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Articles 79621 - 79650 of 196443

Full-Text Articles in Engineering

Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li Jan 2018

Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li

Electronic Theses and Dissertations

The observation of any atomic and molecular dynamics requires a probe that has a timescale comparable to the dynamics itself. Ever since the invention of laser, the temporal duration of the laser pulse has been incrementally reduced from several nanoseconds to just attoseconds. Picosecond and femtosecond laser pulses have been widely used to study molecular rotation and vibration. In 2001, the first single isolated attosecond pulse (1 attosecond = 10^-18 seconds.) was demonstrated. Since this breakthrough, "attoscience" has become a hot topic in ultrafast physics. Attosecond pulses typically have span between EUV to X-ray photon energies and sub-femtosecond pulse duration. …

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Graphene Induced Formation Of Nanostructures In Composites, Chen Shen Jan 2018

Graphene Induced Formation Of Nanostructures In Composites, Chen Shen

Electronic Theses and Dissertations

Graphene induced nanostructures in graphene-based composites and the performance of these composites have been explored in this study. For the metallic nanoparticles decorated graphene aerogels composites, the fabrication of hierarchically structured, reduced graphene oxide (rGO) aerogels with heavily metallic nanoparticles was realized. Higher loading of palladium nanoparticles in graphene aerogels leads to improved hydrogen gas sensing performance. For polymer derived ceramics (PDCs) composites with anisotropic electrical properties, the fabrication of composites was realized by embedding anisotropic reduced graphene oxide aerogels (rGOAs) into the PDCs matrix. Raman spectroscopy and X-ray diffraction studies of PDCs composites with and without graphene indicate that …

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Effect Of Nonclassical Optical Turbulence On A Propagating Laser Beam, Melissa Beason Jan 2018

Effect Of Nonclassical Optical Turbulence On A Propagating Laser Beam, Melissa Beason

Electronic Theses and Dissertations

Theory developed for the propagation of a laser beam through optical turbulence generally assumes that the turbulence is both homogeneous and isotropic and that the associated spectrum follows the classical Kolmogorov spectral power law of κ-11/3. If the atmosphere deviates from these assumptions, beam statistics such as mean intensity, correlation, and scintillation index could vary significantly from mathematical predictions. This work considers the effect of nonclassical turbulence on a propagated beam. Namely, anisotropy of the turbulence and a power law that deviates from κ-11/3. A mathematical model is developed for the scintillation index of a Gaussian beam propagated through nonclassical …

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Assessment Of Microstructure And Mechanical Behavior Of Materials And Phases Observed In Low-Enriched Uranium Monolithic Fuel Plates After Fabrication, Ryan Newell Jan 2018

Assessment Of Microstructure And Mechanical Behavior Of Materials And Phases Observed In Low-Enriched Uranium Monolithic Fuel Plates After Fabrication, Ryan Newell

Electronic Theses and Dissertations

Low enriched uranium (LEU) fuels are being developed to reduce the use of highly enriched uranium in power generation to reduce proliferation risks. Challenges arise in providing sufficient fissile U in LEU without reactor redesign. As such, a novel monolithic fuel plate design employs LEU alloyed with 10 wt. % Mo. Throughout fabrication of these fuel plates, metallurgical transformations and reactions take place as a result of elevated temperatures during processing. The transformations include decomposition of the metastable body-centered cubic γ phase in the fuel and metallurgical interactions at interfaces between fuel plate components. This work aims to provide further …

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Probing The Effects Of Substrate Stiffness On Astrocytes Mechanics, Ariege Bizanti Jan 2018

Probing The Effects Of Substrate Stiffness On Astrocytes Mechanics, Ariege Bizanti

Electronic Theses and Dissertations

Astrocytes are among the most functionally diverse population of cells in the central nervous system (CNS) as they are essential to many important neurological functions including maintaining brain homeostasis, regulating the blood brain barrier, and preventing build-up of toxic substances within the brain, for example. Astrocyte importance to brain physiology and pathology has inspired a host of studies focused on understanding astrocyte behavior primarily from a biological and chemical perspective. However, a clear understanding of astrocyte dysfunction and their link to disease has been hampered by a lack of knowledge of astrocyte behavior from a biomechanical perspective. Furthermore, astrocytes (and …

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The Effect Of Martensite-Fractions Assumptions In Shape Memory Alloy Springs, Christian Vazquez Jan 2018

The Effect Of Martensite-Fractions Assumptions In Shape Memory Alloy Springs, Christian Vazquez

Electronic Theses and Dissertations

This research addresses various models of a spring-mass system that uses a spring made of a shape memory alloy (SMA). The system model describes the martensite fractions, which are values that describe an SMA's crystalline phases, via differential equations. The model admits and this thesis contrasts two commonly used but distinct assumptions: a homogeneous case where the martensite fractions are constant throughout the spring's cross section, and a bilinear case where the evolution of the martensite fractions only occurs beyond some critical radius. While previous literature has developed a model of the system dynamics under the homogeneous assumption using the …

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Decoupling Of Second-Order Linear Systems By Isospectral Transformation, Daniel Kawano, Rubens Salsa, Fai Ma Jan 2018

Decoupling Of Second-Order Linear Systems By Isospectral Transformation, Daniel Kawano, Rubens Salsa, Fai Ma

Faculty Publications - Mechanical Engineering

No abstract provided.

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Slowdown Of Surface Diffusion During Early Stages Of Bacterial Colonization, T. Vourc'h, H. Peerhossaini, J. Leopoldes, A. Mejean, F. Chauvat, C. Cassier-Chauvat Jan 2018

Slowdown Of Surface Diffusion During Early Stages Of Bacterial Colonization, T. Vourc'h, H. Peerhossaini, J. Leopoldes, A. Mejean, F. Chauvat, C. Cassier-Chauvat

Civil and Environmental Engineering Publications

We study the surface diffusion of the model cyanobacterium Synechocystis sp. PCC6803 during the incipient stages of cell contact with a glass surface in the dilute regime. We observe a twitching motility with alternating immobile tumble and mobile run periods, resulting in a normal diffusion described by a continuous-time random walk with a coefficient of diffusion D. Surprisingly, D is found to decrease with time down to a plateau. This is observed only when the cyanobacterial cells are able to produce released extracellular polysaccharides, as shown by a comparative study between the wild-type strain and various polysaccharides-depleted mutants. The analysis …

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Plastic Hinge Relocation In Reinforced Concrete Beams Using Cu-Al-Mn Sma Bars, S. Pareek, Maged Youssef, Mohamed E. Meshaly, Y. Araki Jan 2018

Plastic Hinge Relocation In Reinforced Concrete Beams Using Cu-Al-Mn Sma Bars, S. Pareek, Maged Youssef, Mohamed E. Meshaly, Y. Araki

Civil and Environmental Engineering Publications

costs. The use of Ni-Ti superelastic shape memory alloy (SMA) constitutes a considerable portion of this research. Cu-Al-Mn superelastic SMA has been recently developed to eliminate the high cost of Ni-Ti SMA, as well as, to have better machining characteristics. This paper explores the use of Cu-Al-Mn SMA bars to relocate the plastic hinge of concrete beams through an experimental–numerical study. The cyclic performance of four beams was examined. The first was reinforced with steel bars and the remaining three were reinforced with combination of SMA and steel bars. The location of the SMA bars was different for each of …

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Assessment Of The Flexural Behavior Of Reinforced Concrete Beams Strengthened With Concrete Jackets, M. Monir A. Alhadid, Maged Youssef Jan 2018

Assessment Of The Flexural Behavior Of Reinforced Concrete Beams Strengthened With Concrete Jackets, M. Monir A. Alhadid, Maged Youssef

Civil and Environmental Engineering Publications

Analysis of continuous jacketed Reinforced Concrete (RC) beams requires accounting for the nonlinear behavior of the interface and the materials as well as redistribution of moments. This kind of analysis is complex and require an advanced level of knowledge and experience to perform. Engineers need simplified yet robust tools to practically predict the actual behavior of jacketed RC beams. In the current practice, slip is neglected in the analysis and monolithic behavior is assumed for the jacketed section, which result in higher estimates of stiffness and/or capacity. This paper provides a simplified method to analyze continuous jacketed RC beams taking …

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Seismic Fragility Assessment Of Superelastic Shape Memory Alloy Reinforced Concrete Shear Walls, Emad A. Abraik, Maged A. Youssef Jan 2018

Seismic Fragility Assessment Of Superelastic Shape Memory Alloy Reinforced Concrete Shear Walls, Emad A. Abraik, Maged A. Youssef

Civil and Environmental Engineering Publications

Mitigation of seismic damage can be achieved through self-centering techniques. One of the potential techniques involves the use of Superelastic Shape Memory Alloy (SE-SMA) bars in Reinforced Concrete (RC) structures. This study explores the use of such bars in the plastic-hinge regions of RC walls. The seismic performance and vulnerability of SE‑SMA RC walls of ten- and twenty-story buildings are analytically assessed using fragility curves. The maximum inter-story drift, residual drift, and fragility are evaluated using multi strip analysis. The results clearly demonstrate the superior seismic performance of SE-SMA RC walls as compared to steel RC walls.

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Seismic Performance Of Modular Steel Frames Equipped With Shape Memory Alloy Braces, Papia Sultana, Maged A. Youssef Jan 2018

Seismic Performance Of Modular Steel Frames Equipped With Shape Memory Alloy Braces, Papia Sultana, Maged A. Youssef

Civil and Environmental Engineering Publications

The demand for modular steel buildings (MSBs) has increased because of the improved quality, fast on-site installation, and lower cost of construction. Steel braced frames are usually utilized to form the lateral load resisting system of MSBs. During earthquakes, the seismic energy is dissipated through yielding of the components of the braced frames, which results in residual drifts. Excessive residual drifts complicate the repair of damaged structures or render them irreparable. Researchers have investigated the use of superelastic shape memory alloys (SMAs) in steel structures to reduce the seismic residual deformations. This study explores the potential of using SMA braces …

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Numerical Modeling And Control Of Solids Separation Using Continuously Moving Fine Mesh Filters, Anthony Sherratt, Christopher T. Degroot, Anthony G. Straatman, Domenico Santoro Jan 2018

Numerical Modeling And Control Of Solids Separation Using Continuously Moving Fine Mesh Filters, Anthony Sherratt, Christopher T. Degroot, Anthony G. Straatman, Domenico Santoro

Mechanical and Materials Engineering Publications

No abstract provided.

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The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet, Anthony G. Straatman Jan 2018

The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet, Anthony G. Straatman

Mechanical and Materials Engineering Publications

No abstract provided.

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A Porous Media Model Of Alveolar Duct Flow In The Human Lung, Anthony G. Straatman, Christopher T. Degroot Jan 2018

A Porous Media Model Of Alveolar Duct Flow In The Human Lung, Anthony G. Straatman, Christopher T. Degroot

Mechanical and Materials Engineering Publications

No abstract provided.

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Energy Slices: Benchmarking With Time Slicing, Katarina Grolinger, Hany F. Elyamany, Wilson Higashino, Miriam Am Capretz, Luke Seewald Jan 2018

Energy Slices: Benchmarking With Time Slicing, Katarina Grolinger, Hany F. Elyamany, Wilson Higashino, Miriam Am Capretz, Luke Seewald

Electrical and Computer Engineering Publications

Benchmarking makes it possible to identify low-performing buildings, establishes a baseline for measuring performance improvements, enables setting of energy conservation targets, and encourages energy savings by creating a competitive environment. Statistical approaches evaluate building energy efficiency by comparing measured energy consumption to other similar buildings typically using annual measurements. However, it is important to consider different time periods in benchmarking because of differences in their consumption patterns. For example, an office can be efficient during the night, but inefficient during operating hours due to occupants’ wasteful behavior. Moreover, benchmarking studies often use a single regression model for different building categories. …

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Evaluating Flexibility Metrics On Simple Temporal Networks With Reinforcement Learning, Hamzah I. Khan Jan 2018

Evaluating Flexibility Metrics On Simple Temporal Networks With Reinforcement Learning, Hamzah I. Khan

HMC Senior Theses

Simple Temporal Networks (STNs) were introduced by Tsamardinos (2002) as a means of describing graphically the temporal constraints for scheduling problems. Since then, many variations on the concept have been used to develop and analyze algorithms for multi-agent robotic scheduling problems. Many of these algorithms for STNs utilize a flexibility metric, which measures the slack remaining in an STN under execution. Various metrics have been proposed by Hunsberger (2002); Wilson et al. (2014); Lloyd et al. (2018). This thesis explores how adequately these metrics convey the desired information by using them to build a reward function in a reinforcement learning …

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Addressing Clay Mineralogy Effects On Performance Of Chemically Stabilized Expansive Soils Subjected To Seasonal Wetting And Drying, Bhaskar C.S. Chittoori, Anand J. Puppala, Aravind Pedarla Jan 2018

Addressing Clay Mineralogy Effects On Performance Of Chemically Stabilized Expansive Soils Subjected To Seasonal Wetting And Drying, Bhaskar C.S. Chittoori, Anand J. Puppala, Aravind Pedarla

Civil Engineering Faculty Publications and Presentations

Premature failures in chemically stabilized expansive soils cause millions of dollars in maintenance and repair costs. One of the reasons for these failures is the inability of existing stabilization design guidelines to consider the complex interactions between clay minerals and the stabilizers. It is vital to understand these complex interactions, as they are responsible for the strength improvement and swell/shrink reduction in these soils, in turn affecting the overall health of the infrastructure. Hence, this research study examined the longevity of chemically stabilized expansive soils subjected to wetting/drying conditions with a major focus on clay mineralogy. Eight different natural soils …

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Unified Approach To Sustainability, Resiliency And Risk Assessments, Thomas Robbins, Bhaskar Chittoori, Amit Gajurel, Robert Hamilton Jan 2018

Unified Approach To Sustainability, Resiliency And Risk Assessments, Thomas Robbins, Bhaskar Chittoori, Amit Gajurel, Robert Hamilton

Civil Engineering Faculty Publications and Presentations

Generally, researchers consider sustainability and resiliency aspects of infrastructure projects independently, without considering the relationship that exists between them. Unified approaches that combine sustainability, resiliency, and analyze risk are very minimal. This paper proposes a unified approach to assessing sustainability, resiliency, and risk for infrastructure via evaluating the performance of a tailings dam under various earthquake magnitudes. A tailings dam is typically in operation for many years, which means they may have a direct impact on the local environment, society, and economy. Due to the extended life of the dam, the probability of a major event occurring that could negatively …

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Compound Glass Microsphere Resonator Devices, Jibo Yu, Elfed Lewis, Gerald Farrell, Pengfei Wang Jan 2018

Compound Glass Microsphere Resonator Devices, Jibo Yu, Elfed Lewis, Gerald Farrell, Pengfei Wang

Articles

In recent years, compound glass microsphere resonator devices have attracted increasing interest and have been widely used in sensing, microsphere lasers, and nonlinear optics. Compared with traditional silica resonators, compound glass microsphere resonators have many significant and attractive properties, such as high-Q factor, an ability to achieve high rare earth ion, wide infrared transmittance, and low phonon energy. This review provides a summary and a critical assessment of the fabrication and the optical characterization of compound glasses and the related fabrication and applications of compound glass microsphere resonators.

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Detecting Clickbait: Here’S How To Do It, Christopher Brogly, Victoria Rubin Jan 2018

Detecting Clickbait: Here’S How To Do It, Christopher Brogly, Victoria Rubin

Data and Test Instruments

Automatic clickbait detection is a relatively novel task in natural language processing (NLP) and machine learning (ML). “Clickbait” is a hyperlink created primarily to attract attention to its target content. This article introduces a binary classifier, the Language and Information Technology Research Lab (LiT.RL, pronounced “literal”) Clickbait Detector, which automatically distinguishes clickbait from nonclickbait. We used NLP and ML for 38 textual features, contrasting clickbait with “headlinese.” When tested on 11,000 hyperlinks, it achieves 94 per cent accuracy using a support vector machine. Integrated with the LiT.RL News Verification Browser, a downloadable stand-alone research tool, the Clickbait Detector user interface …

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Ua66/1/1 Spring "New"Sletter, Issue 16, Wku Ogden College Of Science & Engineering Jan 2018

Ua66/1/1 Spring "New"Sletter, Issue 16, Wku Ogden College Of Science & Engineering

WKU Administration Documents

Newsletter created by and about WKU Ogden College of Science & Engineering.

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Aerodynamic Design And Analysis Of A Large-Scale Stall-Regulated H-Type Vertical Axis Wind Turbine For An Offshire Floating Installation, Brian Peter Hand Jan 2018

Aerodynamic Design And Analysis Of A Large-Scale Stall-Regulated H-Type Vertical Axis Wind Turbine For An Offshire Floating Installation, Brian Peter Hand

PhDs

Wind energy has witnessed a consistent expansion over the past decade, especially with the move to offshore installation. There is an increasing need to further exploit superior offshore wind resources, which is pushing multi-megawatt wind turbines into deeper water locations where the current popular horizontal axis wind turbine configuration is not entirely suitable. In particular, there has been a renewed interest in the vertical axis wind turbine (VAWT) configuration due to its inherent design attributes for an offshore floating application and also its potential to provide a significant reduction in the system cost of energy. However, challenges still remain as …

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Energising Dairy Decisions, John Upton, Philip Shine, Michael Breen, Michael D. Murphy Jan 2018

Energising Dairy Decisions, John Upton, Philip Shine, Michael Breen, Michael D. Murphy

Publications

A new tool developed by Teagasc researchers easily and quickly allows dairy farmers to see their energy usage and evaluate how renewable sources could decrease energy costs.

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The Effect Of Cognitive Limb Embodiment On Vascular Physiological Response, Hala Elsir Mustafa Osman Jan 2018

The Effect Of Cognitive Limb Embodiment On Vascular Physiological Response, Hala Elsir Mustafa Osman

ETD Archive

The rubber hand illusion (RHI) is a visual-tactile perceptual illusion commonly used to study body ownership. In this paradigm, a rubber hand is positioned in front of a participant, and the person’s real hand is hidden from sight behind a barrier. When the real hand and the rubber hand are stroked synchronously, individuals perceive the rubber hand as if it were their own; it becomes “embodied.” This illusory experience of body ownership is associated with multimodal integration of touch and vision. From these visual-tactile-cognitive mechanisms, we establish that our hands belong to us when what we see matches what we …

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Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun Jan 2018

Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun

ETD Archive

The objective of this dissertation research is to use Kinect sensor, a motion sensing input device, to develop an integrated software system that can be used for tracking non-compliant activity postures of consented health-care workers for assisting the workers' compliance to best practices, allowing individualized gestures for privacy-aware user registration, movement recognition using rule-based algorithm, real-time feedback, and exercises data collection. The research work also includes developing a graphical user interface and data visualization program for illustrating statistical information for administrator, as well as utilizing cloud based database system used for data resource.

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Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban Jan 2018

Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban

ETD Archive

Currently there is a large interest in the use of more efficient means of propulsion in long term missions due to the costs and difficulties associated with placing and maintaining the needed fuel for conventional chemical systems in orbit. Mass reduction of upper stages will return large returns due to the great reduction in required lower stage fuel. Due to these factors, alternatives are undergoing active research, though this paper is concerned with the area of electrical propulsion. Electric propulsion is broadly defined as propulsion where the energization of the exhaust occurs via application of electromagnetic fields as opposed to …

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Limits Of Small Scale Pressure Swing Adsorption, Aaron A. Moran Jan 2018

Limits Of Small Scale Pressure Swing Adsorption, Aaron A. Moran

ETD Archive

Portable or small scale pressure swing adsorption (PSA) systems have gained increasing popularity in both industry and literature due to the commercial success of personal oxygen concentrators (POCs). While these processes have much in common with larger PSA systems, significant differences exist that make understanding process limitations difficult. These include faster cycle times, smaller adsorbent particles, and a reduced column size. Macropore diffusion is traditionally assumed to control the mass transfer rate in columns packed with zeolite particles in an oxygen production process. While numerous studies have confirmed this assumption for the particle size used in industrial size PSA processes, …

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Characterizing The Effects Of High-Intensity Exercise On Balance And Gait Under Dual-Task Conditions In Parkinson’S Disease, El Iva Baron Jan 2018

Characterizing The Effects Of High-Intensity Exercise On Balance And Gait Under Dual-Task Conditions In Parkinson’S Disease, El Iva Baron

ETD Archive

Parkinson’s disease (PD) is a neurodegenerative disorder, characterized by four cardinal motor symptoms including bradykinesia, tremor, rigidity, and postural instability, and non-motor symptoms including cognitive impairment. Daily activities, such as walking and maintaining balance, are impacted due to impairments in motor function, and are further exacerbated with the addition of cognitive loading, or dual-tasking (DT). High-intensity exercise has demonstrated centrally-mediated improvements of PD symptoms, with additional positive effects on overall health. The goal of this project was to identify changes in dynamic balance recovery and gait function under conditions with and without increased cognitive load after a high-intensity exercise intervention …

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Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat Jan 2018

Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat

ETD Archive

Recent powered lower-limb prosthetic and orthotic (P/O) devices aim to restore legged mobility for persons with an amputation or spinal cord injury. Though various control strategies have been proposed for these devices, specifically finite-state impedance controllers, natural gait mechanics are not usually achieved. The goal of this project was to invent a biologically-inspired controller for powered P/O devices. We hypothesize that a more muscle-like actuation system, including spinal reflexes and vestibular feedback, can achieve able-bodied walking and also respond to outside perturbations. The outputs of the Virtual Muscle Reflex (VMR) controller are joint torque commands, sent to the electric motors …

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