Engineering Commons^™

Bending, Wrinkling, And Folding Of Thin Polymer Film/Elastomer Interfaces, Yuri Ebata

Open Access Dissertations

This work focuses on understanding the buckling deformation mechanisms of bending, wrinkling, and folding that occur on the surfaces and interfaces of polymer systems. We gained fundamental insight into the formation mechanism of these buckled structures for thin glassy films placed on an elastomeric substrate. By taking advantage of geometric confinement, we demonstrated new strategies in controlling wrinkling morphologies. We were able to achieve surfaces with controlled patterned structures which will have a broad impact in optical, adhesive, microelectronics, and microfluidics applications.

Wrinkles and strain localized features, such as delaminations and folds, are observed in many natural systems and are …

Discriminatory Bio-Adhesion Over Nano-Patterned Polymer Brushes, Saugata Gon

Open Access Dissertations

Surfaces functionalized with bio-molecular targeting agents are conventionally used for highly-specific protein and cell adhesion. This thesis explores an alternative approach: Small non-biological adhesive elements are placed on a surface randomly, with the rest of the surface rendered repulsive towards biomolecules and cells. While the adhesive elements themselves, for instance in solution, typically exhibit no selectivity for various compounds within an analyte suspension, selective adhesion of targeted objects or molecules results from their placement on the repulsive surface. The mechanism of selectivity relies on recognition of length scales of the surface distribution of adhesive elements relative to species in the …

Dynamic Modeling Of Synthetic Microbial Consortia To Optimize The Co-Fermentation Of Glucose And Xylose, Timothy Joseph Hanly

Open Access Dissertations

Second-generation biofuels have the potential to replace fossil fuels in the energy economy without negatively impacting the food supply. An effective biocatalyst must be able to convert all sugars found in lignocellulosic hydrolysates to biofuels. Few microbes exist in that have both a wide substrate range and high ethanol yields necessary for this process. Mixed culture biotechnology is a promising alternative to the use of single organisms in the production of fuels from lignocellulosic biomass. These systems mimic natural processes for the degradation of lignocellulose and exploit the native capabilities of each microbe. The segregation of metabolic pathways allows for …

Geochemistry And Inorganic Carbon Transport Of A Glacial Till Drumlin At A Road Salt Facility, Houbao Li

Open Access Dissertations

Investigations were conducted at a salt/premix storage facility lying on top of a glacial drumlin near the coastline in eastern Massachusetts, to characterize salt contaminated groundwater. Groundwater hydrogeochemical variations at different depths were determined based on ten years of monthly or quarterly water quality data from 54 monitoring wells. Groundwater was grouped in three water categories – shallow, middle and deep. Hydrogeochemical characterization indicates that the dominant water types are Na-Cl, Na-Ca-Cl and Ca-HCO3 from the shallow to deep water group. Rock weathering is the dominant hydrogeochemical process for deep water group, whereas salt water percolation and cation exchange control …

Semantically Grounded Learning From Unstructured Demonstrations, Scott D. Niekum

Open Access Dissertations

Robots exhibit flexible behavior largely in proportion to their degree of semantic knowledge about the world. Such knowledge is often meticulously hand-coded for a narrow class of tasks, limiting the scope of possible robot competencies. Thus, the primary limiting factor of robot capabilities is often not the physical attributes of the robot, but the limited time and skill of expert programmers. One way to deal with the vast number of situations and environments that robots face outside the laboratory is to provide users with simple methods for programming robots that do not require the skill of an expert.

For this …

Techniques To Increase Computational Efficiency In Some Deterministic And Random Electromagnetic Propagation Problems, Selman Ozbayat

Open Access Dissertations

Efficient computation in deterministic and uncertain electromagnetic propagation environments, tackled by parabolic equation methods, is the subject of interest of this dissertation. Our work is comprised of two parts. In the first part we determine efficient absorbing boundary conditions for propagation over deterministic terrain and in the second part we study techniques for efficient quantification of random parameters/outputs in volume and surface based electromagnetic problems.

Domain truncation by transparent boundary conditions for open problems where parabolic equation is utilized to govern wave propagation are in general computationally costly. For the deterministic problem, we utilize two approximations to a convolution-in-space type …

Reconfigurable Technologies For Next Generation Internet And Cluster Computing, Deepak C. Unnikrishnan

Open Access Dissertations

Modern web applications are marked by distinct networking and computing characteristics. As applications evolve, they continue to operate over a large monolithic framework of networking and computing equipment built from general-purpose microprocessors and Application Specific Integrated Circuits (ASICs) that offers few architectural choices. This dissertation presents techniques to diversify the next-generation Internet infrastructure by integrating Field-programmable Gate Arrays (FPGAs), a class of reconfigurable integrated circuits, with general-purpose microprocessor-based techniques. Specifically, our solutions are demonstrated in the context of two applications - network virtualization and distributed cluster computing.

Network virtualization enables the physical network infrastructure to be shared among several …

Hybrid Radio Frequency And Video Framework For Identity-Aware Augmented Perception In Disaster Management And Assistive Technologies, Xunyi Yu

Open Access Dissertations

In this dissertation, we introduce a hybrid radio frequency and video framework that enables identity aware-augmented perception. Identity-aware augmented perception enhances users' perception of the surrounding by collecting and analyzing information pertaining to each identifiable or tractable target nearby aggregated from various sensors, and presents it visually or audibly augmenting users' own sensory perceptions. We target two application areas of disaster management and assistive technologies. Incident commanders and first responders can use the technology to perceive information specific to a victim, e.g. triage level, critical conditions, visually superimposed on third person or first person video. The blind and visually impaired …

Tooth Cusp Radius Of Curvature As A Dietary Correlate In Primates, Michael Anthony Berthaume

Open Access Dissertations

Tooth cusp radius of curvature (RoC) has been hypothesized to play an important role in food item breakdown, but has remained largely unstudied due to difficulties in measuring and modeling RoC in multicusped teeth. We tested these hypotheses using a parametric model of a four cusped, maxillary, bunodont molar in conjunction with finite element analysis. When our data failed to support existing hypotheses, we put forth and tested the Complex Cusp Hypothesis which states that, during brittle food items breakdown, an optimally shaped molar would be maximizing stresses in the food item while minimizing stresses in the enamel. After gaining …

Online Management Of Resilient And Power Efficient Multicore Processors, Rance Rodrigues

Open Access Dissertations

The semiconductor industry has been driven by Moore's law for almost half a century. Miniaturization of device size has allowed more transistors to be packed into a smaller area while the improved transistor performance has resulted in a significant increase in frequency. Increased density of devices and rising frequency led, unfortunately, to a power density problem which became an obstacle to further integration. The processor industry responded to this problem by lowering processor frequency and integrating multiple processor cores on a die, choosing to focus on Thread Level Parallelism (TLP) for performance instead of traditional Instruction Level Parallelism (ILP).

While …

Travelers' Route Choice Behavior In Risky Networks, Hengliang Tian

Open Access Dissertations

The accurate modeling of travelers’ route choice decision making when faced with unreliable (risky) travel times is necessary for the assessment of policies aimed at improving travel time reliability. Two major objectives are studied in this thesis. The first objective is to evaluate the applicability of a process model to route choice under risk where the actual process of decision making is captured. Traditionally, we adopt “as-if” econometric models to predict people’s route choice decisions. The second objective is to investigate travelers’ capability to incorporate future real-time traffic information into their current route choice decision making. Two separate stated preference …

Evaluation Of A Split-Root Nutrition System To Optimize Nutrition Of Basil, Ganisher Djurakulovich Abbasov

Open Access Dissertations

The plant-nutrient-water optimum interaction always has been a problematic program for plant growth and development. This work investigates this interaction using a split root nutrition system to determine possible changes in traditional hydroponics to enhance plant growth and development. While split root nutrition systems have been used experimentally to answer some specific questions, the technique has never been used in a production system for optimizing plant, nutrient, and water interaction. The introduction of hydroponics almost a hundred fifty years ago has not changed this situation fundamentally. Moreover, the norm of fertilizer application on agricultural crops has the advantage of increased …

Scaling Reversible Adhesion In Synthetic And Biological Systems, Michael David Bartlett

Open Access Dissertations

Geckos and other insects have fascinated scientists and casual observers with their ability to effortlessly climb up walls and across ceilings. This capability has inspired high capacity, easy release synthetic adhesives, which have focused on mimicking the fibrillar features found on the foot pads of these climbing organisms. However, without a fundamental framework that connects biological and synthetic adhesives from nanoscopic to macroscopic features, synthetic mimics have failed to perform favorably at large contact areas. In this thesis, we present a scaling approach which leads to an understanding of reversible adhesion in both synthetic and biological systems over multiple length …

Computer Simulation Of Viral-Assembly And Translocation, Jyoti Prakash Mahalik

Open Access Dissertations

We investigated four different problems using coarse grained computational models : self-assembly of single stranded (ss) DNA virus, ejection dynamics of double stranded(ds) DNA from phages, translocation of ssDNA through MspA protein pore, and segmental dynamics of a polymer translocating through a synthetic nanopore. In the first part of the project, we investigated the self-assembly of a virus with and without its genome. A coarse-grained model was proposed for the viral subunit proteins and its genome (ssDNA). Langevin dynamics simulation, and replica exchange method were used to determine the kinetics and energetics of the self-assembly process, respectively. The self-assembly follows …

A Hazard-Based Risk Analysis Approach To Understanding Climate Change Impacts To Water Resource Systems: Application To The Upper Great Lakes, Paul Markert Moody

Open Access Dissertations

Water resources systems are designed to operate under a wide range of potential climate conditions. Traditionally, systems have been designed using stationarity-based methods. Stationarity is the assumption that the climate varies within an envelope of variability, implying that future variability will be similar to past variability. Due to anthropogenic climate change, the credibility of the stationarity-based assumptions has been reduced. In response, climate change assessments have been developed to quantify the potential impacts due to climatic change. While these methods quantify potential changes, they lack the probabilistic information that is needed for a risk-based approach to decision-analysis. This dissertation seeks …

Investigation Of Microalgae Cultivation And Anaerobic Codigestion Of Algae And Sewage Sludge For Wastewater Treatment Facilities, Meng Wang

Open Access Dissertations

The main goals of this research are to investigate the anaerobic digestibility of algae and to investigate the effects of growth media on the growth rates, nutrient removal kinetics, and extracellular polymeric substances (EPS) characteristics of wild type green algae. Anaerobic co-digestion of algae with sewage sludge is proposed to improve the digestibility of algae. It is hypothesized that the addition of sewage sludge improves the hydrolysis rate of algae, which is often the rate-limiting step for anaerobic digestion. It is also hypothesized that the composition and concentration of nutrients in growth media will affect the kinetics of nutrient removal …

Development Of Miniature Full Flow And Model Pipeline Probes For Testing Of Box Core Samples Of Surficial Seabed Sediments, Adriane G. Boscardin

Open Access Dissertations

The box corer is a relatively new tool used in the geotechnical community for collection of soft seabed sediments. Miniature full flow and model pipeline probes were developed as tools to characterize and obtain soil parameters of soft seabed sediments collected in the box core for design of offshore pipelines and analysis of shallow debris flows. Probes specifically developed for this study include the miniature t-bar, ball, motorized vane (MV), and toroid. The t-bar, ball, and MV were developed to measure intact and remolded undrained shear strengths (s_u and s_ur). The t-bar and ball can obtain continuous …

Solution Assembly Of Conjugated Polymers, Felicia Bokel

Open Access Dissertations

This dissertation focuses on the solution-state polymer assembly of conjugated polymers with specific attention to nano- and molecular-scale morphology. Understanding how to control these structures holds potential for applications in polymer-based electronics. Optimization of conjugated polymer morphology was performed with three objectives: 1) segregation of donor and acceptor materials on the nanometer length-scale, 2) achieving molecular-scale ordering in terms of crystallinity within distinct domains, and 3) maximizing the number and quality of well-defined donor/acceptor interfaces.

Chapter 1 introduces the development of a mixed solvent method to create crystalline poly(3-hexyl thiophene) (P3HT) fibrils in solution. Chapter 2 describes fibril purification and …

Photo-Reaction Of Copolymers With Pendent Benzophenone, Scott Kenneth Christensen

Open Access Dissertations

This dissertation aims to both deepen and broaden our understanding of copolymers with pendent benzophenone (BP) in relation to both established applications and novel directions in materials science. Photo-reaction of these BP copolymers is explored in attempts to achieve three distinct goals: (1) robust and efficiently photo-crosslinkable solid polymer films, (2) photo-reacted polymer blends with disordered bicontinuous nanostructures, and (3) photo-patterned hydrogel materials with environmental UV stability. We begin by investigating the fundamental gelation behavior of solid polymer films, finding BP copolymers to be particularly effective crosslinkable materials. Gelation efficiency can be tuned according to comonomer chemistry, as BP hydrogen …

Measurement Of The Hydraulic Conductivity Of Gravels Using A Laboratory Permeameter And Silty Sands Using Field Testing With Observation Wells, Aaron Judge

Open Access Dissertations

A new laboratory permeameter was developed for measuring the hydraulic conductivity of gravels ranging from 0.1 to 2 m/s. The release of pneumatic pressure applied to the test specimen induces an underdamped oscillatory response of the water level above the permeameter, similar to an underdamped in situ slug test response in monitoring wells. A closed form model was derived to calibrate the hydraulic minor losses in the permeameter and the hydraulic conductivity of the specimen by performing tests without and with a specimen. The majority of each test series performed on individual specimens produced hydraulic conductivity values within 10% of …

Multiphase Flows With Digital And Traditional Microfluidics, Michael Andrew Nilsson

Open Access Dissertations

Multi-phase fluid systems are an important concept in fluid mechanics, seen every day in how fluids interact with solids, gases, and other fluids in many industrial, medical, agricultural, and other regimes. In this thesis, the development of a two-dimensional digital microfluidic device is presented, followed by the development of a two-phase microfluidic diagnostic tool designed to simulate sandstone geometries in oil reservoirs. In both instances, it is possible to take advantage of the physics involved in multiphase flows to affect positive outcomes in both.

In order to make an effective droplet-based digital microfluidic device, one must be able to precisely …

Effect Of Total Awake Time On Drivers' Performance And Evaluation Of Training Intervention To Mitigate Effects Of Total Awake Time On Drivers' Performance, Abd Malek Abdul Hamid

Open Access Dissertations

Driving while sleepy, drowsy or fatigued are leading contributors to road crashes. Sleepiness, drowsiness and fatigue usually occur at the end of a prolonged period of time during which an individual has been awake. Although these factors have been heavily researched, it is not clear how one of their primary causes, a prolonged total awake time (TAT), might affect driving skills such as hazard anticipation, hazard mitigation and attention maintenance, three skills that are crucial for safe driving.

The first experiment investigated how these three driving skills are affected by prolonged TAT, and if so to what extent. Forty-eight participants …

Particle Behavior On Anisotropically Curved Interfaces, Kathleen Mcennis

Open Access Dissertations

This dissertation presents experimental research investigating the behavior of particles on two different types of anisotropically curved liquid interfaces: cylinders and catenoids. The results are compared to the behavior predicted by theoretical models. Several types of liquids and many types of particles were examined. The size scale of the surfaces ranges from microns to millimeters, with nanometer and micron sized particles.

Semi-cylinders, a few hundred microns in diameter, were made by creating a line of liquid on a surface. Three different fluids were used to create the semi-cylinders: Gallium, ionic liquids, and molten polystyrene (PS). Particle behavior on semi-cylinder liquid …

Effect Of Colloidal Interactions On Formation Of Glasses, Gels, Stable Clusters And Structured Films, Anand Kumar Atmuri

Open Access Dissertations

Colloidal suspensions are ubiquitous because of their vast industrial and household usage. We demonstrate that interactions between colloidal particles play a crucial role in manipulating the phase behavior and thereby the macroscopic properties of a variety of colloidal materials, including structured films, gels, glasses and stable clusters. First, we examined films comprised of two different colloidal particles and investigated the impact of colloidal interactions in manipulating the extent of segregation in the dried films. A transport model was used to predict the volume fraction profiles of the particles as a function of film thickness, which showed that segregation could be …

Mesostructural Characterization And Probabilistic Modeling Of The Design Limit States Of Parallel Strand Lumber, Alireza Amini

Open Access Dissertations

Over recent decades, the public tendency toward using the structural composite lumber (SCL), a common composite of wood made of wood strands or veneers glued and compressed together, as structural members (especially the main load bearing members such as beams and columns) has risen considerably. In contrast to the fast-paced market growth of these products, development is slow. The experimental development is gradual and time-consuming and the computational development is even slower. The objective of this project is to introduce appropriate numerical models for limit state analysis of a certain type of SCL material called PSL.

Parallel strand lumber (PSL), …

Impact Resistant Glassy Polymers: Pre-Stress And Mode Ii Fracture, Jared Steven Archer

Open Access Dissertations

Model glassy polymers, polymethyl methacrylate (PMMA) and polycarbonate (PC) are used to experimentally probe several aspects of polymer fracture. In Chapter 1, the method of pre-stress is employed as a means of improving the fracture properites of brittle PMMA. Samples are tested under equi-biaxial compression, simple shear and a combination of biaxial compression and shear. Equi-biaxial compression is shown to increase the threshold stress level for projectile penetration whereas shear pre-stress has a large effect on the overall energy absorbed during an impact. There is also an apparent interaction observed between compression and shear to dramatically increase the threshold stress. …

Characterization Of Self-Assembled Functional Polymeric Nanostructures: I. Magnetic Nanostructures From Metallopolymers Ii. Zwitterionic Polymer Vesicles In Ionic Liquid, Raghavendra Raj Maddikeri

Open Access Dissertations

Two diverse projects illustrate the application of various materials characterization techniques to investigate the structure and properties of nanostructured functional materials formed in both bulk as well as in solutions. In the first project, ordered magnetic nanostructures were formed within polymer matrix by novel metallopolymers. The novel metal-functionalized block copolymers (BCPs) enabled the confinement of cobalt metal ions within nanostructured BCP domains, which upon simple heat treatment resulted in room temperature ferromagnetic (RTFM) materials. On the contrary, cobalt functionalized homopolymer having similar chemical structure and higher loading of metal-ion are unstructured and exhibited superparamagnetic (SPM) behavior at room temperature. Based …

Particle-Collector Interactions In Nanoscale Heterogeneous Systems, Marina Bendersky

Open Access Dissertations

Particle-surface interactions govern a myriad of interface phenomena, that span from technological applications to naturally occurring biological processes.

In the present work, particle-collector DLVO interactions are computed with the grid-surface integration (GSI) technique, previously applied to the computation of particle colloidal interactions with anionic surfaces patterned with O(10 nm) cationic patches. The applicability of the GSI technique is extended to account for interactions with collectors covered with topographical and chemical nanoscale heterogeneity. Surface roughness is shown to have a significant role in the decrease of the energy barriers, in accordance with experimental deposition rates that are higher than those predicted …

Vehicular Ad Hoc Networks: Interplay Of Geometry, Communications, And Traffic, Mohammad Nekoui

Open Access Dissertations

Vehicular Ad Hoc Networks (VANETs) have been proposed to enhance the safety and efficiency of transportation systems. Such networks hold unique characteristics and fulfill new goals that necessitate their study from a whole new perspective other than what has been the prevailing paradigm for conventional Mobile Ad Hoc Networks (MANETs). The mission of this dissertation is to identify such unique characteristics and propose design strategies for VANETs that target the new system goals.

We argue that the road and obstacle geometry are two important factors that should be appropriately addressed when studying the communications throughput of VANETs. To this end …

Nasics: A `Fabric-Centric' Approach Towards Integrated Nanosystems, Pritish Narayanan

Open Access Dissertations

This dissertation addresses the fundamental problem of how to build computing systems for the nanoscale. With CMOS reaching fundamental limits, emerging nanomaterials such as semiconductor nanowires, carbon nanotubes, graphene etc. have been proposed as promising alternatives. However, nanoelectronics research has largely focused on a `device-first' mindset without adequately addressing system-level capabilities, challenges for integration and scalable assembly.

In this dissertation, we propose to develop an integrated nano-fabric, (broadly defined as nanostructures/devices in conjunction with paradigms for assembly, inter-connection and circuit styles), as opposed to approaches that focus on MOSFET replacement devices as the ultimate goal. In the `fabric-centric' mindset, design …