Engineering Commons^™

Polymerizable Lipids For Controlled Functionalization Of Layered Materials, Kortney Kaye Rupp

Open Access Theses

Self-assembled monolayers (SAM’s) offer a straightforward approach to tailoring the interfacial properties of metals, metal oxides and semiconductors. Noncovalent functionalization of single-layer graphene offers the possibility to finely tune surface chemistry for future applications in electronics. Polymerization of photochemically reactive molecules in a lying-down phase has been used to increase the strength of intermolecular interactions between long alkanes and HOPG substrates. Long-chain fatty acid derivatives with internal diyne groups yield a conjugated ene-yne polymer upon UV irradiation. Diyne lipids with phosphocholine (diyne PC) and phosphoethanolamine (diyne PE) groups offer a charged form of the head group that is robust towards …

Applications Of The Homotopy Analysis Method To Optimal Control Problems, Shubham Singh

Open Access Theses

Traditionally, trajectory optimization for aerospace applications has been performed using either direct or indirect methods. Indirect methods produce highly accurate solutions but suer from a small convergence region, requiring initial guesses close to the optimal solution. In past two decades, a new series of analytical approximation methods have been used for solving systems of dierential equations and boundary value problems.

The Homotopy Analysis Method (HAM) is one such method which has been used to solve typical boundary value problems in nance, science, and engineering. In this investigation, a methodology is created to solve indirect trajectory optimization problems using the Homotopy …

High-Throughput Mechanical Characterization Methods For Composite Electrodes And In-Situ Analysis Of Li-Ion Batteries, Luize Scalco De Vasconcelos

Open Access Theses

Electrodes in commercial rechargeable batteries are microscopically heterogeneous materials. The constituents often have large variation in their mechanical properties, making the characterization process a challenging task. In addition, the mechanical properties and mechanical behaviors of electrodes are closely coupled with the electrochemical processes of lithium insertion and extraction. There is an urgent need to develop an experimental platform to characterize the chemomechanical response of electrodes under the in-situ conditions of charge and discharge.

In the first part of this thesis, instrumented grid indentation is employed to determine the elastic modulus and hardness of the constituent phases of a composite cathode. …

Numerical Methods For Low-Thrust Trajectory Optimization, Robert E. Pritchett

Open Access Theses

The spacecraft trajectory design process frequently includes the optimization of a quantity of importance such as propellant consumption or time of flight. A variety of methods for trajectory optimization are available, however the efficiency of an approach is dependent on the problem scenario it is applied to. Indirect and direct trajectory optimization methods are examined in this investigation with the goal of assessing the characteristics of each approach, and thereby determining the problem scenarios each is best suited for. Insight is gained from application of each optimization method to three sample problems; a circular-to-circular orbit transfer as well as two …

Using Ubiquitous Data To Improve Smartwatches' Context Awareness, Yuankun Song

Open Access Theses

Nowadays, more and more data is being generated by various software applications, services and smart devices every second. The data contains abundant information about people’s daily lives. This research explored the possibility of improving smartwatches’ context awareness by using common ubiquitous data. The researcher developed a prototype system consisting of an Android application and a web application, and conducted an experiment where 10 participants performed several tasks with the help of a smartwatch. The result showed a significant improvement of the smartwatch’s context awareness running the prototype application, which used ubiquitous data to automatically execute proper actions according to contexts. …

Mapping And Analyzing Energy Use And Efficiency In A Modified Hydroponic Shipping Container, Rachel E. Sparks

Open Access Theses

In urban centers today, vertical farming is becoming a popular alternative to conventional agriculture in an effort to increase local food production and improve urban food security by growing crops using hydroponic methods in controlled environment spaces. More specifically, one vertical method involves growing crops inside refurbished shipping containers, or a “farm-in-a-box” concept, which offers a flexible, mobile, and scalable means of year-round food production in a variety of climates. Despite benefits of producing food locally, some of the concerns associated with these vertical farming systems include high energy consumption from climate control and electric lighting systems as well as …

Test Cell Set-Up To Enable Drive-Cycle Testing Of A Variable Valve Actuation Enabled Camless Diesel Engine, Alexander Harrison Taylor

Open Access Theses

The previous facility which was used for engine testing at Purdue's Ray W. Herrick Laboratories utilized an eddy current dynamometer which is only suited for steady-state testing and throttle snaps. To better utilize a pre-existing camless diesel engine, which is is enabled via variable valve actuation, it was desired to perform transient drive-cycle tests. To accomplish this goal, a variable frequency drive AC dynamometer was required. Given that a brand new facility was constructed, the team was presented with an opportunity for ground up design of a test cell.

The new test cell's operation was proved out using a cammed …

Novel Gain Enhancement Technique For Microstrip Patch Antennas Based On Multi-Pronged Feed Network Synthesis, Brian J. Vaughn

Open Access Theses

Developing antennas with enhanced gain has always been an important pursuit within the antenna community, as a higher gain leads to an increase in the received power for any given wireless link. In general, when a higher gain is needed for an application, only certain types of antennas can be used. The goal of this thesis project was to develop a method for increasing the gain of antennas that already exist by applying modifications to them, expanding the design flexibility for wireless applications. In this thesis, a novel method for increasing the gain of microstrip patch antennas by synthesizing specialized …

Fast Voxel Line Update For Time-Space Image Reconstruction, Xiao Wang

Open Access Theses

Recent applications of model-based iterative reconstruction(MBIR) algorithm to time-space Computed Tomography (CT) have shown that MBIR can greatly improve image quality by increasing resolution as well as reducing noise and some artifacts. Among the various iterative methods that have been studied for MBIR, iterative coordinate descent(ICD) has been found to have relatively low overall computational requirements due to its fast convergence. However, high computational cost and long reconstruction times remain as a barrier to the use of MBIR in practical applications. This disadvantage is especially prominent in time-space reconstruction because of the large volume of data. This thesis presents a …

Command Shaping With Constrained Peak Input Acceleration To Minimize Residual Vibration In A Flexible-Joint Robot, Yumeng Wu

Open Access Theses

Rapid point-to-point motion is limited when flexibilities exist in the system. In order to minimize the vibrations related to joint flexibilities, much work has been done, including modifying the system so that vibrations can be damped out more quickly, calculating the inverse dynamics of the system and constructing shaped input profiles that avoid system natural frequencies. In this work, the earlier fixed-time command shaping method has been extended to a peak-acceleration-constrained approach with two basis functions, the ramped sinusoid function and the versine function, such that the maximum acceleration is guaranteed without overconstraining the input profiles. The approach is developed …

Vhf Lumped-Element Reconfigurable Filters Design And Applications In Field-Programmable Filter Array, Wei Yang

Open Access Theses

The increasing demand for limited space in crowded frequency spectrum is creating new challenges to RF frontend communication systems. High gain tunable antennas, tunable filter with high selectivity and isolation, large signal-to-noise ratio tunable low noise amplifiers are demanded. This thesis demonstrates novel tunable filter synthesis that may help in developing solutions for future RF frontend filter applications. The proposed coupling scheme enable the tuning of center frequency, order, response shape, bandwidth, and transmission zero spectral location. Also, this coupling scheme can be used to implement a field-programmable filter arrays (FPFAs) design.

Experimental Characterization Of Scroll Expander For Small-Scale Power Generation In An Organic Rankine Cycle, Felipe Airoldi Accorsi

Open Access Theses

Organic Rankine Cycles (ORC) are thermodynamic power cycles designed to generate work from low temperature sources. The low temperature heat input, typically between 80 °C to 270 °C, allows them to recover energy from industrial waste heat, exhaust gas from diesel, engines, solar systems, geothermal systems, and others. This technology already is commercialized in large-to-medium-scale power plants; however, it is still in development for small-to-micro scale.

The operating principle of ORC comprises four major steps. First, the working fluid evaporates at high pressure using the heat transfer from the low temperature heat source. Then, the working fluid reduces its enthalpy …

Algorithms For Lidar Based Traffic Tracking: Development And Demonstration, Vamsi K. Bandaru

Open Access Theses

The current state of the art of traffic tracking is based on the use of video, and requires extensive manual intervention for it to work, including hours of painstaking human examination of videos frame by frame which also make the acquisition of data extremely expensive. Fundamentally, this is because we do not have observability of the actual scene from a camera which captures a 2D projection of the 3D world. Even if video were to be automated, it would involve such algorithms as RANSACK for outlier elimination while matching features across frames or across multiple cameras. This results in algorithms …

Enhancing Silymarin Fractionation Via Molecular Modeling Using The Conductor-Like Screening Model For Real Solvents, Emma C. Brace

Open Access Theses

The market for bio-based products from plant sources is on the rise. There is a global challenge to implement environmentally clean practices for the production of fuels and pharmaceuticals from sustainable resources. A significant hurdle for discovery of comparable plant-derived products is the extensive volume of trial-and-error experimentation required. To alleviate the experimental burden, a quantum mechanics based molecular modeling approach known as the COnductor-like Screening Model for Real Solvents (COSMO-RS) was used to predict the best biphasic solvent system to purify silymarins from an aqueous mixture. Silymarins are a class of flavonolignans present in milk thistle ( Silybum marianum …

Efficient Inelastic Scattering In Atomistic Tight Binding, James A. Charles

Open Access Theses

In this thesis, the coherent and incoherent transport simulation capabilities of the multipurpose nanodevice simulation tool NEMO5 are presented and applied on transport in tunneling field-effect transistors (TFET). A gentle introduction is given to the non-equilibrium Green's function theory. The comparison with experimental resistivity data confirms the validity of the electron-phonon scattering models. Common pitfalls of numerical implementations such as current conservation, energy mesh resolution, and recursive Green's function stability and the applicability of common approximations of scattering self-energies are discussed. The impact of phonon-assisted tunneling on the performance of TFETs is exemplified with a concrete Si nanowire device. The …

Stochastic Modeling And Dem Simulation Of Granular Media Subsidence Due To Underground Activity, Rodrigo Borela Valente

Open Access Theses

Many communities around the world have been established in areas of ongoing, as well as ceased, underground mining activity. Ground movements induced by ore extraction methods and the collapse of abandoned cavities have long been recognized as a hazard to surface structures. A number of approaches have been proposed for the prediction of subsidence in underground mining regions, and their integration to Geographic Information Systems (GIS) can produce a powerful risk management tool. Nevertheless, this application is often limited by either a lack of generality or excessive computational cost of the methods available.

In this work, the stochastic subsidence model …

Fleet Level Environmental Evaluation Of Emission Taxing Scheme And Biofuel: A Combined Optimization And Multi-Actor Approach, Hsun Chao

Open Access Theses

The Fleet Level Environmental Evaluation Tool (FLEET) can assess environmental impacts of various levels of technology and environmental policies on fleet-level carbon emissions and airline operations. FLEET consists of different models to mimic airlines' behaviors and a resource allocation problem to simulate airlines' aircraft deployments on their networks. Additionally, the Multiactors Biofuel Model can conduct biofuel life-cycle assessments and evaluate biofuel developments and assess the effects of new technology on biofuel production costs and unit carbon emissions as well.

In addition, the European Union (EU) initiated an Emission Trading Scheme (ETS) in the European Economic Area, while International Civil Aviation …

Additive Manufacturing Of Carbon Fiber-Reinforced Thermoplastic Composites, Nicholas M. Denardo

Open Access Theses

Additive manufacturing, or 3D printing, encompasses manufacturing processes that construct a geometry by depositing or solidifying material only where it is needed in the absence of a mold. The ability to manufacture complex geometries on demand directly from a digital file, as well as the decreasing equipment costs due to increased competition in the market, have resulted in the AM industry experiencing rapid growth in the past decade. Many companies have emerged with novel technologies well suited to improve products and/or save costs in various industries.

Until recently, the applications of polymer additive manufacturing have been mainly limited to prototyping. …

An Led-Based Image Sensor With Energy Harvesting And Projection Capabilities College Of Technology, Xiaozhe Fan

Open Access Theses

The light emitting diode (LED) technology has experienced great improvements in efficiency and cost reduction since the first visible light LED was invented in 1962. At the same time, because LEDs exhibit excellent photovoltaic performance, their capabilities of sensing light and harvesting energy have also been explored and studied for many years. By triple functionality of LEDs, they are widely used in a variety of research areas including visible light communication, robotics, structured light application and so on. Meanwhile, this triple functionality of LEDs also inspired researchers to combine and implement different functions in one system.

In this thesis, An …

Design And Analysis Of A High Performance Valve, Jordan M. Garrity

Open Access Theses

Most valves available in the fluid power industry today are capable of achieving either a large flow rate or a quick response time; however, often they are unable to deliver both simultaneously. Commercially available valves that can produce both at the same time require complex geometries with multiple actuation stages and piloting pressures, making them expensive components. To establish their active usage in applications across the fluid power industry, a reduction in price for these components is paramount. The Energy Coupling Actuated Valve (ECAV) is capable of solving the large flow rates with fast actuation speeds trade-off by utilizing a …

Modelling And Control Of A Parallel Through-The-Road Plug-In Hybrid Vehicle, Rohinish Gupta

Open Access Theses

With an increasing number of passenger vehicles, automotive emissions has become a major challenge. Among other pollutants, green house gas (GHG) emissions form a majority of the exhaust coming out of the tail-pipe and are blamed for the rising temperature of the earth. The net carbon emissions due to running a lightduty passenger vehicle are studied in the present thesis. Hybrid electric vehicles have been proven to have lower green house gas emissions than conventional vehicles as electricity is cleaner than fossil fuels.

Using a parallel-through-the-road hybrid architecture vehicle, different power management strategies are studied. To begin with, a detailed …

Service-Level Based Response By Assignment And Order Processing For Warehouse Automation, Zijian He

Open Access Theses

Along with tremendous growth of online sales in this Internet era, unprecedented intensive competition in shortening the delivery time of orders has been occurring among several major online retailers. On the other hand, the idea of customer-oriented service creates a trend of diversified pricing strategy. Different price options are offered to cater to diversified needs of customers. It has become an urgent need for online sales industries to provide the differentiated service levels for different classes of customers with different priorities based on the charging prices and resource constraints of the supply network.

In response to the challenges mentioned above, …

Monitoring Dbms Activity To Detect Insider Threat Using Query Selectivity, Prajwal B. Hegde

Open Access Theses

The objective of the research presented in this thesis is to evaluate the importance of query selectivity for monitoring DBMS activity and detect insider threat. We propose query selectivity as an additional component to an existing anomaly detection system (ADS). We first look at the advantages of working with this particular ADS. This is followed by a discussion about some existing limitations in the anomaly detection system (ADS) and how it affects its overall performance. We look at what query selectivity is and how it can help improve upon the existing limitations of the ADS. The system is then implemented …

A Novel Mode-Switching Hydraulic Hybrid For An On-Highway Vehicle: A Study Of Architecture And Control, Hiral Jayantilal Haria

Open Access Theses

Increasing demand for fossil fuels, their limited reserves and the environmental effects resulting from the transportation sector has raised severe concerns to government agencies, transportation industry as well as the end-users. This has raised interests in improving the fuel economy of road vehicles. One of the promising technologies in this regard is hybridization of vehicle transmission. Hydraulic hybrids have progressively gained acceptance due to their high power density and low component costs relative to their electric counterpart.

Many different hydraulic hybrid architectures have been developed to achieve better power management and regenerative braking and have been tested for performance and …

Ab Initio Based State Specific Modeling Of N2+O System, Han Luo

Open Access Theses

Nitrogen and atomic oxygen play an important role in high temperature gas systems. Their Zeldovich reaction product nitric oxide not only affects aerothermal loads and emissions of hypersonic vehicles, but also has the possibility to influence the efficiency of hypersonic propulsion. Atomic oxygen induced nitrogen dissociation is another reaction mechanism of the N2+O system. However, due to the difficulty of conducting ground tests, there are no experimental data for this reaction now. Thermo-chemical nonequilibrium could make the problem more difficult since experiments could only track macroscopic gas properties instead of internal energy distribution. On the other hand, current reaction and …

The Effect Of Static And Dynamic Aging On Fatigue Behavior Of Sn3.0ag0.5cu Solder Alloy, Yiran Li

Open Access Theses

In microelectronic assemblies, solder joints serve as interconnection between different packaging levels and are an important cause for the failure of microelectronic products. Sn-Ag-Cu solder alloys became important after lead-based solder alloys were caused to be discarded by regulations in European Union and Japan. However, the constitutive behavior of Sn-Ag-Cu alloys is not as well understood as lead-based solder alloys, and many studies confirm the aging of these alloys with time. The aging of Sn-Ag-Cu alloys and its effect on mechanical behavior challenges the reliability prediction of microelectronic assemblies. In this study, the effect of pretest isothermal aging and in-test …

Analysis Of Structural And Functional Brain Networks, Jun Young Jeong

Open Access Theses

The brain is a representative example of a network. It consists of numerous spatially distributed regions that continuously exchange information through structural connections. In the past decade, an increasing number of studies have explored the brain network in both structural and functional aspects; they have begun to decipher complex brain wirings, as well as elucidate how the rich functionality emerges from this architecture. Based upon previous studies, this thesis addresses three critical gaps in the field. (I) Although it is known that the community structures of brain network are spatially overlapping, conventional studies have focused on grouping brain regions into …

Parametric And Design Analysis On Thermoelectric Generators, Shouyuan Huang

Open Access Theses

In facing the limited energy source reserves and environmental problems, thermoelectric generators (TEGs) are one of the promising waste heat recovery systems. The modern TEGs for exhaust stream (e.g. from automobiles) can improve the fuel economy by around 5%, taking advantage of the recent developed thermoelectric (TE) materials.

In this work, we aimed at designing a TEG as an add-on module for a gas-phase heat exchanger with maximized power output, and without negative impact (e.g. maintaining a minimum heat dissipation rate from the hot side). We first developed a parametric optimization algorithm using response surface method (RSM) and genetic algorithm …

Influence Of Stormwater Control Measures On Watershed Hydrology And Biogeochemical Cycling, Colin D. Bell

Open Access Dissertations

Urban development replaces vegetation with impervious surfaces and natural drainage channels with pipe networks that quicken flow paths and alter hydrologic regimes. Additionally, the import of food, application of fertilizer to lawns and gardens, and heightened atmospheric deposition increases nutrient availability in urban landscapes. These excess nutrients are ultimately routed to streams through the pipe networks before it can be processed by the vegetation and microorganisms of the landscape. This combination of physical and chemical disturbances impacts stream ecosystems and degrades their ability to perform valuable services such as removal of nutrients, degradation of pollutants, and provision of recreational and …

Investigation Of Digital Pump/Motor Control Strategies, Farid El Breidi

Open Access Dissertations

A pump is the heart of fluid power systems, it has a significant impact on the efficiency of many fluid power systems. Motors are the most common rotary actuators in fluid power systems. State-of-the-art pump/motor units can achieve efficiencies higher than 90% when operating at maximum displacement; however, as the displacement drops, the efficiency of these units drops to below 50%. A new digital pump/motor design aims at increasing these efficiencies by utilizing two electrically controlled high speed on/off valves per displacement chamber; these valves provide the ability to achieve variable displacement and allow freedom in choosing operating strategies. Such …