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University of Massachusetts Amherst

2016

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Articles 1 - 30 of 123

Full-Text Articles in Engineering

The Role Of Nitrification And Denitrification In Successful Cultivation Of Oxygenic Photogranules For Wastewater Treatment, Kristie Stauch-White Dec 2016

The Role Of Nitrification And Denitrification In Successful Cultivation Of Oxygenic Photogranules For Wastewater Treatment, Kristie Stauch-White

Environmental & Water Resources Engineering Masters Projects

Oxygenic photogranules (OPGs) are compact, spherical, self-immobilizing biofilms in the form of dense aggregates of microorganisms with a predomination of filamentous cyanobacteria cultivated from photoilluminated activated sludge. In this study, aerobic and anaerobic nitrogen transformation processes occurring simultaneously within OPGs, during both successful and unsuccessful cultivations, were examined. Chemical analyses including ammonium, nitrate, and nitrite concentrations at the beginning and periodically during OPG cultivations indicated nitrogen transformations occurring during successful cultivations. Additionally, qPCR studies revealed that successful cultivations supported a greater relative abundance of cyanobacteria, nitrifying, and denitrifying populations during the cultivation period. Dissolved oxygen microprofiles within a successfully cultivated …

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Analyzing Streamflow Forecasts In The Context Of System Performance: A Case Study Of The City Of Baltimore Water Supply, Alexandra Mcintyre Dec 2016

Analyzing Streamflow Forecasts In The Context Of System Performance: A Case Study Of The City Of Baltimore Water Supply, Alexandra Mcintyre

Environmental & Water Resources Engineering Masters Projects

A major challenge confronting water suppliers is how to best incorporate emerging forecasting technologies into their drought management operations. The need for drought plans that make use of proactive drought mitigation actions is particularly pressing as climate change is expected to cause more frequent and severe droughts in the near future. This research evaluates streamflow forecast skill in the context of drought planning. The City of Baltimore’s water supply system serves as a case study. Forecasts generated by the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service’s Middle Atlantic River Forecast Center (MARFC) are integrated into a …

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Nanoscience At Interfaces And Surfaces: From Jamming To Electrode Texturing, Mengmeng Cui Nov 2016

Nanoscience At Interfaces And Surfaces: From Jamming To Electrode Texturing, Mengmeng Cui

Doctoral Dissertations

This dissertation focuses on the nanoparticle self-assembly on the liquid/liquid interface and the nanomaterial modification on surface. The self-assembly of nanoparticles at the liquid/liquid interface was utilized to trap non-equilibrium morphology when the nanoparticles reach jamming state. The dynamics of jammed systems were further studied by X-ray photon correlation spectroscopy. For the surface part, the nanomaterials were modified on the electrodes to improve the performance of microbial electrosynthesis. Also, a novel and simple method was developed to prepare nanomaterials including nanoparticle surfactants and carbon nanotubes (CNTs).

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Retail Analytics And Optimization For Store-Wide Shelf-Space Management, Tulay Flamand Nov 2016

Retail Analytics And Optimization For Store-Wide Shelf-Space Management, Tulay Flamand

Doctoral Dissertations

A major constituent of modern-time economies, retailing is a vibrant business sector that is marked by high competition, tight profit margins, novel business strategies in online and in-store environments, and demanding consumers. Driven by massive volumes of point-of-sale data, retail analytics has become instrumental for unveiling better managerial practices. Our research falls under the umbrella of retail shelf space management. In self-service outlets, shelf space constitutes a scarce resource and its management is central to ensuring an attractive shopping experience and a profitable business. We investigate how, under a given store layout, the allocation of product categories can be optimized …

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Service Improvement And Cost Reduction For Airlines: Optimal Policies For Managing Arrival And Departure Operations Under Uncertainty, Heng Chen Nov 2016

Service Improvement And Cost Reduction For Airlines: Optimal Policies For Managing Arrival And Departure Operations Under Uncertainty, Heng Chen

Doctoral Dissertations

Annual U.S. air travel demand has been growing steadily by 4-5% over the last decade, and it is estimated that the demand will nearly double in the next twenty years. It has also been estimated by the International Civil Aviation Organization that global demand for commercial aircraft will increase at an average annual rate of 4.1% by 2034 (IATA, 2014). However, airport expansions and aviation infrastructure upgrades have not kept pace with the increase in air traffic demand, as only 3% of all the new airport projects around the world are planned in the U.S. (CAPA, 2015). Thus, the operation …

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Transit Preferential Treatments At Signalized Intersections: Person-Based Evaluation And Real-Time Signal Control, Yashar Zeiynali Farid Nov 2016

Transit Preferential Treatments At Signalized Intersections: Person-Based Evaluation And Real-Time Signal Control, Yashar Zeiynali Farid

Doctoral Dissertations

Efficient public transportation has the potential to relieve traffic congestion and improve overall transportation system performance. In order to improve transit services, Transit Preferential Treatments (TPT) are often deployed to give transit vehicles priority over other vehicles at an intersection or along a corridor. Examples of such treatments are exclusive bus lanes, queue jumper lanes, and signal priority strategies. The objective of this study is threefold: 1) perform a person-based evaluation of alternative TPTs when considered individually and in combination, 2) develop a bus travel time prediction model along a signalized arterial, and 3) develop a real-time signal control system, …

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The Fate Of Haloacetonitriles In Drinking Waters, Yun Yu Nov 2016

The Fate Of Haloacetonitriles In Drinking Waters, Yun Yu

Doctoral Dissertations

The fate of HANs in drinking waters from their precursors in natural waters to their degradation products in consumers’ tap were systematically investigated in this study. Combined amino acids were proved reactive with chlorine to form DCAN under typical drinking water conditions. However, the rate of DCAN formation from bound aspartyl residues was much slower compared to free aspartic acid. The key to DCAN formation from combined amino acids was a chlorine-induced peptide degradation process, which slowly degraded the peptide backbone to continuously produce reactive amine functional groups at the N-terminal end. Particularly, when an N-terminal aspartyl residue …

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Accelerating Iterative Computations For Large-Scale Data Processing, Jiangtao Yin Nov 2016

Accelerating Iterative Computations For Large-Scale Data Processing, Jiangtao Yin

Doctoral Dissertations

Recent advances in sensing, storage, and networking technologies are creating massive amounts of data at an unprecedented scale and pace. Large-scale data processing is commonly leveraged to make sense of these data, which will enable companies, governments, and organizations, to make better decisions and bring convenience to our daily life. However, the massive amount of data involved makes it challenging to perform data processing in a timely manner. On the one hand, huge volumes of data might not even fit into the disk of a single machine. On the other hand, data mining and machine learning algorithms, which are usually …

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Evaporation Induced Self-Assembly And Characterization Of Nanoparticulate Films: A New Route To Bulk Heterojunctions, Yipeng Yang Nov 2016

Evaporation Induced Self-Assembly And Characterization Of Nanoparticulate Films: A New Route To Bulk Heterojunctions, Yipeng Yang

Doctoral Dissertations

Polymer-based semiconducting materials are promising candidates for large-scale, low-cost photovoltaic devices. To date, the efficiency of these devices has been low in part because of the challenge of optimizing molecular packing while also obtaining a bicontinuous structure with a characteristic length comparable to the exciton diffusion length of 10 to 20 nm. In this dissertation we developed an innovative evaporation-induced nanoparticle self-assembly technique, which could be an effective approach to fabricate uniform, densely packed, smooth thin films with cm-scale area from home-made P3HT nanoparticles. Unlike the previous reports of nanoparticle-based film formation, we use a mixture of two solvents so …

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Intrinsic Functions For Securing Cmos Computation: Variability, Modeling And Noise Sensitivity, Xiaolin Xu Nov 2016

Intrinsic Functions For Securing Cmos Computation: Variability, Modeling And Noise Sensitivity, Xiaolin Xu

Doctoral Dissertations

A basic premise behind modern secure computation is the demand for lightweight cryptographic primitives, like identifier or key generator. From a circuit perspective, the development of cryptographic modules has also been driven by the aggressive scalability of complementary metal-oxide-semiconductor (CMOS) technology. While advancing into nano-meter regime, one significant characteristic of today's CMOS design is the random nature of process variability, which limits the nominal circuit design. With the continuous scaling of CMOS technology, instead of mitigating the physical variability, leveraging such properties becomes a promising way. One of the famous products adhering to this double-edged sword philosophy is the Physically …

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Stochastic Network Design: Models And Scalable Algorithms, Xiaojian Wu Nov 2016

Stochastic Network Design: Models And Scalable Algorithms, Xiaojian Wu

Doctoral Dissertations

Many natural and social phenomena occur in networks. Examples include the spread of information, ideas, and opinions through a social network, the propagation of an infectious disease among people, and the spread of species within an interconnected habitat network. The ability to modify a phenomenon towards some desired outcomes has widely recognized benefits to our society and the economy. The outcome of a phenomenon is largely determined by the topology or properties of its underlying network. A decision maker can take management actions to modify a network and, therefore, change the outcome of the phenomenon. A management action is an …

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Thermodynamic And Dynamic Models For Directed Assembly Of Small Ensembles Of Colloidal Particles, Raghuram Thyagarajan Nov 2016

Thermodynamic And Dynamic Models For Directed Assembly Of Small Ensembles Of Colloidal Particles, Raghuram Thyagarajan

Doctoral Dissertations

Self and directed assembly of finite clusters (10 to 1000) of colloidal particles into crystalline objects is an emerging area of scientific interest that finds applica- tions in manufacturing of photonic crystals and other meta-materials. Such assembly problems are also of fundamental scientific interest because they involve thermodynamically small systems, with a number of particles that is far below the bulk limit. Robust methods for assembling defect-free target structures will ultimately require reduced-dimension process models that link the particle-level dynamics of the colloids to the actuator states. We have developed a three-part strategy for developing such process models. First, we …

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Dynamic Processor Reconfiguration For Power, Performance And Reliability Management, Sudarshan Srinivasan Nov 2016

Dynamic Processor Reconfiguration For Power, Performance And Reliability Management, Sudarshan Srinivasan

Doctoral Dissertations

Technology advancements allowed more transistors to be packed in a smaller area, while the improved performance helped in achieving higher clock frequencies. This, unfortunately led to a power density problem, forcing processor industry to lower the clock frequency and integrate multiple cores on the same die. Depending on core characteristics, the multiple cores in the die could be symmetric or asymmetric. Asymmetric multi-core processors (AMPs) have been proposed as an alternative to symmetric multi-cores to improve power efficiency. AMPs comprise of cores that implement the same ISA, but differ in performance and power characteristics due to varying sizes of micro-architectural …

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Biopolymer Electrospun Nanofiber Mats To Inactivate And Remove Bacteria, Katrina Ann Rieger Nov 2016

Biopolymer Electrospun Nanofiber Mats To Inactivate And Remove Bacteria, Katrina Ann Rieger

Doctoral Dissertations

The persistence of antibiotic resistance in bacterial pathogens remains a primary concern for immunocompromised and critically-ill hospital patients. Hospital associated infections can be deadly and reduce the successes of medical advancements, such as, cancer therapies and medical implants. Thus, it is imperative to develop materials that can (i) deliver new antibiotics with accuracy, as well as (ii) uptake pathogenic microbes. In this work, we will demonstrate that electrospun nanofiber mats offer a promising platform for both of these objectives because of their high surface-to-volume ratio, interconnected high porosity, gas permeability, and ability to contour to virtually any surface. To provide …

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Detailed Study Of Integral Abutment Bridges And Performance Of Bridge Joints In Traditional Bridges, Brooke H. Quinn Nov 2016

Detailed Study Of Integral Abutment Bridges And Performance Of Bridge Joints In Traditional Bridges, Brooke H. Quinn

Doctoral Dissertations

Integral Abutment Bridges (IABs) are jointless bridges in which the superstructure is cast monolithically with its substructure. Eliminating expansion joints from the superstructure reduces corrosion of bridge elements that typically result from leaking joints in traditional bridges. IABs have proven to be cost effective for both construction and life-cycle analysis. As a result, they are the standard single span highway bridge of choice by the majority of State Departments of Transportation (DOTs) across the country. Despite the widespread use of these bridges, there are no uniform guidelines in place. Factors such as pile orientation, design assumptions, maximum span length, skew …

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Theoretical Modeling, Experimental Observation, And Reliability Analysis Of Flow-Induced Oscillations In Offshore Wind Turbine Blades, Pariya Pourazarm Nov 2016

Theoretical Modeling, Experimental Observation, And Reliability Analysis Of Flow-Induced Oscillations In Offshore Wind Turbine Blades, Pariya Pourazarm

Doctoral Dissertations

Offshore wind energy has been growing rapidly due to its capacity for utilizing much larger turbines and thus higher power generation compared to onshore. With the increasing size of offshore wind turbine rotors, the design criteria used for the blades may also evolve. Increased flexibility in blades causes them to be more susceptible to experiencing flow-induced instability. One of the destructive aero-elastic instabilities that can occur in flexible structures subjected to aerodynamic loading is coupled-mode flutter. Coupled-mode flutter instability has not been a design driver in the current wind turbine blades, however, considering the industry tendency in utilizing longer and …

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Label-Free And Aptamer-Based Surface Enhanced Raman Spectroscopy For Detection Of Food Contaminants, Shintaro Pang Nov 2016

Label-Free And Aptamer-Based Surface Enhanced Raman Spectroscopy For Detection Of Food Contaminants, Shintaro Pang

Doctoral Dissertations

The development of analytical methods to detect food contaminants is a critical step for improving food safety. Surface enhanced Raman spectroscopy (SERS) is an emerging detection technology that has the potential to rapidly, accurately and sensitively detect a wide variety of food contaminants. However, SERS detection becomes a challenge in real complex matrix, such as food, since non-specific matrix signals have the potential to drown out target associated Raman peaks. In this dissertation, we focused on the development and application of label-free, aptamer-based SERS in order to improve the accuracy and specificity of target contaminant detection in food. To accomplish …

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C-Ku-Band Dual-Polarized Array Element For Shared-Aperture Frequency-Scanning Array, Amin Nikravan Nov 2016

C-Ku-Band Dual-Polarized Array Element For Shared-Aperture Frequency-Scanning Array, Amin Nikravan

Doctoral Dissertations

Accurate now-casting and forecasting could prevent losses and reduce risks caused by severe weather. Key observation to improve our knowledge of the weather is the ocean vector wind. National Oceanic and Atmospheric Administration (NOAA) is embarking on an ambiguous but needed effort to launch a new satellite-based instrument called the Dual Frequency Scatterometer (DFS) that will provide accurate global mapping of the ocean vector wind in a timely manner. The Advanced Wind and Rain Airborne Profiler (AWRAP) can play a pivotal role for this mission by providing critical measurements to improve the geophysical model function that DFS will relay on …

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The Effect Of Interruptions On Primary Task Performance In Safety-Critical Environments, Cheryl Ann Nicholas Nov 2016

The Effect Of Interruptions On Primary Task Performance In Safety-Critical Environments, Cheryl Ann Nicholas

Doctoral Dissertations

Safety critical systems in medicine utilize alarms to signal potentially life threatening situations to professionals and patients. In particular, in the medical field multiple alarms from equipment are activated daily and often simultaneously. There are a number of alarms which require caregivers to take breaks in complex, primary tasks to attend to the interruption task which is signaled by the alarm. The motivation for this research is the knowledge that, in general, interrupting tasks can have a potentially negative impact on performance and outcomes of the primary task. The focus of this research is on the effect of an interrupting …

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Multi-Classifier Fusion Strategy For Activity And Intent Recognition Of Torso Movements, Abhijit Kadrolkar Nov 2016

Multi-Classifier Fusion Strategy For Activity And Intent Recognition Of Torso Movements, Abhijit Kadrolkar

Doctoral Dissertations

As assistive, wearable robotic devices are being developed to physically assist their users, it has become crucial to develop safe, reliable methods to coordinate the device with the intentions and motions of the wearer. This dissertation investigates the recognition of user intent during flexion and extension of the human torso in the sagittal plane to be used for control of an assistive exoskeleton for the human torso. A multi-sensor intent recognition approach is developed that combines information from surface electromyogram (sEMG) signals from the user’s muscles and inertial sensors mounted on the user’s body. Intent recognition is implemented by following …

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Terahertz Radiation From Electrically Driven Graphene, Single Walled Carbon Nanotubes, And Platinum Nanostructures, Martin M. Muthee Nov 2016

Terahertz Radiation From Electrically Driven Graphene, Single Walled Carbon Nanotubes, And Platinum Nanostructures, Martin M. Muthee

Doctoral Dissertations

Terahertz power generation continues to be a subject of great interest owing mainly to the sparsity and diversity of sources. Though there has been remarkable development in sources, ranging from quantum cascade lasers, time domain spectroscopy systems and multiplier sources, there still exists hurdles when it comes to integration and application. While some sources excel in a particular attribute like power, they are severely limited when it comes to on-chip or system integration, for example. Furthermore, tunable bandwidth and power are inversely related. Electrically driven radiation sources are emergent and this thesis presents work in terahertz generation from arrays of …

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Cell Modulation Using Functionalized Nanoparticles, Rui Tang Nov 2016

Cell Modulation Using Functionalized Nanoparticles, Rui Tang

Doctoral Dissertations

Monolayer functionalized ultra-small gold nanoparticles (AuNPs) provide a versatile platform for applications in cell research. Through rational design of surface ligands, the chemistry of AuNPs are precisely regulated at atomic level. In this dissertation, applications of AuNPs in cell modulation are discussed. The topics are split into two categories. In the first category, functionalized AuNPs are harnessed to generate a robust monolayer on cell culture surface for cell modulation. The proliferation and behavior of different types of cancer cells and normal cells are modulated by tuning the surface ligands of AuNPs. Fate decision of mesenchymal stem cells are also modulated …

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On Physical Disorder Based Hardware Security Primitives, Arunkumar Vijayakumar Nov 2016

On Physical Disorder Based Hardware Security Primitives, Arunkumar Vijayakumar

Doctoral Dissertations

With CMOS scaling extending transistors to nanometer regime, process variations from manufacturing impacts modern IC design. Fortunately, such variations have enabled an emerging hardware security primitive - Physically Unclonable Function. Physically Unclonable Functions (PUFs) are hardware primitives which utilize disorder from manufacturing variations for their core functionality. In contrast to insecure non-volatile key based roots-of-trust, PUFs promise a favorable feature - no attacker, not even the PUF manufacturer can clone the disorder and any attempt at invasive attack will upset that disorder. Despite a decade of research, certain practical problems impede the widespread adoption of PUFs. This dissertation addresses the …

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Fabrication Of Ultrafine Structures And Functional Surfaces Over Large Areas, Yinyong Li Nov 2016

Fabrication Of Ultrafine Structures And Functional Surfaces Over Large Areas, Yinyong Li

Doctoral Dissertations

Micro-/nanofabrication finds wide use in the preparation of patterned surfaces, which are of vital importance in the applications of functional surfaces, electronics, optics, and sensors. This dissertation will present the preparation of ultrafine structures and functional surfaces over large areas utilizing a combination of top-down lithography technique and bottom-up wrinkling method. First, a simple, scalable and cost-effective spacer lithography approach utilizing polydopamine coating technique was developed for the fabrication of well-controlled nanopatterns with feature size in the sub-20 nm scale. Briefly, a thin layer of polydopamine (PDA) was conformally deposited on the sidewalls of pre-patterned poly (methyl methacrylate) (PMMA) features …

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Integrated Urban Metabolism Analysis Tool (Iumat), Nariman Mostafavi Nov 2016

Integrated Urban Metabolism Analysis Tool (Iumat), Nariman Mostafavi

Doctoral Dissertations

A number of tools are available today for simulating different aspects of urban activity, but these efforts are fragmented and do not effectively reflect the interrelationships between very diverse groups of urban sectors and resource flows. There is a critical need for robust and reliable urban metabolism analysis tools that integrate socio-economic elements of urbanization and physicality of the built environment into evaluating sustainability in cities. This dissertation outlines the development of an Integrated Urban Metabolism Analysis Tool (IUMAT) that dynamically measures the environmental impacts of land cover, transportation, and consumption of energy, water and materials employing a holistic framework. …

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Low Cross-Polarization Vivaldi Arrays, John Logan Nov 2016

Low Cross-Polarization Vivaldi Arrays, John Logan

Doctoral Dissertations

Ultra-wideband (UWB) electronically scanned arrays (ESA) with high efficiency, excellent polarization agility, and wide-scan matching remain essential for servicing multifunctional RF front-ends and other communications, sensing, and jamming or countermeasure systems. To this day, the most popular antenna array element in modern UWB-ESA systems is the Vivaldi, or flared notch, due to its superior wide-scan wide impedance bandwidth, well-known design guidelines, and practical embodiment versatility. Despite their popularity, these arrays tend to radiate unacceptably high cross-polarization levels, thus encouraging a great research opportunity. This dissertation presents the theory and design of a new class of UWB-ESAs, termed Sliced Notch Antenna …

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A Lower Limb Prosthesis With Active Alignment For Reduced Limb Loading, Andrew Lapre Nov 2016

A Lower Limb Prosthesis With Active Alignment For Reduced Limb Loading, Andrew Lapre

Doctoral Dissertations

Over the past decade, the growing field of robotics has created new possibilities in lower limb prostheses. The focus of these new prostheses has been replicating the dynamics of the lost limb in order to restore gait of individuals with lower limb amputations to healthy norms. This places demanding loads on the residual limb. Compensation by the rest of body is high, causes overloading of intact joints and can lead to deterioration of mobility and overall health. Abnormalities remain present in the person’s gait, stemming from the loading of soft tissue and the altered anatomy of the affected limb. In …

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Study Of The Self-Assembly Process Of Microporous Materials Using Molecular Modeling, Mohammad Navaid Khan Nov 2016

Study Of The Self-Assembly Process Of Microporous Materials Using Molecular Modeling, Mohammad Navaid Khan

Doctoral Dissertations

Zeolites are an important class of materials in modern technology with applications in catalysis, separations, biosensing and microelectronics. There are over 200 different zeolite frameworks reported in literature, but only a handful have been used commercially. Understanding their self-assembly process would assist in the fabrication of new zeolites through the control of their pore size/shape, and surface area for advanced applications. With our research we aim to elucidate aspects of zeolite formation using molecular simulations. We have extended the lattice model of silica tetrahedra developed by Jin et al. [L. Jin, S. M. Auerbach and P. A. Monson J. Chem. …

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Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar Nov 2016

Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar

Doctoral Dissertations

The idea of sequencing a DNA based on single-file translocation of the DNA through nanopores under the action of an electric field has received much attention over the past two decades due to the societal need for low cost and high-throughput sequencing. However, due to the high speed of translocation, interrogating individual bases with an acceptable signal to noise ratio as they traverse the pore has been a major problem. Experimental facts on this phenomenon are rich and the associated phenomenology is yet to be fully understood. This thesis focuses on understanding the underlying principles of polymer translocation, with an …

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Predictive Modeling Of Riverine Constituent Concentrations And Loads Using Historic And Imposed Hydrologic Conditions, Mark Hagemann Nov 2016

Predictive Modeling Of Riverine Constituent Concentrations And Loads Using Historic And Imposed Hydrologic Conditions, Mark Hagemann

Doctoral Dissertations

This research was principally concerned with the task of quantifying dissolved and suspended constituents carried in river water when direct measurements are not available. This is a question of scientific and societal relevance, and one with a long history of study and a great deal of remaining difficulty. The traditional approach to estimating these quantities, linear regression models (LMs), suffers from poor flexibility and high subsequent bias in many applications. This research applied semiparametric generalized additive models (GAMs), a more flexible class of regression models, evaluated their performance in various locations and conditions, and applied them in a proactive modeling …

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