Engineering Commons^™

Guaranteed Rendezvous For Cognitive Radio Networks Based On Cycle Length, Li Gou

Dissertations, Master's Theses and Master's Reports

Rendezvous is a fundamental process establishing a communication link on common channel between a pair of nodes in the cognitive radio networks. How to reach rendezvous efficiently and effectively is still an open problem. In this work, we propose a guaranteed cycle lengths based rendezvous (CLR) algorithm for cognitive radio networks. When the cycle lengths of the two nodes are coprime, the rendezvous is guaranteed within one rendezvous period considering the time skew between the two nodes. When T_i and T_j are not coprime, i.e., T_i=T_j, the deadlock checking and node IDs are combined …

Nanotextured Titanium Surfaces For Implants: Manufacturing And Packaging Aspects, Sachin Bhosle

Dissertations, Master's Theses and Master's Reports

It has been shown that nanotexturing the surface of otherwise smooth titanium orthopedic materials increases osteoblast proliferation in vitro, and the bone-implant contact area and pullout force in vivo. However, this prior work has not focused on the requirements for scale-up to industrial processes. This dissertation reports on titanium surface modifications by electrochemical anodization using a benign NH₄F electrolyte, and a hybrid electrolyte also containing AgF, rather than hazardous hydrofluoric acid used elsewhere. Nanotube fabrication of Ti6Al4V foils, rods, thermal plasma sprayed commercial implants, and laser and e-beam melted powder materials was demonstrated.

It was found …

Ecological Sanitation Opportunities In Rural Panamá: Effectiveness And Social Implications Of Intrinsic Ammonia-Based Treatment For Pathogen Inactivation And Incorporation Of Ferrocement Technology, David Kierys

Dissertations, Master's Theses and Master's Reports

The Millennium Development Goals (MDGs) the United Nations created more than 15 years ago established a global developmental framework that set a precedent for many governmental agencies and non-governmental organizations (NGOs.). With the deadline having come and gone many of the objectives set out in the original eight MDGs have come to fruition (Joint Monitoring Program, 2015). One exemplary achievement by the global community, specifically to the Water, Sanitation and Hygiene (WASH) sector was providing 91 percent of the world’s population with access to improved sources of drinking water (UNICEF/WHO, 2015). But, as the Joint Monitoring Program (JMP) – the …

Nonlinear Dielectric Behavior Of Field-Induced Antiferroelectric/Paraelectric-To-Ferroelectric Phase Transition For High Energy Density Capacitor Application, Mingyang Li

Dissertations, Master's Theses and Master's Reports

Electric field-induced antiferroelectric(AFE)/paraelectric(PE)-to-ferroelectric(FE) phase transitions are investigated for the associated nonlinear dielectric behavior, which could offer high dielectric capacity. The phenomenon in monolithic materials has been computed for Kittel antiferroelectric and BaTiO₃ model systems using the Landau-Ginzburg-Devonshire theory. The general switching curves give values of the polarization as a function of external electric field. A similar computation is performed for particle-filled polymer-matrix composites where an internal depolarization field is considered. The polarization-electric field response changes with different depolarization factors, which demonstrate the shape and alignment of the dielectric particles embedded in polymer-matrix are key factors for the composite to …

High Performance Multiview Video Coding, Caoyang Jiang

Dissertations, Master's Theses and Master's Reports

Following the standardization of the latest video coding standard High Efficiency Video Coding in 2013, in 2014, multiview extension of HEVC (MV-HEVC) was published and brought significantly better compression performance of around 50% for multiview and 3D videos compared to multiple independent single-view HEVC coding. However, the extremely high computational complexity of MV-HEVC demands significant optimization of the encoder. To tackle this problem, this work investigates the possibilities of using modern parallel computing platforms and tools such as single-instruction-multiple-data (SIMD) instructions, multi-core CPU, massively parallel GPU, and computer cluster to significantly enhance the MVC encoder performance. The aforementioned computing tools …

Computational Studies On Biomechanics Of Concussion And On Efficacy Of Football Helmets, David Labyak

Dissertations, Master's Theses and Master's Reports

Football helmets have been used for many years to prevent head injuries to players. Over the years, the helmet design has evolved from a crude leather head covering to the more recent form fitting helmets that are seen today. The one design feature that has been common in the majority of all helmets is a hard polycarbonate shell with a foam cushion padding. The main goal of the padding layer was to reduce the amount of linear acceleration during an impact event. The one feature that has been overlooked is how stiff the padding is in rotation.

The purpose of …

Utilizing Reprap Style 3d Printers For The Manufacturing Of Composite Heat Exchangers, John Laureto

Dissertations, Master's Theses and Master's Reports

The low cost 3D printing market is currently dominated by the application of RepRap (self-replicating rapid-prototyper) variants. Presented in this document are practical utilizations of RepRap technology. Developed are innovative processes to manufacture composite materials systems for thermal management solutions.

First, a laser polymer welder system is validated by quantifying maximum peak load and weld width of linear low density polyethylene (LLDPE) lap welds as a function of linear energy density. The development of practical engineering data, in this application, is critical to producing mechanically durable welds. Developed laser and printer parameter sets allow for manufacturing of LLDPE multi-layered heat …

Design Of Robust Hydrogel Based On Mussel-Inspired Chemistry, Yuan Liu

Dissertations, Master's Theses and Master's Reports

The structure of catechol is found in mussel adhesive proteins and contributed to both wet-resistant adhesion and cohesive curing of these proteins. A synthetic nano-silicate, Laponite was incorporated into catechol-containing hydrogels and the hydrogel network-bound catechol formed strong reversible interfacial interaction with Laponite. The contribution of incorporated catechol-Laponite reversible interfacial interactions to the mechanics of hydrogels constructed by different strategies was studied. In the first strategy, Laponite and catechol were introduced into the double network hydrogel (DN) via the free radical co-polymerization of a catechol-containing monomer, backbone monomer, and crosslinker. The introduction of catechol-Laponite interactions significantly improved the compressive strength …

A Study Of High Temperature Heat Pipes And The Impact Of Magnetic Field On The Flow Of Liquid Metal, Udit Sharma

Dissertations, Master's Theses and Master's Reports

A study of high temperature heat pipe was conducted to understand its characteristics. A review of working fluid, temperature, wick structure, problems, operational limit and applications was done. Alkali metal were concluded as the most viable candidate for the working fluid.

The impact of three parameters namely magnetic field, heat flux and temperature was analyzed on the performance of HTHP (High Temperature Heat Pipe). The presence of magnetic field had the most considerable impact on reducing the pumping limit of the heat pipe while the temperature had almost negligible effect. Magnetic field results in the pressure drop and adversely affect …

Advanced Uses For Carbon Nanotubes: A Spherical Sound Source And Hot-Films As Microphones, Micaela M. Thiery

Dissertations, Master's Theses and Master's Reports

Super-aligned carbon nanotube (CNT) thin-film is used to create thermophones. The thermal properties of CNT film allow it to rapidly heat and cool when supplied AC power producing temperature and pressure gradients and, therefore, audible sound. The advantages of CNT thermophones include eliminating all moving components of traditional speakers and reducing the weight of the speaker itself by using CNT film, which is nearly weightless. Additionally, the flexibility of CNT film provides the unique opportunity to construct loudspeakers of various sizes and geometries. In this work, a spherical CNT thermophone is designed, manufactured, and tested for directivity with the overall …

Evaluation Of Thermal Stability Of Ausferrite In Austempered Ductile Iron Using Differential Scanning Calorimetry, Karl Warsinski

Dissertations, Master's Theses and Master's Reports

Austempered Ductile Iron (ADI) is prone to changes in microstructure and mechanical properties when exposed to elevated service temperatures. Differential Scanning Calorimetry has been used to evaluate the stabilizing effects of copper, nickel, molybdenum, and cobalt on the ausferrite structure. Previous studies have conflated the effects of various alloy additions, and little effort has been made to systematically catalog the effects of individual elements. The focus of the current research has been to identify alloying elements that more strongly stabilize the ausferrite structure in order to improve service life of ADI at elevated temperatures. Nickel has been shown to have …

Analysis Of Aeroelastic Effects On The 3-Dimensional Interference Of Wind-Turbine Rotors, Anurag Rajan

Dissertations, Master's Theses and Master's Reports

Greater penetration of wind energy demands better utilization of available wind. This has led to a formidable increase in the rotor diameter over the past few years. Bigger rotors call for lighter, more flexible blades to reduce loads and improve fatigue life. As a result, future blades will deform substantially more than the relatively stiff blades of the past. More efficient use of wind power also calls for incorporating advanced active and passive control strategies and increasing the range of velocities over which wind energy is captured. Hence an improvement in the quality of numerical simulations capable of capturing the …

Accuracy Assessment Of 3d Point Clouds Generated By Photogrammetry From Different Distances, Zhongming An

Dissertations, Master's Theses and Master's Reports

Photogrammetry is playing more important role in many industries today, and thanks to Structure-from-Motion, 3D point clouds and 3D meshes can be produced and be used as a resource for surveying and documentation.

In this project, the accuracies of Structure-from-Motion generated point clouds from pictures taken from different distances are assessed to determine if the distance has a significant impact on the accuracy and what kind of pattern the accuracies will show if there is any. Due to space limit, an improvised turntable was used in order to mimic the condition where camera moves around the object. Multiple images were …

Control Of A Powered Ankle-Foot Prosthesis: From Perception To Impedance Modulation, Guilherme Aramizo Ribeiro

Dissertations, Master's Theses and Master's Reports

Active ankle prostheses controllers are demonstrating gaining smart features to improve the safety and comfort offor users. The perception of user intention to modulate the ankle dynamics is a well-known example of such feature. But not much work focused on the perception of the environment, nor how the environment should be included in the mechanical design and control of the prosthesisprostheses. The proposed work aims to improve the feasibility of integrate the environment perception integration intoto the prostheses controllersler, and to define the desired ankle dynamics, as mechanical impedance, duringof the human walk on different environmental settings. As a preliminary …

Life Cycle Assessment (Lca) Of Ore Transportation Route Alternatives For Eagle Mine, Soumith Kumar Oduru

Dissertations, Master's Theses and Master's Reports

Transportation sector at large is a major consumer of fossil fuels and constitutes more than a quarter of the global greenhouse gas emissions. When making infrastructure route and mode choice decisions for new freight-oriented projects, it is important that environmental and emissions considerations are included as an integral part of the selection process. Emissions from freight transportation projects related to mining and natural resource industry are especially critical, as they involve high volumes and tonnages often in pristine environments. The most logical time for emissions analysis is during modal and route analysis that are often conducted in the planning stage …

Molecular Modeling Of Aerospace Polymer Matrices Including Carbon Nanotube-Enhanced Epoxy, Matthew Radue

Dissertations, Master's Theses and Master's Reports

Carbon fiber (CF) composites are increasingly replacing metals used in major structural parts of aircraft, spacecraft, and automobiles. The current limitations of carbon fiber composites are addressed through computational material design by modeling the salient aerospace matrix materials. Molecular Dynamics (MD) models of epoxies with and without carbon nanotube (CNT) reinforcement and models of pure bismaleimides (BMIs) were developed to elucidate structure-property relationships for improved selection and tailoring of matrices.

The influence of monomer functionality on the mechanical properties of epoxies is studied using the Reax Force Field (ReaxFF). From deformation simulations, the Young’s modulus, yield point, and Poisson’s ratio …

Model-Based Control Of An Rcci Engine, Akshat Abhay Raut

Dissertations, Master's Theses and Master's Reports

Reactivity controlled compression ignition (RCCI) is a combustion strategy that offers high fuel conversion efficiency and near zero emissions of NOx and soot which can help in improving fuel economy in mobile and stationary internal combustion engine (ICE) applications and at the same time lower engine-out emissions. One of the main challenges associated with RCCI combustion is the difficulty in simultaneously controlling combustion phasing, engine load, and cyclic variability during transient engine operations.

This thesis focuses on developing model based controllers for cycle-to-cycle combustion phasing and load control during transient operations. A control oriented model (COM) is developed by using …

Multiscale Modeling: Thermal Conductivity Of Graphene/Cycloaliphatic Epoxy Composites, Sorayot Chinkanjanarot

Dissertations, Master's Theses and Master's Reports

The thermal property of epoxy as the binder in the Carbon Fiber (CF) composites, especially thermal conductivity is important to achieve the advance technology and to improve the performance of materials. Multiscale modeling including molecular dynamic (MD) modeling and micromechanical modeling is used to study the properties of neat Cycloaliphatic Epoxies (CE) and Graphene nanoplatelet (GNP)/CE with and without covalent functionalization.

The thermal properties (glass-transition temperature, thermal expansion coefficient, and thermal conductivity) and mechanical properties of CE system are investigated by MD modeling using OPLS-All Atom force field. A unique crosslinking technique is developed to achieve the cured CE models …

Planning For Intermittent Water Supply In Small Gravity-Fed Distribution Systems: Case Study In Rural Panama, Frank B. Dubasik

Dissertations, Master's Theses and Master's Reports

Intermittent water supply (IWS) is defined as a piped water distribution system that operates in an intermittent fashion, i.e. less than 24 hours per day. Piped water distribution systems are designed to operate with continuous water supply (CWS), meaning the system is operated continuously and maintains positive pressures in the distribution network. Operating a system in an intermittent fashion can cause inequality of access in a water distribution system. It may also result in lower water quality and wear and tear on the system.

In the community of Espavé, Panamá a new water system was installed and brought online in …

Modeling Mass And Thermal Transport In Thin Porous Media Of Pem Fuel Cells, Vinaykumar Konduru

Dissertations, Master's Theses and Master's Reports

Water transport in the Porous Transport Layer (PTL) plays an important role in the efficient operation of polymer electrolyte membrane fuel cells (PEMFC). Excessive water content as well as dry operating conditions are unfavorable for efficient and reliable operation of the fuel cell. The effect of thermal conductivity and porosity on water management are investigated by simulating two-phase ow in the PTL of the fuel cell using a network model. In the model, the PTL consists of a pore-phase and a solid-phase. Different models of the PTLs are generated using independent Weibull distributions for the pore-phase and the solid-phase. The …

Social, Economic, And Technical Feasibility Of Ablution Gray Water Reuse In Tong, Ghana, Adrienne Masterton

Dissertations, Master's Theses and Master's Reports

Water insecurity is a constant stressor for millions of people around the globe. The potential of gray water as an alternative water source has gained increasing attention in the literature. In water-scarce Muslim communities, the practice of ablution – the rinsing of the face, hands, and feet before prayer – offers a unique opportunity for gray water reuse.

This report investigates the feasibility of treating and reusing ablution gray water (AGW) with respect to religious acceptability, economic measures, and physical parameters in Tong, a rural community of Muslim subsistence farmers in northern Ghana. Investigatory tools included: household water use surveys, …

Minimum Time Control Of Paralleled Boost Converters, Shishir Patel

Dissertations, Master's Theses and Master's Reports

Demand for electrification is booming in both, traditional and upcoming generations of technological advancements. One of the constituent blocks of these electrified systems is Power conversion. Power conversion systems are often constructed by paralleling multiple power converter blocks for high performance and reliability of overall system. An advanced control technique is developed with an aim to optimize system states of heterogeneous power converters within minimum time while maintaining feasible stress level on individual power converter blocks. Practical implementation of real-time controller and performance improvement strategies are addressed. Experimental results validating high performance control scheme, and sensitivity analysis of system states …

Development Of An Evaporation Sub-Model And Simulation Of Multiple Droplet Impingement In Volume Of Fluid Method, Sathya Prasad Potham

Dissertations, Master's Theses and Master's Reports

Droplet collision and impingement on a substrate are widely observed phenomenon in many applications like spray injection of Internal Combustion Engines. Existing Lagrangian models do not provide a comprehensive picture of the outcome of these events and may involve model constants requiring experimental data for validation. Physics based models like Volume of Fluid (VOF) method involve no parametric tuning and are more accurate. The aim of this thesis is to extend the basic VOF method with an evaporation sub-model including an additional vapor phase and implement this model in an open source Computational Fluid Dynamics (CFD) software, OpenFOAM. The new …

Assessment Of Annular Flow Boiling In The Context Of Computational Fluid Dynamics (Cfd) Simulations, Experiments, And Existing Correlations, Hrishikesh Prasad Ranga Prasad

Dissertations, Master's Theses and Master's Reports

The main objective of the current work is to achieve a better understanding – through modeling and simulation/programming activities – of annular flow-boiling and its applications based on a synthesis of Computational Fluid Dynamics (CFD) simulations, existing correlations, and experiments. A unique and rigorous 2-D CFD simulations technique was developed for annular flow-boiling to propose a correlation for convective component of Heat Transfer Coefficient (HTC) – defined here as flow-boiling in the absence of nucleation. To provide a context for the correlation structure of convective component of HTC, flow-physics details of annular flow-boiling and correlation structure (based on fundamental considerations) …

Design, Laboratory Testing, And Yield Line Analysis Of A Ferrocement Pit Latrine Slab, Larry Alan Schirmer Jr

Dissertations, Master's Theses and Master's Reports

Access to sanitation for rural and indigenous Panamanians is the vision of global efforts to improve their quality of life. As part of on-site work from the Peace Corps to change public perceptions about open defecation, the author designed and tested a new type of ferrocement latrine slab to reduce the amount of materials involved in building latrines and by extension the manual labor involved. In the course of this investigation, a sanitation based case study establishes the precedent for working with ferrocement in these areas, and the author explores the history and structural properties of ferrocement. In laboratory experiments, …

Polymer Waveguide Manufacturing And Printed Circuit Board Integration, Brandon Swatowski

Dissertations, Master's Theses and Master's Reports

In this age of ever increasing data rates in communication systems, optics are becoming more commonplace for long length (>10m) signal transmission in High Performance Computing (HPC) systems due to their bandwidth capabilities which are higher than their electrical counterparts. In these optical based communication systems, Vertical Cavity Surface Emitting Lasers (VCSELs) are the most commonly used communications lasing medium for multimode fiber applications. These lasers are active in the 850 nm region, with speeds commonly at 10 Gbps/channel. VCSEL vendors are now commercializing lasers at 25 Gbps/channel as well, with research groups actively pursuing rates beyond 40 Gbps/channel, …

Polyvinyl Alcohol (Pva) Fiber-Reinforced Rubber Concrete And Rubberized Self-Compacting Concrete, Jiaqing Wang

Dissertations, Master's Theses and Master's Reports

This study experimentally investigates the mechanical performance and durability of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete and the rubberized self-compacting concrete. The waste rubber particles were introduced as a partial replacement of fine aggregate in the plain concrete. In addition, the waste tire rubbers were pre-treated with alkali surface treatment method to enhance the performance. The PVA fibers were added to the concrete mixes to enhance the post-failure resistance and thus fracture energy. Rubberized fiber concrete samples were prepared with different fine aggregate replacement ratios and the optimum fiber content. At the same time, the rubber particles had been used …

Microstructural Evolution And Mechanical Properties Of Zn-Ti Alloys For Biodegradable Stent Applications, Zhiyong Yin

Dissertations, Master's Theses and Master's Reports

Stents made of biodegradable metallic materials are increasingly gaining interest within the biomaterials field because of their superior mechanical properties and biodegradation rates as compared to polymeric materials. Zinc and its alloys have been developed and investigated as possible candidates for biodegradable stent applications in the last five years. This study intended to formulate and characterize a new series of Zn-Ti alloys, with titanium additions of less than 1-3 wt%, with the primary objective to develop and select an alloy that meets benchmark values of mechanical properties for biodegradable stents. A series of Zn-Ti alloys was formulated through vacuum induction …

The Impact Of Water Injection On Spark Ignition Engine Performance Under High Load Operation, Jeremy Worm

Dissertations, Master's Theses and Master's Reports

An experimental effort has been completed in which water injection was investigated as a means of enabling increases in engine output and high load efficiency. Water was injected into the intake port of a direct fuel injected, 4-cylinder, boosted engine with dual independent variable valve timing. The water was shown to increase volumetric efficiency and decrease the onset of knock which in turn enable more optimal combustion phasing. Both of these affects resulted increases in load of up to 5.5% at the same manifold pressure as the baseline case. The advancement of combustion phasing, combined with elimination of fuel enrichment …

Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune

Dissertations, Master's Theses and Master's Reports

Two electrospray sources were developed to operate on an ionic liquid ferrofluid; one source was a pressure‑fed capillary electrospray source and the other was a novel electrospray source which used a magnetically‑induced instability to produce a peak from which an electric field could extract electrospray. Multiple characteristics of electrospray operation were examined for both sources using faraday plates/cups, a quartz crystal microbalance, a retarding potential analyzer, and a time-of-flight mass spectrometer. The ILFF electrosprays for a capillary source were shown to operate in a mixed ion/droplet regime. The mass flow of the electrospray beam was primarily transported by larger particles …