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Articles 73471 - 73500 of 196403

Full-Text Articles in Engineering

2013 - Greater Monterey County Integrated Regional Water Management - Disadvantaged Community And Tribal Needs Assessment Dec 2018

2013 - Greater Monterey County Integrated Regional Water Management - Disadvantaged Community And Tribal Needs Assessment

Miscellaneous Monterey and San Luis Obispo County Documents and Reports

A 2013 Disadvantaged Community and Tribal Needs Assessment as they relate to water management in the Greater Monterey County Integrated Regional Water Management process in the planning region thus informing future project development.


2018 Fall Engr333 Project Final Report (Section B), Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten Dec 2018

2018 Fall Engr333 Project Final Report (Section B), Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten

ENGR 333

What is the largest possible reduction in Calvin College’s annual energy costs from a $5M initial investment in renewable energy? Renewable energy systems are essential for Calvin College to reduce greenhouse gas emissions and achieve carbon neutrality to meet the Carbon Commitment that President Le Roy signed in December 2017. Also, a significant cost reduction could be a positive result of transitioning to renewable energy sources such as geothermal, wind, solar, and biomass. Four renewable energy sources were studied throughout the semester to determine a feasible renewable energy plan for Calvin with a $5M investment.


Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño Dec 2018

Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño

Electrical and Computer Engineering ETDs

Infrared (IR) detectors are an enabling technology for a broad and growing list of applications including gas detection, night vision, and space-based missile warning. There are ongoing efforts in IR detector research to explore the potential of new material systems and energy band structures in addition to continuously improving their sensitivity through increasing their quantum efficiency and lowering their dark current and noise. This dissertation examines an emerging class of IR detectors known as Interband Cascade Infrared Photodetectors (ICIPs).

ICIPs contain multiple regions to facilitate the collection of photogenerated electrons and to limit unwanted dark current. Theory regarding their performance …


Lightweight Thermal Management Material For Enhancement Of Through-Thickness Thermal Conductivity, Matthew Collins Weisenberger Dec 2018

Lightweight Thermal Management Material For Enhancement Of Through-Thickness Thermal Conductivity, Matthew Collins Weisenberger

Center for Applied Energy Research Faculty Patents

A flexible sheet of aligned carbon nanotubes includes an array of aligned nanotubes held in a polymer matrix material. The carbon nanotubes have an average length of between about 50 microns and about 500 microns. The polymer matrix has an average thickness of between about 10 microns and about 500 microns. The flexible sheet has a density of about 0.2 to about 1.0 glee and includes between about 98 to about 60 weight percent aligned carbon nanotubes and between about 2 and about 40 weight percent polymer. A tape of aligned carbon nanotubes, a method for producing a tape of …


Determination Of Chemical Speciation Of Arsenic And Selenium In High-As Coal Combustion Ash By X-Ray Photoelectron Spectroscopy: Examples From A Kentucky Stoker Ash, Biao Fu, James C. Hower, Shifeng Dai, Sarah M. Mardon, Guijian Liu Dec 2018

Determination Of Chemical Speciation Of Arsenic And Selenium In High-As Coal Combustion Ash By X-Ray Photoelectron Spectroscopy: Examples From A Kentucky Stoker Ash, Biao Fu, James C. Hower, Shifeng Dai, Sarah M. Mardon, Guijian Liu

Center for Applied Energy Research Faculty and Staff Publications

Knowledge of the chemical speciation of arsenic and selenium in coal fly ash is essential in the evaluation of the environmental behavior of fly ash disposed in a landfill in a natural environment. In this study, a series of high-As coal fly ash from stoker boilers were collected to determine the chemical forms of arsenic and selenium. The ash surface chemical characteristics and the speciation of arsenic and selenium were characterized by X-ray photoelectron spectroscopy and X-ray-induced Auger electron spectroscopy. The results indicate that the surface enrichment ratio for selenium (63.3–309.5) is higher than that of arsenic (1.2–21.2). The Wagner …


Quantifying Mg 2+ Binding To Ssdna Oligomers: A Self-Consistent Field Theory Study At Varying Ionic Strengths And Grafting Densities, Merina Jahan, Mark J. Uline Dec 2018

Quantifying Mg 2+ Binding To Ssdna Oligomers: A Self-Consistent Field Theory Study At Varying Ionic Strengths And Grafting Densities, Merina Jahan, Mark J. Uline

Faculty Publications

The performance of aptamer-based biosensors is crucially impacted by their interactions with physiological metal ions, which can alter their structures and chemical properties. Therefore, elucidating the nature of these interactions carries the utmost importance in the robust design of highly efficient biosensors. We investigated Mg 2+ binding to varying sequences of polymers to capture the effects of ionic strength and grafting density on ion binding and molecular reorganization of the polymer layer. The polymers are modeled as ssDNA aptamers using a self-consistent field theory, which accounts for non-covalent ion binding by integrating experimentally-derived binding constants. Our model captures the typical …


Numerical Simulations Of Flow Past A Triangular Airfoil And In A Sweeping Jet Actuator Using Different Turbulence Models, Han Yang Dec 2018

Numerical Simulations Of Flow Past A Triangular Airfoil And In A Sweeping Jet Actuator Using Different Turbulence Models, Han Yang

McKelvey School of Engineering Graduate Student Theses & Dissertations

The goal of this research is to perform 2D turbulent flow simulations to predict the flow past a triangular airfoil used for a Mars air vehicle and in a sweeping jet actuator used for active flow control. Simulations are performed using the commercial CFD software ANSYS Fluent.

The thesis consists of two parts. The first part of the thesis deals with the CFD simulations of a triangular airfoil in low-Reynolds-number compressible flow. This airfoil is one of the candidates for propeller blades on a possible future Martian air vehicle design. The aerodynamics and flow physics of the triangular airfoil is …


Temperature Transient Analysis For Reservoir Characterization, Yilin Mao Dec 2018

Temperature Transient Analysis For Reservoir Characterization, Yilin Mao

LSU Doctoral Dissertations

Recent developments in downhole temperature measurements open new alternatives contributing to reservoir characterization. In this dissertation, novel forward and inverse models to analyze production- and injection-induced temperature signals are developed for conventional and unconventional reservoir applications. Important limitations of the proposed models are addressed by accounting for fluid property variations and complex production strategies.

Forward modeling approaches involve making relevant assumptions that allow rigorous analytical solutions to be constructed using Laplace transform, Method of Characteristics, and control volume analysis. Our results of the analytical models are benchmarked with those from commercial numerical simulation software. Multiple possible scenarios of conventional reservoirs …


Electroless Nickel Plating And Spark Plasma Sintering Of Nano Zro2 For Mechanical Property Enhancement, Kunlong Jia Dec 2018

Electroless Nickel Plating And Spark Plasma Sintering Of Nano Zro2 For Mechanical Property Enhancement, Kunlong Jia

McKelvey School of Engineering Graduate Student Theses & Dissertations

A new approach of combined electroless nickel plating (ENP) and spark plasma sintering (SPS) was used to determine the feasibility of fracture toughness improvement of ZrO2. Nano-grained yttria stabilized zirconia (YSZ) particles of 100nm average diameter were coated with about 1-5 nm of nickel coating by ENP. To reduce nano particle agglomeration throughout the ENP process; vigorous agitation with an ultrasonic horn was used. The coated powder was characterized using Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Transmission electron microscopy (TEM) to study the microstructure and coating characteristics. The coating was identified to be predominantly nickel and of …


Additive Manufacturing Of Ti6al4v Alloy: A Review, Shunyu Liu, Yung C. Shin Dec 2018

Additive Manufacturing Of Ti6al4v Alloy: A Review, Shunyu Liu, Yung C. Shin

School of Mechanical Engineering Faculty Publications

In this paper, the recent progress on Ti6Al4V fabricated by three mostly developed additive manufacturing (AM) techniques-directed energy deposition (DED), selective laser melting (SLM) and electron beammelting (EBM)-is thoroughly investigated and compared. Fundamental knowledge is provided for the creation of links between processing parameters, resultant microstructures and associated mechanical properties. Room temperature tensile and fatigue properties are also reviewed and compared to traditionally manufactured Ti6Al4V parts. The presence of defects in as-builtAMTi6Al4V components and the influences of these defects on mechanical performances are also critically discussed.


2014 - Quarternary Geologic Map Of North-Central Salinas River Valley And Arroyo Seco Dec 2018

2014 - Quarternary Geologic Map Of North-Central Salinas River Valley And Arroyo Seco

Miscellaneous Monterey and San Luis Obispo County Documents and Reports

The new mapping provides a detailed stratigraphic history of incision and deposition from the early Pleistocene to the present. Infiltration from the Salinas River and its tributaries is the source of irrigation water in this agricultural region. Irrigation water is pumped from the aquifers at depths of about 55 and 120 m. Area has become intruded by seawater, especially between cities of Castroville and Salinas.


Spatial And Temporal Analysis Of Precipitation And Effective Rainfall Using Gauge Observations, Satellite, And Gridded Climate Data For Agricultural Water Management In The Upper Colorado River Basin, Mahyar Aboutalebi, Alfonso F. Torres-Rua, L. Niel Allen Dec 2018

Spatial And Temporal Analysis Of Precipitation And Effective Rainfall Using Gauge Observations, Satellite, And Gridded Climate Data For Agricultural Water Management In The Upper Colorado River Basin, Mahyar Aboutalebi, Alfonso F. Torres-Rua, L. Niel Allen

Civil and Environmental Engineering Faculty Publications

Accurate spatial and temporal precipitation estimates are important for hydrological studies of irrigation depletion, net irrigation requirement, natural recharge, and hydrological water balances in defined areas. This analysis supports the verification of water savings (reduced depletion)from deficit irrigation of pastures in the Upper Colorado River Basin. The study area has diverse topography with scattered fields and few precipitation gauges that are not representative of the basin.Gridded precipitation products from TRMM-3B42, PRISM, Daymet, and gauge observations were evaluated on two case studies located in Colorado and Wyoming during the 2014–2016 irrigation seasons. First, the resolution at the farm level is discussed. …


Sub-Nanometer Coupling Distance Control And Plasmon Enhanced Carrier Generation And Dynamics In Iii-V Semiconductor Heterostructures, Sharmin Haq Dec 2018

Sub-Nanometer Coupling Distance Control And Plasmon Enhanced Carrier Generation And Dynamics In Iii-V Semiconductor Heterostructures, Sharmin Haq

Optical Science and Engineering ETDs

Plasmonic modes in metal nanostructures enable light confinement at subwavelength scales. This field confinement is important for exploring the potential of nanotechnology in miniaturization of optics as well as for the advancement of optoelectronic devices, such as photodetectors, photovoltaics, and light-emitting diodes. Plasmon resonances are also ideal for developing ultrasensitive biosensors, and for enhancing surface photochemistry and photocatalysis. The increasing number of plasmon applications requires fundamental understanding of the plasmon coupled system which has not yet been completely understood. Controlling and engineering the plasmon response at the nanoscale will open still more applications in material science, communications, biochemistry and medicine. …


Effect Of Strong Electrolyte Containing Gelling Aids On The Sol-Gel Transition Temperature Of Hypromellose 2910, Elnaz Sadeghi Dec 2018

Effect Of Strong Electrolyte Containing Gelling Aids On The Sol-Gel Transition Temperature Of Hypromellose 2910, Elnaz Sadeghi

Biomedical Engineering ETDs

Hypromellose, or hydroxypropyl methylcellulose (HPMC) - has been widely used for biomedical and pharmaceutical applications due to its advantages, including that it is modifiable in terms of viscosity, and it has the ability to form thermally reversible hydrogels. The thermal gelation temperature (TGel) of a given HPMC solution strongly depends on its characteristic grade and the solution concentration. Applying certain additives can modify the TGel even further; depending on their nature and concentration. With the addition of said additives, a lower or higher TGel can be obtained. For example, the addition of sodium chloride (NaCl) reduces …


Lifecycle Modeling And Assessment Of Unmanned Aerial Vehicles (Drones) Co2e Emissions, Miguel A. Figliozzi Dec 2018

Lifecycle Modeling And Assessment Of Unmanned Aerial Vehicles (Drones) Co2e Emissions, Miguel A. Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

There are no studies that model the potential effectiveness of Unmanned Aerial Vehicles (UAVs) or drones to reduce CO2e lifecycle (including both utilization and vehicle phase) emissions when compared to conventional diesel vans, electric trucks, electric vans, and tricycles. This study presents a novel analysis of lifecycle UAV and ground commercial vehicles CO2e emissions. Different route and customer configurations are modeled analytically. Utilizing real-word data, tradeoffs and comparative advantages of UAVs are discussed. Breakeven points for operational emissions are obtained and the results clearly indicate that UAVs are more CO2e efficient, for small payloads, than conventional diesel vans in a …


Evaluating Future Flood Scenarios Using Cmip5 Climate Projections, Narayan Nyaupane, Balbhadra Thakur, Ajay Kalra, Sajjad Ahmad Dec 2018

Evaluating Future Flood Scenarios Using Cmip5 Climate Projections, Narayan Nyaupane, Balbhadra Thakur, Ajay Kalra, Sajjad Ahmad

Civil and Environmental Engineering and Construction Faculty Research

Frequent flooding events in recent years have been linked with the changing climate. Comprehending flooding events and their risks is the first step in flood defense and can help to mitigate flood risk. Floodplain mapping is the first step towards flood risk analysis and management. Additionally, understanding the changing pattern of flooding events would help us to develop flood mitigation strategies for the future. This study analyzes the change in streamflow under different future carbon emission scenarios and evaluates the spatial extent of floodplain for future streamflow. The study will help facility managers, design engineers, and stakeholders to mitigate future …


Validating The Satisfaction With Travel Scale As A Measure Of Hedonic Subjective Well-Being For Commuting In A U.S. City, Patrick A. Singleton Dec 2018

Validating The Satisfaction With Travel Scale As A Measure Of Hedonic Subjective Well-Being For Commuting In A U.S. City, Patrick A. Singleton

Civil and Environmental Engineering Faculty Publications

The relationships between transportation and well-being are of increasing interest to researchers, practitioners, and policymakers. Stakeholders seeking to improve quality of life and traffic safety require valid and reliable ways of gauging the emotional states of travelers. Psychological scales exist for measuring subjective well-being (SWB), but these instruments have rarely been applied to the travel domain. The Satisfaction with Travel Scale (STS) is a nine-item measure of travel-related hedonic SWB, capturing core affect (emotions) and cognitive evaluations of overall satisfaction associated with personal transportation. Although the STS has been used in an increasing number of studies, questions remain regarding its …


Coordinated Unmanned Aircraft System (Uas) And Ground-Based Weather Measurements To Predict Lagrangian Coherent Structures (Lcss), Peter J. Nolan, James Pinto, Javier González-Rocha, Anders Jensen, Christina N. Vezzi, Sean C. C. Bailey, Gijs De Boer, Constantin Diehl, Roger Laurence Iii, Craig W. Powers, Hosein Foroutan, Shane D. Ross, David G. Schmale Iii Dec 2018

Coordinated Unmanned Aircraft System (Uas) And Ground-Based Weather Measurements To Predict Lagrangian Coherent Structures (Lcss), Peter J. Nolan, James Pinto, Javier González-Rocha, Anders Jensen, Christina N. Vezzi, Sean C. C. Bailey, Gijs De Boer, Constantin Diehl, Roger Laurence Iii, Craig W. Powers, Hosein Foroutan, Shane D. Ross, David G. Schmale Iii

Mechanical Engineering Faculty Publications

Concentrations of airborne chemical and biological agents from a hazardous release are not spread uniformly. Instead, there are regions of higher concentration, in part due to local atmospheric flow conditions which can attract agents. We equipped a ground station and two rotary-wing unmanned aircraft systems (UASs) with ultrasonic anemometers. Flights reported here were conducted 10 to 15 m above ground level (AGL) at the Leach Airfield in the San Luis Valley, Colorado as part of the Lower Atmospheric Process Studies at Elevation—a Remotely-Piloted Aircraft Team Experiment (LAPSE-RATE) campaign in 2018. The ultrasonic anemometers were used to collect simultaneous measurements of …


Riverbank Filtration Impacts On Post Disinfection Water Quality In Small Systems—A Case Study From Auburn And Nebraska City, Nebraska, Matteo D'Alessio, Bruce Dvorak, Chittaranjan Ray Dec 2018

Riverbank Filtration Impacts On Post Disinfection Water Quality In Small Systems—A Case Study From Auburn And Nebraska City, Nebraska, Matteo D'Alessio, Bruce Dvorak, Chittaranjan Ray

Daugherty Water for Food Global Institute: Faculty Publications

Small water systems can experience a fluctuating quality of water in the distribution system after disinfection. As chlorine is the most common disinfectant for small systems, the occurrence of disinfection byproducts (DBPs) represents a common problem for these systems. Riverbank filtration (RBF) can be a valuable solution for small communities located on riverbanks. The objectives of this study were to evaluate (i) the improvements in water quality at two selected RBF systems, and (ii) the potential lower concentrations of DBPs, in particular, trihalomethanes (THMs), in small systems that use RBF. Two small communities in Nebraska, Auburn and Nebraska City, using …


A Fuzzy Based Model For Standardized Sustainability Assessment Of Photovoltaic Cells, Muath Bani Salim, Dervis Emre Demirocak, Nael Barakat Dec 2018

A Fuzzy Based Model For Standardized Sustainability Assessment Of Photovoltaic Cells, Muath Bani Salim, Dervis Emre Demirocak, Nael Barakat

Mechanical Engineering Faculty Publications and Presentations

In this paper, a new environmental sustainability indicator (ESI) is proposed to evaluate photovoltaic (PV) cells utilizing Life Cycle Analysis (LCA) principles. The proposed indicator is based on a model that employs a fuzzy logic algorithm to combine multiple factors, usually used in multiple LCAs, and produce results allowing a comprehensive interpretation of LCA phase sub-results leading to standardized comparisons of various PV cells. Such comparisons would be essential for policymakers and PV cell manufacturers and users, as they allow for fair assessment of the environmental sustainability of a particular type of PV with multiple factors. The output of the …


Vortex Motions Around A Vertically Vibrating Cylinder In Oscillatory Flows, Symphony Chakraborty, Tzu-Wen Lin, Ming-Jyh Chern Dec 2018

Vortex Motions Around A Vertically Vibrating Cylinder In Oscillatory Flows, Symphony Chakraborty, Tzu-Wen Lin, Ming-Jyh Chern

Journal of Marine Science and Technology–Taiwan

Numerical simulations of the vortex-induced vibration (VIV) on a circular cylinder in an oscillatory flow were conducted using the direct-forcing immersed boundary (DFIB) method. VIV of structures is a practical engineering problem. Many engineers have devoted themselves to research on the prevention of VIV, which can cause severe damage to offshore construction equipment and structures. Fluctuating hydrodynamic force induces vibration of structures because of the vortex around the structure. This vibration causes structural failure due to the lock-in phenomenon. A phenomenon termed “springing” (a secondorder wave effect caused by superposition of the incident waves and the reflected waves or other …


Hydrodynamic Analysis Of Underwater Glider With Diamond Wing In Unsteady And Nonuniform Flow Field, Chen-Wei Chen, Zhuo Feng, Xu Liang Dec 2018

Hydrodynamic Analysis Of Underwater Glider With Diamond Wing In Unsteady And Nonuniform Flow Field, Chen-Wei Chen, Zhuo Feng, Xu Liang

Journal of Marine Science and Technology–Taiwan

In this study, the hydrodynamic performance of a proposed underwater glider (UG) that utilizes a diamond wing was analyzed and its gliding ability in undersea environments with both steady and uniform and unsteady and nonuniform oceanic currents optimized. The flow field around the UG was analyzed using the software package RANS CFD. Under conditions where the current varied linearly both with water depth and time, the UG exhibited harmonically heaving and pitching motions, with a constant acceleration incident flow. The dynamic lifting and drag forces acting on the diamond wing and the dynamic heaving force and pitching moment acting at …


Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang Dec 2018

Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cellulose is biodegradable, renewable, and abundant in nature thus cellulose (or paper)-based products can be inexpensively produced and recycled. Among cellulosic materials, bacterial nanocellulose (BNC) draws a special research attention due to the inherent three-dimensional nanofibrous structure, excellent mechanical flexibility, high purity and well-defined surface chemistry, and cost-efficient, scalable and environment-friendly synthesis. BNC can be biosynthesized by Gluconacetobacter xylinus, which is the most characterized BNC producer among various microorganisms. BNC is composed of highly pure cellulose nanofibrils, produced from well-defined dextrose through biochemical steps and subsequent self-assembling of the secreted cellulose fibrils which has the dimension ranges from 25 to …


Kcnq1/Kcne1 Interaction In The Cardiac Iks Channel And Its Physiological Consequences, Jiajing Xu Dec 2018

Kcnq1/Kcne1 Interaction In The Cardiac Iks Channel And Its Physiological Consequences, Jiajing Xu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Dynamic conformational changes of ion channel proteins during activation gating determine their function as carriers of current. The relationship between these molecular movements and channel function over the physiological timescale of the action potential (AP) has not been fully established due to limitations of existing techniques. We constructed a library of possible cardiac IKs protein conformations and applied a combination of protein segmentation and energy linearization to study this relationship computationally. Simulations reproduced the effects of the beta-subunit (KCNE1) on the alpha-subunit (KCNQ1) dynamics and function, observed in experiments. Mechanistically, KCNE1 increased the probability of “visiting” conducting pore conformations on …


Molecular Basis Of Class Ib Drug Interactions With The Nav Channel Macromolecular Complex: A Route To Personalized Medicine For Cardiac Arrhythmia, Wandi Zhu Dec 2018

Molecular Basis Of Class Ib Drug Interactions With The Nav Channel Macromolecular Complex: A Route To Personalized Medicine For Cardiac Arrhythmia, Wandi Zhu

McKelvey School of Engineering Graduate Student Theses & Dissertations

The heart rhythm is precisely controlled by the electrical impulse that propagate in the cardiac tissue. In single cardiomyocytes, the electrical activity generated by action potentials (AP). Cardiac NaV channels (NaV1.5) carry a large influx of Na+ that mediates the initiation and propagation of the AP in both atria and ventricles. Disruption of NaV1.5 function by genetic variants or external factors can result in deadly arrhythmias, such as long QT syndrome and Brugada syndrome. Thus, NaV channels are import therapeutic targets. The class I antiarrhythmics are the modulators of the NaV channels. Although they have been used clinically for over …


Mechanisms Of Calcium Phosphate Mineralization On Biological Interfaces And Their Engineering Applications, Doyoon Kim Dec 2018

Mechanisms Of Calcium Phosphate Mineralization On Biological Interfaces And Their Engineering Applications, Doyoon Kim

McKelvey School of Engineering Graduate Student Theses & Dissertations

All living organisms utilize phosphorus (P) as an essential component of their cell membranes, DNA and RNA, and adenosine triphosphate. Bones, in addition to bearing loads, play an important role in balancing P levels in our bodies. In bones, a network of collagen templates and calcium phosphate (CaP) nanocrystals builds hierarchical levels, from nano- to macroscale. Within this architecture, the thermodynamic properties of CaP minerals are influential. Despite the importance of nucleation, growth, and crystallization in collagen structures for tissue development, little kinetic study of these processes has been conducted due to the limited in situ techniques for monitoring these …


Effects Of Secondary Stall And Unsteady Free-Stream On Blade Drag And Pitching Moments, Michael Malick Dec 2018

Effects Of Secondary Stall And Unsteady Free-Stream On Blade Drag And Pitching Moments, Michael Malick

McKelvey School of Engineering Graduate Student Theses & Dissertations

Dynamic stall is a complex aerodynamic phenomenon occurring in helicopter rotors, limiting the flight envelope and causing control linkage damage and instabilities. The Peters-Modarres semi-empirical dynamic stall model is extended to simulate pitching moment and drag in unsteady freestream and yawed flow, including the effects of secondary stall. The aerodynamics are implemented as a state-space model, suitable for time-marching or aeroelastic analyses. With small modifications to the original stall model, secondary stall effects and unsteady freestream can be simulated without adding additional states. An optimization routine determines sets of parameters that minimize the error between the modeled solution and experimental …


Information-Based Analysis And Control Of Recurrent Linear Networks And Recurrent Networks With Sigmoidal Nonlinearities, Deslin Menolascino Dec 2018

Information-Based Analysis And Control Of Recurrent Linear Networks And Recurrent Networks With Sigmoidal Nonlinearities, Deslin Menolascino

McKelvey School of Engineering Graduate Student Theses & Dissertations

Linear dynamical models have served as an analytically tractable approximation for a variety of natural and engineered systems. Recently, such models have been used to describe high-level diffusive interactions in the activation of complex networks, including those in the brain. In this regard, classical tools from control theory, including controllability analysis, have been used to assay the extent to which such networks might respond to their afferent inputs. However, for natural systems such as brain networks, it is not clear whether advantageous control properties necessarily correspond to useful functionality. That is, are systems that are highly controllable (according to certain …


Fast Forward-Backward Channel Estimation For Mimo Stbc-Ofdm Systems, Lena Chang Dec 2018

Fast Forward-Backward Channel Estimation For Mimo Stbc-Ofdm Systems, Lena Chang

Journal of Marine Science and Technology–Taiwan

In the study, we develop a fast forward-backward estimation (FFBE) method for multiple input multiple output (MIMO) space time block code (STBC) orthogonal frequency division multiplexing (OFDM) systems. We examined the matrix structure of the forward-backward (FB) correlation matrix and observed this matrix possessing permutation invariant (PI) property. We also investigated the eigen-property of a matrix with PI property and proved its eigenvectors possessing symmetric property, which can be calculated from two half dimensionality submatrices. Based on these analyses, we propose a fast eigen-decomposition algorithm to reduce the computations required in the eigendecomposition of FB correlation matrix. Then, the symmetric …


A Novel Splitting Beam Laser Extensometer Technique For Kolsky Tension Bar Systems, Colin Loeffler Dec 2018

A Novel Splitting Beam Laser Extensometer Technique For Kolsky Tension Bar Systems, Colin Loeffler

Mechanical Engineering Research Theses and Dissertations

The Kolsky (Split Hopkinson) Bar has become a well-known and established experimental technique for characterizing the mechanical behavior of materials subjected to dynamic loading conditions. Kolsky bar based experimental techniques facilitate the application of controlled and repeatable dynamic loading conditions to a specimen as well as the high resolution measurement of the resulting mechanical response. In recent decades the technique has been refined and adapted to provide more complex dynamic stress-states beyond uniaxial compression. However, the increasing complexity of the experimental apparatus introduces uncertainty to the traditional specimen deformation measurement techniques.

In this thesis, a direct non-contact optical measurement technique …