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2018

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Articles 6451 - 6480 of 9993

Full-Text Articles in Engineering

Understanding How, Where And How Much Freight Flows Using 2012 Commodity Flow Survey Data, Nowreen Keya Jan 2018

Understanding How, Where And How Much Freight Flows Using 2012 Commodity Flow Survey Data, Nowreen Keya

Electronic Theses and Dissertations

In recent years, with increased economic globalization, growing e-commerce and internet based shopping, freight movement patterns are undergoing a transformative change. The shipment size distribution is moving towards a higher share of smaller size shipments affecting transportation mode and vehicle type requirements. In addition, freight transportation mode is closely affected by the destination location (and its attributes). In our dissertation, we contribute to freight research by developing a comprehensive framework to examine the how, where and how much freight flows in US. Specifically, we study the following dimensions of freight flow: (1) transportation mode, (2) mode and shipment weight choice …

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Nondestructive Testing Methods Aided Via Numerical Computation Models For Various Critical Aerospace Power Generation Systems, Peter Warren Jan 2018

Nondestructive Testing Methods Aided Via Numerical Computation Models For Various Critical Aerospace Power Generation Systems, Peter Warren

Electronic Theses and Dissertations

A current critical necessity for all industries which utilize various equipment that operates in high temperature and extreme environments, is the ability to collect and analyze data via non destructive testing (NDT) methods. Operational conditions and material health must be constantly monitored if components are to be implemented precisely to increase the overall performance and efficiency of the process. Currently in both aerospace and power generation systems there are many methods that are being employed to gather several necessary properties and parameters of a given system. This work will focus primarly on two of these NDT methods, with the ultimate …

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Influence Of Transverse Slot Jet On Premixed Flame Acceleration, Dylan Tarrant Jan 2018

Influence Of Transverse Slot Jet On Premixed Flame Acceleration, Dylan Tarrant

Electronic Theses and Dissertations

This work aims to identify the key flow parameters that influence flame acceleration in a semi-confined square channel. A transverse fluidic jet was used as an active flow blockage mechanism and to introduce turbulence into the propagating flame. Three experimental parameters were used to examine the relative influence of (1) mixture reactivity defined here as system equivalence ratio (SER), (2) jet mixture composition (JMC), and the momentum ratio (MR) on the acceleration of laminar premixed methane flame. High-speed PIV and schlieren photography were utilized to characterize the instantaneous flow-field conditions throughout the flame-jet interaction. Using these diagnostic techniques, flame front …

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Artificial Neuron Using Mos2/Graphene Threshold Switching Memristor, Hirokjyoti Kalita Jan 2018

Artificial Neuron Using Mos2/Graphene Threshold Switching Memristor, Hirokjyoti Kalita

Electronic Theses and Dissertations

With the ever-increasing demand for low power electronics, neuromorphic computing has garnered huge interest in recent times. Implementing neuromorphic computing in hardware will be a severe boost for applications involving complex processes such as pattern recognition. Artificial neurons form a critical part in neuromorphic circuits, and have been realized with complex complementary metal–oxide–semiconductor (CMOS) circuitry in the past. Recently, insulator-to-metal-transition (IMT) materials have been used to realize artificial neurons. Although memristors have been implemented to realize synaptic behavior, not much work has been reported regarding the neuronal response achieved with these devices. In this work, we study the IMT in …

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Different Facial Recognition Techniques In Transform Domains, Taif Al Obaidi Jan 2018

Different Facial Recognition Techniques In Transform Domains, Taif Al Obaidi

Electronic Theses and Dissertations

The human face is frequently used as the biometric signal presented to a machine for identification purposes. Several challenges are encountered while designing face identification systems. The challenges are either caused by the process of capturing the face image itself, or occur while processing the face poses. Since the face image not only contains the face, this adds to the data dimensionality, and thus degrades the performance of the recognition system. Face Recognition (FR) has been a major signal processing topic of interest in the last few decades. Most common applications of the FR include, forensics, access authorization to facilities, …

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Cost And Environmental Impacts Of Leachate Nitrogen/Phosphorus Management Approaches, Alaa Alanezi Jan 2018

Cost And Environmental Impacts Of Leachate Nitrogen/Phosphorus Management Approaches, Alaa Alanezi

Electronic Theses and Dissertations

Landfill leachate is a challenging wastewater to discharge into municipal wastewater treatment plants (WWTPs), the most common approach for leachate management, due to the presence of contaminants that may affect the performance of the treatment plant. Treatment, disposal, and transportation of leachate are expensive and therefore a concern. Currently, sidestream treatment is becoming increasingly common in WWTPs prior to returning the liquid to the plant influent. For this research, a new treatment scheme is introduced combining centrate and leachate to reduce contaminants, recover phosphorous and nitrogen through struvite precipitation, and reduce energy requirements through anaerobic ammonium oxidation (Anammox). By combining …

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Safety Investigation Of Traffic Crashes Incorporating Spatial Correlation Effects, Khalid Alkahtani Jan 2018

Safety Investigation Of Traffic Crashes Incorporating Spatial Correlation Effects, Khalid Alkahtani

Electronic Theses and Dissertations

One main interest in crash frequency modeling is to predict crash counts over a spatial domain of interest (e.g., traffic analysis zones (TAZs)). The macro-level crash prediction models can assist transportation planners with a comprehensive perspective to consider safety in the long-range transportation planning process. Most of the previous studies that have examined traffic crashes at the macro-level are related to high-income countries, whereas there is a lack of similar studies among lower- and middle-income countries where most road traffic deaths (90%) occur. This includes Middle Eastern countries, necessitating a thorough investigation and diagnosis of the issues and factors instigating …

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Categorical Range Reporting In 2d Using Wavelet Tree, Swathi Kanthareddy Sumithra Jan 2018

Categorical Range Reporting In 2d Using Wavelet Tree, Swathi Kanthareddy Sumithra

Electronic Theses and Dissertations

The research involved optimizing the space and bounding the output time by the output size in categorical range reporting of points within the given rectangle query Q in two dimension using wavelet trees and range counting. The time taken to report those points and space to tore n points in set S can be done using wavelet tree and range counting. Consider set S consisting of n points in two-dimension. An orthogonal range reporting query rectangle Q = [a,b] x [c,d] on set S is sent to report the set of points in S which interacts with the query rectangle[Q]. …

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Managing Io Resource For Co-Running Data Intensive Applications In Virtual Clusters, Dan Huang Jan 2018

Managing Io Resource For Co-Running Data Intensive Applications In Virtual Clusters, Dan Huang

Electronic Theses and Dissertations

Today Big Data computer platforms employ resource management systems such as Yarn, Torque, Mesos, and Google Borg to enable sharing the physical computing among many users or applications. Given virtualization and resource management systems, users are able to launch their applications on the same node with low mutual interference and management overhead on CPU and memory. However, there are still challenges to be addressed before these systems can be fully adopted to manage the IO resources in Big Data File Systems (BDFS) and shared network facilities. In this study, we mainly study on three IO management problems systematically, in terms …

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Simultaneous Measurement Of Isotope-Free Tracer And Interdiffusion Coefficients In Sandwich Type Diffusion Couples, Esin Schulz Jan 2018

Simultaneous Measurement Of Isotope-Free Tracer And Interdiffusion Coefficients In Sandwich Type Diffusion Couples, Esin Schulz

Electronic Theses and Dissertations

The experimental determination of the tracer or self-diffusion coefficient as a function of composition can be quite burdensome in alloys since separate measurements must be carried out for each alloy composition. A new formalism recently developed by I.V. Belova, N.S. Kulkarni, Y.H. Sohn and G.E. Murch, based on linear response theory combined with the Boltzmann–Matano method allows determination of tracer and interdiffusion coefficients simultaneously from a single, isotope-free solid to solid diffusion couple experiment. In this study, for the first time, an experimental investigation with an analytical approach based on the new formalism has been carried out in the binary …

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A Localized Blended Rbf Collocation Method For Effective Shock Capturing, Michael Harris Jan 2018

A Localized Blended Rbf Collocation Method For Effective Shock Capturing, Michael Harris

Electronic Theses and Dissertations

Solving partial differential equations (PDEs) can require numerical methods, especially for non-linear problems and complex geometry. Common numerical methods used today are the finite difference method (FDM), finite element method (FEM) and the finite volume method (FVM). These methods require a mesh or grid before a solution is attempted. Developing the mesh can require expensive preprocessing time and the quality of the mesh can have major effects on the solution. In recent years, meshless methods have become a research interest due to the simplicity of using scattered data points. Many types of meshless methods exist stemming from the spectral or …

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Flutter Stability Of Shrouded Turbomachinery Cascades With Nonlinear Frictional Damping, Alex Torkaman Jan 2018

Flutter Stability Of Shrouded Turbomachinery Cascades With Nonlinear Frictional Damping, Alex Torkaman

Electronic Theses and Dissertations

Prediction of flutter in shrouded turbomachinery cascades is difficult due to i) coupling of aerodynamic drivers and structural dynamics of the cascade through shrouds, and ii) presence of nonlinear dry friction damping as a result of relative motion between adjacent shrouds. An analytical framework is developed in this dissertation to determine flutter stability of shrouded cascades with consideration of friction damping. This framework is an extension to the well-established energy method, and it includes all contributing factors affecting stability of the cascade such as aerodynamic excitation and the stabilizing effects of dry friction damping caused by nonlinear contact forces between …

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Evaluation And Augmentation Of Traffic Data From Private Sector And Bluetooth Detection System On Arterials, Yaobang Gong Jan 2018

Evaluation And Augmentation Of Traffic Data From Private Sector And Bluetooth Detection System On Arterials, Yaobang Gong

Electronic Theses and Dissertations

Traffic data are essential for public agencies to monitor the traffic condition of the roadway network in real-time. Recently, public agencies have implemented Bluetooth Detection Systems (BDS) on arterials to collect traffic data and purchased data directly from private sector vendors. However, the quality and reliability of the aforementioned two data sources are subject to rigorous evaluation. The thesis presents a study utilizing high-resolution GPS trajectories to evaluate data from HERE, one of the private sector data vendors, and BDS of arterial corridors in Orlando, Florida. The results showed that the accuracy and reliability of BDS data are better than …

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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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Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon Jan 2018

Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon

Electronic Theses and Dissertations

Laser additive manufacturing (LAM) is an emerging technology capable of fabricating complex geometries not possibly made by investment casting methods for gas turbine applications. LAM techniques consist of building parts in a layer-by-layer process by selectively melting metal powders. In the present study, a mock leading edge segment of a turbine blade fabricated by LAM of Inconel 718 powders is investigated. For this particular design, the traditional showerhead film cooling holes have been replaced by two strips containing engineered-porous regions with the purpose of simulating the effect of transpiration cooling. Transpiration cooling has been considered a promising external convective cooling …

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Evaluating The Integration Of Chlorine Dioxide Into A Coagulation, Sedimentation, And Filtration Process Treating Surface Water, Martin Coleman Jan 2018

Evaluating The Integration Of Chlorine Dioxide Into A Coagulation, Sedimentation, And Filtration Process Treating Surface Water, Martin Coleman

Electronic Theses and Dissertations

Methods of optimizing the coagulation, flocculation, sedimentation, and filtration (CSF) process at a conventional surface water treatment plant (WTP) were conducted to investigate opportunities for the reduction of disinfection by-product (DBP) precursor material. The research had two primary components: (1) optimize coagulant dosage and associated operating pH and (2) investigate pretreatment oxidation with chlorine dioxide (ClO2) and potassium permanganate (KMnO4). To accomplish the first component, jar tests were conducted at various pH and aluminum sulfate (alum) dosages to model current and potential treatment conditions during the CSF process at a WTP. Isopleths were developed to examine the removal efficiencies of …

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Accommodating Exogenous Variable And Decision Rule Heterogeneity In Discrete Choice Models: Application To Bicyclist Route Choice, Bibhas Dey Jan 2018

Accommodating Exogenous Variable And Decision Rule Heterogeneity In Discrete Choice Models: Application To Bicyclist Route Choice, Bibhas Dey

Electronic Theses and Dissertations

The thesis contributes to our understanding of incorporating heterogeneity in discrete choice models with respect to exogenous variables and decision rules. Specifically, we evaluate latent segmentation based mixed models that allow for segmenting population based on decision rules while also incorporating unobserved heterogeneity within the segment level decision rule models. In our analysis, we choose to consider the random utility framework along with random regret minimization approach. Further, instead of assuming the number of segments (as 2), we conduct an exhaustive exploration with multiple segments across the two decision rules. Within each segment we also allow for unobserved heterogeneity. The …

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Interplay Of Molecular And Nanoscale Behaviors In Biological Soft Matter, Nicholas Ciaffone Jan 2018

Interplay Of Molecular And Nanoscale Behaviors In Biological Soft Matter, Nicholas Ciaffone

Electronic Theses and Dissertations

The complexity of biological soft matter at the sub-micrometer level is fundamentally correlated to the functionalities at the larger scale. Reflecting the level of heterogeneities in the properties of systems remains challenging when probing small scales, due to the mismatch between the area surveyed with the tools offering nanoscale resolution, such as atomic force microscopy (AFM), and the scale of natural variations inherent to biology. Hence, to understand the physiological and mechanical alterations that occur within a single cell relative to a cell population, a multiscale approach is necessary. In this work we show that it is possible to observe …

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The Relationship Between Agile Project Management And Project Success Outcomes, Thomas Bergmann Jan 2018

The Relationship Between Agile Project Management And Project Success Outcomes, Thomas Bergmann

Electronic Theses and Dissertations

Agile project management (APM) has recently emerged as a new approach to managing complex projects. Some experts believe that APM will become the standard project management approach used in the 21st century. However, thus far, the role of agility in project management has not been widely investigated. In the recent past, the concept of agility has mainly been applied to software development projects. The literature on agility is still in its early stages, and further research needs to be conducted in new project management domains. This study is intended to determine the impact of the adoption of APM on project …

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Experimental Investigation Of Advanced Ignition Systems For High Efficiency Combustion, Bader Almansour Jan 2018

Experimental Investigation Of Advanced Ignition Systems For High Efficiency Combustion, Bader Almansour

Electronic Theses and Dissertations

Consumption of fossil and bio-derived fuels is growing due to energy demands associated with increase in population and standard of living across the globe. Power generation and transportation sectors are the primary two sources of fuel consumption, which have raised the demand for crude oil and led to serious environmental pollution issues. This demand for energy forced various government agencies to strengthen the allowable exhaust pollutant concentration limits. Recently, CO, CO2, particulate matter, and nitrogen oxides (NOx) emission restrictions have become more stringent to the extent that engines must operate at higher energy densities and efficiencies. Towards this goal, this …

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A Holistic Analysis Of The Long-Term Challenges & Potential Benefits Of The Green Roof, Solar Pv Roofing, And Gripv Roofing Markets In Orlando, Florida, Carolina Kelly Jan 2018

A Holistic Analysis Of The Long-Term Challenges & Potential Benefits Of The Green Roof, Solar Pv Roofing, And Gripv Roofing Markets In Orlando, Florida, Carolina Kelly

Electronic Theses and Dissertations

Green roofs and roof-mounted solar PV arrays have a wide range of environmental and economic benefits, including significantly longer roof lifetimes, reductions in urban runoff, mitigation of the urban heat island (UHI) effect, reduced electricity demand and energy dependence, and/or reduced emissions of greenhouse gases (GHGs) and other harmful pollutants from the electricity generation sector. Consequently, green roofs and solar panels have both become increasingly popular worldwide, and promising new research has emerged for their potential combination in Green Roof Integrated Photovoltaic (GRIPV) roofing applications. However, due to policy resistance, these alternatives still have marginal market shares in the U.S., …

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Development Of A Tabletop Coherent Soft X-Ray Source, Hanfu Kong Jan 2018

Development Of A Tabletop Coherent Soft X-Ray Source, Hanfu Kong

Electronic Theses and Dissertations

The goal of this thesis is to design a tabletop coherent soft X-ray source for attosecond high resolution imaging. We collect signals from gas cells with different length and lens with different focal length. A spectrometer with a grating and a CCD camera is applied to observe and measure the spectrum of the X-ray attosecond pulses. This thesis first introduces the theory background of ultrafast lasers, then mainly explains high harmonic generation, which is the key method for attosecond pulses generation, subsequently presents the experiment system and analyzes the results from the experiment, also compares different combinations of parameters of …

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Regolith-Based Construction Materials For Lunar And Martian Colonies, Kevin Grossman Jan 2018

Regolith-Based Construction Materials For Lunar And Martian Colonies, Kevin Grossman

Electronic Theses and Dissertations

Humankind's ambitions of exploring our solar system and parts beyond depend heavily on our ability to collect resources from local environments at our destinations rather than bringing materials on the journey. This is a concept known as in-situ resource utilization (ISRU) and it is one that has been understood by every explorer and settler in the history of humankind. Regolith on the moon and Mars has been shown to be a particularly useful resource and has the ability to provide humans with resources including water, oxygen, construction material, fabric, radiation shielding, metals, and may more. This dissertation focuses on construction …

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Seepage And Stability Analysis Of The Earth Dams Under Drawdown Conditions By Using The Finite Element Method, Salama Al-Labban Jan 2018

Seepage And Stability Analysis Of The Earth Dams Under Drawdown Conditions By Using The Finite Element Method, Salama Al-Labban

Electronic Theses and Dissertations

One of the major concerns in the behavior of an earth dam is the change in the exit gradient and the impact on the slope stability under drawdown conditions. Drawdown can cause increased seepage forces on the upstream slope which may result in the movement of soil particles in the flow direction and cause erosion problems. In this research, a numerical approach, based on the finite element method (FEM) is used to analyze the seepage through the dam and its foundation to study exit gradients and slope stability under both steady-state and transient conditions. The results show that a central …

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Energy-Optimal Guidance Of An Auv Under Flow Uncertainty And Fluid-Particle Interaction, Demuni Singith De Zoysa Abeysiriwardena Jan 2018

Energy-Optimal Guidance Of An Auv Under Flow Uncertainty And Fluid-Particle Interaction, Demuni Singith De Zoysa Abeysiriwardena

Electronic Theses and Dissertations

The work presented gives an energy-optimal solution to the guidance problem of an AUV. The presented guidance methods are for lower level control of AUV paths, facilitating existing global planning methods to be carried out comparatively more efficiently. The underlying concept is to use the energy of fluid flow fields the AUVs are navigating to extend the duration of missions. This allows gathering of comparatively more data with higher spatio-temporal resolution. The problem is formulated for a generalized two dimensional uniform flow field given a fixed final time and free end states. This allows the AUVs to navigate to certain …

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Turbulent Flame-Vortex Dynamics Of Bluff-Body Premixed Flames, Marissa Geikie Jan 2018

Turbulent Flame-Vortex Dynamics Of Bluff-Body Premixed Flames, Marissa Geikie

Electronic Theses and Dissertations

This study explores the effects of turbulence and pressure-gradient tailoring on the turbulent flame and vorticity transport mechanisms of premixed flames. A turbulent premixed flame stabilized by a bluff-body in a high-speed combustor is used for the investigation. The combustor pressure gradient is altered using a variable-geometry test section. The turbulence within the combustor is controlled using a custom-designed, supersonic variable-turbulence generator. The turbulent flame-flow field is measured and characterized using simultaneous high-speed particle imaging velocimetry (PIV) and CH* chemiluminescence. The flame-vortex dynamics of the turbulent flame are analyzed using a Lagrangian tracking methodology. Lagrangian fluid elements (LFEs) are tagged …

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Bio-Inspired Visual Servo Control Of A Picking Mechanism In An Agricultural Ground Robot, Sinem Gozde Defterli Jan 2018

Bio-Inspired Visual Servo Control Of A Picking Mechanism In An Agricultural Ground Robot, Sinem Gozde Defterli

Electronic Theses and Dissertations

For a recently constructed disease detection agricultural ground robot, the segregation of unhealthy leaves from strawberry plants is a major task of the robot's manipulation subsystem in field operations. In this dissertation, the motion planning of a custom-designed picking mechanism in the ground robot's subsystem is studied in two sections. First, a set of analytical, suboptimal semi-analytical and numerical algorithms are studied to solve the inverse kinematics problem of the handling mechanism in firm circumstances. These premeditated approaches are built on the computation of the joint variables by an identified 3D position data of the target leaf only. The outcomes …

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Design Of High Efficiency Brushless Permanent Magnet Machines And Driver System, Chengyuan He Jan 2018

Design Of High Efficiency Brushless Permanent Magnet Machines And Driver System, Chengyuan He

Electronic Theses and Dissertations

The dissertation is concerned with the design of high-efficiency permanent magnet synchronous machinery and the control system. The dissertation first talks about the basic concept of the permanent magnet synchronous motor (PMSM) design and the mathematics design model of the advanced design method. The advantage of the design method is that it can increase the high load capacity at no cost of increasing the total machine size. After that, the control method of the PMSM and Permanent magnet synchronous generator (PMSG) is introduced. The design, simulation, and test of a permanent magnet brushless DC (BLDC) motor for electric impact wrench …

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Harmful Algal Bloom Mitigating Using Recycled Concrete Aggregate Coated With Fixed-Quat., Ikenna Ezeodurukwe Jan 2018

Harmful Algal Bloom Mitigating Using Recycled Concrete Aggregate Coated With Fixed-Quat., Ikenna Ezeodurukwe

Electronic Theses and Dissertations

Human activities generate surplus nutrients which may lead to algal bloom events in water resources along with serious ecological problems and thus substantial economic losses. Particularly, harmful algal blooms (HABs) represent toxic cyanobacterial blooms which produce cyanotoxins. The primary concerns of HABs are the exposures to a wide variety of cyanotoxins via ingestion of contaminated drinking water, inhalation during recreational activities, and consumption of contaminated fish and shellfish. However, conventional physical and chemical methods are not always possible to efficiently handle these HABs events. It is urgent to develop viable and rapid solutions to control HABs in field and mitigate …

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Fast Compressed Automatic Target Recognition For A Compressive Infrared Imager, Brian Millikan Jan 2018

Fast Compressed Automatic Target Recognition For A Compressive Infrared Imager, Brian Millikan

Electronic Theses and Dissertations

Many military systems utilize infrared sensors which allow an operator to see targets at night. Several of these are either mid-wave or long-wave high resolution infrared sensors, which are expensive to manufacture. But compressive sensing, which has primarily been demonstrated in medical applications, can be used to minimize the number of measurements needed to represent a high-resolution image. Using these techniques, a relatively low cost mid-wave infrared sensor can be realized which has a high effective resolution. In traditional military infrared sensing applications, like targeting systems, automatic targeting recognition algorithms are employed to locate and identify targets of interest to …

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