Engineering Commons^™

Buckling Of Thin Cylindrical Shells: Imperfection Sensitivity, Non-Destructive Technique For Capacity Prediction And Application For Wind Turbine Towers, Kshitij Kumar Yadav

Doctoral Dissertations

The presence of imperfections significantly reduces the load-carrying capacity of thin cylindrical shells and the reduction depends on the shape and the size of the imperfections. As a result, the prediction of the shells' buckling capacity requires a priori knowledge about the imperfections---a difficult, expansive, and time-consuming adventure, if not impossible. Consequently, thin cylindrical shells are designed conservatively using the knockdown factor approach that accommodates the uncertainties associated with the imperfections present in the cylinders; almost all the design codes follow this approach explicitly or implicitly. However, cylindrical shells can be designed more efficiently by making them insensitive to imperfections ...

Optimization And Technology-Based Strategies To Improve Public Transit Performance Accounting For Demand Distribution, Charalampos Sipetas

Doctoral Dissertations

Public transit is important to societies worldwide. The operation of public transit systems is generally associated with great benefits for the users, but there are also cases in which these systems demonstrate inefficient performance. Quantifying transit performance is an important area of research over the last decades. This dissertation presents models to improve transit system performance through optimization techniques and new technologies, recognizing the effects of non-uniform distribution of demand over space and time. The contributions span fixed route transit services and on-demand transit, as well as models for flexible transit operations that lie in between.

Regarding fixed route systems ...

A Generalized Method For Predictive Simulation-Based Lower Limb Prosthesis Design, Mark Price

Doctoral Dissertations

Lower limb prostheses are designed to replace the functions and form of the missing biological anatomy. These functions are hypothesized to improve user outcome measures which are negatively affected by receiving an amputation – such as metabolic cost of transport, preferred walking speed, and perceived discomfort during walking. However, the effect of these design functions on the targeted outcome measures is highly variable, suggesting that these relationships are not fully understood. Biomechanics simulation and modeling tools are increasingly capable of analyzing the effects of a design on the resulting user gait. In this work, prothesis-aided gait is optimized in simulation to ...

Electrospinning Fibers Via Complex Coacervation, Xiangxi Meng

Doctoral Dissertations

Electrospun fibers are high-surface-area materials widely used in applications ranging from batteries to wound dressings. Typically, an electrospinning precursor solution is prepared by dissolving a high-molecular-weight polymer in an organic solvent to form a sufficiently entangled solution. Our approach bypasses the requirement for entanglements and completely avoids toxic chemicals by focusing on using an aqueous complex coacervates solution. Coacervates are a dense, polymer-rich liquid phase resulting from the associative electrostatic complexation of oppositely charged macroions.

We were the first to demonstrate that liquid complex coacervates could be successfully electrospun into polyelectrolyte complex (PEC) fibers. A canonical coacervate system was formed ...

Cold-Formed Steel Stud Assemblies Bearing On Concrete Slabs, Abbas Joorabchian

Doctoral Dissertations

Cold-formed steel (CFS) bearing walls are frequently installed on concrete slabs, which do not provide perfectly rigid and uniform bearing conditions. Existing design guidance assumes bearing conditions have no impact on the axial capacity, though cold-formed steel compressive members are particularly susceptible to end conditions. Studs are typically installed at the edge of concrete slabs, which is prone to spalling and geometric irregularities. Moreover, they are occasionally installed inadvertently overhanging from concrete slabs. In this research project, the impact of non-uniform and partial bearing conditions on the axial strength of cold-formed steel wall assemblies is identified and characterized experimentally and ...

Enabling Iot Authentication, Privacy And Security Via Blockchain, Md Nazmul Islam

Doctoral Dissertations

Although low-power and Internet-connected gadgets and sensors are increasingly integrated into our lives, the optimal design of these systems remains an issue. In particular, authentication, privacy, security, and performance are critical success factors. Furthermore, with emerging research areas such as autonomous cars, advanced manufacturing, smart cities, and building, usage of the Internet of Things (IoT) devices is expected to skyrocket. A single compromised node can be turned into a malicious one that brings down whole systems or causes disasters in safety-critical applications. This dissertation addresses the critical problems of (i) device management, (ii) data management, and (iii) service management in ...

Correcting For Terrain Interference, Attenuation, And System Bias For A Dual Polarimetric, X-Band Radar, Casey Wolsieffer

Masters Theses

This thesis outlines the procedure and theory used to calibrate the UMass eXperimental X-band Radar (UMAXX) for the purpose of monitoring meteorological events in the Pioneer Valley region. Due to the complex topography of the area, lower tilt angles are subject to partial or full beam blockage as well as ground clutter observed through the main beam or sidelobes. Additionally, there are biases internal and external to the system that impact the reflectivity and differential reflectivity measurements. These biases and corrections are addressed in this work. As the radar has been operational since September of 2018, there is ample data ...

Ground Source Heat Pumps: Considerations For Large Facilities In Massachusetts, Eric Wagner

Masters Theses

There has been a significant increase in the interest and implementations of heat pump systems for HVAC purposes in general and of ground source heat pumps (GSHPs) in particular. Though these systems have existed for decades, primarily in Europe, there has been an upward trend particularly in the United States in recent years. With the world-wide push toward CO₂ emissions reduction targets, interest in heat pump systems to reduce CO₂ emissions from heating and cooling is likely to only increase in the future. However, more than ever, financial considerations are also key factors in the implementation of any ...

Mechanical Design And Analysis: High-Precision Microcontact Printhead For Roll-To-Roll Printing Of Flexible Electronics, Mehdi Riza

Masters Theses

Flexible electronics have demonstrated potential in a wide range of applications including wearable sensors, photovoltaics, medical devices and more, due to their properties of extreme adaptability while also being lightweight and highly robust. The main challenge standing in the way of progress in this field is the difficulty of large-scale manufacturing of these flexible electronics compared to their rigid counterparts. Microcontact printing is a form of soft lithography in which an elastomeric stamp is used to transfer sub-micron scale surface patterns onto a flexible substrate via ink monolayers. The integration of microcontact printing into a roll-to-roll (R2R) system will enable ...

Utilizing Unmanned Aerial Vehicles (Uavs) For The Estimation Of Beam Corrosion Of Steel Bridge Girders, Gabrielle Pryor

Masters Theses

The transportation infrastructure in the United States is a complex system that is vital to the everyday operations of the country. Bridges are a significant asset of this network, with many of them approaching the end of their service life. Corrosion is a common cause of deterioration which ultimately results to structural deficiency for the aging bridges. The deterioration rate is a multi-aspect factor that makes bridge inspections crucial. However, the current bridge inspections are very costly and potentially unsafe for the involved personnel. To lower costs and increase safety, many state DOT’s and universities have decided to perform ...

Rain Rain Flush Away: Evaluating Rainwater Catchment First Flush Volumes, David A. Reckhow, Emily Kumpel

Environmental & Water Resources Engineering Masters Projects

Rainwater harvesting systems often include quality control systems such as a diverted first flush volume to improve the collected water quality. The first flush volume has traditionally been defined as a set volume of rain based on the first 1-2 millimeters of rain that falls on a roof. Diverting a volume of water can be seen as a waste when rainwater is a main source of potable water, sometimes leading to lack of implementation, and thus contaminating the final collected water. Understanding the variability of first flush volume required due to environmental parameters can be used to develop an optimized ...

Flipping The Feedback: Formative Assessment In A Flipped Freshman Circuits Class, Donna H. Ziegenfuss, Cynthia M. Furse

Practical Assessment, Research, and Evaluation

This paper describes the application of formative assessment methods in a flipped freshman engineering circuits course. This student-centered approach provided value for the instructor seeking to improve the learning environment and content in real-time, and for the students who actively participated in the process of course improvement. Three types of assessment were used in this course: online formative course feedback every three weeks; weekly ‘muddiest point’ content feedback; and midterm exam scores. Data were assessed using a mixed-methods approach. The formative feedback from this course provided information on how students perceived the flipped classroom and how those perceptions changed across ...

Vowel Harmony Viewed As Error-Correcting Code, Yvo Meeres, Tommi A. Pirinen

Proceedings of the Society for Computation in Linguistics

Robustness reduces the risk of information loss. At present the notion of error-correcting codes (ECCs) is used to achieve robustness in technical fields only. Viewing fault-tolerant natural systems as systems equipped with error-correcting codes permits a formal comparison of natural and technical robustness.

Instancing natural language (NL), we show differences in technical and natural error-correcting approaches. By picking a specific grammar phenomenon which some NLs exhibit – vowel harmony (VH) – we show that (1) VH can be formalized as an ECC as well as (2) VH adds to the robustness of its NL. We provide empirical as well as formal evidence ...

Transportation Sustainability, Eleni Christofa

Sustainability Education Resources

An overview of sustainable transportation planning practices and management strategies and policies; current transportation trends; environmental and energy policies; nonmotorized modes (mainly bicycles and pedestrians); public transportation; life-cycle assessment for transportation infrastructure; alternative fuel vehicles; vehicle emission estimation models; demand management strategies (including parking policies, pricing strategies).

Control Effect Of Peracetic Acid On Chlorinated Dbp Formation And The Application Of Paa Pre-Oxidation In Drinking Water Treatment, Yue Sun

Environmental & Water Resources Engineering Masters Projects

Chlorine has been applied as the main disinfectant in US drinking water treatment for a century. Chlorination is low cost and effective, yet there are problems with this technology, including disagreeable taste of treated drinking water and formation of toxic and potentially carcinogenic disinfection byproducts (DBPs). Alternative disinfection methods including ozone, ferrate and UV light have been studied. They are not widely applied in drinking water treatment because of problems such as the costly generation process or no residual in the system.

Peracetic acid, an easy-to-use and economic friendly oxidant, has been applied as an alternative disinfectant to chlorine in ...

Construction And Materials Best Practice For Concrete Sidewalks, Sergio F. Brena, Kara Peterman, Rhyan Sullivan

Structural Engineering and Mechanics Research Reports

This report summarizes an 18-month effort to investigate best practices to incorporate into the materials and construction of concrete sidewalks to mitigate surface scaling damage induced by freeze-thaw cycles in the presence of deicing chemicals. The study involved an in-situ experimental study accompanied by laboratory testing and quantitative analyses to determine key factors that impact sidewalk performance and durability. The primary variables considered in the study were concrete mixture design (aggregate/paste optimization, air content, and cementitious material replacements), workmanship (delivery, placement, finishing, curing), and deicing treatment. The collective effort involved participants from construction companies, a concrete producer, academia, testing ...

Fabrication Of Binder-Free Electrodes Based On Graphene Oxide With Cnt For Decrease Of Resistance, Di Zhang

Masters Theses

In electrode double layer capacitor (EDLC), electrodes usually contain binder materials to provide adhesion between electrode materials. However, binder materials usually bring unwanted resistances to the component due to their non-conductivity properties and the occupation of ion cavities. The purpose of this thesis is to demonstrate the feasibility of fabricating electrodes for EDLCs by using carbon nanotubes (CNTs) and graphene oxide (GO) without using any binding materials. At the same time, investigating the binder-free electrode’s electrochemical properties and make an assumption of its potential application in the future.

The slurry of binder-free electrodes was fabricated by ultrasonicating water suspended ...

Real-Time Tddft-Based Filtered Spectroscopy, Ivan Williams

Masters Theses

We demonstrate the ability to simulate targeted excitation of atomistic systems using our real-time TDDFT-based simulation framework NESSIE. Traditional ap- proaches for extracting spectra through real-time TDDFT involves excitation of all frequencies via impulse requiring long simulation times and yielding poor resolution. By exciting the system with a modulated sinc pulse between the frequencies of inter- est we are able to obtain a spectral response with far more precision in a significantly shorter time frame than competing implementations.

Optimal Mammography Schedule Estimates Under Varying Disease Burden, Infrastructure Availability, And Other Cause Mortality: A Comparative Analyses Of Six Low- And Middle- Income Countries, Shifali Shifali

Masters Theses

Low-and-middle-income countries (LMICs) have a higher mortality-to-incidence ratio for breast cancer compared to high-income countries (HICs) because of late-stage diagnosis. Mammography screening is recommended for early diagnosis, however, current screening guidelines are only generalized by economic disparities, and are based on extrapolation of data from randomized controlled trials in HICs, which have different disease burdens and all-cause mortality compared to LMICs. Moreover, the infrastructure capacity in LMICs is far below that needed for adopting current screening guidelines. This study analyzes the impact of disease burden, infrastructure availability, and other cause mortality on optimal mammography screening schedules for LMICs. Further, these ...

Network Virtualization And Emulation Using Docker, Openvswitch And Mininet-Based Link Emulation, Narendra Prabhu

Masters Theses

With the advent of virtualization and artificial intelligence, research on networked systems has progressed substantially. As the technology progresses, we expect a boom in not only the systems research but also in the network of systems domain. It is paramount that we understand and develop methodologies to connect and communicate among the plethora of devices and systems that exist today. One such area is mobile ad-hoc and space communication, which further complicates the task of networking due to myriad of environmental and physical conditions. Developing and testing such systems is an important step considering the large investment required to build ...

Metric Learning Via Linear Embeddings For Human Motion Recognition, Byoungdoo Kong

Masters Theses

We consider the application of Few-Shot Learning (FSL) and dimensionality reduction to the problem of human motion recognition (HMR). The structure of human motion has unique characteristics such as its dynamic and high-dimensional nature. Recent research on human motion recognition uses deep neural networks with multiple layers. Most importantly, large datasets will need to be collected to use such networks to analyze human motion. This process is both time-consuming and expensive since a large motion capture database must be collected and labeled. Despite significant progress having been made in human motion recognition, state-of-the-art algorithms still misclassify actions because of characteristics ...

Nozzle Clogging Prevention And Analysis In Cold Spray, Alden Foelsche

Masters Theses

Cold spray is an additive manufacturing method in which powder particles are accelerated through a supersonic nozzle and impinged upon a nearby substrate, provided they reach their so-called critical velocity. True to its name, the cold spray process employs lower particle temperatures than other thermal spray processes while the particle velocities are comparably high. Because bonding occurs mostly in the solid state and at high speeds, cold spray deposits are distinguished for having low porosity and low residual stresses which nearly match those of the bulk material.

One complication with the cold spray process is the tendency for nozzles to ...

A Study On Latent Thermal Energy Storage (Ltes) Using Phase Change Materials (Pcms) 2020, Ritvij Dixit

Masters Theses

The significant increase in energy requirements across the world, provides several opportunities for innovative methods to be developed to facilitate the storage and utilization of energy. The major energy demand is in the form of electrical energy for domestic as well as industrial sectors, a large part of which are the heating and cooling requirements. Appropriate utilization of thermal energy storage can effectively aid in reducing the electrical demand by storage and release of this thermal energy during peak hours.

Thermal Energy Storage using Phase Change Materials (PCMs) is an attractive method of energy storage, with a wide variety of ...

Considerations For The Design Optimization Of Floating Offshore Wind Turbine Blades, Evan M. Gaertner

Doctoral Dissertations

Floating offshore wind turbines are an immature technology with relatively high costs and risk associated with deployment. Of the few floating wind turbine prototypes and demonstration projects deployed in real metocean conditions, all have used standard turbines design for onshore or offshore fixed bottom conditions. This neglects the unique unsteady aerodynamics brought on by floating support structure motion. While the floating platform has been designed and optimized for a given rotor, the global system is suboptimal due to the rotor operating in conditions outside of which it was design for. If the potential offered by floating wind turbines is to ...

Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey

Doctoral Dissertations

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions.

VFSI ...

System Design And Implementation For Hybrid Network Function Virtualization, Xuzhi Zhang

Doctoral Dissertations

With the application of virtualization technology in computer networks, many new research areas and techniques have been explored, such as network function virtualization (NFV). A significant benefit of virtualization is that it reduces the cost of a network system and increases its flexibility. Due to the increasing complexity of the network environment and constantly improving network scale and bandwidth, it is imperative to aim for higher performance, extensibility, and flexibility in the future network systems. In this dissertation, hybrid NFV platforms applying virtualization technology are proposed. We further explore the techniques used to improve the performance, scalability and resilience of ...

Engineering Mesothelin-Binding Proteins As Targeted Cancer Diagnostics And Therapeutics, Allison Rita Sirois

Doctoral Dissertations

Cancer is a significant global health concern; and traditional therapies, including chemotherapeutics, are often simultaneously toxic yet ineffective. There is a critical need to develop targeted cancer therapeutics which specifically inhibit molecules or molecular pathways essential for tumor growth and maintenance. Furthermore, a targeted therapy is only effective when a patient's tumor expresses the molecular target; therefore, companion diagnostics, including molecular imaging agents, are a necessary counterpart of targeted therapies.

Mesothelin (MSLN) is a cell surface protein overexpressed in numerous cancers, including triple-negative breast, pancreatic, ovarian, liver, and lung, with limited expression in normal tissues. Aberrant MSLN expression promotes ...

Performance Evaluation Of Classical And Quantum Communication Systems, Gayane Vardoyan

Doctoral Dissertations

The Transmission Control Protocol (TCP) is a robust and reliable method used to transport data across a network. Many variants of TCP exist, e.g., Scalable TCP, CUBIC, and H-TCP. While some of them have been studied from empirical and theoretical perspectives, others have been less amenable to a thorough mathematical analysis. Moreover, some of the more popular variants had not been analyzed in the context of the high-speed environments for which they were designed. To address this issue, we develop a generalized modeling technique for TCP congestion control under the assumption of high bandwidth-delay product. In a separate contribution ...

Controlled Membrane Remodeling By Nanospheres And Nanorods: Experiments Targeting The Design Principles For Membrane-Based Materials, Sarah Zuraw-Weston

Doctoral Dissertations

In this thesis we explore two experimental systems probing the interactions of nanoparticles with lipid bilayer membranes. Inspired by the ability of cell membranes to alter their shape in response to bound particles, we report two experimental studies: one of nanospheres the other of long, slender nano-rods binding to lipid bilayer vesicles and altering the membrane shape. Our work illuminates the role of particle geometry, particle concentration, adhesion strength and membrane tension in how membrane morphology is determined. We combine giant unilamellar vesicles with oppositely charged nanoparticles, carefully tuning adhesion strength, membrane tension and particle concentration.

In the case of ...

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material ...