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Articles 94381 - 94410 of 197991

Full-Text Articles in Engineering

Analysis Of The Gauss-Bingham Distribution For Attitude Uncertainty Propagation, Jacob E. Darling, Kyle J. Demars Aug 2016

Analysis Of The Gauss-Bingham Distribution For Attitude Uncertainty Propagation, Jacob E. Darling, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Attitude uncertainty quantification typically requires a small angle assumption, and thus an inherent small uncertainty assumption, to be made. This small angle assumption can be eliminated by employing the Bingham distribution to represent the attitude uncertainty in the attitude quaternion directly. Moreover, an extension to the Bingham distribution, termed the Gauss-Bingham distribution, can be used to represent correlated attitude quaternion and angular velocity uncertainty to enable attitude uncertainty propagation. In order to evaluate the potential accuracy gain using the Gauss-Bingham distribution for attitude uncertainty quantification, the Gauss-Bingham distribution method for attitude uncertainty propagation is compared to the propagation step of …

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Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson Aug 2016

Trend Analysis Of Water Quality In Northwest Arkansas Streams Reflects Changes In The Watershed, Zachary Paul Simpson

Graduate Theses and Dissertations

Watershed export of nutrients, sediments, and chemicals impacts receiving waters. Changes within the watershed (e.g., anthropogenic or climatic) can alter the transport of constituents in streams. Stream monitoring is crucial for understanding these effects. This study developed a potential improvement to flow-adjusting constituent concentrations in streams, an important step of analyzing monitoring data in lotic systems for trends. The method incorporates a K-fold cross-validation procedure to optimize a model explaining the relationship between the concentration and streamflow, thus providing a valuable tool to researchers in water quality. Additionally, two case studies were conducted on watersheds located in northwest Arkansas using …

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Design And Analysis Of An Asynchronous Microcontroller, Michael Hinds Aug 2016

Design And Analysis Of An Asynchronous Microcontroller, Michael Hinds

Graduate Theses and Dissertations

This dissertation presents the design of the most complex MTNCL circuit to date. A fully functional MTNCL MSP430 microcontroller is designed and benchmarked against an open source synchronous MSP430. The designs are compared in terms of area, active energy, and leakage energy. Techniques to reduce MTNCL pipeline activity and improve MTNCL register file area and power consumption are introduced. The results show the MTNCL design to have superior leakage power characteristics. The area and active energy comparisons highlight the need for better MTNCL logic synthesis techniques.

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Study Of Plasmonic Properties Of The Gold Nanorods In The Visible To Near Infrared Light Regime, Pijush Kanti Ghosh Aug 2016

Study Of Plasmonic Properties Of The Gold Nanorods In The Visible To Near Infrared Light Regime, Pijush Kanti Ghosh

Graduate Theses and Dissertations

Nanostructures of noble metals show unique plasmonic behavior in the visible to near-infrared light range. Gold nanostructures exhibit a particularly strong plasmonic response for these wavelengths of light. In this study we have investigated optical enhancement and absorption of gold nanorods with different thickness using finite element method simulations. This study reports on the resonance wavelength of the sharp-corner and round-corner rectangles of constant length 100 nm and width 60 nm. The result shows that resonance wavelength depends on the polarization of the incident light; there also exists a strong dependence of the optical enhancement and absorption on the thickness …

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Investigation Of Cnt-Induced Escherichia Coli Lysis And Protein Release, Abdollah Mosleh Aug 2016

Investigation Of Cnt-Induced Escherichia Coli Lysis And Protein Release, Abdollah Mosleh

Graduate Theses and Dissertations

This research investigated the use of carbon nanotubes (CNTs) as a treatment to increase the permeability of a bacterial cell wall. Recombinant Escherichia coli BL21 (DE3) containing a plasmid that expressed Green Fluorescent Protein (GFP) and -lactamase were exposed to CNTs under various levels of agitation for different times. Fluorescence assay for GFP, optical absorbance for -lactamase activity, and Transmission Electron Microscopy (TEM) were used to determine the amount of released protein, and visually examine the permeability enhancement of the cells, respectively. It was found that more -lactamase was present in the culture fluid after treatment with CNTs in a …

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Electrodeionization Versus Electrodialysis: A Clean-Up Of Produced Water In Hydraulic Fracturing, Brigitte Marie Rodgers Aug 2016

Electrodeionization Versus Electrodialysis: A Clean-Up Of Produced Water In Hydraulic Fracturing, Brigitte Marie Rodgers

Graduate Theses and Dissertations

Electrodeionization (EDI) is a widely studied process ranging from applications in wastewater clean-up in the food and beverage industry to purifying organic compounds. To date, there are no apparent studies on applying this technology to produced wastewater recovered from hydraulic fracking sites. Water consumption within hydraulic fracturing sites can reach in the upwards of millions of gallons per site, so a need for a water recycling process becomes necessary within areas where water requirements are scarce. Implementation of an EDI module that is capable of handling high salt solutions from produced wastewater in subsequent fracturing practices will decrease overall water …

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Initial Structural Subsidence As Reflected In Morrowan And Atokan (Pennsylvanian) Subsurface Stratigraphy, Northern Arkoma Basin, North-Central Arkansas, Fatimah Taher Nahi Al Asadi Aug 2016

Initial Structural Subsidence As Reflected In Morrowan And Atokan (Pennsylvanian) Subsurface Stratigraphy, Northern Arkoma Basin, North-Central Arkansas, Fatimah Taher Nahi Al Asadi

Graduate Theses and Dissertations

The Arkoma Basin is a carboniferous foreland basin that is known for its prolific gas production. The objective of this research is to study the initial subsidence of the basin by analyzing the strati-graphic and structural features of the study area. This was accomplished through IHS Petra, Surf-er 13, and Win-Tensor software. Field work studies comprised a large part of this study. Also, a seismic profile and Google earth elevation profiles are among the methods used to study the initial subsidence of the Arkoma Basin. The study area within the basin represents a transitional zone from the shelf into the …

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Compact Modeling Of Sic Insulated Gate Bipolar Transistors, Sonia Perez Aug 2016

Compact Modeling Of Sic Insulated Gate Bipolar Transistors, Sonia Perez

Graduate Theses and Dissertations

This thesis presents a unified (n-channel and p-channel) silicon/silicon carbide Insulated Gate Bipolar Transistor (IGBT) compact model in both MAST and Verilog-A formats. Initially, the existing MAST model mobility equations were updated using recently referenced silicon carbide (SiC) data. The updated MAST model was then verified for each device tested. Specifically, the updated MAST model was verified for the following IGBT devices and operation temperatures: n-channel silicon at 25 ˚C and at 125 ˚C; n-channel SiC at 25 ˚C and at 175 ˚C; and p-channel SiC at 150 ˚C and at 250 ˚C. Verification was performed through capacitance, DC output …

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Photoluminescence Measurement On Low-Temperature Metal Modulation Epitaxy Grown Gan, Yang Wu Aug 2016

Photoluminescence Measurement On Low-Temperature Metal Modulation Epitaxy Grown Gan, Yang Wu

Graduate Theses and Dissertations

A low-temperature photoluminescence (PL) study was conducted on low-temperature metal modulation epitaxy (MME) grown GaN. By comparing the PL signal from high temperature grown GaN buffer layers, and MME grown cap layers on top of the buffer layers, it was found that MME grown GaN cap has a significantly greater defect-related emission. The band edge PL from MME grown GaN found to be 3.51eV at low temperature. The binding energy of the exciton in GaN is determined to be 21meV through temperature dependence analysis. A PL peak at 3.29eV was found in the luminescence of the MME grown cap layer, …

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Chlorine Demand Shows Thresholds And Hierarchy With Source Water Quality At Beaver Lake, Arkansas, Jaime M. Gile Aug 2016

Chlorine Demand Shows Thresholds And Hierarchy With Source Water Quality At Beaver Lake, Arkansas, Jaime M. Gile

Graduate Theses and Dissertations

This study investigated the effects of source water quality in Beaver Lake on the amount of chlorine (Cl) needed to develop decision support system to help guide chlorination practices in pre-treatment of source water. Chlorine demand assays were performed on water samples from Beaver Lake collected from the intake structure at Beaver Water District from March 2014 through August 2015, and using data from these assays, the two points of interest in this study were the Cl dose at which Cl residuals began to accumulate and the mean Cl demand occurring after that dose. Three methods of analysis were used …

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Solution Of Fully-Coupled Shallow Water Equations And Contaminant Transport Using A Primitive Variable Riemann Solver And A Semi-Discrete Supg Method, Faranak Behzadi Aug 2016

Solution Of Fully-Coupled Shallow Water Equations And Contaminant Transport Using A Primitive Variable Riemann Solver And A Semi-Discrete Supg Method, Faranak Behzadi

Masters Theses and Doctoral Dissertations

In the present dissertation, a finite volume and a finite element model are developed and tuned for the solution of the fully-coupled two-dimensional Shallow Water and Contaminant transport Equations with arbitrary bed topography and wetting-drying fronts. A Riemann-solver finite volume scheme, using primitive variables rather than conserved variables, and a semi-discrete Streamline Upwind Petrov-Galerkin (SUPG) method in finite element context are applied to compare the performance of these two numerical models. The Riemann-solver scheme is based on the unstructured finite volume discretization using primitive-variable Roe-flux approximation with an entropy fix. Second-order accuracy in space and time, an implicit scheme based …

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Least Squares Spectral Element Method For Laminar And Turbulent Flows, –Continuous And Discontinuous Approaches–, Jaber Javanshir Hasbestan Aug 2016

Least Squares Spectral Element Method For Laminar And Turbulent Flows, –Continuous And Discontinuous Approaches–, Jaber Javanshir Hasbestan

Masters Theses and Doctoral Dissertations

In this research, application of a least squares spectral element method for compressible laminar and turbulent flow problems is investigated. For the turbulent Reynolds Averaged Navier-Stokes (RANS), a modified Spalart-Allmaras (SA) turbulence model is employed and integrated with the mean flow equations in a segregated fashion. Two different approaches are presented for solving the SA model using the least squares method. The first method represents a simple rearrangement of the equation. However, proper arrangement of the SAmodel is required in order to produce a stable scheme for the least squares methodology. The second approach is into divide the SA equation …

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Study Design Of A Cluster-Randomized Controlled Trial To Evaluate A Large-Scale Distribution Of Cook Stoves And Water Filters In Western Province, Rwanda, Corey L. Nagel, Miles Kirby, Laura D. Zambrano, Ghislaine Rosa, Christina K. Barstow, Evan A. Thomas, Thomas Clasen Aug 2016

Study Design Of A Cluster-Randomized Controlled Trial To Evaluate A Large-Scale Distribution Of Cook Stoves And Water Filters In Western Province, Rwanda, Corey L. Nagel, Miles Kirby, Laura D. Zambrano, Ghislaine Rosa, Christina K. Barstow, Evan A. Thomas, Thomas Clasen

Mechanical and Materials Engineering Faculty Publications and Presentations

Background: In Rwanda, pneumonia and diarrhea are the first and second leading causes of death, respectively, among children under five. Household air pollution (HAP) resultant from cooking indoors with biomass fuels on traditional stoves is a significant risk factor for pneumonia, while consumption of contaminated drinking water is a primary cause of diarrheal disease. To date, there have been no largescale effectiveness trials of programmatic efforts to provide either improved cookstoves or household water filters at scale in a low-income country. In this paper we describe the design of a clusterrandomized trial to evaluate the impact of a national-level program …

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Torsional Strengthening Of Reinforced Concrete Beams Using Cfrp Composites, Ranj Rafeeq Aug 2016

Torsional Strengthening Of Reinforced Concrete Beams Using Cfrp Composites, Ranj Rafeeq

Dissertations and Theses

Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works …

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Variable Response Of A Thermally Tuned Mems Pressure Sensor, Robert A. Lake, Ronald A. Coutu Jr. Aug 2016

Variable Response Of A Thermally Tuned Mems Pressure Sensor, Robert A. Lake, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

A typical microelectromechanical systems (MEMS) pressure sensor consists of a thin, deformable membrane and sensing element such as a piezoresistive element which is used to measure the amount of deflection in response to an applied pressure. Previous efforts demonstrated that buckled membranes, from silicon on insulator (SOI) wafers, can be thermally tuned via joule heating. By applying heat to the membrane through a resistive heating element, compressive stress is induced in the membrane causing it to buckle further out of plane and increasing its overall stiffness response. It is demonstrated that by increasing the stiffness of the membrane, the response …

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15-05 Infrastructure And Technology For Sustainable Livable Cities, Upul Attanayake, Mehedi Hasan, Lizmert Lopez Jul 2016

15-05 Infrastructure And Technology For Sustainable Livable Cities, Upul Attanayake, Mehedi Hasan, Lizmert Lopez

Transportation Research Center Reports

Providing access and mobility for key installations and businesses located in cities become a challenge when there is limited public transport and non-motorized facilities. The challenges are significant in cities that are subjected to severe winter weather conditions. Improving access to sustainable mobility choices is a key aspect of developing livable cities. This project scope is limited to identifying methods and infrastructure to promote walking and cycling. With regards to cycling, bike-share program development and use of location-allocation models as planning tools are presented. To minimize exposure to adverse weather conditions, underground and above ground pedestrian systems are provided. These …

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Florida Rural Small Business Energy Assistance Collaborative Cumulative Report Ending July 31, 2016, Florida Solar Energy Center, Janet Mcilvaine Jul 2016

Florida Rural Small Business Energy Assistance Collaborative Cumulative Report Ending July 31, 2016, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

The U.S. Department of Agriculture's (USDA) Rural Development initiative reaches out to communities across America with many programs (http://www.rd.usda.gov/programs-services/all-programs). USDA's Rural Energy for America Program (REAP) offers grants and loan guarantees for energy efficiency improvements and renewable energy systems to agriculture operations and qualifying rural small businesses. USDA has awarded the University of Central Florida a grant to provide a limited number of subsidized Energy Audits to eligible businesses in Florida in support of USDA Rural Development (USDA-RD) Grant and Loan programs for rural small businesses. The ultimate goal of the energy audits is to increase participation in …

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Experimental Investigation Of Discharge Capacity Of Labyrinth Weirs With And Without Nappe Breakers, Omer Bilhan, Emin Emiroglu, Carol J. Miller Jul 2016

Experimental Investigation Of Discharge Capacity Of Labyrinth Weirs With And Without Nappe Breakers, Omer Bilhan, Emin Emiroglu, Carol J. Miller

Civil and Environmental Engineering Faculty Research Publications

Labyrinth weirs provide higher discharge capacity than conventional weirs, with the ability to pass large flows at comparatively low heads. Labyrinth weirs are primarily used as spillways for dams where the spillway width is restricted. In recent years, many research investigations have considered the hydraulic performance of labyrinth weirs, particularly as dependent on the geometric features. The previous work has improved the design basis for such weirs. However, their design still requires experimentally derived and generalized performance curves. It is especially important to observe the behavior of the weir nappe to ensure the design provides hydraulic optimization and to account …

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Cost Effectiveness Of Energy Efficiency And On-Site Photovoltaic Power For 2015 Iecc Energy Rating Index (Eri) Compliance (Draft), Florida Solar Energy Center, Philip W. Fairey Jul 2016

Cost Effectiveness Of Energy Efficiency And On-Site Photovoltaic Power For 2015 Iecc Energy Rating Index (Eri) Compliance (Draft), Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

EnergyGauge® USA v.5.1 is used to simulate the energy use of one-story, three-bedroom, 2000 ft2 , single-family, frame homes in sixteen representative U.S. climates comprising all eight IECC climate zones. The energy use of the Section R406.2 minimum efficiency home (the Baseline Home) is compared against the energy use of homes complying with the prescriptive requirements of Section R402 of the 2015 IECC and against homes complying with the Section R406 Energy Rating Index (ERI) Compliance Alternative. The improvement cost and energy savings of the improved homes relative to the Baseline Home are then used to determine the cost …

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Dango (Doings And Goings On) - Vol. 22 | Issue 11, Haley Stien, Cecily Towell, Aric Tate, Matthew Kimball, Rusty Towell, Vicente Rojas, Paul Carstens, Joshua Daniel Martinez, Reuben Byrd, Mike Daugherity Jul 2016

Dango (Doings And Goings On) - Vol. 22 | Issue 11, Haley Stien, Cecily Towell, Aric Tate, Matthew Kimball, Rusty Towell, Vicente Rojas, Paul Carstens, Joshua Daniel Martinez, Reuben Byrd, Mike Daugherity

DANGO: Doings and Goings On: Summer Research Newsletter, Department of Engineering and Physics

ACU Department of Engineering and Physics Summer Research Newsletter

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Chemodiversity Of Dissolved Organic Matter In The Amazon Basin, Michael Gonsior, Juliana Valle, Philippe Schmitt-Kopplin, Norbert Hertkorn, David Bastviken, Jenna L. Luek, Mourad Harir, Wanderley Bastos, Alex Enrich-Prast Jul 2016

Chemodiversity Of Dissolved Organic Matter In The Amazon Basin, Michael Gonsior, Juliana Valle, Philippe Schmitt-Kopplin, Norbert Hertkorn, David Bastviken, Jenna L. Luek, Mourad Harir, Wanderley Bastos, Alex Enrich-Prast

Civil & Environmental Engineering

Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajós River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of …

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Unmanned Aerial Vehicles For High-Throughput Phenotyping And Agronomic Research, Yeyin Shi, J. Alex Thomasson, Seth C. Murray, N. Ace Pugh, William L. Rooney, Sanaz Shafian, Nithya Rajan, Gregory Rouze, Cristine L. S. Morgan, Haly L. Neely, Aman Rana, Muthu V. Bagavathiannan, James Henrickson, Ezekiel Bowden, John Valasek, Jeff Olsenholler, Michael P. Bishop, Ryan Sheridan, Eric B. Putman, Sorin Popescu, Travis Burks, Dale Cope, Amir Ibrahim, Billy F. Mccutchen, David D. Baltensperger, Robert V. Avant, Jr., Misty Vidrine, Chenghai Yang Jul 2016

Unmanned Aerial Vehicles For High-Throughput Phenotyping And Agronomic Research, Yeyin Shi, J. Alex Thomasson, Seth C. Murray, N. Ace Pugh, William L. Rooney, Sanaz Shafian, Nithya Rajan, Gregory Rouze, Cristine L. S. Morgan, Haly L. Neely, Aman Rana, Muthu V. Bagavathiannan, James Henrickson, Ezekiel Bowden, John Valasek, Jeff Olsenholler, Michael P. Bishop, Ryan Sheridan, Eric B. Putman, Sorin Popescu, Travis Burks, Dale Cope, Amir Ibrahim, Billy F. Mccutchen, David D. Baltensperger, Robert V. Avant, Jr., Misty Vidrine, Chenghai Yang

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Advances in automation and data science have led agriculturists to seek real-time, high quality, high-volume crop data to accelerate crop improvement through breeding and to optimize agronomic practices. Breeders have recently gained massive data-collection capability in genome sequencing of plants. Faster phenotypic trait data collection and analysis relative to genetic data leads to faster and better selections in crop improvement. Furthermore, faster and higher-resolution crop data collection leads to greater capability for scientists and growers to improve precision-agriculture practices on increasingly larger farms; e.g., site-specific application of water and nutrients. Unmanned aerial vehicles (UAVs) have recently gained traction as agricultural …

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Use Of Clustering Techniques For Protein Domain Analysis, Eric Rodene Jul 2016

Use Of Clustering Techniques For Protein Domain Analysis, Eric Rodene

School of Computing: Dissertations, Theses, and Student Research

Next-generation sequencing has allowed many new protein sequences to be identified. However, this expansion of sequence data limits the ability to determine the structure and function of most of these newly-identified proteins. Inferring the function and relationships between proteins is possible with traditional alignment-based phylogeny. However, this requires at least one shared subsequence. Without such a subsequence, no meaningful alignments between the protein sequences are possible. The entire protein set (or proteome) of an organism contains many unrelated proteins. At this level, the necessary similarity does not occur. Therefore, an alternative method of understanding relationships within diverse sets of proteins …

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Soil-Bentonite Slurry Trench Cutoff Wall Closeout Report, Daniel Ruffing Jul 2016

Soil-Bentonite Slurry Trench Cutoff Wall Closeout Report, Daniel Ruffing

NSF Soil-Bentonite Slurry Trench Cutoff Wall Documents

Assessment report of the construction of a soil-bentonite slurry wall including milestone dates, work description, and quality control.

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Combining Spatial Domain Multiplexing And Orbital Angular Momentum Of Photon-Based Multiplexing To Increase The Bandwidth Of Optical Fiber Communication Systems, Syed H. Murshid, Saud F. Alanzi, Arnob Hridoy, Gregory L. Lovell, Gurinder Parhar, Abhijit Chakravarty, Bilas Chowdhury Jul 2016

Combining Spatial Domain Multiplexing And Orbital Angular Momentum Of Photon-Based Multiplexing To Increase The Bandwidth Of Optical Fiber Communication Systems, Syed H. Murshid, Saud F. Alanzi, Arnob Hridoy, Gregory L. Lovell, Gurinder Parhar, Abhijit Chakravarty, Bilas Chowdhury

Electrical Engineering and Computer Science Faculty Publications

Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple singlemode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different …

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The Impact Of The State-Level Concept On “Newcomers”: A Case Study Of The Kingdom Of Saudi Arabia, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo Jul 2016

The Impact Of The State-Level Concept On “Newcomers”: A Case Study Of The Kingdom Of Saudi Arabia, Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The International Atomic Energy Agency’s (IAEA) latest reports indicate a growing number of states (newcomers) considering the deployment of nuclear energy programs. In developing nuclear infrastructure, newcomers have to employ the prevailing standards to deploy the nuclear program in a secure, safe, and sustainable manner. State-Level Concept (SLC) refers to a comprehensive approach that uses information about a state’s nuclear facilities and capabilities to implement safeguards within the scope of the state’s safeguards agreement. SLC focuses on strengthening the effectiveness and improving the efficiency of the safeguards system considering the State as whole. SLC has been implemented in 53 states, …

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Adjusting Particle-Size Distributions To Account For Aggregation In Tephra-Deposit Model Forecasts, Larry G. Mastin, Alexa R. Van Eaton, Adam J. Durant Jul 2016

Adjusting Particle-Size Distributions To Account For Aggregation In Tephra-Deposit Model Forecasts, Larry G. Mastin, Alexa R. Van Eaton, Adam J. Durant

Michigan Tech Publications, Part 1

Volcanic ash transport and dispersion (VATD) models are used to forecast tephra deposition during volcanic eruptions. Model accuracy is limited by the fact that fine-ash aggregates (clumps into clusters), thus altering patterns of deposition. In most models this is accounted for by ad hoc changes to model input, representing fine ash as aggregates with density ρagg, and a log-normal size distribution with median μagg and standard deviation σagg. Optimal values may vary between eruptions. To test the variance, we used the Ash3d tephra model to simulate four deposits: 18 May 1980 Mount St. Helens; 16-17 September 1992 Crater Peak (Mount …

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Multiple New-Particle Growth Pathways Observed At The Us Doe Southern Great Plains Field Site, Anna L. Hodshire, Michael J. Lawler, Jun Zhao, John Ortega, Coty Jen, Taina Yli-Juuti, Jared F. Brewer, Jack K. Kodros, Kelley C. Barsanti, Dave R. Hanson, Peter H. Mcmurry, James N. Smith, Jeffery R. Pierce Jul 2016

Multiple New-Particle Growth Pathways Observed At The Us Doe Southern Great Plains Field Site, Anna L. Hodshire, Michael J. Lawler, Jun Zhao, John Ortega, Coty Jen, Taina Yli-Juuti, Jared F. Brewer, Jack K. Kodros, Kelley C. Barsanti, Dave R. Hanson, Peter H. Mcmurry, James N. Smith, Jeffery R. Pierce

Civil and Environmental Engineering Faculty Publications and Presentations

New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low volatility species, from diameters ∼ 1 to 30–100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids …

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Multiplex Information Networks For Spatially Evolving Multiagent Formations, Dung Tran, Tansel Yucelen, Eduardo Pasiliao Jul 2016

Multiplex Information Networks For Spatially Evolving Multiagent Formations, Dung Tran, Tansel Yucelen, Eduardo Pasiliao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we show how information exchange rules represented by a network having multiple layers (multiplex information networks) can be designed for enabling spatially evolving multiagent formations. Specifically, we consider the formation tracking problem and introduce a novel distributed control architecture. The proposed approach allows capable agents to spatially alter density and orientation of the resulting formation while tracking a dynamic, non-stationary target without requiring global information exchange ability. A numerical example is provided to illustrate the efficacy of the proposed distributed control architecture.

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Adaptive Control Architectures For Mitigating Sensor Attacks In Cyber-Physical Systems, Tansel Yucelen, Wassim M. Haddad, Eric M. Feron Jul 2016

Adaptive Control Architectures For Mitigating Sensor Attacks In Cyber-Physical Systems, Tansel Yucelen, Wassim M. Haddad, Eric M. Feron

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The accuracy of sensor measurements is critical to the design of high-performance control systems since sensor uncertainties can significantly deteriorate achievable closed-loop dynamical system performance. Sensor uncertainty can arise due to low sensor quality, sensor failure, or detrimental environmental conditions. For example, relatively cheap sensor suites are used for low-cost, small-scale unmanned vehicle applications that can result in inaccurate sensor measurements. Alternatively, sensor measurements can also be corrupted by malicious attacks if dynamical systems are controlled through large-scale, multilayered communication networks as is the case in cyber-physical systems. This paper presents several adaptive control architectures for stabilization of linear dynamical …

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