Engineering Commons^™

Dynamic Modelling Of Single Phase Grid Connected Photovoltaic System, Gopi Krishna Ari

UNLV Theses, Dissertations, Professional Papers, and Capstones

Grid-connected photovoltaic (PV) power systems have been sustaining an exponential growth rate during the past decade. This steep growth is driven by a growing concern about climate change, the adoption of an aggressive regional renewable portfolio standard, rebates and tax incentives, and reduction in PV system cost. One of the main technical barriers that can ultimately limit further PV penetration is the fast variations in the PV system's output power induced by cloud transients. Such events are known to cause voltage fluctuations which may lead to excessive operations of voltage regulation equipment and light flickering.

Solar irradiance variability, which can …

The Use Of A Pylon Mounted Transducer For Investigating The Gait Of Transtibial Amputees, Justin Robert Brink

UNLV Theses, Dissertations, Professional Papers, and Capstones

Two areas of research interest in the design and use of lower limb prosthetic devices are how foot performance varies with design and how prosthesis alignment affects gait. The current study addressed both of these areas through the use of the JR3 triaxial transducer mounted at the base of the socket. The transducer is an innovative form of instrumentation that measures forces and moments at the end of the socket. Traditional measurement of gait uses a force plate buried in the floor of a gait laboratory. The study established that the transducer offers a viable means of instrumentation for amputee …

Upgrading Unlv's Astm E477 Test Facility To Meet The Current Standards Of Astm E477, Ronn Fojas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A by-product of Heating, Ventilation, and Air-conditioning (HVAC) systems is noise that is produced by fans, compressors, and other related equipments and the noises from the turbulence that is created by moving air. Sometimes, it is impractical to modify the sources of the noise, which requires designers to modify the path of the noise, the duct system. These modifications might include installing an in-duct silencer or acoustical lining on the inside walls of the ducts. The testing and the precise quantification of the performance of these silencers and duct linings are necessary for any designer to be able to make …

Structural Performance Of Reinforced Concrete Flat Plat Buildings Subjected To Fire, Sara Jean George

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reinforced concrete structures are typically considered to have inherent resistance to fire. However, several concrete structures around the world have experienced partial or total collapse under fire. Reinforced concrete flat-plate is a type of structural system widely used for office and residential buildings. Flat plate construction is prone to punching shear failure at slab-column connections which may lead to a catastrophic progressive collapse. The slabs of flat-plates generally have very thin concrete cover leaving steel reinforcement more sensitive to thermal loads. Little is known in the engineering community about the structural performance of flat-plate structures subjected to fire. Through a …

Shock And Vibration Isolation System For Ambulatory And Litter Patients In Ground And Air Medical Transport, Mohamad R. Hachem

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project explored the effectiveness of seat and litter air bladder technologies in reducing patient exposure to whole body shock and vibration during ground borne and airborne medical transport. Several seat and litter air bladder configurations were examined during field tests in a U.S. Army RG-33 MRAP ambulance and a U.S. Army HH-60M Black Hawk helicopter. The MRAP field tests were conducted at Ft. Detrick, Maryland. The Black Hawk field tests were conducted at Ft. Rucker, Alabama.

During the field tests, tri-axial vibration signals were recorded on a 16-channel CoCo90 Data Logger/Frequency Analyzer and then post processed in the laboratory …

Buffering Pv Output During Cloud Transients With Energy Storage, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consideration of the use of the major types of energy storage is attempted in this thesis in order to mitigate the effects of power output transients associated with grid-tied CPV systems due to fast-moving cloud coverage. The approach presented here is to buffer intermittency of CPV output power with an energy storage device (used batteries) purchased cheaply from EV owners or battery leasers. When the CPV is connected to the grid with the proper energy storage, the main goal is to smooth out the intermittent solar power and fluctuant load of the grid with a convenient control strategy. This thesis …

Evaluation Of Highly Efficient Distribution Transformer Design And Energy Standards Based On Load, James Sanguinetti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Power distribution transformers have been prevalent in commercial building distribution systems since the inception of modern commercial electricity. Yet as more and more manufactures seek to improve transformer efficiencies by making changes to the design of the transformer itself, a fundamental concept may be overlooked - the impact transformer demand sizing has on power losses. When modern transformers are improperly sized for the application they will be installed for they are not being utilized at their optimum design loading range, which may impact operating efficiency.

This thesis will aim to test and evaluate modern day transformer design coupled with currently …

Improving Efficiency And Capacity Of Hydro-Turbines In The Western United States, Hoover Dam, Jonathan Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal for this thesis is to minimize clearances and tolerances, in order to prevent water leakage. A proper seal on the seal rings does not let excess water flow through the turbine runner, thus conserving more water and wasting less energy. Moreover, water leakage past worn wear plates allows for an extra load for the turbine when operating in condense mode. When the wicket gates are closed, water leakage past worn plates wastes mechanical energy in the water; thus, decreasing the efficiency of the Francis turbine, especially when operating at partial loads. Furthermore, the wicket gates also known as …

Design Of Negative Bias Temperature Instability (Nbti) Tolerant Register File, Saurabh Kothawade

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Negative Bias Temperature Instability (NBTI) is becoming a major reliability problem in the semiconductor industry. As time passes, NBTI reduces the capacity of performing correct computations in the microprocessor. Hence, after certain time period, the microprocessor may fail to work as we expect, causing failure of the entire system it is part of. In this research, we study the root cause of the failure due to NBTI effect. Based on our findings, we propose multiple methods to reduce the negative impact of NBTI on a microprocessor. We build a comprehensive experimental setup to consider real world effects in a microprocessor. …

Relationships Between Runoff, Land Cover And Climate In The Semi-Arid Intermountain Region Of The Western U.S.A., Ibrahim Nourein Mohammed

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Hydrologic science is broadly defined as the geoscience that describes and predicts the occurrence, circulation and distribution of the water of the earth and its atmosphere. The need to predict the effects of land cover and climate changes with their associated impacts on hydrology are among the pressing areas of research, especially within the western United States. The main objective of this dissertation is to provide a better knowledge of land use or land cover along with climate change impacts on streamflow generated from watersheds in the semi-arid intermountain region in and around Utah. This objective was addressed using analyses …

Evaluation Of Turbulence Variable Distributions For Incompressible Fully Rough Pipe Flows, Emilie B. Fowler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The specific turbulent kinetic energy, root-mean-square fluctuating vorticity, and mean-vortexwavelength distributions are presented for fully rough pipe flow. The distributions of these turbulence variables are obtained from a proposed turbulence model. Many of the turbulence models commonly used for computational fluid dynamics are based on an analogy between molecular and turbulent transport. However, traditional k-ε and k-ω models fail to exhibit proper dependence on the molecular viscosity. Based on a rigorous application of the Boussinesq’s hypothesis, Phillips proposed a vorticity-based transport equation for the turbulent kinetic energy. The foundation for this vorticity-based transport equation is presented. In future development of …

Evaluating The Effectiveness Of Three Utah Wastewater Treatment Facilities In Removing Pharmaceuticals And Personal Care Products, Oksana Roth

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The occurrence of Pharmaceuticals and Personal Care Products (PPCPs) in surface waters has become a growing concern within the last decade although the first mention of human PPCPs in the environment goes back to late 1970s. Pharmaceuticals include prescription drugs, over-the-counter medications, and veterinary drugs. Personal care products include products such as lotions, fragrances, and soaps. In addition to traditional personal care products, the term PPCPs has been adopted to represent a wide variety of chemicals used in consumer products including plasticizers and fire retardants. Wastewater effluents are thought to be the main source of PPCPs in surface waters since …

Raman Microspectroscopy, Atomic Force Microscopy, And Electric Cell-Substrate Impedance Sensing For Characterization Of Bio-Interfaces: Molecular, Bacteria, And Mammalian Cells, Gerald Dustin Mcewen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding bio-interfaces will help improve the design and application of biomaterials that can interact with biological objects like nucleic acids, molecules, bacteria, and mammalian cells. Currently, there exist instruments to investigate material properties for the electrical, chemical, physical, and mechanical nature of biomaterials or biological samples. Our goal is to use advanced spectroscopic methods and data analysis to find specific properties of biological objects and see how these properties show the biological object’s response to their environment.

My studies of interfacial electron transfer (ET) of DNA coated gold electrodes aided to understand that the density of DNA on the surface …

Statistical Methods For Launch Vehicle Guidance, Navigation, And Control (Gn&C) System Design And Analysis, Michael Benjamin Rose

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A new tool for launch vehicle design and analysis is developed. The tool is capable of rapid analysis of requirements tradeoffs affecting system design and developed to reduce turnaround time for launch vehicle design and mission planning. It is streamlined to quickly determine trajectory and attitude control dispersions which represent how far the actual trajectory is expected to deviate from the nominal flight path, propellant dispersions which represent how much propellant is required to meet mission requirements, and navigation errors which represent how far the navigation filter’s estimate of the actual trajectory is expected to deviate from the actual trajectory. …

A Phenomenological Study Of Professional Identity Change In Released-Time Seminary Teachers, Mark Daniel Mason

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many practitioners commonly deal with implementing a change that is imposed by an organization. Some imposed changes require practitioners to alter more than what they do in practice but also to change their identity. Many researchers have studied identity change through the lens of sociocultural theory, specifically utilizing communities of practice theory (CoP). However, the majority of these studies used CoP theory as a vehicle to implement the imposed change. Yet some studies have found that after the trial period ends many practitioners revert back to the way they performed in practice prior to the study. One reason for this …

People Matching For Transportation Planning Using Optimized Features And Texel Camera Data For Sequential Estimation, Ziang Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis explores pattern recognition in the dynamic setting of public transportation, such as a bus, as people enter and later exit from a doorway. Matching the entrance and exit of each individual provides accurate information about individual riders such as how long a person is on a bus and which stops the person uses. At a higher level, matching exits to entries provides information about the distribution of traffic flow across the whole transportation system. A texel camera is implemented and multiple measures of people are made where the depth and color data are generated. A large number of …

Finite Element Modeling Of Transverse Post-Tensioned Joints In Accelerated Bridge Construction (Abc) Full-Scale Precast Bridge Deck Panels, Sandeep Reddy Madireddy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Accelerated bridge construction (ABC) techniques are popular among the department of transportations (DOTs). Innovative design and construction methods and high performance materials are used to reduce the typical bridge construction timeline without sacrificing bridge quality. The goal of accelerated bridge construction is to open a cost-effective, long-lasting bridge to traffic with increased safety and reduced traffic disruption in a shortened construction period. Accelerated bridge construction majorly uses steel-concrete composite bridges with full depth precast decks which has two types of connections, shear connection between steel girder and precast deck and transverse joint between precast panels. Longitudinal prestress is applied to …

Heterogeneous Water And Energy End-Uses And Implications For Residential Water And Energy Conservation And Management, Adel M. Abdallah

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Indoor water-use consumes energy to heat hot water. Indoor water- and energy-use vary significantly among households due to variable household water-use behaviors and varying ages and efficiencies of water appliances. Also, the energy consumed to heat water varies among households and depends on water heater efficiency, heater thermostat setup, percentage of hot water in the final used water, and the cold water intake temperature. This research considers behavioral and technological variability in household water-and-energy-use to better understand water and energy linkages and help utilities target water and energy conservation actions to customer and appliances within their homes that the most …

Using Relevance Vector Machines Approach For Prediction Of Total Suspended Solids And Turbidity To Sustain Water Quality And Wildlife In Mud Lake, Hussein Aly Batt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The main objective of the research is the development of Multivariate Relevant Vector Machine (MVRVM) to predict suspended fine sediment, water quality constituents, and provide an understanding for the practical problem of determining the amount of data required for the MVRVM. MVRVM is a statistical learning algorithm that is based on Bayes theory. It has been widely used to predict patterns in hydrological systems and other fields. This research represents the first known attempt to use a MVRVM approach to predict transport of very fine sediment and water quality constituents in a complex natural system.

The results demonstrate the ability …

Integration Of Water-Column And Benthic Processes And Their Effect On Dissolved Oxygen Fluctuations In Small Northern Utah Streams, Ruba A. Mohamed

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Dissolved oxygen (DO) is an important element for aquatic organisms as it is used for respiration by most organisms. Certain concentrations of DO are required in aquatic ecosystems depending on the type and needs of the aquatic organisms. In general, DO concentrations less than 5 mg/L stress many types of aquatic organisms including fishes. In order to maintain DO concentration above the stress level, respiration is one of the factors that should be maintained by controlling the excess growth of aquatic plants. Many factors cause the outbreak of plant growth, including abundance of nutrients and presence of sun light. In …

Identification Of Influential Climate Indicators, Prediction Of Long-Term Streamflow And Great Salt Lake Elevation Using Machine Learning Approach, Niroj K. Shrestha

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In order to meet rising water demand due to rapid population growth and changing climatic conditions around the world, and to reduce the impact of floods and draughts, a comprehensive water management and planning is necessary. Water resource management requires the prediction of streamflow under climatic variability, and variability of hydrologic quantities that changes in time and space. Prediction of streamflow using physically-based model are usually complex and typically requires detailed knowledge of physical processes. The availability of data is an important issue to justify the use of these models. Using a data-driven model that relies on the machine learning …

Using Stereo Particle Image Velocimetry To Quantify And Optimize Mixing In An Algae Raceway Using Delta Wings, Blake W. Lance

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Biofuel research has been continually growing over the past six decades. Of the potential sources for biofuels, microalgae is the most promising, and circulating (raceway) ponds are the most cost-effective method for growing microalgae in abundance. Nevertheless, biofuel production from algae must be more efficient to be competitive with traditional fuels. Previous studies using several airfoils, triangles, and squares at high angles to the flow direction (angle of attack) show an increase in mixing in raceways and can improve productivity by up to a factor of 2.2. Researchers show that increasing growth by increasing mixing is a repeatable effect that …

Simulation Of Counterintuitive Pressure Drop In A Parallel Flow Design For A Specimen Basket For Use In The Advanced Test Reactor, Adam X. Zabriskie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To continue improving nuclear energy, new materials must be tested in testing reactors such as the Advanced Test Reactor (ATR) at Idaho National Laboratory. A new test cap section allowed coolant to contact specimens tested in the ATR. A parallel channel test cap section should reduce the pressure drop across this section compared to a single channel. A fluid experiment conducted by Idaho State University showed the pressure drop was actually greater. A Computation Fluid Dynamics simulation using STAR-CCM+ was conducted of the fluid experiment to explain the abnormal pressure drop. The simulation provided evidence of ow through the test …

Autocorrelation-Based Estimate Of Particle Image Density In Particle Image Velocimetry, Scott O. Warner

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In Particle Image Velocimetry (PIV), the number of particle images per interrogation region, or particle image density, impacts the strength of the correlation and, as a result, the number of valid vectors and the measurement uncertainty. Therefore, any a-priori estimate of the accuracy and uncertainty of PIV requires knowledge of the particle image density. An autocorrelation-based method for estimating the local, instantaneous, particle image density is presented. Synthetic images were used to develop an empirical relationship based on how the autocorrelation peak magnitude varies with particle image density, particle image diameter, illumination intensity, interrogation region size, and background noise.

This …

Traffic Operations Analysis Of Merging Strategies For Vehicles In An Automated Electric Transportation System, Derek Rulon Freckleton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Automated electric transportation has the potential to revolutionize the way people move by providing unparalleled benefits to human health and safety, economic independence, and quality of life. It is a system where vehicles with no emissions control themselves as they cooperatively move people from point “A” to point “B.” Vehicle automation aims to eliminate human error from the task of driving, making the roads safer and leaving drivers able to perform other tasks as they desire while they travel. Also, through wireless in-motion electric power transfer, the gas tank may finally be completely excluded from vehicles without sacrificing freedoms in …

Carrier Frequency Offset Estimation For Orthogonal Frequency Division Multiplexing, Nagaravind Challakere

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of the research for this thesis is to improve the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system by minimising the impact of frequency offset at the receive end. OFDM is a popular standard used in wireless communication systems such as cellphone networks and broadband internet. In an OFDM system, the data symbols modulate the carrier signal at the transmitter. Usually, the receiver function generator performs the demodulation task. In the absence of frequency offset compensation, the transmitted symbols can not be effectively recovered upon reception. This leads to packet loss and a degradation of the Quality …

Effective Thermal Conductivity Of Tri-Isotropic (Triso) Fuel Compacts, Charles P. Folsom

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Next Generation Nuclear Plant (NGNP) program objective is to develop a new type of nuclear reactor that produces process heat instead of electricity. The process heat can be used in the production of hydrogen and many other industrial processes. As part of the NGNP program a new type of nuclear fuel is being developed. The fuel is a composite construction of specially coated fuel particles and graphite pressed together in a cylindrical compact.

Thermal conductivity is an important thermophysical property of the fuel that needs to be measured. Knowledge of the thermal conductivity of the fuel will provide accurate …

Computational Fluid Dynamics Analysis Of Butterfly Valve Performance Factors, Adam Del Toro

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Butterfly valves are commonly used to control fluid flow inside of piping systems. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As a butterfly valve is rotated open, fluid is able to more readily flow past the valve. A butterfly valve’s design is important to understand and is commonly characterized by its own performance factors. How a butterfly valve will perform, while in operation at different opening angles and under different types of flow, is critical information for individuals planning and installing piping systems involving the valve. …

Modeling And Measuring The Characteristics Of An Inductively Coupled Plasma Antenna For A Micro-Propulsion System, Sonya Mary Christensen

Boise State University Theses and Dissertations

An ion thruster for satellites on the order of 10-50 kg in mass is currently under development. The thruster uses an Inductively Coupled Plasma (ICP) generated by a flat spiral antenna fabricated using the Low Temperature Co-Fired Ceramic (LTCC) materials system. The antenna operating frequency range (600 MHz to 1 GHz) in LTCC (ε_r=7.8) results in a wavelength on the same order of magnitude as the total length of conductor in the antenna. This condition provides some interesting antenna electric and magnetic field characteristics. The antenna has been modeled using COMSOL Multiphysics® Simulation Software. By changing the geometry …

Investigation Of The Current Transmission Hysteresis In Electron Hop Funnels, Marcus Pearlman

Boise State University Theses and Dissertations

To integrate field emitter arrays (FEAs) into microwave vacuum electron devices, the use of insulating funnels, called electron hop funnels, is proposed. Electrons are emitted into the wide end of the funnel, and utilizing secondary electron emission to sustain current, the electrons "hop" up the funnel walls. Eventually the electrons exit the funnel as a denser and more uniform electron beam. To pull the electrons up the funnel, an electrode, called the hop electrode, is placed around the exit of the funnel to generate an electric field between the funnel exit and the electron source. The current transmitted through the …