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2019

University of Massachusetts Amherst

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Articles 91 - 111 of 111

Full-Text Articles in Engineering

A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana Mar 2019

A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana

Doctoral Dissertations

Floating offshore wind turbines (FOWTs) hold great potential for the renewable energy industry, but capital costs remain high. In efforts to increase FOWT substructure efficiency and reduce costs, this thesis investigates a novel multiline anchor concept in which FOWTs share anchors instead of being moored separately. The goal of this thesis is to evaluate the force dynamics, design, and potential cost reduction of the system. Anchor forces are simulated using the NREL 5 MW reference turbine and OC4-DeepCwind semisubmersible platform, and multiline anchor force is computed as the vector sum of the contributing mooring line tensions.

The use of a ...


Sequence Design Via Semidefinite Programming Relaxation And Randomized Projection, Dian Mo Mar 2019

Sequence Design Via Semidefinite Programming Relaxation And Randomized Projection, Dian Mo

Doctoral Dissertations

Wideband is a booming technology in the field of wireless communications. The receivers in wideband communication systems are expected to cover a very wide spectrum and adaptively extract the parts of interest. The literature has focused on mixing the input spectrum to baseband using a pseudorandom sequence modulation and recovering the received signals from linearly independent measurements by parallel branches to mitigate the pressures from required extreme high sampling frequency. However, a pseudorandom sequence provides no rejection for the strong interferers received together with weak signals from distant sources. The interferers cause significant distortion due to the nonlinearity of the ...


Energy Efficiency Of Computation In All-Spin Logic: Projections And Fundamental Limits, Zongya Chen Mar 2019

Energy Efficiency Of Computation In All-Spin Logic: Projections And Fundamental Limits, Zongya Chen

Masters Theses

Built with nanomagnets, a spintronic device called the all-spin logic (ASL) device carries information with only spin currents, resulting in a low power supply--10 mV. This voltage is 100 times smaller than the conventional CMOS devices (usually 0.8~1V). The potential for improved energy efficiency made possible by the low operating voltage of ASL makes it one of the most promising devices among its post-CMOS competitors.

The basic working principles of ASL device are introduced in this thesis and two complementary approaches to studying energy efficiency of computation are applied to a common set of ASL circuits: (1) a ...


Application Of Ground Penetrating Radar For Use In Thermal Conductivity Site Investigations, Aaron J. Rubin Mar 2019

Application Of Ground Penetrating Radar For Use In Thermal Conductivity Site Investigations, Aaron J. Rubin

Doctoral Dissertations

Measurement of soil thermal conductivity in-situ is important for many practical geotechnical and civil engineering applications. However, for a variety of reasons it can be difficult to measure in-situ. A novel method to estimate the thermal conductivity of sands based on electrical relative permittivity (dielectric constant) measurements and GPR data is presented. First, an analytical model to estimate thermal conductivity of soils was developed and validated using a database of thermal conductivity measurements. The new thermal conductivity model was then compared to existing models using a larger database of new and pervious thermal conductivity measurements conducted on a wide range ...


Analysis Of Adhesive Anchorage Systems Under Extreme In-Service Temperature Conditions, Rachel Wang Mar 2019

Analysis Of Adhesive Anchorage Systems Under Extreme In-Service Temperature Conditions, Rachel Wang

Masters Theses

Adhesive anchorage systems have found widespread use in structural applications, including bridge widening, concrete repair and rehabilitation, and barrier retrofitting. Because these applications typically require adhesive anchorage systems to be installed outdoors, the effects of climate conditions and day-to-day temperature fluctuations on adhesive behavior and performance should be considered. The purpose of this thesis is to simulate pullout tests of adhesive anchorage systems for threaded rod and reinforcing bars and to emulate effects under various temperature conditions through the use of finite element analysis. Results from the finite element simulation are then compared to the physical tests conducted at UMass ...


Ammonia Production From A Non-Grid Connected Floating Offshore Wind-Farm: A System-Level Techno-Economic Review, Vismay V. Parmar Mar 2019

Ammonia Production From A Non-Grid Connected Floating Offshore Wind-Farm: A System-Level Techno-Economic Review, Vismay V. Parmar

Masters Theses

According to U.S. Department of Energy, offshore wind energy has the potential to generate 7,200 TWh of energy annually, which is nearly twice the current annual energy consumption in the United States. With technical advances in the offshore wind industry, particularly in the floating platforms, windfarms are pushing further into the ocean. This creates new engineering challenges for transmission of energy from offshore site to onshore. One possible solution is to convert the energy produced into chemical energy of ammonia, which was investigated by Dr. Eric Morgan. In his doctoral dissertation, he assessed the technical requirements and economics ...


Performance Of Concrete Tunnel Systems Subject To Fault Displacement, Michael Morano Mar 2019

Performance Of Concrete Tunnel Systems Subject To Fault Displacement, Michael Morano

Masters Theses

A Finite Element Analysis (FEA) investigation of concrete tunnel systems traversing seismic faults is carried out to determine how to effectively mitigate the stresses induced in the liner when subject to fault displacement. A parametric study of various fault parameters, both in the damage zone and competent rock, is carried out to determine the site conditions which induce the most stress on the tunnel liner system. Results indicate that friction angle, cohesion, and elastic modulus of fault zones have varying effects on the stresses induced on the liner. The width of damage zone and expected displacements are also investigated and ...


Insar Simulations For Swot And Dual Frequency Processing For Topographic Measurements, Gerard Masalias Huguet Mar 2019

Insar Simulations For Swot And Dual Frequency Processing For Topographic Measurements, Gerard Masalias Huguet

Masters Theses

In Earth remote sensing precise characterization of the backscatter coefficient is important to extract valuable information about the observed target. A system that eliminates platform motion during near-nadir airborne observations is presented in this thesis, showing an improvement on the accuracy of measurements for a Ka- band scatterometer previously developed at Microwave Remote Sensing Laboratory (MIRSL). These very same results are used to simulate the reflectivity of such targets as seen from a spaceborne radar and estimate height errors based on mission-specific geometry. Finally, data collected from a dual-frequency airborne interferometer com- prised by the Ka-band system and an S-band ...


High Fidelity Modeling Of Cold-Formed Steel Single Lap Shear Screw Fastened Connections, Rita Kalo Mar 2019

High Fidelity Modeling Of Cold-Formed Steel Single Lap Shear Screw Fastened Connections, Rita Kalo

Masters Theses

Cold-formed steel connections are commonly fastened using self-tapping self-drilling screws. The behavior of these connections can differ based on the screw manufacturer or the cold-formed steel product used, both of which have a large selection available for use in industry. Because of their popularity and the many possible variations of these connections, researchers have frequently tested screw connections to characterize their behavior. However, repeatedly conducting this type of experiment is time consuming and expensive. Therefore, the purpose of this work was to create finite element models that can successfully predict the behavior of single lap shear screw connections, a common ...


The Evacuation Problem In Multi-Story Buildings, Quang Hong Cung Mar 2019

The Evacuation Problem In Multi-Story Buildings, Quang Hong Cung

Masters Theses

The pressure from high population density leads to the creation of high-rise structures within urban areas. Consequently, the design of facilities which confront the challenges of emergency evacuation from high-rise buildings become a complex concern. This paper proposes an embedded program which combines a deterministic (GMAFLAD) and stochastic model (M/G/C/C State Dependent Queueing model) into one program, GMAF_MGCC, to solve an evacuation problem. An evacuation problem belongs to Quadratic Assignment Problem (QAP) class which will be formulated as a Quadratic Set Packing model (QSP) including the random flow out of the building and the random pairwise traffic ...


Nonlinear Fastener-Based Modeling Of Cold-Formed Steel Shear Walls Under Lateral Loads, Fani Derveni Jan 2019

Nonlinear Fastener-Based Modeling Of Cold-Formed Steel Shear Walls Under Lateral Loads, Fani Derveni

Structural Engineering Masters Projects

As cold-formed steel (CFS) has increasingly been used in low- and mid-rise construction across United States, it becomes necessary to capture and evaluate its lateral response in both, sub-system/member level and system level. The main lateral resisting system in cold-formed steel construction is shear walls; shear walls are the focus of this work. In particular, the present study aims to shed light on the response of wood sheathed coldformed steel (CFS) shear walls exposed to earthquake events through nonlinear high fidelity fastener-based modeling. The numerical approach is fastener-oriented including nonlinear experimental-determined connector elements for steel-to-sheathing connections, orthotropic oriented strand ...


Driver Performance Due To Unmanned Aerial System Applications In The Vicinity Of Surface Transportation, Alyssa M. Ryan Jan 2019

Driver Performance Due To Unmanned Aerial System Applications In The Vicinity Of Surface Transportation, Alyssa M. Ryan

Transportation Engineering Masters Projects

Unmanned aerial systems (UAS), or drones, have become increasingly utilized for a myriad of applications in the vicinity of the roadway and can offer a low-cost alternative to many labor-intensive data collection techniques, including infrastructure inspection, roadway marking data collection, and more. To collect much of this data with a desired degree of accuracy, UAS must be flown near moving vehicles, pedestrians, and/or bicyclists. However, UAS, and their pilot/crew, have the potential to be a distraction to drivers. A study by Hurwitz et al. suggests that UAS operations are more distracting to drivers as the UAS traverses closer ...


Driver Behaviour And Performances On In-Vehicle Display Based Speed Compliance, Aamani Ramanathan Parthasarthy Jan 2019

Driver Behaviour And Performances On In-Vehicle Display Based Speed Compliance, Aamani Ramanathan Parthasarthy

Transportation Engineering Masters Projects

Traffic Control Devices (TCDs) are integral to driver-to-infrastructure (D2I) and vehicleto- infrastructure (V2I) interactions. The non-conformation (or non-perception) with signage on the part of the driver leads to several compounded safety problems. The need exists for a more robust, low-cost, and user-centric mechanism of delivering information to the driver that can directly bear on the safety of the driver. Technology has now advanced to the point where we can deliver information from a real-world physical environment to the driver in a non-invasive manner using holographic display [1]. With this rapid advancement in-vehicle display (IVD) technology, the transportation industry must undergo ...


Over-Citing Or Under-Citing? A Gis-Based Analysis Of The Relationship Between Crashes And Citations, Mitchell Page Jan 2019

Over-Citing Or Under-Citing? A Gis-Based Analysis Of The Relationship Between Crashes And Citations, Mitchell Page

Transportation Engineering Masters Projects

In July of 2017, the Boston Globe published an article titled “Driving Through These Towns in Mass.? Watch Your Speed” [1] that among other elements, included a series of maps and a brief summary identifying Massachusetts municipalities that had the most traffic violations issued between 2010 and 2016. The article stated that the Massachusetts State Police issued the most citations of any police agency in the state, and that many citations were given along major highways, especially Interstate 90 and major highways and routes that intersect it, such as Interstate 84 and Route 20. Despite the public attention-grabbing nature of ...


Modelling The Surrogate Safety Of Various Left-Turn Phase Sequences, Rohith Prakash Panthangi Jan 2019

Modelling The Surrogate Safety Of Various Left-Turn Phase Sequences, Rohith Prakash Panthangi

Transportation Engineering Masters Projects

Left-turns are the most complex maneuvers in a signalized intersection. Based on the flow of the traffic volume through a given intersection, the left-turn phasing may be controlled in various fashions such as: protected only, permissive only, and protected/permissive. Following the introduction of the flashing yellow arrow (FYA) to the 2009 Edition of the Manual on Uniform Traffic Control Devices (MUTCD), many state agencies have implemented these indications for their left-turn permissive movements. Similar to the existing circular green (CG) permissive indication, the FYA requires drivers to yield to oncoming vehicles before making their left-turn. However, given the novelty ...


Drawing The City, Sandy Litchfield Jan 2019

Drawing The City, Sandy Litchfield

Sustainability Education Resources

How do we represent the spatial and social complexities of contemporary urban environments? And why is this important for artists, designers, planners, architects, and landscape architects?

Twenty-first century cities are complex, messy and wicked. They can be dazzling, magnificent and aweinspiring, full of diverse culture, creative activity, architectural marvels, and cutting-edge innovation. But they are also facing some of the most challenging problems in history– unprecedented economic inequality, sea level change, unpredictable weather events and severe pollution to name just a few. In trying to understand such a complicated system, we need to develop and hone new and distinctive methodsforrepresentation ...


The Core Of Social Network Modeling: Industrial Engineering., Shannon C. Roberts, Chaitra Gopalappa, Nazanin Nazanin Jan 2019

The Core Of Social Network Modeling: Industrial Engineering., Shannon C. Roberts, Chaitra Gopalappa, Nazanin Nazanin

Science and Engineering Saturday Seminars

Networks are abound in our everyday lives, from disaster response networks to cellular networks to social networks. In this workshop, we will introduce the different types of networks and how Industrial Engineering is used to model these networks. Next, we will describe current social network modeling research done at UMass. Finally, we will delve into hands-on activities that include social network analysis, such as the clustering of people into groups, and modeling of the spread of ideas in a social network, such as how tweets spread on Twitter.


Design Rules For Encapsulating Proteins Into Complex Coacervates, Whitney Blocher Mctigue, Sarah L. Perry Jan 2019

Design Rules For Encapsulating Proteins Into Complex Coacervates, Whitney Blocher Mctigue, Sarah L. Perry

Chemical Engineering Faculty Publication Series

We investigated the encapsulation of the model proteins bovine serum albumin (BSA), human hemoglobin (Hb), and hen egg white lysozyme (HEWL) into two-polymer complex coacervates as a function of polymer and solution conditions. Electrostatic parameters such as pH, protein net charge, salt concentration, and polymer charge density can be used to modulate protein uptake. While the use of a two-polymer coacervation system enables the encapsulation of weakly charged proteins that would otherwise require chemical modification to facilitate electrostatic complexation, we observed significantly higher uptake for proteins whose structure includes a cluster of like-charged residues on the protein surface. In addition ...


Designing Electrostatic Interactions Via Polyelectrolyte Monomer Sequence, Tyler K. Lytle, Li-Wei Chang, Natalia Markiewicz, Sarah L. Perry, Charles E. Sing Jan 2019

Designing Electrostatic Interactions Via Polyelectrolyte Monomer Sequence, Tyler K. Lytle, Li-Wei Chang, Natalia Markiewicz, Sarah L. Perry, Charles E. Sing

Chemical Engineering Faculty Publication Series

Charged polymers are ubiquitous in biological systems because electrostatic interactions can drive complicated structure formation and respond to environmental parameters such as ionic strength and pH. In these systems, function emerges from sophisticated molecular design; for example, intrinsically disordered proteins leverage specific sequences of monomeric charges to control the formation and function of intracellular compartments known as membraneless organelles. The role of a charged monomer sequence in dictating the strength of electrostatic interactions remains poorly understood despite extensive evidence that sequence is a powerful tool biology uses to tune soft materials. In this article, we use a combination of theory ...


Ionoelastomer Junctions Between Polymer Networks Of Fixed Anions And Cations, Hyeongjun Kim, Baohong Chen, Zhigang Suo, Ryan C. Hayward Jan 2019

Ionoelastomer Junctions Between Polymer Networks Of Fixed Anions And Cations, Hyeongjun Kim, Baohong Chen, Zhigang Suo, Ryan C. Hayward

Data and Datasets

Readme file included in ZIP file.


Source Data For "Tuning Charge Transport Dynamics Via Clustering Of Doping In Organic Semiconductor Thin Films", Connor J. Boyle, Meenakshi Upadhyaya, Dhandapani Venkataraman, Zlatan Aksamija, Michael Lu-Díaz Jan 2019

Source Data For "Tuning Charge Transport Dynamics Via Clustering Of Doping In Organic Semiconductor Thin Films", Connor J. Boyle, Meenakshi Upadhyaya, Dhandapani Venkataraman, Zlatan Aksamija, Michael Lu-Díaz

Data and Datasets

No abstract provided.