Mechanical Engineering Commons^™

Capillarity And Two-Phase Fluid Transport In Media With Fibers Of Dissimilar Properties, Thomas M. Bucher Jr.

Theses and Dissertations

Capillarity is a physical phenomenon that acts as a driving force in the displacement of one fluid by another within a porous medium. This mechanism operates on the micro and nanoscale, and is responsible for countless observable events. This can include applications such as absorption in various hygiene products, self-cleaning surfaces such as water beading up and rolling off a specially-coated windshield, anti-icing, and water management in fuel cells, among many others.

The most significant research into capillarity has occurred within the last century or so. Traditional formulations for fluid absorption include the Lucas–Washburn model for porous media, which is …

Cfd Assessment Of Respiratory Drug Delivery Efficiency In Adults And Improvements Using Controlled Condensational Growth, Ross L. Walenga

Theses and Dissertations

Pharmaceutical aerosols provide a number of advantages for treating respiratory diseases that include targeting high doses directly to the lungs and reducing exposure of other organs to the medication, which improve effectiveness and minimize side effects. However, difficulties associated with aerosolized drug delivery to the lungs include drug losses in delivery devices and in the extrathoracic region of human upper airways. Intersubject variability of extrathoracic and thoracic drug deposition is a key issue as well and should be minimized. Improvements to respiratory drug delivery efficiency have been recently proposed by Dr. P. Worth Longest and Dr. Michael Hindle through the …

Molecular Dynamics Simulations Of Pure Polytetrafluoroethylene Near Glassy Transition Temperature For Different Molecular Weights, Rawan Al-Nsour

Theses and Dissertations

Fluoropolymers are employed in countless end-user applications across several industries. One such fluoropolymer is polytetrafluoroethylene. This research is concerned with studying and understanding the thermal behavior of polytetrafluoroethylene. Such understanding is critical to predict its behavior in diverse service environments as the polymer ages and for allowing bottom up design of improved polymers for specific applications.

While a plethora of experiments have investigated the thermal properties of polytetrafluoroethylene, examining these properties using molecular dynamics simulations remains in its infancy. In particular, the current body of molecular dynamics research on polytetrafluoroethylene has primarily focused on studying polytetrafluoroethylene phases, its physical nature, …

Magnetic Nanoparticles For Thermally Anoparticles Enhanced Heavy Oil Recovery, Hazem Elshorbagy Elshorbagy

Theses

A novel method of delivering thermal energy efficiently to reservoirs for heavy oil production is described in this study. The method uses magnetic nanoparticles that generate heat locally when exposed to a high frequency magnetic field oscillation via hysteresis losses. This concept is currently used in medical research to thermally kill cancerous cells. Electromagnetic heating is a n alternative method to heat heavy oil reservoirs without using water or steam. Using magnetic nanoparticles with electromagnetic heating would greatly reduce the energy requirement and would allow efficient propagation of heat into deeper regions beyond wellbore locality that are otherwise difficult to …

Influence Of Magnetic Fields On The Evaporation And Combustion Of A Single Droplet, Domingo Elias

LSU Master's Theses

The reliance on combustion as the primary source of energy will continue in the US for the next thirty years [1]. Experiments suggest that the use of magnetic fields can be one tool in the many-sided approach to the problem of environmental protection and energy conservation in the US. For instance, it is estimated that an increase in efficiency of 2% in spray combustion can save the US economy billions of dollars [2]. In this thesis I report on improving the quality of combustion through the use of magnetic fields. (1)I investigated the effects of magnetic fields on the evaporation …

Innovative Heat Transfer Augmentation Techniques In Mechanical Face Seal, Nian Xiao

LSU Doctoral Dissertations

Excessive heat generated at the face seal contact interface has been recognized as one of main causes of failure of mechanical seals. In the past few decades various efforts have been attempted to remove heat from the contact interface uniformly in order to reduce the interfacial temperature, eliminate thermally-induced failure, and thus increase the life of a mechanical seal. Two innovative heat transfer augmentation techniques - surface texturing and built-in phase change device - have been developed in our laboratory to effectively enhance the heat transfer in mechanical face seal. Surface texturing can increase the surface area, change the near …

Composition Control Of Spinel Lithium Manganese Oxide For High Voltage, High Energy Lithium Ion Batteries, Hilary Eikhuemelo

LSU Master's Theses

In the quest for renewable source of energy, a remarkable step made was in the introduction of the battery system. The lithium ion battery was revolutionary in this regard particularly for its light weight and high energy density. There has been significant progress in the development of this battery system since the present form was introduced in the 1990s. There is currently a global dependence on the use of lithium ion battery in diverse applications such as in the electronics, communications and automobiles. Unfortunately, the energy obtainable from the lithium ion battery continuously falls behind the energy demand. This setback …

Energy Dissipation And Entropy Generation During The Fatigue Degradation: Application To Health Monitoring Of Composites, Ali Kahirdeh

LSU Doctoral Dissertations

In this dissertation, an experimental approach for characterizing energy dissipation and degradation evolution in a woven Epoxy/Glass (G10/FR4) laminate subjected to fully reversed bending fatigue test is presented. Infrared thermography and acoustic emission are utilized to characterize the degradation progression. The results show similar evolutionary response indicating the presence of three degradation stages. The effect of the surface cooling on the fatigue life of the laminates is investigated both experimentally and analytically. The results show that the life of the laminate is highly dependent on the temperature and that surface cooling can significantly increase the fatigue life of the laminate. …

Novel Nanostructured Titania And Titania Nanocomposites For Photovoltaics And Photocatalysis, Xinning Luan

LSU Doctoral Dissertations

With the consumption of energy continually increasing around the world and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. Demand for solar energy has experienced exponential increase over the last decade. Nanostructured TiO2 has attracted significant attention due to its nontoxicity, low cost and wide applications in photovoltaics and photocatalysis. This research is focused on novel synthesis and surface modification of TiO2 nanotube arrays for applications in advanced dye-sensitized solar cells (DSSCs) and efficient photocatalysis. The first part of this work entails fast synthesis …

Energy And Thermodynamically Based Approaches For Analysis Of Damage In Contact Problems, Afshin Babaie Aghdam

LSU Doctoral Dissertations

A novel methodology for analysis of damage in contact problems in presented. Two important categories of contact damage are studied, namely crack nucleation and adhesive wear. The proposed methodology is primarily based on the laws of energy and thermodynamics, and as such offers great advantages by unifying the analysis of damage in a variety of contact configurations. Crack nucleation is the first damage type analyzed. For this purpose, the line-contact fretting configuration is chosen. A thermodynamically-based continuum damage mechanics (CDM) approach is employed. Intense stress gradients in the contact region are found to be highly influential in the crack nucleation …

Utilization Of Carbon Nanofibers Grown On Glass Microballoons (Nmbs) In Point-Of-Care Diagnostic Devices, Emmanuel Gikunoo

LSU Doctoral Dissertations

The use of point-of-care (POC) diagnostic systems holds great promise for the early detection of various diseases. However, detection limits for commercially available POC systems have not been able to meet the lower cutoffs offered by the specialized laboratory testing methods. Research into the use of carbon nanofibers (CNFs) grown on glass microballoons in POC devices was studied. The growth of several millions of the CNFs on each microballoon (NMBs) presented a large surface area with high probability of capturing minute concentrations of biospecies. Functionalization of the NMBs with the carboxyl group needed for biospecies conjugation was achieved by air …

Early Prediction Of Fracture In Bodies Bounded By Random Rough Surfaces, Hector Medina

Theses and Dissertations

Under certain loading conditions, surfaces topography coupled with materials degree of brittleness can significantly compromise the mechanical performance of structures. The foregoing remains valid even if roughness is intentionally introduced for engineering reasons. In either case, stress can concentrate. The case of the stress concentration in surfaces having randomly distributed pits is a problem that, although being very practical, yet it remains unsolved. The complexity of a random configuration renders difficult the problem of analytically finding relationships between surface parameters and markers indicative of mechanical failure. Another difficulty is the reproducibility of replicates of specimens possessing random rough surfaces, for …

A Study Of Walkway Safety And Evaluation Of Tribological Test Equipment, Henry Thomas Baker

UNF Graduate Theses and Dissertations

A walkway tribometer measures the coefficient of friction between flooring material and a test foot. The value of the coefficient of friction is an indicator as to whether the flooring surface is slippery and has a propensity to cause slip and falls. This study determined that one style of tribometer, an XL Tribometer, mimics the heel-to-floor interaction of the human heel strike. High speed video footage revealed that the test foot strikes the surface and rotates so that full engagement occurs before sliding thus mimicking the affect of a human ankle. The test foot accelerates forward as would be expected …

Educational Programmes For Spatial Information Sciences In The Technological University Of Dublin, William Prendergast, Eamonn Murphy, Audrey Martin, Avril Behan

Conference papers

The ever increasing spatial information needs of society, the rapid development of new surveying technologies, and the global demand for appropriately qualified surveyors, have triggered a radical re-evaluation of geomatics education worldwide. Significant enhancements have been made to the educational programmes in the spatial information science discipline in the Technological University of Dublin’s (DIT) during the last decade including the provision of a BSc in Geomatics and various masters’ programmes to cater for the increasingly specialised needs of the Geographic Information sector in Ireland.

Standoff Methods For The Detection Of Threat Agents: A Review Of Several Promising Laser-Based Techniques, J. Bruce Johnson, Susan D. Allen, Jonathan Merten, Lewis Johnson, Daniel Pinkham, Scott W. Reeve

Publications

Detection of explosives, explosive precursors, or other threat agents presents a number of technological challenges for optical sensing methods. Certainly detecting trace levels of threat agents against a complex background is chief among these challenges; however, the related issues of multiple target distances (from standoff to proximity) and sampling time scales (from passive mines to rapid rate of march convoy protection) for different applications make it unlikely that a single technique will be ideal for all sensing situations. A number of methods for spanning the range of optical sensor technologies exist which, when integrated, could produce a fused sensor system …

Role Of Surface Chemistry In Nanoscale Electrokinetic Transport, Secuk Atalay

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation work presents the efforts to study the electrofluidics phenomena, with a focus on surface charge properties in nanoscale systems with the potential applications in imaging, energy conversion, ultrafiltration, DNA analysis/sequencing, DNA and protein transport, drug delivery, biological/chemical agent detection and micro/nano chip sensors.

Since the ion or molecular or particle transport and also liquid confinement in nano-structures are strongly dominated by the surface charge properties, in regards of the fundamental understanding of electrofluidics at nanoscale, we have used surface charge chemistry properties based on 2-pK charging mechanism. Using this mechanism, we theoretically and analytically showed the surface charge …

System-Level Simulation Of A Solar Power Tower Plant With Thermocline Thermal Energy Storage, Scott M. Flueckiger, Brian D. Iverson, Suresh V. Garimella, James E. Pacheco

Faculty Publications

A thermocline tank is a low-cost thermal energy storage subsystem for concentrating solar power plants that typically utilizes molten salt and quartzite rock as storage media. Longterm thermal stability of the storage concept remains a design concern. A new model is developed to provide comprehensive simulation of thermocline tank operation at low computational cost, addressing deficiencies with previous models in the literature. The proposed model is then incorporated into a system-level model of a 100 MWe power tower plant to investigate storage performance during long-term operation. Solar irradiance data, taken from measurements for the year 1977 near Barstow, CA, are …

Review Of High-Temperature Central Receiver Designs For Concentrating Solar Power, Brian D. Iverson, Clifford K. Ho

Faculty Publications

This paper reviews central receiver designs for concentrating solar power applications with high-temperature power cycles. Desired features include low-cost and durable materials that can withstand high concentration ratios (~1000 suns), heat-transfer fluids that can withstand temperatures > 650°C, high solar absorptance, and low radiative and convective heat losses leading to a thermal efficiency > 90%. Different receiver designs are categorized and evaluated in this paper: (1) gas receivers, (2) liquid receivers, and (3) solid particle receivers. For each design, the following information is provided: general principle and review of previous modeling and testing activities, expected outlet temperature and thermal efficiency, benefits, perceived …

Sensitivity Analysis Of Wind Plant Performance To Key Turbine Design Parameters: A Systems Engineering Approach, Katherine Dykes, Andrew Ning, Ryan King, Peter Graf, George Scott, Paul Veers

Faculty Publications

This paper introduces the development of a new software framework for research, design, and development of wind energy systems which is meant to 1) represent a full wind plant including all physical and nonphysical assets and associated costs up to the point of grid interconnection, 2) allow use of interchangeable models of varying fidelity for different aspects of the system, and 3) support system level multidisciplinary analyses and optimizations. This paper describes the design of the overall software capability and applies it to a global sensitivity analysis of wind turbine and plant performance and cost. The analysis was performed using …

Simultaneous Monitoring Of Singlet And Triplet Exciton Variations In Solid Organic Semiconductors Driven By An External Static Magnetic Field, Baofu Ding, Kamal Alameh

Research outputs 2014 to 2021

The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet …