Engineering Commons^™

A Protocol Suite For Wireless Personal Area Networks, Karl E. Persson

University of Kentucky Doctoral Dissertations

A Wireless Personal Area Network (WPAN) is an ad hoc network that consists of devices that surround an individual or an object. Bluetooth^® technology is especially suitable for formation of WPANs due to the pervasiveness of devices with Bluetooth^® chipsets, its operation in the unlicensed Industrial, Scientific, Medical (ISM) frequency band, and its interference resilience. Bluetooth^® technology has great potential to become the de facto standard for communication between heterogeneous devices in WPANs.

The piconet, which is the basic Bluetooth^® networking unit, utilizes a Master/Slave (MS) configuration that permits only a single master and up to …

Micro-Fabricated Hydrogen Sensors Operating At Elevated Temperatures, Chi Lu

University of Kentucky Doctoral Dissertations

In this dissertation, three types of microfabricated solid-state sensors had been designed and developed on silicon wafers, aiming to detect hydrogen gas at elevated temperatures. Based on the material properties and sensing mechanisms, they were operated at 140°C, 500°C, and 300°C. The MOS-capacitor device working at 140°C utilized nickel instead of the widely-used expensive palladium, and the performance remained excellent. For very-high temperature sensing (500°C), the conductivity of the thermally oxidized TiO₂ thin film based on the anodic aluminum oxide (AAO) substrate changed 25 times in response to 5 ppm H₂ and the response transient times were just …

Regeneration Of Damaged Growth Plate Using Igf-I Plasmid-Releasing Porous Plga Scaffolds, Nirmal Ravi

University of Kentucky Doctoral Dissertations

Growth plate injuries account for 15-30% of long bone fractures in children. About 10% of these result in significant growth disturbances due to formation of a boney bar. If not treated correctly, this can lead to life-lasting consequences of limb length inequalities and angular deformities. Current treatments for growth plate injuries include removal of boney bar and insertion of fat, silicone, bone cement, etc.. This treatment y is inadequate, leaving almost half of these patients with continued deformities. This dissertation reports characterization of a DNA–containing porous poly(lactic-co-glycolic acid) (PLGA) scaffold system, chondrogenesis using insulin-like growth factor I (IGF-I) plasmid-releasing scaffolds …

Three-Dimensional Free Surface Non-Hydrostatic Modeling Of Plunging Water With Turbulence And Air Entrained Transport, Tien Mun Yee

University of Kentucky Doctoral Dissertations

The advance in computational fluid dynamics in recent years has provided the opportunity for many fluid dynamic problems to be analyzed numerically. One such problem concerns the modeling of plunging water into a still water body, often encountered in pump stations. Air bubbles introduced into the system by the plunging jet can be a significant problem, especially when consumed into operating pumps. The classical approach to investigate the hydrodynamics of plunging jet in pump stations is by physical model studies. This approach is time consuming, tedious and costly. The availability of computational power today, along with appropriate numerical techniques, allows …

Analytical Strip Method To Antisymmetric Laminated Plates, Liecheng Sun

University of Kentucky Doctoral Dissertations

An Analytical Strip Method (ASM) for the analysis of stiffened and non-stiffened antisymmetric laminated composite plates is derived by considering the bending-extension coupling effect for bending, free vibration and buckling. A system of three equations of equilibrium, governing the general response of arbitrarily laminated composite plates, is reduced to a single eighth order partial differential equation in terms of a displacement function. The displacement function is solved in a single series form to determine the displacement, fundamental frequency, and buckling load of antisymmetric cross-ply and angle-ply laminated composite plates. The solution is applicable to rectangular plates with two opposite edges …

Utilizing Mixed Surfactants For Simultaneous Pore Templating And Active Site Formation In Metal Oxides, Mohammed Shahidur Rahman

University of Kentucky Doctoral Dissertations

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous metal oxides, but they typically impart poor long-range order when used as pore templates. Improved order and control over the functional site density may be achieved by mixing them with a cationic surfactant. To confirm this hypothesis, we investigate the lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of the functional nonionic surfactant n-dodecyl β-D-maltoside (C₁₂G₂) and cationic cetyltrimethylammonium bromide (C₁₆TAB). A ternary phase diagram of the C₁₆TAB-C₁₂G_{2 …}

Vortex Model Of Open Channel Flows With Gravel Beds, Brian James Belcher

University of Kentucky Doctoral Dissertations

Turbulent structures are known to be important physical processes in gravel-bed rivers. A number of limitations exist that prohibit the advancement and prediction of turbulence structures for optimization of civil infrastructure, biological habitats and sediment transport in gravel-bed rivers. This includes measurement limitations that prohibit characterization of size and strength of turbulent structures in the riverine environment for different case studies as well as traditional numerical modeling limitations that prohibit modeling and prediction of turbulent structure for heterogeneous beds under high Reynolds number flows using the Navier-Stokes equations. While these limitations exist, researchers have developed various theories for the structure …

Applications Of Computational Fluid Dynamics To Planetary Atmospheres, Xiaolong Deng

University of Kentucky Doctoral Dissertations

Computational Fluid Dynamics (CFD) has been applied to many areas. As one of the most important fluids, the atmosphere is closely related to people’s life. Studying the atmospheres on other planets can help people understand the Earth’s atmosphere and the climate and weather phenomena in it. Because of the complexity of a planetary atmosphere and the limitation of observations, applying CFD to the study of planetary atmospheres is becoming more and more popular. This kind of CFD simulations will also help people design the mission to the extra planets.

In this dissertation, through CFD simulations, we studied the three important …

Production Sequencing And Stability Analysis Of A Just-In-Time System With Sequence Dependent Setups, John Thomas Henninger

University of Kentucky Doctoral Dissertations

Just-In-Time (JIT) production systems is a popular area for researchers but real-world issues such as sequence dependent setups are often overlooked. This research investigates an approach for determining stability and an approach for mixed product sequencing in production systems with sequence dependent setups and buffer thresholds which signal replenishment of a given buffer. Production systems in this research operate under JIT pull production principles by producing only when demand exists and idle when no demand exists.

In the first approach, an iterative method is presented to determine stability for a multi-product production system that operates with replenishment signals and may …

Microstructural Evolution And Physical Behavior Of Palladium And Osmium-Ruthenium Noble Metal Films, Wen-Chung Li

University of Kentucky Doctoral Dissertations

Nanostructured noble metals exhibit novel physical, mechanical and chemical behavior, and hold promise for applications such as gas sensing and electron emission. A strong emphasis was placed on the processing and characterization of these materials, in the form of nanoporous or nanocrystalline thin films. Palladium-based and osmium-ruthenium alloys were investigated in this dissertation research and will be presented as follows:

(1) Preparation and Characterization of Nanoporous Metal Thin Films

(2) Characterization of Osmium-Ruthenium Coatings

Nanoporous palladium (np-Pd) thin films were prepared by dealloying co-sputtered palladium-nickel precursor alloys. Nanoporous structures were created with 3-D interconnected ligaments and open pores. Size of …

Visualization And Characterization Of Ultrasonic Cavitating Atomizer And Other Automotive Paint Sprayers Using Infrared Thermography, Nelson Kudzo Akafuah

University of Kentucky Doctoral Dissertations

The disintegration of a liquid jet emerging from a nozzle has been under investigation for several decades. A direct consequence of the liquid jet disintegration process is droplet formation. The breakup of a liquid jet into discrete droplets can be brought about by the use of a diverse forcing mechanism. Cavitation has been thought to assist the atomization process. Previous experimental studies, however, have dealt with cavitation as a secondary phenomenon assisting the primary atomization mechanism. In this dissertation, the role of the energy created by the collapse of cavitation bubbles, together with the liquid pressure perturbation is explicitly configured …

Investigation Of Surface Fine Grained Laminae, Streambed, And Streambank Processes Using A Watershed Scale Hydrologic And Sediment Transport Model, Joseph Paul Russo

University of Kentucky Doctoral Dissertations

Sediment transport at the watershed scale in the Bluegrass Region of Kentucky is dominated by surface fine grained laminae, streambed, and streambank erosion; high instream sediment storage; and surface erosion processes. All these processes can be impacted by agricultural, urban, and suburban land-uses as well as hydrologic forcing. Understanding sediment transport processes at the watershed scale is a need for budgeting and controlling sediment pollution, and watershed modeling enables investigation of the cumulative effect of sediment processes and the parameters controlling these processes upon the entire sediment budget for a watershed. Sediment transport is being modeled by coupling the hydrologic …