Engineering Commons^™

Advanced Implementations Of The Iterative Multi Region Technique, Fatih Kaburcuk

Dissertations - ALL

The integration of the finite-difference time-domain (FDTD) method into the iterative multi-region (IMR) technique, an iterative approach used to solve large-scale electromagnetic scattering and radiation problems, is presented in this dissertation. The idea of the IMR technique is to divide a large problem domain into smaller subregions, solve each subregion separately, and combine the solutions of subregions after introducing the effect of interaction to obtain solutions at multiple frequencies for the large domain. Solution of the subregions using the frequency domain solvers has been the preferred approach as such solutions using time domain solvers require computationally expensive bookkeeping of time …

A Study For The Propagation Of Electromagnetic Waves Over Imperfect Ground Planes Based On Schelkunoff Integrals, Walid Mohamed Galal Dyab

Dissertations - ALL

A new formulation for the analysis of propagation of electromagnetic waves over imperfectly conducting planar surfaces is proposed. The classical approach for the analysis of this problem uses the Sommerfeld formulation. In Sommerfeld formulation, the wave function corresponding to a point source is expanded in terms of the propagation constants of the various waves in the radial direction from the source. This gives rise to the well-known Sommerfeld integrals which are highly oscillatory and slowly-decaying in nature, especially when the source is mounted just on top of a planar boundary between two media of arbitrary conductivity. In addition, the nature …

Developing Critical Loads And Dynamic Critical Loads For Acidification For Watersheds In The Adirondack Region Of New York And Great Smoky Mountain National Park (Grsm), Qingtao Zhou

Dissertations - ALL

Critical loads (CLs) and dynamic critical loads (DCLs) are important tools for the management of ecosystems that are impacted by high sulfate, nitrate and ammonium deposition. In this study, a biogeochemical model (PnET-BGC) was applied to 20 watersheds in the Adirondack region and 12 watersheds in Great Smoky Mountain National Park (GRSM) to calculate CLs and DCLs. I evaluated ecosystem changes in response to historical and potential future changes in acidic deposition. I analyzed factors affecting CLs and DCLs for acidification in the acid impacted Constable Pond Watershed in the Adirondack region, specifically evaluating trade-offs of sulfate and nitrate deposition, …

Hypothesis Testing Using Spatially Dependent Heavy-Tailed Multisensor Data, Arun Subramanian

Dissertations - ALL

The detection of spatially dependent heavy-tailed signals is considered in this dissertation. While the central limit theorem, and its implication of asymptotic normality of interacting random processes, is generally useful for the theoretical characterization of a wide variety of natural and man-made signals, sensor data from many different applications, in fact, are characterized by non-Gaussian distributions. A common characteristic observed in non-Gaussian data is the presence of heavy-tails or fat tails. For such data, the probability density function (p.d.f.) of extreme values decay at a slower-than-exponential rate, implying that extreme events occur with greater probability. When these events are observed …

Adaptive Power Management For Computers And Mobile Devices, Hao Shen

Dissertations - ALL

Power consumption has become a major concern in the design of computing systems today. High power consumption increases cooling cost, degrades the system reliability and also reduces the battery life in portable devices. Modern computing/communication devices support multiple power modes which enable power and performance tradeoff. Dynamic power management (DPM), dynamic voltage and frequency scaling (DVFS), and dynamic task migration for workload consolidation are system level power reduction techniques widely used during runtime. In the first part of the dissertation, we concentrate on the dynamic power management of the personal computer and server platform where the DPM, DVFS and task …

Discrete Gate Sizing Methodologies For Delay, Area And Power Optimization, Jiani Xie

Dissertations - ALL

The modeling of an individual gate and the optimization of circuit performance has long been a critical issue in the VLSI industry. In this work, we first study of the gate sizing problem for today's industrial designs, and explore the contributions and limitations of all the existing approaches, which mainly suffer from producing only continuous solutions, using outdated timing models or experiencing performance inefficiency.

In this dissertation, we present our new discrete gate sizing technique which optimizes different aspects of circuit performance, including delay, area and power consumption. And our method is fast and efficient as it applies the local …

The Unified-Fft Method For Fast Solution Of Integral Equations As Applied To Shielded-Domain Electromagnetics, Brian J. Rautio

Dissertations - ALL

Electromagnetic (EM) solvers are widely used within computer-aided design (CAD) to improve and ensure success of circuit designs. Unfortunately, due to the complexity of Maxwell's equations, they are often computationally expensive. While considerable progress has been made in the realm of speed-enhanced EM solvers, these fast solvers generally achieve their results through methods that introduce additional error components by way of geometric approximations, sparse-matrix approximations, multilevel decomposition of interactions, and more. This work introduces the new method, Unified-FFT (UFFT). A derivative of method of moments, UFFT scales as O(N log N), and achieves fast analysis by the unique combination of …

Infiltration Performance Of Engineered Surfaces Commonly Used For Distributed Stormwater Management, Nick Alexander Valinski

Theses - ALL

Engineered porous media are commonly used in low impact development (LID) structures to mitigate excess stormwater in urban environments. Differences in infiltrability of these LID systems arise from the wide variety of materials used to create porous surfaces and subsequent maintenance, debris loading, and physical damage. In this study, infiltration capacity of six common materials was tested by multiple replicate experiments with automated mini-disk infiltrometers. The tested materials included porous asphalt, porous concrete, porous brick pavers, flexible porous pavement, engineered soils, and native soils. Porous asphalt, large porous brick pavers, and curb cutout rain gardens showed the greatest infiltration rates. …

The Effects Of Watershed Liming On Mercury Concentrations And Stocks In Soil Of Woods Lake, New York, Zhenni Xie

Theses - ALL

Abstract

In acid-impacted forests, lime has been applied to neutralize acidity and mitigate acidification of soil and surface waters. However, few studies have evaluated the effects of liming on watershed mercury processes and transport. I investigated the effects of liming on mercury, organic carbon, and sulfur concentrations and stocks in forest soil 19 years after the application of lime to the Woods Lake Watershed, Adirondack Park, New York, USA (42o52' N, 71o58' W). The mercury, organic carbon, and sulfur stocks were significantly greater in the forest floor of limed areas (24.5 vs. 11.1 Hg g/ha for Oe and 31.6 vs. …

Indium Telluride Cylinder Fiber Laser, Abhinay Sandupatla

Theses - ALL

A new type of fiber laser is described here. The laser consists of a 25 mm long fiber with an approximately 15 nm thick In2Te3 semiconductor layer at the glass core glass cladding boundary. The laser mirrors consist of a thick vacuum deposited aluminum layer at one end and a thin semitransparent aluminum layer deposited at the other end of the fiber. The laser is pumped from the side with either light from a Halogen Tungsten incandescent lamp or a blue, power LED. Since both, the gain of the In2Te3 semi-conductor and aluminum mirrors have a wide bandwidth the output …

The Effect Of Surface Roughness On The Fretting Corrosion Of 316l Stainless Steel Biomaterial Surfaces, Aarti Shenoy

Theses - ALL

The medical device industry is still seeking answers to the mechanically-assisted corrosion (MAC) problem, which becomes increasingly important due to modularity in design. MAC manifests in various forms, some of which are fretting corrosion, crevice corrosion and stress corrosion. Several studies have been conducted to understand the causes and the factors that affect fretting corrosion. Some of the factors are the applied load, surface potential, oxide film characteristics and solution chemistry near the interface. Surface properties such as surface roughness determine the topography of the surface and the nature of asperity-asperity contact, which is a factor that would determine the …

Early Performance Prediction Methodology For Many-Cores On Chip Based Applications, Boray S. Deepaksubramanyan

Dissertations - ALL

Modern high performance computing applications such as personal computing, gaming, numerical simulations require application-specific integrated circuits (ASICs) that comprises of many cores. Performance for these applications depends mainly on latency of interconnects which transfer data between cores that implement applications by distributing tasks. Time-to-market is a critical consideration while designing ASICs for these applications. Therefore, to reduce design cycle time, predicting system performance accurately at an early stage of design is essential. With process technology in nanometer era, physical phenomena such as crosstalk, reflection on the propagating signal have a direct impact on performance. Incorporating these effects provides a better …

Transient Electromagnetic Scattering By A Radially Uniaxial Dielectric Sphere: Debye Series, Mie Series And Ray Tracing Methods, Mohsen Yazdani

Dissertations - ALL

Transient electromagnetic scattering by a radially uniaxial dielectric sphere is explored using three well-known methods: Debye series, Mie series, and ray tracing theory.

In the first approach, the general solutions for the impulse and step responses of a uniaxial sphere are evaluated using the inverse Laplace transformation of the generalized Mie series solution. Following high frequency scattering solution of a large uniaxial sphere, the Mie series summation is split into the high frequency (HF) and low frequency terms where the HF term is replaced by its asymptotic expression allowing a significant reduction in computation time of the numerical Bromwich integral. …

Reputation Computation In Social Networks And Its Applications, Jooyoung Lee

Dissertations - ALL

This thesis focuses on a quantification of reputation and presents models which compute reputation within networked environments. Reputation manifests past behaviors of users and helps others to predict behaviors of users and therefore reduce risks in future interactions. There are two approaches in computing reputation on networks- namely, the macro-level approach and the micro-level approach. A macro-level assumes that there exists a computing entity outside of a given network who can observe the entire network including degree distributions and relationships among nodes. In a micro-level approach, the entity is one of the nodes in a network and therefore can only …

Evaluation Of Volatile And Semi-Volatile Organic Compounds Potentially Associated With The Gas Shale Fracturing Process In The Fayetteville And Marcellus Shale, Karl Albert Oetjen

Theses - ALL

With the recent growth of the natural gas industry coupled with technological advancements, gas shale fracturing has become an effective and highly profitable method for natural gas production. Unlike conventional natural gas extraction which may require vertical fracturing, gas shale fracturing relies on a method known as horizontal fracturing to remove gas trapped within the impermeable facies. Compared to vertical fracturing, horizontal fracturing requires larger amounts of fluids to be injected downhole under high pressure. These fracturing fluids can contain high concentrations of petroleum hydrocarbons with known adverse health effects. Due to the large volumes used, the potential for groundwater …

Identifying Extract Class And Extract Method Refactoring Opportunities Through Analysis Of Variable Declarations And Uses, Mehmet Kaya

Dissertations - ALL

For small software systems, with perhaps a few thousand lines of code, software structure is largely an esthetic issue. When software systems grow large, including perhaps a million or more lines of source code, their structures become much more important.

Developing a large system requires teams of developers working in concert to provide a finished product in a reasonable amount of time. That means that many people will read each component to use, test or modify towards accomplishing new features.

In the software development life cycle, the maintenance phase is a dominant stage that impacts production cost of the system …

Soft Shape-Memory Polymers As A Platform For Biomedical Applications, Amir Hossein Torbati

Dissertations - ALL

Soft Shape-Memory Polymers as a Platform for Biomedical Applications

Abstract

by

Amir Hossein Torbati

The overall objective of this work was to expand on the previous efforts carried out by other researchers to develop series of "smart" or stimulus-responsive shape-memory polymers for biomaterials applications. For this purpose, novel shape-memory polymers were fabricated and their macrostructure and microstructure were studied to understand their effects on overall shape-memory characteristics and mechanical properties of these materials. The advent of shape-memory polymers has significantly influenced the development and rapid growth of various functional polymers. Shape-memory polymers are used where the dynamic functions of polymers …

Dyadic Green's Functions For Layered General Anisotropic Media And Their Application To Radiation Of Dipole Antennas, Ying Huang

Dissertations - ALL

In this dissertation, the dyadic Green‟s functions (DGFs) for unbounded and layered anisotropic media, with no restriction imposed on the medium property, are derived. Utilizing the obtained DGFs, the radiation problems of a Hertzian dipole and a microstrip antenna in the presence of an anisotropic substrate are solved.

After a brief introduction, the eigenvector dyadic Green‟s functions (E-DGFs) for an unbounded general anisotropic medium through the eigen-decomposition method are derived. The E-DGFs of a layered anisotropic geometry are then constructed based on the derivation of the unbounded E-DGFs using two different approaches. One is through the symmetrical property of the …

Mercury Transport And Fluxes In The Lake Ontario Basin, Joseph Steven Denkenberger

Dissertations - ALL

In this dissertation I assess mercury dynamics in the Lake Ontario Basin. In four interrelated phases, ecosystem mercury concentrations and fluxes were analyzed at increasing scales. Each phase is presented in order of increasing scale, starting with a reach-by-reach analysis in the Seneca River in New York, then moving up to an analysis of the Lake Ontario watershed, followed by an assessment of Lake Ontario, and culminating with an estimate of atmospheric mercury exchange for the entire Great Lakes Basin.

Phase 1 of my research is a multi-year study exploring mercury (Hg) dynamics in the Three Rivers system, with particular …

Distributed Estimation And Performance Limits In Resource-Constrained Wireless Sensor Networks, Yujiao Zheng

Dissertations - ALL

Distributed inference arising in sensor networks has been an interesting and promising discipline in recent years. The goal of this dissertation is to investigate several issues related to distributed inference in sensor networks, emphasizing parameter estimation and target tracking with resource-constrainted networks.

To reduce the transmissions between sensors and the fusion center thereby saving bandwidth and energy consumption in sensor networks, a novel methodology, where each local sensor performs a censoring procedure based on the normalized innovation square (NIS), is proposed for the sequential Bayesian estimation problem in this dissertation. In this methodology, each sensor sends only the informative measurements …

Solving Time Domain Scattering And Radiation Problems In A Marching-On-In-Degree Technique For Method Of Moment, Zicong Mei

Dissertations - ALL

The time domain method of moment has been proposed for a long time. The marching-on-in-time solver suffers from late time instability, while the marching-on-in-degree technique can avoid this problem.

This thesis introduces a new temporal basis function and a new Green's function form that improves the computation speed of the marching-on-in-degree technique. This method can be used for the perfect conductor and can also be applied to conductors with loss or dielectric.

As a method of moment solver, this marching-on-in-degree technique must solve a dense matrix equation and it may be time consuming if the objects are very large. Therefore, …

Network Theoretic Analyses And Enhancements Of Evolutionary Algorithms, Karthik Kuber

Dissertations - ALL

Information in evolutionary algorithms is available at multiple levels; however most analyses focus on the individual level. This dissertation extracts useful information from networks and communities formed by examining interrelationships between individuals in the populations as they change with time.

Network theoretic analyses are extremely useful in multiple fields and applications, e.g., biology (regulation of gene expression), organizational behavior (social networks), and intelligence data analysis (message traffic on the Internet). Evolving populations are represented as dynamic networks, and we show that changes in population characteristics can be recognized at the level of the networks representing successive generations, with implications for …

Effect Of Confinement And Temperature On The Behavior Of Eps Geofoam, Amsalu Birhan

Dissertations - ALL

EPS geofoam blocks underlying compacted soil and structural loads become subjected to multi-axial loading. Effects of confining pressure on the stress-strain behavior of EPS geofoam have been investigated in previous studies. Some studies found increases in confining stress lead to corresponding decreases in both modulus and compressive strength. Increasing confining stress has also been reported to result in higher compressive strength. Regardless of the sense and attributed significance of the effects of confinement on EPS geofoam behavior, the implied effects on performance are generally not considered in practice. A series of triaxial compression tests were conducted on EPS geofoams of …

Electrochemical Control Of Bacterial Persister Cells, Tagbo Herman Roland Niepa

Dissertations - ALL

The emergence of antibiotic-resistant bacteria has presented an increasing challenge to infection control. Conventional methods of antibacterial treatment involving high dose of antibiotics or surgical intervention have proven insufficient for eradicating persistent infections, such as those associated with medical implants. It is well recognized that bacterial populations commonly contain a small percentage of phenotypic variants, known as persister cells, which are metabolically inactive and extremely tolerant to antibiotics. When the antibiotic treatment is stopped, surviving persister cells can regenerate the bacterial population with a similar percentage of persister cells. Thus, persistence presents a great challenge to curing chronic infections.

In …

Attacks And Countermeasures For Webview On Mobile Systems, Tongbo Luo

Dissertations - ALL

ABSTRACT

All the mainstream mobile operating systems provide a web container, called ``WebView''. This Web-based interface can be included as part of the mobile application to retrieve and display web contents from remote servers. WebView not only provides the same functionalities as web browser, more importantly, it enables rich interactions between mobile apps and webpages loaded inside WebView. Through its APIs, WebView enables the two-way interaction. However, the design of WebView changes the landscape of the Web, especially from the security perspective.

This dissertation conducts a comprehensive and systematic study of WebView's impact on web security, with a particular focus …

Patterned Biofilm Formation To Investigate Bacteria-Surface Interactions, Huan Gu

Dissertations - ALL

Bacterial adhesion to surfaces and subsequent formation of microcolonies play important roles in biofilm formation, which is a major cause of chronic infections and persistent biofouling. Despite the significance, mechanistic understanding of biofilm formation is still hindered by the structural heterogeneity in biofilms; and effective control of biofilm formation remains challenging. Biofilm formation is a dynamic process that involves numerous changes in bacterial gene and protein expression. These changes are highly sensitive to environmental factors such as surface chemistry, topography, charge, and hydrophobicity. To better control biofilm morphology and specifically investigate the effects of these factors, a platform was developed …

Energy-Efficient Lightweight Algorithms For Embedded Smart Cameras: Design, Implementation And Performance Analysis, Mauricio Casares

Dissertations - ALL

An embedded smart camera is a stand-alone unit that not only captures images, but also includes a processor, memory and communication interface. Battery-powered, embedded smart cameras introduce many additional challenges since they have very limited resources, such as energy, processing power and memory. When camera sensors are added to an embedded system, the problem of limited resources becomes even more pronounced. Hence, computer vision algorithms running on these camera boards should be light-weight and efficient. This thesis is about designing and developing computer vision algorithms, which are aware and successfully overcome the limitations of embedded platforms (in terms of power …

The Effects Of Active Flow Control On High-Speed Jet Flow Physics And Noise, Zachary P. Berger

Dissertations - ALL

The work to be presented focuses on the noise generation of a fully turbulent, compressible jet flow within a large scale anechoic chamber. The investigations are aimed at understanding the complex nature of the jet flow field in an effort to reduce the far-field noise through active flow control and novel reduced-order modeling. The flow field of a highly subsonic, axisymmetric jet with a nozzle diameter of two inches (50.8 mm), is probed through the implementation of two-component particle image velocimetry (PIV) in the streamwise plane, along the jet's centerline. These measurements are coupled with simultaneously sampled near and far-field …

Hydrochemical Dynamics Under Differing Winter Climate Regimes At The Hubbard Brook Experiment Forest, Colin Fuss

Dissertations - ALL

This dissertation is a two-phase study of the hydrochemical dynamics of drainage waters at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA, that aims to improve understanding of changes in water quality associated with winter climate variation. The first phase was an analysis of the long-term stream and soil water chemistry dataset from Watershed 6, the biogeochemical reference watershed of the HBEF. The second phase was a series of field measurements designed to evaluate variation in the chemistry and hydrology of stream and soil water across a natural gradient of winter climate at the HBEF.

Thirty years (1982-2011) …

Application Of Data Fusion To Fluid Dynamic Data, Christopher John Ruscher

Dissertations - ALL

In recent years, there have been improvements in the methods of obtaining fluid dynamic data, which has led to the generation of vast amounts of data. Extracting the useful information from large data sets can be a challenging task when investigating data from a single source. However, most experiments use data from multiple sources, such as particle image velocimetry (PIV), pressure sensors, acoustic measurements, and computational fluid dynamics (CFD), to name a few. Knowing the strengths and weaknesses of each measurement technique, one can fuse the data together to improve the understanding of the problem being studied. Concepts from the …