Engineering Commons^™

Effects Of Hip And Ankle Moments On Running Stability: Simulation Of A Simplified Model, Rubin C. Cholera

Open Access Theses

In human running, the ankle, knee, and hip moments are known to play different roles to influence the dynamics of locomotion. A recent study of hip moments and several hip-based legged robots have revealed that hip actuation can significantly improve the stability of locomotion, whether controlled or uncontrolled. Ankle moments are expected to also significantly affect running stability, but in a different way than hip moments. Here we seek to advance the current theory of dynamic running and associated legged robots by determining how simple open-loop ankle moments could affect running stability. We simulate a dynamical model, and compare it …

Digital Image Correlation Of Heterogeneous Deformations In Polycrystalline Material With Electron Backscatter Diffraction, Javier Esquivel

Open Access Theses

This work establishes the ability to conduct digital image correlation (DIC) investigations at varying length scales. DIC allows for a computational method of strain field measurements using multiple images to track random speckle patterns on material surfaces. The use of a powder silicon oxide speckle allows for high optical magnification correlation using conventional load frames. Self-assembling gold nanoparticles provide sub-micron resolution speckle patterns to study microstructure influences on deformation using scanning electron microscopy. The complex microstructure in aerospace grade aluminum and nickel-based superalloys, give rise to varied deformation fields, which can be studied using electron backscatter diffraction. Specimen preparation techniques, …

Principle Of Bio-Inspired Insect Wing Rotational Hinge Design, Fan Fei

Open Access Theses

A principle for designing and fabricating bio-inspired miniature artificial insect flapping wing using flexure rotational hinge design is presented. A systematic approach of selecting rotational hinge stiffness value is proposed. Based on the understanding of flapping wing aerodynamics, a dynamic simulation is constructed using the established quasi-steady model and the wing design. Simulations were performed to gain insight on how different parameters affect the wing rotational response. Based on system resonance a model to predict the optimal rotational hinge stiffness based on given wing parameter and flapping wing kinematic is proposed. By varying different wing parameters, the proposed method is …

High Voltage Rear Electric Drivetrain Design For A Parallelthrough-The-Road Plug-In Hybrid Electric Vehicle, Adam Garrett Fogarty

Open Access Theses

Purdue University was selected as one of 15 universities to participate in a three year Advanced Vehicle Technology Competition (AVTC) called EcoCar2: Plugging Into the Future. The vehicle built by the Purdue team was a Parallel-Through-The-Road Plug-in Hybrid Electric Vehicle (PTTR PHEV). The vehicle utilized a B20 diesel powertrain to power the front wheels, as well as a custom electric drivetrain to power the rear wheels. Using this vehicle during the final year of the competition, the team was successful in placing 4th overall as well as 2nd in the category of Well-To-Wheel (WTW) Greenhouse Gas Emissions. A stock 2013 …

Application Of Bayesian Networks In Consumer Service Industry, Yuan Gao

Open Access Theses

Gao, Yuan. M.S.I.E., Purdue University. December 2014. Application of Bayesian Networks in Consumer Service Industry. Major professor: Vincent G. Duffy The purpose of the present study is to explore the application of Bayesian networks in the consumer service industry to model causal relationships within complex risk factor structures using aggregate data. An analysis of the Hawaii tourism market was conducted to find out how visitor characteristics affect their behavior and experience as consumers during the trips, and influence the tourism market outcomes represented by measurable factors. Two hypotheses were proposed regarding the use of aggregate data and the influence of …

Distinguishing Harmonic Behavior Of Longitudinal Resonant Combustion In A Variable Geometry Model Rocket Combustor, Sarah W. Hester

Open Access Theses

Throughout the study of high frequency combustion instability in a single element Continuously Variable Resonance Combustor (CVRC), the excitation of the fundamental longitudinal mode is closely followed by the excitation of higher harmonic modes. In an attempt to establish a heuristic relationship between the appearances of the fundamental mode and its harmonics, several unstable fixed geometry and variable geometry tests from the CVRC are analyzed through traditional Fourier-based methods and alternative signal processing methods such as wavelet analysis and Instantaneous Frequency (IF) Analysis from PC Signal Analysis. Early results led to the conclusion that traditional Fourier-based analysis provides believable and …

Crossflow Transition At Mach 6 On A Cone At Low Angles Of Attack, Ryan O. Henderson

Open Access Theses

Experiments on a sharp 7-degree cone at low angles of attack were conducted at Mach 6 to understand the stationary and traveling modes of crossflow disturbances, the interaction between them, and the development of other instabilities that can lead to transition. Using the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT), pressure and temperature measurements were collected to better describe crossflow characteristics. Noisy and quiet flow conditions were compared to understand crossflow development. Temperature Sensitive Paint (TSP) was used to measure the global surface temperatures on the model. Schmidt-Boelter (SB) gauges were used to convert the surface temperatures to heat transfer. The global …

Joint Architecture For Reusable Vehicle-Integrated Software (J.A.R.V.I.S), Anthony Mark Kane

Open Access Theses

An integrated software architecture for development of unmanned research vehicles is developed. It has been created under the premise that all unmanned vehicles require a core set of functionality that is common across platforms and that priority should be to the readability and reusability of the code base. The architecture defines the top-level system interfaces allowing internal algorithms to be manipulated without affecting the rest of the system. A robust aerospace toolbox has been developed that provides a means to rapidly prototype algorithms without the need of recreating commonly used functions or the use of expensive, proprietary software.

Dynamic Wireless Power Transfer System For The Unmanned Aerial Vehicles, Tae Sup Lee

Open Access Theses

UAVs have limitless applications to help our daily lives for the autonomous operations. UAVs have a limited power capacity due to weight constraints and are therefore not able to travel long distances. Ground stations for recharging UAVs throughout different points can increase the flight time of the UAVs with the current UAV battery capacity. This study investigates how the wireless charging system for the ground station can be made more robust when there are misalignments. The wireless charging system is monitored by an Arduino, micro controller, to assess the current condition of charging. The Arduino is able to change the …

Mode I Fatigue Delamination Onset Of Carbon Fibre Reinforced Polymer With Novel Post-Cure Throughthickness Reinforcement, Christopher John Kourloufas

Open Access Theses

A novel trough thickness reinforcement (TTR) technique, proposed by Kravchenko et al., has been tested under mode I fatigue loading conditions in order to investigate characterisation of the onset of delamination growth in unidirectional 8552/IM7. The experimental results, following standard test method ASTM D6115-13, indicate that the mode I fatigue delamination onset behaviour can be altered by the inclusion of TTR both ahead and behind the crack tip. Tests have been conducted at a wide range of maximum displacement values, corresponding to percentages of the critical fracture toughness value determined for the maternal, GIC . The results were found …

Spatial And Temporal Patterns Of Geo-Tagged Tweets, Yue Li

Open Access Theses

With over 500 million current registered users and over 500 million tweets per day, Twitter has caught the attention of scientists in various disciplines. As Twitter allows users to send messages with location tags, a massive amount of valuable geo-social knowledge is embedded in tweets, which can provide useful implications for human geography, urban science, location-based service, targeted advertising, and social network studies. This thesis aims to determine the lifestyle patterns of college students by analyzing the spatial and temporal dynamics in their tweets. Geo-tagged tweets are collected over a period of six months for four US Midwestern college cites: …

Synthesis Of Multilayered Microparticles For Targeted Drug Delivery, Elizabeth Mercer

Open Access Theses

Microparticles have been shown to be valuable in targeted drug delivery which can lead to an increased dose delivered to a targeted location, reduced patient side effects, and improved patient outcomes. The designed multilayered microparticles have the clinical application to deliver hydrophobic drugs to a targeted area. The composition of the microparticles consists of a poly-lactic acid (PLA) polymer core surrounded by a polymeric shell composed of Poly(lactic-co-glycolic acid)-Poly(ethylene glycol)-Maleimide(PLGA-PEG-Mal). The maleimide promotes conjugation of the collagen binding peptide, SILY. Targeting to type I collagen allows for this microparticle system to attach to exposed collagen in atherosclerotic vessels.

A novel …

Using A Centrifuge For Quality Control Of Pre-Wetted Lightweight Aggregate In Internally Cured Concrete, Albert E. Miller

Open Access Theses

Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always …

High-Purity Gallium Analysis By Inductively Coupled Plasma Mass Spectrometry, Kyungjean Min

Open Access Theses

The mobility of Two-dimensional Electron Gas in AlGaAs/GaAs heterostructures that are grown in the Molecular Beam Epitaxy (MBE) can be increased by purification of the gallium used to grow the films. To attain 200 million cm2/Vs mobility, the impurity concentration of gallium should be reduced to below 1 ppb. The commercial 7N (99.99999%) gallium with 100 ppb total impurity is currently used in the MBE at Purdue University and is being purified by zone refining. To evaluate the commercial 7N gallium and establish the methodology for the impurity measurement after zone refining, germanium, iron, and zinc in 6N and 7N …

Designing Sustainable Mentoring Programs: Examining The Role Of Social Community In The Stem College Student Experience, Joi-Lynn Mondisa

Open Access Theses

In order to begin to understand how to design programs that promote community development and produce beneficial outcomes for community members, we must first define the elements and functions of such a community. In this thesis, I define social community as an environment where like-minded individuals engage indynamic, multidirectional interactions that facilitate social support . Using a human-integrated systems approach, I propose a social community model for STEM minority mentoring programs to understand how a community's design plays a role in the learning and enrichment of its members. The social community model is comprised of three main components: program …

Design And Analysis Of A Cable-Driven Test Apparatus For Flapping-Flight Research, Stephen J. Musick

Open Access Theses

The biology, physiology, kinematics, and aerodynamics of insect flight have been a longstanding fascination for biologists and engineers. The former three are easily obtained through the observation of the organic species. The latter though, is very difficult to study in this fashion. In many cases, aerodynamic forces and fluid-body interactions can be simulated with computational fluid dynamics; another option is to use dynamically-scaled, experimental set-ups to measure physically these values.

An archetypal, experimental set-up may include one or two scaled wings, where each wing is actuated to achieve upwards of three degrees of freedom. The three degrees of freedom correspond …

Watershed Delineation In The Field: A New Approach For Mobile Applications Using Lidar Elevation Data, Samuel Adam Noel

Open Access Theses

With the advancement of mobile devices, opportunities to take watershed management tasks out of the office and into the field can be realized. In turn, field workers can utilize these technologies to expedite the decision-making process so that they may focus on meeting with clients and addressing agricultural watershed management issues. High-resolution (∼1.5 m postspacing) elevation data gathered by light detection and ranging (LiDAR) provides the topographic detail necessary to model hydrology at the field-scale (∼1 km2).

Non-artifactual surface depressions lead to erroneous surface flow patterns when using existing algorithms. So a sequential depression-filling algorithm (SDFA) has been developed to …

Evaluation Of Lane Use Management Strategies, Chaitanya Paleti Siva Sai Krishna

Open Access Theses

The limited funding available for roadway capacity expansion and the growing funding gap, in conjunction with the increasing congestion, creates a critical need for innovative lane use management options. Various cost-effective lane use management strategies have been implemented in the United States and worldwide to address these challenges. However, these strategies have their own costs, operational characteristics, and additional requirements for field deployment. Hence, there is a need for systematic methodologies to evaluate lane use management strategies.

In this thesis, a systematic simulation-based methodology is proposed to evaluate lane use management strategies. It involves identifying traffic corridors that are suitable …

Algorithm Development And Analysis For Advanced Enginetechnologies Including Piezoelectric Fuel Injection And Variablevalve Actuation, Bradley W. Pietrzak

Open Access Theses

As vehicle emissions standards and fuel economy constraints become increasingly strict, the automotive industry must employ the use of advanced engine technologies to overcome these challenges. Fuel injection rate shaping and cylinder deactivation (CDA) are two such technologies, and both of them require the design and implementation of algorithms using various hardware and software tools.

Fuel injection rate shaping is one path towards cleaner and more efficient diesel engines. Piezoelectrically-actuated fuel injectors are well-suited for rate shaping operation, but are difficult to control. Control-related challenges arise primarily due to the lack of measurements available in a fuel injection system on-engine, …

Identifying Conditions To Optimize Lactic Acid Production From Food Waste, Raymond M. Redcorn

Open Access Theses

There is an increased demand for lactic acid for the production of biopolymers and to aid nutrient removal in wastewater treatment. Food waste offers a source of soluble sugars to produce lactic acid, which does not increase land demand, but digestion conditions have yet to be optimized when co-digested with primary sludge. Food waste was collected from cafeteria waste bins, homogenized and seeded with primary sludge. A Box Behnken Response surface design was used to optimize lactic acid production based on pH, temperature, loading rate, and retention time. Subsequent experiments verified and refined those conditions to optimize for both yield …

Analysis Of The Impact Of Early Exhaust Valve Opening And Cylinder Deactivation On Aftertreatment Thermal Management And Efficiency For Compression Ignition Engines, Leighton Edward Roberts

Open Access Theses

In order to meet strict emissions regulations, engine manufacturers have implemented aftertreatment technologies which reduce the tailpipe emissions from diesel engines. The effectiveness of most of these systems is limited when exhaust temperatures are low (usually below 200°C to 250°C). This is a problem for extended low load operation, such as idling and during cold start. Use of variable valve actuation, including early exhaust valve opening (EEVO) and cylinder deactivation (CDA), has been proposed as a means to elevate exhaust temperatures. This thesis discusses a research effort focused on EEVO and CDA as potential enablers of exhaust gas temperature increase …

Development Of Sound Quality Metrics For Gear Rattle In Diesel Engines, Brandon Sobecki

Open Access Theses

Sound quality is an important factor in the design of competitive diesel engines. The noise produced by specific components and mechanisms in the engine can play a significant role in determining the perceived quality of the overall noise and in turn the perceived quality of the engine. The goal of the present research is to characterize the sounds produced by the phenomenon known as gear rattle and to develop a model that can be used to assess gear rattle levels in a way that connects directly with human perception of rattle. Most previous work in this area has been focused …

Measurement Of The Responses Of Polyurethane And Confortm Foams And The Development Of A System Identification Technique To Estimate Polyurethane Foam Parameters From Experimental Impulse Responses, Vaidyanadan Sundaram

Open Access Theses

Flexible polyurethane foam is the main cushioning element used in car seats. Optimization of an occupied seat's static and dynamic behavior requires models of foam that are accurate over a wide range of excitation and pre-compression conditions. Experiments were conducted to measure the response of foam over a wide range of excitation which include slowly varying uniaxial compression tests on a 3 inch cube foam sample, base excitation and impulse excitation test on a foam-mass system. The foam used was the same in all of the experiments, thus obtaining all the responses on the same foam sample which helps eliminate …

Evaluating Intensity As A Controller Function For Nextgen Scenarios With Increased Capacity, Caitlin Anne Surakitbanharn

Open Access Theses

Automated separation assurance is the most mature concept to handle increasing airspace traffic and capacity needs, yet the system lacks a way to pre-emptively identify aircraft separation problems. The intensity control measure looks to find situations where if an aircraft pair makes an unplanned change in heading or altitude at the wrong moment, an unrecoverable situation arises. This research analyzes static, open loop air traffic data in an en-route sector to determine how many high intensity aircraft pairs (HIP) exist per minute, and if the intensity measure is a safely manageable function for air traffic controllers. It is found that …

Waste Heat Recovery Options In A Large Gas-Turbine Combined Power Plant, Ularee Upathumchard

Open Access Theses

This study focuses on power plant heat loss and how to utilize the waste heat in energy recovery systems in order to increase the overall power plant efficiency. The case study of this research is a 700-MW natural gas combined cycle power plant, located in a suburban area of Thailand. An analysis of the heat loss of the combustion process, power generation process, lubrication system, and cooling system has been conducted to evaluate waste heat recovery options. The design of the waste heat recovery options depends to the amount of heat loss from each system and its temperature. Feasible waste …

Computational Fluid Dynamics Analysis Of Freeze Drying Process And Equipment, Nikhil P. Varma

Open Access Theses

Freeze drying is an important, but expensive, inefficient and time consuming process in the pharmaceutical, chemical and food processing industries. Computational techniques could be a very effective tool in predictive design and analysis of both freeze drying process and equipment. This work is an attempt at using Computational Fluid Dynamics(CFD) and numerical simulations as a tool for freeze drying process and equipment design.

Pressure control is critical in freeze dryers, keeping in view the product stability. In industrial freeze dryers, loss of pressure control can lead to loss of an entire batch. Pressure variation within the chamber could also lead …

Transport In Ultra-Thin Heat Pipes For Low Power Applications, Yashwanth Yadavalli

Open Access Theses

Heat pipes and vapor chamber heat spreaders offer a potential solution to the increasing thermal management challenges in thin-form-factor mobile computing platforms, where efficient spreading is required to simultaneously prevent overheating of internal components and formation of hot regions on the device exterior surfaces. The operating conditions for such applications are also characterized by low input heat fluxes, which in combination with the geometric constraints, give rise to unique performance limitations that require examination. This thesis aims to characterize the steady-state and transient heat pipe performance limitations unique to such ultra-thin form factors, and characterizes the key heat transfer mechanisms …

Impact Of Nanostructure On Polymer-Based Nonvolatile Memory Devices, Seung Hyun Sung

Open Access Theses

Memory functionality is essential for many high-end electronic applications (e.g. , smart phones, personal computers). Particularly, organic nonvolatile memory devices based on polymer ferroelectric materials are a promising approach toward the development of low-cost memory due to the ease of processing and flexibility associated with the device. Here, we will focus on a memory device with a two-component active layer and a diode structure. This ferroelectric diode (FeD) has a nanostructured active layer, composed of ferroelectric and semiconducting polymers, and it can provide easy access to high-performance polymer-based memory devices. In order to create these nanostructured active layers, we …

Dissolution Rate And Mechanism Of Metals In Molten Aluminum Alloy A380, Hengyu Zhu

Open Access Theses

Shot sleeve is a very easily worn out part in a high-pressure die-casting machine due to serious dissolution of the area underneath the pouring hole. It is because during a normal pouring process, the high temperature molten aluminum will impact and dissolve that area of the shot sleeve by complex chemical and physical process. Rotation experiment was carried out to H13 and four kinds of refractory metal samples. SEM and EDS pictures were taken in order to investigate the microstructure and the dissolution mechanism of these materials. This suggests a high strength niobium is an ideal material for that area …

Fire Behavior Of Bolted Connections, Qiaqia Zhu

Open Access Theses

Bolted connection failures have been observed in building fires and large-scale structural fire tests. Limited information is available on plate bearing behavior at elevated temperatures. The failure mode of a shear-tab connection could change from plate bearing failure to bolt shear failure between 400 (degree Celsius) °C to 600°C. Component-based models have been used to predict the behavior of bolted connections. Earlier researchers have developed simple mathematical models to represent the force-displacement relationships of bolt shear and plate bearing components of bolted connections. However, these models need to be verified experimentally for US building construction and materials. Therefore, eleven single-bolted …