Engineering Commons^™

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 …

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 …

Studies Of Systems With Nonholonomic Constraints: The Segway And The Chaplygin Sleigh, Joseph Troy Lee Tuttle

Open Access Theses

In this thesis, two systems with nonholonomic systems are investigated: the Segway and the Chaplygin sleigh. Using Lagrangian mechanics, the constrained nonlinear equations of motion for both systems are derived. By use of the nullspace of the constraint matrices, the unconstrained equations of motion can be obtained. For the Segway, these equations are linearized about a zero equilibrium state, placed into state space form and decoupled. A feedback controller is designed about the velocity and heading angle rate reference commands. To compare to the real data from the built Segway, measurement noise was also included in the model. Experimental data …

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 …

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 …

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 …

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 …

Optical Properties Of Silicon Core/Multi-Shell Nanowires Using Fdtd And Ema Methods, Tae Kon Kim

Open Access Theses

Semiconductor nanowires are attracting intense interest as a promising material for solar energy conversion for the new-generation photovoltaic (PV) technology. In particular, silicon core/multi-shell nanowires (SiNWs) are under active investigation for PV and solar water splitting applications because they offer novel approaches for solar to electric energy or fuel conversion leading to high efficiency devices. ^ Theoretical studies using the finite-different time-domain method have been performed to investigate the optical properties of many nanostructure arrays, however, they are computationally intensive and require periodic condition, which may not be satisfied with most fabricated samples. In the present study, effective medium approximation …

Capacity-Related Driver Behavior On Modern Roundabouts Built On High-Speed Roads, Shaikh Ahmad

Open Access Theses

The objective of this thesis was to investigate the factors that affect capacity-related driver behavior on modern roundabouts built on high-speed roads. The capacity of roundabouts is strongly affected by the behavior of drivers as represented by critical headway (critical gap) and follow-up headway (follow-up time). The effects of heavy vehicles (single-unit truck, bus, and semi-trailer) and area type (rural or urban) on roundabout capacity were investigated by comparing the critical headways for roundabouts located on high-speed and low-speed roads. The effects of nighttime conditions (in the presence of street lighting) were also considered. Data were collected using the Purdue …

Solar Sail Trajectory Design In The Earth-Moon Circular Restricted Three Body Problem, Ashwati Das

Open Access Theses

The quest to explore the Moon has helped resolve scientific questions, has spurred leaps in technology development, and has revealed Earth's celestial companion to be a gateway to other destinations. With a renewed focus on returning to the Moon in this decade, alternatives to chemical propulsion systems are becoming attractive methods to efficiently use scarce resources and support extended mission durations. Thus, an investigation is conducted to develop a general framework, that facilitates propellant-free Earth-Moon transfers by exploiting sail dynamics in combination with advantageous transfer options offered in the Earth-Moon circular restricted multi-body dynamical model. Both periodic orbits in the …

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 …

Using Energy-Efficient Technologies To Produce Bedding Plants And Microgreens In Protected And Controlled Environments, Joshua R. Gerovac

Open Access Theses

Gerovac, Joshua R. M.S., Purdue University, December 2014. Using Energy-Efficient Technologies to Produce Bedding Plants and Microgreens in Protected and Controlled Environments. Major Professor: Roberto G. Lopez. Production of bedding plants in commercial greenhouses (GHs) located in northern latitudes begins in late winter and continues through late spring when low outdoor temperatures generally necessitate active heating to maintain temperatures suitable for growth and development. Meanwhile, year-round production of microgreens using multi-layer systems requires sole-source (SS) photosynthetic lighting for production. Energy used to provide active heating in commercial GHs or SS lighting in multi-layer systems is second only to labor as …

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.

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: …

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 …

A Computational Analysis Of The Aerodynamic And Aeromechanical Behavior Of The Purdue Multistage Compressor, David Monk

Open Access Theses

Compressor design programs are becoming more reliant on computational tools to predict and optimize aerodynamic and aeromechanical behavior within a compressor. Recent trends in compressor development continue to push for more efficient, lighter weight, and higher performance machines. To meet these demands, designers must better understand the complex nature of the inherently unsteady flow physics inside of a compressor. As physical testing can be costly and time prohibitive, CFD and other computational tools have become the workhorse during design programs.

The objectives of this research were to investigate the aerodynamic and aeromechanical behavior of the Purdue multistage compressor, as well …

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 …

Indoor Acoustic Mapping And Geolocation, Thomas Shyy

Open Access Theses

The Global Positioning System (GPS) is widely used in navigations of flights, vehicles and travelers nowadays. However, the signals are not always available and there are some cases where the receptions of the GPS signal can be lost because of the presence of urban canyons, buildings, tunnels and forests. Another down side for the GPS is that indoor positioning can be really difficult because of the greater signal interference from the indoor.

On the other hand, the concept of echolocation has also been used for positioning purposes. Echolocation offers a promising approach to improve the quality of life of people …

Evaluation Of Collapse Indicators For Seismically Vulnerable Reinforced Concrete Buildings, Nicholas R. Skok

Open Access Theses

Older reinforced concrete buildings can be prone to column shear and compression failures during earthquakes because of inadequate transverse reinforcement. Cities in seismic areas still have large inventories of older and potentially deficient buildings. To analyze every building and estimate its vulnerability in detail is costly. A simple method to rank quickly older buildings according to their seismic vulnerability is needed to help engineers prioritize the use of resources for rehabilitating the most vulnerable buildings.

Four indicators of building damage or collapse were evaluated using numerical analysis and prior data from building surveys: column index (Hassan & Sozen, 1997), R …

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 …

Realization And Evaluation Of A 3-Degrees-Of-Freedom Mouse Model, Udayan Umapathi

Open Access Theses

Kinesiology research has shown that translation and rotation are inseparable actions in the real world. Motivated by this fact, this thesis explores a model for the computer mouse, the new addition being rotational input about vertical axis of a mouse. We realize our model through Mushaca, a 3-degrees-of-freedom mouse (3DOF mouse) that can sense rotation, in addition to sensing XY planar translation. The thesis presents two realizations of Mushaca - namely a MEMS version that uses accelerometer and gyroscope, and an optical sensor version that uses two optical sensors. Through a controlled user study we try to find out if …

Piston / Cylinder Interface Of Axial Piston Machines – Effect Of Piston Micro-Surface Shaping, Ashley M. Wondergem

Open Access Theses

Axial piston machines are widely used in current industries such as aerospace, agriculture, automotive, heavy machinery, military, etc. Thus new cost-effective and highly efficient designs with better performance and reliability are needed. These new, high efficient pumps and motors will also aid in new applications such as hybrid hydrostatic transmissions and displacement controlled actuation. The aim of this work is to study how to reduce the energy dissipation (increase efficiency) while also improving the load carrying ability of the fluid film between the piston and the cylinder through surface shaping of the piston over a wide range of operating conditions. …

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 …

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 …

Evaluation Of Methods For Estimating Prestress Losses In High-Strength Structural Concrete, Mayren Yelitza Mata Carrillo

Open Access Theses

The purpose of this study was to evaluate the applicability of several current approaches used to estimate losses in prestressed concrete members with compressive strengths greater than 15ksi. The scope of the study focused on time-dependent losses for normal weight concrete bonded applications. The approaches evaluated were the PCI Design Handbook (2010) method, the AASHTO Specifications (2012) refined method, the PCI Bridge Design Manual (2003) time-dependent analysis using both the AASHTO (2012) and the PCI-BDM (2003) creep and shrinkage models, and a time-step method developed by Swartz (2010). The methods were compared to existing data on prestress losses from twenty-two …

Experimental Study Of Droplet Capable Conductivity Probe, Yikuan Yan

Open Access Theses

This research focus on experimentally studying the performance of the newly designed Droplet Capable Conductivity Probe (DCCP). ^ A literature review is performed to illustrate the development of current two-fluid model and interfacial area transport equation. Previous conductivity probe instrumentation is also reviewed. The limitations of current conductivity probe design are described and the necessity of developing DCCP is illustrated. ^ The concept of DCCP-2 and DCCP-4 are introduced and experiments are performed to benchmark the capability of DCCP-4.

Paxos Based Directory Updates For Geo-Replicated Cloud Storage, Srivathsava Rangarajan

Open Access Theses

Modern cloud data stores (e.g., Spanner, Cassandra) replicate data across geographically distributed data centers for availability, redundancy and optimized latencies.^ An important class of cloud data stores involves the use of directories to track the location of individual data objects. Directory-based datastores allow flexible data placement, and the ability to adapt placement in response to changing workload dynamics. However, a key challenge is maintaining and updating the directory state when replica placement changes.^ In this thesis, we present the design and implementation of a system to address the problem of correctly updating these directories. Our system is built around JPaxos, …

Big Data Analytics With Nyc Taxicab Data, Xinwu Qian

Open Access Theses

In recent years, the fast development of pervasive computing technologies gives us access to a variety of big data sources, such as mobile phone users, bank note movements and twitter posts etc. It provides unprecedented opportunities to conduct urban studies and contributes to the sustainable and efficient development of large cities. While big data is an invaluable treasure, our knowledge is limited due to lack of appropriate tools to analyze the data. Hence, this thesis is mainly focused on demonstrating how taxicab data can be used to study urban travel patterns and explore useful insights.

The Effects Of Chronic Neural Implantation On Localized Vasculature, Andrew L. Ready

Open Access Theses

Prosthetic solutions currently available range from simple devices intended for aesthetics purposes to complex systems attempting to restore lost function and sensation; of these methods, none show more promise in restoration of normal function and life satisfaction than neural prosthetics. These devices directly interface with the nervous system in order to restore realistic function and feeling to the patient, potentially returning them to how their life once was. While in some cases patients requiring prosthetics can utilize peripheral nerves, those who suffer from injuries or disease which cause damage to the central nervous system can necessitate the usage of devices …