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Articles 1 - 30 of 55
Full-Text Articles in Engineering
Application Of Techniques For Map Estimation To Distributed Constraint Optimization Problem, Yoonheui Kim
Application Of Techniques For Map Estimation To Distributed Constraint Optimization Problem, Yoonheui Kim
Doctoral Dissertations
The problem of efficiently finding near-optimal decisions in multi-agent systems has become increasingly important because of the growing number of multi-agent applications with large numbers of agents operating in real-world environments. In these systems, agents are often subject to tight resource constraints and agents have only local views. When agents have non-global constraints, each of which is independent, the problem can be formalized as a distributed constraint optimization problem (DCOP). The DCOP is closely associated with the problem of inference on graphical models. Many approaches from inference literature have been adopted to solve DCOPs. We focus on the Max-Sum algorithm …
Multi-Scale Characterization And Engineering Of Taxus Suspension Cultures, Sarah A. Wilson
Multi-Scale Characterization And Engineering Of Taxus Suspension Cultures, Sarah A. Wilson
Doctoral Dissertations
Plants produce a diversity of natural products that have commercial applications as flavorings, fragrances, pesticides and pharmaceuticals. These compounds are often the result of specialized metabolic pathways that are unique to plant systems, and have complex structures that make chemical synthesis routes infeasible. This necessitates exploitation of biological production routes. This thesis work presents a multi-scale characterization and engineering approach to understand and manipulate plant cell cultures on the extracellular (culture) and intracellular (metabolic pathway) levels. Studies focus on the commercially relevant suspension culture system Taxus, a medicinal plant species used for production of the FDA-approved anticancer drug paclitaxel. …
Soil-Structure Modeling And Design Considerations For Offshore Wind Turbine Monopile Foundations, Wystan Carswell
Soil-Structure Modeling And Design Considerations For Offshore Wind Turbine Monopile Foundations, Wystan Carswell
Doctoral Dissertations
Offshore wind turbine (OWT) support structures account for 20-25% of the capital cost for offshore wind installations, making it essential to optimize the design of the tower, substructure, and foundation to the extent possible. This dissertation focuses on monopile foundations, as the vast majority (approximately 75%) of currently installed OWTs are supported by monopile structures. The objective of this dissertation is to provide information on the behavior of monopile support structures to better substantiate design and planning decisions and to provide a basis for reducing the structural material costs. In pursuit of these objectives, research is presented on the topics …
Evaluation Of Ferrate Preoxidation For Drinking Water Treatment, Joseph E. Goodwill
Evaluation Of Ferrate Preoxidation For Drinking Water Treatment, Joseph E. Goodwill
Doctoral Dissertations
Ferrate (Fe(IV)) has been proposed as a viable alternative for pre-oxidation in drinking water treatment (Jiang & Lloyd, 2002; Sharma, Kazama, Jiangyong, & Ray, 2005). The primary advantages of ferrate include a strong oxidation potential without the formation of halogenated by-products. In addition, the by-product of ferrate oxidation, ferric iron (Fe(III)), may have beneficial impacts on downstream particle destabilization and removal processes. Also, ferrate has disinfectant properties and may also provide pathogen inactivation in drinking water (Sharma et al., 2005). However, despite these advantages, there is a dearth of research experience that examines the implications of using ferrate for treating …
Privacy-Preserving Payments For Transportation Systems, Gesine Hinterwalder
Privacy-Preserving Payments For Transportation Systems, Gesine Hinterwalder
Doctoral Dissertations
The operation of our society heavily relies on high mobility of people. Not only our social life but also our economy and trade are built upon a system where people need to be able to move around easily. The costs for building and maintaining a suitable transportation infrastructure to satisfy those needs are high, and to charge users is thus a central requirement. This calls for well functioning payment systems satisfying the multitude of requirements that transportation systems impose on them. Electronic payment systems have many benefits over traditional cash payments as they are easy to maintain, can be more …
Skybridge: A New Nanoscale 3-D Computing Framework For Future Integrated Circuits, Mostafizur Rahman
Skybridge: A New Nanoscale 3-D Computing Framework For Future Integrated Circuits, Mostafizur Rahman
Doctoral Dissertations
Continuous scaling of CMOS has been the major catalyst in miniaturization of integrated circuits (ICs) and crucial for global socio-economic progress. However, continuing the traditional way of scaling to sub-20nm technologies is proving to be very difficult as MOSFETs are reaching their fundamental performance limits [1] and interconnection bottleneck is dominating IC operational power and performance [2]. Migrating to 3-D, as a way to advance scaling, has been elusive due to inherent customization and manufacturing requirements in CMOS architecture that are incompatible with 3-D organization. Partial attempts with die-die [3] and layer-layer [4] stacking have their own limitations [5]. We …
On Thermal Sensor Calibration And Software Techniques For Many-Core Thermal Management, Shiting Lu
On Thermal Sensor Calibration And Software Techniques For Many-Core Thermal Management, Shiting Lu
Doctoral Dissertations
The high power density of a many-core processor results in increased temperature which negatively impacts system reliability and performance. Dynamic thermal management applies thermal-aware techniques at run time to avoid overheating using temperature information collected from on-chip thermal sensors. Temperature sensing and thermal control schemes are two critical technologies for successfully maintaining thermal safety. In this dissertation, on-line thermal sensor calibration schemes are developed to provide accurate temperature information. Software-based dynamic thermal management techniques are proposed using calibrated thermal sensors. Due to process variation and silicon aging, on-chip thermal sensors require periodic calibration before use in DTM. However, the calibration …
Securing Network Processors With Hardware Monitors, Kekai Hu
Securing Network Processors With Hardware Monitors, Kekai Hu
Doctoral Dissertations
As an essential part of modern society, the Internet has fundamentally changed our lives during the last decade. Novel applications and technologies, such as online shopping, social networking, cloud computing, mobile networking, etc, have sprung up at an astonishing pace. These technologies not only influence modern life styles but also impact Internet infrastructure. Numerous new network applications and services require better programmability and flexibility for network devices, such as routers and switches. Since traditional fixed function network routers based on application specific integrated circuits (ASICs) have difficulty keeping pace with the growing demands of next-generation Internet applications, there is an …
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Doctoral Dissertations
Porous materials are of great importance in many fields due to their wide applications. An ongoing theme in this area is the tailoring of materials for specific applications. With a better understanding of the formation mechanisms, tailoring and controlling the pore structure may be achieved. The objective of this research is acquiring further understanding of the fundamental physics that govern the formation of these materials using molecular simulations. We are aiming to unravel the assembly process of silica porous materials using a semi-rigid silica tetrahedral model. This model together with reaction ensemble Monte Carlo simulations allows us to study the …
An Analysis Of Partial-Depth, Floating, Impermeable Guidance Structures For Downstream Fish Passage At Hydroelectric Facilities, Kevin Mulligan
An Analysis Of Partial-Depth, Floating, Impermeable Guidance Structures For Downstream Fish Passage At Hydroelectric Facilities, Kevin Mulligan
Doctoral Dissertations
Partial-depth, impermeable guidance structures (or guide walls) are used to enhance downstream passage effectiveness at a hydroelectric facility by actively guiding fish to a safe passage route (i.e. the bypass). Guide walls have been installed in a variety of ways and, like many fish passage devices, have resulted in variable efficiency rates. Currently, the most common type of installment is a steel panel guide wall attached to a floating boom. While less utilized than other guidance structure options (e.g. louvers and bar racks), guide walls have been gaining popularity, particularly within the Northwest United States. The aim of this dissertation …
Energy Optimizations For Smart Buildings And Smart Grids, Aditya K. Mishra
Energy Optimizations For Smart Buildings And Smart Grids, Aditya K. Mishra
Doctoral Dissertations
Modern buildings are heavy power consumers. For instance, of the total electricity consumed in the US, 75% is consumed in the residential and commercial buildings. This consumption is not evenly distributed over time. Typical consumption profile exhibits several peaks and troughs. The peakiness, in turn, dictates the electric grid's generation, transmission and distribution costs, and also the associated carbon emissions. This thesis discusses challenges involved in achieving the sustainability goals in buildings and electric grids. It investigates building and grid energy footprint optimization techniques to achieve the following goals: 1) making buildings energy efficient, 2) cutting building's electricity bills, 3) …
Virtual Antennas Using Metamaterials, Caglar D. Emiroglu
Virtual Antennas Using Metamaterials, Caglar D. Emiroglu
Doctoral Dissertations
Virtual antenna radiation at microwave frequencies using metamaterials is presented. Based on the transformation electromagnetics technique, the media embedding a physical antenna in a ground recess is designed such that the far-zone radiation pattern of a virtual antenna radiating above a flat conducting ground plane is reproduced. The antenna and a limited surrounding space above a ground plane is folded below the ground level, resulting in a physical antenna in a ground recess that is enclosed in transformation media. The electromagnetic specification of the media surrounding the physical antenna at the bottom of the recess is provided by a properly …
Design And Implementation Of An Economy Plane For The Internet, Xinming Chen
Design And Implementation Of An Economy Plane For The Internet, Xinming Chen
Doctoral Dissertations
The Internet has been very successful in supporting many network applications. As the diversity of uses for the Internet has increased, many protocols and services have been developed by the industry and the research community. However, many of them failed to get deployed in the Internet. One challenge of deploying these novel ideas in operational network is that the network providers need to be involved in the process. Many novel network protocols and services, like multicast and end-to-end QoS, need the support from network providers. However, since network providers are typically driven by business reasons, if they can not get …
Energy-Efficient Content Delivery Networks, Vimal Mathew
Energy-Efficient Content Delivery Networks, Vimal Mathew
Doctoral Dissertations
Internet-scale distributed systems such as content delivery networks (CDNs) operate hundreds of thousands of servers deployed in thousands of data center locations around the globe. Since the energy costs of operating such a large IT infrastructure are a significant fraction of the total operating costs, we argue for redesigning them to incorporate energy optimization as a first-order principle. We focus on CDNs and demonstrate techniques to save energy while meeting client-perceived service level agreements (SLAs) and minimizing impact on hardware reliability. Servers deployed at individual data centers can be switched off at low load to save energy. We show that …
Wind Power Capacity Value Metrics And Variability: A Study In New England, Frederick W. Letson
Wind Power Capacity Value Metrics And Variability: A Study In New England, Frederick W. Letson
Doctoral Dissertations
Capacity value is the contribution of a power plant to the ability of the power system to meet high demand. As wind power penetration in New England, and worldwide, increases so does the importance of identifying the capacity contribution made by wind power plants. It is critical to accurately characterize the capacity value of these wind power plants and the variability of the capacity value over the long term. This is important in order to avoid the cost of keeping extra power plants operational while still being able to cover the demand for power reliably. This capacity value calculation is …
Improving Sea-Surface Remote Sensing Of Ocean Wind Vectors By Scatterometers, Joseph W. Sapp
Improving Sea-Surface Remote Sensing Of Ocean Wind Vectors By Scatterometers, Joseph W. Sapp
Doctoral Dissertations
Though scatterometers have been used to sense global ocean surface wind vectors for over 40 years, there remain some significant shortcomings. The largest problems appear in retrieving the wind vector when the ocean is being driven by high wind speeds or when rain is present in the beam-illuminated volume. Geophysical model functions (GMFs) developed using data from high-wind events can improve retrievals at high wind speeds, but only if sufficient ground truth measurements exist in the scatterometer swath. Airborne scatterometers, such as the Imaging Wind and Rain Airborne Profiler (IWRAP) developed by the Microwave Remote Sensing Laboratory (MIRSL) at the …
On Applications Of Relational Data, Samamon Khemmarat
On Applications Of Relational Data, Samamon Khemmarat
Doctoral Dissertations
With the advances of technology and the popularity of the Internet, a large amount of data is being generated and collected. Much of these data is relational data, which describe how people and things, or entities, are related to one another. For example, data from sale transactions on e-commerce websites tell us which customers buy or view which products. Analyzing the known relationships from relational data can help us to discover knowledge that can benefit businesses, organizations, and our lives. For instance, learning the products that are commonly bought together allows businesses to recommend products to customers and increase their …
Physically Equivalent Intelligent Systems For Reasoning Under Uncertainty At Nanoscale, Santosh Khasanvis
Physically Equivalent Intelligent Systems For Reasoning Under Uncertainty At Nanoscale, Santosh Khasanvis
Doctoral Dissertations
Machines today lack the inherent ability to reason and make decisions, or operate in the presence of uncertainty. Machine-learning methods such as Bayesian Networks (BNs) are widely acknowledged for their ability to uncover relationships and generate causal models for complex interactions. However, their massive computational requirement, when implemented on conventional computers, hinders their usefulness in many critical problem areas e.g., genetic basis of diseases, macro finance, text classification, environment monitoring, etc. We propose a new non-von Neumann technology framework purposefully architected across all layers for solving these problems efficiently through physical equivalence, enabled by emerging nanotechnology. The architecture builds …
Morphology Evolution Mechanisms Of Low Band Gap Polymer-Based Photovoltaics, Sunzida Ferdous
Morphology Evolution Mechanisms Of Low Band Gap Polymer-Based Photovoltaics, Sunzida Ferdous
Doctoral Dissertations
An optimal nanoscale phase separation between the donor (generally, a conjugated polymer) and the acceptor (generally, a fullerene derivative) materials is one of the major requirements for obtaining high efficiency organic photovoltaic (OPV) device. Recent methods of controlling such nanostructure morphology in a bulkheterojunction (BHJ) OPV device involve addition of a small amount of solvent additive to the donor and acceptor solutions. The idea is to retain the acceptor materials into the solution for a longer period of time during the film solidification process, thus allowing the donor material to crystallize earlier. The ultimate morphology resulting from the solvent casting …
Effect Of Processing History And Material Properties On The Growth Of Wrinkle Amplitude, Yu-Cheng Chen
Effect Of Processing History And Material Properties On The Growth Of Wrinkle Amplitude, Yu-Cheng Chen
Doctoral Dissertations
Wrinkling has been employed by many organisms to form unique topography, such as fingerprints, gut villi, and surface of flower petal cells. The wavy wrinkle structure provides friction enhancement, surface area increase, optical, and wetting properties improvement. Inspired by Nature, scientists have created wrinkles synthetically and proposed numerous uses for them. However, wrinkling surfaces encounters limitations on achieving massive area and high amplitude-to-wavelength ratio (aspect ratio). The three phase contact line wrinkling technique creates well-defined wrinkles in a continuous fashion, and has great potential to scale-up for massive production. In addition to the velocity dependent adhesion force, we find the …
Process-Structure-Property Relationship In Ultra High Molecular Weight Polytetrafluoroethylene And Double Network Epoxies, Ranadip Ganguly
Process-Structure-Property Relationship In Ultra High Molecular Weight Polytetrafluoroethylene And Double Network Epoxies, Ranadip Ganguly
Doctoral Dissertations
The focus of this dissertation is to develop a fundamental understanding of process-structure-property relationship in two different classes of polymers: semi-crystalline Ultra High Molecular Weight Polytetrafluoroethylene (UHMWPTFE) and amorphous glassy double network (DN) epoxies. Conventional melt processing techniques such as extrusion and injection molding cannot be applied to UHMWPTFE due to its very high melt viscosity (1010-1011 poise). Therefore, UHMWPTFE is industrially processed by a modified metallurgy technology-sintering. However, the fundamental mechanism for UHMWPTFE sintering is unknown. Further, this process is highly time consuming, cost inefficient and hinders the recyclability of the material. The first part of …
Threat Analysis, Countermeaures And Design Strategies For Secure Computation In Nanometer Cmos Regime, Raghavan Kumar
Threat Analysis, Countermeaures And Design Strategies For Secure Computation In Nanometer Cmos Regime, Raghavan Kumar
Doctoral Dissertations
Advancements in CMOS technologies have led to an era of Internet Of Things (IOT), where the devices have the ability to communicate with each other apart from their computational power. As more and more sensitive data is processed by embedded devices, the trend towards lightweight and efficient cryptographic primitives has gained significant momentum. Achieving a perfect security in silicon is extremely difficult, as the traditional cryptographic implementations are vulnerable to various active and passive attacks. There is also a threat in the form of "hardware Trojans" inserted into the supply chain by the untrusted third-party manufacturers for economic incentives. Apart …
Quality Competition In Supply Chain Networks With Applications To Information Asymmetry, Product Differentiation, Outsourcing, And Supplier Selection, Dong Li
Doctoral Dissertations
The quality of the products produced and delivered in supply chain networks is essential for consumers' safety, well-being, and benefits, and for firms' profitability and reputation. However, because of the complexity of today's large-scale highly globalized supply chain networks, along with issues such as the growth in outsourcing and in global procurement, as well as the information asymmetry associated with quality, supply chain networks are more exposed to both domestic and international quality failures. In this dissertation, I contribute to the equilibrium and dynamic modeling and analysis of quality competition in supply chain networks under scenarios of information asymmetry, product …
A Computational Study On Extension Of Non-Contact Modulation Calorimetry, Xiao Ye
A Computational Study On Extension Of Non-Contact Modulation Calorimetry, Xiao Ye
Doctoral Dissertations
ABSTRACT A COMPUTATIONAL STUDY ON EXTENSION OF NON-CONTACT MODULATION CALORIMETRY May 2015 XIAO YE B.S., SOUTHEAST UNIVERSITY M.S., UNIVERSITY OF MASSACHUSETTS, AMHERST Ph. D., UNIVERSITY OF MASSACHUSETTS, AMHERST Directed by: Professor Robert W. Hyers Accurate thermophysical properties of high temperature metallic liquids are important for both industrial applications and scientific research. For the former, as predictive numerical simulations play an increasingly important role in pivotal industries, such as casting, welding and sintering, the lack of precise thermophysical properties, especially at high temperatures, hamper their further applications. On the other hand, from the stand point of basic metals physics, being able …
Investigation Of Hydration Induced Structural Rearrangements Of Poly(Lactic Acid), Omkar Vidyadhar Vyavahare
Investigation Of Hydration Induced Structural Rearrangements Of Poly(Lactic Acid), Omkar Vidyadhar Vyavahare
Doctoral Dissertations
A comprehensive analysis of microstructural changes associated with hydration of Poly(lactic acid) (PLA) and their effect on the macroscopic properties has been provided. Although water absorbed in PLA is extremely small (~0.5% by weight or 1 water molecule per 30 PLA monomer units), we found significant increase in the kinetics of physical aging and crystallization in the presence of water. The fact that water has such a strong effect on PLA structure is attributed to the polar nature of water, strong intermolecular interactions present in PLA and their changes in the hydrated state. Using vibrational spectroscopy, features associated with bound …
Vortex-Induced Vibration Of Structures With Broken Symmetry, Banafsheh Seyedaghazadeh
Vortex-Induced Vibration Of Structures With Broken Symmetry, Banafsheh Seyedaghazadeh
Doctoral Dissertations
A bluff body, i.e., an object with a blunt cross-section immersed in cross-flow forms an unstable wake, resulting in the formation of large-scale vortical structures, which induce unsteady forces on the body. If the body is flexible or flexibly mounted, vortex-induced vibration (VIV) results, which can have significant implications for a number of physical systems, from aeolian harps to power transmission lines, towing cables, undersea pipelines, drilling risers and mooring lines used to stabilize offshore floating platforms. VIV has been a major subject of research in recent years. The majority of these studies have focused on symmetric systems in which …
Mechanical And Electro-Mechanical Properties Of Crystalline Organic Semiconductors, Marcos A. Reyes-Martinez
Mechanical And Electro-Mechanical Properties Of Crystalline Organic Semiconductors, Marcos A. Reyes-Martinez
Doctoral Dissertations
The study of the physical properties of organic crystalline semiconductors has allowed the advent of a new generation of high-performance organic electronic devices. Exceptional charge-transport properties and recent developments in large-area patterning techniques make organic single crystals (OSCs) excellent candidates for their utilization in the next-generation of electronic technologies, including flexible and conformable organic thin-film devices. In spite of the profound knowledge of the structural and electrical properties of OSCs, knowledge of the mechanical properties and the effects of mechanical strain is almost non-existent. This dissertation aims to bring new understanding of the intrinsic mechanical properties and the effect of …
Synthesis And Biological Applications Of Heavy-Metal-Free Semiconductor Nanocrystals, Ying Qi
Synthesis And Biological Applications Of Heavy-Metal-Free Semiconductor Nanocrystals, Ying Qi
Doctoral Dissertations
Semiconductor nanocrystals, also called quantum dots (QDs), are an interesting class of materials exhibiting size-tunable optical properties. QDs are attractive for a variety of applications, such as biological sensing and imaging, high color definition display technologies, and photovoltaics. The most widely studied QDs are compound semiconductors of the type CdX and PbX (with X= S, Se, and Te). The absorption and fluorescence emission wavelengths of these QDs span the visible and near infrared (NIR) regions of the electromagnetic spectrum. However, the highly toxic heavy metals Cd and Pb contained in these materials are problematic for their widespread use in commercial …
Mechanics Of Helical And Fabric-Like Mesostructures From Polymer-Nanoparticle Hybrids, Jonathan T. Pham
Mechanics Of Helical And Fabric-Like Mesostructures From Polymer-Nanoparticle Hybrids, Jonathan T. Pham
Doctoral Dissertations
Hierarchical structures developed from nanoscale building blocks offer an excellent opportunity to control properties on all length scales, from the molecular level up to the macroscale. Many beautiful examples in Nature have demonstrated the significance of controlling geometry and mechanics on small length scales to control function on an organism-level, shown by the strength of bones, the toughness of a mollusk's shell, or the gecko's ability to climb walls. Inspired by stunning examples in both Nature and common man-made materials and structures, we assemble polymers and inorganic nanoparticles (NPs) with well-defined surface chemistry into long ribbons and fabric-like networks with …
Ultra-Thin Polymer Films And Hierarchical Composites: Processing And Mechanical Properties, Yujie Liu
Ultra-Thin Polymer Films And Hierarchical Composites: Processing And Mechanical Properties, Yujie Liu
Doctoral Dissertations
Properties and fabrications of ultra-thin polymer films and hierarchical composites are of great interest in packaging, electronics, separations, and other manufacturing fields. However, due to the inherently fragile nature of ultra-thin polymer films, measuring their properties has proven difficult. Additionally, variables controlling thin polymer patterns (e.g. substrate wetting property) and composites (weight percent of particulates in matrix) formation have not been fundamentally well understood. Within this spectrum, fundamental understanding of formation mechanisms of these patterns and composites are needed. Additionally, a new characterization technique is required to be able to measure the mechanical properties of fabricated composites and thin films. …