Digital Commons Network^™

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. …

Hardware Accelerated Authentication System For Dynamic Time-Critical Networks, Ankush Singla

Open Access Theses

The secure and efficient operation of time-critical networks, such as vehicular networks, smart-grid and other smart-infrastructures, is of primary importance in today’s society. It is crucial to minimize the impact of security mechanisms over such networks so that the safe and reliable operations of time-critical systems are not being interfered.

Even though there are several security mechanisms, their application to smart-infrastructure and Internet of Things (IoT) deployments may not meet the ubiquitous and time-sensitive needs of these systems. That is, existing security mechanisms either introduce a significant computation and communication overhead, or they are not scalable for a large number …

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. …

Metal-Promoted Self-Assembly Of Collagen Mimetic Peptides Into Biofunctional Scaffolds For Stem Cell Delivery With The Aim Of Tissue Regeneration, Kevin Strauss

Open Access Theses

Collagen is a strong, sturdy, but malleable, protein found abundantly in the extracellular matrix. Consequently, it has become an invaluable biomaterial for use in regenerative medicine. However, natural collagen poses difficulties when it comes to customization and structural control, as well as the risk of infectious prions from animal sources. Our approach utilizes shorter, synthetic collagen mimetic peptide sequences. These peptides retain the incredible triple helical stability of natural collagen but can be modified with versatile metal-binding ligands. In the presence of an appropriate metal ion, the peptides self-assemble into diverse, three-dimensional morphologies. The peptide NCoH, functionalized with N-terminal NTA …

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 …

Nutrient Runoff And Leachate After Land-Application Of Digestate In A Laboratory Study Using Rainfall Simulations, Min Xiao

Open Access Theses

There has been an increasing number of anaerobic digesters on livestock farms in the United States during the past two decades. Anaerobic digestion of manure allows production of renewable energy and generation of stabilized and nutrient-rich digestate that can be used as organic fertilizer. However, the majority of the existed studies using liquid digestate as fertilizer only focused on the effectiveness for crop yield, nutrient content and microorganism in soil. There is insufficient understanding in the environmental impact of digestate land-application. This laboratory study used six treatments including four different liquid digestate treatments, a chemical fertilizer treatment, and an unfertilized …

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 …

A Dose Distribution Study Of Uranyl Nitrate In Zebrafish Using Liquid Scintillation And Passivated Implanted Planar Silicon Detectors, Lee A. Alleman

Open Access Theses

Standard curves for a Perkin Elmer TriCarb 2800 liquid scintillation detector (LSC) and a Ludlum 3030p Passivated Implanted Planar Silicon detector have been developed and utilized for studying the dose distribution of depleted uranium (DU) within zebrafish. The DU source was crystallized uranyl nitrate (N2O8U•6H2O) solution, normally used for staining in electron microscopy with a manufactured average specific activity of 0.3 uCi/g. Zebrafish, both larvae and adults, were exposed to three different mass concentrations, dissected, dissolved and counted using an LSC. The counts were compared to the standard curve correlating the measured activity to that of the mass absorbed. It …

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 …

Students' Reasoning With Haptic Technologies: A Qualitative Study In The Electromagnetism Domain, Sadhana Balachandran

Open Access Theses

With abundant applications in the medical training and entertainment industry, haptic technology is slowly making its way into the realm of science education, particularly in conveying abstract and non-visible concepts. Electric field is one such abstract concept. Past studies have shown that learning concepts such as electric fields in a traditional classroom can be quite challenging since students have a hard time visualizing the phenomena and applying its effects to reason. Furthermore, these concepts are the building blocks for more complex concepts such as matter and molecular interactions. Visuo-haptic devices provide a great platform to enable students to visualize and …

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 …

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 …

Beyond The Gender Gap: Understanding Women's Participation In Wikipedia, Danielle J. Corple

Open Access Theses

In 2010, UNU-MERIT researchers surveyed editors of Wikipedia, “the online encyclopedia that anyone can edit” (Glott, Ghosh, & Schmidt, 2010). When the report revealed that almost 90% of the editors were male, however, it suggested that perhaps not everyone “can edit” Wikipedia—especially women. As the resulting media and academic explanations of the Wikipedia “gender gap” have largely attributed the gap to ‘female lack’—lack of initiative, confidence, or technical skills—very little research has explored the treatment of women within Wikipedia culture. Thus, this paper first draws upon feminist technology scholars to problematize current explanations of the gender gap that frame …

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 …

Detection Of Communication Over Dnssec Covert Channels, Nicole M. Hands

Open Access Theses

Unauthorized data removal and modification from information systems represents a major and formidable threat in modern computing. Security researchers are engaged in a constant and escalating battle with the writers of malware and other methods of network intrusion to detect and mitigate this threat. Advanced malware behaviors include encryption of communications between the server and infected client machines as well as various strategies for resilience and obfuscation of infrastructure. These techniques evolve to use any and all available mechanisms. As the Internet has grown, DNS has been expanded and has been given security updates. This study analyzed the potential uses …

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 …

An Anomaly-Based Intrusion Detection System Based On Artificial Immune System (Ais) Techniques, Harish Valayapalayam Kumaravel

Open Access Theses

Two of the major approaches to intrusion detection are anomaly-based detection and signature-based detection. Anomaly-based approaches have the potential for detecting zero-day and other new forms of attacks. Despite this capability, anomaly-based approaches are comparatively less widely used when compared to signature-based detection approaches. Higher computational overhead, higher false positive rates, and lower detection rates are the major reasons for the same. This research has tried to mitigate this problem by using techniques from an area called the Artificial Immune Systems (AIS). AIS is a collusion of immunology, computer science and engineering and tries to apply a number of techniques …

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 …

Oscillation Of Quenched Slowdown Asymptotics Of Random Walks In Random Environment In Z, Sung Won Ahn

Open Access Dissertations

We consider a one dimensional random walk in a random environment (RWRE) with a positive speed limn→∞ (Xn/) = υα > 0. Gantert and Zeitouni showed that if the environment has both positive and negative local drifts then the quenched slowdown probabilities P ω(Xn < xn) with x∈ (0,υα) decay approximately like exp{- n1-1/s} for a deterministic s > 1. More precisely, they showed that n -γ log Pω(Xn < xn) converges to 0 or -∞ depending on whether γ > 1 - 1/s or γ < 1 - 1/ s. In this paper, …

A Study Of Security Issues Of Mobile Apps In The Android Platform Using Machine Learning Approaches, Lei Cen

Open Access Dissertations

Mobile app poses both traditional and new potential threats to system security and user privacy. There are malicious apps that may do harm to the system, and there are mis-behaviors of apps, which are reasonable and legal when not abused, yet may lead to real threats otherwise. Moreover, due to the nature of mobile apps, a running app in mobile devices may be only part of the software, and the server side behavior is usually not covered by analysis. Therefore, direct analysis on the app itself may be incomplete and additional sources of information are needed. In this dissertation, we …

Essays On Health Insurance, Amanda C. Cook

Open Access Dissertations

Uninsured individuals receive fewer health care services for at least three reasons: higher prices, responsibility for the entire bill, and potential provider reductions for concern of non-payment. This study isolates differences in service levels between insured and uninsured individuals that are attributed to different effective prices; the uninsured pay the bill without a contribution from an insurance company. I capitalize on Maryland's highly regulated health care system, where prices are set by the state, are uniform across all patients, and hospitals are compensated for free care and bad debt, to isolate the difference in quantity demanded by the uninsured. While …