human being is morally responsible for the propensity to evil found in him. It is therefore a disposition that is freely chosen. The poor reception Kant’s doctrine of radical evil has received over the centuries can be traced to his insistence on these two claims. The doctrine has been censured for two reasons: (1) Kant appeals to empirical evidence in his argument …

Go to article

Hydration Shell Water Structure And Aggregation Of Small Amphiphilic Solutes, Shannon R. Pattenaude May 2018

Hydration Shell Water Structure And Aggregation Of Small Amphiphilic Solutes, Shannon R. Pattenaude

Open Access Dissertations

My research aims to address long-standing questions in physical chemistry about water-mediated hydrophobic and ionic interactions of biological relevance. For example, my research has provided some of the first experimental evidence of water driving hydrophobic groups apart rather than pushing them together in solution, thus damping rather than enhancing the contact free energy of oily molecules in water. I have also obtained some of the first experimental evidence concerning the structure of water structure around nonpolar groups in solution, thus demonstrating that hydrophobic hydration-shells have a clathrate hydrate-like structure. In addition, I am currently studying ionic interactions in water, which …

Go to article

Modeling Of Reynolds Stress Tensor With Embedded Galilean Invariance Using A Supervised Deep Learning Algorithm, Dominik Tobias Hauger May 2018

Modeling Of Reynolds Stress Tensor With Embedded Galilean Invariance Using A Supervised Deep Learning Algorithm, Dominik Tobias Hauger

Open Access Theses

Most flows of engineering interest are turbulent. Direct numerical or scale-resolved simulations (DNS) of turbulent flows could provide all of the information desired about such flows. However, these simulations are highly demanding computationally and are not feasible with today’s computing capabilities. Currently, turbulent flows of engineering interest are typically addressed by performing simulations based on the Reynolds Averaged Navier-Stokes (RANS) equations with the eddy-viscosity model. Despite the tremendous progress made, more research is still needed in developing more accurate and more broadly applicable eddy-viscosity models. Steve Pope in a JFM paper published in 1975 the most general expression for the …

Go to article

Synthesis Of Inhomogeneous Waves Using The Least-Squares Method, Trevor A. Kyle May 2018

Synthesis Of Inhomogeneous Waves Using The Least-Squares Method, Trevor A. Kyle

Open Access Theses

The aim of the work presented in this document is to demonstrate the versatility and applicability of least-squares reconstruction of acoustic waves. Appropriately tailored, certain kinds of acoustic waves are able to thermomechanically excite energetic materials in a safe, reliable manner. This allows for easier and more effective detection than current methods are able to offer. Typically, due to the large impedance difference between any given fluid and solid, it is exceedingly difficult to transmit energy between the two dissimilar media. However, it has been shown that certain spatially decaying plane waves, called inhomogeneous waves, are able to breach the …

Go to article

Development And Evaluation Of Automated Virtual Refrigerant Charge Sensor Training Kit, Akash Patil May 2018

Development And Evaluation Of Automated Virtual Refrigerant Charge Sensor Training Kit, Akash Patil

Open Access Theses

In a vapor compression system, the amount of refrigerant charge significantly affects the performance of the unit. Improperly charged systems run sub-optimally and thus result in higher operating costs due to increased energy usage. The unit can be undercharged due to a small leakage over the years. Similarly, the unit can be overcharged due to improper maintenance practices. Currently, there is no direct way to measure the amount of refrigerant in the system. In this thesis, virtual refrigerant charge sensors were developed and implemented for a rooftop unit using a previously developed approach. An open lab methodology with low cost …

Go to article

Numerical Simulation Of Combustion In The Ironmaking Blast Furnace Raceway, Tyamo Okosun May 2018

Numerical Simulation Of Combustion In The Ironmaking Blast Furnace Raceway, Tyamo Okosun

Open Access Dissertations

As almost all conversion of raw iron ore to pig iron at the start of the ironmaking process currently takes place in a blast furnace, these furnaces remain a critical component in the iron and steelmaking industry. Enhancements in the efficiency of blast furnace operation have a significant effect on industrial energy consumption, as the process represents nearly 70% of the total energy consumption of the iron and steelmaking process. Over the past several decades, auxiliary fuel injection has been adopted as a method of reducing the total amount of coke necessary for furnace operation. Coke making is both energy …

Go to article

Fast Direct Solvers And Effective Preconditioners For Large-Scale Sparse Matrices, Zixing Xin May 2018

Fast Direct Solvers And Effective Preconditioners For Large-Scale Sparse Matrices, Zixing Xin

Open Access Dissertations

The dissertation presents some fast direct solvers and efficient preconditioners mainly for sparse matrices. Hierarchical low-rank approximations such as hierarchically semiseparable (HSS) representation play a vital role in the development of these methods. As have been explored by many pioneers, hierarchical low-rank approximations can reduce the computational costs and the space requirement of many matrix operations while preserving desired accuracy. The utilization of such techniques leads to many fast algorithms for both dense and sparse matrix computations. One of the significant contributions of this dissertation is that we propose some novel preconditioners for both dense and sparse symmetric positive definite …

Go to article

Applications Of Context-Aware Systems In Enterprise Environments, Oyindamola D. Oluwatimi May 2018

Applications Of Context-Aware Systems In Enterprise Environments, Oyindamola D. Oluwatimi

Open Access Dissertations

In bring-your-own-device (BYOD) and corporate-owned, personally enabled (COPE) scenarios, employees’ devices store both enterprise and personal data, and have the ability to remotely access a secure enterprise network. While mobile devices enable users to access such resources in a pervasive manner, it also increases the risk of breaches for sensitive enterprise data as users may access the resources under insecure circumstances. That is, access authorizations may depend on the context in which the resources are accessed. In both scenarios, it is vital that the security of accessible enterprise content is preserved. In this work, we explore the use of contextual …

Go to article

A Study Of The Characteristics Of A Differential Privacy Implementation, Niveah T. Abraham May 2018

A Study Of The Characteristics Of A Differential Privacy Implementation, Niveah T. Abraham

Open Access Theses

Building on the theoretic strength of differential privacy, researchers at the University of California Berkeley have built a tool called FLEX that incorporates differential privacy and have tested FLEX using a dataset based on actual queries submitted by Uber’s employees. In their research, a novel idea called elastic sensitivity was introduced to implement differential privacy; this research in turn tests these concepts on datasets from several domains including automobile, medical, network, password, and social media areas. This research also checks for statistical information gathering accuracy from the datasets and observes performance overhead for queries. The study also presents the results …

Go to article

Safeguardp: An Architecture For Mediated Control Of Desktop Applications By Untrusted Crowd Workers, Sylvia T. Carrell May 2018

Safeguardp: An Architecture For Mediated Control Of Desktop Applications By Untrusted Crowd Workers, Sylvia T. Carrell

Open Access Theses

The future of crowdsourcing depends on improving usability for the requesters who post jobs. Allowing workers to perform tasks directly on a requester’s computer could help, by obviating the need to adapt data into formats that a crowdsourcing platform can handle. However, granting remote access to a requester’s desktop would also pose the risk the workers might steal information or take malicious actions. This thesis presents SafeguaRDP, an architecture designed to enable future services in which a mediated and redacted desktop is shown to a remote worker. The redaction of the desktop does not modify any files on the desktop; …

Go to article

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

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

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

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

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

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

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

A Multi-Fidelity Approach To Address Multi-Objective Constrained Mixed-Discrete Nonlinear Programming Problems With Application To Greener Aircraft Design, Samarth Jain May 2018

A Multi-Fidelity Approach To Address Multi-Objective Constrained Mixed-Discrete Nonlinear Programming Problems With Application To Greener Aircraft Design, Samarth Jain

Open Access Theses

Engineering problems often involve solving constrained multi-objective Mixed-Discrete Nonlinear Programming (MDNLP) problems. These problems are inherently difficult to solve given the presence of multiple competing objectives, nonlinear objective and constraint functions, mixed-discrete type design variables, and expensive analysis tools. This work presents a multi-fidelity approach that addresses all these features together and exhibits its efficacy to solve constrained multi-objective MDNLP problems within a reasonable computational budget. The work addresses the high computational cost drawback associated with a previously developed “hybrid multi-objective optimization approach” that combines a Genetic Algorithm (GA) with the gradient-based Sequential Quadratic Programming (SQP) algorithm. The multi-fidelity hybrid …

Go to article

The Role Of Direct Insolation And Near-Surface Moisture Advection In The Recovery Of Cape On 31 March 2016 During Vortex-Southeast, Allison Lafleur May 2018

The Role Of Direct Insolation And Near-Surface Moisture Advection In The Recovery Of Cape On 31 March 2016 During Vortex-Southeast, Allison Lafleur

Open Access Theses

The relative roles of direct insolation and near-surface moisture advection in the recovery of convective available potential energy (CAPE) on 31 March 2016 in northern Alabama are examined using VORTEX-Southeast observations and numerical simulations. In between rounds of nontornadic morning storms and tornadic evening storms, CAPE over the VORTEX-Southeast domain increased from near zero to at least 500 J kg-1. A timeline of the day’s events is provided with a focus on the evolution of the lower levels of the atmosphere. In particular, we focus on its responses to solar insolation and moisture advection, which are hypothesized as the main …

Go to article

Air Traffic Delay Prediction Based On Machine Learning And Delay Propagation, Meng Li May 2018

Air Traffic Delay Prediction Based On Machine Learning And Delay Propagation, Meng Li

Open Access Theses

Flight Delay creates significant problems in the current aviation system. Methods are needed to analyze the manner in which delay propagates in the airport networks. Traditional methods are inadequate to the task. This paper presented a new machine learning based air traffic delay prediction model that combined multi-label random forest classification and approximated delay propagation model. To improve the prediction performance, an optimal feature selection process is introduced and demonstrated to have better performance than directly using all the features of available datasets. Departure delay and late arriving aircraft delay are shown to be the most critical features for delay …

Go to article

Deep Neural Network Architectures For Modulation Classification, Xiaoyu Liu May 2018

Deep Neural Network Architectures For Modulation Classification, Xiaoyu Liu

Open Access Theses

This thesis investigates the value of employing deep learning for the task of wireless signal modulation recognition. Recently in deep learning research on AMC, a framework has been introduced by generating a dataset using GNU radio that mimics the imperfections in a real wireless channel, and uses 10 different modulation types. Further, a CNN architecture was developed and shown to deliver performance that exceeds that of expert-based approaches. Here, we follow the framework of O’shea [1] and find deep neural network architectures that deliver higher accuracy than the state of the art. We tested the architecture of O’shea [1] and …

Go to article

A Vehicle Routing Problem With Payload-Range Dependency By Fuel Consumption, Archit Chandrakant Mokashi May 2018

A Vehicle Routing Problem With Payload-Range Dependency By Fuel Consumption, Archit Chandrakant Mokashi

Open Access Theses

In this research, a new variant of vehicle routing problem is introduced. Fuel consumption constitutes a significant component of transportation costs especially when large volumes of goods are transported using means of transportation such as aircrafts. Hence, the objective of this research is to perform efficient routing of a heterogeneous fleet of vehicles such that fuel consumption costs are minimized. Reduced fuel consumption also reduces greenhouse gases emission and creates a positive impact on the environment. Another unique characteristic studied is the dependence between load carried by a vehicle and the maximum distance it can travel without stopping. Weight of …

Go to article

Feature Learning As A Tool To Identify Existence Of Multiple Biological Patterns, Aleksandr Patsekin May 2018

Feature Learning As A Tool To Identify Existence Of Multiple Biological Patterns, Aleksandr Patsekin

Open Access Theses

This paper introduces a novel approach for assessing multiple patterns in biological imaging datasets. The developed tool should be able to provide most probable structure of a dataset of images that consists of biological patterns not encountered during the model training process. The tool includes two major parts: (1) feature learning and extraction pipeline and (2) subsequent clustering with estimation of number of classes. The feature-learning part includes two deep-learning techniques and a feature quantitation pipeline as a benchmark method. Clustering includes three non-parametric methods. K-means clustering is employed for validation and hypothesis testing by comparing results with provided ground …

Go to article

Cooperative Planning System For Self-Separation In En-Route Airspace, Varun S. Sudarsanan May 2018

Cooperative Planning System For Self-Separation In En-Route Airspace, Varun S. Sudarsanan

Open Access Theses

The increase in flight density and the need to integrate Unmanned Areal Vehicles into the National Airspace demands higher flexibility. Distributing the conflict detection and resolution (CD&R) functions among the aircraft ensures a greater flexibility in the flight plans for the aircraft. A co-operative planning system is proposed for separation assurance by distributing the CD&R in the en-route airspace among a fully-connected network of aircraft. The aircraft cooperate to achieve the common goal of conflict-free trajectories, while attempting to reduce the disruptions from their original flight plans. A pairwise CD&R algorithm is developed through heuristics which is then implemented iteratively …

Go to article

Deep Neural Network Regression And Sobol Sensitivity Analysis For Daily Solar Energy Prediction Given Weather Data, Yixuan Sun May 2018

Deep Neural Network Regression And Sobol Sensitivity Analysis For Daily Solar Energy Prediction Given Weather Data, Yixuan Sun

Open Access Theses

Solar energy forecasting plays an important role in both solar power plants and electricity grid. The effective forecasting is essential for efficient usage and management of the electricity grid, as well as for the solar energy trading. However, many of the existing models or algorithms are based on real physical laws, where tons of calculations, step-by-step modification, and many inputs are required. In this research, a novel deep Multi-layer Perceptron (MLP) based regression approach for predicting solar energy is proposed, in which the inputs are only ensemble weather forecasting data. The results demonstrate that our proposed deep Multi-layer Perceptron based …

Go to article

Sentiment Analysis On Financial News And Microblogs, Chinmay Talekar May 2018

Sentiment Analysis On Financial News And Microblogs, Chinmay Talekar

Open Access Theses

Sentiment analysis is useful for multiple tasks including customer satisfaction metrics, identifying market trends for any industry or products, analyzing reviews from social media comments. This thesis highlights the importance of sentiment analysis, provides a summary of seminal works and different approaches towards sentiment analysis. It aims to address sentiment analysis on financial news and microblogs by classifying textual data from financial news and microblogs as positive or negative. Sentiment analysis is performed by making use of paragraph vectors and logistic regression in this thesis and it aims to compare it with previously performed approaches to performing analysis and help …

Go to article

Performance Enhancement Of Logistic Regression For Big Data On Spark, Mengyao Wang May 2018

Performance Enhancement Of Logistic Regression For Big Data On Spark, Mengyao Wang

Open Access Theses

This research proposes a new ftting algorithm of logistic regression on IRWLS that utilizes the procedure of scanning data row-by-row and has the ability to acquire an exact result with only a few iterations. Furthermore, this research also realizes the distributed parallelization of the proposed method on Spark and conducts various experiments to manifest its memory-wise advantage over the traditional methods such as Spark MLlib package. The results show that the proposed method can provide an exact result rather than an approximated one within 5 or 6 iterations; achieve a satisfying accuracy for fight delay prediction within 1 or 2 …

Go to article

Mathematical Model Of Interstitial Fluid Flow And Characterization Of The Lacunar Canalicular System In Cortical Bone, Melanie B. Venderley May 2018

Mathematical Model Of Interstitial Fluid Flow And Characterization Of The Lacunar Canalicular System In Cortical Bone, Melanie B. Venderley

Open Access Theses

While the mechanotransductive capability of skeletal tissue has been acknowledged for decades, the exact mechanisms that enable bone to sense and respond to external stimuli have remained elusive. Numerous theories have evolved to explain this behavior, most notably those involving fluid movement through the tissue’s hierarchical structure. Within mineralized bone, osteocytes reside in micro and nanoporosities, known as lacunae and canaliculi, which house the cell body and their long cellular processes, respectively. Through this lacunar-canalicular system (LCS), osteocytes form an interconnected network, which allow signaling and communication with surrounding osteocytes via gap junctions and secreted factors. It has been theorized …

Go to article

First Prev Next Last