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Articles 1 - 30 of 33
Full-Text Articles in Engineering
Embedded Piezoelectric Fiber Composite Sensors For Applications In Composite Structures, Hari Prasad Konka
Embedded Piezoelectric Fiber Composite Sensors For Applications In Composite Structures, Hari Prasad Konka
LSU Doctoral Dissertations
Health monitoring of the composite structures is an important issue that must be addressed. Embedded sensors could be an effective way to monitor the health of composite structures continuously and which could also avoid the catastrophic failures of composite structures. Piezoelectric-fiber-composite sensors (PFCS) made from micro-sized Lead Zirconate Titanate (PZT) fibers have great advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCS as an embedded sensor will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composites. This work presents a critical study on using PFCS as an effective embedded sensor within …
Bio-Implantable Microdevices And Structures For Functional Electrical Stimulation Applications, Naga Srinivas Korivi
Bio-Implantable Microdevices And Structures For Functional Electrical Stimulation Applications, Naga Srinivas Korivi
LSU Doctoral Dissertations
This dissertation describes the development of microstructures and devices for applications in functional electrical stimulation. A nerve cuff electrode design has been developed for applications in neural electrical stimulation and recording, which addresses limitations with existing cuff electrodes. The developed clip-on micro-cuff electrode design consists of a naturally closed cuff with inner diameter in the micro-scale or above. A novel pinch-hinge feature allows a user to easily open the cuff and place it on target nerve tissue for stimulation or recording purposes. Upon release of the pinch-hinge, the cuff assumes its normally closed nature. The device conducts and reads electrical …
Catalytic Process For The Conversion Of Synthesis Gas To Ethanol For Use As An Alternative Fuel, Nitin Kumar
Catalytic Process For The Conversion Of Synthesis Gas To Ethanol For Use As An Alternative Fuel, Nitin Kumar
LSU Doctoral Dissertations
Higher alcohols are increasing as a proportion of the transportation fuel market, and can be used as neat fuels, or as blends with conventional fuels. For a number of reasons, these C2+-alcohols will be of interest in the foreseeable future. Large-scale production of higher alcohols will likely be carried out via syngas, which can be produced from a number of feedstocks, including coal, natural gas and biomass. Rhodium-based catalysts have been found to be the most active/selective for higher alcohols. However, the literature shows that the yields of C2+-alcohols that can be achieved with current catalysts, even the most active/selective, …
Fabrication And Property Study Of Plasma Sprayed Alumina Coatings And Magnetron Sputtered Multilayers, Ranran Liu
Fabrication And Property Study Of Plasma Sprayed Alumina Coatings And Magnetron Sputtered Multilayers, Ranran Liu
LSU Doctoral Dissertations
In this study, air or atmospheric plasma spraying (APS), one of thermal spraying processes, was used to produce alumina coatings and single splats. Nanoindentation technique was used to measure the mechanical properties, such as hardness and elastic modulus, of APS alumina coatings and single splats. The detailed procedures to calculate elastic modulus and hardness, and testing parameters for nanoindentation have been provided. This study revealed that the phase combination of α-Al2O3 and γ-Al2O3 played an important role in the scattering distribution of nanoindentation results on APS alumina coatings. In addition, nanoindentation technique was used to predict the phase information of …
Polymer Based Microfabrication And Its Applications In Optical Mems And Biomems, Guocheng Shao
Polymer Based Microfabrication And Its Applications In Optical Mems And Biomems, Guocheng Shao
LSU Doctoral Dissertations
Due to its ease of fabrication, low cost and great variety of functionalities, polymer has become an important material in microfabrication. MEMS devices with polymer as the structure material have found applications in various fields, especially in BioMEMS and optical MEMS. In this dissertation, three polymer based microfabricated devices/components have been developed and tested. Various polymer based fabrication techniques, such as high aspect ratio SU-8 photolithography, three dimensional polydimethylsiloxane (PDMS) soft lithography, multi-layer soft lithography and PDMS double casting technique have been developed/studied and employed in the device fabrication process. The main contribution of this dissertation includes: (1) Developed two …
Damage Detection And Identification In Fiber Reinforced Plastic Structural Members And Field Bridges Using Acoustic Emission Technique, Archana Nair
LSU Doctoral Dissertations
With the increased use of fiber reinforced polymer (FRP) based structural systems for rehabilitation of existing and construction of new bridges there is a requirement for identification of critical components of these structural systems and the determination of critical damage thresholds in them. Of the many available non-destructive techniques (NDT), acoustic emission (AE) monitoring had been identified as one of the most popular techniques applicable for damage discrimination in composites. The current study aimed at using patterns in AE data for the identification of damage modes exhibited by composite structural systems. The extensive experimental program involved testing of two structural …
On The Thermodynamics Of Degradation, Mehdi Amir Darehbidi
On The Thermodynamics Of Degradation, Mehdi Amir Darehbidi
LSU Doctoral Dissertations
All materials when subjected to fatigue loading are prone to failure if the number of cycles exceeds a certain level. Prediction of the number of cycles to failure is, therefore, of utmost importance in nearly all engineering applications. The existing methods for evaluating the fatigue life are tedious, expensive, and extremely time consuming as fatigue often takes many thousands to millions of cycles until failure occurs. Therefore, methods that can readily estimate the number of cycles to failure are highly desirable. In this work, innovative solutions to fatigue problems are presented and their practical significance is discussed. The premise of …
Thermodynamic Approach To Fatigue Failure Analysis In Metals And Composite Materials, Mehdi Naderi Abadi
Thermodynamic Approach To Fatigue Failure Analysis In Metals And Composite Materials, Mehdi Naderi Abadi
LSU Doctoral Dissertations
Fatigue is a dissipative process and must obey the laws of thermodynamics. In general, it can be hypothesized that the degradation of machinery components is a consequence of irreversible thermodynamic processes that disorder a component, and that degradation is a time dependent phenomenon with increasing disorder. This suggests that entropy —a fundamental parameter in thermodynamics that characterizes disorder— offers a natural measure of component degradation. The majority of the existing methods for prediction of fatigue are limited to the study of a single fatigue mode, i.e., bending or torsion or tension-compression. Further, the variability in the duty cycle in a …
In-Wheel Motors: Express Comparative Method For Pmbl Motors, Pavani Gottipati
In-Wheel Motors: Express Comparative Method For Pmbl Motors, Pavani Gottipati
LSU Doctoral Dissertations
One of the challenges facing the electric vehicle industry today is the selection and design of a suitable in-wheel motor. Permanent Magnet Brushless (PMBL) motor is a good choice for the in-wheel motor because of its lossless excitation, improved efficiency, reduced weight and low maintenance. The PMBL motors can be further classified as Axial-Flux Twin-Rotor (AFTR) and Radial-Flux Twin-Rotor (RFTR) machines.
The objective of this dissertation is to develop a fast method for the selection of appropriate in-wheel motor depending on wheel size. To achieve this, torque equations are developed for a conventional single-rotor cylindrical, twin-rotor axial-flux and twin-rotor radial-flux …
Efficient And Robust Signal Detection Algorithms For The Communication Applications, Lu Lu
Efficient And Robust Signal Detection Algorithms For The Communication Applications, Lu Lu
LSU Doctoral Dissertations
Signal detection and estimation has been prevalent in signal processing and communications for many years. The relevant studies deal with the processing of information-bearing signals for the purpose of information extraction. Nevertheless, new robust and efficient signal detection and estimation techniques are still in demand since there emerge more and more practical applications which rely on them. In this dissertation work, we proposed several novel signal detection schemes for wireless communications applications, such as source localization algorithm, spectrum sensing method, and normality test. The associated theories and practice in robustness, computational complexity, and overall system performance evaluation are also provided.
Characterization Of Foam Flow In Pipes Using Two Flow Regime Concept, Rahul Narayanrao Gajbhiye
Characterization Of Foam Flow In Pipes Using Two Flow Regime Concept, Rahul Narayanrao Gajbhiye
LSU Doctoral Dissertations
The objective of this study is to investigate the characteristics of foam flow behavior in pipes in a wide range of experimental conditions, including two pipe materials (stainless steel and nylon pipes with about 0.36 - 0.38 inch in inner diameter and 12 ft in length), three surfactant formulations (Cedepal FA-406, Stepanform-1050, and Aquet-944), and three surfactant concentrations (0.1, 0.5, and 5 wt%). The concept of “two foam-flow regimes”, consisting of high-quality regime and low-quality regime, is at the heart of interpreting the experimental data. The experimental results in horizontal pipes showed the presence of two distinct high-quality and low-quality …
Decoupling User Interface Design Using Libraries Of Reusable Components, Rajesh Sankaran
Decoupling User Interface Design Using Libraries Of Reusable Components, Rajesh Sankaran
LSU Doctoral Dissertations
The integration of electronic and mechanical hardware, software and interaction design presents a challenging design space for researchers developing physical user interfaces and interactive artifacts. Currently in the academic research community, physical user interfaces and interactive artifacts are predominantly designed and prototyped either as one-off instances from the ground up, or using functionally rich hardware toolkits and prototyping systems. During this prototyping phase, undertaking an integral design of the interface or interactive artifact’s electronic hardware is frequently constraining due to the tight couplings between the different design realms and the typical need for iterations as the design matures. Several current …
Small Footprint High Flow Rate Microdevice For Rare Target Cell Capture, Taehyun Park
Small Footprint High Flow Rate Microdevice For Rare Target Cell Capture, Taehyun Park
LSU Doctoral Dissertations
A novel high flow rate cell capture design was introduced to overcome the limitations of the current technologies or methods for rare target cell capture. Even though the rare target cell capture using BioMEMS technology has great potential for cancer diagnosis, previous rare cell capture research could not overcome the limitations of low flow rate or low recovery rate. Rare cell research requires precise sample preparation for accurate results. A new method of preparation for a single or a precise number of target cell was introduced. Current sample preparation methods which are not suitable for rare cell research, such as …
Droplet Motion On Miniaturized Ratchets, Jeong Tae Ok
Droplet Motion On Miniaturized Ratchets, Jeong Tae Ok
LSU Doctoral Dissertations
The main objective of this study is to evaluate the feasibility of using miniaturized asymmetric structures to move liquid droplets and understand the driving mechanism. We developed the fabrication process for large area topological ratchets with the period ranging from millimeter down to sub-micrometer using micromachining techniques. Non-wetting superhydrophobic surfaces were successfully fabricated using soft UV or thermal nanoimprint lithography, reactive ion etching by oxygen plasma, and chemical surface modification by fluorinated silane vapor deposition. An accurate and reproducible experimental setup equipped with high speed camera and automatic injection system was established. Image processing tools allowed us to obtain various …
Catalytic Hydrogenation Of Co To Higher Alcohols, Nachal Devi Subramanian
Catalytic Hydrogenation Of Co To Higher Alcohols, Nachal Devi Subramanian
LSU Doctoral Dissertations
The interest in converting synthesis gas to alcohols and oxygenated fuel additives via CO hydrogenation is growing rapidly due to the increasing rise in oil prices. Among the potential end products, ethanol is desirable since it serves as a clean alternative fuel, a gasoline blend, and a hydrogen carrier to supply fuel cells. The high cost and limited availability of the most active/selective Rh-based catalysts has led to the development of base metal catalysts such as modified Cu-based catalysts. Literature suggests that a combination of Co (or Mn) with Cu can facilitate higher alcohol formation by a non-dissociative adsorption of …
Computational Modeling Of Geogrid Reinforced Soil Foundation And Geogrid Reinforced Base In Flexible Pavement, Jie Gu
LSU Doctoral Dissertations
The objectives of this study are to investigate and evaluate the benefits of inclusion of geogrids in two types of geosynthetic reinforced soil/aggregate structures—e.g. reinforced soil foundations (RSF) and reinforced base aggregate in flexible pavements, thus shedding the light on the design of these reinforced structures. Two different finite element models were developed using ABAQUS software. The first model was used to investigate the bearing capacity and settlement of RSF and to perform parametric study on the effect of different design parameters on the performance of RSF. The second model was used to analyze the performance of geogrid reinforced bases …
Molecular Dynamics Simulation Studies Of Surface-Stress Effects In Metallic Nanostructures, Jijun Lao
Molecular Dynamics Simulation Studies Of Surface-Stress Effects In Metallic Nanostructures, Jijun Lao
LSU Doctoral Dissertations
Using molecular dynamics (MD) simulations we investigate the surface-stress-induced structural transformations and pseudoelastic behavior in palladium (Pd) crystalline nanowires. For a <100> initial crystal orientation our studies indicate that the surface stress can cause Pd nanowires to spontaneously undergo structural changes with characteristics that are determined by the wire cross-sectional area. Specifically, when the cross-sectional area is below 2.18nm x 2.18nm the wire changes spontaneously its crystal structure from the initial fcc structure to a body-centered-tetragonal (bct) structure. In wires of larger cross-sectional area (i.e., 2.57nm x 2.57nm) the structural transformation is achieved via a spontaneous lattice reorientation leading to an …
Surface Functionalization Of Crystalline Silicon Substrates, Sri Sai Vegunta
Surface Functionalization Of Crystalline Silicon Substrates, Sri Sai Vegunta
LSU Doctoral Dissertations
In this work, various chemical and electrochemical methods were demonstrated to attach application-specific organic monolayers to crystalline silicon substrates. In one study, alkyl monolayers were anodically electrografted or thermally grafted onto planar (100) silicon substrates using Grignard precursors. The results show electrografted methyl monolayers provide a stable Si-C termination, resisting oxidation on (100) surfaces for approximately 55 days in air. The alkyl termination could provide a potential alternative to defective native oxides and kinetically unstable hydride surfaces. A mechanism involving two electron transfers per grafting event was established for both the thermal and electrochemical routes. In another study, unsaturated organic …
A Biomimic Self-Healing Shape Memory Polymer Based Syntactic Foam For Smart Structural Composites, Jones Nji
A Biomimic Self-Healing Shape Memory Polymer Based Syntactic Foam For Smart Structural Composites, Jones Nji
LSU Doctoral Dissertations
This study explored the development of a new self-healing Polystyrene Shape Memory Polymer (PSMP) based syntactic foam for service life extension in structural polymeric composites. The objective was to self-heal structural-length scale damage in an autonomous, efficient, timely and repeatable manner at the molecular-length scale. Self-healing is achieved through a novel two step close-then-heal (CTH) self-healing scheme, designed to mimic the natural biological process of wound healing in humans. A new methodology to fabricate three-dimensional (3-D) fiber reinforced shape memory polymer syntactic foam for structural applications was developed. The effect of impact energy on the ability for the 3-D fiber …
Automated Semantic Understanding Of Human Emotions In Writing And Speech, Ricardo A. Calix
Automated Semantic Understanding Of Human Emotions In Writing And Speech, Ricardo A. Calix
LSU Doctoral Dissertations
Affective Human Computer Interaction (A-HCI) will be critical for the success of new technologies that will prevalent in the 21st century. If cell phones and the internet are any indication, there will be continued rapid development of automated assistive systems that help humans to live better, more productive lives. These will not be just passive systems such as cell phones, but active assistive systems like robot aides in use in hospitals, homes, entertainment room, office, and other work environments. Such systems will need to be able to properly deduce human emotional state before they determine how to best interact with …
Analyzing And Predicting Processor Vulnerability To Soft Errors Using Statistical Techniques, Lide Duan
Analyzing And Predicting Processor Vulnerability To Soft Errors Using Statistical Techniques, Lide Duan
LSU Doctoral Dissertations
The shrinking processor feature size, lower threshold voltage and increasing on-chip transistor density make current processors highly vulnerable to soft errors. Architectural Vulnerability Factor (AVF) reflects the probability that a raw soft error eventually causes a visible error in the program output, indicating the processor’s susceptibility to soft errors at architectural level. The awareness of the AVF, both at the early design stage and during program runtime, is greatly useful for designing reliable processors. However, measuring the AVF is extremely costly, resulting in large overheads in hardware, computation, and power. The situation is further exacerbated in a multi-threaded processor environment …
Integrating Multiple Clusters For Compute-Intensive Applications, Zhifeng Yun
Integrating Multiple Clusters For Compute-Intensive Applications, Zhifeng Yun
LSU Doctoral Dissertations
Multicluster grids provide one promising solution to satisfying the growing computational demands of compute-intensive applications. However, it is challenging to seamlessly integrate all participating clusters in different domains into a single virtual computational platform. In order to fully utilize the capabilities of multicluster grids, computer scientists need to deal with the issue of joining together participating autonomic systems practically and efficiently to execute grid-enabled applications. Driven by several compute-intensive applications, this theses develops a multicluster grid management toolkit called Pelecanus to bridge the gap between user's needs and the system's heterogeneity. Application scientists will be able to conduct very large-scale …
Reducing Complexity Of Processor Front Ends With Static Analysis And Selective Preloading, Santhosh Verma
Reducing Complexity Of Processor Front Ends With Static Analysis And Selective Preloading, Santhosh Verma
LSU Doctoral Dissertations
General purpose processors were once designed with the major goal of maximizing performance. As power consumption has grown, with the advent of multi-core processors and the rising importance of embedded and mobile devices, the importance of designing efficient and low cost architectures has increased. This dissertation focuses on reducing the complexity of the front end of the processor, mainly branch predictors. Branch predictors have also been designed with a focus on improving prediction accuracy so that performance is maximized. To accomplish this, the predictors proposed in the literature and used in real systems have become increasingly complex and larger, a …
Characterization Of Novel Akermanite:Poly-E-Caprolactone Scaffolds For Bone Tissue Engineering Aapplications Combined With Human Adipose-Derived Stem Cells, Andre S. Zanetti
Characterization Of Novel Akermanite:Poly-E-Caprolactone Scaffolds For Bone Tissue Engineering Aapplications Combined With Human Adipose-Derived Stem Cells, Andre S. Zanetti
LSU Doctoral Dissertations
The development of porous materials useful as scaffolds for the sustained three-dimensional (3D) growth of human adipose-derived stem cells (hASC) is of particular interest to facilitate healing after musculoskeletal injuries. In this study, a composite porous material obtained by blending akermanite with poly-e-caprolactone (PCL) is proposed as novel alternative to bone tissue regeneration. The objectives of this study are (1) to characterize the akermanite:PCL scaffold properties; (2) to investigate the in vitro osteogenic potential of hASC loaded to optimal akermanite:PCL scaffolds; (3) to assess the metabolic activity and osteogenesis of hASC loaded to optimal akermanite:PCL scaffolds post-thawing using optimal cryopreservation …
Silicon Nanowire Anode For Lithium-Ion Batteries: Fabrication, Characterization And Solid Electrolyte Interphase, Wanli Xu
LSU Doctoral Dissertations
Depletion of fossil fuels and concerns over CO2 emission have driven the development of electric vehicles (EVs) with high-energy efficiencies and low emissions. Lithium-ion rechargeable batteries, compared to lead acid, nickel cadmium, nickel metal hydroxide, and other popular rechargeable batteries, are considered as the most promising candidates for EVs for their high operating voltage and high energy density. Silicon nanowires are considered as lithium-ion battery anodes for their ultra high capacity at 4200 mAh·g-1 (10× higher than conventional graphite anode), as well as stress accommodation for reversible lithiation and delithiation. Silicon nanowires were fabricated via metal assisted electroless etching, and …
Photochemical Reaction Products Of Polycyclic Aromatic Hydrocarbons Adsorbed At An Air-Water Interface, Franz Stefan Ehrenhauser
Photochemical Reaction Products Of Polycyclic Aromatic Hydrocarbons Adsorbed At An Air-Water Interface, Franz Stefan Ehrenhauser
LSU Doctoral Dissertations
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous pollutants resulting from incomplete combustion and hence normally unavoidable. The kinetic aspects of the environmental degradation process have received considerable attention; however, not much is known about the degradation products themselves. Aqueous solutions of naphthalene, acenaphthene, 9H-fluorene, phenanthrene and pyrene were subjected to UVB light in a bulk-phase and a thin-film reactor to assess the identity of the formed photodegradation products. To aide in the challenging analysis of these mixtures, a novel analytical technique based on high performance liquid chromatography (HPLC) coupled to UV diode-array detection and dopant-assisted atmospheric pressure photoionization mass …
Advanced Linear Identification Techniques For Signal Processing And Digital Video Broadcasting, Xiaoyu Feng
Advanced Linear Identification Techniques For Signal Processing And Digital Video Broadcasting, Xiaoyu Feng
LSU Doctoral Dissertations
Linear identification technique is to linearly embed a piece of unique information into digital media data for the purpose of satisfying specific demands such as identification, annotation, and copyright, etc. We need to consider the quantity and the quality of identification data to be embedded as well as the corresponding interference to the original subject signal. However, there exist no generalized computationally-efficient optimization techniques for linear identification up to now. Therefore, in this dissertation work, we try to theoretically investigate the advanced linear identification techniques and combat the tradeoff problems between the quality of the embedded identification data and the …
Analytical Design Method For Cold Production Of Heavy Oil With Bottom Water Using Bilateral Sink Wells, Wenting Qin
Analytical Design Method For Cold Production Of Heavy Oil With Bottom Water Using Bilateral Sink Wells, Wenting Qin
LSU Doctoral Dissertations
Few heavy oil reservoirs with strong bottom water drives have been developed successfully because of severe water coning. Water coning tends to cause low ultimate recovery, low well productivity, and high water production. Although thermal and gravity-assisted methods might improve recovery in oil reservoirs, such methods are widely perceived as either economically unfavorable or technologically infeasible. This study proposes a new, cold production technique, called Bilateral Water Sink (BWS), to meet those challenges. The BWS method suppresses water cresting by producing oil and water simultaneously from separate, horizontal wells completed in the oil and water zones; the oil and water …
Development Of A Time-Dependent, Audio-Visual, Stated Choice Method Of Data Collection For Hurricane Evacuation Behavior, Ravindra Gudishala
Development Of A Time-Dependent, Audio-Visual, Stated Choice Method Of Data Collection For Hurricane Evacuation Behavior, Ravindra Gudishala
LSU Doctoral Dissertations
Revealed preference is the traditional method to collect hurricane evacuation behavior data. However, revealed preference surveys, as they are currently administered, have the disadvantage that they are unable to collect time-sensitive and policy-sensitive data needed to test evacuation policies. In contrast, data collected from a time-dependent, stated-choice survey will allow researchers to collect not only time-sensitive and policy-sensitive data but also information that will allow testing potential new evacuation policies. However, no research has been conducted to establish the methodology of such a survey. To fill the gap, this study was conducted to develop a new time-dependent, audio-visual, stated-choice method …
Phase Noise In Cmos Phase-Locked Loop Circuits, Yang Liu
Phase Noise In Cmos Phase-Locked Loop Circuits, Yang Liu
LSU Doctoral Dissertations
Phase-locked loops (PLLs) have been widely used in mixed-signal integrated circuits. With the continuously increasing demand of market for high speed, low noise devices, PLLs are playing a more important role in communications. In this dissertation, phase noise and jitter performances are investigated in different types of PLL designs. Hot carrier and negative bias temperature instability effects are analyzed from simulations and experiments. Phase noise of a CMOS phase-locked loop as a frequency synthesizer circuit is modeled from the superposition of noises from its building blocks: voltage-controlled oscillator, frequency divider, phase-frequency detector, loop filter and auxiliary input reference clock. A …